Chongxiao Liu1,2, Baige Cao1, Qianren Zhang1, Yifan Zhang1, Xueru Chen1, Xiang Kong3, Yan Dong4,5. 1. Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200092, China. 2. Department of Endocrinology, Seventh People's Hospital of Shanghai University of Traditional Chinese Medicine, Shanghai, 200137, China. 3. Department of Endocrinology, Yijishan Hospital Affiliated Wannan Medical College, Anhui, 241000, China. 4. Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200092, China. dongyansh@sjtu.edu.cn. 5. Shanghai Institute for Pediatric Research, Shanghai, 200092, China. dongyansh@sjtu.edu.cn.
Abstract
PURPOSE: To investigate the role of thioredoxin 2 (Trx2) inhibition induced by intracellular methylglyoxal (MGO) in pancreatic beta-cell mitochondrial dysfunction and apoptosis. METHODS: Rat pancreatic beta-cell line INS-1 cells were treated with Glo1 siRNAs or exogenous MGO to increase intracellular MGO. AGEs formation was detected by ELISA and mitochondrial ROS was detected by probe MitoSOX. Transmission electron microscopy (TEM) analysis and ATP content were measured to evaluate mitochondrial function. Trx2 expression was manipulated by overexpression with recombinant Trx2 lentivirus or knockdown with Trx2 siRNAs, and effects on apoptosis and insulin secretion were measured by flow cytometry and ELISA, respectively. RESULTS: The increase of intracellular MGO by Glo1 blockage or MGO treatment led to advanced glycation end products (AGEs) overproduction, mitochondrial ROS increase, and insulin secretion paralysis. These were probably due to MGO-induced inhibition of mitochondrial Trx2. Trx2 inhibition by blockage of either Glo1 or Trx2 impaired mitochondrial integrity, inhibited cytochrome C oxidases subunit 1 and 4 (Cox1 and Cox4) expression and further reduced ATP generation, and all of these might lead to insulin paralysis; whereas Trx2 overexpression partially reversed MGO-induced oxidative stress, attenuated insulin secretion by preventing mitochondrial damage. Trx2 overexpression also retarded MGO-induced apoptosis of INS-1 cell through inhibiting ASK1 activation and downregulation of the ASK1-p38 MAPK pathway. CONCLUSIONS: Our results reveal a possible mechanism for beta-cell oxidative damage upon intracellular MGO-induced Trx2 inactivation and mitochondrial dysfunction and apoptosis.
PURPOSE: To investigate the role of thioredoxin 2 (Trx2) inhibition induced by intracellular methylglyoxal (MGO) in pancreatic beta-cell mitochondrial dysfunction and apoptosis. METHODS: Rat pancreatic beta-cell line INS-1 cells were treated with Glo1 siRNAs or exogenous MGO to increase intracellular MGO. AGEs formation was detected by ELISA and mitochondrial ROS was detected by probe MitoSOX. Transmission electron microscopy (TEM) analysis and ATP content were measured to evaluate mitochondrial function. Trx2 expression was manipulated by overexpression with recombinant Trx2 lentivirus or knockdown with Trx2 siRNAs, and effects on apoptosis and insulin secretion were measured by flow cytometry and ELISA, respectively. RESULTS: The increase of intracellular MGO by Glo1 blockage or MGO treatment led to advanced glycation end products (AGEs) overproduction, mitochondrial ROS increase, and insulin secretion paralysis. These were probably due to MGO-induced inhibition of mitochondrial Trx2. Trx2 inhibition by blockage of either Glo1 or Trx2 impaired mitochondrial integrity, inhibited cytochrome C oxidases subunit 1 and 4 (Cox1 and Cox4) expression and further reduced ATP generation, and all of these might lead to insulin paralysis; whereas Trx2 overexpression partially reversed MGO-induced oxidative stress, attenuated insulin secretion by preventing mitochondrial damage. Trx2 overexpression also retarded MGO-induced apoptosis of INS-1 cell through inhibiting ASK1 activation and downregulation of the ASK1-p38 MAPK pathway. CONCLUSIONS: Our results reveal a possible mechanism for beta-cell oxidative damage upon intracellular MGO-induced Trx2 inactivation and mitochondrial dysfunction and apoptosis.
Authors: Jae-Chul Lee; Joon Ha Park; In Hye Kim; Geum-Sil Cho; Ji Hyeon Ahn; Hyun-Jin Tae; Soo Young Choi; Jun Hwi Cho; Dae Won Kim; Young-Guen Kwon; Il Jun Kang; Moo-Ho Won; Young-Myeong Kim Journal: Brain Pathol Date: 2016-06-27 Impact factor: 6.508