Hsa_circ_0001021 regulates intestinal epithelial barrier function via sponging miR-224-5p in ulcerative colitis.

Few circRNAs have been thoroughly explored in ulcerative colitis (UC). Microarrays and qualitative real-time PCRs were used to detect and confirm dysregulated circRNAs associated with UC. Functional analysis was performed to explore the roles. A total of 580 circRNAs and 87 miRNAs were simultaneously dysregulated in both inflamed and noninflamed UC colonic mucosa compared with healthy controls. Accordingly, hsa_circ_0001021 was significantly downregulated in patients with UC and was related to Mayo scores. Clinical samples and cell experiments revealed that hsa_circ_0001021 was expressed in epithelial cells and correlated with ZO-1, occludin and CLDN-2. Moreover, hsa_circ_0001021 sponged miR-224-5p to upregulate smad4 and increased ZO-1 and occludin. Hsa_circ_0001021 is related to UC severity and regulates epithelial barrier function via sponging miR-224-5p.