Functional recovery of diabetic mouse hearts by glutaredoxin-1 gene therapy: role of Akt-FoxO-signaling network (original) (raw)
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Journal of Molecular and Cellular Cardiology, 2008
This study examined if glutaredoxin-1 (Glrx1), a redox-regulator of thioredoxin superfamily, plays any role in the redox signaling of ischemic myocardium. The hearts were subjected to 30 min of coronary occlusion followed by 24 h of reperfusion. Another group of hearts was rendered tolerant to ischemia (preconditioned, PC) by four cyclic episodes of 5 min ischemia each followed by another 10 min of reperfusion, which was then subjected to 30 min ischemia and 24 h of coronary occlusion. While ischemia/reperfusion had no effect on Glrx1 expression, adaptation to ischemia resulted in the upregulation of Glrx1 expression, which was inhibited by cadmium, a known inhibitor of Glrx1. CdCl 2 also abolished cardioprotection afforded by PC as evidenced by its ability to partially increase myocardial infarct size without affecting cardiomyocyte apoptosis. The amount of ROS was significantly decreased in the PC heart, which was abolished by CdCl 2 . The cardioprotective role of Glrx1was further confirmed with Glrx1 transgenic and knockout mice. The mouse hearts overexpressing Glrx1 exhibited significantly improved post-ischemic ventricular recovery and reduced myocardial infarct size while hearts deficient in Glrx1 exhibited depressed functional recovery and increased infarct size as compared to the wild-type hearts. Furthermore, Glrx1overexpressing hearts exhibited reduced and Glrx1-deficient hearts exhibited increased ROS production during ischemia and reperfusion. Adapted hearts showed increased Akt phosphorylation that was inhibited by CdCl 2 . The amount of Bcl-2 protein expression was not affected by the inhibition of Glrx1. Taken together, the results of this study implicate a role of Glrx1 in cardioprotection and redox signaling of the ischemic myocardium.
Journal of Molecular and Cellular Cardiology, 2008
This study examined if glutaredoxin-1 (Glrx1), a redox-regulator of thioredoxin superfamily, plays any role in the redox signaling of ischemic myocardium. The hearts were subjected to 30 min of coronary occlusion followed by 24 h of reperfusion. Another group of hearts was rendered tolerant to ischemia (preconditioned, PC) by four cyclic episodes of 5 min ischemia each followed by another 10 min of reperfusion, which was then subjected to 30 min ischemia and 24 h of coronary occlusion. While ischemia/reperfusion had no effect on Glrx1 expression, adaptation to ischemia resulted in the upregulation of Glrx1 expression, which was inhibited by cadmium, a known inhibitor of Glrx1. CdCl 2 also abolished cardioprotection afforded by PC as evidenced by its ability to partially increase myocardial infarct size without affecting cardiomyocyte apoptosis. The amount of ROS was significantly decreased in the PC heart, which was abolished by CdCl 2 . The cardioprotective role of Glrx1was further confirmed with Glrx1 transgenic and knockout mice. The mouse hearts overexpressing Glrx1 exhibited significantly improved post-ischemic ventricular recovery and reduced myocardial infarct size while hearts deficient in Glrx1 exhibited depressed functional recovery and increased infarct size as compared to the wild-type hearts. Furthermore, Glrx1overexpressing hearts exhibited reduced and Glrx1-deficient hearts exhibited increased ROS production during ischemia and reperfusion. Adapted hearts showed increased Akt phosphorylation that was inhibited by CdCl 2 . The amount of Bcl-2 protein expression was not affected by the inhibition of Glrx1. Taken together, the results of this study implicate a role of Glrx1 in cardioprotection and redox signaling of the ischemic myocardium.
Free Radical Biology and Medicine, 2007
To understand the physiological function of glutaredoxin, a thiotransferase catalyzing the reduction of mixed disulfides of protein and glutathione (protein-SSG), we generated a line of knockout mice deficient in the cytosolic glutaredoxin 1 (Grx1). To our surprise, mice deficient in Grx1 were not more susceptible to acute oxidative insults in models of heart and lung injury induced by ischemia/ reperfusion and hyperoxia, respectively; suggesting that changes in S-glutathionylation status of cytosolic proteins are not the major cause of such tissue injury. On the other hand, mouse embryonic fibroblasts (MEFs) isolated from Grx1-deficient mice displayed an increased vulnerability to diquat and paraquat, but they were not more susceptible to cell death induced by hydrogen peroxide (H 2 O 2 ) and diamide. A deficiency in Grx1 also sensitized MEFs to protein S-glutathionylation in response to H 2 O 2 treatment and retarded deglatuthionylation of the S-glutathionylated proteins, especially evident for an unspecified protein of approximately 44 kDa. Additional experiments showed that MEFs lacking Grx1 were more tolerant to apoptosis induced by tumor necrosis factor α plus actinomycin D. These findings suggest that different oxidants may damage the cells via distinct mechanisms in which Grx1-dependent de-glutathionylation may or may not be protective, and Grx1 may exert its function on specific target proteins.
Role of Glutaredoxin-1 and Glutathionylation in Cardiovascular Diseases
International Journal of Molecular Sciences
Cardiovascular diseases are the leading cause of death worldwide, and as rates continue to increase, discovering mechanisms and therapeutic targets become increasingly important. An underlying cause of most cardiovascular diseases is believed to be excess reactive oxygen or nitrogen species. Glutathione, the most abundant cellular antioxidant, plays an important role in the body’s reaction to oxidative stress by forming reversible disulfide bridges with a variety of proteins, termed glutathionylation (GSylation). GSylation can alter the activity, function, and structure of proteins, making it a major regulator of cellular processes. Glutathione-protein mixed disulfide bonds are regulated by glutaredoxins (Glrxs), thioltransferase members of the thioredoxin family. Glrxs reduce GSylated proteins and make them available for another redox signaling cycle. Glrxs and GSylation play an important role in cardiovascular diseases, such as myocardial ischemia and reperfusion, cardiac hypertro...
Journal of Molecular and Cellular Cardiology, 2008
Mitochondrial glutaredoxin-2 (Glrx2) has been recognized as an important redox regulator in mammalian organs including heart. To date no investigations have addressed the potential role of Glrx2 in cardiac disorders. The present study examined if myocardial overexpression of Glrx2 in the heart could rescue the cardiac cells from apoptosis and necrosis induced by ischemia and reperfusion. The human Glrx2 transgene was created by placing a full-length cDNA fragment encoding human mitochondrial Glrx2 downstream to the 5′ flanking sequence and promoter of the mouse α-myosin heavy chain gene. The isolated hearts from Glrx2 transgenic mice and non-transgenic (wild type) littermates [on c57BL/ 6×C3H hybrid background] were subjected to 30 min of global ischemia followed by 2 h of reperfusion via working mode. The hearts from Glrx2 transgenic mice displayed significantly improved contractile performance and reduced myocardial infarct size and cardiomyocyte apoptosis. There was a reduction in cytochrome c release and activation of caspase 3 and caspase 9. Glrx2 overexpression also reduced the ischemia/reperfusionmediated loss of mitochondrial cardiolipin, decreased the activities of reactive oxygen species (ROS) and preserved GSH/GSSG ratio. Glrx2 mediated survival signal appeared to be stemmed from PI-3-kinase-Akt survival signaling pathway and involved the activation of redox sensitive transcription factor NFκB and antiapoptotic protein Bcl-2. The results indicated a crucial role of mitochondrial Glrx2 in cardioprotection.
Biochemical and Biophysical Research Communications, 2009
Oxidative stress induced by hyperglycemia is a key factor in the development of cardiovascular diseases in diabetes. Thioredoxin (Trx) system, a major thiol antioxidant system, regulates the reduction of intracellular reactive oxygen species (ROS). In this study, we demonstrated that high glucose significantly increased intracellular ROS levels in human aortic endothelial cells (HAECs). Additionally, high glucose reduced the antioxidant activity of thioredoxin. To investigate the mechanisms involved, we found that glucose enhanced the expression of thioredoxin interacting protein (Txnip), a Trx inhibitory protein, through p38 mitogen-activated protein kinase (MAPK). We also showed that glucose regulated Txnip at transcription level and p38 MAPK and forkhead box O1 transcriptional factor (FOXO1) were involved in the process. Taken together, upregulation of Txnip and subsequent impairment of thioredoxin antioxidative system through p38 MAPK and FOXO1 may represent a novel mechanism for glucose-induced increase in intracellular ROS.
American Journal of …, 2007
Reactive oxygen species (ROS) and the cellular thiol redox state are crucial mediators of multiple processes in cells like growth, differentiation and apoptosis. Excessive ROS production or oxidative stress is associated with several diseases, including cardiovascular disorders like ischemia/reperfusion. To prevent ROS-induced disorders, the heart is equipped with effective antioxidant systems. Key players in defence against oxidative stress are members of the thioredoxin fold family of proteins. Of these, thioredoxins and glutaredoxins maintain a reduced intracellular redox state in mammalian cells by the reduction of protein thiols. The reversible oxidation of CGPC or CP(S)YC active site cysteine residues is used in reversible electron transport. Thioredoxins and glutaredoxins belong to corresponding systems consisting of NADPH, thioredoxin reductase and thioredoxin or NADPH, glutathione reductase, glutathione and glutaredoxin, respectively. Thioredoxin as well as glutaredoxin activities appear to be very important for progression and severity of several cardiovascular disorders. These proteins function not only as antioxidants, they inhibit or activate apoptotic signaling molecules like apoptosis signal-regulating kinase 1 (ASK-1) and Ras or transcription factors like NF-BB. Thioredoxin activity is regulated by the endogenous inhibitor thioredoxin binding protein 2 (TBP2) indicating an important role of the balance between thioredoxin and TBP2 levels in cardiovascular diseases. In this review, we will summarize cardioprotective effects of endogenous thioredoxin and glutaredoxin systems as well as the high potential in clinical applications of exogenously applied thioredoxin or glutaredoxin or the induction of endogenous thioredoxin and glutaredoxin systems.
Increased Gene Expression of Glutathione Peroxidase-3 in Diabetic Mouse Heart
Biological & Pharmaceutical Bulletin, 2006
Cardiovascular complications of diabetes are the leading cause of mortality. Coronary artery disease is well known as a frequent complication in diabetic patients, while impaired ventricular performance without coronary lesion has been reported in experimental diabetic animals as well as in diabetic patients. 1,2) One of the mechanisms of such functional impairment is the metabolic perturbation of myocytes, 3) including the acceleration of the polyol pathway, an alternate route of glucose metabolism. 4) On the other hand, the alteration of gene expression under hyperglycemia is another factor involved in the pathogenesis of diabetic cardiomyopathy, which may modulate the cellular metabolism, signal transduction and host defense system. Thus, it is of practical significance to elucidate the differences in gene expression between normal and diabetic subjects. So far, however, the gene expression profile in the diabetic heart has not been well documented. This led us to undertake an investigation of the gene expression profile in experimentally induced diabetic mice using a cDNA array technique. We here report a predominant up-regulation of the plasma type glutathione peroxidase, GPX-3, in the streptozotocin-induced diabetic mouse heart. Since oxidative stress is one of the major causes of diabetic complications, 5,6) up-regulation of the GPX-3 gene may be a counter-regulatory response in cardiac tissue to attenuate oxidative insults under hyperglycemia. MATERIALS AND METHODS Materials Mouse cDNA macroarray membranes containing 588 known genes were products of Clontech (Palo Alto, CA, U.S.A.). Other reagents were of the highest grade available. Diabetic Animal Model Male 7-week-old BDF-1 mice fed ad libitum were used in this study. Hyperglycemia was induced by a single administration of streptozotocin (STZ, 200 mg/kg body weight) in the tail vein. The onset of hyperglycemia was verified 3 d after injection of STZ by the mutarotase glucose oxidase method. Insulin (INS, 0.2 U/ mouse/d s.c.) was administered daily for 21 d. The animal
Protective role of thioredoxin-1 in cardiovascular systems
Signal Transduction, 2005
The thioredoxin-1 (Trx-1) system consists of two oxidoreductases, the thioredoxin-reductase and Trx-1. Trx-1 is a ubiquitously expressed oxidoreductase. The cellular functions of Trx-1 are wide range. They include protein disulfide reduction, DNA synthesis, protection from apoptosis, redox regulation of a variety of proteins transcription factors and reduction of H 2 O 2 , respectively. This review will first focus on the essential role for Trx-1 in different cardiovascular cells, namely smooth muscle cells, endothelial cells and cardiomyocytes. Thereby, the review will demonstrate the predominant role of Trx-1 to limit oxidative stress directly due to reactive oxygen species scavenging and by protein-protein interaction with key signaling molecules. Furthermore, the review will focus on important in vivo studies showing a protective role of Trx-1 in different cardiovascular diseases. Thus, the Trx system and Trx-1 could be important future targets to develop clinical therapies for cardiovascular disorders.