1
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Fairley LH, Lai KO, Grimm A, Eckert A, Barron AM. The mitochondrial translocator protein (TSPO) in Alzheimer's disease: Therapeutic and immunomodulatory functions. Biochimie 2024; 224:120-131. [PMID: 38971458 DOI: 10.1016/j.biochi.2024.07.003] [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: 01/12/2024] [Revised: 07/03/2024] [Accepted: 07/03/2024] [Indexed: 07/08/2024]
Abstract
The translocator protein (TSPO) has been widely investigated as a PET-imaging biomarker of neuroinflammation and, more recently, as a therapeutic target for the treatment of neurodegenerative disease. TSPO ligands have been shown to exert neuroprotective effects in vivo and in vitro models of Alzheimer's disease (AD), by reducing toxic beta amyloid peptides, and attenuating brain atrophy. Recent transcriptomic and proteomic analyses, and the generation of TSPO-KO mice, have enabled new insights into the mechanistic function of TSPO in AD. Using a multi-omics approach in both TSPO-KO- and TSPO ligand-treated mice, we have demonstrated a key role for TSPO in microglial respiratory metabolism and phagocytosis in AD. In this review, we discuss emerging evidence for therapeutic and immunomodulatory functions of TSPO in AD, and new tools for studying TSPO in the brain.
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Affiliation(s)
- Lauren H Fairley
- Lee Kong Chian School of Medicine, Nanyang Technological University Singapore, 308232, Singapore
| | - Kei Onn Lai
- Lee Kong Chian School of Medicine, Nanyang Technological University Singapore, 308232, Singapore
| | - Amandine Grimm
- Transfaculty Research Platform, Molecular & Cognitive Neuroscience, Neurobiology Laboratory for Brain Aging and Mental Health, University of Basel, Basel, Switzerland; Psychiatric University Clinics, Basel, Switzerland
| | - Anne Eckert
- Transfaculty Research Platform, Molecular & Cognitive Neuroscience, Neurobiology Laboratory for Brain Aging and Mental Health, University of Basel, Basel, Switzerland; Psychiatric University Clinics, Basel, Switzerland
| | - Anna M Barron
- Lee Kong Chian School of Medicine, Nanyang Technological University Singapore, 308232, Singapore.
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2
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Bréhat J, Issop L, Morin D. History of Tspo deletion and induction in vivo: Phenotypic outcomes under physiological and pathological situations. Biochimie 2024; 224:80-90. [PMID: 38432291 DOI: 10.1016/j.biochi.2024.03.001] [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: 12/21/2023] [Revised: 02/23/2024] [Accepted: 03/01/2024] [Indexed: 03/05/2024]
Abstract
The mitochondrial translocator protein (TSPO) is an outer mitochondrial protein membrane with high affinity for cholesterol. It is expressed in most tissues but is more particularly enriched in steroidogenic tissues. TSPO is involved in various biological mechanisms and TSPO regulation has been related to several diseases. However, despite a considerable number of published studies interested in TSPO over the past forty years, the precise function of the protein remains obscure. Most of the functions attributed to TSPO have been identified using pharmacological ligands of this protein, leading to much debate about the accuracy of these findings. In addition, research on the physiological role of TSPO has been hampered by the lack of in vivo deletion models. Studies to perform genetic deletion of Tspo in animal models have long been unsuccessful, which led to the conclusions that the deletion was deleterious and the gene essential to life. During the last decades, thanks to the significant technical advances allowing genome modification, several models of animal genetically modified for TSPO have been developed. These models have modified our view regarding TSPO and profoundly improved our fundamental knowledge on this protein. However, to date, they did not allow to elucidate the precise molecular function of TSPO and numerous questions persist concerning the physiological role of TSPO and its future as a therapeutic target. This article chronologically reviews the development of deletion and induction models of TSPO.
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Affiliation(s)
- Juliette Bréhat
- INSERM U955-IMRB, Team Ghaleh, UPEC, Ecole Nationale Vétérinaire d'Alfort, Créteil, France
| | - Leeyah Issop
- INSERM U955-IMRB, Team Ghaleh, UPEC, Ecole Nationale Vétérinaire d'Alfort, Créteil, France
| | - Didier Morin
- INSERM U955-IMRB, Team Ghaleh, UPEC, Ecole Nationale Vétérinaire d'Alfort, Créteil, France.
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3
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Li Y, Chen L, Papadopoulos V. The mitochondrial translocator protein (TSPO, 18 kDa): A key multifunctional molecule in liver diseases. Biochimie 2024; 224:91-103. [PMID: 38065288 DOI: 10.1016/j.biochi.2023.11.013] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2023] [Revised: 11/23/2023] [Accepted: 11/29/2023] [Indexed: 08/23/2024]
Abstract
Translocator protein (TSPO, 18 kDa), previously known as peripheral-type benzodiazepine receptor, is an evolutionarily conserved and tryptophan-rich 169-amino-acid protein located on the outer mitochondrial membrane. TSPO plays a crucial role in various fundamental physiological functions and cellular processes. Its expression is altered in pathological conditions, thus rendering TSPO a potential tool for diagnostic imaging and an appealing therapeutic target. The investigation of synthetic TSPO ligands as both agonists and antagonists has provided valuable insights into the regulatory mechanisms and functional properties of TSPO. Recently, accumulating evidence has highlighted the significance of TSPO in liver diseases. However, a comprehensive summary of TSPO function in the normal liver and diverse liver diseases is lacking. This review aims to provide an overview of recent advances in understanding TSPO function in both normal liver cells and various liver diseases, with a particular emphasis on its involvement in liver fibrosis and inflammation and addresses the existing knowledge gaps in the field that require further investigation.
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Affiliation(s)
- Yuchang Li
- Department of Pharmacology and Pharmaceutical Sciences, Alfred E. Mann School of Pharmacy and Pharmaceutical Sciences, University of Southern California, Los Angeles, CA 90089, USA.
| | - Liting Chen
- Department of Pharmacology and Pharmaceutical Sciences, Alfred E. Mann School of Pharmacy and Pharmaceutical Sciences, University of Southern California, Los Angeles, CA 90089, USA
| | - Vassilios Papadopoulos
- Department of Pharmacology and Pharmaceutical Sciences, Alfred E. Mann School of Pharmacy and Pharmaceutical Sciences, University of Southern California, Los Angeles, CA 90089, USA.
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4
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Hector M, Langmann T, Wolf A. Translocator protein (18 kDa) (Tspo) in the retina and implications for ocular diseases. Prog Retin Eye Res 2024; 100:101249. [PMID: 38430990 DOI: 10.1016/j.preteyeres.2024.101249] [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: 12/05/2023] [Revised: 02/28/2024] [Accepted: 02/29/2024] [Indexed: 03/05/2024]
Abstract
Translocator protein (18 kDa) (Tspo), formerly known as peripheral benzodiazepine receptor is a highly conserved transmembrane protein primarily located in the outer mitochondrial membrane. In the central nervous system (CNS), especially in glia cells, Tspo is upregulated upon inflammation. Consequently, Tspo was used as a tool for diagnostic in vivo imaging of neuroinflammation in the brain and as a potential therapeutic target. Several synthetic Tspo ligands have been explored as immunomodulatory and neuroprotective therapy approaches. Although the function of Tspo and how its ligands exert these beneficial effects is not fully clear, it became a research topic of interest, especially in ocular diseases in the past few years. This review summarizes state-of-the-art knowledge of Tspo expression and its proposed functions in different cells of the retina including microglia, retinal pigment epithelium and Müller cells. Tspo is involved in cytokine signaling, oxidative stress and reactive oxygen species production, calcium signaling, neurosteroid synthesis, energy metabolism, and cholesterol efflux. We also highlight recent developments in preclinical models targeting Tspo and summarize the relevance of Tspo biology for ocular and retinal diseases. We conclude that glial upregulation of Tspo in different ocular pathologies and the use of Tspo ligands as promising therapeutic approaches in preclinical studies underline the importance of Tspo as a potential disease-modifying protein.
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Affiliation(s)
- Mandy Hector
- Laboratory for Experimental Immunology of the Eye, Department of Ophthalmology, University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany.
| | - Thomas Langmann
- Laboratory for Experimental Immunology of the Eye, Department of Ophthalmology, University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany; Centre for Molecular Medicine Cologne (CMMC), University of Cologne, Cologne, Germany.
| | - Anne Wolf
- Laboratory for Experimental Immunology of the Eye, Department of Ophthalmology, University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany; Centre for Molecular Medicine Cologne (CMMC), University of Cologne, Cologne, Germany.
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5
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Gore IR, Gould E. Developmental and adult stress: effects of steroids and neurosteroids. Stress 2024; 27:2317856. [PMID: 38563163 PMCID: PMC11046567 DOI: 10.1080/10253890.2024.2317856] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/03/2023] [Accepted: 02/03/2024] [Indexed: 04/04/2024] Open
Abstract
In humans, exposure to early life adversity has profound implications for susceptibility to developing neuropsychiatric disorders later in life. Studies in rodents have shown that stress experienced during early postnatal life can have lasting effects on brain development. Glucocorticoids and sex steroids are produced in endocrine glands and the brain from cholesterol; these molecules bind to nuclear and membrane-associated steroid receptors. Unlike other steroids that can also be made in the brain, neurosteroids bind specifically to neurotransmitter receptors, not steroid receptors. The relationships among steroids, neurosteroids, and stress are multifaceted and not yet fully understood. However, studies demonstrating altered levels of progestogens, androgens, estrogens, glucocorticoids, and their neuroactive metabolites in both developmental and adult stress paradigms strongly suggest that these molecules may be important players in stress effects on brain circuits and behavior. In this review, we discuss the influence of developmental and adult stress on various components of the brain, including neurons, glia, and perineuronal nets, with a focus on sex steroids and neurosteroids. Gaining an enhanced understanding of how early adversity impacts the intricate systems of brain steroid and neurosteroid regulation could prove instrumental in identifying novel therapeutic targets for stress-related conditions.
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Affiliation(s)
- Isha R Gore
- Princeton Neuroscience Institute, Princeton University, Princeton, NJ, USA
| | - Elizabeth Gould
- Princeton Neuroscience Institute, Princeton University, Princeton, NJ, USA
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6
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Vicente-Rodríguez M, Mancuso R, Peris-Yague A, Simmons C, Gómez-Nicola D, Perry VH, Turkheimer F, Lovestone S, Parker CA, Cash D. Pharmacological modulation of TSPO in microglia/macrophages and neurons in a chronic neurodegenerative model of prion disease. J Neuroinflammation 2023; 20:92. [PMID: 37032328 PMCID: PMC10084680 DOI: 10.1186/s12974-023-02769-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Accepted: 03/20/2023] [Indexed: 04/11/2023] Open
Abstract
Neuroinflammation is an important component of many neurodegenerative diseases, whether as a primary cause or a secondary outcome. For that reason, either as diagnostic tools or to monitor progression and/or pharmacological interventions, there is a need for robust biomarkers of neuroinflammation in the brain. Mitochondrial TSPO (18 kDa Translocator protein) is one of few available biomarkers of neuroinflammation for which there are clinically available PET imaging agents. In this study, we further characterised neuroinflammation in a mouse model of prion-induced chronic neurodegeneration (ME7) including a pharmacological intervention via a CSF1R inhibitor. This was achieved by autoradiographic binding of the second-generation TSPO tracer, [3H]PBR28, along with a more comprehensive examination of the cellular contributors to the TSPO signal changes by immunohistochemistry. We observed regional increases of TSPO in the ME7 mouse brains, particularly in the hippocampus, cortex and thalamus. This increased TSPO signal was detected in the cells of microglia/macrophage lineage as well as in astrocytes, endothelial cells and neurons. Importantly, we show that the selective CSF1R inhibitor, JNJ-40346527 (JNJ527), attenuated the disease-dependent increase in TSPO signal, particularly in the dentate gyrus of the hippocampus, where JNJ527 attenuated the number of Iba1+ microglia and neurons, but not GFAP+ astrocytes or endothelial cells. These findings suggest that [3H]PBR28 quantitative autoradiography in combination with immunohistochemistry are important translational tools for detecting and quantifying neuroinflammation, and its treatments, in neurodegenerative disease. Furthermore, we demonstrate that although TSPO overexpression in the ME7 brains was driven by various cell types, the therapeutic effect of the CSF1R inhibitor was primarily to modulate TSPO expression in microglia and neurons, which identifies an important route of biological action of this particular CSF1R inhibitor and provides an example of a cell-specific effect of this type of therapeutic agent on the neuroinflammatory process.
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Affiliation(s)
- Marta Vicente-Rodríguez
- Department of Neuroimaging, BRAIN Centre (Biomarker Research and Imaging for Neuroscience), Institute of Psychiatry, Psychology & Neuroscience, King's College London, London, UK.
- The Wellcome Trust Consortium for the Neuroimmunology of Mood Disorders and Alzheimer's Disease (NIMA), London, UK.
- Departamento de Ciencias Farmacéuticas y de la Salud, Facultad de Farmacia, Universidad San Pablo-CEU, CEU Universities, Madrid, Spain.
| | - Renzo Mancuso
- The Wellcome Trust Consortium for the Neuroimmunology of Mood Disorders and Alzheimer's Disease (NIMA), London, UK
- Microglia and Inflammation in Neurological Disorders (MIND) Lab, VIB Center for Molecular Neurology, VIB, Antwerp, Belgium
- Department of Biomedical Sciences, University of Antwerp, Antwerp, Belgium
- Biological Sciences, Southampton General Hospital, University of Southampton, Southampton, UK
| | - Alba Peris-Yague
- Department of Neuroimaging, BRAIN Centre (Biomarker Research and Imaging for Neuroscience), Institute of Psychiatry, Psychology & Neuroscience, King's College London, London, UK
| | - Camilla Simmons
- Department of Neuroimaging, BRAIN Centre (Biomarker Research and Imaging for Neuroscience), Institute of Psychiatry, Psychology & Neuroscience, King's College London, London, UK
- The Wellcome Trust Consortium for the Neuroimmunology of Mood Disorders and Alzheimer's Disease (NIMA), London, UK
| | - Diego Gómez-Nicola
- The Wellcome Trust Consortium for the Neuroimmunology of Mood Disorders and Alzheimer's Disease (NIMA), London, UK
- Biological Sciences, Southampton General Hospital, University of Southampton, Southampton, UK
| | - V Hugh Perry
- The Wellcome Trust Consortium for the Neuroimmunology of Mood Disorders and Alzheimer's Disease (NIMA), London, UK
- Biological Sciences, Southampton General Hospital, University of Southampton, Southampton, UK
| | - Federico Turkheimer
- Department of Neuroimaging, BRAIN Centre (Biomarker Research and Imaging for Neuroscience), Institute of Psychiatry, Psychology & Neuroscience, King's College London, London, UK
- The Wellcome Trust Consortium for the Neuroimmunology of Mood Disorders and Alzheimer's Disease (NIMA), London, UK
| | - Simon Lovestone
- The Wellcome Trust Consortium for the Neuroimmunology of Mood Disorders and Alzheimer's Disease (NIMA), London, UK
- Janssen Medical Ltd, High Wycombe, UK
| | - Christine A Parker
- Department of Neuroimaging, BRAIN Centre (Biomarker Research and Imaging for Neuroscience), Institute of Psychiatry, Psychology & Neuroscience, King's College London, London, UK
- The Wellcome Trust Consortium for the Neuroimmunology of Mood Disorders and Alzheimer's Disease (NIMA), London, UK
- GlaxoSmithKline, Stevenage, London, UK
| | - Diana Cash
- Department of Neuroimaging, BRAIN Centre (Biomarker Research and Imaging for Neuroscience), Institute of Psychiatry, Psychology & Neuroscience, King's College London, London, UK
- The Wellcome Trust Consortium for the Neuroimmunology of Mood Disorders and Alzheimer's Disease (NIMA), London, UK
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7
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Liu J, Hiser C, Li F, Hall R, Garavito RM, Ferguson-Miller S. New TSPO Crystal Structures of Mutant and Heme-Bound Forms with Altered Flexibility, Ligand Binding, and Porphyrin Degradation Activity. Biochemistry 2023; 62:1262-1273. [PMID: 36947867 PMCID: PMC10077581 DOI: 10.1021/acs.biochem.2c00612] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2022] [Revised: 03/09/2023] [Indexed: 03/24/2023]
Abstract
The ancient protein TSPO (translocator protein 18kD) is found in all kingdoms and was originally identified as a binding site of benzodiazepine drugs. Its physiological function remains unclear, although porphyrins are conserved ligands. Several crystal structures of bacterial TSPO and nuclear magnetic resonance structures of a mouse form have revealed monomer and dimer configurations, but there have been no reports of structures with a physiological ligand. Here, we present the first X-ray structures of Rhodobacter sphaeroides TSPO with a physiological ligand bound. Two different variants (substituting threonine for alanine at position 139 (A139T) and phenylalanine for alanine at position 138 (A138F)) yielded well-diffracting crystals giving structures of both apo- and heme-containing forms. Both variants have wild-type micromolar affinity for heme and protoporphyrin IX, but A139T has very low ability to accelerate the breakdown of porphyrin in the presence of light and oxygen. The binding of heme to one protomer of the dimer of either mutant induces a more rigid structure, both in the heme-binding protomer and the protomer without heme bound, demonstrating an allosteric response. Ensemble refinement of the X-ray data reveals distinct regions of altered flexibility in response to single heme binding to the dimer. The A139T variant shows a more rigid structure overall, which may relate to extra hydrogen bonding of waters captured in the heme crevice. As TSPO has been suggested to have a role in heme delivery from mitochondria to the cytoplasm, the new structures provide potential clues regarding the structural basis of such activity.
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Affiliation(s)
- Jian Liu
- Department
of Chemistry, Michigan State University, East Lansing, Michigan 48824, United States
| | - Carrie Hiser
- Department
of Biochemistry and Molecular Biology, Michigan
State University, East Lansing, Michigan 48824, United States
| | - Fei Li
- Amgen
Inc., San Francisco, California 94080, United States
| | - Robert Hall
- Pharmacology
and Chemical Biology, University of Pittsburgh
School of Medicine, Pittsburgh, Pennsylvania 15213, United States
| | - R. Michael Garavito
- Department
of Biochemistry and Molecular Biology, Michigan
State University, East Lansing, Michigan 48824, United States
| | - Shelagh Ferguson-Miller
- Department
of Biochemistry and Molecular Biology, Michigan
State University, East Lansing, Michigan 48824, United States
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8
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Rodina AV, Semochkina YP, Vysotskaya OV, Parfenova AA, Moskaleva EY. Radiation-induced neuroinflammation monitoring by the level of peripheral blood monocytes with high expression of translocator protein. Int J Radiat Biol 2023; 99:1364-1377. [PMID: 36821843 DOI: 10.1080/09553002.2023.2177765] [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: 05/17/2022] [Revised: 01/11/2023] [Accepted: 02/01/2023] [Indexed: 02/25/2023]
Abstract
PURPOSE Currently there are no effective diagnostic methods for the control of neuroinflammation before manifestation of cognitive impairment after head irradiation. The translocator protein (TSPO) is highly expressed in glial cells upon brain damage, therefore we compared the changes in the number of cells with high TSPO expression in the brain and peripheral blood during radiation-induced neuroinflammation. MATERIALS AND METHODS Hippocampal cytokines mRNA expression and the content of cells with high TSPO expression in the brain and peripheral blood monocytes were analyzed up to eight months after mice head γ-irradiation at a dose of 2 Gy or 8Gy. RESULTS Mice irradiation at a dose of 8 Gy causes neuroinflammation, accompanied by an increase of M1 microglia and TSPOhigh cells in the brain, elevated gene expression of pro-inflammatory and decreased of anti-inflammatory cytokines along with an increased number of microglia and astrocytes in the hippocampus. The content of TSPOhigh cells in the brain correlates with the level TSPOhigh monocytes in three days, one month and two months after exposure. CONCLUSIONS An increase in the level of the monocytes with high expression of TSPO may be considered as a marker for an early diagnostics of post-radiation brain damage leading to cognitive impairment.
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Affiliation(s)
- Alla V Rodina
- Department of Cell Biology, Immunology and Molecular Medicine, Kurchatov Complex of NBICS Technologies, NRC Kurchatov Institute, Moscow, Russian Federation
| | - Yulia P Semochkina
- Department of Cell Biology, Immunology and Molecular Medicine, Kurchatov Complex of NBICS Technologies, NRC Kurchatov Institute, Moscow, Russian Federation
| | - Olga V Vysotskaya
- Department of Cell Biology, Immunology and Molecular Medicine, Kurchatov Complex of NBICS Technologies, NRC Kurchatov Institute, Moscow, Russian Federation
| | - Anna A Parfenova
- Department of Cell Biology, Immunology and Molecular Medicine, Kurchatov Complex of NBICS Technologies, NRC Kurchatov Institute, Moscow, Russian Federation
| | - Elizaveta Y Moskaleva
- Department of Cell Biology, Immunology and Molecular Medicine, Kurchatov Complex of NBICS Technologies, NRC Kurchatov Institute, Moscow, Russian Federation
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9
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Tollefson S, Himes ML, Kozinski KM, Lopresti BJ, Mason NS, Hibbeln J, Muldoon MF, Narendran R. Imaging the Influence of Red Blood Cell Docosahexaenoic Acid Status on the Expression of the 18 kDa Translocator Protein in the Brain: A [ 11C]PBR28 Positron Emission Tomography Study in Young Healthy Men. BIOLOGICAL PSYCHIATRY. COGNITIVE NEUROSCIENCE AND NEUROIMAGING 2022; 7:998-1006. [PMID: 34607054 DOI: 10.1016/j.bpsc.2021.09.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Revised: 09/09/2021] [Accepted: 09/18/2021] [Indexed: 01/11/2023]
Abstract
BACKGROUND Docosahexaenoic acid (DHA) shows anti-inflammatory/proresolution effects in the brain. Higher red blood cell (RBC) DHA in humans is associated with improved cognitive performance and a lower risk for suicide. Here, we hypothesized that binding to the 18 kDa translocator protein (TSPO), a proxy for microglia levels, will be higher in individuals with low DHA relative to high DHA levels. We also postulated that higher TSPO would predict poor cognitive performance and impaired stress resilience. METHODS RBC DHA screening was performed in 320 healthy males. [11C]PBR28 positron emission tomography was used to measure binding to TSPO in 38 and 32 males in the lowest and highest RBC DHA quartiles. Volumes of distribution expressed relative to total plasma ligand concentration (VT) was derived using an arterial input function-based kinetic analysis in 14 brain regions. RESULTS [11C]PBR28 VT was significantly lower (by 12% and 20% in C/T and C/C rs6971 genotypes) in males with low RBC DHA than in males with high RBC DHA. Regional VT was correlated positively and negatively with RBC DHA and serum triglycerides, respectively. No relationships between VT and cognitive performance or stress resilience measures were present. CONCLUSIONS Contrary to our hypothesis, we found lower TSPO binding in low-DHA than in high-DHA subjects. It is unclear as to whether low TSPO binding reflects differences in microglia levels and/or triglyceride metabolism in this study. Future studies with specific targets are necessary to confirm the effect of DHA on microglia. These results underscore the need to consider lipid parameters as a factor when interpreting TSPO positron emission tomography clinical findings.
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Affiliation(s)
- Savannah Tollefson
- Department of Radiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Michael L Himes
- Department of Radiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Katelyn M Kozinski
- Department of Radiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Brian J Lopresti
- Department of Radiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - N Scott Mason
- Department of Radiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Joseph Hibbeln
- National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, Maryland
| | - Matthew F Muldoon
- Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Rajesh Narendran
- Department of Radiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania; Department of Psychiatry, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania.
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10
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Fogliano C, Motta CM, Venditti P, Fasciolo G, Napolitano G, Avallone B, Carotenuto R. Environmental concentrations of a delorazepam-based drug impact on embryonic development of non-target Xenopus laevis. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2022; 250:106244. [PMID: 35878487 DOI: 10.1016/j.aquatox.2022.106244] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2022] [Revised: 07/11/2022] [Accepted: 07/18/2022] [Indexed: 06/15/2023]
Abstract
Benzodiazepines, psychotropics drugs used for treating sleep disorders, anxiety and epilepsy, represent a major class of emerging water pollutants. As occurs for other pharmaceutical residues, they are not efficiently degraded during sewage treatment and persist in effluent waters. Bioaccumulation is already reported in fish and small crustaceans, but the impact and consequences on other "non-target" aquatic species are still unclear and nowadays of great interest. In this study, we investigated the effects of a pharmaceutical preparation containing the benzodiazepine delorazepam on the embryogenesis of Xenopus laevis, amphibian model species, taxa at high risk of exposure to water contaminants. Environmental (1 μg/L) and two higher (5 and 10 μg/L) concentrations were tested on tadpoles up to stage 45/46. Results demonstrate that delorazepam interferes with embryo development and that the effects are prevalently dose-dependent. Delorazepam reduces vitality by decreasing heart rate and motility, induces marked cephalic and abdominal edema, as well as intestinal and retinal defects. At the molecular level, delorazepam increases ROS production, modifies the expression of some master developmental genes and pro-inflammatory cytokines. The resulting stress condition significantly affects embryos' development and threatens their survival. Similar effects should be expected as well in embryos belonging to other aquatic species that have not been yet considered targets for these pharmaceutical residues.
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Affiliation(s)
- Chiara Fogliano
- Department of Biology, University of Naples Federico II, Naples, Italy
| | | | - Paola Venditti
- Department of Biology, University of Naples Federico II, Naples, Italy
| | - Gianluca Fasciolo
- Department of Biology, University of Naples Federico II, Naples, Italy
| | - Gaetana Napolitano
- Department of Science and Technology, University of Naples Parthenope, Naples, Italy
| | - Bice Avallone
- Department of Biology, University of Naples Federico II, Naples, Italy.
| | - Rosa Carotenuto
- Department of Biology, University of Naples Federico II, Naples, Italy
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11
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Wu KC, Liao KS, Yeh LR, Wang YK. Drug Repurposing: The Mechanisms and Signaling Pathways of Anti-Cancer Effects of Anesthetics. Biomedicines 2022; 10:biomedicines10071589. [PMID: 35884894 PMCID: PMC9312706 DOI: 10.3390/biomedicines10071589] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2022] [Revised: 06/20/2022] [Accepted: 07/01/2022] [Indexed: 12/14/2022] Open
Abstract
Cancer is one of the leading causes of death worldwide. There are only limited treatment strategies that can be applied to treat cancer, including surgical resection, chemotherapy, and radiotherapy, but these have only limited effectiveness. Developing a new drug for cancer therapy is protracted, costly, and inefficient. Recently, drug repurposing has become a rising research field to provide new meaning for an old drug. By searching a drug repurposing database ReDO_DB, a brief list of anesthetic/sedative drugs, such as haloperidol, ketamine, lidocaine, midazolam, propofol, and valproic acid, are shown to possess anti-cancer properties. Therefore, in the current review, we will provide a general overview of the anti-cancer mechanisms of these anesthetic/sedative drugs and explore the potential underlying signaling pathways and clinical application of these drugs applied individually or in combination with other anti-cancer agents.
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Affiliation(s)
- King-Chuen Wu
- Department of Anesthesiology, Chang Gung Memorial Hospital, Chiayi 61363, Taiwan;
- Department of Nursing, Chang Gung University of Science and Technology, Chiayi 61363, Taiwan
| | - Kai-Sheng Liao
- Department of Pathology, Ditmanson Medical Foundation, Chia-Yi Christian Hospital, Chiayi 60002, Taiwan;
| | - Li-Ren Yeh
- Department of Anesthesiology, E-Da Cancer Hospital, Kaohsiung 82445, Taiwan
- Department of Medical Imaging and Radiology, Shu-Zen College of Medicine and Management, Kaohsiung 82144, Taiwan
- Correspondence: (L.-R.Y.); (Y.-K.W.); Tel.: +886-7-6150-022 (L.-R.Y.); +886-6-2353-535 (ext. 5333) (Y.-K.W.)
| | - Yang-Kao Wang
- Department of Cell Biology and Anatomy, College of Medicine, National Cheng Kung University, Tainan 70101, Taiwan
- Correspondence: (L.-R.Y.); (Y.-K.W.); Tel.: +886-7-6150-022 (L.-R.Y.); +886-6-2353-535 (ext. 5333) (Y.-K.W.)
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12
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Nicotinic Acetylcholine Receptors and Microglia as Therapeutic and Imaging Targets in Alzheimer's Disease. MOLECULES (BASEL, SWITZERLAND) 2022; 27:molecules27092780. [PMID: 35566132 PMCID: PMC9102429 DOI: 10.3390/molecules27092780] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Revised: 04/21/2022] [Accepted: 04/25/2022] [Indexed: 12/12/2022]
Abstract
Amyloid-β (Aβ) accumulation and tauopathy are considered the pathological hallmarks of Alzheimer’s disease (AD), but attenuation in choline signaling, including decreased nicotinic acetylcholine receptors (nAChRs), is evident in the early phase of AD. Currently, there are no drugs that can suppress the progression of AD due to a limited understanding of AD pathophysiology. For this, diagnostic methods that can assess disease progression non-invasively before the onset of AD symptoms are essential, and it would be valuable to incorporate the concept of neurotheranostics, which simultaneously enables diagnosis and treatment. The neuroprotective pathways activated by nAChRs are attractive targets as these receptors may regulate microglial-mediated neuroinflammation. Microglia exhibit both pro- and anti-inflammatory functions that could be modulated to mitigate AD pathogenesis. Currently, single-cell analysis is identifying microglial subpopulations that may have specific functions in different stages of AD pathologies. Thus, the ability to image nAChRs and microglia in AD according to the stage of the disease in the living brain may lead to the development of new diagnostic and therapeutic methods. In this review, we summarize and discuss the recent findings on the nAChRs and microglia, as well as their methods for live imaging in the context of diagnosis, prophylaxis, and therapy for AD.
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13
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Neuropeptidergic control of neurosteroids biosynthesis. Front Neuroendocrinol 2022; 65:100976. [PMID: 34999057 DOI: 10.1016/j.yfrne.2021.100976] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/21/2021] [Revised: 12/12/2021] [Accepted: 12/22/2021] [Indexed: 01/14/2023]
Abstract
Neurosteroids are steroids synthesized within the central nervous system either from cholesterol or by metabolic reactions of circulating steroid hormone precursors. It has been suggested that neurosteroids exert pleiotropic activities within the central nervous system, such as organization and activation of the central nervous system and behavioral regulation. It is also increasingly becoming clear that neuropeptides exert pleiotropic activities within the central nervous system, such as modulation of neuronal functions and regulation of behavior, besides traditional neuroendocrinological functions. It was hypothesized that some of the physiological functions of neuropeptides acting within the central nervous system may be through the regulation of neurosteroids biosynthesis. Various neuropeptides reviewed in this study possibly regulate neurosteroids biosynthesis by controlling the activities of enzymes that catalyze the production of neurosteroids. It is now required to thoroughly investigate the neuropeptidergic control mechanisms of neurosteroids biosynthesis to characterize the physiological significance of this new neuroendocrinological phenomenon.
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14
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Guilarte TR, Rodichkin AN, McGlothan JL, Acanda De La Rocha AM, Azzam DJ. Imaging neuroinflammation with TSPO: A new perspective on the cellular sources and subcellular localization. Pharmacol Ther 2021; 234:108048. [PMID: 34848203 DOI: 10.1016/j.pharmthera.2021.108048] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Revised: 11/04/2021] [Accepted: 11/24/2021] [Indexed: 12/14/2022]
Abstract
Translocator Protein 18 kDa (TSPO), previously named Peripheral Benzodiazepine Receptor, is a well-validated and widely used biomarker of neuroinflammation to assess diverse central nervous system (CNS) pathologies in preclinical and clinical studies. Many studies have shown that in animal models of human neurological and neurodegenerative disease and in the human condition, TSPO levels increase in the brain neuropil, and this increase is driven by infiltration of peripheral inflammatory cells and activation of glial cells. Therefore, a clear understanding of the dynamics of the cellular sources of the TSPO response is critically important in the interpretation of Positron Emission Tomography (PET) studies and for understanding the pathophysiology of CNS diseases. Within the normal brain compartment, there are tissues and cells such as the choroid plexus, ependymal cells of the lining of the ventricles, and vascular endothelial cells that also express TSPO at even higher levels than in glial cells. However, there is a paucity of knowledge if these cell types respond and increase TSPO in the diseased brain. These cells do provide a background signal that needs to be accounted for in TSPO-PET imaging studies. More recently, there are reports that TSPO may be expressed in neurons of the adult brain and TSPO expression may be increased by neuronal activity. Therefore, it is essential to study this topic with a great deal of detail, methodological rigor, and rule out alternative interpretations and imaging artifacts. High levels of TSPO are present in the outer mitochondrial membrane. Recent studies have provided evidence of its localization in other cellular compartments including the plasma membrane and perinuclear regions which may define functions that are different from that in mitochondria. A greater understanding of the TSPO subcellular localization in glial cells and infiltrating peripheral immune cells and associated function(s) may provide an additional layer of information to the understanding of TSPO neurobiology. This review is an effort to outline recent advances in understanding the cellular sources and subcellular localization of TSPO in brain cells and to examine remaining questions that require rigorous investigation.
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Affiliation(s)
- Tomás R Guilarte
- Brain, Behavior, & the Environment Program, Department of Environmental Health Sciences, Robert Stempel College of Public Health & Social Work, Florida International University, Miami, FL 33199, United States of America.
| | - Alexander N Rodichkin
- Brain, Behavior, & the Environment Program, Department of Environmental Health Sciences, Robert Stempel College of Public Health & Social Work, Florida International University, Miami, FL 33199, United States of America
| | - Jennifer L McGlothan
- Brain, Behavior, & the Environment Program, Department of Environmental Health Sciences, Robert Stempel College of Public Health & Social Work, Florida International University, Miami, FL 33199, United States of America
| | - Arlet Maria Acanda De La Rocha
- Brain, Behavior, & the Environment Program, Department of Environmental Health Sciences, Robert Stempel College of Public Health & Social Work, Florida International University, Miami, FL 33199, United States of America
| | - Diana J Azzam
- Brain, Behavior, & the Environment Program, Department of Environmental Health Sciences, Robert Stempel College of Public Health & Social Work, Florida International University, Miami, FL 33199, United States of America
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15
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Zhang H, Wang H, Gao F, Yang J, Xu Y, Fu Y, Cai M, Zhang X, Yang Q, Tong K, Hu Y, Chen H, Ma C, He W, Zhang J. TSPO deficiency accelerates amyloid pathology and neuroinflammation by impairing microglial phagocytosis. Neurobiol Aging 2021; 106:292-303. [PMID: 34340010 DOI: 10.1016/j.neurobiolaging.2021.06.020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2019] [Revised: 06/08/2021] [Accepted: 06/25/2021] [Indexed: 12/25/2022]
Abstract
Increasing evidence has placed inflammation and immune dysfunction at the center of the pathogenesis of Alzheimer's disease (AD). The mitochondrial protein translocator protein (18 kDa) (TSPO) is highly upregulated in microglia and astrocytes in response to inflammatory stimulation. However, the biological action of TSPO in the pathogenesis of AD has not been determined to date. In this study, we showed that TSPO expression was upregulated in brain tissues from AD patients and AD model mice. APP/PS1 mice lacking TSPO generated significantly higher levels of Aβ1-40 and Aβ1-42 peptides and more Aβ plaques, as well as enhanced microglial activation, in the brain. TSPO-deficient microglia cultured in vitro showed a significant decrease in the ability to phagocytose Aβ peptides or latex beads and generated more proinflammatory cytokines (TNF-α and IL-1β) in response to Aβ peptides. Our findings suggest that TSPO has protective functions against neuroinflammation and Aβ pathogenesis in AD. TSPO may be a potential drug target for the development of drugs that have therapeutic or preventive effects in neuroinflammatory diseases.
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Affiliation(s)
- Han Zhang
- Department of Immunology, CAMS Key Laboratory for T Cell and Immunotherapy, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and School of Basic Medicine, Peking Union Medical College, State Key Laboratory of Medical Molecular Biology, Beijing, China
| | - Huaishan Wang
- Department of Immunology, CAMS Key Laboratory for T Cell and Immunotherapy, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and School of Basic Medicine, Peking Union Medical College, State Key Laboratory of Medical Molecular Biology, Beijing, China
| | - Fei Gao
- Department of Immunology, CAMS Key Laboratory for T Cell and Immunotherapy, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and School of Basic Medicine, Peking Union Medical College, State Key Laboratory of Medical Molecular Biology, Beijing, China
| | - Jia Yang
- Department of Immunology, CAMS Key Laboratory for T Cell and Immunotherapy, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and School of Basic Medicine, Peking Union Medical College, State Key Laboratory of Medical Molecular Biology, Beijing, China
| | - Yi Xu
- Department of Immunology, CAMS Key Laboratory for T Cell and Immunotherapy, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and School of Basic Medicine, Peking Union Medical College, State Key Laboratory of Medical Molecular Biology, Beijing, China
| | - Yi Fu
- Department of Immunology, CAMS Key Laboratory for T Cell and Immunotherapy, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and School of Basic Medicine, Peking Union Medical College, State Key Laboratory of Medical Molecular Biology, Beijing, China
| | - Menghua Cai
- Department of Immunology, CAMS Key Laboratory for T Cell and Immunotherapy, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and School of Basic Medicine, Peking Union Medical College, State Key Laboratory of Medical Molecular Biology, Beijing, China
| | - Xue Zhang
- Department of Immunology, CAMS Key Laboratory for T Cell and Immunotherapy, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and School of Basic Medicine, Peking Union Medical College, State Key Laboratory of Medical Molecular Biology, Beijing, China
| | - Qi Yang
- Department of Immunology, CAMS Key Laboratory for T Cell and Immunotherapy, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and School of Basic Medicine, Peking Union Medical College, State Key Laboratory of Medical Molecular Biology, Beijing, China
| | - Kexin Tong
- Department of Immunology, CAMS Key Laboratory for T Cell and Immunotherapy, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and School of Basic Medicine, Peking Union Medical College, State Key Laboratory of Medical Molecular Biology, Beijing, China
| | - Yu Hu
- Department of Immunology, CAMS Key Laboratory for T Cell and Immunotherapy, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and School of Basic Medicine, Peking Union Medical College, State Key Laboratory of Medical Molecular Biology, Beijing, China
| | - Hui Chen
- Department of Immunology, CAMS Key Laboratory for T Cell and Immunotherapy, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and School of Basic Medicine, Peking Union Medical College, State Key Laboratory of Medical Molecular Biology, Beijing, China
| | - Chao Ma
- Department of Human Anatomy, Histology and Embryology, Institute of Basic Medical Sciences, Neuroscience Center, Chinese Academy of Medical Sciences, School of Basic Medicine, Peking Union Medical College, Beijing, China
| | - Wei He
- Department of Immunology, CAMS Key Laboratory for T Cell and Immunotherapy, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and School of Basic Medicine, Peking Union Medical College, State Key Laboratory of Medical Molecular Biology, Beijing, China.
| | - Jianmin Zhang
- Department of Immunology, CAMS Key Laboratory for T Cell and Immunotherapy, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and School of Basic Medicine, Peking Union Medical College, State Key Laboratory of Medical Molecular Biology, Beijing, China.
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16
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Hiser C, Montgomery BL, Ferguson-Miller S. TSPO protein binding partners in bacteria, animals, and plants. J Bioenerg Biomembr 2021; 53:463-487. [PMID: 34191248 PMCID: PMC8243069 DOI: 10.1007/s10863-021-09905-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Accepted: 06/12/2021] [Indexed: 12/11/2022]
Abstract
The ancient membrane protein TSPO is phylogenetically widespread from archaea and bacteria to insects, vertebrates, plants, and fungi. TSPO’s primary amino acid sequence is only modestly conserved between diverse species, although its five transmembrane helical structure appears mainly conserved. Its cellular location and orientation in membranes have been reported to vary between species and tissues, with implications for potential diverse binding partners and function. Most TSPO functions relate to stress-induced changes in metabolism, but in many cases it is unclear how TSPO itself functions—whether as a receptor, a sensor, a transporter, or a translocator. Much evidence suggests that TSPO acts indirectly by association with various protein binding partners or with endogenous or exogenous ligands. In this review, we focus on proteins that have most commonly been invoked as TSPO binding partners. We suggest that TSPO was originally a bacterial receptor/stress sensor associated with porphyrin binding as its most ancestral function and that it later developed additional stress-related roles in eukaryotes as its ability to bind new partners evolved.
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Affiliation(s)
- Carrie Hiser
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, 48824, USA. .,Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, MI, 48824, USA.
| | - Beronda L Montgomery
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, 48824, USA.,Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, MI, 48824, USA.,Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI, 48824, USA
| | - Shelagh Ferguson-Miller
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, 48824, USA
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17
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Jung ME. A Protective Role of Translocator Protein in Alzheimer's Disease Brain. Curr Alzheimer Res 2021; 17:3-15. [PMID: 32065102 DOI: 10.2174/1567205017666200217105950] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2019] [Revised: 01/13/2020] [Accepted: 01/20/2020] [Indexed: 12/16/2022]
Abstract
Translocator Protein (18 kDa) (TSPO) is a mitochondrial protein that locates cytosol cholesterol to mitochondrial membranes to begin the synthesis of steroids including neurotrophic neurosteroids. TSPO is abundantly present in glial cells that support neurons and respond to neuroinflammation. Located at the outer membrane of mitochondria, TSPO regulates the opening of mitochondrial permeability transition pore (mPTP) that controls the entry of molecules necessary for mitochondrial function. TSPO is linked to neurodegenerative Alzheimer's Disease (AD) such that TSPO is upregulated in the brain of AD patients and signals AD-induced adverse changes in brain. The initial increase in TSPO in response to brain insults remains elevated to repair cellular damages and perhaps to prevent further neuronal degeneration as AD progresses. To exert such protective activities, TSPO increases the synthesis of neuroprotective steroids, decreases neuroinflammation, limits the opening of mPTP, and reduces the generation of reactive oxygen species. The beneficial effects of TSPO on AD brain are manifested as the attenuation of neurotoxic amyloid β and mitochondrial dysfunction accompanied by the improvement of memory and cognition. However, the protective activities of TSPO appear to be temporary and eventually diminish as the severity of AD becomes profound. Timely treatment with TSPO agonists/ligands before the loss of endogenous TSPO's activity may promote the protective functions and may extend neuronal survival.
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Affiliation(s)
- Marianna E Jung
- Pharmacology and Neuroscience, University of North Texas Health Science Center, Institute for Healthy Aging, 3500 Camp Bowie Boulevard, Fort Worth, TX 76107, United States
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18
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Seidlmayer LK, Hanson BJ, Thai PN, Schaefer S, Bers DM, Dedkova EN. PK11195 Protects From Cell Death Only When Applied During Reperfusion: Succinate-Mediated Mechanism of Action. Front Physiol 2021; 12:628508. [PMID: 34149440 PMCID: PMC8212865 DOI: 10.3389/fphys.2021.628508] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Accepted: 04/28/2021] [Indexed: 11/13/2022] Open
Abstract
Aim: Reperfusion after myocardial ischemia causes cellular injury, in part due to changes in mitochondrial Ca2+ handling, oxidative stress, and myocyte energetics. We have previously shown that the 18-kDa translocator protein of the outer mitochondrial membrane (TSPO) can modulate Ca2+ handling. Here, we aim to evaluate the role of the TSPO in ischemia/reperfusion (I/R) injury. Methods: Rabbit ventricular myocytes underwent simulated acute ischemia (20 min) and reperfusion (at 15 min, 1 h, and 3 h) in the absence and presence of 50 μM PK11195, a TSPO inhibitor. Cell death was measured by lactate dehydrogenase (LDH) assay, while changes in mitochondrial Ca2+, membrane potential (ΔΨm), and reactive oxygen species (ROS) generation were monitored using confocal microscopy in combination with fluorescent indicators. Substrate utilization was measured with Biolog mitochondrial plates. Results: Cell death was increased by ~200% following I/R compared to control untreated ventricular myocytes. Incubation with 50 μM PK11195 during both ischemia and reperfusion did not reduce cell death but increased mitochondrial Ca2+ uptake and ROS generation. However, application of 50 μM PK11195 only at the onset and during reperfusion effectively protected against cell death. The large-scale oscillations in ΔΨm observed after ~1 h of reperfusion were significantly delayed by 1 μM cyclosporin A and almost completely prevented by 50 μM PK11195 applied during 3 h of reperfusion. After an initial increase, mitochondrial Ca2+, measured with Myticam, rapidly declined during 3 h of reperfusion after the initial transient increase. This decline was prevented by application of PK11195 at the onset and during reperfusion. PK11195 prevented a significant increase in succinate utilization following I/R and succinate-induced forward-mode ROS generation. Treatment with PK11195 was also associated with a significant increase in glutamate and a decrease in leucine utilization. Conclusion: PK11195 administered specifically at the moment of reperfusion limited ROS-induced ROS release and cell death, likely in part, by a shift from succinate to glutamate utilization. These data demonstrate a unique mechanism to limit cardiac injury after I/R.
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Affiliation(s)
- Lea K Seidlmayer
- Department of Cardiology, University Hospital Olbenburg, Olbenburg, Germany
| | - Benjamin J Hanson
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, Davis, CA, United States
| | - Phung N Thai
- Department of Internal Medicine, Division of Cardiovascular Medicine, School of Medicine, University of California, Davis, Davis, CA, United States
| | - Saul Schaefer
- Department of Internal Medicine, Division of Cardiovascular Medicine, School of Medicine, University of California, Davis, Davis, CA, United States
| | - Donald M Bers
- Department of Pharmacology, School of Medicine, University of California, Davis, Davis, CA, United States
| | - Elena N Dedkova
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, Davis, CA, United States
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19
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Mokrov GV, Deeva OA, Gudasheva TA. The Ligands of Translocator Protein: Design and Biological Properties. Curr Pharm Des 2021; 27:217-237. [PMID: 32881658 DOI: 10.2174/1381612826666200903122025] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Accepted: 07/15/2020] [Indexed: 11/22/2022]
Abstract
In 2020, it is already 43 years since Braestrup and Squires discovered 18 kDa translocator protein (TSPO), known until 2006 as "peripheral benzodiazepine receptor". During this time, the functions of this receptor, which is located on the outer membrane of mitochondria, were studied in detail. One of the key functions of TSPO is the transfer of cholesterol from the outer to the inner mitochondrial membrane, which is the limiting stage in the synthesis of neurosteroids. TSPO is also involved in the transport of porphyrins, mitochondrial respiration, the opening of mitochondrial pores, apoptosis and cell proliferation. This review presents current information on the structure of TSPO, the mechanism of its participation in neurosteroidogenesis, as well as endogenous and synthetic TSPO ligands. Particular emphasis is placed on the analysis of approaches to the design of synthetic ligands and their neuropsychotropic activity in vitro and in vivo. The presented review demonstrates the promise of constructing new neuropsychotropic drugs in the series of TSPO ligands.
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Affiliation(s)
- Grigory V Mokrov
- Zakusov Research Institute of Pharmacology, 125315, Moscow, Russian Federation
| | - Olga A Deeva
- Zakusov Research Institute of Pharmacology, 125315, Moscow, Russian Federation
| | - Tatiana A Gudasheva
- Zakusov Research Institute of Pharmacology, 125315, Moscow, Russian Federation
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20
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Marlow B, Kuenze G, Li B, Sanders CR, Meiler J. Structural determinants of cholesterol recognition in helical integral membrane proteins. Biophys J 2021; 120:1592-1604. [PMID: 33640379 DOI: 10.1016/j.bpj.2021.02.028] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Revised: 01/12/2021] [Accepted: 02/08/2021] [Indexed: 12/20/2022] Open
Abstract
Cholesterol is an integral component of mammalian membranes. It has been shown to modulate membrane fluidity and dynamics and alter integral membrane protein function. However, understanding the molecular mechanisms of how cholesterol impacts protein function is complicated by limited and conflicting structural data. Because of the nature of the crystallization and cryo-EM structure determination, it is difficult to distinguish between specific and biologically relevant interactions and a nonspecific association. The only widely recognized search algorithm for cholesterol-integral-membrane-protein interaction sites is sequence based, i.e., searching for the so-called "Cholesterol Recognition/interaction Amino acid Consensus" motif. Although these motifs are present in numerous integral membrane proteins, there is inconclusive evidence to support their necessity or sufficiency for cholesterol binding. Here, we leverage the increasing number of experimental cholesterol-integral-membrane-protein structures to systematically analyze putative interaction sites based on their spatial arrangement and evolutionary conservation. This analysis creates three-dimensional representations of general cholesterol interaction sites that form clusters across multiple integral membrane protein classes. We also classify cholesterol-integral-membrane-protein interaction sites as either likely-specific or nonspecific. Information gleaned from our characterization will eventually enable a structure-based approach to predict and design cholesterol-integral-membrane-protein interaction sites.
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Affiliation(s)
- Brennica Marlow
- Center for Structural Biology, Vanderbilt University, Nashville, Tennessee; Chemical and Physical Biology Program, Vanderbilt University, Nashville, Tennessee
| | - Georg Kuenze
- Center for Structural Biology, Vanderbilt University, Nashville, Tennessee; Department of Chemistry, Vanderbilt University, Nashville, Tennessee; Institute for Drug Discovery, Leipzig University Medical School, Leipzig, Germany
| | - Bian Li
- Center for Structural Biology, Vanderbilt University, Nashville, Tennessee; Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee
| | - Charles R Sanders
- Center for Structural Biology, Vanderbilt University, Nashville, Tennessee; Department of Biochemistry, Vanderbilt University, Nashville, Tennessee
| | - Jens Meiler
- Center for Structural Biology, Vanderbilt University, Nashville, Tennessee; Chemical and Physical Biology Program, Vanderbilt University, Nashville, Tennessee; Department of Chemistry, Vanderbilt University, Nashville, Tennessee; Institute for Drug Discovery, Leipzig University Medical School, Leipzig, Germany.
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21
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Biosynthesis and signalling functions of central and peripheral nervous system neurosteroids in health and disease. Essays Biochem 2021; 64:591-606. [PMID: 32756865 PMCID: PMC7517341 DOI: 10.1042/ebc20200043] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 07/09/2020] [Accepted: 07/14/2020] [Indexed: 02/07/2023]
Abstract
Neurosteroids are steroid hormones synthesised de novo in the brain and peripheral nervous tissues. In contrast to adrenal steroid hormones that act on intracellular nuclear receptors, neurosteroids directly modulate plasma membrane ion channels and regulate intracellular signalling. This review provides an overview of the work that led to the discovery of neurosteroids, our current understanding of their intracellular biosynthetic machinery, and their roles in regulating the development and function of nervous tissue. Neurosteroids mediate signalling in the brain via multiple mechanisms. Here, we describe in detail their effects on GABA (inhibitory) and NMDA (excitatory) receptors, two signalling pathways of opposing function. Furthermore, emerging evidence points to altered neurosteroid function and signalling in neurological disease. This review focuses on neurodegenerative diseases associated with altered neurosteroid metabolism, mainly Niemann-Pick type C, multiple sclerosis and Alzheimer disease. Finally, we summarise the use of natural and synthetic neurosteroids as current and emerging therapeutics alongside their potential use as disease biomarkers.
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22
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Koganti PP, Selvaraj V. Lack of adrenal TSPO/PBR expression in hamsters reinforces correlation to triglyceride metabolism. J Endocrinol 2020; 247:1-10. [PMID: 32698131 PMCID: PMC8011561 DOI: 10.1530/joe-20-0189] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Accepted: 07/13/2020] [Indexed: 11/08/2022]
Abstract
Despite being a highly conserved protein, the precise role of the mitochondrial translocator protein (TSPO), previously known as the peripheral benzodiazepine receptor (PBR), remains elusive. The void created by studies that overturned a presumptive model that described TSPO/PBR as a mitochondrial cholesterol transporter for steroidogenesis has been filled with evidence that it can affect mitochondrial metabolic functions across different model systems. We previously reported that TSPO/PBR deficient steroidogenic cells upregulate mitochondrial fatty acid oxidation and presented a strong positive correlation between TSPO/PBR expression and tissues active in triglyceride metabolism or lipid storage. Nevertheless, the highlighting of inconsistencies in prior work has provoked reprisals that threaten to stifle progress. One frequent factoid presented as being supportive of a cholesterol import function is that there are no steroid-synthesizing cell types without high TSPO/PBR expression. In this study, we examine the hamster adrenal gland that is devoid of lipid droplets in the cortex and largely relies on de novo cholesterol biosynthesis and uptake for steroidogenesis. We find that Tspo expression in the hamster adrenal is imperceptible compared to the mouse. This observation is consistent with a substantially low expression of Cpt1a in the hamster adrenal, indicating minimal mitochondrial fatty acid oxidation capacity compared to the mouse. These findings provide further reinforcement that the much sought-after mechanism of TSPO/PBR function remains correlated with the extent of cellular triglyceride metabolism. Thus, TSPO/PBR could have a homeostatic function relevant only to steroidogenic systems that manage triglycerides associated with lipid droplets.
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Affiliation(s)
- Prasanthi P. Koganti
- Department of Animal Science, College of Agriculture and Life Sciences, Cornell University, Ithaca, NY 14853
| | - Vimal Selvaraj
- Department of Animal Science, College of Agriculture and Life Sciences, Cornell University, Ithaca, NY 14853
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23
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Gliozzi M, Musolino V, Bosco F, Scicchitano M, Scarano F, Nucera S, Zito MC, Ruga S, Carresi C, Macrì R, Guarnieri L, Maiuolo J, Tavernese A, Coppoletta AR, Nicita C, Mollace R, Palma E, Muscoli C, Belzung C, Mollace V. Cholesterol homeostasis: Researching a dialogue between the brain and peripheral tissues. Pharmacol Res 2020; 163:105215. [PMID: 33007421 DOI: 10.1016/j.phrs.2020.105215] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Revised: 09/23/2020] [Accepted: 09/24/2020] [Indexed: 02/07/2023]
Abstract
Cholesterol homeostasis is a highly regulated process in human body because of its several functions underlying the biology of cell membranes, the synthesis of all steroid hormones and bile acids and the need of trafficking lipids destined to cell metabolism. In particular, it has been recognized that peripheral and central nervous system cholesterol metabolism are separated by the blood brain barrier and are regulated independently; indeed, peripherally, it depends on the balance between dietary intake and hepatic synthesis on one hand and its degradation on the other, whereas in central nervous system it is synthetized de novo to ensure brain physiology. In view of this complex metabolism and its relevant functions in mammalian, impaired levels of cholesterol can induce severe cellular dysfunction leading to metabolic, cardiovascular and neurodegenerative diseases. The aim of this review is to clarify the role of cholesterol homeostasis in health and disease highlighting new intriguing aspects of the cross talk between its central and peripheral metabolism.
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Affiliation(s)
- Micaela Gliozzi
- Institute of Research for Food Safety & Health (IRC-FSH) - Department of Health Sciences, University "Magna Graecia" of Catanzaro, Catanzaro, Italy.
| | - Vincenzo Musolino
- Institute of Research for Food Safety & Health (IRC-FSH) - Department of Health Sciences, University "Magna Graecia" of Catanzaro, Catanzaro, Italy.
| | - Francesca Bosco
- Institute of Research for Food Safety & Health (IRC-FSH) - Department of Health Sciences, University "Magna Graecia" of Catanzaro, Catanzaro, Italy.
| | - Miriam Scicchitano
- Institute of Research for Food Safety & Health (IRC-FSH) - Department of Health Sciences, University "Magna Graecia" of Catanzaro, Catanzaro, Italy.
| | - Federica Scarano
- Institute of Research for Food Safety & Health (IRC-FSH) - Department of Health Sciences, University "Magna Graecia" of Catanzaro, Catanzaro, Italy.
| | - Saverio Nucera
- Institute of Research for Food Safety & Health (IRC-FSH) - Department of Health Sciences, University "Magna Graecia" of Catanzaro, Catanzaro, Italy.
| | - Maria Caterina Zito
- Institute of Research for Food Safety & Health (IRC-FSH) - Department of Health Sciences, University "Magna Graecia" of Catanzaro, Catanzaro, Italy.
| | - Stefano Ruga
- Institute of Research for Food Safety & Health (IRC-FSH) - Department of Health Sciences, University "Magna Graecia" of Catanzaro, Catanzaro, Italy.
| | - Cristina Carresi
- Institute of Research for Food Safety & Health (IRC-FSH) - Department of Health Sciences, University "Magna Graecia" of Catanzaro, Catanzaro, Italy.
| | - Roberta Macrì
- Institute of Research for Food Safety & Health (IRC-FSH) - Department of Health Sciences, University "Magna Graecia" of Catanzaro, Catanzaro, Italy.
| | - Lorenza Guarnieri
- Institute of Research for Food Safety & Health (IRC-FSH) - Department of Health Sciences, University "Magna Graecia" of Catanzaro, Catanzaro, Italy.
| | - Jessica Maiuolo
- Institute of Research for Food Safety & Health (IRC-FSH) - Department of Health Sciences, University "Magna Graecia" of Catanzaro, Catanzaro, Italy.
| | - Annamaria Tavernese
- Division of Cardiology, University Hospital Policlinico Tor Vergata, Rome, Italy.
| | - Anna Rita Coppoletta
- Institute of Research for Food Safety & Health (IRC-FSH) - Department of Health Sciences, University "Magna Graecia" of Catanzaro, Catanzaro, Italy.
| | - Caterina Nicita
- Institute of Research for Food Safety & Health (IRC-FSH) - Department of Health Sciences, University "Magna Graecia" of Catanzaro, Catanzaro, Italy.
| | - Rocco Mollace
- Institute of Research for Food Safety & Health (IRC-FSH) - Department of Health Sciences, University "Magna Graecia" of Catanzaro, Catanzaro, Italy.
| | - Ernesto Palma
- Institute of Research for Food Safety & Health (IRC-FSH) - Department of Health Sciences, University "Magna Graecia" of Catanzaro, Catanzaro, Italy.
| | - Carolina Muscoli
- Institute of Research for Food Safety & Health (IRC-FSH) - Department of Health Sciences, University "Magna Graecia" of Catanzaro, Catanzaro, Italy; IRCCS San Raffaele Pisana, Via di Valcannuta, Rome, Italy.
| | | | - Vincenzo Mollace
- Institute of Research for Food Safety & Health (IRC-FSH) - Department of Health Sciences, University "Magna Graecia" of Catanzaro, Catanzaro, Italy; IRCCS San Raffaele Pisana, Via di Valcannuta, Rome, Italy.
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Loth MK, Guariglia SR, Re DB, Perez J, de Paiva VN, Dziedzic JL, Chambers JW, Azzam DJ, Guilarte TR. A Novel Interaction of Translocator Protein 18 kDa (TSPO) with NADPH Oxidase in Microglia. Mol Neurobiol 2020; 57:4467-4487. [PMID: 32743737 PMCID: PMC7515859 DOI: 10.1007/s12035-020-02042-w] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Accepted: 07/24/2020] [Indexed: 12/12/2022]
Abstract
In the brain neuropil, translocator protein 18 kDa (TSPO) is a stress response protein that is upregulated in microglia and astrocytes in diverse central nervous system pathologies. TSPO is widely used as a biomarker of neuroinflammation in preclinical and clinical neuroimaging studies. However, there is a paucity of knowledge on the function(s) of TSPO in glial cells. In this study, we explored a putative interaction between TSPO and NADPH oxidase 2 (NOX2) in microglia. We found that TSPO associates with gp91phox and p22phox, the principal subunits of NOX2 in primary murine microglia. The association of TSPO with gp91phox and p22phox was observed using co-immunoprecipitation, confocal immunofluorescence imaging, and proximity ligation assay. We found that besides gp91phox and p22phox, voltage-dependent anion channel (VDAC) also co-immunoprecipitated with TSPO consistent with previous reports. When we compared lipopolysaccharide (LPS) stimulated microglia to vehicle control, we found that a lower amount of gp91phox and p22phox protein co-immunoprecipitated with TSPO suggesting a disruption of the TSPO-NOX2 subunits association. TSPO immuno-gold electron microscopy confirmed that TSPO is present in the outer mitochondrial membrane but it is also found in the endoplasmic reticulum (ER), mitochondria-associated ER membrane (MAM), and in the plasma membrane. TSPO localization at the MAM may represent a subcellular site where TSPO interacts with gp91phox and p22phox since the MAM is a point of communication between outer mitochondria membrane proteins (TSPO) and ER proteins (gp91phox and p22phox) where they mature and form the cytochrome b558 (Cytb558) heterodimer. We also found that an acute burst of reactive oxygen species (ROS) increased TSPO levels on the surface of microglia and this effect was abrogated by a ROS scavenger. These results suggest that ROS production may alter the subcellular distribution of TSPO. Collectively, our findings suggest that in microglia, TSPO is associated with the major NOX2 subunits gp91phox and p22phox. We hypothesize that this interaction may regulate Cytb558 formation and modulate NOX2 levels, ROS production, and redox homeostasis in microglia.
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Affiliation(s)
- Meredith K Loth
- Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, NY, USA
| | - Sara R Guariglia
- Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, NY, USA
| | - Diane B Re
- Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, NY, USA
| | - Juan Perez
- Department of Environmental Health Sciences, Robert Stempel College of Public Health & Social Work, Florida International University, Miami, FL, 33199, USA
| | - Vanessa Nunes de Paiva
- Department of Environmental Health Sciences, Robert Stempel College of Public Health & Social Work, Florida International University, Miami, FL, 33199, USA
| | - Jennifer L Dziedzic
- Department of Environmental Health Sciences, Robert Stempel College of Public Health & Social Work, Florida International University, Miami, FL, 33199, USA
| | - Jeremy W Chambers
- Department of Environmental Health Sciences, Robert Stempel College of Public Health & Social Work, Florida International University, Miami, FL, 33199, USA
| | - Diana J Azzam
- Department of Environmental Health Sciences, Robert Stempel College of Public Health & Social Work, Florida International University, Miami, FL, 33199, USA
| | - Tomás R Guilarte
- Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, NY, USA.
- Department of Environmental Health Sciences, Robert Stempel College of Public Health & Social Work, Florida International University, Miami, FL, 33199, USA.
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25
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Rao R, Diharce J, Dugué B, Ostuni MA, Cadet F, Etchebest C. Versatile Dimerisation Process of Translocator Protein (TSPO) Revealed by an Extensive Sampling Based on a Coarse-Grained Dynamics Study. J Chem Inf Model 2020; 60:3944-3957. [DOI: 10.1021/acs.jcim.0c00246] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Rajas Rao
- Université de Paris, Biologie Intégrée du Globule Rouge, UMR_S1134, BIGR, INSERM, F-75015, Paris, France
- Laboratoire d’Excellence GR-Ex, 75015 Paris, France
- Université de la Réunion, Biologie Intégrée du Globule Rouge, UMR_S1134, BIGR, Faculté des Sciences & Technologies Saint-Denis, F-97715 St. Denis, France
| | - Julien Diharce
- Université de Paris, Biologie Intégrée du Globule Rouge, UMR_S1134, BIGR, INSERM, F-75015, Paris, France
- Laboratoire d’Excellence GR-Ex, 75015 Paris, France
- Université de la Réunion, Biologie Intégrée du Globule Rouge, UMR_S1134, BIGR, Faculté des Sciences & Technologies Saint-Denis, F-97715 St. Denis, France
| | - Bérénice Dugué
- Université de Paris, Biologie Intégrée du Globule Rouge, UMR_S1134, BIGR, INSERM, F-75015, Paris, France
- Laboratoire d’Excellence GR-Ex, 75015 Paris, France
- Université de la Réunion, Biologie Intégrée du Globule Rouge, UMR_S1134, BIGR, Faculté des Sciences & Technologies Saint-Denis, F-97715 St. Denis, France
| | - Mariano A. Ostuni
- Université de Paris, Biologie Intégrée du Globule Rouge, UMR_S1134, BIGR, INSERM, F-75015, Paris, France
- Laboratoire d’Excellence GR-Ex, 75015 Paris, France
| | - Frédéric Cadet
- Université de Paris, Biologie Intégrée du Globule Rouge, UMR_S1134, BIGR, INSERM, F-75015, Paris, France
- Laboratoire d’Excellence GR-Ex, 75015 Paris, France
- Université de la Réunion, Biologie Intégrée du Globule Rouge, UMR_S1134, BIGR, Faculté des Sciences & Technologies Saint-Denis, F-97715 St. Denis, France
- PEACCEL, Artificial Intelligence Department, 6 Square Albin Cachot, Box 42, 75013 Paris, France
| | - Catherine Etchebest
- Université de Paris, Biologie Intégrée du Globule Rouge, UMR_S1134, BIGR, INSERM, F-75015, Paris, France
- Laboratoire d’Excellence GR-Ex, 75015 Paris, France
- Université de la Réunion, Biologie Intégrée du Globule Rouge, UMR_S1134, BIGR, Faculté des Sciences & Technologies Saint-Denis, F-97715 St. Denis, France
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Anxiolytic and Anti-depressive Like Effects of Translocator Protein (18 kDa) Ligand YL-IPA08 in a Rat Model of Postpartum Depression. Neurochem Res 2020; 45:1746-1757. [DOI: 10.1007/s11064-020-03036-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Revised: 03/19/2020] [Accepted: 04/15/2020] [Indexed: 12/18/2022]
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Extra-adrenal glucocorticoid biosynthesis: implications for autoimmune and inflammatory disorders. Genes Immun 2020; 21:150-168. [PMID: 32203088 PMCID: PMC7276297 DOI: 10.1038/s41435-020-0096-6] [Citation(s) in RCA: 80] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2019] [Revised: 03/05/2020] [Accepted: 03/09/2020] [Indexed: 12/11/2022]
Abstract
Glucocorticoid synthesis is a complex, multistep process that starts with cholesterol being delivered to the inner membrane of mitochondria by StAR and StAR-related proteins. Here its side chain is cleaved by CYP11A1 producing pregnenolone. Pregnenolone is converted to cortisol by the enzymes 3-βHSD, CYP17A1, CYP21A2 and CYP11B1. Glucocorticoids play a critical role in the regulation of the immune system and exert their action through the glucocorticoid receptor (GR). Although corticosteroids are primarily produced in the adrenal gland, they can also be produced in a number of extra-adrenal tissue including the immune system, skin, brain, and intestine. Glucocorticoid production is regulated by ACTH, CRH, and cytokines such as IL-1, IL-6 and TNFα. The bioavailability of cortisol is also dependent on its interconversion to cortisone which is inactive, by 11βHSD1/2. Local and systemic glucocorticoid biosynthesis can be stimulated by ultraviolet B, explaining its immunosuppressive activity. In this review, we want to emphasize that dysregulation of extra-adrenal glucocorticoid production can play a key role in a variety of autoimmune diseases including multiple sclerosis (MS), lupus erythematosus (LE), rheumatoid arthritis (RA), and skin inflammatory disorders such as psoriasis and atopic dermatitis (AD). Further research on local glucocorticoid production and its bioavailability may open doors into new therapies for autoimmune diseases.
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Jung ME, Metzger DB, Hall J. The long-term but not short-term use of benzodiazepine impairs motoric function and upregulates amyloid β in part through the suppression of translocator protein. Pharmacol Biochem Behav 2020; 191:172873. [PMID: 32105662 DOI: 10.1016/j.pbb.2020.172873] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Revised: 01/22/2020] [Accepted: 02/15/2020] [Indexed: 11/24/2022]
Abstract
Many elderly American women use CNS depressant benzodiazepine (BZD) to ameliorate anxiety or insomnia. However, the chronic use of BZD (cBZD) is prevalent, causing adverse effects of BZD that include movement deficit. We previously reported that cBZD upregulates neurotoxic amyloid β42 (Aβ42) and downregulates neuroprotective translocator protein (TSPO) in the cerebellum, the brain area of movement and balance. The aim of the current study is two-fold: 1) to determine a direct effect of TSPO (inhibition) on cBZD-induced Aβ42 and Aβ-associated molecules; Aβ-producing-protein presenilin-1 (PS1) and Aβ-degrading-enzyme neprilysin and 2) to determine whether Aβ42 upregulation and motoric deficit occur upon a long-term (cBZD) rather than a short-term BZD (sBZD) treatment. Old female mice received BZD (lorazepam) for 20 days (cBZD) or 3 days (sBZD) with or without prototype TSPO ligand PK11195 and were tested for motoric performance for 3 days using Rotarod. ELISA was conducted to measure Aβ42 level and neprilysin activity in cerebellum. RT-PCR and immunoblot were conducted to measure the mRNA and protein levels of TSPO, PS1, and neprilysin. cBZD treatment decreased TSPO and neprilysin but increased Aβ42 accompanied by motoric deficit. Chronic PK11195 treatment acted as a TSPO inhibitor by suppressing TSPO expression and mimicked or exacerbated the effects of cBZD on all parameters measured except for PS1. None of the molecular and behavioral changes induced by cBZD were reproduced by sBZD treatment. These data suggest that cBZD upregulates Aβ42 and downregulates neprilysin in part through TSPO inhibition, the mechanisms distinct from sBZD, collectively contributing to motoric deficit.
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Affiliation(s)
- Marianna E Jung
- Pharmacology and Neuroscience, UNT Health Science Center, Institute for Healthy Aging, 3500 Camp Bowie Boulevard, Fort Worth, TX 76107, United States of America.
| | - Daniel B Metzger
- Pharmacology and Neuroscience, UNT Health Science Center, Institute for Healthy Aging, 3500 Camp Bowie Boulevard, Fort Worth, TX 76107, United States of America
| | - James Hall
- Pharmacology and Neuroscience, UNT Health Science Center, Institute for Healthy Aging, 3500 Camp Bowie Boulevard, Fort Worth, TX 76107, United States of America
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Selvaraj V, Morohaku K, Koganti PP, Zhang J, He W, Quirk SM, Stocco DM. Commentary: Amhr2-Cre-Mediated Global Tspo Knockout. Front Endocrinol (Lausanne) 2020; 11:472. [PMID: 32793121 PMCID: PMC7393387 DOI: 10.3389/fendo.2020.00472] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Accepted: 06/16/2020] [Indexed: 11/26/2022] Open
Affiliation(s)
- Vimal Selvaraj
- Department of Animal Science, College of Agriculture and Life Sciences, Cornell University, Ithaca, NY, United States
- *Correspondence: Vimal Selvaraj
| | - Kanako Morohaku
- Division of Animal Science, School of Science and Technology, Institute of Agriculture, Shinshu University, Nagano, Japan
| | - Prasanthi P. Koganti
- Department of Animal Science, College of Agriculture and Life Sciences, Cornell University, Ithaca, NY, United States
| | - Jianmin Zhang
- State Key Laboratory of Medical Molecular Biology, Department of Immunology, Research Center on Pediatric Development Diseases, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and School of Basic Medicine, Peking Union Medical College, Beijing, China
| | - Wei He
- State Key Laboratory of Medical Molecular Biology, Department of Immunology, Research Center on Pediatric Development Diseases, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and School of Basic Medicine, Peking Union Medical College, Beijing, China
| | - Susan M. Quirk
- Department of Animal Science, College of Agriculture and Life Sciences, Cornell University, Ithaca, NY, United States
| | - Douglas M. Stocco
- Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, TX, United States
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30
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Chung JY, Chen H, Papadopoulos V, Zirkin B. Cholesterol accumulation, lipid droplet formation, and steroid production in Leydig cells: Role of translocator protein (18-kDa). Andrology 2019; 8:719-730. [PMID: 31738001 DOI: 10.1111/andr.12733] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2019] [Revised: 11/06/2019] [Accepted: 11/14/2019] [Indexed: 02/06/2023]
Abstract
BACKGROUND Cholesterol import into the mitochondria of steroid-producing cells is the rate-determining step in steroidogenesis. Numerous studies have provided evidence that the cholesterol-binding translocator protein (18 kDa TSPO) plays an important role in cholesterol translocation into mitochondria and that it also might act on cholesterol homeostasis. Several TSPO-specific ligands have been shown to increase steroid production in vitro and in vivo. OBJECTIVES The present study assessed the effects of the TSPO drug ligand FGIN-1-27 on cholesterol accumulation and lipid droplet formation in relationship to steroid formation. MATERIALS AND METHODS Using MA-10 and primary Leydig cells, immunocytochemical and molecular methods were used to examine cholesterol accumulation, the formation of lipid droplets, and steroid formation in response to LH and FGIN-1-27. Additionally, we determined the effects of Tspo knockout by CRISPR/Cas9, and of siRNA knockdowns of Tspo and Plin2 (Perilipin 2; also known as adipose differentiation-related protein, ADFP) on LH- and FGIN-1-27-induced steroidogenesis. RESULTS In response to LH and FGIN-1-27, cultured MA-10 cells and primary Leydig cells increased steroid formation, cholesterol accumulation, and lipid droplet formation. Cholesterol accumulation in the lipid droplets also was increased in Tspo knockout cells. Knockout of Tspo or its knockdown in MA-10 cells resulted in reduced progesterone formation in response to both LH and FGIN-1-27, as did knockdown of Plin2. Steroid production also was inhibited by the cholesteryl ester hydrolase inhibitor diethylumbelliferyl phosphate. DISCUSSION AND CONCLUSION These results support the conclusion that FGIN-1-27 stimulates steroid formation by increasing TSPO-mediated cholesterol translocation into the inner mitochondria for steroidogenesis, as well as into the cytosol for lipid droplet formation. FGIN-1-27 also increased steroid formation at least in part by inducing the conversion of cholesteryl ester located in lipid droplets to cholesterol, thus making available more substrate for steroid formation.
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Affiliation(s)
- Jin-Yong Chung
- Department of Biochemistry and Molecular Biology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
| | - Haolin Chen
- Department of Biochemistry and Molecular Biology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA.,Department of Anesthesiology, the Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Vassilios Papadopoulos
- Department of Pharmacology and Pharmaceutical Science, School of Pharmacy, University of Southern California, Los Angeles, CA, USA
| | - Barry Zirkin
- Department of Biochemistry and Molecular Biology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
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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: 1.2] [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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32
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Sahoo S, S. B. Pharmacogenomic assessment of herbal drugs in affective disorders. Biomed Pharmacother 2019; 109:1148-1162. [DOI: 10.1016/j.biopha.2018.10.135] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2018] [Revised: 10/20/2018] [Accepted: 10/21/2018] [Indexed: 12/14/2022] Open
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Kawahara Y, Mitsui K, Niwa T, Morimoto N, Kawaharada S, Katsumata S. Translocator protein 18kDa antagonist ameliorates stress-induced stool abnormality and abdominal pain in rodent stress models. Neurogastroenterol Motil 2018; 30:e13425. [PMID: 30069991 DOI: 10.1111/nmo.13425] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Accepted: 06/18/2018] [Indexed: 12/17/2022]
Abstract
BACKGROUND Irritable bowel syndrome (IBS) is a functional gastrointestinal (GI) disorder characterized by abdominal pain and abnormal bowel habits, both of which are exacerbated by psychological stress. The translocator protein 18kDa (TSPO) is a marker of reactive gliosis in a number of central nervous system (CNS) diseases and responsible for many cellular functions, including neurosteroidogenesis. Although it has been reported that psychological stress disturbs neurosteroids levels, the pathophysiological relevance of TSPO in IBS is poorly understood. METHODS We examined the effects of a TSPO antagonist, ONO-2952, on stress-induced stool abnormality and abdominal pain in rats, and on anxiety-related behavior induced by cholecystokinin. KEY RESULTS Oral administration of ONO-2952 attenuated stress-induced defecation and rectal hyperalgesia in rats with an efficacy equivalent to that of a 5-HT3 receptor antagonist. In addition, ONO-2952 suppressed cholecystokinin-induced anxiety-like behavior with an efficacy equivalent to that of psychotropic drugs. On the other hand, ONO-2952 did not affect spontaneous defecation, gastrointestinal transit, visceral nociceptive threshold, and neurosteroid production in non-stressed rats even at a dose 10 times higher than its effective dose in the stress models. CONCLUSIONS AND INFERENCES These results suggest that TSPO antagonism results in antistress action, and that ONO-2952 is a promising candidate for IBS without side effects associated with current treatment.
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Affiliation(s)
- Y Kawahara
- Discovery Research Laboratories I, ONO Pharmaceutical Co., Ltd., Osaka, Japan
| | - K Mitsui
- Discovery Research Laboratories I, ONO Pharmaceutical Co., Ltd., Osaka, Japan
| | - T Niwa
- Discovery Research Laboratories I, ONO Pharmaceutical Co., Ltd., Osaka, Japan
| | - N Morimoto
- Discovery Research Laboratories I, ONO Pharmaceutical Co., Ltd., Osaka, Japan
| | - S Kawaharada
- Discovery Research Laboratories I, ONO Pharmaceutical Co., Ltd., Osaka, Japan
| | - S Katsumata
- Discovery Research Laboratories I, ONO Pharmaceutical Co., Ltd., Osaka, Japan
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Ilkan Z, Akar FG. The Mitochondrial Translocator Protein and the Emerging Link Between Oxidative Stress and Arrhythmias in the Diabetic Heart. Front Physiol 2018; 9:1518. [PMID: 30416455 PMCID: PMC6212558 DOI: 10.3389/fphys.2018.01518] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2018] [Accepted: 10/09/2018] [Indexed: 02/06/2023] Open
Abstract
The mitochondrial translocator protein (TSPO) is a key outer mitochondrial membrane protein that regulates the activity of energy-dissipating mitochondrial channels in response to oxidative stress. In this article, we provide an overview of the role of TSPO in the systematic amplification of reactive oxygen species (ROS) through an autocatalytic process known as ROS-induced ROS-release (RIRR). We describe how this TSPO-driven process destabilizes the mitochondrial membrane potential leading to electrical instability at the cellular and whole heart levels. Finally, we provide our perspective on the role of TSPO in the pathophysiology of diabetes, in general and diabetes-related arrhythmias, in particular.
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Affiliation(s)
- Zeki Ilkan
- Cardiovascular Research Center, Icahn School of Medicine at Mount Sinai, New York, NY, United States
| | - Fadi G Akar
- Cardiovascular Research Center, Icahn School of Medicine at Mount Sinai, New York, NY, United States
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35
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Singh G, Sankanagoudar S, Dogra P, Chandra NC. Interlink between cholesterol & cell cycle in prostate carcinoma. Indian J Med Res 2018; 146:S38-S44. [PMID: 29578193 PMCID: PMC5890594 DOI: 10.4103/ijmr.ijmr_1639_15] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Background & objectives: Earlier reports have shown hypocholesterolaemia in cancer patients and high number of lipid rafts in cancer cells. The primary objective of this study was to compare the intracellular cholesterol turnover in non-cancerous (benign) prostatic hyperplasia (BPH) and carcinoma prostate (CAP) with normal prostate cells obtained from patients undergoing radical cystectomy for carcinoma bladder (sham control). Methods: ELISA-based estimation of prostate-specific antigen (PSA), evaluation of expression of low-density lipoprotein receptor (LDLR), peripheral-type benzodiazepine receptor (PBR) and cyclin E, immunohistochemistry and confocal microscopy, measurement of integrated optical density of the diaminobenzidine (DAB)-stained immunohistograms, isolation of nucleus and cell cytoplasm from prostate tissue by ultracentrifugation followed by estimation of cholesterol spectrophotometrically in isolated nuclear and cytoplasmic fractions were performed. Results: Seventy five individuals, 25 for each group (BPH n=25; CAP n=25 and sham control n=25), were included in the study. Cholesterol was increased in the cytoplasm and nucleus of the prostate cancer cells along with elevated expression of LDLR. Increased cholesterol concentration in the cell nucleus was found comparable with the increased expression of cholesterol transporter viz. PBR in the prostate tumour tissues as compared to its expression in normal prostate cells obtained from individuals undergoing radical cystectomy for carcinoma bladder. Cell cycle protein cyclin E was also highly expressed in cancer tissues. Interpretation & conclusions: The present findings along with increased expression of cell cycle protein cyclin E in the cell nucleus of the tumour tissue suggested the possibility of an intriguing role of cholesterol in the mechanism of cell cycle process of prostate cell proliferation.
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Affiliation(s)
- Govind Singh
- Department of Biochemistry, All India Institute of Medical Sciences, New Delhi, India
| | | | - Premnath Dogra
- Department of Urology, All India Institute of Medical Sciences, New Delhi, India
| | - Nimai Chand Chandra
- Department of Biochemistry, All India Institute of Medical Sciences, New Delhi, India
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36
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Edison P, Donat CK, Sastre M. In vivo Imaging of Glial Activation in Alzheimer's Disease. Front Neurol 2018; 9:625. [PMID: 30131755 PMCID: PMC6090997 DOI: 10.3389/fneur.2018.00625] [Citation(s) in RCA: 64] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2018] [Accepted: 07/10/2018] [Indexed: 12/12/2022] Open
Abstract
Alzheimer's disease (AD) is characterized by memory loss and decline of cognitive function, associated with progressive neurodegeneration. While neuropathological processes like amyloid plaques and tau neurofibrillary tangles have been linked to neuronal death in AD, the precise role of glial activation on disease progression is still debated. It was suggested that neuroinflammation could occur well ahead of amyloid deposition and may be responsible for clearing amyloid, having a neuroprotective effect; however, later in the disease, glial activation could become deleterious, contributing to neuronal toxicity. Recent genetic and preclinical studies suggest that the different activation states of microglia and astrocytes are complex, not as polarized as previously thought, and that the heterogeneity in their phenotype can switch during disease progression. In the last few years, novel imaging techniques e.g., new radiotracers for assessing glia activation using positron emission tomography and advanced magnetic resonance imaging technologies have emerged, allowing the correlation of neuro-inflammatory markers with cognitive decline, brain function and brain pathology in vivo. Here we review all new imaging technology in AD patients and animal models that has the potential to serve for early diagnosis of the disease, to monitor disease progression and to test the efficacy and the most effective time window for potential anti-inflammatory treatments.
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Affiliation(s)
- Paul Edison
- Division of Brain Sciences, Department of Medicine, Imperial College London, London, United Kingdom
| | - Cornelius K Donat
- Division of Brain Sciences, Department of Medicine, Imperial College London, London, United Kingdom
| | - Magdalena Sastre
- Division of Brain Sciences, Department of Medicine, Imperial College London, London, United Kingdom
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37
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Bhoola NH, Mbita Z, Hull R, Dlamini Z. Translocator Protein (TSPO) as a Potential Biomarker in Human Cancers. Int J Mol Sci 2018; 19:ijms19082176. [PMID: 30044440 PMCID: PMC6121633 DOI: 10.3390/ijms19082176] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Revised: 06/21/2018] [Accepted: 06/24/2018] [Indexed: 11/17/2022] Open
Abstract
TSPO is a receptor involved in the regulation of cellular proliferation, apoptosis and mitochondrial functions. Previous studies showed that the expression of TSPO protein correlated positively with tumour malignancy and negatively with patient survival. The aim of this study was to determine the transcription of Tspo mRNA in various types of normal and cancer tissues. In situ hybridization was performed to localise the Tspo mRNA in various human normal and cancer tissues. The relative level of Tspo mRNA was quantified using fluorescent intensity and visual estimation of colorimetric staining. RT-PCR was used to confirm these mRNA levels in normal lung, lung cancer, liver cancer, and cervical cancer cell lines. There was a significant increase in the level of transcription in liver, prostate, kidney, and brain cancers while a significant decrease was observed in cancers of the colon and lung. Quantitative RT-PCR confirmed that the mRNA levels of Tspo are higher in a normal lung cell line than in a lung cancer cell line. An increase in the expression levels of Tspo mRNA is not necessarily a good diagnostic biomarker in most cancers with changes not being large enough to be significantly different when detected by in situ hybridisation.
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Affiliation(s)
- Nimisha H Bhoola
- Faculty of Health Sciences, University of the Witwatersrand, Johannesburg 2193, South Africa.
| | - Zukile Mbita
- Department of Biochemistry, Microbiology and Biotechnology, University of Limpopo, Private Bag X1106, Sovenga 0727, South Africa.
| | - Rodney Hull
- Research, Innovation & Engagements Portfolio, Mangosuthu University of Technology, Durban 4031, South Africa.
| | - Zodwa Dlamini
- Research, Innovation & Engagements Portfolio, Mangosuthu University of Technology, Durban 4031, South Africa.
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38
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Selvaraj V, Stocco DM, Clark BJ. Current knowledge on the acute regulation of steroidogenesis. Biol Reprod 2018; 99:13-26. [PMID: 29718098 PMCID: PMC6044331 DOI: 10.1093/biolre/ioy102] [Citation(s) in RCA: 74] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2017] [Revised: 02/23/2018] [Accepted: 04/26/2018] [Indexed: 12/31/2022] Open
Abstract
How rapid induction of steroid hormone biosynthesis occurs in response to trophic hormone stimulation of steroidogenic cells has been a subject of intensive investigation for approximately six decades. A key observation made very early was that acute regulation of steroid biosynthesis required swift and timely synthesis of a new protein whose role appeared to be involved in the delivery of the substrate for all steroid hormones, cholesterol, from the outer to the inner mitochondrial membrane where the process of steroidogenesis begins. It was quickly learned that this transfer of cholesterol to the inner mitochondrial membrane was the regulated and rate-limiting step in steroidogenesis. Following this observation, the quest for this putative regulator protein(s) began in earnest in the late 1950s. This review provides a history of this quest, the candidate proteins that arose over the years and facts surrounding their rise or decline. Only two have persisted-translocator protein (TSPO) and the steroidogenic acute regulatory protein (StAR). We present a detailed summary of the work that has been published for each of these two proteins, the specific data that has appeared in support of their role in cholesterol transport and steroidogenesis, and the ensuing observations that have arisen in recent years that have refuted the role of TSPO in this process. We believe that the only viable candidate that has been shown to be indispensable is the StAR protein. Lastly, we provide our view on what may be the most important questions concerning the acute regulation of steroidogenesis that need to be asked in future.
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Affiliation(s)
- Vimal Selvaraj
- Department of Animal Science, College of Agriculture and Life Sciences, Cornell University, Ithaca, New York, USA
| | - Douglas M Stocco
- Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, Texas, USA
| | - Barbara J Clark
- Department of Biochemistry and Molecular Genetics, University of Louisville, Louisville, Kentucky, USA
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Expression and purification of the mammalian translocator protein for structural studies. PLoS One 2018; 13:e0198832. [PMID: 29897975 PMCID: PMC5999236 DOI: 10.1371/journal.pone.0198832] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2018] [Accepted: 05/26/2018] [Indexed: 11/19/2022] Open
Abstract
The translocator protein (TSPO) is an 18 kDa polytopic membrane protein of the outer mitochondrial membrane, abundantly present in the steroid-synthesising cells. TSPO has been linked to a number of disorders, and it is recognised as a promising drug target with a range of potential medical applications. Structural and biochemical characterisation of a mammalian TSPO requires expression and purification of the protein of high quality in sufficiently large quantities. Here we describe detailed procedures for heterologous expression and purification of mammalian TSPO in HEK293 cells. We demonstrate that the established procedures can be used for untagged TSPO as well as for C-terminally fused TSPO constructs. Our protocol can be routinely used to generate high-quality TSPO preparations for biochemical and structural studies.
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40
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Bonsack F, Sukumari-Ramesh S. TSPO: An Evolutionarily Conserved Protein with Elusive Functions. Int J Mol Sci 2018; 19:ijms19061694. [PMID: 29875327 PMCID: PMC6032217 DOI: 10.3390/ijms19061694] [Citation(s) in RCA: 61] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Accepted: 05/18/2018] [Indexed: 12/22/2022] Open
Abstract
TSPO (18 kDa translocator protein) was identified decades ago in a search for peripheral tissue binding sites for benzodiazepines, and was formerly called the peripheral benzodiazepine receptor. TSPO is a conserved protein throughout evolution and it is implicated in the regulation of many cellular processes, including inflammatory responses, oxidative stress, and mitochondrial homeostasis. TSPO, apart from its broad expression in peripheral tissues, is highly expressed in neuroinflammatory cells, such as activated microglia. In addition, emerging studies employing the ligands of TSPO suggest that TSPO plays an important role in neuropathological settings as a biomarker and therapeutic target. However, the precise molecular function of this protein in normal physiology and neuropathology remains enigmatic. This review provides an overview of recent advances in our understanding of this multifaceted molecule and identifies the knowledge gap in the field for future functional studies.
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Affiliation(s)
- Frederick Bonsack
- Department of Neurosurgery, Medical College of Georgia, Augusta University, 1120 15th Street, Augusta, GA 30912, USA.
| | - Sangeetha Sukumari-Ramesh
- Department of Neurosurgery, Medical College of Georgia, Augusta University, 1120 15th Street, Augusta, GA 30912, USA.
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41
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Cumming P, Burgher B, Patkar O, Breakspear M, Vasdev N, Thomas P, Liu GJ, Banati R. Sifting through the surfeit of neuroinflammation tracers. J Cereb Blood Flow Metab 2018; 38:204-224. [PMID: 29256293 PMCID: PMC5951023 DOI: 10.1177/0271678x17748786] [Citation(s) in RCA: 73] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Revised: 10/26/2017] [Accepted: 11/09/2017] [Indexed: 01/09/2023]
Abstract
The first phase of molecular brain imaging of microglial activation in neuroinflammatory conditions began some 20 years ago with the introduction of [11C]-( R)-PK11195, the prototype isoquinoline ligand for translocator protein (18 kDa) (TSPO). Investigations by positron emission tomography (PET) revealed microgliosis in numerous brain diseases, despite the rather low specific binding signal imparted by [11C]-( R)-PK11195. There has since been enormous expansion of the repertoire of TSPO tracers, many with higher specific binding, albeit complicated by allelic dependence of the affinity. However, the specificity of TSPO PET for revealing microglial activation not been fully established, and it has been difficult to judge the relative merits of the competing tracers and analysis methods with respect to their sensitivity for detecting microglial activation. We therefore present a systematic comparison of 13 TSPO PET and single photon computed tomography (SPECT) tracers belonging to five structural classes, each of which has been investigated by compartmental analysis in healthy human brain relative to a metabolite-corrected arterial input. We emphasize the need to establish the non-displaceable binding component for each ligand and conclude with five recommendations for a standard approach to define the cellular distribution of TSPO signals, and to characterize the properties of candidate TSPO tracers.
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Affiliation(s)
- Paul Cumming
- School of Psychology and Counselling and IHBI, Faculty of Health, Queensland University of Technology, Brisbane, Australia
- QIMR Berghofer Institute, Brisbane, Australia
| | - Bjorn Burgher
- QIMR Berghofer Institute, Brisbane, Australia
- Metro North Mental Health Service, Brisbane, Australia
| | - Omkar Patkar
- School of Psychology and Counselling and IHBI, Faculty of Health, Queensland University of Technology, Brisbane, Australia
- QIMR Berghofer Institute, Brisbane, Australia
| | - Michael Breakspear
- QIMR Berghofer Institute, Brisbane, Australia
- Metro North Mental Health Service, Brisbane, Australia
| | - Neil Vasdev
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, Boston, MA, USA
- Department of Radiology, Harvard Medical School, Boston, MA, USA
| | - Paul Thomas
- Herston Imaging Research Facility, Faculty of Medicine, University of Queensland Centre for Clinical Research, Herston, Australia
| | - Guo-Jun Liu
- Australian Nuclear Science and Technology Organisation, Lucas Heights, Australia
- National Imaging Facility, Brain and Mind Centre and Faculty of Health Sciences, University of Sydney, Camperdown, Australia
| | - Richard Banati
- Australian Nuclear Science and Technology Organisation, Lucas Heights, Australia
- National Imaging Facility, Brain and Mind Centre and Faculty of Health Sciences, University of Sydney, Camperdown, Australia
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42
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Papadopoulos V, Fan J, Zirkin B. Translocator protein (18 kDa): an update on its function in steroidogenesis. J Neuroendocrinol 2018; 30:10.1111/jne.12500. [PMID: 28667781 PMCID: PMC5748373 DOI: 10.1111/jne.12500] [Citation(s) in RCA: 69] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/04/2017] [Revised: 06/26/2017] [Accepted: 06/27/2017] [Indexed: 12/15/2022]
Abstract
Translocator protein (18 kDa) (TSPO) is a ubiquitous mitochondrial protein. Studies of its responses to drug and endogenous ligands have shown TSPO to be involved either directly or indirectly in numerous biological functions, including mitochondrial cholesterol transport and steroid hormone biosynthesis, porphyrin transport and heme synthesis, apoptosis, cell proliferation, and anion transport. Localised to the outer mitochondrial membrane of steroidogenic cells, TSPO has been shown to associate with cytosolic and mitochondrial proteins as part of a large multiprotein complex involved in mitochondrial cholesterol transport, the rate-limiting step in steroidogenesis. There is general agreement as to the structure and pharmacology of TSPO. Stimulation of TSPO has been shown to have therapeutic use as anxiolytics by inducing allopregnanolone production in the brain, and also potentially for re-establishing androgen levels in hypogonadal ageing animals. Until recently, there has been general agreement regarding the role of TSPO in steroidogenesis. However, recent studies involving genetic depletion of TSPO in mice have created controversy about the role of this protein in steroid and heme synthesis. We review the data on the structure and function of TSPO, as well as the recent results obtained using various genetic animal models. Taken together, these studies suggest that TSPO is a unique mitochondrial pharmacological target for diseases that involve increased mitochondrial activity, including steroidogenesis. Although there is no known mammalian species that lacks TSPO, it is likely that, because of the importance of this ancient protein in evolution and mitochondrial function, redundant mechanisms may exist to replace it under circumstances when it is removed.
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Affiliation(s)
- Vassilios Papadopoulos
- Department of Pharmacology and Pharmaceutical Sciences, School of Pharmacy, University of Southern California, Los Angeles, CA 90089
- Research Institute of the McGill University Health Centre and Department of Medicine, McGill University, Montreal, Quebec, H4A 3J1, Canada
| | - Jinjiang Fan
- Research Institute of the McGill University Health Centre and Department of Medicine, McGill University, Montreal, Quebec, H4A 3J1, Canada
| | - Barry Zirkin
- Department of Biochemistry and Molecular Biology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland 21205, USA
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43
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Liang JJ, Rasmusson AM. Overview of the Molecular Steps in Steroidogenesis of the GABAergic Neurosteroids Allopregnanolone and Pregnanolone. CHRONIC STRESS (THOUSAND OAKS, CALIF.) 2018; 2:2470547018818555. [PMID: 32440589 PMCID: PMC7219929 DOI: 10.1177/2470547018818555] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Accepted: 11/19/2018] [Indexed: 12/23/2022]
Abstract
Allopregnanolone and pregnanolone-neurosteroids synthesized from progesterone in the brain, adrenal gland, ovary and testis-have been implicated in a range of neuropsychiatric conditions including seizure disorders, post-traumatic stress disorder, major depression, post-partum depression, pre-menstrual dysphoric disorder, chronic pain, Parkinson's disease, Alzheimer's disease, neurotrauma, and stroke. Allopregnanolone and pregnanolone equipotently facilitate the effects of gamma-amino-butyric acid (GABA) at GABAA receptors, and when sulfated, antagonize N-methyl-D-aspartate receptors. They play myriad roles in neurophysiological homeostasis and adaptation to stress while exerting anxiolytic, antidepressant, anti-nociceptive, anticonvulsant, anti-inflammatory, sleep promoting, memory stabilizing, neuroprotective, pro-myelinating, and neurogenic effects. Given that these neurosteroids are synthesized de novo on demand, this review details the molecular steps involved in the biochemical conversion of cholesterol to allopregnanolone and pregnanolone within steroidogenic cells. Although much is known about the early steps in neurosteroidogenesis, less is known about transcriptional, translational, and post-translational processes in allopregnanolone- and pregnanolone-specific synthesis. Further research to elucidate these mechanisms as well as to optimize the timing and dose of interventions aimed at altering the synthesis or levels of these neurosteroids is much needed. This should include the development of novel therapeutics for the many neuropsychiatric conditions to which dysregulation of these neurosteroids contributes.
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Affiliation(s)
| | - Ann M. Rasmusson
- Boston
University School of Medicine, Boston, MA,
USA
- National Center for PTSD, Women’s Health
Science Division, Department of Veterans Affairs, Boston, MA, USA
- VA Boston Healthcare System, Boston, MA,
USA
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44
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Notter T, Coughlin JM, Sawa A, Meyer U. Reconceptualization of translocator protein as a biomarker of neuroinflammation in psychiatry. Mol Psychiatry 2018; 23:36-47. [PMID: 29203847 DOI: 10.1038/mp.2017.232] [Citation(s) in RCA: 94] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/23/2017] [Revised: 09/05/2017] [Accepted: 10/02/2017] [Indexed: 02/06/2023]
Abstract
A great deal of interest in psychiatric research is currently centered upon the pathogenic role of inflammatory processes. Positron emission tomography (PET) using radiolabeled ligands selective for the 18 kDa translocator protein (TSPO) has become the most widely used technique to assess putative neuroimmune abnormalities in vivo. Originally used to detect discrete neurotoxic damages, TSPO has generally turned into a biomarker of 'neuroinflammation' or 'microglial activation'. Psychiatric research has mostly accepted these denotations of TSPO, even if they may be inadequate and misleading under many pathological conditions. A reliable and neurobiologically meaningful diagnosis of 'neuroinflammation' or 'microglial activation' is unlikely to be achieved by the sole use of TSPO PET imaging. It is also very likely that the pathological meanings of altered TSPO binding or expression are disease-specific, and therefore, not easily generalizable across different neuropathologies or inflammatory conditions. This difficulty is intricately linked to the varying (and still ill-defined) physiological functions and cellular expression patterns of TSPO in health and disease. While altered TSPO binding or expression may indeed mirror ongoing neuroinflammatory processes in some cases, it may reflect other pathophysiological processes such as abnormalities in cell metabolism, energy production and oxidative stress in others. Hence, the increasing popularity of TSPO PET imaging has paradoxically introduced substantial uncertainty regarding the nature and meaning of neuroinflammatory processes and microglial activation in psychiatry, and likely in other neuropathological conditions as well. The ambiguity of conceiving TSPO simply as a biomarker of 'neuroinflammation' or 'microglial activation' calls for alternative interpretations and complimentary approaches. Without the latter, the ongoing scientific efforts and excitement surrounding the role of the neuroimmune system in psychiatry may not turn into therapeutic hope for affected individuals.
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Affiliation(s)
- T Notter
- Institute of Pharmacology and Toxicology, University of Zurich-Vetsuisse, Zurich, Switzerland.,Neuroscience Center Zurich, University of Zurich and ETH Zurich, Zurich, Switzerland
| | - J M Coughlin
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins Medical Institutions, Baltimore, MD, USA.,Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutions, Baltimore, MD, USA
| | - A Sawa
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins Medical Institutions, Baltimore, MD, USA
| | - U Meyer
- Institute of Pharmacology and Toxicology, University of Zurich-Vetsuisse, Zurich, Switzerland.,Neuroscience Center Zurich, University of Zurich and ETH Zurich, Zurich, Switzerland
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Molecular Imaging of Neuroinflammation in Idiopathic Parkinson's Disease. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2018; 141:347-363. [DOI: 10.1016/bs.irn.2018.08.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
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46
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Zwergal A, Günther L, Brendel M, Beck R, Lindner S, Xiong G, Eilles E, Unterrainer M, Albert NL, Becker-Bense S, Brandt T, Ziegler S, la Fougère C, Dieterich M, Bartenstein P. In Vivo Imaging of Glial Activation after Unilateral Labyrinthectomy in the Rat: A [ 18F]GE180-PET Study. Front Neurol 2017; 8:665. [PMID: 29312111 PMCID: PMC5732190 DOI: 10.3389/fneur.2017.00665] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2017] [Accepted: 11/24/2017] [Indexed: 01/31/2023] Open
Abstract
The functional relevance of reactive gliosis for recovery from acute unilateral vestibulopathy is unknown. In the present study, glial activation was visualized in vivo by [18F]GE180-PET in a rat model of unilateral labyrinthectomy (UL) and compared to behavioral vestibular compensation (VC) overtime. 14 Sprague-Dawley rats underwent a UL by transtympanic injection of bupivacaine/arsenilate, 14 rats a SHAM UL (injection of normal saline). Glial activation was depicted with [18F]GE180-PET and ex vivo autoradiography at baseline and 7, 15, 30 days after UL/SHAM UL. Postural asymmetry and nystagmus were registered at 1, 2, 3, 7, 15, 30 days after UL/SHAM UL. Signs of vestibular imbalance were found only after UL, which significantly decreased until days 15 and 30. In parallel, [18F]GE180-PET and ex vivo autoradiography depicted glial activation in the ipsilesional vestibular nerve and nucleus on days 7 and 15 after UL. Correlation analysis revealed a strong negative association of [18F]GE180 uptake in the ipsilesional vestibular nucleus on day 7 with the rate of postural recovery (R = −0.90, p < 0.001), suggesting that glial activation accelerates VC. In conclusion, glial activation takes place in the ipsilesional vestibular nerve and nucleus within the first 30 days after UL in the rat and can be visualized in vivo by [18F]GE180-PET.
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Affiliation(s)
- Andreas Zwergal
- German Center for Vertigo and Balance Disorders, DSGZ, Ludwig-Maximilians-University, Munich, Germany.,Department of Neurology, Ludwig-Maximilians-University, Munich, Germany
| | - Lisa Günther
- German Center for Vertigo and Balance Disorders, DSGZ, Ludwig-Maximilians-University, Munich, Germany
| | - Matthias Brendel
- Department of Nuclear Medicine, Ludwig-Maximilians-University, Munich, Germany.,Munich Cluster of Systems Neurology, SyNergy, Munich, Germany
| | - Roswitha Beck
- German Center for Vertigo and Balance Disorders, DSGZ, Ludwig-Maximilians-University, Munich, Germany
| | - Simon Lindner
- Department of Nuclear Medicine, Ludwig-Maximilians-University, Munich, Germany
| | - Guoming Xiong
- German Center for Vertigo and Balance Disorders, DSGZ, Ludwig-Maximilians-University, Munich, Germany
| | - Eva Eilles
- German Center for Vertigo and Balance Disorders, DSGZ, Ludwig-Maximilians-University, Munich, Germany
| | - Marcus Unterrainer
- Department of Nuclear Medicine, Ludwig-Maximilians-University, Munich, Germany
| | | | - Sandra Becker-Bense
- German Center for Vertigo and Balance Disorders, DSGZ, Ludwig-Maximilians-University, Munich, Germany.,Department of Neurology, Ludwig-Maximilians-University, Munich, Germany
| | - Thomas Brandt
- German Center for Vertigo and Balance Disorders, DSGZ, Ludwig-Maximilians-University, Munich, Germany.,Clinical Neurosciences, Ludwig-Maximilians-University, Munich, Germany
| | - Sibylle Ziegler
- Department of Nuclear Medicine, Ludwig-Maximilians-University, Munich, Germany
| | - Christian la Fougère
- German Center for Vertigo and Balance Disorders, DSGZ, Ludwig-Maximilians-University, Munich, Germany.,Department of Nuclear Medicine, Eberhard Karls University, Tübingen, Germany
| | - Marianne Dieterich
- German Center for Vertigo and Balance Disorders, DSGZ, Ludwig-Maximilians-University, Munich, Germany.,Department of Neurology, Ludwig-Maximilians-University, Munich, Germany.,Munich Cluster of Systems Neurology, SyNergy, Munich, Germany
| | - Peter Bartenstein
- German Center for Vertigo and Balance Disorders, DSGZ, Ludwig-Maximilians-University, Munich, Germany.,Department of Nuclear Medicine, Ludwig-Maximilians-University, Munich, Germany.,Munich Cluster of Systems Neurology, SyNergy, Munich, Germany
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47
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Keller T, Krzyczmonik A, Forsback S, Picón FRL, Kirjavainen AK, Takkinen J, Rajander J, Cacheux F, Damont A, Dollé F, Rinne JO, Haaparanta-Solin M, Solin O. Radiosynthesis and Preclinical Evaluation of [ 18F]F-DPA, A Novel Pyrazolo[1,5a]pyrimidine Acetamide TSPO Radioligand, in Healthy Sprague Dawley Rats. Mol Imaging Biol 2017; 19:736-745. [PMID: 28083825 PMCID: PMC5574958 DOI: 10.1007/s11307-016-1040-z] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
PURPOSE Many neurological conditions result in the overexpression of the translocator protein 18 kDa (TSPO), today recognized as a biomarker for microglial activation and neuroinflammation imaging. The pyrazolo[1,5-a]pyrimidine acetamides are a particularly attractive class of TSPO-specific ligands, prompting the development of several positron emission tomography (PET) radiotracers. This includes F-DPA, a recently reported fluorinated ligand (K i = 1.7 nM), wherein the fluorine atom is directly linked to the phenyl moiety without the presence of an alkyl or alkoxy spacer chain. Reported here is the preparation of [18F]F-DPA using [18F]Selectfluor bis(triflate) and the preliminary evaluation of [18F]F-DPA in healthy rats. Its metabolic profile and biodistribution in rats are compared with that of [18F]DPA-714, a closely related structure. PROCEDURES [18F]F-DPA was synthesized by electrophilic fluorination using [18F]Selectfluor bis(triflate), [18F]DPA-714 was synthesized by conventional nucleophilic fluorination. The biodistribution of both radiotracers was compared in Sprague Dawley rats. Radiometabolites of both radiotracers in plasma and brain homogenates were analyzed by radioTLC. RESULTS The radiochemical yield of [18F]F-DPA was 15 ± 3 % and the specific activity was 7.8 ± 0.4 GBq/μmol. The radiochemical purity exceeded 99 %. The in vivo time activity curves of [18F]F-DPA demonstrate rapid entry into the brain and a concentration equilibrium at 20-30 min after injection. The metabolic profiles at 90 min after radiotracer injection in the plasma show that unchanged [18F]F-DPA and [18F]DPA-714 account for 28.3 ± 6.4 and 11.1 ± 2.6 % of the remaining radioactivity, respectively. In the brain, unchanged [18F]F-DPA accounts for 93.5 ± 2.8 % of the radioactivity; whereas for [18F]DPA-714, this value is 53.6 ± 1.6 %. CONCLUSIONS [18F]Selectfluor bis(triflate) was successfully used to label F-DPA with fluorine-18. The labeling position on the aromatic moiety imparts a higher stability compared to [18F]DPA-714 with regard to in vivo metabolism. [18F]F-DPA is a promising new radiotracer and warrants further investigation in animal models of disease.
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Affiliation(s)
- Thomas Keller
- Radiopharmaceutical Chemistry Laboratory, Turku PET Centre, University of Turku, Turku, Finland
| | - Anna Krzyczmonik
- Radiopharmaceutical Chemistry Laboratory, Turku PET Centre, University of Turku, Turku, Finland
| | - Sarita Forsback
- Radiopharmaceutical Chemistry Laboratory, Turku PET Centre, University of Turku, Turku, Finland
- Department of Chemistry, University of Turku, Turku, Finland
| | - Francisco R López Picón
- PET Preclinical Imaging Laboratory, Turku PET Centre, University of Turku, Turku, Finland
- MediCity Research Laboratory, University of Turku, Turku, Finland
| | - Anna K Kirjavainen
- Radiopharmaceutical Chemistry Laboratory, Turku PET Centre, University of Turku, Turku, Finland
| | - Jatta Takkinen
- PET Preclinical Imaging Laboratory, Turku PET Centre, University of Turku, Turku, Finland
- MediCity Research Laboratory, University of Turku, Turku, Finland
| | - Johan Rajander
- Accelerator Laboratory, Turku PET Centre, Åbo Akademi University, Turku, Finland
| | - Fanny Cacheux
- CEA, I2BM, Service Hospitalier Frédéric Joliot, Orsay, France
| | | | - Frédéric Dollé
- CEA, I2BM, Service Hospitalier Frédéric Joliot, Orsay, France
| | - Juha O Rinne
- Turku PET Centre, Division of Clinical Neurosciences, Turku University Hospital, Turku, Finland
| | - Merja Haaparanta-Solin
- PET Preclinical Imaging Laboratory, Turku PET Centre, University of Turku, Turku, Finland
- MediCity Research Laboratory, University of Turku, Turku, Finland
| | - Olof Solin
- Radiopharmaceutical Chemistry Laboratory, Turku PET Centre, University of Turku, Turku, Finland.
- Department of Chemistry, University of Turku, Turku, Finland.
- Accelerator Laboratory, Turku PET Centre, Åbo Akademi University, Turku, Finland.
- Turku PET Centre, University of Turku, Kiinamyllynkatu 4-8, 20520, Turku, Finland.
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Differential effects of the 18-kDa translocator protein (TSPO) ligand etifoxine on steroidogenesis in rat brain, plasma and steroidogenic glands: Pharmacodynamic studies. Psychoneuroendocrinology 2017; 83:122-134. [PMID: 28609670 DOI: 10.1016/j.psyneuen.2017.05.022] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/17/2017] [Revised: 05/21/2017] [Accepted: 05/23/2017] [Indexed: 11/20/2022]
Abstract
Etifoxine is indicated in humans for treating anxiety. In rodents, besides its anxiolytic-like properties, it has recently shown neuroprotective and neuroregenerative activities. It acts by enhancing GABAA receptor function and by stimulating acute steroid biosynthesis via the activation of the 18-kDa translocator protein. However, the regulatory action of etifoxine on steroid production is not well characterized. In this work, we performed dose-response, acute and chronic time-course experiments on the effects of intraperitoneal injections of etifoxine on steroid levels in adult male rat brain and plasma analyzed by gas chromatography-mass spectrometry. Concentrations of pregnenolone, progesterone and its 5α-reduced metabolites were significantly increased in both tissues in response to 25 and 50mg/kg of etifoxine, as compared with vehicle controls, and reached maximal values at 0.5-1h post-injection. Daily injections of etifoxine (50mg/kg, 15days) kept them increased at day 15. Comparisons between steroidogenic tissues revealed that 1h after 50mg/kg of etifoxine treatment, levels of pregnenolone, progesterone and corticosterone were highest in adrenal glands and markedly increased together with their reduced metabolites. They were also increased by etifoxine in brain and plasma, but not in testis except for corticosterone and its metabolites. In contrast, testosterone level was significantly decreased in testis while with its 5α-reduced metabolites, it was unchanged in brain. Results demonstrate that the modulation of steroid concentrations by etifoxine is dependent on the type of steroid and on the steroidogenic organ. They further suggest that adrenal steroids upregulated by etifoxine make an important contribution to the steroids present in brain. This work provides a precise and complete view of steroids regulated by etifoxine that could be useful in therapeutic research.
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Gatliff J, East DA, Singh A, Alvarez MS, Frison M, Matic I, Ferraina C, Sampson N, Turkheimer F, Campanella M. A role for TSPO in mitochondrial Ca 2+ homeostasis and redox stress signaling. Cell Death Dis 2017; 8:e2896. [PMID: 28640253 PMCID: PMC5520880 DOI: 10.1038/cddis.2017.186] [Citation(s) in RCA: 66] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Revised: 03/08/2017] [Accepted: 03/23/2017] [Indexed: 12/20/2022]
Abstract
The 18 kDa translocator protein TSPO localizes on the outer mitochondrial membrane (OMM). Systematically overexpressed at sites of neuroinflammation it is adopted as a biomarker of brain conditions. TSPO inhibits the autophagic removal of mitochondria by limiting PARK2-mediated mitochondrial ubiquitination via a peri-organelle accumulation of reactive oxygen species (ROS). Here we describe that TSPO deregulates mitochondrial Ca2+ signaling leading to a parallel increase in the cytosolic Ca2+ pools that activate the Ca2+-dependent NADPH oxidase (NOX) thereby increasing ROS. The inhibition of mitochondrial Ca2+ uptake by TSPO is a consequence of the phosphorylation of the voltage-dependent anion channel (VDAC1) by the protein kinase A (PKA), which is recruited to the mitochondria, in complex with the Acyl-CoA binding domain containing 3 (ACBD3). Notably, the neurotransmitter glutamate, which contributes neuronal toxicity in age-dependent conditions, triggers this TSPO-dependent mechanism of cell signaling leading to cellular demise. TSPO is therefore proposed as a novel OMM-based pathway to control intracellular Ca2+ dynamics and redox transients in neuronal cytotoxicity.
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Affiliation(s)
- Jemma Gatliff
- Department of Comparative Biomedical Sciences, The Royal Veterinary College, University of London, Royal College Street, London NW1 0TU, UK
| | - Daniel A East
- Department of Comparative Biomedical Sciences, The Royal Veterinary College, University of London, Royal College Street, London NW1 0TU, UK
- Regina Elena-National Cancer Institute, 00144 Rome, Italy
| | - Aarti Singh
- Department of Comparative Biomedical Sciences, The Royal Veterinary College, University of London, Royal College Street, London NW1 0TU, UK
| | - Maria Soledad Alvarez
- Department of Comparative Biomedical Sciences, The Royal Veterinary College, University of London, Royal College Street, London NW1 0TU, UK
| | - Michele Frison
- Department of Comparative Biomedical Sciences, The Royal Veterinary College, University of London, Royal College Street, London NW1 0TU, UK
- Department of Neuroimaging, Institute of Psychiatry, King's College London, London, UK
| | - Ivana Matic
- Department of Biology, University of Rome ‘TorVergata’, 00133 Rome, Italy
| | - Caterina Ferraina
- Regina Elena-National Cancer Institute, 00144 Rome, Italy
- Department of Biology, University of Rome ‘TorVergata’, 00133 Rome, Italy
| | - Natalie Sampson
- Division of Experimental Urology, Medical University of Innsbruck, A6020 Innsbruck, Austria
| | - Federico Turkheimer
- Department of Neuroimaging, Institute of Psychiatry, King's College London, London, UK
| | - Michelangelo Campanella
- Department of Comparative Biomedical Sciences, The Royal Veterinary College, University of London, Royal College Street, London NW1 0TU, UK
- Department of Biology, University of Rome ‘TorVergata’, 00133 Rome, Italy
- University College London Consortium for Mitochondrial Research, Gower Street, WC1E 6BT London, UK
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