普洱茶茶色素对HepG2细胞脂质代谢的影响及作用机理

Effect and Mechanism of Pigments from Pu-erh Tea on Lipid Metabolism in HepG2 Cell Model

以正常培养和油酸诱导培养的人肝癌细胞系(human hepatocellular liver carcinoma cell line,Hep G2)细胞为模型,通过测定普洱茶茶色素对Hep G2细胞内甘油三酯(triglyceride,TG)和总胆固醇(total cholesterol,TC)含量,细胞中脂肪酸合成酶(fatty acid synthase,FAS)、固醇调节元件结合蛋白1c(sterol regulatory element binding protein 1c,SREBP-1c)、三磷酸腺苷结合转运子A1(ATP binding cassette transporter A1,ABCA1)、胆固醇7α-羟化酶(cholesterol 7α-hydroxylase,CYP7A1)的转录水平,磷酸化腺苷酸活化蛋白激酶(phospho-AMPactivated protein kinase,p-AMPK)的蛋白表达水平研究普洱茶茶色素的减肥降脂作用机制。结果显示,普洱茶茶色素能明显降低油酸诱导的Hep G2细胞模型中TG和TC含量,作用程度依赖于普洱茶的作用质量浓度。但对正常培养的Hep G2的TG、TC作用影响不显著。经过普洱茶茶色素作用油酸诱导Hep G2细胞24 h后,能显著下调细胞的FAS和SREBP-1c的m RNA表达水平(P<0.05),显著上调ABCA1的转录水平(P<0.05),且使CYP7A1的转录水平呈上升趋势,并显著上调p-AMPK蛋白的表达量(P<0.05)。因此,普洱茶茶色素可通过调控上述调控因子和酶的表达而改善油酸诱导下Hep G2细胞的脂质代谢水平。

The contents of triglyceride(TG)and total cholesterol(TG),the mRNA expression level of fatty acid synthase(FAS),sterol regulatory element binding protein1c(SREBP-1c),cholesterol7α-hydroxylase(CYP7A1)and ATP binding cassette transporter A1(ABCA1),and the protein expression level of phospho-AMP-activated protein kinase(p-AMPK)were investigated for studying the effects of pigments from Pu-erh tea on lipid metabolism in HepG2cell line cultured with normal or oleic acid enriched medium.The results showed that pigments from Pu-erh tea significantly decreased the contents of TG and TC in HepG2cells cultured in oleic acid-enriched medium in a dose-dependent manner,although having no significant effect on HepG2cells cultured in normal medium.The mRNA expression levels of FAS and SREBP-1c were significantly down-regulated,and the mRNA level of ABCA1was significantly up-regulated,the mRNA expression level of CYP7A1showed an increased tendency and the protein expression level of p-AMPK was significantly up-regulated after the treatment with pigments from Pu-erh tea for24hours in HepG2cells cultured in oleic acid-enriched medium(P<0.05).Therefore,pigments from Pu-erh tea could improve lipid metabolism in HepG2cells cultured in oleic acid-enriched medium by regulating the mRNA levels of enzymes and transcription factors.