A polypeptide from Chlamys farreri abolishes UV-induced apoptosis in murine thymocytes in vitro

Previously we reported that a polypeptide from Chlamys farreri (PCF) was a potent photoprotective agent against ultraviolet (UV) irradiation in vitro. To understand the mechanism by which PCF protects cells from irradiation, we studied anti-apoptotic effects of PCF against UV irradiation on the murine thymocytes in vitro. MTT and flow cytometric analysis assays showed that 2 h pretreatment with PCF completely abolished UV induced cell death. TEM examination showed that PCF fully protected the ultrastructure of thymocytes exposed to UV irradiation. Lipid peroxidation and intracellular reactive oxygen species assays indicated that PCF efficiently blocked production of reactive oxygen intermediates induced by UV irradiation. Further, PCF protected UV-irradiated thymocytes from losing mitochondrial transmembrane potential and DNA fragmentation. Based on these observations we propose that PCF is a potent anti-apoptotic factor, which protects cells from irradiation at multiple steps.