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Nazarov PA, Khrulnova SA, Kessenikh AG, Novoyatlova US, Kuznetsova SB, Bazhenov SV, Sorochkina AI, Karakozova MV, Manukhov IV. Observation of Cytotoxicity of Phosphonium Derivatives Is Explained: Metabolism Inhibition and Adhesion Alteration. Antibiotics (Basel) 2023; 12:antibiotics12040720. [PMID: 37107081 PMCID: PMC10135132 DOI: 10.3390/antibiotics12040720] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2023] [Revised: 03/30/2023] [Accepted: 04/02/2023] [Indexed: 04/29/2023] Open
Abstract
The search for new antibiotics, substances that kill prokaryotic cells and do not kill eukaryotic cells, is an urgent need for modern medicine. Among the most promising are derivatives of triphenylphosphonium, which can protect the infected organs of mammals and heal damaged cells as mitochondria-targeted antioxidants. In addition to the antioxidant action, triphenylphosphonium derivatives exhibit antibacterial activity. It has recently been reported that triphenylphosphonium derivatives cause either cytotoxic effects or inhibition of cellular metabolism at submicromolar concentrations. In this work, we analyzed the MTT data using microscopy and compared them with data on changes in the luminescence of bacteria. We have shown that, at submicromolar concentrations, only metabolism is inhibited, while an increase in alkyltriphenylphosphonium (CnTPP) concentration leads to adhesion alteration. Thus, our data on eukaryotic and prokaryotic cells confirm a decrease in the metabolic activity of cells by CnTPPs but do not confirm a cytocidal effect of TPPs at submicromolar concentrations. This allows us to consider CnTPP as a non-toxic antibacterial drug at low concentrations and a relatively safe vector for delivering other antibacterial substances into bacterial cells.
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Affiliation(s)
- Pavel A Nazarov
- Moscow Institute of Physics and Technology,141700 Dolgoprudny, Russia
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, 119992 Moscow, Russia
| | - Svetlana A Khrulnova
- Moscow Institute of Physics and Technology,141700 Dolgoprudny, Russia
- National Research Center for Hematology, 117198 Moscow, Russia
| | - Andrew G Kessenikh
- Moscow Institute of Physics and Technology,141700 Dolgoprudny, Russia
- Laboratory for Microbiology, BIOTECH University, 125080 Moscow, Russia
| | - Uliana S Novoyatlova
- Moscow Institute of Physics and Technology,141700 Dolgoprudny, Russia
- Laboratory for Microbiology, BIOTECH University, 125080 Moscow, Russia
| | | | - Sergey V Bazhenov
- Moscow Institute of Physics and Technology,141700 Dolgoprudny, Russia
- Laboratory for Microbiology, BIOTECH University, 125080 Moscow, Russia
| | - Alexandra I Sorochkina
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, 119992 Moscow, Russia
| | - Marina V Karakozova
- Center of Life Sciences, Skolkovo Institute of Science and Technology, 121205 Moscow, Russia
| | - Ilya V Manukhov
- Moscow Institute of Physics and Technology,141700 Dolgoprudny, Russia
- Laboratory for Microbiology, BIOTECH University, 125080 Moscow, Russia
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2
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Grivennikova VG, Khailova LS, Zharova TV, Kotova EA, Antonenko YN. Inhibition of respiratory complex I by 6-ketocholestanol: Relevance to recoupling action in mitochondria. BIOCHIMICA ET BIOPHYSICA ACTA. BIOENERGETICS 2022; 1863:148594. [PMID: 35850263 DOI: 10.1016/j.bbabio.2022.148594] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Revised: 07/10/2022] [Accepted: 07/11/2022] [Indexed: 06/15/2023]
Abstract
6-Ketocholestanol (kCh) is known as a mitochondrial recoupler, i.e. it abolishes uncoupling of mitochondria by such potent agents as carbonyl cyanide m-chlorophenyl hydrazone (CCCP) and 3,5-di(tert-butyl)-4-hydroxybenzylidenemalononitril (SF6847) [Starkov et al., 1997]. Here, we report data on the kCh-induced inhibition of both NADH-oxidase and NADH-ubiquinone oxidoreductase activities of the respiratory complex I in bovine heart submitochondrial particles (SMP). Based on the absence of such inhibition with hexaammineruthenium (III) (HAR) as the complex I electron acceptor, the kCh effect could be associated with the ubiquinone-binding centre of this respiratory enzyme. In isolated rat liver mitochondria (RLM), kCh inhibited oxygen consumption with the glutamate/malate, substrates of NAD-linked dehydrogenases, while no inhibition of RLM respiration was observed with succinate, in agreement with the absence of the kCh effect on the succinate oxidase activity in SMP. Three kCh analogs (cholesterol, 6α-hydroxycholesterol, and 5α,6α-epoxycholesterol) exhibited no effect on the NADH oxidase activities in both SMP and RLM. Importantly, the kCh analogs were ineffective in the recoupling of RLM treated with CCCP or SF6847. Therefore, interaction of kCh with the complex I may be involved in the kCh-mediated mitochondrial recoupling.
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Affiliation(s)
- Vera G Grivennikova
- Department of Biochemistry, School of Biology, Moscow State University, Moscow 119992, Russian Federation.
| | - Ljudmila S Khailova
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Leninskie Gory 1, Moscow 119991, Russian Federation
| | - Tatyana V Zharova
- Department of Biochemistry, School of Biology, Moscow State University, Moscow 119992, Russian Federation
| | - Elena A Kotova
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Leninskie Gory 1, Moscow 119991, Russian Federation
| | - Yuri N Antonenko
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Leninskie Gory 1, Moscow 119991, Russian Federation.
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Kotova EA, Antonenko YN. Fifty Years of Research on Protonophores: Mitochondrial Uncoupling As a Basis for Therapeutic Action. Acta Naturae 2022; 14:4-13. [PMID: 35441048 PMCID: PMC9013436 DOI: 10.32607/actanaturae.11610] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Accepted: 12/21/2021] [Indexed: 11/20/2022] Open
Abstract
Protonophores are compounds capable of electrogenic transport of protons across
membranes. Protonophores have been intensively studied over the past 50 years
owing to their ability to uncouple oxidation and phosphorylation in
mitochondria and chloroplasts. The action mechanism of classical uncouplers,
such as DNP and CCCP, in mitochondria is believed to be related to their
protonophoric activity; i.e., their ability to transfer protons across the
lipid part of the mitochondrial membrane. Given the recently revealed
deviations in the correlation between the protonophoric activity of some
uncouplers and their ability to stimulate mitochondrial respiration, this
review addresses the involvement of some proteins of the inner mitochondrial
membrane, such as the ATP/ADP antiporter, dicarboxylate carrier, and ATPase, in
the uncoupling process. However, these deviations do not contradict the
Mitchell theory but point to a more complex nature of the interaction of DNP,
CCCP, and other uncouplers with mitochondrial membranes. Therefore, a detailed
investigation of the action mechanism of uncouplers is required for a more
successful pharmacological use, including their antibacterial, antiviral,
anticancer, as well as cardio-, neuro-, and nephroprotective effects.
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Affiliation(s)
- E. A. Kotova
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119991 Russia
| | - Y. N. Antonenko
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119991 Russia
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4
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Role of respiratory uncoupling in drug-induced mitochondrial permeability transition. Toxicol Appl Pharmacol 2021; 427:115659. [PMID: 34332991 DOI: 10.1016/j.taap.2021.115659] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Revised: 07/23/2021] [Accepted: 07/27/2021] [Indexed: 12/30/2022]
Abstract
Mitochondrial injury contributes to severe drug-induced liver injury. Particularly, mitochondrial permeability transition (MPT) is thought to be relevant to cytolytic hepatitis. However, the mechanism of drug-induced MPT is unclear and prediction of MPT is not adequately evaluated in the preclinical stage. In a previous study, we found that troglitazone, a drug withdrawn due to liver injury, induced MPT via mild depolarization probably resulting from uncoupling. Herein, we investigated whether other drugs that induce MPT share similar properties as troglitazone, using isolated mitochondria from rat liver. Of the 22 test drugs examined, six drugs, including troglitazone, induced MPT and showed an uncoupling effect. Additionally, receiver operating characteristic analysis was conducted to predict the MPT potential from the respiratory control ratio, an indicator of uncoupling intensity. Results showed that 2.5 was the best threshold that exhibited high sensitivity (1.00) and high specificity (0.81), indicating that uncoupling was correlated with MPT potential. Activation of calcium-independent phospholipase A2 appeared to be involved in uncoupling-induced MPT. Furthermore, a strong relationship between MPT intensity and the uncoupling effect among similar compounds was confirmed. These results may help in predicting MPT potential using cultured cells and modifying the chemical structures of the drugs to reduce MPT risk.
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Kell DB. A protet-based, protonic charge transfer model of energy coupling in oxidative and photosynthetic phosphorylation. Adv Microb Physiol 2021; 78:1-177. [PMID: 34147184 DOI: 10.1016/bs.ampbs.2021.01.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Textbooks of biochemistry will explain that the otherwise endergonic reactions of ATP synthesis can be driven by the exergonic reactions of respiratory electron transport, and that these two half-reactions are catalyzed by protein complexes embedded in the same, closed membrane. These views are correct. The textbooks also state that, according to the chemiosmotic coupling hypothesis, a (or the) kinetically and thermodynamically competent intermediate linking the two half-reactions is the electrochemical difference of protons that is in equilibrium with that between the two bulk phases that the coupling membrane serves to separate. This gradient consists of a membrane potential term Δψ and a pH gradient term ΔpH, and is known colloquially as the protonmotive force or pmf. Artificial imposition of a pmf can drive phosphorylation, but only if the pmf exceeds some 150-170mV; to achieve in vivo rates the imposed pmf must reach 200mV. The key question then is 'does the pmf generated by electron transport exceed 200mV, or even 170mV?' The possibly surprising answer, from a great many kinds of experiment and sources of evidence, including direct measurements with microelectrodes, indicates it that it does not. Observable pH changes driven by electron transport are real, and they control various processes; however, compensating ion movements restrict the Δψ component to low values. A protet-based model, that I outline here, can account for all the necessary observations, including all of those inconsistent with chemiosmotic coupling, and provides for a variety of testable hypotheses by which it might be refined.
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Affiliation(s)
- Douglas B Kell
- Department of Biochemistry and Systems Biology, Institute of Systems, Molecular and Integrative, Biology, University of Liverpool, Liverpool, United Kingdom; The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Lyngby, Denmark.
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Iaubasarova IR, Khailova LS, Firsov AM, Grivennikova VG, Kirsanov RS, Korshunova GA, Kotova EA, Antonenko YN. The mitochondria-targeted derivative of the classical uncoupler of oxidative phosphorylation carbonyl cyanide m-chlorophenylhydrazone is an effective mitochondrial recoupler. PLoS One 2020; 15:e0244499. [PMID: 33378414 PMCID: PMC7773232 DOI: 10.1371/journal.pone.0244499] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Accepted: 12/10/2020] [Indexed: 12/11/2022] Open
Abstract
The synthesis of a mitochondria-targeted derivative of the classical mitochondrial uncoupler carbonyl cyanide-m-chlorophenylhydrazone (CCCP) by alkoxy substitution of CCCP with n-decyl(triphenyl)phosphonium cation yielded mitoCCCP, which was able to inhibit the uncoupling action of CCCP, tyrphostin A9 and niclosamide on rat liver mitochondria, but not that of 2,4-dinitrophenol, at a concentration of 1–2 μM. MitoCCCP did not uncouple mitochondria by itself at these concentrations, although it exhibited uncoupling action at tens of micromolar concentrations. Thus, mitoCCCP appeared to be a more effective mitochondrial recoupler than 6-ketocholestanol. Both mitoCCCP and 6-ketocholestanol did not inhibit the protonophoric activity of CCCP in artificial bilayer lipid membranes, which might compromise the simple proton-shuttling mechanism of the uncoupling activity on mitochondria.
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Affiliation(s)
- Iliuza R. Iaubasarova
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia
- Faculty of Chemistry, Lomonosov Moscow State University, Moscow, Russia
| | - Ljudmila S. Khailova
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia
| | - Alexander M. Firsov
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia
| | | | - Roman S. Kirsanov
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia
| | - Galina A. Korshunova
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia
| | - Elena A. Kotova
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia
| | - Yuri N. Antonenko
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia
- * E-mail:
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7
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Maeda Y, Kikuchi R, Kawagoe J, Tsuji T, Koyama N, Yamaguchi K, Nakamura H, Aoshiba K. Anti-cancer strategy targeting the energy metabolism of tumor cells surviving a low-nutrient acidic microenvironment. Mol Metab 2020; 42:101093. [PMID: 33007425 PMCID: PMC7578269 DOI: 10.1016/j.molmet.2020.101093] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Revised: 09/17/2020] [Accepted: 09/24/2020] [Indexed: 02/07/2023] Open
Abstract
OBJECTIVE Tumor cells experience hypoxia, acidosis, and hypoglycemia. Metabolic adaptation to glucose shortage is essential to maintain tumor cells' survival because of their high glucose requirement. This study evaluated the hypothesis that acidosis might promote tumor survival during glucose shortage and if so, explored a novel drug targeting metabolic vulnerability to glucose shortage. METHODS Cell survival and bioenergetics metabolism were assessed in lung cancer cell lines. Our in-house small-molecule compounds were screened to identify those that kill cancer cells under low-glucose conditions. Cytotoxicity against non-cancerous cells was also assessed. Tumor growth was evaluated in vivo using a mouse engraft model. RESULTS Acidosis limited the cellular consumption of glucose and ATP, causing tumor cells to enter a metabolically dormant but energetically economic state, which promoted tumor cell survival during glucose deficiency. We identified ESI-09, a previously known exchange protein directly activated by cAMP (EAPC) inhibitor, as an anti-cancer compound that inhibited cancer cells under low-glucose conditions even when associated with acidosis. Bioenergetic studies showed that independent of EPAC inhibition, ESI-09 was a safer mitochondrial uncoupler than a classical uncoupler and created a futile cycle of mitochondrial respiration, leading to decreased ATP production, increased ATP dissipation, and fuel scavenging. Accordingly, ESI-09 exhibited more cytotoxic effects under low-glucose conditions than under normal glucose conditions. ESI-09 was also more effective than actively proliferating cells on quiescent glucose-restricted cells. Cisplatin showed opposite effects. ESI-09 inhibited tumor growth in lung cancer engraft mice. CONCLUSIONS This study highlights the acidosis-induced promotion of tumor survival during glucose shortage and demonstrates that ESI-09 is a novel potent anti-cancer mitochondrial uncoupler that targets a metabolic vulnerability to glucose shortage even when associated with acidosis. The higher cytotoxicity under lower-than-normal glucose conditions suggests that ESI-09 is safer than conventional chemotherapy, can target the metabolic vulnerability of tumor cells to low-glucose stress, and is applicable to many cancer cell types.
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Affiliation(s)
- Yuki Maeda
- Department of Respiratory Medicine, Tokyo Medical University Ibaraki Medical Center, 3-20-1 Chuou, Ami-machi, Inashiki-gun, Ibaraki, 300-0395, Japan
| | - Ryota Kikuchi
- Department of Respiratory Medicine, Tokyo Medical University Ibaraki Medical Center, 3-20-1 Chuou, Ami-machi, Inashiki-gun, Ibaraki, 300-0395, Japan; Department of Respiratory Medicine, Tokyo Medical University, 6-7-1 Nishishinjuku, Shinjuku-ku, Tokyo, 160-0023, Japan
| | - Junichiro Kawagoe
- Department of Respiratory Medicine, Tokyo Medical University Ibaraki Medical Center, 3-20-1 Chuou, Ami-machi, Inashiki-gun, Ibaraki, 300-0395, Japan; Department of Respiratory Medicine, Tokyo Medical University, 6-7-1 Nishishinjuku, Shinjuku-ku, Tokyo, 160-0023, Japan
| | - Takao Tsuji
- Department of Medicine, Otsuki Municipal Hospital, 1255 Hanasaki, Otsuki-chou, Otsuki-shi, Yamanashi, 401-0015, Japan
| | - Nobuyuki Koyama
- Department of Clinical Oncology, Tokyo Medical University Ibaraki Medical Center, 3-20-1 Chuou, Ami-machi, Inashiki-gun, Ibaraki, 300-0395, Japan
| | - Kazuhiro Yamaguchi
- Department of Respiratory Medicine, Tokyo Medical University, 6-7-1 Nishishinjuku, Shinjuku-ku, Tokyo, 160-0023, Japan
| | - Hiroyuki Nakamura
- Department of Respiratory Medicine, Tokyo Medical University Ibaraki Medical Center, 3-20-1 Chuou, Ami-machi, Inashiki-gun, Ibaraki, 300-0395, Japan
| | - Kazutetsu Aoshiba
- Department of Respiratory Medicine, Tokyo Medical University Ibaraki Medical Center, 3-20-1 Chuou, Ami-machi, Inashiki-gun, Ibaraki, 300-0395, Japan.
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8
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Rawling T, MacDermott-Opeskin H, Roseblade A, Pazderka C, Clarke C, Bourget K, Wu X, Lewis W, Noble B, Gale PA, O'Mara ML, Cranfield C, Murray M. Aryl urea substituted fatty acids: a new class of protonophoric mitochondrial uncoupler that utilises a synthetic anion transporter. Chem Sci 2020; 11:12677-12685. [PMID: 34094462 PMCID: PMC8163295 DOI: 10.1039/d0sc02777d] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Accepted: 08/10/2020] [Indexed: 01/21/2023] Open
Abstract
Respiring mitochondria establish a proton gradient across the mitochondrial inner membrane (MIM) that is used to generate ATP. Protein-independent mitochondrial uncouplers collapse the proton gradient and disrupt ATP production by shuttling protons back across the MIM in a protonophoric cycle. Continued cycling relies on the formation of MIM-permeable anionic species that can return to the intermembrane space after deprotonation in the mitochondrial matrix. Previously described protonophores contain acidic groups that are part of delocalised π-systems that provide large surfaces for charge delocalisation and facilitate anion permeation across the MIM. Here we present a new class of protonophoric uncoupler based on aryl-urea substituted fatty acids in which an acidic group and a π-system are separated by a long alkyl chain. The aryl-urea group in these molecules acts as a synthetic anion receptor that forms intermolecular hydrogen bonds with the fatty acid carboxylate after deprotonation. Dispersal of the negative charge across the aryl-urea system produces lipophilic dimeric complexes that can permeate the MIM and facilitate repeated cycling. Substitution of the aryl-urea group with lipophilic electron withdrawing groups is critical to complex lipophilicity and uncoupling activity. The aryl-urea substituted fatty acids represent the first biological example of mitochondrial uncoupling mediated by the interaction of a fatty acid and an anion receptor moiety, via self-assembly.
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Affiliation(s)
- Tristan Rawling
- School of Mathematical and Physical Sciences, Faculty of Science, University of Technology Sydney Sydney NSW 2007 Australia +61-2-9514-7956
| | - Hugo MacDermott-Opeskin
- Research School of Chemistry, College of Science, The Australian National University Canberra ACT 0200 Australia
| | - Ariane Roseblade
- School of Mathematical and Physical Sciences, Faculty of Science, University of Technology Sydney Sydney NSW 2007 Australia +61-2-9514-7956
| | - Curtis Pazderka
- School of Mathematical and Physical Sciences, Faculty of Science, University of Technology Sydney Sydney NSW 2007 Australia +61-2-9514-7956
| | - Callum Clarke
- School of Mathematical and Physical Sciences, Faculty of Science, University of Technology Sydney Sydney NSW 2007 Australia +61-2-9514-7956
| | - Kirsi Bourget
- Discipline of Pharmacology, School of Medical Sciences, University of Sydney Sydney NSW 2006 Australia
| | - Xin Wu
- School of Chemistry, University of Sydney Sydney NSW 2006 Australia
| | - William Lewis
- School of Chemistry, University of Sydney Sydney NSW 2006 Australia
| | - Benjamin Noble
- Research School of Chemistry, College of Science, The Australian National University Canberra ACT 0200 Australia
- School of Engineering, College of Science, Engineering and Health, RMIT University Melbourne VIC 3001 Australia
| | - Philip A Gale
- School of Chemistry, University of Sydney Sydney NSW 2006 Australia
| | - Megan L O'Mara
- Research School of Chemistry, College of Science, The Australian National University Canberra ACT 0200 Australia
| | - Charles Cranfield
- School of Life Sciences, Faculty of Science, University of Technology Sydney Sydney NSW 2007 Australia
| | - Michael Murray
- Discipline of Pharmacology, School of Medical Sciences, University of Sydney Sydney NSW 2006 Australia
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9
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Khailova LS, Vygodina TV, Lomakina GY, Kotova EA, Antonenko YN. Bicarbonate suppresses mitochondrial membrane depolarization induced by conventional uncouplers. Biochem Biophys Res Commun 2020; 530:29-34. [PMID: 32828301 DOI: 10.1016/j.bbrc.2020.06.131] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Accepted: 06/24/2020] [Indexed: 12/19/2022]
Abstract
Bicarbonate has been known to modulate activities of various mitochondrial enzymes such as ATPase and soluble adenylyl cyclase. Here, we found that the ability of conventional protonophoric uncouplers, such as 2,4-dinitrophenol (DNP), carbonylcyanide p-trifluoromethoxyphenylhydrazone (FCCP) and carbonyl cyanide m-chlorophenyl hydrazone (CCCP), but not that of the new popular uncoupler BAM15, to decrease mitochondrial membrane potential was significantly diminished in the presence of millimolar concentrations of bicarbonate. Thus, the depolarizing activity of DNP and FCCP in mitochondria could be sensitive to the local concentration of bicarbonate in cells and tissues. However, bicarbonate could not restore the ATP synthesis suppressed by DNP or CCCP in mitochondria. Bicarbonate neither altered the depolarizing action of DNP and FCCP on proteoliposomes with reconstituted cytochrome c oxidase, nor affected the protonophoric activity of DNP and FCCP in artificial lipid membranes as measured with pyranine-loaded liposomes, thereby showing that the bicarbonate-induced reversal of the depolarizing action of DNP and FCCP on mitochondria did not result from direct interaction of bicarbonate with the uncouplers.
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Affiliation(s)
- Ljudmila S Khailova
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Leninskie Gory 1/40, Moscow, 119991, Russia
| | - Tatyana V Vygodina
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Leninskie Gory 1/40, Moscow, 119991, Russia
| | - Galina Y Lomakina
- Faculty of Chemistry, Lomonosov Moscow State University, Leninskie Gory 1/3, Moscow, 119991, Russia; Bauman Moscow State Technical University, Baumanskaya 2-ya, 5/1, Moscow, 105005, Russia
| | - Elena A Kotova
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Leninskie Gory 1/40, Moscow, 119991, Russia
| | - Yuri N Antonenko
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Leninskie Gory 1/40, Moscow, 119991, Russia.
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10
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Shirouchi B, Yanagi S, Okawa C, Koga M, Sato M. 6-Ketocholestanol suppresses lipid accumulation by decreasing FASN gene expression through SREBP-dependent regulation in HepG2 cells. Cytotechnology 2020; 72:175-187. [PMID: 31933103 DOI: 10.1007/s10616-019-00368-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Accepted: 12/30/2019] [Indexed: 12/20/2022] Open
Abstract
Nuclear receptors, such as liver X receptors (LXRs) and sterol regulatory element-binding proteins (SREBPs), are key regulators of lipogenic genes, including fatty acid synthase (FASN). It has been reported that several oxycholesterols (OCs) act as LXR ligands; however, it is unclear whether all OC molecular species act as ligands. We previously demonstrated that the absorption rate of dietary 6-ketocholestanol (6-keto), an oxycholesterol, is the highest of all the OCs using thoracic lymph duct-cannulated rats. However, limited information is available about the physiological significance of 6-keto. In this study, we investigated whether treatment with 6-keto increases intracellular triacylglycerol (TAG) levels through up-regulation of lipogenic gene expression in HepG2 cells. 6-Keto treatment significantly reduced intracellular TAG levels through down-regulation of lipogenic genes including FASN. Although 6-keto significantly suppressed FASN gene promoter activities, the action was completely diminished when mutations were present in the SREBP promoter site. TO901317 (TO) significantly increased FASN gene promoter activities, whereas simultaneous treatment with TO and 6-keto significantly reduced this activity. We also compared the effects of several OCs that are oxidized at the carbon-6 and -7 in the B-ring of cholesterol on FASN gene promoter activities. Similar to 6-keto, 6α-OH and 6β-OH significantly reduced the activity of the FASN gene promoter, which suggests that oxidation of carbon-6 in the B-ring may play an important role in the reduction of FASN expression. Our results indicate that 6-keto suppresses lipid accumulation by decreasing FASN gene expression through SREBP-dependent regulation in HepG2 cells.
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Affiliation(s)
- Bungo Shirouchi
- Laboratory of Nutrition Chemistry, Department of Bioscience and Biotechnology, Faculty of Agriculture, Graduate School, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka, 819-0395, Japan
| | - Shuhei Yanagi
- Laboratory of Nutrition Chemistry, Department of Bioscience and Biotechnology, Faculty of Agriculture, Graduate School, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka, 819-0395, Japan
| | - Chinami Okawa
- Laboratory of Nutrition Chemistry, Department of Bioscience and Biotechnology, Faculty of Agriculture, Graduate School, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka, 819-0395, Japan
| | - Maiko Koga
- Laboratory of Nutrition Chemistry, Department of Bioscience and Biotechnology, Faculty of Agriculture, Graduate School, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka, 819-0395, Japan
| | - Masao Sato
- Laboratory of Nutrition Chemistry, Department of Bioscience and Biotechnology, Faculty of Agriculture, Graduate School, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka, 819-0395, Japan.
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11
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Chen H, Xu H, Potash S, Starkov A, Belousov VV, Bilan DS, Denton TT, Gibson GE. Mild metabolic perturbations alter succinylation of mitochondrial proteins. J Neurosci Res 2017. [PMID: 28631845 DOI: 10.1002/jnr.24103] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Succinylation of proteins is widespread, modifies both the charge and size of the molecules, and can alter their function. For example, liver mitochondrial proteins have 1,190 unique succinylation sites representing multiple metabolic pathways. Succinylation is sensitive to both increases and decreases of the NAD+ -dependent desuccinylase, SIRT5. Although the succinyl group for succinylation is derived from metabolism, the effects of systematic variation of metabolism on mitochondrial succinylation are not known. Changes in succinylation of mitochondrial proteins following variations in metabolism were compared against the mitochondrial redox state as estimated by the mitochondrial NAD+ /NADH ratio using fluorescent probes. The ratio was decreased by reduced glycolysis and/or glutathione depletion (iodoacetic acid; 2-deoxyglucose), depressed tricarboxylic acid cycle activity (carboxyethyl ester of succinyl phosphonate), and impairment of electron transport (antimycin) or ATP synthase (oligomycin), while uncouplers of oxidative phosphorylation (carbonyl cyanide m-chlorophenyl hydrazine or tyrphostin) increased the NAD+ /NADH ratio. All of the conditions decreased succinylation. In contrast, reducing the oxygen from 20% to 2.4% increased succinylation. The results demonstrate that succinylation varies with metabolic states, is not correlated to the mitochondrial NAD+ /NADH ratio, and may help coordinate the response to metabolic challenge.
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Affiliation(s)
- Huanlian Chen
- Burke Medical Research Institute, Brain and Mind Research Institute, Weill Cornell Medicine, White Plains, New York
| | - Hui Xu
- Burke Medical Research Institute, Brain and Mind Research Institute, Weill Cornell Medicine, White Plains, New York
| | - Samuel Potash
- Burke Medical Research Institute, Brain and Mind Research Institute, Weill Cornell Medicine, White Plains, New York
| | - Anatoly Starkov
- Brain and Mind Research Institute, Weill Cornell Medicine, White Plains, New York
| | - Vsevolod V Belousov
- Laboratory of Molecular Technologies, Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, Russia
| | - Dmitry S Bilan
- Laboratory of Molecular Technologies, Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, Russia
| | - Travis T Denton
- Department of Pharmaceutical Sciences, Washington State University, College of Pharmacy, Spokane, Washington
| | - Gary E Gibson
- Burke Medical Research Institute, Brain and Mind Research Institute, Weill Cornell Medicine, White Plains, New York
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12
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Alkyl-substituted phenylamino derivatives of 7-nitrobenz-2-oxa-1,3-diazole as uncouplers of oxidative phosphorylation and antibacterial agents: involvement of membrane proteins in the uncoupling action. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2017; 1859:377-387. [DOI: 10.1016/j.bbamem.2016.12.014] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2016] [Revised: 12/15/2016] [Accepted: 12/19/2016] [Indexed: 11/19/2022]
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13
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von Ballmoos C, Biner O, Nilsson T, Brzezinski P. Mimicking respiratory phosphorylation using purified enzymes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2015; 1857:321-31. [PMID: 26707617 DOI: 10.1016/j.bbabio.2015.12.007] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 08/17/2015] [Revised: 11/17/2015] [Accepted: 12/16/2015] [Indexed: 11/26/2022]
Abstract
The enzymes of oxidative phosphorylation is a striking example of the functional association of multiple enzyme complexes, working together to form ATP from cellular reducing equivalents. These complexes, such as cytochrome c oxidase or the ATP synthase, are typically investigated individually and therefore, their functional interplay is not well understood. Here, we present methodology that allows the co-reconstitution of purified terminal oxidases and ATP synthases in synthetic liposomes. The enzymes are functionally coupled via proton translocation where upon addition of reducing equivalents the oxidase creates and maintains a transmembrane electrochemical proton gradient that energizes the synthesis of ATP by the F1F0 ATP synthase. The method has been tested with the ATP synthases from Escherichia coli and spinach chloroplasts, and with the quinol and cytochrome c oxidases from E. coli and Rhodobacter sphaeroides, respectively. Unlike in experiments with the ATP synthase reconstituted alone, the setup allows in vitro ATP synthesis under steady state conditions, with rates up to 90 ATP×s(-1)×enzyme(-1). We have also used the novel system to study the phenomenon of "mild uncoupling" as observed in mitochondria upon addition of low concentrations of ionophores (e.g. FCCP, SF6847) and the recoupling effect of 6-ketocholestanol. While we could reproduce the described effects, our data with the in vitro system does not support the idea of a direct interaction between a mitochondrial protein and the uncoupling agents as proposed earlier.
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Affiliation(s)
- Christoph von Ballmoos
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, 3012 Bern, Switzerland.
| | - Olivier Biner
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, 3012 Bern, Switzerland
| | - Tobias Nilsson
- Department of Biochemistry and Biophysics, The Arrhenius Laboratories for Natural Sciences, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Peter Brzezinski
- Department of Biochemistry and Biophysics, The Arrhenius Laboratories for Natural Sciences, Stockholm University, SE-106 91 Stockholm, Sweden
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14
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Figarola JL, Singhal J, Tompkins JD, Rogers GW, Warden C, Horne D, Riggs AD, Awasthi S, Singhal SS. SR4 Uncouples Mitochondrial Oxidative Phosphorylation, Modulates AMP-dependent Kinase (AMPK)-Mammalian Target of Rapamycin (mTOR) Signaling, and Inhibits Proliferation of HepG2 Hepatocarcinoma Cells. J Biol Chem 2015; 290:30321-41. [PMID: 26534958 DOI: 10.1074/jbc.m115.686352] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Indexed: 01/01/2023] Open
Abstract
Mitochondrial oxidative phosphorylation produces most of the energy in aerobic cells by coupling respiration to the production of ATP. Mitochondrial uncouplers, which reduce the proton gradient across the mitochondrial inner membrane, create a futile cycle of nutrient oxidation without generating ATP. Regulation of mitochondrial dysfunction and associated cellular bioenergetics has been recently identified as a promising target for anticancer therapy. Here, we show that SR4 is a novel mitochondrial uncoupler that causes dose-dependent increase in mitochondrial respiration and dissipation of mitochondrial membrane potential in HepG2 hepatocarcinoma cells. These effects were reversed by the recoupling agent 6-ketocholestanol but not cyclosporin A and were nonexistent in mitochondrial DNA-depleted HepG2 cells. In isolated mouse liver mitochondria, SR4 similarly increased oxygen consumption independent of adenine nucleotide translocase and uncoupling proteins, decreased mitochondrial membrane potential, and promoted swelling of valinomycin-treated mitochondria in potassium acetate medium. Mitochondrial uncoupling in HepG2 cells by SR4 results in the reduction of cellular ATP production, increased ROS production, activation of the energy-sensing enzyme AMPK, and inhibition of acetyl-CoA carboxylase and mammalian target of rapamycin signaling pathways, leading to cell cycle arrest and apoptosis. Global analysis of SR4-associated differential gene expression confirms these observations, including significant induction of apoptotic genes and down-regulation of cell cycle, mitochondrial, and oxidative phosphorylation pathway transcripts at 24 h post-treatment. Collectively, our studies demonstrate that the previously reported indirect activation of AMPK and in vitro anticancer properties of SR4 as well as its beneficial effects in both animal xenograft and obese mice models could be a direct consequence of its mitochondrial uncoupling activity.
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Affiliation(s)
- James L Figarola
- From the Departments of Diabetes and Metabolic Diseases Research
| | - Jyotsana Singhal
- From the Departments of Diabetes and Metabolic Diseases Research
| | | | - George W Rogers
- Seahorse Biosciences, North Billerica, Massachusetts 01862, and
| | - Charles Warden
- the Bioinformatics Program, University of Michigan, Ann Arbor, Michigan 48109
| | | | - Arthur D Riggs
- From the Departments of Diabetes and Metabolic Diseases Research
| | - Sanjay Awasthi
- Medical Oncology, Beckman Research Institute of the City of Hope, Comprehensive Cancer Center, Duarte, California 91010
| | - Sharad S Singhal
- From the Departments of Diabetes and Metabolic Diseases Research,
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15
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Weng Z, Luo Y, Yang X, Greenhaw JJ, Li H, Xie L, Mattes WB, Shi Q. Regorafenib impairs mitochondrial functions, activates AMP-activated protein kinase, induces autophagy, and causes rat hepatocyte necrosis. Toxicology 2015; 327:10-21. [DOI: 10.1016/j.tox.2014.11.002] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2014] [Revised: 10/22/2014] [Accepted: 11/03/2014] [Indexed: 12/16/2022]
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16
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Denisov SS, Kotova EA, Khailova LS, Korshunova GA, Antonenko YN. Tuning the hydrophobicity overcomes unfavorable deprotonation making octylamino-substituted 7-nitrobenz-2-oxa-1,3-diazole (n-octylamino-NBD) a protonophore and uncoupler of oxidative phosphorylation in mitochondria. Bioelectrochemistry 2014; 98:30-8. [DOI: 10.1016/j.bioelechem.2014.02.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2013] [Revised: 01/21/2014] [Accepted: 02/23/2014] [Indexed: 11/15/2022]
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17
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Dodecyl and octyl esters of fluorescein as protonophores and uncouplers of oxidative phosphorylation in mitochondria at submicromolar concentrations. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2014; 1837:149-58. [DOI: 10.1016/j.bbabio.2013.09.011] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2013] [Revised: 09/12/2013] [Accepted: 09/18/2013] [Indexed: 11/18/2022]
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18
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Simple thermodynamic model of unassisted proton shuttle uncoupling and prediction of activity from calculated speciation, lipophilicity, and molecular geometry. J Theor Biol 2012; 303:33-61. [PMID: 22425608 DOI: 10.1016/j.jtbi.2012.02.032] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2012] [Revised: 02/21/2012] [Accepted: 02/29/2012] [Indexed: 12/28/2022]
Abstract
A mechanistic model of uncoupling of oxidative phosphorylation by lipophilic weak acids (i.e. proton shuttles) was developed for the purposes of predicting the relative activity of xenobiotics of widely varying structure and of guiding the design of optimized derivatives. The model is based on thermodynamic premises not formulated elsewhere that allow for the calculation of steady-state conditions and of rate of energy dissipation on the basis of acid-dissociation and permeability behavior, the later estimated from partitioning behavior and geometric considerations. Moreover, permeability of either the neutral or of the ionized species is proposed to be effectively enhanced under conditions of asymmetrical molecular distribution. Finally, special considerations were developed to accommodate multi-protic compounds. The comparison of predicted to measured activity for a diverse testset of 48 compounds of natural origin spanning a wide range of activity yielded a Spearman's rho of 0.90. The model was used to tentatively identify several novel proton shuttles, as well as to elucidate core structures particularly conducive to proton shuttle activity from which optimized derivatives can be designed. Principles of design were formulated and examples of derivatives projected to be active at concentrations on the order of 10(-7)M are proposed. Among these are di-protic compounds predicted to shuttle two protons per cycle iteration and proposed to maximally exploit the proton shuttle mechanism. This work promotes the design of highly active, yet easily-metabolized uncouplers for therapeutic applications, namely the indirect activation of AMP-kinase, as well as for various industrial applications where low persistence is desirable.
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19
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Birceanu O, McClelland GB, Wang YS, Brown JCL, Wilkie MP. The lampricide 3-trifluoromethyl-4-nitrophenol (TFM) uncouples mitochondrial oxidative phosphorylation in both sea lamprey (Petromyzon marinus) and TFM-tolerant rainbow trout (Oncorhynchus mykiss). Comp Biochem Physiol C Toxicol Pharmacol 2011; 153:342-9. [PMID: 21172453 DOI: 10.1016/j.cbpc.2010.12.005] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/05/2010] [Revised: 12/09/2010] [Accepted: 12/09/2010] [Indexed: 11/17/2022]
Abstract
The toxicity of 3-trifluoromethyl-4-nitrophenol (TFM) appears to be due to a mismatch between ATP supply and demand in lamprey, depleting glycogen stores and starving the nervous system of ATP. The cause of this TFM-induced ATP deficit is unclear. One possibility is that TFM uncouples mitochondrial oxidative phosphorylation, thus impairing ATP production. To test this hypothesis, mitochondria were isolated from the livers of sea lamprey and rainbow trout, and O(2) consumption rates were measured in the presence of TFM or 2,4-dinitrophenol (2,4-DNP), a known uncoupler of oxidative phosphorylation. TFM and 2,4-DNP markedly increased State IV respiration in a dose-dependent fashion, but had no effect on State III respiration, which is consistent with uncoupling of oxidative phosphorylation. To determine how TFM uncoupled oxidative phosphorylation, the mitochondrial transmembrane potential (TMP) was recorded using the mitochondria-specific dye rhodamine 123. Mitochondrial TMP decreased by 22% in sea lamprey, and by 28% in trout following treatment with 50μmolL(-1) TFM. These findings suggest that TFM acted as a protonophore, dissipating the proton motive force needed to drive ATP synthesis. We conclude that the mode of TFM toxicity in sea lamprey and rainbow trout is via uncoupling of oxidative phosphorylation, leading to impaired ATP production.
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Affiliation(s)
- Oana Birceanu
- Department of Biology, Wilfrid Laurier University, 75 University Avenue W, Waterloo, Ontario, Canada N2L 3C5.
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20
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Przybylo M, Borowik T, Langner M. Fluorescence Techniques for Determination of the Membrane Potentials in High Throughput Screening. J Fluoresc 2010; 20:1139-57. [DOI: 10.1007/s10895-010-0665-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2010] [Accepted: 04/05/2010] [Indexed: 01/14/2023]
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21
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Lim HW, Lim HY, Wong KP. Uncoupling of oxidative phosphorylation by curcumin: implication of its cellular mechanism of action. Biochem Biophys Res Commun 2009; 389:187-92. [PMID: 19715674 DOI: 10.1016/j.bbrc.2009.08.121] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2009] [Accepted: 08/22/2009] [Indexed: 10/20/2022]
Abstract
Curcumin is a phytochemical isolated from the rhizome of turmeric. Recent reports have shown curcumin to have antioxidant, anti-inflammatory and anti-tumor properties as well as affecting the 5'-AMP activated protein kinase (AMPK), mTOR and STAT-3 signaling pathways. We provide evidence that curcumin acts as an uncoupler. Well-established biochemical techniques were performed on isolated rat liver mitochondria in measuring oxygen consumption, F(0)F(1)-ATPase activity and ATP biosynthesis. Curcumin displays all the characteristics typical of classical uncouplers like fccP and 2,4-dinitrophenol. In addition, at concentrations higher than 50 microM, curcumin was found to inhibit mitochondrial respiration which is a characteristic feature of inhibitory uncouplers. As a protonophoric uncoupler and as an activator of F(0)F(1)-ATPase, curcumin causes a decrease in ATP biosynthesis in rat liver mitochondria. The resulting change in ATP:AMP could disrupt the phosphorylation status of the cell; this provides a possible mechanism for its activation of AMPK and its downstream mTOR and STAT-3 signaling.
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Affiliation(s)
- Han Wern Lim
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 119260, Singapore
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22
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The local electric field within phospholipid membranes modulates the charge transfer reactions in reaction centres. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2009; 1787:1039-49. [DOI: 10.1016/j.bbabio.2009.03.011] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2009] [Revised: 03/03/2009] [Accepted: 03/05/2009] [Indexed: 11/19/2022]
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23
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Prikhodko EA, Brailovskaya IV, Korotkov SM, Mokhova EN. Features of mitochondrial energetics in living unicellular eukaryote Tetrahymena pyriformis. A model for study of mammalian intracellular adaptation. BIOCHEMISTRY (MOSCOW) 2009; 74:371-6. [PMID: 19463089 DOI: 10.1134/s0006297909040038] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Tetrahymena pyriformis is used in diverse studies as a non-mammalian alternative due to their resemblance in many main metabolic cycles. However, such basic features of mitochondrial energetics as Delta psi (electrical potential difference across the inner mitochondrial membrane) or maximal stimulation of respiration by uncouplers with different mechanisms of uncoupling, such as DNP (2,4-dinitrophenol) and FCCP (p-trifluoromethoxycarbonylcyanide phenylhydrazone), have not been studied in living ciliates. Tetrahymena pyriformis GL cells during stationary growth phase after incubation under selected conditions were used in this study. Maximal stimulation of cellular respiration by FCCP was about six-fold, thus the proton motive force was high. The DNP uncoupling effect was significantly lower. This suggests low activity of the ATP/ADP-antiporter, which performs not only exchange of intramitochondrial ATP to extramitochondrial ADP, but also helps in the uncoupling process. It participates by a similar mechanism in electrophoretic transport from matrix to cytosol of ATP(4-) and DNP anion, but not FCCP anion. Thus, in contrast with mammalian mitochondria, T. pyriformis mitochondria cannot rapidly supply the cytosol with ATP; possibly the cells need high intramitochondrial ATP. The difference between DNP and FCCP is hypothetically explained by low Delta psi value and/or an increase in concentration of long-chain acyl-CoAs, inhibitors of the ATP/ADP-antiporter. The first suggestion is confirmed by absence of mitochondria with bright fluorescence in T. pyriformis stained with the Delta psi-sensitive probe MitoTracker Red. These data suggest that T. pyriformis cells are useful as a model for study of mitochondrial role in adaptation at the intracellular level.
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Affiliation(s)
- E A Prikhodko
- Belozersky Institute of Physico-Chemical Biology and Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Moscow, 119992, Russia
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24
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Shirasaka Y, Onishi Y, Sakurai A, Nakagawa H, Ishikawa T, Yamashita S. Evaluation of human P-glycoprotein (MDR1/ABCB1) ATPase activity assay method by comparing with in vitro transport measurements: Michaelis-Menten kinetic analysis to estimate the affinity of P-glycoprotein to drugs. Biol Pharm Bull 2007; 29:2465-71. [PMID: 17142983 DOI: 10.1248/bpb.29.2465] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Human ABC transporter P-glycoprotein (P-gp/ABCB1) encoded by the multidrug resistance (MDR1) gene is recognized as one of the most important factors regulating pharmacokinetics of a number of clinically important drugs because of its function of extruding a wide range of structurally unrelated amphiphilic and hydrophobic drugs from the inside to the outside of cells in an ATP-driven mechanism. In the present study, we have evaluated the high-speed ATPase activity assay method by comparing with in vitro transport assay systems using MDR1-transfected MDR1-MDCK cells. Since substrate drugs were found to interfere with the photometric detection of inorganic phosphate (Pi) that was liberated according to the hydrolysis of ATP to ADP in ATPase activity assay, at first, a method in which the amount of Pi can be calculated correctly. Results demonstrate that the kinetic parameters obtained in ATPase activity assay are not necessarily correspond with those in in vitro transport assay, suggesting that these methods might detect the different processes of drug-P-gp interaction. The combining of the ATPase activity assay and in vitro transport technologies provides us the insight into mechanisms of the membrane transport of drugs by P-gp.
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25
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Morin D, Zini R, Berdeaux A, Tillement JP. Effect of the mitochondrial transition pore inhibitor, S-15176, on rat liver mitochondria: ATP synthase modulation and mitochondrial uncoupling induction. Biochem Pharmacol 2006; 72:911-8. [PMID: 16879802 DOI: 10.1016/j.bcp.2006.06.035] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2006] [Revised: 06/26/2006] [Accepted: 06/26/2006] [Indexed: 10/24/2022]
Abstract
S-15176 is a new inhibitor of the permeability transition pore (PTP) which has been shown to display anti-ischemic properties. We show here that S-15176 prevented PTP, cytochrome c release and maintained mitochondrial membrane potential when low concentrations of S-15176 were used (not exceeding 50 nmol/mg protein). For higher concentrations S-15176 is able to collapse mitochondrial potential. This effect was reversed by the recoupling agent 6-ketocholestanol (6-KCh) suggesting that S-15176 has uncoupling properties. In addition, S-15176 is able to inhibit ATP synthase activity and to stimulate the hydrolytic activity of the enzyme but none of these effects appears to be related to its PTP inhibiting property. These data demonstrate that S-15176 interacts with several targets in mitochondria and these pharmacological properties should be considered in the examination of its health benefits as well as its potential cytotoxicity.
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Affiliation(s)
- Didier Morin
- INSERM, U660, Créteil F-94010, France; Université Paris XII, Créteil F-94010, France.
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26
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Li XM, Momsen MM, Brockman HL, Brown RE. Sterol structure and sphingomyelin acyl chain length modulate lateral packing elasticity and detergent solubility in model membranes. Biophys J 2004; 85:3788-801. [PMID: 14645069 PMCID: PMC1303681 DOI: 10.1016/s0006-3495(03)74794-8] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
Membrane microdomains, such as caveolae and rafts, are enriched in cholesterol and sphingomyelin, display liquid-ordered phase properties, and putatively function as protein organizing platforms. The goal of this investigation was to identify sterol and sphingomyelin structural features that modulate surface compression and solubilization by detergent because liquid-ordered phase displays low lateral elasticity and resists solubilization by Triton X-100. Compared to cholesterol, sterol structural changes involved either altering the polar headgroup (e.g., 6-ketocholestanol) or eliminating the isooctyl hydrocarbon tail (e.g., 5-androsten-3beta-ol). Synthetic changes to sphingomyelin resulted in homogeneous acyl chains of differing length but of biological relevance. Using a Langmuir surface balance, surface compressional moduli were assessed at various surface pressures including those (pi > or =30 mN/m) that mimic biomembrane conditions. Sphingomyelin-sterol mixtures generally were less elastic in a lateral sense than chain-matched phosphatidylcholine-sterol mixtures at equivalent high sterol mole fractions. Increasing content of 6-ketocholestanol or 5-androsten-3beta-ol in sphingomyelin decreased lateral elasticity but much less effectively than cholesterol. Our results indicate that cholesterol is ideally structured for maximally reducing the lateral elasticity of membrane sphingolipids, for enabling resistance to Triton X-100 solubilization, and for interacting with sphingomyelins that contain saturated acyl chains similar in length to their sphingoid bases.
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Affiliation(s)
- Xin-Min Li
- The Hormel Institute, University of Minnesota, Austin, Minnesota 55912-3698, USA
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27
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Ligeret H, Barthélémy S, Bouchard Doulakas G, Carrupt PA, Tillement JP, Labidalle S, Morin D. Fluoride curcumin derivatives: new mitochondrial uncoupling agents. FEBS Lett 2004; 569:37-42. [PMID: 15225605 DOI: 10.1016/j.febslet.2004.05.032] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2004] [Revised: 05/05/2004] [Accepted: 05/18/2004] [Indexed: 11/25/2022]
Abstract
The mitochondrial effects of two fluoride curcumin derivatives were studied. They induced the collapse of mitochondrial membrane potential (DeltaPsi), increased mitochondrial respiration, and decreased O(2)*- production and promoted Ca(2+) release. These effects were reversed by the recoupling agent 6-Ketocholestanol, but not by cyclosporin A, an inhibitor of the permeability transition pore (PTP), suggesting that these compounds act as uncoupling agents. This idea was reinforced by the analysis of the physico-chemical properties of the compounds indicating, that they are mainly in the anionic form in the mitochondrial membrane. Moreover, they are able to induce PTP opening by promoting the oxidation of thiol groups and the release of cytochrome c, making these two molecules potential candidates for induction of apoptosis.
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28
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Cadena SMSC, Carnieri EGS, Echevarria A, de Oliveira MBM. Interference of MI-D, a new mesoionic compound, on artificial and native membranes. Cell Biochem Funct 2002; 20:31-7. [PMID: 11835268 DOI: 10.1002/cbf.932] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
MI-D (4-phenyl-5-(4-nitrocinnamoyl)-1,3,4-thiadiazolium-2-phenylamine chloride), a new mesoionic compound, decreased the rate of swelling induced by valinomycin-K+, as well as induced swelling in the presence of nigericin-K+. Shrinkage was also affected, suggesting interference with the inner mitochondrial membrane, which would affect both fluidity and elasticity. Fluorescence polarization of DPH and DPH-PA, probing the core and outer regions respectively, of the DMPC and native membranes, indicated that MI-D shifts the midpoint of phase transition to higher values and orders of the fluid phase. These alterations in membrane fluidity are thus related to MI-D effects on the energy-linked functions of mitochondria.
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Affiliation(s)
- Silvia M S C Cadena
- Departamento de Bioquímica, Universidade Federal do Paraná, Curitiba, Brasil.
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29
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Epstein CB, Hale W, Butow RA. Numerical methods for handling uncertainty in microarray data: an example analyzing perturbed mitochondrial function in yeast. Methods Cell Biol 2002; 65:439-52. [PMID: 11381609 DOI: 10.1016/s0091-679x(01)65026-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- C B Epstein
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
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30
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Alakoskela JMI, Kinnunen PKJ. Probing Phospholipid Main Phase Transition by Fluorescence Spectroscopy and a Surface Redox Reaction. J Phys Chem B 2001. [DOI: 10.1021/jp011080b] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Juha-Matti I. Alakoskela
- Helsinki Biophysics and Biomembrane Group, Institute of Biomedicine/Biochemistry, University of Helsinki, Helsinki, Finland
| | - Paavo K. J. Kinnunen
- Helsinki Biophysics and Biomembrane Group, Institute of Biomedicine/Biochemistry, University of Helsinki, Helsinki, Finland
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31
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Alakoskela JI, Kinnunen PK. Control of a redox reaction on lipid bilayer surfaces by membrane dipole potential. Biophys J 2001; 80:294-304. [PMID: 11159402 PMCID: PMC1301233 DOI: 10.1016/s0006-3495(01)76014-6] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Nitro-2,1,3-benzoxadiazol-4-yl (NBD) group is a widely used, environment-sensitive fluorescent probe. The negatively charged dithionite rapidly reduces the accessible NBD-labeled lipids in liposomes to their corresponding nonfluorescent derivatives. In this study both the phospholipid headgroup and acyl chain NBD-labeled L-alpha-1,2-dipalmitoyl-sn-glycero-3-phospho-[N-(4-nitrobenz-2-oxa-1,3-diazole)-ethanolamine] (DPPN) and 1-acyl-2-[12-[(7-nitro-2,1,3-benzoxadiazol-4-yl)amino]dodecanoyl]-sn-glycero-3-phosphocholine (NBD-PC), respectively, were employed. The correlation of both the rate coefficient k(1) of the redox reaction and the fluorescence properties of the two probes with the membrane dipole potential Psi in fluid dipalmitoylglycerophosphocholine (DPPC) liposomes is demonstrated. When Psi of the bilayer was varied (decreased by phloretin or increased by 6-ketocholestanol), the value for k1 decreased for both DPPN and NBD-PC with increasing Psi. For both fluorophores a positive correlation to Psi was evident for the relative fluorescence emission intensity (RFI, normalized to the emission of the fluorophore in a DPPC matrix). The relative changes in emission intensity as a function of Psi were approximately equal for both NBD derivatives. Changes similar to those caused by phloretin were seen when dihexadecylglycerophosphocholine (DHPC) was added to DPPC liposomes, in keeping with the lower dipole potential for the former lipid compound compared with DPPC. These effects of Psi on NBD fluorescence should be taken into account when interpreting data acquired using NBD-labeled lipids as fluorescent probes.
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Affiliation(s)
- J I Alakoskela
- Helsinki Biophysics and Biomembrane Group, Department of Medical Chemistry, Institute of Biomedicine, University of Helsinki, Helsinki FIN-00014, Finland
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Abstract
Oxygenated derivatives of cholesterol (oxysterols) present a remarkably diverse profile of biological activities, including effects on sphingolipid metabolism, platelet aggregation, apoptosis, and protein prenylation. The most notable oxysterol activities center around the regulation of cholesterol homeostasis, which appears to be controlled in part by a complex series of interactions of oxysterol ligands with various receptors, such as the oxysterol binding protein, the cellular nucleic acid binding protein, the sterol regulatory element binding protein, the LXR nuclear orphan receptors, and the low-density lipoprotein receptor. Identification of the endogenous oxysterol ligands and elucidation of their enzymatic origins are topics of active investigation. Except for 24, 25-epoxysterols, most oxysterols arise from cholesterol by autoxidation or by specific microsomal or mitochondrial oxidations, usually involving cytochrome P-450 species. Oxysterols are variously metabolized to esters, bile acids, steroid hormones, cholesterol, or other sterols through pathways that may differ according to the type of cell and mode of experimentation (in vitro, in vivo, cell culture). Reliable measurements of oxysterol levels and activities are hampered by low physiological concentrations (approximately 0.01-0.1 microM plasma) relative to cholesterol (approximately 5,000 microM) and by the susceptibility of cholesterol to autoxidation, which produces artifactual oxysterols that may also have potent activities. Reports describing the occurrence and levels of oxysterols in plasma, low-density lipoproteins, various tissues, and food products include many unrealistic data resulting from inattention to autoxidation and to limitations of the analytical methodology. Because of the widespread lack of appreciation for the technical difficulties involved in oxysterol research, a rigorous evaluation of the chromatographic and spectroscopic methods used in the isolation, characterization, and quantitation of oxysterols has been included. This review comprises a detailed and critical assessment of current knowledge regarding the formation, occurrence, metabolism, regulatory properties, and other activities of oxysterols in mammalian systems.
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Affiliation(s)
- G J Schroepfer
- Departments of Biochemistry, Rice University, Houston, Texas, USA.
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Abstract
According to the chemosmotic hypothesis, ATP is synthesized in mitochondria, bacteria and chloroplasts via the proton motive force delta p, the energy-rich intermediate of electron transport and photosynthetic phosphorylation. The general applicability of the chemosmotic hypothesis, however, was disputed until present. In particular the relationship between the rate of respiration and delta p in mitochondria was found variable, depending on the experimental conditions. Recently, a new mechanism of respiratory control was found, based on binding of ATP or ADP to subunit IV of cytochrome c oxidase, which is independent of delta p and could explain many previous results contradicting the chemosmotic hypothesis.
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Affiliation(s)
- B Kadenbach
- Fachbereich Chemie, Philipps-Universität, Marburg, Germany.
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Cadena SM, Carnieri EG, Echevarria A, de Oliveira MB. Effect of MI-D, a new mesoionic compound, on energy-linked functions of rat liver mitochondria. FEBS Lett 1998; 440:46-50. [PMID: 9862422 DOI: 10.1016/s0014-5793(98)01427-6] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
MI-D (4-phenyl-5-(4-nitro-cinnamoyl)-1,3,4-thiadiazolium-2-phenylami ne chloride), a new mesoionic compound, depressed the phosphorylation efficiency of liver mitochondria as deduced from an accentuated decrease of the respiratory control coefficient and ADP/O ratio. Analysis of segments of the respiratory chain suggested that the MI-D inhibition site is further on than complex I and between complexes II and III. The transmembrane electrical potential (delta psi) was collapsed dependent on MI-D concentration. ATPase activity was dramatically increased by MI-D in intact mitochondria, but inhibited in carbonylcyanide p-trifluoromethoxyphenylhydrazone (FCCP)-uncoupled mitochondria. These results suggest that MI-D acts as an uncoupler agent, a property closely related to its structural characteristics.
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Affiliation(s)
- S M Cadena
- Departamento de Bioquímica, Universidade Federal do Paraná, Curitiba, Brazil
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Bobyleva V, Pazienza TL, Maseroli R, Tomasi A, Salvioli S, Cossarizza A, Franceschi C, Skulachev VP. Decrease in mitochondrial energy coupling by thyroid hormones: a physiological effect rather than a pathological hyperthyroidism consequence. FEBS Lett 1998; 430:409-13. [PMID: 9688582 DOI: 10.1016/s0014-5793(98)00700-5] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The effect of the in vivo thyroid status on mitochondrial membrane potential (delta psi(m)) in isolated rat hepatocytes was studies by means of a cytofluorimetric technique and the delta psi(m)-specific probe JC-1. It is shown that the delta psi(m) level decreases in the order hypothyroid > euthyroid > hyperthyroid. Polarographic measurement of the hepatocyte respiratory rates revealed an opposite trend of values: the highest respiratory rate in hepatocytes from hyperthyroid animals, the lowest in those from hypothyroid ones. This means that mitochondrial energy coupling is highest in hypothyroid hepatocytes and lowest in hyperthyroid hepatocytes. 6-Ketocholestanol added to hepatocytes failed to counterbalance the uncoupling effect of thyroid hormones on delta psi(m) and respiration rate. Under the same conditions, 6-ketocholestanol appeared to be effective in recoupling of respiration uncoupled by low concentrations of the artificial protonophore FCCP. The mechanism and possible physiological functions of the thyroid hormone-induced decrease in mitochondrial energy coupling are discussed.
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Affiliation(s)
- V Bobyleva
- Department of Biomedical Sciences, University of Modena, Italy
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Skulachev VP. Uncoupling: new approaches to an old problem of bioenergetics. BIOCHIMICA ET BIOPHYSICA ACTA 1998; 1363:100-24. [PMID: 9507078 DOI: 10.1016/s0005-2728(97)00091-1] [Citation(s) in RCA: 681] [Impact Index Per Article: 26.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- V P Skulachev
- Department of Bioenergetics, A.N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow 119899, Russian Federation.
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Abstract
Release of Ca2+ from mitochondria into cytosol in intact thymocytes was studied using the fluorescent dye Fluo-3. It was shown that the release of Ca2+ induced by the dithiol cross-linking agent phenylarsine oxide or by uncoupler was strongly inhibited by cyclosporin A, a specific inhibitor of the permeability transition pore (PTP) in mitochondria. Oxidative stress sensitized the pore so even partial uncoupling caused rapid cyclosporin A-sensitive release of Ca2+. The experiments on digitonin-permeabilized cells confirmed that uncoupling induced opening of the PTP, which forms the major pathway for rapid release of Ca2+ from thymocyte mitochondria.
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Affiliation(s)
- B V Chernyak
- A.N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Russia.
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Korshunov SS, Skulachev VP, Starkov AA. High protonic potential actuates a mechanism of production of reactive oxygen species in mitochondria. FEBS Lett 1997; 416:15-8. [PMID: 9369223 DOI: 10.1016/s0014-5793(97)01159-9] [Citation(s) in RCA: 1273] [Impact Index Per Article: 47.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Formation of H2O2 has been studied in rat heart mitochondria, pretreated with H2O2 and aminotriazole to lower their antioxidant capacity. It is shown that the rate of H2O2 formation by mitochondria oxidizing 6 mM succinate is inhibited by a protonophorous uncoupler, ADP and phosphate, malonate, rotenone and myxothiazol, and is stimulated by antimycin A. The effect of ADP is abolished by carboxyatractylate and oligomycin. Addition of uncoupler after rotenone induces further inhibition of H2O2 production. Inhibition of H2O2 formation by uncoupler, malonate and ADP+Pi is shown to be proportional to the delta psi decrease by these compounds. A threshold delta psi value is found, above which a very strong increase in H2O2 production takes place. This threshold slightly exceeds the state 3 delta psi level. The data obtained are in line with the concept [Skulachev, V.P., Q. Rev. Biophys. 29 (1996), 169-2021 that a high proton motive force in state 4 is potentially dangerous for the cell due to an increase in the probability of superoxide formation.
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Affiliation(s)
- S S Korshunov
- Department of Bioenergetics, A.N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Russia
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Cuéllar A, Ramirez J, Infante VM, Chavez E. Further studies on the recoupling effect of 6-ketocholestanol upon oxidative phosphorylation in uncoupled liver mitochondria. FEBS Lett 1997; 411:365-8. [PMID: 9271237 DOI: 10.1016/s0014-5793(97)00741-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The effect of 6-ketocholestanol was studied on CCCP-induced uncoupling in liver mitochondria, submitochondrial particles and cytochrome oxidase proteoliposomes. It was found that 6-ketocholestanol prevents and reverses uncoupling induced by nM concentrations of CCCP on the three systems assayed. As it was reported on kidney mitochondrial membranes [Chavez et al. (1996) FEBS Lett. 379, 305-308], the recoupling effect caused by 6-ketocholestanol on submitochondrial particles and proteoliposomes could be due to a diminution of membrane fluidity.
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Affiliation(s)
- A Cuéllar
- Departamento de Bioquímica, Instituto Nacional de Cardiología Ignacio Chávez, México D.F., Mexico
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Starkov AA, Simonyan RA, Dedukhova VI, Mansurova SE, Palamarchuk LA, Skulachev VP. Regulation of the energy coupling in mitochondria by some steroid and thyroid hormones. BIOCHIMICA ET BIOPHYSICA ACTA 1997; 1318:173-83. [PMID: 9030262 DOI: 10.1016/s0005-2728(96)00135-1] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Male sex hormones [dihydrotestosterone (DTS), and testosterone] and progesterone, when added to the isolated rat liver mitochondria before or after some protonophores, lower the respiration rate and increase the delta psi level, i.e., reverse the protonophore-induced uncoupling. Such a recoupling ability shows specific structural requirements correlating with hormonal activity of steroids studied. For instance, epiandrosterone, a DTS isomer of very low hormonal activity, and deoxycorticosterone, differing from progesterone by additional OH-group and possessing quite different hormonal activity, as well as female sex hormones (estron and estradiol) show no recoupling effect. Like 6-ketocholestanol (kCh), male sex hormones and progesterone recouple mitochondria uncoupled by low concentrations of SF6847, FCCP and CCCP, but not by high concentration of these uncouplers or by any concentration of DNP, palmitate and gramicidin. In contrast to recoupling by kCh, hormonal recoupling requires addition of serum albumin and is inhibited by low concentrations of palmitate. Recoupling can also be shown on the heart and skeletal muscle mitochondria, being absent from the heart muscle submitochondrial particles, the bacterial chromatophores and the cytochrome oxidase proteoliposomes. In mitochondria it does not depend upon the oxidation substrate used (succinate or PMS + ascorbate were tested). Pronounced seasonal effect upon the DTS recoupling degree was revealed. The recoupling is maximal in January, February and from June to November, being minimal in the spring months and in December. In spring, the in vivo administration of thyroxine, di- or triiodothyronine improves the recoupling ability of DTS. 2 x 10 - 6 M. Thyroxine, when added in vitro, does not affect energy coupling if SF6847 was absent. In the presence of small amounts of SF6847, thyroxine stimulates the uncoupling in a DTS-sensitive fashion, di- and triiodothyronines being less effective. Addition of thyroxine to azide-inhibited mitochondria (oligomycin is present) stimulates respiration and normalizes the delta psi level. In this system, triiodothyronine is much less effective, whereas diiodothyronine is not effective at all. In the intact cells (thymocytes and the Krebs-II cells were tested), DTS lowers the respiration rate stimulated by low concentrations of SF6846 or FCCP. In this case, serum albumin is not required. It is suggested that recoupling effects of male sex hormones and progesterone are involved in their anabolic action just as uncoupling takes part in the catabolic activity of thyroid hormones.
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Affiliation(s)
- A A Starkov
- Department of Bioenergetics, A.N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Russia
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