PCSK9/LDLR通路介导姜黄素烟酸酯促进HepG2摄取脂质

PCSK9/LDLR Pathway Mediates Curcumin Trinicotinate Promoting Lipid Uptake of HepG2

为研究PCSK9/LDLR通路介导姜黄素烟酸酯(CurTn)降低血浆低密度脂蛋白胆固醇(LDL-C),减少动脉内膜下脂质沉积的分子机制,用5、10、15μmo/L姜黄素烟酸酯与25 mg/L LDL共孵育Hep G2细胞24 h,分别采用油红O染色、胆固醇荧光定量试剂盒、Di I-LDL摄取检测细胞内胆固醇含量及LDL摄取情况,用逆转录定量聚合酶链反应(RT-Q-PCR)检测LDLR及SREBP2的m RNA表达,蛋白质印迹检测LDLR、SREBP2及PCSK9蛋白表达.随姜黄素烟酸酯作用浓度的增高细胞内脂滴显著增多,细胞内游离胆固醇(FC)、总胆固醇(TC)含量增高,细胞内胆固醇摄取增多;RT-Q-PCR和蛋白质印迹检测发现,与对照组(Control)比较,5、10、15μmo/L姜黄素烟酸酯处理组LDLR蛋白表达增高,SREBP2 mRNA表达水平升高,PCSK9蛋白表达降低,但对LDLR mRNA及SREBP2蛋白表达无影响.结果表明:姜黄素烟酸酯通过降低PCSK9、减少LDLR降解、升高LDLR蛋白表达,促进HepG2细胞胆摄取胆固醇.初步说明CurTn可能通过抑制PCSK9介导LDLR溶酶体降解,促进肝脏清除血浆LDL-C水平.

Low-density lipoprotein cholesterol （LDL-C） is a major risk factor for the atherosclerotic cardiovascular disease （ASCVD）. Over 70% of circulating LDL-C is metabolized by binding hepatic LDL receptor （LDLR）. Therefore, elevation of LDLR expression would reduce the progression of ASVCD. In order to study the molecular mechanism of Curcumin Nieotinate （CurTn） reducing lipid deposition of arterial intima by lowering plasma LDL-C, HepG2 cells were treated with 5, 10, 15 μmol/L CurTn co-incubated with 25 mg/L LDL for 24 h. Cellular lipid was detected by oil red O staining. Cholesterol content was detected by cholesterol quantitative fluorometric kit. LDL uptake was visualized by DiI-LDL and Hoechst33342. The mRNA expression of LDLR and SREBP2 was analyzed by quantitative Real-time PCR （RT-Q-PCR） and protein expression of LDLR, SREBP2 and PCSK9 by Western blotting. Oil Red O staining showed that lipid droplets increased significantly in 10, 15 μmol/L CurTn groups. The content of Cholesterol and DiI-LDL uptake were higher in 10, 15μmol/L CurTn groups than in control group. RT-Q-PCR and Western blotting showed that CurTn increased LDLR protein expression and decreased PCSK9 protein expression, although CurTn also increased SREBP2 mRNA expression. CurTn had no effect on LDLR mRNA expression in HepG2 cells. These results suggest that PCSK9/LDLR pathway may play a key role in lowering serum LDL-C and attenuating ASCVD risk by CurTn.