The Study Of Roles Of ZBP1 In IFN-mediated Necroptosis

Interferons(IFNs)are important cytokines with immunodulatory and antiviral function.IFNs are mainly divided into two types,type ? and type ?.Both of these two groups exert their roles through JAK(Janus kinase)-STAT(signal transducers and activators of transcription)signaling pathway.IFNs can induce the expression of about 500 ISGs(IFN-stimulated genes)to trigger the immunodulatory and antiviral signaling.Recent evidence has suggested that RIP3-MLKL axis is required for TNF-mediated necroptosis,and EADD and Caspase-8 function as negative regulators.Necroptosis induced by IFNs can be observed in RIP1,FADD,Caspase-8 deficient cells.However,the molecular mechanism of IFN-induced necrosis is not well clarified.In the present study,we generate RIP1,FADD,Capase-8 knockout L929 cells to investigate the mechanism of IFN-mediated necroptosis.Our results demonstrate that IFN can induce necroptosis and the phosphorylation of RIP3 in RIP1,FADD,Capase-8 knockout L929 cells.Moreover,RIP3-MLKL axis and the kinase activity of RIP3 are indispensable in the process of IFN-induced cell death.Futhermore,TNFR1 and PKR are not required for IFN-induced cell death whereas ZBP1 is essential.ZBP1-RIP3-MLKL can form a complex to exert their role in the IFN-induced necroptosis,and dimerization of ZBP1 can trigger cell death directly.Lastly,ZBP1 deficient mice can partially protect the lethality mediated by TNF+IFN-?.Overall,our results suggest the pivotal role of ZBP1 for IFN-induced necroptosis in RIP1,FADD,Capase-8 knockout L929 cells.