Gene muscles in on Type 2 diabetes

There are genes for eye colour, genes for intelligence, and now researchers at the Garvan Institute of Medical Research have discovered a gene that appears to regulate muscle growth.

By understanding how the gene functions it may be possible to alter muscle growth, which is not only hot news for anyone seeking a six pack, but also for sufferers of Type 2 diabetes.

The role of the gene, Grb10, was identified by Dr Lowenna Holt, Associate Professor Greg Cooney and Professor Roger Daly from the Garvan, who observed its effects in mice.

They found that a particular strain of genetically modified mice, which were missing the Grb10 protein, had large muscles. Even newborn mice missing Grb10 had larger muscles, indicating that this protein regulates muscle development before birth.

“Our main finding is that Grb10 plays a role in regulating the size of muscles during embryonic development, mainly by increasing the number of muscle fibres in the muscle, which is unusual,” said Dr Holt. “Usually muscles become bigger by increasing the size of each fibre.”

“We compared global gene expression in large versus normal muscle using gene microarrays and a computer program to visualise changes in gene networks.

“We saw more replication and proliferation gene sets in the Grb10 knockout muscle, telling us that processes causing proliferation of muscle stem cells could be controlled by Grb10 in the embryo.

“We also found that gene sets for muscle development were increased.”

The finding could have relevance to Type 2 diabetes, which is a disorder that occurs when the body can no longer control blood sugar levels properly. However, muscles are the greatest consumers of glucose in the body, so more muscles means less blood sugar.

A drug able to reduce Grb10 expression would increase muscle mass, and so increase the capacity to move glucose from the blood stream into cells, a major goal for any diabetes therapy.

The drug might also be useful for treating muscular dystrophy, where the muscles become weakened and damaged.

The study was published in The Journal of the Federation of American Societies for Experimental Biology.