OVEREXPRESSION OF MANGANESE SUPEROXIDE-DISMUTASE PREVENTS METHYLMERCURY TOXICITY IN HELA-CELLS

HeLa cells were stably transformed with plasmid constructs thar allowe d constitutive expression of antioxidant enzymes such as catalase, glu tathione peroxidase (GSH-Px), Cu,Zn-superoxide dismutase (Cu,Zn-SOD) o r Mn-superoxide dismutase (Mn-SOD) to examine the involvement of react ive oxygen generation in methylmercury toxicity. Overexpression of cat alase, GSH-Px or Cu,Zn-SOD did not affect the sensitivity of HeLa cell s against methylmercury. However, the sensitivity of HeLa cells agains t methylmercury was decreased by overexpression of an enzyme localized in matrix of mitochondria and which decomposes superoxide anions. The se results suggest that formation of superoxide anions in the mitochon dria might be involved in the mechanism of the cytotoxicity of methylm ercury. (C) 1998 Elsevier Science Inc.