c-Jun N-terminal kinase mediates hydrogen peroxide-induced cell death via sustained poly(ADP-ribose) polymerase-1 activation

Reactive oxygen species (ROS) have been closely associated with both apoptotic and non-apoptotic/necrotic cell death. Our previous study has illustrated that c-Jun-N-terminal kinase 1 (JNK1) is the main executor in hydrogen peroxide (H₂O₂)-induced nonapoptotic cell death. The main objective of this study is to further elucidate the molecular mechanisms downstream of JNK1 in H₂O₂- induced cell death. In this study, poly(ADP-ribose) polymerase-1 (PARP-1), a key DNA repair protein, was readily activated by H₂O₂ and inhibition of PARP-1 activation by either a pharmacological or genetic approach offered significant protection against H₂O₂-induced cell death. More importantly, H₂O₂-mediated PARP-1 activation is subject to regulation by JNK1. Suppression of JNK1 activation by a chemical inhibitor or genetic deletion markedly suppressed the late-phase PARP-1 activation induced by H₂O₂, suggesting that JNK1 contributes to the sustained activation of PARP-1. Such findings were supported by the temporal pattern of nuclear translocation of activated JNK and a direct protein-protein interaction between JNK1 and PARP-1 in H₂O₂-treated cells. Finally, in vitro kinase assay suggests that PARP-1 may serve as the direct phosphorylation target for JNK1. Taken together, data from our study reveal a novel underlying mechanism in H₂O₂-induced nonapoptotic cell death: JNK1 promotes a sustained PARP-1 activation via nuclear translocation, protein-protein interaction and PARP-1 phosphorylation.