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Singh AK, Pomorski A, Wu S, Peris-Díaz MD, Czepczyńska-Krężel H, Krężel A. The connection of α- and β-domains in mammalian metallothionein-2 differentiates Zn(II) binding affinities, affects folding, and determines zinc buffering properties. Metallomics 2023; 15:mfad029. [PMID: 37147085 PMCID: PMC10243857 DOI: 10.1093/mtomcs/mfad029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2023] [Accepted: 05/03/2023] [Indexed: 05/07/2023]
Abstract
Mammalian metallothioneins (MTs) are small Cys-rich proteins involved in Zn(II) and Cu(I) homeostasis. They bind seven Zn(II) ions in two distinct β- and α-domains, forming Zn3Cys9 and Zn4Cys11 clusters, respectively. After six decades of research, their role in cellular buffering of Zn(II) ions has begun to be understood recently. This is because of different affinities of bound ions and the proteins' coexistence in variously Zn(II)-loaded Zn4-7MT species in the cell. To date, it has remained unclear how these mechanisms of action occur and how the affinities are differentiated despite the Zn(S-Cys)4 coordination environment being the same. Here, we dissect the molecular basis of these phenomena by using several MT2 mutants, hybrid protein, and isolated domains. Through a combination of spectroscopic and stability studies, thiol(ate) reactivity, and steered molecular dynamics, we demonstrate that both protein folding and thermodynamics of Zn(II) ion (un)binding significantly differ between isolated domains and the whole protein. Close proximity reduces the degrees of freedom of separated domains, making them less dynamic. It is caused by the formation of intra- and interdomain electrostatic interactions. The energetic consequence of domains connection has a critical impact on the role of MTs in the cellular environment, where they function not only as a zinc sponge but also as a zinc buffering system keeping free Zn(II) in the right concentrations. Any change of that subtle system affects the folding mechanism, zinc site stabilities, and cellular zinc buffer components.
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Affiliation(s)
- Avinash Kumar Singh
- Department of Chemical Biology, Faculty of Biotechnology, University of Wrocław, Joliot-Curie 14a, 50-383 Wrocław, Poland
| | - Adam Pomorski
- Department of Chemical Biology, Faculty of Biotechnology, University of Wrocław, Joliot-Curie 14a, 50-383 Wrocław, Poland
| | - Sylwia Wu
- Department of Chemical Biology, Faculty of Biotechnology, University of Wrocław, Joliot-Curie 14a, 50-383 Wrocław, Poland
| | - Manuel D Peris-Díaz
- Department of Chemical Biology, Faculty of Biotechnology, University of Wrocław, Joliot-Curie 14a, 50-383 Wrocław, Poland
| | - Hanna Czepczyńska-Krężel
- Department of Chemical Biology, Faculty of Biotechnology, University of Wrocław, Joliot-Curie 14a, 50-383 Wrocław, Poland
| | - Artur Krężel
- Department of Chemical Biology, Faculty of Biotechnology, University of Wrocław, Joliot-Curie 14a, 50-383 Wrocław, Poland
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2
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Abstract
Zn2+ ions are essential in many physiological processes, including enzyme catalysis, protein structural stabilization, and the regulation of many proteins. The affinities of proteins for Zn2+ ions span several orders of magnitude, with catalytic Zn2+ ions generally held more tightly than structural or regulatory ones. Metal carrier proteins, most of which are not specific for Zn2+, bind these ions with a broad range of affinities that overlap those of catalytic, structural, and regulatory Zn2+ ions and are thought to be responsible for distributing the metal through most cells, tissues, and fluid compartments. While little is known about how many proteins obtain or release these ions, there is now considerable experimental evidence suggesting that metal carrier proteins may be responsible for transferring metals to and from some Zn2+-dependent proteins, thus serving as a major regulatory factor for them. In this review, the biological roles of Zn2+ and structures of Zn2+ binding sites are examined, and experimental evidence demonstrating the direct participation of metal carrier proteins in enzyme regulation is discussed. Mechanisms of metal ion transfer are also offered, and the potential physiological significance of this phenomenon is explored.
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Abstract
The functions, purposes, and roles of metallothioneins have been the subject of speculations since the discovery of the protein over 60 years ago. This article guides through the history of investigations and resolves multiple contentions by providing new interpretations of the structure-stability-function relationship. It challenges the dogma that the biologically relevant structure of the mammalian proteins is only the one determined by X-ray diffraction and NMR spectroscopy. The terms metallothionein and thionein are ambiguous and insufficient to understand biological function. The proteins need to be seen in their biological context, which limits and defines the chemistry possible. They exist in multiple forms with different degrees of metalation and types of metal ions. The homoleptic thiolate coordination of mammalian metallothioneins is important for their molecular mechanism. It endows the proteins with redox activity and a specific pH dependence of their metal affinities. The proteins, therefore, also exist in different redox states of the sulfur donor ligands. Their coordination dynamics allows a vast conformational landscape for interactions with other proteins and ligands. Many fundamental signal transduction pathways regulate the expression of the dozen of human metallothionein genes. Recent advances in understanding the control of cellular zinc and copper homeostasis are the foundation for suggesting that mammalian metallothioneins provide a highly dynamic, regulated, and uniquely biological metal buffer to control the availability, fluctuations, and signaling transients of the most competitive Zn(II) and Cu(I) ions in cellular space and time.
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Affiliation(s)
- Artur Krężel
- Department of Chemical Biology, Faculty of Biotechnology, University of Wrocław, Wrocław 50-383, Poland
| | - Wolfgang Maret
- Departments of Biochemistry and Nutritional Sciences, School of Life Course Sciences, Faculty of Life Sciences and Medicine, King's College London, London SE1 9NH, U.K
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Foster AW, Young TR, Chivers PT, Robinson NJ. Protein metalation in biology. Curr Opin Chem Biol 2021; 66:102095. [PMID: 34763208 PMCID: PMC8867077 DOI: 10.1016/j.cbpa.2021.102095] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Revised: 09/08/2021] [Accepted: 10/04/2021] [Indexed: 12/11/2022]
Abstract
Inorganic metals supplement the chemical repertoire of organic molecules, especially proteins. This requires the correct metals to associate with proteins at metalation. Protein mismetalation typically occurs when excesses of unbound metals compete for a binding site ex vivo. However, in biology, excesses of metal-binding sites typically compete for limiting amounts of exchangeable metals. Here, we summarise mechanisms of metal homeostasis that sustain optimal metal availabilities in biology. We describe recent progress to understand metalation by comparing the strength of metal binding to a protein versus the strength of binding to competing sites inside cells.
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Affiliation(s)
- Andrew W Foster
- Department of Biosciences, Durham University, Durham, DH1 3LE, UK; Department of Chemistry, Durham University, Durham, DH1 3LE, UK
| | - Tessa R Young
- Department of Biosciences, Durham University, Durham, DH1 3LE, UK; Department of Chemistry, Durham University, Durham, DH1 3LE, UK
| | - Peter T Chivers
- Department of Biosciences, Durham University, Durham, DH1 3LE, UK; Department of Chemistry, Durham University, Durham, DH1 3LE, UK
| | - Nigel J Robinson
- Department of Biosciences, Durham University, Durham, DH1 3LE, UK; Department of Chemistry, Durham University, Durham, DH1 3LE, UK.
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5
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Álvarez-Barrios A, Álvarez L, García M, Artime E, Pereiro R, González-Iglesias H. Antioxidant Defenses in the Human Eye: A Focus on Metallothioneins. Antioxidants (Basel) 2021; 10:89. [PMID: 33440661 PMCID: PMC7826537 DOI: 10.3390/antiox10010089] [Citation(s) in RCA: 38] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Revised: 01/03/2021] [Accepted: 01/04/2021] [Indexed: 12/12/2022] Open
Abstract
The human eye, the highly specialized organ of vision, is greatly influenced by oxidants of endogenous and exogenous origin. Oxidative stress affects all structures of the human eye with special emphasis on the ocular surface, the lens, the retina and its retinal pigment epithelium, which are considered natural barriers of antioxidant protection, contributing to the onset and/or progression of eye diseases. These ocular structures contain a complex antioxidant defense system slightly different along the eye depending on cell tissue. In addition to widely studied enzymatic antioxidants, including superoxide dismutase, glutathione peroxidase, catalase, peroxiredoxins and selenoproteins, inter alia, metallothioneins (MTs) are considered antioxidant proteins of growing interest with further cell-mediated functions. This family of cysteine rich and low molecular mass proteins captures and neutralizes free radicals in a redox-dependent mechanism involving zinc binding and release. The state of the art of MTs, including the isoforms classification, the main functions described to date, the Zn-MT redox cycle as antioxidant defense system, and the antioxidant activity of Zn-MTs in the ocular surface, lens, retina and its retinal pigment epithelium, dependent on the number of occupied zinc-binding sites, will be comprehensively reviewed.
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Affiliation(s)
- Ana Álvarez-Barrios
- Instituto Universitario Fernández-Vega (Fundación de Investigación Oftalmológica, Universidad de Oviedo), 33012 Oviedo, Spain; (A.Á.-B.); (L.Á.); (M.G.); (E.A.); (R.P.)
- Department of Physical and Analytical Chemistry, Faculty of Chemistry, University of Oviedo, Julián Clavería, 8, 33006 Oviedo, Spain
| | - Lydia Álvarez
- Instituto Universitario Fernández-Vega (Fundación de Investigación Oftalmológica, Universidad de Oviedo), 33012 Oviedo, Spain; (A.Á.-B.); (L.Á.); (M.G.); (E.A.); (R.P.)
| | - Montserrat García
- Instituto Universitario Fernández-Vega (Fundación de Investigación Oftalmológica, Universidad de Oviedo), 33012 Oviedo, Spain; (A.Á.-B.); (L.Á.); (M.G.); (E.A.); (R.P.)
- Instituto Oftalmológico Fernández-Vega, Avda. Dres. Fernández-Vega, 34, 33012 Oviedo, Spain
| | - Enol Artime
- Instituto Universitario Fernández-Vega (Fundación de Investigación Oftalmológica, Universidad de Oviedo), 33012 Oviedo, Spain; (A.Á.-B.); (L.Á.); (M.G.); (E.A.); (R.P.)
| | - Rosario Pereiro
- Instituto Universitario Fernández-Vega (Fundación de Investigación Oftalmológica, Universidad de Oviedo), 33012 Oviedo, Spain; (A.Á.-B.); (L.Á.); (M.G.); (E.A.); (R.P.)
- Department of Physical and Analytical Chemistry, Faculty of Chemistry, University of Oviedo, Julián Clavería, 8, 33006 Oviedo, Spain
| | - Héctor González-Iglesias
- Instituto Universitario Fernández-Vega (Fundación de Investigación Oftalmológica, Universidad de Oviedo), 33012 Oviedo, Spain; (A.Á.-B.); (L.Á.); (M.G.); (E.A.); (R.P.)
- Instituto Oftalmológico Fernández-Vega, Avda. Dres. Fernández-Vega, 34, 33012 Oviedo, Spain
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Blommel K, Knudsen CS, Wegner K, Shrestha S, Singhal SK, Mehus AA, Garrett SH, Singhal S, Zhou X, Voels B, Sens DA, Somji S. Meta-analysis of gene expression profiling reveals novel basal gene signatures in MCF-10A cells transformed with cadmium. Oncotarget 2020; 11:3601-3617. [PMID: 33062196 PMCID: PMC7533076 DOI: 10.18632/oncotarget.27734] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Accepted: 08/17/2020] [Indexed: 01/19/2023] Open
Abstract
Cadmium (Cd2+) is an environmental toxicant and a human carcinogen. Several studies show an association of Cd2+ exposure to the development of breast cancer. Previously, we have transformed the immortalized non-tumorigenic cell line MCF-10A with Cd2+ and have demonstrated that the transformed cells have anchorage independent growth. In a separate study, we showed that transformation of the immortalized urothelial cells with the environmental carcinogen arsenite (As3+) results in an increase in expression of genes associated with the basal subtype of bladder cancer. In this study, we determined if transformation of the MCF-10A cells with Cd2+ would have a similar effect on the expression of basal genes. The results of our study indicate that there is a decrease in expression of genes associated with keratinization and cornification and this gene signature includes the genes associated with the basal subtype of breast cancer. An analysis of human breast cancer databases indicates an increased expression of this gene signature is associated with a positive correlation to patient survival whereas a reduced expression/absence of this gene signature is associated with poor patient survival. Thus, our study suggests that transformation of the MCF-10A cells with Cd2+ produces a decreased basal gene expression profile that correlates to patient outcome.
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Affiliation(s)
- Katrina Blommel
- Department of Pathology, University of North Dakota, School of Medicine and Health Sciences, Grand Forks, ND 58202, USA.,These authors contributed equally to this work
| | - Carley S Knudsen
- Department of Pathology, University of North Dakota, School of Medicine and Health Sciences, Grand Forks, ND 58202, USA.,These authors contributed equally to this work
| | - Kyle Wegner
- Department of Pathology, University of North Dakota, School of Medicine and Health Sciences, Grand Forks, ND 58202, USA.,These authors contributed equally to this work
| | - Swojani Shrestha
- Department of Pathology, University of North Dakota, School of Medicine and Health Sciences, Grand Forks, ND 58202, USA
| | - Sandeep K Singhal
- Department of Pathology, University of North Dakota, School of Medicine and Health Sciences, Grand Forks, ND 58202, USA
| | - Aaron A Mehus
- Department of Pathology, University of North Dakota, School of Medicine and Health Sciences, Grand Forks, ND 58202, USA
| | - Scott H Garrett
- Department of Pathology, University of North Dakota, School of Medicine and Health Sciences, Grand Forks, ND 58202, USA
| | - Sonalika Singhal
- Department of Pathology, University of North Dakota, School of Medicine and Health Sciences, Grand Forks, ND 58202, USA
| | - Xudong Zhou
- Department of Pathology, University of North Dakota, School of Medicine and Health Sciences, Grand Forks, ND 58202, USA
| | - Brent Voels
- Department of Science, Cankdeska Cikana Community College, Fort Totten, ND 58335, USA
| | - Donald A Sens
- Department of Pathology, University of North Dakota, School of Medicine and Health Sciences, Grand Forks, ND 58202, USA
| | - Seema Somji
- Department of Pathology, University of North Dakota, School of Medicine and Health Sciences, Grand Forks, ND 58202, USA
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7
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Lehvy AI, Horev G, Golan Y, Glaser F, Shammai Y, Assaraf YG. Alterations in ZnT1 expression and function lead to impaired intracellular zinc homeostasis in cancer. Cell Death Discov 2019; 5:144. [PMID: 31728210 PMCID: PMC6851190 DOI: 10.1038/s41420-019-0224-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2019] [Revised: 08/26/2019] [Accepted: 10/01/2019] [Indexed: 02/08/2023] Open
Abstract
Zinc is vital for the structure and function of ~3000 human proteins and hence plays key physiological roles. Consequently, impaired zinc homeostasis is associated with various human diseases including cancer. Intracellular zinc levels are tightly regulated by two families of zinc transporters: ZIPs and ZnTs; ZIPs import zinc into the cytosol from the extracellular milieu, or from the lumen of organelles into the cytoplasm. In contrast, the vast majority of ZnTs compartmentalize zinc within organelles, whereas the ubiquitously expressed ZnT1 is the sole zinc exporter. Herein, we explored the hypothesis that qualitative and quantitative alterations in ZnT1 activity impair cellular zinc homeostasis in cancer. Towards this end, we first used bioinformatics to analyze inactivating mutations in ZIPs and ZNTs, catalogued in the COSMIC and gnomAD databases, representing tumor specimens and healthy population controls, respectively. ZnT1, ZnT10, ZIP8, and ZIP10 showed extremely high rates of loss of function mutations in cancer as compared to healthy controls. Analysis of the putative functional impact of missense mutations in ZnT1-ZnT10 and ZIP1-ZIP14, using homologous protein alignment and structural predictions, revealed that ZnT1 displays a markedly increased frequency of predicted functionally deleterious mutations in malignant tumors, as compared to a healthy population. Furthermore, examination of ZnT1 expression in 30 cancer types in the TCGA database revealed five tumor types with significant ZnT1 overexpression, which predicted dismal prognosis for cancer patient survival. Novel functional zinc transport assays, which allowed for the indirect measurement of cytosolic zinc levels, established that wild type ZnT1 overexpression results in low intracellular zinc levels. In contrast, overexpression of predicted deleterious ZnT1 missense mutations did not reduce intracellular zinc levels, validating eight missense mutations as loss of function (LoF) mutations. Thus, alterations in ZnT1 expression and LoF mutations in ZnT1 provide a molecular mechanism for impaired zinc homeostasis in cancer formation and/or progression.
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Affiliation(s)
- Adrian Israel Lehvy
- 1The Fred Wyszkowski Cancer Research, Laboratory, Department of Biology, Technion-Israel Institute of Technology, Haifa, Israel
| | - Guy Horev
- 2Bioinformatics Knowledge Unit, The Lorry, I. Lokey Interdisciplinary Center for Life, Sciences and Engineering, Technion-Israel, Institute of Technology, Haifa, Israel
| | - Yarden Golan
- 1The Fred Wyszkowski Cancer Research, Laboratory, Department of Biology, Technion-Israel Institute of Technology, Haifa, Israel
| | - Fabian Glaser
- 2Bioinformatics Knowledge Unit, The Lorry, I. Lokey Interdisciplinary Center for Life, Sciences and Engineering, Technion-Israel, Institute of Technology, Haifa, Israel
| | - Yael Shammai
- 1The Fred Wyszkowski Cancer Research, Laboratory, Department of Biology, Technion-Israel Institute of Technology, Haifa, Israel
| | - Yehuda Gérard Assaraf
- 1The Fred Wyszkowski Cancer Research, Laboratory, Department of Biology, Technion-Israel Institute of Technology, Haifa, Israel
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8
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Theocharis SE, Margeli AP, Koutselinis A. Metallothionein: A Multifunctional Protein from Toxicity to Cancer. Int J Biol Markers 2018; 18:162-9. [PMID: 14535585 DOI: 10.1177/172460080301800302] [Citation(s) in RCA: 57] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The metallothionein (MT) family is a class of low molecular weight, intracellular and cysteine-rich proteins presenting high affinity for metal ions. Although the members of this family were discovered nearly 40 years ago, their functional significance remains obscure. Four major MT isoforms, MT-1, MT-2, MT-3 and MT-4, have been identified in mammals. MTs are involved in many pathophysiological processes such as metal ion homeostasis and detoxification, protection against oxidative damage, cell proliferation and apoptosis, chemoresistance and radiotherapy resistance. MT isoforms have been shown to be involved in several aspects of the carcinogenic process, cancer development and progression. MT expression has been implicated as a transient response to any form of stress or injury providing cytoprotective action. Although MT participates in the carcinogenic process, its use as a potential marker of tumor differentiation or cell proliferation, or as a predictor of poor prognosis remains unclear. In the present review the involvement of MT in defense mechanisms to toxicity and in carcinogenicity is discussed.
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Affiliation(s)
- S E Theocharis
- Department of Forensic Medicine and Toxicology, Medical School, University of Athens, Greece.
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9
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de Francisco P, Martín-González A, Turkewitz AP, Gutiérrez JC. Extreme metal adapted, knockout and knockdown strains reveal a coordinated gene expression among different Tetrahymena thermophila metallothionein isoforms. PLoS One 2017; 12:e0189076. [PMID: 29206858 PMCID: PMC5716537 DOI: 10.1371/journal.pone.0189076] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2017] [Accepted: 11/17/2017] [Indexed: 01/01/2023] Open
Abstract
Metallothioneins (MT) constitute a superfamily of small cytosolic proteins that are able to bind metal cations through numerous cysteine (Cys) residues. Like other organisms the ciliate Tetrahymena thermophila presents several MT isoforms, which have been classified into two subfamilies (Cd- and Cu-metallothioneins). The main aim of this study was to examine the specific functions and transcriptional regulation of the five MT isoforms present in T. thermophila, by using several strains of this ciliate. After a laboratory evolution experiment over more than two years, three different T. thermophila strains adapted to extreme metal stress (Cd2+, Cu2+ or Pb2+) were obtained. In addition, three knockout and/or knockdown strains for different metallothionein (MT) genes were generated. These strains were then analyzed for expression of the individual MT isoforms. Our results provide a strong basis for assigning differential roles to the set of MT isoforms. MTT1 appears to have a key role in adaptation to Cd. In contrast, MTT2/4 are crucial for Cu-adaptation and MTT5 appears to be important for Pb-adaptation and might be considered as an “alarm” MT gene for responding to metal stress. Moreover, results indicate that likely a coordinated transcriptional regulation exists between the MT genes, particularly among MTT1, MTT5 and MTT2/4. MTT5 appears to be an essential gene, a first such report in any organism of an essential MT gene.
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Affiliation(s)
- Patricia de Francisco
- Departamento de Microbiología-III, Facultad de Biología, Universidad Complutense de Madrid (UCM), Madrid, Spain
| | - Ana Martín-González
- Departamento de Microbiología-III, Facultad de Biología, Universidad Complutense de Madrid (UCM), Madrid, Spain
| | - Aaron P. Turkewitz
- Department of Molecular Genetics and Cell Biology, Cummings Life Sciences Center, University of Chicago, Chicago, Illinois, United States of America
| | - Juan Carlos Gutiérrez
- Departamento de Microbiología-III, Facultad de Biología, Universidad Complutense de Madrid (UCM), Madrid, Spain
- * E-mail:
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10
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Rekers NV, de Fijter J, Claas FH, Eikmans M. Mechanisms and risk assessment of steroid resistance in acute kidney transplant rejection. Transpl Immunol 2016; 38:3-14. [DOI: 10.1016/j.trim.2016.07.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2016] [Accepted: 07/28/2016] [Indexed: 12/15/2022]
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11
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Cuajungco MP, Lees GJ, Kydd RR, Tanzi RE, Bush AI. Zinc and Alzheimer's Disease: An Update. Nutr Neurosci 2016; 2:191-208. [DOI: 10.1080/1028415x.1999.11747277] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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12
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Kimura T, Kambe T. The Functions of Metallothionein and ZIP and ZnT Transporters: An Overview and Perspective. Int J Mol Sci 2016; 17:336. [PMID: 26959009 PMCID: PMC4813198 DOI: 10.3390/ijms17030336] [Citation(s) in RCA: 274] [Impact Index Per Article: 34.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2016] [Revised: 02/25/2016] [Accepted: 02/25/2016] [Indexed: 12/18/2022] Open
Abstract
Around 3000 proteins are thought to bind zinc in vivo, which corresponds to ~10% of the human proteome. Zinc plays a pivotal role as a structural, catalytic, and signaling component that functions in numerous physiological processes. It is more widely used as a structural element in proteins than any other transition metal ion, is a catalytic component of many enzymes, and acts as a cellular signaling mediator. Thus, it is expected that zinc metabolism and homeostasis have sophisticated regulation, and elucidating the underlying molecular basis of this is essential to understanding zinc functions in cellular physiology and pathogenesis. In recent decades, an increasing amount of evidence has uncovered critical roles of a number of proteins in zinc metabolism and homeostasis through influxing, chelating, sequestrating, coordinating, releasing, and effluxing zinc. Metallothioneins (MT) and Zrt- and Irt-like proteins (ZIP) and Zn transporters (ZnT) are the proteins primarily involved in these processes, and their malfunction has been implicated in a number of inherited diseases such as acrodermatitis enteropathica. The present review updates our current understanding of the biological functions of MTs and ZIP and ZnT transporters from several new perspectives.
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Affiliation(s)
- Tomoki Kimura
- Department of Life Science, Faculty of Science and Engineering, Setsunan University, Neyagawa, Osaka 572-8508, Japan.
| | - Taiho Kambe
- Division of Integrated Life Science, Graduate School of Biostudies, Kyoto University, Kyoto 606-8502, Japan.
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13
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Dziegiel P, Pula B, Kobierzycki C, Stasiolek M, Podhorska-Okolow M. Metallothioneins: Structure and Functions. METALLOTHIONEINS IN NORMAL AND CANCER CELLS 2016. [DOI: 10.1007/978-3-319-27472-0_2] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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14
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Siddiq MM, Hannila SS. Looking downstream: the role of cyclic AMP-regulated genes in axonal regeneration. Front Mol Neurosci 2015; 8:26. [PMID: 26150769 PMCID: PMC4471816 DOI: 10.3389/fnmol.2015.00026] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2015] [Accepted: 06/03/2015] [Indexed: 11/16/2022] Open
Abstract
Elevation of intracellular cyclic AMP (cAMP) levels has proven to be one of the most effective means of overcoming inhibition of axonal regeneration by myelin-associated inhibitors such as myelin-associated glycoprotein (MAG), Nogo, and oligodendrocyte myelin glycoprotein. Pharmacological manipulation of cAMP through the administration of dibutyryl cAMP or rolipram leads to enhanced axonal growth both in vivo and in vitro, and importantly, upregulation of cAMP within dorsal root ganglion neurons is responsible for the conditioning lesion effect, which indicates that cAMP plays a significant role in the endogenous mechanisms that promote axonal regeneration. The effects of cAMP are transcription-dependent and are mediated through the activation of protein kinase A (PKA) and the transcription factor cyclic AMP response element binding protein (CREB). This leads to the induction of a variety of genes, several of which have been shown to overcome myelin-mediated inhibition in their own right. In this review, we will highlight the pro-regenerative effects of arginase I (ArgI), interleukin (IL)-6, secretory leukocyte protease inhibitor (SLPI), and metallothionein (MT)-I/II, and discuss their potential for therapeutic use in spinal cord injury.
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Affiliation(s)
- Mustafa M Siddiq
- Icahn Medical Institute, Pharmacology and Systems Therapeutics, Mount Sinai School of Medicine New York, NY, USA
| | - Sari S Hannila
- Department of Human Anatomy and Cell Science, University of Manitoba Winnipeg, MB, Canada
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15
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Siddiq MM, Hannila SS, Carmel JB, Bryson JB, Hou J, Nikulina E, Willis MR, Mellado W, Richman EL, Hilaire M, Hart RP, Filbin MT. Metallothionein-I/II Promotes Axonal Regeneration in the Central Nervous System. J Biol Chem 2015; 290:16343-56. [PMID: 25947372 DOI: 10.1074/jbc.m114.630574] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2014] [Indexed: 11/06/2022] Open
Abstract
The adult CNS does not spontaneously regenerate after injury, due in large part to myelin-associated inhibitors such as myelin-associated glycoprotein (MAG), Nogo-A, and oligodendrocyte-myelin glycoprotein. All three inhibitors can interact with either the Nogo receptor complex or paired immunoglobulin-like receptor B. A conditioning lesion of the sciatic nerve allows the central processes of dorsal root ganglion (DRG) neurons to spontaneously regenerate in vivo after a dorsal column lesion. After a conditioning lesion, DRG neurons are no longer inhibited by myelin, and this effect is cyclic AMP (cAMP)- and transcription-dependent. Using a microarray analysis, we identified several genes that are up-regulated both in adult DRGs after a conditioning lesion and in DRG neurons treated with cAMP analogues. One gene that was up-regulated under both conditions is metallothionein (MT)-I. We show here that treatment with two closely related isoforms of MT (MT-I/II) can overcome the inhibitory effects of both myelin and MAG for cortical, hippocampal, and DRG neurons. Intrathecal delivery of MT-I/II to adult DRGs also promotes neurite outgrowth in the presence of MAG. Adult DRGs from MT-I/II-deficient mice extend significantly shorter processes on MAG compared with wild-type DRG neurons, and regeneration of dorsal column axons does not occur after a conditioning lesion in MT-I/II-deficient mice. Furthermore, a single intravitreal injection of MT-I/II after optic nerve crush promotes axonal regeneration. Mechanistically, MT-I/II ability to overcome MAG-mediated inhibition is transcription-dependent, and MT-I/II can block the proteolytic activity of α-secretase and the activation of PKC and Rho in response to soluble MAG.
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Affiliation(s)
- Mustafa M Siddiq
- From the Department of Biological Sciences, Hunter College, City University of New York, New York 10065 and
| | - Sari S Hannila
- From the Department of Biological Sciences, Hunter College, City University of New York, New York 10065 and
| | - Jason B Carmel
- the W. M. Keck Center for Collaborative Neuroscience and Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, New Jersey 08854
| | - John B Bryson
- From the Department of Biological Sciences, Hunter College, City University of New York, New York 10065 and
| | - Jianwei Hou
- From the Department of Biological Sciences, Hunter College, City University of New York, New York 10065 and
| | - Elena Nikulina
- From the Department of Biological Sciences, Hunter College, City University of New York, New York 10065 and
| | - Matthew R Willis
- From the Department of Biological Sciences, Hunter College, City University of New York, New York 10065 and
| | - Wilfredo Mellado
- From the Department of Biological Sciences, Hunter College, City University of New York, New York 10065 and
| | - Erica L Richman
- From the Department of Biological Sciences, Hunter College, City University of New York, New York 10065 and
| | - Melissa Hilaire
- From the Department of Biological Sciences, Hunter College, City University of New York, New York 10065 and
| | - Ronald P Hart
- the W. M. Keck Center for Collaborative Neuroscience and Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, New Jersey 08854
| | - Marie T Filbin
- From the Department of Biological Sciences, Hunter College, City University of New York, New York 10065 and
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16
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Blindauer CA. Advances in the molecular understanding of biological zinc transport. Chem Commun (Camb) 2015; 51:4544-63. [DOI: 10.1039/c4cc10174j] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Recognition of the importance of zinc homeostasis for health has driven a surge in structural data on major zinc-transporting proteins.
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17
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Raudenska M, Gumulec J, Podlaha O, Sztalmachova M, Babula P, Eckschlager T, Adam V, Kizek R, Masarik M. Metallothionein polymorphisms in pathological processes. Metallomics 2014; 6:55-68. [PMID: 24068159 DOI: 10.1039/c3mt00132f] [Citation(s) in RCA: 83] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Metallothioneins (MTs) are a class of metal-binding proteins characterized by a high cysteine content and low molecular weight. MTs play an important role in metal metabolism and protect cells against the toxic effects of radiation, alkylating agents and oxygen free radicals. The evidence that individual genetic characteristics of MTs play an important role in physiological and pathological processes associated with antioxidant defense and detoxification inspired targeted studies of genetic polymorphisms in a clinical context. In recent years, common MT polymorphisms were identified and associated with, particularly, western lifestyle diseases such as cancer, complications of atherosclerosis, and type 2 diabetes mellitus along with related complications. This review summarizes all evidence regarding MT polymorphisms of major human MTs (MT1, MT2, MT3 and MT4), their relation to pathological processes, and outlines specific applications of MTs as a set of genetic markers for certain pathologies.
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Affiliation(s)
- Martina Raudenska
- Department of Pathological Physiology, Faculty of Medicine, Masaryk University, Kamenice 5, CZ-625 00 Brno, Czech Republic.
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18
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Zalewska M, Trefon J, Milnerowicz H. The role of metallothionein interactions with other proteins. Proteomics 2014; 14:1343-56. [DOI: 10.1002/pmic.201300496] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2013] [Revised: 02/20/2014] [Accepted: 03/06/2014] [Indexed: 12/24/2022]
Affiliation(s)
- Marta Zalewska
- Department of Biomedical and Environmental Analysis; Faculty of Pharmacy; Wroclaw Medical University; Wroclaw Poland
| | - Jagoda Trefon
- Students Scientific Association; Department of Biomedical and Environmental Analysis; Faculty of Pharmacy; Wroclaw Medical University; Wroclaw Poland
| | - Halina Milnerowicz
- Department of Biomedical and Environmental Analysis; Faculty of Pharmacy; Wroclaw Medical University; Wroclaw Poland
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19
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Rekers NV, Bajema IM, Mallat MJK, Anholts JDH, de Vaal YJH, Zandbergen M, Haasnoot GW, van Zwet EW, de Fijter JW, Claas FHJ, Eikmans M. Increased metallothionein expression reflects steroid resistance in renal allograft recipients. Am J Transplant 2013; 13:2106-18. [PMID: 23763497 DOI: 10.1111/ajt.12314] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2013] [Revised: 04/02/2013] [Accepted: 04/25/2013] [Indexed: 01/25/2023]
Abstract
Steroid-refractory acute rejection is a risk factor for inferior renal allograft outcome. We aimed to gain insight into the mechanisms underlying steroid resistance by identifying novel molecular markers of steroid-refractory acute rejection. Eighty-three kidney transplant recipients (1995-2005), who were treated with methylprednisolone during a first acute rejection episode, were included in this study. Gene expression patterns were investigated in a discovery cohort of 36 acute rejection biopsies, and verified in a validation cohort of 47 acute rejection biopsies. In the discovery set, expression of metallothioneins (MT) was significantly (p < 0.000001) associated with decreased response to steroid treatment. Multivariate analysis resulted in a predictive model containing MT-1 as an independent covariate (AUC = 0.88, p < 0.0000001). In the validation set, MT-1 expression was also significantly associated with steroid resistance (p = 0.029). Metallothionein expression was detected in macrophages and tubular epithelial cells. Parallel to the findings in patients, in vitro experiments of peripheral blood mononuclear cells from 11 donors showed that nonresponse to methylprednisolone treatment is related to highly elevated MT levels. High expression of metallothioneins in renal allografts is associated with resistance to steroid treatment. Metallothioneins regulate intracellular concentrations of zinc, through which they may diminish the zinc-requiring anti-inflammatory effect of the glucocorticoid receptor.
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Affiliation(s)
- N V Rekers
- Department of Immunohematology and Blood Transfusion, Leiden University Medical Center, Leiden, the Netherlands.
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20
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Ruttkay-Nedecky B, Nejdl L, Gumulec J, Zitka O, Masarik M, Eckschlager T, Stiborova M, Adam V, Kizek R. The role of metallothionein in oxidative stress. Int J Mol Sci 2013; 14:6044-66. [PMID: 23502468 PMCID: PMC3634463 DOI: 10.3390/ijms14036044] [Citation(s) in RCA: 501] [Impact Index Per Article: 45.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2013] [Revised: 02/14/2013] [Accepted: 02/20/2013] [Indexed: 12/15/2022] Open
Abstract
Free radicals are chemical particles containing one or more unpaired electrons, which may be part of the molecule. They cause the molecule to become highly reactive. The free radicals are also known to play a dual role in biological systems, as they can be either beneficial or harmful for living systems. It is clear that there are numerous mechanisms participating on the protection of a cell against free radicals. In this review, our attention is paid to metallothioneins (MTs) as small, cysteine-rich and heavy metal-binding proteins, which participate in an array of protective stress responses. The mechanism of the reaction of metallothioneins with oxidants and electrophilic compounds is discussed. Numerous reports indicate that MT protects cells from exposure to oxidants and electrophiles, which react readily with sulfhydryl groups. Moreover, MT plays a key role in regulation of zinc levels and distribution in the intracellular space. The connections between zinc, MT and cancer are highlighted.
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Affiliation(s)
- Branislav Ruttkay-Nedecky
- Central European Institute of Technology, Brno University of Technology, Technicka 3058/10, CZ-616 00 Brno, Czech Republic; E-Mails: (B.R.-N.); (L.N.); (J.G.); (O.Z.); (M.M.); (V.A.)
| | - Lukas Nejdl
- Department of Chemistry and Biochemistry, Faculty of Agronomy, Mendel University in Brno, Zemedelska 1, CZ-613 00 Brno, Czech Republic
| | - Jaromir Gumulec
- Central European Institute of Technology, Brno University of Technology, Technicka 3058/10, CZ-616 00 Brno, Czech Republic; E-Mails: (B.R.-N.); (L.N.); (J.G.); (O.Z.); (M.M.); (V.A.)
- Department of Pathological Physiology, Faculty of Medicine, Masaryk University, Kamenice 5, CZ-612 00 Brno, Czech Republic
| | - Ondrej Zitka
- Central European Institute of Technology, Brno University of Technology, Technicka 3058/10, CZ-616 00 Brno, Czech Republic; E-Mails: (B.R.-N.); (L.N.); (J.G.); (O.Z.); (M.M.); (V.A.)
- Department of Chemistry and Biochemistry, Faculty of Agronomy, Mendel University in Brno, Zemedelska 1, CZ-613 00 Brno, Czech Republic
| | - Michal Masarik
- Central European Institute of Technology, Brno University of Technology, Technicka 3058/10, CZ-616 00 Brno, Czech Republic; E-Mails: (B.R.-N.); (L.N.); (J.G.); (O.Z.); (M.M.); (V.A.)
- Department of Pathological Physiology, Faculty of Medicine, Masaryk University, Kamenice 5, CZ-612 00 Brno, Czech Republic
| | - Tomas Eckschlager
- Department of Paediatric Haematology and Oncology, 2nd Faculty of Medicine, Charles University and University Hospital Motol, V Uvalu 84, CZ-150 06 Prague 5, Czech Republic; E-Mail:
| | - Marie Stiborova
- Department of Biochemistry, Faculty of Science, Charles University, Albertov 2030, CZ-128 40 Prague 2, Czech Republic; E-Mail:
| | - Vojtech Adam
- Central European Institute of Technology, Brno University of Technology, Technicka 3058/10, CZ-616 00 Brno, Czech Republic; E-Mails: (B.R.-N.); (L.N.); (J.G.); (O.Z.); (M.M.); (V.A.)
- Department of Chemistry and Biochemistry, Faculty of Agronomy, Mendel University in Brno, Zemedelska 1, CZ-613 00 Brno, Czech Republic
| | - Rene Kizek
- Central European Institute of Technology, Brno University of Technology, Technicka 3058/10, CZ-616 00 Brno, Czech Republic; E-Mails: (B.R.-N.); (L.N.); (J.G.); (O.Z.); (M.M.); (V.A.)
- Department of Chemistry and Biochemistry, Faculty of Agronomy, Mendel University in Brno, Zemedelska 1, CZ-613 00 Brno, Czech Republic
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21
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Krizkova S, Ryvolova M, Hrabeta J, Adam V, Stiborova M, Eckschlager T, Kizek R. Metallothioneins and zinc in cancer diagnosis and therapy. Drug Metab Rev 2012; 44:287-301. [PMID: 23050852 DOI: 10.3109/03602532.2012.725414] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Metallothioneins (MTs) are involved in protection against oxidative stress (OS) and toxic metals and they participate in zinc metabolism and its homeostasis. Disturbing of zinc homeostasis can lead to formation of reactive oxygen species, which can result in OS causing alterations in immunity, aging, and civilization diseases, but also in cancer development. It is not surprising that altered zinc metabolism and expression of MTs are of great interest in the case of studying of oncogenesis and cancer prognosis. The role of MTs and zinc in cancer development is tightly connected, and the structure and function of MTs are strongly dependent on Zn²⁺ redox state and its binding to proteins. Antiapoptic effects of MTs and their interactions with proteins nuclear factor kappa B, protein kinase C, esophageal cancer-related gene, and p53 as well as the role of MTs in their proliferation, immunomodulation, enzyme activation, and interaction with nitric oxide are reviewed. Utilization of MTs in cancer diagnosis and therapy is summarized and their importance for chemoresistance is also mentioned.
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Affiliation(s)
- Sona Krizkova
- Department of Chemistry and Biochemistry, Faculty of Agronomy, Mendel University in Brno, Brno, Czech Republic
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22
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Alam S, Kelleher SL. Cellular mechanisms of zinc dysregulation: a perspective on zinc homeostasis as an etiological factor in the development and progression of breast cancer. Nutrients 2012; 4:875-903. [PMID: 23016122 PMCID: PMC3448077 DOI: 10.3390/nu4080875] [Citation(s) in RCA: 117] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2012] [Revised: 07/11/2012] [Accepted: 07/17/2012] [Indexed: 12/29/2022] Open
Abstract
Worldwide, breast cancer is the most commonly diagnosed cancer among women and is the leading cause of female cancer deaths. Zinc (Zn) functions as an antioxidant and plays a role in maintaining genomic stability. Zn deficiency results in oxidative DNA damage and increased cancer risk. Studies suggest an inverse association between dietary and plasma Zn levels and the risk for developing breast cancer. In contrast, breast tumor biopsies display significantly higher Zn levels compared with normal tissue. Zn accumulation in tumor tissue also correlates with increased levels of Zn importing proteins. Further, aberrant expression of Zn transporters in tumors correlates with malignancy, suggesting that altered metal homeostasis in the breast could contribute to malignant transformation and the severity of cancer. However, studies have yet to link dysregulated Zn transport and abnormal Zn-dependent functions in breast cancer development. Herein, we summarize studies that address the multi-modal role of Zn dyshomeostasis in breast cancer with respect to the role of Zn in modulating oxidative stress, DNA damage response/repair pathways and cell proliferation/apoptosis, and the relationship to aberrant regulation of Zn transporters. We also compare Zn dysregulation in breast tissue to that of prostate, pancreatic and ovarian cancer where possible.
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Affiliation(s)
- Samina Alam
- Department of Nutritional Sciences, The Pennsylvania State University, University Park, PA 16802, USA;
| | - Shannon L. Kelleher
- Department of Nutritional Sciences, The Pennsylvania State University, University Park, PA 16802, USA;
- Department of Surgery, the Pennsylvania State University College of Medicine, Hershey, PA 17033, USA
- Cell and Molecular Physiology, the Pennsylvania State University College of Medicine, Hershey, PA 17033, USA
- Author to whom correspondence should be addressed; ; Tel.: +1-814-863-9680; Fax: +1-814-863-6103
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23
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Takahashi S. Molecular functions of metallothionein and its role in hematological malignancies. J Hematol Oncol 2012; 5:41. [PMID: 22839501 PMCID: PMC3419633 DOI: 10.1186/1756-8722-5-41] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2012] [Accepted: 07/27/2012] [Indexed: 11/10/2022] Open
Abstract
Metallothionein (MT) was reported to be a potential negative regulator of apoptosis, and various reports have suggested that it may play roles in carcinogenesis and drug resistance, in at least a portion of cancer cells. The author summarizes the current understanding of the molecular functions of MT for tumor cell growth and drug resistance. These activities are regulated through intracellular metal ion modulation and free radical scavenging. Compared with analyses of solid tumors, few studies have analyzed the roles of MT in hematological malignancies. This review mainly describes the functions of MT in hematopoietic cells. Furthermore, through expression analyses of leukemias and lymphomas, the roles of MT in the biology of these diseases are particularly focused upon.
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Affiliation(s)
- Shinichiro Takahashi
- Division of Hematology, Kitasato University School of Allied Health Sciences, 1-15-1 Kitasato, Minami-ku, Sagamihara, 252-0373, Japan.
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24
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Ryu HH, Jung S, Jung TY, Moon KS, Kim IY, Jeong YI, Jin SG, Pei J, Wen M, Jang WY. Role of metallothionein 1E in the migration and invasion of human glioma cell lines. Int J Oncol 2012; 41:1305-13. [PMID: 22843066 DOI: 10.3892/ijo.2012.1570] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2012] [Accepted: 03/21/2012] [Indexed: 11/06/2022] Open
Abstract
Metallothionein 1E (MT1E) has been found to be highly expressed in motile cell lines. We investigated whether MT1E actually modulates the migration and invasion of human glioma cell lines and the types of factors that have an effect on MT1E. RNA differential display was performed using Genefishing™ technology in the human glioma cell lines U343MG-A, U87MG and U87MG-10'; the results were validated by RT-PCR and northern blot analysis, in order to detect possible genetic changes as the determining factors for migration ability in malignant glioma. MT1E was identified in U87MG, a highly motile cell line. The migration and invasion abilities of human glioma cell lines, and MT1E transfectants were investigated using simple scratch testing and Matrigel invasion assays. Morphological and cytoskeletal (actin, vimentin) changes were documented by light and confocal microscopy. The expression of MT1E in four glioma cell lines was assessed by RT-PCR and western blotting. In addition, the effects of MT1E on the activity of the NF-κB p50/p65 transcription factor, MMP-2 and -9 were examined by western blotting and zymography. The endogenous MT1E expression in the human glioma cell lines was statistically correlated with their migratory abilities and invasion. The U87-MT-AS cells became more round and had decreased stress fibers, compared with the U87MG cells. Endogenous MT1E expression in the four human glioma cell lines was directly correlated with migration. Two antisense MT1E-transfected cell lines showed decreased NF-κB p50 translocation into the nucleus, which led to decreased activity of MMP-9 in conditioned media. It may be postulated that MT1E can enhance the migration and invasion of human glioma cells by inducing MMP-9 inactivation via the upregulation of NF-κB p50.
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Affiliation(s)
- Hyang-Hwa Ryu
- Department of Brain Tumor Research Laboratory, Chonnam National University Research Institute of Medical Sciences, Chonnam National University Hwasun Hospital and Medical School, Gwangju, Republic of Korea
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25
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Affiliation(s)
- Kasper P Kepp
- DTU Chemistry, Technical University of Denmark, DK 2800 Kongens Lyngby, Denmark.
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26
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Greisen P, Jespersen JB, Kepp KP. Metallothionein Zn2+- and Cu2+-clusters from first-principles calculations. Dalton Trans 2011; 41:2247-56. [PMID: 22183579 DOI: 10.1039/c1dt11785h] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Detailed electronic structures of Zn(II) and Cu(II) clusters from metallothioneins (MT) have been obtained using density functional theory (DFT), in order to investigate how oxidative stress-caused Cu(II) intermediates affect Zn-binding to MT and cooperatively lead to Cu(I)MT. The inferred accuracy is ∼0.02-0.03 Å for metal-thiolate bond lengths for the models that are the most realistic MT models so far studied by DFT. We find terminal Zn-S and Cu-S bond lengths of 2.35-2.38 Å and 2.30-2.34 Å, whereas bridging M-S bonds are 0.05-0.11 Å longer. This electronic effect is also reflected in changes in electron density on bridging sulfurs. Various imposed backbone constraints quantify the sensitivity of cluster electronic structure towards protein conformational changes. The large negative charge densities of the clusters are central to MT function, and the smaller β-clusters are more prone to modification. Oxidative stress-associated Cu(II) binding weakens the Zn-S bonds and is thus likely to impair the Zn(II) transfer function of MTs, providing a mechanism for cooperative Cu(II) binding leading to loss of Zn(II) and dysfunctional Cu(I)MT clusters.
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Affiliation(s)
- Per Greisen
- Technical University of Denmark, DTU Physics, 2800, Kongens Lyngby, Denmark
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27
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Kepp KP. Full quantum-mechanical structure of the human protein Metallothionein-2. J Inorg Biochem 2011; 107:15-24. [PMID: 22178664 DOI: 10.1016/j.jinorgbio.2011.11.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2011] [Revised: 11/02/2011] [Accepted: 11/08/2011] [Indexed: 01/18/2023]
Abstract
Metallothioneins (MT) are small, metal-binding proteins with diverse functions related to metal ion homeostasis. This paper presents the full 384-388-atom structures of the two native Zn(II)- and the Cd(II)-containing domains of human MT2, optimized with density functional theory. The presented structures are accurate to ~0.03 Å for bond lengths and thus provide new physical insight into the detailed electronic structures of MTs, in particular with accurate accounts of bridging vs. terminal bonds not available from NMR or EXAFS. The MT protein enhances the asymmetry, as compared to the protein-free clusters, causing a hierarchy in binding that most likely allows MTs to transfer ions to multiple targets in vivo. The protein polarization is substantial and occurs primarily via the terminal sulfurs, a key mechanism in providing domain-specific electronic structures. The β-domain polarizes its smaller cluster less on average, due to its less polarizable, higher negative charge density, as reflected in longer MS bond lengths and smaller bond orders. This may explain why MT2β is more reactive and dynamic and why MTs have evolved two different-size, asymmetric domains with different metal binding affinities fit for different molecular targets of metal ion transfer.
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Affiliation(s)
- Kasper P Kepp
- Technical University of Denmark, DTU Chemistry, DK-2800 Kgs. Lyngby, Denmark.
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28
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Huang X, Fang CW, Guo YW, Huang HQ. Differential protein expression of kidney tissue in the scallop Patinopecten yessoensis under acute cadmium stress. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2011; 74:1232-1237. [PMID: 21377207 DOI: 10.1016/j.ecoenv.2011.02.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2010] [Revised: 02/11/2011] [Accepted: 02/13/2011] [Indexed: 05/30/2023]
Abstract
Morphological and proteomic changes in the kidney of scallops exposed to acute cadmium chloride (CdCl₂) were observed, analyzed and compared with those in the non-exposed control group. Under microscopy the paraffin-embedded sections of the kidney revealed that the microstructure of the tissue had been severely deformed after Cd exposure. Two dimensional electrophoresis, MALDI-TOF mass spectrometry and database searches showed 13 differentially expressed protein spots, of which 11 were up-regulated, while two were down-regulated. Among these proteins, guanylate kinase (GK) and C₂H₂-type zinc finger protein are considered to be tightly connected with Cd toxicity. Further studies using quantitative PCR method validated that the GK mRNA was induced under Cd stress. Other proteins identified which had some relevance to Cd toxicity are also discussed. We suggested that differential proteins such as GK could play a potential role as novel biomarkers for monitoring the level of Cd contamination in seawater.
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Affiliation(s)
- Xiang Huang
- Department of Biochemistry and Biotechnology, School of Life Sciences, Xiamen University, Xiamen 361005, China
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29
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Vašák M, Meloni G. Chemistry and biology of mammalian metallothioneins. J Biol Inorg Chem 2011; 16:1067-78. [PMID: 21647776 DOI: 10.1007/s00775-011-0799-2] [Citation(s) in RCA: 197] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2011] [Accepted: 05/12/2011] [Indexed: 10/18/2022]
Abstract
Metallothioneins (MTs) are a class of ubiquitously occurring low molecular mass, cysteine- and metal-rich proteins containing sulfur-based metal clusters formed with Zn(II), Cd(II), and Cu(I) ions. In mammals, four distinct MT isoforms designated MT-1 through MT-4 exist. The first discovered MT-1/MT-2 are widely expressed isoforms, whose biosynthesis is inducible by a wide range of stimuli, including metals, drugs, and inflammatory mediators. In contrast, MT-3 and MT-4 are noninducible proteins, with their expression primarily confined to the central nervous system and certain squamous epithelia, respectively. MT-1 through MT-3 have been reported to be secreted, suggesting that they may play different biological roles in the intracellular and extracellular space. Recent reports established that these isoforms play an important protective role in brain injury and metal-linked neurodegenerative diseases. In the postgenomic era, it is becoming increasingly clear that MTs fulfill multiple functions, including the involvement in zinc and copper homeostasis, protection against heavy metal toxicity, and oxidative damage. All mammalian MTs are monomeric proteins, containing two metal-thiolate clusters. In this review, after a brief summary of the historical milestones of the MT-1/MT-2 research, the recent advances in the structure, chemistry, and biological function of MT-3 and MT-4 are discussed.
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Affiliation(s)
- Milan Vašák
- Department of Biochemistry, University of Zurich, Zurich, Switzerland.
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30
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Napoli E, Ross-Inta C, Wong S, Omanska-Klusek A, Barrow C, Iwahashi C, Garcia-Arocena D, Sakaguchi D, Berry-Kravis E, Hagerman R, Hagerman PJ, Giulivi C. Altered zinc transport disrupts mitochondrial protein processing/import in fragile X-associated tremor/ataxia syndrome. Hum Mol Genet 2011; 20:3079-92. [PMID: 21558427 DOI: 10.1093/hmg/ddr211] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Fragile X-associated tremor/ataxia syndrome (FXTAS) is a late-onset neurodegenerative disorder that affects individuals who are carriers of small CGG premutation expansions in the fragile X mental retardation 1 (FMR1) gene. Mitochondrial dysfunction was observed as an incipient pathological process occurring in individuals who do not display overt features of FXTAS (1). Fibroblasts from premutation carriers had lower oxidative phosphorylation capacity (35% of controls) and Complex IV activity (45%), and higher precursor-to-mature ratios (P:M) of nDNA-encoded mitochondrial proteins (3.1-fold). However, fibroblasts from carriers with FXTAS symptoms presented higher FMR1 mRNA expression (3-fold) and lower Complex V (38%) and aconitase activities (43%). Higher P:M of ATPase β-subunit (ATPB) and frataxin were also observed in cortex from patients that died with FXTAS symptoms. Biochemical findings observed in FXTAS cells (lower mature frataxin, lower Complex IV and aconitase activities) along with common phenotypic traits shared by Friedreich's ataxia and FXTAS carriers (e.g. gait ataxia, loss of coordination) are consistent with a defective iron homeostasis in both diseases. Higher P:M, and lower ZnT6 and mature frataxin protein expression suggested defective zinc and iron metabolism arising from altered ZnT protein expression, which in turn impairs the activity of mitochondrial Zn-dependent proteases, critical for the import and processing of cytosolic precursors, such as frataxin. In support of this hypothesis, Zn-treated fibroblasts showed a significant recovery of ATPB P:M, ATPase activity and doubling time, whereas Zn and desferrioxamine extended these recoveries and rescued Complex IV activity.
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Affiliation(s)
- Eleonora Napoli
- Department of Molecular Biosciences, School of Veterinary Medicine, School of Medicine, University of California Davis, Davis, CA 95616, USA
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Huang ZX, Liu F, Zheng Q, Yu WH. Zinc Transfer Kinetics of Metallothioneins and Their Fragments with Apo-carbonic Anhydrase. CHINESE J CHEM 2010. [DOI: 10.1002/cjoc.20010190506] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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32
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Jensen KP, Rykær M. The building blocks of metallothioneins: heterometallic Zn2+ and Cd2+ clusters from first-principles calculations. Dalton Trans 2010; 39:9684-95. [DOI: 10.1039/c0dt00087f] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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33
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Xia N, Liu L, Yi X, Wang J. Studies of interaction of tumor suppressor p53 with apo-MT using surface plasmon resonance. Anal Bioanal Chem 2009; 395:2569-75. [DOI: 10.1007/s00216-009-3174-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2009] [Revised: 09/18/2009] [Accepted: 09/19/2009] [Indexed: 11/24/2022]
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34
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Kim HG, Hwang YP, Han EH, Choi CY, Yeo CY, Kim JY, Lee KY, Jeong HG. Metallothionein-III provides neuronal protection through activation of nuclear factor-kappaB via the TrkA/phosphatidylinositol-3 kinase/Akt signaling pathway. Toxicol Sci 2009; 112:435-49. [PMID: 19767621 DOI: 10.1093/toxsci/kfp230] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Metallothionein (MT)-III is associated with resistance to neuronal injury. However, the underlying mechanism for its effects is unclear. The present study investigated the mechanisms of MT-III protection of neuronal cells from hypoxia or DNA damage-induced cell death. MT-III reduced the hydrogen peroxide- or DNA damage-induced effects on neuronal cells, including the cell death, the activation of caspase-3 and -9, and the release of mitochondrial cytochrome c to the cytoplasm in a dose-dependent manner. MT-III also increased the activation of Akt, the phosphorylation and degradation of IkappaB, the nuclear translocation/accumulation and the transcriptional activity of nuclear factor-kappaB (NF-kappaB) in neuronal cells in a dose-dependent manner. The MT-III-induced antiapoptotic effects and increase in NF-kappaB activity were blocked by specific inhibitors of TrkA, phosphatidylinositol-3 kinase (PI3K), Akt, or NF-kappaB, indicating that MT-III provides neuronal protection by activating NF-kappaB through the TrkA/PI3K/Akt signaling pathway.
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Affiliation(s)
- Hyung Gyun Kim
- Department of Pharmacy and Research Center for Proteineous Materials, College of Pharmacy, Chosun University, Gwangju, South Korea
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35
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Thompson CA, Burcham PC. Genome-Wide Transcriptional Responses to Acrolein. Chem Res Toxicol 2008; 21:2245-56. [DOI: 10.1021/tx8001934] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Affiliation(s)
- Colin A. Thompson
- Pharmacology and Anaesthesiology Unit, School of Medicine and Pharmacology, The University of Western Australia, Perth WA 6009, Australia
| | - Philip C. Burcham
- Pharmacology and Anaesthesiology Unit, School of Medicine and Pharmacology, The University of Western Australia, Perth WA 6009, Australia
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36
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Kimura T, Itoh N. Function of Metallothionein in Gene Expression and Signal Transduction: Newly Found Protective Role of Metallothionein. ACTA ACUST UNITED AC 2008. [DOI: 10.1248/jhs.54.251] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- Tomoki Kimura
- Department of Toxicology, Faculty of Pharmaceutical Sciences, Setsunan University
| | - Norio Itoh
- Department of Toxicology, Graduate School of Pharmaceutical Sciences, Osaka University
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37
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Chung RS, Hidalgo J, West AK. New insight into the molecular pathways of metallothionein-mediated neuroprotection and regeneration. J Neurochem 2007; 104:14-20. [PMID: 17986229 DOI: 10.1111/j.1471-4159.2007.05026.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
There is a large body of evidence demonstrating that metallothioneins (MTs) expressed in astrocytes following CNS injury, exhibit both neuroprotective and neuroregenerative properties and are critical for recovery outcomes. As these proteins lack signal peptides, and have well characterized free radical scavenging and heavy metal binding properties, the neuroprotective functions of MTs have been attributed to these intracellular roles. However, there is an increasing realization that the neuroprotective functions of MTs may also involve an extracellular component. In this issue of Journal of Neurochemistry, Ambjørn et al. reveal considerable insight into this novel function of MTs. In this review, we examine the seminal work of Ambjørn et al. in the context of our current understanding of the role of MT in astrocyte-neuron interactions in the injured brain, and also discuss the significant therapeutic potential of their work.
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Affiliation(s)
- R S Chung
- NeuroRepair Group, Menzies Research Institute, University of Tasmania, Hobart, Tasmania, Australia.
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38
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Formigari A, Irato P, Santon A. Zinc, antioxidant systems and metallothionein in metal mediated-apoptosis: biochemical and cytochemical aspects. Comp Biochem Physiol C Toxicol Pharmacol 2007; 146:443-59. [PMID: 17716951 DOI: 10.1016/j.cbpc.2007.07.010] [Citation(s) in RCA: 120] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/05/2007] [Revised: 07/23/2007] [Accepted: 07/25/2007] [Indexed: 11/19/2022]
Abstract
Copper, zinc and iron are essential metals for different physiological functions, even though their excess can lead to biological damage. This review provides a background of toxicity related to copper, iron and zinc excess, biological mechanisms of their homeostasis and their respective roles in the apoptotic process. The antioxidant action of metallothionein has been highlighted by summarizing the most important findings that confirm the role of zinc in cellular protection in relation to metallothionein expression and apoptotic processes. In particular, we show that a complex and efficient antioxidant system, the induction of metallothionein and the direct action of zinc have protective roles against oxidative damage and the resulting apoptosis induced by metals with redox proprieties. In addition, to emphasize the protective effects of Zn and Zn-MT in Cu and Fe-mediated oxidative stress-dependent apoptosis, some aspects of apoptotic cell death are shown. The most widely used cytochemical techniques also have been examined in order to critically evaluate the available data from a methodological point of view. The observations on the role of Zn and MT could potentially develop new applications for this metal and MT in biomedical research.
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Mason AZ, Moeller R, Thrippleton KA, Lloyd D. Use of stable isotopically enriched proteins and directly coupled high-performance liquid chromatography inductively coupled plasma mass spectrometry for quantitatively monitoring the transfer of metals between proteins. Anal Biochem 2007; 369:87-104. [PMID: 17673155 DOI: 10.1016/j.ab.2007.06.015] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2007] [Revised: 06/09/2007] [Accepted: 06/12/2007] [Indexed: 11/28/2022]
Abstract
Studies have shown that metallothionein (MT) may play an important role in modulating the activity of certain Zn-regulated enzymes under various oxidoreductive conditions by either donating or removing Zn. To better determine the role of MT in interprotein metal transfer, we describe a procedure that uses stable isotopically enriched (67)Zn(7) metallothionein 2 ((67)Zn(7)-MT-2) to quantitatively determine the stoichiometry of transfer of Zn from the protein to a recipient apo-metalloenzyme, apo-carbonic anhydrase (apo-CA) by directly coupled ion exchange high-performance liquid chromatography inductively coupled plasma mass spectrometry. Quantitatively, the transfer of (67)Zn was consistent with the enzymatic activation of the apo-enzyme as judged by its esterase activity and ability to cleave p-nitrophenyl acetate. Maximum enzyme activation occurred at an MT-2:apo-CA molar ratio of 1, implying the release of a single atom of Zn from MT-2. Preincubation of (67)Zn(7)-MT-2 with an excess of oxidized glutathione (GSSG) increased metal donation fourfold, whereas reduced glutathione (GSH) inhibited donation by approximately 50%. By using multiple recipient and donor proteins having different stable isotopic signatures, the technique has the potential for quantitatively studying the kinetic and thermodynamic aspects of Zn transfer between numerous competing ligands in vitro, an important first step toward understanding the regulatory role of this metal in protein functioning and cellular metabolism in vivo.
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Affiliation(s)
- Andrew Z Mason
- Department of Biological Sciences and Institute for Integrated Research in Materials, Environments, and Society, California State University, Long Beach, Long Beach, CA 90840, USA.
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40
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Krezel A, Hao Q, Maret W. The zinc/thiolate redox biochemistry of metallothionein and the control of zinc ion fluctuations in cell signaling. Arch Biochem Biophys 2007; 463:188-200. [PMID: 17391643 DOI: 10.1016/j.abb.2007.02.017] [Citation(s) in RCA: 167] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2006] [Revised: 02/08/2007] [Accepted: 02/09/2007] [Indexed: 11/29/2022]
Abstract
Free zinc ions are potent effectors of proteins. Their tightly controlled fluctuations ("zinc signals") in the picomolar range of concentrations modulate cellular signaling pathways. Sulfur (cysteine) donors generate redox-active coordination environments in proteins for the redox-inert zinc ion and make it possible for redox signals to induce zinc signals. Amplitudes of zinc signals are determined by the cellular zinc buffering capacity, which itself is redox-sensitive. In part by interfering with zinc and redox buffering, reactive species, drugs, toxins, and metal ions can elicit zinc signals that initiate physiological and pathobiochemical changes or lead to cellular injury when free zinc ions are sustained at higher concentrations. These interactions establish redox-inert zinc as an important factor in redox signaling. At the center of zinc/redox signaling are the zinc/thiolate clusters of metallothionein. They can transduce zinc and redox signals and thereby attenuate or amplify these signals.
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Affiliation(s)
- Artur Krezel
- Department of Preventive Medicine & Community Health, The University of Texas Medical Branch, Division of Human Nutrition, 700 Harborside Drive, Galveston, TX 77555, USA
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41
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Deb SC, Fukushima T. Metals in aquatic ecosystems: mechanisms of uptake, accumulation and release‐Ecotoxicological perspectives. ACTA ACUST UNITED AC 2007. [DOI: 10.1080/00207239908711212] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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42
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Formigari A, Santon A, Irato P. Efficacy of zinc treatment against iron-induced toxicity in rat hepatoma cell line H4-II-E-C3. Liver Int 2007; 27:120-7. [PMID: 17241390 DOI: 10.1111/j.1478-3231.2006.01389.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
OBJECTIVE In this study, we have attempted to explore the possible protection afforded by Zn with regard to its antioxidant potential properties in the iron-induced toxicity. METHODS Rat hepatoma cell line H4-II-E-C3 was treated with 150 muM ZnSO4, 200 muM FeSO4 or 150 muM ZnSO4+ 200 muM FeSO4 for 24 h. We studied the effect of metallothionein (MT), glutathione and metal (Fe and Zn) accumulation. We evaluated the levels of both MT-1 and MT-2 mRNAs, activities of antioxidant enzymes, and also determined the distribution of MT and cell death index. RESULTS The cotreatment produced highest levels of MT. Fe concentration was significantly lower in the Zn-Fe-treated cells compared with Fe-treated cells. In both Zn treatments, the superoxide dismutase/glutathione peroxidase ratio was similar to control. The cell death index was lower in the Zn-Fe-treated cells compared with Fe-treated cells. CONCLUSIONS Zn may act as antioxidant by competitive inhibition of iron uptake by the divalent metal transporter and/or by MT induction.
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Affiliation(s)
- A Formigari
- Department of Biology, University of Padova, Padova, Italy.
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43
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Blindauer CA, Razi MT, Campopiano DJ, Sadler PJ. Histidine ligands in bacterial metallothionein enhance cluster stability. J Biol Inorg Chem 2007; 12:393-405. [PMID: 17203314 DOI: 10.1007/s00775-006-0196-4] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2006] [Accepted: 11/15/2006] [Indexed: 11/26/2022]
Abstract
The cyanobacterial metallothionein (MT) SmtA is the prototype for bacterial MTs and protects against elevated levels of zinc. In contrast to mammalian MTs, bacterial MTs coordinate to metal ions not only via cysteine sulfurs, but unusually for MTs, also via histidine nitrogens. To investigate whether histidine coordination in these metal-sulfur clusters provides advantages over S-coordination only, we mutated the two metal-binding histidine residues in the cyanobacterial MT SmtA from Synechococcus PCC7942 to cysteines. We show that the mutant proteins are still capable of binding up to four zinc ions as is the wild-type protein. However, the mutations perturb protein folding and metal-binding dynamics. Interestingly, several homologues of SmtA also show variations in these two residues. We conclude that histidine residues in Synechococcus PCC7942 SmtA have a stabilising effect due to electrostatic interactions that impact on protein folding and metal cluster charge, and are involved in fine-tuning the reactivity of the bound metal ions.
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Affiliation(s)
- Claudia A Blindauer
- School of Chemistry, University of Edinburgh, West Mains Road, Edinburgh, EH9 3JJ, UK.
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44
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Childers M, Eckel G, Himmel A, Caldwell J. A new model of cystic fibrosis pathology: Lack of transport of glutathione and its thiocyanate conjugates. Med Hypotheses 2007; 68:101-12. [PMID: 16934416 DOI: 10.1016/j.mehy.2006.06.020] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2006] [Accepted: 06/08/2006] [Indexed: 01/22/2023]
Abstract
Many of the symptoms of cystic fibrosis are not explained by the current disease mechanisms. Therefore, the authors conducted an extensive literature review and present a new model of cystic fibrosis pathology, which is the culmination of this research. Understanding that the cystic fibrosis transmembrane conductance regulator (CFTR) is responsible for glutathione (GSH) transport, the authors hypothesize that mutations of the CFTR, which create abnormal GSH transport, will lead to aberrations of GSH levels in both the intracellular as well as the extracellular milieu. These alterations in normal cellular GSH levels affect the redox state of the cell, thereby affecting the intracellular stress protein, metallothionein. The authors describe how this disruption of the redox state caused by excess cellular GSH, will naturally prevent the delivery of zinc as a cofactor for various enzymatic processes, and how these disruptions in normal redox may cause alterations in both humoral and cell-mediated immunity. Moreover, the symptom of thick sticky mucus in these patients might be explained through the understanding that oversulfation of mucus is a direct result of elevated cellular GSH and cysteine. The issues of hyperinflammation, altered pH and the imbalance of fatty acids that are typical in cystic fibrosis are addressed-all of which may also be linked to disruptions in GSH homeostasis. Additionally, this new model of cystic fibrosis pathology, clarifies the relationship between the CFTR and the multi-drug resistance proteins, and the lack of cell-mediated immunity by predicting that the substrate of these proteins is a glutathione adduct of thiocyanate. Finally, a new therapeutic strategy by using isothiocyanates to rectify the GSH imbalance and restore the immune system is suggested for the treatment of cystic fibrosis patients.
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Affiliation(s)
- Melanie Childers
- Share International Foundation, 1720 205th Pl NE, Sammamish, WA 98074, USA.
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45
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Bourdineaud JP, Baudrimont M, Gonzalez P, Moreau JL. Challenging the model for induction of metallothionein gene expression. Biochimie 2006; 88:1787-92. [PMID: 16935407 DOI: 10.1016/j.biochi.2006.07.021] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2006] [Accepted: 07/26/2006] [Indexed: 11/24/2022]
Abstract
Metallothioneins (MTs) are low-molecular-weight, cysteine-rich metal-binding proteins found in a wide variety of organisms including bacteria, fungi and all eukaryotic plant and animal species. MTs bind essential and non-essential heavy metals. In mammalian cells MT genes are highly inducible by many heavy metals including Zn, Cd, Hg, and Cu. Aquatic systems are contaminated by different pollutants, including metals, as a result of man's activities. Bivalve molluscs are known to accumulate high concentrations of heavy metals in their tissue and are widely used as bioindicators for pollution in marine and freshwater environments, with MTs frequently used as a valuable marker of metal contamination. We here describe the MT isoform gene expression patterns of marine and freshwater molluscs and fish species after Cd or Zn contamination. Contamination was carried out at a river site polluted by a zinc ore extraction plant or in the laboratory at low, environmentally relevant metal concentrations. A comparison for each species based on the accumulated MT protein levels often shows discrepancies between gene expression and protein level. In addition, several differences observed in the pattern of MT gene expression between mollusc and mammalian species enable us to discuss and challenge a model for the induction of MT gene expression.
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Affiliation(s)
- J-P Bourdineaud
- Laboratoire d'Ecophysiologie et d'Ecotoxicologie des Systèmes Aquatiques (LEESA), Université Bordeaux-1, UMR CNRS 5805, place du Docteur-Peyneau, 33120 Arcachon, France.
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46
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Abstract
The biologic function of metallothionein (MT) has been a perplexing topic ever since the discovery of this protein. Many studies have suggested that MT plays a role in the homeostasis of essential metals such as zinc and copper, detoxification of toxic metals such as cadmium, and protection against oxidative stress. However, mechanistic insights into the actions of MT have not been adequately achieved. MT contains high levels of sulfur. The mutual affinity of sulfur and transition metals makes the binding of these metals to MT thermodynamically stable. Under physiologic conditions, zinc-MT is the predominant form of the metal-binding protein. The recognition of the redox regulation of zinc release from or binding to MT provides an alternate perspective on biologic function of MT. Oxidation of the thiolate cluster by a number of mild cellular oxidants causes zinc release and formation of MT-disulfide (or thionin if all metals are released from MT, but this is unlikely to occur in vivo), which have been demonstrated in vivo. Therefore, the thermodynamic stability of zinc binding makes MT an ideal zinc reservoir in vivo, and the redox regulation of zinc mobilization enables MT function in zinc homeostasis. MT-disulfide can be reduced by glutathione in the presence of selenium catalyst, restoring the capacity of the protein to bind zinc. This MT redox cycle may play a crucial role in MT biologic function. It may link to the homeostasis of essential metals, detoxification of toxic metals and protection against oxidative stress.
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Affiliation(s)
- Y James Kang
- Department of Medicine, University of Louisville School of Medicine, 511 S. Floyd Street, MDR 530, Louisville, KY 40202, USA.
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Wakida K, Morimoto N, Shimazawa M, Hozumi I, Nagase H, Inuzuka T, Hara H. Cilostazol reduces ischemic brain damage partly by inducing metallothionein-1 and -2. Brain Res 2006; 1116:187-93. [PMID: 16952340 DOI: 10.1016/j.brainres.2006.07.125] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2006] [Revised: 07/26/2006] [Accepted: 07/27/2006] [Indexed: 11/26/2022]
Abstract
The neuroprotective effect of cilostazol, an antiplatelet drug, was examined after 24 h permanent middle cerebral artery (MCA) occlusion in mice, and explored the possible underlying mechanism by examining metallothionein (MT)-1 and -2 induction in vivo. Cilostazol (30 mg/kg) was intraperitoneally administered at 12 h before, 1 h before, and just after MCA occlusion. Mice were euthanized at 24 h after the occlusion, and the neuronal damage was evaluated using 2,3,5-triphenyltetrazolium chloride (TTC) staining. Cilostazol significantly reduced the infarct area and volume, especially in the cortex. Real-time RT-PCR revealed increased mRNA expressions for MT-1 and -2 in the cortex of normal brains at 6 h after cilostazol treatment without MCA occlusion. MT-1 and -2 immunoreactivity was also increased in the cortex of such mice, and this immunoreactivity was observed in the ischemic hemisphere at 24 h after MCA occlusion (without cilostazol treatment). The strongest MT-1 and -2 immunoreactivity was detected in MCA-occlused mice treated with cilostazol [in the peri-infarct zone of the cortex (penumbral zone)]. These findings indicate that cilostazol has neuroprotective effects in vivo against permanent focal cerebral ischemia, especially in the penumbral zone in the cortex, and that MT-1 and -2 may be partly responsible for these neuroprotective effects.
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Affiliation(s)
- K Wakida
- Department of Biofunctional Molecules, Gifu Pharmaceutical University, 5-6-1 Mitahora-higashi, Gifu 502-8585, Japan
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Abstract
Hepatocytes in adults are in a nonproliferative state but they have high capacity to regenerate within few hours after an injury. After partial hepatectomy or chemical injury, hepatocytes undergo a synchronized multistep process consisting of priming/initiation, proliferation, and termination. These distinct steps are essential for restoring the structure and functions of liver. The mechanisms involved in each of these steps of regeneration are well documented from various laboratories and are described in several reviews. We briefly describe these steps and the involvement of various cytokines and growth factors for cell regeneration in this short review. Liver cell regeneration may also involve stem cell proliferation. The regenerating cells require large amounts of zinc within a short time, and this requirement is met by induction of a zinc and copper binding protein, metallothionein (MT), during the priming step, soon after an injury. There are several reports on the transfer of zinc from MT to various metalloenzymes and transcription factors. Genetically modified mouse models have been used to study the involvement of interleukin (IL)-6 and tumor necrosis factor (TNF)-alpha in cell regeneration. The use of an MT-knockout mouse has enabled us to investigate the specific role of MT in liver regeneration after partial hepatectomy, chemical injury, and fibrosis. Several studies have suggested a defective liver regeneration after an injury in MT-knockout mice. There is cumulative evidence that indicates an essential role for MT in liver cell regeneration.
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Affiliation(s)
- M George Cherian
- Department of Pathology, University of Western Ontario, London, Ontario N6A 5C1, Canada.
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Ostrakhovitch EA, Olsson PE, Jiang S, Cherian MG. Interaction of metallothionein with tumor suppressor p53 protein. FEBS Lett 2006; 580:1235-8. [PMID: 16442532 DOI: 10.1016/j.febslet.2006.01.036] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2005] [Accepted: 01/12/2006] [Indexed: 11/20/2022]
Abstract
Previous reports have shown that metallothionein (MT) may modulate p53 activity through zinc exchange. However, little is known on a direct interaction between MT and p53 in cells. The results demonstrate an interaction between MT and p53 can occur in vitro. The complex between MT and p53 was observed in breast cancer epithelial cells with both wild and inactive type of p53. Furthermore, it was shown that wt-p53 was preferentially associated with Apo-MT. Our data suggest that co-expression of MT and p53 and their complex formation in tumor cells may be involved in regulation of apoptosis in these cells.
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Affiliation(s)
- Elena A Ostrakhovitch
- Department of Pathology, University of Western Ontario, London, Ont., Canada N6A 5C1.
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50
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Feng W, Cai J, Pierce WM, Franklin RB, Maret W, Benz FW, Kang YJ. Metallothionein transfers zinc to mitochondrial aconitase through a direct interaction in mouse hearts. Biochem Biophys Res Commun 2005; 332:853-8. [PMID: 15913554 DOI: 10.1016/j.bbrc.2005.04.170] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2005] [Accepted: 04/29/2005] [Indexed: 10/25/2022]
Abstract
Previous studies have shown that in a cell-free system, metallothionein (MT) releases zinc when the environment becomes oxidized and the released zinc is transferred to a zinc-binding protein if such a protein is present. However, it is unknown whether and how zinc transfers from MT to other proteins in vivo. The present study was undertaken to test the hypothesis that if zinc transfer from MT to other proteins occurs in vivo, the transfer would proceed through a direct interaction between MT and a specific group of proteins. The heart extract obtained from MT-null mice was incubated with 65Zn-MT or 65ZnCl2 and the proteins receiving 65Zn were separated by blue-native PAGE (BN-PAGE) or sodium dodecyl sulfate-PAGE (SDS-PAGE), and detected by autoradiography. A unique 65Zn-binding band was observed from the 65Zn-MT-incubated, but not the 65ZnCl2-incubated preparation. The analysis using matrix assisted laser desorption/ionization-time-of-flight (MALDI-TOF) mass spectrometry revealed that mitochondrial aconitase (m-aconitase) was among the proteins accepting Zn directly from Zn-MT. The m-aconitase, not the cytosolic aconitase (c-aconitase), was co-immunoprecipitated with MT. This study demonstrates that MT transfers zinc to m-aconitase through a direct interaction.
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Affiliation(s)
- Wenke Feng
- Department of Medicine, University of Louisville School of Medicine, Louisville, KY 40202, USA
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