The role of the death-domain kinase RIP in tumour-necrosis-factor-induced activation of mitogen-activated protein kinases

The death-domain kinase RIP (receptor-interacting protein) is an important effector of tumour necrosis factor (TNF) signalling and is essential for TNF-induced nuclear factor-kappaB activation. However, the function of RIP in the TNF-induced activation of mitogen-activated protein kinases (MAPKs) has not been fully investigated. In this report, using Rip null (Rip(-/-)) mouse fibroblast cells, we investigated whether RIP is required for TNF-induced activation of the MAPKs extracellular-signal-related kinase (ERK), p38 and c-Jun amino-terminal kinase (JNK). We found that TNF-induced activation of ERK, p38 and JNK is decreased in Rip(-/-) cells. The activation of these kinases by interleukin-1 is normal in Rip(-/-) cells. More importantly, we showed that the kinase activity of RIP is needed for ERK activation.