Myotonic dystrophy type 1 (DM1) is caused by a CTG expansion mutation located in the DMPK gene. The identification and characterization of RNA-binding proteins that interact with expanded CUG repeats and the discovery that a similar CCTG expansion in an intron causes myotonic dystrophy type 2 (DM2), have provided strong support that RNA gain of function effects play an important role in DM manifestations in skeletal muscle. Although the CNS deficits are one of the most clinically significant aspects of DM, the molecular mechanisms underlying these changes have been unclear. Progress during the current funding period extends our understanding of the CNS features of the disease and molecular mechanisms of microsatellite expansion mutations. Project #3 (PI: Day) has established that DM results in a striking diffuse abnormality of white matter integrity that parallels the cognitive deficits in children, and executive function deficits in adults. Project #2 (PI: Swanson) has extended our understanding of the role of RNA gain of function effects by demonstrating that another member of the MBNL gene family, MBNL2, is a critical regulator of alternative splicing during postnatal brain development. Project #1 (PI: Ranum) has made the unexpected discovery that microsatellite expansion mutations can express homopolymeric expansion proteins without the canonical AUG-initiation codon and that novel proteins accumulate in DM patient tissue. These results suggest novel expansion proteins contribute to DM. The focus of this proposal will be to better understand the clinical consequences of the DM1 and DM2 mutations and to relate specific clinical phenotypes to underlying molecular deficits. To accomplish these goals we propose 3 Projects and 2 Cores: Project 1: Repeat-Associated Non-ATG Translation in DM1 and DM2 Project 2: Mechanisms of RNA-Mediated CNS Pathogenesis in Myotonic Dystrophy Project 3: Clinical and Genetic Characterization of Myotonic Dystrophy Core A: Neuropathology/Functional Imaging Core Core B: Administrative Core.

Public Health Relevance

The goals of this Program are to understand how myotonic dystrophy mutations cause specific brain abnormalities that affect cognition and sleep. We will use an interdisciplinary approach to understand these problems and identify the underlying molecules that contribute to disease.

National Institute of Health (NIH)
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National Institute of Neurological Disorders and Stroke Initial Review Group (NSD)
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Nuckolls, Glen H
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University of Florida
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Pletnikova, Olga; Sloane, Kelly L; Renton, Alan E et al. (2014) Hippocampal sclerosis dementia with the C9ORF72 hexanucleotide repeat expansion. Neurobiol Aging 35:2419.e17-21
Mohan, Apoorva; Goodwin, Marianne; Swanson, Maurice S (2014) RNA-protein interactions in unstable microsatellite diseases. Brain Res 1584:3-14
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 56:311-22
Cleary, John Douglas; Ranum, Laura P W (2014) Repeat associated non-ATG (RAN) translation: new starts in microsatellite expansion disorders. Curr Opin Genet Dev 26:6-15
Wozniak, Jeffrey R; Mueller, Bryon A; Lim, Kelvin O et al. (2014) Tractography reveals diffuse white matter abnormalities in Myotonic Dystrophy Type 1. J Neurol Sci 341:73-8
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
Cramer, Samuel W; Gao, Wangcai; Chen, Gang et al. (2013) Reevaluation of the beam and radial hypotheses of parallel fiber action in the cerebellar cortex. J Neurosci 33:11412-24
Zhang, Chaolin; Lee, Kuang-Yung; Swanson, Maurice S et al. (2013) Prediction of clustered RNA-binding protein motif sites in the mammalian genome. Nucleic Acids Res 41:6793-807
Cleary, John D; Ranum, Laura P W (2013) Repeat-associated non-ATG (RAN) translation in neurological disease. Hum Mol Genet 22:R45-51

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