砷对巨噬细胞胆固醇流出及ABCA1、ABCG1、SRBI基因表达的影响

Arsenic on cholesterol efflux and the expression of ABCA1,ABCG1 and SRBI

目的分析砷对巨噬细胞胆固醇流出及腺苷三磷酸结合盒家族A亚家族成员1(ABCA1)、腺苷三磷酸结合盒转运体G1(ABCG1)和清道夫受体-BI(SRBI)基因表达的影响,为砷致动脉粥样硬化的机制研究提供依据。方法人髓系白血病单核细胞(THP-1)加入佛波酯诱导成巨噬细胞,与小鼠原代巨噬细胞用0、0.625、1.25、2.5和5μmol/L的亚砷酸钠处理48 h,采用荧光定量PCR和免疫印迹法检测ABCA1、ABCG1和SRBI基因表达水平;采用同位素示踪法检测胆固醇流出率。用含2.5μmol/L亚砷酸钠培养基处理巨噬细胞48 h,再换无砷培养基培养48 h,每隔12 h收集细胞,分析砷对ABCA1表达水平和胆固醇流出的时间效应。结果砷以剂量依赖方式抑制ABCA1、ABCG1的表达和胆固醇流出;5μmol/L砷处理组THP-1细胞和小鼠原代巨噬细胞中ABCA1 mRNA相对表达量分别下降69%和72%,ABCG1 mRNA相对表达量分别下降42%和34%,胆固醇流出率分别下降55%和59%(均P<0.05)。砷对SRBI的表达无明显影响(均P>0.05)。砷以时间依赖方式抑制THP-1细胞ABCA1表达和胆固醇流出,砷处理48 h时ABCA1 mRNA相对表达量和胆固醇流出率下降至最低,分别为0 h时的43%和42%;去除砷影响后ABCA1 mRNA相对表达量和胆固醇流出率逐渐恢复。结论砷通过下调巨噬细胞ABCA1和ABCG1的表达抑制胆固醇流出。

Objective To explore the impact of arsenic on cholesterol efflux and the expression of ATP-binding cassette,sub-family A,member 1(ABCA1),ATP-binding cassette transporter G1(ABCG1),and scavenger receptor class B member I(SRBI)in macrophages,so as to provide the evidence for the mechanism of arsenic induced atherosclerosis.Methods The human myeloid leukemia mononuclear cells(THP-1),induced by phorbol myristate acetate,and mouse primary macrophages were treated with 0,0.625,1.25,2.5 and 5μmol/L NaAsO_(2) for 48 hours.Then the cells treated with 2.5μmol/L NaAsO_(2) were changed to arsenic free mediums for 48 hours and collected every 12 hours to analyze the time effect of arsenic.The expression levels of ABCA1,ABCG1 and SRBI were determined by quantitative polymerase chain reaction and western blotting.Cholesterol efflux rates were measured by ^(3)H isotope tracer.Results Arsenic significantly down-regulated the expression levels of ABCA1 and ABCG1,and cholesterol efflux in a dose-dependent manner.The levels of ABCA1 mRNA decreased by 69%and 72%,the levels of ABCG1 mRNA decreased by 42%and 34%,and the rate of cholesterol efflux decreased by 55%and 59%in THP-1 and mouse primary macrophages cells treated with 5μmol/L NaAsO_(2)(all P<0.05).Arsenic had no significant effect on SRBI expression(all P>0.05).Arsenic inhibited ABCA1 expression and cholesterol efflux in THP-1 in a time-dependent manner.Compared with cells before the exposure of arsenic,the level of ABCA1 mRNA and the rate of cholesterol efflux in THP-1 bottomed at 48 hours by 43%and 42%,and gradually recovered when arsenic was removed.Conclusions Arsenic inhibits cholesterol efflux by down-regulating the expression of ABCA1 and ABCG1 in macrophages.