Faulty membrane repair causes complications

During vigorous exercise, heart muscle cells take a beating. In fact, some of those cells rupture and, if not for a repair process capable of resealing cell membranes, those cells would die and cause heart damage (cardiomyopathy). Researchers at the University of Iowa, Iowa City, have discovered a specific repair mechanism in heart muscle and identified a protein called dysferlin that is critical for resealing heart muscle cell membranes. The study also shows that loss of dysferlin causes cardiomyopathy. Furthermore, heart damage is exaggerated by vigorous exercise or by inherent muscle weakness caused by a muscular dystrophy defect.

Active tissues, like a beating heart or contracting muscle, need mechanisms to repair the inevitable cell membrane tears caused by physical stress and strain. Researcher Kevin Campbell and his colleagues identified dysferlin as a key protein in this vital repair mechanism in skeletal muscle. in humans, dysferlin deficiency--which leads to faulty muscle membrane repair--causes three types of muscular dystrophy.

The study expands knowledge of dysferlin function, showing that dysferlin-mediated membrane repair also is important in heart muscle cells and suggests that inadequate membrane repair also can lead to cardiomyopathy. "If we could boost this repair mechanism, it might be possible to slow cardiac and skeletal muscle damage in muscular dystrophy patients," says Campbell, who holds the Biomedical Research Chair in Molecular Physiology.

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