Abstract
RIPK1 regulates cell death and inflammation and has been implicated in the pathogenesis of inflammatory diseases. RIPK1 autophosphorylation promotes cell death induction; however, the underlying mechanisms and the role of specific autophosphorylation sites remain elusive. Using knock-in mouse models, here we show that S161 autophosphorylation has a critical physiological function in RIPK1-mediated cell death and inflammation. S161N substitution partially suppressed RIPK1-mediated catalytic activity and cell death induction but was sufficient to prevent skin inflammation induced by keratinocyte necroptosis or apoptosis in relevant mouse models. Combined S161N and S166A mutations synergized to prevent RIPK1-mediated cell death more efficiently than the single site mutations, revealing functional redundancy. Moreover, phosphomimetic S161E mutation could overcome the necroptosis-inhibitory effect of S166A mutation, revealing that S161 phosphorylation is sufficient for necroptosis induction. Collectively, a functional interplay of S161 and S166 phosphorylation events regulates RIPK1-dependent cell death and inflammation.