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Vogelauer M, Cheng C, Karimian A, Iranpour HG, Kurdistani SK. Zinc is Essential for the Copper Reductase Activity of Yeast Nucleosomes. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.14.557765. [PMID: 37745536 PMCID: PMC10515886 DOI: 10.1101/2023.09.14.557765] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 09/26/2023]
Abstract
The histone H3-H4 tetramer is a copper reductase enzyme, facilitating the production of cuprous (Cu1+) ions for distribution to copper-dependent enzymes. It was, however, unknown if this enzymatic activity occurred within nucleosomes. To investigate this, we obtained native nucleosomes from Saccharomyces cerevisiae using micrococcal nuclease digestion of chromatin in isolated nuclei and ion-exchange chromatographic purification. The purified nucleosomal fragments robustly reduced Cu2+ to Cu1+ ions, with the optimal activity dependent on the presence of zinc ions. Mutation of the histone H3 histidine 113 (H3H113) residue at the active site substantially reduced the enzymatic activity of nucleosomes, underscoring the catalytic role of histone H3. Consistently, limiting zinc ions reduced intracellular Cu1+ levels and compromised growth, phenotypes that were mitigated by genetically enhancing the copper reductase activity of histone H3. These results indicate that yeast nucleosomes possess copper reductase activity, suggesting that the fundamental unit of eukaryotic chromatin is an enzyme complex.
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Affiliation(s)
- Maria Vogelauer
- Department of Biological Chemistry, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Chen Cheng
- Department of Biological Chemistry, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Ansar Karimian
- Department of Biological Chemistry, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Hooman Golshan Iranpour
- Department of Biological Chemistry, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Siavash K. Kurdistani
- Department of Biological Chemistry, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90095, USA
- Department of Pathology and Laboratory Medicine, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90095, USA
- Molecular Biology Institute, University of California Los Angeles, Los Angeles, CA 90095, USA
- Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90095, USA
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Pillars and Gaps of S-Nitrosylation-Dependent Epigenetic Regulation in Physiology and Cancer. Life (Basel) 2021; 11:life11121424. [PMID: 34947954 PMCID: PMC8704633 DOI: 10.3390/life11121424] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Revised: 12/13/2021] [Accepted: 12/15/2021] [Indexed: 11/17/2022] Open
Abstract
Nitric oxide (NO) is a diffusible signaling molecule produced by three isoforms of nitric oxide synthase, which release NO during the metabolism of the amino acid arginine. NO participates in pathophysiological responses of many different tissues, inducing concentration-dependent effect. Indeed, while low NO levels generally have protective effects, higher NO concentrations induce cytotoxic/cytostatic actions. In recent years, evidences have been accumulated unveiling S-nitrosylation as a major NO-dependent post-translational mechanism ruling gene expression. S-nitrosylation is a reversible, highly regulated phenomenon in which NO reacts with one or few specific cysteine residues of target proteins generating S-nitrosothiols. By inducing this chemical modification, NO might exert epigenetic regulation through direct effects on both DNA and histones as well as through indirect actions affecting the functions of transcription factors and transcriptional co-regulators. In this light, S-nitrosylation may also impact on cancer cell gene expression programs. Indeed, it affects different cell pathways and functions ranging from the impairment of DNA damage repair to the modulation of the activity of signal transduction molecules, oncogenes, tumor suppressors, and chromatin remodelers. Nitrosylation is therefore a versatile tool by which NO might control gene expression programs in health and disease.
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Affiliation(s)
- Johannes Rudolph
- Department of Biochemistry, University of Colorado at Boulder, Boulder, CO, USA
| | - Karolin Luger
- Department of Biochemistry, University of Colorado at Boulder, Boulder, CO, USA
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Attar N, Campos OA, Vogelauer M, Cheng C, Xue Y, Schmollinger S, Salwinski L, Mallipeddi NV, Boone BA, Yen L, Yang S, Zikovich S, Dardine J, Carey MF, Merchant SS, Kurdistani SK. The histone H3-H4 tetramer is a copper reductase enzyme. Science 2020; 369:59-64. [PMID: 32631887 PMCID: PMC7842201 DOI: 10.1126/science.aba8740] [Citation(s) in RCA: 53] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Accepted: 05/13/2020] [Indexed: 12/16/2022]
Abstract
Eukaryotic histone H3-H4 tetramers contain a putative copper (Cu2+) binding site at the H3-H3' dimerization interface with unknown function. The coincident emergence of eukaryotes with global oxygenation, which challenged cellular copper utilization, raised the possibility that histones may function in cellular copper homeostasis. We report that the recombinant Xenopus laevis H3-H4 tetramer is an oxidoreductase enzyme that binds Cu2+ and catalyzes its reduction to Cu1+ in vitro. Loss- and gain-of-function mutations of the putative active site residues correspondingly altered copper binding and the enzymatic activity, as well as intracellular Cu1+ abundance and copper-dependent mitochondrial respiration and Sod1 function in the yeast Saccharomyces cerevisiae The histone H3-H4 tetramer, therefore, has a role other than chromatin compaction or epigenetic regulation and generates biousable Cu1+ ions in eukaryotes.
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Affiliation(s)
- Narsis Attar
- Department of Biological Chemistry, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90095, USA
- Molecular Biology Institute, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Oscar A Campos
- Department of Biological Chemistry, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90095, USA
- Molecular Biology Institute, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Maria Vogelauer
- Department of Biological Chemistry, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Chen Cheng
- Department of Biological Chemistry, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Yong Xue
- Department of Biological Chemistry, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Stefan Schmollinger
- Institute for Genomics and Proteomics, Department of Chemistry and Biochemistry, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Lukasz Salwinski
- Department of Biological Chemistry, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90095, USA
- UCLA-DOE Institute for Genomics and Proteomics, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Nathan V Mallipeddi
- Department of Biological Chemistry, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Brandon A Boone
- Department of Biological Chemistry, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Linda Yen
- Department of Molecular, Cell, and Developmental Biology, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Sichen Yang
- Department of Biological Chemistry, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Shannon Zikovich
- Department of Biological Chemistry, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Jade Dardine
- Department of Biological Chemistry, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Michael F Carey
- Department of Biological Chemistry, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90095, USA
- Molecular Biology Institute, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Sabeeha S Merchant
- Institute for Genomics and Proteomics, Department of Chemistry and Biochemistry, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Siavash K Kurdistani
- Department of Biological Chemistry, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90095, USA.
- Molecular Biology Institute, University of California Los Angeles, Los Angeles, CA 90095, USA
- Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90095, USA
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Bittarello AC, Vieira JCS, Braga CP, da Cunha Bataglioli I, de Oliveira G, Rocha LC, Zara LF, Buzalaf MAR, de Oliveira LCS, Adamec J, de Magalhães Padilha P. Metalloproteomic approach of mercury-binding proteins in liver and kidney tissues of Plagioscion squamosissimus (corvina) and Colossoma macropomum (tambaqui) from Amazon region: Possible identification of mercury contamination biomarkers. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 711:134547. [PMID: 31812405 DOI: 10.1016/j.scitotenv.2019.134547] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Revised: 09/16/2019] [Accepted: 09/17/2019] [Indexed: 06/10/2023]
Abstract
Fish is an important source of protein, vitamins, and minerals. However, this food is also a major source of human exposure to toxic contaminants such as mercury. Thus, this paper aimed to evaluate mercury-binding proteins for possible application as biomarkers of mercury contamination in hepatic and renal tissues of Plagioscion squamosissimus (carnivorous fish) and Colossoma macropomum (omnivorous fish) from the Amazon region using metalloproteomic approach. The proteome of hepatic and renal tissues of fish species was separated by two-dimensional polyacrylamide gel electrophoresis (2D-PAGE), and the mercury concentrations in protein spots were determined by graphite furnace atomic absorption spectrometry (GFAAS). Finally, the protein spots associated to mercury were characterized by electrospray ionization mass spectrometry (ESI-MS/MS). The activity of antioxidant enzymes (SOD, CAT, GPx, and GST) and lipid peroxidation (LPO) were also determined. The results showed that the highest concentrations of mercury were found in the carnivorous species (P. squamosissimus) and that the accumulation pattern of this metal was higher in hepatic tissues than in renal tissues for both species. A tendency was observed for greater enzymatic activity in the hepatic and renal tissues of P. squamosissimus, the species with the highest concentration of mercury. Only GPx activity in the kidney and GST in the liver were lower for the P. squamosissimus species, and this finding can be explained by the interaction of mercury with these enzymes. The data obtained by ESI-MS/MS allowed for the characterization of the protein spots associated to mercury, revealing proteins involved in energy metabolism, biomolecules transport, protein synthesis and degradation, cell differentiation, gene regulation, and the antioxidant system. The results obtained in the present study can contribute to understanding the physiological processes underlying mercury toxicity and have provided new perspectives on possible candidates for mercury contamination biomarkers in fish.
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Affiliation(s)
- Alis Correia Bittarello
- São Paulo State University (UNESP), School of Veterinary Medicine and Animal Science, Botucatu, Brazil
| | - José Cavalcante Souza Vieira
- São Paulo State University (UNESP), Institute of Biosciences, Botucatu, Brazil; Institute of Chemistry (INQUI), Federal University of Mato Grosso do Sul, Campo Grande (UFMS), Brazil.
| | | | | | | | - Leone Campos Rocha
- São Paulo State University (UNESP), School of Veterinary Medicine and Animal Science, Botucatu, Brazil
| | - Luiz Fabrício Zara
- University of Brasília (UNB), College of Planaltina, Distrito Federal, Brazil
| | | | | | - Jiri Adamec
- University of Nebraska (UNL), Lincoln, United States
| | - Pedro de Magalhães Padilha
- São Paulo State University (UNESP), School of Veterinary Medicine and Animal Science, Botucatu, Brazil; São Paulo State University (UNESP), Institute of Biosciences, Botucatu, Brazil.
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Kamnev AA, Tugarova AV. Sample treatment in Mössbauer spectroscopy for protein-related analyses: Nondestructive possibilities to look inside metal-containing biosystems. Talanta 2017; 174:819-837. [PMID: 28738659 DOI: 10.1016/j.talanta.2017.06.057] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Revised: 06/01/2017] [Accepted: 06/19/2017] [Indexed: 01/07/2023]
Abstract
In this review, the unique possibilities are considered of the 57Fe transmission (TMS) and 57Co emission (EMS) variants of Mössbauer (nuclear γ-resonance) spectroscopy as nondestructive techniques with minimal sample preparation/treatment and a significant analytical potential, with a focus on the analysis of cation-binding sites in metalloproteins. The techniques are shown to provide unique structural and quantitative information on the coordination microenvironment, the chemical state and transformations of the Mössbauer nuclides in sophisticated metal-containing proteins, including those within complicated supramolecular structures, and in microbial cells or tissues. Recent representative examples of analyses of Fe-containing proteins by 57Fe TMS are briefly discussed, along with the newly emerging data on using 57Co EMS for probing the structural organisation of 57Co-doped cation-binding sites in sophisticated biocomplexes including metalloenzymes. Finally, some rare or exotic applications of Mössbauer spectroscopy (including the synchrotron-based methodology) in protein-related studies are outlined.
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Affiliation(s)
- Alexander A Kamnev
- Laboratory of Biochemistry, Institute of Biochemistry and Physiology of Plants and Microorganisms, Russian Academy of Sciences, 13 Prosp. Entuziastov, 410049, Saratov, Russia.
| | - Anna V Tugarova
- Laboratory of Biochemistry, Institute of Biochemistry and Physiology of Plants and Microorganisms, Russian Academy of Sciences, 13 Prosp. Entuziastov, 410049, Saratov, Russia
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Kamnev AA, Perfiliev YD, Kulikov LA, Tugarova AV, Kovács K, Homonnay Z, Kuzmann E. Cobalt(II) complexation with small biomolecules as studied by 57Co emission Mössbauer spectroscopy. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2017; 172:77-82. [PMID: 27130827 DOI: 10.1016/j.saa.2016.04.031] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2015] [Revised: 03/29/2016] [Accepted: 04/08/2016] [Indexed: 06/05/2023]
Abstract
In the emission (57Co) variant of Mössbauer spectroscopy (EMS), the 57Co radionuclide (with a half-life of 9months) is used that undergoes a nuclear decay 57Co→57Fe via electron capture followed by the emission of a γ-quantum, the energy of which is modified by the chemical state and the close coordination environment of the parent 57Co atom. While EMS has been used largely in materials science and nuclear chemistry, its high sensitivity can also be of great advantage in revealing fine structural features and for speciation analysis of biological complexes, whenever the 57Co2+ cation can be used directly as the coordinating metal or as a substitute for native cobalt or other metal ions. As such EMS applications are yet rare, in order to reliably interpret emission spectra of sophisticated 57Co2+-doped biosystems, model EMS studies of simple cobalt biocomplexes are necessary. In this work, EMS spectroscopic data are analysed and discussed for 57Co2+ complexes with a range of small biomolecules of different structures, including 4-n-hexylresorcinol, homoserine lactone and a few amino acids (spectra measured in rapidly frozen dilute aqueous solutions or in the dried state at T=80K). The EMS data obtained are discussed with regard to the available literature data related to the coordination modes of the biocomplexes under study.
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Affiliation(s)
- Alexander A Kamnev
- Laboratory of Biochemistry, Institute of Biochemistry and Physiology of Plants and Microorganisms, Russian Academy of Sciences, 410049 Saratov, Russia.
| | - Yurii D Perfiliev
- Laboratory of Nuclear Chemistry Techniques, Department of Radiochemistry, Faculty of Chemistry, M.V. Lomonosov Moscow State University, 119992 Moscow, Russia
| | - Leonid A Kulikov
- Laboratory of Nuclear Chemistry Techniques, Department of Radiochemistry, Faculty of Chemistry, M.V. Lomonosov Moscow State University, 119992 Moscow, Russia
| | - Anna V Tugarova
- Laboratory of Biochemistry, Institute of Biochemistry and Physiology of Plants and Microorganisms, Russian Academy of Sciences, 410049 Saratov, Russia
| | - Krisztina Kovács
- Laboratory of Nuclear Chemistry, Department of Analytical Chemistry, Institute of Chemistry, Loránd Eötvös University, H-1117 Budapest, Hungary
| | - Zoltán Homonnay
- Laboratory of Nuclear Chemistry, Department of Analytical Chemistry, Institute of Chemistry, Loránd Eötvös University, H-1117 Budapest, Hungary
| | - Ernő Kuzmann
- Laboratory of Nuclear Chemistry, Department of Analytical Chemistry, Institute of Chemistry, Loránd Eötvös University, H-1117 Budapest, Hungary
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Bresson C, Darolles C, Carmona A, Gautier C, Sage N, Roudeau S, Ortega R, Ansoborlo E, Malard V. Cobalt chloride speciation, mechanisms of cytotoxicity on human pulmonary cells, and synergistic toxicity with zinc. Metallomics 2013; 5:133-43. [PMID: 23505636 DOI: 10.1039/c3mt20196a] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Cobalt is used in numerous industrial sectors, leading to occupational diseases, particularly by inhalation. Cobalt-associated mechanisms of toxicity are far from being understood and information that could improve knowledge in this area is required. We investigated the impact of a soluble cobalt compound, CoCl(2)·6H(2)O, on the BEAS-2B lung epithelial cell line, as well as its impact on metal homeostasis. Cobalt speciation in different culture media, in particular soluble and precipitated cobalt species, was investigated via theoretical and analytical approaches. The cytotoxic effects of cobalt on the cells were assessed. Upon exposure of BEAS-2B cells to cobalt, intracellular accumulation of cobalt and zinc was demonstrated using direct in situ microchemical analysis based on ion micro-beam techniques and analysis after cell lysis by inductively coupled plasma mass spectrometry (ICP-MS). Microchemical imaging revealed that cobalt was rather homogeneously distributed in the nucleus and in the cytoplasm whereas zinc was more abundant in the nucleus. The modulation of zinc homeostasis led to the evaluation of the effect of combined cobalt and zinc exposure. In this case, a clear synergistic increase in toxicity was observed as well as a substantial increase in zinc content within cells. Western blots performed under the same coexposure conditions revealed a decrease in ZnT1 expression, suggesting that cobalt could inhibit zinc release through the modulation of ZnT1. Overall, this study highlights the potential hazard to lung function, of combined exposure to cobalt and zinc.
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Affiliation(s)
- Carole Bresson
- Laboratoire de développement Analytique Nucléaire, Isotopique et Elémentaire, Gif-sur-Yvette, France.
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Kamnev AA, Tugarova AV, Kovács K, Kuzmann E, Biró B, Tarantilis PA, Homonnay Z. Emission (57Co) Mössbauer spectroscopy as a tool for probing speciation and metabolic transformations of cobalt(II) in bacterial cells. Anal Bioanal Chem 2012; 405:1921-7. [DOI: 10.1007/s00216-012-6370-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2012] [Revised: 08/18/2012] [Accepted: 08/20/2012] [Indexed: 11/25/2022]
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Wolford JL, Chishti Y, Jin Q, Ward J, Chen L, Vogt S, Finney L. Loss of pluripotency in human embryonic stem cells directly correlates with an increase in nuclear zinc. PLoS One 2010; 5:e12308. [PMID: 20808840 PMCID: PMC2924898 DOI: 10.1371/journal.pone.0012308] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2010] [Accepted: 07/21/2010] [Indexed: 01/02/2023] Open
Abstract
The pluripotency of human embryonic stem cells (hESCs) is important to investigations of early development and to cell replacement therapy, but the mechanism behind pluripotency is incompletely understood. Zinc has been shown to play a key role in differentiation of non-pluripotent cell types, but here its role in hESCs is directly examined. By mapping the distribution of metals in hESCs at high resolution by x-ray fluorescence microprobe (XFM) and by analyzing subcellular metal content, we have found evidence that loss of pluripotency is directly correlated with an increase in nuclear zinc. Zinc elevation not only redefines our understanding of the mechanisms that support pluripotency, but also may act as a biomarker and an intervention point for stem cell differentiation.
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Affiliation(s)
- Janet L. Wolford
- Biosciences Division, Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois, United States of America
| | - Yasmin Chishti
- Biosciences Division, Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois, United States of America
| | - Qiaoling Jin
- Biosciences Division, Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois, United States of America
| | - Jesse Ward
- X-ray Science Division, Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois, United States of America
| | - Liaohai Chen
- Biosciences Division, Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois, United States of America
| | - Stefan Vogt
- X-ray Science Division, Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois, United States of America
| | - Lydia Finney
- Biosciences Division, Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois, United States of America
- X-ray Science Division, Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois, United States of America
- * E-mail:
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Illi B, Colussi C, Grasselli A, Farsetti A, Capogrossi MC, Gaetano C. NO sparks off chromatin: tales of a multifaceted epigenetic regulator. Pharmacol Ther 2009; 123:344-52. [PMID: 19464317 DOI: 10.1016/j.pharmthera.2009.05.003] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2009] [Accepted: 05/11/2009] [Indexed: 10/20/2022]
Abstract
The discovery of nitric oxide (NO) revealed its ambiguous nature, which is related to its pleiotropic activities that control the homeostasis of every organism from bacteria to mammals in several physiological and pathological situations. The wide range of action of NO basically depends on two features: 1) the variety of chemical reactions depending on NO, and 2) the differential cellular responses elicited by distinct NO concentrations. Despite the increasing body of knowledge regarding its chemistry, biology and NO-dependent signaling pathways, little information is available on the nuclear actions of NO in terms of gene expression regulation. Indeed, studies of a putative role for this diatomic compound in regulating chromatin remodeling are still in their infancy. Only recently has the role of NO in epigenetics emerged, and some of its putative epigenetic properties are still only hypothetical. In the present review, we discuss the current evidence for NO-related mechanisms of epigenetic gene expression regulation. We link some of the well known NO chemical reactions and metabolic processes (e.g., S-nitrosylation of thiols, tyrosine nitration, cGMP production) to chromatin modification and address the most recent, striking hypothesis about NO and the control of chromosomes structure.
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Affiliation(s)
- Barbara Illi
- Laboratorio di Biologia Vascolare e Medicina Rigenerativa, Centro Cardiologico Monzino-IRCCS, Milan, Italy
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Colvin RA, Bush AI, Volitakis I, Fontaine CP, Thomas D, Kikuchi K, Holmes WR. Insights into Zn2+homeostasis in neurons from experimental and modeling studies. Am J Physiol Cell Physiol 2008; 294:C726-42. [DOI: 10.1152/ajpcell.00541.2007] [Citation(s) in RCA: 159] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
To understand the mechanisms of neuronal Zn2+homeostasis better, experimental data obtained from cultured cortical neurons were used to inform a series of increasingly complex computational models. Total metals (inductively coupled plasma-mass spectrometry), resting metallothionein,65Zn2+uptake and release, and intracellular free Zn2+levels using ZnAF-2F were determined before and after neurons were exposed to increased Zn2+, either with or without the addition of a Zn2+ionophore (pyrithione) or metal chelators [EDTA, clioquinol (CQ), and N, N, N′, N′-tetrakis(2-pyridylmethyl)ethylenediamine]. Three models were tested for the ability to match intracellular free Zn2+transients and total Zn2+content observed under these conditions. Only a model that incorporated a muffler with high affinity for Zn2+, trafficking Zn2+to intracellular storage sites, was able to reproduce the experimental results, both qualitatively and quantitatively. This “muffler model” estimated the resting intracellular free Zn2+concentration to be 1.07 nM. If metallothionein were to function as the exclusive cytosolic Zn2+muffler, the muffler model predicts that the cellular concentration required to match experimental data is greater than the measured resting concentration of metallothionein. Thus Zn2+buffering in resting cultured neurons requires additional high-affinity cytosolic metal binding moieties. Added CQ, as low as 1 μM, was shown to selectively increase Zn2+influx. Simulations reproduced these data by modeling CQ as an ionophore. We conclude that maintenance of neuronal Zn2+homeostasis, when challenged with Zn2+loads, relies heavily on the function of a high-affinity muffler, the characteristics of which can be effectively studied with computational models.
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