1
|
Hernansanz-Agustín P, Morales-Vidal C, Calvo E, Natale P, Martí-Mateos Y, Jaroszewicz SN, Cabrera-Alarcón JL, Acín-Pérez R, López-Montero I, Vázquez J, Enríquez JA. A transmitochondrial sodium gradient controls membrane potential in mammalian mitochondria. Cell 2024:S0092-8674(24)00974-7. [PMID: 39303716 DOI: 10.1016/j.cell.2024.08.045] [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: 01/22/2024] [Revised: 07/02/2024] [Accepted: 08/21/2024] [Indexed: 09/22/2024]
Abstract
Eukaryotic cell function and survival rely on the use of a mitochondrial H+ electrochemical gradient (Δp), which is composed of an inner mitochondrial membrane (IMM) potential (ΔΨmt) and a pH gradient (ΔpH). So far, ΔΨmt has been assumed to be composed exclusively of H+. Here, using a rainbow of mitochondrial and nuclear genetic models, we have discovered that a Na+ gradient equates with the H+ gradient and controls half of ΔΨmt in coupled-respiring mammalian mitochondria. This parallelism is controlled by the activity of the long-sought Na+-specific Na+/H+ exchanger (mNHE), which we have identified as the P-module of complex I (CI). Deregulation of this mNHE function, without affecting the canonical enzymatic activity or the assembly of CI, occurs in Leber's hereditary optic neuropathy (LHON), which has profound consequences in ΔΨmt and mitochondrial Ca2+ homeostasis and explains the previously unknown molecular pathogenesis of this neurodegenerative disease.
Collapse
Affiliation(s)
- Pablo Hernansanz-Agustín
- Centro Nacional de Investigaciones Cardiovasculares Carlos III (CNIC), Madrid 28029, Spain; Centro de Investigación Biomédica en Red de Fragilidad y Envejecimiento Saludable, Madrid, Spain.
| | - Carmen Morales-Vidal
- Centro Nacional de Investigaciones Cardiovasculares Carlos III (CNIC), Madrid 28029, Spain
| | - Enrique Calvo
- Centro Nacional de Investigaciones Cardiovasculares Carlos III (CNIC), Madrid 28029, Spain; Centro de Investigación Biomédica en Red de Enfermedades Cardiovasculares (CIBER-CV), Madrid, Spain
| | - Paolo Natale
- Departamento de Química-Física, Facultad de Ciencias Químicas, Universidad Complutense de Madrid (UCM), Madrid, Spain; Instituto de Investigación Biomédica Hospital Doce de Octubre (imas12), Madrid, Spain
| | - Yolanda Martí-Mateos
- Centro Nacional de Investigaciones Cardiovasculares Carlos III (CNIC), Madrid 28029, Spain
| | | | | | - Rebeca Acín-Pérez
- Department of Medicine, Endocrinology, David Geffen School of Medicine, UCLA, Los Angeles, CA 90095, USA
| | - Iván López-Montero
- Departamento de Química-Física, Facultad de Ciencias Químicas, Universidad Complutense de Madrid (UCM), Madrid, Spain; Instituto de Investigación Biomédica Hospital Doce de Octubre (imas12), Madrid, Spain; Instituto Pluridisciplinar-UCM, Madrid, Spain
| | - Jesús Vázquez
- Centro Nacional de Investigaciones Cardiovasculares Carlos III (CNIC), Madrid 28029, Spain; Centro de Investigación Biomédica en Red de Enfermedades Cardiovasculares (CIBER-CV), Madrid, Spain
| | - José Antonio Enríquez
- Centro Nacional de Investigaciones Cardiovasculares Carlos III (CNIC), Madrid 28029, Spain; Centro de Investigación Biomédica en Red de Fragilidad y Envejecimiento Saludable, Madrid, Spain.
| |
Collapse
|
2
|
Ježek P, Dlasková A, Engstová H, Špačková J, Tauber J, Průchová P, Kloppel E, Mozheitova O, Jabůrek M. Mitochondrial Physiology of Cellular Redox Regulations. Physiol Res 2024; 73:S217-S242. [PMID: 38647168 PMCID: PMC11412358 DOI: 10.33549/physiolres.935269] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/04/2024] Open
Abstract
Mitochondria (mt) represent the vital hub of the molecular physiology of the cell, being decision-makers in cell life/death and information signaling, including major redox regulations and redox signaling. Now we review recent advances in understanding mitochondrial redox homeostasis, including superoxide sources and H2O2 consumers, i.e., antioxidant mechanisms, as well as exemplar situations of physiological redox signaling, including the intramitochondrial one and mt-to-cytosol redox signals, which may be classified as acute and long-term signals. This review exemplifies the acute redox signals in hypoxic cell adaptation and upon insulin secretion in pancreatic beta-cells. We also show how metabolic changes under these circumstances are linked to mitochondrial cristae narrowing at higher intensity of ATP synthesis. Also, we will discuss major redox buffers, namely the peroxiredoxin system, which may also promote redox signaling. We will point out that pathological thresholds exist, specific for each cell type, above which the superoxide sources exceed regular antioxidant capacity and the concomitant harmful processes of oxidative stress subsequently initiate etiology of numerous diseases. The redox signaling may be impaired when sunk in such excessive pro-oxidative state.
Collapse
Affiliation(s)
- P Ježek
- Laboratory of Mitochondrial Physiology, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic.
| | | | | | | | | | | | | | | | | |
Collapse
|
3
|
Chenna S, Koopman WJH, Prehn JHM, Connolly NMC. Mechanisms and mathematical modelling of ROS production by the mitochondrial electron transport chain. Am J Physiol Cell Physiol 2022; 323:C69-C83. [PMID: 35613354 DOI: 10.1152/ajpcell.00455.2021] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Reactive oxygen species (ROS) are recognised both as damaging molecules and intracellular signalling entities. In addition to its role in ATP generation, the mitochondrial electron transport chain (ETC) constitutes a relevant source of mitochondrial ROS, in particular during pathological conditions. Mitochondrial ROS homeostasis depends on species- and site-dependent ROS production, their bioreactivity, diffusion, and scavenging. However, our quantitative understanding of mitochondrial ROS homeostasis has thus far been hampered by technical limitations, including lack of truly site- and/or ROS-specific reporter molecules. In this context, the use of computational models is of great value to complement and interpret empirical data, as well as to predict variables that are difficult to assess experimentally. During the last decades, various mechanistic models of ETC-mediated ROS production have been developed. Although these often-complex models have generated novel insights, their parameterisation, analysis, and integration with other computational models is not straightforward. In contrast, phenomenological (sometimes termed "minimal") models use a relatively small set of equations to describe empirical relationship(s) between ROS-related and other parameters, and generally aim to explore system behaviour and generate hypotheses for experimental validation. In this review, we first discuss ETC-linked ROS homeostasis and introduce various detailed mechanistic models. Next, we present how bioenergetic parameters (e.g. NADH/NAD+ ratio, mitochondrial membrane potential) relate to site-specific ROS production within the ETC and how these relationships can be used to design minimal models of ROS homeostasis. Finally, we illustrate how minimal models have been applied to explore pathophysiological aspects of ROS.
Collapse
Affiliation(s)
- Sandeep Chenna
- Centre for Systems Medicine, Department of Physiology and Medical Physics, Royal College of Surgeons in Ireland, Dublin, Ireland
| | - Werner J H Koopman
- Department of Pediatrics, Amalia Children's Hospital, Radboud Institute for Molecular Life Sciences (RIMLS), Radboud Center for Mitochondrial Disorders (RCMM), Radboud University Medical Center (Radboudumc), Nijmegen, The Netherlands.,Human and Animal Physiology, Wageningen University, Wageningen, The Netherlands
| | - Jochen H M Prehn
- Centre for Systems Medicine, Department of Physiology and Medical Physics, Royal College of Surgeons in Ireland, Dublin, Ireland.,SFI FutureNeuro Research Centre, Dublin, Ireland
| | - Niamh M C Connolly
- Centre for Systems Medicine, Department of Physiology and Medical Physics, Royal College of Surgeons in Ireland, Dublin, Ireland
| |
Collapse
|
4
|
Kumar R, Jafri MS. Computational Modeling of Mitochondria to Understand the Dynamics of Oxidative Stress. Methods Mol Biol 2022; 2497:363-422. [PMID: 35771458 PMCID: PMC9811848 DOI: 10.1007/978-1-0716-2309-1_27] [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] [Indexed: 01/14/2023]
Abstract
Mitochondria are complex organelles that use catabolic metabolism to produce ATP which is the critical energy source for cell function. Oxidative phosphorylation by the electron transport chain, which receives reducing equivalents (NADH and FADH2) from the tricarboxylic acid cycle, also produces reactive oxygen species (ROS) as a by-product at complex I and III. ROS play a significant role in health and disease. In order to better understand this process, a computational model of mitochondrial energy metabolism and the production of ROS has been developed. The model demonstrates the process regulating ROS production and removal and how different energy substrates can affect ROS production.
Collapse
Affiliation(s)
- Rashmi Kumar
- School of Systems Biology, George Mason University, Fairfax, VA, USA
| | - Mohsin S Jafri
- School of Systems Biology, George Mason University, Fairfax, VA, USA.
- Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, MD, USA.
| |
Collapse
|
5
|
Manoli SS, Kisor K, Webb BA, Barber DL. Ethyl isopropyl amiloride decreases oxidative phosphorylation and increases mitochondrial fusion in clonal untransformed and cancer cells. Am J Physiol Cell Physiol 2021; 321:C147-C157. [PMID: 34038242 DOI: 10.1152/ajpcell.00001.2021] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Many cancer cells, regardless of their tissue origin or genetic landscape, have increased expression or activity of the plasma membrane Na-H exchanger NHE1 and a higher intracellular pH (pHi) compared with untransformed cells. A current perspective that remains to be validated is that increased NHE1 activity and pHi enable a Warburg-like metabolic reprogramming of increased glycolysis and decreased mitochondrial oxidative phosphorylation. We tested this perspective and find it is not accurate for clonal pancreatic and breast cancer cells. Using the pharmacological reagent ethyl isopropyl amiloride (EIPA) to inhibit NHE1 activity and decrease pHi, we observe no change in glycolysis, as indicated by secreted lactate and intracellular pyruvate, despite confirming increased activity of the glycolytic enzyme phosphofructokinase-1 at higher pH. Also, in contrast to predictions, we find a significant decrease in oxidative phosphorylation with EIPA, as indicated by oxygen consumption rate (OCR). Decreased OCR with EIPA is not associated with changes in pathways that fuel oxidative phosphorylation or with mitochondrial membrane potential but occurs with a change in mitochondrial dynamics that includes a significant increase in elongated mitochondrial networks, suggesting increased fusion. These findings conflict with current paradigms on increased pHi inhibiting oxidative phosphorylation and increased oxidative phosphorylation being associated with mitochondrial fusion. Moreover, these findings raise questions on the suggested use of EIPA-like compounds to limit metabolic reprogramming in cancer cells.
Collapse
Affiliation(s)
- Sagar S Manoli
- Department of Cell and Tissue Biology, University of California, San Francisco, California
| | - Kyle Kisor
- Department of Cell and Tissue Biology, University of California, San Francisco, California
| | - Bradley A Webb
- Department of Biochemistry, West Virginia University, Morgantown, West Virginia
| | - Diane L Barber
- Department of Cell and Tissue Biology, University of California, San Francisco, California
| |
Collapse
|
6
|
Nieuwenhuijs-Moeke GJ, Bosch DJ, Leuvenink HG. Molecular Aspects of Volatile Anesthetic-Induced Organ Protection and Its Potential in Kidney Transplantation. Int J Mol Sci 2021; 22:ijms22052727. [PMID: 33800423 PMCID: PMC7962839 DOI: 10.3390/ijms22052727] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Revised: 02/25/2021] [Accepted: 03/03/2021] [Indexed: 12/16/2022] Open
Abstract
Ischemia reperfusion injury (IRI) is inevitable in kidney transplantation and negatively impacts graft and patient outcome. Reperfusion takes place in the recipient and most of the injury following ischemia and reperfusion occurs during this reperfusion phase; therefore, the intra-operative period seems an attractive window of opportunity to modulate IRI and improve short- and potentially long-term graft outcome. Commonly used volatile anesthetics such as sevoflurane and isoflurane have been shown to interfere with many of the pathophysiological processes involved in the injurious cascade of IRI. Therefore, volatile anesthetic (VA) agents might be the preferred anesthetics used during the transplantation procedure. This review highlights the molecular and cellular protective points of engagement of VA shown in in vitro studies and in vivo animal experiments, and the potential translation of these results to the clinical setting of kidney transplantation.
Collapse
Affiliation(s)
- Gertrude J. Nieuwenhuijs-Moeke
- Department of Anesthesiology, University Medical Centre Groningen, University of Groningen, Hanzeplein 1, 9713 GZ Groningen, The Netherlands;
- Correspondence: ; Tel.: +31-631623075
| | - Dirk J. Bosch
- Department of Anesthesiology, University Medical Centre Groningen, University of Groningen, Hanzeplein 1, 9713 GZ Groningen, The Netherlands;
| | - Henri G.D. Leuvenink
- Department of Surgery, University Medical Centre Groningen, University of Groningen, Hanzeplein 1, 9713 GZ Groningen, The Netherlands;
| |
Collapse
|
7
|
Draper ACE, Wilson Z, Maile C, Faccenda D, Campanella M, Piercy RJ. Species-specific consequences of an E40K missense mutation in superoxide dismutase 1 (SOD1). FASEB J 2019; 34:458-473. [PMID: 31914665 DOI: 10.1096/fj.201901455r] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Revised: 09/25/2019] [Accepted: 10/08/2019] [Indexed: 11/11/2022]
Abstract
A glutamic acid to lysine (E40K) residue substitution in superoxide dismutase 1 (SOD1) is associated with canine degenerative myelopathy: the only naturally occurring large animal model of amyotrophic lateral sclerosis (ALS). The E40 residue is highly conserved across mammals, except the horse, which naturally carries the (dog mutant) K40 residue. Here we hypothesized that in vitro expression of mutant dog SOD1 would recapitulate features of human ALS (ie, SOD1 protein aggregation, reduced cell viability, perturbations in mitochondrial morphology and membrane potential, reduced ATP production, and increased superoxide ion levels); further, we hypothesized that an equivalent equine SOD1 variant would share similar perturbations in vitro, thereby explain horses' susceptibility to certain neurodegenerative diseases. As in human ALS, expression of mutant dog SOD1 was associated with statistically significant increased aggregate formation, raised superoxide levels (ROS), and altered mitochondrial morphology (increased branching (form factor)), when compared to wild-type dog SOD1-expressing cells. Similar deficits were not detected in cells expressing the equivalent horse SOD1 variant. Our data helps explain the ALS-associated cellular phenotype of dogs expressing the mutant SOD1 protein and reveals that species-specific sequence conservation does not necessarily predict pathogenicity. The work improves understanding of the etiopathogenesis of canine degenerative myelopathy.
Collapse
Affiliation(s)
- Alexandra C E Draper
- Comparative Neuromuscular Disease Laboratory, Royal Veterinary College, University of London, London, UK
| | - Zoe Wilson
- Comparative Neuromuscular Disease Laboratory, Royal Veterinary College, University of London, London, UK
| | - Charlotte Maile
- Comparative Neuromuscular Disease Laboratory, Royal Veterinary College, University of London, London, UK
| | - Danilo Faccenda
- Mitochondrial Cell Biology and Pharmaceutical Research Unit, Department of Comparative Biomedical Sciences, Royal Veterinary College, University of London, London, UK
| | - Michelangelo Campanella
- Mitochondrial Cell Biology and Pharmaceutical Research Unit, Department of Comparative Biomedical Sciences, Royal Veterinary College, University of London, London, UK.,University College London Consortium for Mitochondrial Research, University College London, University of London, London, UK
| | - Richard J Piercy
- Comparative Neuromuscular Disease Laboratory, Royal Veterinary College, University of London, London, UK
| |
Collapse
|
8
|
Patel B, Zheleznova NN, Ray SC, Sun J, Cowley AW, O'Connor PM. Voltage gated proton channels modulate mitochondrial reactive oxygen species production by complex I in renal medullary thick ascending limb. Redox Biol 2019; 27:101191. [PMID: 31060879 PMCID: PMC6859587 DOI: 10.1016/j.redox.2019.101191] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2019] [Revised: 04/02/2019] [Accepted: 04/05/2019] [Indexed: 11/24/2022] Open
Abstract
Hv1 is a voltage-gated proton channel highly expressed in immune cells where, it acts to maintain NAD(P)H oxidase activity during the respiratory burst. We have recently reported that Hv1 is expressed in cells of the medullary thick ascending limb (mTAL) of the kidney and is critical to augment reactive oxygen species (ROS) production by this segment. While Hv1 is associated with NOX2 mediated ROS production in immune cells, the source of the Hv1 dependent ROS in mTAL remains unknown. In the current study, the rate of ROS formation was quantified in freshly isolated mTAL using dihydroethidium and ethidium fluorescence. Hv1 dependent ROS production was stimulated by increasing bath osmolality and ammonium chloride (NH4Cl) loading. Loss of either p67phox or NOX4 did not abolish the formation of ROS in mTAL. Hv1 was localized to mitochondria within mTAL, and the mitochondrial superoxide scavenger mitoTEMPOL reduced ROS formation. Rotenone significantly increased ROS formation and decreased mitochondrial membrane potential in mTAL from wild-type rats, while treatment with this inhibitor decreased ROS formation and increased mitochondrial membrane potential in mTAL from Hv1−/− mutant rats. These data indicate that NADPH oxidase is not the primary source of Hv1 dependent ROS production in mTAL. Rather Hv1 localizes to the mitochondria in mTAL and modulates the formation of ROS by complex I. These data provide a potential explanation for the effects of Hv1 on ROS production in cells independent of its contribution to maintenance of cell membrane potential and intracellular pH.
Collapse
Affiliation(s)
- Bansari Patel
- Department of Physiology, Medical College of Georgia, Augusta, Georgia, USA
| | | | - Sarah C Ray
- Department of Physiology, Medical College of Georgia, Augusta, Georgia, USA
| | - Jingping Sun
- Department of Physiology, Medical College of Georgia, Augusta, Georgia, USA
| | - Allen W Cowley
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Paul M O'Connor
- Department of Physiology, Medical College of Georgia, Augusta, Georgia, USA.
| |
Collapse
|
9
|
Zielonka J, Kalyanaraman B. Small-molecule luminescent probes for the detection of cellular oxidizing and nitrating species. Free Radic Biol Med 2018; 128:3-22. [PMID: 29567392 PMCID: PMC6146080 DOI: 10.1016/j.freeradbiomed.2018.03.032] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Revised: 03/09/2018] [Accepted: 03/16/2018] [Indexed: 01/24/2023]
Abstract
Reactive oxygen species (ROS) have been implicated in both pathogenic cellular damage events and physiological cellular redox signaling and regulation. To unravel the biological role of ROS, it is very important to be able to detect and identify the species involved. In this review, we introduce the reader to the methods of detection of ROS using luminescent (fluorescent, chemiluminescent, and bioluminescent) probes and discuss typical limitations of those probes. We review the most widely used probes, state-of-the-art assays, and the new, promising approaches for rigorous detection and identification of superoxide radical anion, hydrogen peroxide, and peroxynitrite. The combination of real-time monitoring of the dynamics of ROS in cells and the identification of the specific products formed from the probes will reveal the role of specific types of ROS in cellular function and dysfunction. Understanding the molecular mechanisms involving ROS may help with the development of new therapeutics for several diseases involving dysregulated cellular redox status.
Collapse
Affiliation(s)
- Jacek Zielonka
- Department of Biophysics, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, United States; Free Radical Research Center, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, United States; Cancer Center, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, United States.
| | - Balaraman Kalyanaraman
- Department of Biophysics, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, United States; Free Radical Research Center, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, United States; Cancer Center, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, United States
| |
Collapse
|
10
|
Ježek P, Holendová B, Garlid KD, Jabůrek M. Mitochondrial Uncoupling Proteins: Subtle Regulators of Cellular Redox Signaling. Antioxid Redox Signal 2018; 29:667-714. [PMID: 29351723 PMCID: PMC6071544 DOI: 10.1089/ars.2017.7225] [Citation(s) in RCA: 80] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
SIGNIFICANCE Mitochondria are the energetic, metabolic, redox, and information signaling centers of the cell. Substrate pressure, mitochondrial network dynamics, and cristae morphology state are integrated by the protonmotive force Δp or its potential component, ΔΨ, which are attenuated by proton backflux into the matrix, termed uncoupling. The mitochondrial uncoupling proteins (UCP1-5) play an eminent role in the regulation of each of the mentioned aspects, being involved in numerous physiological events including redox signaling. Recent Advances: UCP2 structure, including purine nucleotide and fatty acid (FA) binding sites, strongly support the FA cycling mechanism: UCP2 expels FA anions, whereas uncoupling is achieved by the membrane backflux of protonated FA. Nascent FAs, cleaved by phospholipases, are preferential. The resulting Δp dissipation decreases superoxide formation dependent on Δp. UCP-mediated antioxidant protection and its impairment are expected to play a major role in cell physiology and pathology. Moreover, UCP2-mediated aspartate, oxaloacetate, and malate antiport with phosphate is expected to alter metabolism of cancer cells. CRITICAL ISSUES A wide range of UCP antioxidant effects and participations in redox signaling have been reported; however, mechanisms of UCP activation are still debated. Switching off/on the UCP2 protonophoretic function might serve as redox signaling either by employing/releasing the extra capacity of cell antioxidant systems or by directly increasing/decreasing mitochondrial superoxide sources. Rapid UCP2 degradation, FA levels, elevation of purine nucleotides, decreased Mg2+, or increased pyruvate accumulation may initiate UCP-mediated redox signaling. FUTURE DIRECTIONS Issues such as UCP2 participation in glucose sensing, neuronal (synaptic) function, and immune cell activation should be elucidated. Antioxid. Redox Signal. 29, 667-714.
Collapse
Affiliation(s)
- Petr Ježek
- 1 Department of Mitochondrial Physiology, Institute of Physiology of the Czech Academy of Sciences , Prague, Czech Republic
| | - Blanka Holendová
- 1 Department of Mitochondrial Physiology, Institute of Physiology of the Czech Academy of Sciences , Prague, Czech Republic
| | - Keith D Garlid
- 2 UCLA Cardiovascular Research Laboratory, David Geffen School of Medicine at UCLA , Los Angeles, California
| | - Martin Jabůrek
- 1 Department of Mitochondrial Physiology, Institute of Physiology of the Czech Academy of Sciences , Prague, Czech Republic
| |
Collapse
|
11
|
Komlódi T, Geibl FF, Sassani M, Ambrus A, Tretter L. Membrane potential and delta pH dependency of reverse electron transport-associated hydrogen peroxide production in brain and heart mitochondria. J Bioenerg Biomembr 2018; 50:355-365. [PMID: 30116920 PMCID: PMC6209044 DOI: 10.1007/s10863-018-9766-8] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2018] [Accepted: 07/30/2018] [Indexed: 12/19/2022]
Abstract
Succinate-driven reverse electron transport (RET) is one of the main sources of mitochondrial reactive oxygen species (mtROS) in ischemia-reperfusion injury. RET is dependent on mitochondrial membrane potential (Δψm) and transmembrane pH difference (ΔpH), components of the proton motive force (pmf); a decrease in Δψm and/or ΔpH inhibits RET. In this study we aimed to determine which component of the pmf displays the more dominant effect on RET-provoked ROS generation in isolated guinea pig brain and heart mitochondria respiring on succinate or α-glycerophosphate (α-GP). Δψm was detected via safranin fluorescence and a TPP+ electrode, the rate of H2O2 formation was measured by Amplex UltraRed, the intramitochondrial pH (pHin) was assessed via BCECF fluorescence. Ionophores were used to dissect the effects of the two components of pmf. The K+/H+ exchanger, nigericin lowered pHin and ΔpH, followed by a compensatory increase in Δψm that led to an augmented H2O2 production. Valinomycin, a K+ ionophore, at low [K+] increased ΔpH and pHin, decreased Δψm, which resulted in a decline in H2O2 formation. It was concluded that Δψm is dominant over ∆pH in modulating the succinate- and α-GP-evoked RET. The elevation of extramitochondrial pH was accompanied by an enhanced H2O2 release and a decreased ∆pH. This phenomenon reveals that from the pH component not ∆pH, but rather absolute value of pH has higher impact on the rate of mtROS formation. Minor decrease of Δψm might be applied as a therapeutic strategy to attenuate RET-driven ROS generation in ischemia-reperfusion injury.
Collapse
Affiliation(s)
- Tímea Komlódi
- Department of Medical Biochemistry, MTA-SE Laboratory for Neurobiochemistry, Semmelweis University, 37-47 Tűzoltó St, Budapest, 1094, Hungary
| | - Fanni F Geibl
- Department of Medical Biochemistry, MTA-SE Laboratory for Neurobiochemistry, Semmelweis University, 37-47 Tűzoltó St, Budapest, 1094, Hungary.,Department of Neurology, Philipps University Marburg, 35043, Marburg, Germany
| | - Matilde Sassani
- Department of Medical Biochemistry, MTA-SE Laboratory for Neurobiochemistry, Semmelweis University, 37-47 Tűzoltó St, Budapest, 1094, Hungary.,Department of Neuroscience, Sheffield Institute for Translational Neuroscience (SITraN), University of Sheffield, Sheffield, UK
| | - Attila Ambrus
- Department of Medical Biochemistry, MTA-SE Laboratory for Neurobiochemistry, Semmelweis University, 37-47 Tűzoltó St, Budapest, 1094, Hungary
| | - László Tretter
- Department of Medical Biochemistry, MTA-SE Laboratory for Neurobiochemistry, Semmelweis University, 37-47 Tűzoltó St, Budapest, 1094, Hungary.
| |
Collapse
|
12
|
Plecitá-Hlavatá L, Tauber J, Li M, Zhang H, Flockton AR, Pullamsetti SS, Chelladurai P, D'Alessandro A, El Kasmi KC, Ježek P, Stenmark KR. Constitutive Reprogramming of Fibroblast Mitochondrial Metabolism in Pulmonary Hypertension. Am J Respir Cell Mol Biol 2017; 55:47-57. [PMID: 26699943 DOI: 10.1165/rcmb.2015-0142oc] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Remodeling of the distal pulmonary artery wall is a characteristic feature of pulmonary hypertension (PH). In hypoxic PH, the most substantial pathologic changes occur in the adventitia. Here, there is marked fibroblast proliferation and profound macrophage accumulation. These PH fibroblasts (PH-Fibs) maintain a hyperproliferative, apoptotic-resistant, and proinflammatory phenotype in ex vivo culture. Considering that a similar phenotype is observed in cancer cells, where it has been associated, at least in part, with specific alterations in mitochondrial metabolism, we sought to define the state of mitochondrial metabolism in PH-Fibs. In PH-Fibs, pyruvate dehydrogenase was markedly inhibited, resulting in metabolism of pyruvate to lactate, thus consistent with a Warburg-like phenotype. In addition, mitochondrial bioenergetics were suppressed and mitochondrial fragmentation was increased in PH-Fibs. Most importantly, complex I activity was substantially decreased, which was associated with down-regulation of the accessory subunit nicotinamide adenine dinucleotide reduced dehydrogenase (ubiquinone) Fe-S protein 4 (NDUFS4). Owing to less-efficient ATP synthesis, mitochondria were hyperpolarized and mitochondrial superoxide production was increased. This pro-oxidative status was further augmented by simultaneous induction of cytosolic nicotinamide adenine dinucleotide phosphate reduced oxidase 4. Although acute and chronic exposure to hypoxia of adventitial fibroblasts from healthy control vessels induced increased glycolysis, it did not induce complex I deficiency as observed in PH-Fibs. This suggests that hypoxia alone is insufficient to induce NDUFS4 down-regulation and constitutive abnormalities in complex I. In conclusion, our study provides evidence that, in the pathogenesis of vascular remodeling in PH, alterations in fibroblast mitochondrial metabolism drive distinct changes in cellular behavior, which potentially occur independently of hypoxia.
Collapse
Affiliation(s)
- Lydie Plecitá-Hlavatá
- 1 Department of Membrane Transport Biophysics, Institute of Physiology, Czech Academy of Sciences, Prague, Czech Republic
| | - Jan Tauber
- 1 Department of Membrane Transport Biophysics, Institute of Physiology, Czech Academy of Sciences, Prague, Czech Republic
| | - Min Li
- 2 Developmental Lung Biology and Cardiovascular Pulmonary Research Laboratory, University of Colorado, Denver, Colorado
| | - Hui Zhang
- 2 Developmental Lung Biology and Cardiovascular Pulmonary Research Laboratory, University of Colorado, Denver, Colorado.,3 Department of Pediatrics, Shengjing Hospital of China Medical, University, Shenyang, China
| | - Amanda R Flockton
- 2 Developmental Lung Biology and Cardiovascular Pulmonary Research Laboratory, University of Colorado, Denver, Colorado
| | - Soni Savai Pullamsetti
- 4 Department of Lung Development and Remodeling, University of Giessen and Marburg Lung Center, Bad Nauheim, Germany; and
| | - Prakash Chelladurai
- 4 Department of Lung Development and Remodeling, University of Giessen and Marburg Lung Center, Bad Nauheim, Germany; and
| | | | - Karim C El Kasmi
- 6 Pediatric Gastroenterology, University of Colorado, Denver, Colorado
| | - Petr Ježek
- 1 Department of Membrane Transport Biophysics, Institute of Physiology, Czech Academy of Sciences, Prague, Czech Republic
| | - Kurt R Stenmark
- 2 Developmental Lung Biology and Cardiovascular Pulmonary Research Laboratory, University of Colorado, Denver, Colorado
| |
Collapse
|
13
|
Ježek J, Engstová H, Ježek P. Antioxidant mechanism of mitochondria-targeted plastoquinone SkQ1 is suppressed in aglycemic HepG2 cells dependent on oxidative phosphorylation. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2017; 1858:750-762. [PMID: 28554565 DOI: 10.1016/j.bbabio.2017.05.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Revised: 05/17/2017] [Accepted: 05/24/2017] [Indexed: 12/19/2022]
Abstract
Previously suggested antioxidant mechanisms for mitochondria-targeted plastoquinone SkQ1 included: i) ion-pairing of cationic SkQ1+ with free fatty acid anions resulting in uncoupling; ii) SkQ1H2 ability to interact with lipoperoxyl radical; iii) interference with electron flow at the inner ubiquinone (Q) binding site of Complex III (Qi), involving the reduction of SkQ1 to SkQ1H2 by ubiquinol. We elucidated SkQ1 antioxidant properties by confocal fluorescence semi-quantification of mitochondrial superoxide (Jm) and cytosolic H2O2 (Jc) release rates in HepG2 cells. Only in glycolytic cells, SkQ1 prevented the rotenone-induced enhancement of Jm and Jc but not basal releases without rotenone. The effect ceased in glutaminolytic aglycemic cells, in which the redox parameter NAD(P)H/FAD increased after rotenone in contrast to its decrease in glycolytic cells. Autofluorescence decay indicated decreased NADPH/NADH ratios with rotenone in both metabolic modes. SkQ1 did not increase cell respiration and diminished Jm established high by antimycin or myxothiazol but not by stigmatellin. The revealed SkQ1 antioxidant modes reflect its reduction to SkQ1H2 at Complex I IQ or Complex III Qi site. Both reductions diminish electron diversions to oxygen thus attenuating superoxide formation. Resulting SkQ1H2 oxidizes back to SkQ1at the second (flavin) Complex I site, previously indicated for MitoQ10. Regeneration proceeds only at lower NAD(P)H/FAD in glycolytic cells. In contrast, cyclic SkQ1 reduction/SkQ1H2 oxidation does not substantiate antioxidant activity in intact cells in the absence of oxidative stress (neither pro-oxidant activity, representing a great advantage). A targeted delivery to oxidative-stressed tissues is suggested for the effective antioxidant therapy based on SkQ1.
Collapse
Affiliation(s)
- Jan Ježek
- Department No. 75, Institute of Physiology, Academy of Sciences, Vídeňská 1083, Prague 14220, Czech Republic.
| | - Hana Engstová
- Department No. 75, Institute of Physiology, Academy of Sciences, Vídeňská 1083, Prague 14220, Czech Republic
| | - Petr Ježek
- Department No. 75, Institute of Physiology, Academy of Sciences, Vídeňská 1083, Prague 14220, Czech Republic.
| |
Collapse
|
14
|
Vancomycin induces reactive oxygen species-dependent apoptosis via mitochondrial cardiolipin peroxidation in renal tubular epithelial cells. Eur J Pharmacol 2017; 800:48-56. [PMID: 28216050 DOI: 10.1016/j.ejphar.2017.02.025] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2016] [Revised: 02/08/2017] [Accepted: 02/15/2017] [Indexed: 12/11/2022]
Abstract
Vancomycin (VCM) is a first-line antibiotic for serious infections caused by methicillin-resistant Staphylococcus aureus. However, nephrotoxicity is one of the most complaint in VCM therapy. We previously reported that VCM induced apoptosis in a porcine proximal tubular epithelial cell line (LLC-PK1), in which mitochondrial complex I may generate superoxide, leading to cell death. In the present study, VCM caused production of mitochondrial reactive oxygen species and peroxidation of the mitochondrial phospholipid cardiolipin that was reversed by administration of the mitochondrial uncoupler carbonyl cyanide-4-(trifluoromethoxy) phenylhydrazone (FCCP). FCCP also significantly suppressed VCM-induced depolarization of the mitochondrial membrane and apoptosis. Moreover, the lipophilic antioxidant vitamin E and a mitochondria-targeted antioxidant, mitoTEMPO, also significantly suppressed VCM-induced depolarization of mitochondrial membrane and apoptosis, whereas vitamin C, n-acetyl cysteine, or glutathione did not provide significant protection. These findings suggest that peroxidation of the mitochondrial membrane cardiolipin mediated the VCM-induced production of intracellular reactive oxygen species and initiation of apoptosis in LLC-PK1 cells. Furthermore, regulation of mitochondrial function using a mitochondria-targeted antioxidant, such as mitoTEMPO, may constitute a potential strategy for mitigation of VCM-induced proximal tubular epithelial cell injury.
Collapse
|
15
|
Rango M, Piatti M, Di Fonzo A, Ardolino G, Airaghi L, Biondetti P, Bresolin N. Abnormal brain temperature in early-onset Parkinson's disease. Mov Disord 2016; 31:425-6. [DOI: 10.1002/mds.26548] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2015] [Revised: 12/17/2015] [Accepted: 12/20/2015] [Indexed: 11/09/2022] Open
Affiliation(s)
- Mario Rango
- Department of Neuroscience and Mental Health, IRCCS Cà Granda-Ospedale Maggiore Policlinico Foundation; University of Milan; Milan Italy
- Excellence Center for Advanced MR Studies, IRCCS Cà Granda-Ospedale Maggiore Policlinico Foundation; Milan Italy
| | - Marco Piatti
- Department of Neuroscience and Mental Health, IRCCS Cà Granda-Ospedale Maggiore Policlinico Foundation; University of Milan; Milan Italy
- Excellence Center for Advanced MR Studies, IRCCS Cà Granda-Ospedale Maggiore Policlinico Foundation; Milan Italy
| | - Alessio Di Fonzo
- Department of Neuroscience and Mental Health, IRCCS Cà Granda-Ospedale Maggiore Policlinico Foundation; University of Milan; Milan Italy
| | - Gianluca Ardolino
- Department of Neuroscience and Mental Health, IRCCS Cà Granda-Ospedale Maggiore Policlinico Foundation; University of Milan; Milan Italy
| | - Lorena Airaghi
- Department of Internal Medicine, IRCCS Cà Granda-Ospedale Maggiore Policlinico Foundation; University of Milan; Milan Italy
| | - Piero Biondetti
- Excellence Center for Advanced MR Studies, IRCCS Cà Granda-Ospedale Maggiore Policlinico Foundation; Milan Italy
- Radiology Unit, IRCCS Cà Granda-Ospedale Maggiore Policlinico Foundation; Milan Italy
| | - Nereo Bresolin
- Department of Neuroscience and Mental Health, IRCCS Cà Granda-Ospedale Maggiore Policlinico Foundation; University of Milan; Milan Italy
- Excellence Center for Advanced MR Studies, IRCCS Cà Granda-Ospedale Maggiore Policlinico Foundation; Milan Italy
| |
Collapse
|
16
|
Oyanagi E, Uchida M, Miyakawa T, Miyachi M, Yamaguchi H, Nagami K, Utsumi K, Yano H. Palmitoleic acid induces the cardiac mitochondrial membrane permeability transition despite the presence of L-carnitine. Biochem Biophys Res Commun 2015; 463:29-36. [PMID: 25983324 DOI: 10.1016/j.bbrc.2015.05.011] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2015] [Accepted: 05/06/2015] [Indexed: 11/26/2022]
Abstract
Although palmitoleic acid (C16:1) is associated with arrhythmias, and increases in an age-dependent matter, the effects of L-carnitine, which is essential for the transport of long-chain fatty acids into the mitochondria, are unclear. It has been postulated that L-carnitine may attenuate palmitate (C16:0)-induced mitochondrial dysfunction and the apoptosis of cardiomyocytes. The aim of this study was to elucidate the activity of L-carnitine in the prevention of the palmitoleic acid-induced mitochondrial membrane permeability transition and cytochrome c release using isolated cardiac mitochondria from rats. Palmitoleoyl-CoA-induced mitochondrial respiration was not accelerated by L-carnitine treatment, and this respiration was slightly inhibited by oligomycin, which is an inhibitor of ATP synthase. Despite pretreatment with L-carnitine, the mitochondrial membrane potential decreased and mitochondrial swelling was induced by palmitoleoyl-CoA. In the presence of a combination of L-carnitine and tiron, a free radical scavenger, there was attenuated mitochondrial swelling and cytochrome c release following palmitoleoyl-CoA treatment. We concluded that palmitoleic acid, but not palmitate, induces the cardiac mitochondrial membrane permeability transition despite the presence of L-carnitine.
Collapse
Affiliation(s)
- Eri Oyanagi
- Department of Health Promotion and Exercise, National Institute of Health and Nutrition, Tokyo, Japan; Research Institute of Health and Welfare, Kibi International University, Takahashi, Japan
| | - Masataka Uchida
- Department of Health & Sports Science, Kawasaki University of Medical Welfare, Kurashiki, Japan
| | - Takeshi Miyakawa
- Department of Health & Sports Science, Kawasaki University of Medical Welfare, Kurashiki, Japan
| | - Motohiko Miyachi
- Department of Health Promotion and Exercise, National Institute of Health and Nutrition, Tokyo, Japan
| | - Hidetaka Yamaguchi
- Research Institute of Health and Welfare, Kibi International University, Takahashi, Japan
| | - Kuniatsu Nagami
- Research Institute of Health and Welfare, Kibi International University, Takahashi, Japan
| | - Kozo Utsumi
- Department of Cytology & Histology, Okayama University Graduate School, Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan
| | - Hiromi Yano
- Department of Health & Sports Science, Kawasaki University of Medical Welfare, Kurashiki, Japan.
| |
Collapse
|
17
|
Rybalka E, Timpani CA, Cooke MB, Williams AD, Hayes A. Defects in mitochondrial ATP synthesis in dystrophin-deficient mdx skeletal muscles may be caused by complex I insufficiency. PLoS One 2014; 9:e115763. [PMID: 25541951 PMCID: PMC4277356 DOI: 10.1371/journal.pone.0115763] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2014] [Accepted: 12/01/2014] [Indexed: 12/21/2022] Open
Abstract
Duchenne Muscular Dystrophy is a chronic, progressive and ultimately fatal skeletal muscle wasting disease characterised by sarcolemmal fragility and intracellular Ca2+ dysregulation secondary to the absence of dystrophin. Mounting literature also suggests that the dysfunction of key energy systems within the muscle may contribute to pathological muscle wasting by reducing ATP availability to Ca2+ regulation and fibre regeneration. No study to date has biochemically quantified and contrasted mitochondrial ATP production capacity by dystrophic mitochondria isolated from their pathophysiological environment such to determine whether mitochondria are indeed capable of meeting this heightened cellular ATP demand, or examined the effects of an increasing extramitochondrial Ca2+ environment. Using isolated mitochondria from the diaphragm and tibialis anterior of 12 week-old dystrophin-deficient mdx and healthy control mice (C57BL10/ScSn) we have demonstrated severely depressed Complex I-mediated mitochondrial ATP production rate in mdx mitochondria that occurs irrespective of the macronutrient-derivative substrate combination fed into the Kreb's cycle, and, which is partially, but significantly, ameliorated by inhibition of Complex I with rotenone and stimulation of Complex II-mediated ATP-production with succinate. There was no difference in the MAPR response of mdx mitochondria to increasing extramitochondrial Ca2+ load in comparison to controls, and 400 nM extramitochondrial Ca2+ was generally shown to be inhibitory to MAPR in both groups. Our data suggests that DMD pathology is exacerbated by a Complex I deficiency, which may contribute in part to the severe reductions in ATP production previously observed in dystrophic skeletal muscle.
Collapse
Affiliation(s)
- Emma Rybalka
- Centre for Chronic Disease Prevention and Management, College of Health and Biomedicine, Victoria University, Melbourne, Victoria, Australia
- Institute of Sport, Exercise & Active Living (ISEAL), Victoria University, Melbourne, Victoria, Australia
- Australian Institute of Musculoskeletal Science, Western Health, Victoria, Australia
| | - Cara A. Timpani
- Centre for Chronic Disease Prevention and Management, College of Health and Biomedicine, Victoria University, Melbourne, Victoria, Australia
| | - Matthew B. Cooke
- Centre for Chronic Disease Prevention and Management, College of Health and Biomedicine, Victoria University, Melbourne, Victoria, Australia
- Institute of Sport, Exercise & Active Living (ISEAL), Victoria University, Melbourne, Victoria, Australia
- Australian Institute of Musculoskeletal Science, Western Health, Victoria, Australia
| | - Andrew D. Williams
- School of Human Life Sciences, University of Tasmania, Launceston, Australia
| | - Alan Hayes
- Centre for Chronic Disease Prevention and Management, College of Health and Biomedicine, Victoria University, Melbourne, Victoria, Australia
- Institute of Sport, Exercise & Active Living (ISEAL), Victoria University, Melbourne, Victoria, Australia
- Australian Institute of Musculoskeletal Science, Western Health, Victoria, Australia
| |
Collapse
|
18
|
Stelmashook EV, Novikova SV, Amelkina GA, Genrikhs EE, Khaspekov LG, Isaev NK. The mechanism of the neurocytotoxic effect of the Na+/H+ exchange inhibitor 5-(N-ethyl-N-isopropyl)-amiloride (EIPA) in the rat cerebellum cultured granule neurons. NEUROCHEM J+ 2014. [DOI: 10.1134/s181971241402010x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
|
19
|
JEŽEK P, OLEJÁR T, SMOLKOVÁ K, JEŽEK J, DLASKOVÁ A, PLECITÁ-HLAVATÁ L, ZELENKA J, ŠPAČEK T, ENGSTOVÁ H, PAJUELO REGUERA D, JABŮREK M. Antioxidant and Regulatory Role of Mitochondrial Uncoupling Protein UCP2 in Pancreatic β-cells. Physiol Res 2014; 63:S73-91. [DOI: 10.33549/physiolres.932633] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Research on brown adipose tissue and its hallmark protein, mitochondrial uncoupling protein UCP1, has been conducted for half a century and has been traditionally studied in the Institute of Physiology (AS CR, Prague), likewise UCP2 residing in multiple tissues for the last two decades. Our group has significantly contributed to the elucidation of UCP uncoupling mechanism, fully dependent on free fatty acids (FFAs) within the inner mitochondrial membrane. Now we review UCP2 physiological roles emphasizing its roles in pancreatic β-cells, such as antioxidant role, possible tuning of redox homeostasis (consequently UCP2 participation in redox regulations), and fine regulation of glucose-stimulated insulin secretion (GSIS). For example, NADPH has been firmly established as being a modulator of GSIS and since UCP2 may influence redox homeostasis, it likely affects NADPH levels. We also point out the role of phospholipase iPLA2 isoform in providing FFAs for the UCP2 antioxidant function. Such initiation of mild uncoupling hypothetically precedes lipotoxicity in pancreatic β-cells until it reaches the pathological threshold, after which the antioxidant role of UCP2 can be no more cell-protective, for example due to oxidative stress-accumulated mutations in mtDNA. These mechanisms, together with impaired autocrine insulin function belong to important causes of Type 2 diabetes etiology.
Collapse
Affiliation(s)
- P. JEŽEK
- Department of Membrane Transport Biophysics, Institute of Physiology Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
20
|
Malingriaux EA, Rupprecht A, Gille L, Jovanovic O, Jezek P, Jaburek M, Pohl EE. Fatty acids are key in 4-hydroxy-2-nonenal-mediated activation of uncoupling proteins 1 and 2. PLoS One 2013; 8:e77786. [PMID: 24204965 PMCID: PMC3810126 DOI: 10.1371/journal.pone.0077786] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2013] [Accepted: 09/12/2013] [Indexed: 11/19/2022] Open
Abstract
The production of reactive oxygen species (ROS) in mitochondria is very sensitive to the proton motive force and may be decreased by mild uncoupling, mediated e.g. by mitochondrial uncoupling proteins (UCPs). UCPs were conversely hypothesized to be activated by ROS. Conclusions from experiments studying the reactive product of lipid peroxidation 4-hydroxy-2-nonenal (HNE) in isolated mitochondria and UCP knock-out mice are highly controversial. Here we investigated the molecular mechanism of HNE action by evaluating the separate contributions of lipid and protein phases of the membrane and by comparing UCP1 and UCP2, which were reconstituted in planar lipid bilayers. We demonstrated that aldehyde does not directly activate either UCP1 or UCP2. However, HNE strongly potentiated the membrane conductance increase (Gm) mediated by different long-chain fatty acids in UCP-containing and in UCP-free membranes and this suggest the involvement of both lipid-mediated and protein-mediated mechanisms with FA playing the central role. Gm increase was concentration-dependent and exhibited a typical saturation kinetic with the binding constant 0.3 mM. By using Electron Paramagnetic Resonance, membrane fluidity change could be excluded as a cause for the HNE-mediated increase in the presence of FA. The impact of the HNE binding to definite positively charged UCP amino acid residues is discussed as a possible protein-mediated mechanism of the UCP activation.
Collapse
Affiliation(s)
- Elena A. Malingriaux
- Institute of Physiology, Pathophysiology and Biophysics, University of Veterinary Medicine, Vienna, Austria
| | - Anne Rupprecht
- Institute of Physiology, Pathophysiology and Biophysics, University of Veterinary Medicine, Vienna, Austria
| | - Lars Gille
- Institute of Pharmacology and Toxicology, University of Veterinary Medicine, Vienna, Austria
| | - Olga Jovanovic
- Institute of Physiology, Pathophysiology and Biophysics, University of Veterinary Medicine, Vienna, Austria
| | - Petr Jezek
- Institute of Physiology, Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | - Martin Jaburek
- Institute of Physiology, Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | - Elena E. Pohl
- Institute of Physiology, Pathophysiology and Biophysics, University of Veterinary Medicine, Vienna, Austria
- * E-mail:
| |
Collapse
|
21
|
Redox homeostasis in pancreatic β cells. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2012; 2012:932838. [PMID: 23304259 PMCID: PMC3532876 DOI: 10.1155/2012/932838] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/13/2012] [Accepted: 10/30/2012] [Indexed: 12/20/2022]
Abstract
We reviewed mechanisms that determine reactive oxygen species (redox) homeostasis, redox information signaling and metabolic/regulatory function of autocrine insulin signaling in pancreatic β cells, and consequences of oxidative stress and dysregulation of redox/information signaling for their dysfunction. We emphasize the role of mitochondrion in β cell molecular physiology and pathology, including the antioxidant role of mitochondrial uncoupling protein UCP2. Since in pancreatic β cells pyruvate cannot be easily diverted towards lactate dehydrogenase for lactate formation, the respiration and oxidative phosphorylation intensity are governed by the availability of glucose, leading to a certain ATP/ADP ratio, whereas in other cell types, cell demand dictates respiration/metabolism rates. Moreover, we examine the possibility that type 2 diabetes mellitus might be considered as an inevitable result of progressive self-accelerating oxidative stress and concomitantly dysregulated information signaling in peripheral tissues as well as in pancreatic β cells. It is because the redox signaling is inherent to the insulin receptor signaling mechanism and its impairment leads to the oxidative and nitrosative stress. Also emerging concepts, admiting participation of redox signaling even in glucose sensing and insulin release in pancreatic β cells, fit in this view. For example, NADPH has been firmly established to be a modulator of glucose-stimulated insulin release.
Collapse
|
22
|
Zhou M, Xu A, Tam PKH, Lam KSL, Huang B, Liang Y, Lee IK, Wu D, Wang Y. Upregulation of UCP2 by adiponectin: the involvement of mitochondrial superoxide and hnRNP K. PLoS One 2012; 7:e32349. [PMID: 22359684 PMCID: PMC3281141 DOI: 10.1371/journal.pone.0032349] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2011] [Accepted: 01/26/2012] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND The adipocyte-derived hormone adiponectin elicits protective functions against fatty liver diseases and hepatic injuries at least in part by stimulating the expression of a mitochondrial inner membrane transporter, uncoupling protein 2 (UCP2). The present study was designed to investigate the cellular and molecular mechanisms underlying adiponectin-induced UCP2 expression. METHODOLOGY/PRINCIPAL FINDINGS Mice were treated with adiponectin and/or different drug inhibitors. Parenchymal (PCs) and nonparenchymal (NPCs) cells were fractionated from the liver tissues for mitochondria isolation, Western blotting and quantitative PCR analysis. Mitochondrial superoxide production was monitored by MitoSOX staining and flow cytometry analysis. Compared to control mice, the expression of UCP2 was significantly lower in NPCs, but not PCs of adiponectin knockout mice (AKO). Both chronic and acute treatment with adiponectin selectively increased the mRNA and protein abundance of UCP2 in NPCs, especially in the enriched endothelial cell fractions. The transcription inhibitor actinomycin D could not block adiponectin-induced UCP2 expression, whereas the protein synthesis inhibitor cycloheximide inhibited the elevation of UCP2 protein but not its mRNA levels. Mitochondrial content of heterogeneous nuclear ribonucleoprotein K (hnRNP K), a nucleic acid binding protein involved in regulating mRNA transportation and stabilization, was significantly enhanced by adiponectin, which also evoked a transient elevation of mitochondrial superoxide. Rotenone, an inhibitor of mitochondrial respiratory complex I, abolished adiponectin-induced superoxide production, hnRNP K recruitment and UCP2 expression. CONCLUSIONS/SIGNIFICANCE Mitochondrial superoxide production stimulated by adiponectin serves as a trigger to initiate the translocation of hnRNP K, which in turn promotes UCP2 expressions in liver.
Collapse
Affiliation(s)
- Mingyan Zhou
- Department of Pharmacology and Pharmacy, University of Hong Kong, Hong Kong, China
| | - Aimin Xu
- Department of Pharmacology and Pharmacy, University of Hong Kong, Hong Kong, China
- Department of Medicine, University of Hong Kong, Hong Kong, China
| | - Paul K. H. Tam
- Department of Surgery, University of Hong Kong, Hong Kong, China
| | - Karen S. L. Lam
- Department of Medicine, University of Hong Kong, Hong Kong, China
| | - Bosheng Huang
- Department of Pharmacology and Pharmacy, University of Hong Kong, Hong Kong, China
| | - Yan Liang
- Department of Pharmacology and Pharmacy, University of Hong Kong, Hong Kong, China
| | - In-Kyu Lee
- School of Medicine, Kyungpook National University, Daegu, Korea
| | - Donghai Wu
- Key Laboratory of Regenerative Biology, Guangzhou Institute of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou, China
| | - Yu Wang
- Department of Pharmacology and Pharmacy, University of Hong Kong, Hong Kong, China
- * E-mail:
| |
Collapse
|
23
|
Oyanagi E, Yano H, Uchida M, Utsumi K, Sasaki J. Protective action of L-carnitine on cardiac mitochondrial function and structure against fatty acid stress. Biochem Biophys Res Commun 2011; 412:61-7. [PMID: 21791201 DOI: 10.1016/j.bbrc.2011.07.039] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2011] [Accepted: 07/08/2011] [Indexed: 02/04/2023]
Abstract
Cardiovascular risks are frequently accompanied by high serum fatty acid levels. Although recent studies have shown that fatty acids affect mitochondrial function and induce cell apoptosis, L-carnitine is essential for the uptake of fatty acids by mitochondria, and may attenuate the mitochondrial dysfunction and apoptosis of cardiocytes. This study aimed to elucidate the activity of L-carnitine in the prevention on fatty acid-induced mitochondrial membrane permeability transition and cytochrome c release using isolated cardiac mitochondria from rats. Palmitoyl-CoA-induced mitochondrial respiration that was observed with L-carnitine was inhibited with oligomycin. The palmitoyl-CoA-induced mitochondrial membrane depolarization and swelling were greatly inhibited by the presence of L-carnitine. In ultrastructural observations, terminally swollen and ruptured mitochondria with little or no distinguishable cristae structures were induced by treatment with palmitoyl-CoA. However, the severe morphological damage in cardiac mitochondria was dramatically inhibited by pretreatment with L-carnitine. Treatment with L-carnitine also attenuated 4-hydroxy-L-phenylglycine- and rotenone-induced mitochondrial swelling even when the L-carnitine could not protect against the decrease in oxygen consumption associated with these inhibitors. Furthermore, L-carnitine completely inhibited palmitoyl-CoA-induced cytochrome c release. We concluded that L-carnitine is essential for cardiac mitochondria to attenuate the membrane permeability transition, and to maintain the ultrastructure and membrane stabilization, in the presence of high fatty acid β-oxidation. Consequently, the cells may be protected against apoptosis by L-carnitine through inhibition of the fatty acid-induced cytochrome c release.
Collapse
Affiliation(s)
- Eri Oyanagi
- Department of Cytology and Histology, Okayama University Graduate School, Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan
| | | | | | | | | |
Collapse
|
24
|
Wu YN, Munhall AC, Johnson SW. Mitochondrial uncoupling agents antagonize rotenone actions in rat substantia nigra dopamine neurons. Brain Res 2011; 1395:86-93. [DOI: 10.1016/j.brainres.2011.04.032] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2011] [Accepted: 04/18/2011] [Indexed: 12/21/2022]
|
25
|
Batista AP, Marreiros BC, Pereira MM. Decoupling of the catalytic and transport activities of complex I from Rhodothermus marinus by sodium/proton antiporter inhibitor. ACS Chem Biol 2011; 6:477-83. [PMID: 21268658 DOI: 10.1021/cb100380y] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The energy transduction by complex I from Rhodothermusmarinus was addressed by studying the influence of 5-(N-ethyl-N-isopropyl)-amiloride (EIPA) on the activities of this enzyme. EIPA is an inhibitor of both Na(+)/H(+) antiporter and complex I NADH:quinone oxidoreductase activity. We performed studies of NADH:quinone oxidoreductase and H(+) and Na(+) translocation activities of complex I from R. marinus at different concentrations of EIPA, using inside-out membrane vesicles. We observed that the oxidoreductase activity and both H(+) and Na(+) transports are inhibited by EIPA. Most interestingly, the catalytic and the two transport activities showed different inhibition profiles. The transports are inhibited at concentrations of EIPA at which the catalytic activity is not affected. In this way the catalytic and transport activities were decoupled. Moreover, the inhibition of the catalytic activity was not influenced by the presence of Na(+), whereas the transport of H(+) showed different inhibition behaviors in the presence and absence of Na(+). Taken together our observations indicate that complex I from R. marinus performs energy transduction by two different processes: proton pumping and Na(+)/H(+) antiporting. The decoupling of the catalytic and transport activities suggests the involvement of an indirect coupling mechanism, possibly through conformational changes.
Collapse
Affiliation(s)
- Ana P. Batista
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Av. da Republica EAN, 2780-157 Oeiras, Portugal
| | - Bruno C. Marreiros
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Av. da Republica EAN, 2780-157 Oeiras, Portugal
| | - Manuela M. Pereira
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Av. da Republica EAN, 2780-157 Oeiras, Portugal
| |
Collapse
|
26
|
Gabrielová E, Jabůrek M, Gažák R, Vostálová J, Ježek J, Křen V, Modrianský M. Dehydrosilybin attenuates the production of ROS in rat cardiomyocyte mitochondria with an uncoupler-like mechanism. J Bioenerg Biomembr 2010; 42:499-509. [PMID: 21153691 DOI: 10.1007/s10863-010-9319-2] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2010] [Accepted: 11/01/2010] [Indexed: 11/26/2022]
Abstract
Reactive oxygen species (ROS) originating from mitochondria are perceived as a factor contributing to cell aging and means have been sought to attenuate ROS formation with the aim of extending the cell lifespan. Silybin and dehydrosilybin, two polyphenolic compounds, display a plethora of biological effects generally ascribed to their known antioxidant capacity. When investigating the cytoprotective effects of these two compounds in the primary cell cultures of neonatal rat cardiomyocytes, we noted the ability of dehydrosilybin to de-energize the cells by monitoring JC-1 fluorescence. Experiments evaluating oxygen consumption and membrane potential revealed that dehydrosilybin uncouples the respiration of isolated rat heart mitochondria albeit with a much lower potency than synthetic uncouplers. Furthermore, dehydrosilybin revealed a very high potency in suppressing ROS formation in isolated rat heart mitochondria with IC(50) = 0.15 μM. It is far more effective than its effect in a purely chemical system generating superoxide or in cells capable of oxidative burst, where the IC(50) for dehydrosilybin exceeds 50 μM. Dehydrosilybin also attenuated ROS formation caused by rotenone in the primary cultures of neonatal rat cardiomyocytes. We infer that the apparent uncoupler-like activity of dehydrosilybin is the basis of its ROS modulation effect in neonatal rat cardiomyocytes and leads us to propose a hypothesis on natural ischemia preconditioning by dietary polyphenols.
Collapse
Affiliation(s)
- Eva Gabrielová
- Institute of Medical Chemistry and Biochemistry, Faculty of Medicine and Dentistry, Palacký University, Olomouc, Czech Republic
| | | | | | | | | | | | | |
Collapse
|
27
|
Ohnishi T, Nakamaru-Ogiso E, Ohnishi ST. A new hypothesis on the simultaneous direct and indirect proton pump mechanisms in NADH-quinone oxidoreductase (complex I). FEBS Lett 2010; 584:4131-7. [PMID: 20816962 DOI: 10.1016/j.febslet.2010.08.039] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2010] [Revised: 08/21/2010] [Accepted: 08/29/2010] [Indexed: 02/07/2023]
Abstract
Recently, Sazanov's group reported the X-ray structure of whole complex I [Nature, 465, 441 (2010)], which presented a strong clue for a "piston-like" structure as a key element in an "indirect" proton pump. We have studied the NuoL subunit which has a high sequence similarity to Na(+)/H(+) antiporters, as do the NuoM and N subunits. We constructed 27 site-directed NuoL mutants. Our data suggest that the H(+)/e(-) stoichiometry seems to have decreased from (4H(+)/2e(-)) in the wild-type to approximately (3H(+)/2e(-)) in NuoL mutants. We propose a revised hypothesis that each of the "direct" and the "indirect" proton pumps transports 2H(+) per 2e(-).
Collapse
Affiliation(s)
- Tomoko Ohnishi
- Johnson Research Foundation, Department of Biochemistry and Biophysics, University of Pennsylvania School of Medicine, Philadelphia, PA 19104-6059, USA.
| | | | | |
Collapse
|
28
|
Nakamaru-Ogiso E, Kao MC, Chen H, Sinha SC, Yagi T, Ohnishi T. The membrane subunit NuoL(ND5) is involved in the indirect proton pumping mechanism of Escherichia coli complex I. J Biol Chem 2010; 285:39070-8. [PMID: 20826797 DOI: 10.1074/jbc.m110.157826] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Complex I pumps protons across the membrane by using downhill redox energy. Here, to investigate the proton pumping mechanism by complex I, we focused on the largest transmembrane subunit NuoL (Escherichia coli ND5 homolog). NuoL/ND5 is believed to have H(+) translocation site(s), because of a high sequence similarity to multi-subunit Na(+)/H(+) antiporters. We mutated thirteen highly conserved residues between NuoL/ND5 and MrpA of Na(+)/H(+) antiporters in the chromosomal nuoL gene. The dNADH oxidase activities in mutant membranes were mostly at the control level or modestly reduced, except mutants of Glu-144, Lys-229, and Lys-399. In contrast, the peripheral dNADH-K(3)Fe(CN)(6) reductase activities basically remained unchanged in all the NuoL mutants, suggesting that the peripheral arm of complex I was not affected by point mutations in NuoL. The proton pumping efficiency (the ratio of H(+)/e(-)), however, was decreased in most NuoL mutants by 30-50%, while the IC(50) values for asimicin (a potent complex I inhibitor) remained unchanged. This suggests that the H(+)/e(-) stoichiometry has changed from 4H(+)/2e(-) to 3H(+) or 2H(+)/2e(-) without affecting the direct coupling site. Furthermore, 50 μm of 5-(N-ethyl-N-isopropyl)-amiloride (EIPA), a specific inhibitor for Na(+)/H(+) antiporters, caused a 38 ± 5% decrease in the initial H(+) pump activity in the wild type, while no change was observed in D178N, D303A, and D400A mutants where the H(+) pumping efficiency had already been significantly decreased. The electron transfer activities were basically unaffected by EIPA in both control and mutants. Taken together, our data strongly indicate that the NuoL subunit is involved in the indirect coupling mechanism.
Collapse
Affiliation(s)
- Eiko Nakamaru-Ogiso
- Johnson Research Foundation, Department of Biochemistry and Biophysics, School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
| | | | | | | | | | | |
Collapse
|
29
|
Koopman WJH, Nijtmans LGJ, Dieteren CEJ, Roestenberg P, Valsecchi F, Smeitink JAM, Willems PHGM. Mammalian mitochondrial complex I: biogenesis, regulation, and reactive oxygen species generation. Antioxid Redox Signal 2010; 12:1431-70. [PMID: 19803744 DOI: 10.1089/ars.2009.2743] [Citation(s) in RCA: 301] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Virtually every mammalian cell contains mitochondria. These double-membrane organelles continuously change shape and position and contain the complete metabolic machinery for the oxidative conversion of pyruvate, fatty acids, and amino acids into ATP. Mitochondria are crucially involved in cellular Ca2+ and redox homeostasis and apoptosis induction. Maintenance of mitochondrial function and integrity requires an inside-negative potential difference across the mitochondrial inner membrane. This potential is sustained by the electron-transport chain (ETC). NADH:ubiquinone oxidoreductase or complex I (CI), the first and largest protein complex of the ETC, couples the oxidation of NADH to the reduction of ubiquinone. During this process, electrons can escape from CI and react with ambient oxygen to produce superoxide and derived reactive oxygen species (ROS). Depending on the balance between their production and removal by antioxidant systems, ROS may function as signaling molecules or induce damage to a variety of biomolecules or both. The latter ultimately leads to a loss of mitochondrial and cellular function and integrity. In this review, we discuss (a) the role of CI in mitochondrial functioning; (b) the composition, structure, and biogenesis of CI; (c) regulation of CI function; (d) the role of CI in ROS generation; and (e) adaptive responses to CI deficiency.
Collapse
Affiliation(s)
- Werner J H Koopman
- Department of Biochemistry, Nijmegen Centre for Molecular Life Sciences, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands.
| | | | | | | | | | | | | |
Collapse
|
30
|
Isoflurane protects cardiomyocytes and mitochondria by immediate and cytosol-independent action at reperfusion. Br J Pharmacol 2010; 160:220-32. [PMID: 20423337 DOI: 10.1111/j.1476-5381.2010.00698.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
BACKGROUND AND PURPOSE The volatile anaesthetic isoflurane protects the heart from ischaemia and reperfusion (I/R) injury when applied at the onset of reperfusion [anaesthetic postconditioning (APoC)]. However, the mechanism of APoC-mediated protection is unknown. In this study, we examined the effect of APoC on mitochondrial bioenergetics, mitochondrial matrix pH (pH(m)) and cytosolic pH (pH(i)), and intracellular Ca(2+). EXPERIMENTAL APPROACH Cardiac mitochondria from Wistar rats were isolated after in vivo I/R with or without APoC (1.4%-vol isoflurane, 1 minimum alveolar concentration), and mitochondrial permeability transition pore (mPTP) opening, mitochondrial membrane potential (DeltaPsi(m)), and oxygen consumption were assessed. In isolated cardiomyocytes and isolated mitochondria I/R injury was produced in vitro, with or without APoC (0.5 mM isoflurane). Intracellular Ca(2+), pH(m), pH(i) and DeltaPsi(m) were monitored with SNARF-1, TMRE and fluo-4, respectively. Myocyte survival was assessed when APoC was induced at pH 7.4 and 7.8. In isolated mitochondria oxygen consumption and ATP synthesis were measured. KEY RESULTS In vivo APoC protected against mPTP opening, slowed mitochondrial respiration and depolarized mitochondria. APoC decreased the number of hypercontracted cardiomyocytes at pH 7.4, but not at pH 7.8. APoC attenuated intracellular Ca(2+) accumulation, maintained lower pH(m), and preserved DeltaPsi(m) during reoxygenation. Isoflurane did not affect the regulation of cytosolic pH. In mitochondria, APoC preserved ATP production rate and respiration. CONCLUSIONS AND IMPLICATIONS At reperfusion, APoC inhibited mitochondrial respiration, depolarized mitochondria and acidified pH(m). These events may lead to inhibition of mPTP opening and, consequently, to preserved DeltaPsi(m) and ATP synthesis. This reduces intracellular Ca(2+) overload and cell death.
Collapse
|
31
|
Chan KM, Rajab NF, Siegel D, Din LB, Ross D, Inayat-Hussain SH. Goniothalamin induces coronary artery smooth muscle cells apoptosis: the p53-dependent caspase-2 activation pathway. Toxicol Sci 2010; 116:533-48. [PMID: 20498002 DOI: 10.1093/toxsci/kfq151] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Goniothalamin (GN), a styryl-lactone isolated from Goniothalamus andersonii, has been demonstrated to possess antirestenostic properties by inducing apoptosis on coronary artery smooth muscle cells (CASMCs). In this study, the molecular mechanisms of GN-induced CASMCs apoptosis were further elucidated. Apoptosis assessment based on the externalization of phosphatidylserine demonstrated that GN induces CASMCs apoptosis in a concentration-dependent manner. The GN-induced DNA damage occurred with concomitant elevation of p53 as early as 2 h, demonstrating an upstream signal for apoptosis. However, the p53 elevation in GN-treated CASMCs was independent of NAD(P)H: quinone oxidoreductase 1 and Mdm-2 expression. An increase in hydrogen peroxide and reduction in free thiols confirmed the role for oxidative stress in GN treatment. Pretreatment with the pan-caspase inhibitor benzyloxycarbonyl-Val-Ala-Asp-fluoromethyl ketone (z-VAD-FMK) that significantly abrogated GN-induced CASMCs apoptosis suggested the involvement of caspase(s). The role of apical caspase-2, -8, and -9 was then investigated, and sequential activation of caspase-2 and -9 but not caspase-8 leading to downstream caspase-3 cleavage was observed in GN-treated CASMCs. Reduction of ATP level and decrease in oxygen consumption further confirmed the role of mitochondria in GN-induced apoptosis in CASMCs. The mitochondrial release of cytochrome c was seen without mitochondrial membrane potential loss and was independent of cardiolipin. These data provide insight into the mechanisms of GN-induced apoptosis, which may have important implications in the development of drug-eluting stents.
Collapse
Affiliation(s)
- Kok Meng Chan
- Department of Biomedical Science, Faculty of Allied Health Sciences, Universiti Kebangsaan Malaysia, Jalan Raja Muda Abdul Aziz, Kuala Lumpur 50300, Malaysia
| | | | | | | | | | | |
Collapse
|
32
|
L-carnitine is essential to beta-oxidation of quarried fatty acid from mitochondrial membrane by PLA(2). Mol Cell Biochem 2010; 342:95-100. [PMID: 20443048 DOI: 10.1007/s11010-010-0472-z] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2009] [Accepted: 04/17/2010] [Indexed: 12/19/2022]
Abstract
Mitochondrial beta-oxidation is an important system involved in the energy production of various cells. In this system, the function of L-carnitine is essential for the uptake of fatty acids to mitochondria. However, it is unclear whether or not endogenous respiration, ADP-induced O(2) consumption without substrates, is caused by L-carnitine treatment. In this study, we investigated whether L-carnitine is essential to the beta-oxidation of quarried fatty acids from the mitochondrial membrane by phospholipase A(2) (PLA(2)) using isolated mitochondria from the liver of rats. Intact mitochondria were incubated in a medium containing Pi, CoA and L-carnitine. The effect of L-carnitine treatment on ADP-induced mitochondrial respiration was observed without exogenous respiratory substrate. Increase in mitochondrial respiration was induced by treatment with L-carnitine in a concentration-dependent manner. Treatment with rotenone, a complex I blocker, completely inhibited ADP-induced oxygen consumption even in the presence of L-carnitine. Moreover, the L-carnitine dependent ADP-induced mitochondrial oxygen consumption did not increase when PLA(2) inhibitors were treated before ADP treatment. The L-carnitine-dependent ADP-induced oxygen consumption did contribute to ATP productions but not heat generation via an uncoupling system. These results suggest that L-carnitine might be essential to the beta-oxidation of quarried fatty acids from the mitochondrial membrane by PLA(2).
Collapse
|
33
|
Plecitá-Hlavatá L, Ježek J, Ježek P. Pro-oxidant mitochondrial matrix-targeted ubiquinone MitoQ10 acts as anti-oxidant at retarded electron transport or proton pumping within Complex I. Int J Biochem Cell Biol 2009; 41:1697-707. [DOI: 10.1016/j.biocel.2009.02.015] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2008] [Revised: 02/17/2009] [Accepted: 02/18/2009] [Indexed: 12/18/2022]
|
34
|
Jezek P, Plecitá-Hlavatá L. Mitochondrial reticulum network dynamics in relation to oxidative stress, redox regulation, and hypoxia. Int J Biochem Cell Biol 2009; 41:1790-804. [PMID: 19703650 DOI: 10.1016/j.biocel.2009.02.014] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2008] [Revised: 02/17/2009] [Accepted: 02/19/2009] [Indexed: 02/03/2023]
Abstract
A single mitochondrial network in the cell undergoes constant fission and fusion primarily depending on the local GTP gradients and the mitochondrial energetics. Here we overview the main properties and regulation of pro-fusion and pro-fission mitodynamins, i.e. dynamins-related GTPases responsible for mitochondrial shape-forming, such as pro-fusion mitofusins MFN1, MFN2, and the inner membrane-residing long OPA1 isoforms, and pro-fission mitodynamins FIS1, MFF, and DRP1 multimers required for scission. Notably, the OPA1 cleavage into non-functional short isoforms at a diminished ATP level (collapsed membrane potential) and the DRP1 recruitment upon phosphorylation by various kinases are overviewed. Possible responses of mitodynamins to the oxidative stress, hypoxia, and concomitant mtDNA mutations are also discussed. We hypothesize that the increased GTP formation within the Krebs cycle followed by the GTP export via the ADP/ATP carrier shift the balance between fission and fusion towards fusion by activating the GTPase domain of OPA1 located in the peripheral intermembrane space (PIMS). Since the protein milieu of PIMS is kept at the prevailing oxidized redox potential by the TOM, MIA40 and ALR/Erv1 import-redox trapping system, redox regulations shift the protein environment of PIMS to a more reduced state due to the higher substrate load and increased respiration. A higher cytochrome c turnover rate may prevent electron transfer from ALR/Erv1 to cytochrome c. Nevertheless, the putative links between the mitodynamin responses, mitochondrial morphology and the changes in the mitochondrial bioenergetics, superoxide production, and hypoxia are yet to be elucidated, including the precise basis for signaling by the mitochondrion-derived vesicles.
Collapse
Affiliation(s)
- Petr Jezek
- Department of Membrane Transport Biophysics, No. 75, Institute of Physiology, v.v.i., Academy of Sciences of the Czech Republic, Vídenská 1083, CZ 14220 Prague, Czech Republic.
| | | |
Collapse
|
35
|
Alán L, Smolková K, Kronusová E, Santorová J, Jezek P. Absolute levels of transcripts for mitochondrial uncoupling proteins UCP2, UCP3, UCP4, and UCP5 show different patterns in rat and mice tissues. J Bioenerg Biomembr 2009; 41:71-8. [PMID: 19242784 DOI: 10.1007/s10863-009-9201-2] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2008] [Accepted: 01/29/2009] [Indexed: 12/11/2022]
Abstract
Existing controversies led us to analyze absolute mRNA levels of mitochondrial uncoupling proteins (UCP1-UCP5). Individual UCP isoform mRNA levels varied by up to four orders of magnitude in rat and mouse tissues. UCP2 mRNA content was relatively high (0.4 to 0.8 pg per 10 ng of total mRNA) in rat spleen, rat and mouse lung, and rat heart. Levels of the same order of magnitude were found for UCP3 mRNA in rat and mouse skeletal muscle, for UCP4 and UCP5 mRNA in mouse brain, and for UCP2 and UCP5 mRNA in mouse white adipose tissue. Significant differences in pattern were found for rat vs. mouse tissues, such as the dominance of UCP3/UCP5 vs. UCP2 transcript in mouse heart and vice versa in rat heart; or UCP2 (UCP5) dominance in rat brain contrary to 10-fold higher UCP4 and UCP5 dominance in mouse brain. We predict high antioxidant/antiapoptotic UCP function in tissues with higher UCP mRNA content.
Collapse
Affiliation(s)
- Lukás Alán
- Department of Membrane Transport Biophysics, No.75, Institute of Physiology, Academy of Sciences of the Czech Republic, Prague, Czech Republic.
| | | | | | | | | |
Collapse
|