The Research Of DNA Methylation In Diabetic Nephropathy

Part 1.DNA methylation profiling of diabetic nephropathyObjectives:Diabetic nephropathy(DN)is an important cause of kidney failure.However,the pathogenesis of DN has not been fully unraveled yet.This study intends to explore the epigenetic mechanism of DN.Methodolgy:Three groups of subjects were included:patients with DN,patients with diabetes without nephropathy,normal control.Kidney tissues were collected.The difference of methylation level between three groups was analyzed using the method of whole genome bisulfite sequencing.DNA methylation profiling of diabetic nephropathy was established and the effects of differential methylation on diabetic nephropathy was investigated.Results:(1)Global DNA methylation level was significantly higher in patients with DN than in the patients with diabetes without nephropathy.(2)The number of Differentially methylated regions(DMR)between diabetic nephropathy and diabetes without nephropathy was also significantly increased.(3)Results of GO analysis and KEGG enrichment analysis of genes related with identified DMR showed that focal adhesion was significantly enriched.Methylation levels of integrin family genes of diabetic nephropathy were obviously different from the diabetes without nephropathy.(4)ACTN4 was significantly enriched in the pathway of adherens junction and DMRs in ACTN4 was identified after comparison with diabetes patients without nephropathy.Conclusion:DNA methylation profile was significantly changed in the kidneys of diabetic nephropathy.DNA methylation plays a vital role in the pathogenesis of diabetic nephropathy.Part 2.Combined analysis of DNA methylation and transcriptome profiling of diabetic nephropathyObjecives:DNA methylation and transcriptional profiling of diabetic nephropathy were combined to analyze the relationship between gene methylation and gene expression and explore the role of DNA methylation in the pathogenesis of diabetic nephropathy.Methodolgy:Based on transcriptional data of diabetic nephropathy in GEO database,bioinformatics methods were used to screen differentially expressed genes in patients with diabetic nephropathy.The correlation between differentially expressed genes(DEGs)and differentially methylated genes(DMGs)was analyzed.Using online analysis website----DAVID,GO and KEGG analysis were performed on the genes of which the level of methylation and expression was significantly different.The main biological functions and pathways these genes involved were investigated.Results:(1)Based on the transcriptional data of diabetic nephropathy in GEO(GSE30122),914 differentially expressed genes(DEGs)were screened.Compared with the normal control,634 highly expressed genes in diabetic nephropathy patients and 280 down regulated genes were found.(2)It was indicated that 206 DMRs and 153 related genes had obvious difference on the level of methylation and expression,including SYNPO,and so on.(3)90 DMR and 62 related genes had negative correlation with the expression of differentially expressed genes,which were mainly enriched in PI3K-Akt signaling pathway.Conclusion:There is a close relationship between DNA methylation and gene expression in the diabetic nephropathy.DNA methylation plays a vital role in the pathogenesis of diabetic nephropathy.