Molecular Cell, 01 June 2017, Vol.66(5), pp.698-710.e5
TNF is an inflammatory cytokine that upon binding to its receptor, TNFR1, can drive cytokine production, cell survival, or cell death. TNFR1 stimulation causes activation of NF-κB, p38α, and its downstream effector kinase MK2, thereby promoting transcription, mRNA stabilization, and translation of target genes. Here we show that TNF-induced activation of MK2 results in global RIPK1 phosphorylation. MK2 directly phosphorylates RIPK1 at residue S321, which inhibits its ability to bind FADD/caspase-8 and induce RIPK1-kinase-dependent apoptosis and necroptosis. Consistently, a phospho-mimetic S321D RIPK1 mutation limits TNF-induced death. Mechanistically, we find that phosphorylation of S321 inhibits RIPK1 kinase activation. We further show that cytosolic RIPK1 contributes to complex-II-mediated cell death, independent of its recruitment to complex-I, suggesting that complex-II originates from both RIPK1 in complex-I and cytosolic RIPK1. Thus, MK2-mediated phosphorylation of RIPK1 serves as a checkpoint within the TNF signaling pathway that integrates cell survival and cytokine production. Jaco et al. show that MK2 directly phosphorylates RIPK1 at residue S321, suppressing the cytotoxic potential of RIPK1 and acting as a checkpoint within the TNF signaling pathway.
Tnf ; Ripk1 ; P38 ; Mk2 ; Cell Death ; Caspase-8 ; Necroptosis ; Iaps ; Cytokine ; Complex-II ; Biology
View record in ScienceDirect (Access to full text may be restricted)
View full text in ScienceDirect