Crucial Roles of the RIP Homotypic Interaction Motifs of RIPK3 in RIPK1-Dependent Cell Death and Lymphoproliferative Disease.

Receptor-interacting protein kinase 3 (RIPK3) has been identified as an essential regulator of necroptosis, apoptosis, and inflammatory signaling. RIPK3 contains an N-terminal kinase domain and a C-terminal RIP homotypic interaction motif (RHIM). However, the physiological roles of RIPK3 RHIM remain unclear. Here we generate knockin mice endogenously expressing the RIPK3 RHIM mutant, RIPK3V448P. Cells expressing RIPK3V448P are resistant to RIPK1 kinase-dependent apoptosis and necroptosis, and Ripk3V448P/V448P mice rescue embryonic lethality of Fadd-deficient mice by intercrossing. Strikingly, Ripk3V448P/V448PFadd-/- mice display more severe lymphoproliferative disease with a marked increase in abnormal CD3+B220+ lymphocytes compared with Ripk3-/-Fadd-/- mice. More importantly, these inflammatory morbidities in Ripk3V448P/V448PFadd-/- mice are profoundly inhibited by additional deletion of Ripk1. Taken together, these results reveal a previously unidentified physiological function of RHIM of RIPK3 in regulating RIPK1-dependent cell death and lymphoproliferative disease.