Beyond necroptosis: structural determinants, context-dependent non-canonical functions, and precision therapeutic targeting of RIPK3.

Abstract

Receptor-interacting protein kinase 3 (RIPK3) is classically recognized as a central executor of necroptosis, but accumulating evidence indicates that its functions extend beyond lytic cell death. RIPK3 regulates metabolic processes, inflammatory signaling, organelle homeostasis, and stress responses through both kinase-dependent and kinase-independent mechanisms. In this review, we summarize the structural and regulatory basis of RIPK3 activation, including RIP homotypic interaction motif (RHIM)-mediated complex assembly, conformational regulation, and post-translational modification (PTM) networks that influence signaling outcomes. Recent structural and pharmacological studies have revealed druggable conformational states within the RIPK3 kinase domain and demonstrated that inhibitor-induced conformational changes can affect downstream signaling beyond catalytic inhibition. We further discuss non-canonical RIPK3 functions in mitochondrial metabolism, inflammasome regulation, autophagy, senescence, and immune regulation, highlighting the importance of cellular context, metabolic state, and signaling environment in determining RIPK3 activity. RIPK3 can therefore contribute to either tissue protection or pathological inflammation depending on the biological setting. Finally, we review emerging therapeutic strategies, including interaction-selective targeting, PTM-based modulation, cell-type-specific delivery, and conformation-selective inhibitor design, which aim to suppress disease-associated RIPK3 signaling while preserving its physiological functions.