1
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Naima J, Ohta Y. Potassium Ions Decrease Mitochondrial Matrix pH: Implications for ATP Production and Reactive Oxygen Species Generation. Int J Mol Sci 2024; 25:1233. [PMID: 38279231 PMCID: PMC10815940 DOI: 10.3390/ijms25021233] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2023] [Revised: 01/05/2024] [Accepted: 01/14/2024] [Indexed: 01/28/2024] Open
Abstract
Potassium (K+) is the most abundant cation in the cytosol and is maintained at high concentrations within the mitochondrial matrix through potassium channels. However, many effects of K+ at such high concentrations on mitochondria and the underlying mechanisms remain unclear. This study aims to elucidate these effects and mechanisms by employing fluorescence imaging techniques to distinguish and precisely measure signals inside and outside the mitochondria. We stained the mitochondrial matrix with fluorescent dyes sensitive to K+, pH, reactive oxygen species (ROS), and membrane potential in plasma membrane-permeabilized C6 cells and isolated mitochondria from C6 cells. Fluorescence microscopy facilitated the accurate measurement of fluorescence intensity inside and outside the matrix. Increasing extramitochondrial K+ concentration from 2 mM to 127 mM led to a reduction in matrix pH and a decrease in the generation of highly reactive ROS. In addition, elevated K+ levels electrically polarized the inner membrane of the mitochondria and promoted efficient ATP synthesis via FoF1-ATPase. Introducing protons (H+) into the matrix through phosphate addition led to further mitochondrial polarization, and this effect was more pronounced in the presence of K+. K+ at high concentrations, reaching sub-hundred millimolar levels, increased H+ concentration within the matrix, suppressing ROS generation and boosting ATP synthesis. Although this study does not elucidate the role of specific types of potassium channels in mitochondria, it does suggest that mitochondrial K+ plays a beneficial role in maintaining cellular health.
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Affiliation(s)
| | - Yoshihiro Ohta
- Department of Biotechnology and Life Science, Tokyo University of Agriculture and Technology, Nakacho, Koganei, Tokyo 184-8588, Japan;
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2
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Grayson C, Mailloux RJ. Coenzyme Q 10 and nicotinamide nucleotide transhydrogenase: Sentinels for mitochondrial hydrogen peroxide signaling. Free Radic Biol Med 2023; 208:260-271. [PMID: 37573896 DOI: 10.1016/j.freeradbiomed.2023.08.015] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/05/2023] [Revised: 07/21/2023] [Accepted: 08/08/2023] [Indexed: 08/15/2023]
Abstract
Mitochondria use hydrogen peroxide (H2O2) as a mitokine for cell communication. H2O2 output for signaling depends on its rate of production and degradation, both of which are strongly affected by the redox state of the coenzyme Q10 (CoQ) pool and NADPH availability. Here, we propose the CoQ pool and nicotinamide nucleotide transhydrogenase (NNT) have evolved to be central modalities for mitochondrial H2O2 signaling. Both factors play opposing yet equally important roles in dictating H2O2 availability because they are connected to one another by two central parameters in bioenergetics: electron supply and Δp. The CoQ pool is the central point of convergence for electrons from various dehydrogenases and the electron transport chain (ETC). The increase in Δp creates a significant amount of protonic backpressure on mitochondria to promote H2O2 genesis through CoQ pool reduction. These same factors also drive the activity of NNT, which uses electrons and the Δp to eliminate H2O2. In this way, electron supply and the magnitude of the Δp manifests as a redox connection between the two sentinels, CoQ and NNT, which serve as opposing yet equally important forces required for budgeting H2O2. Taken together, CoQ and NNT are sentinels linked through mitochondrial bioenergetics to manage H2O2 availability for interorganelle and intercellular redox signaling.
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Affiliation(s)
- Cathryn Grayson
- The School of Human Nutrition, Faculty of Agricultural and Environmental Sciences, McGill University, Ste.-Anne-de-Bellevue, Quebec, Canada
| | - Ryan J Mailloux
- The School of Human Nutrition, Faculty of Agricultural and Environmental Sciences, McGill University, Ste.-Anne-de-Bellevue, Quebec, Canada.
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3
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Okoye CN, Chinnappareddy N, Stevens D, Kamunde C. Factors affecting liver mitochondrial hydrogen peroxide emission. Comp Biochem Physiol B Biochem Mol Biol 2022; 259:110713. [PMID: 35026417 DOI: 10.1016/j.cbpb.2022.110713] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Revised: 12/19/2021] [Accepted: 01/04/2022] [Indexed: 10/19/2022]
Abstract
Mitochondria are key cellular sources of reactive oxygen species (ROS) and contain at least 12 known sites on multiple enzymes that convert molecular oxygen to superoxide and hydrogen peroxide (H2O2). Quantitation of site-specific ROS emission is critical to understand the relative contribution of different sites and the pathophysiologic importance of mitochondrial ROS. However, factors that affect mitochondrial ROS emission are not well understood. We characterized and optimized conditions for maximal total and site-specific H2O2 emission during oxidation of standard substrates and probed the source of the high H2O2 emission in unenergized rainbow trout liver mitochondria. We found that mitochondrial H2O2 emission capacity depended on the substrate being oxidized, mitochondrial protein concentration, and composition of the ROS detection system. Contrary to our expectation, addition of exogenous superoxide dismutase reduced H2O2 emission. Titration of conventional mitochondrial electron transfer system (ETS) inhibitors over a range of conditions revealed that one size does not fit all; inhibitor concentrations evoking maximal responses varied with substrate and were moderated by the presence of other inhibitors. Moreover, the efficacy of suppressors of electron leak (S1QEL1.1 and S3QEL2) was low and depended on the substrate being oxidized. We found that H2O2 emission in unenergized rainbow trout liver mitochondria was suppressed by GKT136901 suggesting that it is associated with NADPH oxidase activity. We conclude that optimization of assay conditions is critical for quantitation of maximal H2O2 emission and would facilitate more valid comparisons of mitochondrial total and site-specific H2O2 emission capacities between studies, tissues, and species.
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Affiliation(s)
- Chidozie N Okoye
- Department of Biomedical Sciences, Atlantic Veterinary College, University of Prince Edward Island, 550 University Avenue, Charlottetown, PE C1A 4P3, Canada
| | - Nirmala Chinnappareddy
- Department of Biomedical Sciences, Atlantic Veterinary College, University of Prince Edward Island, 550 University Avenue, Charlottetown, PE C1A 4P3, Canada
| | - Don Stevens
- Department of Biomedical Sciences, Atlantic Veterinary College, University of Prince Edward Island, 550 University Avenue, Charlottetown, PE C1A 4P3, Canada
| | - Collins Kamunde
- Department of Biomedical Sciences, Atlantic Veterinary College, University of Prince Edward Island, 550 University Avenue, Charlottetown, PE C1A 4P3, Canada.
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4
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Broome S, Atiola RD, Braakhuis A, Mitchell C, Merry TL. Mitochondria-targeted antioxidant supplementation does not affect muscle soreness or recovery of maximal voluntary isometric contraction force following muscle-damaging exercise in untrained men: a randomised clinical trial. Appl Physiol Nutr Metab 2022; 47:762-774. [PMID: 35201920 DOI: 10.1139/apnm-2021-0767] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Unaccustomed exercise causes muscle damage resulting in loss of muscle function, which may be attributable to exercise-induced increases in skeletal muscle reactive oxygen species (ROS). This study examined the effect of mitochondria-targeted antioxidant supplementation on recovery of muscle function following exercise. Thirty-two untrained men received MitoQ (20 mg/day) or a placebo for 14 days before performing 300 maximal eccentric contractions of the knee extensor muscles of one leg. Muscle function was assessed using isokinetic dynamometry before, immediately after, and 24, 48, 72, and 168 hours after exercise. Muscle soreness was assessed using a visual analogue scale 24, 48, 72, and 168 hours after exercise. Blood samples were collected before, immediately after, and 2, 24, 48, 72, and 168 hours after exercise and urine samples were collected before and during the 48 hours after exercise. The reduction in maximal voluntary isometric contraction force and peak concentric torque following exercise was unaffected by MitoQ while recovery of peak eccentric torque was delayed in the MitoQ group. Exercise-induced increases in urine F2-isoprostanes were unaffected by MitoQ. MitoQ augmented exercise-induced increases in plasma CK levels while plasma IL-6 was similar between groups. Muscle soreness was not affected by MitoQ. These results indicate that MitoQ does not attenuate post-exercise muscle soreness and may delay recovery of muscle function following eccentric exercise. Novelty: • Post-exercise recovery of maximal voluntary isometric contraction force and peak concentric torque were unaffected by MitoQ. • MitoQ delayed post-exercise recovery of peak eccentric torque. • Post-exercise muscle soreness was unaffected by MitoQ.
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Affiliation(s)
- Sophie Broome
- The University of Auckland Faculty of Medical and Health Sciences, 62710, Auckland, Auckland, New Zealand;
| | - R D Atiola
- The University of Auckland Faculty of Medical and Health Sciences, 62710, Auckland, Auckland, New Zealand;
| | - A Braakhuis
- The University of Auckland Faculty of Medical and Health Sciences, 62710, Auckland, Auckland, New Zealand;
| | - Cam Mitchell
- The University of British Columbia Faculty of Education, 141631, Vancouver, British Columbia, Canada;
| | - Troy L Merry
- The University of Auckland Faculty of Medical and Health Sciences, 62710, Auckland, Auckland, New Zealand;
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5
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Corkey BE, Deeney JT, Merrins MJ. What Regulates Basal Insulin Secretion and Causes Hyperinsulinemia? Diabetes 2021; 70:2174-2182. [PMID: 34593535 PMCID: PMC8576498 DOI: 10.2337/dbi21-0009] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Accepted: 07/28/2021] [Indexed: 12/12/2022]
Abstract
We hypothesize that basal hyperinsulinemia is synergistically mediated by an interplay between increased oxidative stress and excess lipid in the form of reactive oxygen species (ROS) and long-chain acyl-CoA esters (LC-CoA). In addition, ROS production may increase in response to inflammatory cytokines and certain exogenous environmental toxins that mislead β-cells into perceiving nutrient excess when none exists. Thus, basal hyperinsulinemia is envisioned as an adaptation to sustained real or perceived nutrient excess that only manifests as a disease when the excess demand can no longer be met by an overworked β-cell. In this article we will present a testable hypothetical mechanism to explain the role of lipids and ROS in basal hyperinsulinemia and how they differ from glucose-stimulated insulin secretion (GSIS). The model centers on redox regulation, via ROS, and S-acylation-mediated trafficking via LC-CoA. These pathways are well established in neural systems but not β-cells. During GSIS, these signals rise and fall in an oscillatory pattern, together with the other well-established signals derived from glucose metabolism; however, their precise roles have not been defined. We propose that failure to either increase or decrease ROS or LC-CoA appropriately will disturb β-cell function.
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Affiliation(s)
- Barbara E Corkey
- Department of Medicine, Boston University School of Medicine, Boston, MA
| | - Jude T Deeney
- Department of Medicine, Boston University School of Medicine, Boston, MA
| | - Matthew J Merrins
- Department of Biomolecular Chemistry and Section of Endocrinology, Diabetes and Metabolism, Department of Medicine, University of Wisconsin-Madison School of Medicine and Public Health, Madison, WI
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Shen L, Gao L, Yang M, Zhang J, Wang Y, Feng Y, Wang L, Wang S. Deletion of the PA4427-PA4431 Operon of Pseudomonas aeruginosa PAO1 Increased Antibiotics Resistance and Reduced Virulence and Pathogenicity by Affecting Quorum Sensing and Iron Uptake. Microorganisms 2021; 9:microorganisms9051065. [PMID: 34069209 PMCID: PMC8156433 DOI: 10.3390/microorganisms9051065] [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: 04/13/2021] [Revised: 05/06/2021] [Accepted: 05/10/2021] [Indexed: 12/06/2022] Open
Abstract
The respiratory chain is very important for bacterial survival and pathogenicity, yet the roles of the respiratory chain in P. aeruginosa remain to be fully elucidated. Here, we not only proved experimentally that the operon PA4427-PA4431 of Pseudomonas aeruginosa PAO1 encodes respiratory chain complex III (cytobc1), but also found that it played important roles in virulence and pathogenicity. PA4429–31 deletion reduced the production of the virulence factors, including pyocyanin, rhamnolipids, elastase, and extracellular polysaccharides, and it resulted in a remarkable decrease in pathogenicity, as demonstrated in the cabbage and Drosophila melanogaster infection models. Furthermore, RNA-seq analysis showed that PA4429–31 deletion affected the expression levels of the genes related to quorum-sensing systems and the transport of iron ions, and the iron content was also reduced in the mutant strain. Taken together, we comprehensively illustrated the function of the operon PA4427–31 and its application potential as a treatment target in P. aeruginosa infection.
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7
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Lee H, Jose PA. Coordinated Contribution of NADPH Oxidase- and Mitochondria-Derived Reactive Oxygen Species in Metabolic Syndrome and Its Implication in Renal Dysfunction. Front Pharmacol 2021; 12:670076. [PMID: 34017260 PMCID: PMC8129499 DOI: 10.3389/fphar.2021.670076] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2021] [Accepted: 04/14/2021] [Indexed: 12/16/2022] Open
Abstract
Metabolic syndrome (MetS), a complex of interrelated risk factors for cardiovascular disease and diabetes, is comprised of central obesity (increased waist circumference), hyperglycemia, dyslipidemia (high triglyceride blood levels, low high-density lipoprotein blood levels), and increased blood pressure. Oxidative stress, caused by the imbalance between pro-oxidant and endogenous antioxidant systems, is the primary pathological basis of MetS. The major sources of reactive oxygen species (ROS) associated with MetS are nicotinamide-adenine dinucleotide phosphate (NADPH) oxidases and mitochondria. In this review, we summarize the current knowledge regarding the generation of ROS from NADPH oxidases and mitochondria, discuss the NADPH oxidase- and mitochondria-derived ROS signaling and pathophysiological effects, and the interplay between these two major sources of ROS, which leads to chronic inflammation, adipocyte proliferation, insulin resistance, and other metabolic abnormalities. The mechanisms linking MetS and chronic kidney disease are not well known. The role of NADPH oxidases and mitochondria in renal injury in the setting of MetS, particularly the influence of the pyruvate dehydrogenase complex in oxidative stress, inflammation, and subsequent renal injury, is highlighted. Understanding the molecular mechanism(s) underlying MetS may lead to novel therapeutic approaches by targeting the pyruvate dehydrogenase complex in MetS and prevent its sequelae of chronic cardiovascular and renal diseases.
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Affiliation(s)
- Hewang Lee
- Department of Medicine, The George Washington University School of Medicine and Health Sciences, Washington, DC, United States
| | - Pedro A Jose
- Department of Medicine, The George Washington University School of Medicine and Health Sciences, Washington, DC, United States.,Department of Pharmacology and Physiology, The George Washington University School of Medicine and Health Sciences, Washington, DC, United States
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8
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Generation of Reactive Oxygen Species by Mitochondria. Antioxidants (Basel) 2021; 10:antiox10030415. [PMID: 33803273 PMCID: PMC8001687 DOI: 10.3390/antiox10030415] [Citation(s) in RCA: 117] [Impact Index Per Article: 39.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Revised: 02/28/2021] [Accepted: 03/01/2021] [Indexed: 12/15/2022] Open
Abstract
Reactive oxygen species (ROS) are series of chemical products originated from one or several electron reductions of oxygen. ROS are involved in physiology and disease and can also be both cause and consequence of many biological scenarios. Mitochondria are the main source of ROS in the cell and, particularly, the enzymes in the electron transport chain are the major contributors to this phenomenon. Here, we comprehensively review the modes by which ROS are produced by mitochondria at a molecular level of detail, discuss recent advances in the field involving signalling and disease, and the involvement of supercomplexes in these mechanisms. Given the importance of mitochondrial ROS, we also provide a schematic guide aimed to help in deciphering the mechanisms involved in their production in a variety of physiological and pathological settings.
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9
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Correia-Álvarez E, Keating JE, Glish G, Tarran R, Sassano MF. Reactive Oxygen Species, Mitochondrial Membrane Potential, and Cellular Membrane Potential Are Predictors of E-Liquid Induced Cellular Toxicity. Nicotine Tob Res 2020; 22:S4-S13. [PMID: 33320253 PMCID: PMC8493666 DOI: 10.1093/ntr/ntaa177] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Accepted: 09/08/2020] [Indexed: 12/22/2022]
Abstract
Introduction The use of flavors in electronic cigarettes appeals to adults and
never-smoking youth. Consumption has rapidly increased over the last decade,
and in the U.S. market alone, there are over 8000 unique flavors. The U.S.
Food and Drug Administration (FDA) has begun to regulate e-liquids, but many
have not been tested, and their impact, both at the cellular level, and on
human health remains unclear. Methods We tested e-liquids on the human cell line HEK293T and measured toxicity,
mitochondrial membrane potential
(ΔΨ m), reactive oxygen species
production (ROS), and cellular membrane potential
(Vm) using high-throughput screening (HTS)
approaches. Our HTS efforts included single-dose and 16-point
dose–response curves, which allowed testing of ≥90
commercially available e-liquids in parallel to provide a rapid assessment
of cellular effects as a proof of concept for a fast, preliminary toxicity
method. We also investigated the chemical composition of the flavors via gas
chromatography–mass spectrometry. Results We found that e-liquids caused a decrease in
ΔΨ m and
Vm and an increase in ROS production and
toxicity in a dose-dependent fashion. In addition, the presence of five
specific chemical components: vanillin, benzyl alcohol, acetoin,
cinnamaldehyde, and methyl-cyclopentenolone, but not nicotine, were linked
with the changes observed in the cellular traits studied. Conclusion Our data suggest that ΔΨ m, ROS,
Vm, and toxicity may be indicative of the
extent of cell death upon e-liquid exposure. Further research on the effect
of flavors should be prioritized to help policy makers such as the FDA to
regulate e-liquid composition. Implications E-liquid cellular toxicity can be predicted using parameters amenable to HTS.
Our data suggest that ΔΨ m, ROS,
Vm, and toxicity may be indicative of the
extent of cell death upon e-liquid exposure, and this toxicity is linked to
the chemical composition, that is, flavoring components. Further research on
the effect of flavors should be prioritized to help policy makers such as
the FDA to regulate e-liquid composition.
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Affiliation(s)
- Eva Correia-Álvarez
- Department of Cell Biology and Physiology, University of North
Carolina, Chapel Hill, NC
| | - James E Keating
- Department of Chemistry, University of North Carolina,
Chapel Hill, NC
| | - Gary Glish
- Department of Chemistry, University of North Carolina,
Chapel Hill, NC
| | - Robert Tarran
- Department of Cell Biology and Physiology, University of North
Carolina, Chapel Hill, NC
| | - M Flori Sassano
- Department of Cell Biology and Physiology, University of North
Carolina, Chapel Hill, NC
- Corresponding Author: M. Flori Sassano, PhD, Department of Cell
Biology and Physiology, University of North Carolina 115 Mason Farm Road, Chapel
Hill, NC 27599-7544, USA. Telephone: 919-966-7053; Fax: 919-966-6927; E-mail:
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Mason SA, Trewin AJ, Parker L, Wadley GD. Antioxidant supplements and endurance exercise: Current evidence and mechanistic insights. Redox Biol 2020; 35:101471. [PMID: 32127289 PMCID: PMC7284926 DOI: 10.1016/j.redox.2020.101471] [Citation(s) in RCA: 58] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Revised: 02/11/2020] [Accepted: 02/17/2020] [Indexed: 01/07/2023] Open
Abstract
Antioxidant supplements are commonly consumed by endurance athletes to minimize exercise-induced oxidative stress, with the intention of enhancing recovery and improving performance. There are numerous commercially available nutritional supplements that are targeted to athletes and health enthusiasts that allegedly possess antioxidant properties. However, most of these compounds are poorly investigated with respect to their in vivo redox activity and efficacy in humans. Therefore, this review will firstly provide a background to endurance exercise-related redox signalling and the subsequent adaptations in skeletal muscle and vascular function. The review will then discuss commonly available compounds with purported antioxidant effects for use by athletes. N-acetyl cysteine may be of benefit over the days prior to an endurance event; while chronic intake of combined 1000 mg vitamin C + vitamin E is not recommended during periods of heavy training associated with adaptations in skeletal muscle. Melatonin, vitamin E and α-lipoic acid appear effective at decreasing markers of exercise-induced oxidative stress. However, evidence on their effects on endurance performance are either lacking or not supportive. Catechins, anthocyanins, coenzyme Q10 and vitamin C may improve vascular function, however, evidence is either limited to specific sub-populations and/or does not translate to improved performance. Finally, additional research should clarify the potential benefits of curcumin in improving muscle recovery post intensive exercise; and the potential hampering effects of astaxanthin, selenium and vitamin A on skeletal muscle adaptations to endurance training. Overall, we highlight the lack of supportive evidence for most antioxidant compounds to recommend to athletes.
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Affiliation(s)
- Shaun A Mason
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, Geelong, Australia
| | - Adam J Trewin
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, Geelong, Australia
| | - Lewan Parker
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, Geelong, Australia
| | - Glenn D Wadley
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, Geelong, Australia.
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Isei MO, Kamunde C. Effects of copper and temperature on heart mitochondrial hydrogen peroxide production. Free Radic Biol Med 2020; 147:114-128. [PMID: 31825803 DOI: 10.1016/j.freeradbiomed.2019.12.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Revised: 12/05/2019] [Accepted: 12/05/2019] [Indexed: 11/19/2022]
Abstract
High energy demand for continuous mechanical work and large number of mitochondria predispose the heart to excessive reactive oxygen species (ROS) production that may precipitate oxidative stress and heart failure. While mitochondria have been proposed as a unifying cellular target and driver of adverse effects induced by diverse stressful states, there is limited understanding of how heart mitochondrial ROS homeostasis is affected by combinations of stress factors. Thus, we probed the effect of copper (Cu) and thermal stress on ROS (as hydrogen peroxide, H2O2) emission and elucidated the effects of Cu on ROS production sites in rainbow trout heart mitochondria using the Amplex UltraRed-horseradish peroxidase detection system optimized for our model. Mitochondria oxidizing malate-glutamate or succinate were incubated at 4, 11 (control) and 23 °C and exposed to a range (1-100 μM) of Cu concentrations. We found that the rates and patterns of H2O2 emission depended on substrate type, Cu concentration and temperature. In mitochondria oxidizing malate-glutamate, Cu increased the rate of H2O2 emission with a spike at 1 μM while temperature had no effect. In contrast, both temperature and Cu increased the rate of H2O2 emission in mitochondria oxidizing succinate with a prominent spike at 25 μM Cu. The rates of H2O2 emission at the three temperatures during the spike imposed by 25 μM Cu were of the order 11 > 23 > 4 °C. Interestingly, 5 μM Cu supressed H2O2 emission in mitochondria oxidizing succinate or malate-glutamate suggesting a common mechanism of action independent of substrate type. In the absence of Cu, the site-specific capacities of H2O2 emission were: complex III outer ubiquinone binding site (site IIIQo) > complex II flavin site (site IIF) ≥ complex I flavin site (site IF) > complex I ubiquinone-binding site (site IQ). Rotenone marginally increased succinate-driven H2O2 emission suggesting either the absence of reverse electron transport (RET)-driven ROS production at site IQ or masking of the expected rotenone response (reduction) by H2O2 produced from other sites. Cu acted at multiple sites in the electron transport system resulting in different site-specific H2O2 emission responses depending on the concentration. Specifically, site IF H2O2 emission was suppressed by Cu concentration-dependently while H2O2 emission by site IIF was inhibited and stimulated by low and high concentrations of Cu, respectively. Additionally, emission from site IIIQo was stimulated by low and inhibited by high Cu concentrations. Overall, our study unveiled distinctive effects and sites of modulation of mitochondrial ROS production by Cu with implications for cardiac redox signaling networks and development of mitochondria-targeted Cu-based drugs.
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Affiliation(s)
- Michael O Isei
- Department of Biomedical Sciences, Atlantic Veterinary College, University of Prince Edward Island, 550 University Avenue, Charlottetown, PE, C1A 4P3, Canada
| | - Collins Kamunde
- Department of Biomedical Sciences, Atlantic Veterinary College, University of Prince Edward Island, 550 University Avenue, Charlottetown, PE, C1A 4P3, Canada.
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12
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Wang HW, Zhang Y, Tan PP, Jia LS, Chen Y, Zhou BH. Mitochondrial respiratory chain dysfunction mediated by ROS is a primary point of fluoride-induced damage in Hepa1-6 cells. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2019; 255:113359. [PMID: 31614248 DOI: 10.1016/j.envpol.2019.113359] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2019] [Revised: 09/12/2019] [Accepted: 10/06/2019] [Indexed: 05/20/2023]
Abstract
To evaluate the mechanism of fluoride (F) mitochondrial toxicity, we cultured Hepa1-6 cells with different F concentrations (0, 1 and 2 mmoL/L) and determined cell pathological morphology, mitochondrial respiratory chain damage and cell cycle change. Results showed that the activities and mRNA expression levels of antioxidant enzymes considerably decreased, whereas the contents of reactive oxygen species (ROS), malondialdehyde (MDA) and nitric oxide (NO) markedly increased. Breakage of mitochondrial cristae and substantial vacuolated mitochondria were observed by transmission electron microscopy. These results indicate the F-induced oxidative damage in Hepa1-6 cells. The enzyme activities of mitochondrial complexes I, II, III and IV were disordered in Hepa1-6 cells treated by excessive F, thereby indicating a remarkable down-regulation. Further research showed that complex subunits also demonstrated the development of disorder, in which the protein expressions levels of NDUFV2 and SDHA were substantially down-regulated, whereas those of CYC1 and COX Ⅳ were markedly up-regulated. Reductions in ATP and mitochondrial membrane potential were detected with the dysfunction of the mitochondrial respiratory chain. The G2/M phase arrest of the cell cycle in Hepa1-6 cells was measured via flow cytometry, and the up-regulated protein expressions of Cyt c, caspase 9, caspase 3 and substantial apoptotic cells were determined. In summary, this study demonstrated that ROS-mediated mitochondrial respiratory chain dysfunction causes F-induced Hepa1-6 cell damage.
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Affiliation(s)
- Hong-Wei Wang
- Henan Key Laboratory of Environmental and Animal Product Safety, Henan University of Science and Technology, Luoyang 471003, Henan, China
| | - Yan Zhang
- Henan Key Laboratory of Environmental and Animal Product Safety, Henan University of Science and Technology, Luoyang 471003, Henan, China
| | - Pan-Pan Tan
- Henan Key Laboratory of Environmental and Animal Product Safety, Henan University of Science and Technology, Luoyang 471003, Henan, China
| | - Liu-Shu Jia
- Henan Key Laboratory of Environmental and Animal Product Safety, Henan University of Science and Technology, Luoyang 471003, Henan, China
| | - Yu Chen
- Henan Key Laboratory of Environmental and Animal Product Safety, Henan University of Science and Technology, Luoyang 471003, Henan, China
| | - Bian-Hua Zhou
- Henan Key Laboratory of Environmental and Animal Product Safety, Henan University of Science and Technology, Luoyang 471003, Henan, China.
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13
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Bunik VI. Redox-Driven Signaling: 2-Oxo Acid Dehydrogenase Complexes as Sensors and Transmitters of Metabolic Imbalance. Antioxid Redox Signal 2019; 30:1911-1947. [PMID: 30187773 DOI: 10.1089/ars.2017.7311] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
SIGNIFICANCE This article develops a holistic view on production of reactive oxygen species (ROS) by 2-oxo acid dehydrogenase complexes. Recent Advances: Catalytic and structural properties of the complexes and their components evolved to minimize damaging effects of side reactions, including ROS generation, simultaneously exploiting the reactions for homeostatic signaling. CRITICAL ISSUES Side reactions of the complexes, characterized in vitro, are analyzed in view of protein interactions and conditions in vivo. Quantitative data support prevalence of the forward 2-oxo acid oxidation over the backward NADH oxidation in feeding physiologically significant ROS production by the complexes. Special focus on interactions between the active sites within 2-oxo acid dehydrogenase complexes highlights the central relevance of the complex-bound thiyl radicals in regulation of and signaling by complex-generated ROS. The thiyl radicals arise when dihydrolipoyl residues of the complexes regenerate FADH2 from the flavin semiquinone coproduced with superoxide anion radical in 1e- oxidation of FADH2 by molecular oxygen. FUTURE DIRECTIONS Interaction of 2-oxo acid dehydrogenase complexes with thioredoxins (TRXs), peroxiredoxins, and glutaredoxins mediates scavenging of the thiyl radicals and ROS generated by the complexes, underlying signaling of disproportional availability of 2-oxo acids, CoA, and NAD+ in key metabolic branch points through thiol/disulfide exchange and medically important hypoxia-inducible factor, mammalian target of rapamycin (mTOR), poly (ADP-ribose) polymerase, and sirtuins. High reactivity of the coproduced ROS and thiyl radicals to iron/sulfur clusters and nitric oxide, peroxynitrite reductase activity of peroxiredoxins and transnitrosylating function of thioredoxin, implicate the side reactions of 2-oxo acid dehydrogenase complexes in nitric oxide-dependent signaling and damage.
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Affiliation(s)
- Victoria I Bunik
- 1 Belozersky Institute of Physicochemical Biology, Lomonosov Moscow State University, Moscow, Russian Federation.,2 Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Moscow, Russian Federation
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Rundle KI, Sharaf MS, Stevens D, Kamunde C, van den Heuvel MR. Oil Sands Derived Naphthenic Acids Are Oxidative Uncouplers and Impair Electron Transport in Isolated Mitochondria. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2018; 52:10803-10811. [PMID: 30102860 DOI: 10.1021/acs.est.8b02638] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Naphthenic acids (NAs) are predominant compounds in oil sands influenced waters. These acids cause numerous acute and chronic effects in fishes. However, the mechanism of toxicity underlying these effects has not been fully elucidated. Due to their carboxylic acid moiety and the reported disruption of cellular bioenergetics by similar structures, we hypothesized that NAs would uncouple mitochondrial respiration with the resultant production of reactive oxygen species (ROS). Naphthenic acids were extracted and purified from 17-year-old oil sands tailings waters yielding an extract of 99% carboxylic acids with 90% fitting the classical O2-NA definition. Mitochondria were isolated from rainbow trout liver and exposed to different concentrations of NAs. Mitochondrial respiration, membrane potential, and ROS emission were measured using the Oroboros fluorespirometry system. Additionally, mitochondrial ROS emission and membrane potential were evaluated with real-time flow cytometry. Results showed NAs uncoupled oxidative phosphorylation, inhibited respiration, and increased ROS emission. The effective concentration (EC50) and inhibition concentration (IC50) values for the end points measured ranged from 21.0 to 157.8 mg/L, concentrations similar to tailings waters. For the same end points, EC10/IC10 values ranged from 11.8 to 66.7 mg/L, approaching concentrations found in the environment. These data unveil mechanisms underlying effects of NAs that may contribute to adverse effects on organisms in the environment.
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Affiliation(s)
- Kate I Rundle
- Canadian Rivers Institute, Department of Biomedical Science, Atlantic Veterinary College , University of Prince Edward Island , Charlottetown , Canada C1A 4P3
| | - Mahmoud S Sharaf
- Department of Biomedical Science, Atlantic Veterinary College , University of Prince Edward Island , Charlottetown , Canada C1A 4P3
| | - Don Stevens
- Department of Biomedical Science, Atlantic Veterinary College , University of Prince Edward Island , Charlottetown , Canada C1A 4P3
| | - Collins Kamunde
- Department of Biomedical Science, Atlantic Veterinary College , University of Prince Edward Island , Charlottetown , Canada C1A 4P3
| | - Michael R van den Heuvel
- Canadian Rivers Institute, Department of Biomedical Science, Atlantic Veterinary College , University of Prince Edward Island , Charlottetown , Canada C1A 4P3
- Canadian Rivers Institute, Department of Biology , University of Prince Edward Island , Charlottetown , Canada C1A 4P3
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15
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Kamunde C, Sharaf M, MacDonald N. H 2O 2 metabolism in liver and heart mitochondria: Low emitting-high scavenging and high emitting-low scavenging systems. Free Radic Biol Med 2018; 124:135-148. [PMID: 29802890 DOI: 10.1016/j.freeradbiomed.2018.05.064] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Revised: 04/15/2018] [Accepted: 05/15/2018] [Indexed: 01/10/2023]
Abstract
Although mitochondria are presumed to emit and consume reactive oxygen species (ROS), the quantitative interplay between the two processes in ROS regulation is not well understood. Here, we probed the role of mitochondrial bioenergetics in H2O2 metabolism using rainbow trout liver and heart mitochondria. Both liver and heart mitochondria emitted H2O2 at rates that depended on their metabolic state, with the emission rates (free radical leak) constituting 0.8-2.9% and 0.2-2.5% of the respiration rate in liver and heart mitochondria, respectively. When presented with exogenous H2O2, liver and heart mitochondria consumed it by first order reactions with half-lives (s) of 117 and 210, and rate constants of 5.96 and 3.37 (× 10-3 s-1), respectively. The mitochondrial bioenergetic status greatly affected the rate of H2O2 consumption in heart but not liver mitochondria. Moreover, the activities and contribution of H2O2 scavenging systems varied between liver and heart mitochondria. The significance of the scavenging systems ranked by the magnitude (%) of inhibition of H2O2 removal after correcting for emission were, liver (un-energized and energized): catalase > glutathione (GSH) ≥ thioredoxin reductase (TrxR); un-energized heart mitochondria: catalase > TrxR > GSH and energized heart mitochondria: GSH > TrxR > catalase. Notably, depletion of GSH evoked a massive surge in H2O2 emission that grossly masked the contribution of this pathway to H2O2 scavenging in heart mitochondria. Irrespective of the organ of their origin, mitochondria behaved as H2O2 regulators that emitted or consumed it depending on the ambient H2O2 concentration, mitochondrial bioenergetic state and activity of the scavenging enzyme systems. Indeed, manipulation of mitochondrial bioenergetics and H2O2 scavenging systems caused mitochondria to switch from being net consumers to net emitters of H2O2. Overall, our data suggest that the low levels of H2O2 typically present in cells would favor emission of this metabolite but the scavenging systems would prevent its accumulation.
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Affiliation(s)
- Collins Kamunde
- Department of Biomedical Sciences, Atlantic Veterinary College, University of Prince Edward Island, 550 University Avenue, Charlottetown, PE, Canada C1A 4P3.
| | - Mahmoud Sharaf
- Department of Biomedical Sciences, Atlantic Veterinary College, University of Prince Edward Island, 550 University Avenue, Charlottetown, PE, Canada C1A 4P3
| | - Nicole MacDonald
- Department of Biomedical Sciences, Atlantic Veterinary College, University of Prince Edward Island, 550 University Avenue, Charlottetown, PE, Canada C1A 4P3
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16
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Berry BJ, Trewin AJ, Amitrano AM, Kim M, Wojtovich AP. Use the Protonmotive Force: Mitochondrial Uncoupling and Reactive Oxygen Species. J Mol Biol 2018; 430:3873-3891. [PMID: 29626541 DOI: 10.1016/j.jmb.2018.03.025] [Citation(s) in RCA: 102] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Revised: 03/21/2018] [Accepted: 03/26/2018] [Indexed: 02/06/2023]
Abstract
Mitochondrial respiration results in an electrochemical proton gradient, or protonmotive force (pmf), across the mitochondrial inner membrane. The pmf is a form of potential energy consisting of charge (∆ψm) and chemical (∆pH) components, that together drive ATP production. In a process called uncoupling, proton leak into the mitochondrial matrix independent of ATP production dissipates the pmf and energy is lost as heat. Other events can directly dissipate the pmf independent of ATP production as well, such as chemical exposure or mechanisms involving regulated mitochondrial membrane electrolyte transport. Uncoupling has defined roles in metabolic plasticity and can be linked through signal transduction to physiologic events. In the latter case, the pmf impacts mitochondrial reactive oxygen species (ROS) production. Although capable of molecular damage, ROS also have signaling properties that depend on the timing, location, and quantity of their production. In this review, we provide a general overview of mitochondrial ROS production, mechanisms of uncoupling, and how these work in tandem to affect physiology and pathologies, including obesity, cardiovascular disease, and immunity. Overall, we highlight that isolated bioenergetic models-mitochondria and cells-only partially recapitulate the complex link between the pmf and ROS signaling that occurs in vivo.
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Affiliation(s)
- Brandon J Berry
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Box 711/604, 575 Elmwood Ave., Rochester, NY 14642, USA.
| | - Adam J Trewin
- Department of Anesthesiology and Perioperative Medicine, University of Rochester Medical Center, Box 711/604, 575 Elmwood Ave., Rochester, NY 14642, USA.
| | - Andrea M Amitrano
- Department of Pathology, University of Rochester Medical Center, Box 609, 601 Elmwood Ave., Rochester, NY 14642, USA; Department of Microbiology and Immunology, University of Rochester Medical Center, Box 609, 601 Elmwood Ave., Rochester, NY 14642, USA.
| | - Minsoo Kim
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Box 711/604, 575 Elmwood Ave., Rochester, NY 14642, USA; Department of Pathology, University of Rochester Medical Center, Box 609, 601 Elmwood Ave., Rochester, NY 14642, USA; Department of Microbiology and Immunology, University of Rochester Medical Center, Box 609, 601 Elmwood Ave., Rochester, NY 14642, USA.
| | - Andrew P Wojtovich
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Box 711/604, 575 Elmwood Ave., Rochester, NY 14642, USA; Department of Anesthesiology and Perioperative Medicine, University of Rochester Medical Center, Box 711/604, 575 Elmwood Ave., Rochester, NY 14642, USA.
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