Histone 3 Lysine 27 Acetylation Profiling Reveals Its Role In The Chronic DSS-induced Colitis Mousemodel

Objective This project intends to use the transcriptome and epigenetic omics research methods to explore the alteration of H3 protein lysine residues 27 acetylation(H3K27ac)in chronic DSS(dextran sodium sulfate)induced colitis than the control group in the intestinal tissue,in order to make clear whether to participate in IBD(Inflammatory bowel diseases),and at the same time identify candidate genes with abnormal gene expression and possible transcription factor regulation network and enhancer so on causing by H3K27 ac changes.The possible regulatory mechanism of transcription factor binding epigenetic modification was further verified.Methods Here,we established the dextran sulfate sodium(DSS)-induced chronic colitis and performed RNA-sequencing(RNA-seq)and Chromatin Immunoprecipitation followed by NGS sequencing(Ch IP-seq)for H3K27 ac in the mice colon tissues to investigate whether the H3K27 ac is involved in the development of intestinal inflammation.Bioinformatics GO and KEGG methods were used to analyze the data.After the identification of transcription factors,real-time fluorescence quantitative assay(RT-PCR)and Western blotting were used to confirm their expression,and protein co-precipitation(COIP)was further used to confirm their interaction with H3K27 ac modifying enzyme.Results We found that the global H3K27 ac level and distribution in colon tissue had no significant difference after DSS treatment,while H3K27 ac signals were significantly enriched on the typical-enhancers specific in the DSS group compared with the control.By combining with RNA-seq data(fold change>2),we identified 89 candidate genes for further exploration,which represented the susceptible genes to H3K27 ac change upon the DSS treatment.Since changes in H3K27 ac levels alters the transcription factor occupancy,dynamic enhancer activity can thus serve as a tool to identify shifts in transcription factors(TFs)regulatory networks induced by DSS treatment.As such,we further predicted TFs involved in DSS-induced colitis.Among them,we found that upregulated activated STAT1 in enteritis may promote the expression of target genes IFITM1,CXCL10 and GPX3 in intestinal epithelial cells by binding EP300 to promote H3K27 ac enrichment on the upstream typical enhancer sequence of the target genes.Its effects on inflammation and proliferation of intestinal epithelial needs further study.Conclusion H3K27 ac increase on special typical-enhancers in the DSS group is possibly related with the development of intestinal inflammation by up-regulating adjacent gene expression and shifting TFs networks.Among them,up-regulated PSTAT1 is most likely to promote target genes expression through synergistic promotion of H3K27 ac signal in the upstream typical enhancer region of the target genes by binding EP300,thus participating in the initiation and development of enteritis which will provide new insight into the pathogenesis and therapy in the IBD.