ABSTRACT
Objective To investigate the effects of the polymorphisms in the promoter of ATP binding cassette transporter (ABCG1) on the transcription activity,and the relationship of the polymorphisms with the susceptibility to coronary artery disease (CAD).Methods A case-control study was conducted,217 CADpatients and 142 controls were enrolled in this study.Thesingle nucleotide polymorphisms (SNPs) in the promoter of ABCG1 were identified by sequencing.The promoter haplotypes of ABCG1 were determined with allele specific primer sequencing or Gene cloning sequencing.The transcription activity of the promoter haplotypes were evaluated with dual luciferase reporter system.The frequency of SNPs and haplotypes were analyzed between CAD group and the control group,premature CAD and non-premature CAD group,as well as multivessel lesion and single vessel lesion group.The frequency distribution was compared between two groups with x2 test or Fisher exact test.The difference of the luciferase activity was compared between groups by t-test or one-way analysis of variance.Results Only 3 SNPs were found in ABCG1 promoter sequence of about 1 000 bp upstream of the transcription start site,which are-384 (A/G),-204 (A/C) and-134 (T/G),respectively.The 3 SNPs are in strong linkage disequilibrium,Tajima's D =2.655 (P ＜ 0.01),which constituted 3 haplotypes.There was no significant difference in SNPs and haplotype frequency between the CAD group and the normal control group,and the severity of vascular disease and the early onset of coronary heart disease were not associated with the polymorphisms in ABCG1 promoter.There was no significant difference in the transcriptional activity of the three constitutive promoter haplotypes,but the transcriptional activity was notably elevated as the GAT haplotype was mutated into GAG (P ＜ 0.05).Conclusions The 3 SNPs identified in ABCG1 promoter region A did not alter the promoter activity.There was no significant correlation between the frequency distribution of SNPs and promoter haplotypes and the susceptibility to CAD.
ABSTRACT
Objective: To investigate the regulatory effects of two kinds of SV40 poly(A) signals on the upstream gene expression in three cell lines, so as to provide theoretical evidence for selection of poly(A) of vectors. Methods: A dual luciferase reporter vector Dual-Luc was constructed, and two SV40 poly(A) signal sequences were inserted in the downstream of the R-Luc gene separately. Then the two diverse dual luciferase reporter gene vectors Dual-Luc2 and Dual-Luc3 were transfected into 293, L-02, and HeLa cells. The relative quantities of the target gene (F-Luc) to control gene (R-Luc) were measured by Dual-Glo™ Luciferase Assay System and Reverse Transcription-Polymerase Chain Reaction (RT-PCR). Results: The two Dual-Luciferase vectors (Dual-Luc2 and Dual-Luc3) were successfully constructed. Dual-Glo™ Luciferase Assay showed that the mean F-Luc/R-Luc values were 3.25±0.43 and 3.03±0.14 in Dual-Luc2 and Dual-Luc3 transfected 293 cells(P>0.05), 6.16±0.39 and 3.83±0.39 in L-02 cells(P<0.05), and 1.21±0.10 and 0.66±0.02 in HeLa cells(P<0.05), respectively. The results of RT-PCR were consistent with those of luciferase assay. Conclusion: The two kinds of SV40 poly(A) signals have different regulatory effects on the upstream gene expression in different cell lines. SV40 poly(A) signals regulate the upstream gene expression at the transcriptional stage.
ABSTRACT
Objective:To observe the influence of ginsenoside Rg1 on transcriptional activation of NF-κB induced by hydrogen peroxide (H_2O_2) in 293T cell,and probe into the antioxidant mechanism of ginsenoside Rg1.Methods:In the experiment,cells was exposed to H_2O_2 after pretreatment with Rg1,cell proliferation and cytotoxicity studies were detected by MTT and Trypan blue.The quantities of generation of intracellular reactive oxygen species (iROS) was analyzed by flow cytometric analysis measured with fluorescent probe 2,7-dichlorofluorescin diacetate (DCFH-DA).NF-κB-responsive element-luciferase reporter gene was transfected and dual-luciferase cis-reporting systems were used to assay the transcriptional activity of NF-κB under the stimulated circumstance of oxidative stress induced by H_2O_2.Results:The results of MTT showed that ginsenoside Rg1 apparently protected the proliferation of 293T cell,which were repressed by H_2O_2 (P＜0.05).The results by trypan blue showed that H_2O_2 stimulated substantial cytotoxicity.This effect was markedly attenuated by treatment with ginsenoside Rg1.Oxidant production,measured as the fluorescence of dichlorofluorescein,was significant increased by 40%-50% through H_2O_2 stimulation.The decrease in iROS generation was significant blocked by 35%-40% through Rg1 and antioxidant.The relative luciferase reporter assay of NF-κB was apparently improved by H_2O_2-induced(P＜0.05),but Ginsenoside Rg1 significantly repressed the relative value of luciferase (P＜0.05).Conclusion:Ginsenoside Rg1 has the obvious protective function from the damage of oxidative stress damage,whose possible mechanism is to eliminate excessive free radicals of the cells effectively,to reduce transcriptional activation of nuclear factor kappa B(NF-κB),and subsequently to suppress the NF-κB circuit activation.