HSP25 protects skeletal muscle cells against oxidative stress

Reactive oxygen species (ROS) may cause skeletal muscle degeneration in a number of pathological conditions. Small heat shock proteins (HSPs) have been found to confer resistance against ROS in different cell types; however, the importance of their antioxidant function in skeletal muscle cells remains to be determined. In the present study, differentiation of skeletal myoblasts resulted in protection against hydrogen peroxide-induced cell death and protein oxidation. This differentiation-induced resistance to oxidative stress was associated with increased protein expression of HSP25, increased glutathione levels, and glutathione peroxidase activity, but little change in catalase activity. Overexpression of HSP25 in stably transfected myoblasts produced dose-dependent protection against hydrogen peroxide-induced damage that was associated with increased glutathione levels and glutathione peroxidase activity. Inhibition of glutathione synthesis with buthionine sulfoximine abrogated the protection induced by HSP25 overexpression. These findings indicate that HSP25 may play a key role in regulating the glutathione system and resistance to ROS in skeletal muscle cells.