小鼠肝脏胰岛素受体的特异性敲除降低极低密度脂蛋白中三酰甘油分泌的研究

Knockout of insulin receptors in hepatocytes reduced the secretion of triglyceride in very low density lipoprotein

目的:建立肝组织特异性胰岛素受体急性缺失的动物模型,分析胰岛素信号缺失对三酰甘油代谢的影响。方法:在构建腺病毒时,利用Cre-LoxP系统机制,在Cre重组酶基因的上游插入肝组织特异性表达的白蛋白基因启动子。扩增纯化病毒,经小鼠尾静脉注射病毒14 d后,收集小鼠血浆,测定极低密度脂蛋白三酰甘油分泌速率,抽提肝脏脂质并用酶法检测脂质含量,用免疫印迹法分析胰岛素受体和脂代谢相关基因在肝脏内的表达。结果:成功构建了肝脏特异性胰岛素受体急性缺失动物模型。胰岛素信号缺失显著降低了小鼠肝脏的极低密度脂蛋白三酰甘油的分泌速度,同时也下调了肝脏脂肪酸合成相关基因和极低密度脂蛋白形成相关基因的表达。结论:肝脏胰岛素信号急性缺失降低极低密度脂蛋白中三酰甘油的分泌速度,这种变化可能和肝脏内脂肪酸的合成速度下降有关。

Objective：In order to investigate the effect of insulin signaling in triglyceride（TG） metabolism,a hepatic insulin receptor knockout model was developed.Methods：Based on Cre-LoxP system,a promoter of hepatic tissue specific albumin gene was introduced into upstream of the cre recombinase gene.Albumin-Cre adenovirus（Ad-CRE） and GFP adenovirus（Ad-GFP） were amplified in 293A cells and purified before intravenous administration.After adenovirus infection for 14 days,blood samples were collected and livers were frozen.The levels of cholesterol（TC） and TG were measured,and the expression of insulin receptor and other lipoprotein metabolism related genes were analyzed by Western blot.The TG secretion rate in very low density lipoprotein（VLDL） was determined by injection of Triton WR1339.Results： The mouse model of acute knockout for hepatic insulin receptor was successfully established.TG secretion in VLDL was reduced,accompanied by decreased expression of lipoprotein metabolism related genes in hepatic insulin receptor-depletion mice.Conclusion： Acute knockout of hepatic insulin receptor reduced TG secretion in VLDL,which is probably associated with decreased lipogenesis.