中文摘要：

目的观察脂肪酸转位酶FAT/CD36在棕榈酸诱导的HepG2细胞内脂质积聚中的作用,并探讨其分子机制。方法 HepG2细胞分对照组和棕榈酸组,用Western blot、双荧光素酶报告基因、荧光定量PCR、多聚核糖体分析检测棕榈酸对CD36表达、启动子活性和蛋白翻译效率的影响;油红O染色和FFA定量测定反映细胞内脂质含量;荧光显微镜实时观察细胞对FFA的动态摄入。然后将小干扰RNA转染到HepG2细胞,构建低表达CD36的HepG2细胞和阴性对照HepG2。用油红O染色,FFA定量和荧光显微镜观测棕榈酸负荷的转染细胞内脂质积聚和FFA摄取。结果棕榈酸能促进HepG2细胞CD36的表达,增强其启动子活性,增加蛋白翻译效率;棕榈酸组细胞内脂滴增多,FFA含量（240.17±19.83）ng/mg明显高于对照组（144.60±53.52）ng/mg（P〈0.05）,脂肪酸摄取速度也明显快于对照组;低表达CD36的HepG2细胞中CD36的mRNA和蛋白含量仅为阴性对照细胞的58%和50%。低表达CD36的HepG2细胞内脂滴明显少于阴性对照,FFA水平（98.38±14.18）ng/mg较阴性对照组（240.17±21.12）ng/mg明显减低（P〈0.05）,细胞对FFA的摄取也减慢。结论棕榈酸在转录和翻译水平促进HepG2的CD36表达,导致细胞内脂质积聚。

英文摘要：

Objective To investigate the role of fatty acid translocase FAT/CD36 in the palmitateinduced intracellular lipid accumulation in HepG2 cells and explore the underlying mechanism. Methods HepG2 cells were treated with 0,0. 08,0. 16 and 0. 32 mmol / L palmitate. Western blotting,dual-luciferase assay,real-time PCR and polysome ribosome analysis were performed to detect the CD36 expression,promoter activity and protein transcriptional efficiency. Oil Red O staining and free fatty acids quantitative measurements were used to examine the intracellular lipid contents. The rate of fluorescent-labeled fatty acid uptake was measured under a fluorescent microscope. The effects of inhibited CD36 expression by RNA interference in HepG2 on intracellular lipid accumulation and fatty acid uptake under palmitate condition were also studied.Results Palmitate promoted CD36 expression in HepG2 cells,accompanied by an increase of CD36 promoter activity and the protein translation efficiency. In palmitate-treated cells,more lipid droplets were observed,and FFA contents were significantly higher than control group（ 240. 17 ± 19. 83 vs 144. 60 ± 53. 52 ng / mg,P〈0. 05）. Palmitate treatment also resulted in the rate of fatty acid uptake. In addition,the mRNA and protein levels of CD36 in the cells after CD36-siRNA transfection were only 58% and 50% of the cells transfected with NC-siRNA. In response to palmitate loading,CD36-siRNA-HepG2 showed less lipid droplets accumulation,and lower FFA contents compared with the NC-siRNA transfected HepG2 cells（ 98. 38 ± 14. 18 vs 240. 17 ±21. 12 ng / mg,P〈0. 05）. The rate of fatty acid uptake was also slower in CD36-siRNA-HepG2 than in NC cells. Conclusion Palmitate promotes the expression of CD36 at transcriptional and translational levels,resulting in excess intracellular lipid accumulation in HepG2 cells.