Genomes and Genes
Pathogenesis of Myopathy in Models of Myotonic Dystrophy
Principal Investigator: Charles A Thornton
Abstract: DESCRIPTION (provided by applicant): Myotonic dystrophy type 1 [DM1] leads to maldevelopment, myotonia, and wasting of skeletal muscle. DM1 is caused by an unstable CTG repeat expansion in the 3'untranslated region of DMPK. Our central hypothesis is that skeletal muscle findings in DM1 result from a toxic effect of repeat expansion transcripts. Support for this hypothesis comes from studies of HSALR transgenic mice that express CUG expansion RNA in muscle. (CUG)n transcripts accumulate in nuclear foci, leading to a myotonic myopathy that is similar to DM1. Our working model postulates the following sequence of events: expression of CUG expansion RNA ->accumulation of (CUG)n RNA in nuclear foci ->sequestration of muscleblind [Mbnl] proteins in nuclear foci ->abnormal regulation of alternative splicing ->expression of inappropriate splice isoforms ->symptoms of DM. We now have evidence that this model can explain certain aspects of DM1, such as, chloride channelopathy and myotonia. We plan to extend this model and define its limits. First, we will compare patterns of alternative splicing in HSALR, Mbnll knockout, and wild-type mice and test the hypothesis that CUG expansion RNA compromises a specific developmental program of alternative splicing that depends on Mbnl1, the predominant Mbnl protein expressed in muscle. A striking example of aberrant splicing involves Serca1, the calcium re-uptake pump in sarcoplasmic reticulum. The physiologic significance of mis-splicing Serca1 will be determined by calcium imaging. Second, there is little information about metabolism of (CUG)n transcripts. We have derived transgenic mice for inducible expression of CUG expansion transcripts. These mice will be used to compare the accumulation and degradation of transcripts with or without an expanded CUG repeat. We also will test the hypothesis that overexpression of nuclear mRNA-degradases can accelerate clearance of poly-CUG RNA. Third, we will assess myonuclear morphology and bromodeoxyuridine incorporation in HSA(LR) mice to test the hypothesis that accumulation of CUG expansion RNA leads to nuclear demise. In related experiments we will investigate the mechanism of cell death that occurs in HSA(LR) myoblasts when growth factors are withdrawn. Fourth, we have derived transgenic mice with cre-activation alleles to develop models for DM1-related maldevelopment and wasting and test the hypothesis that CUG expansion RNA interferes with muscle differentiation.
Funding Period: 2009-09-18 - 2010-09-17
more information: NIH RePORT
- Mexiletine is an effective antimyotonia treatment in myotonic dystrophy type 1E L Logigian
Department of Neurology, University of Rochester, Rochester, NY, USA
Neurology 74:1441-8. 2010..To determine if mexiletine is safe and effective in reducing myotonia in myotonic dystrophy type 1 (DM1)...
- Epigenetic changes and non-coding expanded repeatsMasayuki Nakamori
Department of Neurology, University of Rochester Medical Center, Rochester, New York 14642, USA
Neurobiol Dis 39:21-7. 2010..Here we review the mechanisms of gene dysregulation induced by non-coding repeat expansions, and early indications that some of these disorders may prove to be responsive to therapeutic intervention...
- Scaled-down genetic analysis of myotonic dystrophy type 1 and type 2Masayuki Nakamori
Department of Neurology, Box 673, University of Rochester Medical Center, Rochester, NY 14642, USA
Neuromuscul Disord 19:759-62. 2009..These methods can facilitate genetic analysis in cells and tissues obtained from individuals with myotonic dystrophy...
- Aberrant alternative splicing and extracellular matrix gene expression in mouse models of myotonic dystrophyHongqing Du
RNA Center, Department of Molecular, Cell and Developmental Biology, Sinsheimer Labs, University of California, Santa Cruz, California, USA
Nat Struct Mol Biol 17:187-93. 2010..These findings reveal unanticipated similarities between DM1 and other muscular dystrophies...
- Pentamidine reverses the splicing defects associated with myotonic dystrophyM Bryan Warf
Department of Chemistry and Institute of Molecular Biology, University of Oregon, Eugene, OR 97403, USA
Proc Natl Acad Sci U S A 106:18551-6. 2009..Furthermore, pentamidine partially rescued splicing defects of 2 pre-mRNAs in mice expressing expanded CUG repeats...
- Triplet-repeat oligonucleotide-mediated reversal of RNA toxicity in myotonic dystrophySusan A M Mulders
Department of Cell Biology, Nijmegen Centre for Molecular Life Sciences, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
Proc Natl Acad Sci U S A 106:13915-20. 2009..Our data demonstrate proof of principle for therapeutic use of simple sequence AONs in DM1 and potentially other unstable microsatellite diseases...
- Reversal of RNA dominance by displacement of protein sequestered on triplet repeat RNAThurman M Wheeler
Departments of Neurology, Pharmacology and Physiology, University of Rochester, Rochester, NY 14642, USA
Science 325:336-9. 2009..These findings suggest an alternative use of antisense methods, to inhibit deleterious interactions of proteins with pathogenic RNAs...
- Rational design of ligands targeting triplet repeating transcripts that cause RNA dominant disease: application to myotonic muscular dystrophy type 1 and spinocerebellar ataxia type 3Alexei Pushechnikov
Department of Chemistry and The Center of Excellence in Bioinformatics and Life Sciences, The State University of New York, 657 Natural Sciences Complex, Buffalo, New York 14260, USA
J Am Chem Soc 131:9767-79. 2009..These studies suggest a general approach to targeting RNA, including those that cause RNA dominant disease...
- Transcriptional and post-transcriptional impact of toxic RNA in myotonic dystrophyRobert J Osborne
Department of Neurology, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642, USA
Hum Mol Genet 18:1471-81. 2009....
- Cell-free cloning of highly expanded CTG repeats by amplification of dimerized expanded repeatsRobert J Osborne
Department of Neurology, University of Rochester School of Medicine and Dentistry, 601 Elmwood Avenue, Rochester, NY 14642, USA
Nucleic Acids Res 36:e24. 2008..Amplification of dimerized expanded repeats (ADER) opens new possibilities for studies of repeat instability and pathogenesis in myotonic dystrophy, a neurological disorder caused by an expanded CTG repeat...
- Correction of ClC-1 splicing eliminates chloride channelopathy and myotonia in mouse models of myotonic dystrophyThurman M Wheeler
Department of Neurology, University of Rochester, Rochester, New York 14618, USA
J Clin Invest 117:3952-7. 2007....
- Myotonic dystrophy: RNA-mediated muscle diseaseThurman M Wheeler
Department of Neurology, University of Rochester, Rochester, New York, USA
Curr Opin Neurol 20:572-6. 2007..The aim of this review is to highlight recent progress in elucidating the disease mechanism in myotonic dystrophy type 1 and type 2...
- Ribonuclear foci at the neuromuscular junction in myotonic dystrophy type 1T M Wheeler
Department of Neurology, University of Rochester, 601 Elmwood Avenue, Box 673, Rochester, NY 14642, USA
Neuromuscul Disord 17:242-7. 2007..Our findings indicate that subsynaptic nuclei and motor neurons are at risk for DM1-induced spliceopathy, which may affect function or stability of the neuromuscular junction...
- Muscle chloride channel dysfunction in two mouse models of myotonic dystrophyJohn D Lueck
Department of Physiology and Pharmacology, University of Rochester, Rochester, NY 14642, USA
J Gen Physiol 129:79-94. 2007....
- Chloride channelopathy in myotonic dystrophy resulting from loss of posttranscriptional regulation for CLCN1John D Lueck
Department of Pharmacology and Physiology, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642, USA
Am J Physiol Cell Physiol 292:C1291-7. 2007....
- RNA-dominant diseasesRobert J Osborne
Department of Neurology, University of Rochester Medical Center, Rochester, NY 14642, USA
Hum Mol Genet 15:R162-9. 2006..This review describes some of the recent advances in understanding the pathophysiology of RNA-dominant diseases...
- Failure of MBNL1-dependent post-natal splicing transitions in myotonic dystrophyXiaoyan Lin
Department of Neuroscience, University of Rochester Medical Center, Rochester, NY 14642, USA
Hum Mol Genet 15:2087-97. 2006..Sequestration of MBNL1, and failure to maintain these splicing transitions, has a pivotal role in the pathogenesis of muscle disease in DM...