Prion protein protects against DNA damage induced by paraquat in cultured cells

Exposure of cells to paraquat leads to production of superoxide anion (O2*-). This reacts with hydrogen peroxide to give the hydroxyl radical (*OH), leading to lipid peroxidation and cell death. In this study, we investigated the effects of cellular prion protein (PrPC) overexpression on paraquat-induced toxicity by using an established model system, rabbit kidney epithelial A74 cells, which express a doxycycline-inducible murine PrPC gene. PrPC overexpression was found to significantly reduce paraquat-induced cell toxicity, DNA damage, and malondialdehyde acid levels. Superoxide dismutase (total SOD and CuZn-SOD) and glutathione peroxidase activities were higher in doxycycline-stimulated cells. Our findings clearly show that PrPC overexpression plays a protective role against paraquat toxicity, probably by virtue of its superoxide dismutase-like activity.