RNA N6-methyladenosine Methyltransferase METTL3 Promotes Ucerative Colitis Progression Through Regulating MMP12

Objective:Ulcerative colitis is a non-specific intestinal inflammatory disease characterized by continuous and diffuse inflammation of colorectal mucosa induced by various factors.The occurrence and progression of ulcerative colitis are closely related to epigenetic modification,and the mechanism of DNA methylation and histone modification is widely studied.However,the relationship between N6-adenylate methylation（N6-methyladenosine,m6A）at the RNA transcription level and the pathogenesis of ulcerative colitis remains unclear.This study focuses on the role and molecular mechanism of m6A methyltransferase METTL3 mediated modification of m6A in ulcerative colitisMethods:Acute ulcerative colitis model was constructed in mice with intestinal conditional knockout of Mettl3 gene(Mettl3^fl/+c KO),and the effect of intestinal specific knockout of Mettl3 on the clinical symptoms and pathological features of ulcerative colitis was analyzed.Mouse colorectal mucosal tissue was analyzed by microarray gene expression profile to find downstream target genes regulated by Mettl3 in ulcerative colitis.METTL3 was overexpressed and knocked down in human colon epithelial cells NCM460.The expression of METTL3 downstream target molecule MMP12 was detected by q RT-PCR and ELISA.Mettl3 was overexpressed and knocked down in mouse macrophages RAW264.7.The expression of Mmp12,a downstream target molecule of Mettl3,was verified by q RT-PCR and ELISA.The m6A modification of Mmp12mRNA was further detected by RIP-q PCR.Results:In ulcerative colitis model mice induced by DSS,and first found that the intestinal conditional knockout of Mettl3 gene alleviated the clinical symptoms and inflammatory response of ulcerative colitis mice.Second,intestinal conditional knockout of Mettl3 gene inhibited the expression of pro-inflammatory factor Mmp12 in ulcerative colitis mice by reducing macrophage infiltration.Further mechanism studies showed that METTL3 had no regulatory effect on the expression of MMP12 in intestinal epithelial cells,but was regulating the expression of Mmp12 in activated macrophages.In addition,Mettl3 positively regulates the expression of Mmp12mRNA in activated macrophages by m6A modification.Conclusion:Intestinal conditional knockout of Mettl3 gene alleviated the progression of ulcerative colitis in mice and suppressed the expression of the proinflammatory factor Mmp12,which was associated with the regulation of Mmp12 mRNA expression by Mettl3 on m6A modification in activated macrophages.