胰高血糖素样肽-通过Foxo1/3调控肝细胞脂质代谢研究

Glucagon-like peptide-1 regulates lipid metabolism in hepatocytes through Foxo1/3

目的通过观察胰高血糖素样肽-1(GLP-1)是否依赖Foxos调控肝细胞脂质代谢及相关基因的表达,探讨GLP-1治疗非酒精性脂肪性肝病(NAFLD)的分子机制。方法通过以棕榈酸/油酸刺激HepG2细胞构建NAFLD细胞模型。通过小干扰RNA(siRNA)单独敲减Foxo1、Foxo3或同时敲减Foxo1和Foxo3,观察GLP-1对HepG2细胞脂肪变性模型中甘油三酯(TG)浓度的影响。利用实时定量PCR(RT-PCR)检测同时敲减Foxo1和Foxo3后HepG2细胞中调脂基因SREBP1c和Acox2的变化。结果模型组单位蛋白TG含量明显高于对照组[(12.65±1.32)μg/mg比(4.32±0.54)μg/mg,P<0.05]。使用GLP-1处理模型组细胞,TG浓度显著低于模型组[(8.38±1.48)μg/mg比(12.65±1.32)μg/mg,P<0.05];敲减Foxo1或Foxo3后的GLP-1处理组TG浓度分别为(9.09±1.34)μg/mg和(8.90±1.60)μg/mg,依然显著低于模型组(P<0.05)。同时敲减Foxo1和Foxo3的模型组TG的浓度(14.66±1.77)μg/mg显著高于未敲除的模型组(12.65±1.32)μg/mg,同时敲减Foxo1和Foxo3的模型+GLP-1处理组TG的浓度与同时敲减Foxo1和Foxo3的模型组差异无统计学意义(P>0.05)。Foxo1/3敲减后GLP-1对SREBP1c和Acox2表达无显著影响(P>0.05)。结论GLP-1在肝细胞内可以抑制TG的合成,可能通过介导与Foxo1和Foxo3的相关通路有关,但具体作用机制还需要后续进一步研究。

Objective Glucagon-like peptide-1 (GLP-1) has been reported to be effective in the treatment of nonalcoholic fatty liver disease (NAFLD). However, the molecular mechanism of GLP-1 on NAFLD is remained unclear. The present study was to detect whether the effect of GLP-1 on triglyceride (TG) content in hepatocytes is dependent on Foxos. Methods HepG2 cells were treated with palmitic/oleic acid for 24 h. The knockdown of Foxo1, Foxo3 was conducted through small interfering RNA (siRNA). Real time PCT (RT-PCR) was used to detect the changes of the SREBP1c and Acox2 genes in HepG2 cells after Foxo1/3 knockdown. Results As expected, palmitic/oleic acid increased TG concentration in HepG2 cells [(12.65 ± 1.32) μg/mg vs. (4.32±0.54) μg/mg, P<0.05]. Addition of GLP-1 dose (10, 50, 100nmol/L) dependently lowered the TG content and reached plateau at 100 nmol/L of GLP-1 [TG(8.38±1.47) μg/mg]. The GLP-1 effect on TG remained after knocking down either Foxo1 [(9.09±1.34)μg/mg] or Foxo3 [(8.90±1.60) μg/mg] alone, but not when knocking down Foxo1 and Foxo3 (Foxo1/3) together [(14.66±1.77)μg/mg]. Moreover, knocking down Foxo1/3 also abolished GLP-1 effect on SREBP1c and Acox2 expression. Conclusion GLP-1 can inhibit the synthesis of TG in hepatocytes depending on Foxo1 and Foxo3. Further studies are needed to explore the specific mechanisms.