Original article Role of glutaredoxin-1 in cardioprotection: An insight with Glrx1 transgenic and knockout animals Gautam Malik, Norbert Nagy, Ye-Shih Ho, Nilanjana Maulik, Dipak K. Das ⁎ Cardiovascular Research Center, University of Connecticut School of Medicine, Farmington, Connecticut, CT 06030-1110, USA Institute of Environmental Health Sciences, Wayne State University, Detroit, MI, USA Received 26 July 2007; received in revised form 20 August 2007; accepted 28 August 2007 Available online 18 September 2007 Abstract 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 up- regulation 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, Glrx1- overexpressing 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. © 2007 Elsevier Inc. All rights reserved. Keywords: Glutaredoxin; Reactive oxygen species; Transgenic and knockout mice; Adapted heart; Ischemia/reperfusion; Redox signaling 1. Introduction Glutaredoxins (Glrxs) belong to the members of the thioredoxin superfamily of thiol/disulfide exchange catalysts, and hence known as thioltransferases. Glrxs serve as reductants of protein- SG mixed disulfides, provide reducing equivalents to ribonucle- otide reductase [1,2]. Glrxs are predominantly localized in the cytoplasm; however, they can also be detected in the nucleus and mitochondria [3]. Two mammalian Glrxs have been identified: Glrx1 localizes in the cytosol and Glrx1 localizes primarily in mitochondria, but can also localize in the nucleus [4]. Glrx2 encodes two isoforms; a nuclear Glrx2 exists in addition to a mitochondrial Glrx2. Both Glrx1 and Glrx2 play a crucial role in redox regulation. Similar to Trx-1 [5], Glrx1 can regulate apoptosis through ASK-1 (apoptosis signal-regulating kinase-1), which is a mitogen- activated protein kinase kinase kinase (MAPKKK) that binds to the reduced Glrx1 [6]. Upon oxidation, Glrx1 becomes detached from ASK-1 thereby potentiating a survival signal while activation of ASK-1 will generate a death signal. Recently, Glrx1 has been identified in mammalian hearts [7]; however, its role in ischemic heart disease remains unknown. The present study was designed to determine the role of Glrx1 in myocardial ischemic reperfusion injury. We developed transgenic mice overexpressing Glrx1 as well as Glrx1 knockout mice devoid of Glrx1 expression in the heart to specifically examine the role of Glrx1 in the heart. The results of our study demonstrated that Glrx1 transgenic mouse hearts were resistant to and Glrx1 knockout mouse hearts were susceptible to ischemia reperfusion injury. Available online at www.sciencedirect.com Journal of Molecular and Cellular Cardiology 44 (2008) 261 – 269 www.elsevier.com/locate/yjmcc ⁎ Corresponding author. Cardiovascular Research Center, University of Connecticut School of Medicine, Farmington, Connecticut, CT 06030-1110, USA. Tel: +1 860 679 3687; fax: +1 860 679 4606. E-mail address: DDAS@NEURON.UCHC.EDU (D.K. Das). 0022-2828/$ - see front matter © 2007 Elsevier Inc. All rights reserved. doi:10.1016/j.yjmcc.2007.08.022 RETRACTED