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内质网应激(endoplasmic reticulum stress,ER stress)对非酒精性脂肪性肝病(non-alcoholic fatty liver disease,NAFLD)的发生发展具有十分重要的作用。本实验室前期结果证实,载脂蛋白A1(apolipoprotein A-Ⅰ,apo A-Ⅰ)可以通过减少肝细胞脂质堆积来减轻蛋氨酸胆碱缺乏饲料造成的非酒精性肝炎(non-alcoholic steatohepatitis,NASH),但相关机制仍不十分清楚。为探索apo A-Ⅰ对内质网应激的影响,本研究采用衣霉素处理人肝癌BEL-7402细胞。Western印迹结果证实,衣霉素确实可以诱导BEL-7402细胞内质网应激,并具有时间和剂量依赖性。通过将apo A-Ⅰ表达载体及其对照载体转染到BEL-7402细胞,再加入衣霉素处理,结果显示,与对照组相比,过表达apo A-Ⅰ的细胞内质网应激标志分子表达明显减轻,同时与脂质合成相关的固醇调节元件结合蛋白1、脂肪酸合成酶和乙酰辅酶A羧化酶1蛋白质水平明显降低。脂质检测结果表明,细胞内甘油三酯和游离胆固醇水平也明显降低(P<0.05)。上述结果表明,apo A-Ⅰ能够减轻衣霉素引起的内质网应激,可能机制是通过调控固醇调节元件结合蛋白1减少肝细胞的脂质堆积。
Endoplasmic reticulum stress (ER stress) plays an important role in the development of non-alcoholic fatty liver disease (NAFLD). Our previous results demonstrated that apolipoprotein A-Ⅰ (apo A-Ⅰ) can reduce the non-alcoholic steatohepatitis (NASH) caused by choline deficiency in feedstuffs by reducing the lipid accumulation in liver cells ), But the mechanism is still not very clear. In order to explore the impact of apo A-Ⅰ on endoplasmic reticulum stress, we used tunicamycin to treat human hepatoma BEL-7402 cells. Western blotting results confirmed that tunicamycin can indeed induce endoplasmic reticulum stress in BEL-7402 cells in a time-and dose-dependent manner. By transfecting apo A-Ⅰ expression vector and its control vector into BEL-7402 cells and adding tunicamycin, the results showed that compared with the control group, the endoplasmic reticulum stress marker overexpressing apo A-Ⅰ At the same time, the protein levels of sterol regulatory element binding protein 1, fatty acid synthase and acetyl CoA carboxylase 1 related to lipid synthesis were significantly reduced. Lipid test results showed that intracellular triglyceride and free cholesterol levels were also significantly reduced (P <0.05). The above results indicate that apo A-Ⅰ can attenuate tunicamycin-induced endoplasmic reticulum stress through a mechanism that reduces lipid accumulation in hepatocytes by regulating sterol regulatory element-binding protein-1.