YAP triggers the Wnt/?-catenin signalling pathway and promotes enterocyte self-renewal, regeneration and tumorigenesis after DSS-induced injury.

ABSTRACT: Impaired epithelial regeneration is a crucial pathophysiological feature of ulcerative colitis (UC). Yes-associated protein (YAP1) appears to control cell proliferation and differentiation. In this study, we sought to identify the roles of YAP in intestinal epithelial cell (IEC) self-renewal, regeneration and tumorigenesis. We first observed that YAP was significantly reduced in 62.5% (45/72) of human UC tissues and it was dramatically enhanced during epithelial regeneration in a murine colitis model. Using lentiviral infection, we established a YAP-overexpression (YAP^WT) mouse model. We then found that after tissue injury, YAP^WT mice had increased epithelial cell self-renewal capacity and drastically restored intestinal crypt structure. Strikingly, these mice were more susceptible to colitis-associated cancer (CAC) in chemically induced carcinoma. Mechanistically, YAP and ?-catenin showed increased nuclear co-localization during regeneration after inflammation. Overexpressing YAP significantly improved IEC 'wound-healing' ability and increased the expression of both ?-catenin and the transcriptional targets of Wnt signalling Lgr5 and cyclin D1, whereas silencing ?-catenin in YAP^WT cells attenuated this effect. Remarkably, we observed that YAP could directly interact with ?-catenin in the nucleus and formed a transcriptional YAP/?-catenin/TCF4 complex; Lgr5 and cyclin D1 were confirmed to be the target genes of this complex. In contrast, cancer cell proliferation and tumour development were suppressed by the phospho-mimetic YAP mutant. In summary, nuclear YAP-driven IEC proliferation could control epithelial regeneration after inflammation and may serve as a potential therapeutic target in UC. However, excessive YAP activation promoted CAC development.

SUBMITTER: Deng F 

PROVIDER: S-EPMC5833613 | biostudies-literature | 2018 Feb

REPOSITORIES: biostudies-literature