UCP3 overexpression neutralizes oxidative stress rather than nitrosative stress in mouse myotubes

The deleterious effects of oxidants on proteins may be modified by overexpression of uncoupling protein 3 (UCP3) in skeletal muscle cells exposed to hyperoxia or H(2)O(2). UCP3 overexpression significantly attenuated the increase in protein carbonylation in response to hyperoxia and H(2)O(2) exposures. However, antioxidant enzyme content and activity (superoxide dismutases, peroxiredoxins, glutathione peroxidase-I, and catalase) were reduced or not modified in UCP3-overexpressing myotubes exposed to oxidants. Protein nitration increased in UCP3-overexpressing cells exposed to hyperoxia, but not to H(2)O(2). We conclude that protein oxidation rather than nitration is neutralized by UPC3 overexpression in mouse myotubes exposed to abundant reactive oxygen species.