MiR-29a inhibited intestinal epithelial cells autophagy partly by decreasing ATG9A in ulcerative colitis

Ulcerative colitis (UC), with high morbidity has become one of the fastest-growing severe illnesses in the world. Although MiR-29a is highly expressed in the tissues of UC patients, the mechanism of miR-29a involved in the specific pathogenesis of UC is not known. In this study, a GFP-light chain 3 (LC3) immunofluorescence assay was used to observe the formation of the autophagic spot; qRT-PCR and western blotting analyses were carried out to detect the expression of autophagy-related proteins, including BECN1, Autophagy-related gene (ATG)5, ATG16L, and transcription factor EB. The dual-fluorescence reporter assay was used to analyze the direct effect of miR-29a on ATG9A; experimental dextran sulfate sodium-induced colitis in mice was used to establish the UC model. Our studies showed that the overexpression of miR-29a not only suppressed the production of GFP-LC3 autophagy spots but also inhibited the level of LC3II/LC3I and upregulated the expression of P62 in HT29 and HCT116 cells. Moreover, the results showed that miR-29a directly targeted the 3′UTR region of ATG9A mRNA to suppress the activation of HT29 and HCT116 cells' autophagy. Also, overexpression of ATG9A rescued rapamycin-induced autophagy that was inhibited by overexpression of miR-29a. In addition, miR-29a also affected the expression of autophagy-related proteins (BECN1, ATG5, ATG16L1, and transcription factor EB). Notably, miR-29a was upregulated, whereas ATG9A was downregulated in the experimental dextran sulfate sodium-induced colitis in mice. In effect, this study showed that miR-29a inhibits rapamycin-induced intestinal epithelial cells' autophagy partly by decreasing ATG9A in UC. These findings may provide new insights that may help control the inflammation in UC. Correspondence to Miao Ouyang, MD, Gastroenterology Department, Xiangya Hospital, Central South University, No. 87 Xiangya Road, Changsha 410008, People's Republic of China Tel: +86 073 189 753 999; fax: +86 13 907 482 825; e-mail: ouyangmiao1115@163.com Received November 17, 2017 Accepted March 28, 2018 Copyright © 2018 Wolters Kluwer Health, Inc. All rights reserved.

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