游离脂肪酸诱导的胰岛βTC3细胞缺陷与线粒体功能改变的相关性研究

Free fatty acids-induced βTC3 cell defects are associated with altered mitochondrial function

目的通过研究游离脂肪酸(FFA)慢性作用对胰岛细胞解偶联蛋白2(UCP2)mRNA和蛋白表达以及线粒体膜电位的影响,探讨FFA损害胰岛功能的机制。方法将不同浓度油酸作用于胰岛βTC3细胞72h,分别分析基础和葡萄糖刺激的胰岛素分泌量(GSIS),线粒体膜电位,ATP敏感钾电流(IKATP)、UCP2mRNA和蛋白表达;再用油酸和PPARγ配体罗格列酮共同作用,观察UCP2mRNA和蛋白的表达。结果与对照组相比,油酸明显增加2·8mmol/L葡萄糖时的基础胰岛素分泌量,减少16·7mmol/L葡萄糖时的GSIS(P均<0·01),并且呈剂量依赖性。油酸可明显降低线粒体膜电位平均荧光强度(MIF)值,使IKATP外流增加,增加UCP2mRNA和蛋白表达(P均<0·01),呈剂量依赖性;与油酸组相比,油酸+罗格列酮组增加了UCP2mRNA和蛋白表达(P<0·01)。结论在胰岛βTC3细胞中,FFA对胰岛功能的损害与线粒体功能改变有关。FFA可能通过上调PPARγ增加UCP2表达,UCP2的表达与作用增加可导致线粒体膜电位降低,使线粒体功能下降,引起胰岛素分泌减少,产生对胰岛功能的损害作用。

Objective To investigate the effect of free fatty acids（FFA） on uncoupling protein 2 （UCP2） and mitochondrial membrane potential on islet βTC3 cells, and to explore the mechanism of pancreatic β cells impairment induced by FFA. Methods βTC3 cells were exposed to different concentrations of oleic acid. After incubation for 72 hours, the amount of basal and glucose-stimulated insulin secretion（GSIS）, mitochondrial membrane potential, ATP-sensitive potassium currents （IKATP） and the mRNA and protein expressions of UCP2 were determined. Results Compared with those in the control group, the oleic acid groups showed that basal insulin secretion was significantly increased （glucose 2. 8 mmol/L）and glucose-stimulated insulin release（glucose 16.7 mmol/L）was markedly reduced （all P〈 0.01） in a dose-dependent manner. Oleic acid significantly decreased mitochondrial membrane potential and increased the levels IKATP and the mRNA and protein expressions of UCP2（all P〈0. 01） in a dose-dependent manner. Conclusions In islet βTC3 cells chronically exposed to FFA, the impairment of the function of islets may be associated with altered mitochontrial function. FFA causes overexpressions of the UCP-2 mRNA and protein via PPART pathway, which results in a decrease of mitochondrial membrane potential.