Muscular dystrophies, congenital heart muscle defects, and other muscle disorders often arise for reasons that scientists don't fully understand. Now, researchers from the University of North Carolina (UNC) School of Medicine and the Baylor College of Medicine have discovered an important process in muscle cells whose disruption could turn out to be a cause of many of these disorders. The scientists found that, in mice, four key muscle-cell proteins are produced in a shorter, fetal form up to the first few weeks of life, after which production shifts to longer, adult forms of the proteins. This transition must occur in order for the adult muscle to function normally. Forcing adult muscle cells to produce the shorter, fetal forms leads to major structural problems in the cells and muscle weakness. "This is the first demonstration that this transition occurs for these proteins in muscle cells and is important for normal muscle function - and it sheds light on the overall functions of these four proteins, about which very little is known," said study co-senior author Jimena Giudice, Ph.D., a new Assistant Professor in the Department of Cell Biology and Physiology at the UNC School of Medicine. Thomas Cooper, M.D., Professor of Pathology and Immunology at Baylor College of Medicine and study co-senior author, said, "If we are to truly understand the full scope of functions of individual genes, we will need to determine the functions of the different protein isoforms that are generated from each gene.
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