| Inflammatory bowel disease(IBD)is a group of chronic non-specific intestinal inflammatory diseases including ulcerative colitis(UC)and Crohn’s disease(CD).The etiology and pathophysiology of IBD are still unclear,which may be related to abnormal innate and acquired immune responses in intestinal mucosa,intestinal microbiota,injury of intestinal mucosal barrier,susceptibility genes and environmental factors.Large-scale genome-wide association study(GWAS)of IBD patients revealed nearly 200 IBD susceptible genes.Only a small number of single-Nucleotide Polymorphisms(SNP)loci located in the gene coding regions,which could directly affect the coding process.But the function of the rest SNP loci and their molecular contribution to the phenotype of disease are still unknown.In addition,infection of individuals carrying susceptible genes is considered to be the main pathogenesis of IBD.Studies on susceptibility gene loci and their interaction with environmental triggers is of great significance to understand the pathogenesis IBD and apply in disease diagnosis and treatment.Janus kinase/signal transducer and activator of transcriptions(JAK-STAT)is a common intracellular pathway of many cytokines.JAK-STAT is widely involved in the biological process including cell proliferation,differentiation,apoptosis and inflammation.IBD susceptibility genes in JAK-STAT pathway are IL23R,IL12B,JAK2,TYK2,STAT3,STAT1,STAT4,SOCS1,IL10 and STAT5.STAT5 can be activated by a variety of cytokines,growth factors and hormones,and plays a key role in the formation of intestinal barrier.In this paper,we studied on STAT5A SNP rs7220367 to identify its effect on gene expression and cell function,and the mechanism of SNP involved in IBD.Further,conditional intestinal epithelial stem cell Stat5 knockout mice used to research the effect of Stat5 on Salmonella typhimurium infection and the interaction between susceptible genes and environmental triggers.In order to explore the function of STATS A SNP rs7220367,we used CRISPR/Cas9 gene editing technology to introduce C to G mutation and construct mutant cell lines.And then we studied the effect on cell proliferation and apoptosis,cell migration,gene transcription,protein expression and epigenetic genes.The results showed that SNP rs7220367 up-regulated the expression of STAT5A and the expression of proteins in disease pathways,inhibited cell proliferation,promoted cell migration,and affected the epigenetic genes.The results suggested that STAT5A involved in the pathogenesis of IBD and might be a potential therapeutic target for IBD.In order to elucidate the role of STAT5 in intestinal inflammatory diseases induced by environmental triggers such as pathogenic microbial infection,we used tamoxifen to induce conditional knockout of Stat5 in intestinal epithelial stem cells of mice,and Salmonella typhimurium was used to induced acute infection.Injury of intestine,expression of related proteins and inflammatory factors,microflora composition of feces was studied.The results showed that StatS knockout aggravated intestinal pathological damage and intestinal flora disturbance caused by Salmonella typhimurium infection,suggesting that STAT5 plays’ an important role in maintaining intestinal epithelial homeostasis and microbial homeostasis.In summary,the study of IBD susceptible gene locus STAT5A SNP rs7220367 revealed that the disease-related SNP can significantly affected the cell function and gene expression.The results helped to elucidate the pathogenesis of IBD and provided a protocol for studying the function of other susceptible gene loci.In vivo experiments of intestinal stem cells StatS knockout mice combined with Salmonella typhimurium infection showed that STAT5 played an important role in maintaining intestinal epithelial homeostasis and microbial homeostasis.All the results suggest that STAT5 signaling pathway in intestinal cells has an important function,both overexpression and knockout involves in diseases,and also provides new sight for the treatment of IBD. |
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