Arginine Di-methylation of RIP3 safeguards necroptosis for intestinal homeostasis.

Necroptosis, driven by RIP3, is critical for intestinal homeostasis but requires stringent regulation to prevent inflammatory pathology. While inhibitory checkpoints of RIP3 are known, mechanisms enabling its physiological activation remain unclear. We identify PRMT5-mediated symmetric di-methylation of RIP3 at arginine 479 (R479) serves as a gatekeeper specifically suppresses RIP1- but not ZBP1- driven necroptosis in intestinal epithelial cells (IECs). Notably, even though STORM super-resolution imaging and molecular dynamics simulations revealed that R479 methylation adjacent to the RHIM domain sterically blocks RIP3 oligomerization both with RIP1 and ZBP1. Mice harboring IEC-specific Rip3R479K knockin mutation developed spontaneous necroptosis-driven colitis in vivo, directly linking this PTM to pathogenesis. Leveraging these insights, we engineered an SDMA-mimetic peptide that competitively inhibit necroptosis, rescuing Prmt5-deficient mice from lethal colitis without disrupting global signaling homeostasis. Unlike conventional kinase inhibitors, this "methylation mimicry" strategy selectively targets pathogenic cell death, offering a therapeutically actionable advance for IBD and related disorders.