NIH scientists identify gene that could hold the key to muscle repair
Researchers have long questioned why patients with Duchenne muscular dystrophy (DMD) tend to manage well through childhood and adolescence, yet succumb to their disease in early adulthood, or why elderly people who lose muscle strength following bed rest find it difficult or impossible to regain.
Akinso: Researchers at the National Institutes of Health have found a gene that could be the key to treating the condition known as Duchenne muscular dystrophy. Patients with the condition tend to manage well through childhood and adolescence, yet succumb to their disease in early adulthood.
Sartorelli:Usually children are in wheelchairs by twelve thirteen years old and they usually succumb to the condition when they are 20.
Akinso: Duchenne muscular dystrophy is an inherited disorder that involves rapidly worsening muscle weakness, explains Dr. Vittorio Sartorelli, a senior investigator at the NIH.
Sartorelli:And because of the mechanical properties of the muscle every time that there is contraction there is some sort of wear and tear effect. And so the muscle gets damaged, because the cell membrane is not intact. If the cell membrane is not perfectly ceiled every time that we have contraction you get a little big of damage and that is responsible for the degeneration of the muscle.
Akinso: This is also why elderly people who lose muscle strength following bed rest find it difficult or impossible to regain. The causes may lie in a specialized population of cells called satellite cells. Satellite cells are key to the development of skeletal muscle of the embryo and fetus, and they continue to actively increase muscle mass through infancy. After that, they decrease in number and become inactive, until they are activated by injury or degeneration to proliferate. Dr. Sartorelli and researchers have looked at a particular gene to see how it affected satellite cell growth.
Sartorelli:The gene is called Ezh2. It helps in understanding the biology and before therapy you have to understand the biology. Before fixing a car you have understand how that car works when itís fine. We have defined a molecule Ezh2 that is essential for satellite cells proliferation.
Akinso: Suspecting a genetic switch that might turn off satellite cell proliferation in these circumstances, the scientists looked to the Ezh2 gene. When they genetically inactivated Ezh2 in satellite cells of laboratory mice, the mice failed to repair muscle damage caused by traumatic injury Ė the satellite cells could not proliferate. Dr. Sartorelli cautions that while the identification of Ezh2ís role is a crucial step, any therapies are still many years away. For more information on this study, visit www.niams.nih.gov. This is Wally Akinso at the National Institutes of Health, Bethesda, Maryland.
About This Audio Report
Reporter: Wally Akinso
Sound Bite: Dr. Sartorelli
Topic: Duchenne, muscular, dystrophy, muscle, repair