色素上皮衍生因子对人HepG2肝细胞脂代谢的影响

Effects of pigment epithelium-derived factor on lipid metabolism in HepG2 hepatocytes

目的:探讨色素上皮衍生因子(Pigment epithelium-derived factor,PEDF)对人HepG2肝细胞脂代谢的影响。方法:分别用重组人PEDF细胞因子和PEDF抗体干预HepG2肝细胞,采用实时荧光定量PCR和Western blot方法检测脂质合成和分解的关键酶mRNA及蛋白水平的变化;裂解细胞后用酶法测定细胞内甘油三酯(Triglyceride,TG)含量。结果:(1)PEDF干预人HepG2肝细胞后,固醇调节元件结合蛋白1(Sterol regulatory element-binding protein1,SREBP1)、脂肪酸合成酶(Fatty acid syn-thase,FAS)、乙酰辅酶A羧化酶1(Acetyl coenzyme A carboxylase1,ACC1)、羟甲基戊二酰辅酶还原酶(HMG-coA reductases,HMGR)mRNA的表达较正常对照分别降低39%、38%、61%、32%(P<0.05),而脂肪甘油三酯脂酶(Adipose triglyceride lipase,ATGL)的表达增加了98%(P<0.05);用PEDF抗体干预后,SREBP1、FAS、ACC1、HMGR mRNA的表达分别较正常对照增加92%、56%、67%、42%(P<0.05),ATGL的表达则减少了51%(P<0.05)。(2)在蛋白水平,PEDF干预后FAS、ACC1、HMGR表达较正常组分别减少58%、54%、43%,而ATGL的表达增加20%(P<0.05);用PEDF抗体干预后,FAS、ACC1、HMGR表达较正常组分别增加41%、39%、48%,而ATGL的表达减少40%(P<0.05)。(3)PEDF的干预使细胞内TG明显减少([410.40±13.43)mg/g vs.(234.70±35.70)mg/g,P<0.05],而PEDF抗体干预后,细胞内TG含量有上升趋势,但无统计学差异([410.40±13.43)mg/g vs.(440.32±25.67)mg/g,P=0.67]。结论:PEDF在HepG2肝细胞中可抑制脂肪酸的合成,并促进脂肪分解,从而降低细胞内TG的含量。

Objective：To investigate the effects of pigment epithelium-derived factor（PEDF） on lipid metabolism in HepG2 hepatocytes.Methods：HepG2 hepatocytes were treated with recombinant human PEDF or PEDF antibody.The key enzymes of lipid metabolism were detected by real time quantitative PCR and Western blot;intracellular triglyceride（TG） content was determined by enzymatic method.Results：（1）PEDF decreased the mRNA levels of sterol regulatory element-binding protein1（SREBP1）,fatty acid synthase（FAS）,acetyl coenzyme A carboxylase1（ACC1） and HMG-coA reductases（HMGR） by 39%,38%,61%,32% respectively（P〈0.05）,while increased the mRNA level of adipose triglyceride lipase（ATGL） by 98%（P〈0.05）.On the contrary,PEDF antibody increased the mRNA levels of SREBP1,FAS,ACC1,HMGR by 92%,56%,67%,42% respectively（P〈0.05）,and decreased the mRNA level of ATGL by 51%（P〈0.05）.（2）Besides,PEDF decreased the protein levels of FAS,ACC1,HMGR by 58%,54%,43% respectively（P〈0.05）,and increased the protein level of ATGL by 20%（P〈0.05）.While PEDF antibody increased the protein levels of FAS,ACC1,HMGR expression by 41%,39%,48% respectively（P〈0.05）,and decreased the protein level of ATGL by 40%（P〈0.05）.（3）PEDF significantly reduced intracellular TG content[（410.40±13.43） mg/g vs.（234.70±35.70） mg/g,P〈0.05],but PEDF antibody treated group showed an increase tendency of TG content,however without significant difference[（410.40±13.43） mg/g vs.（440.32±25.67） mg/g,P=0.67].Conclusion：In HepG2 hepatocytes,PEDF reduced the intracellular TG content by inhibiting fatty acid synthesis,and promoting lipolysis.