Sphingosine 1-phosphate attenuates H2O2-induced apoptosis in endothelial cells

Reactive oxygen species including H2O2 lead vascular endothelial cells (EC) to undergo apoptosis. Sphingosine 1-phosphate (S1P) is a platelet-derived sphingolipid mediator that elicits various EC responses. We aimed to explore whether and how S1P modulates EC apoptosis induced by H2O2. Treatment of cultured bovine aortic EC (BAEC) with H2O2 (750 μM for 6 h) led to DNA fragmentation (ELISA), DNA nick formation (TUNEL staining), and cleavage of caspase-3, key features of EC apoptosis. These responses elicited by H2O2 were alike markedly attenuated by pretreatment with S1P (1 μM, 30 min). H2O2 induced robust phosphorylation of both p38 and JNK MAP kinases. However, pretreatment with S1P decreased phosphorylation of only p38 MAP kinase, but not that of JNK; conversely, an inhibitor of p38 MAP kinase, but not that of JNK, attenuated H2O2-induced caspase-3 activation. Thus S1P attenuates H2O2-induced apoptosis of cultured BAEC, involving p38 MAP kinase.