| Summary: | Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Biology, 2001. === Includes bibliographical references. === Myotonic Dystrophy type 1 (DM1), the most common form of adult-onset skeletal muscle dystrophy, is caused by expansion of a CTG repeat sequence embedded in the 3'UTR of a gene which encodes a serine threonine kinase, DMPK. The precise mechanism by which CTG repeat expansion causes the complex pathology of DM1 is under active investigation. Repeat expansion leads to a failure of transport of DMPK mRNA from nucleus to cytoplasm indicating that reduction in DMPK expression levels is at least one major consequence of repeat expansion. Mouse models suggest that haploinsufficiency of DMPK accounts for at least a portion of the symptoms of DM1. DMPK -/- mice exhibit a progressive muscle myopathy similar to that seen in DM1, and both DMPK -/- and DMPK +/- mice reiterate cardiac conduction abnormalities characteristic of DM1 patients. However, the in vivo role of DMPK, the identity and nature of its substrate(s) and the biological pathway(s) within which it functions remain to be elucidated. To determine the in vivo function of DMPK I have taken a proteomics-based approach that utilizes 2-dimensional SDS-PAGE and mass spectrometry to compare directly heart proteins of wild-type and DMPK -/- mice in order to identify proteins that are altered in the absence of DMPK. === (cont.) I have identified several proteins with altered mobility on 2D SDS-PAGE gels in mutant versus wild-type cells in heart and peripheral muscle of DMPK-/- animals. Two of these were analyzed by mass spectrometry and identified as fatty acid binding proteins (FABPs). The altered mobility of these proteins suggests that they have different properties in the absence of DMPK. Further investigation of these FABPs could potentially shed light into the in vivo role of DMPK and into the biological pathway(s) in which DMPK functions. === by Brenda Sierra Luciano. === Ph.D.
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