Calpain-1 is required for hydrogen peroxide-induced myotube atrophy

Abstract

Recent reports suggest numerous roles for cysteine proteases in the progression of skeletal muscle atrophy due to disuse or disease. Nonetheless, a specific requirement for these proteases in the progression of skeletal muscle atrophy has not been demonstrated. Therefore, this investigation determined whether calpains or caspase-3 is required for oxidant- induced C2C12 myotube atrophy. We demonstrate that exposure to hydrogen peroxide (25 (μMH 2O 2) induces myotube oxidative damage and atrophy, with no evidence of cell death. Twenty-four hours of exposure to H 2O 2 significantly reduced both myotube diameter and the abundance of numerous proteins, including myosin ( - 81%), a-actinin (-40%), desmin (-79%), talin (-37%), and troponin I ( - 80%). Myotube atrophy was also characterized by increased cleavage of the cysteine protease substrate αII-spectrin following4hand 24hofH2O2 treatment. This degradation was blocked by administration of the protease inhibitor leupeptin (10 μM). Using small interfering RNA transfection of mature myotubes against the specific proteases calpain-1, calpain-2, and caspase-3, we demonstrated that calpain-1 is required for H 2O 2-induced myotube atrophy. Collectively, our data provide the first evidence for an absolute requirement for calpain-1 in the development of skeletal muscle myotube atrophy in response to oxidant-induced cellular stress. © 2009 the American Physiological Society.