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Sendai Y, Takeda K, Ohta K, Nakae S, Koshika K, Kitamura K, Higuchi M, Ichinohe T, Azuma T, Okumura K, Ohno T. Ro5-4864, a translocator protein ligand, regulates T cell-mediated inflammatory responses in skin. Int Immunol 2025; 37:221-234. [PMID: 39460731 DOI: 10.1093/intimm/dxae065] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2024] [Accepted: 10/24/2024] [Indexed: 10/28/2024] Open
Abstract
Translocator protein (TSPO) is a mitochondrial outer membrane protein expressed on a variety of immune cells, including macrophages, dendritic cells, and T cells, in addition to neurons and steroid-producing cells. Previous studies of TSPO ligands have suggested that TSPO is involved in multiple cellular functions, including steroidogenesis, immunomodulation, and cell proliferation. Currently, there are limited reports on the effects of TSPO or TSPO ligands on T cell-mediated immune responses. Here, we investigated the involvement of TSPO/TSPO ligand in T cell responses using a 2,4-dinitro-1-fluorobenzene (DNFB)-induced contact hypersensitivity (CH) model. Treatment with Ro5-4864, a TSPO ligand, during DNFB sensitization reduced the number and activation status of CD4+ and CD8+ T cells in draining lymph nodes and alleviated skin inflammation after DNFB challenge. Adoptive transfer of Ro5-4864-treated mouse-derived DNFB-sensitized T cells to naive mice inhibited CH responses after DNFB challenge. Ro5-4864-treated sensitized T cells showed lower proliferative responses when stimulated with DNFB-pulsed antigen-presenting cells compared to control-treated sensitized T cells. Ro5-4864 also suppressed cell proliferation, as well as adenosine triphosphate and lactate production, during T cell activation. Moreover, the inhibitory effects of Ro5-4864 on T cell responses were conserved in TSPO-deficient cells. Our results suggest that Ro5-4864 inhibits CH responses by suppressing energy metabolism, at least via glycolysis, to reduce the T cell primary response in a TSPO-independent manner.
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Affiliation(s)
- Yuka Sendai
- Oral Health Science Center, Tokyo Dental College, Tokyo 101-0061, Japan
- Department of Dental Anesthesiology, Tokyo Dental College, Tokyo 101-0061, Japan
| | - Kazuyoshi Takeda
- Department of Biofunctional Microbiota, Graduate School of Medicine, Juntendo University, Tokyo 113-8412, Japan
- Laboratory of Cell Biology, Research Support Center, Graduate School of Medicine, Juntendo University, Tokyo 113-8421, Japan
| | - Keisuke Ohta
- Advanced Imaging Research Center, Kurume University School of Medicine, Fukuoka 830-0011, Japan
| | - Susumu Nakae
- Graduate School of Integrated Sciences for Life, Hiroshima University, Hiroshima 739-8511, Japan
| | - Kyotaro Koshika
- Oral Health Science Center, Tokyo Dental College, Tokyo 101-0061, Japan
- Department of Dental Anesthesiology, Tokyo Dental College, Tokyo 101-0061, Japan
| | - Kei Kitamura
- Department of Histology and Developmental Biology, Tokyo Dental College, Tokyo 101-0061, Japan
| | - Makoto Higuchi
- Department of Functional Brain Imaging, Institute for Quantum Medical Science, Quantum Life and Medical Science Directorate, National Institutes for Quantum Science and Technology, Chiba 263-8555, Japan
| | - Tatsuya Ichinohe
- Department of Dental Anesthesiology, Tokyo Dental College, Tokyo 101-0061, Japan
| | - Toshifumi Azuma
- Department of Biochemistry, Tokyo Dental College, Tokyo 101-0061, Japan
| | - Ko Okumura
- Department of Biofunctional Microbiota, Graduate School of Medicine, Juntendo University, Tokyo 113-8412, Japan
- Atopy Research Center, Graduate School of Medicine, Juntendo University, Tokyo 113-8412, Japan
| | - Tatsukuni Ohno
- Oral Health Science Center, Tokyo Dental College, Tokyo 101-0061, Japan
- Department of Biofunctional Microbiota, Graduate School of Medicine, Juntendo University, Tokyo 113-8412, Japan
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2
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Yu M, Zhao S. Functional role of translocator protein and its ligands in ocular diseases (Review). Mol Med Rep 2024; 29:33. [PMID: 38186312 PMCID: PMC10804439 DOI: 10.3892/mmr.2024.13157] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2023] [Accepted: 12/08/2023] [Indexed: 01/09/2024] Open
Abstract
The 18 kDa translocator protein (TSPO) is an essential outer mitochondrial membrane protein that is responsible for mitochondrial transport, maintenance of mitochondrial homeostasis and normal physiological cell function. The role of TSPO in the pathogenesis of ocular diseases is a growing area of interest. More notably, TSPO exerts positive effects in regulating various pathophysiological processes, such as the inflammatory response, oxidative stress, steroid synthesis and modulation of microglial function, in combination with a variety of specific ligands such as 1‑(2‑chlorophenyl‑N‑methylpropyl)‑3‑isoquinolinecarboxamide, 4'‑chlorodiazepam and XBD173. In the present review, the expression of TSPO in ocular tissues and the functional role of TSPO and its ligands in diverse ocular diseases was discussed.
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Affiliation(s)
- Mingyi Yu
- Tianjin Key Laboratory of Retinal Functions and Diseases, Tianjin Branch of National Clinical Research Center for Ocular Disease, Eye Institute and School of Optometry, Tianjin Medical University Eye Hospital, Tianjin 30384, P.R. China
| | - Shaozhen Zhao
- Tianjin Key Laboratory of Retinal Functions and Diseases, Tianjin Branch of National Clinical Research Center for Ocular Disease, Eye Institute and School of Optometry, Tianjin Medical University Eye Hospital, Tianjin 30384, P.R. China
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3
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Baglini E, Poggetti V, Cavallini C, Petroni D, Forini F, Nicolini G, Barresi E, Salerno S, Costa B, Iozzo P, Neglia D, Menichetti L, Taliani S, Da Settimo F. Targeting the Translocator Protein (18 kDa) in Cardiac Diseases: State of the Art and Future Opportunities. J Med Chem 2024; 67:17-37. [PMID: 38113353 PMCID: PMC10911791 DOI: 10.1021/acs.jmedchem.3c01716] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2023] [Revised: 11/16/2023] [Accepted: 11/24/2023] [Indexed: 12/21/2023]
Abstract
Mitochondria dysfunctions are typical hallmarks of cardiac disorders (CDs). The multiple tasks of this energy-producing organelle are well documented, but its pathophysiologic involvement in several manifestations of heart diseases, such as altered electromechanical coupling, excitability, and arrhythmias, is still under investigation. The human 18 kDa translocator protein (TSPO) is a protein located on the outer mitochondrial membrane whose expression is altered in different pathological conditions, including CDs, making it an attractive therapeutic and diagnostic target. Currently, only a few TSPO ligands are employed in CDs and cardiac imaging. In this Perspective, we report an overview of the emerging role of TSPO at the heart level, focusing on the recent literature concerning the development of TSPO ligands used for fighting and imaging heart-related disease conditions. Accordingly, targeting TSPO might represent a successful strategy to achieve novel therapeutic and diagnostic strategies to unravel the fundamental mechanisms and to provide solutions to still unanswered questions in CDs.
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Affiliation(s)
- Emma Baglini
- Institute
of Clinical Physiology, National Research Council of Italy, CNR Research Area, Via G. Moruzzi 1, Pisa 56124, Italy
| | - Valeria Poggetti
- Department
of Pharmacy, University of Pisa, Via Bonanno 6, Pisa 56126, Italy
| | - Chiara Cavallini
- Institute
of Clinical Physiology, National Research Council of Italy, CNR Research Area, Via G. Moruzzi 1, Pisa 56124, Italy
| | - Debora Petroni
- Institute
of Clinical Physiology, National Research Council of Italy, CNR Research Area, Via G. Moruzzi 1, Pisa 56124, Italy
| | - Francesca Forini
- Institute
of Clinical Physiology, National Research Council of Italy, CNR Research Area, Via G. Moruzzi 1, Pisa 56124, Italy
| | - Giuseppina Nicolini
- Institute
of Clinical Physiology, National Research Council of Italy, CNR Research Area, Via G. Moruzzi 1, Pisa 56124, Italy
| | - Elisabetta Barresi
- Department
of Pharmacy, University of Pisa, Via Bonanno 6, Pisa 56126, Italy
| | - Silvia Salerno
- Department
of Pharmacy, University of Pisa, Via Bonanno 6, Pisa 56126, Italy
| | - Barbara Costa
- Department
of Pharmacy, University of Pisa, Via Bonanno 6, Pisa 56126, Italy
| | - Patricia Iozzo
- Institute
of Clinical Physiology, National Research Council of Italy, CNR Research Area, Via G. Moruzzi 1, Pisa 56124, Italy
| | - Danilo Neglia
- Fondazione
CNR/Regione Toscana Gabriele Monasterio, Cardiovascular and Imaging
Departments, CNR Research Area, Via G. Moruzzi 1, Pisa 56124, Italy
| | - Luca Menichetti
- Institute
of Clinical Physiology, National Research Council of Italy, CNR Research Area, Via G. Moruzzi 1, Pisa 56124, Italy
| | - Sabrina Taliani
- Department
of Pharmacy, University of Pisa, Via Bonanno 6, Pisa 56126, Italy
| | - Federico Da Settimo
- Department
of Pharmacy, University of Pisa, Via Bonanno 6, Pisa 56126, Italy
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4
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Gouilly D, Saint-Aubert L, Ribeiro MJ, Salabert AS, Tauber C, Péran P, Arlicot N, Pariente J, Payoux P. Neuroinflammation PET imaging of the translocator protein (TSPO) in Alzheimer's disease: an update. Eur J Neurosci 2022; 55:1322-1343. [PMID: 35083791 DOI: 10.1111/ejn.15613] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Revised: 01/18/2022] [Accepted: 01/19/2022] [Indexed: 11/28/2022]
Abstract
Neuroinflammation is a significant contributor to Alzheimer's disease (AD). Until now, PET imaging of the translocator protein (TSPO) has been widely used to depict the neuroimmune endophenotype of AD. The aim of this review was to provide an update to the results from 2018 and to advance the characterization of the biological basis of TSPO imaging in AD by re-examining TSPO function and expression and the methodological aspects of interest. Although the biological basis of the TSPO PET signal is obviously related to microglia and astrocytes in AD, the observed process remains uncertain and might not be directly related to neuroinflammation. Further studies are required to re-examine the cellular significance underlying a variation in the PET signal in AD and how it can be impacted by a disease-modifying treatment.
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Affiliation(s)
- Dominique Gouilly
- ToNIC, Toulouse NeuroImaging Center, Université de Toulouse, Inserm, UPS, France
| | - Laure Saint-Aubert
- ToNIC, Toulouse NeuroImaging Center, Université de Toulouse, Inserm, UPS, France
| | - Maria-Joao Ribeiro
- Department of Nuclear Medicine, CHU, Tours, France.,UMR 1253, iBrain, Université de Tours, France.,Inserm CIC 1415, CHRU, Tours, France
| | - Anne-Sophie Salabert
- ToNIC, Toulouse NeuroImaging Center, Université de Toulouse, Inserm, UPS, France.,Department of Nuclear Medicine, CHU, Toulouse, France
| | | | - Patrice Péran
- ToNIC, Toulouse NeuroImaging Center, Université de Toulouse, Inserm, UPS, France
| | - Nicolas Arlicot
- UMR 1253, iBrain, Université de Tours, France.,Inserm CIC 1415, CHRU, Tours, France
| | - Jérémie Pariente
- ToNIC, Toulouse NeuroImaging Center, Université de Toulouse, Inserm, UPS, France.,Department of Cognitive Neurology, Epilepsy and Movement Disorders, CHU, Toulouse, France.,Center of Clinical Investigations (CIC1436), CHU, Toulouse, France
| | - Pierre Payoux
- ToNIC, Toulouse NeuroImaging Center, Université de Toulouse, Inserm, UPS, France.,Department of Nuclear Medicine, CHU, Toulouse, France
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5
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Banerji R, Huynh C, Figueroa F, Dinday MT, Baraban SC, Patel M. Enhancing glucose metabolism via gluconeogenesis is therapeutic in a zebrafish model of Dravet syndrome. Brain Commun 2021; 3:fcab004. [PMID: 33842883 PMCID: PMC8023476 DOI: 10.1093/braincomms/fcab004] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Revised: 12/14/2020] [Accepted: 12/16/2020] [Indexed: 01/18/2023] Open
Abstract
Energy-producing pathways are novel therapeutic targets for the treatment of neurodevelopmental disorders. Here, we focussed on correcting metabolic defects in a catastrophic paediatric epilepsy, Dravet syndrome which is caused by mutations in sodium channel NaV1.1 gene, SCN1A. We utilized a translatable zebrafish model of Dravet syndrome (scn1lab) which exhibits key characteristics of patients with Dravet syndrome and shows metabolic deficits accompanied by down-regulation of gluconeogenesis genes, pck1 and pck2. Using a metabolism-based small library screen, we identified compounds that increased gluconeogenesis via up-regulation of pck1 gene expression in scn1lab larvae. Treatment with PK11195, a pck1 activator and a translocator protein ligand, normalized dys-regulated glucose levels, metabolic deficits, translocator protein expression and significantly decreased electrographic seizures in mutant larvae. Inhibition of pck1 in wild-type larvae mimicked metabolic and behaviour defects observed in scn1lab mutants. Together, this suggests that correcting dys-regulated metabolic pathways can be therapeutic in neurodevelopmental disorders such as Dravet syndrome arising from ion channel dysfunction.
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Affiliation(s)
- Rajeswari Banerji
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado, Anschutz Medical Campus, Aurora, Colorado, CA 80045, USA
| | - Christopher Huynh
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado, Anschutz Medical Campus, Aurora, Colorado, CA 80045, USA
| | - Francisco Figueroa
- Department of Neurological Surgery, Epilepsy Research Laboratory, University of California, San Francisco, CA 94143, USA
| | - Matthew T Dinday
- Department of Neurological Surgery, Epilepsy Research Laboratory, University of California, San Francisco, CA 94143, USA
| | - Scott C Baraban
- Department of Neurological Surgery, Epilepsy Research Laboratory, University of California, San Francisco, CA 94143, USA
| | - Manisha Patel
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado, Anschutz Medical Campus, Aurora, Colorado, CA 80045, USA
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A systematic review of post-translational modifications in the mitochondrial permeability transition pore complex associated with cardiac diseases. Biochim Biophys Acta Mol Basis Dis 2020; 1867:165992. [PMID: 33091565 DOI: 10.1016/j.bbadis.2020.165992] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Revised: 09/23/2020] [Accepted: 10/08/2020] [Indexed: 12/28/2022]
Abstract
The mitochondrial permeability transition pore (mPTP) opening is involved in the pathophysiology of multiple cardiac diseases, such as ischemia/reperfusion injury and heart failure. A growing number of evidence provided by proteomic screening techniques has demonstrated the role of post-translational modifications (PTMs) in several key components of the pore in response to changes in the extra/intracellular environment and bioenergetic demand. This could lead to a fine, complex regulatory mechanism that, under pathological conditions, can shift the state of mitochondrial functions and, thus, the cell's fate. Understanding the complex relationship between these PTMs is still under investigation and can provide new, promising therapeutic targets and treatment approaches. This review, using a systematic review of the literature, presents the current knowledge on PTMs of the mPTP and their role in health and cardiac disease.
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7
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Ammer LM, Vollmann-Zwerenz A, Ruf V, Wetzel CH, Riemenschneider MJ, Albert NL, Beckhove P, Hau P. The Role of Translocator Protein TSPO in Hallmarks of Glioblastoma. Cancers (Basel) 2020; 12:cancers12102973. [PMID: 33066460 PMCID: PMC7602186 DOI: 10.3390/cancers12102973] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Revised: 10/09/2020] [Accepted: 10/09/2020] [Indexed: 12/18/2022] Open
Abstract
Simple Summary The translocator protein (TSPO) has been under extensive investigation as a specific marker in positron emission tomography (PET) to visualize brain lesions following injury or disease. In recent years, TSPO is increasingly appreciated as a potential novel therapeutic target in cancer. In Glioblastoma (GBM), the most malignant primary brain tumor, TSPO expression levels are strongly elevated and scientific evidence accumulates, hinting at a pivotal role of TSPO in tumorigenesis and glioma progression. The aim of this review is to summarize the current literature on TSPO with respect to its role both in diagnostics and especially with regard to the critical hallmarks of cancer postulated by Hanahan and Weinberg. Overall, our review contributes to a better understanding of the functional significance of TSPO in Glioblastoma and draws attention to TSPO as a potential modulator of treatment response and thus an important factor that may influence the clinical outcome of GBM. Abstract Glioblastoma (GBM) is the most fatal primary brain cancer in adults. Despite extensive treatment, tumors inevitably recur, leading to an average survival time shorter than 1.5 years. The 18 kDa translocator protein (TSPO) is abundantly expressed throughout the body including the central nervous system. The expression of TSPO increases in states of inflammation and brain injury due to microglia activation. Not least due to its location in the outer mitochondrial membrane, TSPO has been implicated with a broad spectrum of functions. These include the regulation of proliferation, apoptosis, migration, as well as mitochondrial functions such as mitochondrial respiration and oxidative stress regulation. TSPO is frequently overexpressed in GBM. Its expression level has been positively correlated to WHO grade, glioma cell proliferation, and poor prognosis of patients. Several lines of evidence indicate that TSPO plays a functional part in glioma hallmark features such as resistance to apoptosis, invasiveness, and proliferation. This review provides a critical overview of how TSPO could regulate several aspects of tumorigenesis in GBM, particularly in the context of the hallmarks of cancer proposed by Hanahan and Weinberg in 2011.
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Affiliation(s)
- Laura-Marie Ammer
- Wilhelm Sander-NeuroOncology Unit and Department of Neurology, University Hospital Regensburg, 93053 Regensburg, Germany; (L.-M.A.); (A.V.-Z.)
| | - Arabel Vollmann-Zwerenz
- Wilhelm Sander-NeuroOncology Unit and Department of Neurology, University Hospital Regensburg, 93053 Regensburg, Germany; (L.-M.A.); (A.V.-Z.)
| | - Viktoria Ruf
- Center for Neuropathology and Prion Research, Ludwig Maximilians University of Munich, 81377 Munich, Germany;
| | - Christian H. Wetzel
- Molecular Neurosciences, Department of Psychiatry and Psychotherapy, University of Regensburg, 93053 Regensburg, Germany;
| | | | - Nathalie L. Albert
- Department of Nuclear Medicine, Ludwig-Maximilians-University Munich, 81377 Munich, Germany;
| | - Philipp Beckhove
- Regensburg Center for Interventional Immunology (RCI) and Department Internal Medicine III, University Hospital Regensburg, 93053 Regensburg, Germany;
| | - Peter Hau
- Wilhelm Sander-NeuroOncology Unit and Department of Neurology, University Hospital Regensburg, 93053 Regensburg, Germany; (L.-M.A.); (A.V.-Z.)
- Correspondence:
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8
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Bravo-San Pedro JM, Sica V, Kroemer G. The elusive "hunger protein": an appetite-stimulatory factor that is overabundant in human obesity. Mol Cell Oncol 2019; 6:e1667193. [PMID: 31692883 PMCID: PMC6816372 DOI: 10.1080/23723556.2019.1667193] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2019] [Revised: 09/01/2019] [Accepted: 09/10/2019] [Indexed: 11/23/2022]
Abstract
Paradoxically, most if not all previously known appetite-stimulatory hormones are downregulated in human obesity, reflecting failing homeostatic circuitries. Recently, we discovered that acyl-coenzyme-A binding protein/diazepam-binding inhibitor (ACBP/DBI) acts as a lipogenic and appetite stimulator, when systemically injected into mice. ACBP/DBI plasma levels are also elevated in obese subjects, supporting the notion that it may represent the elusive "hunger protein" that explains overeating in human obesity.
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Affiliation(s)
- José Manuel Bravo-San Pedro
- INSERM U1138, Centre de Recherche des Cordeliers, Sorbonne Université, Université de Paris, Paris, France
- Team “Metabolism, Cancer & Immunity” labellisée par la Ligue contre le Cancer, Paris, France
- Karolinska Institute, Department of Women’s and Children’s Health, Karolinska University Hospital, Stockholm, Sweden
| | - Valentina Sica
- INSERM U1138, Centre de Recherche des Cordeliers, Sorbonne Université, Université de Paris, Paris, France
- Team “Metabolism, Cancer & Immunity” labellisée par la Ligue contre le Cancer, Paris, France
- Karolinska Institute, Department of Women’s and Children’s Health, Karolinska University Hospital, Stockholm, Sweden
| | - Guido Kroemer
- INSERM U1138, Centre de Recherche des Cordeliers, Sorbonne Université, Université de Paris, Paris, France
- Team “Metabolism, Cancer & Immunity” labellisée par la Ligue contre le Cancer, Paris, France
- Karolinska Institute, Department of Women’s and Children’s Health, Karolinska University Hospital, Stockholm, Sweden
- Pôle de Biologie, Hôpital Européen Georges Pompidou, AP-HP, Paris, France
- Suzhou Institute for Systems Medicine, Chinese Academy of Sciences, Suzhou, China
- Cell Biology and Metabolomics platforms, Gustave Roussy Cancer Campus, Villejuif, France
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9
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Klee K, Storti F, Barben M, Samardzija M, Langmann T, Dunaief J, Grimm C. Systemic knockout of Tspo in mice does not affect retinal morphology, function and susceptibility to degeneration. Exp Eye Res 2019; 188:107816. [PMID: 31562844 DOI: 10.1016/j.exer.2019.107816] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Revised: 09/19/2019] [Accepted: 09/24/2019] [Indexed: 12/11/2022]
Abstract
Translocator protein (18 kDa) (TSPO) is a mitochondrial protein expressed by reactive microglia and astrocytes at the site of neuronal injury. Although TSPO function has not been fully determined, synthetic TSPO ligands have beneficial effects on different pathologies of the central nervous system, including the retina. Here, we studied the pattern of Tspo expression in the aging human retina and in two mouse models of retinal degeneration. Using a newly generated Tspo-KO mouse, we investigated the impact of the lack of TSPO on retinal morphology, function and susceptibility to degeneration. We show that TSPO was expressed in both human and mouse retina and retinal pigment epithelium (RPE). Tspo was induced in the mouse retina upon degeneration, but constitutively expressed in the RPE. Similarly, TSPO expression levels in healthy human retina and RPE were not differentially regulated during aging. Tspo-KO mice had normal retinal morphology and function up to 48 weeks of age. Photoreceptor loss caused either by exposure to excessive light levels or by a mutation in the phosphodiesterase 6b gene was not affected by the absence of Tspo. The reactivity states of retinal mononuclear phagocytes following light-damage were comparable in Tspo-KO and control mice. Our data suggest that lack of endogenous TSPO does not directly influence the magnitude of photoreceptor degeneration or microglia activation in these two models of retinal degeneration. We therefore hypothesize that the interaction of TSPO with its ligands may be required to modulate disease progression.
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Affiliation(s)
- Katrin Klee
- Lab for Retinal Cell Biology, Department of Ophthalmology, University of Zurich, Schlieren, Switzerland; Center for Integrative Human Physiology (ZIHP), University of Zurich, Zurich, Switzerland
| | - Federica Storti
- Lab for Retinal Cell Biology, Department of Ophthalmology, University of Zurich, Schlieren, Switzerland
| | - Maya Barben
- Lab for Retinal Cell Biology, Department of Ophthalmology, University of Zurich, Schlieren, Switzerland
| | - Marijana Samardzija
- Lab for Retinal Cell Biology, Department of Ophthalmology, University of Zurich, Schlieren, Switzerland
| | - Thomas Langmann
- Laboratory for Experimental Immunology of the Eye, Department of Ophthalmology, University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany; Center for Molecular Medicine Cologne (CMMC), Cologne, Germany
| | - Joshua Dunaief
- Department of Ophthalmology, Scheie Eye Institute, University of Pennsylvania, Philadelphia, PA, USA
| | - Christian Grimm
- Lab for Retinal Cell Biology, Department of Ophthalmology, University of Zurich, Schlieren, Switzerland; Center for Integrative Human Physiology (ZIHP), University of Zurich, Zurich, Switzerland; Neuroscience Center, University of Zurich, Zurich, Switzerland.
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10
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Kim S, Kim N, Park S, Jeon Y, Lee J, Yoo SJ, Lee JW, Moon C, Yu SW, Kim EK. Tanycytic TSPO inhibition induces lipophagy to regulate lipid metabolism and improve energy balance. Autophagy 2019; 16:1200-1220. [PMID: 31469345 PMCID: PMC7469491 DOI: 10.1080/15548627.2019.1659616] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Hypothalamic glial cells named tanycytes, which line the 3rd ventricle (3V), are components of the hypothalamic network that regulates a diverse array of metabolic functions for energy homeostasis. Herein, we report that TSPO (translocator protein), an outer mitochondrial protein, is highly enriched in tanycytes and regulates homeostatic responses to nutrient excess as a potential target for an effective intervention in obesity. Administration of a TSPO ligand, PK11195, into the 3V, and tanycyte-specific deletion of Tspo reduced food intake and elevated energy expenditure, leading to negative energy balance in a high-fat diet challenge. Ablation of tanycytic Tspo elicited AMPK-dependent lipophagy, breaking down lipid droplets into free fatty acids, thereby elevating ATP in a lipid stimulus. Our findings suggest that tanycytic TSPO affects systemic energy balance through macroautophagy/autophagy-regulated lipid metabolism, and highlight the physiological significance of TSPO in hypothalamic lipid sensing and bioenergetics in response to overnutrition. Abbreviations 3V: 3rd ventricle; ACAC: acetyl-Coenzyme A carboxylase; AGRP: agouti related neuropeptide; AIF1/IBA1: allograft inflammatory factor 1; AMPK: AMP-activated protein kinase; ARC: arcuate nucleus; Atg: autophagy related; Bafilo: bafilomycin A1; CAMKK2: calcium/calmodulin-dependent protein kinase kinase 2, beta; CCCP: carbonyl cyanide m-chlorophenylhydrazone; CNS: central nervous system; COX4I1: cytochrome c oxidase subunit 4I1; FFA: free fatty acid; GFAP: glial fibrillary acidic protein; HFD: high-fat diet; ICV: intracerebroventricular; LAMP2: lysosomal-associated membrane protein 2; LD: lipid droplet; MAP1LC3B/LC3B: microtubule-associated protein 1 light chain 3 beta; MBH: mediobasal hypothalamus; ME: median eminence; MEF: mouse embryonic fibroblast; NCD: normal chow diet; NEFM/NFM: neurofilament medium; NPY: neuropeptide Y; OL: oleic acid; POMC: pro-opiomelanocortin-alpha; PRKN/Parkin: parkin RBR E3 ubiquitin protein ligase; Rax: retina and anterior neural fold homeobox; RBFOX3/NeuN: RNA binding protein, fox-1 homolog (C. elegans) 3; RER: respiratory exchange ratio; siRNA: small interfering RNA; SQSTM1: sequestosome 1; TG: triglyceride; TSPO: translocator protein; ULK1: unc-51 like kinase 1; VCO2: carbon dioxide production; VMH: ventromedial hypothalamus; VO2: oxygen consumption
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Affiliation(s)
- Seolsong Kim
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology , Daegu, Republic of Korea
| | - Nayoun Kim
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology , Daegu, Republic of Korea
| | - Seokjae Park
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology , Daegu, Republic of Korea.,Neurometabolomics Research Center, Daegu Gyeongbuk Institute of Science and Technology , Daegu, Republic of Korea
| | - Yoonjeong Jeon
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology , Daegu, Republic of Korea.,Neurometabolomics Research Center, Daegu Gyeongbuk Institute of Science and Technology , Daegu, Republic of Korea
| | - Jaemeun Lee
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology , Daegu, Republic of Korea
| | - Seung-Jun Yoo
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology , Daegu, Republic of Korea.,Convergence Research Advanced Centre for Olfaction, Daegu Gyeongbuk Institute of Science and Technology , Daegu, Republic of Korea
| | - Ji-Won Lee
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology , Daegu, Republic of Korea
| | - Cheil Moon
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology , Daegu, Republic of Korea.,Convergence Research Advanced Centre for Olfaction, Daegu Gyeongbuk Institute of Science and Technology , Daegu, Republic of Korea
| | - Seong-Woon Yu
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology , Daegu, Republic of Korea.,Neurometabolomics Research Center, Daegu Gyeongbuk Institute of Science and Technology , Daegu, Republic of Korea
| | - Eun-Kyoung Kim
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology , Daegu, Republic of Korea.,Neurometabolomics Research Center, Daegu Gyeongbuk Institute of Science and Technology , Daegu, Republic of Korea
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11
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Shoshan-Barmatz V, Pittala S, Mizrachi D. VDAC1 and the TSPO: Expression, Interactions, and Associated Functions in Health and Disease States. Int J Mol Sci 2019; 20:ijms20133348. [PMID: 31288390 PMCID: PMC6651789 DOI: 10.3390/ijms20133348] [Citation(s) in RCA: 61] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2019] [Revised: 07/02/2019] [Accepted: 07/03/2019] [Indexed: 12/12/2022] Open
Abstract
The translocator protein (TSPO), located at the outer mitochondrial membrane (OMM), serves multiple functions and contributes to numerous processes, including cholesterol import, mitochondrial metabolism, apoptosis, cell proliferation, Ca2+ signaling, oxidative stress, and inflammation. TSPO forms a complex with the voltage-dependent anion channel (VDAC), a protein that mediates the flux of ions, including Ca2+, nucleotides, and metabolites across the OMM, controls metabolism and apoptosis and interacts with many proteins. This review focuses on the two OMM proteins TSPO and VDAC1, addressing their structural interaction and associated functions. TSPO appears to be involved in the generation of reactive oxygen species, proposed to represent the link between TSPO activation and VDAC, thus playing a role in apoptotic cell death. In addition, expression of the two proteins in healthy brains and diseased states is considered, as is the relationship between TSPO and VDAC1 expression. Both proteins are over-expressed in in brains from Alzheimer’s disease patients. Finally, TSPO expression levels were proposed as a biomarker of some neuropathological settings, while TSPO-interacting ligands have been considered as a potential basis for drug development.
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Affiliation(s)
- Varda Shoshan-Barmatz
- Department of Life Sciences and the National Institute for Biotechnology in the Negev, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel.
| | - Srinivas Pittala
- Department of Life Sciences and the National Institute for Biotechnology in the Negev, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel
| | - Dario Mizrachi
- Department of Physiology and Developmental Biology, Brigham Young University, Provo, UT 84602, USA
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12
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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: 19] [Impact Index Per Article: 3.2] [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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13
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Gong Z, Han Y, Wu L, Xia T, Ren H, Yang D, Gu D, Wang H, Hu C, He D, Zhou L, Zeng C. Translocator protein 18 kDa ligand alleviates neointimal hyperplasia in the diabetic rat artery injury model via activating PKG. Life Sci 2019; 221:72-82. [PMID: 30738868 DOI: 10.1016/j.lfs.2019.02.015] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2018] [Revised: 02/03/2019] [Accepted: 02/06/2019] [Indexed: 01/01/2023]
Abstract
AIMS The proliferation of VSMCs is the pathologic basis for intimal hyperplasia after angioplasty in diabetic patients. Translocator protein (TSPO), located in the outer mitochondrial membrane, has been found to regulate redox intermediate components in cell dysfunction. We hypothesized that TSPO may regulate VSMC proliferation and migration, and be involved in the intimal hyperplasia after angioplasty in diabetes. MATERIALS AND METHODS Cell proliferation was measured by cell counting and MTT assays. Cell migration was measured by Transwell® and scratch-wound assays. TSPO expression in arteries of rats and high glucose-treated A10 cells were detected by immunoblotting and immunofluorescence staining. Neointimal formation of carotid artery was induced by balloon injury in type 2 diabetic rat. KEY FINDINGS TSPO expression was increased in the arterial samples from diabetic rats and A10 cells treated with high glucose. Down-regulation of TSPO expression by siRNA decreased the high-glucose-induced VSMC proliferation and migration in A10 cells. This phenomenon could be simulated by using TSPO ligands, PK 11195 and Ro5-4864. cGMP/PKG signals were involved in the TSPO ligand action, since in the presence of cGMP or PKG inhibitor ODQ or KT5823 respectively, the effect of PK 11195 on VSMC proliferation was blocked. Furthermore, PK 11195 significantly inhibited neointimal formation by the inhibition of VSMC proliferation. SIGNIFICANCE This study suggests that TSPO inhibition suppresses the proliferation and migration of VSMCs induced by hyperglycemia, consequently, preventing atherosclerosis and restenosis after angioplasty in diabetic conditions. TSPO may be a potential therapeutic target to reduce arterial remodeling induced by angioplasty in diabetes.
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Affiliation(s)
- Zhengfan Gong
- Department of Cardiology, Daping Hospital, The Third Military Medical University, Chongqing, PR China; Chongqing Institute of Cardiology, Chongqing Key Laboratory of Hypertension Research, Chongqing, PR China
| | - Yu Han
- Department of Cardiology, Daping Hospital, The Third Military Medical University, Chongqing, PR China; Chongqing Institute of Cardiology, Chongqing Key Laboratory of Hypertension Research, Chongqing, PR China
| | - Lianpan Wu
- Department of Cardiology, Daping Hospital, The Third Military Medical University, Chongqing, PR China; Chongqing Institute of Cardiology, Chongqing Key Laboratory of Hypertension Research, Chongqing, PR China
| | - Tianyang Xia
- Department of Cardiology, Daping Hospital, The Third Military Medical University, Chongqing, PR China; Chongqing Institute of Cardiology, Chongqing Key Laboratory of Hypertension Research, Chongqing, PR China
| | - Hongmei Ren
- Department of Cardiology, Daping Hospital, The Third Military Medical University, Chongqing, PR China; Chongqing Institute of Cardiology, Chongqing Key Laboratory of Hypertension Research, Chongqing, PR China
| | - Donghai Yang
- Department of Cardiology, Daping Hospital, The Third Military Medical University, Chongqing, PR China; Chongqing Institute of Cardiology, Chongqing Key Laboratory of Hypertension Research, Chongqing, PR China
| | - Daqian Gu
- Department of Cardiology, Daping Hospital, The Third Military Medical University, Chongqing, PR China; Chongqing Institute of Cardiology, Chongqing Key Laboratory of Hypertension Research, Chongqing, PR China
| | - He Wang
- Department of Cardiology, Daping Hospital, The Third Military Medical University, Chongqing, PR China; Chongqing Institute of Cardiology, Chongqing Key Laboratory of Hypertension Research, Chongqing, PR China; Department of Cardiology, The First Affiliated Hospital of Henan University of Chinese Medicine, Zhengzhou, PR China
| | - Cuimei Hu
- Department of Cardiology, Daping Hospital, The Third Military Medical University, Chongqing, PR China; Chongqing Institute of Cardiology, Chongqing Key Laboratory of Hypertension Research, Chongqing, PR China
| | - Duofen He
- Department of Cardiology, Daping Hospital, The Third Military Medical University, Chongqing, PR China; Chongqing Institute of Cardiology, Chongqing Key Laboratory of Hypertension Research, Chongqing, PR China
| | - Lin Zhou
- Department of Cardiology, Daping Hospital, The Third Military Medical University, Chongqing, PR China; Chongqing Institute of Cardiology, Chongqing Key Laboratory of Hypertension Research, Chongqing, PR China.
| | - Chunyu Zeng
- Department of Cardiology, Daping Hospital, The Third Military Medical University, Chongqing, PR China; Chongqing Institute of Cardiology, Chongqing Key Laboratory of Hypertension Research, Chongqing, PR China.
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14
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Etifoxine, a TSPO Ligand, Worsens Hepatitis C-Related Insulin Resistance but Relieves Lipid Accumulation. BIOMED RESEARCH INTERNATIONAL 2019; 2019:3102414. [PMID: 30984779 PMCID: PMC6432734 DOI: 10.1155/2019/3102414] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Revised: 12/22/2018] [Accepted: 01/23/2019] [Indexed: 11/17/2022]
Abstract
Etifoxine, an 18 kDa translocator protein (TSPO) agonist for the treatment of anxiety disorders in clinic, may be able to cause acute liver injury or cytolytic hepatitis. TSPO has been demonstrated to participate in inflammatory responses in infective diseases as well as to modulate glucose and lipid homeostasis. Hepatitis C virus (HCV) infection disrupts glucose and lipid homoeostasis, leading to insulin resistance (IR). Whether TSPO affects the HCV-induced IR remains unclear. Here, we found that the administration of etifoxine increased the TSPO protein expression and recovered the HCV-mediated lower mitochondrial membrane potential (MMP) without affecting HCV infection. Moreover, etifoxine reversed the HCV-induced lipid accumulation by modulating the expressions of sterol regulatory element-binding protein-1 and apolipoprotein J. On the other hand, in infected cells pretreated with etifoxine, the insulin-mediated insulin receptor substrate-1/Akt signals, forkhead box protein O1 translocation, and glucose uptake were blocked. Taken together, our results pointed out that etifoxine relieved the HCV-retarded MMP and reduced the lipid accumulation but deteriorated the HCV-induced IR by interfering with insulin signal molecules.
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15
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Potential involvement of the 18 kDa translocator protein and reactive oxygen species in apoptosis of THP-1 macrophages induced by sonodynamic therapy. PLoS One 2018; 13:e0196541. [PMID: 29746502 PMCID: PMC5944937 DOI: 10.1371/journal.pone.0196541] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2017] [Accepted: 04/14/2018] [Indexed: 11/19/2022] Open
Abstract
Sonodynamic therapy (SDT) with exogenous protoporphyrin IX (PpIX) or endogenous PpIX derived from 5-aminolevulinic acid (ALA) has been carried out to produce apoptotic effects on macrophages, indicating a potential treatment methodology for atherosclerosis. Our previous studies have found that mitochondria damage by reactive oxygen species (ROS) plays a major role in the SDT-induced apoptosis. This study aimed at investigating the potential involvement of the mitochondrial 18 kDa translocator protein (TSPO) and ROS in the pro-apoptotic effects of SDT on THP-1 macrophages. THP-1 macrophages were divided into control and SDT groups, and went through pretreatment of the specific TSPO ligand PK11195 and ROS scavengers N-Acetyl Cysteine (NAC), then compared with groups without pretreatment. Application of PK11195 reduced intracellular accumulation of endogenous PpIX. PK11195 and NAC reduced the generation of intracellular ROS and oxidation of cardiolipin induced by SDT, respectively. PK11195 and NAC also reduced SDT-induced mitochondrial membrane potential (ΔΨm) loss, the translocation of cytochrome c and cell apoptosis. PpIX accumulation, ROS generation and cell apoptosis were also attenuated by siTSPO. Our findings indicate the pivotal role of TSPO and ROS in SDT-induced cardiolipin oxidation, ΔΨm collapse, cytochrome c translocation and apoptosis in THP-1 macrophages.
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16
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Gene Knockout Shows That PML (TRIM19) Does Not Restrict the Early Stages of HIV-1 Infection in Human Cell Lines. mSphere 2017; 2:mSphere00233-17. [PMID: 28656178 PMCID: PMC5480037 DOI: 10.1128/mspheredirect.00233-17] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Accepted: 05/26/2017] [Indexed: 01/12/2023] Open
Abstract
PML is involved in innate immune mechanisms against both DNA and RNA viruses. Although the mechanism by which PML inhibits highly divergent viruses is unclear, it was recently found that it can increase the transcription of interferon-stimulated genes (ISGs). However, whether human PML inhibits HIV-1 has been debated. Here we provide unambiguous, knockout-based evidence that PML does not restrict the early postentry stages of HIV-1 infection in a variety of human cell types and does not participate in the inhibition of HIV-1 by IFN-I. Although this study does not exclude the possibility of other mechanisms by which PML may interfere with HIV-1, we nonetheless demonstrate that PML does not generally act as an HIV-1 restriction factor in human cells and that its presence is not required for IFN-I to stimulate the expression of anti-HIV-1 genes. These results contribute to uncovering the landscape of HIV-1 inhibition by ISGs in human cells. The PML (promyelocytic leukemia) protein is a member of the TRIM family, a large group of proteins that show high diversity in functions but possess a common tripartite motif giving the family its name. We and others recently reported that both murine PML (mPML) and human PML (hPML) strongly restrict the early stages of infection by HIV-1 and other lentiviruses when expressed in mouse embryonic fibroblasts (MEFs). This restriction activity was found to contribute to the type I interferon (IFN-I)-mediated inhibition of HIV-1 in MEFs. Additionally, PML caused transcriptional repression of the HIV-1 promoter in MEFs. In contrast, the modulation of the early stages of HIV-1 infection of human cells by PML has been investigated by RNA interference, with unclear results. In order to conclusively determine whether PML restricts HIV-1 or not in human cells, we used the clustered regularly interspaced short palindromic repeat with Cas9 (CRISPR-Cas9) system to knock out its gene in epithelial, lymphoid, and monocytic human cell lines. Infection challenges showed that PML knockout had no effect on the permissiveness of these cells to HIV-1 infection. IFN-I treatments inhibited HIV-1 equally whether PML was expressed or not. Overexpression of individual hPML isoforms, or of mPML, in a human T cell line did not restrict HIV-1. The presence of PML was not required for the restriction of nonhuman retroviruses by TRIM5α (another human TRIM protein), and TRIM5α was inhibited by arsenic trioxide through a PML-independent mechanism. We conclude that PML is not a restriction factor for HIV-1 in human cell lines representing diverse lineages. IMPORTANCE PML is involved in innate immune mechanisms against both DNA and RNA viruses. Although the mechanism by which PML inhibits highly divergent viruses is unclear, it was recently found that it can increase the transcription of interferon-stimulated genes (ISGs). However, whether human PML inhibits HIV-1 has been debated. Here we provide unambiguous, knockout-based evidence that PML does not restrict the early postentry stages of HIV-1 infection in a variety of human cell types and does not participate in the inhibition of HIV-1 by IFN-I. Although this study does not exclude the possibility of other mechanisms by which PML may interfere with HIV-1, we nonetheless demonstrate that PML does not generally act as an HIV-1 restriction factor in human cells and that its presence is not required for IFN-I to stimulate the expression of anti-HIV-1 genes. These results contribute to uncovering the landscape of HIV-1 inhibition by ISGs in human cells.
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17
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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: 3.1] [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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18
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Palzur E, Sharon A, Shehadeh M, Soustiel JF. Investigation of the mechanisms of neuroprotection mediated by Ro5-4864 in brain injury. Neuroscience 2016; 329:162-70. [PMID: 27223627 DOI: 10.1016/j.neuroscience.2016.05.014] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2015] [Revised: 05/07/2016] [Accepted: 05/10/2016] [Indexed: 11/17/2022]
Abstract
Increasing evidence has established the involvement of the 18-kDa translocator protein (TSPO) in the process of mitochondrial membrane permeabilization and subsequent apoptosis through modulation of the mitochondrial permeability transition pore. Recent studies have shown that treatment with Ro5-4864, a TSPO ligand, resulted in a neuroprotective effect in traumatic brain injury. Yet, the nature of this effect remained uncertain as mature neurons are considered to be lacking the TSPO protein. In order to investigate the mechanism of Ro5-4864-mediated neuroprotection, the neuro-inflammatory and neurosteroid response to cortical injury was tested in sham-operated, vehicle, cyclosporine A (CsA) and Ro5-4864-treated rats. As anticipated, the levels of interleukin 1β and tumor necrosis factor α, as well as the astrocyte and microglia cellular density in the injured area were all decreased by CsA in comparison with the vehicle group. By contrast, no visible effect could be observed in Ro5-4864-treated animals. None of the groups showed any significant difference with any other in respect with the expression of brain-derived neurotrophic factor. Double immunofluorescence staining with NeuN and TSPO confirmed the absence of TSPO in native neurons though showed clear evidence of co-localization of TSPO in the cytoplasm of NeuN-stained injured neurons. Altogether, this study shows that the neuronal protection mediated by Ro5-4864 in brain injury cannot be solely attributed to an indirect effect of the ligand on glial TSPO but may also represent the consequence of the modulation of upregulated TSPO in injured neurons. This observation may be of importance for future pharmacological research in neurotrauma.
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Affiliation(s)
- Eilam Palzur
- Eliachar Research Laboratory, Medical Center of the Galilee, Faculty of Medicine in the Galilee, University of Bar Ilan, Naharia 22100, Israel
| | - Aviram Sharon
- Department of Neurosurgery, Medical Center of the Galilee, Faculty of Medicine in the Galilee, University of Bar Ilan, Naharia 22100, Israel
| | - Mona Shehadeh
- Eliachar Research Laboratory, Medical Center of the Galilee, Faculty of Medicine in the Galilee, University of Bar Ilan, Naharia 22100, Israel
| | - Jean Francois Soustiel
- Eliachar Research Laboratory, Medical Center of the Galilee, Faculty of Medicine in the Galilee, University of Bar Ilan, Naharia 22100, Israel; Department of Neurosurgery, Medical Center of the Galilee, Faculty of Medicine in the Galilee, University of Bar Ilan, Naharia 22100, Israel.
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19
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TSPO: kaleidoscopic 18-kDa amid biochemical pharmacology, control and targeting of mitochondria. Biochem J 2016; 473:107-21. [PMID: 26733718 DOI: 10.1042/bj20150899] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The 18-kDa translocator protein (TSPO) localizes in the outer mitochondrial membrane (OMM) of cells and is readily up-regulated under various pathological conditions such as cancer, inflammation, mechanical lesions and neurological diseases. Able to bind with high affinity synthetic and endogenous ligands, its core biochemical function resides in the translocation of cholesterol into the mitochondria influencing the subsequent steps of (neuro-)steroid synthesis and systemic endocrine regulation. Over the years, however, TSPO has also been linked to core cellular processes such as apoptosis and autophagy. It interacts and forms complexes with other mitochondrial proteins such as the voltage-dependent anion channel (VDAC) via which signalling and regulatory transduction of these core cellular events may be influenced. Despite nearly 40 years of study, the precise functional role of TSPO beyond cholesterol trafficking remains elusive even though the recent breakthroughs on its high-resolution crystal structure and contribution to quality-control signalling of mitochondria. All this along with a captivating pharmacological profile provides novel opportunities to investigate and understand the significance of this highly conserved protein as well as contribute the development of specific therapeutics as presented and discussed in the present review.
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20
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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: 56] [Impact Index Per Article: 5.6] [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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21
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Hatty CR, Banati RB. Protein-ligand and membrane-ligand interactions in pharmacology: the case of the translocator protein (TSPO). Pharmacol Res 2015; 100:58-63. [PMID: 26238176 DOI: 10.1016/j.phrs.2015.07.029] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/03/2015] [Revised: 07/28/2015] [Accepted: 07/29/2015] [Indexed: 11/30/2022]
Abstract
The targets of many small molecule drugs are membrane proteins, and traditionally the focus of pharmacology is on the interaction between such receptors and their small molecule drug ligands. However, the lipid membranes of cells and organelles are increasingly appreciated as diverse and dynamic structures that also specifically interact with small molecule drugs and peptides, causing profound changes in the properties of these membranes, and modulating the function of the membrane and the proteins within it. Drug-membrane interactions are likely to have a role in both the therapeutic and toxic activity of a variety of compounds, and their role in the overall pharmacological effect of a drug needs to be understood more clearly. This is the case for the 18 kDa translocator protein (TSPO) and its ligands, where functions that were established based on pharmacological studies are being called into question. Re-examining the putative functions of the TSPO and the effects of its ligands reveals a need to consider in more detail the interplay between protein-ligand and membrane-ligand interactions, and the modulatory relationship between TSPO and the lipid membrane.
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Affiliation(s)
- Claire R Hatty
- Medical Imaging & Radiation Sciences Faculty Research Group, Faculty of Health Sciences, The University of Sydney, Brain & Mind Research Institute, 94 Mallett Street, Camperdown, NSW 2050, Australia.
| | - Richard B Banati
- Medical Imaging & Radiation Sciences Faculty Research Group, Faculty of Health Sciences, The University of Sydney, Brain & Mind Research Institute, 94 Mallett Street, Camperdown, NSW 2050, Australia; Life Sciences, Australian Nuclear Science and Technology Organisation, New Illawarra Road, Lucas Heights, NSW 2234, Australia
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22
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Enigmatic Translocator protein (TSPO) and cellular stress regulation. Trends Biochem Sci 2015; 40:497-503. [PMID: 26228316 DOI: 10.1016/j.tibs.2015.07.001] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2015] [Revised: 06/25/2015] [Accepted: 07/06/2015] [Indexed: 11/23/2022]
Abstract
Translocator proteins (TSPOs) are conserved, ubiquitous membrane proteins identified initially as benzodiazepine-binding proteins in mammalian cells. Recent genetic and biochemical studies have challenged the accepted model that TSPOs are essential and required for steroidogenesis in animal cells. Instead, evidence from different kingdoms of life suggests that TSPOs are encoded by nonessential genes that are temporally upregulated in cells encountering conditions of oxidative stress, including inflammation and tissue injury. Here we discuss how TSPOs may be involved in complex homeostasis signaling mechanisms. We suggest that the main physiological role of TSPOs may be to modulate oxidative stress, irrespective of the cell type or subcellular localization, in part through the subtle regulation of tetrapyrrole metabolism.
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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: 97] [Impact Index Per Article: 9.7] [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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Bonora M, Wieckowski MR, Chinopoulos C, Kepp O, Kroemer G, Galluzzi L, Pinton P. Molecular mechanisms of cell death: central implication of ATP synthase in mitochondrial permeability transition. Oncogene 2015; 34:1475-86. [PMID: 24727893 DOI: 10.1038/onc.2014.96] [Citation(s) in RCA: 164] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2014] [Revised: 02/20/2014] [Accepted: 02/27/2014] [Indexed: 12/14/2022]
Abstract
The term mitochondrial permeability transition (MPT) is commonly used to indicate an abrupt increase in the permeability of the inner mitochondrial membrane to low molecular weight solutes. Widespread MPT has catastrophic consequences for the cell, de facto marking the boundary between cellular life and death. MPT results indeed in the structural and functional collapse of mitochondria, an event that commits cells to suicide via regulated necrosis or apoptosis. MPT has a central role in the etiology of both acute and chronic diseases characterized by the loss of post-mitotic cells. Moreover, cancer cells are often relatively insensitive to the induction of MPT, underlying their increased resistance to potentially lethal cues. Thus, intense efforts have been dedicated not only at the understanding of MPT in mechanistic terms, but also at the development of pharmacological MPT modulators. In this setting, multiple mitochondrial and extramitochondrial proteins have been suspected to critically regulate the MPT. So far, however, only peptidylprolyl isomerase F (best known as cyclophilin D) appears to constitute a key component of the so-called permeability transition pore complex (PTPC), the supramolecular entity that is believed to mediate MPT. Here, after reviewing the structural and functional features of the PTPC, we summarize recent findings suggesting that another of its core components is represented by the c subunit of mitochondrial ATP synthase.
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Affiliation(s)
- M Bonora
- Section of Pathology, Oncology and Experimental Biology, Laboratory for Technologies of Advanced Therapies (LTTA), Department of Morphology, Surgery and Experimental Medicine, Interdisciplinary Centre for the Study of Inflammation (ICSI), University of Ferrara, Ferrara, Italy
| | - M R Wieckowski
- Department of Biochemistry, Nencki Institute of Experimental Biology, Warsaw, Poland
| | - C Chinopoulos
- Department of Medical Biochemistry, Semmelweis University, Budapest, Hungary
| | - O Kepp
- 1] Equipe 11 labelisée par la Ligue Nationale contre le cancer, INSERM U1138, Centre de Recherche des Cordeliers, Paris, France [2] Université Paris Descartes/Paris 5, Sorbonne Paris Cité, Paris, France [3] Metabolomics and Cell Biology platforms, Gustave Roussy Comprehensive Cancer Center, Villejuif, France
| | - G Kroemer
- 1] Equipe 11 labelisée par la Ligue Nationale contre le cancer, INSERM U1138, Centre de Recherche des Cordeliers, Paris, France [2] Université Paris Descartes/Paris 5, Sorbonne Paris Cité, Paris, France [3] Metabolomics and Cell Biology platforms, Gustave Roussy Comprehensive Cancer Center, Villejuif, France [4] Pôle de Biologie, Hôpital Européen Georges Pompidou, AP-HP, Paris, France
| | - L Galluzzi
- 1] Equipe 11 labelisée par la Ligue Nationale contre le cancer, INSERM U1138, Centre de Recherche des Cordeliers, Paris, France [2] Université Paris Descartes/Paris 5, Sorbonne Paris Cité, Paris, France [3] Gustave Roussy Comprehensive Cancer Center, Villejuif, France
| | - P Pinton
- Section of Pathology, Oncology and Experimental Biology, Laboratory for Technologies of Advanced Therapies (LTTA), Department of Morphology, Surgery and Experimental Medicine, Interdisciplinary Centre for the Study of Inflammation (ICSI), University of Ferrara, Ferrara, Italy
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Tu LN, Zhao AH, Stocco DM, Selvaraj V. PK11195 effect on steroidogenesis is not mediated through the translocator protein (TSPO). Endocrinology 2015; 156:1033-9. [PMID: 25535830 PMCID: PMC4330312 DOI: 10.1210/en.2014-1707] [Citation(s) in RCA: 75] [Impact Index Per Article: 7.5] [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) is a mitochondrial outer membrane protein of unknown function with high physiological expression in steroidogenic cells. Using TSPO gene-deleted mice, we recently demonstrated that TSPO function is not essential for steroidogenesis. The first link between TSPO and steroidogenesis was established in studies showing modest increases in progesterone production by adrenocortical and Leydig tumor cell lines after treatment with PK11195. To reconcile discrepancies between physiological and pharmacological interpretations of TSPO function, we generated TSPO-knockout MA-10 mouse Leydig tumor cells (MA-10:TspoΔ/Δ) and examined their steroidogenic potential after exposure to either dibutyryl-cAMP or PK11195. Progesterone production in MA-10:TspoΔ/Δ after dibutyryl-cAMP was not different from control MA-10:Tspo+/+ cells, confirming that TSPO function is not essential for steroidogenesis. Interestingly, when treated with increasing concentrations of PK11195, both control MA-10:Tspo+/+ cells and MA-10:TspoΔ/Δ cells responded in a similar dose-dependent manner showing increases in progesterone production. These results show that the pharmacological effect of PK11195 on steroidogenesis is not mediated through TSPO.
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Affiliation(s)
- Lan N Tu
- Department of Animal Science, College of Agriculture and Life Sciences (L.N.T., A.H.Z., V.S.), Cornell University, Ithaca, New York 14853; and Department of Cell Biology and Biochemistry, School of Medicine (D.M.S.), Texas Tech University Health Sciences Center, Lubbock, Texas 79430
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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: 0.9] [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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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: 369] [Impact Index Per Article: 36.9] [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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Hatty CR, Le Brun AP, Lake V, Clifton LA, Liu GJ, James M, Banati RB. Investigating the interactions of the 18kDa translocator protein and its ligand PK11195 in planar lipid bilayers. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2013; 1838:1019-30. [PMID: 24374318 DOI: 10.1016/j.bbamem.2013.12.013] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2013] [Revised: 12/16/2013] [Accepted: 12/18/2013] [Indexed: 12/20/2022]
Abstract
The functional effects of a drug ligand may be due not only to an interaction with its membrane protein target, but also with the surrounding lipid membrane. We have investigated the interaction of a drug ligand, PK11195, with its primary protein target, the integral membrane 18kDa translocator protein (TSPO), and model membranes using Langmuir monolayers, quartz crystal microbalance with dissipation monitoring (QCM-D) and neutron reflectometry (NR). We found that PK11195 is incorporated into lipid monolayers and lipid bilayers, causing a decrease in lipid area/molecule and an increase in lipid bilayer rigidity. NR revealed that PK11195 is incorporated into the lipid chain region at a volume fraction of ~10%. We reconstituted isolated mouse TSPO into a lipid bilayer and studied its interaction with PK11195 using QCM-D, which revealed a larger than expected frequency response and indicated a possible conformational change of the protein. NR measurements revealed a TSPO surface coverage of 23% when immobilised to a modified surface via its polyhistidine tag, and a thickness of 51Å for the TSPO layer. These techniques allowed us to probe both the interaction of TSPO with PK11195, and PK11195 with model membranes. It is possible that previously reported TSPO-independent effects of PK11195 are due to incorporation into the lipid bilayer and alteration of its physical properties. There are also implications for the variable binding profiles observed for TSPO ligands, as drug-membrane interactions may contribute to the apparent affinity of TSPO ligands.
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Affiliation(s)
- Claire R Hatty
- Medical Imaging & Radiation Sciences Faculty Research Group, Faculty of Health Sciences, The University of Sydney, c/o Brain & Mind Research Institute, 94 Mallett Street, Camperdown, NSW 2050, Australia
| | - Anton P Le Brun
- Bragg Institute, Australian Nuclear Science and Technology Organisation, New Illawarra Road, Lucas Heights, NSW 2234, Australia
| | - Vanessa Lake
- Bragg Institute, Australian Nuclear Science and Technology Organisation, New Illawarra Road, Lucas Heights, NSW 2234, Australia
| | - Luke A Clifton
- ISIS Pulsed Neutron and Muon Source, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Oxford, Didcot OX11 0QX, UK
| | - Guo Jun Liu
- Medical Imaging & Radiation Sciences Faculty Research Group, Faculty of Health Sciences, The University of Sydney, c/o Brain & Mind Research Institute, 94 Mallett Street, Camperdown, NSW 2050, Australia; Life Sciences, Australian Nuclear Science and Technology Organisation, New Illawarra Road, Lucas Heights, NSW 2234, Australia
| | - Michael James
- Bragg Institute, Australian Nuclear Science and Technology Organisation, New Illawarra Road, Lucas Heights, NSW 2234, Australia; School of Chemistry, University of New South Wales, Kensington NSW 2052, Australia
| | - Richard B Banati
- Medical Imaging & Radiation Sciences Faculty Research Group, Faculty of Health Sciences, The University of Sydney, c/o Brain & Mind Research Institute, 94 Mallett Street, Camperdown, NSW 2050, Australia; Life Sciences, Australian Nuclear Science and Technology Organisation, New Illawarra Road, Lucas Heights, NSW 2234, Australia.
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Li F, Xia Y, Meiler J, Ferguson-Miller S. Characterization and modeling of the oligomeric state and ligand binding behavior of purified translocator protein 18 kDa from Rhodobacter sphaeroides. Biochemistry 2013; 52:5884-99. [PMID: 23952237 PMCID: PMC3756528 DOI: 10.1021/bi400431t] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
![]()
Translocator
Protein 18 kDa (TSPO), previously known as the peripheral-type
benzodiazepine receptor (PBR), is a mitochondrial outer membrane protein
that has been identified as a key player in cholesterol and porphyrin
transport, apoptotic signaling, and cancer development, as well as
neurological inflammation and disease. Despite a number of TSPO ligands
whose effects have been studied with respect to these varied biological
activities, the nature of their interactions with TSPO and the molecular
mechanism of their effects remain controversial, in part because of
the lack of an atomic-resolution structure. We expressed and purified
the homologue of mammalian TSPO from Rhodobacter sphaeroides (RsTSPO), as well as a mutant form in a proposed
drug binding loop, RsTSPOW38C. We characterized their
binding behaviors with endogenous ligands and a series of compounds
that affect apoptosis by using a sensitive tryptophan fluorescence
quenching assay. Our results show that RsTSPO behaves
as a dimer in the purified state and binds with low micromolar affinity
to many of these ligands, including retinoic acid, curcumin, and a
known Bcl-2 inhibitor, gossypol, suggesting a possible direct role
for TSPO in their regulation of apoptosis. A computational model of
the RsTSPO dimer is constructed using EM-Fold, Rosetta,
and a cryo-electron microscopy density map. Binding behaviors of known
ligands are discussed in the context of the model with respect to
regions that may be involved in binding.
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Affiliation(s)
- Fei Li
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824, United States
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The 18-kDa translocator protein (TSPO) disrupts mammary epithelial morphogenesis and promotes breast cancer cell migration. PLoS One 2013; 8:e71258. [PMID: 23967175 PMCID: PMC3743866 DOI: 10.1371/journal.pone.0071258] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2013] [Accepted: 06/27/2013] [Indexed: 12/04/2022] Open
Abstract
Mitochondria play important roles in cancer progression and have emerged as viable targets for cancer therapy. Increasing levels of the outer mitochondrial membrane protein, 18-kDa translocator protein (TSPO), are associated with advancing breast cancer stage. In particular, higher TSPO levels are found in estrogen receptor (ER)-negative breast tumors, compared with ER-positive tumors. In this study, we sought to define the roles of TSPO in the acquisition of breast cancer malignancy. Using a three-dimensional Matrigel culture system, we determined the impact of elevated TSPO levels on mammary epithelial morphogenesis. Our studies demonstrate that stable overexpression of TSPO in mammary epithelial MCF10A acini drives proliferation and provides partial resistance to luminal apoptosis, resulting in enlarged acinar structures with partially filled lumen that resemble early stage breast lesions leading to breast cancer. In breast cancer cell lines, TSPO silencing or TSPO overexpression significantly altered the migratory activity. In addition, we found that combination treatment with the TSPO ligands (PK 11195 or Ro5-4864) and lonidamine, a clinical phase II drug targeting mitochondria, decreased viability of ER-negative breast cancer cell lines. Taken together, these data demonstrate that increases in TSPO levels at different stages of breast cancer progression results in the acquisition of distinct properties associated with malignancy. Furthermore, targeting TSPO, particularly in combination with other mitochondria-targeting agents, may prove useful for the treatment of ER-negative breast cancer.
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Rasagiline prevents apoptosis induced by PK11195, a ligand of the outer membrane translocator protein (18 kDa), in SH-SY5Y cells through suppression of cytochrome c release from mitochondria. J Neural Transm (Vienna) 2013; 120:1539-51. [PMID: 23681678 DOI: 10.1007/s00702-013-1033-x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2013] [Accepted: 05/02/2013] [Indexed: 12/13/2022]
Abstract
Rasagiline protects neuronal cells from cell death caused by various lines of insults. Its neuroprotective function is due to suppression of mitochondrial apoptosis signaling and induction of neuroprotective genes, including Bcl-2 and neurotrophic factors. Rasagiline inhibits the mitochondrial membrane permeabilization, an initial stage in apoptosis, but the mechanism has been elusive. In this paper, it was investigated how rasagiline regulates mitochondrial death cascade in apoptosis induced in SH-SY5Y cells by PK11195, a ligand of the outer membrane translocator protein of 18 kDa. Rasagiline prevented release of cytochrome c (Cyt-c), and the following caspase 3 activation, ATP depletion and apoptosis, but did not inhibit the mitochondrial membrane potential collapse, in contrast to Bcl-2 overexpression. Rasagiline stabilized the mitochondrial contact site and suppressed Cyt-c release into cytoplasm, which should be the critical point for the regulation of apoptosis. Monoamine oxidase was not associated with anti-apoptotic activity of rasagiline in PK11195-induced apoptosis.
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Mendonça-Torres MC, Roberts SS. The translocator protein (TSPO) ligand PK11195 induces apoptosis and cell cycle arrest and sensitizes to chemotherapy treatment in pre- and post-relapse neuroblastoma cell lines. Cancer Biol Ther 2013; 14:319-26. [PMID: 23358477 DOI: 10.4161/cbt.23613] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
High-risk neuroblastoma (NB) has a poor prognosis. Even with intensive myeloablative chemotherapy, relapse is common and almost uniformly fatal, and new treatments are needed. Translocator protein 18kDa (TSPO) ligands have been studied as potential new therapeutic agents in many cancers, but not in NB. We studied the effects of TSPO ligands on cell proliferation, cell cycle progression and apoptosis using paired cell lines derived from the same patient at the time of initial surgery and again after development of progressive disease or relapse post-chemotherapy. We found that TSPO expression was significantly increased 2- to 10-fold in post-relapse cell lines compared with pre-treatment lines derived from the same individual. Subsequently, these cell lines were treated with the specific TSPO ligand 1-(2-chlorophenyl-N-methylpropyl)-3-isoquinolinecarboxamide (PK11195) (0-160µM) as a single agent, with cytotoxic chemotherapy agents alone (carboplatin, etoposide or melphalan), or with combinations of PK11195 and chemotherapy drugs. We found that PK11195 inhibited proliferation in a dose-dependent manner, induced apoptosis and caused G 1/S cell cycle arrest in all tested NB cell lines at micromolar concentrations. In addition, PK11195 significantly decreased mRNA expression of the chemotherapy resistance efflux pumps ABCA3, ABCB1 and ABCC1 in two post-relapse NB cell lines. We also found that pre-treatment with PK11195 sensitized these cell lines to treatment with cytotoxic chemotherapy agents. These results suggest that PK11195 alone or in combination with standard chemotherapeutic drugs warrants further study for the treatment of neuroblastoma.
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Affiliation(s)
- Maria C Mendonça-Torres
- Department of Pediatrics, Division of Hematology/Oncology, Uniformed Services University of the Health Sciences, Bethesda, MD USA
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Abstract
Improving the control of energy homeostasis can lower cardiovascular risk in metabolically compromised individuals. To identify new regulators of whole-body energy control, we conducted a high-throughput screen in transgenic reporter zebrafish for small molecules that modulate the expression of the fasting-inducible gluconeogenic gene pck1. We show that this in vivo strategy identified several drugs that impact gluconeogenesis in humans, as well as metabolically uncharacterized compounds. Most notably, we find that the Translocator Protein (TSPO) ligands PK 11195 and Ro5-4864 are glucose lowering agents despite a strong inductive effect on pck1 expression. We show that these drugs are activators of a fasting-like energy state, and importantly that they protect high-fat diet induced obese mice from hepatosteatosis and glucose intolerance, two pathological manifestations of metabolic dysregulation. Thus, using a whole-organism screening strategy, this study has identified new small molecule activators of fasting metabolism.
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The 18 kDa translocator protein influences angiogenesis, as well as aggressiveness, adhesion, migration, and proliferation of glioblastoma cells. Pharmacogenet Genomics 2012; 22:538-50. [PMID: 22547081 DOI: 10.1097/fpc.0b013e3283539cdc] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
BACKGROUND It is known that the mitochondrial 18 kDa translocator protein (TSPO) is present in almost all peripheral tissues and also in glial cells in the brain. TSPO levels are typically enhanced in correlation with tumorigenesis of cancer cells including glioblastoma. Relevant for angiogenesis, TSPO is also present in almost all cells of the cardiovascular system. METHODS We studied the effect of TSPO knockdown by siRNA on various aspects of tumor growth of U118MG glioblastoma cells in two in-vivo models: a nude mouse model with intracerebral implants of U118MG glioblastoma cells and implantation of U118MG glioblastoma cells on the chorionallantoic membrane (CAM) of chicken embryos. In vitro, we further assayed the influence of TSPO on the invasive potential of U118MG cells. RESULTS TSPO knockdown increased tumor growth in both in-vivo models compared with the scrambled siRNA control. Angiogenesis was also increased by TSPO knockdown as determined by a CAM assay. TSPO knockdown led to a decrease in adhesion to the proteins of the extracellular matrix, including fibronectin, collagen I, collagen IV, laminin I, and fibrinogen. TSPO knockdown also led to an enhancement in the migratory capability of U118MG cells, as determined in a modified Boyden chamber. Application of the TSPO ligand 1-(2-chlorophenyl)-N-methyl-N-(1-methylpropyl)-3-isoquinolinecarboxamide (PK 11195) at a concentration of 25 µmol/l in the in-vitro models yielded results similar to those obtained on TSPO knockdown. We found no effects of PK 11195 on TSPO protein expression. Interestingly, at low nmol/l concentrations (around 1 nmol/l), PK 11195 enhanced adhesion to collagen I, suggesting a bimodal concentration effect of PK 11195. CONCLUSION Intact TSPO appears to be able to counteract the invasive and angiogenic characteristics related to the aggressiveness of U118MG glioblastoma cells in vivo and in vitro.
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Takai N, Kira N, Ishii T, Yoshida T, Nishida M, Nishida Y, Nasu K, Takano M, Midori H, Koga S, Narahara H. RETRACTED ARTICLE: A translocator protein ligand PK11195 shows antigrowth activity in human choriocarcinoma cells. Tumour Biol 2012; 33:1505-10. [DOI: 10.1007/s13277-012-0401-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2012] [Accepted: 04/05/2012] [Indexed: 10/28/2022] Open
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Vidau C, González-Polo RA, Niso-Santano M, Gómez-Sánchez R, Bravo-San Pedro JM, Pizarro-Estrella E, Blasco R, Brunet JL, Belzunces LP, Fuentes JM. Fipronil is a powerful uncoupler of oxidative phosphorylation that triggers apoptosis in human neuronal cell line SHSY5Y. Neurotoxicology 2011; 32:935-43. [PMID: 21621551 DOI: 10.1016/j.neuro.2011.04.006] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2011] [Revised: 03/04/2011] [Accepted: 04/20/2011] [Indexed: 11/28/2022]
Abstract
Fipronil is a phenylpyrazole insecticide known to elicit neurotoxicity via an interaction with ionotropic receptors, namely GABA and glutamate receptors. Recently, we showed that fipronil and other phenylpyrazole compounds trigger cell death in Caco-2 cells. In this study, we investigated the mode of action and the type of cell death induced by fipronil in SH-SY5Y human neuroblastoma cells. Flow cytometric and western blot analyses demonstrated that fipronil induces cellular events belonging to the apoptosis process, such as mitochondrial potential collapse, cytochrome c release, caspase-3 activation, nuclear condensation and phosphatidylserine externalization. In addition, fipronil induces a rapid ATP depletion with concomitant activation of anaerobic glycolysis. This cellular response is characteristic of mitochondrial injury associated with a defect of the respiration process. Therefore, we also investigated the effect of fipronil on the oxygen consumption in isolated mitochondria. Interestingly, we show for the first time that fipronil is a strong uncoupler of oxidative phosphorylation at relative low concentrations. Thus in this study, we report a new mode of action by which the insecticide fipronil could triggers apoptosis.
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Affiliation(s)
- Cyril Vidau
- INRA, Laboratoire de toxicologie environnementale, UMR 406, Abeille et environnement, 84914 Avignon Cedex 9, France
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Rupprecht R, Papadopoulos V, Rammes G, Baghai TC, Fan J, Akula N, Groyer G, Adams D, Schumacher M. Translocator protein (18 kDa) (TSPO) as a therapeutic target for neurological and psychiatric disorders. Nat Rev Drug Discov 2011; 9:971-88. [PMID: 21119734 DOI: 10.1038/nrd3295] [Citation(s) in RCA: 747] [Impact Index Per Article: 53.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The translocator protein (18 kDa) (TSPO) is localized primarily in the outer mitochondrial membrane of steroid-synthesizing cells, including those in the central and peripheral nervous system. One of its main functions is the transport of the substrate cholesterol into mitochondria, a prerequisite for steroid synthesis. TSPO expression may constitute a biomarker of brain inflammation and reactive gliosis that could be monitored by using TSPO ligands as neuroimaging agents. Moreover, initial clinical trials have indicated that TSPO ligands might be valuable in the treatment of neurological and psychiatric disorders. This Review focuses on the biology and pathophysiology of TSPO and the potential of currently available TSPO ligands for the diagnosis and treatment of neurological and psychiatric disorders.
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Affiliation(s)
- Rainer Rupprecht
- Department of Psychiatry and Psychotherapy, Ludwig-Maximilians University, Nussbaumstrasse 7, 80336 Munich, Germany.
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Wemeau M, Kepp O, Tesnière A, Panaretakis T, Flament C, De Botton S, Zitvogel L, Kroemer G, Chaput N. Calreticulin exposure on malignant blasts predicts a cellular anticancer immune response in patients with acute myeloid leukemia. Cell Death Dis 2010; 1:e104. [PMID: 21368877 PMCID: PMC3032293 DOI: 10.1038/cddis.2010.82] [Citation(s) in RCA: 108] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Experiments performed in mice revealed that anthracyclines stimulate immunogenic cell death that is characterized by the pre-apoptotic exposure of calreticulin (CRT) on the surface of dying tumor cells. Here, we determined whether CRT exposure at the cell surface (ecto-CRT) occurs in human cancer in response to anthracyclines in vivo, focusing on acute myeloid leukemia (AML), which is currently treated with a combination of aracytine and anthracyclines. Most of the patients benefit from the induction chemotherapy but relapse within 1–12 months. In this study, we investigated ecto-CRT expression on malignant blasts before and after induction chemotherapy. We observed that leukemic cells from some patients exhibited ecto-CRT regardless of chemotherapy and that this parameter was not modulated by in vivo chemotherapy. Ecto-CRT correlated with the presence of phosphorylated eIF2α within the blasts, in line with the possibility that CRT exposure results from an endoplasmic reticulum stress response. Importantly, high levels of ecto-CRT on malignant myeloblasts positively correlated with the ability of autologous T cells to secrete interferon-γ on stimulation with blast-derived dendritic cell. We conclude that the presence of ecto-CRT on leukemia cells facilitates cellular anticancer immune responses in AML patients.
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Affiliation(s)
- M Wemeau
- Institut National de la Santé et de la Recherche Médicale, Villejuif, France
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40
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Leducq-Alet N, Vin V, Savi P, Bono F. TNF-alpha induced PMN apoptosis in whole human blood: Protective effect of SSR180575, a potent and selective peripheral benzodiazepine ligand. Biochem Biophys Res Commun 2010; 399:475-9. [DOI: 10.1016/j.bbrc.2010.07.011] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2010] [Accepted: 07/03/2010] [Indexed: 10/19/2022]
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41
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Ho WP, Chan WP, Hsieh MS, Chen RM. Runx2-mediated bcl-2 gene expression contributes to nitric oxide protection against hydrogen peroxide-induced osteoblast apoptosis. J Cell Biochem 2010; 108:1084-93. [PMID: 19746447 DOI: 10.1002/jcb.22338] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Nitric oxide (NO) can regulate osteoblast activities. This study was aimed to evaluate the protective effects of pretreatment with sodium nitroprusside (SNP) as a source of NO on hydrogen peroxide-induced osteoblast insults and its possible mechanisms. Exposure of human osteosarcoma MG63 cells to hydrogen peroxide significantly increased cellular oxidative stress, but decreased ALP activity and cell viability, inducing cell apoptosis. Pretreatment with 0.3 mM SNP significantly lowered hydrogen peroxide-induced cell insults. Treatment of human MG63 cells with hydrogen peroxide inhibited Bcl-2 mRNA and protein production, but pretreatment with 0.3 mM SNP significantly ameliorated such inhibition. Sequentially, hydrogen peroxide decreased the mitochondrial membrane potential, but increased the levels of cytochrome c and caspase-3 activity. Pretreatment with 0.3 mM SNP significantly lowered such alterations. Exposure to hydrogen peroxide decreased Runx2 mRNA and protein syntheses. However, pretreatment with 0.3 mM SNP significantly lowered the suppressive effects. Runx2 knockdown using RNA interference inhibited Bcl-2 mRNA production in human MG63 cells. Protection of pretreatment with 0.3 mM SNP against hydrogen peroxide-induced alterations in ALP activity, caspase-3 activity, apoptotic cells, and cell viability were also alleviated after administration of Runx2 small interference RNA. Thus, this study shows that pretreatment with 0.3 mM SNP can protect human MG63 cells from hydrogen peroxide-induced apoptotic insults possibly via Runx2-involved regulation of bcl-2 gene expression.
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Affiliation(s)
- Wei-Pin Ho
- Department of Orthopedic Surgery, Taipei Medical University-Wan Fang Hospital, Taipei, Taiwan, ROC
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42
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Bertomeu T, Zvereff V, Ibrahim A, Zehntner SP, Aliaga A, Rosa-Neto P, Bedell BJ, Falardeau P, Gourdeau H. TLN-4601 peripheral benzodiazepine receptor (PBR/TSPO) binding properties do not mediate apoptosis but confer tumor-specific accumulation. Biochem Pharmacol 2010; 80:1572-9. [PMID: 20655882 DOI: 10.1016/j.bcp.2010.07.018] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2010] [Revised: 07/05/2010] [Accepted: 07/12/2010] [Indexed: 12/22/2022]
Abstract
TLN-4601 is a farnesylated dibenzodiazepinone isolated from Micromonospora sp. with an antiproliferative effect on several human cancer cell lines. Although the mechanism of action of TLN-4601 is unknown, our earlier work indicated that TLN-4601 binds the PBR (peripheral benzodiazepine receptor; more recently known as the translocator protein or TSPO), an 18 kDa protein associated with the mitochondrial permeability transition (mPT) pore. While the exact function of the PBR remains a matter of debate, it has been implicated in heme and steroid synthesis, cellular growth and differentiation, oxygen consumption and apoptosis. Using the Jurkat immortalized T-lymphocyte cell line, documented to have negligible PBR expression, and Jurkat cells stably transfected with a human PBR cDNA, the present study demonstrates that TLN-4601 induces apoptosis independently of PBR expression. As PBRs are overexpressed in brain tumors compared to normal brain, we examined if TLN-4601 would preferentially accumulate in tumors using an intra-cerebral tumor model. Our results demonstrate the ability of TLN-4601 to effectively bind the PBR in vivo as determined by competitive binding assay and receptor occupancy. Analysis of TLN-4601 tissue and plasma indicated that TLN-4601 preferentially accumulates in the tumor. Indeed, drug levels were 200-fold higher in the tumor compared to the normal brain. TLN-4601 accumulation in the tumor (176 μg/g) was also significant compared to liver (24.8 μg/g; 7-fold) and plasma (16.2 μg/mL; 11-fold). Taken together our data indicate that while PBR binding does not mediate cell growth inhibition and apoptosis, PBR binding may allow for the specific accumulation of TLN-4601 in PBR positive tumors.
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Affiliation(s)
- T Bertomeu
- Thallion Pharmaceuticals Inc., 7150 Alexander-Fleming, Montréal, QC, H4S 2C8, Canada
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43
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Abstract
Mitochondria are the cells' powerhouse, but also their suicidal weapon store. Dozens of lethal signal transduction pathways converge on mitochondria to cause the permeabilization of the mitochondrial outer membrane, leading to the cytosolic release of pro-apoptotic proteins and to the impairment of the bioenergetic functions of mitochondria. The mitochondrial metabolism of cancer cells is deregulated owing to the use of glycolytic intermediates, which are normally destined for oxidative phosphorylation, in anabolic reactions. Activation of the cell death machinery in cancer cells by inhibiting tumour-specific alterations of the mitochondrial metabolism or by stimulating mitochondrial membrane permeabilization could therefore be promising therapeutic approaches.
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Affiliation(s)
- Simone Fulda
- University Children's Hospital, Ulm University, Eythstrasse 24, D-89075 Ulm, Germany.
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44
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Mukhopadhyay S, Guillory B, Mukherjee S, Das SK. Antiproliferative effect of peripheral benzodiazepine receptor antagonist PK11195 in rat mammary tumor cells. Mol Cell Biochem 2010; 340:203-13. [PMID: 20204676 DOI: 10.1007/s11010-010-0419-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2009] [Accepted: 02/10/2010] [Indexed: 01/26/2023]
Abstract
This study aims to establish the antiproliferative effects of PK11195, a peripheral benzodiazepine receptor antagonist (PBR) in rat mammary tumor cells. Breast tumors were induced by administration of a carcinogen, dimethylbenz[a]anthracene to 50-day-old female rats maintained on a standard AIN-76A diet with casein as the protein source. The tumors were developed approximately after 120 days. The tumors were of grade I (20%), grade II (60%), and grade III (20%). The tumors were isolated and cultured in DMEM/F12 media with supplements. We characterized the properties of the isolated cells and study the effect of PK11195 on those cells. We were successful in growing breast tumor cells up to 30 passages for cellular characterization. These cells had high reactivity with Ki-67 and PCNA antibodies suggesting high proliferation rate. These cells were highly invasive as evident by matrigel invading ability. Furthermore, these cells acquired a positive response for CD-31 and VEGF antibodies suggesting angiogenic potential, and also possessed migrating ability/motility as evident by the wound healing properties. These cells expressed elevated levels of PBR, a cancer promoting gene. The proliferation, invasion and migration appear to decrease when treated with PK11195, a PBR antagonist. Furthermore, PK11195 treatment caused an increase in apoptosis as evident by increase in the levels of annexin V. However, the inhibition of cell proliferation by PK11195 was counteracted by Ro5-4864, a PBR agonist. Thus, PBR antagonist may be a potential therapeutic agent for the control of aggressiveness of breast cancer.
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Affiliation(s)
- Sutapa Mukhopadhyay
- Department of Cancer Biology, Meharry Medical College, 1005 D.B.Todd Blvd., Nashville, TN 37208, USA
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45
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Binding of NIR-conPK and NIR-6T to astrocytomas and microglial cells: evidence for a protein related to TSPO. PLoS One 2009; 4:e8271. [PMID: 20020060 PMCID: PMC2792720 DOI: 10.1371/journal.pone.0008271] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2009] [Accepted: 11/12/2009] [Indexed: 12/02/2022] Open
Abstract
PK 11195 and DAA1106 bind with high-affinity to the translocator protein (TSPO, formerly known as the peripheral benzodiazepine receptor). TSPO expression in glial cells increases in response to cytokines and pathological stimuli. Accordingly, [11C]-PK 11195 and [11C]-DAA1106 are recognized molecular imaging (MI) agents capable of monitoring changes in TSPO expression occurring in vivo and in response to various neuropathologies. Here we tested the pharmacological characteristics and TSPO-monitoring potential of two novel MI agents: NIR-conPK and NIR-6T. NIR-conPK is an analogue of PK 11195 conjugated to the near-infrared (NIR) emitting fluorophore: IRDye 800CW. NIR-6T is a DAA1106 analogue also conjugated to IRDye 800CW. We found that NIR-6T competed for [3H]-PK 11195 binding in astrocytoma cell homogenates with nanomolar affinity, but did not exhibit specific binding in intact astrocytoma cells in culture, indicating that NIR-6T is unlikely to constitute a useful MI agent for monitoring TSPO expression in intact cells. Conversely, we found that NIR-conPK did not compete for [3H]-PK 11195 binding in astrocytoma cell homogenate, but exhibited specific binding in intact astrocytoma cells in culture with nanomolar affinity, suggesting that NIR-conPK binds to a protein distinct, but related to, TSPO. Accordingly, treating intact astrocytoma cells and microglia in culture with cytokines led to significant changes in the amount of NIR-conPK specific binding without corresponding change in TSPO expression. Remarkably, the cytokine-induced changes in the protein targeted by NIR-conPK in intact microglia were selective, since IFN-γ (but not TNFα and TGFβ) increased the amount of NIR-conPK specific binding in these cells. Together these results suggest that NIR-conPK binds to a protein that is related to TSPO, and expressed by astrocytomas and microglia. Our results also suggest that the expression of this protein is increased by specific cytokines, and thus allows for the monitoring of a particular subtype of microglia activation.
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46
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Galluzzi L, Morselli E, Kepp O, Vitale I, Rigoni A, Vacchelli E, Michaud M, Zischka H, Castedo M, Kroemer G. Mitochondrial gateways to cancer. Mol Aspects Med 2009; 31:1-20. [PMID: 19698742 DOI: 10.1016/j.mam.2009.08.002] [Citation(s) in RCA: 190] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2009] [Revised: 08/12/2009] [Accepted: 08/13/2009] [Indexed: 12/29/2022]
Abstract
Mitochondria are required for cellular survival, yet can also orchestrate cell death. The peculiar biochemical properties of these organelles, which are intimately linked to their compartmentalized ultrastructure, provide an optimal microenvironment for multiple biosynthetic and bioenergetic pathways. Most intracellular ATP is generated by mitochondrial respiration, which also represents the most relevant source of intracellular reactive oxygen species. Mitochondria participate in a plethora of anabolic pathways, including cholesterol, cardiolipin, heme and nucleotide biosynthesis. Moreover, mitochondria integrate numerous pro-survival and pro-death signals, thereby exerting a decisive control over several biochemical cascades leading to cell death, in particular the intrinsic pathway of apoptosis. Therefore, it is not surprising that cancer cells often manifest the deregulation of one or several mitochondrial functions. The six classical hallmarks of cancer (i.e., limitless replication, self-provision of proliferative stimuli, insensitivity to antiproliferative signals, disabled apoptosis, sustained angiogenesis, invasiveness/metastatic potential), as well as other common features of tumors (i.e., avoidance of the immune response, enhanced anabolic metabolism, disabled autophagy) may directly or indirectly implicate deregulated mitochondria. In this review, we discuss several mechanisms by which mitochondria can contribute to malignant transformation and tumor progression.
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Affiliation(s)
- Lorenzo Galluzzi
- INSERM, U848, Institut Gustave Roussy, PR1, 39 Rue Camille Desmoulins, F-94805 Villejuif, France
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47
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Krestinina OV, Grachev DE, Odinokova IV, Reiser G, Evtodienko YV, Azarashvili TS. Effect of peripheral benzodiazepine receptor (PBR/TSPO) ligands on opening of Ca2+-induced pore and phosphorylation of 3.5-kDa polypeptide in rat brain mitochondria. BIOCHEMISTRY (MOSCOW) 2009; 74:421-9. [PMID: 19463096 DOI: 10.1134/s0006297909040105] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The effect of nanomolar concentrations of PBR/TSPO ligands--Ro 5-4864, PK11195, and PPIX--on Ca2+-induced permeability transition pore (PTP) opening in isolated rat brain mitochondria was investigated. PBR/TSPO agonist Ro 5-4864 (100 nM) and endogenous ligand PPIX (1 microM) were shown to stimulate PTP opening, while antagonist PK11195 (100 nM) suppressed this process. Correlation between PBR ligand action on PTP opening and phosphorylation of a 3.5 kDa polypeptide was investigated. In intact brain mitochondria, incorporation of [gamma-(32)P]ATP into 3.5 kDa peptide was decreased in the presence of Ro 5-4864 and PPIX and increased in the presence of PK11195. At threshold Ca2+ concentrations leading to PTP opening, PBR/TSPO ligands were found to stimulate dephosphorylation of the 3.5 kDa peptide. Specific anti-PBR/TSPO antibody prevented both PTP opening and dephosphorylation of the 3.5-kDa peptide. The peptide was identified as subunit c of F(o)F(1)-ATPase by Western blot using specific anti-subunit c antibody. The results suggest that subunit c of F(o)F(1)-ATPase could be an additional target for PBR/TSPO ligands action, is subjected to Ca2+- and TSPO-dependent phosphorylation/dephosphorylation, and is involved in PTP operation in mitochondria.
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Affiliation(s)
- O V Krestinina
- Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, Pushchino, Moscow Region, 142290, Russia
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48
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González-Polo RA, Niso-Santano M, Morán JM, Ortiz-Ortiz MA, Bravo-San Pedro JM, Soler G, Fuentes JM. Silencing DJ-1 reveals its contribution in paraquat-induced autophagy. J Neurochem 2009; 109:889-98. [DOI: 10.1111/j.1471-4159.2009.06020.x] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Favreau F, Rossard L, Zhang K, Desurmont T, Manguy E, Belliard A, Fabre S, Liu J, Han Z, Thuillier R, Papadopoulos V, Hauet T. Expression and modulation of translocator protein and its partners by hypoxia reoxygenation or ischemia and reperfusion in porcine renal models. Am J Physiol Renal Physiol 2009; 297:F177-90. [PMID: 19386723 DOI: 10.1152/ajprenal.90422.2008] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Translocator protein (TSPO), formerly known as the peripheral-type benzodiazepine receptor, is an 18-kDa drug- and cholesterol-binding protein localized to the outer mitochondrial membrane and implicated in a variety of cell and mitochondrial functions. To determine the role of TSPO in ischemia-reperfusion injury (IRI), we used both in vivo and in vitro porcine models: an in vivo renal ischemia model where different conservation modalities were tested and an in vitro model where TSPO-transfected porcine proximal tubule LLC-PK(1) cells were exposed to hypoxia and oxidative stress. The expression of TSPO and its partners in steroidogenic cells, steroidogenic acute regulatory protein (StAR) and cytochrome P-450 side chain cleavage CYP11A1, as well as the impact of TSPO overexpression and exposure to TSPO ligands in vitro in hypoxia-ischemia conditions were investigated. Hypoxia induced caspase activation, reduction of ATP content, and LLC-PK(1) cell death. Transfection and overexpression of TSPO rescued the cells from the detrimental effects of hypoxia and reoxygenation. Moreover, TSPO overexpression was accompanied by a reduction of H(2)O(2)-induced necrosis. TSPO drug ligands did not affect TSPO-mediated functions. In vivo, TSPO expression was modulated by IRI and during regeneration particularly in proximal tubule cells, which do not express this protein at the basal level. Under the same conditions, StAR and CYP11A1 protein and gene expression was reduced without apparent relation to TSPO changes. Pregnenolone was identified and measured in the pig kidney. Pregnenolone synthesis was not affected by the experimental conditions used. Taken together, these results indicate that changes in TSPO expression in kidney regenerating tissue could be important for renal protection and maintenance of kidney function.
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Affiliation(s)
- Frederic Favreau
- Inserm, U927, Faculté de Médecine, Université de Poitiers, 86021 Poitiers Cedex, France
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50
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Berridge MV, Herst PM, Lawen A. Targeting mitochondrial permeability in cancer drug development. Mol Nutr Food Res 2008; 53:76-86. [DOI: 10.1002/mnfr.200700493] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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