内脂素通过过氧化物酶体增殖物激活受体γ信号转导通路下调ATP结合盒转运蛋白A1的表达

Study on down-regulation of the expression of ATP binding cassette transporters A1 induced by visfatin via PPARγ signal transduction pathway

目的:观察过氧化物酶体增殖物激活受体γ(PPARγ)信号通路在内脂素(visfatin)调控人单核细胞株(THP-1)源性巨噬细胞ATP结合盒转运蛋白A1(ABCA1)表达中的作用,探讨visfatin诱导泡沫细胞形成的机制和途径。方法:THP-1单核细胞诱导分化为巨噬细胞,随机分组,给予不同浓度的visfatin和PPARγ激动剂罗格列酮进行干预,分别运用油红O染色法观察细胞内脂滴形成情况,反转录聚合酶链反应(RT-PCR)法和蛋白免疫印迹(Western blot)法检测各组细胞ABCA1及PPARγmR-NA和蛋白表达,酶荧光学法检测细胞内总胆固醇(TC)和游离胆固醇(FC)含量,TC与FC之差为胆固醇酯(CE)含量。结果:与对照组比较,visfatin干预组油红O染色显示细胞内脂滴形成增加,PPARγ及ABCA1 mRNA和蛋白表达水平降低(均P<0.05),细胞内FC含量升高(P<0.05);相关分析显示,visfatin呈浓度依赖性下调PPARγ及ABCA1 mRNA和蛋白的表达。与visfatin干预组比较,罗格列酮组ABCA1 mRNA和蛋白表达水平升高(均P<0.05),细胞内FC含量降低(P<0.05);相关分析显示,罗格列酮呈浓度依赖性上调ABCA1 mRNA和蛋白的表达。结论:visfatin通过PPARγ信号转导通路下调ABCA1表达,减少细胞内FC流出,从而诱导泡沫细胞形成。这可能为visfatin致动脉粥样硬化发病机制的研究提供了一个新的理论依据。

Objective：To investigate the role of Peroxisome proliferator-activated receptor Gamma（PPARγ） signal transduction pathway on the down-regulation of the expression of ATP-binding cassette transporters A1（ABCA1） and to dicuss the mechanism of THP1-derived foam cell formation induced by visfatin.Methods：THP-1 monocytes were induced into macrophages by 160 nmol/L phorbol myristate acetate（PMA） for 48 h,then the macrophages were exposed to visfatin and PPARγ activator（Rosiglitazone） with different concentrations.Lipid droplets in cytoplasm were observed by Oil red O staining.The expressions of PPARγ and ABCA1 mRNA and protein were determined by reverse transcriptase polymerase chain reaction（RT-PCR） and Western blot respectively.The contents of total cholesterol（TC） and free cholesterol（FC） were detected by enzyme fluorescence analysis.The contents of cholesterol ester（CE） were calculated by the difference between TC and FC.Results：Compared with the control group,the expressions of PPARγ and ABCA1 mRNA and protein were down-regulated and the contents of FC were incresed in visfatin groups（P〈0.05）.It was in a concentration-dependent manner.Compared with the visfatin groups,the expressions of ABCA1 mRNA and protein were up-regulated and the contents of FC were decreased in Rosiglitazone groups（P〈0.05）.It was in a concentration-dependent manner.Conclusion：The down-regulation of ABCA1 expression is induced by visfatin via PPARγ signal transduction pathway,which induced foam cell formation.This may provide a new evidence for visfatin inducing atherosclerosis.