Figure 9. RIP1 is a central signaling protein in regulation of TNF-α/TRAIL mediated extrinsic apoptosis and necroptosis during NDV infection.

NDV infection activates NF-κB, induces the expression and secretion of TNF-α and TRAIL. TNF-α and TRAIL binds to TNF receptor or TRAIL receptor on cell surface, and the pro-apoptotic complex is formed. Caspase 8 is activated and cleaves Bid and RIP1, promotes apoptosis. Meanwhile, full length RIP1 promotes the phosphorylation of MLKL. RIP1 binds to phosphor-MLKL and recruits it to SGs, prevents it move to plasma membrane, thereby inhibiting necroptosis.