WTAP promotes the progression of ulcerative colitis by silencing the expression of CES2 through m6A modification

Objective

This study will explore the function of WTAP, the critical segment of m⁶A methyltransferase complex, in UC and its regulation on immune response.

Methods

The expression levels of key proteins were detected in colon tissues which were derived from UC patients and mice. Macrophage polarization and CD4⁺ T cell infiltration were detected by flow cytometry and IF staining. ELISA assay was utilized to analyze the level of the inflammatory cytokines. m⁶A-RIP-PCR, actinomycin D test, and RIP assays were utilized to detect the m⁶A level, stability, and bound proteins of CES2 mRNA. A dual luciferase reporter assay was conducted to confirm the transcriptional interactions between genes. A co-culture system of intestinal epithelium-like organs was constructed to detect the primary mouse intestinal epithelial cells (PMIEC) differentiation. The interaction between proteins was detected via Co-IP assay.

Results

The expression of WTAP and CES2 in UC tissues was increased and decreased, respectively. Knockdown of WTAP inhibited the progression of UC in mice by inhibiting M1 macrophage polarization and CD4⁺ T cell infiltration. WTAP combined YTHDF2 to promote the m⁶A modification of CES2 mRNA and inhibited its expression. CES2 co-expressed with EPHX2 and overexpression of CES2 promoted the differentiation of PMIEC. The inhibitory effect of WTAP knockdown on the progress of UC was partially abrogated by CES2 knockdown.

Conclusion

WTAP/YTHDF2 silences CES2 by promoting its m⁶A modification and then promotes the progression of UC. WTAP could be a promoting therapy target of UC.