RNF144B deficiency aggravated neuroinflammatory response induced by cerebral ischemic stroke via regulating TRAF3 ubiquitination.

Stroke, as a predominant cerebrovascular event, is characterized by disproportionately high morbidity, disability, and mortality rates. The central role of neuroinflammation in its pathophysiology underscores the clinical significance of modulating related regulatory pathways. Notably, ring finger protein 144B (RNF144B), an E3 ubiquitin ligase with demonstrated anti-inflammatory properties, presents a potential novel therapeutic target. Herein, we aimed to rigorously investigate RNF144B's involvement in stroke pathogenesis and delineate its mechanistic underpinnings. RNF144B knockout (KO) and wild-type (WT) C57BL/6 male mice were subjected to middle cerebral artery occlusion (MCAO) to mimic ischemic stroke. Co-immunoprecipitation, immunofluorescent staining, western blot, RT-PCR were used to investigate the function and mechanism of RNF144B during MCAO. RNF144B expression was significantly upregulated following cerebral ischemic stroke. The absence of RNF144B promotes microglial activation and polarization, exacerbating neuroinflammatory responses. Mechanistically, RNF144B interacts with and promotes the K48-linked ubiquitination of Tumor necrosis factor receptor (TNFR)-associated factor 3 (TRAF3), leading to its proteasomal degradation. The absence of RNF144B stabilizes TRAF3, thereby enhancing the activation of NF-κB and MAPK signaling pathways. Importantly, TRAF3 knockdown in RNF144B-deficient mice partially reversed the detrimental effects on neurological function, microglial activity, and neuroinflammation post-MCAO. The absence of RNF144B exacerbates stroke-induced neuroinflammation through TRAF3 stabilization, revealing this E3 ubiquitin ligase as a potential therapeutic target for cerebral ischemia.