O. Das, S. Acharya Chowdhury, A. Gope, A. Nanda Goswami, M. Bhaumik
Inflammatory bowel disease (IBD) often involves disrupted intestinal epithelial barrier, but therapies specifically targeting this barrier are limited. We found that downregulated AUF1 (HNRNPD) contributes to defective barrier integrity in ulcerative colitis (UC). Compared to controls, its expression level was decreased and inversely correlated with clinical severity. Knocking down AUF1 in human and mouse colonic organoids led to impaired barrier function, with reduced Occludin and upregulated Claudin-2, mimicking characteristic IBD-associated mucosal alterations. Distinct RNA-binding activity of AUF1 protein isoforms contributed to these changes: p37 stabilized Occludin mRNA and blocked microRNA-122/Ago2-mediated repression, whereas p40 promoted Claudin-2 mRNA degradation via ubiquitin-proteasome pathway. Restoring AUF1 expression in organoids enhanced epithelial properties and, when transplanted into mice with established colitis, accelerated mucosal healing and epithelial regeneration in recipient mice and decreased fibrosis. Our study unravelled a post-transcriptional mechanism important for intestinal homeostasis and demonstrated a concept of using engineered organoids for treating IBD.