Ang-(1-7)与Mas结合促进NIT细胞分泌胰岛素

摘要

Objective To investigate the effects of Ang-(l-7) and Mas receptor on insulin secretion in NIT cell and their potential mechanism. Methods NIT cells were exposed to Ang-(l-7) of different concentrations (10~ ~ 10-3 mol/L) for 24 hours. Glucose stimulated insulin secretion by NIT cells was detected with ELISA. The full cDNA sequence of Mas, GLUT-2 and TGF-β1 were obtained from NIT cell line using RT-PCR. After NIT cells were exposed to 10-5 mol/L Ang-(l-7) for 48 hours, Mas, GLUT-2 and TGF-β 1 mRNA expression were estimated by real-time PCR; Meantime, the protein levels of the afore variables were detected by Western blot analy-sis. Results NIT islet cell line responded to extracellular Ang-(l-7) (10-8 -10-3 mol/L) with increased insulin secretion in a concentration dependent manner. The insulin secretion increased significantly in the presence of 10-5mol/LAng-(l-7) (8.86±0.53)mlU/Lcompared to control group (8, 06 ±0. 39)mlU/L) (P<0.05). In the experiments, compared to control group, the cells preincubated with 10-5 mol/L Ang-(l-7) were up-regulated in Mas gene and protein expression ( P < 0. 05 ) , and caused a significant stimulation of mRNA and protein expres-sion of GLUT-2 (P <0. 05). On the contrary, the result showed a reduction in TGF-βl mRNA and protein expression (P <0. 05). Conclusions The binding of Ang-( 1-7) and Mas can stimulate the NIT cells to secrete insulin, probably through its enhancing the ability to intake glucose and inhibit the progression of fibrosis.%目的 体外研究Ang-( 1-7)对NIT细胞胰岛素分泌的影响及其潜在机制.方法 将NIT细胞在不同浓度Ang-(1-7)( 10-8～10-3 mol/L)培养24 h,ELISA法检测NIT细胞对葡萄糖刺激的胰岛素分泌功能.用RT-PCR法,从NIT细胞中扩增Mas、GLUT-2和TGF-β1基因的全长cDNA序列.将NIT细胞在10-5mol/L Ang-(1-7)条件下培养48 h,QRT-PCR方法检测NIT细胞Mas、GLUT-2及TGF-β1的mRNA表达,Western印迹方法测定NIT细胞Mas、GLUT-2及TGF-β1的蛋白表达.结果 NIT细胞系随着细胞外Ang-( 1-7)浓度(10-8～ 10-3 mol/L)的增加胰岛素分泌增加,10-5 mol/L Ang-( 1-7)组胰岛素分泌量为(8.86±0.53)mIU/L,显著高于对照组(8.06±0.39) mIU/L(P＜0.05).与对照组相比,经10-5 mol/L Ang-(1-7)预处理的NIT细胞Mas及GLUT-2的mRNA和蛋白表达上调(P＜0.05)；相反,经10-5 mol/L Ang-(1-7)预处理的NIT细胞TGF-β1的mRNA和蛋白表达水平下降(P＜0.05).结论 Ang-( 1-7)与Mas结合能够促进NIT细胞分泌胰岛素,这可能与提高NIT细胞摄取葡萄糖的能力、抑制纤维化进程等相关.