Polypeptide from Chlamys farreri inhibits murine thymocytes apoptosis and modulates UVB induced signaling pathway activation

Polypeptide from Chlamys farreri (PCF) has been identified as a potent antioxidant and photoprotective agent. In this study, we investigated whether PCF could inhibit apoptosis of murine thymocytes induced by ultraviolet B (UVB) and modulate UVB induced the mitogen-activated protein kinases (MAPKs) cascade in vitro. Our results show that PCF inhibit UVB-induced apoptotic cell death in murine thymocytes. We also found that PCF potently stimulated the phosphorylation of ERKs, which is involved in the cell survival-signaling cascade. Furthermore, the specific inhibition of the ERKs pathways by PD98059 reduced the cytoprotective effect of PCF. On the other hand, the JNKs and p38 inhibitor SP600125 and SB203580 additively enhanced the cytoprotective effect of PCF. We concluded that the activation of JNKs and p38 kinase played an important role in UVB-induced apoptosis, and PCF likely exerted its cytoprotective effect in thymocytes through ERKs activation. These suggested that part of the antiapoptotic effect of PCF might be mediated by its ability to modulate the MAPKs cascade.