The Integrated Profiling Analysis Of Whole Genome Methylation And Gene Expression Between HepG₂ And HL-7702 Normal Liver Cells

DNA methylation is one of the earliest discovered and more common epigenetic phenomenon, it refers that under the DNA methyltransferase (DNMTs) help, the S-adenosyl methionine (SAM) was added to the DNA molecule nucleotide as a methyl donor. DNA methylation usually occurs on the fifth carbon atoms of DNA cytosine, whereby the cytosine is modified to 5-methylcytosine (5mC) DNA methylation-dependent gene control pathways as being particularly important for disease research. Getting the methylation level of all C site in whole genome is significant for the specificity of time and space of epigenetics research. In this study, we tried to understand the regulatory mechanism of methylation and mRNA in tumor development comprehensively. Therefore, next-generation high-throughput sequencing technology was used the to anlyze whole genome methylation, mRNA expression profiles of HepG2 cell line and HL-7702 cell line, and integrated analysis was did. The research has completed the following contents:1.In this study, we analyzed the differentially expressed mRNA of HepG2 cells and HL-7702 cell line. Firstly, we picked out differently expressed mRNAs with |log2(fold-change|>=1.0, FDR<0.01. Then we used DAVID to do functional annotation and KEGG pathway analysis. In the diff-expression data analysis, we found servial genes related to the cell cycle, cell division, MAPK and JUN pathway. In up-regulation genes, we found 2 genes related to cell apoptosis, death: hsa04110:Cell cycle, hsa04115:p53 signaling pathway. In the down-regulations genes, we found servial genes related to cell apoptosis, cell cycle and transcription, and the KEGG analysis revealed that 3 genes genes related to cell apoptosis, death: hsa04210:Apoptosis、hsa04310:Wnt signaling pathway、hsa04115:p53 signaling pathway.2. In this study, we analyzed the methylation level of HepG2 cells and HL-7702 cell line, including sample preparation, next genaration sequencing, quality assessment, differential expression analysis, functional annotation and mRNAexpression methylation integrated analysis. First of all, we compared three the methylation level of HepG2 cells and HL-7702 cell line and found that that cytosine methylation was mainly in the unannotation region, while the annotated cytosine methylation was mainly in the CpG island. And the methylation annotation revealed that the most CpG island was located in extron, intron and promoter. Then we integrated analyzed the different mRNA and methylation in promoter region, we found 174 Up-regulation genes and 409 Down-regulation genes. Furthermore, the GO and KEGG analisis showed that the most genes are not related to cell apoptosis, death.