[Effects of pargyline on histone methylation in promoter and enhancer regions and transcription of CYP3A4/3A7].
This study was designed to investigate effects of pargyline on histone methylation in the promoter and enhancer regions and transcription of cytochrome P450 3A4/3A7 (CYP3A4/3A7) gene. Human primary fetal liver cells were isolated, cultured and randomly divided into several groups including control, solvent, pargyline low, middle, high dose (treated with 0.6, 1.2, 2.4 mmol·L(−1)). HepG2 cells were cultured and treated with 0.03, 0.3, 3 mmol·L(−1) pargyline. After 48 hours, total RNAs were prepared from the cells to determine the expression of CYP3A m RNA in primary fetal cells and HepG2 cells with real-time quantative PCR (qPCR). HepG2 cells were cultured and then treated with 3 mmol·L(−1) pargyline for 48 hours. The chromatin immunoprecipitation (ChIP) assay was performed with dimethylation of histone H3 at lysine 4 (H3K4me2), and IgG antibodies respectively. The precipitated DNA was resuspended and used for qPCR. Primers were used to detect different regions of CYP3A4/3A7 promoter and enhancer. Occupancy of H3K4me2 was shown as percent of input DNA relative to control cells. The results suggested that pargyline has an effect on primary fetal liver cells and HepG2 cells proliferation. The level of CYP3A7 was markedly enhanced in human primary fetal liver cells by treatment with 1.2, 2.4 mmol·L(−1) of pargyline (P < 0.05, P < 0.01) and the levels of CYP3A4/3A7 were remarkably enhanced by treatment with 3 mmol·L(−1) of pargyline in HepG2 cells (P < 0.001) compared with solvent control. Occupancy of H3K4me2 on human CYP3A4 promoter (−362 to +53) and enhancer segment (−7 836 to −6 093) harbored the overlapping hepatocyte nuclear factors 4A (HNF4A) binding site compared with a negative control. Occupancy of H3K4me2 on human CYP3A7 promoter (−163 to +103) and enhancer segment (−4 054 to −3 421, −6 265 to −6 247) overlapped with glucocorticoid receptor (GR) binding site. In conclusion, the enriched H3K4me2 in the promoter and enhancer regions was induced by pargyline with HNF4A or GR binding site in CYP3A4/3A7 gene to activate the corresponding genes.