Scientists discover 'Hulk' protein behind huge muscle growth

Scientists in Australia say they have discovered one of the molecular keys to a protein that promotes weight and muscle mass gain, without any exercise involved.

Researchers found that by blocking the function of Grb10, nicknamed the 'Hulk' protein, while mice were in the womb, they were considerably stronger and more muscular at birth than normal mice.

The study, published in the journal 'FASEB', has important implications for a wide range of conditions such as muscular dystrophy, Type 2 diabetes, and problems produced by muscle inflammation.

Grb10 seems to have a significant role in promoting muscle growth without any change in activity, diet, or adverse health effects, the researchers said.

"By identifying a novel mechanism regulating muscle development, our work has revealed potential new strategies to increase muscle mass," said Lowenna J Holt from the Diabetes and Obesity Research Program at the Garvan Institute of Medical Research in Sydney.

Holt and her colleagues compared two groups of mice, one with the Grb10 gene and the other where it was blocked.

Researchers examined the properties of the muscles in both adult and newborn mice and discovered that the increase caused by the loss of Grb10 had mainly occurred during prenatal development.

These results suggested that it may in future be possible to alter muscle growth and help faster healing, as the processes involved in muscle regeneration and repair are similar to those for the initial formation of muscle.

"Don't turn in your gym membership just yet," said Dr Gerald Weissmann, editor-in-chief of the 'FASEB' Journal.

"If you want big muscles, the classic prescription still applies: lift heavy things, eat and sleep right, and have your hormones checked," said Weissmann.

"But this study shows that when we understand the basic science of how muscle fibres grow and multiply, we will be able to lift the burden - literally - of muscle disease for many of our patients," he said.