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Zorova LD, Abramicheva PA, Andrianova NV, Babenko VA, Zorov SD, Pevzner IB, Popkov VA, Semenovich DS, Yakupova EI, Silachev DN, Plotnikov EY, Sukhikh GT, Zorov DB. Targeting Mitochondria for Cancer Treatment. Pharmaceutics 2024; 16:444. [PMID: 38675106 PMCID: PMC11054825 DOI: 10.3390/pharmaceutics16040444] [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: 02/28/2024] [Accepted: 03/20/2024] [Indexed: 04/28/2024] Open
Abstract
There is an increasing accumulation of data on the exceptional importance of mitochondria in the occurrence and treatment of cancer, and in all lines of evidence for such participation, there are both energetic and non-bioenergetic functional features of mitochondria. This analytical review examines three specific features of adaptive mitochondrial changes in several malignant tumors. The first feature is characteristic of solid tumors, whose cells are forced to rebuild their energetics due to the absence of oxygen, namely, to activate the fumarate reductase pathway instead of the traditional succinate oxidase pathway that exists in aerobic conditions. For such a restructuring, the presence of a low-potential quinone is necessary, which cannot ensure the conventional conversion of succinate into fumarate but rather enables the reverse reaction, that is, the conversion of fumarate into succinate. In this scenario, complex I becomes the only generator of energy in mitochondria. The second feature is the increased proliferation in aggressive tumors of the so-called mitochondrial (peripheral) benzodiazepine receptor, also called translocator protein (TSPO) residing in the outer mitochondrial membrane, the function of which in oncogenic transformation stays mysterious. The third feature of tumor cells is the enhanced retention of certain molecules, in particular mitochondrially directed cations similar to rhodamine 123, which allows for the selective accumulation of anticancer drugs in mitochondria. These three features of mitochondria can be targets for the development of an anti-cancer strategy.
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Affiliation(s)
- Ljubava D. Zorova
- A.N. Belozersky Research Institute of Physico-Chemical Biology, Lomonosov Moscow State University, 119991 Moscow, Russia; (L.D.Z.); (P.A.A.); (V.A.B.); (S.D.Z.); (I.B.P.); (V.A.P.); (D.S.S.); (E.I.Y.); (D.N.S.); (E.Y.P.)
- V.I. Kulakov National Medical Research Center of Obstetrics, Gynecology and Perinatology, 117997 Moscow, Russia
| | - Polina A. Abramicheva
- A.N. Belozersky Research Institute of Physico-Chemical Biology, Lomonosov Moscow State University, 119991 Moscow, Russia; (L.D.Z.); (P.A.A.); (V.A.B.); (S.D.Z.); (I.B.P.); (V.A.P.); (D.S.S.); (E.I.Y.); (D.N.S.); (E.Y.P.)
| | - Nadezda V. Andrianova
- A.N. Belozersky Research Institute of Physico-Chemical Biology, Lomonosov Moscow State University, 119991 Moscow, Russia; (L.D.Z.); (P.A.A.); (V.A.B.); (S.D.Z.); (I.B.P.); (V.A.P.); (D.S.S.); (E.I.Y.); (D.N.S.); (E.Y.P.)
| | - Valentina A. Babenko
- A.N. Belozersky Research Institute of Physico-Chemical Biology, Lomonosov Moscow State University, 119991 Moscow, Russia; (L.D.Z.); (P.A.A.); (V.A.B.); (S.D.Z.); (I.B.P.); (V.A.P.); (D.S.S.); (E.I.Y.); (D.N.S.); (E.Y.P.)
- V.I. Kulakov National Medical Research Center of Obstetrics, Gynecology and Perinatology, 117997 Moscow, Russia
| | - Savva D. Zorov
- A.N. Belozersky Research Institute of Physico-Chemical Biology, Lomonosov Moscow State University, 119991 Moscow, Russia; (L.D.Z.); (P.A.A.); (V.A.B.); (S.D.Z.); (I.B.P.); (V.A.P.); (D.S.S.); (E.I.Y.); (D.N.S.); (E.Y.P.)
- Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, 119991 Moscow, Russia
| | - Irina B. Pevzner
- A.N. Belozersky Research Institute of Physico-Chemical Biology, Lomonosov Moscow State University, 119991 Moscow, Russia; (L.D.Z.); (P.A.A.); (V.A.B.); (S.D.Z.); (I.B.P.); (V.A.P.); (D.S.S.); (E.I.Y.); (D.N.S.); (E.Y.P.)
- V.I. Kulakov National Medical Research Center of Obstetrics, Gynecology and Perinatology, 117997 Moscow, Russia
| | - Vasily A. Popkov
- A.N. Belozersky Research Institute of Physico-Chemical Biology, Lomonosov Moscow State University, 119991 Moscow, Russia; (L.D.Z.); (P.A.A.); (V.A.B.); (S.D.Z.); (I.B.P.); (V.A.P.); (D.S.S.); (E.I.Y.); (D.N.S.); (E.Y.P.)
- V.I. Kulakov National Medical Research Center of Obstetrics, Gynecology and Perinatology, 117997 Moscow, Russia
| | - Dmitry S. Semenovich
- A.N. Belozersky Research Institute of Physico-Chemical Biology, Lomonosov Moscow State University, 119991 Moscow, Russia; (L.D.Z.); (P.A.A.); (V.A.B.); (S.D.Z.); (I.B.P.); (V.A.P.); (D.S.S.); (E.I.Y.); (D.N.S.); (E.Y.P.)
| | - Elmira I. Yakupova
- A.N. Belozersky Research Institute of Physico-Chemical Biology, Lomonosov Moscow State University, 119991 Moscow, Russia; (L.D.Z.); (P.A.A.); (V.A.B.); (S.D.Z.); (I.B.P.); (V.A.P.); (D.S.S.); (E.I.Y.); (D.N.S.); (E.Y.P.)
| | - Denis N. Silachev
- A.N. Belozersky Research Institute of Physico-Chemical Biology, Lomonosov Moscow State University, 119991 Moscow, Russia; (L.D.Z.); (P.A.A.); (V.A.B.); (S.D.Z.); (I.B.P.); (V.A.P.); (D.S.S.); (E.I.Y.); (D.N.S.); (E.Y.P.)
| | - Egor Y. Plotnikov
- A.N. Belozersky Research Institute of Physico-Chemical Biology, Lomonosov Moscow State University, 119991 Moscow, Russia; (L.D.Z.); (P.A.A.); (V.A.B.); (S.D.Z.); (I.B.P.); (V.A.P.); (D.S.S.); (E.I.Y.); (D.N.S.); (E.Y.P.)
- V.I. Kulakov National Medical Research Center of Obstetrics, Gynecology and Perinatology, 117997 Moscow, Russia
| | - Gennady T. Sukhikh
- V.I. Kulakov National Medical Research Center of Obstetrics, Gynecology and Perinatology, 117997 Moscow, Russia
| | - Dmitry B. Zorov
- A.N. Belozersky Research Institute of Physico-Chemical Biology, Lomonosov Moscow State University, 119991 Moscow, Russia; (L.D.Z.); (P.A.A.); (V.A.B.); (S.D.Z.); (I.B.P.); (V.A.P.); (D.S.S.); (E.I.Y.); (D.N.S.); (E.Y.P.)
- V.I. Kulakov National Medical Research Center of Obstetrics, Gynecology and Perinatology, 117997 Moscow, Russia
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2
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Endlicher R, Drahota Z, Štefková K, Červinková Z, Kučera O. The Mitochondrial Permeability Transition Pore-Current Knowledge of Its Structure, Function, and Regulation, and Optimized Methods for Evaluating Its Functional State. Cells 2023; 12:cells12091273. [PMID: 37174672 PMCID: PMC10177258 DOI: 10.3390/cells12091273] [Citation(s) in RCA: 14] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2023] [Revised: 04/19/2023] [Accepted: 04/25/2023] [Indexed: 05/15/2023] Open
Abstract
The mitochondrial permeability transition pore (MPTP) is a calcium-dependent, ion non-selective membrane pore with a wide range of functions. Although the MPTP has been studied for more than 50 years, its molecular structure remains unclear. Short-term (reversible) opening of the MPTP protects cells from oxidative damage and enables the efflux of Ca2+ ions from the mitochondrial matrix and cell signaling. However, long-term (irreversible) opening induces processes leading to cell death. Ca2+ ions, reactive oxygen species, and changes in mitochondrial membrane potential regulate pore opening. The sensitivity of the pore to Ca2+ ions changes as an organism ages, and MPTP opening plays a key role in the pathogenesis of many diseases. Most studies of the MPTP have focused on elucidating its molecular structure. However, understanding the mechanisms that will inhibit the MPTP may improve the treatment of diseases associated with its opening. To evaluate the functional state of the MPTP and its inhibitors, it is therefore necessary to use appropriate methods that provide reproducible results across laboratories. This review summarizes our current knowledge of the function and regulation of the MPTP. The latter part of the review introduces two optimized methods for evaluating the functional state of the pore under standardized conditions.
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Affiliation(s)
- René Endlicher
- Department of Physiology, Faculty of Medicine in Hradec Králové, Charles University, 500 03 Hradec Králové, Czech Republic
- Department of Anatomy, Faculty of Medicine in Hradec Králové, Charles University, 500 03 Hradec Králové, Czech Republic
| | - Zdeněk Drahota
- Department of Physiology, Faculty of Medicine in Hradec Králové, Charles University, 500 03 Hradec Králové, Czech Republic
- Institute of Physiology, Czech Academy of Sciences, 142 00 Prague, Czech Republic
| | - Kateřina Štefková
- Department of Anatomy, Faculty of Medicine in Hradec Králové, Charles University, 500 03 Hradec Králové, Czech Republic
| | - Zuzana Červinková
- Department of Physiology, Faculty of Medicine in Hradec Králové, Charles University, 500 03 Hradec Králové, Czech Republic
| | - Otto Kučera
- Department of Physiology, Faculty of Medicine in Hradec Králové, Charles University, 500 03 Hradec Králové, Czech Republic
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Solhjoo S, Liu T, Sidor A, Lee DI, O'Rourke B, Steenbergen C. Oxidative stress in the mitochondrial matrix underlies ischemia/reperfusion-induced mitochondrial instability. J Biol Chem 2022; 299:102780. [PMID: 36496071 PMCID: PMC9852550 DOI: 10.1016/j.jbc.2022.102780] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2022] [Revised: 11/28/2022] [Accepted: 11/30/2022] [Indexed: 12/12/2022] Open
Abstract
Ischemia and reperfusion affect multiple elements of cardiomyocyte electrophysiology, especially within the mitochondria. We previously showed that in cardiac monolayers, upon reperfusion after coverslip-induced ischemia, mitochondrial inner membrane potential (ΔΨ) unstably oscillates between polarized and depolarized states, and ΔΨ instability corresponds with arrhythmias. Here, through confocal microscopy of compartment-specific molecular probes, we investigate the mechanisms underlying the postischemic ΔΨ oscillations, focusing on the role of Ca2+ and oxidative stress. During reperfusion, transient ΔΨ depolarizations occurred concurrently with periods of increased mitochondrial oxidative stress (5.07 ± 1.71 oscillations/15 min, N = 100). Supplementing the antioxidant system with GSH monoethyl ester suppressed ΔΨ oscillations (1.84 ± 1.07 oscillations/15 min, N = 119, t test p = 0.027) with 37% of mitochondrial clusters showing no ΔΨ oscillations (versus 4% in control, odds ratio = 14.08, Fisher's exact test p < 0.001). We found that limiting the production of reactive oxygen species using cyanide inhibited postischemic ΔΨ oscillations (N = 15, t test p < 10-5). Furthermore, ΔΨ oscillations were not associated with any discernable pattern in cell-wide oxidative stress or with the changes in cytosolic or mitochondrial Ca2+. Sustained ΔΨ depolarization followed cytosolic and mitochondrial Ca2+ increase and was associated with increased cell-wide oxidative stress. Collectively, these findings suggest that transient bouts of increased mitochondrial oxidative stress underlie postischemic ΔΨ oscillations, regardless of Ca2+ dynamics.
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Affiliation(s)
- Soroosh Solhjoo
- Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
| | - Ting Liu
- Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Agnieszka Sidor
- Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Dong I Lee
- Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Brian O'Rourke
- Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
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Bernardi P, Carraro M, Lippe G. The mitochondrial permeability transition: Recent progress and open questions. FEBS J 2022; 289:7051-7074. [PMID: 34710270 PMCID: PMC9787756 DOI: 10.1111/febs.16254] [Citation(s) in RCA: 67] [Impact Index Per Article: 33.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Accepted: 10/27/2021] [Indexed: 01/13/2023]
Abstract
Major progress has been made in defining the basis of the mitochondrial permeability transition, a Ca2+ -dependent permeability increase of the inner membrane that has puzzled mitochondrial research for almost 70 years. Initially considered an artefact of limited biological interest by most, over the years the permeability transition has raised to the status of regulator of mitochondrial ion homeostasis and of druggable effector mechanism of cell death. The permeability transition is mediated by opening of channel(s) modulated by matrix cyclophilin D, the permeability transition pore(s) (PTP). The field has received new impulse (a) from the hypothesis that the PTP may originate from a Ca2+ -dependent conformational change of F-ATP synthase and (b) from the reevaluation of the long-standing hypothesis that it originates from the adenine nucleotide translocator (ANT). Here, we provide a synthetic account of the structure of ANT and F-ATP synthase to discuss potential and controversial mechanisms through which they may form high-conductance channels; and review some intriguing findings from the wealth of early studies of PTP modulation that still await an explanation. We hope that this review will stimulate new experiments addressing the many outstanding problems, and thus contribute to the eventual solution of the puzzle of the permeability transition.
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Affiliation(s)
- Paolo Bernardi
- Department of Biomedical Sciences and CNR Neuroscience InstituteUniversity of PadovaItaly
| | - Michela Carraro
- Department of Biomedical Sciences and CNR Neuroscience InstituteUniversity of PadovaItaly
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5
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Molecular mechanisms and consequences of mitochondrial permeability transition. Nat Rev Mol Cell Biol 2022; 23:266-285. [PMID: 34880425 DOI: 10.1038/s41580-021-00433-y] [Citation(s) in RCA: 187] [Impact Index Per Article: 93.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/29/2021] [Indexed: 12/29/2022]
Abstract
Mitochondrial permeability transition (mPT) is a phenomenon that abruptly causes the flux of low molecular weight solutes (molecular weight up to 1,500) across the generally impermeable inner mitochondrial membrane. The mPT is mediated by the so-called mitochondrial permeability transition pore (mPTP), a supramolecular entity assembled at the interface of the inner and outer mitochondrial membranes. In contrast to mitochondrial outer membrane permeabilization, which mostly activates apoptosis, mPT can trigger different cellular responses, from the physiological regulation of mitophagy to the activation of apoptosis or necrosis. Although there are several molecular candidates for the mPTP, its molecular nature remains contentious. This lack of molecular data was a significant setback that prevented mechanistic insight into the mPTP, pharmacological targeting and the generation of informative animal models. In recent years, experimental evidence has highlighted mitochondrial F1Fo ATP synthase as a participant in mPTP formation, although a molecular model for its transition to the mPTP is still lacking. Recently, the resolution of the F1Fo ATP synthase structure by cryogenic electron microscopy led to a model for mPTP gating. The elusive molecular nature of the mPTP is now being clarified, marking a turning point for understanding mitochondrial biology and its pathophysiological ramifications. This Review provides an up-to-date reference for the understanding of the mammalian mPTP and its cellular functions. We review current insights into the molecular mechanisms of mPT and validated observations - from studies in vivo or in artificial membranes - on mPTP activity and functions. We end with a discussion of the contribution of the mPTP to human disease. Throughout the Review, we highlight the multiple unanswered questions and, when applicable, we also provide alternative interpretations of the recent discoveries.
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Palzur E, Edelman D, Sakas R, Soustiel JF. Etifoxine Restores Mitochondrial Oxidative Phosphorylation and Improves Cognitive Recovery Following Traumatic Brain Injury. Int J Mol Sci 2021; 22:12881. [PMID: 34884686 PMCID: PMC8657969 DOI: 10.3390/ijms222312881] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2021] [Revised: 11/22/2021] [Accepted: 11/23/2021] [Indexed: 12/05/2022] Open
Abstract
The opening of the mitochondrial permeability transition pore (mPTP) has emerged as a pivotal event following traumatic brain injury (TBI). Evidence showing the impact of the translocator protein (TSPO) over mPTP activity has prompted several studies exploring the effect of TSPO ligands, including etifoxine, on the outcome of traumatic brain injury (TBI). Mitochondrial respiration was assessed by respirometry in isolated rat brain mitochondria (RBM) by measurements of oxidative phosphorylation capacity (OXPHOS). The addition of calcium to RBM was used to induce mitochondrial injury and resulted in significant OXPHOS reduction that could be reversed by preincubation of RBM with etifoxine. Sensorimotor and cognitive functions were assessed following controlled cortical impact and compared in vehicle and etifoxine-treated animals. There was no difference between the vehicle and etifoxine groups for sensorimotor functions as assessed by rotarod. In contrast, etifoxine resulted in a significant improvement of cognitive functions expressed by faster recovery in Morris water maze testing. The present findings show a significant neuroprotective effect of etifoxine in TBI through restoration of oxidative phosphorylation capacity associated with improved behavioral and cognitive outcomes. Since etifoxine is a registered drug used in common clinical practice, implementation in a phase II study may represent a reasonable step forward.
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Affiliation(s)
- Eilam Palzur
- Eliachar Research Laboratory, Galilee Medical Center, Nahariya 2210001, Israel; (E.P.); (R.S.)
| | - Doron Edelman
- Galilee Medical Center, Department of Neurosurgery, Nahariya 2210001, Israel;
| | - Reem Sakas
- Eliachar Research Laboratory, Galilee Medical Center, Nahariya 2210001, Israel; (E.P.); (R.S.)
| | - Jean Francois Soustiel
- Eliachar Research Laboratory, Galilee Medical Center, Nahariya 2210001, Israel; (E.P.); (R.S.)
- Galilee Medical Center, Department of Neurosurgery, Nahariya 2210001, Israel;
- Azrieli Faculty of Medicine, University of Bar Ilan, Zafed 1311502, Israel
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Federico M, De la Fuente S, Palomeque J, Sheu SS. The role of mitochondria in metabolic disease: a special emphasis on heart dysfunction. J Physiol 2021; 599:3477-3493. [PMID: 33932959 PMCID: PMC8424986 DOI: 10.1113/jp279376] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Accepted: 03/18/2021] [Indexed: 01/10/2023] Open
Abstract
Metabolic diseases (MetDs) embrace a series of pathologies characterized by abnormal body glucose usage. The known diseases included in this group are metabolic syndrome, prediabetes and diabetes mellitus types 1 and 2. All of them are chronic pathologies that present metabolic disturbances and are classified as multi-organ diseases. Cardiomyopathy has been extensively described in diabetic patients without overt macrovascular complications. The heart is severely damaged during the progression of the disease; in fact, diabetic cardiomyopathies are the main cause of death in MetDs. Insulin resistance, hyperglycaemia and increased free fatty acid metabolism promote cardiac damage through mitochondria. These organelles supply most of the energy that the heart needs to beat and to control essential cellular functions, including Ca2+ signalling modulation, reactive oxygen species production and apoptotic cell death regulation. Several aspects of common mitochondrial functions have been described as being altered in diabetic cardiomyopathies, including impaired energy metabolism, compromised mitochondrial dynamics, deficiencies in Ca2+ handling, increases in reactive oxygen species production, and a higher probability of mitochondrial permeability transition pore opening. Therefore, the mitochondrial role in MetD-mediated heart dysfunction has been studied extensively to identify potential therapeutic targets for improving cardiac performance. Herein we review the cardiac pathology in metabolic syndrome, prediabetes and diabetes mellitus, focusing on the role of mitochondrial dysfunctions.
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Affiliation(s)
- Marilen Federico
- Centro de Investigaciones Cardiovasculares, CCT-La Plata-CONICET, Facultad de Cs. Medicas, UNLP, La Plata, Argentina
| | - Sergio De la Fuente
- Center for Translational Medicine, Department of Medicine, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA 19107 USA
| | - Julieta Palomeque
- Centro de Investigaciones Cardiovasculares, CCT-La Plata-CONICET, Facultad de Cs. Medicas, UNLP, La Plata, Argentina
- Centro de Altos Estudios en Ciencias Humanas y de la Salud, Universidad Abierta Interamericana, CABA, Argentina
| | - Shey-Shing Sheu
- Center for Translational Medicine, Department of Medicine, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA 19107 USA
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Morciano G, Naumova N, Koprowski P, Valente S, Sardão VA, Potes Y, Rimessi A, Wieckowski MR, Oliveira PJ. The mitochondrial permeability transition pore: an evolving concept critical for cell life and death. Biol Rev Camb Philos Soc 2021; 96:2489-2521. [PMID: 34155777 DOI: 10.1111/brv.12764] [Citation(s) in RCA: 52] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Revised: 05/28/2021] [Accepted: 06/04/2021] [Indexed: 02/06/2023]
Abstract
In this review, we summarize current knowledge of perhaps one of the most intriguing phenomena in cell biology: the mitochondrial permeability transition pore (mPTP). This phenomenon, which was initially observed as a sudden loss of inner mitochondrial membrane impermeability caused by excessive calcium, has been studied for almost 50 years, and still no definitive answer has been provided regarding its mechanisms. From its initial consideration as an in vitro artifact to the current notion that the mPTP is a phenomenon with physiological and pathological implications, a long road has been travelled. We here summarize the role of mitochondria in cytosolic calcium control and the evolving concepts regarding the mitochondrial permeability transition (mPT) and the mPTP. We show how the evolving mPTP models and mechanisms, which involve many proposed mitochondrial protein components, have arisen from methodological advances and more complex biological models. We describe how scientific progress and methodological advances have allowed milestone discoveries on mPTP regulation and composition and its recognition as a valid target for drug development and a critical component of mitochondrial biology.
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Affiliation(s)
- Giampaolo Morciano
- Maria Cecilia Hospital, GVM Care & Research, Via Corriera 1, Cotignola, Ravenna, 48033, Italy.,Department of Medical Sciences, Section of Experimental Medicine, Laboratory for Technologies of Advanced Therapies (LTTA), University of Ferrara, Via Fossato di Mortara 70, Ferrara, 44121, Italy
| | - Natalia Naumova
- Department of Cardiac Thoracic and Vascular Sciences and Public Health, University of Padua Medical School, Via Giustiniani 2, Padova, 35128, Italy
| | - Piotr Koprowski
- Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteur Street, Warsaw, 02-093, Poland
| | - Sara Valente
- CNC - Center for Neuroscience and Cell Biology, CIBB - Centre for Innovative Biomedicine and Biotechnology, University of Coimbra, UC Biotech, Biocant Park, Cantanhede, 3060-197, Portugal
| | - Vilma A Sardão
- CNC - Center for Neuroscience and Cell Biology, CIBB - Centre for Innovative Biomedicine and Biotechnology, University of Coimbra, UC Biotech, Biocant Park, Cantanhede, 3060-197, Portugal
| | - Yaiza Potes
- Laboratory of Mitochondrial Biology and Metabolism, Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteur Street, Warsaw, 02-093, Poland
| | - Alessandro Rimessi
- Department of Medical Sciences, Section of Experimental Medicine, Laboratory for Technologies of Advanced Therapies (LTTA), University of Ferrara, Via Fossato di Mortara 70, Ferrara, 44121, Italy
| | - Mariusz R Wieckowski
- Laboratory of Mitochondrial Biology and Metabolism, Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteur Street, Warsaw, 02-093, Poland
| | - Paulo J Oliveira
- CNC - Center for Neuroscience and Cell Biology, CIBB - Centre for Innovative Biomedicine and Biotechnology, University of Coimbra, UC Biotech, Biocant Park, Cantanhede, 3060-197, Portugal
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9
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Jung ME. A Protective Role of Translocator Protein in Alzheimer's Disease Brain. Curr Alzheimer Res 2021; 17:3-15. [PMID: 32065102 DOI: 10.2174/1567205017666200217105950] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2019] [Revised: 01/13/2020] [Accepted: 01/20/2020] [Indexed: 12/16/2022]
Abstract
Translocator Protein (18 kDa) (TSPO) is a mitochondrial protein that locates cytosol cholesterol to mitochondrial membranes to begin the synthesis of steroids including neurotrophic neurosteroids. TSPO is abundantly present in glial cells that support neurons and respond to neuroinflammation. Located at the outer membrane of mitochondria, TSPO regulates the opening of mitochondrial permeability transition pore (mPTP) that controls the entry of molecules necessary for mitochondrial function. TSPO is linked to neurodegenerative Alzheimer's Disease (AD) such that TSPO is upregulated in the brain of AD patients and signals AD-induced adverse changes in brain. The initial increase in TSPO in response to brain insults remains elevated to repair cellular damages and perhaps to prevent further neuronal degeneration as AD progresses. To exert such protective activities, TSPO increases the synthesis of neuroprotective steroids, decreases neuroinflammation, limits the opening of mPTP, and reduces the generation of reactive oxygen species. The beneficial effects of TSPO on AD brain are manifested as the attenuation of neurotoxic amyloid β and mitochondrial dysfunction accompanied by the improvement of memory and cognition. However, the protective activities of TSPO appear to be temporary and eventually diminish as the severity of AD becomes profound. Timely treatment with TSPO agonists/ligands before the loss of endogenous TSPO's activity may promote the protective functions and may extend neuronal survival.
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Affiliation(s)
- Marianna E Jung
- Pharmacology and Neuroscience, University of North Texas Health Science Center, Institute for Healthy Aging, 3500 Camp Bowie Boulevard, Fort Worth, TX 76107, United States
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10
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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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11
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Panda S, Behera S, Alam MF, Syed GH. Endoplasmic reticulum & mitochondrial calcium homeostasis: The interplay with viruses. Mitochondrion 2021; 58:227-242. [PMID: 33775873 DOI: 10.1016/j.mito.2021.03.008] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2020] [Revised: 03/08/2021] [Accepted: 03/22/2021] [Indexed: 02/08/2023]
Abstract
Calcium ions (Ca2+) act as secondary messengers in a plethora of cellular processes and play crucial role in cellular organelle function and homeostasis. The average resting concentration of Ca2+ is nearly 100 nM and in certain cells it can reach up to 1 µM. The high range of Ca2+ concentration across the plasma membrane and intracellular Ca2+ stores demands a well-coordinated maintenance of free Ca2+ via influx, efflux, buffering and storage. Endoplasmic Reticulum (ER) and Mitochondria depend on Ca2+ for their function and also serve as major players in intracellular Ca2+ homeostasis. The ER-mitochondria interplay helps in orchestrating cellular calcium homeostasis to avoid any detrimental effect resulting from Ca2+ overload or depletion. Since Ca2+ plays a central role in many biological processes it is an essential component of the virus-host interactions. The large gradient across membranes enable the viruses to easily modulate this buffered environment to meet their needs. Viruses exploit Ca2+ signaling to establish productive infection and evade the host immune defense. In this review we will detail the interplay between the viruses and cellular & ER-mitochondrial calcium signaling and the significance of these events on viral life cycle and disease pathogenesis.
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Affiliation(s)
- Swagatika Panda
- Institute of Life Sciences, Bhubaneswar, Virus-Host Interaction Lab, Institute of Life Sciences, Bhubaneswar, India
| | - Suchismita Behera
- Institute of Life Sciences, Bhubaneswar, Clinical Proteomics Laboratory, Institute of Life Sciences, Bhubaneswar, India
| | - Mohd Faraz Alam
- Institute of Life Sciences, Bhubaneswar, Virus-Host Interaction Lab, Institute of Life Sciences, Bhubaneswar, India
| | - Gulam Hussain Syed
- Institute of Life Sciences, Bhubaneswar, Virus-Host Interaction Lab, Institute of Life Sciences, Bhubaneswar, India.
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12
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Cui Y, Pan M, Ma J, Song X, Cao W, Zhang P. Recent progress in the use of mitochondrial membrane permeability transition pore in mitochondrial dysfunction-related disease therapies. Mol Cell Biochem 2021; 476:493-506. [PMID: 33000352 DOI: 10.1007/s11010-020-03926-0] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Accepted: 09/23/2020] [Indexed: 12/13/2022]
Abstract
Mitochondria have various cellular functions, including ATP synthesis, calcium homeostasis, cell senescence, and death. Mitochondrial dysfunction has been identified in a variety of disorders correlated with human health. Among the many underlying mechanisms of mitochondrial dysfunction, the opening up of the mitochondrial permeability transition pore (mPTP) is one that has drawn increasing interest in recent years. It plays an important role in apoptosis and necrosis; however, the molecular structure and function of the mPTP have still not been fully elucidated. In recent years, the abnormal opening up of the mPTP has been implicated in the development and pathogenesis of diverse diseases including ischemia/reperfusion injury (IRI), neurodegenerative disorders, tumors, and chronic obstructive pulmonary disease (COPD). This review provides a systematic introduction to the possible molecular makeup of the mPTP and summarizes the mitochondrial dysfunction-correlated diseases and highlights possible underlying mechanisms. Since the mPTP is an important target in mitochondrial dysfunction, this review also summarizes potential treatments, which may be used to inhibit pore opening up via the molecules composing mPTP complexes, thus suppressing the progression of mitochondrial dysfunction-related diseases.
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Affiliation(s)
- Yuting Cui
- School of Life Science, Shandong University of Technology, Zibo, Shandong Province, China
| | - Mingyue Pan
- Department of Pharmacy, Shenzhen Luohu People's Hospital, Shenzhen, Guangdong Province, China
| | - Jing Ma
- The Eighth Affiliated Hospital, Sun Yat-Sen University, Shenzhen, Guangdong Province, China
| | - Xinhua Song
- School of Life Science, Shandong University of Technology, Zibo, Shandong Province, China
| | - Weiling Cao
- Department of Pharmacy, Shenzhen Luohu People's Hospital, Shenzhen, Guangdong Province, China.
| | - Peng Zhang
- Department of Pharmacy, Shenzhen Luohu People's Hospital, Shenzhen, Guangdong Province, China.
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13
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Bertholet AM, Kirichok Y. Patch-Clamp Analysis of the Mitochondrial H + Leak in Brown and Beige Fat. Front Physiol 2020; 11:326. [PMID: 32351404 PMCID: PMC7174661 DOI: 10.3389/fphys.2020.00326] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Accepted: 03/20/2020] [Indexed: 01/27/2023] Open
Abstract
Mitochondria convert the chemical energy of metabolic substrates into adenosine triphosphate (ATP) and heat. Although ATP production has become a focal point of research in bioenergetics, mitochondrial thermogenesis is also crucial for energy metabolism. Mitochondria generate heat due to H+ leak across the inner mitochondrial membrane (IMM) which is mediated by mitochondrial uncoupling proteins. The mitochondrial H+ leak was first identified, and studied for many decades, using mitochondrial respiration technique. Unfortunately, this method measures H+ leak indirectly, and its precision is insufficient for the rigorous insight into the mitochondrial function at the molecular level. Direct patch-clamp recording of H+ leak would have a significantly higher amplitude and time resolution, but application of the patch-clamp technique to a small subcellular organelle such as mitochondria has been challenging. We developed a method that facilitates patch-clamp recording from the whole IMM, enabling the direct measurement of small H+ leak currents via uncoupling proteins and thus, providing a rigorous understanding of the molecular mechanisms involved. In this paper we cover the methodology of measuring the H+ leak in mitochondria of specialized thermogenic tissues brown and beige fat.
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Affiliation(s)
- Ambre M. Bertholet
- Department of Physiology, University of California, San Francisco, San Francisco, CA, United States
| | - Yuriy Kirichok
- Department of Physiology, University of California, San Francisco, San Francisco, CA, United States
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14
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Magi S, Piccirillo S, Preziuso A, Amoroso S, Lariccia V. Mitochondrial localization of NCXs: Balancing calcium and energy homeostasis. Cell Calcium 2020; 86:102162. [DOI: 10.1016/j.ceca.2020.102162] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2019] [Revised: 01/10/2020] [Accepted: 01/12/2020] [Indexed: 01/04/2023]
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15
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Carraro M, Bernardi P. Measurement of membrane permeability and the mitochondrial permeability transition. Methods Cell Biol 2019; 155:369-379. [PMID: 32183968 DOI: 10.1016/bs.mcb.2019.10.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The mitochondrial permeability transition (PT) is an increase in the inner membrane permeability caused by the opening of a Ca2+-activated high-conductance channel, the so-called PT pore (PTP) or mitochondrial megachannel (MMC). Recent data indicate that F-ATP synthase contributes substantially to the generation of the PTP, yet this hypothesis is the matter of controversy. In this chapter, we will describe an approach to study the pore, i.e., the evaluation of mitochondrial swelling by means of a decrease in the absorbance at 540nm. This method should be useful to resolve apparent discrepancies in the literature and help solve emerging issues on the identity of mitochondrial pores.
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Affiliation(s)
- Michela Carraro
- Department of Biomedical Sciences, University of Padova, Padova, Italy.
| | - Paolo Bernardi
- Department of Biomedical Sciences, University of Padova, Padova, Italy.
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16
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Carraro M, Checchetto V, Szabó I, Bernardi P. F‐ATPsynthase and the permeability transition pore: fewer doubts, more certainties. FEBS Lett 2019; 593:1542-1553. [DOI: 10.1002/1873-3468.13485] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2019] [Revised: 06/09/2019] [Accepted: 06/10/2019] [Indexed: 12/27/2022]
Affiliation(s)
- Michela Carraro
- Department of Biomedical Sciences University of Padova Italy
| | | | - Ildikó Szabó
- Department of Biology University of Padova Italy
| | - Paolo Bernardi
- Department of Biomedical Sciences University of Padova Italy
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17
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Shehadeh M, Palzur E, Apel L, Soustiel JF. Reduction of Traumatic Brain Damage by Tspo Ligand Etifoxine. Int J Mol Sci 2019; 20:ijms20112639. [PMID: 31146356 PMCID: PMC6600152 DOI: 10.3390/ijms20112639] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2019] [Revised: 05/25/2019] [Accepted: 05/26/2019] [Indexed: 01/30/2023] Open
Abstract
Experimental studies have shown that ligands of the 18 kDa translocator protein can reduce neuronal damage induced by traumatic brain injury by protecting mitochondria and preventing metabolic crisis. Etifoxine, an anxiolytic drug and 18 kDa translocator protein ligand, has shown beneficial effects in the models of peripheral nerve neuropathy. The present study investigates the potential effect of etifoxine as a neuroprotective agent in traumatic brain injury (TBI). For this purpose, the effect of etifoxine on lesion volume and modified neurological severity score at 4 weeks was tested in Sprague-Dawley adult male rats submitted to cortical impact contusion. Effects of etifoxine treatment on neuronal survival and apoptosis were also assessed by immune stains in the perilesional area. Etifoxine induced a significant reduction in the lesion volume compared to nontreated animals in a dose-dependent fashion with a similar effect on neurological outcome at four weeks that correlated with enhanced neuron survival and reduced apoptotic activity. These results are consistent with the neuroprotective effect of etifoxine in TBI that may justify further translational research.
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Affiliation(s)
- Mona Shehadeh
- Eliachar Research Laboratory, Galilee Medical Center, P.O. Box 21, Nahariya 2210001, Israel.
| | - Eilam Palzur
- Eliachar Research Laboratory, Galilee Medical Center, P.O. Box 21, Nahariya 2210001, Israel.
| | - Liat Apel
- Institute of Pathology, Galilee Medical Center, P.O. Box 21, Nahariya 2210001, Israel.
- The Azrieli Faculty of Medicine in the Galilee, Bar Ilan University, Safed 13100, Israel.
| | - Jean Francois Soustiel
- Eliachar Research Laboratory, Galilee Medical Center, P.O. Box 21, Nahariya 2210001, Israel.
- The Azrieli Faculty of Medicine in the Galilee, Bar Ilan University, Safed 13100, Israel.
- Department of Neurosurgery, Galilee Medical Center, P.O. Box 21, Nahariya 2210001, Israel.
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18
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Ilkan Z, Akar FG. The Mitochondrial Translocator Protein and the Emerging Link Between Oxidative Stress and Arrhythmias in the Diabetic Heart. Front Physiol 2018; 9:1518. [PMID: 30416455 PMCID: PMC6212558 DOI: 10.3389/fphys.2018.01518] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2018] [Accepted: 10/09/2018] [Indexed: 02/06/2023] Open
Abstract
The mitochondrial translocator protein (TSPO) is a key outer mitochondrial membrane protein that regulates the activity of energy-dissipating mitochondrial channels in response to oxidative stress. In this article, we provide an overview of the role of TSPO in the systematic amplification of reactive oxygen species (ROS) through an autocatalytic process known as ROS-induced ROS-release (RIRR). We describe how this TSPO-driven process destabilizes the mitochondrial membrane potential leading to electrical instability at the cellular and whole heart levels. Finally, we provide our perspective on the role of TSPO in the pathophysiology of diabetes, in general and diabetes-related arrhythmias, in particular.
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Affiliation(s)
- Zeki Ilkan
- Cardiovascular Research Center, Icahn School of Medicine at Mount Sinai, New York, NY, United States
| | - Fadi G Akar
- Cardiovascular Research Center, Icahn School of Medicine at Mount Sinai, New York, NY, United States
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19
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Drummond‐Main CD, Rho JM. Electrophysiological characterization of a mitochondrial inner membrane chloride channel in rat brain. FEBS Lett 2018; 592:1545-1553. [DOI: 10.1002/1873-3468.13042] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2018] [Revised: 03/09/2018] [Accepted: 03/12/2018] [Indexed: 11/08/2022]
Affiliation(s)
- Christopher D. Drummond‐Main
- Developmental Neurosciences Research Program University of Calgary Alberta Canada
- Alberta Children's Hospital Research Institute University of Calgary Alberta Canada
| | - Jong M. Rho
- Developmental Neurosciences Research Program University of Calgary Alberta Canada
- Alberta Children's Hospital Research Institute University of Calgary Alberta Canada
- Departments of Pediatrics Clinical Neurosciences, and Physiology & Pharmacology University of Calgary Alberta Canada
- Hotchkiss Brain Institute Cumming School of Medicine University of Calgary Alberta Canada
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20
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Arduino DM, Perocchi F. Pharmacological modulation of mitochondrial calcium homeostasis. J Physiol 2018; 596:2717-2733. [PMID: 29319185 DOI: 10.1113/jp274959] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2017] [Accepted: 12/13/2017] [Indexed: 12/26/2022] Open
Abstract
Mitochondria are pivotal organelles in calcium (Ca2+ ) handling and signalling, constituting intracellular checkpoints for numerous processes that are vital for cell life. Alterations in mitochondrial Ca2+ homeostasis have been linked to a variety of pathological conditions and are critical in the aetiology of several human diseases. Efforts have been taken to harness mitochondrial Ca2+ transport mechanisms for therapeutic intervention, but pharmacological compounds that direct and selectively modulate mitochondrial Ca2+ homeostasis are currently lacking. New avenues have, however, emerged with the breakthrough discoveries on the genetic identification of the main players involved in mitochondrial Ca2+ influx and efflux pathways and with recent hints towards a deep understanding of the function of these molecular systems. Here, we review the current advances in the understanding of the mechanisms and regulation of mitochondrial Ca2+ homeostasis and its contribution to physiology and human disease. We also introduce and comment on the recent progress towards a systems-level pharmacological targeting of mitochondrial Ca2+ homeostasis.
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Affiliation(s)
- Daniela M Arduino
- Gene Center, Department of Biochemistry, Ludwig-Maximilians Universität München, Munich, 81377, Germany.,Institute for Diabetes and Obesity, Helmholtz Diabetes Center (HDC), Helmholtz Zentrum München and German National Diabetes Center (DZD), Neuherberg, 85764, Germany
| | - Fabiana Perocchi
- Gene Center, Department of Biochemistry, Ludwig-Maximilians Universität München, Munich, 81377, Germany.,Institute for Diabetes and Obesity, Helmholtz Diabetes Center (HDC), Helmholtz Zentrum München and German National Diabetes Center (DZD), Neuherberg, 85764, Germany
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21
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Barichello T, Simões LR, Collodel A, Giridharan VV, Dal-Pizzol F, Macedo D, Quevedo J. The translocator protein (18 kDa) and its role in neuropsychiatric disorders. Neurosci Biobehav Rev 2017; 83:183-199. [DOI: 10.1016/j.neubiorev.2017.10.010] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Revised: 09/20/2017] [Accepted: 10/10/2017] [Indexed: 02/08/2023]
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22
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Gambardella J, Sorriento D, Ciccarelli M, Del Giudice C, Fiordelisi A, Napolitano L, Trimarco B, Iaccarino G, Santulli G. Functional Role of Mitochondria in Arrhythmogenesis. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 982:191-202. [PMID: 28551788 DOI: 10.1007/978-3-319-55330-6_10] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Growing evidence indicate that mitochondria play a functional role in arrhythmogenesis. We report here the molecular mechanisms underlying the action of these highly dynamic organelles in the regulation of cell metabolism, action potential and, overall, heart excitability. In particular, we examine the role of cardiac mitochondria in linking metabolism and cell excitability. The importance of the main mitochondrial channels is evaluated as well, including the recently identified calcium uniporter. Promises and pitfalls of potential therapeutic strategies targeting mitochondrial pathways are also assessed.
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Affiliation(s)
- Jessica Gambardella
- Columbia University Medical Center, New York, NY, USA.,Department of Medicine, Surgery and Dentistry, University of Salerno, Baronissi, Italy
| | - Daniela Sorriento
- Department of Advanced Biomedical Sciences, "Federico II" University, Naples, Italy
| | - Michele Ciccarelli
- Department of Medicine, Surgery and Dentistry, University of Salerno, Baronissi, Italy
| | - Carmine Del Giudice
- Department of Advanced Biomedical Sciences, "Federico II" University, Naples, Italy
| | - Antonella Fiordelisi
- Department of Advanced Biomedical Sciences, "Federico II" University, Naples, Italy
| | - Luigi Napolitano
- Department of Advanced Biomedical Sciences, "Federico II" University, Naples, Italy
| | - Bruno Trimarco
- Department of Advanced Biomedical Sciences, "Federico II" University, Naples, Italy
| | - Guido Iaccarino
- Department of Medicine, Surgery and Dentistry, University of Salerno, Baronissi, Italy
| | - Gaetano Santulli
- Dept. of Biomedical Advanced Sciences, Federico II University, Naples, Italy. .,Columbia University Medical Center, New York Presbyterian Hospital-Manhattan, New York, NY, USA.
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23
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Hurst S, Hoek J, Sheu SS. Mitochondrial Ca 2+ and regulation of the permeability transition pore. J Bioenerg Biomembr 2017; 49:27-47. [PMID: 27497945 PMCID: PMC5393273 DOI: 10.1007/s10863-016-9672-x] [Citation(s) in RCA: 148] [Impact Index Per Article: 21.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2016] [Accepted: 07/31/2016] [Indexed: 02/06/2023]
Abstract
The mitochondrial permeability transition pore was originally described in the 1970's as a Ca2+ activated pore and has since been attributed to the pathogenesis of many diseases. Here we evaluate how each of the current models of the pore complex fit to what is known about how Ca2+ regulates the pore, and any insight that provides into the molecular identity of the pore complex. We also discuss the central role of Ca2+ in modulating the pore's open probability by directly regulating processes, such as ATP/ADP balance through the tricarboxylic acid cycle, electron transport chain, and mitochondrial membrane potential. We review how Ca2+ influences second messengers such as reactive oxygen/nitrogen species production and polyphosphate formation. We discuss the evidence for how Ca2+ regulates post-translational modification of cyclophilin D including phosphorylation by glycogen synthase kinase 3 beta, deacetylation by sirtuins, and oxidation/ nitrosylation of key residues. Lastly we introduce a novel view into how Ca2+ activated proteolysis through calpains in the mitochondria may be a driver of sustained pore opening during pathologies such as ischemia reperfusion injury.
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Affiliation(s)
- Stephen Hurst
- Center for Translational Medicine, Department of Medicine, Sidney Kimmel Medical College, Thomas Jefferson University, 1020 Locust Street, Suite 543D, Philadelphia, PA, 19107, USA
| | - Jan Hoek
- Mitocare Center for Mitochondria Research, Department of Pathology Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA, 19107, USA
| | - Shey-Shing Sheu
- Center for Translational Medicine, Department of Medicine, Sidney Kimmel Medical College, Thomas Jefferson University, 1020 Locust Street, Suite 543D, Philadelphia, PA, 19107, USA.
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24
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Zulian A, Schiavone M, Giorgio V, Bernardi P. Forty years later: Mitochondria as therapeutic targets in muscle diseases. Pharmacol Res 2016; 113:563-573. [PMID: 27697642 DOI: 10.1016/j.phrs.2016.09.043] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/21/2016] [Accepted: 09/29/2016] [Indexed: 11/22/2022]
Abstract
The hypothesis that mitochondrial dysfunction can be a general mechanism for cell death in muscle diseases is 40 years old. The key elements of the proposed pathogenetic sequence (cytosolic Ca2+ overload followed by excess mitochondrial Ca2+ uptake, functional and then structural damage of mitochondria, energy shortage, worsened elevation of cytosolic Ca2+ levels, hypercontracture of muscle fibers, cell necrosis) have been confirmed in amazing detail by subsequent work in a variety of models. The explicit implication of the hypothesis was that it "may provide the basis for a more rational treatment for some conditions even before their primary causes are known" (Wrogemann and Pena, 1976, Lancet, 1, 672-674). This prediction is being fulfilled, and the potential of mitochondria as pharmacological targets in muscle diseases may soon become a reality, particularly through inhibition of the mitochondrial permeability transition pore and its regulator cyclophilin D.
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Affiliation(s)
- Alessandra Zulian
- CNR Neuroscience Institute and Department of Biomedical Sciences, University of Padova, Padova, Italy
| | - Marco Schiavone
- CNR Neuroscience Institute and Department of Biomedical Sciences, University of Padova, Padova, Italy
| | - Valentina Giorgio
- CNR Neuroscience Institute and Department of Biomedical Sciences, University of Padova, Padova, Italy
| | - Paolo Bernardi
- CNR Neuroscience Institute and Department of Biomedical Sciences, University of Padova, Padova, Italy.
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25
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Selvaraj V, Tu LN. Current status and future perspectives: TSPO in steroid neuroendocrinology. J Endocrinol 2016; 231:R1-R30. [PMID: 27422254 DOI: 10.1530/joe-16-0241] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/08/2016] [Accepted: 07/15/2016] [Indexed: 12/21/2022]
Abstract
The mitochondrial translocator protein (TSPO), previously known as the peripheral benzodiazepine receptor (PBR), has received significant attention both as a diagnostic biomarker and as a therapeutic target for different neuronal disease pathologies. Recently, its functional basis believed to be mediating mitochondrial cholesterol import for steroid hormone production has been refuted by studies examining both in vivo and in vitro genetic Tspo-deficient models. As a result, there now exists a fundamental gap in the understanding of TSPO function in the nervous system, and its putative pharmacology in neurosteroid production. In this review, we discuss several recent findings in steroidogenic cells that are in direct contradiction to previous studies, and necessitate a re-examination of the purported role for TSPO in de novo neurosteroid biosynthesis. We critically examine the pharmacological effects of different TSPO-binding drugs with particular focus on studies that measure neurosteroid levels. We highlight the basis of key misconceptions regarding TSPO that continue to pervade the literature, and the need for interpretation with caution to avoid negative impacts. We also summarize the emerging perspectives that point to new directions that need to be investigated for understanding the molecular function of TSPO, only after which the true potential of this therapeutic target in medicine may be realized.
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Affiliation(s)
- Vimal Selvaraj
- Department of Animal ScienceCornell University, Ithaca, New York, USA
| | - Lan N Tu
- Department of Animal ScienceCornell University, Ithaca, New York, USA
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26
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Tetrapyrroles as Endogenous TSPO Ligands in Eukaryotes and Prokaryotes: Comparisons with Synthetic Ligands. Int J Mol Sci 2016; 17:ijms17060880. [PMID: 27271616 PMCID: PMC4926414 DOI: 10.3390/ijms17060880] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2016] [Revised: 05/17/2016] [Accepted: 05/19/2016] [Indexed: 12/26/2022] Open
Abstract
The 18 kDa translocator protein (TSPO) is highly 0conserved in eukaryotes and prokaryotes. Since its discovery in 1977, numerous studies established the TSPO’s importance for life essential functions. For these studies, synthetic TSPO ligands typically are applied. Tetrapyrroles present endogenous ligands for the TSPO. Tetrapyrroles are also evolutionarily conserved and regulate multiple functions. TSPO and tetrapyrroles regulate each other. In animals TSPO-tetrapyrrole interactions range from effects on embryonic development to metabolism, programmed cell death, response to stress, injury and disease, and even to life span extension. In animals TSPOs are primarily located in mitochondria. In plants TSPOs are also present in plastids, the nuclear fraction, the endoplasmic reticulum, and Golgi stacks. This may contribute to translocation of tetrapyrrole intermediates across organelles’ membranes. As in animals, plant TSPO binds heme and protoporphyrin IX. TSPO-tetrapyrrole interactions in plants appear to relate to development as well as stress conditions, including salt tolerance, abscisic acid-induced stress, reactive oxygen species homeostasis, and finally cell death regulation. In bacteria, TSPO is important for switching from aerobic to anaerobic metabolism, including the regulation of photosynthesis. As in mitochondria, in bacteria TSPO is located in the outer membrane. TSPO-tetrapyrrole interactions may be part of the establishment of the bacterial-eukaryote relationships, i.e., mitochondrial-eukaryote and plastid-plant endosymbiotic relationships.
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27
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Revisiting trends on mitochondrial mega-channels for the import of proteins and nucleic acids. J Bioenerg Biomembr 2016; 49:75-99. [DOI: 10.1007/s10863-016-9662-z] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2016] [Accepted: 04/25/2016] [Indexed: 12/14/2022]
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28
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Tu LN, Zhao AH, Hussein M, Stocco DM, Selvaraj V. Translocator Protein (TSPO) Affects Mitochondrial Fatty Acid Oxidation in Steroidogenic Cells. Endocrinology 2016; 157:1110-21. [PMID: 26741196 PMCID: PMC4769361 DOI: 10.1210/en.2015-1795] [Citation(s) in RCA: 71] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Translocator protein (TSPO), also known as the peripheral benzodiazepine receptor, is a highly conserved outer mitochondrial membrane protein present in specific subpopulations of cells within different tissues. In recent studies, the presumptive model depicting mammalian TSPO as a critical cholesterol transporter for steroidogenesis has been refuted by studies examining effects of Tspo gene deletion in vivo and in vitro, biochemical testing of TSPO cholesterol transport function, and specificity of TSPO-mediated pharmacological responses. Nevertheless, high TSPO expression in steroid-producing cells seemed to indicate an alternate function for this protein in steroidogenic mitochondria. To seek an explanation, we used CRISPR/Cas9-mediated TSPO knockout steroidogenic MA-10 Leydig cell (MA-10:TspoΔ/Δ) clones to examine changes to core mitochondrial functions resulting from TSPO deficiency. We observed that 1) MA-10:TspoΔ/Δ cells had a shift in substrate utilization for energy production from glucose to fatty acids with significantly higher mitochondrial fatty acid oxidation (FAO), and increased reactive oxygen species production; and 2) oxygen consumption rate, mitochondrial membrane potential, and proton leak were not different between MA-10:TspoΔ/Δ and MA-10:Tspo+/+ control cells. Consistent with this finding, TSPO-deficient adrenal glands from global TSPO knockout (Tspo(-/-)) mice also showed up-regulation of genes involved in FAO compared with the TSPO floxed (Tspo(fl/fl)) controls. These results demonstrate the first experimental evidence that TSPO can affect mitochondrial energy homeostasis through modulation of FAO, a function that appears to be consistent with high levels of TSPO expression observed in cell types active in lipid storage/metabolism.
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Affiliation(s)
- Lan N Tu
- Department of Animal Science (L.N.T., A.H.Z., M.H., V.S.), College of Agriculture and Life Sciences, Cornell University, Ithaca, New York 14853; and Department of Cell Biology and Biochemistry (D.M.S.), School of Medicine, Texas Tech University Health Sciences Center, Lubbock, Texas 79430
| | - Amy H Zhao
- Department of Animal Science (L.N.T., A.H.Z., M.H., V.S.), College of Agriculture and Life Sciences, Cornell University, Ithaca, New York 14853; and Department of Cell Biology and Biochemistry (D.M.S.), School of Medicine, Texas Tech University Health Sciences Center, Lubbock, Texas 79430
| | - Mahmoud Hussein
- Department of Animal Science (L.N.T., A.H.Z., M.H., V.S.), College of Agriculture and Life Sciences, Cornell University, Ithaca, New York 14853; and Department of Cell Biology and Biochemistry (D.M.S.), School of Medicine, Texas Tech University Health Sciences Center, Lubbock, Texas 79430
| | - Douglas M Stocco
- Department of Animal Science (L.N.T., A.H.Z., M.H., V.S.), College of Agriculture and Life Sciences, Cornell University, Ithaca, New York 14853; and Department of Cell Biology and Biochemistry (D.M.S.), School of Medicine, Texas Tech University Health Sciences Center, Lubbock, Texas 79430
| | - Vimal Selvaraj
- Department of Animal Science (L.N.T., A.H.Z., M.H., V.S.), College of Agriculture and Life Sciences, Cornell University, Ithaca, New York 14853; and Department of Cell Biology and Biochemistry (D.M.S.), School of Medicine, Texas Tech University Health Sciences Center, Lubbock, Texas 79430
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Morin D, Musman J, Pons S, Berdeaux A, Ghaleh B. Mitochondrial translocator protein (TSPO): From physiology to cardioprotection. Biochem Pharmacol 2015; 105:1-13. [PMID: 26688086 DOI: 10.1016/j.bcp.2015.12.003] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2015] [Accepted: 12/04/2015] [Indexed: 01/08/2023]
Abstract
The mitochondrial translocator protein (TSPO) is a high affinity cholesterol binding protein which is primarily located in the outer mitochondrial membrane where it has been shown to interact with proteins implicated in mitochondrial permeability transition pore (mPTP) formation. TSPO is found in different species and is expressed at high levels in tissues that synthesize steroids but is also present in other peripheral tissues especially in the heart. TSPO has been involved in the import of cholesterol into mitochondria, a key step in steroidogenesis. This constitutes the main established function of the protein which was recently challenged by genetic studies. TSPO has also been associated directly or indirectly with a wide range of cellular functions such as apoptosis, cell proliferation, differentiation, regulation of mitochondrial function or porphyrin transport. In the heart the role of TSPO remains undefined but a growing body of evidence suggests that TSPO plays a critical role in regulating physiological cardiac function and that TSPO ligands may represent interesting drugs to protect the heart under pathological conditions. This article briefly reviews current knowledge regarding TSPO and discusses its role in the cardiovascular system under physiological and pathologic conditions. More particularly, it provides evidence that TSPO can represent an alternative strategy to develop new pharmacological agents to protect the myocardium against ischemia-reperfusion injury.
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Affiliation(s)
- Didier Morin
- INSERM U955, Équipe 3, Créteil, France; Université Paris-Est, UMR_S955, DHU A-TVB, UPEC, Créteil, France.
| | - Julien Musman
- INSERM U955, Équipe 3, Créteil, France; Université Paris-Est, UMR_S955, DHU A-TVB, UPEC, Créteil, France.
| | - Sandrine Pons
- INSERM U955, Équipe 3, Créteil, France; Université Paris-Est, UMR_S955, DHU A-TVB, UPEC, Créteil, France.
| | - Alain Berdeaux
- INSERM U955, Équipe 3, Créteil, France; Université Paris-Est, UMR_S955, DHU A-TVB, UPEC, Créteil, France.
| | - Bijan Ghaleh
- INSERM U955, Équipe 3, Créteil, France; Université Paris-Est, UMR_S955, DHU A-TVB, UPEC, Créteil, France.
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TSPO ligand residence time influences human glioblastoma multiforme cell death/life balance. Apoptosis 2015; 20:383-98. [PMID: 25413799 DOI: 10.1007/s10495-014-1063-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Ligands addressed to the mitochondrial Translocator Protein (TSPO) have been suggested as cell death/life and steroidogenesis modulators. Thus, TSPO ligands have been proposed as drug candidates in several diseases; nevertheless, a correlation between their binding affinity and in vitro efficacy has not been demonstrated yet, questioning the specificity of the observed effects. Since drug-target residence time is an emerging parameter able to influence drug pharmacological features, herein, the interaction between TSPO and irDE-MPIGA, a covalent TSPO ligand, was investigated in order to explore TSPO control on death/life processes in a standardized glioblastoma cell setting. After 90 min irDE-MPIGA cell treatment, 25 nM ligand concentration saturated irreversibly all TSPO binding sites; after 24 h, TSPO de-novo synthesis occurred and about 40 % TSPO binding sites resulted covalently bound to irDE-MPIGA. During cell culture treatments, several dynamic events were observed: (a) early apoptotic markers appeared, such as mitochondrial membrane potential collapse (at 3 h) and externalization of phosphatidylserine (at 6 h); (b) cell viability was reduced (at 6 h), without cell cycle arrest. After digitonin-permeabilized cell suspension treatment, a modulation of mitochondrial permeability transition pore was evidenced. Similar effects were elicited by the reversible TSPO ligand PIGA only when applied at micromolar dose. Interestingly, after 6 h, irDE-MPIGA cell exposure restored cell survival parameters. These results highlighted the ligand-target residence time and the cellular setting are crucial parameters that should be taken into account to understand the drug binding affinity and efficacy correlation and, above all, to translate efficiently cellular drug responses from bench to bedside.
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31
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Bernardi P, Forte M. Commentary: SPG7 is an essential and conserved component of the mitochondrial permeability transition pore. Front Physiol 2015; 6:320. [PMID: 26581158 PMCID: PMC4631815 DOI: 10.3389/fphys.2015.00320] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2015] [Accepted: 10/22/2015] [Indexed: 12/21/2022] Open
Affiliation(s)
- Paolo Bernardi
- Department of Biomedical Sciences, University of Padova Padova, Italy
| | - Michael Forte
- Vollum Institute, Oregon Health and Science University Portland, OR, USA
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32
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Arbo BD, Benetti F, Garcia-Segura LM, Ribeiro MF. Therapeutic actions of translocator protein (18 kDa) ligands in experimental models of psychiatric disorders and neurodegenerative diseases. J Steroid Biochem Mol Biol 2015. [PMID: 26200949 DOI: 10.1016/j.jsbmb.2015.07.007] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Translocator protein (TSPO) is an 18kDa protein located at contact sites between the outer and the inner mitochondrial membrane. Numerous studies have associated TSPO with the translocation of cholesterol across the aqueous mitochondrial intermembrane space and the regulation of steroidogenesis, as well as with the control of some other mitochondrial functions, such as mitochondrial respiration, mitochondrial permeability transition pore opening, apoptosis and cell proliferation. In the brain, changes in TSPO expression occur in several neuropathological conditions including neurodegenerative diseases and psychiatric disorders. Furthermore, TSPO ligands have been shown to promote neuroprotection in animal models of brain pathology. At least in some cases, the mechanisms of neuroprotection are associated with modifications in brain steroidogenesis. In addition, regulation of neuroinflammation seems to be a common mechanism in the neuroprotective actions of TSPO ligands in different animal models of brain pathology.
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Affiliation(s)
- B D Arbo
- Laboratório de Interação Neuro-Humoral, Department of Physiology, ICBS, Universidade Federal do Rio Grande do Sul (UFRGS), Rua Sarmento Leite, 500, CEP 90050-170 Porto Alegre, RS, Brazil; Cajal Institute, CSIC, Avenida Doctor Arce, 37, 28002 Madrid, Spain.
| | - F Benetti
- Laboratório de Neurofisiologia Cognitiva e do Desenvolvimento, Department of Physiology, ICBS, Universidade Federal do Rio Grande do Sul (UFRGS), Rua Sarmento Leite, 500, CEP 90050-170 Porto Alegre, RS, Brazil
| | | | - M F Ribeiro
- Laboratório de Interação Neuro-Humoral, Department of Physiology, ICBS, Universidade Federal do Rio Grande do Sul (UFRGS), Rua Sarmento Leite, 500, CEP 90050-170 Porto Alegre, RS, Brazil
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Bernardi P, Rasola A, Forte M, Lippe G. The Mitochondrial Permeability Transition Pore: Channel Formation by F-ATP Synthase, Integration in Signal Transduction, and Role in Pathophysiology. Physiol Rev 2015; 95:1111-55. [PMID: 26269524 DOI: 10.1152/physrev.00001.2015] [Citation(s) in RCA: 420] [Impact Index Per Article: 46.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
The mitochondrial permeability transition (PT) is a permeability increase of the inner mitochondrial membrane mediated by a channel, the permeability transition pore (PTP). After a brief historical introduction, we cover the key regulatory features of the PTP and provide a critical assessment of putative protein components that have been tested by genetic analysis. The discovery that under conditions of oxidative stress the F-ATP synthases of mammals, yeast, and Drosophila can be turned into Ca(2+)-dependent channels, whose electrophysiological properties match those of the corresponding PTPs, opens new perspectives to the field. We discuss structural and functional features of F-ATP synthases that may provide clues to its transition from an energy-conserving into an energy-dissipating device as well as recent advances on signal transduction to the PTP and on its role in cellular pathophysiology.
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Affiliation(s)
- Paolo Bernardi
- Department of Biomedical Sciences and Consiglio Nazionale delle Ricerche Neuroscience Institute, University of Padova, Padova, Italy; Vollum Institute, Oregon Health and Sciences University, Portland, Oregon; and Department of Food Science, University of Udine, Udine, Italy
| | - Andrea Rasola
- Department of Biomedical Sciences and Consiglio Nazionale delle Ricerche Neuroscience Institute, University of Padova, Padova, Italy; Vollum Institute, Oregon Health and Sciences University, Portland, Oregon; and Department of Food Science, University of Udine, Udine, Italy
| | - Michael Forte
- Department of Biomedical Sciences and Consiglio Nazionale delle Ricerche Neuroscience Institute, University of Padova, Padova, Italy; Vollum Institute, Oregon Health and Sciences University, Portland, Oregon; and Department of Food Science, University of Udine, Udine, Italy
| | - Giovanna Lippe
- Department of Biomedical Sciences and Consiglio Nazionale delle Ricerche Neuroscience Institute, University of Padova, Padova, Italy; Vollum Institute, Oregon Health and Sciences University, Portland, Oregon; and Department of Food Science, University of Udine, Udine, Italy
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Sekler I. Standing of giants shoulders the story of the mitochondrial Na(+)Ca(2+) exchanger. Biochem Biophys Res Commun 2015; 460:50-2. [PMID: 25998733 DOI: 10.1016/j.bbrc.2015.02.170] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Accepted: 02/23/2015] [Indexed: 01/23/2023]
Abstract
It is now the 40th anniversary of the Journal of Molecular and Cellular Cardiology paper by Ernesto Carafoli and colleagues. This seminal study described for the first time mitochondrial Ca(2+) extrusion and its coupling to Na(+). This short review will describe the profound impact that this work had on mitochondrial signaling and the cross talk between the mitochondria, the ER, and the plasma membrane. It will further tell how the functional identification and in particular its unique cation selectivity to both Li(+) and Na(+) eventually contributed to the identification of the mitochondrial Na(+)/Ca(2+) exchanger gene NCLX many years later. The last part will describe how molecular tools derived from NCLX identification are used to study the novel physiological aspects of Ca(2+) signaling.
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Selvaraj V, Stocco DM. The changing landscape in translocator protein (TSPO) function. Trends Endocrinol Metab 2015; 26:341-8. [PMID: 25801473 PMCID: PMC7171652 DOI: 10.1016/j.tem.2015.02.007] [Citation(s) in RCA: 92] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/03/2014] [Revised: 02/11/2015] [Accepted: 02/18/2015] [Indexed: 11/25/2022]
Abstract
Translocator protein (TSPO), previously known as the peripheral benzodiazepine receptor (PBR), is an outer mitochondrial membrane protein. TSPO has been shown to cooperate with steroidogenic acute regulatory protein (StAR) and function in the transport of cholesterol into mitochondria. TSPO has also been considered as a structural component of the mitochondrial permeability transition pore (MPTP). However, recent advances have changed these views of TSPO's functions and have prompted a re-evaluation of established concepts. This review summarizes the history of TSPO, key elements of the debate, and functional experiments that have changed our understanding. Moving forward, we examine how this fundamental change impacts our understanding of TSPO and affects the future of TSPO as a therapeutic and diagnostic target.
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Affiliation(s)
- Vimal Selvaraj
- Department of Animal Science, Cornell University, Ithaca, NY 14853, USA.
| | - Douglas M Stocco
- Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA
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36
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Kaga M, Nakamoto Y, Nakamura K, Ikeda K, Yoshii M, Kawana S. Stress sensitivity in patients with atopic dermatitis in relation to the translocator protein 18 kDa (TSPO). J NIPPON MED SCH 2015; 81:148-56. [PMID: 24998961 DOI: 10.1272/jnms.81.148] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Atopic dermatitis (AD) is a chronic inflammatory skin disease, characterized by pruritic and eczematous skin lesions and dermatitis that worsens under stressful conditions. However, the relation of these symptoms to an individual's stress sensitivity is not well understood. On the other hand, expression of the translocator protein (18 kDa) (TSPO), formerly known as the peripheral-type benzodiazepine receptor, has been used as a biological marker of trait anxiety and stress sensitivity. The present study was designed to address this issue by examining TSPO in patients with AD. Fifty-two patients with AD (30 male and 22 female) and 163 healthy volunteers (89 male and 74 female) participated in this study. State-Trait Anxiety Inventory (STAI) scores were significantly higher in patients with AD, especially male patients, than in healthy subjects. The expression of platelet TSPO, as determined with a binding assay with [(3)H] PK11195, was also significantly higher in patients with AD, indicating that AD is a stress-responsive disease. In genomic analysis using lymphocytes, a single-nucleotide polymorphism of the human TSPO gene at exon 4 (485G>A), which is presumably associated with an individual's stress sensitivity, showed significantly lower frequencies of G/G and higher frequencies of G/A in patients with AD than in healthy subjects. The severity of AD, as determined with the Scoring of Atopic Dermatitis index, was correlated with TSPO expression in male patients with the G/A phenotype. In conclusion, the present study provides new evidence that variation in the TSPO gene affects susceptibility to AD.
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Affiliation(s)
- Mio Kaga
- Department of Dermatology, Nippon Medical School
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37
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Busch AW, Montgomery BL. Interdependence of tetrapyrrole metabolism, the generation of oxidative stress and the mitigative oxidative stress response. Redox Biol 2015; 4:260-71. [PMID: 25618582 PMCID: PMC4315935 DOI: 10.1016/j.redox.2015.01.010] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2014] [Revised: 01/12/2015] [Accepted: 01/14/2015] [Indexed: 01/01/2023] Open
Abstract
Tetrapyrroles are involved in light harvesting and light perception, electron-transfer reactions, and as co-factors for key enzymes and sensory proteins. Under conditions in which cells exhibit stress-induced imbalances of photosynthetic reactions, or light absorption exceeds the ability of the cell to use photoexcitation energy in synthesis reactions, redox imbalance can occur in photosynthetic cells. Such conditions can lead to the generation of reactive oxygen species (ROS) associated with alterations in tetrapyrrole homeostasis. ROS accumulation can result in cellular damage and detrimental effects on organismal fitness, or ROS molecules can serve as signals to induce a protective or damage-mitigating oxidative stress signaling response in cells. Induced oxidative stress responses include tetrapyrrole-dependent and -independent mechanisms for mitigating ROS generation and/or accumulation. Thus, tetrapyrroles can be contributors to oxidative stress, but are also essential in the oxidative stress response to protect cells by contributing to detoxification of ROS. In this review, we highlight the interconnection and interdependence of tetrapyrrole metabolism with the occurrence of oxidative stress and protective oxidative stress signaling responses in photosynthetic organisms. Tetrapyrroles are involved in light sensing and oxidative stress mitigation. Reactive oxygen species (ROS) can form upon light exposure of free tetrapyrroles. Tetrapyrrole homeostasis must be tightly regulated to avoid oxidative stress. ROS can result in cellular damage or oxidative stress signaling in cells.
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38
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The mitochondrial translocator protein and arrhythmogenesis in ischemic heart disease. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2015; 2015:234104. [PMID: 25918579 PMCID: PMC4397036 DOI: 10.1155/2015/234104] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/08/2015] [Accepted: 03/18/2015] [Indexed: 12/19/2022]
Abstract
Mitochondrial dysfunction is a hallmark of multiple cardiovascular disorders, including ischemic heart disease. Although mitochondria are well recognized for their role in energy production and cell death, mechanisms by which they control excitation-contraction coupling, excitability, and arrhythmias are less clear. The translocator protein (TSPO) is an outer mitochondrial membrane protein that is expressed in multiple organ systems. The abundant expression of TSPO in macrophages has been leveraged to image the immune response of the heart to inflammatory processes. More recently, the recognition of TSPO as a regulator of energy-dissipating mitochondrial pathways has extended its utility from a diagnostic marker of inflammation to a therapeutic target influencing diverse pathophysiological processes. Here, we provide an overview of the emerging role of TSPO in ischemic heart disease. We highlight the importance of TSPO in the regenerative process of reactive oxygen species (ROS) induced ROS release through its effects on the inner membrane anion channel (IMAC) and the permeability transition pore (PTP). We discuss evidence implicating TSPO in arrhythmogenesis in the settings of acute ischemia-reperfusion injury and myocardial infarction.
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The translocator protein as a potential molecular target for improved treatment efficacy in photodynamic therapy. Future Med Chem 2015; 6:775-92. [PMID: 24941872 DOI: 10.4155/fmc.14.37] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Since its serendipitous discovery over 30 years ago, the translocator protein (18 kDa) has been demonstrated to play an important role in a multitude of critical biological processes. Although implemented as a novel therapeutic and diagnostic tool for a variety of disease states, its most promising role is as a molecular target for anticancer treatments such as photodynamic therapy (PDT). This review gives an overview of the attempts made by researchers to design porphyrin-based photosensitizers for use as anticancer therapeutics in PDT as well as improved imaging agents for diagnostic purposes. With a better understanding of the structure and function of the translocator protein, the synthesis of porphyrins for use in PDT with optimum binding affinities will become ever more possible.
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40
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Bernardi P, Di Lisa F. The mitochondrial permeability transition pore: molecular nature and role as a target in cardioprotection. J Mol Cell Cardiol 2015; 78:100-6. [PMID: 25268651 PMCID: PMC4294587 DOI: 10.1016/j.yjmcc.2014.09.023] [Citation(s) in RCA: 355] [Impact Index Per Article: 39.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/22/2014] [Revised: 09/15/2014] [Accepted: 09/19/2014] [Indexed: 12/18/2022]
Abstract
The mitochondrial permeability transition (PT) - an abrupt increase permeability of the inner membrane to solutes - is a causative event in ischemia-reperfusion injury of the heart, and the focus of intense research in cardioprotection. The PT is due to opening of the PT pore (PTP), a high conductance channel that is critically regulated by a variety of pathophysiological effectors. Very recent work indicates that the PTP forms from the F-ATP synthase, which would switch from an energy-conserving to an energy-dissipating device. This review provides an update on the current debate on how this transition is achieved, and on the PTP as a target for therapeutic intervention. This article is part of a Special Issue entitled "Mitochondria: from basic mitochondrial biology to cardiovascular disease".
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Affiliation(s)
- Paolo Bernardi
- Department of Biomedical Sciences, University of Padova, 35121 Padova, Italy; Consiglio Nazionale delle Ricerche Neuroscience Institute, University of Padova, 35121 Padova, Italy.
| | - Fabio Di Lisa
- Department of Biomedical Sciences, University of Padova, 35121 Padova, Italy; Consiglio Nazionale delle Ricerche Neuroscience Institute, University of Padova, 35121 Padova, Italy.
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Leneveu-Jenvrin C, Connil N, Bouffartigues E, Papadopoulos V, Feuilloley MGJ, Chevalier S. Structure-to-function relationships of bacterial translocator protein (TSPO): a focus on Pseudomonas. Front Microbiol 2014; 5:631. [PMID: 25477872 PMCID: PMC4237140 DOI: 10.3389/fmicb.2014.00631] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2014] [Accepted: 11/04/2014] [Indexed: 12/21/2022] Open
Abstract
The translocator protein (TSPO), which was previously designated as the peripheral-type benzodiazepine receptor, is a 3.5 billion year-old evolutionarily conserved protein expressed by most Eukarya, Archae and Bacteria, but its organization and functions differ remarkably. By taking advantage of the genomic data available on TSPO, we focused on bacterial TSPO and attempted to define functions of TSPO in Pseudomonas via in silico approaches. A tspo ortholog has been identified in several fluorescent Pseudomonas. This protein presents putative binding motifs for cholesterol and PK 11195, which is a specific drug ligand of mitochondrial TSPO. While it is a common surface distribution, the sense of insertion and membrane localization differ between α- and γ-proteobacteria. Experimental published data and STRING analysis of common TSPO partners in fluorescent Pseudomonas indicate a potential role of TSPO in the oxidative stress response, iron homeostasis and virulence expression. In these bacteria, TSPO could also take part in signal transduction and in the preservation of membrane integrity.
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Affiliation(s)
- Charlène Leneveu-Jenvrin
- Laboratory of Microbiology Signals and Microenvironment EA 4312, University of Rouen Evreux, France
| | - Nathalie Connil
- Laboratory of Microbiology Signals and Microenvironment EA 4312, University of Rouen Evreux, France
| | - Emeline Bouffartigues
- Laboratory of Microbiology Signals and Microenvironment EA 4312, University of Rouen Evreux, France
| | - Vassilios Papadopoulos
- Department of Medicine, Research Institute of the McGill University Health Centre, McGill University Montreal, QC, Canada
| | - Marc G J Feuilloley
- Laboratory of Microbiology Signals and Microenvironment EA 4312, University of Rouen Evreux, France
| | - Sylvie Chevalier
- Laboratory of Microbiology Signals and Microenvironment EA 4312, University of Rouen Evreux, France
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42
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Zorov DB, Juhaszova M, Sollott SJ. Mitochondrial reactive oxygen species (ROS) and ROS-induced ROS release. Physiol Rev 2014; 94:909-50. [PMID: 24987008 DOI: 10.1152/physrev.00026.2013] [Citation(s) in RCA: 3174] [Impact Index Per Article: 317.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Byproducts of normal mitochondrial metabolism and homeostasis include the buildup of potentially damaging levels of reactive oxygen species (ROS), Ca(2+), etc., which must be normalized. Evidence suggests that brief mitochondrial permeability transition pore (mPTP) openings play an important physiological role maintaining healthy mitochondria homeostasis. Adaptive and maladaptive responses to redox stress may involve mitochondrial channels such as mPTP and inner membrane anion channel (IMAC). Their activation causes intra- and intermitochondrial redox-environment changes leading to ROS release. This regenerative cycle of mitochondrial ROS formation and release was named ROS-induced ROS release (RIRR). Brief, reversible mPTP opening-associated ROS release apparently constitutes an adaptive housekeeping function by the timely release from mitochondria of accumulated potentially toxic levels of ROS (and Ca(2+)). At higher ROS levels, longer mPTP openings may release a ROS burst leading to destruction of mitochondria, and if propagated from mitochondrion to mitochondrion, of the cell itself. The destructive function of RIRR may serve a physiological role by removal of unwanted cells or damaged mitochondria, or cause the pathological elimination of vital and essential mitochondria and cells. The adaptive release of sufficient ROS into the vicinity of mitochondria may also activate local pools of redox-sensitive enzymes involved in protective signaling pathways that limit ischemic damage to mitochondria and cells in that area. Maladaptive mPTP- or IMAC-related RIRR may also be playing a role in aging. Because the mechanism of mitochondrial RIRR highlights the central role of mitochondria-formed ROS, we discuss all of the known ROS-producing sites (shown in vitro) and their relevance to the mitochondrial ROS production in vivo.
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Affiliation(s)
- Dmitry B Zorov
- A. N. Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia; and Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of Health, Baltimore, Maryland
| | - Magdalena Juhaszova
- A. N. Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia; and Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of Health, Baltimore, Maryland
| | - Steven J Sollott
- A. N. Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia; and Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of Health, Baltimore, Maryland
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43
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O-Uchi J, Ryu SY, Jhun BS, Hurst S, Sheu SS. Mitochondrial ion channels/transporters as sensors and regulators of cellular redox signaling. Antioxid Redox Signal 2014; 21:987-1006. [PMID: 24180309 PMCID: PMC4116125 DOI: 10.1089/ars.2013.5681] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
SIGNIFICANCE Mitochondrial ion channels/transporters and the electron transport chain (ETC) serve as key sensors and regulators for cellular redox signaling, the production of reactive oxygen species (ROS) and nitrogen species (RNS) in mitochondria, and balancing cell survival and death. Although the functional and pharmacological characteristics of mitochondrial ion transport mechanisms have been extensively studied for several decades, the majority of the molecular identities that are responsible for these channels/transporters have remained a mystery until very recently. RECENT ADVANCES Recent breakthrough studies uncovered the molecular identities of the diverse array of major mitochondrial ion channels/transporters, including the mitochondrial Ca2+ uniporter pore, mitochondrial permeability transition pore, and mitochondrial ATP-sensitive K+ channel. This new information enables us to form detailed molecular and functional characterizations of mitochondrial ion channels/transporters and their roles in mitochondrial redox signaling. CRITICAL ISSUES Redox-mediated post-translational modifications of mitochondrial ion channels/transporters and ETC serve as key mechanisms for the spatiotemporal control of mitochondrial ROS/RNS generation. FUTURE DIRECTIONS Identification of detailed molecular mechanisms for redox-mediated regulation of mitochondrial ion channels will enable us to find novel therapeutic targets for many diseases that are associated with cellular redox signaling and mitochondrial ion channels/transporters.
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Affiliation(s)
- Jin O-Uchi
- 1 Department of Medicine, Center for Translational Medicine, Jefferson Medical College, Thomas Jefferson University , Philadelphia, Pennsylvania
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44
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Zorov DB, Isaev NK, Plotnikov EY, Silachev DN, Zorova LD, Pevzner IB, Morosanova MA, Jankauskas SS, Zorov SD, Babenko VA. Perspectives of mitochondrial medicine. BIOCHEMISTRY (MOSCOW) 2014; 78:979-90. [PMID: 24228919 DOI: 10.1134/s0006297913090034] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Mitochondrial medicine was established more than 50 years ago after discovery of the very first pathology caused by impaired mitochondria. Since then, more than 100 mitochondrial pathologies have been discovered. However, the number may be significantly higher if we interpret the term "mitochondrial medicine" more widely and include in these pathologies not only those determined by the genetic apparatus of the nucleus and mitochondria, but also acquired mitochondrial defects of non-genetic nature. Now the main problems of mitochondriology arise from methodology, this being due to studies of mitochondrial activities under different models and conditions that are far from the functioning of mitochondria in a cell, organ, or organism. Controversial behavior of mitochondria ("friends and foes") to some extent might be explained by their bacterial origin with possible preservation of "egoistic" features peculiar to bacteria. Apparently, for normal mitochondrial functioning it is essential to maintain homeostasis of a number of mitochondrial elements such as mitochondrial DNA structure, membrane potential, and the system of mitochondrial quality control. Abrogation of these elements can cause a number of pathologies that have become subjects of mitochondrial medicine. Some approaches to therapy of mitochondrial pathologies are discussed.
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Affiliation(s)
- D B Zorov
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119991, Russia.
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Abstract
The field of mitochondrial ion channels has recently seen substantial progress, including the molecular identification of some of the channels. An integrative approach using genetics, electrophysiology, pharmacology, and cell biology to clarify the roles of these channels has thus become possible. It is by now clear that many of these channels are important for energy supply by the mitochondria and have a major impact on the fate of the entire cell as well. The purpose of this review is to provide an up-to-date overview of the electrophysiological properties, molecular identity, and pathophysiological functions of the mitochondrial ion channels studied so far and to highlight possible therapeutic perspectives based on current information.
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Šileikytė J, Blachly-Dyson E, Sewell R, Carpi A, Menabò R, Di Lisa F, Ricchelli F, Bernardi P, Forte M. Regulation of the mitochondrial permeability transition pore by the outer membrane does not involve the peripheral benzodiazepine receptor (Translocator Protein of 18 kDa (TSPO)). J Biol Chem 2014; 289:13769-81. [PMID: 24692541 DOI: 10.1074/jbc.m114.549634] [Citation(s) in RCA: 158] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Translocator protein of 18 kDa (TSPO) is a highly conserved, ubiquitous protein localized in the outer mitochondrial membrane, where it is thought to play a key role in the mitochondrial transport of cholesterol, a key step in the generation of steroid hormones. However, it was first characterized as the peripheral benzodiazepine receptor because it appears to be responsible for high affinity binding of a number of benzodiazepines to non-neuronal tissues. Ensuing studies have employed natural and synthetic ligands to assess the role of TSPO function in a number of natural and pathological circumstances. Largely through the use of these compounds and biochemical associations, TSPO has been proposed to play a role in the mitochondrial permeability transition pore (PTP), which has been associated with cell death in many human pathological conditions. Here, we critically assess the role of TSPO in the function of the PTP through the generation of mice in which the Tspo gene has been conditionally eliminated. Our results show that 1) TSPO plays no role in the regulation or structure of the PTP, 2) endogenous and synthetic ligands of TSPO do not regulate PTP activity through TSPO, 3) outer mitochondrial membrane regulation of PTP activity occurs though a mechanism that does not require TSPO, and 4) hearts lacking TSPO are as sensitive to ischemia-reperfusion injury as hearts from control mice. These results call into question a wide variety of studies implicating TSPO in a number of pathological processes through its actions on the PTP.
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Affiliation(s)
- Justina Šileikytė
- From the Consiglio Nazionale delle Ricerche Institute of Neuroscience and Department of Biomedical Sciences, University of Padova, Via Ugo Bassi 58/B, I-35121 Padova, Italy
| | | | - Randall Sewell
- the Vollum Institute, Oregon Health and Sciences University, Portland, Oregon 97239, and
| | - Andrea Carpi
- From the Consiglio Nazionale delle Ricerche Institute of Neuroscience and Department of Biomedical Sciences, University of Padova, Via Ugo Bassi 58/B, I-35121 Padova, Italy
| | - Roberta Menabò
- From the Consiglio Nazionale delle Ricerche Institute of Neuroscience and Department of Biomedical Sciences, University of Padova, Via Ugo Bassi 58/B, I-35121 Padova, Italy
| | - Fabio Di Lisa
- From the Consiglio Nazionale delle Ricerche Institute of Neuroscience and Department of Biomedical Sciences, University of Padova, Via Ugo Bassi 58/B, I-35121 Padova, Italy
| | - Fernanda Ricchelli
- the Consiglio Nazionale delle Ricerche Institute of Biomedical Technologies at the Department of Biology, University of Padova, I-35121 Padova, Italy
| | - Paolo Bernardi
- From the Consiglio Nazionale delle Ricerche Institute of Neuroscience and Department of Biomedical Sciences, University of Padova, Via Ugo Bassi 58/B, I-35121 Padova, Italy,
| | - Michael Forte
- the Vollum Institute, Oregon Health and Sciences University, Portland, Oregon 97239, and
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Fan J, Papadopoulos V. Evolutionary origin of the mitochondrial cholesterol transport machinery reveals a universal mechanism of steroid hormone biosynthesis in animals. PLoS One 2013; 8:e76701. [PMID: 24124589 PMCID: PMC3790746 DOI: 10.1371/journal.pone.0076701] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2013] [Accepted: 08/23/2013] [Indexed: 11/18/2022] Open
Abstract
Steroidogenesis begins with the transport of cholesterol from intracellular stores into mitochondria via a series of protein-protein interactions involving cytosolic and mitochondrial proteins located at both the outer and inner mitochondrial membranes. In adrenal glands and gonads, this process is accelerated by hormones, leading to the production of high levels of steroids that control tissue development and function. A hormone-induced multiprotein complex, the transduceosome, was recently identified, and is composed of cytosolic and outer mitochondrial membrane proteins that control the rate of cholesterol entry into the outer mitochondrial membrane. More recent studies unveiled the steroidogenic metabolon, a bioactive, multimeric protein complex that spans the outer-inner mitochondrial membranes and is responsible for hormone-induced import, segregation, targeting, and metabolism of cholesterol by cytochrome P450 family 11 subfamily A polypeptide 1 (CYP11A1) in the inner mitochondrial membrane. The availability of genome information allowed us to systematically explore the evolutionary origin of the proteins involved in the mitochondrial cholesterol transport machinery (transduceosome, steroidogenic metabolon, and signaling proteins), trace the original archetype, and predict their biological functions by molecular phylogenetic and functional divergence analyses, protein homology modeling and molecular docking. Although most members of these complexes have a history of gene duplication and functional divergence during evolution, phylogenomic analysis revealed that all vertebrates have the same functional complex members, suggesting a common mechanism in the first step of steroidogenesis. An archetype of the complex was found in invertebrates. The data presented herein suggest that the cholesterol transport machinery is responsible for steroidogenesis among all vertebrates and is evolutionarily conserved throughout the entire animal kingdom.
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Affiliation(s)
- Jinjiang Fan
- Research Institute of the McGill University Health Centre, Montréal, Québec, Canada
| | - Vassilios Papadopoulos
- Research Institute of the McGill University Health Centre, Montréal, Québec, Canada
- Department of Medicine, Biochemistry and Pharmacology and Therapeutics, McGill University, Montréal, Québec, Canada
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Bernardi P. The mitochondrial permeability transition pore: a mystery solved? Front Physiol 2013; 4:95. [PMID: 23675351 PMCID: PMC3650560 DOI: 10.3389/fphys.2013.00095] [Citation(s) in RCA: 253] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2013] [Accepted: 04/19/2013] [Indexed: 01/04/2023] Open
Abstract
The permeability transition (PT) denotes an increase of the mitochondrial inner membrane permeability to solutes with molecular masses up to about 1500 Da. It is presumed to be mediated by opening of a channel, the permeability transition pore (PTP), whose molecular nature remains a mystery. Here I briefly review the history of the PTP, discuss existing models, and present our new results indicating that reconstituted dimers of the FOF1 ATP synthase form a channel with properties identical to those of the mitochondrial megachannel (MMC), the electrophysiological equivalent of the PTP. Open questions remain, but there is now promise that the PTP can be studied by genetic methods to solve the large number of outstanding problems.
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Affiliation(s)
- Paolo Bernardi
- Department of Biomedical Sciences, University of Padova Padova, Italy
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In vitro catabolic effect of protoporphyrin IX in human osteoblast-like cells: possible role of the 18 kDa mitochondrial translocator protein. J Bioenerg Biomembr 2013; 45:333-41. [PMID: 23475134 DOI: 10.1007/s10863-013-9501-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2012] [Accepted: 02/06/2013] [Indexed: 01/19/2023]
Abstract
In several pathological conditions, when conversion of Protoporphyrin (PP)IX into heme is impaired, a toxic accumulation of PPIX might occur. PPIX has been found to have affinity to the mitochondrial Translocator Protein 18 kDa. Since it is known that TSPO is abundant in human osteoblast cells, thus we assumed that PPIX can affect cellular functions via interactions with TSPO in these cells. Therefore we aimed to study the metabolic responses of human osteoblast to a high (10⁻⁵ M) concentration of PPIX in vitro. We found that in primary culture of human osteoblast-like cells cell numbers decreased following exposure to PPIX(10⁻⁵ M). Cellular [¹⁸F]-FDG incorporation, mitochondrial mass, ATP content were suppressed, and ΔΨm collapsed. Lactate dehydrogenase activity was enhanced in culture media, indicating overall cell death, while no increase in apoptotic levels was observed. Cellular proliferation was not affected. Protein expression of TSPO, VDAC 1, and hexokinase 2 decreased, although the synthesis of mRNA for hexokinase 2 increased. Thus, PPIX(10⁻⁵ M) has a cytotoxic effect on human osteoblast-like cell in vitro. Since these cells remain viable following exposure to another TSPO ligand, PK 11195 (10⁻⁵ M), as observed previously by us, the mode of action of PPIX on osteoblast-like cells is not identical to that of PK 11195. Accordingly pathological accumulation of PPIX may cause necrosis of osteoblasts leading to bone mass loss. We show that this phenomenon is unrelated to iron overload.
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Siemen D, Ziemer M. What is the nature of the mitochondrial permeability transition poreand What is it Not? IUBMB Life 2013; 65:255-62. [DOI: 10.1002/iub.1130] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2012] [Accepted: 12/07/2012] [Indexed: 12/23/2022]
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