The study of muscular system protein myostatin has been of great interest to researchers as a potential therapeutic target for people with muscular disorders. Although much is known about how myostatin affects muscle growth, there has been disagreement about what types of muscle cells it acts upon. New research from a team including Carnegie's Chen-Ming Fan and Christoph Lepper narrows down the field to one likely type of cell. Their work is published the week of August 6 by Proceedings of the National Academy of Sciences.
Myostatin is known to inhibit muscle growth and its function is common in many mammals, including cows, sheep, dogs, humans, and mice. Mutant mice lacking in myostatin have muscle mass that is almost double that of normal mice. This property is what makes it an attractive potential drug target. By inhibiting myostatin a drug could, in theory, promote muscle growth, even in a person with a muscular disease.
There has been considerable debate about which types of muscle cells are targeted by myostatin: fibrous muscle cells called myofibers, or muscle stem cells called satellite cells. The satellite cells are activated by muscular injury, begin to divide, and fuse to myofibers. Some studies seem to indicate myostatin targets satellite cells, others indicate myofibers.
The research team, co-led by Fan and Se-Jin Lee, who is a former Carnegie Staff Associate and currently at Johns Hopkins University Medical School, used a variety of techniques-both genetic and pharmacological-and determined that the muscle growth caused by inhibiting myostatin does not significantly involve the incorporation of satellite cells into myofibers.