Three-Protein Repair Cluster Identified

Scientists in the United States and Japan have identified a three-protein cluster that reseals damaged muscle-fiber membranes. The findings, published June 5, 2009, in the Journal of Biological Chemistry, could have implications for development of treatments for muscular dystrophies.






The Muscle Fiber Membrane
Defects in the muscle-fiber membrane underlie many muscular dystrophies. The newly identified "repair complex" consisting of mitsugumin 53, caveolin 3 and dysferlin provides a new therapeutic target.

Jianjie Ma at the Robert Wood Johnson Medical School in Piscataway, N.J., coordinated the multinational team, whose findings build on earlier research, especially a paper published in Nature Cell Biology by many of the same U.S. and Japanese researchers in January 2009.

In experiments using mouse muscle fibers, the investigators determined that mitsugumin 53 (MG53), a protein they announced in January as contributing to muscle-fiber repair, works closely with two other proteins, dysferlin and caveolin 3.

Scientists have known for a few years that dysferlin is involved in muscle-fiber membrane repair and that mutations of the gene for dysferlin or caveolin 3 can cause limb-girdle muscular dystrophy (LGMD). They've also known that mutations of dysferlin can cause Miyoshi myopathy, a form of distal muscular dystrophy.

Now it appears that these three proteins -- dysferlin, caveolin 3 and MG53 -- form a cluster (complex) that repairs damaged membranes. Targeting the molecular functions of this cluster provides a new and promising avenue for therapeutic research, the researchers say.

Such research is especially important for muscular dystrophies in which membrane damage plays a major role, such as Duchenne muscular dystrophy (DMD), Becker muscular dystrophy (BMD), some types of limb-girdle muscular dystrophy (LGMD) and possibly some types of congenital muscular dystrophy (CMD).

For more on this, see the April Quest Extra article “New Membrane Repair Protein Identified.”

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