胰岛素抵抗细胞模型的胰岛素降解酶表达

Expression of insulin degrading enzyme in insulin resistance cell model

目的 了解胰岛素降解酶 (IDE)基因、酶蛋白表达水平与胰岛素敏感性的关系 ,并初步探讨胰岛素降解抑制剂氯喹改善胰岛素敏感性的分子机制。方法 以原代大鼠肝细胞胰岛素抵抗(IR)模型为研究对象 ,分别采用免疫印迹技术和逆转录 聚合酶链反应 (RT PCR)技术检测IR细胞模型的IDE酶蛋白表达 (EIP)及基因表达水平 (EIG) ,同时检测IDE活性和反映细胞胰岛素敏感性的14 C 2 脱氧葡萄糖掺入率及14 C 醋酸盐掺入率 ,并观察氯喹对IR细胞模型上述指标的影响。结果IR细胞模型的EIG及EIP水平显著高于对照细胞 ,并与其IDE活性呈显著正相关 ,与两种掺入率呈显著负相关。同时氯喹可明显抑制IR细胞模型以及对照细胞的EIG及EIP水平 ,而且抑制的程度与氯喹作用时间的长短密切相关。结论 大鼠肝细胞的EIG和EIP与其胰岛素敏感性之间呈负相关关系 ;高浓度胰岛素可刺激大鼠肝细胞的IDE基因mRNA及酶蛋白的表达 ,而氯喹则对其起明显的抑制作用 ;胰岛素和氯喹对大鼠肝细胞EIG的影响可能是通过影响IDE基因转录来实现。

Objective To study the relationship among expression of insulin degrading enzyme (IDE) gene (EIG), enzyme protein and insulin sensitivity, and to investigate the molecular mechanism for improvement of insulin sensitivity by chloroquine. Methods Expression of IDE protein (EIP) and EIG were determined on insulin resistance (IR) hepatocytes of rat by immunoblotting technique and RT PCR respectively. Incorporation rate of 14 C 2 deoxyglucose and 14 C acetate which were used to estimate insulin sensitivity of cells, and IDE activity were determined in IR hepatocytes of rat. Moreover, effects of chloroquine on these indices were observed. Results EIG, EIP in IR cells were higher than those in the control cells. EIG and EIP were positively correlated with IDE activity, and negatively correlated with the two kinds of incorporation rate. Chloroquine significantly decreased EIG and EIP in IR cells and control cells, and the decreases in EIG and EIP were correlated with the duration of treatment. Conclusion EIG and EIP of rat hepatocytes were negatively correlated with insulin sensitivity; EIG and EIP of rat hepatocytes can be stimulated with insulin at high concentration and inhibited with chloroquine; Effects of insulin and chloroquine on EIG may influence the transcription of EIP in the hepatocytes of rat.