Epigenetic Modifications of PI6 during Cellular Senescence / 环境与健康杂志

ABSTRACT

Objective To understand the epigenetic regulations of P16 during cellular replicative senescence and premature senescence induced by hydrogen peroxide of human embryonic lung fibroblasts(HEFs).Methods The normal HEFs were divided into young cells(22 PDL),mid-aged cells(35 PDL)and replicative senescent cells(49 PDL)during replicative senescence.The synchronously cultured 22 PDL HEFs were exposed for 2 h to 400?mol/L H_2O_2 at half confluence on daily basis.The procedure lasted for 4 consecutive days.And then the treated cells were cultured for another 7 days,called premature senescent cells.The mRNA level of P16 was detected by fluorescence quantitative PCR.The methylation level in the promoter region -846～-639 bp was observed by methylation-specific PCR(MSP).The histone modifications was detected by chromatin immunoprecipitation-QPCR assay,including acetylation for H3,H4 and methylation for H3(Lys4)and H4(Lys20).Results In the process of cellular senescence,the mRNA level of P16 decreased in mid-aged cells,but increased significantly in both replicative and premature senescent cells compared with that of young cells(P