Department of Gastroenterology, First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, Zhejiang Province, China.
J Gastroenterol Hepatol. 2010 Mar;25(3):613-8. doi: 10.1111/j.1440-1746.2009.06086.x. Epub 2009 Nov 19.
The aim of the present study is to elucidate whether endoplasmic reticulum stress involved in the course of lipogenesis in fatty acids induced hepatic steatosis and the potential effect of metformin on endoplasmic reticulum stress.
HepG2 cells were exposed to different types of culture media. After incubation for 24 h, cells were harvested to evaluate cell survival rate and lipid level among different groups. Moreover, reverse transcriptase polymerase chain reaction and western blot for glucose-regulated protein-78 (GRP78), sterol response element-binding protein-1c (SREBP1c) and fatty acid synthase (FAS) were applied.
The levels of triglyceride (TG), mRNA of FAS, mRNA and protein of GRP78 and SREBP1c significantly increased in the free fatty acids (FFA)-induced hepatic steatosis group. Then, HepG2 cells with hepatic steatosis induced by FFA were treated by metformin, levels of TG, GRP78 mRNA, SREBP1c mRNA and FAS mRNA as well as GRP78 and SREBP1 protein levels were partially decreased but without significant differences.
Endoplasmic reticulum stress might be involved in lipogenesis in fatty acids-induced hepatic steatosis. Therefore, endoplasmic reticulum stress might serve as a novel target in the pathogenesis and therapy of non-alcoholic fatty liver disease.
本研究旨在阐明内质网应激是否参与脂肪酸诱导的肝脂肪生成过程，并探讨二甲双胍对内质网应激的潜在作用。
将 HepG2 细胞暴露于不同类型的培养基中。孵育 24 h 后，收集细胞以评估不同组之间的细胞存活率和脂质水平。此外，应用逆转录聚合酶链反应和 Western blot 检测葡萄糖调节蛋白 78（GRP78）、固醇调节元件结合蛋白 1c（SREBP1c）和脂肪酸合成酶（FAS）。
游离脂肪酸（FFA）诱导的肝脂肪变性组中甘油三酯（TG）水平、FAS mRNA、GRP78 mRNA 和 SREBP1c mRNA 及 FAS 蛋白水平显著升高。然后，用二甲双胍处理由 FFA 诱导的肝脂肪变性的 HepG2 细胞，TG 水平、GRP78 mRNA、SREBP1c mRNA 和 FAS mRNA 以及 GRP78 和 SREBP1 蛋白水平部分降低，但无统计学差异。
内质网应激可能参与脂肪酸诱导的肝脂肪生成。因此，内质网应激可能成为非酒精性脂肪性肝病发病机制和治疗的新靶点。
