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Koo BH, Hwang HM, Yi BG, Lim HK, Jeon BH, Hoe KL, Kwon YG, Won MH, Kim YM, Berkowitz DE, Ryoo S. Arginase II Contributes to the Ca 2+/CaMKII/eNOS Axis by Regulating Ca 2+ Concentration Between the Cytosol and Mitochondria in a p32-Dependent Manner. J Am Heart Assoc 2019; 7:e009579. [PMID: 30371203 PMCID: PMC6222941 DOI: 10.1161/jaha.118.009579] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Background Arginase II activity contributes to reciprocal regulation of endothelial nitric oxide synthase (eNOS). We tested the hypotheses that arginase II activity participates in the regulation of Ca2+/Ca2+/calmodulin‐dependent kinase II/eNOS activation, and this process is dependent on mitochondrial p32. Methods and Results Downregulation of arginase II increased the concentration of cytosolic Ca2+ ([Ca2+]c) and decreased mitochondrial Ca2+ ([Ca2+]m) in microscopic and fluorescence‐activated cell sorting analyses, resulting in augmented eNOS Ser1177 phosphorylation and decreased eNOS Thr495 phosphorylation through Ca2+/Ca2+/calmodulin‐dependent kinase II. These changes were observed in human umbilical vein endothelial cells treated with small interfering RNA against p32 (sip32). Using matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry, fluorescence immunoassay, and ion chromatography, inhibition of arginase II reduced the amount of spermine, a binding molecule, and the release of Ca2+ from p32. In addition, arginase II gene knockdown using small interfering RNA and knockout arginase II‐null mice resulted in reduced p32 protein level. In the aortas of wild‐type mice, small interfering RNA against p32 induced eNOS Ser1177 phosphorylation and enhanced NO‐dependent vasorelaxation. Arginase activity, p32 protein expression, spermine amount, and [Ca2+]m were increased in the aortas from apolipoprotein E (ApoE−/−) mice fed a high‐cholesterol diet, and intravenous administration of small interfering RNA against p32 restored Ca2+/Ca2+/calmodulin‐dependent kinase II‐dependent eNOS Ser1177 phosphorylation and improved endothelial dysfunction. The effects of arginase II downregulation were not associated with elevated NO production when tested in aortic endothelia from eNOS knockout mice. Conclusions These data demonstrate a novel function of arginase II in regulation of Ca2+‐dependent eNOS phosphorylation. This novel mechanism drives arginase activation, mitochondrial dysfunction, endothelial dysfunction, and atherogenesis.
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Affiliation(s)
- Bon-Hyeock Koo
- 1 Department of Biology School of medicine Kangwon National University Chuncheon Korea
| | - Hye-Mi Hwang
- 1 Department of Biology School of medicine Kangwon National University Chuncheon Korea
| | - Bong-Gu Yi
- 1 Department of Biology School of medicine Kangwon National University Chuncheon Korea
| | - Hyun Kyo Lim
- 4 Department of Anesthesiology and Pain Medicine Yonsei University Wonju College of Medicine Wonju Korea
| | - Byeong Hwa Jeon
- 5 Infectious Signaling Network Research Center Department of Physiology School of Medicine Chungnam National University Daejeon Korea
| | - Kwang Lae Hoe
- 6 Department of New Drug Discovery and Development Chungnam National University Daejeon Korea
| | | | - Moo-Ho Won
- 2 Department of Neurobiology School of medicine Kangwon National University Chuncheon Korea
| | - Young Myeong Kim
- 3 College of Natural Sciences and Departments of Molecular and Cellular Biochemistry School of medicine Kangwon National University Chuncheon Korea
| | - Dan E Berkowitz
- 8 Department of Anesthesiology and Critical Care Medicine Johns Hopkins University Baltimore MD
| | - Sungwoo Ryoo
- 1 Department of Biology School of medicine Kangwon National University Chuncheon Korea
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Ohkubo S, Dalla Via L, Grancara S, Kanamori Y, García-Argáez AN, Canettieri G, Arcari P, Toninello A, Agostinelli E. The antioxidant, aged garlic extract, exerts cytotoxic effects on wild-type and multidrug-resistant human cancer cells by altering mitochondrial permeability. Int J Oncol 2018; 53:1257-1268. [PMID: 29956777 DOI: 10.3892/ijo.2018.4452] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2018] [Accepted: 05/16/2018] [Indexed: 11/06/2022] Open
Abstract
Aged garlic extract (AGE) has been shown to possess therapeutic properties in cancer; however its mechanisms of action are unclear. In this study, we demonstrate by MTT assay that AGE exerts an anti-proliferative effect on a panel of both sensitive and multidrug-resistant (MDR) human cancer cell lines and enhances the effects of hyperthermia (42˚C) on M14 melanoma cells. The evaluation of the mitochondrial activity in whole cancer cells treated with AGE, performed by cytofluorimetric analysis in the presence of the lipophilic cationic fluorochrome JC-1, revealed the occurrence of dose-dependent mitochondrial membrane depolarization. Membrane potential was measured by the TPP+ selective electrode. In order to shed light on its mechanisms of action, the effects of AGE on isolated rat liver mitochondria were also examined. In this regard, AGE induced a mitochondrial membrane hyperpolarization of approximately 15 mV through a mechanism that was similar to that observed with the ionophores, nigericin or salinomycin, by activating an exchange between endogenous K+ with exogenous H+. The prolonged incubation of the mitochondria with AGE induced depolarization and matrix swelling, indicative of mitochondrial permeability transition induction that, however, occurs through a different mechanism from the well-known one. In particular, the transition pore opening induced by AGE was due to the rearrangement of the mitochondrial membranes following the increased activity of the K+/H+ exchanger. On the whole, the findings of this study indicate that AGE exerts cytotoxic effects on cancer cells by altering mitochondrial permeability. In particular, AGE in the mitochondria activates K+/H+ exchanger, causes oxidative stress and induces mitochondrial permeability transition (MPT).
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Affiliation(s)
- Shinji Ohkubo
- Department of Biochemical Sciences 'A. Rossi Fanelli', Sapienza University of Rome, I-00185 Rome, Italy
| | - Lisa Dalla Via
- Department of Pharmaceutical and Pharmacological Sciences, University of Padua, I-35131 Padua, Italy
| | - Silvia Grancara
- Department of Biochemical Sciences 'A. Rossi Fanelli', Sapienza University of Rome, I-00185 Rome, Italy
| | - Yuta Kanamori
- Department of Biochemical Sciences 'A. Rossi Fanelli', Sapienza University of Rome, I-00185 Rome, Italy
| | - Aída Nelly García-Argáez
- Department of Pharmaceutical and Pharmacological Sciences, University of Padua, I-35131 Padua, Italy
| | - Gianluca Canettieri
- Department of Molecular Medicine - Sapienza University of Rome, 00161 Rome, Italy
| | - Paolo Arcari
- Department of Molecular Medicine and Medical Biotechnology, University of Naples Federico II, I-80138 Naples, Italy
| | - Antonio Toninello
- Department of Biomedical Sciences, University of Padua, I-35131 Padua, Italy
| | - Enzo Agostinelli
- Department of Biochemical Sciences 'A. Rossi Fanelli', Sapienza University of Rome, I-00185 Rome, Italy
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Milestones and recent discoveries on cell death mediated by mitochondria and their interactions with biologically active amines. Amino Acids 2016; 48:2313-26. [PMID: 27619911 DOI: 10.1007/s00726-016-2323-z] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2016] [Accepted: 08/25/2016] [Indexed: 12/19/2022]
Abstract
Mitochondria represent cell "powerhouses," being involved in energy transduction from the electrochemical gradient to ATP synthesis. The morphology of their cell types may change, according to various metabolic processes or osmotic pressure. A new morphology of the inner membrane and mitochondrial cristae, significantly different from the previous one, has been proposed for the inner membrane and mitochondrial cristae, based on the technique of electron tomography. Mitochondrial Ca(2+) transport (the transporter has been isolated) generates reactive oxygen species and induces the mitochondrial permeability transition of both inner and outer mitochondrial membranes, leading to induction of necrosis and apoptosis. In the mitochondria of several cell types (liver, kidney, and heart), mitochondrial oxidative stress is an essential step in the induction of cell death, although not in brain, in which the phenomenon is caused by a different mechanism. Mitochondrial permeability transition drives both apoptosis and necrosis, whereas mitochondrial outer membrane permeability is characteristic of apoptosis. Adenine nucleotide translocase remains the most important component involved in membrane permeability, with the opening of the transition pore, although other proteins, such as ATP synthase or phosphate carriers, have been proposed. Intrinsic cell death is triggered by the release from mitochondria of proteic factors, such as cytochrome c, apoptosis inducing factor, and Smac/DIABLO, with the activation of caspases upon mitochondrial permeability transition or mitochondrial outer membrane permeability induction. Mitochondrial permeability transition induces the permeability of the inner membrane in sites in contact with the outer membrane; mitochondrial outer membrane permeability forms channels on the outer membrane by means of various stimuli involving Bcl-2 family proteins. The biologically active amines, spermine, and agmatine, have specific functions on mitochondria which distinguish them from other amines. Enzymatic oxidative deamination of spermine by amine oxidases in tumor cells may produce reactive oxygen species, leading to transition pore opening and apoptosis. This process could be exploited as a new therapeutic strategy to combat cancer.
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Grancara S, Dalla Via L, García-Argáez AN, Ohkubo S, Pacella E, Manente S, Bragadin M, Toninello A, Agostinelli E. Spermine cycling in mitochondria is mediated by adenine nucleotide translocase activity: mechanism and pathophysiological implications. Amino Acids 2016; 48:2327-37. [PMID: 27255894 DOI: 10.1007/s00726-016-2264-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2016] [Accepted: 05/23/2016] [Indexed: 10/21/2022]
Abstract
Spermine, besides to be transported in mitochondria by an energy dependent electrophoretic mechanism, can be also released by two different mechanisms. The first one is induced in deenergizing conditions by FCCP or antimycin A and it is mediated by an electroneutral exchange spermine protons. The second one takes place in energizing conditions during the activity of the adenine nucleotide translocase and is mediated by an electroneutral symport mechanism involving the efflux in co-transport of spermine and phosphate and the exchange of exogenous ADP with endogenous ATP. The triggering of this mechanism permits an alternating cycling of spermine across the mitochondrial membrane, that is spermine is transported or released by energized mitochondria in the absence or presence of ATP synthesis, respectively. The physiological implications of this cycling of spermine are related to the induction or prevention of mitochondrial permeability transition and, consequently, on apoptosis or its prevention.
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Affiliation(s)
- Silvia Grancara
- Department of Biochemical Sciences, SAPIENZA University of Rome, Piazzale Aldo Moro 5, 00185, Rome, Italy
| | - Lisa Dalla Via
- Department of Pharmaceutical and Pharmacological Sciences, University of Padua, Via F. Marzolo 5, 35131, Padua, Italy
| | - Aida Nelly García-Argáez
- Department of Pharmaceutical and Pharmacological Sciences, University of Padua, Via F. Marzolo 5, 35131, Padua, Italy
| | - Shinji Ohkubo
- Department of Biochemical Sciences, SAPIENZA University of Rome, Piazzale Aldo Moro 5, 00185, Rome, Italy
| | - Elena Pacella
- Department of Sense Organs, Faculty Medicine and Dentistry, SAPIENZA University of Rome, Viale del Policlinico 155, 00161, Rome, Italy
| | - Sabrina Manente
- Department of Molecular Sciences and Nanosystems, Ca' Foscari University of Venice, Venice, Italy
| | - Marcantonio Bragadin
- Department of Molecular Sciences and Nanosystems, Ca' Foscari University of Venice, Venice, Italy
| | - Antonio Toninello
- Department of Biomedical Sciences, University of Padua, Viale U. Bassi 58 B, 35131, Padua, Italy. .,Department of Biomedical Sciences, University of Padua, Viale G. Colombo 3, 35131, Padua, Italy.
| | - Enzo Agostinelli
- Department of Biochemical Sciences, SAPIENZA University of Rome, Piazzale Aldo Moro 5, 00185, Rome, Italy
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Grancara S, Zonta F, Ohkubo S, Brunati AM, Agostinelli E, Toninello A. Pathophysiological implications of mitochondrial oxidative stress mediated by mitochondriotropic agents and polyamines: the role of tyrosine phosphorylation. Amino Acids 2015; 47:869-83. [PMID: 25792113 DOI: 10.1007/s00726-015-1964-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2014] [Accepted: 03/11/2015] [Indexed: 12/23/2022]
Abstract
Mitochondria, once merely considered as the "powerhouse" of cells, as they generate more than 90 % of cellular ATP, are now known to play a central role in many metabolic processes, including oxidative stress and apoptosis. More than 40 known human diseases are the result of excessive production of reactive oxygen species (ROS), bioenergetic collapse and dysregulated apoptosis. Mitochondria are the main source of ROS in cells, due to the activity of the respiratory chain. In normal physiological conditions, ROS generation is limited by the anti-oxidant enzymatic systems in mitochondria. However, disregulation of the activity of these enzymes or interaction of respiratory complexes with mitochondriotropic agents may lead to a rise in ROS concentrations, resulting in oxidative stress, mitochondrial permeability transition (MPT) induction and triggering of the apoptotic pathway. ROS concentration is also increased by the activity of amine oxidases located inside and outside mitochondria, with oxidation of biogenic amines and polyamines. However, it should also be recalled that, depending on its concentration, the polyamine spermine can also protect against stress caused by ROS scavenging. In higher organisms, cell signaling pathways are the main regulators in energy production, since they act at the level of mitochondrial oxidative phosphorylation and participate in the induction of the MPT. Thus, respiratory complexes, ATP synthase and transition pore components are the targets of tyrosine kinases and phosphatases. Increased ROS may also regulate the tyrosine phosphorylation of target proteins by activating Src kinases or phosphatases, preventing or inducing a number of pathological states.
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Affiliation(s)
- Silvia Grancara
- Department of Biomedical Sciences, University of Padova, Viale U. Bassi 58B, 35131, Padua, Italy
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Elustondo PA, Negoda A, Kane CL, Kane DA, Pavlov EV. Spermine selectively inhibits high-conductance, but not low-conductance calcium-induced permeability transition pore. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2014; 1847:231-240. [PMID: 25448536 DOI: 10.1016/j.bbabio.2014.10.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2014] [Revised: 10/13/2014] [Accepted: 10/29/2014] [Indexed: 12/21/2022]
Abstract
The permeability transition pore (PTP) is a large channel of the mitochondrial inner membrane, the opening of which is the central event in many types of stress-induced cell death. PTP opening is induced by elevated concentrations of mitochondrial calcium. It has been demonstrated that spermine and other polyamines can delay calcium-induced swelling of isolated mitochondria, suggesting their role as inhibitors of the mitochondrial PTP. Here we further investigated the mechanism by which spermine inhibits the calcium-induced, cyclosporine A (CSA) -sensitive PTP by using three indicators: 1) calcium release from the mitochondria detected with calcium green, 2) mitochondrial membrane depolarization using TMRM, and 3) mitochondrial swelling by measuring light absorbance. We found that despite calcium release and membrane depolarization, indicative of PTP activation, mitochondria underwent only partial swelling in the presence of spermine. This was in striking contrast to the high-amplitude swelling detected in control mitochondria and in mitochondria treated with the PTP inhibitor CSA. We conclude that spermine selectively prevents opening of the high-conductance state, while allowing activation of the lower conductance state of the PTP. We propose that the existence of lower conductance, stress-induced PTP might play an important physiological role, as it is expected to allow the release of toxic levels of calcium, while keeping important molecules (e.g., NAD) within the mitochondrial matrix.
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Affiliation(s)
- Pia A Elustondo
- Department of Physiology and Biophysics, Dalhousie University, Halifax, NS B3H 4R2, Canada
| | - Alexander Negoda
- Department of Physiology and Biophysics, Dalhousie University, Halifax, NS B3H 4R2, Canada
| | - Constance L Kane
- Department of Human Kinetics, St. Francis Xavier University, Antigonish, NS B2G 2W5, Canada
| | - Daniel A Kane
- Department of Human Kinetics, St. Francis Xavier University, Antigonish, NS B2G 2W5, Canada
| | - Evgeny V Pavlov
- Department of Physiology and Biophysics, Dalhousie University, Halifax, NS B3H 4R2, Canada.
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Toninello A, Dalla Via L, Testa S, Siliprandi D. Electrophoretic polyamine transport in rat liver mitochondria. Amino Acids 2013; 2:69-76. [PMID: 24194273 DOI: 10.1007/bf00806076] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Naturally occurring polyamines (spermidine, putrescine, cadaverine), as the well studied spermine, are transported into rat liver mitochondrial matrix provided that mitochondria are energized and the electrical membrane potential has a value of about 180 mV. This condition is achieved by the presence of inorganic phosphate, or acetate, or nigericin in the incubation medium. Valinomycin plus K(+) almost completely blocks polyamine transport.The obtained results clearly show that all naturally occurring polyamines are transported by an electrophoretic mechanism in responce to a high negative inner electrical potential.The distribution ratio of polyamines across the mitochondrial membrane is far from the thermodynamic equilibrium by many orders of magnitude. This result might suggest the existence of a different pathway for polyamine efflux.
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Affiliation(s)
- A Toninello
- Centro Studio Fisiologia Mitocondriale del C.N.R. Padova, Dipartimento di Chimica Biologica, Universita' di Padova, Via Trieste 75, I-35121, Padova, Italy
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Grancara S, Martinis P, Manente S, García-Argáez AN, Tempera G, Bragadin M, Dalla Via L, Agostinelli E, Toninello A. Bidirectional fluxes of spermine across the mitochondrial membrane. Amino Acids 2013; 46:671-9. [PMID: 24043461 DOI: 10.1007/s00726-013-1591-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2013] [Accepted: 09/04/2013] [Indexed: 02/08/2023]
Abstract
The polyamine spermine is transported into the mitochondrial matrix by an electrophoretic mechanism having as driving force the negative electrical membrane potential (ΔΨ). The presence of phosphate increases spermine uptake by reducing ΔpH and enhancing ΔΨ. The transport system is a specific uniporter constituted by a protein channel exhibiting two asymmetric energy barriers with the spermine binding site located in the energy well between the two barriers. Although spermine transport is electrophoretic in origin, its accumulation does not follow the Nernst equation for the presence of an efflux pathway. Spermine efflux may be induced by different agents, such as FCCP, antimycin A and mersalyl, able to completely or partially reduce the ΔΨ value and, consequently, suppress or weaken the force necessary to maintain spermine in the matrix. However this efflux may also take place in normal conditions when the electrophoretic accumulation of the polycationic polyamine induces a sufficient drop in ΔΨ able to trigger the efflux pathway. The release of the polyamine is most probably electroneutral in origin and can take place in exchange with protons or in symport with phosphate anion. The activity of both the uptake and efflux pathways induces a continuous cycling of spermine across the mitochondrial membrane, the rate of which may be prominent in imposing the concentrations of spermine in the inner and outer compartment. Thus, this event has a significant role on mitochondrial permeability transition modulation and consequently on the triggering of intrinsic apoptosis.
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Affiliation(s)
- Silvia Grancara
- Department of Biomedical Sciences, University of Padua, Viale U. Bassi 58 B, 35131, Padua, Italy
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Spanaki C, Zaganas I, Kounoupa Z, Plaitakis A. The complex regulation of human glud1 and glud2 glutamate dehydrogenases and its implications in nerve tissue biology. Neurochem Int 2012; 61:470-81. [PMID: 22658952 DOI: 10.1016/j.neuint.2012.05.020] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2012] [Revised: 05/20/2012] [Accepted: 05/21/2012] [Indexed: 12/01/2022]
Abstract
Mammalian glutamate dehydrogenase (GDH) is a housekeeping mitochondrial enzyme (hGDH1 in the human) that catalyses the reversible inter-conversion of glutamate to α-ketoglutarate and ammonia, thus interconnecting amino acid and carbohydrate metabolism. It displays an energy sensing mechanism, which permits enzyme activation under low cellular energy states. As GDH is at the crossroads of important metabolic pathways, a tight control of its activity is essential. Indeed, to fulfill its role in metabolism and cellular energetics, mammalian GDH has evolved into a highly regulated enzyme subject to allosteric modulation by diverse compounds. The recent emergence (<23 million years ago) in apes and humans of a hGDH2 isoenzyme with distinct regulatory properties, as well as, the detection of gain-of-function variants in hGDH1 and hGDH2 that affect the nervous system, have introduced additional complexities. The properties of the two highly homologous human GDHs were studied using purified recombinant hGDH1 and hGDH2 obtained by expression of the corresponding cDNAs in Sf21 cells. Results showed that, in contrast to hGDH1 that maintains substantial basal activity (35-40% of its maximal capacity), hGDH2 displays low basal activity (3-8% of maximal) that is remarkably responsive to activation by rising levels of ADP and/or l-leucine. This is primarily due to the Arg443Ser evolutionary change, which also made hGDH2 markedly sensitive to estrogens and neuroleptic drugs. In contrast to hGDH1, which is subject to potent GTP inhibition, hGDH2 has dissociated its function from this energy switch, being able to metabolize glutamate even when the Krebs cycle generates GTP levels sufficient to inactivate the housekeeping hGDH1. Our data also show that spermidine, a polyamine thought to reduce oxidative stress and to prolong survival, and EGCG, a green tea polyphenol, inhibit hGDH2 at lower concentrations than hGDH1. The implications of these findings in nerve tissue biology are discussed.
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Affiliation(s)
- Cleanthe Spanaki
- Department of Neurology, Medical School, University of Crete, Heraklion, Crete, Greece
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Battaglia V, Tibaldi E, Grancara S, Zonta F, Brunati AM, Martinis P, Bragadin M, Grillo MA, Tempera G, Agostinelli E, Toninello A. Effect of peroxides on spermine transport in rat brain and liver mitochondria. Amino Acids 2011; 42:741-9. [DOI: 10.1007/s00726-011-0990-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2011] [Accepted: 06/02/2011] [Indexed: 11/28/2022]
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Do mammalian amine oxidases and the mitochondrial polyamine transporter have similar protein structures? Amino Acids 2011; 42:725-31. [DOI: 10.1007/s00726-011-0988-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2011] [Accepted: 05/05/2011] [Indexed: 10/17/2022]
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Further characterization of agmatine binding to mitochondrial membranes: involvement of imidazoline I2 receptor. Amino Acids 2011; 42:761-8. [DOI: 10.1007/s00726-011-0992-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2011] [Accepted: 05/05/2011] [Indexed: 10/17/2022]
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Agmatine transport in brain mitochondria: a different mechanism from that in liver mitochondria. Amino Acids 2009; 38:423-30. [PMID: 19997762 DOI: 10.1007/s00726-009-0401-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2009] [Accepted: 10/20/2009] [Indexed: 10/20/2022]
Abstract
The diamine agmatine (AGM), exhibiting two positive charges at physiological pH, is transported into rat brain mitochondria (RBM) by an electrophoretic mechanism, requiring high membrane potential values and exhibiting a marked non-ohmic force-flux relationship. The mechanism of this transport apparently resembles that observed in rat liver mitochondria (RLM), but there are several characteristics that strongly suggest the presence of a different transporter of agmatine in RBM. In this type of mitochondria, the extent of initial binding and total accumulation is higher and lower, respectively, than that in liver; saturation kinetics and the flux-voltage relationship also exhibit different trends, whereas idazoxan and putrescine, ineffective in RLM, act as inhibitors. The characteristics of agmatine uptake in RBM lead to the conclusion that its transporter is a channel with two asymmetric energy barriers, showing some characteristics similar to those of the imidazoline receptor I(2) and the sharing with the polyamine transporter.
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15
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Ca2+ -independent effects of spermine on pyruvate dehydrogenase complex activity in energized rat liver mitochondria incubated in the absence of exogenous Ca2+ and Mg2+. Amino Acids 2008; 36:449-56. [PMID: 18500430 DOI: 10.1007/s00726-008-0099-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2008] [Accepted: 04/29/2008] [Indexed: 10/22/2022]
Abstract
In the absence of exogenous Ca(2+) and Mg(2+) and in the presence of EGTA, which favours the release of endogenous Ca(2+), the polyamine spermine is able to stimulate the activity of pyruvate dehydrogenase complex (PDC) of energized rat liver mitochondria (RLM). This stimulation exhibits a gradual concentration-dependent trend, which is maximum, about 140%, at 0.5 mM concentration, after 30 min of incubation. At concentrations higher than 0.5 mM, spermine still stimulates PDC, when compared with the control, but shows a slight dose-dependent decrease. Changes in PDC stimulation are very close to the phosphorylation level of the E(1alpha) subunit of PDC, which regulates the activity of the complex, but it is also the target of spermine. In other words, progressive dephosphorylation gradually enhances the stimulation of RLM and progressive phosphorylation slightly decreases it. These results provide the first evidence that, when transported in RLM, spermine can interact in various ways with PDC, showing dose-dependent behaviour. The interaction most probably takes place directly on a specific site for spermine on one of the regulatory enzymes of PDC, i.e. pyruvate dehydrogenase phosphatase (PDP). The interaction of spermine with PDC may also involve activation of another regulatory enzyme, pyruvate dehydrogenase kinase (PDK), resulting in an increase in E(1alpha) phosphorylation and consequently reduced stimulation of PDC at high polyamine concentrations. The different effects of spermine in RLM are discussed, considering the different activities of PDP and PDK isoenzymes. It is suggested that the polyamine at low concentrations stimulates the isoenzyme PDP(2) and at high concentrations it stimulates PDK(2).
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Grillo MA, Battaglia V, Colombatto S, Rossi CA, Simonian AR, Salvi M, Khomutov AR, Toninello A. Inhibition of agmatine transport in liver mitochondria by new charge-deficient agmatine analogues. Biochem Soc Trans 2007; 35:401-4. [PMID: 17371286 DOI: 10.1042/bst0350401] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The charge of the agmatine analogues AO-Agm [N-(3-aminooxypropyl)guanidine], GAPA [N-(3-aminopropoxy)guanidine] and NGPG [N-(3-guanidinopropoxy)guanidine] is deficient as compared with that of agmatine and they are thus able to inhibit agmatine transport in liver mitochondria. The presence of the guanidine group is essential for an optimal effect, since AO-Agm and NGPG display competitive inhibition, whereas that of GAPA is non-competitive. NGPG is the most effective inhibitor (Ki=0.86 mM). The sequence in the inhibitory efficacy is not directly dependent on the degree of protonation of the molecules; in fact NGPG has almost the same charge as GAPA. When the importance of the guanidine group for agmatine uptake is taken into account, this observation suggests that the agmatine transporter is a single-binding, centre-gated pore rather than a channel.
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Affiliation(s)
- M A Grillo
- Department of Medicine and Experimental Oncology, University of Turin, Italy
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Salvi M, Battaglia V, Mancon M, Colombatto S, Cravanzola C, Calheiros R, Marques M, Grillo M, Toninello A. Agmatine is transported into liver mitochondria by a specific electrophoretic mechanism. Biochem J 2006; 396:337-45. [PMID: 16509824 PMCID: PMC1462718 DOI: 10.1042/bj20060003] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Agmatine, a divalent diamine with two positive charges at physiological pH, is transported into the matrix of liver mitochondria by an energy-dependent mechanism the driving force of which is DeltaPsi (electrical membrane potential). Although this process showed strict electrophoretic behaviour, qualitatively similar to that of polyamines, agmatine is most probably transported by a specific uniporter. Shared transport with polyamines by means of their transporter is excluded, as divalent putrescine and cadaverine are ineffective in inhibiting agmatine uptake. Indeed, the use of the electroneutral transporter of basic amino acids can also be discarded as ornithine, arginine and lysine are completely ineffective at inducing the inhibition of agmatine uptake. The involvement of the monoamine transporter or the existence of a leak pathway are also unlikely. Flux-voltage analysis and the determination of activation enthalpy, which is dependent upon the valence of agmatine, are consistent with the hypothesis that the mitochondrial agmatine transporter is a channel or a single-binding centre-gated pore. The transport of agmatine was non-competitively inhibited by propargylamines, in particular clorgilyne, that are known to be inhibitors of MAO (monoamine oxidase). However, agmatine is normally transported in mitoplasts, thus excluding the involvement of MAO in this process. The I2 imidazoline receptor, which binds agmatine to the mitochondrial membrane, can also be excluded as a possible transporter since its inhibitor, idazoxan, was ineffective at inducing the inhibition of agmatine uptake. Scatchard analysis of membrane binding revealed two types of binding site, S1 and S2, both with mono-co-ordination, and exhibiting high-capacity and low-affinity binding for agmatine compared with polyamines. Agmatine transport in liver mitochondria may be of physiological importance as an indirect regulatory system of cytochrome c oxidase activity and as an inducer mechanism of mitochondrial-mediated apoptosis.
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Affiliation(s)
- Mauro Salvi
- *Dipartimento di Chimica Biologica, Università di Padova, Istituto di Neuroscienze del C.N.R., Unità per lo studio delle Biomembrane, 35121 Padova, Italy
| | - Valentina Battaglia
- *Dipartimento di Chimica Biologica, Università di Padova, Istituto di Neuroscienze del C.N.R., Unità per lo studio delle Biomembrane, 35121 Padova, Italy
| | - Mario Mancon
- *Dipartimento di Chimica Biologica, Università di Padova, Istituto di Neuroscienze del C.N.R., Unità per lo studio delle Biomembrane, 35121 Padova, Italy
| | - Sebastiano Colombatto
- †Dipartimento di Medicina e Oncologia Sperimentale, Sezione di Biochimica, Università di Torino, 10126 Torino, Italy
| | - Carlo Cravanzola
- †Dipartimento di Medicina e Oncologia Sperimentale, Sezione di Biochimica, Università di Torino, 10126 Torino, Italy
| | - Rita Calheiros
- ‡Unidade de Quimica-Fisica Molecular, Universidade de Coimbra, 3004-535 Coimbra, Portugal
| | - Maria P. M. Marques
- ‡Unidade de Quimica-Fisica Molecular, Universidade de Coimbra, 3004-535 Coimbra, Portugal
| | - Maria A. Grillo
- †Dipartimento di Medicina e Oncologia Sperimentale, Sezione di Biochimica, Università di Torino, 10126 Torino, Italy
| | - Antonio Toninello
- *Dipartimento di Chimica Biologica, Università di Padova, Istituto di Neuroscienze del C.N.R., Unità per lo studio delle Biomembrane, 35121 Padova, Italy
- To whom correspondence should be addressed (email )
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Hoshino K, Momiyama E, Yoshida K, Nishimura K, Sakai S, Toida T, Kashiwagi K, Igarashi K. Polyamine transport by mammalian cells and mitochondria: role of antizyme and glycosaminoglycans. J Biol Chem 2005; 280:42801-8. [PMID: 16263714 DOI: 10.1074/jbc.m505445200] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The role of antizyme (AZ) and glycosaminoglycans in polyamine uptake by mammalian cells and mitochondria was examined using NIH3T3 and FM3A cells and rat liver mitochondria. AZ is synthesized as two isoforms (29 and 24.5 kDa) due to the existence of two initiation codon AUGs in the AZ mRNA. Most AZ existed as the 24.5-kDa form translatable from the second AUG, but a portion of the 29-kDa AZ from the first AUG was associated with mitochondria because of the presence of a mitochondrial targeting signal between the first and the second methionine. The predominance of the 24.5-kDa isoform was mainly due to the presence of spermidine and a favorable sequence context (Kozak sequence) at the second initiation codon AUG. Spermine uptake by NIH3T3 cells was inhibited by both 29- and 24.5-kDa AZs, but uptake by rat liver mitochondria was not influenced by either form of AZ. Because spermine uptake by mitochondria caused a release of cytochrome c, an enhancer of apoptosis, we looked for inhibitors of mitochondrial spermine uptake other than AZ. Cations such as Na+, K+, and Mg2+ were inhibitors of the mitochondrial uptake. It has been reported that heparan sulfate on glypican-1 plays important roles in spermine uptake by human embryonic lung fibroblasts. Heparin, but not heparan sulfate, slightly inhibited spermine uptake by FM3A cells in the absence of Mg2+ and Ca2+ but had no effect under physiological conditions in the presence of Mg2+ and Ca2+.
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Affiliation(s)
- Kenji Hoshino
- Graduate School of Pharmaceutical Sciences, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba 260-8675, Japan
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19
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Salvi M, Toninello A. Effects of polyamines on mitochondrial Ca2+ transport. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2004; 1661:113-24. [PMID: 15003874 DOI: 10.1016/j.bbamem.2003.12.005] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2003] [Revised: 11/27/2003] [Accepted: 12/04/2003] [Indexed: 11/26/2022]
Abstract
Mammalian mitochondria are able to enhance Ca(2+) accumulation in the presence of polyamines by activating the saturable systems of Ca(2+) inward transport and buffering extramitochondrial Ca(2+) concentrations to levels similar to those in the cytosol of resting cells. This effect renders them responsive to regulate free Ca(2+) concentrations in the physioloical range. The mechanism involved is due to a rise in the affinity of the Ca(2+) transport system, induced by polyamines, most probably exhibiting allosteric behaviour. The regulatory site of this mechanism is the so-called S(1) binding site of polyamines, which operates in physiological conditions and is located in the energy well between the two peaks present in the energy profile of mitochondrial spermine transport. Spermine is bidirectionally transported across teh inner membrane by cycling, in which influx and efflux are driven by electrical and pH gradients, respectively. Most probably, polyamine affects the Ca(2+) transport system when it acts from the outside-that is, in the direction of its uniporter channel, in order to reach the S(1) site. Important physiological functions are related to activation of Ca(2+) transport systems by polyamines and their interactions with the S(1) site. These functions include a rise in the metabolic rate for energy supply and modulation of mitochondrial permeability transition induction, with consequent effects on the triggering of the apoptotic pathway.
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Affiliation(s)
- Mauro Salvi
- Dipartimento di Chimica Biologica, Universita' di Padova, Istituto di Neuroscienze del C.N.R., Unita' per lo Studio delle Biomembrane, Via G. Colombo 3, 35121 Padua, Italy
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20
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Salvi M, Toninello A. Reciprocal effects between spermine and Mg2+ on their movements across the mitochondrial membrane. Arch Biochem Biophys 2003; 411:262-6. [PMID: 12623075 DOI: 10.1016/s0003-9861(02)00731-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Mg(2+) competitively inhibits spermine transport in energized rat liver mitochondria (RLM) and exhibits a K(i) of 0.1mM on the initial rate and an I(50) of 0.6mM on total spermine accumulation after 20 min. Addition of 2mM Mg(2+) after spermine accumulation induces release of the polyamine. In view of the fact that spermine cycles across the inner membrane under physiological conditions, these results demonstrate that Mg(2+) inhibits spermine influx but does not affect the efflux pathway of the polyamine; the inhibitory effect occurs via an interaction with the specific site responsible for spermine transport. Instead, spermine inhibits Mg(2+) binding without affecting the rate of Mg(2+) transport, suggesting that both cations bind to the same site, which, however, is not used for Mg(2+) transport. Spermine also inhibits Mg(2+) efflux from RLM induced under conditions of the "low conductance state," a preliminary step preceding permeability transition pore opening.
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Affiliation(s)
- Mauro Salvi
- Dipartimento di Chimica Biologica, Istituto di Neuroscienze del C.N.R., Universita' di Padova, Unita' per lo Studio delle Biomembrane, Via G. Colombo 3, 35121 Padova, Italy
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21
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Salvi M, Brunati AM, Bordin L, La Rocca N, Clari G, Toninello A. Characterization and location of Src-dependent tyrosine phosphorylation in rat brain mitochondria. BIOCHIMICA ET BIOPHYSICA ACTA 2002; 1589:181-95. [PMID: 12007793 DOI: 10.1016/s0167-4889(02)00174-x] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Analysis of protein phosphorylation in highly purified rat brain mitochondria revealed the presence of several alkali-stable phosphoproteins whose phosphorylation markedly increases upon treatment with peroxovanadate and Mn(2+), a property indicating tyrosine phosphorylation. These include three prominent bands, with apparent sizes of 50, 60, and 75 kDa, which are detectable by anti-phosphotyrosine. Tyrosine phosphorylation disappears when mitochondria are treated with PP2, an inhibitor of the Src kinase family, suggesting the presence of members of this family in rat brain mitochondria. Immunoblotting and immunoprecipitation assays of mitochondrial lysates confirmed the presence of Fyn, Src and Lyn kinases, as well as Csk, a protein kinase which negatively controls the activity of the Src kinase family. Results show that tyrosine-phosphorylated proteins are membrane-bound and that they are located on the inner surface of the outer membrane and/or the external surface of the inner membrane. Instead, Src tyrosine kinases are mainly located in the intermembrane space - in particular, as revealed by immunogold experiments for Lyn kinase, in the cristal lumen. Rat brain mitochondria were also found to possess a marked level of tyrosine phosphatase activity, strongly inhibited by peroxovanadate.
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Affiliation(s)
- Mauro Salvi
- Dipartimento di Chimica Biologica, Università di Padova, Centro delle Biomembrane del CNR, Viale G. Colombo 3, 35121 Padua, Italy
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22
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Salvi M, Toninello A. The effect of methylglyoxal-bis(guanylhydrazone) on mitochondrial Ca(2+) fluxes. Biochem Pharmacol 2002; 63:247-50. [PMID: 11841799 DOI: 10.1016/s0006-2952(01)00827-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Methylglyoxal-bis(guanylhydrazone) (MGBG) induces a dose-dependent inhibition of the electrophoretic Ca(2+) uptake by rat liver mitochondria (RLM) without affecting the electrical membrane potential. MGBG is also able to inhibit the electroneutral Ca(2+) release from mitochondria. These effects result in a progressive increase of Ca(2+) level in suspending medium indicating that Ca(2+) uptake is inhibited at higher extent than Ca(2+) efflux. Spermine instead, induces a lowering of external Ca(2+) concentration. This action is reversed by MGBG which again raises the external Ca(2+) concentration then in the absence of spermine, though at a lower extent. The mechanism of MGBG effects and their implications on energy metabolism are discussed.
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Affiliation(s)
- Mauro Salvi
- Dipartimento di Chimica Biologica, Universita' di Padova, Centro di Studio delle Biomembrane del CNR, Viale G. Colombo 3, I-35121, Padova, Italy
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23
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Bordin L, Vargiu C, Clari G, Brunati AM, Colombatto S, Salvi M, Grillo MA, Toninello A. Phosphorylation of recombinant human spermidine/spermine N(1)-acetyltransferase by CK1 and modulation of its binding to mitochondria: a comparison with CK2. Biochem Biophys Res Commun 2002; 290:463-8. [PMID: 11779193 DOI: 10.1006/bbrc.2001.6204] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Cytosolic spermidine/spermine acetyltransferase (SSAT) catalyzes the acetylation of the N(1)-propylamino groups of spermine and spermidine. The enzyme has a very short half-life and is rapidly induced by various stimuli. Once acetylated, these polyamines are subjected to the action of polyamine oxidase, which, besides initiating polyamine catabolism, may produce reactive oxygen species that in turn trigger modifications in subcellular compartments such as mitochondria. The present work evaluates the ability of the cAMP-independent Ser/Thr-protein kinase CK1 to phosphorylate SSAT. Results demonstrate that SSAT is phosphorylated by CK1, in sites distinct from those phosphorylated by CK2. Moreover, both phosphorylation processes are involved in the uptake of SSAT into rat liver mitochondria. Although CK2 is less effective than CK1 in phosphorylating SSAT, CK2 phosphorylation is much more powerful in preventing binding of SSAT to mitochondrial structures. These results suggest the involvement of CK1- and CK2-mediated SSAT phosphorylation in regulating the contents of polyamines and SSAT itself within subcellular compartments and implicate SSAT and polyamines as indirect modulators of progression through the cell cycle.
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Affiliation(s)
- Luciana Bordin
- Dipartimento di Chimica Biologica, Università di Padova, Via G. Colombo 3, 35121 Padua, Italy
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24
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Toninello A, Salvi M, Colombo L. The membrane permeability transition in liver mitochondria of the great green goby Zosterisessor ophiocephalus (Pallas). J Exp Biol 2000; 203:3425-34. [PMID: 11044381 DOI: 10.1242/jeb.203.22.3425] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Liver mitochondria from the great green goby Zosterisessor ophiocephalus (Pallas) normally exhibit bioenergetic variables (membrane potential 165+/−7 mV; respiratory control ratio 6.6+/−0.4; ADP/O ratio 1.85+/−0.8; means +/− s.e.m., N=6) and activities of physiological transport systems (phosphate/proton symporter, adenine nucleotide antiporter, Ca(2+) electrophoretic uniporter) comparable with those of rat liver mitochondria. When incubated in the presence of Ca(2+) and an inducer agent such as phosphate, these mitochondria undergo a complete collapse of membrane potential accompanied by a large-amplitude swelling of the matrix, influx of sucrose from the incubation medium, release of endogenous Mg(2+) and K(+) (approximately 90% of the total) and of preaccumulated Ca(2+) and oxidation of endogenous pyridine nucleotides. All these phenomena, which are completely eliminated by cyclosporin A and inhibited with different efficacies by Mg(2+) and spermine, demonstrate that the induction of the permeability transition in this type of mitochondria has characteristics similar to those described in rat liver mitochondria. In contrast, the requirement for very high Ca(2+) concentrations (greater than 100 micromol l(−1) for the induction of the permeability transition represents a very important difference that distinguishes this phenomenon in fish and mammalian mitochondria.
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Affiliation(s)
- A Toninello
- Dipartimento di Chimica Biologica dell'Università di Padova, Centro delle Biomembrane del C.N.R., Italy.
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25
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Toninello A, Dalla Via L, Stevanato R, Yagisawa S. Kinetics and free energy profiles of spermine transport in liver mitochondria. Biochemistry 2000; 39:324-31. [PMID: 10630992 DOI: 10.1021/bi991217c] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
In the present study, the voltage-dependent mechanism of spermine transport in liver mitochondria [Toninello, A., Dalla Via, L., Siliprandi, D., and Garlid, K. D. (1992) J. Biol. Chem. 267, 18393-18397] was further characterized by determining the rate constants J(max) and K(m) as functions of membrane potential. An increase in mitochondrial membrane potential from 150 to 210 mV promoted spermine transport, as reflected by an approximate 4-fold increase in J(max) and 25% decrease in K(m). The mechanism for the voltage dependence of transport was examined using the beta value, i. e., the slope of ln(flux) vs FDeltaPsi/RT plots. Flux-voltage analyses performed at very high and very low spermine concentrations yielded beta values of 0.125 and 0.25, for J(max) and J(max)/K(m), respectively. The physical significance of these beta values was analyzed by means of a theory relating the enzyme reaction rate to the free energy profiles [Yagisawa, S. (1985) Biochem. J. 303, 305-311]. Depending on the nature of K(m), two possible models could be proposed to describe the location and shape of the barriers in the membrane. Analysis of previous data concerning spermine binding [Dalla Via, L., Di Noto, V., Siliprandi, D., and Toninello, A. (1996) Biochim. Biophys. Acta 1284, 247-252] by a new rationale provided evidence for an asymmetrical energy profile composed of two peaks with the binding site near the membrane surface followed by a rate-determining energy barrier for the movement of the bound spermine toward the internal region of the membrane.
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Affiliation(s)
- A Toninello
- Dipartimento di Chimica Biologica, Università di Padova, and Centro di Studio delle Biomembrane del C.N.R. di Padova, Viale G. Colombo 3, 35121 Padova, Italy.
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26
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Toninello A, Via LD, Di Noto V, Mancon M. The effects of methylglyoxal-bis(guanylhydrazone) on spermine binding and transport in liver mitochondria. Biochem Pharmacol 1999; 58:1899-906. [PMID: 10591144 DOI: 10.1016/s0006-2952(99)00278-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
This study evaluated the effect of the anticancer drug methylglyoxal-bis(guanylhydrazone) (MGBG) on the binding of the polyamine spermine to the mitochondrial membrane and its transport into the inner compartment of this organelle. Spermine binding was studied by applying a new thermodynamic treatment of ligand-receptor interactions (Di Noto et al., Macromol Theory Simul 5: 165-181, 1996). Results showed that MGBG inhibited the binding of spermine to the site competent for the first step in polyamine transport; the interaction of spermine with this site, termed S1, also mediates the inhibitory effect of the polyamine on the mitochondrial permeability transition (Dalla Via et al., Biochim Biophys Acta 1284: 247-252, 1996). In the presence of 1 mM MGBG, the binding capacity and affinity of this site were reduced by about 2.6-fold; on the contrary, the binding capacity of the S2 site, which is most likely responsible for the internalization of cytoplasmic proteins (see Dalla Via et al., reference cited above), increased by about 1.3-fold, and its binding affinity remained unaffected. MGBG also inhibited the initial rate of spermine transport in a dose-dependent manner by establishing apparently sigmoidal kinetics. Consequently, the total extent of spermine accumulation inside mitochondria was inhibited. This inhibition in transport seems to reflect a conformational change at the level of the channel protein constituting the polyamine transport system, rather than competitive inhibition at the inner active site of the channel, thereby excluding the possibility that the polyamine and drug use the same transport pathway. Furthermore, it is suggested that, in the presence of MGBG, the S2 site is able to participate in residual spermine transport. MGBG also strongly inhibits deltapH-dependent spermine efflux, resulting in a complete block in the bidirectional flux of the polyamine and its sequestration inside the matrix space. The effects of MGBG on spermine accumulation are consistent with in vivo disruption of the regulator of energy metabolism and replication of the mitochondrial genome.
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Affiliation(s)
- A Toninello
- Dipartimento di Chimica Biologica, Universita' di Padova, Centro di Studio Delle Biomembrane Del CNR, Padua, Italy.
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Dalla Via L, Di Noto V, Toninello A. Binding of spermidine and putrescine to energized liver mitochondria. Arch Biochem Biophys 1999; 365:231-8. [PMID: 10328817 DOI: 10.1006/abbi.1999.1170] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The binding of spermidine and putrescine to mitochondrial membranes was studied by applying a thermodynamic model of ligand-receptor interactions developed both for equilibrium and far-from-equilibrium binding processes (V. Di Noto, L. Dalla Via, A. Toninello, and M. Vidali Macromol. Theory Simul. 5, 165-181, 1996). Results demonstrate the presence of two monocoordinated binding sites (S1 and S2) for spermidine and one monocoordinated binding site (S2) for putrescine, all exhibiting high capacity and low affinity. It is proposed that differences in the polyamines' flexibility and hydrophilicity perhaps contributes to the observed variations in their interactions with the two sites. A comparison of the binding parameters of these polyamines with those of spermine reveals differences in the specific function of the S1 and S2 sites, identified in studies of spermine binding (L. Dalla Via, V. Di Noto, D. Siliprandi, and A. Toninello Biochim. Biophys. Acta 1284, 247-252, 1996).
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Affiliation(s)
- L Dalla Via
- Università di Padova, Centro di Studio delle Biomembrane del CNR di Padova, viale G. Colombo 3, Padova, 35121, Italy
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Votyakova TV, Wallace HM, Dunbar B, Wilson SB. The covalent attachment of polyamines to proteins in plant mitochondria. EUROPEAN JOURNAL OF BIOCHEMISTRY 1999; 260:250-7. [PMID: 10091605 DOI: 10.1046/j.1432-1327.1999.00147.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Plant mitochondria from both potato and mung bean incorporated radioactivity into acid insoluble material when incubated with labelled polyamines (spermine, spermidine and putrescine). Extensive washing of mitochondrial precipitates with trichloroacetic acid and the excess of cold polyamine failed to remove bound radioactivity. Addition of nonradioactive polyamine stopped further incorporation of radioactivity but did not release radioactivity already bound. The radioactivity is incorporated into the membrane fraction. The labelling process has all the features of an enzymatic reaction: it is long lasting with distinctive kinetics peculiar to each polyamine, it is temperature dependent and is affected by N-ethylmaleimide. The latter inhibits the incorporation of putrescine but stimulates the incorporation of spermine and spermidine. Treatment of prelabelled mitochondria with pepsin releases bound radioactivity thus indicating protein to be the ligand for the attachment of polyamines. HPLC of mitochondrial hydrolysates revealed that the radioactivity bound to mitochondria is polyamines; traces of acetyl polyamines were also found in some samples. On autoradiograms of SDS/PAGE gels several radioactive bands of proteins were detected. Protein sequencing of labelled spots from a 2D gel gave a sequence which was 60% identical to catalase. We suggest that the attachment of polyamines to mitochondrial proteins occurs cotranslationally possibly via transglutaminases.
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Affiliation(s)
- T V Votyakova
- Department of Molecular and Cell Biology, University of Aberdeen, Scotland
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Dalla Via L, Di Noto V, Toninello A. Spermine binding to liver mitochondria deenergized by ruthenium red plus either FCCP or antimycin A. FEBS Lett 1998; 422:36-42. [PMID: 9475165 DOI: 10.1016/s0014-5793(97)01594-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Thermodynamic analysis of spermine binding to mitochondria treated with ruthenium red and deenergized with either FCCP or antimycin A confirms the presence of two polyamine binding sites, S1 and S2, both with monocoordination, as previously observed in energized mitochondria [Dalla Via et al., Biochim. Biophys. Acta 1284 (1996) 247-252]. Both sites undergo a marked change in binding capacity and binding affinity upon mitochondrial deenergization. This change is most likely responsible for the incomplete or delayed spermine-mediated inhibition of the permeability transition induced in deenergized mitochondria.
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Affiliation(s)
- L Dalla Via
- Dipartimento di Scienze Farmaceutiche, Università di Padova, Padua, Italy
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Dalla Via L, Di Noto V, Siliprandi D, Toninello A. Spermine binding to liver mitochondria. BIOCHIMICA ET BIOPHYSICA ACTA 1996; 1284:247-52. [PMID: 8914591 DOI: 10.1016/s0005-2736(96)00140-x] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Non-equilibrium binding of spermine to mitochondrial membranes is studied in rat liver mitochondria by applying a new thermodynamic treatment of ligand-receptor interactions (Di Noto, V., Dalla Via, L., Toninello, A. and Vidali, M. (1996) Macromol. Theory Simul. 5, 165-181). The presence on mitochondrial membranes of two spermine binding sites, both with monocoordination, is demonstrated. The calculated binding energy is characteristic for weak interactions. The treatment allows also to evaluate the variations of the molar fraction ratio of spermine bound to sites 1 and 2 as function of total bound spermine. The possible role of the two sites is discussed.
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Affiliation(s)
- L Dalla Via
- Dipartimento di Chimica Biologica, Università di Padova, Italy
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Luvisetto S, Schemehl I, Canton M, Azzone GF. The effect of respiration on the permeability of the mitochondrial membrane to ions. BIOCHIMICA ET BIOPHYSICA ACTA 1994; 1186:12-8. [PMID: 8011661 DOI: 10.1016/0005-2728(94)90129-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
1. The rates of cation uptake, for either organic cations such as tetrapropylammonium, TPA+, at variable tetraphenylboron concentrations, TPB-, or inorganic cations such as Mn2+, or K+ plus valinomycin, have been measured in mitochondria either respiring, under uncoupler titrations, or non-respiring, under variable K+ diffusion potentials. 2. The flow-force relationship for the respiration-coupled ion fluxes during titrations with uncouplers is almost identical to that obtained for the K(+)-diffusion driven fluxes. Similar results are obtained when TPA+ is replaced with inorganic cations, either monovalent such as K+ (+valinomycin), or divalent such as Mn2+. 3. By applying the Eyring analysis, as developed by Garlid et al. (Garlid, K.D., Beavis, A.D. and Ratkje, S.K. (1989) Biochim. Biophys. Acta 976, 109-121), from the flux-voltage relationships the values for the permeability coefficients and for the energy barriers have been obtained for the transport of the ion pair TPA(+)-TPB-, of Mn2+ and of K+ plus valinomycin, in non-respiring and in respiring, coupled and uncoupled, mitochondria. 4. The findings that the rates of respiration-coupled ion fluxes, at all values of membrane potential, are similar to the rates of the K+ diffusion potential-coupled ion fluxes and the similar pattern of the flux-voltage relationships during the titrations with uncouplers and artificial gradients indicate that the membrane permeability for ions is not modified by respiration.
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Affiliation(s)
- S Luvisetto
- C.N.R. Unit for the Study of Physiology of Mitochondria, University of Padova, Italy
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Bordin L, Cattapan F, Clari G, Toninello A, Siliprandi N, Moret V. Spermine-mediated casein kinase II-uptake by rat liver mitochondria. BIOCHIMICA ET BIOPHYSICA ACTA 1994; 1199:266-70. [PMID: 7718030 DOI: 10.1016/0304-4165(94)90005-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Spermine, ubiquitous intracellular polyamine, is able to promote the transmembrane translocation of casein kinase CKII through the outer membrane of rat liver mitochondria and its binding to more internal mitochondrial structures. These findings suggest that spermine may play a critical role in regulating the subcellular distribution of casein kinase CKII.
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Affiliation(s)
- L Bordin
- Istituto di Medicina Interna, Università di Padova, Italy
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33
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Jarzyna R, Lietz T, Bryła J. Effect of polyamines on glutamate dehydrogenase within permeabilized kidney-cortex mitochondria and isolated renal tubules of rabbit. Biochem Pharmacol 1994; 47:1387-93. [PMID: 7910459 DOI: 10.1016/0006-2952(94)90338-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The effect of polyamines on glutamate dehydrogenase [L-glutamate: NAD(P) oxidoreductase (deaminating) [EC 1.4.1.3]) activity has been studied in both permeabilized kidney-cortex mitochondria and isolated renal tubules of rabbit. Spermidine was the most potent inhibitor of glutamate synthesis in permeabilized mitochondria resulting in about 80% decrease of the enzyme activity at 5 mM concentration. Putrescine, alpha-monofluoromethylputrescine (MFMP) and (R,R)-delta-methyl-alpha-acetylenic-putrescine (MAP) were more efficient than spermine. The inhibitory action of polyamines was potentiated by an elevated NADH content in the reaction mixture. Increasing concentrations of either NH4Cl, KCl or NaCl in the incubation medium resulted in a decrease of polyamine-induced inhibition of the enzyme activity, indicating that monovalent cations can compete with polyamines for the binding site at glutamate dehydrogenase. The inhibitory action of spermidine on glutamate synthesis was abolished by 2 mM ADP or 10 mM L-leucine, allosteric activators of the enzyme, as well as on the addition of either oxalate or sulphate at 20 mM concentrations. Spermidine did not affect glutamate formation when NADH was substituted by NADPH, suggesting an importance of the NADH binding to the inhibitory site of the enzyme for a decrease of reductive amination of 2-oxoglutarate by polyamine. Although spermidine did not influence glutamate deamination in the presence of NAD+, it stimulated this process by about 70% when NAD+ was substituted by NADP+. In the presence of ADP the stimulatory effect of polyamine was not significant. The data indicate that in permeabilized rabbit kidney-cortex mitochondria the effect of polyamines on both glutamate formation and glutamate deamination via the reaction catalysed by glutamate dehydrogenase is dependent upon the coenzyme utilized by the enzyme. In the presence of NADH their inhibitory effect on the glutamate formation may be alleviated by allosteric activators of the enzyme, and concentrations of potassium, sodium, sulphate and oxalate. In isolated rabbit renal tubules incubated with 5 mM methionine sulfoximine and aminooxyacetate, in order to inhibit glutamine synthetase and aminotransferases, respectively, 5 mM spermidine decreased glutamate formation by about 30%, while putrescine and spermine did not significantly diminish the enzyme activity. In the presence of octanoate glutamate formation was reduced by about 30% by naturally occurring polyamines as well as MFMP and MAP, indicating that under these conditions NADH rather than NADPH is utilized as the coenzyme. In view of these data it is possible to suggest that polyamines may be of importance to control glutamate dehydrogenase activity under physiological conditions.
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Affiliation(s)
- R Jarzyna
- Institute of Biochemistry, Warsaw University, Poland
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34
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Votyakova TV, Bazhenova EN, Zvjagilskaya RA. Yeast mitochondrial calcium uptake: regulation by polyamines and magnesium ions. J Bioenerg Biomembr 1993; 25:569-74. [PMID: 8132496 DOI: 10.1007/bf01108413] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Spermine, spermidine, and magnesium ions modulate the kinetic parameters of the Ca2+ transport system of Endomyces magnusii mitochondria. Mg2+ at concentrations up to 5 mM partially inhibits Ca2+ transport with a half-maximal inhibiting concentration of approximately 0.5 mM. In the presence of 2 mM MgCl2, the S0.5 value of the Ca2+ transport system increases from 220 to 490 microM, which indicates decreased affinity for the system. Spermine and spermidine exert an activating effect, having half-maximal concentrations of 12 and 50 microM, respectively. In the case of spermine, the S0.5 value falls to 50-65 microM, which implies an increase in the transport system affinity for Ca2+. Both Mg2+ and spermine cause a decrease of the Hill coefficient, giving evidence for a smaller degree of cooperativity. Spermine and spermidine enable yeast mitochondria to remove Ca2+ from the media completely. In contrast, Mg2+ lowers the mitochondrial buffer capacity. When both Mg2+ and spermine are present in the medium, their effects on the S0.5 value and the free extramitochondrial Ca2+ concentration are additive. The ability of spermine and Mg2+ to regulate yeast mitochondrial Ca2+ transport is discussed.
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Affiliation(s)
- T V Votyakova
- A. N. Bach Institute of Biochemistry, Russian Academy of Sciences, Moscow
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35
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Evidence that spermine, spermidine, and putrescine are transported electrophoretically in mitochondria by a specific polyamine uniporter. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(19)36975-3] [Citation(s) in RCA: 68] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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36
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Sun X, Garlid K. On the mechanism by which bupivacaine conducts protons across the membranes of mitochondria and liposomes. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(18)41754-1] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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37
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Siliprandi D, Toninello A, Dalla Via L. Bidirectional transport of spermine in rat liver mitochondria. BIOCHIMICA ET BIOPHYSICA ACTA 1992; 1102:62-6. [PMID: 1510993 DOI: 10.1016/0005-2728(92)90065-a] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Further study of the mitochondrial transport of spermine (Toninello et al. (1988) J. Biol. Chem. 263, 19407) shows that, after loading rat liver mitochondria with [14C]spermine and [32P]phosphate, these components are released together into the surrounding medium by adding mersalyl or N-ethylmaleimide. On later addition of dithioerythritol, both are recaptured, but if acetate or nigericin are added instead, only spermine re-enters and there is continued export of phosphate. This bidirectional transport of spermine in and out mitochondria is driven, respectively, by membrane potential and pH gradient at constant protonmotive force. Results using [14C]spermine or [32P]phosphate, in conjunction with the their unlabelled isomers and with or without carbonyl cyanide/p-trifuloromethoxyphenylhydrazone (FCCP) present suggest that there is a continuous energy-dependent efflux-influx cycling of spermine and phosphate.
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Affiliation(s)
- D Siliprandi
- Dipartimento di Chimica Biologica Universita' di Padova, Italy
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38
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Abstract
In spite of their abundance, the function of PAs in the adult nervous system remains enigmatic. It is postulated that after trauma, the induction of polyamine metabolism (i.e. the polyamine response), which is inherently transient, is an integral part of a protective biochemical program that is essential for neuronal survival. Several functions ascribed to PAs may assume importance in cellular defense. Thus, regulation of the ionic environment, modulation of signal pathways, control of cellular Ca2+ homeostasis, inhibition of lipid peroxidation, and interaction with nucleic acids are all putative sites for PA action. During maturation, the CNS, unlike the peripheral nervous system, undergoes changes which result in the expression of an incomplete polyamine response after trauma. This may be due to an altered pattern of gene expression, and/or restrictive compartmentalization of the PAs and their metabolizing enzymes. Induction of this partial polyamine response after injury results in a sustained accumulation of putrescine, which by itself may be harmful, without the concomitant increase in spermidine and spermine. Administration of exogenous PAs after trauma exerts a neuroprotective effect. Exogenous PAs are postulated to gain access into cells via an induced uptake system after trauma, and function similarly to newly synthesized PAs. Besides the injured neurons themselves, tissues which are connected or associated with these neurons may be potential targets where PAs could act to stimulate neurotrophic factor production. Based on the neuroprotective effects of PAs in laboratory animals and on their proposed role in mechanisms of neuronal survival, the development of PA-based compounds as therapeutic neuroprotective agents should be pursued.
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Affiliation(s)
- G M Gilad
- Neuropsychiatry Branch, NIMH Neurosciences Center at Saint Elizabeths, Washington, DC 20032
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39
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Luvisetto S, Schmehl I, Intravaia E, Conti E, Azzone G. Mechanism of loss of thermodynamic control in mitochondria due to hyperthyroidism and temperature. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(19)49540-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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40
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Kakinuma Y, Masuda N, Igarashi K. Proton potential-dependent polyamine transport by vacuolar membrane vesicles of Saccharomyces cerevisiae. BIOCHIMICA ET BIOPHYSICA ACTA 1992; 1107:126-30. [PMID: 1319738 DOI: 10.1016/0005-2736(92)90337-l] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Vacuolar membrane vesicles of Saccharomyces cerevisiae accumulated spermine and spermidine in the presence of ATP, not in the presence of ADP. Spermine and spermidine transport at pH 7.4 showed saturation kinetics with Km values of 0.2 mM and 0.7 mM, respectively. Spermine uptake was competitively inhibited by spermidine and putrescine, but was not affected by seven amino acids, substrates of active transport systems of vacuolar membrane. Spermine transport was inhibited by the H(+)-ATPase-specific inhibitors bafilomycin A1 and N,N'-dicyclohexylcarbodiimide, but not by vanadate. It was also sensitive to Cu2+ or Zn2+ ions, inhibitors of vacuolar H(+)-ATPase. Both 3,5-di-tert-butyl-4-hydroxybenzilidenemalononitrile (SF6847) and nigericin blocked completely the spermine uptake, but valinomycin did not. [14C]Spermine accumulated in the vesicles was exchangeable with unlabeled spermine and spermidine. However, it was released by a protonophore only in the presence of a counterion such as Ca2+. These results indicate that a polyamine-specific transport system depending on a proton potential functions in the vacuolar membrane of this organism.
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Affiliation(s)
- Y Kakinuma
- Faculty of Pharmaceutical Sciences, Chiba University, Japan
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41
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Abstract
We have investigated the kinetics of interaction of cationic fluorescent lipophiles (dyes) rhodamine 123, rhodamine 6G, tetramethyl rhodamine ethyl ester, safranine O, 1,1'-diethyloxacarbocyanine, 1,1'-diethyloxadicarbocyanine, and 1,1'-diethylthiadicarbocyanine iodide with isolated respiring rat-liver mitochondria (RLM). Dye flux across the RLM inner membrane was measured by following the kinetics of fluorescence signal change after mixing of dye and RLM. The time course of fluorescence was analysed in terms of a kinetic model of the binding and transport processes involved. The rate constants of dye influx and efflux were extracted from the observed effect on the apparent time constant of fluorescence change to equilibrium intensity upon mixing dye with increasing concentrations of RLM. From the influx rate constants obtained, the apparent permeability constants for dye influx (at zero potential) across the membrane were calculated and ranged from 3 to 140 x 10(-4) cm/s. The influx rate constant was found to be linearly related to relative dye lipophilicity, as predicted by the model. As another test of the model, from the ratio of the influx and efflux rate constants, the apparent trans-membrane potential, psi, was calculated and found generally to agree with reported values, but to depend on the lipophilicity of the dye used. Not predicted by the simple model was a dissymmtry observed in the influx and efflux time constants for fluorescence change to equilibrium intensity. Inferences are made relating to the utility of these dyes as probes of psi.
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43
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Watanabe S, Kusama-Eguchi K, Kobayashi H, Igarashi K. Estimation of polyamine binding to macromolecules and ATP in bovine lymphocytes and rat liver. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(18)54780-3] [Citation(s) in RCA: 101] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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44
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Rottenberg H, Marbach M. Regulation of Ca2+ transport in brain mitochondria. I. The mechanism of spermine enhancement of Ca2+ uptake and retention. BIOCHIMICA ET BIOPHYSICA ACTA 1990; 1016:77-86. [PMID: 2310743 DOI: 10.1016/0005-2728(90)90009-s] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Spermine enhances electrogenic Ca2+ uptake and inhibits Na(+)-independent Ca2+ efflux in rat brain mitochondria. As a result, Ca2+ retention by brain mitochondria increases greatly and the external free Ca2+ level at steady-state can be lowered to physiologically relevant concentrations. The stimulation of Ca2+ uptake by spermine is more pronounced at low concentrations of Ca2+, effectively lowering the apparent Km for Ca2+ uptake from 3 microM to 1.5 microM. However, the apparent Vmax is also increased. At low Ca2+ concentrations, Ca2+ uptake is diffusion-limited. Spermine strongly inhibits Ca2+ binding to anionic phospholipids and it is suggested that this increases the rate of surface diffusion which reduces the apparent Km for uptake. The same effect could inhibit the Na(+)-independent efflux if the rate of efflux is limited by Ca2+ dissociation from the efflux carrier. In brain mitochondria (but not in liver) the spermine effect depends on the presence of ADP. In a medium that contains physiological concentrations of Pi, Mg+, K+, ADP and spermine, brain mitochondria sequester Ca2+ down to 0.1 microM and below, depending on the matrix Ca2+ load. Moreover, brain mitochondria under the same conditions buffer the external medium at 0.4 microM, a concentration at which the set point becomes independent of the matrix Ca2+ content. Thus, mitochondria appear to be capable of modulating calcium oscillations in brain cells.
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Affiliation(s)
- H Rottenberg
- Pathology Department, Hahnemann University, Philadelphia, PA 19102
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45
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Bernardi P, Angrilli A, Azzone GF. A gated pathway for electrophoretic Na+ fluxes in rat liver mitochondria. Regulation by surface Mg2+. EUROPEAN JOURNAL OF BIOCHEMISTRY 1990; 188:91-7. [PMID: 2156695 DOI: 10.1111/j.1432-1033.1990.tb15375.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Addition of EDTA to mitochondria incubated aerobically in a phosphate-supplemented medium containing Na+ ions results in activation of cation uptake which is accompanied by membrane depolarization and stimulation of respiration. The same results are obtained in media containing Li+ but not K+, indicating that this pathway for cation transport is selective. The activation of Na+ transport is not accompanied by changes of matrix Mg2+, indicating that cation transport is controlled by surface-bound rather than intramitochondrial Mg2+. Na+ transport in respiring mitochondria is competitively inhibited by Mg2+ with a Ki in the nanomolar range. A Na+ current can also be induced by a K+ diffusion potential in the absence of respiration. The K(+)-diffusion-driven Na+ current has the same magnitude in the absence or presence of inorganic phosphate, suggesting that Na+ transport is mediated by Na+ uniport rather than by electrogenic nNa+/H+ antiport with n greater than 1. Analysis of the flow/force relationship indicates that the putative Na+ uniporter has a conductance of about 0.2 nmol Na+ x mg protein-1 x min-1 x mV-1, and that it is active only when the membrane potential exceeds about 150 mV.
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Affiliation(s)
- P Bernardi
- Consiglio Nazionale delle Ricerche Unit, University of Padova, Italy
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46
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Beavis AD, Garlid KD. Evidence for the allosteric regulation of the mitochondrial K+/H+ antiporter by matrix protons. J Biol Chem 1990. [DOI: 10.1016/s0021-9258(19)39834-5] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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47
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Garlid KD, Beavis AD, Ratkje SK. On the nature of ion leaks in energy-transducing membranes. BIOCHIMICA ET BIOPHYSICA ACTA 1989; 976:109-20. [PMID: 2675980 DOI: 10.1016/s0005-2728(89)80219-1] [Citation(s) in RCA: 94] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Diffusion is the implicit null hypothesis for ion transport across biological membranes. A proper model of ionic diffusion across the permeability barrier is needed to distinguish among leaks, channels and carriers and to determine whether changes in flux reflect changes in permeability (regulation) or merely changes in the driving force. These issues arise in all biomembranes, but they are particularly confounding in energy-transducing membranes on account of their characteristically high electrical gradients. This paper examines the nature of the barrier to ion leaks, using the classical Eyring rate theory. We introduce new practical procedures for estimating permeability coefficients from ion flux data. We also reach some general conclusions regarding ion leaks across energy-transducing membranes. (1) The dependence of ion flux on the electrical membrane potential is invariably non-linear (non-ohmic). (2) Non-ohmic behavior does not imply variable permeability. (3) Ohmic behavior is exceptional and its occurrence should alert us to the possibility of an underlying carrier or channel. (4) Leak pathways are very likely localized to protein-lipid interfaces and will exhibit quasi-specific properties such as saturation and competition. (5) The inherent non-ohmicity of leaks and the requirement for efficient energy transduction impose constraints upon the magnitude of allowable Gibbs free-energy changes in biological systems. (6) Nature adapts to these constraints by devising mechanisms for step-wise splitting of the partial reactions of energy transduction.
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Affiliation(s)
- K D Garlid
- Department of Pharmacology, Medical College of Ohio, Toledo 43699-0008
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48
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Toninello A, Siliprandi D, Castagnini P, Novello MC, Siliprandi N. Bidirectional transport of spermine across the inner membrane of liver mitochondria. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1988; 250:491-6. [PMID: 3076335 DOI: 10.1007/978-1-4684-5637-0_43] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Affiliation(s)
- A Toninello
- Centro Studio Fisiologia Mitocondriale CNR, Padova
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