Selenoprotein W is a glutathione‐dependent antioxidant in vivo

Abstract

The function of selenoprotein W (Se‐W) was investigated by cloning the corresponding cDNA from mouse brain and expressing it in CHO cells and H1299 human lung cancer cells. Overexpression of Se‐W markedly reduced the sensitivity of both cell lines to H₂O₂ cytotoxicity. The intracellular peroxide concentration of the transfected cells was lower than that of the parental cells in the absence or presence of extracellular H₂O₂. The resistance to oxidative stress conferred by Se‐W was dependent on glutathione. Expression of Se‐W mutants in which selenocysteine‐13 or cysteine‐37 was replaced by serine did not confer resistance to H₂O₂, implicating these residues in the antioxidant activity of Se‐W in vivo.