RNF186 is an E3 ubiquitin ligase that regulates multiple cellular processes critical for tissue homeostasis and disease prevention. Its primary function involves ubiquitin-dependent protein modification, mediating both K48- and K63-linked ubiquitination of diverse substrates 1. In the intestine, RNF186 maintains homeostasis through EFNB1-EPHB2-mediated autophagy activation in colonic epithelial cells 2. Upon pattern recognition receptor stimulation, RNF186 promotes ubiquitination of signaling molecules to enable optimal antimicrobial responses, including reactive oxygen species production and intracellular bacterial clearance 3. IBD-risk variants demonstrate loss-of-function in these immune pathways 3. Beyond intestinal immunity, RNF186 regulates metabolic processes including hepatic lipophagy by ubiquitinating cytoplasmic HMGB1, leading to its proteasomal degradation 1. It also controls nutrient sensing through sestrin-2 ubiquitination, modulating mTORC1 activity 4. In cancer, RNF186 exhibits context-dependent roles: functioning as a tumor suppressor in breast cancer while promoting progression in endometrial carcinoma through proteasome and PI3K-AKT pathway regulation 5. Its E3 ligase activity is essential for these diverse biological functions, making RNF186 dysfunction relevant to inflammatory bowel disease, metabolic disorders, and malignancy 6.