E3 Ubiquitin Ligase Ring Finger Protein 2 Alleviates Cerebral Ischemia-Reperfusion Injury by Stabilizing Mesencephalic Astrocyte-Derived Neurotrophic Factor Through Monoubiquitination.

Aim: Cerebral ischemic stroke (IS) is one of the leading causes of morbidity and mortality globally. However, the mechanisms underlying IS injury remain poorly understood. Ring finger protein 2 (RNF2), the member of the polycomb family (PcG), has been implicated in diverse biological and pathological conditions. However, whether RNF2 plays a role in IS progression is not clarified. This study aims to investigate the potential effects of RNF2 on IS.

Methods: The effects of RNF2 were studied in human postmortem IS brains, a rat model of IS, tunicamycin (TM)-induced mouse neuroblastoma neuro2a (N2a) cells, and oxygen-glucose deprivation/reperfusion (OGD/R)-induced SH-SY5Y cells.

Results: Here, we demonstrated that RNF2 was markedly upregulated both in human postmortem IS brains and ischemic rat brains and RNF2 overexpression alleviated brain injury induced by middle cerebral artery occlusion by reducing neuron apoptosis. Mechanistically, we found that RNF2 is an E3 ubiquitin ligase for the mesencephalic astrocyte-derived neurotrophic factor (MANF), which confers protection against brain ischemia. RNF2 interacted with MANF and promoted the monoubiquitination of MANF, consequently facilitating its stability and nuclear localization.

Conclusion: Collectively, RNF2 is identified as a critical inhibitor of IS injury by stabilizing MANF through monoubiquitination, suggesting that RNF2 is a potential therapeutic target for IS.