Objective: To investigate the effects of DNA hypomethylation on mRNA and protein expression of perforin promotor in T cells.
Methods: T cells were isolated from the peripheral venous blood of healthy donors by density gradient centrifugation. CD4(+) and CD8(+) subsets were isolated using Miltenyi beads and protocols provided by the manufacturer. Where indicated the T cells were stimulated with PHA for 24 h, then treated with 5-azaC for an additional 72 h. Genomic DNA, mRNA, and protein were isolated from untreated and 5-azaC-treated T cells. Purified DNA was treated with sodium bisulfite, the desired sequences were amplified in sequential fragments using nested PCR. The amplified fragments were cloned into bacteria DH5 alpha and 5 independent clones for each of the amplified fragments were sequenced. The expression of perforin was determined using real time RT-PCR and Western blot.
Results: The perforin mRNA and protein in the CD4(+) and CD8(+) subsets treated with 5-azaC were significantly higher than those in the untreated subsets (P<0.05). The results of bisulfite genomic sequencing showed that the methylation of perforin promotor was significantly reduced in the treated cells compared with the untreated cells (P<0.05).
Conclusion: The mRNA and protein expression of perforin significantly increases in the CD4(+) and CD8(+) T cells treated with 5-azaC,which is associated with DNA hypomethylation of perforin promoter in T cells.