Abstract

Duchenne muscular dystrophy is an incurable, genetic neuromuscular disorder that causes progressive, severe muscle wasting in young men and eventually leads to early death. The disease is caused by a mutation in the gene encoding the cytoskeletal protein dystrophin, which leads to stress induced sarcolemmal tearing. Abnormally high levels of intracellular Ca2+ in muscle cells is a main feature of the disorder as it triggers many secondary effects that are detrimental to the proper functioning of skeletal muscle. Both utrophin and HSP70 have been suggested to have potential therapeutic potential as a result of their preferential expression in the relatively damage-resistant slow, oxidative fibres. In my studies, I found that by forcing transgenic expression of the Ca2+ chelator parvalbumin in slow fibres, utrophin expression in slow fibres was blunted without altering HSP70 expression. In this case, the slow fibres showed increased signs of stress and damage therefore suggesting that endogenous HSP70 alone may not spare dystrophin deficient muscle fibres. These results indicate that utrophin (but not HSP70) is a potential therapeutic target that will prevent muscle degeneration in patients with DMD.