Aussie researchers find key to muscle growth
By Sid Astbury, dpa
September 11, 2012, 12:03 am TWN
Sydney--If there were an Olympics for mice, a team from Sydney's Garvan Institute of Medical Research would likely top the medal tables.
"These mice are bigger and stronger," researcher Greg Cooney said. "Pick one up and you can feel that they have greater capacity to pull and drag away from you."
The Garvan rodents did not put on muscle through hours on an exercise wheel but were bred that way in a project that holds out hope for those with muscle-wasting conditions as well as metabolic disorders like Type 2 diabetes.
A protein called Grb10 was absent while they were in the womb and they were born with bigger muscles.
"This model shows an increase in the number of muscle fibers rather than the size of fibers and that's unusual compared with other models where animals have bigger muscles because the fibers are bigger," Cooney said. "This is a different way of having bigger muscles."
Generations of the bulked-up mice have been born. Some are past their second birthday and have shown no ill effects from the manipulation of their genes. The hope is that reducing or eliminating Grb10 could help speed recovery in people with muscle injury.
"What might happen if you had a muscle injury is that the cells that replaced those injured muscles might do so more quickly and more effectively," Cooney said. "That's probably a reasonable scenario."
It is a long way down the track but there could be a pill to knock out Grb10. "Grb10 acts as a break on signal pathways that are involved in regeneration and growth. It's part of a normal mechanism for regulating growing too fast. Remove it and things go faster."
Cooney and his Garvan colleagues are buoyed by recent research elsewhere suggesting that reducing Grb10 might protect the pancreas from the damage which can cause diabetes.
"It's possible that drugs that limited the amount of this protein in specific tissues might well become available," he said. "If you could regulate what Grb10 is doing you might be able to help muscle regeneration and limit or repair the damage to the pancreas that leads to diabetes."
The Garvan research was published in the latest issue of FASEB, the journal of the Federation of American Societies for Experimental Biology.