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P057 CRL4DCAF2 promotes cell proliferation and limits the development of colitis

Wang, C.(1);Yao, L.(1);Zhang, Y.(1);Cao, Q.(1);

(1)Sir Run Run Shaw Hospital,Zhejiang University School of Medicine, Department of Gastroenterology, Hangzhou, China

Background

Ulcerative colitis (UC) is an idiopathic intestinal inflammatory disease , which leads to chronic intestinal mucosal barrier damage. More and more evidences show that ubiquitination of proteins regulates the occurrence and development of intestinal inflammation. DCAF family proteins could form E3 ubiquitin ligase with CRL4-DDB1 to regulate cell growth, differentiation, apoptosis and other life activities. CRL4DCAF2 is a crucial regulator in cell cycle regulation, but there are few studies on its application in intestinal epithelium. This study aims to explore the specific mechanism of CRL4DCAF2 in regulating the proliferation and repairment of intestinal epithelial cells.

Methods

DSS - induced colitis in mice was used as the experimental model in vivo. HCT116 and SW480 cell lines were used as experimental models in vitro studies.The Cre-loxP system was used to construct a mouse model of intestinal epithelium-specific DCAF2 knockout. The intestinal mucosa biopsy specimens of 11 normal patients and 11 UC patients were collected. In addition, qRT-PCR, Western blot, RNA-seq and immunofluorescent staining were used to detect the expression levels of target genes in human colon biopsy specimens, mouse colon tissues, HCT116 or SW480 cells

Results

DCAF2 gene was highly expressed in the colon of mice. The occurrence and development of DSS-induced experimental colitis was accompanied by a significant down-regulation of DCAF2 protein expression in colon. DCAF2 mRNA level was significantly decreased in UC patients. Mouse with intestinal epithelial-specific knockout of DCAF2(i.e. DCAF2IEC-KO) suffered from embryonic death. Compared with wild-type adult C57BL/6J mice, DCAF2IEC-KD mouse showed more severe intestinal inflammation in DSS-induced colitis model. CCK-8 test, PI staining and EDU staining flow cytometry experiments showed that the proliferation of intestinal epithelial cells with DCAF2 overexpression was faster than that of the control (P < 0.05) in HCT116 and SW480 cell lines, while in knockdown of DCAF2 models, the opposite results were obtained. Its effect may be related to the ubiquitination of p21. At the same time, MLN4924 in vivo and in vitro experiments further verified our experimental results. Combined with RNA-seq and Western blot, we also found that DCAF2 may reduce the symptoms of colitis by maintaining the stability of autophagy.

Conclusion

DCAF2 is low expressed in patients with ulcerative colitis, which may promote the activation and proliferation of intestinal epithelial cells. It could maintain autophagy stability, and restore intestinal barrier, thus alleviate the development of ulcerative colitis 

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