Mice that grow larger muscles and can run for twice as long as their unaltered littermates before tiring could point toward new treatments for the muscle loss that can occur with aging.
The mice were engineered to lack a molecule called NCOR in their muscle tissue. In a second, related study, knocking out the same molecule in fat resulted in mice that were overweight but sensitive to insulin, a result that could lead to more targeted treatments for diabetes. Both studies were published in the journal Cell last week.
NCOR acts as a dimmer switch for other molecules in a cell. It is known as a corepressor, slowing the production of transcription factors, which in turn regulate the expression of genes. Dimmer-switch molecules are often good drug targets thanks to this subtle effect, says Johan Auwerx, a researcher at École Polytechnique Fédérale de Lausanne, who led the first study, which involved knocking out NCOR in muscle. "That's better from a medical standpoint, because you don't want to turn a molecule all on or off," he says.