BCNU-induced gR2 defect mediates S-glutathionylation of Complex I and respiratory uncoupling in myocardium.
A deficiency of mitochondrial glutathione reductase (or GR2) is capable of adversely affecting the reduction of GSSG and increasing mitochondrial oxidative stress. BCNU [1,3-bis (2-chloroethyl)-1-nitrosourea] is an anticancer agent and known inhibitor of cytosolic GR ex vivo and in vivo. Here we tested the hypothesis that a BCNU-induced GR2 defect contributes to mitochondrial dysfunction and subsequent impairment of heart function. Intraperitoneal administration of BCNU (40 mg/kg) specifically inhibited GR2 activity by 79.8 ± 2.7% in the mitochondria of rat heart. However, BCNU treatment modestly enhanced the activities of mitochondrial Complex I and other ETC components. The cardiac function of BCNU-treated rats was analyzed by echocardiography, revealing a systolic dysfunction associated with decreased ejection fraction, decreased cardiac output, and an increase in left ventricular internal dimension and left ventricular volume in systole. The respiratory control index of isolated mitochondria from the myocardium was moderately decreased after BCNU treatment, whereas NADH-linked uncoupling of oxygen consumption was significantly enhanced. Extracellular flux analysis to measure the fatty acid oxidation of myocytes indicated a 20% enhancement after BCNU treatment. When the mitochondria were immunoblotted with antibodies against GSH and UCP3, both protein S-glutathionylation of Complex I and expression of UCP3 were significantly up-regulated. Overexpression of SOD2 in the myocardium significantly reversed BCNU-induced GR2 inhibition and mitochondrial impairment. In conclusion, BCNU-mediated cardiotoxicity is characterized by the GR2 deficiency that negatively regulates heart function by impairing mitochondrial integrity, increasing oxidative stress with Complex I S-glutathionylation, and enhancing uncoupling of mitochondrial respiration.
Department of Integrative Medical Sciences, College of Medicine, Northeast Ohio Medical University, Rootstown, OH 44272, USA.
Patrick T
PT
Kang
Department of Integrative Medical Sciences, College of Medicine, Northeast Ohio Medical University, Rootstown, OH 44272, USA.
Chwen-Lih
CL
Chen
Department of Integrative Medical Sciences, College of Medicine, Northeast Ohio Medical University, Rootstown, OH 44272, USA.
Pei
P
Ren
Department of Integrative Medical Sciences, College of Medicine, Northeast Ohio Medical University, Rootstown, OH 44272, USA.
Giacinta
G
Guarini
Department of Integrative Medical Sciences, College of Medicine, Northeast Ohio Medical University, Rootstown, OH 44272, USA. Electronic address: ychen1@neomed.edu.
Yeong-Renn
YR
Chen
D000818:Animals; D018906:Antineoplastic Agents, Alkylating / Q000009:adverse effects* / Q000494:pharmacology; D054715:Cardiotoxins / Q000009:adverse effects / Q000494:pharmacology; D002330:Carmustine / Q000009:adverse effects* / Q000494:pharmacology; D002417:Cattle; D002460:Cell Line; D042967:Electron Transport Complex I / Q000737:chemistry / Q000378:metabolism*; D005230:Fatty Acids, Nonesterified / Q000378:metabolism; D005978:Glutathione / Q000378:metabolism*; D005980:Glutathione Reductase / Q000037:antagonists & inhibitors* / Q000378:metabolism; D006352:Heart Ventricles / Q000187:drug effects / Q000378:metabolism / Q000503:physiopathology; D007473:Ion Channels / Q000378:metabolism; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D008929:Mitochondria, Heart / Q000187:drug effects* / Q000378:metabolism; D024101:Mitochondrial Proteins / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects; D011499:Protein Processing, Post-Translational / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D013482:Superoxide Dismutase / Q000235:genetics / Q000378:metabolism; D000071247:Uncoupling Protein 3; D018487:Ventricular Dysfunction, Left / Q000139:chemically induced* / Q000378:metabolism / Q000503:physiopathology; D000099156:Superoxide Dismutase 2
D018906:Antineoplastic Agents, Alkylating; D054715:Cardiotoxins; D002330:Carmustine; D042967:Electron Transport Complex I; D005230:Fatty Acids, Nonesterified; D005978:Glutathione; D005980:Glutathione Reductase; D007473:Ion Channels; D024101:Mitochondrial Proteins; D013482:Superoxide Dismutase; D000071247:Uncoupling Protein 3; D000099156:Superoxide Dismutase 2; C000604393:Ucp3 protein, mouse; C000604394:Ucp3 protein, rat
Complex I; Glutathione reductase; Mitochondria; Oxidative stress; S-Glutathionylation; Systolic dysfunction