1
|
Holt AG, Davies AM. The long term effects of uncoupling interventions as a therapy for dementia in humans. J Theor Biol 2024; 587:111825. [PMID: 38621584 DOI: 10.1016/j.jtbi.2024.111825] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2024] [Revised: 03/25/2024] [Accepted: 04/09/2024] [Indexed: 04/17/2024]
Abstract
In this paper we use simulation methods to study a hypothetical uncoupling agent as a therapy for dementia. We simulate the proliferation of mitochondrial deletion mutants amongst a population of wild-type in human neurons. Mitochondria play a key role in ATP generation. Clonal expansion can lead to the wild-type being overwhelmed by deletions such that a diminished population can no longer fulfil a cell's energy requirement, eventually leading to its demise. The intention of uncoupling is to reduce the formation of deletion mutants by reducing mutation rate. However, a consequence of uncoupling is that the energy production efficacy is also reduced which in turn increases wild-type copy number in order to compensate for the energy deficit. The results of this paper showed that uncoupling reduced the severity of dementia, however, there was some increase in cognitive dysfunction pre-onset of dementia. The effectiveness of uncoupling was dependent upon the timing of intervention relative to the onset of dementia and would necessitate predicting its onset many years in advance.
Collapse
|
2
|
Yamoune S, Müller JP, Langmia IM, Scholl C, Stingl JC. Uncoupling of Cytochrome P450 2B6 and stimulation of reactive oxygen species production in pharmacogenomic alleles affected by interethnic variability. Biochim Biophys Acta Gen Subj 2024; 1868:130595. [PMID: 38467309 DOI: 10.1016/j.bbagen.2024.130595] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2023] [Revised: 02/29/2024] [Accepted: 03/04/2024] [Indexed: 03/13/2024]
Abstract
Cytochrome P450 mediated substrate metabolism is generally characterized by the formation of reactive intermediates. In vitro and in vivo reaction uncoupling, results in the accumulation and dissociation of reactive intermediates, leading to increased ROS formation. The susceptibility towards uncoupling and altered metabolic activity is partly modulated by pharmacogenomic alleles resulting in amino acid substitutions. A large variability in the prevalence of these alleles has been demonstrated in CYP2B6, with some being predominantly unique to African populations. The aim of this study is to characterize the uncoupling potential of recombinant CYP2B6*1, CYP2B6*6 and CYP2B6*34 metabolism of specific substrates. Therefore, functional effects of these alterations on enzyme activity were determined by quantification of bupropion, efavirenz and ketamine biotransformation using HPLC-MS/MS. Determination of H2O2 levels was performed by the AmplexRed/horseradish peroxidase assay. Our studies of the amino acid substitutions Q172H, K262R and R487S revealed an exclusive use of the peroxide shunt for the metabolism of bupropion and ketamine by CYP2B6*K262R. Ketamine was also identified as a trigger for the peroxide shunt in CYP2B6*1 and all variants. Concurrently, ketamine acted as an uncoupler for all enzymes. We further showed that the expressed CYP2B6*34 allele results in the highest H2O2 formation. We therefore conclude that the reaction uncoupling and peroxide shunt are directly linked and can be substrate specifically induced with K262R carriers being most likely to use the peroxide shunt and R487S carrier being most prone to reaction uncoupling. This elucidates the functional diversity of pharmacogenomics in drug metabolism and safety.
Collapse
Affiliation(s)
- Sabrina Yamoune
- Institute of Clinical Pharmacology, University Hospital of RWTH Aachen, Germany; Research Division, Federal Institute for Drugs and Medical Devices (BfArM), Bonn, Germany.
| | - Julian Peter Müller
- Institute of Clinical Pharmacology, University Hospital of RWTH Aachen, Germany
| | | | - Catharina Scholl
- Research Division, Federal Institute for Drugs and Medical Devices (BfArM), Bonn, Germany
| | | |
Collapse
|
3
|
Caggiano EG, Taniguchi CM. UCP2 and pancreatic cancer: conscious uncoupling for therapeutic effect. Cancer Metastasis Rev 2024:10.1007/s10555-023-10157-4. [PMID: 38194152 DOI: 10.1007/s10555-023-10157-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/02/2023] [Accepted: 11/13/2023] [Indexed: 01/10/2024]
Abstract
Pancreatic cancer has an exaggerated dependence on mitochondrial metabolism, but methods to specifically target the mitochondria without off target effects in normal tissues that rely on these organelles is a significant challenge. The mitochondrial uncoupling protein 2 (UCP2) has potential as a cancer-specific drug target, and thus, we will review the known biology of UCP2 and discuss its potential role in the pathobiology and future therapy of pancreatic cancer.
Collapse
Affiliation(s)
- Emily G Caggiano
- Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.
- The University of Texas MD Anderson Cancer Center UTHealth Houston Graduate School of Biomedical Sciences, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.
| | - Cullen M Taniguchi
- Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
- Department of Experimental Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| |
Collapse
|
4
|
Herrnhold M, Hamp I, Plettenburg O, Jastroch M, Keuper M. Adverse bioenergetic effects of N-acyl amino acids in human adipocytes overshadow beneficial mitochondrial uncoupling. Redox Biol 2023; 66:102874. [PMID: 37683300 PMCID: PMC10493596 DOI: 10.1016/j.redox.2023.102874] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2023] [Revised: 08/31/2023] [Accepted: 09/01/2023] [Indexed: 09/10/2023] Open
Abstract
OBJECTIVE Enhancing energy turnover via uncoupled mitochondrial respiration in adipose tissue has great potential to improve human obesity and other metabolic complications. However, the amount of human brown adipose tissue and its uncoupling protein 1 (UCP1) is low in obese patients. Recently, a class of endogenous molecules, N-acyl amino acids (NAAs), was identified as mitochondrial uncouplers in murine adipocytes, presumably acting via the adenine nucleotide translocator (ANT). Given the translational potential, we investigated the bioenergetic effects of NAAs in human adipocytes, characterizing beneficial and adverse effects, dose ranges, amino acid derivatives and underlying mechanisms. METHOD NAAs with neutral (phenylalanine, leucine, isoleucine) and polar (lysine) residues were synthetized and assessed in intact and permeabilized human adipocytes using plate-based respirometry. The Seahorse technology was applied to measure bioenergetic parameters, dose-dependency, interference with UCP1 and adenine nucleotide translocase (ANT) activity, as well as differences to the established chemical uncouplers niclosamide ethanolamine (NEN) and 2,4-dinitrophenol (DNP). RESULT NAAs with neutral amino acid residues potently induce uncoupled respiration in human adipocytes in a dose-dependent manner, even in the presence of the UCP1-inhibitor guanosine diphosphate (GDP) and the ANT-inhibitor carboxyatractylate (CAT). However, neutral NAAs significantly reduce maximal oxidation rates, mitochondrial ATP-production, coupling efficiency and reduce adipocyte viability at concentrations above 25 μM. The in vitro therapeutic index (using induced proton leak and viability as determinants) of NAAs is lower than that of NEN and DNP. CONCLUSION NAAs are potent mitochondrial uncouplers in human adipocytes, independent of UCP1 and ANT. However, previously unnoticed adverse effects harm adipocyte functionality, reduce the therapeutic index of NAAs in vitro and therefore question their suitability as anti-obesity agents without further chemical modifications.
Collapse
Affiliation(s)
- Marie Herrnhold
- Department of Molecular Biosciences, The Wenner-Gren Institute, The Arrhenius Laboratories F3, Stockholm University, SE-106 91, Stockholm, Sweden
| | - Isabel Hamp
- Institute of Medicinal Chemistry, Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Neuherberg, Germany; Institute of Organic Chemistry, Leibniz Universität Hannover, Hannover, Germany
| | - Oliver Plettenburg
- Institute of Medicinal Chemistry, Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Neuherberg, Germany; Institute of Organic Chemistry, Leibniz Universität Hannover, Hannover, Germany
| | - Martin Jastroch
- Department of Molecular Biosciences, The Wenner-Gren Institute, The Arrhenius Laboratories F3, Stockholm University, SE-106 91, Stockholm, Sweden
| | - Michaela Keuper
- Department of Molecular Biosciences, The Wenner-Gren Institute, The Arrhenius Laboratories F3, Stockholm University, SE-106 91, Stockholm, Sweden.
| |
Collapse
|
5
|
Dos Santos KBP, Raimundo AFG, Klosowski EM, de Souza BTL, Mito MS, Constantin RP, Mantovanelli GC, Mewes JM, Bizerra PFV, da Costa Menezes PVM, Utsunomiya KS, Gilglioni EH, Marchiosi R, Dos Santos WD, Ferrarese-Filho O, Caetano W, de Souza Pereira PC, Gonçalves RS, Constantin J, Ishii-Iwamoto EL, Constantin RP. Toluidine blue O directly and photodynamically impairs the bioenergetics of liver mitochondria: a potential mechanism of hepatotoxicity. Photochem Photobiol Sci 2023; 22:279-302. [PMID: 36152272 DOI: 10.1007/s43630-022-00312-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Accepted: 09/19/2022] [Indexed: 10/14/2022]
Abstract
Toluidine blue O (TBO) is a phenothiazine dye that, due to its photochemical characteristics and high affinity for biomembranes, has been revealed as a new photosensitizer (PS) option for antimicrobial photodynamic therapy (PDT). This points to a possible association with membranous organelles like mitochondrion. Therefore, here we investigated its effects on mitochondrial bioenergetic functions both in the dark and under photostimulation. Two experimental systems were utilized: (a) isolated rat liver mitochondria and (b) isolated perfused rat liver. Our data revealed that, independently of photostimulation, TBO presented affinity for mitochondria. Under photostimulation, TBO increased the protein carbonylation and lipid peroxidation levels (up to 109.40 and 119.87%, respectively) and decreased the reduced glutathione levels (59.72%) in mitochondria. TBO also uncoupled oxidative phosphorylation and photoinactivated the respiratory chain complexes I, II, and IV, as well as the FoF1-ATP synthase complex. Without photostimulation, TBO caused uncoupling of oxidative phosphorylation and loss of inner mitochondrial membrane integrity and inhibited very strongly succinate oxidase activity. TBO's uncoupling effect was clearly seen in intact livers where it stimulated oxygen consumption at concentrations of 20 and 40 μM. Additionally, TBO (40 μM) reduced cellular ATP levels (52.46%) and ATP/ADP (45.98%) and ATP/AMP (74.17%) ratios. Consequently, TBO inhibited gluconeogenesis and ureagenesis whereas it stimulated glycogenolysis and glycolysis. In conclusion, we have revealed for the first time that the efficiency of TBO as a PS may be linked to its ability to photodynamically inhibit oxidative phosphorylation. In contrast, TBO is harmful to mitochondrial energy metabolism even without photostimulation, which may lead to adverse effects when used in PDT.
Collapse
|
6
|
Veliova M, Tol MJ, Tontonoz P, Shirihai OS, Liesa M. Measuring Mitochondrial Uncoupling in Mouse Primary Brown Adipocytes Differentiated Ex Vivo. Methods Mol Biol 2023; 2662:53-65. [PMID: 37076670 DOI: 10.1007/978-1-0716-3167-6_5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/21/2023]
Abstract
Measuring the mitochondrial respiratory capacity of brown adipocytes ex vivo is an essential approach to understand the cell-autonomous regulators of mitochondrial uncoupling in brown adipose tissue. Here, we describe two protocols to isolate brown preadipocytes from mice, their ex vivo differentiation to mature brown adipocytes and the quantification of their mitochondrial uncoupling capacity by respirometry.
Collapse
Affiliation(s)
- Michaela Veliova
- Division of Endocrinology, Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
- Department of Molecular and Medical Pharmacology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | - Marcus J Tol
- Department of Pathology and Laboratory Medicine, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
- Department of Biological Chemistry, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
- Molecular Biology Institute, University of California, Los Angeles, CA, USA
| | - Peter Tontonoz
- Department of Pathology and Laboratory Medicine, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
- Department of Biological Chemistry, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
- Molecular Biology Institute, University of California, Los Angeles, CA, USA
| | - Orian S Shirihai
- Division of Endocrinology, Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
- Department of Molecular and Medical Pharmacology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | - Marc Liesa
- Division of Endocrinology, Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA.
- Department of Molecular and Medical Pharmacology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA.
- Molecular Biology Institute, University of California, Los Angeles, CA, USA.
- Institut de Biologia Molecular de Barcelona, IBMB, CSIC, Barcelona, Catalonia, Spain.
| |
Collapse
|
7
|
Hass DT, Bisbach CM, Sadilek M, Sweet IR, Hurley JB. Aerobic Glycolysis in Photoreceptors Supports Energy Demand in the Absence of Mitochondrial Coupling. Adv Exp Med Biol 2023; 1415:435-441. [PMID: 37440069 DOI: 10.1007/978-3-031-27681-1_64] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/14/2023]
Abstract
Metabolism is adapted to meet energetic needs. Based on the amount of ATP required to maintain plasma membrane potential, photoreceptor energy demands must be high. The available evidence suggests that photoreceptors primarily generate metabolic energy through aerobic glycolysis, though this evidence is based primarily on protein expression and not measurement of metabolic flux. Aerobic glycolysis can be validated by measuring flux of glucose to lactate. Aerobic glycolysis is also inefficient and thus an unexpected adaptation for photoreceptors to make. We measured metabolic rates to determine the energy-generating pathways that support photoreceptor metabolism. We found that photoreceptors indeed perform aerobic glycolysis and this is associated with mitochondrial uncoupling.
Collapse
Affiliation(s)
- Daniel T Hass
- Department of Biochemistry, University of Washington, Seattle, WA, USA.
| | - Celia M Bisbach
- Department of Biochemistry, University of Washington, Seattle, WA, USA
| | - Martin Sadilek
- Department of Chemistry, University of Washington, Seattle, WA, USA
| | - Ian R Sweet
- UW Medicine - Diabetes Institute, University of Washington, Seattle, WA, USA
| | - James B Hurley
- Department of Biochemistry, University of Washington, Seattle, WA, USA
| |
Collapse
|
8
|
Richardson RB, Mailloux RJ. WITHDRAWN: Mitochondria need their sleep: Sleep-wake cycling and the role of redox, bioenergetics, and temperature regulation, involving cysteine-mediated redox signaling, uncoupling proteins, and substrate cycles. Free Radic Biol Med 2022:S0891-5849(22)01013-9. [PMID: 36462628 DOI: 10.1016/j.freeradbiomed.2022.11.036] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/29/2022] [Accepted: 11/25/2022] [Indexed: 12/03/2022]
Abstract
This article has been withdrawn at the request of the author(s) and/or editor. The Publisher apologizes for any inconvenience this may cause. The full Elsevier Policy on Article Withdrawal can be found at https://www.elsevier.com/about/our-business/policies/article-withdrawal
Collapse
Affiliation(s)
- Richard B Richardson
- Radiobiology and Health, Canadian Nuclear Laboratories (CNL), Chalk River Laboratories, Chalk River, Ontario, K0J 1J0, Canada; McGill Medical Physics Unit, McGill University, Cedars Cancer Centre - Glen Site, Montreal, Quebec QC, H4A 3J1, Canada.
| | - Ryan J Mailloux
- School of Human Nutrition, Faculty of Agricultural and Environmental Sciences, McGill University, Sainte-Anne-de-Bellevue, Quebec, H9X 3V9, Canada
| |
Collapse
|
9
|
Beignon F, Gueguen N, Tricoire-Leignel H, Mattei C, Lenaers G. The multiple facets of mitochondrial regulations controlling cellular thermogenesis. Cell Mol Life Sci 2022; 79:525. [PMID: 36125552 DOI: 10.1007/s00018-022-04523-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Revised: 07/21/2022] [Accepted: 08/09/2022] [Indexed: 12/01/2022]
Abstract
Understanding temperature production and regulation in endotherm organisms becomes a crucial challenge facing the increased frequency and intensity of heat strokes related to global warming. Mitochondria, located at the crossroad of metabolism, respiration, Ca2+ homeostasis, and apoptosis, were recently proposed to further act as cellular radiators, with an estimated inner temperature reaching 50 °C in common cell lines. This inner thermogenesis might be further exacerbated in organs devoted to produce consistent efforts as muscles, or heat as brown adipose tissue, in response to acute solicitations. Consequently, pathways promoting respiratory chain uncoupling and mitochondrial activity, such as Ca2+ fluxes, uncoupling proteins, futile cycling, and substrate supplies, provide the main processes controlling heat production and cell temperature. The mitochondrial thermogenesis might be further amplified by cytoplasmic mechanisms promoting the over-consumption of ATP pools. Considering these new thermic paradigms, we discuss here all conventional wisdoms linking mitochondrial functions to cellular thermogenesis in different physiological conditions.
Collapse
Affiliation(s)
- Florian Beignon
- Univ Angers, MitoLab, Unité MITOVASC, UMR CNRS 6015, INSERM U1083, SFR ICAT, Angers, France.
| | - Naig Gueguen
- Univ Angers, MitoLab, Unité MITOVASC, UMR CNRS 6015, INSERM U1083, SFR ICAT, Angers, France.,Service de Biochimie et Biologie Moléculaire, CHU d'Angers, Angers, France
| | | | - César Mattei
- Univ Angers, CarMe, Unité MITOVASC, UMR CNRS 6015, INSERM U1083, SFR ICAT, Angers, France
| | - Guy Lenaers
- Univ Angers, MitoLab, Unité MITOVASC, UMR CNRS 6015, INSERM U1083, SFR ICAT, Angers, France. .,Service de Neurologie, CHU d'Angers, Angers, France.
| |
Collapse
|
10
|
Pileggi CA, Blondin DP, Hooks BG, Parmar G, Alecu I, Patten DA, Cuillerier A, O'Dwyer C, Thrush AB, Fullerton MD, Bennett SA, Doucet É, Haman F, Cuperlovic-Culf M, McPherson R, Dent RRM, Harper ME. Exercise training enhances muscle mitochondrial metabolism in diet-resistant obesity. EBioMedicine 2022; 83:104192. [PMID: 35965199 PMCID: PMC9482931 DOI: 10.1016/j.ebiom.2022.104192] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Revised: 07/05/2022] [Accepted: 07/15/2022] [Indexed: 12/14/2022] Open
Abstract
Background Current paradigms for predicting weight loss in response to energy restriction have general validity but a subset of individuals fail to respond adequately despite documented diet adherence. Patients in the bottom 20% for rate of weight loss following a hypocaloric diet (diet-resistant) have been found to have less type I muscle fibres and lower skeletal muscle mitochondrial function, leading to the hypothesis that physical exercise may be an effective treatment when diet alone is inadequate. In this study, we aimed to assess the efficacy of exercise training on mitochondrial function in women with obesity with a documented history of minimal diet-induced weight loss. Methods From over 5000 patient records, 228 files were reviewed to identify baseline characteristics of weight loss response from women with obesity who were previously classified in the top or bottom 20% quintiles based on rate of weight loss in the first 6 weeks during which a 900 kcal/day meal replacement was consumed. A subset of 20 women with obesity were identified based on diet-resistance (n=10) and diet sensitivity (n=10) to undergo a 6-week supervised, progressive, combined aerobic and resistance exercise intervention. Findings Diet-sensitive women had lower baseline adiposity, higher fasting insulin and triglycerides, and a greater number of ATP-III criteria for metabolic syndrome. Conversely in diet-resistant women, the exercise intervention improved body composition, skeletal muscle mitochondrial content and metabolism, with minimal effects in diet-sensitive women. In-depth analyses of muscle metabolomes revealed distinct group- and intervention- differences, including lower serine-associated sphingolipid synthesis in diet-resistant women following exercise training. Interpretation Exercise preferentially enhances skeletal muscle metabolism and improves body composition in women with a history of minimal diet-induced weight loss. These clinical and metabolic mechanism insights move the field towards better personalised approaches for the treatment of distinct obesity phenotypes. Funding Canadian Institutes of Health Research (CIHR-INMD and FDN-143278; CAN-163902; CIHR PJT-148634).
Collapse
Affiliation(s)
- Chantal A Pileggi
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, Ontario, Canada; Ottawa Institute of Systems Biology, Ottawa, Ontario, Canada; National Research Council of Canada, Digital Technologies Research Centre, Ottawa, Canada
| | - Denis P Blondin
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, Ontario, Canada
| | - Breana G Hooks
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, Ontario, Canada; Ottawa Institute of Systems Biology, Ottawa, Ontario, Canada; Centre for Infection, Immunity and Inflammation, Ottawa, Ontario, Canada
| | - Gaganvir Parmar
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, Ontario, Canada; Ottawa Institute of Systems Biology, Ottawa, Ontario, Canada
| | - Irina Alecu
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, Ontario, Canada; Ottawa Institute of Systems Biology, Ottawa, Ontario, Canada
| | - David A Patten
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, Ontario, Canada; Ottawa Institute of Systems Biology, Ottawa, Ontario, Canada
| | - Alexanne Cuillerier
- Department of Cellular and Molecular Medicine, Faculty of Medicine, University of Ottawa, Ottawa, Ontario, Canada
| | - Conor O'Dwyer
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, Ontario, Canada
| | - A Brianne Thrush
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, Ontario, Canada
| | - Morgan D Fullerton
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, Ontario, Canada; Centre for Infection, Immunity and Inflammation, Ottawa, Ontario, Canada; Centre for Catalysis Research and Innovation, Ottawa, Ontario, Canada
| | - Steffany Al Bennett
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, Ontario, Canada; Ottawa Institute of Systems Biology, Ottawa, Ontario, Canada; Centre for Catalysis Research and Innovation, Ottawa, Ontario, Canada
| | - Éric Doucet
- School of Human Kinetics, Faculty of Health Sciences, University of Ottawa, Ottawa, Ontario, Canada
| | - François Haman
- School of Human Kinetics, Faculty of Health Sciences, University of Ottawa, Ottawa, Ontario, Canada
| | - Miroslava Cuperlovic-Culf
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, Ontario, Canada; Ottawa Institute of Systems Biology, Ottawa, Ontario, Canada; National Research Council of Canada, Digital Technologies Research Centre, Ottawa, Canada
| | - Ruth McPherson
- Division of Cardiology, University of Ottawa Heart Institute, Ottawa, Ontario Canada
| | - Robert R M Dent
- Division of Endocrinology, Department of Medicine, University of Ottawa, Ottawa, Ontario, Canada
| | - Mary-Ellen Harper
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, Ontario, Canada; Ottawa Institute of Systems Biology, Ottawa, Ontario, Canada; Centre for Infection, Immunity and Inflammation, Ottawa, Ontario, Canada.
| |
Collapse
|
11
|
Samartsev VN, Semenova AA, Ivanov AN, Dubinin MV. Comparative study of free respiration in liver mitochondria during oxidation of various electron donors and under conditions of shutdown of complex III of the respiratory chain. Biochem Biophys Res Commun 2022; 606:163-167. [PMID: 35364324 DOI: 10.1016/j.bbrc.2022.03.099] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Accepted: 03/19/2022] [Indexed: 11/02/2022]
Abstract
The present work shows that the rate of free respiration of liver mitochondria (in the absence of ATP synthesis (state 4) during the oxidation of succinate is 1.7 times higher than during the oxidation of glutamate with malate. In turn, in the case of oxidation of ferrocyanide with ascorbate, this value is 3.1 times greater than in the case of succinate oxidation. A similar pattern is also observed upon stimulation of free respiration by low concentrations (5 and 10 μM) of the protonophore uncoupler 2,4-dinitrophenol (DNP). It is found that the passive leakage rate of protons in state 4 is the same if the H+/O ratios are 10, 6, and 2 upon the oxidation of glutamate with malate, succinate, and ferrocyanide with ascorbate, respectively. At these values of the H+/O ratio, low concentrations of DNP stimulate passive proton leakage equally during the oxidation of these respiration substrates. In the case of succinate oxidation, bypassing complex III by N,N,N',N'-tetramethyl-p-phenylenediamine (TMPD) to the maximum degree, as well as switching this complex completely to idle mode by α,ω-hexadecanedioic acid (HDA) cause a 3-fold stimulation of respiration in state 4. We conclude that at mitochondrial free respiration the values of the H+/2e- ratio for complexes I, III, and IV of the respiratory chain are 4, 4, and 2, respectively. It is assumed that the free respiration of mitochondria is carried out by simple diffusion of protons through the inner membrane, and the rate of this diffusion depends on the total number of protons released by the complexes of the electron transport chain into the intermembrane space.
Collapse
Affiliation(s)
- Victor N Samartsev
- Mari State University, pl. Lenina 1, Yoshkar-Ola, Mari El, 424001, Russia
| | - Alena A Semenova
- Mari State University, pl. Lenina 1, Yoshkar-Ola, Mari El, 424001, Russia
| | - Andrey N Ivanov
- Mari State University, pl. Lenina 1, Yoshkar-Ola, Mari El, 424001, Russia
| | - Mikhail V Dubinin
- Mari State University, pl. Lenina 1, Yoshkar-Ola, Mari El, 424001, Russia.
| |
Collapse
|
12
|
Cheropkina H, Catucci G, Marucco A, Fenoglio I, Gilardi G, Sadeghi SJ. Human flavin-containing monooxygenase 1 and its long-sought hydroperoxyflavin intermediate. Biochem Pharmacol 2021; 193:114763. [PMID: 34509493 DOI: 10.1016/j.bcp.2021.114763] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Revised: 09/03/2021] [Accepted: 09/07/2021] [Indexed: 01/22/2023]
Abstract
Out of the five isoforms of human flavin-containing monooxygenase (hFMO), FMO1 and FMO3 are the most relevant to Phase I drug metabolism. They are involved in the oxygenation of xenobiotics including drugs and pesticides using NADPH and FAD as cofactors. Majority of the characterization of these enzymes has involved hFMO3, where intermediates of its catalytic cycle have been described. On the other hand, research efforts have so far failed in capturing the same key intermediate that is responsible for the monooxygenation activity of hFMO1. In this work we demonstrate spectrophotometrically the formation of a highly stable C4a-hydroperoxyflavin intermediate of hFMO1 upon reduction by NADPH and in the presence of O2. The measured half-life of this flavin intermediate revealed it to be stable and not fully re-oxidized even after 30 min at 15 °C in the absence of substrate, the highest stability ever observed for a human FMO. In addition, the uncoupling reactions of hFMO1 show that this enzyme is <1% uncoupled in the presence of substrate, forming small amounts of H2O2 with no observable superoxide as confirmed by EPR spin trapping experiments. This behaviour is different from hFMO3, that is shown to form both H2O2 and superoxide anion radical as a result of ∼50% uncoupling. These data are consistent with the higher stability of the hFMO1 intermediate in comparison to hFMO3. Taken together, these data demonstrate the different behaviours of these two closely related enzymes with consequences for drug metabolism as well as possible toxicity due to reactive oxygen species.
Collapse
Affiliation(s)
- Hanna Cheropkina
- Department of Life Sciences and Systems Biology, University of Torino, Italy
| | - Gianluca Catucci
- Department of Life Sciences and Systems Biology, University of Torino, Italy
| | - Arianna Marucco
- Department of Life Sciences and Systems Biology, University of Torino, Italy
| | | | - Gianfranco Gilardi
- Department of Life Sciences and Systems Biology, University of Torino, Italy
| | - Sheila J Sadeghi
- Department of Life Sciences and Systems Biology, University of Torino, Italy.
| |
Collapse
|
13
|
Raimundo AFG, Dos Santos KBP, Klosowski EM, de Souza BTL, Mito MS, Constantin RP, Mantovanelli GC, Mewes JM, Bizerra PFV, Menezes PVMDC, Utsunomiya KS, Gilglioni EH, Marchiosi R, Dantas Dos Santos W, Ferrarese-Filho O, Caetano W, Pereira PCS, Gonçalves RS, Constantin J, Ishii-Iwamoto EL, Constantin RP. The photodynamic and intrinsic effects of Azure B on mitochondrial bioenergetics and the consequences of its intrinsic effects on hepatic energy metabolism. Photodiagnosis Photodyn Ther 2021; 35:102446. [PMID: 34289416 DOI: 10.1016/j.pdpdt.2021.102446] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2021] [Revised: 06/16/2021] [Accepted: 07/12/2021] [Indexed: 01/10/2023]
Abstract
BACKGROUND The present study aimed to characterize the intrinsic and photodynamic effects of azure B (AB) on mitochondrial bioenergetics, as well as the consequences of its intrinsic effects on hepatic energy metabolism. METHODS Two experimental systems were utilized: (a) isolated rat liver mitochondria and (b) isolated perfused rat liver. RESULTS AB interacted with mitochondria regardless of photostimulation, but its binding degree was reduced by mitochondrial energization. Under photostimulation, AB caused lipid peroxidation and protein carbonylation and decreased the content of reduced glutathione (GSH) in mitochondria. AB impaired mitochondrial bioenergetics in at least three distinct ways: (1) uncoupling of oxidative phosphorylation; (2) photoinactivation of complexes I and II; and (3) photoinactivation of the FoF1-ATP synthase complex. Without photostimulation, AB also demonstrated mitochondrial toxicity, which was characterized by the induction of lipid peroxidation, loss of inner mitochondrial membrane integrity, and uncoupling of oxidative phosphorylation. The perfused rat liver experiments showed that mitochondria were one of the major targets of AB, even in intact cells. AB inhibited gluconeogenesis and ureagenesis, two biosynthetic pathways strictly dependent on intramitochondrially generated ATP. Contrariwise, AB stimulated glycogenolysis and glycolysis, which are required compensatory pathways for the inhibited oxidative phosphorylation. Similarly, AB reduced the cellular ATP content and the ATP/ADP and ATP/AMP ratios. CONCLUSIONS Although the properties and severe photodynamic effects of AB on rat liver mitochondria might suggest its usefulness in PDT treatment of liver tumors, this possibility should be considered with precaution given the toxic intrinsic effects of AB on mitochondrial bioenergetics and energy-linked hepatic metabolism.
Collapse
|
14
|
de Souza BTL, Klosowski EM, Mito MS, Constantin RP, Mantovanelli GC, Mewes JM, Bizerra PFV, da Silva FSI, Menezes PVMDC, Gilglioni EH, Utsunomiya KS, Marchiosi R, Dos Santos WD, Ferrarese-Filho O, Caetano W, de Souza Pereira PC, Gonçalves RS, Constantin J, Ishii-Iwamoto EL, Constantin RP. The photosensitiser azure A disrupts mitochondrial bioenergetics through intrinsic and photodynamic effects. Toxicology 2021; 455:152766. [PMID: 33775737 DOI: 10.1016/j.tox.2021.152766] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Revised: 02/24/2021] [Accepted: 03/23/2021] [Indexed: 12/20/2022]
Abstract
Azure A (AA) is a cationic molecule of the class of phenothiazines that has been applied in vitro as a photosensitising agent in photodynamic antimicrobial chemotherapy. It is a di-demethylated analogue of methylene blue (MB), which has been demonstrated to be intrinsically and photodynamically highly active on mitochondrial bioenergetics. However, as far as we know, there are no studies about the photodynamic effects of AA on mammalian mitochondria. Therefore, this investigation aimed to characterise the intrinsic and photodynamic acute effects of AA (0.540 μM) on isolated rat liver mitochondria, isolated hepatocytes, and isolated perfused rat liver. The effects of AA were assessed by evaluating several parameters of mitochondrial bioenergetics, oxidative stress, cell viability, and hepatic energy metabolism. The photodynamic effects of AA were assessed under simulated hypoxic conditions, a suitable way for mimicking the microenvironment of hypoxic solid tumour cells. AA interacted with the mitochondria and, upon photostimulation (10 min of light exposure), produced toxic amounts of reactive oxygen species (ROS), which damaged the organelle, as demonstrated by the high levels of lipid peroxidation and protein carbonylation. The photostimulated AA also depleted the GSH pool, which could compromise the mitochondrial antioxidant defence. Bioenergetically, AA photoinactivated the complexes I, II, and IV of the mitochondrial respiratory chain and the F1FO-ATP synthase complex, sharply inhibiting the oxidative phosphorylation. Upon photostimulation (10 min of light exposure), AA reduced the efficiency of mitochondrial energy transduction and oxidatively damaged lipids in isolated hepatocytes but did not decrease the viability of cells. Despite the useful photobiological properties, AA presented noticeable dark toxicity on mitochondrial bioenergetics, functioning predominantly as an uncoupler of oxidative phosphorylation. This harmful effect of AA was evidenced in isolated hepatocytes, in which AA diminished the cellular ATP content. In this case, the cells exhibited signs of cell viability reduction in the presence of high AA concentrations, but only after a long time of incubation (at least 90 min). The impairments on mitochondrial bioenergetics were also clearly manifested in intact perfused rat liver, in which AA diminished the cellular ATP content and stimulated the oxygen uptake. Consequently, gluconeogenesis and ureogenesis were strongly inhibited, whereas glycogenolysis and glycolysis were stimulated. AA also promoted the release of cytosolic and mitochondrial enzymes into the perfusate concomitantly with inhibition of oxygen consumption. In general, the intrinsic and photodynamic effects of AA were similar to those of MB, but AA caused some distinct effects such as the photoinactivation of the complex IV of the mitochondrial respiratory chain and a diminution of the ATP levels in the liver. It is evident that AA has the potential to be used in mitochondria-targeted photodynamic therapy, even under low oxygen concentrations. However, the fact that AA directly disrupts mitochondrial bioenergetics and affects several hepatic pathways that are linked to ATP metabolism, along with its ability to perturb cellular membranes and its little potential to reduce cell viability, could result in significant adverse effects especially in long-term treatments.
Collapse
Affiliation(s)
- Byanca Thais Lima de Souza
- Department of Biochemistry, Laboratory of Biological Oxidations and Laboratory of Experimental Steatosis, State University of Maringá, Maringá, 87020-900, Paraná, Brazil.
| | - Eduardo Makiyama Klosowski
- Department of Biochemistry, Laboratory of Biological Oxidations and Laboratory of Experimental Steatosis, State University of Maringá, Maringá, 87020-900, Paraná, Brazil.
| | - Márcio Shigueaki Mito
- Department of Biochemistry, Laboratory of Biological Oxidations and Laboratory of Experimental Steatosis, State University of Maringá, Maringá, 87020-900, Paraná, Brazil.
| | - Renato Polimeni Constantin
- Department of Biochemistry, Laboratory of Plant Biochemistry, State University of Maringá, Maringá, 87020-900, Paraná, Brazil.
| | - Gislaine Cristiane Mantovanelli
- Department of Biochemistry, Laboratory of Biological Oxidations and Laboratory of Experimental Steatosis, State University of Maringá, Maringá, 87020-900, Paraná, Brazil.
| | - Juliana Morais Mewes
- Department of Biochemistry, Laboratory of Biological Oxidations and Laboratory of Experimental Steatosis, State University of Maringá, Maringá, 87020-900, Paraná, Brazil.
| | - Paulo Francisco Veiga Bizerra
- Department of Biochemistry, Laboratory of Biological Oxidations and Laboratory of Experimental Steatosis, State University of Maringá, Maringá, 87020-900, Paraná, Brazil.
| | - Fernanda Sayuri Itou da Silva
- Department of Biochemistry, Laboratory of Biological Oxidations and Laboratory of Experimental Steatosis, State University of Maringá, Maringá, 87020-900, Paraná, Brazil.
| | - Paulo Vinicius Moreira da Costa Menezes
- Department of Biochemistry, Laboratory of Biological Oxidations and Laboratory of Experimental Steatosis, State University of Maringá, Maringá, 87020-900, Paraná, Brazil.
| | - Eduardo Hideo Gilglioni
- Department of Biochemistry, Laboratory of Biological Oxidations and Laboratory of Experimental Steatosis, State University of Maringá, Maringá, 87020-900, Paraná, Brazil.
| | - Karina Sayuri Utsunomiya
- Department of Biochemistry, Laboratory of Biological Oxidations and Laboratory of Experimental Steatosis, State University of Maringá, Maringá, 87020-900, Paraná, Brazil.
| | - Rogério Marchiosi
- Department of Biochemistry, Laboratory of Plant Biochemistry, State University of Maringá, Maringá, 87020-900, Paraná, Brazil.
| | - Wanderley Dantas Dos Santos
- Department of Biochemistry, Laboratory of Plant Biochemistry, State University of Maringá, Maringá, 87020-900, Paraná, Brazil.
| | - Osvaldo Ferrarese-Filho
- Department of Biochemistry, Laboratory of Plant Biochemistry, State University of Maringá, Maringá, 87020-900, Paraná, Brazil.
| | - Wilker Caetano
- Department of Chemistry, Research Nucleus in Photodynamic System, State University of Maringá, Maringá, 87020-900, Paraná, Brazil.
| | - Paulo Cesar de Souza Pereira
- Department of Chemistry, Research Nucleus in Photodynamic System, State University of Maringá, Maringá, 87020-900, Paraná, Brazil.
| | - Renato Sonchini Gonçalves
- Department of Chemistry, Research Nucleus in Photodynamic System, State University of Maringá, Maringá, 87020-900, Paraná, Brazil.
| | - Jorgete Constantin
- Department of Biochemistry, Laboratory of Biological Oxidations and Laboratory of Experimental Steatosis, State University of Maringá, Maringá, 87020-900, Paraná, Brazil.
| | - Emy Luiza Ishii-Iwamoto
- Department of Biochemistry, Laboratory of Biological Oxidations and Laboratory of Experimental Steatosis, State University of Maringá, Maringá, 87020-900, Paraná, Brazil.
| | - Rodrigo Polimeni Constantin
- Department of Biochemistry, Laboratory of Biological Oxidations and Laboratory of Experimental Steatosis, State University of Maringá, Maringá, 87020-900, Paraná, Brazil; Department of Biochemistry, Laboratory of Plant Biochemistry, State University of Maringá, Maringá, 87020-900, Paraná, Brazil.
| |
Collapse
|
15
|
Ho KL, Karwi QG, Wagg C, Zhang L, Vo K, Altamimi T, Uddin GM, Ussher JR, Lopaschuk GD. Ketones can become the major fuel source for the heart but do not increase cardiac efficiency. Cardiovasc Res 2021; 117:1178-1187. [PMID: 32402081 PMCID: PMC7982999 DOI: 10.1093/cvr/cvaa143] [Citation(s) in RCA: 48] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Revised: 04/16/2020] [Accepted: 05/07/2020] [Indexed: 12/18/2022] Open
Abstract
AIMS Ketones have been proposed to be a 'thrifty' fuel for the heart and increasing cardiac ketone oxidation can be cardioprotective. However, it is unclear how much ketone oxidation can contribute to energy production in the heart, nor whether increasing ketone oxidation increases cardiac efficiency. Therefore, our goal was to determine to what extent high levels of the ketone body, β-hydroxybutyrate (βOHB), contributes to cardiac energy production, and whether this influences cardiac efficiency. METHODS AND RESULTS Isolated working mice hearts were aerobically perfused with palmitate (0.8 mM or 1.2 mM), glucose (5 mM) and increasing concentrations of βOHB (0, 0.6, 2.0 mM). Subsequently, oxidation of these substrates, cardiac function, and cardiac efficiency were assessed. Increasing βOHB concentrations increased myocardial ketone oxidation rates without affecting glucose or fatty acid oxidation rates where normal physiological levels of glucose (5 mM) and fatty acid (0.8 mM) are present. Notably, ketones became the major fuel source for the heart at 2.0 mM βOHB (at both low or high fatty acid concentrations), with the elevated ketone oxidation rates markedly increasing tricarboxylic acid (TCA) cycle activity, producing a large amount of reducing equivalents and finally, increasing myocardial oxygen consumption. However, the marked increase in ketone oxidation at high concentrations of βOHB was not accompanied by an increase in cardiac work, suggesting that a mismatch between excess reduced equivalents production from ketone oxidation and cardiac adenosine triphosphate production. Consequently, cardiac efficiency decreased when the heart was exposed to higher ketone levels. CONCLUSIONS We demonstrate that while ketones can become the major fuel source for the heart, they do not increase cardiac efficiency, which also underscores the importance of recognizing ketones as a major fuel source for the heart in times of starvation, consumption of a ketogenic diet or poorly controlled diabetes.
Collapse
Affiliation(s)
- Kim L Ho
- Cardiovascular Research Centre Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB T6G 2S2, Canada
| | - Qutuba G Karwi
- Cardiovascular Research Centre Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB T6G 2S2, Canada
- Department of Pharmacology, College of Medicine, University of Diyala, Diyala, Iraq
| | - Cory Wagg
- Cardiovascular Research Centre Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB T6G 2S2, Canada
| | - Liyan Zhang
- Cardiovascular Research Centre Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB T6G 2S2, Canada
| | - Katherina Vo
- Cardiovascular Research Centre Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB T6G 2S2, Canada
| | - Tariq Altamimi
- Diabetes and Obesity Center, University of Louisville, Louisville, KT, USA
| | - Golam M Uddin
- Cardiovascular Research Centre Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB T6G 2S2, Canada
| | - John R Ussher
- Cardiovascular Research Centre Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB T6G 2S2, Canada
- Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, AB, Canada
| | - Gary D Lopaschuk
- Cardiovascular Research Centre Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB T6G 2S2, Canada
| |
Collapse
|
16
|
Hass DT, Barnstable CJ. Uncoupling proteins in the mitochondrial defense against oxidative stress. Prog Retin Eye Res 2021; 83:100941. [PMID: 33422637 DOI: 10.1016/j.preteyeres.2021.100941] [Citation(s) in RCA: 45] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Revised: 12/28/2020] [Accepted: 01/03/2021] [Indexed: 02/06/2023]
Abstract
Oxidative stress is a major component of most major retinal diseases. Many extrinsic anti-oxidative strategies have been insufficient at counteracting one of the predominant intrinsic sources of reactive oxygen species (ROS), mitochondria. The proton gradient across the inner mitochondrial membrane is a key driving force for mitochondrial ROS production, and this gradient can be modulated by members of the mitochondrial uncoupling protein (UCP) family. Of the UCPs, UCP2 shows a widespread distribution and has been shown to uncouple oxidative phosphorylation, with concomitant decreases in ROS production. Genetic studies using transgenic and knockout mice have documented the ability of increased UCP2 activity to provide neuroprotection in models of a number of diseases, including retinal diseases, indicating that it is a strong candidate for a therapeutic target. Molecular studies have identified the structural mechanism of action of UCP2 and have detailed the ways in which its expression and activity can be controlled at the transcriptional, translational and posttranslational levels. These studies suggest a number of ways in control of UCP2 expression and activity can be used therapeutically for both acute and chronic conditions. The development of such therapeutic approaches will greatly increase the tools available to combat a broad range of serious retinal diseases.
Collapse
Affiliation(s)
- Daniel T Hass
- Department of Biochemistry, The University of Washington, Seattle, WA, 98109, USA
| | - Colin J Barnstable
- Department of Neural and Behavioral Sciences, The Pennsylvania State University, Hershey, PA, 17033, USA.
| |
Collapse
|
17
|
Semenova AA, Samartsev VN, Dubinin MV. The stimulation of succinate-fueled respiration of rat liver mitochondria in state 4 by α,ω-hexadecanedioic acid without induction of proton conductivity of the inner membrane. Intrinsic uncoupling of the bc 1 complex. Biochimie 2021; 181:215-225. [PMID: 33400934 DOI: 10.1016/j.biochi.2020.12.021] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Revised: 12/19/2020] [Accepted: 12/28/2020] [Indexed: 10/22/2022]
Abstract
The paper shows that natural α,ω-dioic acid, α,ω-hexadecanedioic acid (HDA), is able to stimulate the respiration of succinate-fueled rat liver mitochondria in state 4 without induction of proton conductivity of the inner membrane. This effect of HDA is less pronounced in glutamate/malate-fueled mitochondria, as well as in the case of ascorbate/TMPD or ascorbate/ferrocyanide substrate systems, which transfer electrons directly to cytochrome c. It is noted that HDA-induced stimulation of respiration is not associated with damage to the inner membrane in a part of mitochondria and with shunting of electrons through the bc1 complex. Therefore, HDA can be considered as a natural decoupling agent. Specific inhibitors of the bc1 complex (antimycin A and myxothiazole) as well as malonate and dithionitrobenzoate were used in the inhibitory analysis. These and other experiments have shown that during the oxidation of succinate in liver mitochondria, the decoupling effect of HDA is mainly carried out at the level of the bc1 complex. We hypothesized that HDA is capable of promoting the cyclic transport of protons within the bc1 complex and thus switch this complex to the idle mode of operation (intrinsic uncoupling of the bc1 complex). Induction of free respiration in liver mitochondria by HDA at the level of the bc1 complex is considered as one of the "rescue pathways" of hepatocytes in various pathological conditions, accompanied by disorders of carbohydrate and lipid metabolism and increased oxidative stress.
Collapse
Affiliation(s)
- Alena A Semenova
- Mari State University, Pl. Lenina 1, Yoshkar-Ola, Mari El, 424001, Russia
| | - Victor N Samartsev
- Mari State University, Pl. Lenina 1, Yoshkar-Ola, Mari El, 424001, Russia
| | - Mikhail V Dubinin
- Mari State University, Pl. Lenina 1, Yoshkar-Ola, Mari El, 424001, Russia.
| |
Collapse
|
18
|
Klosowski EM, de Souza BTL, Mito MS, Constantin RP, Mantovanelli GC, Mewes JM, Bizerra PFV, Menezes PVMDC, Gilglioni EH, Utsunomiya KS, Marchiosi R, Dos Santos WD, Filho OF, Caetano W, Pereira PCDS, Gonçalves RS, Constantin J, Ishii-Iwamoto EL, Constantin RP. The photodynamic and direct actions of methylene blue on mitochondrial energy metabolism: A balance of the useful and harmful effects of this photosensitizer. Free Radic Biol Med 2020; 153:34-53. [PMID: 32315767 DOI: 10.1016/j.freeradbiomed.2020.04.015] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Revised: 04/13/2020] [Accepted: 04/13/2020] [Indexed: 02/06/2023]
Abstract
According to the literature, methylene blue (MB) is a photosensitizer (PS) with a high affinity for mitochondria. Therefore, several studies have explored this feature to evaluate its photodynamic effects on the mitochondrial apoptotic pathway under normoxic conditions. We are aware only of limited reports regarding MB's photodynamic effects on mitochondrial energy metabolism, especially under hypoxic conditions. Thus, the purposes of this study were to determine the direct and photodynamic acute effects of MB on the energy metabolism of rat liver mitochondria under hypoxic conditions and its direct acute effects on several parameters linked to energy metabolism in the isolated perfused rat liver. MB presented a high affinity for mitochondria, irrespective of photostimulation or proton gradient formation. Upon photostimulation, MB demonstrated high in vitro oxidizing species generation ability. Consequently, MB damaged the mitochondrial macromolecules, as could be evidenced by the elevated levels of lipid peroxidation and protein carbonyls. In addition to generating a pro-oxidant environment, MB also led to a deficient antioxidant defence system, as indicated by the reduced glutathione (GSH) depletion. Bioenergetically, MB caused uncoupling of oxidative phosphorylation and led to photodynamic inactivation of complex I, complex II, and F1FO-ATP synthase complex, thus decreasing mitochondrial ATP generation. Contrary to what is expected for an ideal PS, MB displayed appreciable dark toxicity on mitochondrial energy metabolism. The results indicated that MB acted via at least three mechanisms: direct damage to the inner mitochondrial membrane; uncoupling of oxidative phosphorylation; and inhibition of electron transfer. Confirming the impairment of mitochondrial energy metabolism, MB also strongly inhibited mitochondrial ATP production. In the perfused rat liver, MB stimulated oxygen consumption, decreased the ATP/ADP ratio, inhibited gluconeogenesis and ureogenesis, and stimulated glycogenolysis, glycolysis, and ammoniagenesis, fully corroborating its uncoupling action in intact cells, as well. It can be concluded that even under hypoxic conditions, MB is a PS with potential for photodynamic effect-induced mitochondrial dysfunction. However, MB disrupts the mitochondrial energy metabolism even in the dark, causing energy-linked liver metabolic changes that could be harmful in specific circumstances.
Collapse
Affiliation(s)
- Eduardo Makiyama Klosowski
- Department of Biochemistry, Laboratory of Biological Oxidations and Laboratory of Experimental Steatosis, State University of Maringá, Maringá, 87020-900, Paraná, Brazil.
| | - Byanca Thais Lima de Souza
- Department of Biochemistry, Laboratory of Biological Oxidations and Laboratory of Experimental Steatosis, State University of Maringá, Maringá, 87020-900, Paraná, Brazil.
| | - Marcio Shigueaki Mito
- Department of Biochemistry, Laboratory of Biological Oxidations and Laboratory of Experimental Steatosis, State University of Maringá, Maringá, 87020-900, Paraná, Brazil.
| | - Renato Polimeni Constantin
- Department of Biochemistry, Laboratory of Plant Biochemistry, State University of Maringá, Maringá, 87020-900, Paraná, Brazil.
| | - Gislaine Cristiane Mantovanelli
- Department of Biochemistry, Laboratory of Biological Oxidations and Laboratory of Experimental Steatosis, State University of Maringá, Maringá, 87020-900, Paraná, Brazil.
| | - Juliana Morais Mewes
- Department of Biochemistry, Laboratory of Biological Oxidations and Laboratory of Experimental Steatosis, State University of Maringá, Maringá, 87020-900, Paraná, Brazil.
| | - Paulo Francisco Veiga Bizerra
- Department of Biochemistry, Laboratory of Biological Oxidations and Laboratory of Experimental Steatosis, State University of Maringá, Maringá, 87020-900, Paraná, Brazil.
| | - Paulo Vinicius Moreira da Costa Menezes
- Department of Biochemistry, Laboratory of Biological Oxidations and Laboratory of Experimental Steatosis, State University of Maringá, Maringá, 87020-900, Paraná, Brazil.
| | - Eduardo Hideo Gilglioni
- Department of Biochemistry, Laboratory of Biological Oxidations and Laboratory of Experimental Steatosis, State University of Maringá, Maringá, 87020-900, Paraná, Brazil.
| | - Karina Sayuri Utsunomiya
- Department of Biochemistry, Laboratory of Biological Oxidations and Laboratory of Experimental Steatosis, State University of Maringá, Maringá, 87020-900, Paraná, Brazil.
| | - Rogério Marchiosi
- Department of Biochemistry, Laboratory of Plant Biochemistry, State University of Maringá, Maringá, 87020-900, Paraná, Brazil.
| | - Wanderley Dantas Dos Santos
- Department of Biochemistry, Laboratory of Plant Biochemistry, State University of Maringá, Maringá, 87020-900, Paraná, Brazil.
| | - Osvaldo Ferrarese Filho
- Department of Biochemistry, Laboratory of Plant Biochemistry, State University of Maringá, Maringá, 87020-900, Paraná, Brazil.
| | - Wilker Caetano
- Department of Chemistry, State University of Maringá, Maringá, 87020-900, Paraná, Brazil.
| | | | | | - Jorgete Constantin
- Department of Biochemistry, Laboratory of Biological Oxidations and Laboratory of Experimental Steatosis, State University of Maringá, Maringá, 87020-900, Paraná, Brazil.
| | - Emy Luiza Ishii-Iwamoto
- Department of Biochemistry, Laboratory of Biological Oxidations and Laboratory of Experimental Steatosis, State University of Maringá, Maringá, 87020-900, Paraná, Brazil.
| | - Rodrigo Polimeni Constantin
- Department of Biochemistry, Laboratory of Biological Oxidations and Laboratory of Experimental Steatosis, State University of Maringá, Maringá, 87020-900, Paraná, Brazil.
| |
Collapse
|
19
|
Samartsev VN, Semenova AA, Dubinin MV. A Comparative Study of the Action of Protonophore Uncouplers and Decoupling Agents as Inducers of Free Respiration in Mitochondria in States 3 and 4: Theoretical and Experimental Approaches. Cell Biochem Biophys 2020; 78:203-16. [PMID: 32367259 DOI: 10.1007/s12013-020-00914-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2020] [Accepted: 04/17/2020] [Indexed: 02/07/2023]
Abstract
Theoretical and experimental studies have revealed that that in the liver mitochondria an increase in the rate of free respiration in state 3 induced by protonophore uncouplers 2,4-dinitrophenol and сarbonyl cyanide 4-(trifluoromethoxy)phenylhydrazone is equal to or slightly greater than the increase in respiration rate in state 4 induced by these uncouplers. In contrast to these protonophore uncouplers, the decoupler α,ω-tetradecanedioic acid, increasing the rate of respiration in state 4, does not significantly affect the rate of free respiration in state 3. We have proposed quantitative indicators that allow determining the constituent part of the rate of respiration in state 4, associated with the decoupling effect of the uncoupler. Using the example of palmitic acid, we have found out the fundamental possibility of the simultaneous functioning of uncouplers by two mechanisms: as protonophores and as decouplers. The data obtained contradict the delocalized version of Mitchell's chemiosmotic theory, but are in complete agreement with its local version. It can be assumed that the F0F1-ATP synthase and nearby respiratory chain complexes form a local zone of coupled respiration and oxidative ATP synthesis (zones of oxidative phosphorylation). The uncoupler-induced stimulation of mitochondrial free respiration of mitochondria in state 3 is mainly due to the return of protons to the matrix in local zones, where the generation of a proton motive force (Δр) by respiratory chain complexes is associated with various transport processes, but not with ATP synthesis (zones of protonophore uncoupling). In contrast, respiratory stimulation in state 4 by decouplers is realized in local zones of oxidative phosphorylation by switching the respiratory chain complexes to the idle mode of operation in the absence of ATP synthesis.
Collapse
|
20
|
Wu K, Luan G, Xu Y, Shen S, Qian S, Zhu Z, Zhang X, Yin S, Ye J. Cigarette smoke extract increases mitochondrial membrane permeability through activation of adenine nucleotide translocator (ANT) in lung epithelial cells. Biochem Biophys Res Commun 2020; 525:733-739. [PMID: 32143825 DOI: 10.1016/j.bbrc.2020.02.160] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2020] [Accepted: 02/20/2020] [Indexed: 10/24/2022]
Abstract
Cigarette smoke is one of major risk factors in the pathogenesis of chronic obstructive pulmonary disease (COPD). It is generally believed that cigarette smoke induces mitochondrial damage in the alveolar epithelial cells to contribute to COPD. However, the exact molecular mechanism remains unknown for the mitochondrial damage. In this study, cigarette smoke extract (CSE) was found to induce the mitochondrial membrane permeability (MMP), which promoted proton leakage leading to the reduction in mitochondrial potential and ATP production. ANT in the mitochondrial inner membrane was activated by CSE for the alteration of MMP. The activation was observed without an alteration in the protein level of ANT. Inhibition of the ANT activity with ADP or bongkrekic acid prevented the MMP alteration and potential drop upon CSE exposure. The ANT activation was observed with a rise in ROS production, inhibition of the mitochondrial respiration, decrease in the complex III protein and rise in mitophagy activity. The results suggest that ANT may mediate the toxic effect of cigarette smoke on mitochondria and control of ANT activity is a potential strategy in intervention of the toxicity.
Collapse
Affiliation(s)
- Kaiyue Wu
- National Demonstration Center for Experimental Fisheries Science Education, Shanghai Ocean University, Shanghai, 201306, China; Department of Respiratory Medicine, Shanghai Sixth People's Hospital East, Shanghai University of Medicine & Health Sciences, Shanghai, 201306, China
| | - Guangxin Luan
- National Demonstration Center for Experimental Fisheries Science Education, Shanghai Ocean University, Shanghai, 201306, China; Department of Respiratory Medicine, Shanghai Sixth People's Hospital East, Shanghai University of Medicine & Health Sciences, Shanghai, 201306, China
| | - Yanhong Xu
- Central Laboratory, Shanghai Sixth People's Hospital East Campus, Shanghai University of Medicine & Health Sciences, Shanghai, 201306, China
| | - Shuang Shen
- Central Laboratory, Shanghai Sixth People's Hospital East Campus, Shanghai University of Medicine & Health Sciences, Shanghai, 201306, China
| | - Shengnan Qian
- Central Laboratory, Shanghai Sixth People's Hospital East Campus, Shanghai University of Medicine & Health Sciences, Shanghai, 201306, China
| | - Zhen Zhu
- Department of Respiratory Medicine, Shanghai Sixth People's Hospital East, Shanghai University of Medicine & Health Sciences, Shanghai, 201306, China
| | - Xiaoying Zhang
- Central Laboratory, Shanghai Sixth People's Hospital East Campus, Shanghai University of Medicine & Health Sciences, Shanghai, 201306, China
| | - Shaojun Yin
- Department of Respiratory Medicine, Shanghai Sixth People's Hospital East, Shanghai University of Medicine & Health Sciences, Shanghai, 201306, China.
| | - Jianping Ye
- Central Laboratory, Shanghai Sixth People's Hospital East Campus, Shanghai University of Medicine & Health Sciences, Shanghai, 201306, China; Shanghai Diabetes Institute, Sixth People's Hospital, Shanghai Jiao Tong University, Shanghai, 200233, China.
| |
Collapse
|
21
|
Escher BI, Abagyan R, Embry M, Klüver N, Redman AD, Zarfl C, Parkerton TF. Recommendations for Improving Methods and Models for Aquatic Hazard Assessment of Ionizable Organic Chemicals. Environ Toxicol Chem 2020; 39:269-286. [PMID: 31569266 DOI: 10.1002/etc.4602] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Revised: 09/04/2019] [Accepted: 09/20/2019] [Indexed: 05/19/2023]
Abstract
Ionizable organic chemicals (IOCs) such as organic acids and bases are an important substance class requiring aquatic hazard evaluation. Although the aquatic toxicity of IOCs is highly dependent on the water pH, many toxicity studies in the literature cannot be interpreted because pH was not reported or not kept constant during the experiment, calling for an adaptation and improvement of testing guidelines. The modulating influence of pH on toxicity is mainly caused by pH-dependent uptake and bioaccumulation of IOCs, which can be described by ion-trapping and toxicokinetic models. The internal effect concentrations of IOCs were found to be independent of the external pH because of organisms' and cells' ability to maintain a stable internal pH milieu. If the external pH is close to the internal pH, existing quantitative structure-activity relationships (QSARs) for neutral organics can be adapted by substituting the octanol-water partition coefficient by the ionization-corrected liposome-water distribution ratio as the hydrophobicity descriptor, demonstrated by modification of the target lipid model. Charged, zwitterionic and neutral species of an IOC can all contribute to observed toxicity, either through concentration-additive mixture effects or by interaction of different species, as is the case for uncoupling of mitochondrial respiration. For specifically acting IOCs, we recommend a 2-step screening procedure with ion-trapping/QSAR models used to predict the baseline toxicity, followed by adjustment using the toxic ratio derived from in vitro systems. Receptor- or plasma-binding models also show promise for elucidating IOC toxicity. The present review is intended to help demystify the ecotoxicity of IOCs and provide recommendations for their hazard and risk assessment. Environ Toxicol Chem 2020;39:269-286. © 2019 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals, Inc. on behalf of SETAC.
Collapse
Affiliation(s)
- Beate I Escher
- Helmholtz Centre for Environmental Research-UFZ, Leipzig, Germany
- Center for Applied Geoscience, Eberhard Karls University of Tübingen, Tübingen, Germany
| | - Ruben Abagyan
- Skaggs School of Pharmacy & Pharmaceutical Sciences, University of California San Diego, La Jolla, California, USA
| | - Michelle Embry
- Health and Environmental Sciences Institute, Washington, DC, USA
| | - Nils Klüver
- Helmholtz Centre for Environmental Research-UFZ, Leipzig, Germany
| | | | - Christiane Zarfl
- Center for Applied Geoscience, Eberhard Karls University of Tübingen, Tübingen, Germany
| | | |
Collapse
|
22
|
Foitzick MF, Medina NB, Iglesias García LC, Gravielle MC. Benzodiazepine exposure induces transcriptional down-regulation of GABA A receptor α1 subunit gene via L-type voltage-gated calcium channel activation in rat cerebrocortical neurons. Neurosci Lett 2020; 721:134801. [PMID: 32007495 DOI: 10.1016/j.neulet.2020.134801] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Revised: 01/24/2020] [Accepted: 01/30/2020] [Indexed: 01/10/2023]
Abstract
GABAA receptors are targets of different pharmacologically relevant drugs, such as barbiturates, benzodiazepines, and anesthetics. In particular, benzodiazepines are prescribed for the treatment of anxiety, sleep disorders, and seizure disorders. Benzodiazepines potentiate GABA responses by binding to GABAA receptors, which are mainly composed of α (1-3, 5), β2, and γ2 subunits. Prolonged activation of GABAA receptors by endogenous and exogenous modulators induces adaptive changes that lead to tolerance. For example, chronic administration of benzodiazepines produces tolerance to most of their pharmacological actions, limiting their usefulness. The mechanism of benzodiazepine tolerance is still unknown. To investigate the molecular basis of tolerance, we studied the effect of sustained exposure of rat cerebral cortical neurons to diazepam on the GABAA receptor. Flunitrazepam binding experiments showed that diazepam treatment induced uncoupling between GABA and benzodiazepine sites, which was blocked by co-incubation with flumazenil, picrotoxin, or nifedipine. Diazepam also produced selective transcriptional down-regulation of GABAA receptor α1 subunit gene through a mechanism dependent on the activation of L-type voltage-gated calcium channels. These findings suggest benzodiazepine-induced stimulation of calcium influx through L-type voltage-gated calcium channels triggers the activation of a signaling pathway that leads to uncoupling and an alteration of receptor subunit expression. Insights into the mechanism of benzodiazepine tolerance will contribute to the design of new drugs that can maintain their efficacies after long-term treatments.
Collapse
Affiliation(s)
- María Florencia Foitzick
- Instituto de Investigaciones Farmacológicas (ININFA), Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires. CONICET, Buenos Aires, Argentina
| | - Nelsy Beatriz Medina
- Instituto de Investigaciones Farmacológicas (ININFA), Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires. CONICET, Buenos Aires, Argentina
| | - Lucía Candela Iglesias García
- Instituto de Investigaciones Farmacológicas (ININFA), Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires. CONICET, Buenos Aires, Argentina
| | - María Clara Gravielle
- Instituto de Investigaciones Farmacológicas (ININFA), Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires. CONICET, Buenos Aires, Argentina.
| |
Collapse
|
23
|
Catucci G, Gao C, Rampolla G, Gilardi G, Sadeghi SJ. Uncoupled human flavin-containing monooxygenase 3 releases superoxide radical in addition to hydrogen peroxide. Free Radic Biol Med 2019; 145:250-255. [PMID: 31580948 DOI: 10.1016/j.freeradbiomed.2019.09.038] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/28/2019] [Revised: 09/26/2019] [Accepted: 09/29/2019] [Indexed: 11/21/2022]
Abstract
Human flavin-containing monooxygenase 3 (hFMO3) is a drug-metabolizing enzyme capable of performing N- or S-oxidation using the C4a-hydroperoxy intermediate. In this work, we employ both wild type hFMO3 as well as an active site polymorphic variant (N61S) to unravel the uncoupling reactions in the catalytic cycle of this enzyme. We demonstrate that in addition to H2O2 this enzyme also produces superoxide anion radicals as its uncoupling products. The level of uncoupling was found to vary between 50 and 70% (WT) and 90-98% (N61S) for incubations with NADPH and benzydamine over a period of 5 or 20 min, respectively. For the first time, we were able to follow the production of the superoxide radical in hFMO3, which was found to account for 13-18% of the total uncoupling of this human enzyme. Moreover, measurements in the presence or absence of the substrate show that the substrate lowers the level of uncoupling only related to the H2O2 and not the superoxide radical. This is consistent with the entry point of the substrate in this enzyme's catalytic cycle. These findings highlight the importance of the involvement of hFMO3 in the production of radicals in the endoplasmic reticulum, as well as the relevance of single-nucleotide polymorphism leading to deleterious effects of oxidative stress.
Collapse
Affiliation(s)
- Gianluca Catucci
- Department of Life Sciences and Systems Biology, University of Torino, Italy
| | - Chongliang Gao
- Department of Life Sciences and Systems Biology, University of Torino, Italy
| | - Giulia Rampolla
- Department of Life Sciences and Systems Biology, University of Torino, Italy
| | - Gianfranco Gilardi
- Department of Life Sciences and Systems Biology, University of Torino, Italy
| | - Sheila J Sadeghi
- Department of Life Sciences and Systems Biology, University of Torino, Italy.
| |
Collapse
|
24
|
Mottola G, Nikinmaa M, Anttila K. Hsp70s transcription-translation relationship depends on the heat shock temperature in zebrafish. Comp Biochem Physiol A Mol Integr Physiol 2019; 240:110629. [PMID: 31790806 DOI: 10.1016/j.cbpa.2019.110629] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2019] [Revised: 11/25/2019] [Accepted: 11/27/2019] [Indexed: 11/29/2022]
Abstract
Virtually all organisms respond to heat shock by transcription of genes encoding for heat shock proteins (HSPs), but the mechanisms behind post-transcriptional regulation are not known in detail. When we exposed zebrafish to 5 and 7 °C above normal rearing temperature for 30 min, hsp70 mRNA expression was 28 and 150 -fold higher than in control, respectively. Protein expression, on the other hand, showed no significant change at the +5 °C and a 2-fold increase at the +7 °C exposure. This suggests that the transcription of hsp70 gene does not immediately correspond to translation to related proteins under certain stress temperatures, but, when the temperature is higher, and potentially detrimental, transcription and translation are intimately coupled. Those results confirm that temperature is an important abiotic factor involved in heat shock post-transcriptional regulation mechanisms in fish. However, further studies are needed to determine the relationship between this environmental factor and post-transcriptional regulation mechanisms. Earlier, the coupling/uncoupling of hsp transcription and translation has only been studied using cold-water fish, or zebrafish embryos. With current findings, we suggest this mechanism might be present even in adult warm water fish like the zebrafish.
Collapse
Affiliation(s)
- Giovanna Mottola
- Department of Biology, University of Turku, Vesilinnantie 5, 20500 Turku, Finland..
| | - Mikko Nikinmaa
- Department of Biology, University of Turku, Vesilinnantie 5, 20500 Turku, Finland
| | - Katja Anttila
- Department of Biology, University of Turku, Vesilinnantie 5, 20500 Turku, Finland
| |
Collapse
|
25
|
Svab G, Doczi J, Gerencser AA, Ambrus A, Gallyas F, Sümegi B, Tretter L. The Mitochondrial Targets of Neuroprotective Drug Vinpocetine on Primary Neuron Cultures, Brain Capillary Endothelial Cells, Synaptosomes, and Brain Mitochondria. Neurochem Res 2019; 44:2435-2447. [PMID: 31535355 PMCID: PMC6776483 DOI: 10.1007/s11064-019-02871-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2019] [Revised: 08/29/2019] [Accepted: 09/05/2019] [Indexed: 12/13/2022]
Abstract
Vinpocetine is considered as neuroprotectant drug and used for treatment of brain ischemia and cognitive deficiencies for decades. A number of enzymes, channels and receptors can bind vinpocetine, however the mechanisms of many effects' are still not clear. The present study investigated the effects of vinpocetine from the mitochondrial bioenergetic aspects. In primary brain capillary endothelial cells the purinergic receptor-stimulated mitochondrial Ca2+ uptake and efflux were studied. Vinpocetine exerted a partial inhibition on the mitochondrial calcium efflux. In rodent brain synaptosomes vinpocetine (30 μM) inhibited respiration in uncoupler stimulated synaptosomes and decreased H2O2 release from the nerve terminals in resting and in complex I inhibited conditions, respectively. In isolated rat brain mitochondria using either complex I or complex II substrates leak respiration was stimulated, but ADP-induced respiration was inhibited by vinpocetine. The stimulation of oxidation was associated with a small extent of membrane depolarization. Mitochondrial H2O2 production was inhibited by vinpocetine under all conditions investigated. The most pronounced effects were detected with the complex II substrate succinate. Vinpocetine also mitigated both Ca2+-induced mitochondrial Ca2+-release and Ca2+-induced mitochondrial swelling. It lowered the rate of mitochondrial ATP synthesis, while increasing ATPase activity. These results indicate more than a single mitochondrial target of this vinca alkaloid. The relevance of the affected mitochondrial mechanisms in the anti ischemic effect of vinpocetine is discussed.
Collapse
Affiliation(s)
- Gergely Svab
- Department of Medical Biochemistry, MTA-SE Laboratory for Neurobiochemistry, Semmelweis University, 37-47 Tuzolto Street, Budapest, 1094, Hungary
| | - Judit Doczi
- Department of Medical Biochemistry, MTA-SE Laboratory for Neurobiochemistry, Semmelweis University, 37-47 Tuzolto Street, Budapest, 1094, Hungary
| | - Akos A Gerencser
- Department of Medical Biochemistry, MTA-SE Laboratory for Neurobiochemistry, Semmelweis University, 37-47 Tuzolto Street, Budapest, 1094, Hungary.,Buck Institute for Research on Aging, Novato, CA, USA
| | - Attila Ambrus
- Department of Medical Biochemistry, MTA-SE Laboratory for Neurobiochemistry, Semmelweis University, 37-47 Tuzolto Street, Budapest, 1094, Hungary
| | - Ferenc Gallyas
- Department of Biochemistry and Medical Chemistry, University of Pecs Medical School, Pecs, Hungary.,Szentagothai Research Centre, University of Pecs, Pecs, Hungary.,Nuclear-Mitochondrial Interactions Research Group, Hungarian Academy of Sciences, Budapest, Hungary
| | - Balazs Sümegi
- Department of Biochemistry and Medical Chemistry, University of Pecs Medical School, Pecs, Hungary.,Szentagothai Research Centre, University of Pecs, Pecs, Hungary.,Nuclear-Mitochondrial Interactions Research Group, Hungarian Academy of Sciences, Budapest, Hungary
| | - László Tretter
- Department of Medical Biochemistry, MTA-SE Laboratory for Neurobiochemistry, Semmelweis University, 37-47 Tuzolto Street, Budapest, 1094, Hungary.
| |
Collapse
|
26
|
Auger C, Knuth CM, Abdullahi A, Samadi O, Parousis A, Jeschke MG. Metformin prevents the pathological browning of subcutaneous white adipose tissue. Mol Metab 2019; 29:12-23. [PMID: 31668383 PMCID: PMC6728757 DOI: 10.1016/j.molmet.2019.08.011] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Revised: 08/02/2019] [Accepted: 08/12/2019] [Indexed: 12/13/2022] Open
Abstract
Objective Browning, the conversion of white adipose tissue (WAT) to a beige phenotype, has gained interest as a strategy to induce weight loss and improve insulin resistance in metabolic disorders. However, for hypermetabolic conditions stemming from burn trauma or cancer cachexia, browning is thought to contribute to energy wasting and supraphysiological nutritional requirements. Metformin's impact on this phenomenon and underlying mechanisms have not been explored. Methods We used both a murine burn model and human ex vivo adipose explants to assess metformin and 5-aminoimidazole-4-carboxamide ribonucleotide (AICAR)'s effects on the development of subcutaneous beige adipose. Enzymes involved in fat homeostasis and browning, as well as mitochondrial dynamics, were assessed to determine metformin's effects. Results Treatment with the biguanide metformin lowers lipolysis in beige fat by inducing protein phosphatase 2A (PP2A) independently of adenosine monophosphate kinase (AMPK) activation. Increased PP2A activity catalyzes the dephosphorylation of acetyl-CoA carboxylase (Ser 79) and hormone sensitive lipase (Ser 660), thus promoting fat storage and the “whitening” of otherwise lipolytic beige adipocytes. Moreover, co-incubation of metformin with the PP2A inhibitor okadaic acid countered the anti-lipolytic effects of this biguanide in human adipose. Additionally, we show that metformin does not activate this pathway in the WAT of control mice and that AICAR sustains the browning of white adipose, offering further evidence that metformin acts independently of this cellular energy sensor. Conclusions This work provides novel insights into the mechanistic underpinnings of metformin's therapeutic benefits and potential as an agent to reduce the lipotoxicity associated with hypermetabolism and adipose browning. Metformin prevents the catabolism of murine iWAT tissue post-burn injury. Mitochondrial respiration and uncoupling in adipose are decreased by metformin. Metformin, independently of AMPK, reduces adipose lipolysis and β-oxidation via PP2A. AICAR treatment activates AMPK in peripheral adipose leading to sustained browning. PP2A is directly induced by metformin in scWAT, lowering ACC/HSL phosphorylation.
Collapse
Affiliation(s)
- Christopher Auger
- Ross Tilley Burn Centre, Sunnybrook Health Sciences Centre, Toronto, Ontario, M4N 3M5, Canada
| | - Carly M Knuth
- University of Toronto, Toronto, Ontario, M5S 1A1, Canada
| | | | - Osai Samadi
- University of Toronto, Toronto, Ontario, M5S 1A1, Canada
| | - Alexandra Parousis
- Ross Tilley Burn Centre, Sunnybrook Health Sciences Centre, Toronto, Ontario, M4N 3M5, Canada
| | - Marc G Jeschke
- Ross Tilley Burn Centre, Sunnybrook Health Sciences Centre, Toronto, Ontario, M4N 3M5, Canada; University of Toronto, Toronto, Ontario, M5S 1A1, Canada.
| |
Collapse
|
27
|
Gebhart V, Reiß K, Kollau A, Mayer B, Gorren ACF. Site and mechanism of uncoupling of nitric-oxide synthase: Uncoupling by monomerization and other misconceptions. Nitric Oxide 2019; 89:14-21. [PMID: 31022534 DOI: 10.1016/j.niox.2019.04.007] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2019] [Revised: 03/15/2019] [Accepted: 04/15/2019] [Indexed: 01/20/2023]
Abstract
Nitric oxide synthase (NOS) catalyzes the transformation of l-arginine, molecular oxygen (O2), and NADPH-derived electrons to nitric oxide (NO) and l-citrulline. Under some conditions, however, NOS catalyzes the reduction of O2 to superoxide (O2-) instead, a phenomenon that is generally referred to as uncoupling. In principle, both the heme in the oxygenase domain and the flavins in the reductase domain could catalyze O2- formation. In the former case the oxyferrous (Fe(II)O2) complex that is formed as an intermediate during catalysis would dissociate to heme and O2-; in the latter case the reduced flavins would reduce O2 to O2-. The NOS cofactor tetrahydrobiopterin (BH4) is indispensable for coupled catalysis. In the case of uncoupling at the heme this is explained by the essential role of BH4 as an electron donor to the oxyferrous complex; in the case of uncoupling at the flavins it is assumed that the absence of BH4 results in NOS monomerization, with the monomers incapable to sustain NO synthesis but still able to support uncoupled catalysis. In spite of little supporting evidence, uncoupling at the reductase after NOS monomerization appears to be the predominant hypothesis at present. To set the record straight we extended prior studies by determining under which conditions uncoupling of the neuronal and endothelial isoforms (nNOS and eNOS) occurred and if a correlation exists between uncoupling and the monomer/dimer equilibrium. We determined the rates of coupled/uncoupled catalysis by measuring NADPH oxidation spectrophotometrically at 340 nm and citrulline synthesis as the formation of [3H]-citrulline from [3H]-Arg. The monomer/dimer equilibrium was determined by FPLC and, for comparison, by low-temperature polyacrylamide gel electrophoresis. Uncoupling occurred in the absence of Arg and/or BH4, but not in the absence of Ca2+ or calmodulin (CaM). Since omission of Ca2+/CaM will completely block heme reduction while still allowing substantial FMN reduction, this argues against uncoupling by the reductase domain. In the presence of heme-directed NOS inhibitors uncoupling occurred to the extent that these compound allowed heme reduction, again arguing in favor of uncoupling at the heme. The monomer/dimer equilibrium showed no correlation with uncoupling. We conclude that uncoupling by BH4 deficiency takes place exclusively at the heme, with virtually no contribution from the flavins and no role for NOS monomerization.
Collapse
Affiliation(s)
- Verena Gebhart
- Department of Pharmacology and Toxicology Institute of Pharmaceutical Sciences, Karl-Franzens-University Graz, A-8010, Graz, Austria
| | - Katja Reiß
- Department of Pharmacology and Toxicology Institute of Pharmaceutical Sciences, Karl-Franzens-University Graz, A-8010, Graz, Austria
| | - Alexander Kollau
- Department of Pharmacology and Toxicology Institute of Pharmaceutical Sciences, Karl-Franzens-University Graz, A-8010, Graz, Austria
| | - Bernd Mayer
- Department of Pharmacology and Toxicology Institute of Pharmaceutical Sciences, Karl-Franzens-University Graz, A-8010, Graz, Austria
| | - Antonius C F Gorren
- Department of Pharmacology and Toxicology Institute of Pharmaceutical Sciences, Karl-Franzens-University Graz, A-8010, Graz, Austria.
| |
Collapse
|
28
|
Müller ME, Vikstrom S, König M, Schlichting R, Zarfl C, Zwiener C, Escher BI. Mitochondrial Toxicity of Selected Micropollutants, Their Mixtures, and Surface Water Samples Measured by the Oxygen Consumption Rate in Cells. Environ Toxicol Chem 2019; 38:1000-1011. [PMID: 30779373 DOI: 10.1002/etc.4396] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Revised: 02/11/2019] [Accepted: 02/13/2019] [Indexed: 06/09/2023]
Abstract
Some environmental pollutants impair mitochondria, which are of vital importance as energy factories in eukaryotic cells. Mitochondrial toxicity was quantified by measuring the change of the oxygen consumption rate (OCR) of HepG2 cells with the Agilent Seahorse XFe 96 Analyzer. Various mechanisms of mitochondrial toxicity, including inhibition of the electron transport chain or adenosine triphosphate (ATP) synthase as well as uncoupling of oxidative phosphorylation, were differentiated by dosing the sample in parallel with reference compounds following the OCR over time. These time-OCR traces were used to derive effect concentrations for 10% inhibition of the electron transport chain or 10% of uncoupling. The low effect level of 10% was necessary because environmental mixtures contain thousands of chemicals; only few of them interfere with mitochondria, but the others cause cytotoxicity. The OCR bioassay was validated with environmental pollutants of known mechanism of mitochondrial toxicity. Binary mixtures of uncouplers or inhibitors acted according to the mixture model of concentration addition. Uncoupling and/or inhibitory effects were detected in extracts of river water samples without apparent cytotoxicity. Uncoupling effects could only be quantified in water samples if inhibitory effects occurred at lower concentrations because no uncoupling can be detected without an appreciable membrane potential built up. The OCR bioassay can thus complement chemical analysis and in vitro bioassays for monitoring micropollutants in water. Environ Toxicol Chem 2019;00:1-12. © 2019 SETAC.
Collapse
Affiliation(s)
- Maximilian E Müller
- Eberhard Karls University of Tübingen, Center for Applied Geoscience, Tübingen, Germany
| | | | - Maria König
- UFZ-Helmholtz Centre for Environmental Research, Leipzig, Germany
| | - Rita Schlichting
- UFZ-Helmholtz Centre for Environmental Research, Leipzig, Germany
| | - Christiane Zarfl
- Eberhard Karls University of Tübingen, Center for Applied Geoscience, Tübingen, Germany
| | - Christian Zwiener
- Eberhard Karls University of Tübingen, Center for Applied Geoscience, Tübingen, Germany
| | - Beate I Escher
- Eberhard Karls University of Tübingen, Center for Applied Geoscience, Tübingen, Germany
- UFZ-Helmholtz Centre for Environmental Research, Leipzig, Germany
| |
Collapse
|
29
|
Abstract
The heart and blood vessels are constantly interfering with each other in a closed system. For a few decades, the concept of ventricular-arterial coupling has been considered as a key pathogenesis of heart failure especially in heart failure with preserved ejection fraction.
Collapse
|
30
|
Nicholatos JW, Robinette TM, Tata SVP, Yordy JD, Francisco AB, Platov M, Yeh TK, Ilkayeva OR, Huynh FK, Dokukin M, Volkov D, Weinstein MA, Boyko AR, Miller RA, Sokolov I, Hirschey MD, Libert S. Cellular energetics and mitochondrial uncoupling in canine aging. GeroScience 2019; 41:229-242. [PMID: 30937823 DOI: 10.1007/s11357-019-00062-6] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2018] [Accepted: 03/18/2019] [Indexed: 01/02/2023] Open
Abstract
The first domesticated companion animal, the dog, is currently represented by over 190 unique breeds. Across these numerous breeds, dogs have exceptional variation in lifespan (inversely correlated with body size), presenting an opportunity to discover longevity-determining traits. We performed a genome-wide association study on 4169 canines representing 110 breeds and identified novel candidate regulators of longevity. Interestingly, known functions within the identified genes included control of coat phenotypes such as hair length, as well as mitochondrial properties, suggesting that thermoregulation and mitochondrial bioenergetics play a role in lifespan variation. Using primary dermal fibroblasts, we investigated mitochondrial properties of short-lived (large) and long-lived (small) dog breeds. We found that cells from long-lived breeds have more uncoupled mitochondria, less electron escape, greater respiration, and capacity for respiration. Moreover, our data suggest that long-lived breeds have higher rates of catabolism and β-oxidation, likely to meet elevated respiration and electron demand of their uncoupled mitochondria. Conversely, cells of short-lived (large) breeds may accumulate amino acids and fatty acid derivatives, which are likely used for biosynthesis and growth. We hypothesize that the uncoupled metabolic profile of long-lived breeds likely stems from their smaller size, reduced volume-to-surface area ratio, and therefore a greater need for thermogenesis. The uncoupled energetics of long-lived breeds lowers reactive oxygen species levels, promotes cellular stress tolerance, and may even prevent stiffening of the actin cytoskeleton. We propose that these cellular characteristics delay tissue dysfunction, disease, and death in long-lived dog breeds, contributing to canine aging diversity.
Collapse
Affiliation(s)
- Justin W Nicholatos
- Department of Biomedical Sciences, Cornell University, Ithaca, NY, 14850, USA.
| | - Timothy M Robinette
- Department of Biomedical Sciences, Cornell University, Ithaca, NY, 14850, USA
| | - Saurabh V P Tata
- Department of Biomedical Sciences, Cornell University, Ithaca, NY, 14850, USA
| | - Jennifer D Yordy
- Department of Biomedical Sciences, Cornell University, Ithaca, NY, 14850, USA
| | - Adam B Francisco
- Department of Biomedical Sciences, Cornell University, Ithaca, NY, 14850, USA
| | - Michael Platov
- Department of Biomedical Sciences, Cornell University, Ithaca, NY, 14850, USA
| | - Tiffany K Yeh
- Department of Biomedical Sciences, Cornell University, Ithaca, NY, 14850, USA
| | - Olga R Ilkayeva
- Duke Molecular Physiology Institute and Sarah W. Stedman Nutrition and Metabolism Center, Duke University Medical Center, Durham, NC, 27701, USA
| | - Frank K Huynh
- Duke Molecular Physiology Institute and Sarah W. Stedman Nutrition and Metabolism Center, Duke University Medical Center, Durham, NC, 27701, USA
| | - Maxim Dokukin
- Department of Mechanical Engineering, Tufts University, Medford, MA, 02155, USA
| | - Dmytro Volkov
- Department of Mechanical Engineering, Tufts University, Medford, MA, 02155, USA
| | - Michael A Weinstein
- Department of Biomedical Engineering, Tufts University, Medford, MA, 02155, USA
| | - Adam R Boyko
- Department of Biomedical Sciences, Cornell University, Ithaca, NY, 14850, USA
| | - Richard A Miller
- Department of Pathology, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Igor Sokolov
- Department of Mechanical Engineering, Tufts University, Medford, MA, 02155, USA.,Department of Biomedical Engineering, Tufts University, Medford, MA, 02155, USA
| | - Matthew D Hirschey
- Duke Molecular Physiology Institute and Sarah W. Stedman Nutrition and Metabolism Center, Duke University Medical Center, Durham, NC, 27701, USA
| | - Sergiy Libert
- Department of Biomedical Sciences, Cornell University, Ithaca, NY, 14850, USA.
| |
Collapse
|
31
|
Zabeau L, Wauman J, Dam J, Van Lint S, Burg E, De Geest J, Rogge E, Silva A, Jockers R, Tavernier J. A novel leptin receptor antagonist uncouples leptin's metabolic and immune functions. Cell Mol Life Sci 2019; 76:1201-14. [PMID: 30659329 DOI: 10.1007/s00018-019-03004-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Revised: 12/28/2018] [Accepted: 01/02/2019] [Indexed: 12/19/2022]
Abstract
Leptin links body energy stores to high energy demanding processes like reproduction and immunity. Based on leptin's role in autoimmune diseases and cancer, several leptin and leptin receptor (LR) antagonists have been developed, but these intrinsically lead to unwanted weight gain. Here, we report on the uncoupling of leptin's metabolic and immune functions based on the cross talk with the epidermal growth factor receptor (EGFR). We show that both receptors spontaneously interact and, remarkably, that this complex can partially overrule the lack of LR activation by a leptin antagonistic mutein. Moreover, this leptin mutant induces EGFR phosphorylation comparable to wild-type leptin. Exploiting this non-canonical leptin signalling pathway, we identified a camelid single-domain antibody that selectively inhibits this LR-EGFR cross talk without interfering with homotypic LR signalling. Administration in vivo showed that this single-domain antibody did not interfere with leptin's metabolic functions, but could reverse the leptin-driven protection against starvation-induced thymic and splenic atrophy. These findings offer new opportunities for the design and clinical application of selective leptin and LR antagonists that avoid unwanted metabolic side effects.
Collapse
|
32
|
Igamberdiev AU, Kleczkowski LA. Thermodynamic buffering, stable non-equilibrium and establishment of the computable structure of plant metabolism. Prog Biophys Mol Biol 2019; 146:23-36. [PMID: 30444975 DOI: 10.1016/j.pbiomolbio.2018.11.005] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 09/12/2018] [Revised: 11/02/2018] [Accepted: 11/12/2018] [Indexed: 01/09/2023]
Abstract
The equilibria of coenzyme nucleotides and substrates established in plant cells generate simple rules that govern the plant metabolome and provide optimal conditions for the non-equilibrium fluxes of major metabolic processes such as ATP synthesis, CO2 fixation, and mitochondrial respiration. Fast and abundant enzymes, such as adenylate kinase, carbonic anhydrase or malate dehydrogenase, provide constant substrate flux for these processes. These "buffering" enzymes follow the Michaelis-Menten (MM) kinetics and operate near equilibrium. The non-equilibrium "engine" enzymes, such as ATP synthase, Rubisco or the respiratory complexes, follow the modified version of MM kinetics due to their high concentration and low concentration of their substrates. The equilibrium reactions serve as control gates for the non-equilibrium flux through the engine enzymes establishing the balance of the fluxes of load and consumption of metabolic components. Under the coordinated operation of buffering and engine enzymes, the concentrations of free and Mg-bound adenylates and of free Mg2+ are set, serving as feedback signals from the adenylate metabolome. Those are linked to various cell energetics parameters, including membrane potentials. Also, internal levels of reduced and oxidized pyridine nucleotides are established in the coordinated operation of malate dehydrogenase and respiratory components, with proton concentration as a feedback from pyridine nucleotide pools. Non-coupled pathways of respiration serve to equilibrate the levels of pyridine nucleotides, adenylates, and as a pH stat. This stable non-equilibrium organizes the fluxes of energy spatially and temporally, controlling the rates of major metabolic fluxes that follow thermodynamically and kinetically defined computational principles.
Collapse
|
33
|
Podgurskaya AD, Tsvelaya VA, Frolova SR, Kalita IY, Kudryashova NN, Agladze KI. Effect of heptanol and ethanol on excitation wave propagation in a neonatal rat ventricular myocyte monolayer. Toxicol In Vitro 2018; 51:136-144. [PMID: 29778719 DOI: 10.1016/j.tiv.2018.05.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2017] [Revised: 05/11/2018] [Accepted: 05/15/2018] [Indexed: 11/24/2022]
Abstract
In this work, the action of heptanol and ethanol was investigated in a two-dimensional (2D) model of cardiac tissue: the neonatal rat ventricular myocyte monolayer. Heptanol is known in electrophysiology as a gap junction uncoupler but may also inhibit voltage-gated ionic channels. Ethanol is often associated with the occurrence of arrhythmias. These substances influence sodium, calcium, and potassium channels, but the complete mechanism of action of heptanol and ethanol remains unknown. The optical mapping method was used to measure conduction velocities (CVs) in concentrations of 0.05-1.8 mM heptanol and 17-1342 mM ethanol. Heptanol was shown to slow the excitation wave significantly, and a mechanism that involves a simultaneous action on cell coupling and activation threshold was suggested. Whole-cell patch-clamp experiments showed inhibition of sodium and calcium currents at a concentration of 0.5 mM heptanol. Computer modeling was used to estimate the relative contribution of the cell uncoupling and activation threshold increase caused by heptanol. Unlike heptanol, ethanol slightly influenced the CV at clinically relevant concentrations. Additionally, the critical concentrations for re-entry formation in ethanol were determined.
Collapse
Affiliation(s)
- A D Podgurskaya
- The Laboratory of the Biophysics of Excitable Systems, Moscow Institute of Physics and Technology (State University), 9 Institutskiy per., Dolgoprudny, Moscow Region 141701, Russian Federation
| | - V A Tsvelaya
- The Laboratory of the Biophysics of Excitable Systems, Moscow Institute of Physics and Technology (State University), 9 Institutskiy per., Dolgoprudny, Moscow Region 141701, Russian Federation
| | - S R Frolova
- The Laboratory of the Biophysics of Excitable Systems, Moscow Institute of Physics and Technology (State University), 9 Institutskiy per., Dolgoprudny, Moscow Region 141701, Russian Federation
| | - I Y Kalita
- The Laboratory of the Biophysics of Excitable Systems, Moscow Institute of Physics and Technology (State University), 9 Institutskiy per., Dolgoprudny, Moscow Region 141701, Russian Federation
| | - N N Kudryashova
- The Laboratory of the Biophysics of Excitable Systems, Moscow Institute of Physics and Technology (State University), 9 Institutskiy per., Dolgoprudny, Moscow Region 141701, Russian Federation; Department of Physics and Astronomy, Ghent University, B-9000 Ghent, Belgium
| | - K I Agladze
- The Laboratory of the Biophysics of Excitable Systems, Moscow Institute of Physics and Technology (State University), 9 Institutskiy per., Dolgoprudny, Moscow Region 141701, Russian Federation.
| |
Collapse
|
34
|
Doerrier C, Garcia-Souza LF, Krumschnabel G, Wohlfarter Y, Mészáros AT, Gnaiger E. High-Resolution FluoRespirometry and OXPHOS Protocols for Human Cells, Permeabilized Fibers from Small Biopsies of Muscle, and Isolated Mitochondria. Methods Mol Biol 2018; 1782:31-70. [PMID: 29850993 DOI: 10.1007/978-1-4939-7831-1_3] [Citation(s) in RCA: 123] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Protocols for High-Resolution FluoRespirometry of intact cells, permeabilized cells, permeabilized muscle fibers, isolated mitochondria, and tissue homogenates offer sensitive diagnostic tests of integrated mitochondrial function using standard cell culture techniques, small needle biopsies of muscle, and mitochondrial preparation methods. Multiple substrate-uncoupler-inhibitor titration (SUIT) protocols for analysis of oxidative phosphorylation (OXPHOS) improve our understanding of mitochondrial respiratory control and the pathophysiology of mitochondrial diseases. Respiratory states are defined in functional terms to account for the network of metabolic interactions in complex SUIT protocols with stepwise modulation of coupling control and electron transfer pathway states. A regulated degree of intrinsic uncoupling is a hallmark of oxidative phosphorylation, whereas pathological and toxicological dyscoupling is evaluated as a mitochondrial defect. The noncoupled state of maximum respiration is experimentally induced by titration of established uncouplers (CCCP, FCCP, DNP) to collapse the protonmotive force across the mitochondrial inner membrane and measure the electron transfer (ET) capacity (open-circuit operation of respiration). Intrinsic uncoupling and dyscoupling are evaluated as the flux control ratio between non-phosphorylating LEAK respiration (electron flow coupled to proton pumping to compensate for proton leaks) and ET capacity. If OXPHOS capacity (maximally ADP-stimulated O2 flux) is less than ET capacity, the phosphorylation pathway contributes to flux control. Physiological substrate combinations supporting the NADH and succinate pathway are required to reconstitute tricarboxylic acid cycle function. This supports maximum ET and OXPHOS capacities, due to the additive effect of multiple electron supply pathways converging at the Q-junction. ET pathways with electron entry separately through NADH (pyruvate and malate or glutamate and malate) or succinate (succinate and rotenone) restrict ET capacity and artificially enhance flux control upstream of the Q-cycle, providing diagnostic information on specific ET-pathway branches. O2 concentration is maintained above air saturation in protocols with permeabilized muscle fibers to avoid experimental O2 limitation of respiration. Standardized two-point calibration of the polarographic oxygen sensor (static sensor calibration), calibration of the sensor response time (dynamic sensor calibration), and evaluation of instrumental background O2 flux (systemic flux compensation) provide the unique experimental basis for high accuracy of quantitative results and quality control in High-Resolution FluoRespirometry.
Collapse
|
35
|
Morlock LK, Böttcher D, Bornscheuer UT. Simultaneous detection of NADPH consumption and H 2O 2 production using the Ampliflu™ Red assay for screening of P450 activities and uncoupling. Appl Microbiol Biotechnol 2018; 102:985-94. [PMID: 29150709 DOI: 10.1007/s00253-017-8636-3] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Revised: 11/06/2017] [Accepted: 11/07/2017] [Indexed: 10/18/2022]
Abstract
Cytochrome P450s belong to a large and diverse group of heme-containing enzymes. These monooxygenases catalyze the incorporation of a single atom of molecular oxygen into their substrate. In contrast to most other enzymes, the activity of P450 enzymes is not only dependent on substrate and cofactor availability and reaction conditions, but also depends on the coupling efficiency of the catalytic cycle itself. Through the electron transfer from NAD(P)H to the heme-center of the P450, the enzyme becomes activated and binds oxygen. The thereby generated iron-oxygen complex undergoes multiple reductive steps forming different activated oxygen species. These intermediates can decay easily, releasing the reactive oxygen species superoxide anion and hydrogen peroxide (H2O2), which can also be further reduced to water. This so-called uncoupling of the reaction cycle drains electrons from the system, which consequently does not lead to the desired product, but merely H2O2 formation with stoichiometric consumption of NAD(P)H. Hence, measuring NAD(P)H consumption only can lead to an overestimation of substrate conversion. To measure this uncoupling, we herein report a microtiter plate-based assay for the simultaneous quantification of hydrogen peroxide formation and NAD(P)H consumption using Ampliflu™ Red as reporter. This was exemplified for the P450 monooxygenase from Bacillus megaterium (P450 BM3) and five mutants, using different substrates. We demonstrate the applicability of the assay, which provides a versatile basis for a high-throughput preliminary screening of P450 enzyme libraries without the need for GC or HPLC analysis and clear indication of the extent of hydrogen peroxide uncoupling.
Collapse
|
36
|
Grünig D, Felser A, Bouitbir J, Krähenbühl S. The catechol-O-methyltransferase inhibitors tolcapone and entacapone uncouple and inhibit the mitochondrial respiratory chain in HepaRG cells. Toxicol In Vitro 2017; 42:337-347. [PMID: 28526448 DOI: 10.1016/j.tiv.2017.05.013] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2017] [Revised: 04/26/2017] [Accepted: 05/15/2017] [Indexed: 01/08/2023]
Abstract
The catechol-O-methyltransferase inhibitor tolcapone causes hepatotoxicity and mitochondrial damage in animal models. We studied the interaction of tolcapone with mitochondrial respiration in comparison to entacapone in different experimental models. In HepaRG cells (human cell-line), tolcapone decreased the ATP content (estimated IC50 100±15μM) and was cytotoxic (estimated IC50 333±45μM), whereas entacapone caused no cytotoxicity and no ATP depletion up to 200μM. Cytochrome P450 induction did not increase the toxicity of the compounds. In HepaRG cells, tolcapone (not entacapone) inhibited maximal complex I- and complex II-linked oxygen consumption. In intact mouse liver mitochondria, tolcapone stimulated state 2 complex II-linked respiration and both compounds inhibited state 3 respiration of complex IV. Mitochondrial uncoupling was confirmed for both compounds by stimulation of complex I-linked respiration in the presence of oligomycin. Inhibition of complex I, II and IV for tolcapone and of complex I and IV for entacapone was directly demonstrated in disrupted mouse liver mitochondria. In HepaRG cells, tolcapone-induced inhibition of mitochondrial respiration was associated with increased lactate and ROS production and hepatocyte necrosis. In conclusion, both compounds uncouple oxidative phosphorylation and inhibit mitochondrial enzyme complexes. Tolcapone is a more potent mitochondrial toxicant than entacapone. Mitochondrial toxicity is a possible mechanism for tolcapone-associated hepatotoxicity.
Collapse
Affiliation(s)
- David Grünig
- Division of Clinical Pharmacology & Toxicology, University Hospital Basel, Switzerland; Department of Biomedicine, University of Basel, Switzerland
| | - Andrea Felser
- Division of Clinical Pharmacology & Toxicology, University Hospital Basel, Switzerland; Department of Biomedicine, University of Basel, Switzerland
| | - Jamal Bouitbir
- Division of Clinical Pharmacology & Toxicology, University Hospital Basel, Switzerland; Department of Biomedicine, University of Basel, Switzerland; Swiss Center of Applied Human Toxicology (SCAHT), Switzerland
| | - Stephan Krähenbühl
- Division of Clinical Pharmacology & Toxicology, University Hospital Basel, Switzerland; Department of Biomedicine, University of Basel, Switzerland; Swiss Center of Applied Human Toxicology (SCAHT), Switzerland.
| |
Collapse
|
37
|
Marín-Prida J, Pardo Andreu GL, Rossignoli CP, Durruthy MG, Rodríguez EO, Reyes YV, Acosta RF, Uyemura SA, Alberici LC. The cytotoxic effects of VE-3N, a novel 1,4-dihydropyridine derivative, involve the mitochondrial bioenergetic disruption via uncoupling mechanisms. Toxicol In Vitro 2017; 42:21-30. [PMID: 28363597 DOI: 10.1016/j.tiv.2017.03.011] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2016] [Revised: 03/03/2017] [Accepted: 03/27/2017] [Indexed: 01/21/2023]
Abstract
Several 1,4-dihydropyridine derivatives overcome the multidrug resistance in tumors, but their intrinsic cytotoxic mechanisms remain unclear. Here we addressed if mitochondria are involved in the cytotoxicity of the novel 1,4-dihydropyridine derivative VE-3N [ethyl 6-chloro-5-formyl-2-methyl-4-(3-nitrophenyl)-1,4-dihydropyridine-3-carboxylate] towards cancer cells by employing hepatic carcinoma (HepG2) cells and isolated rat liver mitochondria. In HepG2 cells, VE-3N induced mitochondrial membrane potential dissipation, ATP depletion, annexin V/propidium iodide double labeling, and Hoechst staining; events indicating apoptosis induction. In isolated rat liver mitochondria, VE-3N promoted mitochondrial uncoupling by exerting protonophoric actions and by increasing membrane fluidity. Mitochondrial uncoupling was evidenced by an increase in resting respiration, dissipation of mitochondrial membrane potential, inhibition of Ca2+ uptake, stimulation of Ca2+ release, decrease in ATP synthesis, and swelling of valinomycin-treated organelles in hyposmotic potassium acetate media. Furthermore, uncoupling concentrations of VE-3N in the presence of Ca2+ plus ruthenium red induced the mitochondrial permeability transition process. These results indicate that mitochondrial uncoupling is potentially involved in the VE-3N cytotoxic actions towards HepG2 cells. Considering that hepatocellular carcinoma is the most common form of liver cancer, our findings may open a new avenue for the development of VE-3N-based cancer therapies, and help to unravel the cytotoxic mechanisms of 1,4-dihydropyridines towards cancer cells.
Collapse
Affiliation(s)
- Javier Marín-Prida
- Center for Research and Biological Evaluations, Institute of Pharmacy and Food, University of Havana, 222 St. # 2317, La Coronela, La Lisa, Havana, Cuba
| | - Gilberto L Pardo Andreu
- Center for Research and Biological Evaluations, Institute of Pharmacy and Food, University of Havana, 222 St. # 2317, La Coronela, La Lisa, Havana, Cuba.
| | - Camila Pederiva Rossignoli
- Department of Physics and Chemistry, School of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo, Av. Café s/n, 14040-903, Ribeirão Preto, São Paulo, Brazil
| | - Michael González Durruthy
- Center for Research and Biological Evaluations, Institute of Pharmacy and Food, University of Havana, 222 St. # 2317, La Coronela, La Lisa, Havana, Cuba
| | - Estael Ochoa Rodríguez
- Laboratory of Organic Synthesis, Faculty of Chemistry, University of Havana, Zapata st./G and Carlitos Aguirre, Vedado Plaza de la Revolución, PO 10400, Havana, Cuba
| | - Yamila Verdecia Reyes
- Laboratory of Organic Synthesis, Faculty of Chemistry, University of Havana, Zapata st./G and Carlitos Aguirre, Vedado Plaza de la Revolución, PO 10400, Havana, Cuba
| | - Roberto Fernández Acosta
- Department of Pharmacy, Institute of Pharmacy and Food, University of Havana, 222 St. # 2317, La Coronela, La Lisa, Havana, Cuba
| | - Sergio A Uyemura
- Department of Clinical Analyses, Toxicology and Food Sciences, School of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo, Av. Café s/n, 14040-903 Ribeirão Preto, São Paulo, Brazil
| | - Luciane C Alberici
- Department of Physics and Chemistry, School of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo, Av. Café s/n, 14040-903, Ribeirão Preto, São Paulo, Brazil
| |
Collapse
|
38
|
Wilson JL, Bouillaud F, Almeida AS, Vieira HL, Ouidja MO, Dubois-Randé JL, Foresti R, Motterlini R. Carbon monoxide reverses the metabolic adaptation of microglia cells to an inflammatory stimulus. Free Radic Biol Med 2017; 104:311-323. [PMID: 28108277 DOI: 10.1016/j.freeradbiomed.2017.01.022] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/04/2016] [Revised: 01/02/2017] [Accepted: 01/15/2017] [Indexed: 12/11/2022]
Abstract
Microglia fulfill important immunological functions in the brain by responding to pathological stresses and modulating their activities according to pro- or anti-inflammatory stimuli. Recent evidence indicates that changes in metabolism accompany the switch in microglia activation state, favoring glycolysis over oxidative phosphorylation when cells exhibit a pro-inflammatory phenotype. Carbon monoxide (CO), a byproduct of heme breakdown by heme oxygenase, exerts anti-inflammatory action and affects mitochondrial function in cells and tissues. In the present study, we analyzed the metabolic profile of BV2 and primary mouse microglia exposed to the CO-releasing molecules CORM-401 and CORM-A1 and investigated whether CO affects the metabolic adaptation of cells to the inflammatory stimulus lipopolysaccharide (LPS). Microglia respiration and glycolysis were measured using an Extracellular Flux Analyzer to provide a real-time bioenergetic assessment, and biochemical parameters were evaluated to define the metabolic status of the cells under normal or inflammatory conditions. We show that CO prevents LPS-induced depression of microglia respiration and reduction in ATP levels while altering the early expression of inflammatory markers, suggesting the metabolic changes induced by CO are associated with control of inflammation. CO alone affects microglia respiration depending on the concentration, as low levels increase oxygen consumption while higher amounts inhibit respiration. Increased oxygen consumption was attributed to an uncoupling activity observed in cells, at the molecular level (respiratory complex activities) and during challenge with LPS. Thus, application of CO is a potential countermeasure to reverse the metabolic changes that occur during microglia inflammation and in turn modulate their inflammatory profile.
Collapse
Affiliation(s)
- Jayne Louise Wilson
- Inserm U955, Equipe 12, Créteil 94000, France; University Paris-Est, Faculty of Medicine, Créteil 94000, France.
| | - Frédéric Bouillaud
- Institut Cochin, Inserm U1016-CNRS UMR8104-Université Paris Descartes, Paris, France.
| | - Ana S Almeida
- CEDOC, NOVA Medical School, Universidade Nova de Lisboa, 1169-056 Lisboa, Portugal; Instituto de Tecnologia Química e Biológica (ITQB), Universidade Nova de Lisboa, Apartado 127, 2781-901 Oeiras, Portugal; Instituto de Biologia Experimental e Tecnológica (iBET), Apartado 12, 2781-901 Oeiras, Portugal.
| | - Helena L Vieira
- CEDOC, NOVA Medical School, Universidade Nova de Lisboa, 1169-056 Lisboa, Portugal; Instituto de Biologia Experimental e Tecnológica (iBET), Apartado 12, 2781-901 Oeiras, Portugal.
| | - Mohand Ouidir Ouidja
- Laboratoire de Recherche sur la Croissance et la Regénération Tissulaires (CRRET), UPRESA CNRS 7053, Université Paris XII-Val de Marne, 94010 Créteil, France.
| | - Jean-Luc Dubois-Randé
- AP-HP, Hôpital Henri Mondor-A, Chenevier,Chenevier, Service Hospitalier, Créteil, France.
| | - Roberta Foresti
- Inserm U955, Equipe 12, Créteil 94000, France; University Paris-Est, Faculty of Medicine, Créteil 94000, France.
| | - Roberto Motterlini
- Inserm U955, Equipe 12, Créteil 94000, France; University Paris-Est, Faculty of Medicine, Créteil 94000, France.
| |
Collapse
|
39
|
Sun J, Comeau JF, Baenziger JE. Probing the structure of the uncoupled nicotinic acetylcholine receptor. Biochim Biophys Acta Biomembr 2016; 1859:146-154. [PMID: 27871840 DOI: 10.1016/j.bbamem.2016.11.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2016] [Revised: 11/10/2016] [Accepted: 11/17/2016] [Indexed: 10/20/2022]
Abstract
In the absence of activating anionic lipids and cholesterol, the nicotinic acetylcholine receptor (nAChR) from Torpedo adopts an uncoupled conformation that does not usually gate open in response to agonist. The uncoupled conformation binds both agonists and non-competitive channel blockers with a lower affinity than the desensitized state, consistent with both the extracellular agonist-binding and transmembrane channel-gating domains individually adopting resting-state like conformations. To test this hypothesis, we characterized the binding of the agonist, acetylcholine, and two fluorescent channel blockers, ethidium and crystal violet, to resting, desensitized and uncoupled nAChRs in reconstituted membranes. The measured Kd for acetylcholine binding to the uncoupled nAChR is similar to that for the resting state, confirming that the agonist binding site adopts a resting-state like conformation. Although both ethidium and crystal violet bind to the resting and desensitized channel pores with distinct affinities, no binding of either probe was detected to the uncoupled nAChR. Our data suggest that the transmembrane domain of the uncoupled nAChR adopts a conformation distinct from that of the resting and desensitized states. The lack of binding is consistent with a more constricted channel pore, possibly along the lines of what is observed in crystal structures of the prokaryotic homolog, ELIC.
Collapse
Affiliation(s)
- Jiayin Sun
- Department of Biochemistry, Microbiology, and Immunology, University of Ottawa, 451 Smyth Rd, K1H 8M5 Ottawa, ON, Canada
| | - J Frederique Comeau
- Department of Biochemistry, Microbiology, and Immunology, University of Ottawa, 451 Smyth Rd, K1H 8M5 Ottawa, ON, Canada
| | - John E Baenziger
- Department of Biochemistry, Microbiology, and Immunology, University of Ottawa, 451 Smyth Rd, K1H 8M5 Ottawa, ON, Canada.
| |
Collapse
|
40
|
Abstract
Adaptive thermogenesis regulates core body temperature, controls fat deposition, and contributes strongly to the overall energy balance. This process occurs in brown fat and requires uncoupling protein 1 (UCP1), an integral protein of the inner mitochondrial membrane. Classic biochemical studies revealed the general principle of adaptive thermogenesis: in the presence of long-chain fatty acids (FA), UCP1 increases the permeability of the inner mitochondrial membrane for H+, which makes brown fat mitochondria produce heat rather than ATP. However, the exact mechanism by which UCP1 increases the membrane H+ conductance in a FA-dependent manner has remained a fundamental unresolved question. Recently, the patch-clamp technique was successfully applied to the inner mitochondrial membrane of brown fat to directly characterize the H+ currents carried by UCP1. Based on the patch-clamp data, a new model of UCP1 operation was proposed. In brief, FA anions are transport substrates of UCP1, and UCP1 operates as an unusual FA anion/H+ symporter. Interestingly, in contrast to short-chain FA anions, long-chain FA anions cannot easily dissociate from UCP1 due to strong hydrophobic interactions established by their carbon tails, and a single long-chain FA participates in many H+ transport cycles. Therefore, in the presence of long-chain FA, endogenous activators of brown fat thermogenesis, UCP1 effectively operates as an H+ uniport. In addition to their transport function, long-chain FA competitively remove tonic inhibition of UCP1 by cytosolic purine nucleotides, thus enabling activation of the thermogenic H+ leak through UCP1 under physiological conditions.
Collapse
Affiliation(s)
- Ambre M Bertholet
- Department of Physiology, University of California San Francisco, UCSF Mail Code 2140, Genentech Hall Room N272F, 600 16th Street, San Francisco, CA 94158, USA
| | - Yuriy Kirichok
- Department of Physiology, University of California San Francisco, UCSF Mail Code 2140, Genentech Hall Room N272F, 600 16th Street, San Francisco, CA 94158, USA.
| |
Collapse
|
41
|
D'Alessandro M, Turina P, Melandri BA, Dunn SD. Modulation of coupling in the Escherichia coli ATP synthase by ADP and P i: Role of the ε subunit C-terminal domain. Biochim Biophys Acta Bioenerg 2016; 1858:34-44. [PMID: 27751906 DOI: 10.1016/j.bbabio.2016.10.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 12/31/2015] [Revised: 08/06/2016] [Accepted: 10/13/2016] [Indexed: 01/28/2023]
Abstract
The ε-subunit of ATP-synthase is an endogenous inhibitor of the hydrolysis activity of the complex and its α-helical C-terminal domain (εCTD) undergoes drastic changes among at least two different conformations. Even though this domain is not essential for ATP synthesis activity, there is evidence for its involvement in the coupling mechanism of the pump. Recently, it was proposed that coupling of the ATP synthase can vary as a function of ADP and Pi concentration. In the present work, we have explored the possible role of the εCTD in this ADP- and Pi-dependent coupling, by examining an εCTD-lacking mutant of Escherichia coli. We show that the loss of Pi-dependent coupling can be observed also in the εCTD-less mutant, but the effects of Pi on both proton pumping and ATP hydrolysis were much weaker in the mutant than in the wild-type. We also show that the εCTD strongly influences the binding of ADP to a very tight binding site (half-maximal effect≈1nM); binding at this site induces higher coupling in EFOF1 and increases responses to Pi. It is proposed that one physiological role of the εCTD is to regulate the kinetics and affinity of ADP/Pi binding, promoting ADP/Pi-dependent coupling.
Collapse
Affiliation(s)
- M D'Alessandro
- Department of Biology, Laboratory of Biochemistry and Biophysics, University of Bologna, Via Irnerio 42, 40126 Bologna, Italy
| | - P Turina
- Department of Biology, Laboratory of Biochemistry and Biophysics, University of Bologna, Via Irnerio 42, 40126 Bologna, Italy.
| | - B A Melandri
- Department of Biology, Laboratory of Biochemistry and Biophysics, University of Bologna, Via Irnerio 42, 40126 Bologna, Italy
| | - S D Dunn
- Department of Biochemistry, University of Western Ontario, London, Ontario N6A 5C1, Canada
| |
Collapse
|
42
|
Boitz JM, Jardim A, Ullman B. GMP reductase and genetic uncoupling of adenylate and guanylate metabolism in Leishmania donovani parasites. Mol Biochem Parasitol 2016; 208:74-83. [PMID: 27343371 DOI: 10.1016/j.molbiopara.2016.06.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2016] [Revised: 06/20/2016] [Accepted: 06/21/2016] [Indexed: 11/26/2022]
Abstract
Purine acquisition is an essential nutritional process for Leishmania. Although purine salvage into adenylate nucleotides has been investigated in detail, little attention has been focused on the guanylate branch of the purine pathway. To characterize guanylate nucleotide metabolism in Leishmania and create a cell culture model in which the pathways for adenylate and guanylate nucleotide synthesis can be genetically uncoupled for functional studies in intact cells, we created and characterized null mutants of L. donovani that were deficient in either GMP reductase alone (Δgmpr) or in both GMP reductase and its paralog IMP dehydrogenase (Δgmpr/Δimpdh). Whereas wild type parasites were capable of utilizing virtually any purine nucleobase/nucleoside, the Δgmpr and Δgmpr/Δimpdh null lines exhibited highly restricted growth phenotypes. The Δgmpr single mutant could not grow in xanthine, guanine, or their corresponding nucleosides, while no purine on its own could support the growth of Δgmpr/Δimpdh cells. Permissive growth conditions for the Δgmpr/Δimpdh necessitated both xanthine, guanine, or the corresponding nucleosides, and additionally, a second purine that could serve as a source for adenylate nucleotide synthesis. Interestingly, GMPR, like its paralog IMPDH, is compartmentalized to the leishmanial glycosome, a process mediated by its COOH-terminal peroxisomal targeting signal. The restricted growth phenotypes displayed by the L. donovani Δgmpr and Δgmpr/Δimpdh null mutants confirms the importance of GMPR in the purine interconversion processes of this parasite.
Collapse
Affiliation(s)
- Jan M Boitz
- Department of Biochemistry and Molecular Biology, Oregon Health & Science University, 3181 SW Sam Jackson Park Rd., Mail Code L224, Portland, OR 97239, USA
| | - Armando Jardim
- Institute of Parasitology and Centre for Host-Parasite Interactions, Macdonald Campus of McGill University, 21 111 Lakeshore Road, Ste-Anne-de-Bellevue, Quebec, H9X3V9, Canada
| | - Buddy Ullman
- Department of Biochemistry and Molecular Biology, Oregon Health & Science University, 3181 SW Sam Jackson Park Rd., Mail Code L224, Portland, OR 97239, USA.
| |
Collapse
|
43
|
Cho YS, Lee JH, Jung KH, Park JW, Moon SH, Choe YS, Lee KH. Molecular mechanism of (18)F-FDG uptake reduction induced by genipin in T47D cancer cell and role of uncoupling protein-2 in cancer cell glucose metabolism. Nucl Med Biol 2016; 43:587-92. [PMID: 27451963 DOI: 10.1016/j.nucmedbio.2016.06.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2015] [Revised: 05/25/2016] [Accepted: 06/04/2016] [Indexed: 12/21/2022]
Abstract
INTRODUCTION Compounds that modulate cancer cell glucose metabolism could open new opportunities for antitumor therapy and for monitoring response using (18)F-FDG PET. Genipin, a natural dietary compound that blocks uncoupling protein 2 (UCP2)-mediated mitochondrial proton leakage, is a potential anticancer agent. We investigated the effect of genipin on glucose metabolism and the mitochondrial function of cancer cells. METHODS Breast and colon cancer cells were assessed for effects of genipin on (18)F-FDG uptake. T47D breast cancer cells were further evaluated for time-dependent and dose-dependent effects on (18)F-FDG uptake, lactate release, oxygen consumption rate (OCR), reactive oxygen species (ROS) production, and mitochondrial membrane potential. The effects of UCP2 knockdown were evaluated using specific siRNA. RESULTS Cancer cells displayed significant reductions in (18)F-FDG uptake by genipin. T47D cells showed the greatest reduction to 32.6±1.0% of controls by 250μM genipin. The effect occurred rapidly, reaching a plateau by 1h that lasted up to 24h. The effect was dose-dependent with a half-inhibitory concentration of 60.8μM. An accompanying decrease in lactate release was consistent with reduced glycolytic flux. OCR was significantly decreased by genipin to 82.2±11.4% of controls, and ROS generation was increased to 156.7±16.0%. These effects were largely reproduced by UCP2 knockdown with specific siRNA. CONCLUSIONS Genipin decreased cancer cell (18)F-FDG uptake by reducing both glycolytic flux and mitochondrial oxidative respiration. This effect appeared to occur by blocking the ability of UCP2 to dissipate energy and restrict ROS production through proton leakage.
Collapse
Affiliation(s)
- Young Seok Cho
- Department of Nuclear Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.
| | - Jin Hee Lee
- Department of Nuclear Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
| | - Kyung-Ho Jung
- Department of Nuclear Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
| | - Jin-Won Park
- Department of Nuclear Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
| | - Seung Hwan Moon
- Department of Nuclear Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
| | - Yearn Seong Choe
- Department of Nuclear Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
| | - Kyung-Han Lee
- Department of Nuclear Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.
| |
Collapse
|
44
|
Starkov AA, Chinopoulos C, Starkova NN, Konrad C, Kiss G, Stepanova A, Popov VN. Divalent cation chelators citrate and EDTA unmask an intrinsic uncoupling pathway in isolated mitochondria. J Bioenerg Biomembr 2017; 49:3-11. [PMID: 26971498 DOI: 10.1007/s10863-016-9656-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2016] [Accepted: 03/07/2016] [Indexed: 10/22/2022]
Abstract
We demonstrate a suppression of ROS production and uncoupling of mitochondria by exogenous citrate in Mg2+ free medium. Exogenous citrate suppressed H2O2 emission and depolarized mitochondria. The depolarization was paralleled by the stimulation of respiration of mitochondria. The uncoupling action of citrate was independent of the presence of sodium, potassium, or chlorine ions, and it was not mediated by the changes in permeability of the inner mitochondrial membrane to solutes. The citrate transporter was not involved in the citrate effect. Inhibitory analysis data indicated that several well described mitochondria carriers and channels (ATPase, IMAC, ADP/ATP translocase, mPTP, mKATP) were not involved in citrate's effect. Exogenous MgCl2 strongly inhibited citrate-induced depolarization. The uncoupling effect of citrate was demonstrated in rat brain, mouse brain, mouse liver, and human melanoma cells mitochondria. We interpreted the data as an evidence to the existence of a hitherto undescribed putative inner mitochondrial membrane channel that is regulated by extramitochondrial Mg2+ or other divalent cations.
Collapse
|
45
|
Gravielle MC. Activation-induced regulation of GABAA receptors: Is there a link with the molecular basis of benzodiazepine tolerance? Pharmacol Res 2015; 109:92-100. [PMID: 26733466 DOI: 10.1016/j.phrs.2015.12.030] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/05/2015] [Revised: 12/21/2015] [Accepted: 12/22/2015] [Indexed: 12/01/2022]
Abstract
Benzodiazepines have been used clinically for more than 50 years to treat disorders such as insomnia, anxiety, and epilepsy, as well as to aid muscle relaxation and anesthesia. The therapeutic index for benzodiazepines if very high and the toxicity is low. However, their usefulness is limited by the development of either or both tolerance to most of their pharmacological actions and dependence. Tolerance develops at different rates depending on the pharmacological action, suggesting the existence of distinct mechanisms for each behavioral parameter. Alternatively, multiple mechanisms could coexist depending on the subtype of GABAA receptor expressed and the brain region involved. Because most of the pharmacological actions of benzodiazepines are mediated through GABAA receptor binding, adaptive alterations in the number, structure, and/or functions of these receptors may play an important role in the development of tolerance. This review is focused on the regulation of GABAA receptors induced by long-term benzodiazepine exposure and its relationship with the development of tolerance. Understanding the mechanisms behind benzodiazepine tolerance is critical for designing drugs that could maintain their efficacy during long-term treatments.
Collapse
Affiliation(s)
- María Clara Gravielle
- Instituto de Investigaciones Farmacológicas, Consejo Nacional de Investigaciones Científicas y Técnicas, Universidad de Buenos Aires, Junín 956, C1113AAD Buenos Aires, Argentina.
| |
Collapse
|
46
|
Gomez JF, Cardona K, Trenor B. Lessons learned from multi-scale modeling of the failing heart. J Mol Cell Cardiol 2015; 89:146-59. [PMID: 26476237 DOI: 10.1016/j.yjmcc.2015.10.016] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/06/2015] [Revised: 10/07/2015] [Accepted: 10/14/2015] [Indexed: 12/26/2022]
Abstract
Heart failure constitutes a major public health problem worldwide. Affected patients experience a number of changes in the electrical function of the heart that predispose to potentially lethal cardiac arrhythmias. Due to the multitude of electrophysiological changes that may occur during heart failure, the scientific literature is complex and sometimes ambiguous, perhaps because these findings are highly dependent on the etiology, the stage of heart failure, and the experimental model used to study these changes. Nevertheless, a number of common features of failing hearts have been documented. Prolongation of the action potential (AP) involving ion channel remodeling and alterations in calcium handling have been established as the hallmark characteristics of myocytes isolated from failing hearts. Intercellular uncoupling and fibrosis are identified as major arrhythmogenic factors. Multi-scale computational simulations are a powerful tool that complements experimental and clinical research. The development of biophysically detailed computer models of single myocytes and cardiac tissues has contributed greatly to our understanding of processes underlying excitation and repolarization in the heart. The electrical, structural, and metabolic remodeling that arises in cardiac tissues during heart failure has been addressed from different computational perspectives to further understand the arrhythmogenic substrate. This review summarizes the contributions from computational modeling and simulation to predict the underlying mechanisms of heart failure phenotypes and their implications for arrhythmogenesis, ranging from the cellular level to whole-heart simulations. The main aspects of heart failure are presented in several related sections. An overview of the main electrophysiological and structural changes that have been observed experimentally in failing hearts is followed by the description and discussion of the simulation work in this field at the cellular level, and then in 2D and 3D cardiac structures. The implications for arrhythmogenesis in heart failure are also discussed including therapeutic measures, such as drug effects and cardiac resynchronization therapy. Finally, the future challenges in heart failure modeling and simulation will be discussed.
Collapse
Affiliation(s)
- Juan F Gomez
- Instituto de Investigación Interuniversitario en Bioingeniería y Tecnología Orientada, al Ser Humano (I3BH), Universitat Politècnica de València, Camino de Vera s/n, 46022 Valencia, Spain.
| | - Karen Cardona
- Instituto de Investigación Interuniversitario en Bioingeniería y Tecnología Orientada, al Ser Humano (I3BH), Universitat Politècnica de València, Camino de Vera s/n, 46022 Valencia, Spain.
| | - Beatriz Trenor
- Instituto de Investigación Interuniversitario en Bioingeniería y Tecnología Orientada, al Ser Humano (I3BH), Universitat Politècnica de València, Camino de Vera s/n, 46022 Valencia, Spain.
| |
Collapse
|
47
|
Baenziger JE, Hénault CM, Therien JP, Sun J. Nicotinic acetylcholine receptor-lipid interactions: Mechanistic insight and biological function. Biochim Biophys Acta 2015; 1848:1806-17. [PMID: 25791350 DOI: 10.1016/j.bbamem.2015.03.010] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2015] [Revised: 02/15/2015] [Accepted: 03/09/2015] [Indexed: 01/14/2023]
Abstract
Membrane lipids are potent modulators of the nicotinic acetylcholine receptor (nAChR) from Torpedo. Lipids influence nAChR function by both conformational selection and kinetic mechanisms, stabilizing varying proportions of activatable versus non-activatable conformations, as well as influencing the transitions between these conformational states. Of note, some membranes stabilize an electrically silent uncoupled conformation that binds agonist but does not undergo agonist-induced conformational transitions. The uncoupled nAChR, however, does transition to activatable conformations in relatively thick lipid bilayers, such as those found in lipid rafts. In this review, we discuss current understanding of lipid-nAChR interactions in the context of increasingly available high resolution structural and functional data. These data highlight different sites of lipid action, including the lipid-exposed M4 transmembrane α-helix. Current evidence suggests that lipids alter nAChR function by modulating interactions between M4 and the adjacent transmembrane α-helices, M1 and M3. These interactions have also been implicated in both the folding and trafficking of nAChRs to the cell surface. We review current mechanistic understanding of lipid-nAChR interactions, and highlight potential biological roles for lipid-nAChR interactions in modulating the synaptic response. This article is part of a Special Issue entitled: Lipid-protein interactions.
Collapse
|
48
|
Hénault CM, Sun J, Therien JP, daCosta CJ, Carswell CL, Labriola JM, Juranka PF, Baenziger JE. The role of the M4 lipid-sensor in the folding, trafficking, and allosteric modulation of nicotinic acetylcholine receptors. Neuropharmacology 2015; 96:157-68. [PMID: 25433148 DOI: 10.1016/j.neuropharm.2014.11.011] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2014] [Revised: 10/31/2014] [Accepted: 11/18/2014] [Indexed: 11/24/2022]
Abstract
With the availability of high resolution structural data, increasing attention has focused on the mechanisms by which drugs and endogenous compounds allosterically modulate nicotinic acetylcholine receptor (nAChR) function. Lipids are potent modulators of the nAChR from Torpedo. Membrane lipids influence nAChR function by both conformational selection and kinetic mechanisms, stabilizing varying proportions of pre-existing resting, open, desensitized, and uncoupled conformations, as well as influencing the transitions between these conformational states. Structural and functional data highlight a role for the lipid-exposed M4 transmembrane α-helix of each subunit in lipid sensing, and suggest that lipids influence gating by altering the binding of M4 to the adjacent transmembrane α-helices, M1 and M3. M4 has also been implicated in both the folding and trafficking of nAChRs to the cell surface, as well as in the potentiation of nAChR gating by neurosteroids. Here, we discuss the roles of M4 in the folding, trafficking, and allosteric modulation of nAChRs. We also consider the hypothesis that variable chemistry at the M4-M1/M3 transmembrane α-helical interface in different nAChR subunits governs the capacity for potentiation by activating lipids. This article is part of the Special Issue entitled 'The Nicotinic Acetylcholine Receptor: From Molecular Biology to Cognition'.
Collapse
|
49
|
Moncayo R, Moncayo H. The WOMED model of benign thyroid disease: Acquired magnesium deficiency due to physical and psychological stressors relates to dysfunction of oxidative phosphorylation. BBA Clin 2014; 3:44-64. [PMID: 26675817 PMCID: PMC4661500 DOI: 10.1016/j.bbacli.2014.11.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/29/2014] [Revised: 10/15/2014] [Accepted: 11/04/2014] [Indexed: 12/11/2022]
Abstract
BACKGROUND The aim of this study was to discern whether a relation between biochemical parameters, sonography and musculoskeletal data exists in cases of hyperthyroidism and whether they are modifiable through supplementation with selenomethionine and magnesium citrate as well as by acupuncture and manual medicine methods. RESULTS A direct correlation between whole blood selenium and serum magnesium was found in subjects without thyroid disease and in menopausal women while it was reversed in cases of thyroid diseases as well as in patients with depression, infection, and in infertile women. Vascularization indices were elevated in cases of newly diagnosed benign thyroid diseases. Musculoskeletal changes i.e. lateral tension and idiopathic moving toes, as well as situations of physical and psychological stress and minor trauma and infection led to an increase of vascularization. Magnesium levels correlated negatively with these two conditions. The supplementation brought a reduction of the vascularization indices and reduced the incidence of idiopathic moving toes. Treatment of lateral tension required manual medicine methods and acupuncture (gastrocnemius). A small subgroup of patients showed a further reduction of hyper-vascularization after receiving coenzyme Q10. CONCLUSIONS We interpret the elevated thyroid vascularization and low magnesium levels as signs of an inflammatory process related to the musculoskeletal changes. Improvement of thyroid function and morphology can be achieved after correcting the influence of stressors together with the supplementation regime. We hypothesize that the central biochemical event in thyroid disease is that of an acquired, altered mitochondrial function due to deficiency of magnesium, selenium, and coenzyme Q10.
Collapse
Affiliation(s)
- Roy Moncayo
- WOMED, Karl-Kapferer-Strasse 5, AT-6020 Innsbruck, Austria
| | - Helga Moncayo
- WOMED, Karl-Kapferer-Strasse 5, AT-6020 Innsbruck, Austria
| |
Collapse
|
50
|
Stier A, Bize P, Roussel D, Schull Q, Massemin S, Criscuolo F. Mitochondrial uncoupling as a regulator of life-history trajectories in birds: an experimental study in the zebra finch. ACTA ACUST UNITED AC 2014; 217:3579-89. [PMID: 25063856 DOI: 10.1242/jeb.103945] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Mitochondria have a fundamental role in the transduction of energy from food into ATP. The coupling between food oxidation and ATP production is never perfect, but may nevertheless be of evolutionary significance. The 'uncoupling to survive' hypothesis suggests that 'mild' mitochondrial uncoupling evolved as a protective mechanism against the excessive production of damaging reactive oxygen species (ROS). Because resource allocation and ROS production are thought to shape animal life histories, alternative life-history trajectories might be driven by individual variation in the degree of mitochondrial uncoupling. We tested this hypothesis in a small bird species, the zebra finch (Taeniopygia guttata), by treating adults with the artificial mitochondrial uncoupler 2,4-dinitrophenol (DNP) over a 32-month period. In agreement with our expectations, the uncoupling treatment increased metabolic rate. However, we found no evidence that treated birds enjoyed lower oxidative stress levels or greater survival rates, in contrast to previous results in other taxa. In vitro experiments revealed lower sensitivity of ROS production to DNP in mitochondria isolated from skeletal muscles of zebra finch than mouse. In addition, we found significant reductions in the number of eggs laid and in the inflammatory immune response in treated birds. Altogether, our data suggest that the 'uncoupling to survive' hypothesis may not be applicable for zebra finches, presumably because of lower effects of mitochondrial uncoupling on mitochondrial ROS production in birds than in mammals. Nevertheless, mitochondrial uncoupling appeared to be a potential life-history regulator of traits such as fecundity and immunity at adulthood, even with food supplied ad libitum.
Collapse
Affiliation(s)
- Antoine Stier
- University of Angers, Groupe Écologie et Conservation des Vertébrés (GECCO), 49045 Angers, Cedex 01, France
| | - Pierre Bize
- Department of Ecology and Evolution, University of Lausanne, Biophore 1015 Lausanne-Dorigny, Switzerland
| | - Damien Roussel
- Laboratoire d'Écologie des Hydrosystèmes Naturels et Anthropisés, CNRS UMR 5023, Université de Lyon, 69622 Villeurbanne Cedex, France
| | - Quentin Schull
- University of Strasbourg, Institut Pluridisciplinaire Hubert Curien, 67037 Strasbourg Cedex, France Département d'Ecologie, Physiologie et Ethologie (DEPE), CNRS UMR 7178, 23 rue Becquerel, 67087 Strasbourg Cedex 2, France
| | - Sylvie Massemin
- University of Strasbourg, Institut Pluridisciplinaire Hubert Curien, 67037 Strasbourg Cedex, France Département d'Ecologie, Physiologie et Ethologie (DEPE), CNRS UMR 7178, 23 rue Becquerel, 67087 Strasbourg Cedex 2, France
| | - François Criscuolo
- University of Strasbourg, Institut Pluridisciplinaire Hubert Curien, 67037 Strasbourg Cedex, France Département d'Ecologie, Physiologie et Ethologie (DEPE), CNRS UMR 7178, 23 rue Becquerel, 67087 Strasbourg Cedex 2, France
| |
Collapse
|