Ulcerative colitis (UC) is a chronic colitis with unknown etiology. Circular RNA (circRNA) has shown regulatory effect in many diseases, but the role of circRNA in UC is barely known. This study uncovers the function and regulatory mechanism of circRNA HECTD1 (circHECTD1) in UC.

Colonic mucosal tissues of 60 patients with active UC and 30 healthy controls were collected for H&E staining. Lipopolysaccharide (LPS) and dextran sulfate sodium (DSS) were used to induce inflammation and UC in Caco-2 cells and C57BL/6 mice where modification of circHECTD1, miR-182–5p and/or human antigen R (HuR) took place. The Caco-2 cells and the colon tissues of DSS-treated mice were collected for analysis of the expression levels of inflammatory cytokines, NLRP3 inflammasome, and autophagy-related proteins. The interactions among circHECTD1, miR-182–5p, and HuR were verified.

The colonic mucosal tissues of UC patients showed impaired autophagy and decreased expressions of circHECTD1 and HuR. Overexpression of circHECTD1 or HuR or inhibition of miR-182–5p suppressed inflammation and promoted autophagy of LPS-induced Caco-2 cells. The expression of HuR was promoted by circHECTD1 via miR-182–5p in Caco-2 cells. Overexpression of circHECTD1 reduced colonic injuries and inflammation by promoting autophagy in DSS-treated mice.

Overexpression of circHECTD1 alleviates UC by promoting HuR-dependent autophagy via miR-182–5p. This study highlights the therapeutic potential of circHECTD1 for UC and adds to the knowledge of circRNA in the pathogenesis of UC.