ABSTRACT
Objective To investigate the effects of DNA methylation on the expression of lympho-cyte activation gene 3 (lag3) in different human T cell lines.Methods A quantitative PCR and a flow cy-tometry analysis were performed to measure the expression of lag3 gene in various T cell lines at mRNA and protein levels.The distribution of CpG sites within the promoter and body of lag3 gene was detected to locate the potential regulatory region(s) (CpG island and CpG island shore).The levels of DNA methylation in each cell line were analyzed.The T cell lines were demethylated with 5-Aza-2′-deoxycytidine (5-Aza-2′-dc) for further investigation on the changes of lag3 gene expression and DNA methylation.Results Jurkat E6-1 cells showed the highest expression level of lag3 gene as compared with J.CaM1.6 and CEM cells.Hyperm-ethylated CpG islands were detected in cells of each cell line.The methylation levels of CpG island shore in J.CaM1.6 and CEM cells were higher than that in Jurkat E6-1 cells.Treatment of J.CaM1.6 and CEM cells with 5-Aza-2′-dc significantly promoted the expression of lag3 gene at mRNA and protein levels as well as the demethylation of CpG island shore.No significant differences with the expression of lag3 gene and the methylation of CpG island were observed in Jurkat E6-1 cells with or without 5-Aza-2′-dc stimulation.Con-clusion Methylation and demethylation of CpG island shore played important roles in regulating the tran-scription of lag3 gene.