Wrecking Repair

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Science  30 May 2003:
Vol. 300, Issue 5624, pp. 1343
DOI: 10.1126/science.300.5624.1343a

The muscular dystrophies represent a group of heritable disorders causing progressive physical decline due to skeletal muscle wasting. Mutations in the gene that encodes dysferlin cause two distinct muscular dystrophies—Miyoshi myopathy and limb-girdle muscular dystrophy type 2B. Basal et al. examined the cellular defects that are responsible for the decline seen in these patients. The muscle cells from mice engineered to lack dysferlin possessed normal levels of the dystrophin glycoprotein complex, whose disruption is responsible for the most common form of muscular dystrophy. However, dysferlin was shown to be key to the repair of muscle cell membranes damaged during the normal wear and tear caused by movement. Small tears in the muscle cell membranes are a common occurrence during activity, and it appears that dysferlin-rich vesicles normally repair these tears by undergoing calcium-dependent fusion with the cell membrane. In mutant dysferlin-deficient muscle fibers, vesicles accumulate at the site of membrane disruption but fail to fuse and seal the damaged membranes.—SMH

Nature 423, 168 (2003).

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