Targeting the RNF31-TFEB-NLRP3 Axis With a Curcumin Analog to Restore Autophagy and Alleviate Intestinal Inflammation.

Inflammatory bowel disease (IBD) is characterized by impaired autophagy and chronic inflammation. Although the E3 ubiquitin ligase RNF31 is upregulated in IBD, its pathogenic mechanisms remain incompletely understood. To address this, a combination of in vitro and in vivo methods was employed. In vitro, lipopolysaccharide (LPS)-stimulated cell models were used to analyze transcription factor EB (TFEB) phosphorylation, its interaction with RNF31, ubiquitination, and subcellular localization. In vivo, a DSS-induced IBD mouse model was used to assess intestinal pathology, inflammation, and RNF31-TFEB-NLRP3 axis proteins after treatment with a novel synthetic curcumin analog (CM-C1). We identified TFEB as a novel substrate of RNF31. LPS-induced phosphorylation of TFEB promoted its binding to RNF31 (via TFEB-S281/T276 and RNF31-K908), leading to TFEB ubiquitination, proteasomal degradation, suppressed autophagy, and subsequent NLRP3 inflammasome activation. The bioavailable TFEB activator CM-C1 directly disrupted the RNF31-TFEB interaction. This action promoted TFEB nuclear translocation, restored autophagic flux, alleviated intestinal inflammation in vitro and in vivo, and beneficially remodeled the gut microbiota. Our study unveils the RNF31-TFEB-NLRP3 axis as a pivotal pathogenic pathway in IBD and nominates CM-C1, which targets this axis, as a promising multimodal therapeutic candidate.