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Monzel AS, Enríquez JA, Picard M. Multifaceted mitochondria: moving mitochondrial science beyond function and dysfunction. Nat Metab 2023; 5:546-562. [PMID: 37100996 PMCID: PMC10427836 DOI: 10.1038/s42255-023-00783-1] [Citation(s) in RCA: 66] [Impact Index Per Article: 66.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Accepted: 03/10/2023] [Indexed: 04/28/2023]
Abstract
Mitochondria have cell-type specific phenotypes, perform dozens of interconnected functions and undergo dynamic and often reversible physiological recalibrations. Given their multifunctional and malleable nature, the frequently used terms 'mitochondrial function' and 'mitochondrial dysfunction' are misleading misnomers that fail to capture the complexity of mitochondrial biology. To increase the conceptual and experimental specificity in mitochondrial science, we propose a terminology system that distinguishes between (1) cell-dependent properties, (2) molecular features, (3) activities, (4) functions and (5) behaviours. A hierarchical terminology system that accurately captures the multifaceted nature of mitochondria will achieve three important outcomes. It will convey a more holistic picture of mitochondria as we teach the next generations of mitochondrial biologists, maximize progress in the rapidly expanding field of mitochondrial science, and also facilitate synergy with other disciplines. Improving specificity in the language around mitochondrial science is a step towards refining our understanding of the mechanisms by which this unique family of organelles contributes to cellular and organismal health.
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Affiliation(s)
- Anna S Monzel
- Department of Psychiatry, Division of Behavioral Medicine, Columbia University Irving Medical Center, New York, NY, USA
| | - José Antonio Enríquez
- Centro Nacional de Investigaciones Cardiovasculares Carlos III, Madrid, Spain
- CIBER de Fragilidad y Envejecimiento Saludable (CIBERFES), Madrid, Spain
| | - Martin Picard
- Department of Psychiatry, Division of Behavioral Medicine, Columbia University Irving Medical Center, New York, NY, USA.
- Department of Neurology, H. Houston Merritt Center, Columbia Translational Neuroscience Initiative, Columbia University Irving Medical Center, New York, NY, USA.
- New York State Psychiatric Institute, New York, NY, USA.
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2
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Abstract
Ascorbic acid, as one of the basic exogenous vitamins, is known for its tremendous antioxidant properties. This review has been prepared to show not only the importance of ascorbic acid as a free radical scavenger, but also to summarize its antioxidant action based on other mechanisms, including activation of intracellular antioxidant systems. Ascorbic acid interacts with small molecule antioxidants, including tocopherol, glutathione and thioredoxin, but also can stimulate the biosynthesis and activation of antioxidant enzymes, such as superoxide dismutase, catalase or glutathione peroxidase. Moreover, ascorbic acid promotes the activity of several transcription factors (Nrf2, Ref-1, AP-1), which enables the expression of genes encoding antioxidant proteins. Additionally, it supports the action of other exogenous antioxidants, mainly polyphenols. In this connection, both DNA, protein and lipids are protected against oxidation. Although ascorbic acid has strong antioxidant properties, it can also have pro-oxidant effects in the presence of free transition metals. However, its role in prevention of DNA mutation and cellular apoptosis, especially in relation to cancer cells is controversial.
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Affiliation(s)
- Agnieszka Gęgotek
- Department of Inorganic and Analytical Chemistry, Medical University of Bialystok, Bialystok, Poland
| | - Elżbieta Skrzydlewska
- Department of Inorganic and Analytical Chemistry, Medical University of Bialystok, Bialystok, Poland.
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3
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Aumailley L, Bourassa S, Gotti C, Droit A, Lebel M. Vitamin C modulates the levels of several proteins of the mitochondrial complex III and its activity in the mouse liver. Redox Biol 2022; 57:102491. [PMID: 36179436 PMCID: PMC9520280 DOI: 10.1016/j.redox.2022.102491] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2022] [Revised: 09/09/2022] [Accepted: 09/22/2022] [Indexed: 11/19/2022] Open
Abstract
Ascorbate is a crucial antioxidant and essential cofactor of biosynthetic and regulatory enzymes. Unlike humans, mice can synthesize ascorbate thanks to the key enzyme gulonolactone oxidase (Gulo). In the present study, we used the Gulo-/- mouse model, which cannot synthesize their own ascorbate to determine the impact of this vitamin on the liver proteome of specific subcellular organelles. We performed label-free Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS) global quantitative proteomic profiling to identify and quantify proteins in microsomal enriched liver extracts (MEE) from Gulo-/- mice treated with 0-0.4% (w/v) ascorbate in drinking water until the age of four months. Using a principal component analysis on normalized and imputed data of the label-free protein quantifications, a sex-based difference in MEE proteome profiles was observed for all the different ascorbate treated mice. Suboptimal hepatic ascorbate concentrations affected the levels of more proteins and hence biochemical processes in females than in males. Nevertheless, Pearson correlation analyses revealed that the MS intensities of various proteins involved in complement activation inversely correlated with liver ascorbate concentrations in both Gulo-/- males and females. Moreover, the correlation analyses also indicated that several proteins in the mitochondrial complex III of the electron transport chain positively correlated with liver ascorbate concentrations in both Gulo-/- females and males. Consequently, the mitochondrial complex III activity in Gulo-/- female and male mice treated with suboptimal hepatic concentrations of ascorbate was significantly lower than Gulo-/- mice treated with optimal ascorbate concentration. Finally, the whole liver of ascorbate-deficient Gulo-/- mice exhibited lower ATP levels and increased reactive oxygen species. These findings provide new information on how ascorbate deficiency potentially induces mitochondrial dysfunction in the liver of mice.
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Affiliation(s)
- Lucie Aumailley
- Centre de recherche du CHU de Québec, Faculty of Medicine, Université Laval, Québec City, Québec, G1V 4G2, Canada
| | - Sylvie Bourassa
- Proteomics Platform, Centre de recherche du CHU de Québec, Faculty of Medicine, Université Laval, Québec City, Québec, G1V 4G2, Canada
| | - Clarisse Gotti
- Proteomics Platform, Centre de recherche du CHU de Québec, Faculty of Medicine, Université Laval, Québec City, Québec, G1V 4G2, Canada
| | - Arnaud Droit
- Centre de recherche du CHU de Québec, Faculty of Medicine, Université Laval, Québec City, Québec, G1V 4G2, Canada; Proteomics Platform, Centre de recherche du CHU de Québec, Faculty of Medicine, Université Laval, Québec City, Québec, G1V 4G2, Canada
| | - Michel Lebel
- Centre de recherche du CHU de Québec, Faculty of Medicine, Université Laval, Québec City, Québec, G1V 4G2, Canada.
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4
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Gęgotek A, Skrzydlewska E. Antioxidative and Anti-Inflammatory Activity of Ascorbic Acid. Antioxidants (Basel) 2022; 11:1993. [PMID: 36290716 PMCID: PMC9598715 DOI: 10.3390/antiox11101993] [Citation(s) in RCA: 31] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2022] [Revised: 09/30/2022] [Accepted: 10/05/2022] [Indexed: 07/24/2023] Open
Abstract
Ascorbic acid, as a one of the basic exogenous vitamins, occurs in the body in the form of ascorbate, known for its strong antioxidant and anti-inflammatory properties. The presented review shows not only the importance of ascorbate as a free radical scavenger but also summarizes its antioxidant action based on other mechanisms, including the activation of intracellular antioxidant systems and its effect on the NFκB/TNFα pathway and apoptosis. Ascorbate interacts with small-molecule antioxidants, including tocopherol, glutathione, and thioredoxin; it can also stimulate biosynthesis and the activation of antioxidant enzymes, such as superoxide dismutase, catalase, or glutathione peroxidase. Moreover, ascorbate promotes the activity of transcription factors (Nrf2, Ref-1, AP-1), which enables the expression of genes encoding antioxidant proteins. Additionally, it supports the action of other exogenous antioxidants, mainly polyphenols. In this regard, both DNA, proteins, and lipids are protected against oxidation, leading to an inflammatory reaction and even cell death. Although ascorbate has strong antioxidant properties, it can also have pro-oxidant effects in the presence of free transition metals. However, its role in the prevention of DNA mutation, inflammation, and cell apoptosis, especially in relation to cancer cells, is controversial.
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5
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Fujii J. Ascorbate is a multifunctional micronutrient whose synthesis is lacking in primates. J Clin Biochem Nutr 2021; 69:1-15. [PMID: 34376908 PMCID: PMC8325764 DOI: 10.3164/jcbn.20-181] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Accepted: 12/07/2020] [Indexed: 02/06/2023] Open
Abstract
Ascorbate (vitamin C) is an essential micronutrient in primates, and exhibits multiple physiological functions. In addition to antioxidative action, ascorbate provides reducing power to α-ketoglutarate-dependent non-heme iron dioxygenases, such as prolyl hydroxylases. Demethylation of histones and DNA with the aid of ascorbate results in the reactivation of epigenetically silenced genes. Ascorbate and its oxidized form, dehydroascorbate, have attracted interest in terms of their roles in cancer therapy. The last step in the biosynthesis of ascorbate is catalyzed by l-gulono-γ-lactone oxidase whose gene Gulo is commonly mutated in all animals that do not synthesize ascorbate. One common explanation for this deficiency is based on the increased availability of ascorbate from foods. In fact, pathways for ascorbate synthesis and the detoxification of xenobiotics by glucuronate conjugation share the metabolic processes up to UDP-glucuronate, which prompts another hypothesis, namely, that ascorbate-incompetent animals might have developed stronger detoxification systems in return for their lack of ability to produce ascorbate, which would allow them to cope with their situation. Here, we overview recent advances in ascorbate research and propose that an enhanced glucuronate conjugation reaction may have applied positive selection pressure on ascorbate-incompetent animals, thus allowing them to dominate the animal kingdom.
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Affiliation(s)
- Junichi Fujii
- Department of Biochemistry and Molecular Biology, Graduate School of Medical Science, Yamagata University, Yamagata 990-9585, Japan
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6
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Fiorani M, Guidarelli A, Cantoni O. Mitochondrial reactive oxygen species: the effects of mitochondrial ascorbic acid vs untargeted and mitochondria-targeted antioxidants. Int J Radiat Biol 2020; 97:1055-1062. [PMID: 31976796 DOI: 10.1080/09553002.2020.1721604] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
PREMISE Mitochondria represent critical sites for reactive oxygen species (ROS) production, which dependent on concentration is responsible for the regulation of both physiological and pathological processes. PURPOSE Antioxidants in mitochondria regulate the redox balance, prevent mitochondrial damage and dysfunction and maintain a physiological ROS-dependent signaling. The aim of the present review is to provide critical elements for addressing this issue in the context of various pharmacological approaches using antioxidants targeted or non-targeted to mitochondria. Furthermore, this review focuses on the mitochondrial antioxidant effects of ascorbic acid (AA), providing clues on the complexities associated with the cellular uptake and subcellular distribution of the vitamin. CONCLUSIONS Antioxidants that are not specifically targeted to mitochondria fail to accumulate in significant amounts in critical sites of mitochondrial ROS production and may eventually interfere with the ensuing physiological signaling. Mitochondria-targeted antioxidants are more effective, but are expected to interfere with the mitochondrial ROS-dependent physiologic signaling. AA promotes multiple beneficial effects in mitochondria. The complex regulation of vitamin C uptake in these organelles likely contributes to its versatile antioxidant response, thereby providing a central role to the vitamin for adequate control of mitochondrial dysfunction associated with increased mitochondrial ROS production.
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Affiliation(s)
- Mara Fiorani
- Department of Biomolecular Sciences, University of Urbino Carlo Bo, Urbino, Italy
| | - Andrea Guidarelli
- Department of Biomolecular Sciences, University of Urbino Carlo Bo, Urbino, Italy
| | - Orazio Cantoni
- Department of Biomolecular Sciences, University of Urbino Carlo Bo, Urbino, Italy
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7
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A screen of Crohn's disease-associated microbial metabolites identifies ascorbate as a novel metabolic inhibitor of activated human T cells. Mucosal Immunol 2019; 12:457-467. [PMID: 29695840 PMCID: PMC6202286 DOI: 10.1038/s41385-018-0022-7] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2017] [Revised: 01/17/2018] [Accepted: 02/27/2018] [Indexed: 02/06/2023]
Abstract
Microbial metabolites are an emerging class of mediators influencing CD4+ T-cell function. To advance the understanding of direct causal microbial factors contributing to Crohn's disease, we screened 139 predicted Crohn's disease-associated microbial metabolites for their bioactivity on human CD4+ T-cell functions induced by disease-associated T helper 17 (Th17) polarizing conditions. We observed 15 metabolites with CD4+ T-cell bioactivity, 3 previously reported, and 12 unprecedented. A deeper investigation of the microbe-derived metabolite, ascorbate, revealed its selective inhibition on activated human CD4+ effector T cells, including IL-17A-, IL-4-, and IFNγ-producing cells. Mechanistic assessment suggested the apoptosis of activated human CD4+ T cells associated with selective inhibition of energy metabolism. These findings suggest a substantial rate of relevant T-cell bioactivity among Crohn's disease-associated microbial metabolites, and evidence for novel modes of bioactivity, including targeting of T-cell energy metabolism.
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8
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Scalera V, Giangregorio N, De Leonardis S, Console L, Carulli ES, Tonazzi A. Characterization of a Novel Mitochondrial Ascorbate Transporter From Rat Liver and Potato Mitochondria. Front Mol Biosci 2018; 5:58. [PMID: 29998111 PMCID: PMC6028771 DOI: 10.3389/fmolb.2018.00058] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2018] [Accepted: 06/06/2018] [Indexed: 12/30/2022] Open
Abstract
The Mitochondrial Ascorbic Acid Transporter (MAT) from both rat liver and potato mitochondria has been reconstituted in proteoliposomes. The protein has a molecular mass in the range of 28–35 kDa and catalyzes saturable, temperature and pH dependent, unidirectional ascorbic acid transport. The transport activity is sodium independent and it is optimal at acidic pH values. It is stimulated by proton gradient, thus supporting that ascorbate is symported with H+. It is efficiently inhibited by the lysine reagent pyridoxal phosphate and it is not affected by inhibitors of other recognized plasma and mitochondrial membranes ascorbate transporters GLUT1(glucose transporter-1) or SVCT2 (sodium-dependent vitamin C transporter-2). Rat protein catalyzes a cooperative ascorbate transport, being involved two binding sites; the measured K0.5 is 1.5 mM. Taking into account the experimental results we propose that the reconstituted ascorbate transporter is not a GLUT or SVCT, since it shows different biochemical features. Data of potato transporter overlap the mammalian ones, except for the kinetic parameters non-experimentally measurable, thus supporting the MAT in plants fulfills the same transport role.
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Affiliation(s)
- Vito Scalera
- Department of Bioscience, Biotechnology and Biopharmaceutics, University of Bari, Bari, Italy
| | - Nicola Giangregorio
- Department of Bioscience, Biotechnology and Biopharmaceutics, University of Bari, Bari, Italy.,CNR-IBIOM (Institute of Biomembranes, Bioenergetics and Molecular Biotechnologies), Bari, Italy
| | | | - Lara Console
- Unit of Biochemistry and Molecular Biotechnology, Department DiBEST (Biologia, Ecologia, Scienze della Terra), University of Calabria, Rende, Italy
| | | | - Annamaria Tonazzi
- Department of Bioscience, Biotechnology and Biopharmaceutics, University of Bari, Bari, Italy.,CNR-IBIOM (Institute of Biomembranes, Bioenergetics and Molecular Biotechnologies), Bari, Italy
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9
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Pshenichnyuk SA, Modelli A, Komolov AS. Interconnections between dissociative electron attachment and electron-driven biological processes. INT REV PHYS CHEM 2018. [DOI: 10.1080/0144235x.2018.1461347] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Affiliation(s)
- Stanislav A. Pshenichnyuk
- Institute of Molecule and Crystal Physics – Subdivision of the Ufa Research Centre of the Russian Academy of Sciences, Ufa, Russia
| | - Alberto Modelli
- Dipartimento di Chimica ‘G. Ciamician’, Università di Bologna, Bologna, Italy
- Centro Interdipartimentale di Ricerca in Scienze Ambientali, Ravenna, Italy
| | - Alexei S. Komolov
- Department of Solid State Electronics, St. Petersburg State University, St. Petersburg, Russia
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10
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Rouleau L, Antony AN, Bisetto S, Newberg A, Doria C, Levine M, Monti DA, Hoek JB. Synergistic effects of ascorbate and sorafenib in hepatocellular carcinoma: New insights into ascorbate cytotoxicity. Free Radic Biol Med 2016; 95:308-322. [PMID: 27036367 PMCID: PMC4867251 DOI: 10.1016/j.freeradbiomed.2016.03.031] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Revised: 03/24/2016] [Accepted: 03/28/2016] [Indexed: 12/15/2022]
Abstract
We investigated the mechanism of selective ascorbate-induced cytotoxicity in tumor cells, including Hep G2 cells, compared to primary hepatocytes. H2O2 formation was required for ascorbate cytotoxicity, as extracellular catalase treatment protected tumor cells. H2O2 generated by glucose oxidase treatment also caused cell killing, but treatment with a pharmacologic dose (5-20mM) of ascorbate was significantly more cytotoxic at comparable rates of H2O2 production, suggesting that ascorbate enhanced H2O2 cytotoxicity. This was further supported by the finding that ascorbate at a non-cytotoxic dose (1mM) enhanced cell killing caused by glucose oxidase. Consistent with this conclusion, ascorbate treatment caused deregulation of cellular calcium homeostasis, resulting in massive mitochondrial calcium accumulation. Ascorbate acted synergistically with the chemotherapeutic sorafenib in killing Hep G2 cells, but not primary hepatocytes, suggesting adjuvant ascorbate treatment can broaden sorafenib's therapeutic range. Sorafenib caused mitochondrial depolarization and prevented mitochondrial calcium sequestration. Subsequent ascorbate addition further deregulated cellular calcium homeostasis promoting cell death. Additionally, we present the case of a patient with hepatocellular carcinoma (HCC) who had prolonged regression of a rib metastasis upon combination treatment with ascorbate and sorafenib, indicating that these studies have direct clinical relevance.
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Affiliation(s)
- Lauren Rouleau
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Anil Noronha Antony
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Sara Bisetto
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Andrew Newberg
- Jefferson-Myrna Brind Center of Integrative Medicine, Thomas Jefferson University Hospital, Philadelphia, PA 19107, USA
| | - Cataldo Doria
- Division of Transplantation, Liver Tumor Center, Thomas Jefferson University Hospital, Philadelphia, PA 19107, USA
| | - Mark Levine
- Molecular and Clinical Nutrition Section, Digestive Diseases Branch, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD 20892, USA
| | - Daniel A Monti
- Jefferson-Myrna Brind Center of Integrative Medicine, Thomas Jefferson University Hospital, Philadelphia, PA 19107, USA
| | - Jan B Hoek
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107, USA
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11
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Pshenichnyuk SA, Modelli A, Lazneva EF, Komolov AS. Hypothesis for the Mechanism of Ascorbic Acid Activity in Living Cells Related to Its Electron-Accepting Properties. J Phys Chem A 2016; 120:2667-76. [DOI: 10.1021/acs.jpca.6b02272] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Stanislav A. Pshenichnyuk
- Institute of Molecule and Crystal Physics,
Ufa Research Centre, Russian Academy of Sciences, Prospekt Oktyabrya
151, 450075 Ufa, Russia
- Physics Faculty, St. Petersburg State University, Uljanovskaja 1, 198504 St. Petersburg, Russia
| | - Alberto Modelli
- Dipartimento
di Chimica “G. Ciamician”, Università di Bologna, via Selmi 2, 40126 Bologna, Italy
- Centro Interdipartimentale di Ricerca in Scienze Ambientali, via S. Alberto 163, 48123 Ravenna, Italy
| | - Eleonora F. Lazneva
- Physics Faculty, St. Petersburg State University, Uljanovskaja 1, 198504 St. Petersburg, Russia
| | - Alexei S. Komolov
- Physics Faculty, St. Petersburg State University, Uljanovskaja 1, 198504 St. Petersburg, Russia
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12
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Li R. Vitamin C, a Multi-Tasking Molecule, Finds a Molecular Target in Killing Cancer Cells. ACTA ACUST UNITED AC 2016; 1:141-156. [PMID: 29780883 DOI: 10.20455/ros.2016.829] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Early work in the 1970s by Linus Pauling, a twice-honored Nobel laureate, led to his proposal of using high-dose vitamin C to treat cancer patients. Over the past several decades, a number of studies in animal models as well as several small-scale clinical studies have provided substantial support of Linus Pauling's early proposal. Production of reactive oxygen species (ROS) via oxidation of vitamin C appears to be a major underlying event, leading to the selective killing of cancer cells. However, it remains unclear how vitamin C selectively kills cancer cells while sparing normal cells and what the molecular targets of high-dose vitamin C are. In a recent article published in Science (2015 December 11; 350(6266):1391-6. doi: 10.1126/science.aaa5004), Yun et al. reported that vitamin C selectively kills KRAS and BRAF mutant colorectal cancer cells by targeting glyceraldehyde 3-phosphate dehydrogenase (GAPDH) through an ROS-dependent mechanism. This work by Yun et al. along with other findings advances our current understanding of the molecular basis of high-dose vitamin C-mediated cancer cell killing, which will likely give an impetus to the continued research efforts aiming to further decipher the novel biochemistry of vitamin C and its unique role in cancer therapy.
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Affiliation(s)
- Robert Li
- School of Osteopathic Medicine, Campbell University, Buies Creek, NC 27506, USA.,College of Pharmacy and Health Sciences, Campbell University, Buies Creek, NC 27506, USA.,Virginia Tech-Wake Forest University School of Biomedical Engineering and Sciences, Blacksburg, VA 24061, USA.,Department of Biomedical Sciences and Pathobiology, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA.,Department of Biology, University of North Carolina, Greensboro, NC 27412, USA
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13
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Fiorani M, Azzolini C, Cerioni L, Scotti M, Guidarelli A, Ciacci C, Cantoni O. The mitochondrial transporter of ascorbic acid functions with high affinity in the presence of low millimolar concentrations of sodium and in the absence of calcium and magnesium. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2015; 1848:1393-401. [DOI: 10.1016/j.bbamem.2015.03.009] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2014] [Revised: 02/13/2015] [Accepted: 03/10/2015] [Indexed: 12/30/2022]
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14
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Lane DJR, Richardson DR. The active role of vitamin C in mammalian iron metabolism: much more than just enhanced iron absorption! Free Radic Biol Med 2014; 75:69-83. [PMID: 25048971 DOI: 10.1016/j.freeradbiomed.2014.07.007] [Citation(s) in RCA: 143] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/13/2014] [Revised: 07/04/2014] [Accepted: 07/08/2014] [Indexed: 01/18/2023]
Abstract
Ascorbate is a cofactor in numerous metabolic reactions. Humans cannot synthesize ascorbate owing to inactivation of the gene encoding the enzyme l-gulono-γ-lactone oxidase, which is essential for ascorbate synthesis. Accumulating evidence strongly suggests that in addition to the known ability of dietary ascorbate to enhance nonheme iron absorption in the gut, ascorbate within mammalian systems can regulate cellular iron uptake and metabolism. Ascorbate modulates iron metabolism by stimulating ferritin synthesis, inhibiting lysosomal ferritin degradation, and decreasing cellular iron efflux. Furthermore, ascorbate cycling across the plasma membrane is responsible for ascorbate-stimulated iron uptake from low-molecular-weight iron-citrate complexes, which are prominent in the plasma of individuals with iron-overload disorders. Importantly, this iron-uptake pathway is of particular relevance to astrocyte brain iron metabolism and tissue iron loading in disorders such as hereditary hemochromatosis and β-thalassemia. Recent evidence also indicates that ascorbate is a novel modulator of the classical transferrin-iron uptake pathway, which provides almost all iron for cellular demands and erythropoiesis under physiological conditions. Ascorbate acts to stimulate transferrin-dependent iron uptake by an intracellular reductive mechanism, strongly suggesting that it may act to stimulate iron mobilization from the endosome. The ability of ascorbate to regulate transferrin iron uptake could help explain the metabolic defect that contributes to ascorbate-deficiency-induced anemia.
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Affiliation(s)
- Darius J R Lane
- Molecular Pharmacology and Pathology Program, Department of Pathology and Bosch Institute, University of Sydney, Sydney, NSW 2006, Australia.
| | - Des R Richardson
- Molecular Pharmacology and Pathology Program, Department of Pathology and Bosch Institute, University of Sydney, Sydney, NSW 2006, Australia.
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15
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Bánhegyi G, Benedetti A, Margittai É, Marcolongo P, Fulceri R, Németh CE, Szarka A. Subcellular compartmentation of ascorbate and its variation in disease states. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2014; 1843:1909-16. [DOI: 10.1016/j.bbamcr.2014.05.016] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2014] [Revised: 05/27/2014] [Accepted: 05/28/2014] [Indexed: 12/11/2022]
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16
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Szarka A, Lőrincz T. Cellular and intracellular transport of vitamin C. The physiologic aspects. Orv Hetil 2013; 154:1651-6. [DOI: 10.1556/oh.2013.29712] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Vitamin C requirement is satisfied by natural sources and vitamin C supplements in the ordinary human diet. The two major forms of vitamin C in the diet are L-ascorbic acid and L-dehydroascorbic acid. Both ascorbate and dehydroascorbate are absorbed along the entire length of the human intestine. The reduced form, L-ascorbic acid is imported by an active mechanism, requiring two sodium-dependent vitamin C transporters (SVCT1 and SVCT2). The transport of the oxidized form, dehydroascorbate is mediated by glucose transporters GLUT1, GLUT3 and possibly GLUT4. Initial rate of uptake of both ascorbate and dehydroascorbate is saturable with increasing external substrate concentration. Vitamin C plasma concentrations are tightly controlled when the vitamin is taken orally. It has two simple reasons, on the one hand, the capacity of the transporters is limited, on the other hand the two Na+-dependent transporters can be down-regulated by an elevated level of ascorbate. Orv. Hetil., 154 (42), 1651–1656.
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Affiliation(s)
- András Szarka
- Semmelweis Egyetem, Általános Orvostudományi Kar Orvosi Vegytani Molekuláris Biológiai és Patobiokémiai Intézet Budapest Tűzoltó u. 34–47. 1097
- Budapesti Műszaki és Gazdaságtudományi Egyetem Alkalmazott Biotechnológia és Élelmiszer-tudományi Tanszék, Biokémiai és Molekuláris Biológiai Laboratórium Budapest
| | - Tamás Lőrincz
- Budapesti Műszaki és Gazdaságtudományi Egyetem Alkalmazott Biotechnológia és Élelmiszer-tudományi Tanszék, Biokémiai és Molekuláris Biológiai Laboratórium Budapest
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Masterjohn C, Mah E, Guo Y, Koo SI, Bruno RS. γ-Tocopherol abolishes postprandial increases in plasma methylglyoxal following an oral dose of glucose in healthy, college-aged men. J Nutr Biochem 2011; 23:292-8. [PMID: 21543210 DOI: 10.1016/j.jnutbio.2010.12.007] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2010] [Revised: 12/03/2010] [Accepted: 12/09/2010] [Indexed: 01/26/2023]
Abstract
Postprandial hyperglycemia contributes to the risk of cardiovascular disease in part by increasing concentrations of the reactive dicarbonyl methylglyoxal (MGO), a byproduct of glucose metabolism. Oxidative stress increases MGO formation from glucose in vitro and decreases its glutathione-dependent detoxification to lactate. We hypothesized that the antioxidant γ-tocopherol, a form of vitamin E, would decrease hyperglycemia-mediated postprandial increases in plasma MGO in healthy, normoglycemic, college-aged men. Participants (n=12 men; 22.3±1.0 years; 29.3±2.4 kg/m(2)) received an oral dose of glucose (75 g) in the fasted state prior to and following 5-day ingestion of a vitamin E supplement enriched in γ-tocopherol (500 mg/day). γ-Tocopherol supplementation increased (P<.0001) plasma γ-tocopherol from 2.22±0.32 to 7.06±0.71 μmol/l. Baseline MGO concentrations and postprandial hyperglycemic responses were unaffected by γ-tocopherol supplementation (P>.05). Postprandial MGO concentrations increased in the absence of supplemental γ-tocopherol (P<.05), but not following γ-tocopherol supplementation (P>.05). Area under the curve for plasma MGO was significantly (P<.05) smaller with the supplementation of γ-tocopherol than without (area under the curve (0-180 min), -778±1010 vs. 2277±705). Plasma concentrations of γ-carboxyethyl-hydroxychroman, reduced glutathione and markers of total antioxidant capacity increased after supplementation, and these markers and plasma γ-tocopherol were inversely correlated with plasma MGO (r=-0.48 to -0.67, P<.05). These data suggest that short-term supplementation of γ-tocopherol abolishes the oral glucose-mediated increases in postprandial MGO through its direct and indirect antioxidant properties and may reduce hyperglycemia-mediated cardiovascular disease risk.
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Affiliation(s)
- Christopher Masterjohn
- Department of Nutritional Sciences, University of Connecticut, Storrs, CT 06269-4017, USA
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18
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Behan RK, Lippard SJ. The aging-associated enzyme CLK-1 is a member of the carboxylate-bridged diiron family of proteins. Biochemistry 2010; 49:9679-81. [PMID: 20923139 DOI: 10.1021/bi101475z] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The aging-associated enzyme CLK-1 is proposed to be a member of the carboxylate-bridged diiron family of proteins. To evaluate this hypothesis and characterize the protein, we expressed soluble mouse CLK-1 (MCLK1) in Escherichia coli as a heterologous host. Using Mössbauer and EPR spectroscopy, we established that MCLK1 indeed belongs to this protein family. Biochemical analyses of the in vitro activity of MCLK1 with quinone substrates revealed that NADH can serve directly as a reductant for catalytic activation of dioxygen and substrate oxidation by the enzyme, with no requirement for an additional reductase protein component. The direct reaction of NADH with a diiron-containing oxidase enzyme has not previously been encountered for any member of the protein superfamily.
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Affiliation(s)
- Rachel K Behan
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
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19
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Corti A, Casini AF, Pompella A. Cellular pathways for transport and efflux of ascorbate and dehydroascorbate. Arch Biochem Biophys 2010; 500:107-15. [PMID: 20494648 DOI: 10.1016/j.abb.2010.05.014] [Citation(s) in RCA: 154] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2010] [Revised: 05/13/2010] [Accepted: 05/14/2010] [Indexed: 11/17/2022]
Abstract
The mechanisms allowing the cellular transport of ascorbic acid represent a primary aspect for the understanding of the roles played by this vitamin in pathophysiology. Considerable research effort has been spent in the field, on several animal models and different cell types. Several mechanisms have been described to date, mediating the movements of different redox forms of ascorbic acid across cell membranes. Vitamin C can enter cells both in its reduced and oxidized form, ascorbic acid (AA) and dehydroascorbate (DHA), utilizing respectively sodium-dependent transporters (SVCT) or glucose transporters (GLUT). Modulation of SVCT expression and function has been described by cytokines, steroids and post-translational protein modification. Cellular uptake of DHA is followed by its intracellular reduction to AA by several enzymatic and non-enzymatic systems. Efflux of vitamin C has been also described in a number of cell types and different pathophysiological functions were proposed for this phenomenon, in dependence of the cell model studied. Cellular efflux of AA is mediated through volume-sensitive (VSOAC) and Ca(2+)-dependent anion channels, gap-junction hemichannels, exocytosis of secretory vesicles and possibly through homo- and hetero-exchange systems at the plasma membrane level. Altogether, available data suggest that cellular efflux of ascorbic acid - besides its uptake - should be taken into account when evaluating the cellular homeostasis and functions of this important vitamin.
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Affiliation(s)
- Alessandro Corti
- Dipartimento di Patologia Sperimentale, Università di Pisa, Italy.
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20
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Lowes DA, Webster NR, Galley HF. Dehydroascorbic acid as pre-conditioner: protection from lipopolysaccharide induced mitochondrial damage. Free Radic Res 2010; 44:283-92. [PMID: 20166893 DOI: 10.3109/10715760903468766] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Oxidative stress-induced mitochondrial dysfunction is a common consequence of severe sepsis. However, oxidative stress also activates signalling cascades which enable protection of cells against subsequent oxidative damage. This study hypothesized that cellular uptake of vitamin C as dehydroascorbic acid rather than ascorbic acid would up-regulate antioxidant enzyme systems and impart a protective effect to mitochondria in cells subsequently exposed to lipopolysaccharide (LPS) in an iron free environment. Treatment of monocytes with dehydroascorbic acid, but not ascorbic acid, caused oxidative stress (p< 0.001). Dehydroascorbic acid exposure also resulted in increased manganese superoxide dismutase (p= 0.018) and catalase (p= 0.003) expression. Pre-treatment of monocytes with dehydroascorbic acid followed by LPS resulted in higher mitochondrial membrane potentials than cells without pre-treatment (p< 0.0001). Lower cytochrome c in cytosol (p< 0.05) and higher mitochondrial expression of the anti-apoptotic Bcl-2 protein (p= 0.029) was also found in monocytes pre-treated before subsequent LPS exposure, compared to cells without pre-treatment. In conclusion, acute exposure of monocytes to dehydroascorbic acid in an iron free environment induces cytoprotective antioxidant enzymes and protected mitochondria from the harmful effects of oxidative stress prior to a septic insult, which was abrogated when cells were pre-incubated with the DHA uptake inhibitor cytocholasin B.
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Affiliation(s)
- Damon A Lowes
- Division of Applied Medicine, School of Medicine & Dentistry, University of Aberdeen, UK
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21
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Yu MA, Egawa T, Yeh SR, Rousseau DL, Gerfen GJ. EPR characterization of ascorbyl and sulfur dioxide anion radicals trapped during the reaction of bovine Cytochrome c Oxidase with molecular oxygen. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2010; 203:213-219. [PMID: 20056464 PMCID: PMC6446898 DOI: 10.1016/j.jmr.2009.12.017] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2009] [Revised: 12/21/2009] [Accepted: 12/21/2009] [Indexed: 05/28/2023]
Abstract
The reaction intermediates of reduced bovine Cytochrome c Oxidase (CcO) were trapped following its reaction with oxygen at 50 micros-6 ms by innovative freeze-quenching methods and studied by EPR. When the enzyme was reduced with either ascorbate or dithionite, distinct radicals were generated; X-band (9 GHz) and D-band (130 GHz) CW-EPR measurements support the assignments of these radicals to ascorbyl and sulfur dioxide anion radical (SO2(-.)), respectively. The X-band spectra show a linewidth of 12 G for the ascorbyl radical and 11 G for the SO2(-.) radical and an isotropic g-value of 2.005 for both species. The D-band spectra reveal clear distinctions in the g-tensors and powder patterns of the two species. The ascorbyl radical spectrum displays approximate axial symmetry with g-values of g(x)=2.0068, g(y)=2.0066, and g(z)=2.0023. The SO2(-.) radical has rhombic symmetry with g-values of g(x)=2.0089, g(y)=2.0052, and g(z)=2.0017. When the contributions from the ascorbyl and SO2(-.) radicals were removed, no protein-based radical on CcO could be identified in the EPR spectra.
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22
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Abstract
Although ascorbic acid is an important water-soluble antioxidant and enzyme cofactor in plants and animals, humans and some other species do not synthesize ascorbate due to the lack of the enzyme catalyzing the final step of the biosynthetic pathway, and for them it has become a vitamin. This review focuses on the role of ascorbate in various hydroxylation reactions and in the redox homeostasis of subcellular compartments including mitochondria and endoplasmic reticulum. Recently discovered functions of ascorbate in nucleic acid and histone dealkylation and proteoglycan deglycanation are also summarized. These new findings might delineate a role for ascorbate in the modulation of both pro- and anti-carcinogenic mechanisms. Recent advances and perspectives in therapeutic applications are also reviewed. On the basis of new and earlier observations, the advantages of the lost ability to synthesize ascorbate are pondered. The increasing knowledge of the functions of ascorbate and of its molecular sites of action can mechanistically substantiate a place for ascorbate in the treatment of various diseases.
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Affiliation(s)
- J Mandl
- Department of Medical Chemistry, Molecular Biology and Patobiochemistry, Semmelweis University Budapest, Budapest, Hungary.
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23
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Fiorani M, Guidarelli A, Blasa M, Azzolini C, Candiracci M, Piatti E, Cantoni O. Mitochondria accumulate large amounts of quercetin: prevention of mitochondrial damage and release upon oxidation of the extramitochondrial fraction of the flavonoid. J Nutr Biochem 2009; 21:397-404. [PMID: 19278846 DOI: 10.1016/j.jnutbio.2009.01.014] [Citation(s) in RCA: 141] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2008] [Revised: 01/16/2009] [Accepted: 01/21/2009] [Indexed: 12/24/2022]
Abstract
Quercetin uptake in Jurkat cells is extremely rapid and associated with a remarkable accumulation of the flavonoid, dependent on its binding to intracellular components. Cell-associated quercetin is biologically active, quantitatively consumed to promote survival in the presence of reactive species, such as peroxynitrite (ONOO(-)), or reduction of extracellular oxidants via activation of plasma membrane oxidoreductases. In alternative, quercetin is very slowly released upon post-incubation in drug-free medium, an event significantly accelerated by extracellular albumin. Quercetin uptake is also observed in isolated mitochondria, resulting in an enormous accumulation of the flavonoid, consumed under conditions associated with prevention of lipid peroxidation induced by ONOO(-). Interestingly, remarkable quercetin accumulation is also detected in the mitochondria isolated from quercetin-pre-loaded cells, and exposure to either ONOO(-) or extracellular oxidants caused the parallel loss of both the mitochondrial and cytosolic fractions of the flavonoid. In conclusion, Jurkat cells accumulate large amounts of quercetin and even larger amounts of the flavonoid further accumulate in their mitochondria. Intramitochondrial quercetin appears to be functional for prevention of mitochondrial damage as well as for redistribution to the cytosol, when the fraction of the flavonoid therein retained is progressively consumed either by cell-permeant oxidants or by activation of plasma membrane oxidoreductases.
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Affiliation(s)
- Mara Fiorani
- Dipartimento di Scienze Biomolecolari, Università degli Studi di Urbino Carlo Bo, Urbino, Italy.
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24
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Igamberdiev AU, Hill RD. Plant mitochondrial function during anaerobiosis. ANNALS OF BOTANY 2009; 103:259-68. [PMID: 18586697 PMCID: PMC2707300 DOI: 10.1093/aob/mcn100] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2008] [Revised: 04/29/2008] [Accepted: 05/21/2008] [Indexed: 05/17/2023]
Abstract
BACKGROUND Under hypoxic conditions, plant mitochondria preserve the capacity to oxidize external NADH, NADPH and tricarboxylic acid cycle substrates. Nitrite serves as an alternative electron acceptor at the level of cytochrome oxidase, with possibly complex III and the alternative oxidase also being involved. Nitric oxide is a significant product of the reaction, which has a high affinity for cytochrome c oxidase, inhibiting it. The excess NO is scavenged by hypoxically induced class 1 haemoglobin in the reaction involving ascorbate. SCOPE By using nitrite, mitochondria retain a limited capacity for ATP synthesis. NADH, produced from glycolysis during anaerobiosis and oxidized in the mitochondrial electron transport chain, should shift the composition of metabolites formed during anaerobiosis with increased conversion of pyruvate to alanine and greater involvement of other transamination reactions, such as those involving gamma-aminobutyric acid formation. CONCLUSIONS Anaerobic mitochondrial metabolism may have a more significant role than previously thought in alleviating the effects of anoxia on plant cells. There is a need to re-examine mitochondrial carbon and nitrogen metabolism under anoxia to establish the extent of this involvement.
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Affiliation(s)
- Abir U. Igamberdiev
- Department of Biology, Memorial University of Newfoundland, St John's, NL, Canada, A1B 3X9
| | - Robert D. Hill
- Department of Plant Science, University of Manitoba, Winnipeg, MB, Canada, R3T 2N2
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25
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Heaney ML, Gardner JR, Karasavvas N, Golde DW, Scheinberg DA, Smith EA, O'Connor OA. Vitamin C antagonizes the cytotoxic effects of antineoplastic drugs. Cancer Res 2008; 68:8031-8. [PMID: 18829561 DOI: 10.1158/0008-5472.can-08-1490] [Citation(s) in RCA: 136] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Vitamin C is an antioxidant vitamin that has been hypothesized to antagonize the effects of reactive oxygen species-generating antineoplastic drugs. The therapeutic efficacy of the widely used antineoplastic drugs doxorubicin, cisplatin, vincristine, methotrexate, and imatinib were compared in leukemia (K562) and lymphoma (RL) cell lines with and without pretreatment with dehydroascorbic acid, the commonly transported form of vitamin C. The effect of vitamin C on viability, clonogenicity, apoptosis, P-glycoprotein, reactive oxygen species (ROS), and mitochondrial membrane potential was determined. Pretreatment with vitamin C caused a dose-dependent attenuation of cytotoxicity, as measured by trypan blue exclusion and colony formation after treatment with all antineoplastic agents tested. Vitamin C given before doxorubicin treatment led to a substantial reduction of therapeutic efficacy in mice with RL cell-derived xenogeneic tumors. Vitamin C treatment led to a dose-dependent decrease in apoptosis in cells treated with the antineoplastic agents that was not due to up-regulation of P-glycoprotein or vitamin C retention modulated by antineoplastics. Vitamin C had only modest effects on intracellular ROS and a more general cytoprotective profile than N-acetylcysteine, suggesting a mechanism of action that is not mediated by ROS. All antineoplastic agents tested caused mitochondrial membrane depolarization that was inhibited by vitamin C. These findings indicate that vitamin C given before mechanistically dissimilar antineoplastic agents antagonizes therapeutic efficacy in a model of human hematopoietic cancers by preserving mitochondrial membrane potential. These results support the hypothesis that vitamin C supplementation during cancer treatment may detrimentally affect therapeutic response.
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Affiliation(s)
- Mark L Heaney
- Departments of Medicine and Molecular Pharmacology and Chemistry, Memorial Sloan-Kettering Cancer Center, New York, NY 10021, USA.
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26
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May JM, Li L, Qu ZC, Cobb CE. Mitochondrial recycling of ascorbic acid as a mechanism for regenerating cellular ascorbate. Biofactors 2007; 30:35-48. [PMID: 18198400 DOI: 10.1002/biof.5520300105] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Mitochondria are the major source of potentially damaging reactive oxygen species in most cells. Since ascorbic acid, or vitamin C, can protect against cellular oxidant stress, we studied the ability of mitochondria prepared from guinea pig skeletal muscle to recycle the vitamin from its oxidized forms. Although ascorbate concentrations in freshly prepared mitochondria were only about 0.2 mM, when provided with 6 mM succinate and 1 mM dehydroascorbate (the two-electron-oxidized form of the vitamin), mitochondria were able to generate and maintain concentrations as high as 4 mM, while releasing most of the ascorbate into the incubation medium. Mitochondrial reduction of dehydroascorbate was strongly inhibited by 1,3-bis(chloroethyl)-1-nitrosourea and by phenylarsine oxide. Despite existing evidence that mitochondrial ascorbate protects the organelle from oxidant damage, ascorbate failed to preserve mitochondrial alpha-tocopherol during prolonged incubation in oxygenated buffer. Nonetheless, the capacity for mitochondria to recycle ascorbate from its oxidized forms, measured as ascorbate-dependent ferricyanide reduction, was several-fold greater than total steady-state ascorbate concentrations. This, and the finding that more than half of the ascorbate recycled from dehydroascorbate escaped the mitochondrion, suggests that mitochondrial recycling of ascorbate might be an important mechanism for regenerating intracellular ascorbate.
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Affiliation(s)
- James M May
- Department of Medicine, Vanderbilt University School of Medicine, Nashville, TN 37232-0475, USA.
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27
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KC S, Cárcamo JM, Golde DW. Vitamin C enters mitochondria via facilitative glucose transporter 1 (Gluti) and confers mitochondrial protection against oxidative injury. FASEB J 2005; 19:1657-67. [PMID: 16195374 DOI: 10.1096/fj.05-4107com] [Citation(s) in RCA: 176] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Reactive oxygen species (ROS)-induced mitochondrial abnormalities may have important consequences in the pathogenesis of degenerative diseases and cancer. Vitamin C is an important antioxidant known to quench ROS, but its mitochondrial transport and functions are poorly understood. We found that the oxidized form of vitamin C, dehydroascorbic acid (DHA), enters mitochondria via facilitative glucose transporter 1 (Glut1) and accumulates mitochondrially as ascorbic acid (mtAA). The stereo-selective mitochondrial uptake of D-glucose, with its ability to inhibit mitochondrial DHA uptake, indicated the presence of mitochondrial Glut. Computational analysis of N-termini of human Glut isoforms indicated that Glut1 had the highest probability of mitochondrial localization, which was experimentally verified via mitochondrial expression of Glut1-EGFP. In vitro mitochondrial import of Glut1, immunoblot analysis of mitochondrial proteins, and cellular immunolocalization studies indicated that Glut1 localizes to mitochondria. Loading mitochondria with AA quenched mitochondrial ROS and inhibited oxidative mitochondrial DNA damage. mtAA inhibited oxidative stress resulting from rotenone-induced disruption of the mitochondrial respiratory chain and prevented mitochondrial membrane depolarization in response to a protonophore, CCCP. Our results show that analogous to the cellular uptake, vitamin C enters mitochondria in its oxidized form via Glut1 and protects mitochondria from oxidative injury. Since mitochondria contribute significantly to intracellular ROS, protection of the mitochondrial genome and membrane may have pharmacological implications against a variety of ROS-mediated disorders.
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Affiliation(s)
- Sagan KC
- Department of Pharmacology, Weill Medical College, Cornell University, New York, New York 10021, USA
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28
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K C S, Cárcamo JM, Golde DW. Antioxidants prevent oxidative DNA damage and cellular transformation elicited by the over-expression of c-MYC. Mutat Res 2005; 593:64-79. [PMID: 16085125 DOI: 10.1016/j.mrfmmm.2005.06.015] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2005] [Revised: 06/14/2005] [Accepted: 06/15/2005] [Indexed: 12/24/2022]
Abstract
Reactive oxygen species (ROS)-induced genomic damage may have important consequences in the initiation and progression of cancer. Deregulated expression of the proto-oncogene c-MYC is associated with intracellular oxidative stress and increased DNA damage. However, the protective role of antioxidants such as Vitamin C against MYC-induced genomic damage has not been fully investigated. In a variety of cell lines, we show that ectopic MYC over-expression results in the elevation of intracellular ROS levels and a concomitant increase in oxidative DNA damage, as assessed by levels of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxo-dG) in the genomic DNA. Loading cells with ascorbic acid (AA) relieved MYC-elicited intracellular oxidative stress and conferred genomic protection. A mitochondrially targeted Vitamin E analog, TPPB, also protected cells from MYC-elicited oxidative DNA damage, suggesting the involvement of mitochondria in increased ROS production. We found that deregulated MYC expression resulted in the attenuation of intracellular glutathione levels, which was reversed by loading cells with Vitamin C. Additionally, cells over-expressing MYC had elevated levels of intracellular superoxide, which was significantly quenched by Vitamin C or the selective superoxide quencher, Tiron. Consequently, Vitamin C and other antioxidants protected cells from MYC-induced cellular transformation. Our studies implicate a role for ROS, and superoxide in particular, in MYC-elicited oxidative DNA damage and cellular transformation, and point to a pharmacological role of antioxidants in cancer chemoprevention.
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Affiliation(s)
- Sagun K C
- Department of Pharmacology, Weill Graduate School of Cornell University, New York, NY 10021, USA
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29
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Dhar-Mascareño M, Cárcamo JM, Golde DW. Hypoxia-reoxygenation-induced mitochondrial damage and apoptosis in human endothelial cells are inhibited by vitamin C. Free Radic Biol Med 2005; 38:1311-22. [PMID: 15855049 DOI: 10.1016/j.freeradbiomed.2005.01.017] [Citation(s) in RCA: 99] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/22/2004] [Revised: 01/20/2005] [Accepted: 01/20/2005] [Indexed: 10/25/2022]
Abstract
Hypoxia and hypoxia-reperfusion (H-R) play important roles in human pathophysiology because they occur in clinical conditions such as circulatory shock, myocardial ischemia, stroke, and organ transplantation. Reintroduction of oxygen to hypoxic cells during reperfusion causes an increase in generation of reactive oxygen species (ROS), which can alter cell signaling, and cause damage to lipids, proteins, and DNA leading to ischemia-reperfusion injury. Since vitamin C is a potent antioxidant and quenches ROS, we investigated the role of intracellular ascorbic acid (iAA) in endothelial cells undergoing hypoxia-reperfusion. Intracellular AA protected human endothelial cells from H-R-induced apoptosis. Intracellular AA also prevents loss of mitochondrial membrane potential and the release of cytochrome C and activation of caspase-9 and caspase-3 during H-R. Additionally, inhibition of caspase-9 activation prevented H-R-induced apoptosis, suggesting a mitochondrial site of initiation of apoptosis. We found that H-R induced an increase in ROS in endothelial cells that was abrogated in the presence of iAA. Our results indicate that vitamin C prevents hypoxia and H-R-induced damage to human endothelium.
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Affiliation(s)
- Manya Dhar-Mascareño
- Molecular Pharmacology and Chemistry Program, Memorial Sloan-Kettering Cancer Center, New York, NY 10021, USA.
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30
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Szarka A, Horemans N, Bánhegyi G, Asard H. Facilitated glucose and dehydroascorbate transport in plant mitochondria. Arch Biochem Biophys 2004; 428:73-80. [PMID: 15234271 DOI: 10.1016/j.abb.2004.05.011] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2004] [Revised: 05/11/2004] [Indexed: 10/26/2022]
Abstract
Ascorbate, dehydroascorbate, and glucose transport was investigated in plant mitochondria and mitoplasts prepared from cultured BY2 tobacco cells. Using a rapid filtration method with radiolabeled ligands, we observed a specific glucose and dehydroascorbate transport, which was temperature and time dependent and saturable. Inhibition of mitochondrial respiration by KCN and the uncoupler 2,4-dinitrophenol did not influence the transport of the investigated compounds. Dehydroascorbate transport was inhibited by glucose and genistein, while glucose uptake was decreased upon 3-O-methyl-glucose, D-mannose, cytochalasin B or genistein addition. On the other hand, a low affinity low capacity ascorbate transport was found. Oxidizing agents (potassium ferricyanide or ascorbate oxidase) increased ascorbate uptake. The results demonstrate the presence of dehydroascorbate and glucose transport in plant mitochondria and suggest that it is mediated by the same or closely related transporter(s).
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Affiliation(s)
- András Szarka
- Department of Medical Chemistry, Molecular Biology and Pathobiochemistry, Semmelweis University, Budapest, Hungary
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31
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Barone MC, Darley-Usmar VM, Brookes PS. Reversible inhibition of cytochrome c oxidase by peroxynitrite proceeds through ascorbate-dependent generation of nitric oxide. J Biol Chem 2003; 278:27520-4. [PMID: 12743113 DOI: 10.1074/jbc.m304129200] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Reversible inhibition of cytochrome c oxidase (CcOX) by nitric oxide (NO*) has potential physiological roles in the regulation of mitochondrial respiration, redox signaling, and apoptosis. However peroxynitrite (ONOO-), an oxidant formed from the reaction of NO* and superoxide, appears mostly detrimental to cell function. This occurs both through direct oxidant reactions and by decreasing the availability of NO* for interacting with CcOX. When isolated CcOX respires with ascorbate as a reducing substrate, the conversion of ONOO- to NO* is observed. It is not known whether this can be ascribed to a direct interaction of the enzyme with ONOO-. In this investigation, the role of ascorbate in this system was examined using polarographic methods to measure NO* production and CcOX activity simultaneously in both the purified enzyme and isolated mitochondria. It was found that ascorbate alone accounts for >90% of the NO* yield from ONOO- in the presence or absence of purified CcOX in turnover. The yield of NO was CcOX-independent but was dependent on ascorbate and ONOO- concentrations and was not affected by metal chelators. Consistent with this, the interaction of ONOO- with CcOX in respiring isolated mitochondria only yielded NO* when ascorbate was also present in the incubation. These observations are discussed in the context of ONOO-/ascorbate reactivity and the interaction of CcOX with reactive nitrogen species.
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Affiliation(s)
- Maria Cecilia Barone
- Department of Pathology and Center for Free Radical Biology, University of Alabama at Birmingham, Birmingham, Alabama 35294, USA
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