Pratyusha Mandal; Scott B. Berger; Sirika Pillay; Kenta Moriwaki; Chunzi Huang; Hongyan Guo; John D. Lich; Joshua Finger; Viera Kasparcova; Bart Votta; Michael Ouellette; Bryan W. King; David Wisnoski; Ami S. Lakdawala; Michael P. DeMartino; Linda N. Casillas; Pamela A. Haile; Clark A. Sehon; Robert W. Marquis; Jason Upton; Lisa P. Daley-Bauer; Linda Roback; Nancy Ramia; Cole M. Dovey; Jan E. Carette; Francis Ka-Ming Chan; John Bertin; Peter J. Gough; Edward S. Mocarski; William J. Kaiser
Molecular Cell, 2014, 56, 481–495
https://doi.org/10.1016/j.molcel.2014.10.021

Abstract

Receptor-interacting protein kinase 3 (RIP3 or RIPK3) has emerged as a central player in necroptosis and a potential target to control inflammatory disease. Here, three selective small-molecule compounds are shown to inhibit RIP3 kinase-dependent necroptosis, although their therapeutic value is undermined by a surprising, concentration-dependent induction of apoptosis. These compounds interact with RIP3 to activate caspase 8 (Casp8) via RHIM-driven recruitment of RIP1 (RIPK1) to assemble a Casp8-FADD-cFLIP complex completely independent of pronecrotic kinase activities and MLKL. RIP3 kinase-dead D161N mutant induces spontaneous apoptosis independent of compound, whereas D161G, D143N, and K51A mutants, like wild-type, only trigger apoptosis when compound is present. Accordingly, RIP3-K51A mutant mice (Rip3K51A/K51A) are viable and fertile, in stark contrast to the perinatal lethality of Rip3D161N/D161N mice. RIP3 therefore holds both necroptosis and apoptosis in balance through a Ripoptosome-like platform. This work highlights a common mechanism unveiling RHIM-driven apoptosis by therapeutic or genetic perturbation of RIP3.