Myotonic dystrophy (DM) is the most common form of adult onset muscular dystrophy. DM is an autosomal dominant neuromuscular disorder that is caused by a (CTG)n repeat expansion in the 3' UTR of the DM protein kinase (DMPK) gene. The long term objective of the proposed research is to elucidate how a triplet repeat expansion in the 3' UTR of a gene leads to a dominantly inherited disease. Current evidence suggests that DM pathogenesis is associated with the accumulation of DMPK mutant allele transcripts within the nucleus. Our working 'sequestration' hypothesis is that DM is an RNA dominant disease in which the (CUG)n expansion forms an exceptionally stable double stranded RNA (dsRNA) hairpin structure. This unusual RNA hairpin acts as a high affinity binding site for triplet repeat expansion dsRNA binding proteins that possibly play important roles in nucleocytoplasmic RNA export. Large repeat expansions associated with severe disease lead to sequestration of these proteins on DMPK mutant allele transcripts and a dominant negative effect on the export of other RNAs. This proposal is focused on testing this RNA dominance model using several different experimental approaches. First, the hypothesis that (CUG)n expansion RNAs have a dominant negative effect on mRNA export will be directly examined using RNA microinjection into frog oocyte and mammalian fibroblast nuclei. Second, the sequestration hypothesis predicts that expansion binding proteins should accumulate in nuclear foci together with DMPK mutant transcripts. Therefore, we will complete the characterization of several proteins that preferentially recognize large (CUG)n expansions, and determine the subcellular distribution of these proteins in normal and DM patient cells. Third, preferred RNA binding sites for these expansion binding proteins will be characterized by in vitro and in vivo analyses with particular emphasis on identifying RNAs that normally associate with these proteins. Fourth, we will determine if expansion binding proteins are involved in mRNA export by combining the use of monoclonal antibodies and recombinant proteins with the microinjection system developed in the first aim. Fifth, the relevance of RNA dominance to other neuromuscular and neurological diseases will be investigated. These studies have important implications for elucidating molecular mechanisms involved in DM pathogenesis and cellular strategies which facilitate the exchange of genetic information between the nucleus and cytoplasm.

National Institute of Health (NIH)
National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS)
Research Project (R01)
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Cell Development and Function Integrated Review Group (CDF)
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Nuckolls, Glen H
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University of Florida
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Scotti, Marina M; Swanson, Maurice S (2016) RNA mis-splicing in disease. Nat Rev Genet 17:19-32
Coram, Ryan J; Stillwagon, Samantha J; Guggilam, Anuradha et al. (2015) Muscleblind-like 1 is required for normal heart valve development in vivo. BMC Dev Biol 15:36
Goodwin, Marianne; Mohan, Apoorva; Batra, Ranjan et al. (2015) MBNL Sequestration by Toxic RNAs and RNA Misprocessing in the Myotonic Dystrophy Brain. Cell Rep 12:1159-68
Davis, Jennifer; Salomonis, Nathan; Ghearing, Natasha et al. (2015) MBNL1-mediated regulation of differentiation RNAs promotes myofibroblast transformation and the fibrotic response. Nat Commun 6:10084
Rau, Frédérique; Lainé, Jeanne; Ramanoudjame, Laetitita et al. (2015) Abnormal splicing switch of DMD's penultimate exon compromises muscle fibre maintenance in myotonic dystrophy. Nat Commun 6:7205
Batra, Ranjan; Manchanda, Mini; Swanson, Maurice S (2015) Global insights into alternative polyadenylation regulation. RNA Biol 12:597-602
Batra, Ranjan; Charizanis, Konstantinos; Manchanda, Mini et al. (2014) Loss of MBNL leads to disruption of developmentally regulated alternative polyadenylation in RNA-mediated disease. Mol Cell 56:311-322
Mohan, Apoorva; Goodwin, Marianne; Swanson, Maurice S (2014) RNA-protein interactions in unstable microsatellite diseases. Brain Res 1584:3-14
Goodwin, Marianne; Swanson, Maurice S (2014) RNA-binding protein misregulation in microsatellite expansion disorders. Adv Exp Med Biol 825:353-88
Hernandez-Hernandez, Oscar; Guiraud-Dogan, Celine; Sicot, Geraldine et al. (2013) Myotonic dystrophy CTG expansion affects synaptic vesicle proteins, neurotransmission and mouse behaviour. Brain 136:957-70

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