The human genome initiative and other lines of genomics research have engendered powerful new research tools, such as microarray analysis of gene expression and transgenesis in mice. The candidate has taken a leading role 'in developing a framework to incorporate these methods into patient-oriented research. He now seeks to extend this framework and devote more effort to mentoring new investigators in this underserved field. Myototuic dystrophy (DM), the most common inherited muscle disease in adults, has been adopted as a test case for this integrative approach. Although the pathophysiology of DM historicaly has been problematic, this approach is yielding rapid progress. DM is caused by expansion of a CTG repeat in the DM protein kinase (DMTK) gene. The repeat is located 'in a region that is transcribed (as a CUG repeat) but not translated into protein. The candidate has developed evidence that the pathogenic effect of the expanded repeat is mediated at the level of RNA: transcripts with an expanded CUG repeat do not leave the nucleus, they accumulate in the nucleus in multiple discreet foci, and they are sufficient to generate a DM phenotype in transgenic mice. This work establishes a novel, RNA-mediated disease mechanism, provides the first animal model for DIM, and lays the groundwork for farther progress through parallel studies of human DM and the transgenic model.
Aim I is to elucidate the mechanism of myotonia. Preliminary data indicate that expanded CUG repeats trigger aberrant splicing of a chloride channel mRNA and corresponding loss of chloride conductance in the muscle membrane. an alteration sufficient to cause myotonia.
Aim 2 is to undertake a broad search for genes whose expression is altered in human and murine DM. Preliminary data indicate strong activation of genes that are involved in the genotoxic stress response.
Aim 3 is to identify proteins that colocalize with, and may be sequestered by the expanded CUG repeats. One such protein, EXP42, has already been identified. EYCP42 is the human homologue of a gene that causes muscle disease when mutated in Drosophi1a, making it a strong candidate for involvement in the pathogenesis of DM.
Aim 4 is tit determine whether deficiency of DMPK enhances the toxicity of expanded CUG repeats, and to explore the possibility that the mechanical and biochemical stress of myotonia contributes to the degeneration of muscle fibers. information from this study may have a therapeutic application.

Agency
National Institute of Health (NIH)
Institute
National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS)
Type
Midcareer Investigator Award in Patient-Oriented Research (K24)
Project #
1K24AR048143-01
Application #
6418329
Study Section
Special Emphasis Panel (ZAR1-TAS-C (O4))
Program Officer
Lymn, Richard W
Project Start
2002-05-01
Project End
2007-04-30
Budget Start
2002-05-01
Budget End
2003-04-30
Support Year
1
Fiscal Year
2002
Total Cost
$96,852
Indirect Cost
Name
University of Rochester
Department
Neurology
Type
Schools of Dentistry
DUNS #
208469486
City
Rochester
State
NY
Country
United States
Zip Code
14627
Nakamori, Masayuki; Sobczak, Krzysztof; Puwanant, Araya et al. (2013) Splicing biomarkers of disease severity in myotonic dystrophy. Ann Neurol 74:862-72
Sobczak, Krzysztof; Wheeler, Thurman M; Wang, Wenli et al. (2013) RNA interference targeting CUG repeats in a mouse model of myotonic dystrophy. Mol Ther 21:380-7
Ofori, Leslie O; Hoskins, Jason; Nakamori, Masayuki et al. (2012) From dynamic combinatorial 'hit' to lead: in vitro and in vivo activity of compounds targeting the pathogenic RNAs that cause myotonic dystrophy. Nucleic Acids Res 40:6380-90
Mankodi, Ami; Wheeler, Thurman M; Shetty, Reena et al. (2012) Progressive myopathy in an inducible mouse model of oculopharyngeal muscular dystrophy. Neurobiol Dis 45:539-46
Chen, Catherine Z; Sobczak, Krzysztof; Hoskins, Jason et al. (2012) Two high-throughput screening assays for aberrant RNA-protein interactions in myotonic dystrophy type 1. Anal Bioanal Chem 402:1889-98
Tang, Zhen Zhi; Yarotskyy, Viktor; Wei, Lan et al. (2012) Muscle weakness in myotonic dystrophy associated with misregulated splicing and altered gating of Ca(V)1.1 calcium channel. Hum Mol Genet 21:1312-24
Wheeler, Thurman M; Leger, Andrew J; Pandey, Sanjay K et al. (2012) Targeting nuclear RNA for in vivo correction of myotonic dystrophy. Nature 488:111-5
López Castel, Arturo; Nakamori, Masayuki; Tomé, Stephanie et al. (2011) Expanded CTG repeat demarcates a boundary for abnormal CpG methylation in myotonic dystrophy patient tissues. Hum Mol Genet 20:1-15
Nakamori, Masayuki; Pearson, Christopher E; Thornton, Charles A (2011) Bidirectional transcription stimulates expansion and contraction of expanded (CTG)*(CAG) repeats. Hum Mol Genet 20:580-8
López Castel, Arturo; Nakamori, Masayuki; Thornton, Charles A et al. (2011) Identification of restriction endonucleases sensitive to 5-cytosine methylation at non-CpG sites, including expanded (CAG)n/(CTG)n repeats. Epigenetics 6:416-20

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