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自噬在TXNIP过表达诱导的INS-1胰岛细胞凋亡中的作用

王静, 王瑾, 王娟娟, 张炜芳, 焦向英

山西医科大学基础医学院生理学系，太原 030001

摘要

硫氧还蛋白相互作用蛋白(thioredoxin interacting protein, TXNIP)是内源性硫氧还蛋白结合抑制蛋白，在糖尿病患者血清和组织中均高表达。本研究观察TXNIP过表达对正常糖脂浓度下培养的INS-1细胞自噬水平的影响，并分析自噬在TXNIP诱导的细胞凋亡中的作用。常规培养的INS-1胰岛细胞分为正常培养组、空病毒(Ad-eGFP)组和TXNIP过表达(Ad-TXNIP-eGFP)组，后两组转染相应腺病毒，48 h后测定TXNIP mRNA和蛋白的表达情况；用Western blot检测各组自噬相关的Beclin-1、LC3和P62的蛋白表达情况，以cleaved caspase 3/caspase 3比值和流式细胞术检测各组细胞凋亡情况；用IF/ICC法检测各组细胞内自噬体数量的变化。结果显示，与Ad-eGFP组相比，Ad-TXNIP-eGFP组TXNIP mRNA和蛋白表达量均明显升高；与Ad-eGFP组相比，Ad-TXNIP-eGFP组LC3-II/LC3-I比值和Beclin-1蛋白表达水平升高，P62蛋白表达降低，自噬体荧光强度增强，细胞凋亡率升高，cleaved caspase 3/caspase 3比值上升。使用自噬抑制剂3-MA干预后，与TXNIP过表达组相比，TXNIP过表达+3-MA组自噬明显受到抑制，同时凋亡明显减轻。以上结果提示，在正常糖脂浓度培养下的INS-1细胞过表达TXNIP可以通过诱导自噬促进细胞凋亡。

关键词： INS-1细胞; 硫氧还蛋白相互作用蛋白 ; 自噬 ; 凋亡

分类号：R335+.6

Role of autophagy in TXNIP overexpression-induced apoptosis of INS-1 islet cells

Wang Jing, WANG Jin, WANG Juan-Juan, ZHANG Wei-Fang, JIAO Xiang-Ying

Department of Physiology, Shanxi Medical University, Taiyuan 030001, China

Abstract

Thioredoxin (Trx) interacting protein (TXNIP) is a Trx-binding protein that inhibits the antioxidative function of Trx and is highly expressed in the serum and tissue samples from diabetes patients. This study was to explore whether TXNIP overexpression could cause INS-1 cell autophagy under normal glucose and lipid concentrations, and to analyze the role of autophagy in the apoptosis of INS-1 cells. The INS-1 cells cultured under normal conditions were divided into three groups: normal control, empty adenovirus vector (Ad-eGFP) and TXNIP overexpression (Ad-TXNIP-eGFP) groups. Forty-eight hours after transfection, the expression levels of TXNIP mRNA and protein were measured. Western blot was used to examine the protein expression levels of Beclin-1 and P62, as well as LC3-II/LC3-I ratio, which are associated with autophagy. IF/ICC was used to measure the autophagosome. In addition, the cleaved caspase-3/caspase-3 ratio, the apoptosis marker, was also measured, and the apoptotic rates were detected by flow cytometry (FCM). The results showed that the TXNIP mRNA and protein levels were significantly up-regulated in Ad-TXNIP-eGFP group, suggesting that TXNIP overexpression model was successfully established. In Ad-TXNIP-eGFP group, the protein levels of Beclin-1 and LC3-II/LC3-I ratio were increased, while the protein expression of P62 was decreased, compared with those in Ad-eGFP group. Red fluorescent intensity, representing autophagy level, was higher in Ad-TXNIP-eGFP group than that in Ad-eGFP group. These results suggested that TXNIP overexpression can significantly promote INS-1 cell autophagy. Meanwhile, cleaved caspase 3/caspase 3 ratio and the number of apoptotic cells were significantly increased in Ad-TXNIP-eGFP group. The inhibitor of autophagy, 3-MA, reduced TXNIP overexpression-induced apoptosis in INS-1 cells. Taken together, our data demonstrate that autophagy appears to be an important pathway in TXNIP overexpression-induced apoptosis in INS-1 cells.

Key words: INS-1 islet cells; thioredoxin interacting protein ; autophagy ; apoptosis

收稿日期：2016-11-28　　录用日期：2017-01-11

通讯作者：焦向英　　E-mail: jiaoxy@gmail.com

引用本文：

王静, 王瑾, 王娟娟, 张炜芳, 焦向英. 自噬在TXNIP过表达诱导的INS-1胰岛细胞凋亡中的作用[J]. 生理学报 2017; 69 (4): 445-451.

Wang Jing, WANG Jin, WANG Juan-Juan, ZHANG Wei-Fang, JIAO Xiang-Ying. Role of autophagy in TXNIP overexpression-induced apoptosis of INS-1 islet cells. Acta Physiol Sin 2017; 69 (4): 445-451 (in Chinese with English abstract).