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Franco C, Canzoniero LMT. Zinc homeostasis and redox alterations in obesity. Front Endocrinol (Lausanne) 2024; 14:1273177. [PMID: 38260166 PMCID: PMC10800374 DOI: 10.3389/fendo.2023.1273177] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/05/2023] [Accepted: 12/18/2023] [Indexed: 01/24/2024] Open
Abstract
Impairment of both cellular zinc and redox homeostasis is a feature of several chronic diseases, including obesity. A significant two-way interaction exists between redox metabolism and the relatively redox-inert zinc ion. Redox metabolism critically influences zinc homeostasis and controls its cellular availability for various cellular functions by regulating zinc exchange from/to zinc-binding proteins. Zinc can regulate redox metabolism and exhibits multiple pro-antioxidant properties. On the other hand, even minor disturbances in zinc status and zinc homeostasis affect systemic and cellular redox homeostasis. At the cellular level, zinc homeostasis is regulated by a multi-layered machinery consisting of zinc-binding molecules, zinc sensors, and two selective families of zinc transporters, the Zinc Transporter (ZnT) and Zrt, Irt-like protein (ZIP). In the present review, we summarize the current state of knowledge on the role of the mutual interaction between zinc and redox homeostasis in physiology and pathophysiology, pointing to the role of zinc in the alterations responsible for redox stress in obesity. Since zinc transporters primarily control zinc homeostasis, we describe how changes in the expression and activity of these zinc-regulating proteins are associated with obesity.
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2
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Wu BB, Leung KT, Poon ENY. Mitochondrial-Targeted Therapy for Doxorubicin-Induced Cardiotoxicity. Int J Mol Sci 2022; 23:1912. [PMID: 35163838 PMCID: PMC8837080 DOI: 10.3390/ijms23031912] [Citation(s) in RCA: 40] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2021] [Revised: 01/27/2022] [Accepted: 02/01/2022] [Indexed: 01/27/2023] Open
Abstract
Anthracyclines, such as doxorubicin, are effective chemotherapeutic agents for the treatment of cancer, but their clinical use is associated with severe and potentially life-threatening cardiotoxicity. Despite decades of research, treatment options remain limited. The mitochondria is commonly considered to be the main target of doxorubicin and mitochondrial dysfunction is the hallmark of doxorubicin-induced cardiotoxicity. Here, we review the pathogenic mechanisms of doxorubicin-induced cardiotoxicity and present an update on cardioprotective strategies for this disorder. Specifically, we focus on strategies that can protect the mitochondria and cover different therapeutic modalities encompassing small molecules, post-transcriptional regulators, and mitochondrial transfer. We also discuss the shortcomings of existing models of doxorubicin-induced cardiotoxicity and explore advances in the use of human pluripotent stem cell derived cardiomyocytes as a platform to facilitate the identification of novel treatments against this disorder.
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Affiliation(s)
- Bin Bin Wu
- Centre for Cardiovascular Genomics and Medicine, Lui Che Woo Institute of Innovative Medicine, The Chinese University of Hong Kong (CUHK), Hong Kong SAR, China;
- Hong Kong Hub of Paediatric Excellence (HK HOPE), The Chinese University of Hong Kong (CUHK), Hong Kong SAR, China;
| | - Kam Tong Leung
- Hong Kong Hub of Paediatric Excellence (HK HOPE), The Chinese University of Hong Kong (CUHK), Hong Kong SAR, China;
- Department of Paediatrics, The Chinese University of Hong Kong (CUHK), Hong Kong SAR, China
| | - Ellen Ngar-Yun Poon
- Centre for Cardiovascular Genomics and Medicine, Lui Che Woo Institute of Innovative Medicine, The Chinese University of Hong Kong (CUHK), Hong Kong SAR, China;
- Hong Kong Hub of Paediatric Excellence (HK HOPE), The Chinese University of Hong Kong (CUHK), Hong Kong SAR, China;
- Department of Medicine and Therapeutics, The Chinese University of Hong Kong (CUHK), Hong Kong SAR, China
- School of Biomedical Sciences, The Chinese University of Hong Kong (CUHK), Hong Kong SAR, China
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3
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Bjørklund G, Tippairote T, Dadar M, Lizcano F, Aaseth J, Borisova O. The Roles of Dietary, Nutritional and Lifestyle Interventions in Adipose Tissue Adaptation and Obesity. Curr Med Chem 2021; 28:1683-1702. [PMID: 32368968 DOI: 10.2174/0929867327666200505090449] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2019] [Revised: 03/03/2020] [Accepted: 03/28/2020] [Indexed: 11/22/2022]
Abstract
The obesity and the associated non-communicable diseases (NCDs) are globally increasing in their prevalence. While the modern-day lifestyle required less ventilation of metabolic energy through muscular activities, this lifestyle transition also provided the unlimited accession to foods around the clock, which prolong the daily eating period of foods that contained high calorie and high glycemic load. These situations promote the high continuous flux of carbon substrate availability in mitochondria and induce the indecisive bioenergetic switches. The disrupted bioenergetic milieu increases the uncoupling respiration due to the excess flow of the substrate-derived reducing equivalents and reduces ubiquinones into the respiratory chain. The diversion of the uncoupling proton gradient through adipocyte thermogenesis will then alleviate the damaging effects of free radicals to mitochondria and other organelles. The adaptive induction of white adipose tissues (WAT) to beige adipose tissues (beAT) has shown beneficial effects on glucose oxidation, ROS protection and mitochondrial function preservation through the uncoupling protein 1 (UCP1)-independent thermogenesis of beAT. However, the maladaptive stage can eventually initiate with the persistent unhealthy lifestyles. Under this metabolic gridlock, the low oxygen and pro-inflammatory environments promote the adipose breakdown with sequential metabolic dysregulation, including insulin resistance, systemic inflammation and clinical NCDs progression. It is unlikely that a single intervention can reverse all these complex interactions. A comprehensive protocol that includes dietary, nutritional and all modifiable lifestyle interventions, can be the preferable choice to decelerate, stop, or reverse the NCDs pathophysiologic processes.
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Affiliation(s)
- Geir Bjørklund
- Council for Nutritional and Environmental Medicine (CONEM), Mo i Rana, Norway
| | - Torsak Tippairote
- Doctor of Philosophy Program in Nutrition, Faculty of Medicine Ramathibodi Hospital and Institute of Nutrition, Mahidol University, Bangkok, Thailand
| | - Maryam Dadar
- Razi Vaccine and Serum Research Institute, Agricultural Research, Education and Extension Organization (AREEO), Karaj, Iran
| | | | - Jan Aaseth
- Research Department, Innlandet Hospital Trust, Brumunddal, Norway
| | - Olga Borisova
- Odesa I. I. Mechnikov National University, Odessa, Ukraine
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4
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Miller HC, Louw R, Mereis M, Venter G, Boshoff JD, Mienie L, van Reenen M, Venter M, Lindeque JZ, Domínguez-Martínez A, Quintana A, van der Westhuizen FH. Metallothionein 1 Overexpression Does Not Protect Against Mitochondrial Disease Pathology in Ndufs4 Knockout Mice. Mol Neurobiol 2021; 58:243-262. [PMID: 32918239 DOI: 10.1007/s12035-020-02121-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Accepted: 09/05/2020] [Indexed: 01/24/2023]
Abstract
Mitochondrial diseases (MD), such as Leigh syndrome (LS), present with severe neurological and muscular phenotypes in patients, but have no known cure and limited treatment options. Based on their neuroprotective effects against other neurodegenerative diseases in vivo and their positive impact as an antioxidant against complex I deficiency in vitro, we investigated the potential protective effect of metallothioneins (MTs) in an Ndufs4 knockout mouse model (with a very similar phenotype to LS) crossed with an Mt1 overexpressing mouse model (TgMt1). Despite subtle reductions in the expression of neuroinflammatory markers GFAP and IBA1 in the vestibular nucleus and hippocampus, we found no improvement in survival, growth, locomotor activity, balance, or motor coordination in the Mt1 overexpressing Ndufs4-/- mice. Furthermore, at a cellular level, no differences were detected in the metabolomics profile or gene expression of selected one-carbon metabolism and oxidative stress genes, performed in the brain and quadriceps, nor in the ROS levels of macrophages derived from these mice. Considering these outcomes, we conclude that MT1, in general, does not protect against the impaired motor activity or improve survival in these complex I-deficient mice. The unexpected absence of increased oxidative stress and metabolic redox imbalance in this MD model may explain these observations. However, tissue-specific observations such as the mildly reduced inflammation in the hippocampus and vestibular nucleus, as well as differential MT1 expression in these tissues, may yet reveal a tissue- or cell-specific role for MTs in these mice.
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Affiliation(s)
- Hayley Christy Miller
- Human Metabolomics, Faculty of Natural and Agricultural Sciences, North-West University (Potchefstroom Campus), Private Bag X6001, Potchefstroom, South Africa
| | - Roan Louw
- Human Metabolomics, Faculty of Natural and Agricultural Sciences, North-West University (Potchefstroom Campus), Private Bag X6001, Potchefstroom, South Africa
| | - Michelle Mereis
- Human Metabolomics, Faculty of Natural and Agricultural Sciences, North-West University (Potchefstroom Campus), Private Bag X6001, Potchefstroom, South Africa
| | - Gerda Venter
- Human Metabolomics, Faculty of Natural and Agricultural Sciences, North-West University (Potchefstroom Campus), Private Bag X6001, Potchefstroom, South Africa
| | - John-Drew Boshoff
- Human Metabolomics, Faculty of Natural and Agricultural Sciences, North-West University (Potchefstroom Campus), Private Bag X6001, Potchefstroom, South Africa
| | - Liesel Mienie
- Human Metabolomics, Faculty of Natural and Agricultural Sciences, North-West University (Potchefstroom Campus), Private Bag X6001, Potchefstroom, South Africa
| | - Mari van Reenen
- Human Metabolomics, Faculty of Natural and Agricultural Sciences, North-West University (Potchefstroom Campus), Private Bag X6001, Potchefstroom, South Africa
| | - Marianne Venter
- Human Metabolomics, Faculty of Natural and Agricultural Sciences, North-West University (Potchefstroom Campus), Private Bag X6001, Potchefstroom, South Africa
| | - Jeremie Zander Lindeque
- Human Metabolomics, Faculty of Natural and Agricultural Sciences, North-West University (Potchefstroom Campus), Private Bag X6001, Potchefstroom, South Africa
| | - Adán Domínguez-Martínez
- Institut de Neurociències i Departament de Biologia Cel·lular, Fisiologia i Immunologia, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Albert Quintana
- Institut de Neurociències i Departament de Biologia Cel·lular, Fisiologia i Immunologia, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Francois Hendrikus van der Westhuizen
- Human Metabolomics, Faculty of Natural and Agricultural Sciences, North-West University (Potchefstroom Campus), Private Bag X6001, Potchefstroom, South Africa.
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5
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Critical Role of Zinc as Either an Antioxidant or a Prooxidant in Cellular Systems. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2018; 2018:9156285. [PMID: 29743987 PMCID: PMC5884210 DOI: 10.1155/2018/9156285] [Citation(s) in RCA: 183] [Impact Index Per Article: 30.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/26/2017] [Revised: 01/09/2018] [Accepted: 01/16/2018] [Indexed: 01/11/2023]
Abstract
Zinc is recognized as an essential trace metal required for human health; its deficiency is strongly associated with neuronal and immune system defects. Although zinc is a redox-inert metal, it functions as an antioxidant through the catalytic action of copper/zinc-superoxide dismutase, stabilization of membrane structure, protection of the protein sulfhydryl groups, and upregulation of the expression of metallothionein, which possesses a metal-binding capacity and also exhibits antioxidant functions. In addition, zinc suppresses anti-inflammatory responses that would otherwise augment oxidative stress. The actions of zinc are not straightforward owing to its numerous roles in biological systems. It has been shown that zinc deficiency and zinc excess cause cellular oxidative stress. To gain insights into the dual action of zinc, as either an antioxidant or a prooxidant, and the conditions under which each role is performed, the oxidative stresses that occur in zinc deficiency and zinc overload in conjunction with the intracellular regulation of free zinc are summarized. Additionally, the regulatory role of zinc in mitochondrial homeostasis and its impact on oxidative stress are briefly addressed.
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Chmielewska M, Symonowicz K, Pula B, Owczarek T, Podhorska-Okolow M, Ugorski M, Dziegiel P. Expression of metallothioneins I and II in kidney of doxorubicin-treated rats. ACTA ACUST UNITED AC 2015; 67:297-303. [DOI: 10.1016/j.etp.2015.01.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2014] [Revised: 12/12/2014] [Accepted: 01/29/2015] [Indexed: 10/24/2022]
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Guo J, Guo Q, Fang H, Lei L, Zhang T, Zhao J, Peng S. Cardioprotection against doxorubicin by metallothionein Is associated with preservation of mitochondrial biogenesis involving PGC-1α pathway. Eur J Pharmacol 2014; 737:117-24. [PMID: 24858368 DOI: 10.1016/j.ejphar.2014.05.017] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2014] [Revised: 05/08/2014] [Accepted: 05/14/2014] [Indexed: 12/23/2022]
Abstract
Metallothionein (MT) has been shown to inhibit cardiac oxidative stress and protect against the cardiotoxicity induced by doxorubicin (DOX), a potent and widely used chemotherapeutic agent. However, the mechanism of MT׳s protective action against DOX still remains obscure. Mitochondrial biogenesis impairment has been implicated to play an important role in the etiology and progression of DOX-induced cardiotoxicity. Increasing evidence indicates an intimate link between MT-mediated cardioprotection and mitochondrial biogenesis. This study was aimed to explore the possible contribution of mitochondrial biogenesis in MT׳s cardioprotective action against DOX. Adult male MT-I/II-null (MT(-/-)) and wild-type (MT(+/+)) mice were given a single dose of DOX intraperitoneally. Our results revealed that MT deficiency significantly sensitized mice to DOX-induced cardiac dysfunction, ultrastructural alterations, and mortality. DOX disrupted cardiac mitochondrial biogenesis indicated by mitochondrial DNA copy number and decreased mitochondrial number, and these effects were greater in MT(-/-) mice. Basal MT effectively protected against DOX-induced inhibition on the peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α), a key regulator of mitochondrial biogenesis, and its downstream factors including mitochondrial transcription factor A. Moreover, MT was found to preserve the protein expression of manganese superoxide dismutase, a transcriptional target of PGC-1α. in vitro study showed that MT absence augmented DOX-induced increase of mitochondrial superoxide production in primary cultured cardiomyocytes. These findings suggest that MT׳s cardioprotection against DOX is mediated, at least in part, by preservation of mitochondrial biogenesis involving PGC-1α pathway.
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Affiliation(s)
- Jiabin Guo
- Evaluation and Research Centre for Toxicology, Institute of Disease Control and Prevention, the Academy of Military Medical Sciences, Beijing, PR China
| | - Qian Guo
- Evaluation and Research Centre for Toxicology, Institute of Disease Control and Prevention, the Academy of Military Medical Sciences, Beijing, PR China
| | - Haiqing Fang
- Evaluation and Research Centre for Toxicology, Institute of Disease Control and Prevention, the Academy of Military Medical Sciences, Beijing, PR China
| | - Lei Lei
- Evaluation and Research Centre for Toxicology, Institute of Disease Control and Prevention, the Academy of Military Medical Sciences, Beijing, PR China
| | - Tingfen Zhang
- Evaluation and Research Centre for Toxicology, Institute of Disease Control and Prevention, the Academy of Military Medical Sciences, Beijing, PR China
| | - Jun Zhao
- Evaluation and Research Centre for Toxicology, Institute of Disease Control and Prevention, the Academy of Military Medical Sciences, Beijing, PR China
| | - Shuangqing Peng
- Evaluation and Research Centre for Toxicology, Institute of Disease Control and Prevention, the Academy of Military Medical Sciences, Beijing, PR China.
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8
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Shuai Y, Guo J, Dong Y, Zhong W, Xiao P, Zhou T, Zhang L, Peng S. Global gene expression profiles of MT knockout and wild-type mice in the condition of doxorubicin-induced cardiomyopathy. Toxicol Lett 2010; 200:77-87. [PMID: 21040762 DOI: 10.1016/j.toxlet.2010.10.017] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2010] [Revised: 10/22/2010] [Accepted: 10/25/2010] [Indexed: 10/18/2022]
Abstract
Increasing evidence from in vivo and in vitro studies has indicated that MT exerts protective effects against DOX-induced cardiotoxicity; however the underlying precise mechanisms still remain an enigma. Therefore, the present study was designed using MT knockout mice in concert with genomic approaches to explore the possible molecular and cellular mechanisms in terms of the genetic network changes. MT-I/II null (MT⁻/⁻) mice and corresponding wild-type mice (MT+/+) were administrated with a single dose of DOX (15 mg/kg, i.p.) or equal volume of saline. Animals were sacrificed on the 4th day after DOX administration and samples were collected for further analyses. Global gene expression profiles of cardiac mRNA from two genotype mice revealed that 381 characteristically MT-responsive genes were identified between MT+/+ mice and MT⁻/⁻ mice in response to DOX, including fos, ucp3, car3, atf3, map3k6, etc. Functional analysis implied MAPK signaling pathway, p53 signaling pathway, Jak-STAT signaling pathway, PPAR signaling pathway, Wnt signaling pathway, etc. might be involved to mediate the protection of DOX cardiomyopathy by MT. Results from the present study not only validated the previously reported possible mechanisms of MT protection against DOX toxicity, but also provided new clues into the molecular mechanisms involved in this process.
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Affiliation(s)
- Yi Shuai
- Evaluation and Research Center for Toxicology, Institute of Disease Control and Prevention, Academy of Military Medical Science, 20 Dongdajie Street, Fengtai District, Beijing 100071, PR China
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9
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Kang YJ. Antioxidant defense against anthracycline cardiotoxicity by metallothionein. Cardiovasc Toxicol 2007; 7:95-100. [PMID: 17652812 DOI: 10.1007/s12012-007-0007-3] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/1999] [Revised: 11/30/1999] [Accepted: 11/30/1999] [Indexed: 10/23/2022]
Abstract
Anthracycline cardiotoxicity is related to oxidative stress generated from the metabolism of anthracyclines in the heart. Studies using transgenic mice with high levels of antioxidants such as catalase or metallothionein (MT) specifically in the heart have demonstrated that elevation of cardiac antioxidant defense leads to intervention of anthracycline cardiotoxicity. MT protection against anthracycline-induced cardiac toxicity is related to its anti-apoptotic effect by inhibiting both p38-MAPK-mediated and mitochondrial cytochrome c-release-mediated apoptotic signaling. The anti-apoptotic effect of MT is closely related to its antioxidant action, which involves regulation of zinc homeostasis by the MT redox cycle. MT interferes with oxidant-mediated detrimental process through at least in part zinc release and zinc transfers directly from MT to acceptor proteins. In addition, MT posttranslationally modulates critical proteins involved in mitochondrial respiration and energy metabolism. All of these processes constitute the mechanisms by which MT protects from anthracycline cardiotoxicity.
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Affiliation(s)
- Y James Kang
- University of Louisville School of Medicine, 511 S. Floyd St., MDR530, Louisville, KY 40202, USA.
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Shuai Y, Guo JB, Peng SQ, Zhang LS, Guo J, Han G, Dong YS. Metallothionein protects against doxorubicin-induced cardiomyopathy through inhibition of superoxide generation and related nitrosative impairment. Toxicol Lett 2007; 170:66-74. [PMID: 17382496 DOI: 10.1016/j.toxlet.2007.02.010] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2006] [Revised: 02/13/2007] [Accepted: 02/15/2007] [Indexed: 10/23/2022]
Abstract
Metallothionein (MT) has been shown to be an effective protector against DOX-induced cardiomyopathy, however the involved precise mechanisms are still unknown. The present study was undertaken to clarify whether the inhibition of superoxide generation and related nitrosative damage were involved in the metallothionein attenuation of DOX-induced cardiac injury. MT-I/II null (MT-/-) mice and corresponding wild-type mice (MT+/+) were pretreated with either saline or zinc (300 micromol/kg, s.c., once a day for 2 days) prior to a single dose of DOX (15 mg/kg, i.p.) or equal volume of saline. Animals were sacrificed on the 4th day after DOX administration and samples were collected for further analyses. DOX caused remarkable cardiac damage in both MT+/+ and MT-/- mice as demonstrated by biochemical and histopathological alterations. Zinc pretreatment significantly increased the cardiac MT levels and therefore inhibited the cardiac toxic effects of DOX only in MT+/+ mice, but not in MT-/- mice. Furthermore, elevated formation of superoxide and peroxynitrite were obviously observed after DOX treatment, while these elevation were prevented by MT induction by zinc in MT+/+ mice, but not in MT-/- mice. These findings suggest that metallothionein induction by zinc exhibits protective effects on the cardiac toxicology of DOX, which might be mediated through the prevention of superoxide generation and related nitrosative impairment.
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Affiliation(s)
- Yi Shuai
- Department of Nutrition and Food Hygiene, School of Public Health, Sichuan University, Chengdu 610041, PR China
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11
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Li X, Chen H, Epstein PN. Metallothionein and catalase sensitize to diabetes in nonobese diabetic mice: reactive oxygen species may have a protective role in pancreatic beta-cells. Diabetes 2006; 55:1592-604. [PMID: 16731821 DOI: 10.2337/db05-1357] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
It is widely proposed that reactive oxygen species (ROS) contribute to beta-cell death in type 1 diabetes. We tested this in nonobese diabetic (NOD) mice using beta-cell-specific overexpression of three antioxidant proteins: metallothionein (MT), catalase (Cat), or manganese superoxide dismutase (MnSOD). Unexpectedly, the cytoplasmic antioxidants, MT and catalase, greatly accelerated diabetes after cyclophosphamide and accelerated spontaneous diabetes in male NOD mice. This occurred despite the fact that they reduced cytokine-induced ROS production and MT reduced streptozotocin diabetes in NOD mice. Accelerated diabetes onset coincided with increased beta-cell death but not with increased immune attack. Islets from MTNOD mice were more sensitive to cytokine injury. In vivo and in vitro studies indicated reduced activation of the Akt/pancreatic duodenal homeobox-1 survival pathway in MTNOD and CatNOD islets. Our study indicates that cytoplasmic ROS may have an important role for protecting the beta-cell from autoimmune destruction.
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Affiliation(s)
- Xiaoyan Li
- Department of Pharmacology and Toxicology, University of Louisville, 570 South Preston St., Baxter Research Building, Suite 304, Louisville, KY 40202, USA
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12
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Reinecke F, Levanets O, Olivier Y, Louw R, Semete B, Grobler A, Hidalgo J, Smeitink J, Olckers A, Van Der Westhuizen F. Metallothionein isoform 2A expression is inducible and protects against ROS-mediated cell death in rotenone-treated HeLa cells. Biochem J 2006; 395:405-15. [PMID: 16402917 PMCID: PMC1422768 DOI: 10.1042/bj20051253] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The role of MT (metallothionein) gene expression was investigated in rotenone-treated HeLa cells to induce a deficiency of NADH:ubiquinone oxidoreductase (complex I). Complex I deficiency leads to a diversity of cellular consequences, including production of ROS (reactive oxygen species) and apoptosis. HeLa cells were titrated with rotenone, resulting in dose-dependent decrease in complex I activity and elevated ROS production at activities lower than 33%. Expression of MT2A (MT isoform 2A), but not MT1A or MT1B RNA, was significantly inducible by rotenone (up to 7-fold), t-BHP (t-butyl hydroperoxide; 5-fold) and CdCl2 (50-fold), but not ZnCl2. Myxothiazol treatment did not elevate either ROS or MT2A levels, which supports a ROS-related mechanism for rotenone-induced MT2A expression. To evaluate the role of MT2A expression, MT2A and MT1B were overexpressed in HeLa cells and treated with rotenone. Compared with control and MT1B-overexpressing cells, ROS production was significantly lower and cell viability higher in MT2A-overexpressing HeLa cells when ROS production was enhanced by treatment with t-BHP. Mitochondrial membrane potential was noticeably less reduced in both MT-overexpressing cell lines. MT2A overexpression in rotenone-treated cells also significantly reduced or delayed apoptosis induction, as measured by caspase 3/7 activity and cytosolic nucleosome enrichment. We conclude that MT2A offers significant protection against the main death-causing consequences of rotenone-induced complex I deficiency in HeLa cells. Our results are in support of the protective role against oxidative stress ascribed to MTs and provide evidence that MT2A expression may be a beneficial downstream adaptive response in complex I-deficient cells.
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Affiliation(s)
- Fimmie Reinecke
- *Division of Biochemistry, School for Chemistry and Biochemistry, North-West University, Potchefstroom 2531, South Africa
| | - Oksana Levanets
- *Division of Biochemistry, School for Chemistry and Biochemistry, North-West University, Potchefstroom 2531, South Africa
- †Institute of Molecular Biology and Genetics of the National Academy of Sciences of Ukraine, Kiev 03143, Ukraine
| | - Yolanda Olivier
- *Division of Biochemistry, School for Chemistry and Biochemistry, North-West University, Potchefstroom 2531, South Africa
| | - Roan Louw
- *Division of Biochemistry, School for Chemistry and Biochemistry, North-West University, Potchefstroom 2531, South Africa
| | - Boitumelo Semete
- ‡Centre for Genome Research, North-West University, Pretoria 0020, South Africa
| | - Anne Grobler
- §School for Pharmacy, North-West University, Potchefstroom 2531, South Africa
| | - Juan Hidalgo
- ∥Institute of Neurosciences, Department of Cellular Biology, Physiology and Immunology, Faculty of Sciences, Autonomous University of Barcelona, Barcelona 08193, Spain
| | - Jan Smeitink
- ¶Nijmegen Centre for Mitochondrial Disorders, Radboud University Nijmegen Medical Centre, Nijmegen 6500, The Netherlands
| | - Antonel Olckers
- ‡Centre for Genome Research, North-West University, Pretoria 0020, South Africa
| | - Francois H. Van Der Westhuizen
- *Division of Biochemistry, School for Chemistry and Biochemistry, North-West University, Potchefstroom 2531, South Africa
- To whom correspondence should be addressed (email )
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Shen X, Zheng S, Metreveli NS, Epstein PN. Protection of cardiac mitochondria by overexpression of MnSOD reduces diabetic cardiomyopathy. Diabetes 2006; 55:798-805. [PMID: 16505246 DOI: 10.2337/diabetes.55.03.06.db05-1039] [Citation(s) in RCA: 277] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
We previously reported damage and elevated biogenesis in cardiac mitochondria of a type 1 diabetic mouse model and proposed that mitochondria are one of the major targets of oxidative stress. In this study, we targeted overexpression of the mitochondrial antioxidant protein manganese superoxide dismutase (MnSOD) to the heart to protect cardiac mitochondria from oxidative damage. Transgenic hearts had a 10- to 20-fold increase in superoxide dismutase (SOD) activity, and the transgenic SOD was located in mitochondria. The transgene caused a twofold increase in cardiac catalase activity. MnSOD transgenic mice demonstrated normal cardiac morphology, contractility, and mitochondria, and their cardiomyocytes were protected from exogenous oxidants. Crossing MnSOD transgenic mice with our type 1 model tested the benefit of eliminating mitochondrial reactive oxygen species. Overexpression of MnSOD improved respiration and normalized mass in diabetic mitochondria. MnSOD also protected the morphology of diabetic hearts and completely normalized contractility in diabetic cardiomyocytes. These results showed that elevating MnSOD provided extensive protection to diabetic mitochondria and provided overall protection to the diabetic heart.
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Affiliation(s)
- Xia Shen
- Department of Pathology, University of Washington, Seattle, USA
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14
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Futakawa N, Kondoh M, Ueda S, Higashimoto M, Takiguchi M, Suzuki S, Sato M. Involvement of Oxidative Stress in the Synthesis of Metallothionein Induced by Mitochondrial Inhibitors. Biol Pharm Bull 2006; 29:2016-20. [PMID: 17015943 DOI: 10.1248/bpb.29.2016] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We previously reported that synthesis of metallothionein (MT) was induced by mitochondrial inhibitors such as 2,4-dinitrophenol (DNP) or antimycin A (Kondoh et al., 2001), which are potent inhibitors of mitochondrial respiration. Although the inhibitors are known to be radical generators in mitochondria, the involvement of oxidative stress in the synthesis of MT induced by mitochondrial inhibitors and the biological functions of MT remain obscure. In this study, therefore, we examined the involvement of oxidative stress in MT synthesis induced by mitochondrial inhibitors and the biological functions of MT. In cultured mouse fibroblast cells, the addition of DNP increased both MT concentration and MT mRNA level. Administration of DNP to L-buthionine-SR-sulfoximine (BSO)-pretreated mice increased hepatic lipid peroxidation and induction of MT synthesis. In addition, vitamin E prevented induction of MT synthesis as well as lipid peroxidation in the liver of mice caused by administration of DNP. Administration of mitochondrial inhibitor to mice elevated the levels of lipid peroxidation in the liver and mitochondria, and MT in the liver, indicating the generation of mitochondrial oxidative stress. These data suggest that the induction of MT synthesis by mitochondrial inhibitors is correlated with generation of oxidative stress in mitochondria. Furthermore, the level of DNP-induced alanine aminotransferase (ALT) activity, reflecting hepatic damage, was greater in MT-null mice than in wild-type mice, and intracellular accumulation of reactive oxygen species (ROS) caused by the action of mitochondrial inhibitors was greater in MT-null fibloblast cells than in wild-type cells. The results suggest that MT plays a role as a radical scavenger of intracellular ROS produced in mitochondria. Taken together, the results suggest that mitochondrial oxidative stress induces the synthesis of MT, which may contribute to regulation of mitochondrial ROS production.
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Affiliation(s)
- Naoki Futakawa
- Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Yamashiro-cho, Tokushima, Japan
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15
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Merten KE, Feng W, Zhang L, Pierce W, Cai J, Klein JB, Kang YJ. Modulation of cytochrome C oxidase-va is possibly involved in metallothionein protection from doxorubicin cardiotoxicity. J Pharmacol Exp Ther 2005; 315:1314-9. [PMID: 16144979 DOI: 10.1124/jpet.105.089763] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Previous studies using a cardiac-specific metallothionein (MT)-overexpressing transgenic (MT-TG) mouse model have demonstrated that MT protects from doxorubicin (DOX)-induced oxidative heart injury. The molecular mechanisms that underlie this cardioprotection, however, have yet to be defined. In the present study, we tested the hypothesis that MT overexpression activates cytoprotective mechanisms, leading to cardiac protection from DOX toxicity. MT-TG mice and nontransgenic wild-type (WT) controls were treated i.p. with DOX at a single dose of 20 mg/kg and sacrificed on the third day after the treatment. An expression proteomic analysis involving two-dimensional gel electrophoresis and matrix-assisted laser desorption ionization time-of-flight mass spectrometry was used to identify MT-induced changes in cytoprotection-related proteins. We identified 18 proteins that were modified by DOX treatment in the heart. These proteins included those involved in cellular antioxidant defense, enzymes of the mitochondrial electron transport chain, enzymes involved in beta-oxidation of fatty acids and glycolysis, and proteins involved in regulation of cardiac muscle contraction. However, the most dominant modification by MT is the cytochrome c oxidase subunit Va (CCO-Va). In response to DOX treatment, a specific isoform of CCO-Va was enhanced in the MT-TG but not in the WT mouse hearts. Because CCO-Va is a critical component in the mitochondrial electron transport chain, the results suggest that the cardioprotective effect of MT may be related to an increased expression or a differential modification of CCO-Va.
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Affiliation(s)
- Kevyn E Merten
- Department of Pharmacology and Toxicology, University of Louisville School of Medicine, 511 South Floyd Street, MDR 530, Louisville, KY 40202, USA
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16
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Cai L, Wang J, Li Y, Sun X, Wang L, Zhou Z, Kang YJ. Inhibition of superoxide generation and associated nitrosative damage is involved in metallothionein prevention of diabetic cardiomyopathy. Diabetes 2005; 54:1829-37. [PMID: 15919806 DOI: 10.2337/diabetes.54.6.1829] [Citation(s) in RCA: 159] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The mechanisms of metallothionein prevention of diabetic cardiomyopathy are largely unknown. The present study was performed to test whether inhibition of nitrosative damage is involved in metallothionein prevention of diabetic cardiomyopathy. Cardiac-specific metallothionein-overexpressing transgenic (MT-TG) mice and wild-type littermate controls were treated with streptozotocin (STZ) by a single intraperitoneal injection, and both developed diabetes. However, the development of diabetic cardiomyopathy, revealed by histopathological and ultrastructural examination, serum creatine phosphokinase, and cardiac hemodynamic analysis, was significantly observed only in the wild-type, but not in MT-TG, diabetic mice 2 weeks and 6 months after STZ treatment. Formations of superoxide and 3-nitrotyrosine (3-NT), a marker for peroxynitrite-induced protein damage, were detected only in the heart of wild-type diabetic mice. Furthermore, primary cultures of cardiomyocytes from wild-type and MT-TG mice were exposed to lipopolysaccharide/tumor necrosis factor-alpha for generating intracellular peroxynitrite. Increases in 3-NT formation and cytotoxicity were observed in wild-type, but not in MT-TG, cardiomyocytes. Either urate, a peroxynitrite-specific scavenger, or Mn(111) tetrakis 1-methyl 4-pyridyl porphyrin pentachloride (MnTMPyP), a superoxide dismutase mimic, significantly inhibited the formation of 3-NT along with a significant prevention of cytotoxicity. These results thus suggest that metallothionein prevention of diabetic cardiomyopathy is mediated, at least in part, by suppression of superoxide generation and associated nitrosative damage.
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Affiliation(s)
- Lu Cai
- Department of Medicine, University of Louisville School of Medicine, 511 South Floyd St., MDR 533, Louisville, KY 40202, USA.
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17
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Fadillioglu E, Yilmaz HR, Erdogan H, Sogut S. The activities of tissue xanthine oxidase and adenosine deaminase and the levels of hydroxyproline and nitric oxide in rat hearts subjected to doxorubicin: protective effect of erdosteine. Toxicology 2003; 191:153-8. [PMID: 12965118 DOI: 10.1016/s0300-483x(03)00258-0] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The aim of this experimental study was to investigate the effects of erdosteine, an antioxidant agent, on doxorubicin (DXR)-induced cardio-toxicity through nitric oxide (NO) levels, collagen synthesis, xanthine oxidase (XO) and adenosine deaminase (ADA) activities in rats. Rats were treated with erdosteine (10 mg/kg b.wt. per day, orally) or saline starting 2 days before administrating a single dose of DXR (20 mg/kg i.p.) or saline. At the 10th day of the DXR administration, hearts were removed under anesthesia for biochemical measurements. Enzyme activities as well as OH-proline and NO levels were found to be significantly increased in DXR group compared with the control group. All of the parameters studied except ADA activity were decreased significantly approximating to the control levels upon erdosteine administration. In conclusion, erdosteine seems to be an alternative agent for protection of cardiac tissue against DXR-induced cardio-toxicity through its regulatory effect on XO activity and NO level.
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Affiliation(s)
- Ersin Fadillioglu
- Department of Physiology, Faculty of Medicine, Inonu University, TR 44069, Malatya, Turkey.
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Sun X, Kang YJ. Prior increase in metallothionein levels is required to prevent doxorubicin cardiotoxicity. Exp Biol Med (Maywood) 2002; 227:652-7. [PMID: 12192109 DOI: 10.1177/153537020222700815] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Many studies have shown that metallothionein (MT) can be increased significantly by different oxidative insults in multiple organ systems. However, the increase in MT production often fails to protect against oxidative tissue injury. On the other hand, recent studies using a cardiac-specific, MT-overexpressing, transgenic mouse model have shown that MT protects against oxidative heart injury. Thus, the present study was undertaken to test the hypothesis that prior increase in MT levels is required to prevent oxidative injury. Oxidative heart injury was induced by doxorubicin (DOX), an important anticancer drug that causes severe cardiotoxicity through oxidative stress. Cardiac-specific, MT-overexpressing, transgenic mice and wild-type (WT) FVB mice were treated with DOX at 20 mg/kg. Four days after the treatment, MT concentrations were markedly elevated in the WT mouse heart. The elevated MT concentrations were comparable with those found in the transgenic mouse heart, which did not show further MT elevation in response to DOX challenge. Severe oxidative injury occurred in the heart of WT mice, including myocardial lipid peroxidation, morphological changes as examined by electron microscopy, high levels of serum creatine kinase activity, and decreased total glutathione concentrations in the heart. However, all of these pathological changes were significantly inhibited in the MT-transgenic mice. Therefore, this study demonstrates that there is a correlation between MT induction and oxidative stress in the DOX-treated mouse heart. However, MT can protect the heart from oxidative injury only if it is present prior to induction of oxidative stress.
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Affiliation(s)
- Xiuhua Sun
- Department of Medicine, University of Louisville School of Medicine, and Jewish Hospital Heart and Lung Institute, Louisville, Kentucky 40202, USA
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Zhou Z, Sun X, Lambert JC, Saari JT, Kang YJ. Metallothionein-independent zinc protection from alcoholic liver injury. THE AMERICAN JOURNAL OF PATHOLOGY 2002; 160:2267-74. [PMID: 12057929 PMCID: PMC1850821 DOI: 10.1016/s0002-9440(10)61174-1] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 03/18/2002] [Indexed: 12/19/2022]
Abstract
Previous studies using metallothionein (MT)-overexpressing transgenic mice have demonstrated that MT protects the liver from oxidative injury induced by alcohol. The mechanism of action of MT is unknown. Because MT primarily binds to zinc under physiological conditions and releases zinc under oxidative stress and zinc is an antioxidant element, it is likely that zinc mediates the protective action of MT. The present study was undertaken to determine the distinct role of zinc in hepatic protection from alcoholic injury. MT I/II-knockout (MT-KO) mice along with their wild-type controls were treated with three gastric doses of ethanol at 5 g/kg at 12-hour intervals. Zinc sulfate was injected intraperitoneally in a dosage of 5 mg/kg/day for 3 days before ethanol treatment. MT concentrations in MT-KO mice were very low and zinc concentrations in MT-KO mice were lower than in wild-type mice. Zinc treatment significantly elevated hepatic MT concentrations only in wild-type mice and increased zinc concentrations in both MT-KO and wild-type mice. Ethanol treatment caused degenerative morphological changes and necrotic appearance in the livers of MT-KO mice. Microvesicular steatosis was the only ethanol-induced change in the liver of wild-type mice. Ethanol treatment decreased hepatic glutathione concentrations and increased hepatic lipid peroxidation, and the concentrations of lipid peroxide products in the wild-type mice were lower than in the MT-KO mice. All of these alcohol-induced toxic responses were significantly suppressed by zinc treatment in both MT-KO and wild-type mouse livers. These results demonstrate that zinc, independent of MT, plays an important role in protection from alcoholic liver injury. However, MT is required to maintain high levels of zinc in the liver, suggesting that the protective action of MT in the liver is likely mediated by zinc.
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Affiliation(s)
- Zhanxiang Zhou
- Department of Medicine, University of Louisville School of Medicine, Louisville, Kentucky 40202, USA
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Mihm MJ, Yu F, Weinstein DM, Reiser PJ, Bauer JA. Intracellular distribution of peroxynitrite during doxorubicin cardiomyopathy: evidence for selective impairment of myofibrillar creatine kinase. Br J Pharmacol 2002; 135:581-8. [PMID: 11834605 PMCID: PMC1573167 DOI: 10.1038/sj.bjp.0704495] [Citation(s) in RCA: 83] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Cardiac peroxynitrite and protein nitration are increased during doxorubicin cardiotoxicity, but the intracellular targets and functional consequences have not been defined. We investigated the intracellular distribution of protein nitration during doxorubicin cardiotoxicity in mice. Following in vivo cardiac function assessments by echocardiography, cardiac tissues were prepared for immunohistochemistry and electron microscopy 5 days after doxorubicin (20 mg kg(-1)) or vehicle control. Increased cardiac 3-nitrotyrosine was observed using light microscopy in doxorubicin treated animals. Immunogold electron microscopy (55,000x) revealed increased myofibrillar and mitochondrial 3-nitrotyrosine levels following doxorubicin, but cellular 3-nitrotyrosine density was 2 fold higher in myofibrils. We therefore investigated the actions of peroxynitrite on intact cardiac contractile apparatus. Skinned ventricular trabeculae were exposed to physiologically relevant peroxynitrite concentrations (50 or 300 nM) for 1 h, then Ca(2+) induced contractile responses were measured in the presence of ATP (4 mM) or phosphocreatine (12 mM) as high energy phosphate supplier. ATP maximal force generation was unaltered after 50 nM peroxynitrite, but phosphocreatine/ATP response was reduced (0.99+/-0.63 vs 1.59+/-0.11), suggesting selective inactivation of myofibrillar creatine kinase (MM-CK). Reduction of ATP maximal force was observed at 300 nM peroxynitrite and phosphocreatine/ATP response was further reduced (0.64+/-0.30). Western blotting showed concentration dependent nitration of MM-CK in treated trabeculae. Similarly, cardiac tissues from doxorubicin treated mice demonstrated increased nitration and inactivation of MM-CK compared to controls. These results demonstrate that peroxynitrite-related protein nitration are mechanistic events in doxorubicin cardiomyopathy and that the cardiac myofibril is an important oxidative target in this setting. Furthermore, MM-CK may be a uniquely vulnerable target to peroxynitrite in vivo.
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Affiliation(s)
- Michael J Mihm
- Division of Pharmacology, College of Pharmacy and OSU Heart & Lung Research Institute, Columbus, Ohio, U.S.A
| | - Fushun Yu
- Division of Pharmacology, College of Pharmacy and OSU Heart & Lung Research Institute, Columbus, Ohio, U.S.A
| | - David M Weinstein
- Division of Pharmacology, College of Pharmacy and OSU Heart & Lung Research Institute, Columbus, Ohio, U.S.A
| | - Peter J Reiser
- College of Dentistry, Ohio State University, Columbus, OH 43210, U.S.A
| | - John Anthony Bauer
- Division of Pharmacology, College of Pharmacy and OSU Heart & Lung Research Institute, Columbus, Ohio, U.S.A
- Author for correspondence:
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Liang Q, Carlson EC, Donthi RV, Kralik PM, Shen X, Epstein PN. Overexpression of metallothionein reduces diabetic cardiomyopathy. Diabetes 2002; 51:174-81. [PMID: 11756338 DOI: 10.2337/diabetes.51.1.174] [Citation(s) in RCA: 143] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Many diabetic patients suffer from cardiomyopathy, even in the absence of vascular disease. This diabetic cardiomyopathy predisposes patients to heart failure and mortality from myocardial infarction. Evidence from animal models suggests that reactive oxygen species play an important role in the development of diabetic cardiomyopathy. Our laboratory previously developed a transgenic mouse model with targeted overexpression of the antioxidant protein metallothionein (MT) in the heart. In this study we used MT-transgenic mice to test whether an antioxidant protein can reduce cardiomyopathy in the OVE26 transgenic model of diabetes. OVE26 diabetic mice exhibited cardiomyopathy characterized by significantly altered mRNA expression, clear morphological abnormalities, and reduced contractility under ischemic conditions. Diabetic hearts appeared to be under oxidative stress because they had significantly elevated oxidized glutathione (GSSG). Diabetic mice with elevated cardiac MT (called OVE26MT mice) were obtained by crossing OVE26 transgenic mice with MT transgenic mice. Hyperglycemia in OVE26MT mice was indistinguishable from hyperglycemia in OVE26 mice. Despite this, the MT transgene significantly reduced cardiomyopathy in diabetic mice: OVE26MT hearts showed more normal levels of mRNA and GSSG. Typically, OVE26MT hearts were found to be morphologically normal, and elevated MT improved the impaired ischemic contractility seen in diabetic hearts. These results demonstrate that cardiomyocyte-specific expression of an antioxidant protein reduces damage to the diabetic heart.
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Affiliation(s)
- Qiangrong Liang
- Division of Molecular Cardiovascular Biology, University of Cincinnati, Ohio, USA
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22
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Sato M, Kondoh M. Recent studies on metallothionein: protection against toxicity of heavy metals and oxygen free radicals. TOHOKU J EXP MED 2002; 196:9-22. [PMID: 12498322 DOI: 10.1620/tjem.196.9] [Citation(s) in RCA: 194] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Metallothionein (MT) is a ubiquitous, cysteine-rich, metal-binding protein. MT synthesis is induced by various stimuli such as cadmium, mercury, zinc, oxidative stress, glucocorticoid, and anticancer agents. Recently, transgenic mice with loss-of-function mutations in the MT-I/-II genes were established. It has been assumed that MT plays a role in the detoxification of heavy metals. In recent studies using MT-null mice, the ability of MT to protect against cadmium-induced renal, liver and bone injuries has been confirmed. Moreover, MT is also capable of scavenging oxygen free radicals. MT is involved in the protection of tissues against various forms of oxidative injury, including radiation, lipid peroxidation, oxidative stress caused by anticancer drugs, and conditions of hyperoxia. However, MT still lacks an established biological function. Unexpectedly, the MT-null mice were apparently in good health, and the critical biological roles of MT have been questioned. MT seems to be a protective protein produced in response to a variety of stresses. Here, current studies on the protective roles of MT against toxicity of heavy metals and reactive oxygen species are reviewed, and the putative biological functions of MT are discussed.
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Affiliation(s)
- Masao Sato
- Department of Public Health, Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Tokushima 770-8514, Japan.
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Chen H, Carlson EC, Pellet L, Moritz JT, Epstein PN. Overexpression of metallothionein in pancreatic beta-cells reduces streptozotocin-induced DNA damage and diabetes. Diabetes 2001; 50:2040-6. [PMID: 11522669 DOI: 10.2337/diabetes.50.9.2040] [Citation(s) in RCA: 106] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The release of reactive oxygen species (ROS) has been proposed as a cause of streptozotocin (STZ)-induced beta-cell damage. This initiates a destructive cascade, consisting of DNA damage, excess activation of the DNA repair enzyme poly(ADP-ribose) polymerase, and depletion of cellular NAD+. Metallothionein (MT) is an inducible antioxidant protein that has been shown to protect DNA from chemical damage in several cell types. Therefore, we examined whether overexpression of MT could protect beta-cell DNA and thereby prevent STZ-induced diabetes. Two lines of transgenic mice were produced with up to a 30-fold elevation in beta-cell MT. Cultured islets from control mice and MT transgenic mice were exposed to STZ. MT was found to decrease STZ-induced islet disruption, DNA breakage, and depletion of NAD+. To assess in vivo protection, transgenic and control mice were injected with STZ. Transgenic mice had significantly reduced hyperglycemia. Ultrastructural examination of islets from STZ-treated mice showed that MT prevented degranulation and cell death. These results demonstrate that MT can reduce diabetes and confirm the DNA damage mechanism of STZ-induced beta-cell death.
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Affiliation(s)
- H Chen
- Department of Pediatrics, University of Louisville, Louisville, Kentucky 40202, USA
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Wang GW, Zhou Z, Klein JB, Kang YJ. Inhibition of hypoxia/reoxygenation-induced apoptosis in metallothionein-overexpressing cardiomyocytes. Am J Physiol Heart Circ Physiol 2001; 280:H2292-9. [PMID: 11299233 DOI: 10.1152/ajpheart.2001.280.5.h2292] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
To study possible mechanisms for metallothionein (MT) inhibition of ischemia-reperfusion-induced myocardial injury, cardiomyocytes isolated from MT-overexpressing transgenic neonatal mouse hearts and nontransgenic controls were subjected to 4 h of hypoxia (5% CO2-95% N2, glucose-free modified Tyrode's solution) followed by 1 h of reoxygenation in MEM + 20% fetal bovine serum (FBS) (5% CO2-95% air), and cytochrome c-mediated caspase-3 activation apoptotic pathway was determined. Hypoxia/reoxygenation-induced apoptosis was significantly suppressed in MT-overexpressing cardiomyocytes, as measured by both terminal deoxynucleotidyl transferase-mediated deoxyuridine 5-triphosphate nick-end labeling and annexin V-FITC binding. In association with apoptosis, mitochondrial cytochrome c release, as determined by Western blot, was observed to occur in nontransgenic cardiomyocytes. Correspondingly, caspase-3 was activated as determined by laser confocal microscopic examination with the use of FITC-conjugated antibody against active caspase-3 and by enzymatic assay. The activation of this apoptotic pathway was significantly inhibited in MT-overexpressing cells, as evidenced by both suppression of cytochrome c release and inhibition of caspase-3 activation. The results demonstrate that MT suppresses hypoxia/reoxygenation-induced cardiomyocyte apoptosis through, at least in part, inhibition of cytochrome c-mediated caspase-3 activation.
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Affiliation(s)
- G W Wang
- Department of Medicine, University of Louisville, Louisville, Kentucky 40292, USA
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Ye B, Maret W, Vallee BL. Zinc metallothionein imported into liver mitochondria modulates respiration. Proc Natl Acad Sci U S A 2001; 98:2317-22. [PMID: 11226237 PMCID: PMC30136 DOI: 10.1073/pnas.041619198] [Citation(s) in RCA: 184] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Metallothionein (MT) localizes in the intermembrane space of liver mitochondria as well as in the cytosol and nucleus. Incubation of intact liver mitochondria with physiological, micromolar concentrations of MT leads to the import of MT into the mitochondria where it inhibits respiration. This activity is caused by the N-terminal beta-domain of MT; in this system, the isolated C-terminal alpha-domain is inactive. Free zinc inhibits respiration at concentrations commensurate with the zinc content of either MT or the isolated beta-domain, indicating that MT inhibition involves zinc delivery to mitochondria. Respiratory inhibition of uncoupled mitochondria identifies the electron transfer chain as the primary site of inhibition. The apoform of MT, thionein, is an endogenous chelating agent and activates zinc-inhibited respiration with a 1:1 stoichiometry ([zinc binding sites]/[zinc]). Carbamoylation of the lysines of MT significantly attenuates the inhibitory effect, suggesting that these residues are critical for the passage of MT through the outer mitochondrial membrane. Such an import pathway has been proposed for other proteins that also lack a mitochondrial targeting sequence, e.g., apocytochrome c, and possibly Cox17, a mitochondrial copper chaperone that is the only protein known so far to exhibit significant primary sequence homology to MT. The presence and respiratory inhibition of MT in liver, but not heart, mitochondria suggest a hitherto unknown biological modulating activity of MT in cellular respiration and energy metabolism in a tissue-specific manner.
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Affiliation(s)
- B Ye
- Center for Biochemical and Biophysical Sciences and Medicine, Harvard Medical School, Seeley G. Mudd Building, 250 Longwood Avenue, Boston, MA 02115, USA
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