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Abstract submissions to News
Directions in Biology and Disease of Skeletal Muscle, April 23-26, Dallas,
Texas
Abstract Title: |
Gene Expression Profiling to Monitor Therapeutic and Adverse
Effects of Antisense Therapies for Duchenne Muscular Dystrophy |
Presenting/First Author: |
't Hoen, Peter A (Postdoc - Degree Year: 4) |
Department, Institution: |
Center for Human and Clinical Genetics, Leiden University Medical
Center |
Address: |
PO Box 9600 LEIDEN, 2300 RC Netherlands |
Phone/Fax: |
+31 71 5269421 / +31 71 5268285 |
Email: |
[email protected] |
Abstract Theme: |
Therapies |
Author(s): |
't Hoen, Peter A (Center for Human and Clinical Genetics, Leiden
University Medical Center, PO Box 9600, 2300 RC LEIDEN)
van der Wees, Caroline G (Center for Human and Clinical Genetics, Leiden
University Medical Center, PO Box 9600, 2300 RC LEIDEN)
Aartsma-Rus, Annemieke (Center for Human and Clinical Genetics, Leiden
University Medical Center, PO Box 9600, 2300 RC LEIDEN)
Goyenvalle, Aurélie (Genethon & CNRS UMR 8115, 1, rue de
l'Internationale, Evry, France)
Garcia, Luis (Genethon & CNRS UMR 8115, 1, rue de l'Internationale, Evry,
France)
van Ommen, Gertjan (Center for Human and Clinical Genetics, Leiden
University Medical Center, PO Box 9600, 2300 RC LEIDEN)
den Dunnen, Johan T (Center for Human and Clinical Genetics, Leiden
University Medical Center, PO Box 9600, 2300 RC LEIDEN)
van Deutekom, Judith C (Center for Human and Clinical Genetics, Leiden
University Medical Center, PO Box 9600, 2300 RC LEIDEN) |
Body of Abstract: |
We used expression profiling to monitor the efficacy and possible
adverse effects of antisense therapies for Duchenne muscular dystrophy (DMD).
Muscles from mdx mice were injected with antisense constructs that
restore the open reading frame in the Dmd gene. Polyethylenimine (PEI)-complexed
antisense oligonucleotides (AONs) were more effective than uncomplexed,
F127- or Optison-complexed AONs. In contrast to F127 and Optison, PEI
induced the expression of many immune genes, reflecting an aggravation
of the inflammation present in untreated mdx mice. The level of
transcript correction was too low to cause a significant shift towards
wild-type expression patterns. Injection with adenoassociated
virus-expressed antisense sequences resulted in much higher production
of dystrophin. Depending on the efficacy, the expression of genes known
to be elevated in muscular dystrophies, partly or completely returned to
wild-type expression levels. Reductions in inflammation and fibrosis
were among the most prominent changes observed. We conclude that
expression profiling is a powerful tool to monitor desired and adverse
effects of new therapeutic approaches in preclinical research and
clinical trials.
Funded by Prinses Beatrix Fonds. |
|
Abstract Title: |
Towards Clinical Studies on Antisense-mediated Exon Skipping in
Duchenne Muscular Dystrophy. |
Presenting/First Author: |
't Hoen, Peter-Bram A (Postdoc - Degree Year: ) |
Department, Institution: |
Center for Human and Clinical Genetics, Leiden University Medical
Center |
Address: |
Einthovenweg 20- Postbus 9600 Leiden, 2300 RC Netherlands |
Phone/Fax: |
+31-71-526 9421 / +31-71-526 8285 |
Email: |
[email protected] |
Abstract Theme: |
Therapies |
Author(s): |
't Hoen, Peter-Bram A (Center for Human and Clinical Genetics,
Leiden University Medical Center, Leiden, The Netherlands)
Heemskerk, Hans (Center for Human and Clinical Genetics, Leiden
University Medical Center, Leiden, The Netherlands)
de Winter, Christa (Center for Human and Clinical Genetics, Leiden
University Medical Center, Leiden, The Netherlands)
Verschuuren, Jan J (Department of Neurology, Leiden University Medical
Center, Leiden, The Netherlands)
van Kuik, Petra (Prosensa BV, Leiden, The Netherlands)
de Kimpe, Sjef (Prosensa BV, Leiden, The Netherlands)
Platenburg, Gerard J (Prosensa BV, Leiden, The Netherlands)
van Deutekom, Judith C (Center for Human and Clinical Genetics, Leiden
University Medical Center, Leiden, The Netherlands) |
Body of Abstract: |
For Duchenne muscular dystrophy (DMD), antisense oligonucleotides (AONs)have
demonstrated to be an efficient and relatively simple and safe
alternative to gene replacement approaches. By inducing specific exon
skipping, AONs allow restoration of the open reading frame of mutated
DMD transcripts and turn on the synthesis of internally truncated, but
largely functional dystrophins. In the first half of 2006, a clinical
study, based on intramuscular injections of an AON, will be undertaken
in a selected group of DMD patients, of which the set-up will be
discussed. To facilitate full-body treatment of DMD patients, we are now
focusing on the development of a safe and efficient systemic
AON-delivery method. Using the mdx mouse model, we compare efficacy,
persistence and biodistribution of an AON targeting the mutated exon 23.
We have obtained high exon 23 skipping and dystrophin levels (up to 45%)
in different muscles, including diaphragm and heart. We determined the p
hysiological stability of the AON in the different organs and tissues,
and noted a half life of 10 days in skeletal muscle. The overall
therapeutic effect was further demonstrated by decreased creatin kinase
levels and improved muscle performances in RotaRod studies. |
|
Abstract Title: |
The role of alpha-syntrophin in assembly of the neuromuscular
junction signaling scaffold |
Presenting/First Author: |
Adams, Marvin E (Faculty) |
Department, Institution: |
Physiology and Biophysics, University of Washington |
Address: |
1959 Pacific ST NE Seattle, WA 98195 United States |
Phone/Fax: |
206 543-9094 / 206 68500619 |
Email: |
[email protected] |
Abstract Theme: |
Sarcolemmal Excitability |
Author(s): |
Adams, Marvin E (University of Washington, Seattle, WA 98195)
Froehner, Stanley C (University of Washington, Seattle, WA 98195)
|
Body of Abstract: |
Dystrophin and its homologues utrophin and dystrobrevin are
concentrated at the postsynaptic neuromuscular junction (NMJ) where they
form scaffolding complexes with the adapter protein, alpha-syntrophin.
The NMJs of alpha-syntrophin null mice have reduced levels and abnormal
distribution of acetylcholine receptors(AChRs). These mice lack both
utrophin and neuronal nitric oxide synthase (nNOS) at the NMJ. We
generated transgenic mice that express alpha-syntrophin lacking the PDZ
domain or the first pleckstrin homology (PH) domain and tested if the
mutated alpha-syntrophin restores the NMJ scaffold in alpha-syntrophin
null mice. We find that the PDZ domain of syntrophin is required for
nNOS localization to the NMJ and for proper distribution of AChRs.
Likewise the AChRs remain abnormally distributed when only the PH domain
of alpha-syntrophin is missing. Surprisingly, nNOS localization at the
synapse (and sarcolemma) could not be restored by alpha-syntrophin mi
ssing the first PH domain despite the presence of a functional PDZ
domain. Utrophin localization to the NMJ did not require the PDZ or PH
domain. The domains of alpha-syntrophin play distinct roles in synapse
formation/maintenance at the NMJ. Supported by NIH and MDA. |
|
Abstract Title: |
Identification of the cofilin-2 gene, CFL2, as a probable sixth
gene for nemaline myopathy |
Presenting/First Author: |
Agrawal, Pankaj B (Faculty) |
Department, Institution: |
Medicine, Children's Hospital |
Address: |
300 Longwood Ave Boston, MA 02115 United States |
Phone/Fax: |
6179192153 / 6177300253 |
Email: |
[email protected] |
Abstract Theme: |
Molecular Basis of Muscle Dysfunction |
Author(s): |
Agrawal, Pankaj B (Children's Hospital and Harvard Medical School,
Boston)
Schweikert, Rebecca (Children's Hospital and Harvard Medical School,
Boston)
Darras, Basil T (Children's Hospital and Harvard Medical School, Boston)
Beggs, Alan H (Children's Hospital and Harvard Medical School, Boston)
|
Body of Abstract: |
Nemaline Myopathy (NM) is characterized by skeletal muscle weakness
and presence of nemaline bodies. Causative mutations have been described
in NEB, ACTA1, TPM2, TPM3, and TNNT1 genes. Cofilin-2 (CFL2) is a
candidate gene for NM as it encodes a thin filament protein involved in
actin regulation. We screened 132 unrelated NM cases and found a
homozygous missense CFL2 mutation in two siblings who had typical NM.
Microscopically, the proband’s muscle showed moderate numbers of
nemaline bodies. The proband and her affected sibling were homozygous
for c.103G>A mutation resulting in the Ala35Thr change. An unaffected
sibling and both parents, who are first cousins, were heterozygous. The
mutation was not seen in 282 controls including 91 from the same
geographical region. On comparing the expression of cofilin-2 in the
patient with that in age-matched normal skeletal muscle, the patient’s
muscle had dramatically lower amounts of cofilin-2 on immunofluorescence,
and 2-D SDS-PAGE with Western blot. Expression of both normal and mutant
cofilin-2 in E. coli demonstrated that the mutant protein was
considerably less soluble than the wild type, supporting that CFL2
likely represents a sixth gene responsible for NM. |
|
Abstract Title: |
Regulation of satellite cell growth and differentiation by
extracellular heparan sulfate 6-O endosulfatases |
Presenting/First Author: |
Ai, Xingbin (Faculty) |
Department, Institution: |
cell & Dev. Biol, Boston Biomedical Research Institute |
Address: |
64 Grove Street Watertown, MA 02476 United States |
Phone/Fax: |
6176587869 / 6179721759 |
Email: |
[email protected] |
Abstract Theme: |
Repair Mechanisms |
Author(s): |
Ai, Xingbin (Boston Biomedical Research Institute, Watertown, MA
02476)
Langsdorf, Ally (Boston Biomedical Research Institute, Watertown, MA
02476)
Emerson, Charles P (Boston Biomedical Research Institute, Watertown, MA
02476)
|
Body of Abstract: |
Satellite cells are quiescent “stem” cells in adult skeletal muscles
that can be activated upon injury to repair damaged muscle under
physiological and disease conditions. Although signals involved in the
growth and differentiation of satellite cells are known, the regulatory
mechanisms that coordinate the activities of these signals in intact and
regenerating muscles have not been characterized. Both intact and
injured muscles express a number of growth factors that require 6-O
sulfated heparan sulfate (HS) to form functional signaling complexes to
induce the proliferation and differentiation of satellite cells. We
recently have identified a novel family of HS endosulfatases (Sulfs)
that catalytically remove HS 6-O sulfates to repress growth factor
signaling. Mouse endosulfatase 1 (MSulf1) and MSulf2 are differentially
expressed by quiescent and activated satellite cells, but not by muscle
fibers. Loss of MSulfs leads to delayed myofiber differentiation and
prolo nged satellite cell proliferation in response to FGF2. We are
investigating roles of MSulf1 and MSulf2 in satellite cell growth and
differentiation using tissue culture model and cardiotoxin-induced acute
injury model. This work is supported by MDA. |
|
Abstract Title: |
Rigid spine muscular dystrophy caused by a homozygous mutation in
the 3’ UTR Selenocystein Insertion Sequence Element of Selenoprotein N |
Presenting/First Author: |
Allamand, Valérie (Faculty) |
Department, Institution: |
Institut de Myologie- GH Pitié-Salpétriè, INSERM U582 |
Address: |
47 Boulevard de l'Hôpital Paris Cedex 13, 75651 France |
Phone/Fax: |
+33 1 42 16 57 43 / +33 1 42 16 57 00 |
Email: |
[email protected] |
Abstract Theme: |
Congenital Muscular Dystrophy and Nuclear Membrane Diseases |
Author(s): |
Allamand, Valérie (INSERM U582, Institut de Myologie, IFR 14, Groupe
Hospitalier Pitié-Salpêtrière, Université Pierre et Marie Curie, Paris,
France)
Richard, Pascale (Assistance Publique-Hôpitaux de Paris, Groupe
Hospitalier Pitié-Salpêtrière, UF Cardiogénétique et Myogénétique,
Service de Biochimie B, Paris, France)
Lescure, Alain (CNRS-Université Louis Pasteur, UPR 9002, Institut de
Biologie Moléculaire et Cellulaire, Strasbourg, France)
Ferreiro, Ana (INSERM U582, Institut de Myologie, IFR 14, Groupe
Hospitalier Pitié-Salpêtrière, Université Pierre et Marie Curie, Paris,
France)
Krol, Alain (CNRS-Université Louis Pasteur, UPR 9002, Institut de
Biologie Moléculaire et Cellulaire, Strasbourg, France)
Pellegrini, Nadine (Hôpital Raymond Poincaré, Garches, France)
Urtizberea, Andoni J (Hôpital Raymond Poincaré, Garches, France)
Guicheney, Pascale (INSERM U582, Institut de Myologie, IFR 14, Groupe
Hospitalier Pitié-Salpêtrière, Université Pierre et Marie Curie, Paris,
France) |
Body of Abstract: |
Selenoprotein N (SelN) was the first selenoprotein shown to be
involved in a genetic disorder. The SEPN1-related myopathy regroups four
autosomal recessive disorders: Rigid Spine Muscular Dystrophy (RSMD1),
multiminicore disease, desmin-related myopathy with Mallory Body-like
inclusions and congenital fiber type disproportion.
Here we report the first mutation in the Selenocysteine Insertion
Sequence (SECIS) of SelN, in a patient presenting a classical although
rather mild form of RSMD1. In cultured fibroblasts mRNA and protein
levels were greatly decreased. We also demonstrated that this mutation
abolishes SECIS-binding protein 2 (SBP2) binding to SECIS in vitro,
thereby preventing cotranslational incorporation of selenocysteine and
SelN synthesis.
This is the first mutation identified in the “non-Watson-Crick” quartet
of the SECIS element, a hairpin structure located in the 3’ UTR allowing,
through interactions with trans-acting partners, the insertion of a
selenocysteine residue at the UGA codon. The identification of this
mutation reveals the structural basis for a novel mechanism leading to
SEPN1-related myopathy.
Supports: INSERM, AFM, GIS-Institut des Maladies Rares, Assistance
Publique-Hôpitaux de Paris. |
|
Abstract Title: |
Studies of sarcoglycan trafficking and localization in Drosophila |
Presenting/First Author: |
Allikian, Michael J (Faculty) |
Department, Institution: |
Medicine, University of Chicago |
Address: |
5841 S. Maryland, MC6088 Chicago, IL 60637 United States |
Phone/Fax: |
773 702-2684 / 773 702-2681 |
Email: |
[email protected] |
Abstract Theme: |
Molecular Basis of Muscle Dysfunction |
Author(s): |
Allikian, Michael J (University of Chicago, Chicago, IL 60637)
Bhabha, Gira (University of Chicago, Chicago, IL 60637)
McNally, Elizabeth M (University of Chicago, Chicago, IL 60637)
|
Body of Abstract: |
The dystrophin glycoprotein complex (DGC) is essential for plasma
membrane stability in skeletal muscle myofibers and cardiomyocytes.
Mutations in the genes encoding dystrophin and its associated proteins,
the sarcoglycans, lead to muscular dystrophy in humans and in mouse
models. Trafficking of the sarcoglycan complex to the sarcolemma is a
critical step for skeletal myofiber and cardiomyocyte maintenance.
However, little is known about the molecular mediators of this process.
To identify proteins necessary for sarcoglycan localization and
interaction, we created transgenic Drosophila that express a properly
localized and labeled delta-sarcoglycan subunit. We subsequently carried
out a genetic screen using this transgenic fly line and identified two
different deficiencies that harbor genes necessary for proper
sarcoglycan processing and localization. These deficiencies, both on
chromosome 2, encompass many loci. One is comprised of 21 genes, the
other is su bstantially larger and contains 130 genes. For the smaller
region, lines were obtained that are mutant for each of the known genes
in the interval. For the larger deletion, we opted to examine lines that
had smaller deletions to narrow down the interval of interest. |
|
Abstract Title: |
Viral expression of IGF-IB drives proliferation at the expense of
hypertrophy in mdx skeletal muscle |
Presenting/First Author: |
Barton, Elisabeth R (Faculty) |
Department, Institution: |
Anatomy and Cell Biology, University of Pennsylvania School of
Dental Medicine |
Address: |
240 S. 40th Street Philadelphia, PA 19104 United States |
Phone/Fax: |
215-573-0887 / 215-573-2324 |
Email: |
[email protected] |
Abstract Theme: |
Regulation of Muscle Mass |
Author(s): |
Barton, Elisabeth R (University of Pennsylvania School of Dental
Medicine, Philadelphia, PA 19104)
Feng, Jessie (University of Pennsylvania School of Dental Medicine,
Philadelphia, PA 19104)
Ma, Rong-Ine (University of Pennsylvania School of Dental Medicine,
Philadelphia, PA 19104)
Tian, Zuozhen (University of Pennsylvania School of Dental Medicine,
Philadelphia, PA 19104)
|
Body of Abstract: |
Alternative splicing of the insulin-like growth factor I gene gives
rise to at least 4 peptide classes, leading to the production of an
identical IGF-I protein but different E-peptide extensions. We have
recently shown that viral delivery of murine IGF-IA and IGF-IB produce
hypertrophy in young growing animals, yet only IGF-IA can increase
muscle mass in mature animals. This raises the possibility that the
IGF-IB target is only available during the growth phase, and could be
activated satellite cells. We tested this hypothesis using viral
delivery of either IGF-IA or IGF-IB in mature mdx mice (which have
activated satellite cells due to ongoing degeneration/regeneration) and
in mature wildtype mice. Hypertrophy was observed in mdx and wildtype
muscles treated with IGF-IA. In contrast, muscles treated with IGF-IB
produced no hypertrophy, and IGF-IB treated mdx muscles had large
regions of unresolved proliferation. These results are consistent with
IGF-IB mediated p roliferation via satellite cell targets. It suggests
that transient expression of IGF-IB in concert with damage might boost
proliferation of these cells to enhance repair. However, constant
expression of this isoform may be detrimental to completion of repair in
muscle. |
|
Abstract Title: |
Designing oligonucleotides containing CpG modifications to
recruit specific repair mechanisms leads to improved gene correction
efficiency in skeletal muscles of mdx mice. |
Presenting/First Author: |
Bertoni, Carmen (Faculty) |
Department, Institution: |
Neurology, Stanford University |
Address: |
300 Pasteur drive Room A-343 Stanford, CA 94304 United States |
Phone/Fax: |
(650) 493 5000 Ext.62073 / (50)858 3935 |
Email: |
[email protected] |
Abstract Theme: |
Therapies |
Author(s): |
Bertoni, Carmen (Stanford University, Stanford, CA 94304)
Rustagi, Arjun (Stanford University, Stanford, CA 94304)
Rando, Thomas A (Stanford University, Stanford, CA 94304)
|
Body of Abstract: |
Gene editing mediated by single stranded oligonucleotides (ssODNs)
represents an appealing option to DMD since it has the potential to
treat both single point mutations as well as deletions that cause a
frame shift of the dystrophin mRNA. We have focused on the development
of new vectors capable of activating specific repair mechanisms to
direct the correction of mutations in genomic DNA. The methyl binding
protein 4 (MBD4) takes an active role in DNA repair and is highly
expressed in muscles. MBD4 contains a specific glycosilase capable of
recognizing a T to G transversion at CpG sites and direct the conversion
of the thymine into methylcytosine. CpG modifications were introduced on
the mutating base of the targeting oligonucleotide in the attempt to
mimic a deamination of methylcytosine which results in the activation of
MBD4. The ability of these modified ssODNs to increase gene repair was
studied in mdx muscle cells in vitro and in vivo. The level of dystrophi
n protein expression was significantly increased by the use of these
modified ssODNs. Our studies demonstrated the specific recruitment of
the MBD4-mediated repair pathway. Correction of the dystrophin gene was
shown at the genomic level and was stable over time. |
|
Abstract Title: |
Improved Quality of Life and Reduced Health Care Needs for Boys
with Duchenne Muscular Dystrophy treated with Long-term Deflazacort |
Presenting/First Author: |
Biggar, Doug W (Faculty) |
Department, Institution: |
Pediatrics, Bloorview Kids Rehab |
Address: |
150 Kilgour Road Toronto, ON M4G 1R8 Canada |
Phone/Fax: |
416-424-3813 / 416-424-3840 |
Email: |
[email protected] |
Abstract Theme: |
Therapies |
Author(s): |
Biggar, Doug W (Bloorview Kids Rehab, Toronto, Ontario, Canada. M4G
IR8)
Harris, Vivien A (Bloorview Kids Rehab, Toronto, Ontario, Canada. M4G
IR8)
Eliasoph, Laila R (Bloorview Kids Rehab, Toronto, Ontario, Canada. M4G
IR8)
Gonzales, Angela N (Bloorview Kids Rehab, Toronto, Ontario, Canada. M4G
IR8)
MacLeod, Kathleen A (Bloorview Kids Rehab, Toronto, Ontario, Canada. M4G
IR8)
|
Body of Abstract: |
ABSTRACT: We compare the clinical outcomes of 74 boys, 10 to 18
years of age with DMD: 40 were treated (T) and 34 were not treated (NT)
with daily deflazacort. Boys-T were able to rise from supine to standing,
climb 4 stairs and walk 10 metres without aids, 3-5 years longer than
boys-NT. At 10 years, boys-T had significantly better pulmonary function
than boys-NT and at 15 years, 8 of 34 boys-NT required nocturnal
ventilation (T=0). Thirty of 34 boys-NT had a spinal curve greater than
20° compared to 4 of 40 boys-T. Most boys-NT required assistance with
feeding after spine surgery compared to none of the boys-T. At 18 years,
7 of 34 boys-NT had lost 25% or more of their body weight (T=0) and 4 of
those 7 boys required a gastric feeding tube. At 18 years, 20 of 34
boys-NT had cardiac left ventricular ejection fractions less than 45%
compared to 4 of 40 boys-T. Twelve of 34 boys-NT died in their second
decade (17.6 ± 1.7 years) primarily of cardio respiratory comp lications.
Two of 40 boys-T died at 13 and 18 years of age from cardiac failure.
The boys-T were significantly shorter, did not have excessive weight
gain and 22 of 40 had asymptomatic cataracts. Long bone fractures
occurred in 25% of boys in both the T and NT groups. We conclude that
long-term deflazacort treatment has a very significant impact on health,
quality of life and health care needs for boys with DMD and their
families, and is usually associated with few side effects. |
|
Abstract Title: |
Differential expression of iron metabolism proteins in normal
human skeletal and cardiac muscle |
Presenting/First Author: |
Boyer, Philip J (Faculty) |
Department, Institution: |
Pathology/Neuropath., Univ. of Texas Southwestern |
Address: |
5323 Harry Hines Blvd., Room H2.132 Dallas, TX 75390-9073 United
States |
Phone/Fax: |
214-648-7170 / 214-648-2077 |
Email: |
[email protected] |
Abstract Theme: |
Molecular Basis of Muscle Dysfunction |
Author(s): |
Boyer, Philip J (Univ. of Texas Southwestern, Dallas, TX 75390)
Dellinger, Bonnie B (Penn State Univ., Hersehy, PA 17033)
Simmons, Zachary (Penn State Univ., Hersehy, PA 17033)
Carey, Evan P (Univ. of Texas Southwestern, Dallas, TX 75390)
Piner0, Diego J (Penn State Univ., Hersehy, PA 17033)
Connor, James R (Penn State Univ., Hersehy, PA 17033)
|
Body of Abstract: |
This study characterizes the distribution of the various iron
metabolism proteins in striated muscle. Frozen sections from
histologically normal skeletal muscle biopsies (N=10) and hearts
obtained at autopsy (N=5) were evaluated by Perls' iron stain and by
immunohistochemistry using antibodies against divalent metal transporter
1 (DMT1), ferroportin 1 (FP1), transferrin, transferrin receptor, and
the hemochromatosis gene product (HFE). Type I and type II fibers were
distinguished using ATPase histochemistry and myosin heavy chain
immunohistochemistry. Iron was diffusely present in all myofibers.
Skeletal myofibers were labeled by all markers with differentially
strong expression of HFE and FP1 noted in type I and II fibers,
respectively. In cardiac muscle, strong expression of both HFE and FP1
was noted; distinct localization of DMT1 and HFE was present at
intercalated disks. The differential expression of HFE and FP1 in type I
and II myofibers likely reflects di fferent iron requirements.
Significant expression of HFE implies an important role for this protein
in iron metabolism in striated muscle and is likely relevant to the
accumulation of iron in cardiac muscle in hemochromatosis. (Support:
Kimmel Family Philanthropic Fund) |
|
Abstract Title: |
Severe muscular dystrophy in mice that lack the alpha7 integrin
and dystrophin: a new dystrophic mouse model |
Presenting/First Author: |
Burkin, Dean J (Faculty) |
Department, Institution: |
Pharmacology, University of Nevada |
Address: |
1664 N. Virginia Reno, NV 89557 United States |
Phone/Fax: |
775-784-6288 / 775-784-1620 |
Email: |
[email protected] |
Abstract Theme: |
Molecular Basis of Muscle Dysfunction |
Author(s): |
Burkin, Dean J (Univ. of Nevada, Reno, NV 89557)
Rooney, Jachinta E (Univ. of Nevada, Reno, NV 89557)
Welser, Jennifer V (Univ. of Nevada, Reno, NV 89557) |
Body of Abstract: |
The dystrophin glycoprotein complex and alpha7beta1 integrin are
transmembrane receptors in skeletal muscle that provide molecular
continuity between laminin in the extracellular matrix and the cell
cytoskeleton. Loss of dystrophin results in Duchenne Muscular Dystrophy
(DMD). Mutations in the alpha7 integrin gene cause congenital myopathy.
The alpha7beta1 integrin is increased in the skeletal muscle of DMD
patients and mdx mice. This observation led to the suggestion that
dystrophin and the alpha7beta1 integrin might have complementary
functional and structural roles. To test this hypothesis, we generated
mice lacking both dystrophin and alpha7 integrin (mdx/alpha7-/-). mdx/alpha7-/-
mice developed early onset muscular dystrophy highly akin to DMD
patients and died between 2-4 weeks of age. Skeletal muscle fibers from
mdx/alpha7-/- mice exhibited loss of membrane integrity, increased
centrally located nuclei and mononuclear cell infiltrate compared to mdx
or alph a7 integrin null animals. Loss of dystrophin and/or alpha7
integrin resulted in altered expression of laminin-alpha2 chain. These
results point to complementary roles for dystrophin and the alpha7beta1
integrin in maintaining the functional integrity of skeletal muscle. |
|
Abstract Title: |
Paired-like homeodomain transcription factor 1 (Pitx1) regulates
genes involved in muscle atrophy |
Presenting/First Author: |
Chen, Yi-Wen (Faculty) |
Department, Institution: |
Center for Genetic Medicine Research, Children’s National Medical
Center |
Address: |
111 Michigan Avenue, N.W. Washington, DC 20010 United States |
Phone/Fax: |
202-884-6025 / 202-884-6014 |
Email: |
[email protected] |
Abstract Theme: |
Molecular Basis of Muscle Dysfunction |
Author(s): |
Chen, Yi-Wen (Children’s National Medical Center, Washington, DC
20010)
Kostek, Matthew (Children’s National Medical Center, Washington, DC
20010)
Li, Ling (Children’s National Medical Center, Washington, DC 20010)
Shi, Rongye (Children’s National Medical Center, Washington, DC 20010) |
Body of Abstract: |
Paired-like homeodomain transcription factor 1 (Pitx1) plays a
critical role in specification of hindlimb identity, however its role in
postnatal skeletal muscle is not known. By comparing expression profiles
of facioscapulohumeral muscular dystrophy (FSHD) to 125 muscle profiles
of 11 neuromuscular disorders, we showed PITX1 was specifically
up-regulated 11 fold (p<0.01) and 13.2 (p<0.001) in affected and
unaffected FSHD muscles, respectively. Further in vivo functional
studies showed Pitx1 induced the ubiquitin-proteasome pathways,
including up-regulation of Foxo1a and atrogin 1. Interestingly, although
not up-regulated in other neuromuscular diseases, we found PITX1, FOXO1A
and atrogin 1 was up-regulated in muscles undergoing atrophy after two
days of inactivity. Using luciferase assay, we further showed that
cotransfecting Pitx1 expression vector and a Foxo1a promoter fragment
containing consensus Pitx1 binding sites leaded to 8 fold up-regulation
(p<0.001 ) of luciferase activities. Our results suggest that PITX1 is
likely to be involved in the early skeletal muscle atrophy process
through regulating FOXO1A, an upstream regulator of atrogin 1 and the
ubiquitin-ligase proteasome pathway. |
|
Abstract Title: |
Muscle LIM Protein cooperates with titin to maintain the
structural integrity of Drosophila muscle |
Presenting/First Author: |
Clark, Kathleen A (Faculty) |
Department, Institution: |
Biology, University of Utah |
Address: |
2000 Circle of Hope Salt Lake City, UT 84112 United States |
Phone/Fax: |
801 581 4793 / 801 581 2175 |
Email: |
[email protected] |
Abstract Theme: |
Sarcomere Cytoskeleton |
Author(s): |
Clark, Kathleen A (Univ. of Utah, Salt Lake City, UT 84112)
Bland, Jennifer M (Univ. of Utah, Salt Lake City, UT 84112)
Beckerle, Mary C (Univ. of Utah, Salt Lake City, UT 84112)
|
Body of Abstract: |
Muscle LIM Protein (MLP) is found at Z-lines and muscle termini in
mature muscle, but is nuclear during muscle differentiation. Thus, MLP
may have important roles as both a structural protein and regulator of
gene expression. Mutations in MLP lead to cardiomyopathy, and MLP is
potently upregulated in skeletal muscle during eccentric exercise;
however, its cellular functions remain unknown.
We have undertaken the study of an MLP homolog in Drosophila melanogater.
We generated null mutations in mlp84B and found that the protein is
essential for post-embryonic muscle function. The mlp84B mutants cannot
fully contract their body wall muscles during pupariation, and make a
long, thin pupal case. Most animals arrest development at this point,
and exhibit only limited muscle contractions. A few mutants eclose as
adults, but have impaired flight. We looked for mutations in other genes
that would modify the mlp84B phenotype. Flies null for mlp84B and
heterozygous for a mutation in D-titin show marked enhancement of the
mlp84B muscle phenotypes. Surprisingly, the mlp84B mutant muscles on
their own do not have any observable structural defects, but
co-reduction in D-titin activity produces a severe disruption of muscle
organization. |
|
Abstract Title: |
A Novel Fluorescent Nanocircuit for Measuring Conformational
Heterogeneity of Myosin Bound to Thin Filaments |
Presenting/First Author: |
Coffee, Pilar G (Grad) |
Department, Institution: |
Biology, University of North Texas |
Address: |
PO Box 305220 Denton, TX 76203 United States |
Phone/Fax: |
940-565-2683 / 940-565-4136 |
Email: |
[email protected] |
Abstract Theme: |
Sarcomere Cytoskeleton |
Author(s): |
Coffee, Pilar G (University of North Texas, Denton, TX 76203)
Root, Douglas D (University of North Texas, Denton, TX 76203)
|
Body of Abstract: |
A novel fluorescent nanocircuit assay is developed to study the
dynamics of the interactions of actomyosin using LRET. Excitation of the
CS-124 antenna with a pulsed laser excites a terbium chelate on the
lever arm which transfers energy to its acceptor, Cy5-ADP on myosin,
which in turn relays the energy to Cy7-Troponin T on the thin filament.
The nanocircuit is broken if any of the three components is farther
apart than their Ro distance for energy transfer to occur, so the decay
of signal from the terminal acceptor reports on the conformation of
myosin S1 bound near troponin while the decays of previous fluors of the
circuit report on the average conformations of all S1 regardless of
their position. The nanocircuit has allowed us to distinguish pre-
versus post-powerstroke conformations of skeletal myosin S1 when it is
bound near troponin on the thin filament. Additionally, it has allowed
us to detect changes in the relationship of troponin T relative to myos
in in the presence and absence of muscle contraction triggering molecule
calcium. A speculative model is suggested that myosins binding adjacent
to the troponin complex are unable to complete their powerstroke but
might contribute to the activation of the thin filament. |
|
Abstract Title: |
Identification of putative in vivo substrates of calpain 3 by
using comparative proteomics of overexpressing transgenic and
non-transgenic mice |
Presenting/First Author: |
Cohen, Niaz (Postdoc - Degree Year: 2) |
Department, Institution: |
Neurology and Pediatrics, University of California, Los Angeles |
Address: |
635 Young Dr. South Los Angeles, CA 90095-7334 United States |
Phone/Fax: |
310-794-5225 / 310-206-1998 |
Email: |
[email protected] |
Abstract Theme: |
Molecular Basis of Muscle Dysfunction |
Author(s): |
Cohen, Niaz (University of California, Los Angeles, USA)
Kudryashova, Elena (University of California, Los Angeles, USA)
Kramerova, Irina (University of California, Los Angeles, USA)
Anderson (deceased), Louise (University of Newcastle, UK)
Beckmann, Jacques (University of Lausanne, Lausanne, Switzerland)
Bushby, Katherine (Institute of Human Genetics, International Center for
Life, Newcastle upon Tyne, UK)
Spencer, Melissa (University of California, Los Angeles, USA)
|
Body of Abstract: |
Calpain 3 (CAPN3) is a calcium dependent protease, mutations in
which cause limb girdle muscular dystrophy type 2A. To understand the
physiological function of CAPN3 we compared the proteomes of transgenic
mice that over express CAPN3 (CAPN3 Tg) and their non-transgenic (non-Tg)
counterparts. We first examined known dystrophy-related proteins to
determine if overexpression of CAPN3 results in a change in their
distribution or concentration. This analysis did not identify any known
dystrophy proteins as substrates of CAPN3. Next, we used a proteomic
approach to identify differentially represented proteins in 2-DE of
CAPN3 Tg and non-Tg mice. LC-MS/MS analysis led to the identification of
10 possible substrates for CAPN3, classified into two categories:
metabolic and myofibrillar. Myosin light chain 1 (MLC1) was focused upon
because our previous studies suggested a role for CAPN3 in sarcomere
remodeling. In this study, CAPN3 was shown to proteolyse MLC1 in vit ro.
These studies are the first to identify possible substrates for CAPN3 in
vivo, and support a role for CAPN3 in sarcomere remodeling by cleavage
of myofibrillar proteins such as MLC1. In addition, these data also
suggest a role for CAPN3 in mitochondrial protein turnover. |
|
Abstract Title: |
Evaluation of the olopatadine effect in the dystrophinopathy
progression in mdx mice submitted to physical activity |
Presenting/First Author: |
Costa, Maria Cristina R (Faculty) |
Department, Institution: |
Medicine, University of Ribeirao Preto |
Address: |
Av Costabile Romano 2201 Ribeirao Preto, 14096-900 Brazil |
Phone/Fax: |
55-16-3603-6795 / 55-16-3919-3028 |
Email: |
[email protected] |
Abstract Theme: |
Therapies |
Author(s): |
Costa, Maria Cristina R (Univ. of Ribeirao Preto, Muscular Dystrophy
Research Center - AADM, Ribeirao Preto, 14096-900, Brazil)
Araujo, Daniela D (Univ. of Ribeirao Preto, Muscular Dystrophy Research
Center - AADM, Ribeirao Preto, 14096-900, Brazil)
Pires, Francisco Souza M (Univ. of Ribeirao Preto, Muscular Dystrophy
Research Center - AADM, Ribeirao Preto, 14096-900, Brazil)
Fuzisaki, Tatiana T (Univ. of Ribeirao Preto, Muscular Dystrophy
Research Center - AADM, Ribeirao Preto, 14096-900, Brazil)
Matioli, Fabiana (Univ. of Ribeirao Preto, Muscular Dystrophy Research
Center - AADM, Ribeirao Preto, 14096-900, Brazil)
Cerri, Daniel G (Univ. of Ribeirao Preto, Muscular Dystrophy Research
Center - AADM, Ribeirao Preto, 14096-900, Brazil)
Couto, Lucelio B (Univ. of Ribeirao Preto, Muscular Dystrophy Research
Center - AADM, Ribeirao Preto, 14096-900, Brazil)
Bizario, Joao Carlos S (Univ. of Ribeirao Preto, Muscular Dystrophy
Research Center - AADM, Ribeirao Preto, 14096-900, Brazil) |
Body of Abstract: |
Duchenne Muscular Dystrophy (DMD) is a progressive neuromuscular
disease caused by dystrophin absence. The mdx mouse, a DMD animal model,
shows milder phenotype, intensified by physical activity. Inflammatory
response and immune cells contribute to muscle degeneration and/or
regeneration. Mast cells are recruited to injury sites and liberate
mediators that increase collagen production, attract other inflammatory
cells and intensify tissue damage. Olopatadine, an H1-histamine
antagonist and a mast cell degranulation inhibitor, decreases Ca2+
influx and the liberation of histamine, tryptase, leukotrienes and
prostaglandins. In this study, we have evaluated the effect of
olopatadine in mdx mice. Four-week old mice were characterized in the
beginning and in the end of a physical activity program during five
weeks in relation to histopathological analyses of gastrocnemius and
diaphragm and serum creatine kinase dosage. Nine week old mice treated
with olopatadine showe d amelioration of muscular condition, with less
inflammatory infiltrates and necrosis foci, decreased degeneration/regeneration
ratio and centrally nucleated myofibers. Quantitative analyses are in
progress in order to reinforce the benefic effect of olopatine in DMD. |
|
Abstract Title: |
Ageing, Skeletal Muscle and Sprint-Force Training |
Presenting/First Author: |
Cristea, Alexander D (Undergrad) |
Department, Institution: |
Neurovetenskap, Inst f neurofysiologi |
Address: |
Akademiska Sjukhuset Uppsala Uppsala, 751 85 Sweden |
Phone/Fax: |
(46)18 6119338 / (46)18500952 |
Email: |
[email protected] |
Abstract Theme: |
|
Author(s): |
Cristea, Alexander (University of Uppsala, Uppsala; Clinincal
Neurofysiology, University Hospital, Uppsala)
Larsson, Lars (Clinincal Neurofysiology, University Hospital, Uppsala)
|
Body of Abstract: |
The potential of sprint-force training to ameliorate sarcopenia was
explored. The relationship between age, training and skinned single
fiber characteristics and force production were determined in 18- to 77-yr-old
male sprinters. The maximum force generated by the single muscle fibers
was higher (P<0.01) in the younger than in the older subjects. Type I
and IIa MyHC fibers had a larger cross sectional area in younger than in
elderly (P<0.05). The specific tension in single fibers expressing the
type I and IIa MyHC isoforms did not significantly differ between
younger and older subjects. The V0 of type I MyHC fibers was lower (P<0.05)
in older than in younger subjects, but there was no ageing-related
difference in the shortening velocity of muscle fibers expressing the
IIa MyHC isoform. The sprint-trained athletes experienced the earlier
reported ageing-related reduction in the size of fast fibers and a lower
area and V0 of type I MyHC fibers. At the same, the mu scle fiber and
strength characteristics were preserved at a high level in the oldest
runners, underlining the favorable impact of sprint exercise on ageing
skeletal muscle.
Supported by NIH, Swedish Research Council, Swedish National Centre for
Research in Sports |
|
Abstract Title: |
Association between AKT signaling and hypertrophic response of
Duchenne and limb-girdle muscular dystrophies |
Presenting/First Author: |
Crosbie, Rachelle H (Faculty) |
Department, Institution: |
Physiological Science, UCLA |
Address: |
621 Charles E. Young Drive South Los Angeles, CA 90095-1606 United
States |
Phone/Fax: |
310-794-2103 / 310-206-9184 |
Email: |
[email protected] |
Abstract Theme: |
Therapies |
Author(s): |
Crosbie, Rachelle H (University of California, Los Angeles)
Peter, Angela K (University of California, Los Angeles)
|
Body of Abstract: |
Dystrophic muscle undergoes repeated cycles of degeneration/regeneration,
characterized by the presence of hypertrophic fibers. In order to
elucidate the signaling pathways that govern these events, we
investigated Akt activation in normal and dystrophic muscle. Akt is
activated in neonatal muscle and in actively dividing myoblasts,
supporting a developmental role for Akt signaling. Akt activation was
detected at very early, prenecrotic stages of disease pathogenesis and
maximal activation was observed during peak stages of muscle hypertrophy.
Duchenne muscular dystrophy patients exhibit a similar pattern of Akt
activation. Mice with sarcoglycan-deficient muscular dystrophy possess
more severe muscle pathology and display elevated Akt signaling. However,
the highest levels of Akt activation were found in dystrophin-utrophin
deficient muscle with very advanced dystrophy. We propose that Akt may
serve as an early biomarker of disease and that Akt activation mediates
hypertrophy in muscular dystrophy. Current investigations are focused on
introducing constitutively-active and dominant-negative Akt into
prenecrotic mdx mice to determine how early modification of Akt activity
influences disease pathogenesis. |
|
Abstract Title: |
Overexpression of Microspan, a Novel Component of the
Sarcoplasmic Reticulum, Causes Severe Muscle Pathology with Triad
Abnormalities |
Presenting/First Author: |
Crosbie, Rachelle H (Faculty) |
Department, Institution: |
Physiological Science, UCLA |
Address: |
621 Charles E Young Drive South Los Angeles, CA 90024 United States |
Phone/Fax: |
310-794-2103 / 310-206-3987 |
Email: |
[email protected] |
Abstract Theme: |
Molecular Basis of Muscle Dysfunction |
Author(s): |
Crosbie, Rachelle H (Univ. of California, Los Angeles, CA 90095)
Peter, Angela K (Univ. of California, Los Angeles, CA 90095)
Heighway, Jim (Univ. of Liverpool, Cancer Research Centre, Liverpool,
UK)
Espinoza, Erica (Univ. of California, Los Angeles, CA 90095)
Miller, Gaynor (Univ. of California, Los Angeles, CA 90095)
|
Body of Abstract: |
Sarcospan is a core component of the dystrophin-glycoprotein complex.
We describe the isolation of an alternatively-spliced isoform of
sarcospan, which we designate ‘microspan’ based on its small size
relative to sarcospan. Microspan has two transmembrane domains, is not
an integral component of the dystrophin-glycoprotein complex and is not
perturbed by the loss of dystrophin. Microspan protein is detected at
the sarcoplasmic reticulum using indirect immunofluorescence and
immunoelectron microscopy. Furthermore, microspan purifies with skeletal
muscle sarcoplasmic reticulum and not transverse tubules. Mice
engineered to overexpress microspan display severe kyphosis and die at
approximately eight weeks of age. Levels of ryanodine receptor,
dihydropyridine receptor, and SERCA-1 are greatly reduced in microspan
transgenic muscle. Furthermore, electron microscopy reveals that
microspan overexpression causes a dramatic perturbation in triad
structure. Our findings suggest that microspan is an important component
of the sarcoplasmic reticulum and may contribute to
excitation-contraction coupling. |
|
Abstract Title: |
Sarcospan Overexpression in Skeletal Muscle Perturbs the
Dystrophin-Glycoprotein Complex and Causes Severe Muscle Pathology |
Presenting/First Author: |
Crosbie, Rachelle H (Faculty) |
Department, Institution: |
Physiological Science, UCLA |
Address: |
621 Charles E Young Drive South Los Angeles, CA 90095 United States |
Phone/Fax: |
310-794-2103 / 310-206-3987 |
Email: |
[email protected] |
Abstract Theme: |
Plasma Membrane Stability/Repair |
Author(s): |
Crosbie, Rachelle H (Univ. of California, Los Angeles, CA 90095)
Espinoza, Erica (Univ. of California, Los Angeles, CA 90095)
Mehta, Swapan (Univ. of California, Los Angeles, CA 90095)
Miller, Gaynor (Univ. of California, Los Angeles, CA 90095)
|
Body of Abstract: |
Sarcospan is a tetraspanin-like component of the
dystrophin-glycoprotein complex (DGC). In order to elucidate the role of
sarcospan in muscle, we generated transgenic mice that overexpress
sarcospan (~10-fold) in skeletal muscle. Sarcospan transgenic mice
exhibit kyphosis and die prematurely between 8 and 10 weeks of age. At 4
weeks of age, sarcospan transgenic mice are smaller, less motile, and
display an abnormal waddling gait. Histological analysis reveals that
sarcospan overexpression causes severe muscle pathology, including
variation in fiber size, fibrosis, and mild central nucleation. Using
serum creatine kinase and Evans Blue dye assays, we show that sarcospan
transgenic muscle fibers display normal sarcolemma integrity. Increases
in sarcospan expression cause upregulation of the entire DGC and
caveolin-3 at the sarcolemma. Surprisingly, we were unable to purify the
DGC from sarcospan transgenic muscle. Biochemical fractionation
demonstrates that sarcospa n clusters the DGC and into insoluble protein
aggregates within the membrane, which also affects structure of the
extracellular matrix. These perturbations lead to severe muscle
pathology reminiscent of congenital muscular dystrophy. |
|
Abstract Title: |
Effect of Sarcospan Expression on Dystroglycan Function |
Presenting/First Author: |
Crosbie, Rachelle H (Faculty) |
Department, Institution: |
Physiological Science, UCLA |
Address: |
621 Charles E Young Drive South Los Angeles, CA 90095 United States |
Phone/Fax: |
310-794-2103 / 310-206-3987 |
Email: |
[email protected] |
Abstract Theme: |
Sarcomere Cytoskeleton |
Author(s): |
Crosbie, Rachelle H (Univ. of California, Los Angeles, CA 90095)
Miller, Gaynor (Univ. of California, Los Angeles, CA 90095)
Felix, Ricardo (Cinvestav-IPN, Mexico)
Mehta, Swapan (Univ. of California, Los Angeles, CA 90095)
|
Body of Abstract: |
Several observations suggest that dystroglycan and sarcospan may
interact. We set out to probe whether sarcospan affects dystroglycan
function by creating stable myoblast cell lines with either elevated or
reduced levels of sarcospan. Myoblasts are an excellent model system for
such studies since they express dystroglycan and sarcospan, but not the
sarcoglycans. Myoblasts with reduced sarcospan are small and round with
few filapodia. In contrast, myoblasts with elevated sarcospan are very
large and exhibit many filapodia. Cell surface area was quantitated by
whole cell patch clamp, demonstrating that sarcospan overexpressing
cells are 30% larger than controls while sarcospan-deficient cells are
30% smaller. Sarcospan-deficiency doubled cell division rates and
sarcospan overexpression reduced cell growth rates. Sarcospan stable
cell lines never differentiated into myotubes. Dystroglycan levels were
coordinately regulated with sarcospan. Upregulation of dystroglycan led
to elevated numbers of focal adhesion contacts and dramatic increases in
laminin binding. Reduction of dystroglycan was associated with fewer
focal adhesions and suppressed laminin binding. These data suggest that
sarcospan functions to regulate dystroglycan. |
|
Abstract Title: |
Therapeutical benefit of AAV-mediated injection of a mutated
propeptide of myostatin in calpain 3 deficient mice |
Presenting/First Author: |
Daniele, Nathalie (Faculty) |
Department, Institution: |
UMR8115, Genethon |
Address: |
1, rue de l'internationale Evry, 91000 France |
Phone/Fax: |
33 1 69 47 29 87 / 33 1 60 77 86 98 |
Email: |
[email protected] |
Abstract Theme: |
Regulation of Muscle Mass |
Author(s): |
Daniele, Nathalie (Genethon, CNRS UMR 8115, Evry 91000, France)
Bartoli, Marc (Genethon, CNRS UMR 8115, Evry 91000, France)
Poupiot, Jerome (Genethon, CNRS UMR 8115, Evry 91000, France)
Fougerousse, Francoise (Genethon, CNRS UMR 8115, Evry 91000, France)
Vulin, Adeline (Genethon, CNRS UMR 8115, Evry 91000, France)
Garcia, Luis (Genethon, CNRS UMR 8115, Evry 91000, France)
Danos, Olivier (Genethon, CNRS UMR 8115, Evry 91000, France)
Richard, Isabelle (Genethon, CNRS UMR 8115, Evry 91000, France) |
Body of Abstract: |
Myostatin (GDF8) is a negative regulator of muscle mass which
inhibition has been proposed as a therapeutical strategy for muscle
wasting conditions. Indeed, blocking myostatin action through different
strategies has been proved beneficial for the pathophysiology of the
dystrophin–deficient mdx mouse. We tested the inhibition of myostatin by
AAV-mediated expression of a mutated myostatin propeptide fused to the
murine secreted alkaline phophatase in wild-type and two animal models
of muscular dystrophies. The results in wild-type mice indicated that
the fusion is permissive for the secretion of mSeAP and induce a
hypertrophy. Unexpectedly, in the highly regenerative Sgca-null mice,
expression is not maintained, suggesting that inhibition of myostatin
does not improve survival of the muscle fibers. However, in calpain 3
deficient mice, a boost in muscle mass and a muscle strengthening were
obtained, suggesting that myostatin inhibition could constitute of a
therape utical strategy for this pathology. |
|
Abstract Title: |
CNS abnormalities in myotonic dystrophy types 1 and 2 |
Presenting/First Author: |
Day, John W (Faculty) |
Department, Institution: |
Neurology and Institute Human Genetics, University of Minnesota |
Address: |
420 Delaware St. SE Minneapolis, MN 55455 United States |
Phone/Fax: |
612-625-6180 / 612-625-8488 |
Email: |
[email protected] |
Abstract Theme: |
|
Author(s): |
Day, John W (Department of Neurology, University of Minnesota,
Minneapolis, MN 55455)
Dalton, Joline C (Department of Genetics, Cell Biology and Development,
University of Minnesota, Minneapolis, MN 55455)
Franc, Daniel (Department of Psychiatry, University of Minnesota,
Minneapolis, MN 55455)
Rodriguez, Craig P (Department of Psychiatry, University of Minnesota,
Minneapolis, MN 55455)
Wozniak, Jeff R (Department of Psychiatry, University of Minnesota,
Minneapolis, MN 55455)
Ranum, Laura P (Department of Genetics, Cell Biology and Development,
University of Minnesota, Minneapolis, MN 55455)
Lim, Kelvin O (Department of Psychiatry, University of Minnesota,
Minneapolis, MN 55455)
|
Body of Abstract: |
CNS dysfunction can be severe in muscular dystrophy, but the
molecular pathophysiology is often unknown. To define CNS changes in
myotonic dystrophy, we studied subjects with both DM1 and DM2.
Demonstrations of molecular and clinical parallels of DM1 and DM2, each
of which is caused by a transcribed but untranslated repeat expansion,
indicate that features common to both forms result from toxic effects of
the RNA expansions. Whether this mechanism also causes the CNS aspects
of DM, which differ in DM1 and DM2, remains unclear.
Neuropsychological tests and MRI scans were performed on 5 strictly
defined adult-onset DM1, 3 DM2, and 8 healthy control subjects.
Quantitative volumetric measures of grey matter, white matter, and CSF
showed significantly less grey matter volume in both DM groups compared
to controls. Diffusion tensor imaging showed significantly reduced
inferior frontal fractional anisotropy (FA, a measure of white matter
integrity) in both DM groups compared to controls. Consistent with the
frontal white matter changes, there was a trend toward reduced working
memory in both DM groups compared to controls. Determining CNS changes
common to DM1 and DM2 will help define features caused by the toxic RNA
mechanism. |
|
Abstract Title: |
Muscle-derived nitric oxide modulates adult neurogenesis in the
brains of mdx mice. |
Presenting/First Author: |
Deng, Bo (Grad) |
Department, Institution: |
Physiological Science, UCLA |
Address: |
621 Charles E. Young Drive South Los Angeles, CA 90095 United States |
Phone/Fax: |
310-206-8389 / 310-825-8489 |
Email: |
[email protected] |
Abstract Theme: |
Congenital Muscular Dystrophy and Nuclear Membrane Diseases |
Author(s): |
Deng, Bo (Univ. of California, Los Angeles, CA 90095)
Tidball, James G (Univ. of California, Los Angeles, CA 90095)
|
Body of Abstract: |
Duchenne muscular dystrophy (DMD) patients display significant
cognitive defects with IQs about 1 standard deviation below normal.
However, the mechanisms underlying these defects are obscure. Learning
deficits are well-correlated with perturbations in adult neurogenesis in
the dentate gyrus (DG), which can be modulated by nitric oxide (NO). NO
is not only a local signaling molecule, it can also have systemic,
regulatory roles, which suggests that systemic NO may modulate adult
neurogenesis. In DMD patients, there is an approximately 80% reduction
in NOS activity in muscle as well as in plasma NO concentrations. Mdx
mice, the animal model of DMD, display similar reduction in muscle NOS
activity and learning deficits. Therefore, we propose that loss of
systemic, muscle-derived NO causes defects in adult neurogenesis in the
DG of mdx mice. We have found that mdx mice display enhanced cell
proliferation and decreased neuronal differentiation in the DG, which
can be rescued to wild-type levels by expression of a muscle-specific
nNOS transgene. Our data strongly support our hypothesis, providing new
insights into the mechanisms underlying the learning deficits in DMD
patients. (Supported by the Muscular Dystrophy Association) |
|
Abstract Title: |
Aberrant expression of lymphatic vessel proteins in laminin
alpha2-deficient mouse muscle suggests that laminin alpha2 is required
for normal lymphangiogenesis in muscle. |
Presenting/First Author: |
Dominov, Janice A (Faculty) |
Department, Institution: |
Neuromuscular Diseases, Boston Biomedical Research Institute |
Address: |
64 Grove Street Watertown, MA 02472 United States |
Phone/Fax: |
617-658-7739 / 617-972-1761 |
Email: |
[email protected] |
Abstract Theme: |
Congenital Muscular Dystrophy and Nuclear Membrane Diseases |
Author(s): |
Dominov, Janice A (Boston Biomedical Research Institute, Harvard
Medical School)
Wardrop, Katherine E (Boston Biomedical Research Institute)
|
Body of Abstract: |
An early feature of laminin alpha2-deficient congenital muscular
dystrophy is transient inflammation of muscle tissue. We are studying
early pathogenesis of laminin alpha2-deficient (dy) mouse muscles using
tenascin-C and lymphatic vessel expression as indicators of
inflammation. We have found that expression of the lymphatic vessel
marker LYVE-1 is dramatically reduced in dy muscles as early as 7 days
after birth. Other lymphatic markers, podoplanin and Prox1, are also
aberrantly expressed in dy muscles compared with controls. Podoplanin is
up-regulated in the space surrounding dy fibers while Prox1 is
up-regulated within muscle fibers themselves. Expression of the blood
vessel marker CD31 is not altered in dy muscles. Results suggest that
laminin alpha2 is required for normal lymphangiogenesis in skeletal
muscle. Lymphatic vessels transport proteins, fluids and cells from
tissues to lymph nodes and help recruit immune cells into damaged tissue
to promote repair. An abnormal lymphatic system in dy muscles could
significantly impair both the inflammatory process and muscle
regeneration. These observations provide evidence for additional
complexity in the underlying cause of laminin alpha2-deficient muscle
pathology. Support: NIAMS |
|
Abstract Title: |
Application of amphiphillic polymers for gene delivery |
Presenting/First Author: |
Doran, Timothy J (Faculty) |
Department, Institution: |
Muscular Dystrophy, Carolinas Medical Center |
Address: |
1000 Blythe Blvd Charlotte, NC 28203 United States |
Phone/Fax: |
704-446-6237 / 704-355-1679 |
Email: |
[email protected] |
Abstract Theme: |
Therapies |
Author(s): |
Doran, Timothy J (MDA/ALS Center, Cannon Research Center, Carolinas
Medical Center, Charlotte, NC)
Gonsalves, Ken (Department of Chemistry, UNC Charlotte, Charlotte, NC)
Yengo, Chris M (Department of Biology, UNC Charlotte, Charlotte, NC)
Lu, Qi L (MDA/ALS Center, Cannon Research Center, Carolinas Medical
Center, Charlotte, NC)
|
Body of Abstract: |
Non ionic copolymers consisting of hydrophobic and hydrophilic
blocks in a triblock configuration hold a great potential for gene and
nucleic acid delivery. They are easily synthesized and can be
manipulated to produce a wide array of polymers with highly diverse
physical properties and potential interactions with target transgenes or
oligonucleotides. The efficiency can be improved by incorporating
functional groups critical for gene delivery which will induce DNA
encapsulation and protection. Preliminary studies found that polymers
improve efficiency of gene delivery in vivo and in vitro differentially.
The polymers also bind to nucleic acid differentially. Both peak
excitation and stopped-flow kinetic studies revealed that the
interaction is different from those seen in cationic polymers which
condense nucleic acid. Systematic investigation into the interaction
between polymer and nucleic acid in connection with the effect of
polymers on gene delivery could re veal the relationship between
structure and function and lead to new designs of polymers that should
increase delivery efficiency, provide specific targeting of cells, and
reduce toxicity. |
|
Abstract Title: |
Loss of cyclophilin D improves cardiac pathology in
delta-sarcoglycan deficient mice, but has no effect on skeletal muscle
pathology |
Presenting/First Author: |
Douglas, Millay P (Grad) |
Department, Institution: |
Molecular Cardiovascular Biology, Cincinnati Children's Hopital
Medical Center |
Address: |
3333 Burnet Ave. CHRF Rm. 3029 Cincinnati, OH 45229 United States |
Phone/Fax: |
513-636-2467 / 513-636-5958 |
Email: |
[email protected] |
Abstract Theme: |
Molecular Basis of Muscle Dysfunction |
Author(s): |
Millay, Douglas P (Univ. of Cincinnati, Cincinnati Children's
Hospital Medical Center, Cincinnati, OH 45229-3039)
Parsons, Stephanie A (Univ. of Cincinnati, Cincinnati Children's
Hospital Medical Center, Cincinnati, OH 45229-3039)
McNally, Elizabeth M (The Univ. of Chicago, Chicago, IL 60637)
Molkentin, Jeffery D (Univ. of Cincinnati, Cincinnati Children's
Hospital Medical Center, Cincinnati, OH 45229-3039)
|
Body of Abstract: |
Increased Ca2+ influx is hypothesized to initiate dystrophic
myofiber loss through activation of degradative enzymes and/or cell
death signaling pathways. Cyclophilin D directly regulates
Ca2+-dependent necrosis through its interaction with the mitochondrial
permeability transition pore. We generated mice lacking
delta-sarcoglycan (scgd-/-) and cyclophilin D (Ppif-/-) in order to
block mitochondrial-driven necrosis. Cell death indicators, central
nucleation, and histological analysis revealed no differences in the
skeletal muscles of scgd-/-Ppif-/- mice compared to scgd-/- mice.
However, scgd-/-Ppif-/- mice had improved cardiac function and
preliminary data suggests less cardiac fibrosis. Our results indicate
that loss of cyclophilin D is not effective in altering skeletal muscle
pathology in scgd-/- mice, but that cardiac muscle is benefited.
However, other types of muscular dystrophy could utilize a
mitochondrial-dependent necrotic pathway. Hence, we crossed the Ppif-/-
mouse with a mouse model of congenital muscular dystrophy due to
laminin-2A deficiency. Preliminary data from this cross will also be
presented to better suggest the overall importance of
mitochondrial-dependent necrosis in muscular dystrophy. |
|
Abstract Title: |
AAV-mediated Microdystrophin Expression Reduces Muscular
Dystrophy in Symptomatic Utrophin/dystrophin Double Knock-out Mice |
Presenting/First Author: |
Duan, Dongsheng (Faculty) |
Department, Institution: |
Molecular Microbiology and Immunology, University of Missouri |
Address: |
One Hospital Dr. Columbia, MO 65212 United States |
Phone/Fax: |
573-884-9584 / 573-882-4287 |
Email: |
[email protected] |
Abstract Theme: |
Therapies |
Author(s): |
Yue, Yongping (University of Missouri, Columbia, MO)
Liu, Mingju (University of Missouri, Columbia, MO)
Duan, Dongsheng (University of Missouri, Columbia, MO)
|
Body of Abstract: |
AAV-mediated microdystrophin expression has shown encouraging
results in ameliorating in mdx muscle pathology. Unfortunately, mdx mice
do not display the same phenotype as human patients. Utrophin/dystrophin
double knock-out (u-dko) mice were developed to mold severe dystrophic
changes in human patients. In this study we evaluated therapeutic effect
of the ?R4-R23/?C microdystrophin gene (?R4/?C) after AAV-6 gene
transfer in neonatal u-dko muscle. At two months after gene transfer,
percentage of centrally nucleated myofiber was reduced from 89.2% to
3.4% and muscle weight was normalized. We have also demonstrated for the
first time that microdystrophin can eliminate interstitial fibrosis,
macrophage infiltration and restore dystrobrevin and syntrophin to the
dystrophin-associated glycoprotein complex. The most impressive results
were achieved in muscle force measurement. Neonatal gene therapy
increased twitch and tetanic specific force. It also brought the
response to eccentric contraction-induced injury to the normal range. In
summary, our results suggest that the ?R4/?C microgene holds great
promise in preventing muscular dystrophy. |
|
Abstract Title: |
Increased cytokines, chemokines, and extracellular matrix
proteins in 21-day mdx and mdx:utrophin-/- serum and diaphragm muscles |
Presenting/First Author: |
Evans, Nicholas P (Grad) |
Department, Institution: |
Human Nutrition Foods and Exercise, Virginia Tech |
Address: |
338 Wallace Hall Blacksburg, VA 24060 United States |
Phone/Fax: |
540-231-9048 / 540-231-3916 |
Email: |
[email protected] |
Abstract Theme: |
Congenital Muscular Dystrophy and Nuclear Membrane Diseases |
Author(s): |
Evans, Nicholas P (Dept. Human Nutrition Foods and Exercise,
Virginia Tech, Blacksburg VA 24060)
Call, Jarrod A (Dept. Human Nutrition Foods and Exercise, Virginia Tech,
Blacksburg VA 24060)
Niday, Ashley K (Dept. of Engineering Sci. and Mechanics, Virginia Tech,
Blacksburg VA 24060)
Voelker, Kevin A (Dept. Human Nutrition Foods and Exercise, Virginia
Tech, Blacksburg VA 24060)
Wolff, Andrew V (Dept. Mechanical Engineering, Virginia Tech, Blacksburg
VA 24060)
Grange, Robert W (Dept. Human Nutrition Foods and Exercise, Virginia
Tech, Blacksburg VA 24060)
|
Body of Abstract: |
Dystrophin-deficient muscles (i.e., Duchenne muscular dystrophy) are
characterized by immune/inflammatory responses and fiber necrosis.
Cytokines and chemokines are important signaling molecules that regulate
the immune/inflammatory response. We hypothesized the concentration of
inflammatory cytokines, chemokines and extracellular matrix proteins in
serum and diaphragm muscles of mdx (n=2) and mdx:utrophin-/- (n=3) mice
would be elevated vs. control (n=3) during early maturation (e.g., age
21-d). The cytokines IL1α and IL-10 were increased ≥ 3-fold in mdx
serum, while IL1α, and IL10 were increased 3 to 4-fold in both
mdx:utrn-/- serum and diaphragm (P≥0.05). The chemokines MCP1 and MCP5
were increased 2 to 10-fold in mdx and mdx:utrn-/- serum (P≥0.05), but
only MCP5 was increased in mdx:utrn-/- diaphragm (P≥0.05). Rantes was
increased 8-fold in mdx:utrn-/- diaphragm (P≥0.05). The extracellular
matrix protein MMP3 was increas ed 3-fold in mdx and mdx:utrn-/-
diaphragm (P≥0.05), but OPN and MMP9 were unchanged. These data suggest
that immune/inflammatory signaling mechanisms may be important mediators
in early disease progression to target for therapeutic intervention.
Research supported by NIH grant AR049881. |
|
Abstract Title: |
Systemic rAAV6-microdystrophin administration enhances skeletal
muscle function and extends lifespan in the dystrophin-/utrophin- mouse
model of severe muscular dystrophy |
Presenting/First Author: |
Gregorevic, Paul (Postdoc - Degree Year: 2001) |
Department, Institution: |
Neurology, The University of Washington |
Address: |
1959 NE Pacific Street Seattle, WA 98195 United States |
Phone/Fax: |
(206) 221-5412 / (206) 616-8272 |
Email: |
[email protected] |
Abstract Theme: |
Therapies |
Author(s): |
Gregorevic, Paul (Dept of Neurology, Univ of Washington, Seattle, WA
98195)
Blankinship, Michael J (Dept of Neurology, Univ of Washington, Seattle,
WA 98195)
Minami, Elina (Dept of Pathology, Univ of Washington, Seattle, WA 98195)
Allen, James M (Dept of Neurology, Univ of Washington, Seattle, WA
98195)
Adams, Marvin E (Dept of Physiology and Biophysics, Univ of Washington,
Seattle, WA 98195)
Froehner, Stanley C (Dept of Physiology and Biophysics, Univ of
Washington, Seattle, WA 98195)
Murry, Charles E (Dept of Pathology, Univ of Washington, Seattle, WA
98195)
Chamberlain, Jeffrey S (Dept of Neurology, Univ of Washington, Seattle,
WA 98195) |
Body of Abstract: |
Gene replacement for the treatment of Duchenne muscular dystrophy
(DMD) has not been rigorously assessed for therapeutic potential because
traditional gene transfer systems do not efficiently transduce key
skeletal muscles in mammals. Also, previous studies have typically
assessed local interventions in the dystrophin-deficient mdx mouse,
which poorly models the severe dystrophy and shortened lifespan of DMD
patients. We have established that IV delivery of recombinant
adeno-associated viral (rAAV) vectors facilitates systemic gene transfer
in mice. This advance has enabled us to rigorously evaluate
administration of a microdystrophin construct as a treatment for DMD in
the dystrophin-/utrophin- mouse, which exhibits severe muscular
dystrophy and ~75% shortened lifespan compared with wildtype mice.
Systemic rAAV6-microdystrophin administration restored dystrophin
expression in limb and respiratory muscles, reducing indices of muscle
disease, and increasing mus cle function. Treated mice also exhibited
considerably extended lifespan. These data demonstrate that systemic
rAAV6-microdystrophin administration can alleviate pathology associated
with muscular dystrophy body-wide in mice, and may hold potential for
treatment of DMD. |
|
Abstract Title: |
Anti-inflammatory drugs, or increased IGF-1 expression, reduce
necrosis of dystrophic muscle. |
Presenting/First Author: |
Grounds, Miranda D (Faculty) |
Department, Institution: |
Anatomy & Human Biology, University of Western Australia |
Address: |
Stirling Highway, Crawley Perth, WA 6009 Australia |
Phone/Fax: |
(618) 6488 3486 / (618) 6488 1051 |
Email: |
[email protected] |
Abstract Theme: |
Plasma Membrane Stability/Repair |
Author(s): |
Grounds, Miranda D (University of Western Australia, Australia.)
Radley, Hannah (University of Western Australia, Australia.)
Shavlakadze, Thea (University of Western Australia, Australia.)
Gebski, Bjanka (University of Western Australia, Australia.)
Torrisi, Jo (University of Western Australia, Australia.)
Davies, Marilyn (University of Western Australia, Australia.)
Bogoyevitch, Marie (University of Western Australia, Australia.)
|
Body of Abstract: |
Dystrophic myofibres with defective dystroglycan complexes are
susceptible to sarcolemma damage. Little is known about the balance
between repair of minor damage and myofibre necrosis. Inflammatory
cytokines and cells can exacerbate initial damage and we have shown
reduced necrosis of dystrophic mdx muscle following a range of
anti-inflammatory interventions including silencing TNF-alpha using
antibodies (Remicade and cV1q) or the soluble receptor (Enbrel), the
depletion of neutrophils, the blocking of mast cell degranulation
(Cromolyn), the blocking of complement C5a, and exposure to the
corticosteroid prednisolone. These data support an important role for
inflammation in the exacerbation of muscular dystrophy and provide new
drug interventions to reduce the clinical severity of Duchenne Muscular
Dystrophy. Conversely, we have shown that over-expression of IGF-1
specifically within dystrophic myofibres of MLC.IGF-1:Ea/mdx also
reduces necrosis (see http://school
.anhb.uwa.edu.au/personalpages/grounds/). As TNF-alpha can block IGF-1
signaling, the mechanisms of action of both TNF-alpha and IGF-1 combined
with interactions between these signaling pathways is a central focus of
our ongoing research. |
|
Abstract Title: |
Mechanisms for dystrophin expression in BMD patients with
premature stop codons and frameshift mutations in DMD exon 1 |
Presenting/First Author: |
Gurvich, Olga L (Postdoc - Degree Year: 2005) |
Department, Institution: |
Human Genetics, Universtiy of Utah |
Address: |
15 North 2030 East Salt Lake City, UT 84112 United States |
Phone/Fax: |
801-587-7849 / 801-581-6463 |
Email: |
[email protected] |
Abstract Theme: |
Congenital Muscular Dystrophy and Nuclear Membrane Diseases |
Author(s): |
Gurvich, Olga L (Department of Human Genetics, University of Utah,
Salt Lake City, UT, USA)
Aggarwal, Gaurav (Department of Human Genetics, University of Utah, Salt
Lake City, UT, USA)
Anderson, Christine B (Department of Human Genetics, University of Utah,
Salt Lake City, UT, USA)
Howard, Michael T (Department of Human Genetics, University of Utah,
Salt Lake City, UT, USA)
Hart, Kim (Department of Human Genetics, University of Utah, Salt Lake
City, UT, USA)
Weiss, Robert B (Department of Human Genetics, University of Utah, Salt
Lake City, UT, USA)
Flanigan, Kevin M (Departments of Neurology and Pathology, University of
Utah, Salt Lake City, UT, USA)
|
Body of Abstract: |
A Becker Muscular Dystrophy (BMD) patient who can ambulate at age 62
carries a premature stop codon mutation (c.9G>A; Trp3X) in exon 1 of the
DMD gene. Three potential mechanisms may explain the phenotype:
readthrough of the premature UGA codon; upregulation of alternate
full-length DMD isoforms; or translational initiation at a downstream
methionine codon.
Muscle biopsy was analyzed by immunofluorescence (IF) and immunoblot
(IB), and by quantitative RT-PCR of Dp427m, Dp427p, and Dp427c mRNAs.
Readthrough was determined using a dual luciferase reporter system.
Only a low level (<1%) translational read-through of the Trp3X stop
codon was detected. Upregulation (2.5 fold) of Dp427c alone was noted.
IF and IB showed significant dystrophin expression with dys1, dys2, and
dys3 antibodies, but not with ManEx1a (recognizing an exon 1-encoded
epitope specific to the Dp427m isoform); a decrease in size was
suggested by IB. Approaches to verify the downstream initiation
hypothesis are currently being developed.
We have identified only four more patients with exon 1 mutations (two
Trp3X, Trp4X, and c.15delA). All have BMD, which leads us to postulate
that a mechanism(s) exists which ameliorates the detrimental effect of
exon 1 mutations. |
|
Abstract Title: |
Genetic Modifiers of Muscular Dystrophy |
Presenting/First Author: |
Heydemann, Ahlke (Faculty) |
Department, Institution: |
Medicine, University of Chicago |
Address: |
4218 N Bell #2 Chicago, IL 60618 United States |
Phone/Fax: |
773 702 2684 / 773 702 2681 |
Email: |
[email protected] |
Abstract Theme: |
|
Author(s): |
Heydemann, Ahlke (The University of Chicago, Chicago, IL 60637)
Huber, Jill M (The University of Chicago, Chicago, IL 60637)
Demonbreun, Alexis (The University of Chicago, Chicago, IL 60637)
Hadhazy, Michele (The University of Chicago, Chicago, IL 60637)
McNally, Elizabeth M (The University of Chicago, Chicago, IL 60637)
|
Body of Abstract: |
Limb Girdle Muscular Dystrophy 2C is variable in its presentation
and severity in both humans and mice (Sgcg). To assess the genetic
contribution to phenotypic variation in muscular dystrophy, we initiated
a study to identify genetic modifiers. Sgcg mutant mice were backcrossed
heterozygously for ten generations into four different genetic
background strains: 129/SVEMS+/J (g129), C57BL/6J (gC57), DBA 2J (gDBA)
and CD1 VAF+ (gCD1). After the tenth generation, we assayed homozygous
mouse skeletal, abdominal, diaphragm and heart muscles for Evan’s Blue
Dye (EBD) uptake and hydroxyproline (HOP) content. EBD is a measure of
increased membrane permeability. HOP content measures the amount of
collagen and fibrosis. Both characteristics are hallmarks of muscular
dystrophy. All muscles including heart were affected by dye uptake and
enhanced fibrosis. g129 mice displayed less EBD uptake and less HOP
deposition, and gDBA were the most severely affected by these two a
ssays. We have now analyzed over 100 F2 Sgcg null mice generated from
g129 x gDBA crosses, followed by F1 intercrosses. From these mice,
cohorts that display divergent values for three characteristics will be
analyzed using genome wide scans. Funding: NIH RO1. |
|
Abstract Title: |
A Genetic Study in a C. elegans Model of Muscular Dystrophy |
Presenting/First Author: |
Hongkyun, Kim (Faculty) |
Department, Institution: |
Neurology, Gallo Research Center |
Address: |
5858 Horton Street, suite 200 Emeryville, CA 94608 United States |
Phone/Fax: |
510-985-3162 / 510-985-3101 |
Email: |
[email protected] |
Abstract Theme: |
Molecular Basis of Muscle Dysfunction |
Author(s): |
Kim, Hongkyun (Gallo Research Center, Department of Neurology,
University of California, San Francisco, CA 94608)
Wu, Julia (Gallo Research Center, Department of Neurology, University of
California, San Francisco, CA 94608)
Rogers, Matthew J (Gallo Research Center, Department of Neurology,
University of California, San Francisco, CA 94608)
Pierce-Shimomura, Jonathan T (Gallo Research Center, Department of
Neurology, University of California, San Francisco, CA 94608)
McIntire, Steven L (Gallo Research Center, Department of Neurology,
University of California, San Francisco, CA 94608)
|
Body of Abstract: |
C. elegans is an established model organism that possesses most of
the components of the DGC. DGC mutations can result in progressive
muscle degeneration and a unique defect in the movement of C. elegans.
Using this model system, we have pursued genetic screens to identify new
components of the DGC and to understand the mechanisms underlying the
muscle degeneration. First, we performed a forward genetic screen to
identify mutants that exhibit the same locomotory phenotype as the known
DGC mutants. This screen led to the identification of novel genes,
including a plasma membrane acetylcholine/choline transporter that is
expressed in body muscle and interacts with the DGC. Second, we have
screened directly for mutations resulting in age-dependent muscle
degeneration. C. elegans is semi-transparent, allowing the direct
visualization of muscle degeneration in aging animals. Thus far, we have
identified several mutations that cause muscle degeneration without d
efects in muscle formation, as is observed in the DGC mutants. These
studies may lead to a better understanding of muscle disease and the
mechanisms that lead to muscle degeneration in patients with muscular
dystrophies. |
|
Abstract Title: |
Expression of clathrin heavy chain isoform CHC22 in the
inflammatory myopathies |
Presenting/First Author: |
HOSHINO, SACHIKO (Postdoc - Degree Year: 2002) |
Department, Institution: |
GW Hooper Foundation, UCSF |
Address: |
513 Parnassus Avenue San Francisco, CA 94143-0552 United States |
Phone/Fax: |
415 476 6405 / 415 476 6185 |
Email: |
[email protected] |
Abstract Theme: |
|
Author(s): |
Hoshino, Sachiko (University of California San Francisco, CA,
94143-0552)
Ishii, Akiko (University of Tsukuba, Tsukuba City, Japan, 305-8577)
Ohkoshi, Norio (Tsukuba University of Technology, Tsukuba City, Japan,
305-8520)
Esk, Christopher (University of California San Francisco, CA,
94143-0552)
Brodsky, Frances M (University of California San Francisco, CA,
94143-0552)
|
Body of Abstract: |
The CHC22 isoform of clathrin heavy chain is expressed primarily in
skeletal muscle and has a distinct distribution from that of the
ubiquitous form of clathrin heavy chain (CHC17) that mediates vesicular
membrane traffic. Relative to CHC17, CHC22 protein levels are elevated
during myoblast differentiation and in regenerating rat muscle fibers,
suggesting a role for CHC22 in muscle development and/or repair. To
determine whether CHC22 protein was elevated in regenerating human
muscle fibers, its expression was analyzed in two inflammatory
myopathies, polymyositis (PM) and dermatomyositis (DM). In these
diseases, regenerating fibers express increased levels of class I
histocompatibility molecules, as well as developmental myosin heavy
chain. The distribution of these markers relative to CHC22, the H & E
phenotype of the fibers and the fiber type (determined by ATPase
reaction) were analyzed. Compared to controls (N=4), the staining for
both CHC22 and class I h istocompatibility molecules was increased in
muscle samples from PM (N=8) and DM (N=4) patients. The localization of
the increased expression of both markers was coincident and was mainly
confined to regenerating fibers. All of the fibers in which CHC22
expression was detected were type II fibers. These observations support
the implication of CHC22 in a membrane traffic pathway involved in
myogenesis or muscle repair and suggest relevance of its function to
human muscle disease. |
|
Abstract Title: |
Selenoprotein N: Evidence for a novel cis-acting stimulator of
Selenocysteine insertion |
Presenting/First Author: |
Howard, Michael T (Faculty) |
Department, Institution: |
Human Genetics, University of Utah |
Address: |
15 N 2030 E, Rm 2100 Salt Lake City, UT 84105 United States |
Phone/Fax: |
801-585-1927 / 801-585-3910 |
Email: |
[email protected] |
Abstract Theme: |
Molecular Basis of Muscle Dysfunction |
Author(s): |
Howard, Michael (University of Utah, Salt Lake City, UT 85105)
Aggarwal, Gaurav (University of Utah, Salt Lake City, UT 85105)
Anderson, Christine (University of Utah, Salt Lake City, UT 85105)
Flanigan, Kevin (University of Utah, Salt Lake City, UT 85105)
Atkins, John (University of Utah, Salt Lake City, UT 85105)
|
Body of Abstract: |
Mutations in SEPN1 are associated with several early onset
myopathies including, rigid spine muscular dystrophy, multiminicore
disease and desmin-related myopathy with mallory body-like inclusions.
Expression of SEPN1 requires redefinition of an in-frame UGA codon to
encode for incorporation of the 21st amino acid, selenocysteine.
Selenocysteine insertion is known to require a specialized
selenocysteine insertion sequence (SECIS) located in the 3’ UTR of the
mRNA. Using a reconstituted in vitro translation system, and a cell
based dual luciferase reporter assay, we have identified a second
cis-acting modulator of selenocysteine insertion efficiency, termed
Selenocysteine Redefinition Element (SRE), comprised of a stem loop
located 6 nts 3’of the SEPN1 UGA selenocysteine codon. Directed
mutagenesis and phylogenetic analysis supports the importance of this
stem loop and sequences located 5’ to it. The SRE is sufficient to
induce high level readthrough of the UGA cod on in the absence of the
SECIS element, and acts to facilitate selenocysteine insertion mediated
by the 3’UTR SECIS element and SECIS binding protein 2. Potential
regulatory roles for this new stimulator of selenocysteine insertion
will be presented. |
|
Abstract Title: |
mdm Muscular Dystrophy: Interactions with Calpain 3 and a Novel
Functional Role for Titin’s N2A Domain |
Presenting/First Author: |
Huebsch, Kimberly A (Postdoc - Degree Year: 2003) |
Department, Institution: |
NA, The Jackson Laboratory |
Address: |
600 Main Street Bar Harbor, ME 04609 United States |
Phone/Fax: |
(207) 288-6503 / (207) 288-6073 |
Email: |
[email protected] |
Abstract Theme: |
Molecular Basis of Muscle Dysfunction |
Author(s): |
Huebsch, Kimberly A (The Jackson Laboratory, Bar Harbor, ME 04609)
Kudryashova, Elena (Department of Neurology and Pediatrics, and Duchenne
Muscular Dystrophy Research Center, Los Angeles, CA 90095)
Wooley, Christine M (The Jackson Laboratory, Bar Harbor, ME 04609)
Sher, Roger B (The Jackson Laboratory, Bar Harbor, ME 04609)
Seburn, Kevin L (The Jackson Laboratory, Bar Harbor, ME 04609)
Spencer, Melissa J (Department of Neurology and Pediatrics, and Duchenne
Muscular Dystrophy Research Center, Los Angeles, CA 90095)
Cox, Gregory A (The Jackson Laboratory, Bar Harbor, ME 04609)
|
Body of Abstract: |
Human tibial muscular dystrophy (TMD) and limb-girdle muscular
dystrophy 2J (LGMD2J) are caused by mutations in the giant sarcomeric
protein titin (TTN) adjacent to a binding site for the muscle-specific
protease calpain 3 (CAPN3). Muscular dystrophy with myositis (mdm) is a
recessive mouse mutation with severe and progressive muscular
degeneration caused by a deletion in the N2A domain of titin
(TTN-N2A?83), disrupting a putative binding site for CAPN3. To determine
whether the muscular dystrophy in mutant mdm mice is caused by
misregulation of CAPN3 activity, genetic crosses with CAPN3
overexpressing transgenic (C3Tg) and CAPN3 knockout (C3KO) mice were
generated. Here we report that overexpression of CAPN3 exacerbates the
mdm disease, leading to a shorter lifespan and more severe muscular
dystrophy. However, in a direct genetic test of CAPN3’s role as a
mediator of mdm pathology, C3KO;mdm double mutant mice showed no change
in the progression or severity of disease indicating that aberrant CAPN3
activity is not a primary mechanism in this disease. To determine
whether we could detect a functional deficit in titin in a non-disease
state, we examined the treadmill locomotion of heterozygous +/mdm mice
and detected a significant increase in stride time with a concomitant
increase in stance time. Interestingly, these altered gait parameters
were completely corrected by CAPN3 overexpression in transgenic
C3Tg;+/mdm mice, supporting a CAPN3-dependent role for the N2A domain of
TTN in the dynamics of muscle contraction. |
|
Abstract Title: |
Identification of novel utrophin-interacting proteins |
Presenting/First Author: |
Humston, Jill L (Grad) |
Department, Institution: |
Physiology, University of Wisconsin-Madison |
Address: |
Rm 127 470 N. Charter St. Madison, WI 53706 United States |
Phone/Fax: |
608-265-3440 / (608) 265-5512 |
Email: |
[email protected] |
Abstract Theme: |
|
Author(s): |
Humston, Jill L (Graduate program in Molecular and Cellular
Pharmacology, University of Wisconsin, Madison, 53706)
Rybakova, Inna N (Department of Physiology, University of Wisconsin,
Madison, 53706)
Vestling, Martha M (Department of Chemistry, University of Wisconsin,
Madison, 53706)
Ervasti, James M (Department of Physiology, University of Wisconsin,
Madison, 53706)
|
Body of Abstract: |
Dystrophin and utrophin have a number of well-established molecular
partners. However, the large size and multi-domain structure of
dystrophin and utrophin lead us to hypothesize that novel interacting
proteins remain to be identified. We utilized full-length recombinant
Flag-utrophin as an affinity probe to isolate interacting proteins from
lysates of normal skeletal muscle. This pull-down approach was validated
by co-elution of syntrophin, a known dystrophin and utrophin binding
partner. Proteins specifically bound to Flag-utrophin were identified
based on the array of tryptic peptides detected by MALDI-TOF mass
spectrometry. Interestingly, we identified two proteins previously
localized to costameres, but not known to directly bind utrophin. We
also identified several proteins previously implicated in acetylcholine
receptor clustering at the neuromuscular junction, the primary location
of utrophin in normal muscle. Our results support the use of whole
protein a ffinity chromatography in combination with mass spectrometry
to identify new molecular partners of utrophin. This approach is also
directly applicable for identifying novel molecular partners of
full-length dystrophin. |
|
Abstract Title: |
Elevated gamma-actin in skeletal muscle alters expression of
genes associated with cellular metabolism |
Presenting/First Author: |
Jaeger, Michele A (Grad) |
Department, Institution: |
Physiology, University of Wisconsin-Madison |
Address: |
1300 University Ave Madison, WI 53706 United States |
Phone/Fax: |
608-265-3440 / 608-265-5512 |
Email: |
[email protected] |
Abstract Theme: |
Congenital Muscular Dystrophy and Nuclear Membrane Diseases |
Author(s): |
Jaeger, Michele A (Graduate Program in Cellular and Molecular
Biology, Univ. of Wisconsin-Madison)
Fitzsimons, Daniel P (Department of Physiology, Univ. of
Wisconsin-Madison)
Sonnemann, Kevin J (Department of Physiology, Univ. of
Wisconsin-Madison)
Mitchell, Stephanie (Research Center for Genetic Medicine, Children's
National Medical Center, Washington, DC)
Hoffman, Eric P (Research Center for Genetic Medicine, Children's
National Medical Center, Washington, DC)
Ervasti, James M (Department of Physiology, Univ. of Wisconsin-Madison)
|
Body of Abstract: |
Our lab has previously shown that cytoplasmic gamma-actin protein
levels are elevated 10-fold in dystrophin-deficient mdx skeletal muscle.
To determine the role of increased gamma-actin in the pathophysiology of
dystrophic muscle, we generated transgenic mice over-expressing
gamma-actin specifically in skeletal muscle. Force generation, levels of
necrosis, regeneration, and membrane damage in transgenic mice were not
different from wild-type, indicating that elevated gamma-actin does not
contribute to classic mdx pathology. However, microarray analysis of
wild-type, transgenic and mdx skeletal muscle indicated that elevated
levels of gamma-actin contribute to the altered transcriptional profiles
reported in mdx mice. The majority of genes differentially expressed in
both transgenic and mdx mice were associated with cellular metabolism.
Most interestingly, many nuclear-encoded mitochondrial transcripts were
down-regulated, suggesting that elevated gamma-actin ma y contribute to
the altered energy metabolism observed in mdx muscle.
This work was supported by the NIH (AR049899) and NRSA T32 HL07936 from
the UW Cardiovascular Research Center. |
|
Abstract Title: |
DM2 intronic expansions: evidence for CCUG accumulation without
flanking sequence or effects on ZNF9 mRNA processing or protein
expression |
Presenting/First Author: |
Jamie, Margolis M (Grad) |
Department, Institution: |
Genetics, Cell Biology and Genetics, University of Minnesota |
Address: |
MMC 206 Mayo 8206 420 Delaware Minneapolis, MN 55455 United States |
Phone/Fax: |
612-626-3521 / 612-625-8488 |
Email: |
[email protected] |
Abstract Theme: |
Molecular Basis of Muscle Dysfunction |
Author(s): |
Margolis, Jamie M (University of Minnesota, Minneapolis 55455)
Schoser, Benedikt G (Ludwig Maximilians University, Munich 80336)
Moseley, Melinda L (University of Minnesota, Minneapolis 55455)
Day, John W (University of Minnesota, Minneapolis 55455)
Ranum, Laura P (University of Minnesota, Minneapolis 55455)
|
Body of Abstract: |
Myotonic dystrophy type 2 (DM2) is caused by a large CCTG expansion
mutation (mean = 5,000 CCTGs; range=75-11,000) in intron 1 of the zinc
finger protein 9 (ZNF9) gene. Although an RNA gain of function mechanism
involving DM1 CUG or DM2 CCUG expansion transcripts is now well
established, still debated are the potential role that flanking
sequences within the DMPK 3’UTR may have on disease pathogenesis and
whether or not decreased expression of DMPK, ZNF9 or neighboring genes
at these loci contribute to disease. To address these questions in DM2,
we have examined the nucleic acid content of the ribonuclear inclusions
and the effects of these expansions on ZNF9 expression. Using cell lines
haploid and homozygous for the expansion and skeletal muscle biopsy
tissue, we demonstrate that pre-mRNAs containing large CCUG expansions
are normally spliced and exported from the nucleus, that the expansions
do not decrease ZNF9 expression at the mRNA or protein level, and that
the ribonuclear inclusions contain the CCUG expansion, but not flanking
intronic sequences. These data support a gain of function RNA model in
which the accumulation of the CCUG expansion itself is sufficient to
cause the multisystemic features of DM2. |
|
Abstract Title: |
Protective role of proteolytic clearance of troponin T fragments
in muscle cells |
Presenting/First Author: |
Jin, J.-P. (Faculty) |
Department, Institution: |
Medicine, Northwestern University |
Address: |
2650 Ridge Ave., SB515 Evanston, IL 60201 United States |
Phone/Fax: |
(847)570-1960 / (847)570-1865 |
Email: |
[email protected] |
Abstract Theme: |
Molecular Basis of Muscle Dysfunction |
Author(s): |
Jin, J.-P. (Northwestern University)
Wang, Xin (Northwestern University)
|
Body of Abstract: |
A nonsense mutation at codon Glu180 in the exon 11 of slow skeletal
muscle TnT gene causes an autosomal-recessive nemaline myopathy. The
truncated slow TnT has substantially lower affinity for binding to
tropomyosin due to the loss of one of two tropomyosin-binding sites.
Inefficient incorporation into myofilament resulted in the instability
of mutant slow TnT in the patient muscle. Rapid degradation of the
truncated slow TnT provides a protective mechanism to avoid potential
dominant-negative effect in careers.
Free TnT shows toxicity to cells. To investigate the role of the
proteolytic clearance in preventing cytotoxicity of non-incorporated TnT
in muscle cells, we studied expression and cellular toxicity of TnT. The
results demonstrated toxic effects of TnT fragments in both bacterial
and eukaryotic cells. Therefore, a peak release of TnT fragments during
acute myocardial infarction or skeletal muscle fatigue and injury may
impose toxic effects if it exceeds the proteolytic clearance capacity.
The potentially apoptotic effect of TnT fragments may be a pathogenic
factor in muscle diseases. To identify TnT peptide sequences responsible
for the toxic effect and to understand the underlying mechanism has a
clinical significance. |
|
Abstract Title: |
Selective deletion of the N-terminal variable region of cardiac
troponin T in ischemia-reperfusion by myofibril-associated ?-calpain
cleavage |
Presenting/First Author: |
Jin, J.-P. (Faculty) |
Department, Institution: |
Medicine, Northwestern University |
Address: |
2650 Ridge Ave., SB515 Evanston, IL 60201 United States |
Phone/Fax: |
847 570-1960 / 847 570-1865 |
Email: |
[email protected] |
Abstract Theme: |
Cardiac Pathology |
Author(s): |
Jin, J.-P. (Northwestern University)
Zhang, Zhiling (Northwestern University)
Biesiadecki, Brandon (Northwestern University)
|
Body of Abstract: |
An N-terminal truncated cardiac TnT(cTnT-ND) is found in myocardial
ischemia reperfusion. It is generated by selectively removing the
N-terminal variable region and preserving the conserved core structure
of TnT. Triton X-100 extraction of cardiac muscle strips promoted
production of cTnT-ND, indicating a myofibril-associated proteolytic
activity. Supporting a role of ?-calpain in producing cTnT-ND in
myocardial ischemia reperfusion, calpain inhibitors decreased the level
of cTnT-ND in Triton-extracted myofibrils. ?-calpain treatment of
cardiac myofibril effectively reproduced cTnT-ND. In contrast, ?-calpain
treatment of isolated cardiac TnT resulted in non-specific degradation,
suggesting that this restricted proteolysis of TnT is relevant to the
physiological structures of the myofilament. Triton X-100 treatment of
transgenic mouse cardiac myofibrils over-expressing fast skeletal muscle
TnT produced similar N-terminal truncations of the exogenous and
endogenous TnT. With the established functional effect of removing the
N-terminal variable region of TnT, this ?-calpain-mediated proteolytic
modification of TnT represents an acute mechanism to adjust muscle
contractility under stress conditions. |
|
Abstract Title: |
Dissecting the signaling and mechanical functions of the
dystrophin-glycoprotein complex |
Presenting/First Author: |
Judge, Luke M (Grad) |
Department, Institution: |
Neurology, University of Washington |
Address: |
1959 NE Pacific St. Room K233 HSC Seattle, WA 98195-7720 United
States |
Phone/Fax: |
(206) 221-5412 / (206) 616-8272 |
Email: |
[email protected] |
Abstract Theme: |
Molecular Basis of Muscle Dysfunction |
Author(s): |
Judge, Luke M (Univ. of Washington, Seattle, WA 98195)
Haraguchi, Miki (Univ. of Washington, Seattle, WA 98195)
Chamberlain, Jeffrey S (Univ. of Washington, Seattle, WA 98195)
|
Body of Abstract: |
DMD is caused by mutations in dystrophin, which is required for
assembly of the dystrophin-glycoprotein complex (DGC) and which provides
a mechanical link between the cytoskeleton and the extracellular matrix.
Several proteins in the DGC also participate in signaling cascades, but
the relative contribution of signaling and mechanical dysfunction to
myofiber necrosis is unclear. To examine this question we generated
transgenic mice that express the dystrophin isoform Dp116 in skeletal
muscle. Dp116 cannot link to the cytoskeleton but did assemble the DGC.
Expression of Dp116 mildly increased the severity of dystrophy in mdx4cv
muscle, likely due to displacement of utrophin from the sarcolemma.
Therefore, we crossed Dp116 transgenic mice with mice deficient for both
dystrophin and utrophin (mdx:utrn-/-). Dp116:mdx:utrn-/- muscles were
similarly dystrophic although muscle mass was increased compared to
control mdx:utrn-/-. Unexpectedly, expression of Dp116 pre vented growth
retardation, joint contractures, kyphosis, and premature death. We
propose that expression of Dp116 and restoration of the DGC does not
prevent myofiber necrosis but compensates for muscle damage by
maintaining muscle mass and regenerative capacity. |
|
Abstract Title: |
Regulation of Membrane-Associated Beta-Catenin by Calpain 3
During Terminal Stages of Myogenic Differentiation |
Presenting/First Author: |
Kramerova, irina (Faculty) |
Department, Institution: |
Neurology, UCLA |
Address: |
635 Charles Young Dr. South Los Angeles, CA 90095 United States |
Phone/Fax: |
(310)267-4582 / (310)206-1998 |
Email: |
[email protected] |
Abstract Theme: |
|
Author(s): |
Kramerova, Irina (Univ. of California, Los Angeles, CA 90095)
Kudryashova, Elena (Univ. of California, Los Angeles, CA 90095)
Wu, Benjamin (Univ. of California, Los Angeles, CA 90095)
Spencer, Melissa J (Univ. of California, Los Angeles, CA 90095)
|
Body of Abstract: |
Mutations in the cysteine protease calpain 3 (C3) cause LGMD2A. We
have showed that myoblasts isolates from C3 knockout (C3KO) mice were
able to fuse; however, sarcomere formation was disrupted. Here we show
that C3KO myotubes have an increased myonuclear index and that C3 acts
during myogenesis to specifically control levels of membrane-associated
but not cytoplasmic beta-catenin. In the absence of C3, beta-catenin
abnormally accumulates at the membrane coincident with increased levels
of M-cadherin. Given the role of M-cadherin in myoblast fusion, this
finding might explain increased myonuclear index in C3KO cultures.
Consistent with these observations, we found an increased myonuclei in
adult C3KO muscles even though the fibers are smaller than wild type. In
addition, replacement of beta1 integrin isoforms, that normally
accompanies myotube maturation, did not occur properly in C3KO myotubes.
However, this is not a primary defect since neither of these isoforms
are substrates for C3. These data suggest that the persistence of fusion
that we observed in C3KO cells, possibly due to accumulation of
beta-catenin and M-cadherin, inhibits subsequent steps of
differentiation such as integrin isoform switching and sarcomere
assembly. |
|
Abstract Title: |
Measuring calpain 3 proteolytic activity using an in vitro
substrate |
Presenting/First Author: |
Laure, Lydie (Grad) |
Department, Institution: |
UMR8115, Genethon |
Address: |
1, rue de l'internationale Evry, GA 91000 France |
Phone/Fax: |
33 1 69 47 28 85 / 33 1 60 77 86 98 |
Email: |
[email protected] |
Abstract Theme: |
|
Author(s): |
Laure, Lydie (Généthon, CNRS-UMR 8115, Evry 91000, France)
Milic, Astrid (Généthon, CNRS-UMR 8115, Evry 91000, France)
Daniele, Nathalie (Généthon, CNRS-UMR 8115, Evry 91000, France)
Lochmueller, Hanns (Friedrich-Baur-Institute, München, Germany)
Mora, Marina (Istituto Nazionale Neurologico “C. Besta”,, Milano,
Italy.)
Comi, Giacomo (Fondazione Ospedale Maggiore, Milano, Italy)
Moggio, Maurizio (Fondazione Ospedale Maggiore, Milano, Italy)
Richard, Isabelle (Généthon, CNRS-UMR 8115, Evry 91000, France) |
Body of Abstract: |
Limb-girdle muscular dystrophy type 2A (LGMD2A; OMIM 253600) is an
autosomal recessive muscular disorder caused by mutations in the gene
coding for calpain 3, a calcium-dependant protease. In order to improve
presently available LGMD2A diagnosis, we developed an in vitro assay
that can detect the proteolytic activity of calpain 3 in a muscle
sample. This assay is based on the use of an inactive calpain 3 that can
still be a substrate for active calpain 3 molecules that may be present
in the sample to be tested. A total of 80 human biopsies consisting of
43 LGMD2A muscles and 37 controls have been analyzed with this assay. In
all controls, normal calpain 3 level and activity were observed. A
reduced or absent proteolytic activity was found in 32 (74%) of the
LGMD2A biopsies. In the remaining 12 biopsies, normal proteolytic
activity was found despite the presence of calpain 3 mutation(s),
suggesting that other calpain 3 properties, possibly recognition of
substrates , should be impaired to give rise to the LGMD2A phenotype.
Although the false positive results are possible, we believe that this
assay is a quick and simple approach that improves LGMD2A diagnosis as
it is able to test at once several calpain 3 properties. |
|
Abstract Title: |
Myosin function in patients with a IIa myosin missense mutation
(Glu-706 to Lys). |
Presenting/First Author: |
Li, Mingxin (Grad) |
Department, Institution: |
Department of clinical neurophysiology, Academic Hospital, Uppsala
University |
Address: |
Akademiska Sjukhuset Ing 85, 3tr Uppsala, 751 85 Sweden |
Phone/Fax: |
+46(0)18 611 3432 / +01146(0)18 556 106 |
Email: |
[email protected] |
Abstract Theme: |
Molecular Basis of Muscle Dysfunction |
Author(s): |
Li, M. (Depart. of Clinical Neurophysiology, Uppsala Univ., Uppsala,
SE-75185, Sweden)
Lionikas, A. (Center for Developmental and Health Genetics, The
Pennsylvania State Univ., Univ. Park, Pennsylvania 16802, USA)
Yu, F. (Center for Developmental and Health Genetics, The Pennsylvania
State Univ., Univ. Park, Pennsylvania 16802, USA)
Tajshargi, H. (Depart. of Pathology, Sahlgrenska Univ. Hospital,
Goteborg, Sweden)
Oldfors, A. (Depart. of Pathology, Sahlgrenska Univ. Hospital, Goteborg,
Sweden)
Larsson, L. (Depart. of Clinical Neurophysiology, Uppsala Univ.,
Uppsala, SE-75185, Sweden)
|
Body of Abstract: |
Objective: Analyze the pathogenic events leading to the progressive
muscle weakness in the adults with a E706K mutation in the head of the
myosin heavy chain (MyHC) Methods: Maximum velocity of unloaded
shortening (V0) and maximum force normalized to fiber cross-sectional
area (specific tension) were measured in single cell segments. Myosin
function was also studied without the confounding influence of
structural and regulatory proteins in a single muscle fiber in vitro
motility assay. Sensitive electrophoretic methods were used to determine
MyHC isoform expression in the fiber segment. Results: A dramatic
impairment in the function of the IIa MyHC isoform was observed in the
single muscle fiber in vitro motility assay, while the other MyHC
isoforms were spared. Investigation of contractility at the single fiber
level revealed a dramatic decrease in the number of preparations
fulfilling the criteria for acceptance irrespective of MyHC isoform
expression. Conclu sions: The pathogenesis of the MyHC IIa E706K
myopathy involves defective function of the mutated myosin. The myopathy
encompasses alterations in the structural integrity of all muscle cells
irrespective of MyHC isoform expression. |
|
Abstract Title: |
Transfection of Adult Desmin-Null Muscles with GFP-Desmin Plasmid
Restores Sarcomere Alignment and Stress Generation |
Presenting/First Author: |
Lieber, Richard L (Faculty) |
Department, Institution: |
Orthopaedics and Bioengineering, University of California, San Diego |
Address: |
9500 Gilman Drive La Jolla, CA 92093-9151 United States |
Phone/Fax: |
858-534-0162 / 858-553-4381 |
Email: |
[email protected] |
Abstract Theme: |
Sarcomere Cytoskeleton |
Author(s): |
Lieber, Richard L (University of California, San Diego)
Palmisano, Michelle G (University of California, San Diego)
Bremner, Shannon (University of California, San Diego)
Shah, Sameer B (University of California, San Diego)
Ryan, Allen F (University of California, San Diego)
|
Body of Abstract: |
In the absence of desmin, muscles demonstrate pathology
characterized by a disorganized Z-disk and a 25% decrease in stress
produced. This could be due directly to the desmin loss or to secondary
changes due to development in the absence of desmin. We transfected
desmin-null muscles with a GFP-desmin plasmid to test the hypothesis
that reintroduction of desmin directly reverses these effects.
GFP-desmin plasmids were introduced into the desmin-null mice tibialis
anterior (TA) by electroporation. Muscle physiological testing was then
performed and passive mechanics were performed on single cells isolated
from these muscles while imaging by confocal microscopy.
Z-disk phase shift variance (i.e. “waviness" of Z-disk) was
significantly greater for desmin-null fibers (KO) (0.017±0.001 sq µm/µm)
and transfected desmin-null fibers not expressing GFP-desmin (KO-D)
(0.019±0.001), compared to wild-type (WT) (0.005±0.001) and transfected
desmin-null fibers expressing GFP-desmin (KO+D) (0.006±0.001; p<0.001).
Similarly, stress generated was significantly less for KO muscles
(160±41 kPa) and KO-D (146±85), compared to WT (205±32) and KO+D
(189±44; p<0.05). Stress generated was positively correlated with the
degree of transfection (r2=0.82,p<.0001).
These results show that the GFP-desmin chimeric protein integrated into
the myofibrillar lattice and reversed the structural and functional
alterations induced by the absence of desmin. |
|
Abstract Title: |
Alpha7 beta1 integrin promotes muscle cell adhesion,
proliferation and decreases apoptosis without disrupting normal
transcription |
Presenting/First Author: |
Liu, Jianming (Grad) |
Department, Institution: |
Department of Cell & Developmental Biolo, University of illinois at
urbana-champaign |
Address: |
B107 Chemical and Life Sciences Laboratory (CLSL), 601 S. Goodwin
Avenue urbana, IL 61801 United States |
Phone/Fax: |
(217) 333-6058 / (217) 244-1648 |
Email: |
[email protected] |
Abstract Theme: |
Therapies |
Author(s): |
Liu, Jianming (Department of Cell and Development Biology,University
of Illinois at Urbana- Champaign, Urbana, IL 61801)
Berry, Suzanne E (Department of Cell and Development Biology,University
of Illinois at Urbana- Champaign, Urbana, IL 61801)
Kaufman, Stephen J (Department of Cell and Development
Biology,University of Illinois at Urbana- Champaign, Urbana, IL 61801)
|
Body of Abstract: |
Alpha7 beta1 integrin is one of the two major complexes in skeletal
muscle that link laminin in the extracellular matrix and the actin
cytoskeleton. The integrin can functionally compensate for the loss of
the dystrophin-associated glycoprotein complex (DGC) in mice with severe
muscular dystrophy. Alleviation of dystrophy in mdx/utr(-/-) mice by
additional integrin alpha7 demonstrates the potential of enhanced
integrin as a therapy for muscular dystrophy. We report here that
inducible expression of 3-fold more integrin alpha7 in C2C12 myoblasts
promotes adhesion to laminin and proliferation. Apoptosis, resulting
from staurosoprin treatment, also decreases in the presence of more
integrin alpha7. Affymetrix array analysis shows that neither a 3-fold
increase of alpha7 integrin in C2C12 myoblasts nor a 8-fold increase in
skeletal muscle tissue alters their transcriptomes. We conclude that
enhanced integrin alpha7 expression in skeletal muscle does not disrupt
normal skeletal muscle transcription at levels that achieve functional
improvements in dystrophic mice. This suggests that increasing integrin
levels in muscular dystrophy may be therapeutic and without additional
side effects. Supported by the NIH and MDA. |
|
Abstract Title: |
NKT cells and Osteopontin Correspond with the Inflammatory
Response in Mdx Muscular Dystrophy |
Presenting/First Author: |
Lopez, Sylvia A (Grad) |
Department, Institution: |
Neurology and Pediatrics, University of California, Los Angeles |
Address: |
635 Charles E. Young Dr. South, NRB 404 Los Angeles, CA 90059 United
States |
Phone/Fax: |
(310) 267-4582 / (310) 206-1998 |
Email: |
[email protected] |
Abstract Theme: |
Molecular Basis of Muscle Dysfunction |
Author(s): |
Lopez, Sylvia A (David Geffen School of Medicine at UCLA, Los
Angeles, CA 90095 and Duchenne Muscular Dystrophy Research Center, UCLA)
Montecino-Rodriguez, Encarnacion (Department of Pathology and Laboratory
Medicine and Duchenne Muscular Dystrophy Research Center, UCLA)
Wu, Ben G (David Geffen School of Medicine at UCLA, Los Angeles, CA
90095 and Duchenne Muscular Dystrophy Research Center, UCLA)
Kramerova, Irina (David Geffen School of Medicine at UCLA, Los Angeles,
CA 90095 and Duchenne Muscular Dystrophy Research Center, UCLA)
Kudryashova, Elena (David Geffen School of Medicine at UCLA, Los
Angeles, CA 90095 and Duchenne Muscular Dystrophy Research Center, UCLA)
Hoffman, Eric P (Childrens National Medical Center, Washington D.C.)
Micelli, Carrie (Department of Microbiology and Molecular Genetics,
UCLA)
Spencer, Melissa (David Geffen School of Medicine at UCLA, Los Angeles,
CA 90095 and Duchenne Muscular Dystrophy Research Center, UCLA) |
Body of Abstract: |
Muscle inflammation is a secondary feature that exacerbates Duchenne
Muscular Dystrophy (DMD). The goal of this investigation was to
characterize immune cells infiltrating dystrophic muscle with the
purpose of identifying specific T cell populations that might be
targeted for immunotherapeutics. Flow cytometry of purified lymphocytes
from mdx mice showed that the Vbeta8.1/8.2 T cell receptor (TCR)
rearrangement represented approximately 30% of all T cells and that
these Vbeta8.1/8.2 cells expressed NK cell surface markers, suggesting
that they are NKT cells. Cell sorting confirmed that Vbeta8.1/8.2+ cells
expressed the invariant Valpha14 TCR chain and MIP-2, a chemokine not
expressed by conventional T cells. Sorted NKT cells also expressed
osteopontin (OPN), a pro-inflammatory cytokine. Examination of DMD
biopsies confirmed the presence of both NKT cells and OPN.
Interestingly, OPN was highly expressed by invading immune cells and
muscle fibers. Mdx mice were trea ted with asialo GM1, an antibody that
inhibits NK and NKT cell activity. This treatment caused reductions in
serum OPN and splenic IL-4. These studies suggest that NKT cells
infiltrate dystrophic muscle and express cytokines that modulate the
immune response. |
|
Abstract Title: |
Differences in myogenesis and sarcolemmal repair after single and
repetitive muscle strains |
Presenting/First Author: |
Lovering, Richard M (Faculty) |
Department, Institution: |
Physiology, Univ of Maryland, School of Medicine, Dept. of
Physiology |
Address: |
685 W. Baltimore St., HSF-1, Rm 580 Baltimore, MD 21201 United
States |
Phone/Fax: |
410-409-1077 / 410-706-8341 |
Email: |
[email protected] |
Abstract Theme: |
Plasma Membrane Stability/Repair |
Author(s): |
Lovering, Richard M (University of Maryland School of Medicine,
Baltimore, MD)
Roche, Joseph A (University of Maryland School of Medicine, Baltimore,
MD)
Bloch, Robert J (University of Maryland School of Medicine, Baltimore,
MD)
De Deyne, Patrick G (DePuy Biologics/Soft Tissue Technologies, Raynham,
MA)
|
Body of Abstract: |
We determined if myogenic cell proliferation in skeletal muscle was
equally important to recovery of contractile function after different
contraction-induced injuries. Tibialis anterior (TA) muscles of
anesthetized male rats were injured by a single lengthening contraction
under large strain (1R), or multiple lengthening contractions under
small strain (MR). Gamma irradiation was used to prevent proliferation.
Maximal tetanic tension was assessed after injury and on days 3, 7, 14,
and 21 during recovery. Both 1R and MR protocols caused comparable
injuries, as measured by a loss of force, but irradiation inhibited
recovery of force only after the MR protocol. Centrally nucleated fibers
were only present after MR, and only in unirradiated muscle. Evans blue
dye injected before injury was retained by myofibers recovering from 1R,
but was lost after MR. Dye-labeled fibers after 1R initially lost
sarcolemmal dystrophin, but eventually regained it, although they
retained dye. Our results suggest that myogenesis is necessary for
recovery after multiple lengthening contractions, but not after a single
maximal lengthening contraction. Instead, recovery after 1R involves
membrane resealing and replacement of damaged proteins. |
|
Abstract Title: |
Body-wide restoration of functional levels of dystrophin by
intravenous delivery of antisense oligonucleotides alleviates pathology
in dystrophic mice |
Presenting/First Author: |
Lu, Qi L (Faculty) |
Department, Institution: |
Muscular Dystrophy Laboratory, Carolinas Medical Center |
Address: |
1542 Garden Terrace Charlotte, NC 28203 United States |
Phone/Fax: |
7043551701 / 7043551679 |
Email: |
[email protected] |
Abstract Theme: |
Therapies |
Author(s): |
Lu, Qi L (Qi Long Lu, Carolinas Medical Center, Charlotte, NC, USA)
Alter, Julia (Julia Alter, Imperial College, London Univ. London, UK)
Lou, Fang (Fang Lou, Univ. Hertfordshire, UK)
Partridge, Terence A (Terence A. Partridge, Children's National Medical
Center, Washington DC)
|
Body of Abstract: |
Duchenne muscular dystrophy (DMD) results from non-sense or
frame-shifting mutations in the dystrophin gene. The majority of these
mutations can be corrected by antisense oligonucleotide (AON)-mediated
exon skipping, which creates shortened, but in-frame transcripts and
produces at least partially functional proteins. 2’-O-methyl
phosphorothioate AONs (2OMeAONs) induced functional levels of dystrophin
within individual muscles by local injection, but therapeutically
inadequate levels of dystrophin in body-wide skeletal muscles when
delivered systemically. With several different chemistries for AON, it
is now possible to induce dystrophin expression up to levels in
individual muscles with functional significance. Importantly, methods of
systemic delivery applicable to clinic is able to restore dystrophin
expression up to 50% of normal level in all skeletal muscles with clear
indications of functional improvements including reduced rates in
central nucleation of mus cle fibers, improved force generation and
decreased serum CK levels. Thus exon skipping provides a realistic hope
for the treatment of a majority of DMD patients. |
|
Abstract Title: |
Congenital Myopathy with Internal Myonuclei and Perinuclear
Aggregates: Reducing Body Myopathy without cytoplasmic bodies? |
Presenting/First Author: |
Maiti, Baijayanta (Grad) |
Department, Institution: |
Human Genetics, University of Utah |
Address: |
533 EIHG, 15 N 2030 E Salt Lake City, UT 84112 United States |
Phone/Fax: |
801-585-0246 / 801-581-6463 |
Email: |
[email protected] |
Abstract Theme: |
Congenital Muscular Dystrophy and Nuclear Membrane Diseases |
Author(s): |
Maiti, Baijayanta (Dept. of Human Genetics, University of Utah)
Chin, Steven S (Dept. of Pathology, University of Utah School of
Medicine)
Flanigan, Kevin M (Depts. of Human Genetics, Pathology, and Neurology,
University of Utah School of Medicine)
|
Body of Abstract: |
Reducing body myopathy (RBM) is a rare congenital disorder marked by
cytoplasmic reducing bodies (RBs) and dense perinuclear osmiophilic
aggregates. We report the clinical and pathological findings from two
cases of congenital myopathy. One shows the classic features of RBM; the
other shows RBM-like perinuclear aggregates, but no cytoplasmic RBs.
Case 1 presented with weakness by age 2. Biopsy at age 4 revealed
non-specific myopathic changes but no reducing bodies. Biopsy 16 months
later revealed widespread cytoplasmic reducing bodies, seen by both
light and electron microscopy, and typical perinuclear aggregates. Case
2 is the more severely affected of two siblings with weakness. Muscle
biopsy at age 2 and again at age 8 showed the presence of many internal
nuclei, and no cytoplasmic bodies. Electron microscopy revealed many
nuclei surrounded by perinuclear aggregates typical of RBM. This may be
a variant of RBM, or it may represent RBM in evolution, with the
presence of perinuclear aggregation as the earliest feature preceding
development of cytoplasmic RBs. However, given the absence of RBs in
serial biopsies (six years apart) in a profoundly weak patient, this may
represent a novel congenital myopathy. |
|
Abstract Title: |
Myotonic dystrophy type 2: a reversible multisystemic murine
model of CCUG RNA toxicity |
Presenting/First Author: |
Margolis, Jamie M (Grad) |
Department, Institution: |
Genetics, Cell Biology and Genetics, University of Minnesota |
Address: |
MMC 206 Mayo 8206 420 Delaware Minneapolis, MN 55455 United States |
Phone/Fax: |
612-626-3521 / 612-625-8488 |
Email: |
[email protected] |
Abstract Theme: |
Molecular Basis of Muscle Dysfunction |
Author(s): |
Margolis, Jamie M (University of Minnesota, Minneapolis 55455)
Kang, Yuan-Lin (University of Minnesota, Minneapolis 55455)
Day, John W (University of Minnesota, Minneapolis 55455)
Ranum, Laura P (University of Minnesota, Minneapolis 55455)
|
Body of Abstract: |
Myotonic dystrophy type 2 (DM2) is caused by a large CCTG repeat in
intron 1 of the zinc finger protein 9 gene. There is growing evidence
that DM1 and DM2 are caused by an RNA gain of function mechanism in
which the repeats themselves cause the multisystemic features of these
diseases. To investigate the role that expression of the CCUG
transcripts has on the DM phenotype, we developed a tetracycline
inducible murine model of DM2. The expression of a CCTG-300 is driven by
a tet-responsive element minimal CMV promoter as part of a non-coding
transcript. These TRE-CCTG expansion lines were crossed to CMV driven
tet activator mice, creating doubly transgenic mice that ubiquitously
express the CCUG expansion. H&E staining of muscle from these doubly
transgenic animals shows variation in fiber size and centrally located
nuclei. Additionally, skeletal muscle shows ribonuclear inclusions, and
aberrant splicing of the insulin receptor. In a separate series of
experiments the TRE-CCUG expansion lines will be crossed to two
different BAC transgenics engineered to drive expression of the tTA
using the endogenous human DMPK or ZNF9 promoters to determine how
differences in the expression pattern of the repeat affect the
phenotype. |
|
Abstract Title: |
Titin-cap knockdown by RNA interference inhibits myogenic
regulatory factors in C2C12 cells |
Presenting/First Author: |
Markert, Chad D (Postdoc - Degree Year: 2004) |
Department, Institution: |
Veterinary Biosciences, University of Missouri--Columbia |
Address: |
1600 E Rollins Rd, Rm E102 Columbia, MO 65211 United States |
Phone/Fax: |
573-884-6731 / 573-884-6890 |
Email: |
[email protected] |
Abstract Theme: |
Regulation of Muscle Mass |
Author(s): |
Markert, Chad (Department of Biomedical Sciences, College of
Veterinary Medicine, Univ. of Missouri--Columbia)
Ning, Jie (Department of Biomedical Sciences, College of Veterinary
Medicine, Univ. of Missouri--Columbia)
Zhu, Zhifang (Department of Biomedical Sciences, College of Veterinary
Medicine, Univ. of Missouri--Columbia)
Staley, JT (Department of Physical Medicine and Rehabilitation, Univ. of
Missouri--Columbia)
Stoker, Aaron (Department of Veterinary Medicine and Surgery, Univ. of
Missouri--Columbia)
Omolewu, Rachel Gee, James M (The Dalton Cardiovascular Research Center,
Univ. of Missouri--Columbia)
Childers, Martin K (Department of Physical Medicine and Rehabilitation,
Univ. of Missouri--Columbia) |
Body of Abstract: |
Null mutation of titin-cap (T-cap) causes limb-girdle muscular
dystrophy type 2G (LGMD2G). Patients with LGMD2G develop muscle wasting
and weakness, and lose the ability to walk by the third decade. Previous
findings suggest that T-cap regulates myostatin, a key regulator of
muscle growth. PURPOSE: We tested the hypothesis that T-cap knockdown
with RNA interference increases myostatin level and leads to impaired
muscle cell differentiation. METHODS: C2C12 myoblasts were grown to
confluence in GM (0 D) and then shifted to DM for 5 Days. Cells were
treated with T-cap siRNA duplex constructs and analyzed for RNA and
protein expression using Northern blots, real-time RT-PCR and Western
immunoblots. RESULTS: siRNA treatment decreased T-cap RNA (p<0.05) and
protein expression in differentiating muscle cells. Subsequent
expression of myostatin increased, while decreases were observed in the
myogenic regulatory factors MyoD and myogenin. CONCLUSIONS: Our findings
suppo rt the hypothesis that T-cap knockdown with RNA interference
increases myostatin levels and impairs normal muscle cell
differentiation. This process likely occurs by repression of myogenic
regulatory factors. Funded, in part, by the MU Research Board. |
|
Abstract Title: |
Clinico-pathological Spectrum of FKRP Related Diseases |
Presenting/First Author: |
Muntoni, Francesco (Faculty) |
Department, Institution: |
Pediatrics, Imperial College, Hammersmith Hospital |
Address: |
Du Cane Road London, W12ONN England |
Phone/Fax: |
00442083833295 / 00442087462187 |
Email: |
[email protected] |
Abstract Theme: |
Congenital Muscular Dystrophy and Nuclear Membrane Diseases |
Author(s): |
Muntoni, Francesco (Department of Pediatrics, Imperial College,
Hammersmith Hospital, London, England)
Brockington, Martin (Department of Pediatrics, Imperial College,
Hammersmith Hospital, London, England)
Torelli, Silvia (Department of Pediatrics, Imperial College, Hammersmith
Hospital, London, England)
Kaluarachchi, Manuja R (Department of Pediatrics, Imperial College,
Hammersmith Hospital, London, England)
Brown, Susan C (Department of Pediatrics, Imperial College, Hammersmith
Hospital, London, England)
|
Body of Abstract: |
Defective glycosylation of alpha dystroglycan is a recently
identified mechanism responsible for muscular dystrophy (MD). Mutations
in 6 glycosyltransferases result in different conditions, ranging in
severity from congenital onset MD and severe brain and eye structural
involvement, to onset of weakness in adolescence or adult life.
Originally severity was thought to be dependent on the mutated gene i.e.
POMT1; POMT2; POMGnT1; fukutin; FKRP or LARGE. However, recent data
suggests that phenotype is due to the effect of the mutation on the
enzymatic function of the protein rather than the gene involved.
Mutations in FKRP are the best example of this spectrum of phenotypes
which range from Walker-Warburg severity to adult onset LGMD2I. At the
protein level the expression of the glycosylated alpha-dystroglycan
broadly correlates with disease severity suggesting a direct or indirect
role for FKRP in dystroglycan processing. We have studied the
sub-cellular localization of FKRP using different antibodies; and
performed in-situ hybridization studies on its pattern of expression in
the brain. These studies will improve our understanding of the
functional role of FKRP and provide us with insight into the
pathogenesis of FKRP-related MDs. |
|
Abstract Title: |
Early increases in 20s Proteasome activity in fast and slow
twitch muscle of rats exposed to moderate psychological stress |
Presenting/First Author: |
Myburgh, Kathryn H (Faculty) |
Department, Institution: |
Physiological Sciences, Stellenbosch University |
Address: |
Merriman Avenue Stellenbosch, 7602 South Africa |
Phone/Fax: |
27 21 8083149 / 27 21 8083145 |
Email: |
[email protected] |
Abstract Theme: |
Regulation of Muscle Mass |
Author(s): |
Myburgh, Kathryn H (Univ. Stellenbosch, Stellenbosch 7602, South
Africa)
Neethling, Ian (Univ. Stellenbosch, Stellenbosch 7602, South Africa)
Smith, Carine (Univ. Stellenbosch, Stellenbosch 7602, South Africa)
|
Body of Abstract: |
We exposed adult male Wistar rats to incremental, intermittent
stress to determine the effect on skeletal muscle 20s proteasome
activity and atrophy of the soleus and extensor digitorum longus (EDL).
Six control rats had no intervention (C). Six rats were exposed to
restraint stress for 7 days (S7). Group S14, exposed to the same stress
in wk 1, had restraint stress or randomly applied novel stressors (cage
tilt; soiled bedding; tail exposure to heat) in wk 2. Stress exposure
was 30 min for days 1-2, increasing to 3x 30 min for days 5-14. A 4th
group, stressed similarly to S14, also exercised carrying weights in wk
2 (S14E7-14).
After 1 wk, S7 lost 47 ±15 g (8 %) of body mass with no change in C
(P<0.01). But, soleus to body mass ratio (C: 0.45 ±0.06 vs. S7: 0.49
±0.03 mg/g) and EDL to body mass ratio (C: 0.42 ±0.09 vs. S7: 0.42 ±0.03
mg/g) did not differ. Stress exposure increased 20s proteasome activity
by 24.8% in soleus and 39.2% in EDL (both P<0.05). S14 and S14E7-14
results will be available shortly.
Preliminary evidence suggests that moderate psychological stress
upregulates the 20s proteasome before atrophy.
Approval: Univ Research Ethics Committee; Funding: National Research
Foundation |
|
Abstract Title: |
Aberrant splicing of dystrophin and alpha-dystrobrevin in
myotonic dystrophy |
Presenting/First Author: |
Nakamori, Masayuki (Grad) |
Department, Institution: |
neurology, Osaka university graduate school of medicine |
Address: |
2-2, D-4 Suita, Osaka, 565-0871 Japan |
Phone/Fax: |
81-6-6879-3571 / 81-6-6879-3579 |
Email: |
[email protected] |
Abstract Theme: |
Sarcolemmal Excitability |
Author(s): |
Nakamori, Masayuki (Osaka Univ., Suita 565-0871, Japan)
Kimura, Takashi (Osaka Univ., Suita 565-0871, Japan)
Fujimura, Harutoshi (Toneyama National Hospital, Toyonaka 560-8552,
Japan)
Aoike, Futoshi (Osaka Univ., Suita 565-0871, Japan)
Takahashi, Masanori P (Osaka Univ., Suita 565-0871, Japan)
Sakoda, Saburou (Osaka Univ., Suita 565-0871, Japan)
|
Body of Abstract: |
In myotonic dystrophy type 1 (DM1), misregulation of alternative
mRNA splicing has been attributed to some of its clinical features
including myotonia. However, the cause of muscle wasting, a core symptom
of DM, has still been unknown. The abnormalities of cytoskeletal
proteins are responsible for some forms of progressive muscular
dystrophies. Alpha-dystrobrevin (DB), a component of
dystrophin-associated protein complex, and dystrophin have been shown to
have alternative splicing isoforms. Therefore, we examined the splicing
abnormalities of these cytoskeletal proteins in muscles from DM1 using
RT-PCR. We also quantified the mRNA and protein for DB by real time PCR
and Western blot. We found significant existence of alternatively
spliced isoforms of dystrophin and DB in DM1. The total amount of mRNA
for DB2 was significantly increased in DM1 than in control. Moreover the
expression of aberrantly spliced DB isoform was confirmed using a
specific antibody. These re sults suggest the possibility of functional
defect in structural proteins in DM1 muscle, which might results in
structural vulnerability of the sarcolemma or disturbance of signaling
pathway.
Supported by Ministry of Health, Labour and Welfare, Japan (17A-10) and
JSPS. |
|
Abstract Title: |
Role of the MEF2-regulated gene myospryn in striated muscle |
Presenting/First Author: |
Naya, Frank J (Faculty) |
Department, Institution: |
Biology, Boston University |
Address: |
24 Cummington Street Boston, MA 02215 United States |
Phone/Fax: |
617-353-2469 / 617-353-6340 |
Email: |
[email protected] |
Abstract Theme: |
Sarcomere Cytoskeleton |
Author(s): |
Naya, Frank J (Boston University, Boston, MA 02215)
Reynolds, Joseph G (Boston University, Boston, MA 02215)
McCalmon, Sarah (Boston University, Boston, MA 02215)
Tomczyk, Thomas (Boston University, Boston, MA 02215)
|
Body of Abstract: |
The MEF2 transcription factor plays an important role in muscle gene
expression and differentiation. A novel MEF2-regulated gene, myospryn,
was identified by our lab by expression profiling using mef2a knockout
mice which exhibit severe cytoarchitectural defects in cardiac muscle.
The myospryn gene encodes a muscle-specific protein that interacts with
alpha-actinin and is localized to the costamere, an elaborate protein
network at the periphery of the Z-disc. Myospryn interacts with
dysbindin which itself associates with alpha-dystrobrevin, a protein
within the dystrophin-glycoprotein complex (DGC). Furthermore, myospryn
transcripts are down-regulated in dystrophic muscle. A recent
bioinformatics analysis by our lab has revealed that Myospryn is related
to the protein kinase A (PKA) anchoring protein (AKAP) family. Indeed,
co-immunoprecipitation assays have shown a direct interaction between
Myospryn and PKA. Moreover, immunostaining of adult mouse skeletal
muscle shows co-localization of endogenous Myospryn and PKA. These
studies set the foundation for further investigating the potential role
of Myospryn directing PKA signaling events to modulate the function of
the DGC. Supported by NIH/NHLBI R01 HL73304. |
|
Abstract Title: |
Morphology, and EDL stress production and passive mechanical
properties of maturing mdx and mdx:utrophin-/- mice |
Presenting/First Author: |
Niday, Ashley K (Faculty) |
Department, Institution: |
HNFE, Virginia Tech |
Address: |
338 Wallace Hall Blacksburg, VA 24060 United States |
Phone/Fax: |
540-231-9048 / 540-231-3916 |
Email: |
[email protected] |
Abstract Theme: |
Congenital Muscular Dystrophy and Nuclear Membrane Diseases |
Author(s): |
Niday, Ashley K (Dept. of Engineering Science and Mechanices,
Blacksburg, VA 24060)
Wolff, Andrew V (Dept. of Mechanical Engineering, Blacksburg, VA 24060)
Voelker, Kevin A (Dept. of Human Nutrition, Foods and Exercise,
Blacksburg, VA 24060)
Call, Jarrod A (Dept. of Human Nutrition, Foods and Exercise,
Blacksburg, VA 24060)
Evans, Nick P (Dept. of Human Nutrition, Foods and Exercise, Blacksburg,
VA 24060)
Granata, Kevin P (Dept. of Engineering Science and Mechanices,
Blacksburg, VA 24060)
Grange, Robert W (Dept. of Human Nutrition, Foods and Exercise,
Blacksburg, VA 24060)
|
Body of Abstract: |
The purpose of this study was to (1) profile body mass, and extensor
digitorum longus (EDL) muscle mass and length and, (2) determine stress
production and passive mechanical properties (i.e., stiffness and
damping) of maturing Control (C), mdx (M) and mdx: utrophin-/- (M:U-/-)
EDL at ages 14-, 21-,28- and 35-d. Our aim was to identify specific ages
for more detailed analysis of disease mechanisms. EDL muscles were
subjected to passive stretch protocols in vitro. Force profiles were fit
to a 3 parameter viscoelastic muscle model. At 14-d, all physical
characteristics across the 3 genotypes were similar; at ages 21-35-d C
and M:U-/- were similar, but at 21-d, M body and muscle masses were
larger than C and M:U-/- values (P≤0.05). Stress production at 14 and
28-d was similar for all genotypes, but was depressed for M:U-/- vs C at
21-d, and for M and M:U-/- vs C at age 35-d (P≤0.05). Series elastic
stiffness of the 3 genotypes were not different at ages 14-28-d, but M
series stiffness was greater at 35-d vs C. M parallel elastic stiffness
was similar to C at each age, except at 28-d (>C; P≤0.05). These time
course data will be useful to target specific ages to explore dystrophic
mechanisms. Research supported by NIH grant AR049881. |
|
Abstract Title: |
Transcription factors in atrophy caused by post-synaptic block of
neuromuscular transmission and muscle unloading in rats muscle |
Presenting/First Author: |
Nordquist, Jenny (Postdoc - Degree Year: 2002) |
Department, Institution: |
Neuroscience, Uppsala University |
Address: |
Akademiska sjukhuset, ing. 85, 3 tr Uppsala, 751 85 Sweden |
Phone/Fax: |
+46 18 611 34 32 / +46 18 55 61 06 |
Email: |
[email protected] |
Abstract Theme: |
|
Author(s): |
Nordquist, Jenny (Department of Neuroscience, Clinical
Neurophysiology, Uppsala University, Sweden.)
Höglund, Anna-Stina (Department of Neuroscience, Clinical
Neurophysiology, Uppsala University, Sweden.)
Norman, Holly (Department of Neuroscience, Clinical Neurophysiology,
Uppsala University, Sweden.)
Dworkin, Barry (Hershey Medical Center, Hershey, Pennsylvania, USA)
Larsson, Lars (Department of Neuroscience, Clinical Neurophysiology,
Uppsala University, Sweden.)
|
Body of Abstract: |
The muscle wasting associated with modern intensive care has a
negative effect on rehabilitation and quality of life in patients
recovering from critical illness. To identify the mechanisms behind this
form of muscle wasting, we analysed the nuclear concentrations of a
number of transcription factors in extensor digitorum longus (EDL) and
soleus muscles in a rat intensive care unit (ICU) model. The rats were
sedated, treated with a post-synaptic neuromuscular blocker and
mechanically ventilated for 7-14 days. A significant muscle wasting and
an up-regulation of the ubiquitin ligases MAFbx and MuRF1 followed the
treatment. Bcl-3 displayed a concomitant decrease in concentration,
suggesting kB controlled gene expression not involving NFkB p65. The
nuclear levels of GR and TRalpha1 were altered and are also suggested as
potential mediators of the MAFbx- and MuRF1-induction in the absence of
induced Foxo1. We believe that this model, and the strategy of
quantifying nu clear proteins, will provide a valuable tool for further,
more detailed, analyses of the muscle wasting occurring in patients kept
on a mechanical ventilator.
The study was supported by NIH (AR45627, AR47318, AG14731), AFM and the
Swedish Research Council (8651). |
|
Abstract Title: |
Longitudinal measurements of myofibrillar protein and mRNA
expression in patients with Acute Quadriplegic Myopathy |
Presenting/First Author: |
Norman, Holly (Grad) |
Department, Institution: |
Neurophysiology, Uppsala University |
Address: |
Akademiska Sjukhuset, Ing 85, 3 tr Uppsala, 751 85 Sweden |
Phone/Fax: |
46-18-6113432 / 46-18-556106 |
Email: |
[email protected] |
Abstract Theme: |
|
Author(s): |
Norman, H (Uppsala University, Uppsala, Sweden)
Andersson, P (Uppsala University, Uppsala, Sweden)
Nordquist, J (Uppsala University, Uppsala, Sweden)
Zackrisson, H (Karolinska Institute, Stockholm, Sweden)
Larsson, L (Uppsala University, Uppsala, Sweden)
|
Body of Abstract: |
Acute Quadriplegic Myopathy (AQM) is an acquired myopathy caused by
pharmacological treatment used in anaesthesiology and the intensive care
and is characterized by severe muscle wasting and paralysis, and a loss
of myosin (MyHC) and myosin binding proteins (MyBP). Degradation of
thick filament proteins has been suggested to cause the muscle wasting
in AQM. Based on previous observations in our group we hypothesize that
downregulation of proteins synthesis at the transcriptional level is
equally important in causing the loss of muscle mass and myofibrillar
proteins. Therefore myofibrillar protein and mRNA expression, i.e.,
MyHC, actin, and MyBP, were measured during the acute and recovery
stages of AQM. At the protein level, a loss of MyHC and MyBP was
observed during muscle paralysis according to immunoblots and gel
electrophoreses. Protein levels returned to normal after 1-2 months
recovery. At the transcriptional level, decreased levels of mRNA for the
domi nating MyHC isoforms and actin, but not for the MyBP, were observed
during the acute stage of AQM according to real-time PCR. It is
suggested that the decreased MyHC synthesis at the transcriptional level
is a strong contributing factor in the development of AQM. |
|
Abstract Title: |
Impact of chronic post-synaptic block of neuromuscular
transmission, muscle unloading and mechanical ventilation on skeletal
muscle protein and mRNA expression |
Presenting/First Author: |
Norman, Holly S (Grad) |
Department, Institution: |
Clinical Neurophysiology, Uppsala University |
Address: |
Inst f Neurovetenskap, klinisk neurofysiologi, Akademiska Sjukhuset,
Ing 85, 3tr Uppsala, 751 85 Sweden |
Phone/Fax: |
011-46-18-6113432 / 011-46-18-556106 |
Email: |
[email protected] |
Abstract Theme: |
Molecular Basis of Muscle Dysfunction |
Author(s): |
Norman, Holly (Uppsala University, Uppsala, Sweden)
Nordquist, J (Uppsala University, Uppsala, Sweden)
Andersson, P (Uppsala University, Uppsala, Sweden)
Ansved, T (Karolinska Institute, Stockholm, Sweden)
Tang, X (Hershey Medical Center at the Pennsylvania State University
College of Medicine, Hershey, Pennsylvania)
Dworkin, B (Hershey Medical Center at the Pennsylvania State University
College of Medicine, Hershey, Pennsylvania)
Larsson, L (Uppsala University, Uppsala, Sweden)
|
Body of Abstract: |
We developed a rodent model to study muscle atrophy found in the
intensive care unit (ICU). Rats were paralyzed by block of neuromuscular
transmission (NMB) and mechanically ventilated for 1-2 weeks. The
effects on protein and mRNA expression of sarcomeric proteins, i.e.,
myosin heavy chain (MyHC), actin, myosin binding proteins -C (MyBP-C)
and - H (MyBP-H) in fast- and slow-twitch limb, respiratory and
masticatory muscles, were studied. At the protein level, a decreased
MyHC:actin ratio was observed in both fast- and slow-twitch hindlimb, a
masticatory and in one respiratory (intercostal) muscles, but not in the
other (diaphragm). At the mRNA level, decreased expression of MyHC
isoform(s) was observed in the hindlimb and intercostal muscles, but not
in the diaphragm and masseter. The MyBP-C mRNA expression was decreased
in the limb muscles, but otherwise remained unaffected, whereas MyBP-H
increased for all muscles. Differing effects on protein and mRNA expre
ssion between the ICU model and a model with denervated hindlimb muscles
are also reported. The NMB rat is a useful model for studying muscle
wasting and impaired muscle function in immobilized ICU patients. |
|
Abstract Title: |
A gene for speed: The ACTN3 R577X polymorphism influences muscle
performance |
Presenting/First Author: |
North, Kathryn N (Faculty) |
Department, Institution: |
Neurogenetics, University of Sydney |
Address: |
Hawkesbury Road, Westmead Sydney, 2145 Australia |
Phone/Fax: |
+61-438-601654 / +61-2-98453389 |
Email: |
[email protected] |
Abstract Theme: |
Sarcomere Cytoskeleton |
Author(s): |
North, Kathryn N (University of Sydney, NSW, Australia)
Macarthur, Daniel G (University of Sydney, NSW, Australia)
Yang, Nan (Children's Hospital at Westmead, Sydney, NSW, Australia)
Seto, Jane T (Children's Hospital at Westmead, Sydney, NSW, Australia)
Raftery, Joanna (Children's Hospital at Westmead, Sydney, NSW,
Australia)
Kee, Anthony J (Children's Medical Research Institute, Sydney, NSW,
Australia)
Hardeman, Edna C (Children's Medical Research Institute, Sydney, NSW,
Australia)
Gunning, Peter W (Children's Hospital at Westmead, Sydney, NSW,
Australia) |
Body of Abstract: |
Alpha-actinin-3 is a component of the Z-disc in fast skeletal muscle
fibres. Intriguingly, a common nonsense variant in the human ACTN3 gene
(R577X) results in complete deficiency of alpha-actinin-3 in ~18% of the
general population.We have recently demonstrated a significantly lower
frequency of XX homozygotes amongst elite sprint athletes, suggesting
that the presence of alpha-actinin-3 is required for optimal fast fibre
function. This finding has been supported by a number of recent studies
demonstrating associations between R577X genotype and muscle strength
and response to training. The ACTN3 R577X polymorphism thus represents a
genetic factor influencing muscle performance in humans.
We have developed an ACTN3 KO mouse model that replicates human
alpha-actinin-3 deficiency. The closely related protein, α-actinin-2, is
able to compensate for the absence of α-actinin-3 in sarcomere assembly
and function at baseline physiological conditions. However, there is a
marked increase in sarcomeric damage following eccentric exercise in KO
mice compared to WT, suggesting that α-actinin-3 protects muscle from
exercise-induced damage, and explaining the association between R577X
and muscle function in humans. |
|
Abstract Title: |
Unravelling the thin filament: mechanisms of weakness in
intranuclear rod myopathy |
Presenting/First Author: |
North, Kathryn N (Faculty) |
Department, Institution: |
Neurogenetics, University of Sydney |
Address: |
Children's Hospital, Hawkesbury Road, Westmead Sydney, 2145
Australia |
Phone/Fax: |
+61-438-601654 / +61-2-98453389 |
Email: |
[email protected] |
Abstract Theme: |
Molecular Basis of Muscle Dysfunction |
Author(s): |
North, Kathryn N (University of Sydney, NSW, Australia)
Domazetovska, Ana (University of Sydney, NSW, Australia)
Ilkovski, Biljana (Chidren's Hospital at Westmead, Sydney, Australia)
Valova, Val A (Children's Medical Research Institute, Sydney, Australia)
Hardeman, Edna C (Children's Medical Research Institute, Sydney,
Australia)
Gunning, Peter W (Chidren's Hospital at Westmead, Sydney, Australia)
Yang, Nan (Chidren's Hospital at Westmead, Sydney, Australia)
Cooper, Sandra T (Chidren's Hospital at Westmead, Sydney, Australia) |
Body of Abstract: |
Mutations at Val163 in ACTA1 result in congenital myopathy with rods
containing actin and α-actinin confined to the nucleus and minimal
disruption of sarcomeric structure. We are investigating mechanisms
underlying intranuclear rod formation and their effects on cell
function. By MALDI-TOF MS the mutant V163M ACTA1 allele is expressed at
lower relative levels to the wild type allele. The expression levels of
the mutant allele varied between affected patients within the same
family and correlated with severity of symptoms. Transfection studies in
C2C12 myoblasts show significant increase in the ability of the V163M
actin mutant to incorporate into large actin filaments. By live-cell
imaging, intranuclear aggregates form inside the nucleus and are dynamic
structures. We also demonstrate that the ‘trapping’ of alpha-actinin
into intranuclear aggregates has an adverse effect on cell viability and
division. We have now generated a knock-in mouse model of the V163M
mutation in ACTA1. These mice are viable, but a proportion die in the
first week of life, likely due to poor feeding associated with a
myopathy. We are now using the animal model to further investigate the
pathogenesis of weakness in our patients. |
|
Abstract Title: |
Regulation of muscle contraction in a novel myopathy associated
with a mutation in the beta-tropomyosin (TPM2) gene |
Presenting/First Author: |
Ochala, Julien (Postdoc - Degree Year: 2005) |
Department, Institution: |
Neuroscience, Clinical Neurophysiology, Uppsala University |
Address: |
University Hospital, Entrance 85, 3rd floor Uppsala, SE-751 85
Sweden |
Phone/Fax: |
+46 18 611 9338 / +46 18 55 6106 |
Email: |
[email protected] |
Abstract Theme: |
|
Author(s): |
Ochala, Julien (Uppsala University, Uppsala 751 85, Sweden)
Kimber, Eva (Sahlgrenska University Hospital, Goteborg 413 45, Sweden)
Tajshargi, Homa (Sahlgrenska University Hospital, Goteborg 413 45,
Sweden)
Tulinius, Mar (Sahlgrenska University Hospital, Goteborg 413 45, Sweden)
Oldfors, Anders (Sahlgrenska University Hospital, Goteborg 413 45,
Sweden)
Larsson, Lars (Uppsala University, Uppsala 751 85, Sweden)
|
Body of Abstract: |
A novel beta-tropomyosin (beta-Tm) TPM2 mutation, R133W, in exon 4
associated with muscle weakness and distal arthrogryposis was recently
identified in a woman and her daughter. In spite of muscle weakness,
vastus lateralis biopsies revealed only minor morphological changes and
type I fiber predominance. No nemaline rods were observed. The aim of
the study was to explore the mechanisms underlying the motor handicap in
patients with the beta-Tm mutation. Maximum force normalized to fiber
cross-sectional area (SF), maximum unloaded shortening velocity (Vo),
and tension-pCa relationship were measured in chemically skinned vastus
lateralis muscle fibers (n = 105) from the 2 patients and from 4 healthy
control subjects. A 30% decrease in SF and a 40% increase in Vo were
observed (p<0.05) in patients type I muscle cells where the beta-Tm is
dominating. The force-pCa relationship did not differ between patient
and control fibers. Further, unregulated actin filament speed propelled
by myosin was similar between patient and control fibers. Thus, the
beta-Tm mutation appears to have a significant effect on the kinetics of
the cross-bridge cycling causing muscle weakness, without affecting the
Ca2+-activation of contractile proteins. |
|
Abstract Title: |
Transcriptional profile of transgenic mice expressing an expanded
CUG repeat |
Presenting/First Author: |
Osborne, Robert J (Postdoc - Degree Year: 2) |
Department, Institution: |
Neurology, University of Rochester |
Address: |
575 Elmwood Ave Rochester, NY 14642 United States |
Phone/Fax: |
585 461 4791 / 585 273 1255 |
Email: |
[email protected] |
Abstract Theme: |
Molecular Basis of Muscle Dysfunction |
Author(s): |
Osborne, Robert J (University of Rochester, NY, 14642)
Welle, Stephen (University of Rochester, NY, 14642)
Thornton, Charles A (University of Rochester, NY, 14642)
|
Body of Abstract: |
HSALR transgenic mice expressing CUG expansion RNA in skeletal
muscle exhibit myotonia, myopathy and misregulated alternative splicing
characteristic of myotonic dystrophy type 1 (DM1). In an attempt to
identify additional pathways affected by repeat expansion RNA, we used
expression microarrays to compare skeletal muscle in two independent
founder lines of HSALR mice and in wild-type (WT) mice. We identified
105 probe sets that were differentially expressed in both transgenic
lines compared to WT (P≤0.01, fold-change ≥2). We postulated that some
expression changes resulted from responses to myotonic discharges or
nonspecific muscle injury. To eliminate these genes from consideration,
we also studied adr (ClC-1 null) mice and their WT controls. adr mice
have severe myotonia and modest up-regulation of regeneration dependent
genes. After filtering out probe sets showing similar changes in adr and
HSALR mice, we were left with 53 genes that were up- regulated and 16
genes that were down-regulated. Of note, none of these genes have been
previously implicated in DM pathogenesis. The function of these genes
suggests signaling pathways that might be involved in the DM disease
process. |
|
Abstract Title: |
Muscle specific delivery of the alpha sarcoglycan gene provides
functional and morphological correction of limb girdle muscular
dystrophy type 2D |
Presenting/First Author: |
Pacak, Christina A (Grad) |
Department, Institution: |
Molecular Genetics and Microbiology, University of Florida |
Address: |
1600 SW Archer Rd, ARB RG_150 Gainesville, FL 32610 United States |
Phone/Fax: |
352-377-6257 / 352-392-8885 |
Email: |
[email protected] |
Abstract Theme: |
Therapies |
Author(s): |
Pacak, Christina A (Dept. of Molecular Genetics and Microbiology,
Powell Gene Therapy Center, University of Florida, Gainesville, FL,
32610)
Gaidosh, Gabriel (Dept. of Physiology, Powell Gene Therapy Center,
University of Florida, Gainesville, FL, 32610)
Germain, Sean (Dept. of Pediatrics, Powell Gene Therapy Center,
University of Florida, Gainesville, FL, 32610)
Lewis, Melissa A (Dept. of Pediatrics, Powell Gene Therapy Center,
University of Florida, Gainesville, FL, 32610)
Campbell, Kevin P (HHMI, University of Iowa)
Walter, Glenn A (Dept. of Physiology, Powell Gene Therapy Center,
University of Florida, Gainesville, FL, 32610)
Byrne, Barry J (Dept. of Pediatrics, Powell Gene Therapy Center,
University of Florida, Gainesville, FL, 32610)
|
Body of Abstract: |
Limb Girdle Muscular Dystrophy (LGMD) describes a group of inherited
diseases that are the physical consequence of mutations in genes
encoding proteins involved in maintaining skeletal muscle membrane
stability. LGMD-2D is the result of mutations in the alpha sarcoglycan
(sgca) gene. Here we describe a gene delivery approach employing a
muscle specific promoter expressing the human sgca gene in combination
with the adeno-associated virus 1 capsid to provide functional and
morphological correction of LGMD-2D. Delivery of our construct to adult
sgca-/- mice has demonstrated successful establishment of the
sarcoglycan complex in muscle cell membranes and reduced fiber damage.
Using a T2 weighted MRI technique, we observed the prevention of lesion
development in lower hind-limbs following delivery of our construct to
sgca-/- mouse neonates. Force mechanics measurements performed on
extensor digitorum longus muscles from mice treated as adults or
neonates showed c orrection of the typical resistance to stretch LGMD-2D
phenotype. Both our gene delivery scheme and T2 weighted MRI method for
non-invasively assessing muscle integrity are clinically applicable
techniques warranting further progression towards implementation in
humans. |
|
Abstract Title: |
Characterization of the cardiac phenotype in a mouse model of
Pompe Disease and correction using AAV-mediated gene delivery |
Presenting/First Author: |
Pacak, Christina A (Grad) |
Department, Institution: |
Molecular Genetics and Microbiology, University of Florida |
Address: |
1600 SW Archer Rd, ARB RG_150 Gainesville, FL 32610 United States |
Phone/Fax: |
352-846-2887 / 352-392-8885 |
Email: |
[email protected] |
Abstract Theme: |
Cardiac Pathology |
Author(s): |
Pacak, Christina A (Molecular Genetics and Microbiology, Powell Gene
Therpay Center, Gainesville, FL 32610)
Mah, Cathryn S (Cellular and Molecular Therapy, Powell Gene Therapy
Center, Gainesville, FL, 32610)
Cresawn, Kerry O (Pediatric Cardiology, Powell Gene Therapy Center,
Gainesville, FL, 32610)
Lewis, Melissa A (Pediatric Cardiology, Powell Gene Therapy Center,
Gainesville, FL, 32610)
Germain, Sean (Pediatric Cardiology, Powell Gene Therapy Center,
Gainesville, FL, 32610)
Byrne, Barry J (Pediatric Cardiology, Powell Gene Therapy Center,
Gainesville, FL, 32610)
|
Body of Abstract: |
Pompe Disease is a form of muscular dystrophy and metabolic myopathy
caused by mutations in the acid alpha glucosidase (GAA) gene and results
in dilated cardiomyopathy and skeletal muscle weakness. Insufficient
amounts of GAA leads to the accumulation of glycogen in lysosomes and
consequent cellular dysfunction. We have observed development of the
cardiac pathology in Pompe mice (GAA-/-) through analysis of ECG traces,
MRI data and histological analysis. Similar to the patient population an
age-related progression of disease occurs in the mouse model. By 2 weeks
of age periodic acid Schiff (PAS) staining shows abnormal amounts of
glycogen in lysosomes of cardiac cells. Mitochondrial aggregation and
lysosome enlargement are evident in electron microscopy images. Through
ECG analysis we observe a shortened PR interval at 3 months mimicking
the conduction phenotype in human patients. MRI data shows an increased
myocardial mass by 12 months. A treatment approa ch using intra-venous
(IV) delivery of either recombinant adeno-associated virus (rAAV)
serotypes 1 or 9 carrying the CMV-hGAA construct to GAA-/- neonates
results in restoration of GAA activity and ameliorate the cardiac
phenotypes observed by PAS, ECG, and MRI analysis. |
|
Abstract Title: |
Overcoming Immune Rejection in Myoblast Transplant Therapy
through Hematopoietic Cell Transplantation |
Presenting/First Author: |
Parker, Maura H (Postdoc - Degree Year: 2) |
Department, Institution: |
Transplantation Biology, Fred Hutchinson Cancer Research Center |
Address: |
1100 Fairview Ave. N. Seattle, WA 98109 United States |
Phone/Fax: |
206-667-1623 / 206-667-6124 |
Email: |
[email protected] |
Abstract Theme: |
Therapies |
Author(s): |
Parker, Maura H (Clinical Research Division, Fred Hutchinson Cancer
Research Center, Seattle, WA 98109)
Storb, Rainer (Clinical Research Division, Fred Hutchinson Cancer
Research Center, Seattle, WA 98109)
Kuhr, Christian (Department of Surgery, University of Washington,
Seattle, WA 98195)
Tapscott, Stephen J (Human Biology Division, Fred Hutchinson Cancer
Research Center, Seattle, WA 98109)
|
Body of Abstract: |
Duchenne Muscular Dystrophy (DMD) is the most common and severe form
of muscular dystrophy in humans. The goal of satellite cell-derived
myoblast transplant therapy (MTT) for DMD is to increase dytrophin
expression in existing fibers, and provide a stem cell source for future
regeneration. The major limitation to the success of MTT has been immune
rejection of transplanted myoblasts. We asked if generating a chimeric
DMD-affected dog, in which the immune system is reconstituted with
DLA-identical donor-derived hematopoietic cells, could provide a more
effective platform for myoblast transplant therapy. DMD affected canines
were subjected to myeloblative conditioning prior to hematopoietic cell
transplant, generating a fully chimeric dog. The hematopoietic cells did
not detectably contribute to either skeletal muscle or the satellite
cell population. However, intramuscular injection of donor-derived
satellite cell-derived myoblasts results in robust and stable expr
ession of dystrophin in DMD affected skeletal muscle. This establishes
chimeric recipients as a viable model for addressing myoblast
transplantation in an immune tolerant, random-bred, large animal model
of Duchenne muscular dystrophy. |
|
Abstract Title: |
Genetic Disruption of Calcineurin Improves Skeletal Muscle
Pathology and Cardiac Function in a Mouse Model of Limb-Girdle Muscular
Dystrophy |
Presenting/First Author: |
Parsons, Stephanie A (Postdoc - Degree Year: 2003) |
Department, Institution: |
Physiology, University of Pennsylvania |
Address: |
1115 Abramson, 3615 Civic Center Blvd. Philadelphia, PA 19446 United
States |
Phone/Fax: |
215-898-0046 / 215-746-3684 |
Email: |
[email protected] |
Abstract Theme: |
Molecular Basis of Muscle Dysfunction |
Author(s): |
Parsons, Stephanie A (Cincinnati Children’s Hospital Medical Center,
Cincinnati, OH 45229-3039)
Millay, Douglas P (University of Cincinnati, Cincinnati, OH, 45267)
Sargent, Michelle A (Cincinnati Children’s Hospital Medical Center,
Cincinnati, OH 45229-3039)
Naya, Francisco J (Boston University, Boston, MA, 02215)
McNally, Elizabeth M (The University of Chicago, Chicago, IL 60637)
Molkentin, Jeffery D (Cincinnati Children’s Hospital Medical Center,
Cincinnati, OH 45229-3039)
|
Body of Abstract: |
Calcineurin (Cn) is a Ca2+/calmodulin-dependent serine/threonine
protein phosphatase that regulates differentiation-specific gene
expression in diverse tissues, including control of fiber-type in
skeletal muscle. Cn is also thought to regulate dystrophic muscle
pathogenesis. For instance, the Cn inhibitor cyclosporine A can delay
muscle regeneration in the dystrophin-deficient mdx mouse, while
expression of activated Cn can reduce disease severity and increase
utrophin expression. Here we examined the role of Cn in the more severe
delta-sarcoglycan-/- (scgd-/-) mouse model of limb-girdle muscular
dystrophy. In contrast to mdx mice, genetic deletion of a loxP-targeted
CnB1 gene using a skeletal muscle-specific cre allele in the scgd-/-
background substantially reduced skeletal muscle degeneration and
histopathology compared with scgd-/- mice. A similar decrease in disease
manifestation was also observed in scgd-/- CnAbeta gene-targeted mice in
both skeletal muscle and heart. Conversely, greater Cn expression
augmented cardiac fibrosis, decreased cardiac function, and increased
fat replacement in various skeletal muscles. Collectively, our results
suggest that Cn inhibition may benefit limb-girdle type of muscular
dystrophies. |
|
Abstract Title: |
Aberrant Golgi Complex Organization in Dystrophin-Deficient
Skeletal Muscle Fibers |
Presenting/First Author: |
Percival, Justin M (Postdoc - Degree Year: 2002) |
Department, Institution: |
Physiology and Biophysics, University of Washington |
Address: |
1959 NE Pacific St Seattle, WA 98195 United States |
Phone/Fax: |
206 543 9094 / 206 685 0619 |
Email: |
[email protected] |
Abstract Theme: |
Molecular Basis of Muscle Dysfunction |
Author(s): |
Percival, Justin M (University of Washington, WA 98195)
Froehner, Stanley C (University of Washington, WA 98195)
|
Body of Abstract: |
Interest in the Golgi complex (GC) in skeletal muscle has emerged
from studies showing that defective glycosylation causes congenital
muscular dystrophy. Glycosylation is a well-established function of the
GC. We investigated whether GC abnormalities also occur in the mdx mouse
model for Duchenne Muscular Dystrophy. In wild type muscle fibers the GC
has an unconventional punctate morphology in contrast to the ribbon-like
GC organization of adjacent non-muscle cells. The GC shows a fiber
type-specific distribution and is predominantly localized just below the
sarcolemma. The GC is heavily concentrated beneath post-synaptic
membranes in a fiber type-specific manner, but is reduced and
mislocalized in mdx muscles. In both dystrophic and regenerating muscle
fibers surface GC puncta are reduced. Increased numbers of enlarged GC
puncta are found in the core of regenerating fibers. Aberrant GC
organization occurs prior to necrosis and may represent an unrecognized
early event in the development of dystrophy. Together these findings
demonstrate a secondary disruption of GC organization in
dystrophin-deficient muscles. Alterations in Golgi organization may
disrupt normal trafficking pathways and contribute to the dystrophic
phenotype. |
|
Abstract Title: |
Molecular basis for skeletal muscle group diversity: How many
‘colors’ and what kind? |
Presenting/First Author: |
Porter, John D (Faculty) |
Department, Institution: |
Channels, Synapses, & Circuits Cluster, National Institute of
Neurological Disorders and Stroke |
Address: |
6001 Executive Blvd, NINDS/NSC 2142 Bethesda, MD 20878 United States |
Phone/Fax: |
301-496-1917 / 301-402-1501 |
Email: |
[email protected] |
Abstract Theme: |
Molecular Basis of Muscle Dysfunction |
Author(s): |
Porter, John D (Case Western Reserve University and University
Hospitals of Cleveland)
Merriam, Anita P (Case Western Reserve University and University
Hospitals of Cleveland)
Feuerman, Jason (Case Western Reserve University and University
Hospitals of Cleveland)
Gong, Bendi (Case Western Reserve University and University Hospitals of
Cleveland)
Kaminski, Henry J (Case Western Reserve University and University
Hospitals of Cleveland)
|
Body of Abstract: |
Skeletal muscles are not created equal. The muscle allotype concept
states that muscle groups may differ by more than just their content of
highly conserved muscle fiber types. It is important to understand the
breadth and consequences of allotype-specific traits, as current
neuromuscular disease models do not account for the not-uncommon
heterogeneity of muscle group responses. Here, we used genome-wide
expression profiling to characterize a diverse set of adult murine
skeletal muscles. We asked the question—how many muscle colors/allotypes
and what kind? Our approach used a genome-wide perspective that
facilitates definitive allotype identification. We identified (a) a
consensus skeletal muscle transcriptome but also (b) clear-cut
differentiation of four putative muscle allotypes based upon the
aggregate genetic distance between muscle groups. Data strongly support
the notion that skeletal muscle group traits are not a simple result of
the aggregate properties o f highly conserved fiber types. These data
represent an important step toward defining a novel classification
scheme that can provide a conceptual basis for future studies of the
differential development, function, and pathogenesis of muscle groups.
Support: NEI. |
|
Abstract Title: |
NIH translational research program in muscular dystrophy |
Presenting/First Author: |
Porter, John D (Faculty) |
Department, Institution: |
Channels, Synapses, & Circuits Cluster, National Institute of
Neurological Disorders and Stroke |
Address: |
6001 Executive Blvd, NINDS/NSC 2142 Bethesda, MD 20878 United States |
Phone/Fax: |
301-496-1917 / 301-402-1501 |
Email: |
[email protected] |
Abstract Theme: |
|
Author(s): |
Porter, John D (National Institute of Neurological Disorders and
Stroke (NINDS), Bethesda, MD)
Nuckolls, Glen (National Institute of Arthritis and Musculoskeletal and
Skin Diseases (NIAMS), Bethesda, MD)
Miller, Thomas (National Institute of Neurological Disorders and Stroke
(NINDS), Bethesda, MD)
|
Body of Abstract: |
NINDS, NIAMS, and NICHD have released a program that facilitates the
translation of mechanistic knowledge into new therapies for muscular
dystrophy (MD). Although pathogenic mechanisms are known for many MDs,
there is no consensus as to which strategy, or combination of
strategies, may prove successful in reducing patient morbidity and
mortality. This program solicits applications for
exploratory/developmental grants (R21; PAR-06-203) and milestone-driven
cooperative agreements (U01; PAR-06-044) to develop efficacious
treatments for MD and supports the development of drugs, biologics, and
devices in cells and animals, but excludes basic or mechanistic work and
non-exempt human studies. Awards can support the full spectrum of
preclinical development activities from preliminary studies through IND
or IDE application to the FDA. Applications for support are reviewed in
a special peer review environment in a context of other preclinical
development projects. Experimen tal approaches should address one or
more of the MDs, and be based upon established disease mechanisms or in
strategies previously shown to have potential efficacy in MD. Potential
applicants are encouraged to make early contact with an NIH program
director listed here. |
|
Abstract Title: |
Spectrin mutations cause destabilitzation of membrane proteins
and Purkinje cell degeneration in spinocerebellar ataxia type 5 |
Presenting/First Author: |
Ranum, Laura (Faculty) |
Department, Institution: |
Genetics, Cell Biology and Development, University of Minnesota |
Address: |
MMC 206, 420 Delaware St. S.E. Minneapolis, MN 55455 United States |
Phone/Fax: |
612 624-0901 / 612 625-8488 |
Email: |
[email protected] |
Abstract Theme: |
|
Author(s): |
Ranum, Laura (University of Minnesota, Minneapolis)
Dick, Katherine (University of Minnesota, Minneapolis)
Gincel, Dan (Johns Hopkins University, Baltimore MD)
Zuelke, Christine (University of Lübeck, Germany)
Brice, Alexis (INSERM and UniversitySalpetriere Hospital, Paris France)
Rothstein, Jeffrey (Johns Hopkins University, Baltimore MD)
Day, John (University of Minnesota, Minneapolis)
Yoshio, Ikeda (University of Minnesota, Minneapolis) |
Body of Abstract: |
One unexplained feature of Duchenne muscular dystrophy is its effect
on the central nervous system, which involves variably severe cognitive
impairment. The mechanisms by which the absence of dystrophin cause
neuronal loss or dysfunction remain unknown. We report that mutations in
beta-III spectrin, a similar plasma-membrane associated cytoskeletal
protein, cause cerebellar Purkinje cell degeneration in spinocerebellar
ataxia type 5. Two families have separate in-frame deletions in the 3rd
spectrin repeat and a third family has a missense mutation in the
actin/ARP1 binding region. Beta-III spectrin, which is highly expressed
in Purkinje cells, stabilizes the glutamate transporter EAAT4 at the
surface of the plasma membrane. Dramatic differences in EAAT4 were found
by Western and cell fractionation in SCA5 autopsy tissue and cell
culture studies demonstrate that wildtype but not mutant β-III spectrin
stabilizes EAAT4 at the plasma membrane. Spectrin mutat ions are a novel
cause of neurodegenerative disease that affect the stabilization of
membrane proteins involved in glutamate signaling. These results may
help determine how Duchenne muscular dystrophy, and other disorders
involving cytoskeletal proteins, cause CNS effects. |
|
Abstract Title: |
Chronic treatment with the beta-adrenoceptor agonist formoterol
deleteriously affects cardiac function in rats |
Presenting/First Author: |
Ryall, James G (Postdoc - Degree Year: 2006) |
Department, Institution: |
Physiology, The University of Melbourne |
Address: |
Grattan Street Melbourne, 3010 Australia |
Phone/Fax: |
613-8344-8942 / 613-8344-5818 |
Email: |
[email protected] |
Abstract Theme: |
Cardiac Pathology |
Author(s): |
Ryall, James G (The University of Melbourne, Victoria, 3010,
Australia)
Schertzer, Jonathan D (The University of Melbourne, Victoria, 3010,
Australia)
Allen, Andrew (The University of Melbourne, Victoria, 3010, Australia)
Lynch, Gordon S (The University of Melbourne, Victoria, 3010, Australia)
|
Body of Abstract: |
The beta-agonist formoterol has been shown to elicit skeletal muscle
hypertrophy and may have therapeutic potential for muscle wasting
conditions. However, their use in clinical practice requires a better
understanding of the possible effects of activation of
beta-adrenoceptors in the heart. We tested the hypothesis that low-dose
administration of formoterol would not cause cardiac hypertrophy and
associated cardiovascular complications in rats. Male rats were
anesthetized and implanted with a radio telemeter to monitor
cardiovascular function during 4 weeks of formoterol administration (25
micro g/kg/day, i.p.). Treatment reduced systolic and diastolic blood
pressure (9% and 14%, respectively), increased heart rate (19%) and
decreased diastolic relaxation time (22%), in the first few days of
administration. However, after treatment, heart rate was reduced(12%)
and diastolic relaxation increased (14%). These findings indicate that
even low-dose formoterol admini stration affects cardiovascular
parameters, and warrants closer scrutiny before clinical application can
be advocated.
Supported by the Muscular Dystrophy Association (USA), the Australian
Research Council and the Australian Association of Gerontology. |
|
Abstract Title: |
Dystrophin and utrophin: sequence homologues with distinct
functional mechanisms |
Presenting/First Author: |
Rybakova, Inna (Faculty) |
Department, Institution: |
Physiology, UW |
Address: |
1300 University Av. Madison, WI 53706 United States |
Phone/Fax: |
608-265-3440 / 608-265-5512 |
Email: |
[email protected] |
Abstract Theme: |
Molecular Basis of Muscle Dysfunction |
Author(s): |
Rybakova, Inna N (Dept. of Physiology, University of Wisconsin
Medical School, Madison, WI 53706)
Humston, Jill L (Dept. of Physiology, University of Wisconsin Medical
School, Madison, WI 53706)
Sonnemann, Kevin J (Dept. of Physiology, University of Wisconsin Medical
School, Madison, WI 53706)
Ervasti, James M (Dept. of Physiology, University of Wisconsin Medical
School, Madison, WI 53706)
|
Body of Abstract: |
Dystrophin and utrophin are homologous proteins that link the actin
cytoskeleton to the extracellular matrix. We previously demonstrated
that the actin binding region of full-length utrophin spans from its
N-terminus through the first 10 spectrin-like repeats. Here, we defined
the molecular epitopes of dystrophin-actin interaction and directly
compared the actin binding properties of dystrophin and utrophin.
According to our data, dystrophin and utrophin both bound alongside
actin filaments with sub-micromolar affinities. Both proteins stabilized
F-actin from depolymerization with similar efficacies, but did not
appear to compete for binding sites on actin. We found that dystrophin
binding to actin was sensitive to increasing ionic strength while
utrophin binding was unaffected. Dystrophin construct spanning from the
N-terminus through repeat 10 bound actin with low affinity and near 1:1
stoichiometry as previously measured for the isolated N-terminus. In
contra st, a construct spanning from the N-terminus through repeat 17
bound actin with properties most similar to full-length dystrophin. We
conclude that dystrophin and utrophin are functionally homologous actin
binding proteins but act through distinct modes of contact. |
|
Abstract Title: |
Eosinophilia, a mediator of fibrosis in dystrophin-deficient
muscle |
Presenting/First Author: |
Sokolow, Sophi (Postdoc - Degree Year: 2) |
Department, Institution: |
Physiological Science, University of California at Los Angeles |
Address: |
621 Charles Young Drive S Los Angeles, CA 90095 United States |
Phone/Fax: |
+13102068390 / +13108258489 |
Email: |
[email protected] |
Abstract Theme: |
Congenital Muscular Dystrophy and Nuclear Membrane Diseases |
Author(s): |
Sokolow, Sophie (University of California, Los Angeles, CA 90095)
Wehling-Henricks, Michelle (University of California, Los Angeles, CA
90095)
Lee, James J (Mayo Clinic Arizona, Scottsdale, AZ 85259)
Tidball, James G (University of California, Los Angeles, CA 90095)
|
Body of Abstract: |
Eosinophils (eos) are inflammatory cells in dystrophin-deficient
muscle that have unknown significance in the pathology of muscular
dystrophy. Major basic protein (MBP) is a major cytolytic protein that
is released by eos that can lyse target cells, suggesting that MBP may
mediate eos lysis of dystrophin-deficient, mdx mouse muscles. We
confirmed eos’ cytotoxicity by showing that these cells lyse myotubes in
culture. We tested whether eos contribute to mdx pathology by generating
a mutant mouse model that is deficient in dystrophin and major basic
protein (mMBP-1) genes. We observed that MBP+/+ eos invade mdx fibers
and are localized at sites of necrotic fibers. However, the MPB-/-/mdx
muscles show no reduction in muscle fiber injury in vivo, although they
invade mdx muscle. MBP deficiency has no effect on the concentrations of
macrophages, neutrophils or CD4+ T-cells in mdx muscle, but causes a
large increase in cytotoxic T-cells (CTLs) in mdx diaphragm and qua
driceps. Finally, we showed that the absence of MBP causes a significant
reduction in diaphragm and hamstring fibrosis at 14 months of age. These
findings show that eosinophilia promotes fibrosis of dystrophic muscle
by a mechanism that may involve CTLs. |
|
Abstract Title: |
Gamma-actin is not required for muscle development but its
absence leads to a novel form of centronuclear myopathy |
Presenting/First Author: |
Sonnemann, Kevin J (Postdoc - Degree Year: 2005) |
Department, Institution: |
Physiology, University of Wisconsin-Madison |
Address: |
1300 University Ave Madison, WI 53704 United States |
Phone/Fax: |
608.265.3440 / 608.265.5512 |
Email: |
[email protected] |
Abstract Theme: |
Molecular Basis of Muscle Dysfunction |
Author(s): |
Sonnemann, Kevin J (Department of Physiology, University of
Wisconsin, Madison, WI 53706)
Fitzsimons, Daniel P (Department of Physiology, University of Wisconsin,
Madison, WI 53706)
Patel, Jitandrakumar R (Department of Physiology, University of
Wisconsin, Madison, WI 53706)
Liu, Yewei (Department of Biochemistry, University of Maryland,
Baltimore, MD 21201)
Schneider, Martin F (Department of Biochemistry, University of Maryland,
Baltimore, MD 21201)
Moss, Richard L (Department of Physiology, University of Wisconsin,
Madison, WI 53706)
Ervasti, James M (Department of Physiology, University of Wisconsin,
Madison, WI 53706)
|
Body of Abstract: |
Cytoplasmic gamma-actin is hypothesized to play important roles in
myogenesis and sarcomere assembly. In mature skeletal muscle gamma-actin
localizes to costameres. Here, we show that muscle development proceeded
normally in skeletal muscle-specific gamma-actin knockout (Actg1-msKO)
mice. In 1-month-old mice, Actg1-msKO muscle fibers were regular in
shape and appearance and displayed properly assembled sarcomeres.
However, Actg1-msKO mice displayed an overt myopathy characterized by
hind limb joint contractures. Focal areas of necrosis and regeneration
progressed from low levels at 3 months of age to widespread incidence by
12 months of age. Actg1-msKO mice exhibited deficits in whole-body
tension and isometric twitch force in isolated hind limb muscles.
Surprisingly, these pathologies were observed without the fibrosis,
inflammation, and membrane damage typical of muscular dystrophies but
are consistent with a novel centronuclear myopathy. Our data demonstrate
a n important role for gamma-actin in adult skeletal muscle and describe
a new mouse model to explore a structural basis for centronuclear
myopathies. Supported by grants from the MDA, AHA, NIH 049899, and NRSA
T32 HL07936 from the UW Cardiovascular Research Center. |
|
Abstract Title: |
Impaired Inward Rectifier K+ Conductance in Ba+2-Poisoned Muscle:
Insights into the Pathophysiology of Hypokalemic Paralysis |
Presenting/First Author: |
Struyk, Arie F (Faculty) |
Department, Institution: |
Neurology, University of Texas-Southwestern Medical Center |
Address: |
6000 Harry Hines Blvd Dallas, TX 75390 United States |
Phone/Fax: |
214 648-7453 / 214 648-7451 |
Email: |
[email protected] |
Abstract Theme: |
Sarcolemmal Excitability |
Author(s): |
Struyk, Arie F (University of Texas-Southwestern Medical Center,
Dallas, TX 75390)
Cannon, Stephen C (University of Texas-Southwestern Medical Center,
Dallas, TX 75390)
|
Body of Abstract: |
Ba+2 poisoning induces sarcolemmal depolarization accompanied by
hypokalemia, similar to paralytic attacks that occur in familial
Hypokalemic Periodic Paralysis (HypoPP), Andersen-Tawil syndrome (ATS),
and thyrotoxicosis. We measured resting K+ currents from Ba+2-poisoned
mouse skeletal muscle under voltage-clamp. Ba+2 depolarized fibers and
selectively blocked a strong inward rectifying K+ conductance (gIRK),
consistent with the notion that gIRK has a major influence on VREST. The
pathological implications of this dependence were explored. As expected,
VREST became hyperpolarized in low external K+ (2 mM), but was
depolarized in 1 mM K+. We propose this paradoxical depolarization
response in very low K+ is related to the leftward shift in gIRK. In
support of this idea, partial block of gIRK with Ba+2 altered the
threshold, such that sarcolemmal depolarization could be elicited by
exposure to 2 mM K+. Model simulations derived from these data
illustrate the relationship between gIRK and VREST stability. These
findings suggest that altered gIRK influence over VREST may contribute
to the depolarization-induced paralysis found in HypoPP, ATS, and
thyrotoxicosis. |
|
Abstract Title: |
Decreased stiffness and power generation from muscle lacking
muscle LIM protein |
Presenting/First Author: |
Swank, Douglas (Faculty) |
Department, Institution: |
Center for Biotechnology, Rensselaer Polytechnic Institute |
Address: |
110 8th Street Troy, NY 12180 United States |
Phone/Fax: |
518-276-4174 / 518-276-2851 |
Email: |
[email protected] |
Abstract Theme: |
Cardiac Pathology |
Author(s): |
Swank, Douglas (Center for Biotechnology, Rensselaer Polytechnic
Institute, Troy, NY)
Lesage, Heather (Dept of Mol. Physiology, University of Vermont,
Burlington, VT)
Clark, Kathleen (Huntsman Cancer Institute, University of Utah, Salt
Lake City, UT)
|
Body of Abstract: |
Muscle LIM protein (MLP) is located in the Z-line of sarcomeres
where it is hypothesized to be involved in sensing muscle stretch.
Mutations in human MLP lead to cardiac hypertrophy or dilated
cardiomyopathies. We generated a Drosophila line null for MLP, Def/Def,
through the use of deficiency chromosomes. MLP null flies that survive
to adulthood are unable to fly. Transgenic expression of one copy of the
mlp84B gene in the deficiency background, P[mlp+],Def/Def, rescues
flight ability (flight index (FI) of 2.8, wing beat frequency (WBF) of
150 Hz), although not to wild type levels (FI of 5.4, WBF of 184 Hz).
Transgenic expression of 2 MLP transgenes, P[mlp+, mlp+],Def/Def,
increased WBF (162 Hz) compared to P[mlp+],Def/Def, but no improvement
in flight ability was observed. Mechanical analysis of skinned flight
muscle fibers showed a 30% decrease in oscillatory power production for
fibers lacking MLP compared to P[mlp+, mlp+],Def/Def fibers. MLP null
fibers disp layed decreased passive, active, and rigor stiffness
compared to P[mlp+, mlp+], Def/Def fibers. We conclude that MLP is
either a parallel compliant element in the z-disk, or it interacts with
D-titin to help maintain muscle stiffness. Supported by NIH AR51473 to
D.M.S. |
|
Abstract Title: |
Transplantation of SM/C-2.6+ satellite cells transduced with
micro-dystrophin CS1 cDNA by lentiviral vector into mdx mice |
Presenting/First Author: |
Takeda, Shin'ichi (Faculty) |
Department, Institution: |
Department of Molecular Therapy, National Institute of Neuroscience,
NCNP |
Address: |
4-1-1 Ogawa-higashi Kodaira, 187-8502 Japan |
Phone/Fax: |
+81-42-346-1720 / +81-42-346-1750 |
Email: |
[email protected] |
Abstract Theme: |
Therapies |
Author(s): |
Takeda, Shin'ichi (Department of Molecular Therapy, National
Institute of Neuroscience, NCNP, Tokyo, Japan)
Ikemoto, Madoka (Department of Molecular Therapy, National Institute of
Neuroscience, NCNP, Tokyo, Japan)
Fukada, So-ichiro (Department of Molecular Therapy, National Institute
of Neuroscience, NCNP, Tokyo, Japan)
Uezumi, Akiyoshi (Department of Molecular Therapy, National Institute of
Neuroscience, NCNP, Tokyo, Japan)
Masuda, Satoru (Department of Molecular Therapy, National Institute of
Neuroscience, NCNP, Tokyo, Japan)
Miyoshi, Hiroyuki (Subteam for Manipulation of Cell Fate, BRC, RIKEN
Tsukuba Institute, Ibaraki, Japan)
Yamamoto, Hiroshi (Department of Immunology, Osaka University, Osaka,
Japan)
Miyagoe-Suzuki, Yuko (Department of Molecular Therapy, National
Institute of Neuroscience, NCNP, Tokyo, Japan) |
Body of Abstract: |
Duchenne muscular dystrophy (DMD) is an X-linked, lethal muscle
disorder caused by?mutations in the dystrophin gene and satellite cells
are expected to be an ideal cell source for cell therapy of DMD. We
developed a cell sorting system to purify quiescent satellite cells from
intact mouse skeletal muscle using a recently developed novel monoclonal
antibody SM/C-2.6 (Exp. Cell Res. 296: 245-55, 2004). First, to
determine the regenerative capacity of SM/C-2.6+ cells, we injected
three kinds of cells, fresh isolated quiescent satellite cells, passaged
satellite cells and primary myoblasts prepared by preplating technique
from GFP-Tg mice into skeletal muscles of dystrophin-deficient mdx mice.
Grafting of fresh isolated SM/C-2.6+ cells resulted in a large number of
GFP-positive fibers at 4 weeks after the injection, whereas grafting of
the same number of SM/C-2.6+ cells passaged in vitro and primary
myoblasts gave rise to significantly fewer GFP-positive fibers. Surpr
isingly, SM/C-2.6+ cells passaged once in culture after isolation showed
almost the same regenerative capacity with those of fresh SM/C-2.6.
Next, to test whether autologous, genetically corrected satellite cells
may represent a possible tool for the therapy of DMD, we isolated
SM/C-2.6+ cells from skeletal muscles of mdx mice and transduced them
with a lentiviral vector expressing micro-dystrophin CS1 (Mol Ther 10:
821-8, 2004). We, then, transplanted them into mdx muscles and found
that many fibers expressed micro-dystrophin on the sarcolemma four weeks
after the injection. These data indicate that mdx SM/C-2.6+ cells
transduced with a micro-dystrophin gene by a lentiviral vector
represents a promising approach to cell therapy of DMD. |
|
Abstract Title: |
Regulation of emerin interactions by tyrosine phosphorylation |
Presenting/First Author: |
Tifft, Kathryn E (Grad) |
Department, Institution: |
Cell Biology, Johns Hopkins School of Medicine |
Address: |
725 North Wolfe Street, WBSB G-11 Baltimore, MD 21205 United States |
Phone/Fax: |
410-614-2654 / 410-955-4129 |
Email: |
[email protected] |
Abstract Theme: |
Congenital Muscular Dystrophy and Nuclear Membrane Diseases |
Author(s): |
Tifft, Kathryn E (Johns Hopkins School of Medicine, Baltimore, MD)
Wilson, Katherine L (Johns Hopkins School of Medicine, Baltimore, MD)
|
Body of Abstract: |
Emery-Dreifuss muscular dystrophy (EDMD) is characterized by
weakening of selected skeletal muscles, contractures of major tendons,
and cardiac conduction defects. Loss of the inner nuclear membrane
protein emerin causes X-linked EDMD. Emerin regulates gene expression
during muscle development, potentially via direct binding to
transcriptional regulators like BAF, GCL, Lmo7, Btf, and mRNA splicing
factor YT521B. Emerin also binds structural proteins (lamin A, actin,
and Nesprins) suggesting additional roles in nuclear structure. The
binding sites in emerin for many partners overlap suggesting regulation
of emerin binding partners and emerin functions. Five labs identified
eleven tyrosine residues in emerin that are phosphorylated in vivo. We
confirmed that emerin is tyrosine phosphorylated in HeLa cells and
discovered that tyrosine phosphorylation decreases in the presence of
Src inhibitors. We are testing the hypothesis that phosphorylation of
specific tyrosine r esidues in emerin regulates specific partners using
single missense mutations at known sites of tyrosine phosphorylation.
Understanding how emerin is regulated by tyrosine phosphorylation may
provide novel insight into emerin function and the mechanism of EDMD
disease. |
|
Abstract Title: |
Myotubularin knockdown results in down-regulation of genes that
may be important for cell size control and regulation of oxidative state |
Presenting/First Author: |
Tomczak, Kinga K (Postdoc - Degree Year: 2000) |
Department, Institution: |
Genetics and Genomics, Children's Hospital Boston and Harvard
Medical Shool |
Address: |
300 Longwood Avenue Boston, MA 02130 United States |
Phone/Fax: |
617-919-2155 / 617-730-0253 |
Email: |
[email protected] |
Abstract Theme: |
Molecular Basis of Muscle Dysfunction |
Author(s): |
Tomczak, Kinga K (Genomics Program and Division of Genetics,
Children’s Hospital Boston and Harvard Medical School, Boston, USA)
Pierson, Christopher R (Genomics Program and Division of Genetics,
Children’s Hospital Boston and Harvard Medical School, Boston, USA)
Zerra, Patricia E (Genomics Program and Division of Genetics, Children’s
Hospital Boston and Harvard Medical School, Boston, USA)
Buj-Bello, Anna (Molecular Pathology, IGBMC, Illkirch, France)
Sanoudou, Despina (IIBEAA, Athens, Greece)
Laporte, Jocelyn (Molecular Pathology, IGBMC, Illkirch, France)
Mandel, Jean-Louis (Molecular Pathology, IGBMC, Illkirch, France)
Beggs, Alan H (Genomics Program and Division of Genetics, Children’s
Hospital Boston and Harvard Medical School, Boston, USA) |
Body of Abstract: |
MTM1 encodes myotubularin, a phosphoinositide phosphatase that is
thought to play a role in vesicular trafficking and is mutated in
X-linked myotubular myopathy (XLMTM). Mtm1 expression was knocked down
(KD) in C2C12 cells using siRNA and expression profiling was performed
at 3 time points of muscle differentiation: day -2 (myoblasts), day +2
(myogenic fusion) and day +6 (mature myotubes). The cells fused as
expected on day 2 and showed well-differentiated myotubes on day 6
confirming no gross effects of KD. T-tests and geometric fold change
analyses revealed 27 genes that were consistently up- or down-regulated
in Mtm1 KD. The microtubule associated gene, doublecortin (Dcx) was
up-regulated in Mtm1 KD cells and absent in controls at all time points.
Among down-regulated transcripts, Car3 (carbonic anhydrase 3) and
mitochondrial Txn2 (thioredoxin 2) are thought to be involved in
protection of the cell from oxidative damage while two other genes Gdf5
(growth differ entiation factor 5) and Igfbp4 (insulin growth factor
binding protein 4) are involved in regulation of growth. Decreased
expression of Car3, Txn2, Igfbp4 and Gdf5 was confirmed by quantitative
real-time PCR in KD cells and in Mtm1 knock-out mouse muscles.
Alterations in these genes suggest a role of myotubularin in the control
of cell or fiber size and regulation of the oxidative state. The
pathogenic mechanism linking alterations in the expression of these
genes with Mtm1 KD and XLMTM is on going. |
|
Abstract Title: |
Systemic gene delivery of of micro-dystrophin prevents acute
heart failure in mdx mice |
Presenting/First Author: |
Townsend, DeWayne (Postdoc - Degree Year: 2003) |
Department, Institution: |
Molecular and Integrative Physiology, University of Michigan |
Address: |
7712 Med Sci II, 1301 E Catherine St Ann Arbor, MI 48109 United
States |
Phone/Fax: |
734-764-9920 / 734-647-6461 |
Email: |
[email protected] |
Abstract Theme: |
Plasma Membrane Stability/Repair |
Author(s): |
Townsend, DeWayne (Univ. of Michigan, Ann Arbor, MI 48109)
Blankinship, Mike J (Univ. of Washington, Seattle, WA, 98195)
Allen, James M (Univ. of Washington, Seattle, WA, 98195)
Chamberlain, Jeffery S (Univ. of Washington, Seattle, WA, 98195)
Metzger, Joseph M (Univ. of Michigan, Ann Arbor, MI 48109)
|
Body of Abstract: |
Duchenne muscular dystrophy (DMD) is a debilitating and fatal
disease, that is characterized by both skeletal muscle pathology and
cardiomyopathy, resulting from deletions of dystrophin (DYS). None of
the truncated forms of dystrophin have been functionally assessed in
cardiac tissue. A single intravenous injection of high titer (~10^12
vector genomes/mouse) adeno-associated virus-micro-DYS (3.7 kb) resulted
in strong and uniform expression of micro-DYS at 10 weeks post
injection. These mice show supra-normal levels of several
dystrophin-associated proteins. The cardiac function of virus injected
mice was assessed by pressure-volume catheterization at baseline and
during a 30 minute dobutamine challenge. At baseline conditions the
end-diastolic volume of the mdx mouse is significantly smaller compared
to controls (20±2 ul (n=10) vs. 31±3 ul (n=8); P<0.01); this geometry is
corrected by the expression of micro-DYS (31±3 ul (n=8); P>0.05 vs.
Control). Furthermore, w ithout therapeutic intervention, 70% of mdx
mice develop acute heart failure during a dobutamine challenge; this
decompensation is alleviated by expression of micro-DYS (n=8). Thus
micro-DYS is able to redress both acute and chronic aspects of
dystrophic cardiomyopathy. |
|
Abstract Title: |
FRG1 interacts with spliceosomal proteins |
Presenting/First Author: |
Van der Maarel, Silvère M (Faculty) |
Department, Institution: |
Human Genetics, Leiden University Medical Center |
Address: |
Albinusdreef 2 Leiden, AZ 2333 ZA Netherlands |
Phone/Fax: |
+31 71 526 9480 / +31 71 526 8285 |
Email: |
[email protected] |
Abstract Theme: |
|
Author(s): |
van der Maarel, Silvère M (Dept. of Human Genetics, Leiden
University Medical Center, Leiden, Netherlands)
van Koningsbruggen, Silvana (Dept. of Human Genetics, Leiden University
Medical Center, Leiden, Netherlands)
Straasheijm, Kirsten R (Dept. of Human Genetics, Leiden University
Medical Center, Leiden, Netherlands)
Sterrenburg, Ellen (Dept. of Human Genetics, Leiden University Medical
Center, Leiden, Netherlands)
Klooster, Rinse (Dept. of Human Genetics, Leiden University Medical
Center, Leiden, Netherlands)
de Graaf, Natascha (Dept. of Human Genetics, Leiden University Medical
Center, Leiden, Netherlands)
Dauwerse, Hans G (Dept. of Human Genetics, Leiden University Medical
Center, Leiden, Netherlands)
Frants, Rune R (Dept. of Human Genetics, Leiden University Medical
Center, Leiden, Netherlands) |
Body of Abstract: |
Facioscapulohumeral muscular dystrophy (FSHD) is caused by an
epigenetic mechanism involving contraction of the D4Z4 repeat and loss
of transcriptional control over one or more genes. FRG1 is considered a
candidate gene for FSHD and the FRG1 protein localizes to nucleoli,
Cajal bodies and speckles. It has been suggested to be a component of
the spliceosome but its exact function is unknown. Transgenic mice
muscle-specifically overexpressing FRG1 have muscular dystrophy and
upregulation of FRG1 correlates with mis-splicing of specific pre-mRNAs.
Missplicing is also observed in our FRG1 stable cell lines, but not in
skeletal muscle of FSHD patients.
By computational analysis, yeast-two-hybrid screens, and
co-immunoprecipitation and co-localization studies, we have identified
known and novel proteins that associate with FRG1. All of these have a
direct or indirect role in pre-mRNA splicing. In addition, artificially
induced nucleolar aggregates of VSV-FRG1 specifically sequester proteins
involved in pre-mRNA splicing, but not in other processes of RNA
biogenesis. Our data confirm the presence of FRG1 in the human
spliceosome and strongly support a role for FRG1 in splicing.
Supported by NIAMS, MDA, FSHD Foundation and IOP. |
|
Abstract Title: |
Which is the calcium channel partner of triadin TRISK 32 ? |
Presenting/First Author: |
Vassilopoulos, Stéphane - (Undergrad) |
Department, Institution: |
DRDC- CEA Grenoble, INSERM U607 - CCFP |
Address: |
17 rue des Martyrs Grenoble, 38054 France |
Phone/Fax: |
33 4 38 78 58 39 / 33 4 38 78 50 41 |
Email: |
[email protected] |
Abstract Theme: |
Sarcolemmal Excitability |
Author(s): |
Vassilopoulos, Stéphane - (Inserm U607 - CCFP- CEA Grenoble, 38054
Grenoble, France)
Oddoux, Sarah - (Inserm U607 - CCFP- CEA Grenoble, 38054 Grenoble,
France)
Brocard, Julie - (Inserm U607 - CCFP- CEA Grenoble, 38054 Grenoble,
France)
Fauré, Julien - (Inserm U607 - CCFP- CEA Grenoble, 38054 Grenoble,
France)
Lunardi, Joël - (Inserm U607 - CCFP- CEA Grenoble, 38054 Grenoble,
France)
Marty, Isabelle - (Inserm U607 - CCFP- CEA Grenoble, 38054 Grenoble,
France)
|
Body of Abstract: |
Internal calcium release is performed via two major calcium release
channels: Ryanodine receptor (RyR) or IP3-receptor (IP3R). In skeletal
muscle, release of calcium leading to contraction is performed by the
calcium release complex, which involves RyR1 as the intracellular
calcium channel. Other proteins are associated to RyR1 in this complex,
among which triadin. We have cloned four triadin isoforms: Trisk 95,
Trisk 51, Trisk 49 and Trisk 32. Trisk 32 is not only expressed in
skeletal muscle, it is also the major cardiac triadin isoform. We have
shown that in skeletal muscle, Trisk 32 is only partially associated
with RyR1, but could be associated with IP3R. In cardiac muscle on the
contrary, Trisk 32 has been shown to be associated with RyR2. In the
present work, we studied the respective localization of RyR1, Trisk 32
and IP3R using immunofluorescent labeling, and their association by
immunoprecipitation in rat skeletal muscle. We performed the same study
on rat cardiac muscle, to analyze the respective localization of RyR2,
Trisk 32 and IP3R and their possible association. We wish to identify
through this study the calcium release channel partner of Trisk 32, both
in heart and in skeletal muscle. |
|
Abstract Title: |
Proteomic analysis of CAPN3 deficient mice implicates CAPN3 in
myofibrillar protein turnover |
Presenting/First Author: |
Venkatraman, Gayathri (Postdoc - Degree Year: 2004) |
Department, Institution: |
Neurology, University of California at Los Angeles |
Address: |
NRB 1, Room 404, 635 Charles Young Drive South Los Angeles, CA 90095
United States |
Phone/Fax: |
310-267-4582 / 310-206-1998 |
Email: |
[email protected] |
Abstract Theme: |
Congenital Muscular Dystrophy and Nuclear Membrane Diseases |
Author(s): |
Venkatraman, Gayathri (Department of Neurology, Univ. of California,
Los Angeles)
Gomes, Aldrin V (Department of Physiolgy and Medicine, University of
California, Los Angeles)
Spencer, Melissa J (Department of Neurology, Univ. of California, Los
Angeles)
|
Body of Abstract: |
Calpain 3 (CAPN3) is a calcium-dependent, cysteine protease
predominantly found in skeletal muscle. Mutations in CAPN3 cause Limb
Girdle muscular dystrophy type 2A. Previously, we showed that CAPN3
knockout (KO) mice have reduced accumulation of ubiquitinated proteins
during muscle remodeling, and that this reduction is not due to enhanced
proteasome activity. These studies suggest that CAPN3 acts upstream of
the ubiquitin-proteasome pathway during muscle protein turnover. To
further investigate proteins targeted for ubiquitination by CAPN3, we
compared ubiquitinated proteins from wildtype (WT) and CAPN3 deficient
mice. Ubiquitinated proteins were isolated by affinity purification, and
analyzed by LC-MS/MS. Over 200 proteins were identified in the
ubiquitinated extracts from WT and KO muscles. Immunoblotting confirmed
the MS data which suggested that myosin heavy chain, myomesin and actin
are all significantly reduced in the ubiquitinated fraction from CAPN3
KO m ice. The down regulation of the major muscle sarcomeric proteins in
the ubiquitinated fraction of the CAPN3 KO muscle suggests a role for
CAPN3 during myofibrillar protein turnover. Supported by NIH AR48177 to
MJS. |
|
Abstract Title: |
Prevention of oculopharyngeal muscular dystrophy-associated
aggregation of nuclear poly(A)-binding protein with an intracellularly
expressed camelid-derived antibody domain |
Presenting/First Author: |
Verheesen, Peter (Faculty) |
Department, Institution: |
Molecular Biology, Ablynx nv |
Address: |
Technologiepark 4 Ghent, 9000 Belgium |
Phone/Fax: |
+3292610622 / +3292610628 |
Email: |
[email protected] |
Abstract Theme: |
Molecular Basis of Muscle Dysfunction |
Author(s): |
Verheesen, Peter (Univ. of Utrecht, Utrecht, The Netherlands)
de Kluijver, Anna (Univ. of Utrecht, Utrecht, The Netherlands)
van Koningsbruggen, Silvana (Leiden University Medical Center, Leiden,
The Netherlands)
de Haard, Hans (Ablynx nv, Ghent, Belgium)
van Ommen, Gert-Jan (Leiden University Medical Center, Leiden, The
Netherlands)
Verrips, Theo (Univ. of Utrecht, Utrecht, The Netherlands)
van der Maarel, Silvère (Leiden University Medical Center, Leiden, The
Netherlands)
|
Body of Abstract: |
Oculopharyngeal muscular dystrophy (OPMD) is regarded a paradigm for
protein aggregation disorders. It is caused by extensions of the
N-terminal polyalanine stretch of the nuclear polyA-binding protein 1
(PABPN1) causing the presence of intranuclear aggregates in skeletal
muscle. Intranuclear aggregation of mutant PABPN1 is also observed in
transgenic mouse and cell models for OPMD supporting a direct role for
protein aggregation in pathogenesis.
We have isolated camelid-derived antibody reagents (VHH) against
different epitopes in PABPN1, which specifically detect and label
endogenous PABPN1 in cell lysates, cultured cells and muscle sections.
When expressed intracellularly as intrabodies in a model for OPMD,
aggregation was prevented in a dose-dependent manner. These intrabodies
also have curative properties as they could reduce already existing
aggregates. Given the domain specificity of VHH-mediated aggregation
interference, this approach facilitates definition of the nucleation
kernel in aggregation-prone proteins, thus providing etiological insight
into this and other protein aggregation disorders. It may also provide
useful therapeutic agents.
Supported by IOP Genomics/Senter Novem, the NIH, and E.C. |
|
Abstract Title: |
Sarcoglycan expression is restored in delta-sarcoglycan null mice
by muscle-derived stem cell transplantation |
Presenting/First Author: |
Wallace, Gregory Q (Postdoc - Degree Year: 2005) |
Department, Institution: |
Medicine, University Of Chicago |
Address: |
5841 S Maryland Chicago, IL 60637 United States |
Phone/Fax: |
7737022864 / 7737022681 |
Email: |
[email protected] |
Abstract Theme: |
|
Author(s): |
Wallace, Gregory Q (Department of Medicine, University of Chicago,
Chicago, Illinois, USA)
Lapidos-Cielo, Karen A (Department of Molecular Genetics and Cell
Biology, University of Chicago, Illinois, USA)
Chen, Yiyin E (Department of Molecular Genetics and Cell Biology,
University of Chicago, Illinois, USA)
McNally, Elizabeth M (Department of Medicine, University of Chicago,
Chicago, Illinois, USA)
|
Body of Abstract: |
Muscular dystrophies are characterized by progressive muscle
degeneration that overcomes muscle’s ability to regenerate. Stem cell
transplantation is a promising therapeutic strategy for functional
correction of dystrophic muscle. Use of stem cells has the dual
advantage of delivering normal copies of the disease-causing gene while
adding cells to the regenerative cell pool. Ongoing challenges in
optimizing a stem cell-based therapy approach include identifying cells
with potent myogenic activity, maintaining long-term survival of
transplanted cells, and avoiding immune responses. We have isolated
mononuclear cells from muscle of adult, male wildtype mice and injected
them directly into muscles of delta-sarcoglycan null female mice. Donor
cells were fractionated by Hoechst dye staining, centrifugation through
a Ficoll gradient, or by cell size immediately prior to injection. Four
weeks or six months after transplantation, mice were sacrificed and
donor-derived mus cle fibers were scored. We have identified a subset of
adult, muscle-derived stem cells that can yield up to 13% donor-derived
muscle fibers and survive at least six months in vivo.
Research supported by Muscular Dystrophy Association and National
Institutes of Health. |
|
Abstract Title: |
Local calcium release events in wildtype and dystrophic adult
myofibers |
Presenting/First Author: |
Ward, Christopher W (Faculty) |
Department, Institution: |
OSAHN, Univ. Maryland |
Address: |
755 W Lombard St Baltimore, MD 21201 United States |
Phone/Fax: |
410-706-3618 / 410-706-2222 |
Email: |
[email protected] |
Abstract Theme: |
Molecular Basis of Muscle Dysfunction |
Author(s): |
Ward, Christopher W (University of Maryland Baltimore)
Voelker, Kevin (Virginia Tech, Blacksburg, VA)
Grange, Robert W (Virginia Tech, Blacksburg, VA)
Shtifman, Alexander (St Elizabeth's Hospital, Tufts Univ., MA)
|
Body of Abstract: |
Local calcium (Ca2+) release events (LCRE) are spatially restricted
elevations in Ca2+ arising from a small cluster of ryanodine
receptor(RyR) Ca2+ channels in the sarcoplasmic reticulum (SR). In
intact adult mammalian myofibers solely expressing RyR1, spontaneous
LCRE are suppressed and rarely visualized. Recently, spontaneous LCRE in
intact FDB myofibers was revealed secondary to osmotic stress (Wang et
al., Nat. Cell. Bio, 2005) with an enhanced occurrence in MDX myofibers;
a disease in which an alteration in calcium homeostasis is a hallmark of
the pathogenesis. Having verified these results qualitatively, we
determined that external [Ca2+] modulates the occurrence of LCRE as well
as global SR Ca2+ release during osmotic and ionic stress in WT and MDX
myofibers. In addition we have verified that in MDX myofibers,
sarcolemma permeability to Ca2+ is ~ 2 fold higher than WT controls. We
hypothesize that under stress, MDX myofibers have an increased Ca2+
influx wh ich contributes to the occurrence of LCRE. Independent of the
sarcolemma pathway, permeablized MDX myofibers demonstrate an increase
in LCRE frequency and altered properties which may suggest an alteration
in RyR dependent Ca2+ release as a contributing factor. |
|
Abstract Title: |
Ribonuclear inclusions in junctional nuclei and anterior horn
cells in myotonic dystrophy type I |
Presenting/First Author: |
Wheeler, Thurman M (Postdoc - Degree Year: ) |
Department, Institution: |
Neurology, University of Rochester |
Address: |
601 Elmwood Ave., Box 673 Rochester, NY 14642 United States |
Phone/Fax: |
5852731456 / 5852731255 |
Email: |
[email protected] |
Abstract Theme: |
Molecular Basis of Muscle Dysfunction |
Author(s): |
Wheeler, Thurman M (University of Rochester, Rochester, NY 14642)
Krym, Matt C (University of Rochester, Rochester, NY 14642)
Thornton, Charles A (University of Rochester, Rochester, NY 14642)
|
Body of Abstract: |
A characteristic feature of muscle pathology in myotonic dystrophy
(DM) is the finding of severely atrophic fibers that are nearly devoid
of cytoplasm, similar to those seen in denervated muscle. This
observation has prompted speculation that DM1 may lead to instability of
the NMJ. However, whether DMPK is expressed at the motor endplate is
controversial. To address this question, we used fluorescent in situ
hybridization (FISH) to examine the expression pattern of expanded
repeat RNA. First, in HSALR transgenic mice that express skeletal actin
mRNA with an expanded CUG in the 3’ UTR, nuclear RNA foci are abundant
in extrajunctional myonuclei but minimal to absent in junctional nuclei.
Of note, HSALR mice display some histologic features similar to DM but
they do not develop nuclear clumps. Next, FISH in human DM1 muscle
clearly demonstrates nuclear foci in junctional nuclei and motor
neurons, indicating that DMPK RNA is expressed on both sides of the
endpla te. These results indicate an important difference between the
HSALR transgenic model and human DM1, and suggest that specialization of
junctional nuclei involves downregulation of genes encoding myofibrillar
proteins. Analysis of muscle sections confirms that DMPK protein
accumulates at the neuromuscular junction. Finally, muscleblind-1
protein forms foci that colocalize with expanded repeat RNA in
junctional nuclei and motor neurons, suggesting susceptibility to
RNA-mediated toxicity. These observations raise the possibility that
expression of CUG expansion RNA may compromise the stability or function
of the NMJ in DM1. |
|
Abstract Title: |
Prevention of Lethal Muscular Dystrophy in a Severe DMD Mouse
Model via Human Retinal Dystrophin Transgene: Implications for DMD Gene
Therapy |
Presenting/First Author: |
White, Robert A (Faculty) |
Department, Institution: |
Medical Research, Children's Mercy Hospital, Pediatric Research
Center, 4th Fl |
Address: |
2401 Gillham Kansas City, MO 64108 United States |
Phone/Fax: |
816-983-6502 / 816-983-6501 |
Email: |
[email protected] |
Abstract Theme: |
Therapies |
Author(s): |
White, Robert A (Children's Mercy Hospitals & Clinics, Kansas City,
MO)
McNulty, Steven G (Children's Mercy Hospitals & Clinics, Kansas City,
MO)
Modrcin, Ann C (Children's Mercy Hospitals & Clinics, Kansas City, MO)
Rinaldi, Robert J (Children's Mercy Hospitals & Clinics, Kansas City,
MO)
Gaedigk, Roger (Children's Mercy Hospitals & Clinics, Kansas City, MO)
Law, Douglas J (University of Missouri-Kansas City)
Fitzgerald-Gustafson, Kathleen M (University of Kansas Medical Center,
Kansas City, KS)
Hauschka, Stephen D (University of Washington, Seattle, WA) |
Body of Abstract: |
Duchenne muscular dystrophy (DMD) is a progressive muscle disease
characterized by lack of dystrophin expression, progressive muscle
weakness, and death by the third decade. The most commonly used mouse
model of DMD is the muscular dystrophy mdx mouse. This mutant has
underlying muscle disease but appears physically normal with an ordinary
lifespan possibly due to compensatory expression of utrophin in these
mice. In contrast to mdx mice, double mutant mice (DM), deficient for
both dystrophin and utrophin (mdx/Y, utrn-/-), present a model that most
resembles DMD. These mice die prematurely at 3 months of age and suffer
from severe muscle weakness, pronounced growth retardation, and severe
spinal curvature. The capacity of human retinal dystrophin (Dp260) to
compensate for the absence of muscle dystrophin was tested in DM mice.
Functional outcomes were assessed by muscle histology, EMG, MRI,
mobility studies and measurement of weight and longevity. MCK
promoter-dri ven transgenic expression of Dp260 in DM mice converts
their disease course from a severe, lethal muscular dystrophy to a
viable, mild myopathic phenotype. These studies have important clinical
implications for the possible treatment of DMD, via gene therapy
approaches. |
|
Abstract Title: |
Nanopolymer-oligonucleotides for the induction of dystrophin
expression in mdx mice |
Presenting/First Author: |
Williams, Jason H (Grad) |
Department, Institution: |
Pharmacology & Physiology, Drexel University College of Medicine |
Address: |
245 N 15th St Philadelphia, PA 19118 United States |
Phone/Fax: |
215-762-4979 / 215-762-2299 |
Email: |
[email protected] |
Abstract Theme: |
Therapies |
Author(s): |
Williams, Jason H (Drexel University College of Medicine,
Philadelphia, PA 19102)
Sirsi, Shashank R (Drexel University College of Medicine, Philadelphia,
PA 19102)
Nicolai, Jackie (Drexel University College of Medicine, Philadelphia, PA
19102)
Latta, Daniel R (Drexel University College of Medicine, Philadelphia, PA
19102)
Lutz, Gordon J (Drexel University College of Medicine, Philadelphia, PA
19102)
|
Body of Abstract: |
Antisense oligonucleotides (AOs) have previously been shown to
modulate dystrophin pre-mRNA splicing, causing “skipping” of mutated
dystrophin exons, and production of partially to fully functional
protein. Thus, AOs are hopeful drug candidates for treatment of Duchenne
muscular dystrophy (DMD). However, AO-based approaches are hindered by a
lack of effective carriers to facilitate delivery of AOs to myonuclei.
In our recent report we showed that a PEG-PEI copolymer comprised of low
Mw PEI2K functioned as an effective AO carrier, producing wide-spread
appearance of dystrophin-positive fibers after intramuscular injection
into mdx mice, with no apparent cytotoxicity. We now show evidence of
dystrophin expression at extended time points. These data suggest that
PEG-PEI copolymers are able to sequester and protect AOs from
degradation, and may facilitate sustained delivery of AOs to myonuclei
over long durations. Overall, PEG-PEI copolymers represent a flexible
nucleotide delivery system with controllable size and adjustable
unpackaging properties. Additional optimization of
nanopolymer-oligonucleotide properties will likely improve transfection
efficiency and promote wider usage of this beneficial carrier compound. |
|
Abstract Title: |
Passive mechanical properties of maturing EDL are not affected by
lack of dystrophin |
Presenting/First Author: |
Wolff, Andrew V (Grad) |
Department, Institution: |
Mechanical Engineering, Virginia Tech |
Address: |
338 Wallace Hall Blacksburg, VA 24061 United States |
Phone/Fax: |
540-525-0178 / 540-231-3916 |
Email: |
[email protected] |
Abstract Theme: |
Congenital Muscular Dystrophy and Nuclear Membrane Diseases |
Author(s): |
Wolff, Andrew V (Department of Mechanical Engineering, Virginia
Tech, Blacksburg, VA)
Niday, Ashley K (Department of Engineering Science and Mechanics,
Virginia Tech, Blacksburg, VA)
Voelker, Kevin A (Department of Human Nutrition, Foods and Exercise,
Virginia Tech, Blacksburg, VA)
Call, Jarrod A (Department of Human Nutrition, Foods and Exercise,
Virginia Tech, Blacksburg, VA)
Evans, Nick P (Department of Human Nutrition, Foods and Exercise,
Virginia Tech, Blacksburg, VA)
Granata, Kevin P (Department of Human Nutrition, Foods and Exercise,
Virginia Tech, Blacksburg, VA)
Grange, Robert W (Department of Human Nutrition, Foods and Exercise,
Virginia Tech, Blacksburg, VA)
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Body of Abstract: |
To better understand the role that mechanical weakness might play in
the onset of Duchenne muscular dystrophy, the mechanical properties of
maturing dystrophic and control skeletal muscles should be
systematically assessed. The purpose of this study was to determine (1)
if the passive mechanical properties of maturing dystrophic muscles were
different from control; and, (2) if different, when during maturation
did these properties change? At ages prior to and following the overt
onset of the dystrophic process (14-35 days), control and dystrophic
extensor digitorum longus (EDL) muscles were subjected to two passive
stretch protocols at 5% strain with two strain rates in vitro. Force
profiles at the instantaneous strain rate were fit to a three parameter
viscoelastic muscle model to determine two parameters of stiffness and a
damping parameter. The dystrophic and control EDL muscles exhibited
similar passive mechanical properties at each age. These results sug
gest a functional threshold for dystrophic muscle below which damage may
be minimized. Determining this threshold could have important clinical
implications for treatments of muscular dystrophy involving physical
activity. Research supported by NIH grant AR049881. |
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Abstract Title: |
A C-terminal skeletal muscle sodium channel mutation associated
with myotonia disrupts fast inactivation |
Presenting/First Author: |
Wu, Fen-Fen (Postdoc - Degree Year: 2001) |
Department, Institution: |
Neurology, UT Southwestern Medical Center |
Address: |
6000 Harry Hines Blvd Dallas, TX 75390 United States |
Phone/Fax: |
214-648-7450 / 214-648-7451 |
Email: |
[email protected] |
Abstract Theme: |
Sarcolemmal Excitability |
Author(s): |
Wu, Fen-Fen (Univ of Texas Southwestern Medical Center, Dallas, TX
75390)
Gordon, Erynn (Children’s National Medical Center, Washington, DC 20010)
Hoffman, Eric P (Children’s National Medical Center, Washington, DC
20010)
Cannon, Stephen C (Univ of Texas Southwestern Medical Center, Dallas, TX
75390)
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Body of Abstract: |
Missense mutations in the skeletal muscle sodium channel
alpha-subunit gene (SCN4A) are associated with clinically overlapping
diseases caused by alterations in sarcolemmal excitability, which may
result in myotonia or periodic paralysis. A cold-aggravated myotonia
patient was screened 24 exons of SCN4A by DHPLC and sequencing. Two
novel changes were found: T323M in the DIS5-S6 loop and F1705I in the
C-terminus. The functional impact was assessed by recording whole-cell
Na+ currents from HEK cells. T323M currents were indistinguishable from
WT. Fast inactivation (FI) was impaired for F1705I by an 8.6 mV
rightwards shift in voltage dependence and a 2-fold slowing in the
inactivation rate. Recovery from FI was not altered, nor was an increase
in the persistent current. Activation and slow inactivation were not
affected. These data suggest that T323M is a benign polymorphism,
whereas F1705I results in FI defects, which are often observed for
myotonia. This is the first example of a SCN4A C-terminal mutation
associated with human disease. Like the cardiac disorders (LQT3 or
Brugada syndrome) and epilepsy (GEFS+) associated with C-terminal
mutations in other NaV channels, the defect of F1705I was a partial
disruption of FI. |
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