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Barichello T, Simões LR, Collodel A, Giridharan VV, Dal-Pizzol F, Macedo D, Quevedo J. The translocator protein (18 kDa) and its role in neuropsychiatric disorders. Neurosci Biobehav Rev 2017; 83:183-199. [DOI: 10.1016/j.neubiorev.2017.10.010] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Revised: 09/20/2017] [Accepted: 10/10/2017] [Indexed: 02/08/2023]
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Regulation of Mitochondrial, Cellular, and Organismal Functions by TSPO. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2017; 82:103-136. [PMID: 29413517 DOI: 10.1016/bs.apha.2017.09.004] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
In 1999, the enigma of the 18kDa mitochondrial translocator protein (TSPO), also known as the peripheral-type benzodiazepine receptor, was the seeming disparity of the many functions attributed to TSPO, ranging from the potential of TSPO acting as a housekeeping gene at molecular biological levels to adaptations to stress, and even involvement in higher emotional and cognitive functioning, such as anxiety and depression. In the years since then, knowledge regarding the many functions modulated by TSPO has expanded, and understanding has deepened. In addition, new functions could be firmly associated with TSPO, such as regulation of programmed cell death and modulation of gene expression. Interestingly, control by the mitochondrial TSPO over both of these life and death functions appears to include Ca++ homeostasis, generation of reactive oxygen species (ROS), and ATP production. Other mitochondrial functions under TSPO control are considered to be steroidogenesis and tetrapyrrole metabolism. As TSPO effects on gene expression and on programmed cell death can be related to the wide range of functions that can be associated with TSPO, several of these five elements of Ca++, ROS, ATP, steroids, and tetrapyrroles may indeed form the basis of TSPO's capability to operate as a multifunctional housekeeping gene to maintain homeostasis of the cell and of the whole multicellular organism.
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Leva G, Klein C, Benyounes J, Hallé F, Bihel F, Collongues N, De Seze J, Mensah-Nyagan AG, Patte-Mensah C. The translocator protein ligand XBD173 improves clinical symptoms and neuropathological markers in the SJL/J mouse model of multiple sclerosis. Biochim Biophys Acta Mol Basis Dis 2017; 1863:3016-3027. [PMID: 28899788 DOI: 10.1016/j.bbadis.2017.09.007] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2017] [Revised: 09/04/2017] [Accepted: 09/08/2017] [Indexed: 12/18/2022]
Abstract
Multiple sclerosis (MS) is a severe autoimmune disease characterized by inflammatory, demyelinating and neurodegenerative components causing motor, sensory, visual and/or cognitive symptoms. The relapsing-remitting MS affecting 85% of patients is reliably mimicked by the proteolipid-protein (PLP)-induced experimental autoimmune encephalomyelitis (EAE) SJL/J-mouse model. Significant progress was made for MS treatment but the development of effective therapies devoid of severe side-effects remains a great challenge. Here, we combine clinical, behavioral, histopathological, biochemical and molecular approaches to demonstrate that low and well tolerated doses (10-20mg/kg) of TSPO ligand XBD173 (Emapunil) efficiently ameliorate clinical signs and neuropathology of PLP-EAE mice. In addition to the conventional clinical scoring of symptoms, we applied the robust behavioral Catwalk-method to confirm that XBD173 (10mg/kg) increases the maximum contact area parameter at EAE-disease peak, indicating an improvement/recovery of motor functions. Consistently, histopathological studies coupled with microscope-cellSens quantification and RT-qPCR analyzes showed that XBD173 prevented demyelination by restoring normal protein and mRNA levels of myelin basic protein that was significantly repressed in PLP-EAE mice spinal cord and brain. Interestingly, ELISA-based measurement revealed that XBD173 increased allopregnanolone concentrations in PLP-EAE mice spinal and brain tissues. Furthermore, flow cytometry assessment demonstrated that XBD173 therapy decreased serum level of pro-inflammatory cytokines, including interleukin-17A, Interleukin-6 and tumor-necrosis-factor alpha in PLP-EAE mice. As the optimal XBD173 dosing exerting the maximal beneficial action in EAE mice is the lower 10mg/kg dose, the paper opens interesting perspectives for the development of efficient and safe therapies against MS with slight or no side-effects.
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Affiliation(s)
- Géraldine Leva
- Biopathologie de la Myéline, Neuroprotection et Stratégies Thérapeutiques, INSERM U1119, Fédération de Médecine Translationnelle de Strasbourg (FMTS), Université de Strasbourg, Bâtiment 3 de la Faculté de Médecine, 11 rue Humann, 67 000 Strasbourg, France
| | - Christian Klein
- Biopathologie de la Myéline, Neuroprotection et Stratégies Thérapeutiques, INSERM U1119, Fédération de Médecine Translationnelle de Strasbourg (FMTS), Université de Strasbourg, Bâtiment 3 de la Faculté de Médecine, 11 rue Humann, 67 000 Strasbourg, France
| | - Jérémie Benyounes
- Biopathologie de la Myéline, Neuroprotection et Stratégies Thérapeutiques, INSERM U1119, Fédération de Médecine Translationnelle de Strasbourg (FMTS), Université de Strasbourg, Bâtiment 3 de la Faculté de Médecine, 11 rue Humann, 67 000 Strasbourg, France
| | - François Hallé
- Laboratoire d'innovation thérapeutique (LIT) CNRS UMR 7200, Faculté de Pharmacie de Strasbourg, 74 route du Rhin, CS 60024, 67401 Illkirch Cedex, France
| | - Frédéric Bihel
- Laboratoire d'innovation thérapeutique (LIT) CNRS UMR 7200, Faculté de Pharmacie de Strasbourg, 74 route du Rhin, CS 60024, 67401 Illkirch Cedex, France
| | - Nicolas Collongues
- Biopathologie de la Myéline, Neuroprotection et Stratégies Thérapeutiques, INSERM U1119, Fédération de Médecine Translationnelle de Strasbourg (FMTS), Université de Strasbourg, Bâtiment 3 de la Faculté de Médecine, 11 rue Humann, 67 000 Strasbourg, France
| | - Jérôme De Seze
- Biopathologie de la Myéline, Neuroprotection et Stratégies Thérapeutiques, INSERM U1119, Fédération de Médecine Translationnelle de Strasbourg (FMTS), Université de Strasbourg, Bâtiment 3 de la Faculté de Médecine, 11 rue Humann, 67 000 Strasbourg, France
| | - Ayikoe-Guy Mensah-Nyagan
- Biopathologie de la Myéline, Neuroprotection et Stratégies Thérapeutiques, INSERM U1119, Fédération de Médecine Translationnelle de Strasbourg (FMTS), Université de Strasbourg, Bâtiment 3 de la Faculté de Médecine, 11 rue Humann, 67 000 Strasbourg, France.
| | - Christine Patte-Mensah
- Biopathologie de la Myéline, Neuroprotection et Stratégies Thérapeutiques, INSERM U1119, Fédération de Médecine Translationnelle de Strasbourg (FMTS), Université de Strasbourg, Bâtiment 3 de la Faculté de Médecine, 11 rue Humann, 67 000 Strasbourg, France.
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Manchester KR, Lomas EC, Waters L, Dempsey FC, Maskell PD. The emergence of new psychoactive substance (NPS) benzodiazepines: A review. Drug Test Anal 2017; 10:37-53. [DOI: 10.1002/dta.2211] [Citation(s) in RCA: 63] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2017] [Revised: 04/11/2017] [Accepted: 04/26/2017] [Indexed: 01/17/2023]
Affiliation(s)
- Kieran R. Manchester
- School of Applied Sciences, Queensgate Campus; University of Huddersfield; Huddersfield UK
| | - Emma C. Lomas
- School of Applied Sciences, Queensgate Campus; University of Huddersfield; Huddersfield UK
| | - Laura Waters
- School of Applied Sciences, Queensgate Campus; University of Huddersfield; Huddersfield UK
| | - Fiona C. Dempsey
- MedAnnex Ltd, 1 Summerhall Place; Techcube 3.5; Edinburgh EH9 1PL UK
| | - Peter D. Maskell
- School of Science, Engineering and Technology; Abertay University; Dundee UK
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Overexpression of the 18 kDa translocator protein (TSPO) in the hippocampal dentate gyrus produced anxiolytic and antidepressant-like behavioural effects. Neuropharmacology 2017; 125:117-128. [PMID: 28655607 DOI: 10.1016/j.neuropharm.2017.06.023] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Revised: 06/18/2017] [Accepted: 06/22/2017] [Indexed: 12/22/2022]
Abstract
The 18 kDa translocator protein (TSPO) is a five transmembrane domain protein that plays a crucial role in neurosteroid (e.g., allopregnanolone) synthesis by promoting the transport of cholesterol to the inner mitochondrial membrane. This protein is predominantly expressed in steroid-synthesizing tissues, including the central and peripheral nervous system, affecting stress-related disorders such as anxiety and depression. Recent studies have focused on the hippocampal dentate gyrus, which is very important for involvement of anxiety and depression. However, the exact role that TSPO plays in the pathophysiology of anxiety and depression and the involvement of the hippocampal dentate gyrus in regulating these behavioural effects remain elusive. This study used the lentiviral vectors mediating TPSO overexpression to assess the effects of TPSO overexpression in the hippocampal dentate gyrus on anxiolytic and antidepressant-like behavioural effects in mice. The expression of TSPO and the concentration of allopregnanolone in hippocampus tissues (3 mm in diameter around the injection site on both sides) were measured by Western blot and ELISA, respectively. The results indicated that microinjection of the LV-TSPO resulted in a significant increase in TSPO expression and allopregnanolone concentration in the hippocampus. Moreover, TSPO overexpression of the mouse hippocampal dentate gyrus generated significant anxiolytic and antidepressant-like behavioural effects in a series of behavioural models. These effects were completely blocked by the TSPO antagonist PK11195 (3 mg/kg, intraperitoneally) and the 5α-reductase inhibitor finasteride (5 mg/kg,intraperitoneally). Meanwhile, the increased allopregnanolone was also reversed by PK11195 and finasteride. In addition, neither PK11195 nor finasteride had an effect on the expression of TSPO. Overall, our results are the first to suggest that the overexpression of TSPO in the hippocampal dentate gyrus produced anxiolytic and antidepressant-like behavioural effects that are partially mediated by downstream allopregnanolone biosynthesis. Our results suggest that TSPO would be a potential anxiolytic and antidepressant therapeutic target.
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Elkamhawy A, Park JE, Hassan AH, Pae AN, Lee J, Park BG, Paik S, Do J, Park JH, Park KD, Moon B, Park WK, Cho H, Jeong DY, Roh EJ. Design, synthesis, biological evaluation and molecular modelling of 2-(2-aryloxyphenyl)-1,4-dihydroisoquinolin-3(2 H )-ones: A novel class of TSPO ligands modulating amyloid-β-induced mPTP opening. Eur J Pharm Sci 2017; 104:366-381. [DOI: 10.1016/j.ejps.2017.04.015] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2016] [Revised: 04/18/2017] [Accepted: 04/19/2017] [Indexed: 12/22/2022]
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Coughlin JM, Wang Y, Minn I, Bienko N, Ambinder EB, Xu X, Peters ME, Dougherty JW, Vranesic M, Koo SM, Ahn HH, Lee M, Cottrell C, Sair HI, Sawa A, Munro CA, Nowinski CJ, Dannals RF, Lyketsos CG, Kassiou M, Smith G, Caffo B, Mori S, Guilarte TR, Pomper MG. Imaging of Glial Cell Activation and White Matter Integrity in Brains of Active and Recently Retired National Football League Players. JAMA Neurol 2017; 74:67-74. [PMID: 27893897 DOI: 10.1001/jamaneurol.2016.3764] [Citation(s) in RCA: 121] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Importance Microglia, the resident immune cells of the central nervous system, play an important role in the brain's response to injury and neurodegenerative processes. It has been proposed that prolonged microglial activation occurs after single and repeated traumatic brain injury, possibly through sports-related concussive and subconcussive injuries. Limited in vivo brain imaging studies months to years after individuals experience a single moderate to severe traumatic brain injury suggest widespread persistent microglial activation, but there has been little study of persistent glial cell activity in brains of athletes with sports-related traumatic brain injury. Objective To measure translocator protein 18 kDa (TSPO), a marker of activated glial cell response, in a cohort of National Football League (NFL) players and control participants, and to report measures of white matter integrity. Design, Setting, and Participants This cross-sectional, case-control study included young active (n = 4) or former (n = 10) NFL players recruited from across the United States, and 16 age-, sex-, highest educational level-, and body mass index-matched control participants. This study was conducted at an academic research institution in Baltimore, Maryland, from January 29, 2015, to February 18, 2016. Main Outcomes and Measures Positron emission tomography-based regional measures of TSPO using [11C]DPA-713, diffusion tensor imaging measures of regional white matter integrity, regional volumes on structural magnetic resonance imaging, and neuropsychological performance. Results The mean (SD) ages of the 14 NFL participants and 16 control participants were 31.3 (6.1) years and 27.6 (4.9) years, respectively. Players reported a mean (SD) of 7.0 (6.4) years (range, 1-21 years) since the last self-reported concussion. Using [11C]DPA-713 positron emission tomographic data from 12 active or former NFL players and 11 matched control participants, the NFL players showed higher total distribution volume in 8 of the 12 brain regions examined (P < .004). We also observed limited change in white matter fractional anisotropy and mean diffusivity in 13 players compared with 15 control participants. In contrast, these young players did not differ from control participants in regional brain volumes or in neuropsychological performance. Conclusions and Relevance The results suggest that localized brain injury and repair, indicated by higher TSPO signal and white matter changes, may be associated with NFL play. Further study is needed to confirm these findings and to determine whether TSPO signal and white matter changes in young NFL athletes are related to later onset of neuropsychiatric symptoms.
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Affiliation(s)
- Jennifer M Coughlin
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins Medical Institutions, Baltimore, Maryland2Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutions, Baltimore, Maryland
| | - Yuchuan Wang
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutions, Baltimore, Maryland
| | - Il Minn
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutions, Baltimore, Maryland
| | - Nicholas Bienko
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins Medical Institutions, Baltimore, Maryland
| | - Emily B Ambinder
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutions, Baltimore, Maryland
| | - Xin Xu
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutions, Baltimore, Maryland
| | - Matthew E Peters
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins Medical Institutions, Baltimore, Maryland
| | - John W Dougherty
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins Medical Institutions, Baltimore, Maryland
| | - Melin Vranesic
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutions, Baltimore, Maryland
| | - Soo Min Koo
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutions, Baltimore, Maryland
| | - Hye-Hyun Ahn
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutions, Baltimore, Maryland
| | - Merton Lee
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutions, Baltimore, Maryland
| | - Chris Cottrell
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins Medical Institutions, Baltimore, Maryland
| | - Haris I Sair
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutions, Baltimore, Maryland
| | - Akira Sawa
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins Medical Institutions, Baltimore, Maryland
| | - Cynthia A Munro
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins Medical Institutions, Baltimore, Maryland3Department of Neurology, Johns Hopkins Medical Institutions, Baltimore, Maryland
| | - Christopher J Nowinski
- Concussion Legacy Foundation, Waltham, Massachusetts5Alzheimer's Disease and CTE Center, Boston University School of Medicine, Boston, Massachusetts
| | - Robert F Dannals
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutions, Baltimore, Maryland
| | - Constantine G Lyketsos
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins Medical Institutions, Baltimore, Maryland
| | - Michael Kassiou
- School of Chemistry, University of Sydney, New South Wales, Australia7Discipline of Medical Radiation Sciences, University of Sydney, Sydney, New South Wales, Australia
| | - Gwenn Smith
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins Medical Institutions, Baltimore, Maryland
| | - Brian Caffo
- Department of Biostatistics, Johns Hopkins Medical Institutions, Baltimore, Maryland
| | - Susumu Mori
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutions, Baltimore, Maryland
| | - Tomas R Guilarte
- Department of Environmental and Occupational Health, Florida International University, Miami10Program in Cognitive Neuroscience and Imaging, Florida International University, Miami
| | - Martin G Pomper
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins Medical Institutions, Baltimore, Maryland2Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutions, Baltimore, Maryland
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Humble SR. Mitochondrial dysfunction in an animal model of diabetic neuropathy is associated with a reduction of neurosteroid synthesis. F1000Res 2017; 6:506. [PMID: 29623189 PMCID: PMC5861509 DOI: 10.12688/f1000research.11056.1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 03/01/2018] [Indexed: 10/05/2023] Open
Abstract
Background: Recent work in a model of diabetic neuropathy revealed that layer 2/3 cortical pyramidal neurones of the pain pathway exhibited reduced endogenous neurosteroid modulation of the GABA AR and exogenously applied neurosteroids had an exaggerated impact. It is postulated that this is related to reduced precursor synthesis, due to mitochondrial dysfunction in diabetic neuropathy. Benzodiazepines are also known to activate neurosteroidogenesis by binding to mitochondrial translocator protein (TSPO). This study explored the differential effect of diazepam on GABA AR modulation via neurosteroidogenesis in diabetic and wild type (WT) mice. Methods: Whole-cell patch-clamp technique was used on slices of neural tissue. Electrophysiological recordings were obtained from layer 2/3 cortical pyramidal neurons of the pain pathway from mice with type-II diabetic neuropathy ( ob/ob) and WT controls aged 60-80 days. Results: There was a key difference in the response of the WT and ob/ob cortical neurons to simultaneous incubation with diazepam and flumazenil. In contrast, diazepam and the 5a-reductase inhibitor finasteride, individually or in combination, produced the same response in both strains. Conclusions: The exaggerated effect of diazepam on GABAergic inhibitory tone in the ob/ob, despite the presence of the GABA AR benzodiazepine antagonist flumazenil is likely observed due to physiological upregulation of key neurosteroidogenic enzymes in response to the reduced pregnenolone synthesis by the mitochondria. By increasing pregnenolone via TSPO activation, it is possible to promote enhanced neurosteroidogenesis and increase GABAergic inhibitory tone via an alternate route. In diabetic neuropathy, mitochondrial dysfunction may play an important role. Enhancing the GABAergic neurosteroid tone could be of potential therapeutic benefit.
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Affiliation(s)
- Stephen R. Humble
- Department of Anaesthetics and Pain Management, Charing Cross Hospital, Imperial College NHS Healthcare Trust London, London, W6 8RF, UK
- Imperial College London, Charing Cross Campus, Margravine Road, London, W6 8RP, UK
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Humble SR. Mitochondrial dysfunction in an animal model of diabetic neuropathy is associated with a reduction of neurosteroid synthesis. F1000Res 2017; 6:506. [PMID: 29623189 PMCID: PMC5861509 DOI: 10.12688/f1000research.11056.2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 03/01/2018] [Indexed: 01/28/2023] Open
Abstract
Background: Recent work in a model of diabetic neuropathy revealed that layer 2/3 cortical pyramidal neurones of the pain pathway exhibited reduced endogenous neurosteroid modulation of the GABA AR and exogenously applied neurosteroids had an exaggerated impact. It is postulated that this is related to reduced precursor synthesis, due to mitochondrial dysfunction in diabetic neuropathy. Benzodiazepines are also known to activate neurosteroidogenesis by binding to mitochondrial translocator protein (TSPO). This study explored the differential effect of diazepam on GABA AR modulation via neurosteroidogenesis in diabetic and wild type (WT) mice. Methods: Whole-cell patch-clamp technique was used on slices of neural tissue. Electrophysiological recordings were obtained from layer 2/3 cortical pyramidal neurons of the pain pathway from mice with type-II diabetic neuropathy ( ob/ob) and WT controls aged 60-80 days. Results: There was a key difference in the response of the WT and ob/ob cortical neurons to simultaneous incubation with diazepam and flumazenil. In contrast, diazepam and the 5a-reductase inhibitor finasteride, individually or in combination, produced the same response in both strains. Conclusions: The exaggerated effect of diazepam on GABAergic inhibitory tone in the ob/ob, despite the presence of the GABA AR benzodiazepine antagonist flumazenil is likely observed due to physiological upregulation of key neurosteroidogenic enzymes in response to the reduced pregnenolone synthesis by the mitochondria. By increasing pregnenolone via TSPO activation, it is possible to promote enhanced neurosteroidogenesis and increase GABAergic inhibitory tone via an alternate route. In diabetic neuropathy, mitochondrial dysfunction may play an important role. Enhancing the GABAergic neurosteroid tone could be of potential therapeutic benefit.
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Affiliation(s)
- Stephen R Humble
- Department of Anaesthetics and Pain Management, Charing Cross Hospital, Imperial College NHS Healthcare Trust London, London, W6 8RF, UK.,Imperial College London, Charing Cross Campus, Margravine Road, London, W6 8RP, UK
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Baez E, Guio-Vega GP, Echeverria V, Sandoval-Rueda DA, Barreto GE. 4'-Chlorodiazepam Protects Mitochondria in T98G Astrocyte Cell Line from Glucose Deprivation. Neurotox Res 2017; 32:163-171. [PMID: 28405935 DOI: 10.1007/s12640-017-9733-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Revised: 03/30/2017] [Accepted: 04/04/2017] [Indexed: 01/12/2023]
Abstract
The translocator protein (TSPO), formerly known as the peripheral-type benzodiazepine receptor (PBR), is considered an important regulator of steroidogenesis and a potential therapeutic target in neurological disorders. Previous evidence suggests that TSPO ligands can protect cells during injury and prevent apoptosis in central nervous system (CNS) cells. However, its actions on astrocytic cells under metabolic injury are not well understood. In this study, we explored whether 4'-chlorodiazepam (Ro5-4864), a TSPO ligand, might protect astrocyte mitochondria under glucose deprivation. Our results showed that 4'-chlorodiazepam preserved cell viability and reduced nuclear fragmentation in glucose-deprived cells. These effects were accompanied by a reduced production of free radicals and maintenance of mitochondrial functions in cells treated with 4'-chlorodiazepam. Finally, our findings suggest that TSPO might be involved in reducing oxidative stress by preserving mitochondrial functions in astrocytic cells exposed to glucose withdrawal.
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Affiliation(s)
- Eliana Baez
- Departamento de Nutrición y Bioquímica, Facultad de Ciencias, Pontificia Universidad Javeriana, Bogotá D.C., Colombia
| | - Gina Paola Guio-Vega
- Departamento de Nutrición y Bioquímica, Facultad de Ciencias, Pontificia Universidad Javeriana, Bogotá D.C., Colombia
| | | | - Daniel Andres Sandoval-Rueda
- Departamento de Nutrición y Bioquímica, Facultad de Ciencias, Pontificia Universidad Javeriana, Bogotá D.C., Colombia
| | - George E Barreto
- Departamento de Nutrición y Bioquímica, Facultad de Ciencias, Pontificia Universidad Javeriana, Bogotá D.C., Colombia. .,Instituto de Ciencias Biomédicas, Universidad Autónoma de Chile, Santiago, Chile.
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Molecular Biology Digest of Cell Mitophagy. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2017; 332:233-258. [PMID: 28526134 DOI: 10.1016/bs.ircmb.2016.12.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The homeostasis of eukaryotic cells relies on efficient mitochondrial function. The control of mitochondrial quality is framed by the combination of distinct but interdependent mechanisms spanning biogenesis, regulation of dynamic network, and finely tuned degradation either through ubiquitin-proteasome system or autophagy (mitophagy). There is continuous evolution on the pathways orchestrating the mitochondrial response to stress signals and the organelle adaptation to quality control during acute and subtle dysfunctions. Notably, it remains indeed ill-defined whether active mitophagy leads to cell survival or death by defective mitochondrial degradation. Above all, uncharted is whether and how pharmacologically tackle these mechanisms may lead to conceive novel therapeutic strategies for treating conditions associated with the defective mitochondria. Here, we attempt to provide a chronological and comprehensive overview of the determining discoveries, which have led to the current knowledge of mitophagy.
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Li XM, Meng J, Li LT, Guo T, Yang LK, Shi QX, Li XB, Chen Y, Yang Q, Zhao JN. Effect of ZBD-2 on chronic pain, depressive-like behaviors, and recovery of motor function following spinal cord injury in mice. Behav Brain Res 2017; 322:92-99. [PMID: 28108322 PMCID: PMC5339413 DOI: 10.1016/j.bbr.2017.01.025] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Revised: 01/09/2017] [Accepted: 01/12/2017] [Indexed: 02/06/2023]
Abstract
ZBD-2 significantly attenuated the symptoms of chronic SCI-pain and pain-induced depressive-like behaviors. ZBD-2 inhibited the decreases in the expression of synaptic plasticity-related signaling proteins. ZBD-2 reversed chronic, SCI-induced gliocyte activation at the lesion site.
In addition to debilitating sensory and motor deficits, patients with spinal cord injury (SCI) may experience chronic hyperpathic pain (SCI-pain). Recent studies have revealed that translocator protein (TSPO) is involved in repairing neural cells as well as reducing anxiety and depression. However, the role of TSPO in SCI-pain and pain-induced depression remains unknown. The present study aimed to determine the effects of a new TSPO ligand, ZBD-2, on SCI-pain and consequent pain-induced depressive-like behaviors in mice. Treatment with ZBD-2 at either dose significantly attenuated the symptoms of chronic SCI-pain and pain-induced depressive-like behaviors. ZBD-2 reversed SCI-induced elevation of serum corticosterone levels, an index of hyper-activation of the hypothalamic–pituitary–adrenal (HPA) axis. Additionally, administration of ZBD-2 inhibited decreases in the expression of synaptic plasticity-related signaling proteins, including brain-derived neurotrophic factor (BDNF) and cyclic AMP-responsive element binding protein (CREB). Moreover, ZBD-2 administration reversed chronic, SCI-induced gliocyte activation at the lesion site. Therefore, ZBD-2 may improve chronic SCI-pain and pain-induced depressive-like behaviors via suppression of gliocyte activation and restoration of the synaptic plasticity-related signaling systems.
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Affiliation(s)
- Xiao-Ming Li
- Department of Orthopedics, Jinling Hospital, Clinical School of Nanjing, Second Military Medical University, Nanjing, 210002, China
| | - Jia Meng
- Department of Orthopedics, Jinling Hospital, Clinical School of Nanjing, Second Military Medical University, Nanjing, 210002, China
| | - Lin Tao Li
- Department of Orthopedics, Jinling Hospital, Clinical School of Nanjing, Second Military Medical University, Nanjing, 210002, China
| | - Ting Guo
- Department of Orthopedics, Jinling Hospital, Clinical School of Nanjing, Second Military Medical University, Nanjing, 210002, China
| | - Liu-Kun Yang
- Department of Pharmacology, School of Pharmacy, Fourth Military Medical University, Xi'an, 710032, China
| | - Qi-Xin Shi
- Department of Pharmacology, School of Pharmacy, Fourth Military Medical University, Xi'an, 710032, China
| | - Xu-Bo Li
- Department of Pharmacology, School of Pharmacy, Fourth Military Medical University, Xi'an, 710032, China
| | - Yong Chen
- Department of Orthopedics, Jinling Hospital, Clinical School of Nanjing, Second Military Medical University, Nanjing, 210002, China.
| | - Qi Yang
- Department of Pharmacology, School of Pharmacy, Fourth Military Medical University, Xi'an, 710032, China.
| | - Jian-Ning Zhao
- Department of Orthopedics, Jinling Hospital, Clinical School of Nanjing, Second Military Medical University, Nanjing, 210002, China.
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63
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Zhang X. Detergents: Friends not foes for high-performance membrane proteomics toward precision medicine. Proteomics 2016; 17. [PMID: 27633951 DOI: 10.1002/pmic.201600209] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2016] [Revised: 07/31/2016] [Accepted: 09/13/2016] [Indexed: 01/05/2023]
Abstract
Precision medicine, particularly therapeutics, emphasizes the atomic-precise, dynamic, and systems visualization of human membrane proteins and their endogenous modifiers. For years, bottom-up proteomics has grappled with removing and avoiding detergents, yet faltered at the therapeutic-pivotal membrane proteins, which have been tackled by classical approaches and are known for decades refractory to single-phase aqueous or organic denaturants. Hydrophobicity and aggregation commonly challenge tissue and cell lysates, biofluids, and enriched samples. Frequently, expected membrane proteins and peptides are not identified by shotgun bottom-up proteomics, let alone robust quantitation. This review argues the cause of this proteomic crisis is not detergents per se, but the choice of detergents. Recently, inclusion of compatible detergents for membrane protein extraction and digestion has revealed stark improvements in both quantitative and structural proteomics. This review analyzes detergent properties behind recent proteomic advances, and proposes that rational use of detergents may reconcile outstanding membrane proteomics dilemmas, enabling ultradeep coverage and minimal artifacts for robust protein and endogenous PTM measurements. The simplicity of detergent tools confers bottom-up membrane proteomics the sophistication toward precision medicine.
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Affiliation(s)
- Xi Zhang
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, MA, USA.,Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, USA
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64
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Feng L, Jensen P, Thomsen G, Dyssegaard A, Svarer C, Knudsen LV, Møller K, Thomsen C, Mikkelsen JD, Guilloteau D, Knudsen GM, Pinborg LH. The Variability of Translocator Protein Signal in Brain and Blood of Genotyped Healthy Humans Using In Vivo 123I-CLINDE SPECT Imaging: A Test–Retest Study. J Nucl Med 2016; 58:989-995. [DOI: 10.2967/jnumed.116.183202] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2016] [Accepted: 10/21/2016] [Indexed: 11/16/2022] Open
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65
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Evaluation of PET Imaging Performance of the TSPO Radioligand [18F]DPA-714 in Mouse and Rat Models of Cancer and Inflammation. Mol Imaging Biol 2016; 18:127-34. [PMID: 26194010 PMCID: PMC4722075 DOI: 10.1007/s11307-015-0877-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Purpose Many radioligands have been explored for imaging the 18-kDa translocator protein (TSPO), a diagnostic and therapeutic target for inflammation and cancer. Here, we investigated the TSPO radioligand [18F]DPA-714 for positron emission tomography (PET) imaging of cancer and inflammation. Procedures [18F]DPA-714 PET imaging was performed in 8 mouse and rat models of breast and brain cancer and 4 mouse and rat models of muscular and bowel inflammation. Results [18F]DPA-714 showed different uptake levels in healthy organs and malignant tissues of mice and rats. Although high and displaceable [18F]DPA-714 binding is observed ex vivo, TSPO-positive PET imaging of peripheral lesions of cancer and inflammation in mice did not show significant lesion-to-background signal ratios. Slower [18F]DPA-714 metabolism and muscle clearance in mice compared to rats may explain the elevated background signal in peripheral organs in this species. Conclusion Although TSPO is an evolutionary conserved protein, inter- and intra-species differences call for further exploration of the pharmacological parameters of TSPO radioligands. Electronic supplementary material The online version of this article (doi:10.1007/s11307-015-0877-x) contains supplementary material, which is available to authorized users.
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66
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Selvaraj V, Tu LN. Current status and future perspectives: TSPO in steroid neuroendocrinology. J Endocrinol 2016; 231:R1-R30. [PMID: 27422254 DOI: 10.1530/joe-16-0241] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/08/2016] [Accepted: 07/15/2016] [Indexed: 12/21/2022]
Abstract
The mitochondrial translocator protein (TSPO), previously known as the peripheral benzodiazepine receptor (PBR), has received significant attention both as a diagnostic biomarker and as a therapeutic target for different neuronal disease pathologies. Recently, its functional basis believed to be mediating mitochondrial cholesterol import for steroid hormone production has been refuted by studies examining both in vivo and in vitro genetic Tspo-deficient models. As a result, there now exists a fundamental gap in the understanding of TSPO function in the nervous system, and its putative pharmacology in neurosteroid production. In this review, we discuss several recent findings in steroidogenic cells that are in direct contradiction to previous studies, and necessitate a re-examination of the purported role for TSPO in de novo neurosteroid biosynthesis. We critically examine the pharmacological effects of different TSPO-binding drugs with particular focus on studies that measure neurosteroid levels. We highlight the basis of key misconceptions regarding TSPO that continue to pervade the literature, and the need for interpretation with caution to avoid negative impacts. We also summarize the emerging perspectives that point to new directions that need to be investigated for understanding the molecular function of TSPO, only after which the true potential of this therapeutic target in medicine may be realized.
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Affiliation(s)
- Vimal Selvaraj
- Department of Animal ScienceCornell University, Ithaca, New York, USA
| | - Lan N Tu
- Department of Animal ScienceCornell University, Ithaca, New York, USA
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67
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Simon-O'Brien E, Gauthier D, Riban V, Verleye M. Etifoxine improves sensorimotor deficits and reduces glial activation, neuronal degeneration, and neuroinflammation in a rat model of traumatic brain injury. J Neuroinflammation 2016; 13:203. [PMID: 27565146 PMCID: PMC5002207 DOI: 10.1186/s12974-016-0687-3] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Accepted: 08/18/2016] [Indexed: 12/14/2022] Open
Abstract
Background Traumatic brain injury (TBI) results in important neurological impairments which occur through a cascade of deleterious physiological events over time. There are currently no effective treatments to prevent these consequences. TBI is followed not only by an inflammatory response but also by a profound reorganization of the GABAergic system and a dysregulation of translocator protein 18 kDa (TSPO). Etifoxine is an anxiolytic compound that belongs to the benzoxazine family. It potentiates GABAergic neurotransmission, either through a positive allosteric effect or indirectly, involving the activation of TSPO that leads to an increase in neurosteroids synthesis. In several models of peripheral nerve injury, etifoxine has been demonstrated to display potent regenerative and anti-inflammatory properties and to promote functional recovery. Prior study also showed etifoxine efficacy in reducing brain edema in rats. In light of these positive results, we used a rat model of TBI to explore etifoxine treatment effects in a central nervous system injury, from functional outcomes to the underlying mechanisms. Methods Male Sprague-Dawley rats received contusion (n = 18) or sham (n = 19) injuries centered laterally to bregma over the left sensorimotor cortex. They were treated with etifoxine (50 mg/kg, i.p.) or its vehicle 30 min following injury and every day during 7 days. Rats underwent behavioral testing to assess sensorimotor function. In another experiment, injured rats (n = 10) or sham rats (n = 10) received etifoxine (EFX) (50 mg/kg, i.p.) or its vehicle 30 min post-surgery. Brains were then dissected for analysis of neuroinflammation markers, glial activation, and neuronal degeneration. Results Brain-injured rats exhibited significant sensorimotor function deficits compared to sham-injured rats in the bilateral tactile adhesive removal test, the beam walking test, and the limb-use asymmetry test. After 2 days of etifoxine treatment, behavioral impairments were significantly reduced. Etifoxine treatment reduced pro-inflammatory cytokines levels without affecting anti-inflammatory cytokines levels in injured rats, reduced macrophages and glial activation, and reduced neuronal degeneration. Conclusions Our results showed that post-injury treatment with etifoxine improved functional recovery and reduced neuroinflammation in a rat model of TBI. These findings suggest that etifoxine may have a therapeutic potential in the treatment of TBI.
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Affiliation(s)
| | - Delphine Gauthier
- Pharmacology Department, Biocodex, Chemin d'Armancourt, 60200, Compiègne, France
| | - Véronique Riban
- Pharmacology Department, Biocodex, Chemin d'Armancourt, 60200, Compiègne, France
| | - Marc Verleye
- Pharmacology Department, Biocodex, Chemin d'Armancourt, 60200, Compiègne, France
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TSPO PIGA Ligands Promote Neurosteroidogenesis and Human Astrocyte Well-Being. Int J Mol Sci 2016; 17:ijms17071028. [PMID: 27367681 PMCID: PMC4964404 DOI: 10.3390/ijms17071028] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Revised: 06/22/2016] [Accepted: 06/23/2016] [Indexed: 01/05/2023] Open
Abstract
The steroidogenic 18 kDa translocator protein (TSPO) is an emerging, attractive therapeutic tool for several pathological conditions of the nervous system. Here, 13 high affinity TSPO ligands belonging to our previously described N,N-dialkyl-2-phenylindol-3-ylglyoxylamide (PIGA) class were evaluated for their potential ability to affect the cellular Oxidative Metabolism Activity/Proliferation index, which is used as a measure of astrocyte well-being. The most active PIGA ligands were also assessed for steroidogenic activity in terms of pregnenolone production, and the values were related to the metabolic index in rat and human models. The results showed a positive correlation between the increase in the Oxidative Metabolism Activity/Proliferation index and the pharmacologically induced stimulation of steroidogenesis. The specific involvement of steroid molecules in mediating the metabolic effects of the PIGA ligands was demonstrated using aminoglutethimide, a specific inhibitor of the first step of steroid biosynthesis. The most promising steroidogenic PIGA ligands were the 2-naphthyl derivatives that showed a long residence time to the target, in agreement with our previous data. In conclusion, TSPO ligand-induced neurosteroidogenesis was involved in astrocyte well-being.
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69
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Tetrapyrroles as Endogenous TSPO Ligands in Eukaryotes and Prokaryotes: Comparisons with Synthetic Ligands. Int J Mol Sci 2016; 17:ijms17060880. [PMID: 27271616 PMCID: PMC4926414 DOI: 10.3390/ijms17060880] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2016] [Revised: 05/17/2016] [Accepted: 05/19/2016] [Indexed: 12/26/2022] Open
Abstract
The 18 kDa translocator protein (TSPO) is highly 0conserved in eukaryotes and prokaryotes. Since its discovery in 1977, numerous studies established the TSPO’s importance for life essential functions. For these studies, synthetic TSPO ligands typically are applied. Tetrapyrroles present endogenous ligands for the TSPO. Tetrapyrroles are also evolutionarily conserved and regulate multiple functions. TSPO and tetrapyrroles regulate each other. In animals TSPO-tetrapyrrole interactions range from effects on embryonic development to metabolism, programmed cell death, response to stress, injury and disease, and even to life span extension. In animals TSPOs are primarily located in mitochondria. In plants TSPOs are also present in plastids, the nuclear fraction, the endoplasmic reticulum, and Golgi stacks. This may contribute to translocation of tetrapyrrole intermediates across organelles’ membranes. As in animals, plant TSPO binds heme and protoporphyrin IX. TSPO-tetrapyrrole interactions in plants appear to relate to development as well as stress conditions, including salt tolerance, abscisic acid-induced stress, reactive oxygen species homeostasis, and finally cell death regulation. In bacteria, TSPO is important for switching from aerobic to anaerobic metabolism, including the regulation of photosynthesis. As in mitochondria, in bacteria TSPO is located in the outer membrane. TSPO-tetrapyrrole interactions may be part of the establishment of the bacterial-eukaryote relationships, i.e., mitochondrial-eukaryote and plastid-plant endosymbiotic relationships.
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Palzur E, Sharon A, Shehadeh M, Soustiel JF. Investigation of the mechanisms of neuroprotection mediated by Ro5-4864 in brain injury. Neuroscience 2016; 329:162-70. [PMID: 27223627 DOI: 10.1016/j.neuroscience.2016.05.014] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2015] [Revised: 05/07/2016] [Accepted: 05/10/2016] [Indexed: 11/17/2022]
Abstract
Increasing evidence has established the involvement of the 18-kDa translocator protein (TSPO) in the process of mitochondrial membrane permeabilization and subsequent apoptosis through modulation of the mitochondrial permeability transition pore. Recent studies have shown that treatment with Ro5-4864, a TSPO ligand, resulted in a neuroprotective effect in traumatic brain injury. Yet, the nature of this effect remained uncertain as mature neurons are considered to be lacking the TSPO protein. In order to investigate the mechanism of Ro5-4864-mediated neuroprotection, the neuro-inflammatory and neurosteroid response to cortical injury was tested in sham-operated, vehicle, cyclosporine A (CsA) and Ro5-4864-treated rats. As anticipated, the levels of interleukin 1β and tumor necrosis factor α, as well as the astrocyte and microglia cellular density in the injured area were all decreased by CsA in comparison with the vehicle group. By contrast, no visible effect could be observed in Ro5-4864-treated animals. None of the groups showed any significant difference with any other in respect with the expression of brain-derived neurotrophic factor. Double immunofluorescence staining with NeuN and TSPO confirmed the absence of TSPO in native neurons though showed clear evidence of co-localization of TSPO in the cytoplasm of NeuN-stained injured neurons. Altogether, this study shows that the neuronal protection mediated by Ro5-4864 in brain injury cannot be solely attributed to an indirect effect of the ligand on glial TSPO but may also represent the consequence of the modulation of upregulated TSPO in injured neurons. This observation may be of importance for future pharmacological research in neurotrauma.
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Affiliation(s)
- Eilam Palzur
- Eliachar Research Laboratory, Medical Center of the Galilee, Faculty of Medicine in the Galilee, University of Bar Ilan, Naharia 22100, Israel
| | - Aviram Sharon
- Department of Neurosurgery, Medical Center of the Galilee, Faculty of Medicine in the Galilee, University of Bar Ilan, Naharia 22100, Israel
| | - Mona Shehadeh
- Eliachar Research Laboratory, Medical Center of the Galilee, Faculty of Medicine in the Galilee, University of Bar Ilan, Naharia 22100, Israel
| | - Jean Francois Soustiel
- Eliachar Research Laboratory, Medical Center of the Galilee, Faculty of Medicine in the Galilee, University of Bar Ilan, Naharia 22100, Israel; Department of Neurosurgery, Medical Center of the Galilee, Faculty of Medicine in the Galilee, University of Bar Ilan, Naharia 22100, Israel.
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71
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Li F, Liu J, Liu N, Kuhn LA, Garavito RM, Ferguson-Miller S. Translocator Protein 18 kDa (TSPO): An Old Protein with New Functions? Biochemistry 2016; 55:2821-31. [PMID: 27074410 DOI: 10.1021/acs.biochem.6b00142] [Citation(s) in RCA: 91] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Translocator protein 18 kDa (TSPO) was previously known as the peripheral benzodiazepine receptor (PBR) in eukaryotes, where it is mainly localized to the mitochondrial outer membrane. Considerable evidence indicates that it plays regulatory roles in steroidogenesis and apoptosis and is involved in various human diseases, such as metastatic cancer, Alzheimer's and Parkinson's disease, inflammation, and anxiety disorders. Ligands of TSPO are widely used as diagnostic tools and treatment options, despite there being no clear understanding of the function of TSPO. An ortholog in the photosynthetic bacterium Rhodobacter was independently discovered as the tryptophan-rich sensory protein (TspO) and found to play a role in the response to changes in oxygen and light conditions that regulate photosynthesis and respiration. As part of this highly conserved protein family found in all three kingdoms, the rat TSPO is able to rescue the knockout phenotype in Rhodobacter, indicating functional as well as structural conservation. Recently, a major breakthrough in the field was achieved: the determination of atomic-resolution structures of TSPO from different species by several independent groups. This now allows us to reexamine the function of TSPO with a molecular perspective. In this review, we focus on recently determined structures of TSPO and their implications for potential functions of this ubiquitous multifaceted protein. We suggest that TSPO is an ancient bacterial receptor/stress sensor that has developed additional interactions, partners, and roles in its mitochondrial outer membrane environment in eukaryotes.
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Affiliation(s)
- Fei Li
- Department of Biochemistry and Molecular Biology, Michigan State University , East Lansing, Michigan 48824, United States
| | - Jian Liu
- Department of Biochemistry and Molecular Biology, Michigan State University , East Lansing, Michigan 48824, United States
| | - Nan Liu
- Department of Biochemistry and Molecular Biology, Michigan State University , East Lansing, Michigan 48824, United States.,Department of Computer Science and Engineering, Michigan State University , East Lansing, Michigan 48824-1319, United States.,Department of Chemistry, Michigan State University , East Lansing, Michigan 48824-1319, United States
| | - Leslie A Kuhn
- Department of Biochemistry and Molecular Biology, Michigan State University , East Lansing, Michigan 48824, United States.,Department of Computer Science and Engineering, Michigan State University , East Lansing, Michigan 48824-1319, 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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Changes in Binding of [(123)I]CLINDE, a High-Affinity Translocator Protein 18 kDa (TSPO) Selective Radioligand in a Rat Model of Traumatic Brain Injury. Neuromolecular Med 2016; 18:158-69. [PMID: 26969181 DOI: 10.1007/s12017-016-8385-y] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2015] [Accepted: 02/02/2016] [Indexed: 01/01/2023]
Abstract
After traumatic brain injury (TBI), secondary injuries develop, including neuroinflammatory processes that contribute to long-lasting impairments. These secondary injuries represent potential targets for treatment and diagnostics. The translocator protein 18 kDa (TSPO) is expressed in activated microglia cells and upregulated in response to brain injury and therefore a potential biomarker of the neuroinflammatory processes. Second-generation radioligands of TSPO, such as [(123)I]CLINDE, have a higher signal-to-noise ratio as the prototype ligand PK11195. [(123)I]CLINDE has been employed in human studies using single-photon emission computed tomography to image the neuroinflammatory response after stroke. In this study, we used the same tracer in a rat model of TBI to determine changes in TSPO expression. Adult Sprague-Dawley rats were subjected to moderate controlled cortical impact injury and sacrificed at 6, 24, 72 h and 28 days post surgery. TSPO expression was assessed in brain sections employing [(123)I]CLINDE in vitro autoradiography. From 24 h to 28 days post surgery, injured animals exhibited a marked and time-dependent increase in [(123)I]CLINDE binding in the ipsilateral motor, somatosensory and parietal cortex, as well as in the hippocampus and thalamus. Interestingly, binding was also significantly elevated in the contralateral M1 motor cortex following TBI. Craniotomy without TBI caused a less marked increase in [(123)I]CLINDE binding, restricted to the ipsilateral hemisphere. Radioligand binding was consistent with an increase in TSPO mRNA expression and CD11b immunoreactivity at the contusion site. This study demonstrates the applicability of [(123)I]CLINDE for detailed regional and quantitative assessment of glial activity in experimental models of TBI.
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73
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The hGFAP-driven conditional TSPO knockout is protective in a mouse model of multiple sclerosis. Sci Rep 2016; 6:22556. [PMID: 26925573 PMCID: PMC4772008 DOI: 10.1038/srep22556] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2014] [Accepted: 02/17/2016] [Indexed: 01/04/2023] Open
Abstract
The mitochondrial translocator protein (TSPO) has been implicated in CNS diseases. Here, we sought to determine the specific role of TSPO in experimental autoimmune encephalomyelitis (EAE), the most studied animal model of multiple sclerosis (MS). To fundamentally elucidate the functions of TSPO, we first developed a viable TSPO knockout mouse. A conditional TSPO knockout mouse was generated by utilizing the Cre-Lox system. We generated a TSPO floxed mouse, and then crossed this mouse with a Cre recombinase expressing mouse driven by the human glial fibrillary acidic protein (hGFAP) promoter. The resultant mouse was a neural linage line specific TSPO knockout. The loss of TSPO in the CNS did not result in overt developmental defects or phenotypes. The TSPO−/− mouse showed a decrease in GFAP expression, correlating with a decrease in astrogliosis in response to neural injury during EAE. This decrease in astrogliosis was also witnessed in the lessening of severity of EAE clinical scoring, indicating an in vivo functional role for TSPO in suppressing EAE. The TSPO−/− mouse could be a useful tool in better understanding the role of TSPO in CNS disease, and our results implicate TSPO as a potential therapeutic target in MS.
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Faden AI, Wu J, Stoica BA, Loane DJ. Progressive inflammation-mediated neurodegeneration after traumatic brain or spinal cord injury. Br J Pharmacol 2016; 173:681-91. [PMID: 25939377 PMCID: PMC4742301 DOI: 10.1111/bph.13179] [Citation(s) in RCA: 198] [Impact Index Per Article: 24.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2014] [Revised: 03/31/2015] [Accepted: 04/14/2015] [Indexed: 12/14/2022] Open
Abstract
Traumatic brain injury (TBI) has been linked to dementia and chronic neurodegeneration. Described initially in boxers and currently recognized across high contact sports, the association between repeated concussion (mild TBI) and progressive neuropsychiatric abnormalities has recently received widespread attention, and has been termed chronic traumatic encephalopathy. Less well appreciated are cognitive changes associated with neurodegeneration in the brain after isolated spinal cord injury. Also under-recognized is the role of sustained neuroinflammation after brain or spinal cord trauma, even though this relationship has been known since the 1950s and is supported by more recent preclinical and clinical studies. These pathological mechanisms, manifested by extensive microglial and astroglial activation and appropriately termed chronic traumatic brain inflammation or chronic traumatic inflammatory encephalopathy, may be among the most important causes of post-traumatic neurodegeneration in terms of prevalence. Importantly, emerging experimental work demonstrates that persistent neuroinflammation can cause progressive neurodegeneration that may be treatable even weeks after traumatic injury.
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Affiliation(s)
- Alan I Faden
- Department of Anesthesiology, Center for Shock, Trauma and Anesthesiology Research (STAR), University of Maryland School of Medicine, Baltimore, MD, USA
| | - Junfang Wu
- Department of Anesthesiology, Center for Shock, Trauma and Anesthesiology Research (STAR), University of Maryland School of Medicine, Baltimore, MD, USA
| | - Bogdan A Stoica
- Department of Anesthesiology, Center for Shock, Trauma and Anesthesiology Research (STAR), University of Maryland School of Medicine, Baltimore, MD, USA
| | - David J Loane
- Department of Anesthesiology, Center for Shock, Trauma and Anesthesiology Research (STAR), University of Maryland School of Medicine, Baltimore, MD, USA
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Porcu P, Barron AM, Frye CA, Walf AA, Yang SY, He XY, Morrow AL, Panzica GC, Melcangi RC. Neurosteroidogenesis Today: Novel Targets for Neuroactive Steroid Synthesis and Action and Their Relevance for Translational Research. J Neuroendocrinol 2016; 28:12351. [PMID: 26681259 PMCID: PMC4769676 DOI: 10.1111/jne.12351] [Citation(s) in RCA: 120] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/09/2015] [Revised: 12/12/2015] [Accepted: 12/12/2015] [Indexed: 12/19/2022]
Abstract
Neuroactive steroids are endogenous neuromodulators synthesised in the brain that rapidly alter neuronal excitability by binding to membrane receptors, in addition to the regulation of gene expression via intracellular steroid receptors. Neuroactive steroids induce potent anxiolytic, antidepressant, anticonvulsant, sedative, analgesic and amnesic effects, mainly through interaction with the GABAA receptor. They also exert neuroprotective, neurotrophic and antiapoptotic effects in several animal models of neurodegenerative diseases. Neuroactive steroids regulate many physiological functions, such as the stress response, puberty, the ovarian cycle, pregnancy and reward. Their levels are altered in several neuropsychiatric and neurological diseases and both preclinical and clinical studies emphasise a therapeutic potential of neuroactive steroids for these diseases, whereby symptomatology ameliorates upon restoration of neuroactive steroid concentrations. However, direct administration of neuroactive steroids has several challenges, including pharmacokinetics, low bioavailability, addiction potential, safety and tolerability, which limit its therapeutic use. Therefore, modulation of neurosteroidogenesis to restore the altered endogenous neuroactive steroid tone may represent a better therapeutic approach. This review summarises recent approaches that target the neuroactive steroid biosynthetic pathway at different levels aiming to promote neurosteroidogenesis. These include modulation of neurosteroidogenesis through ligands of the translocator protein 18 kDa and the pregnane xenobiotic receptor, as well as targeting of specific neurosteroidogenic enzymes such as 17β-hydroxysteroid dehydrogenase type 10 or P450 side chain cleavage. Enhanced neurosteroidogenesis through these targets may be beneficial not only for neurodegenerative diseases, such as Alzheimer's disease and age-related dementia, but also for neuropsychiatric diseases, including alcohol use disorders.
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Affiliation(s)
- Patrizia Porcu
- Neuroscience Institute, National Research Council of Italy (CNR), Cagliari, Italy
| | - Anna M. Barron
- Molecular Imaging Center, National Institute of Radiological Sciences, Anagawa, Inage-ku, Chiba, Japan
| | - Cheryl Anne Frye
- Institute of Arctic Biology, The University of Alaska–Fairbanks, Fairbanks, AK, USA
- The University at Albany, Albany, NY, USA
| | - Alicia A. Walf
- Institute of Arctic Biology, The University of Alaska–Fairbanks, Fairbanks, AK, USA
- The University at Albany, Albany, NY, USA
- Department of Cognitive Science, Rensselaer Polytechnic Institute, Troy, NY, USA
| | - Song-Yu Yang
- Department of Developmental Biochemistry, NYS Institute for Basic Research in Developmental Disabilities, Staten Island, NY, USA
| | - Xue-Ying He
- Department of Developmental Biochemistry, NYS Institute for Basic Research in Developmental Disabilities, Staten Island, NY, USA
| | - A. Leslie Morrow
- Departments of Psychiatry and Pharmacology, Bowles Center for Alcohol Studies, University of North Carolina School of Medicine, Chapel Hill, NC, USA
| | - Gian Carlo Panzica
- Department of Neuroscience, University of Turin, and NICO - Neuroscience Institute Cavalieri Ottolenghi, Orbassano, Italy
| | - Roberto C. Melcangi
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Milan, Italy
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Srivastava P, Kaul A, Ojha H, Kumar P, Tiwari AK. Design, synthesis and biological evaluation of methyl-2-(2-(5-bromo benzoxazolone)acetamido)-3-(1H-indol-3-yl)propanoate: TSPO ligand for SPECT. RSC Adv 2016. [DOI: 10.1039/c6ra19514h] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The translator protein (TSPO, 18 kDa), a transmembrane mitochondrial protein, has been explored as an important biomarker by researchers for inflammation, immune modulation and cell proliferation. Here we report a new SPECT agent99mTc-MBIP for TSPO imaging and quantification.
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Affiliation(s)
- Pooja Srivastava
- Division of Cyclotron and Radiopharmaceutical Sciences
- Institute of Nuclear Medicine and Allied Sciences
- Delhi-110054
- India
- Molecular Neuroscience and Functional Genomics Laboratory
| | - Ankur Kaul
- Division of Cyclotron and Radiopharmaceutical Sciences
- Institute of Nuclear Medicine and Allied Sciences
- Delhi-110054
- India
| | - Himanshu Ojha
- Division of Cyclotron and Radiopharmaceutical Sciences
- Institute of Nuclear Medicine and Allied Sciences
- Delhi-110054
- India
| | - Pravir Kumar
- Molecular Neuroscience and Functional Genomics Laboratory
- Department of Biotechnology
- Delhi Technological University
- Delhi 110042
- India
| | - Anjani K. Tiwari
- Division of Cyclotron and Radiopharmaceutical Sciences
- Institute of Nuclear Medicine and Allied Sciences
- Delhi-110054
- India
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Therapies negating neuroinflammation after brain trauma. Brain Res 2015; 1640:36-56. [PMID: 26740405 DOI: 10.1016/j.brainres.2015.12.024] [Citation(s) in RCA: 68] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2015] [Revised: 12/07/2015] [Accepted: 12/14/2015] [Indexed: 12/11/2022]
Abstract
Traumatic brain injury (TBI) elicits a complex secondary injury response, with neuroinflammation as a crucial central component. Long thought to be solely a deleterious factor, the neuroinflammatory response has recently been shown to be far more intricate, with both beneficial and detrimental consequences depending on the timing, magnitude and specific immune composition of the response post-injury. Despite extensive preclinical and clinical research into mechanisms of secondary injury after TBI, no effective neuroprotective therapy has been identified, with potential candidates repeatedly proving disappointing in the clinic. The neuroinflammatory response offers a promising avenue for therapeutic targeting, aiming to quell the deleterious consequences without influencing its function in providing a neurotrophic environment supportive of repair. The present review firstly describes the findings of recent clinical trials that aimed to modulate inflammation as a means of neuroprotection. Secondly, we discuss promising multifunctional and single-target anti-inflammatory candidates either currently in trial, or with ample experimental evidence supporting clinical application. This article is part of a Special Issue entitled SI:Brain injury and recovery.
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Abstract
The most commonly utilized PET radionuclide is fluorine-18 ((18)F) because of its convenient half-life and excellent imaging properties. In this review, we present the first analysis of patents issued for radiotracers labeled with fluorine-18 (between 2009 and 2015), and provide perspective on current trends and future directions in PET radiotracer development.
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Graham A. Mitochondrial regulation of macrophage cholesterol homeostasis. Free Radic Biol Med 2015; 89:982-92. [PMID: 26416507 DOI: 10.1016/j.freeradbiomed.2015.08.010] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/08/2015] [Revised: 07/28/2015] [Accepted: 08/11/2015] [Indexed: 12/19/2022]
Abstract
This review explores the relationship between mitochondrial structure and function in the regulation of macrophage cholesterol metabolism and proposes that mitochondrial dysfunction contributes to loss of the elegant homeostatic mechanisms which normally maintain cellular sterol levels within defined limits. Mitochondrial sterol 27-hydroxylase (CYP27A1) can generate oxysterol activators of liver X receptors which heterodimerise with retinoid X receptors, enhancing the transcription of ATP binding cassette transporters (ABCA1, ABCG1, and ABCG4), that can remove excess cholesterol via efflux to apolipoproteins A-1, E, and high density lipoprotein, and inhibit inflammation. The activity of CYP27A1 is regulated by the rate of supply of cholesterol substrate to the inner mitochondrial membrane, mediated by a complex of proteins. The precise identity of this dynamic complex remains controversial, even in steroidogenic tissues, but may include steroidogenic acute regulatory protein and the 18 kDa translocator protein, together with voltage-dependent anion channels, ATPase AAA domain containing protein 3A, and optic atrophy type 1 proteins. Certainly, overexpression of StAR and TSPO proteins can enhance macrophage cholesterol efflux to apoA-I and/or HDL, while perturbations in mitochondrial function, or changes in the expression of mitochondrial fusion proteins, alter the efficiency of cholesterol efflux. Molecules which can sustain or improve mitochondrial function or increase the activity of the protein complex involved in cholesterol transfer may have utility in resolving the problem of dysregulated macrophage cholesterol homeostasis, a condition which may contribute to inflammation, atherosclerosis, nonalcoholic steatohepatitis, osteoblastic bone resorption, and some disorders of the central nervous system.
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Affiliation(s)
- Annette Graham
- Department of Life Sciences, School of Health and Life Sciences, and Institute for Applied Health Research, Glasgow Caledonian University, 70 Cowcaddens Road, Glasgow G4 0BA, United Kingdom.
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TSPO ligand residence time influences human glioblastoma multiforme cell death/life balance. Apoptosis 2015; 20:383-98. [PMID: 25413799 DOI: 10.1007/s10495-014-1063-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Ligands addressed to the mitochondrial Translocator Protein (TSPO) have been suggested as cell death/life and steroidogenesis modulators. Thus, TSPO ligands have been proposed as drug candidates in several diseases; nevertheless, a correlation between their binding affinity and in vitro efficacy has not been demonstrated yet, questioning the specificity of the observed effects. Since drug-target residence time is an emerging parameter able to influence drug pharmacological features, herein, the interaction between TSPO and irDE-MPIGA, a covalent TSPO ligand, was investigated in order to explore TSPO control on death/life processes in a standardized glioblastoma cell setting. After 90 min irDE-MPIGA cell treatment, 25 nM ligand concentration saturated irreversibly all TSPO binding sites; after 24 h, TSPO de-novo synthesis occurred and about 40 % TSPO binding sites resulted covalently bound to irDE-MPIGA. During cell culture treatments, several dynamic events were observed: (a) early apoptotic markers appeared, such as mitochondrial membrane potential collapse (at 3 h) and externalization of phosphatidylserine (at 6 h); (b) cell viability was reduced (at 6 h), without cell cycle arrest. After digitonin-permeabilized cell suspension treatment, a modulation of mitochondrial permeability transition pore was evidenced. Similar effects were elicited by the reversible TSPO ligand PIGA only when applied at micromolar dose. Interestingly, after 6 h, irDE-MPIGA cell exposure restored cell survival parameters. These results highlighted the ligand-target residence time and the cellular setting are crucial parameters that should be taken into account to understand the drug binding affinity and efficacy correlation and, above all, to translate efficiently cellular drug responses from bench to bedside.
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Arbo BD, Benetti F, Garcia-Segura LM, Ribeiro MF. Therapeutic actions of translocator protein (18 kDa) ligands in experimental models of psychiatric disorders and neurodegenerative diseases. J Steroid Biochem Mol Biol 2015. [PMID: 26200949 DOI: 10.1016/j.jsbmb.2015.07.007] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Translocator protein (TSPO) is an 18kDa protein located at contact sites between the outer and the inner mitochondrial membrane. Numerous studies have associated TSPO with the translocation of cholesterol across the aqueous mitochondrial intermembrane space and the regulation of steroidogenesis, as well as with the control of some other mitochondrial functions, such as mitochondrial respiration, mitochondrial permeability transition pore opening, apoptosis and cell proliferation. In the brain, changes in TSPO expression occur in several neuropathological conditions including neurodegenerative diseases and psychiatric disorders. Furthermore, TSPO ligands have been shown to promote neuroprotection in animal models of brain pathology. At least in some cases, the mechanisms of neuroprotection are associated with modifications in brain steroidogenesis. In addition, regulation of neuroinflammation seems to be a common mechanism in the neuroprotective actions of TSPO ligands in different animal models of brain pathology.
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Affiliation(s)
- B D Arbo
- Laboratório de Interação Neuro-Humoral, Department of Physiology, ICBS, Universidade Federal do Rio Grande do Sul (UFRGS), Rua Sarmento Leite, 500, CEP 90050-170 Porto Alegre, RS, Brazil; Cajal Institute, CSIC, Avenida Doctor Arce, 37, 28002 Madrid, Spain.
| | - F Benetti
- Laboratório de Neurofisiologia Cognitiva e do Desenvolvimento, Department of Physiology, ICBS, Universidade Federal do Rio Grande do Sul (UFRGS), Rua Sarmento Leite, 500, CEP 90050-170 Porto Alegre, RS, Brazil
| | | | - M F Ribeiro
- Laboratório de Interação Neuro-Humoral, Department of Physiology, ICBS, Universidade Federal do Rio Grande do Sul (UFRGS), Rua Sarmento Leite, 500, CEP 90050-170 Porto Alegre, RS, Brazil
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Repalli J. Translocator protein (TSPO) role in aging and Alzheimer's disease. Curr Aging Sci 2015; 7:168-75. [PMID: 25495567 PMCID: PMC4435228 DOI: 10.2174/1874609808666141210103146] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2014] [Revised: 10/31/2014] [Accepted: 12/09/2014] [Indexed: 01/22/2023]
Abstract
Cellular damage and deregulated apoptotic cell death lead to functional impairment, and a main
consequence of these events is aging. Cellular damage is initiated by different stress/risk factors such as
oxidative stress, inflammation, and heavy metals. These stress/risk factors affect the cellular homeostasis
by altering methylation status of several aging and Alzheimer’s disease associated genes; these effects can
be manifested immediately after exposure to stress and at later stages of life. However, when cellular damage
exceeds certain threshold levels apoptosis is initiated. This review discusses the stress factors involved
in cellular damage and the role and potential of TSPO-mediated cell death in aging as well as in Alzheimer’s disease,
which is also characterized by extensive cell death. Mitochondrial-mediated apoptotic death through the release of cytochrome
c is regulated by TSPO, and increased expression of this protein is observed in both elderly people and in patients
with Alzheimer’s disease. TSPO forms and mediates opening of the mitochondrial membrane pore, mPTP and oxidizes
cardiolipin, and these events lead to the leakage of apoptotic death mediators, such as cytochrome c, resulting in cell
death. However, TSPO has many proposed functions and can also increase steroid synthesis, which leads to inhibition of
inflammation and inhibition of the release of apoptotic factors, thereby decreasing cell damage and promoting cell survival.
Thus, TSPO mediates apoptosis and decreases the cell damage, which in turn dictates the process of aging as well
as the functionality of organs such as the brain. TSPO modulation with ligands in the Alzheimer’s disease mouse model
showed improvement in behavioral symptoms, and studies in Drosophila species showed increased cell survival and prolonged
lifespan in flies after TSPO inhibition. These data suggest that since effects/signs of stress can manifest at any
time, prevention through change in lifestyle and TSPO modulation could be potential strategies for altering both the aging
process and the progression of Alzheimer’s disease.
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Affiliation(s)
- Jayanthi Repalli
- NYU Langone Medical Center,180 Varick Street, Room 802, New York, NY, 10014, USA.
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Targeting the 18-kDa translocator protein: recent perspectives for neuroprotection. Biochem Soc Trans 2015; 43:559-65. [DOI: 10.1042/bst20150028] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Indexed: 12/14/2022]
Abstract
The translocator protein (TSPO, 18 kDa), mainly localized in the outer mitochondrial membrane of steroidogenic tissues, is involved in several cellular functions. TSPO level alterations have been reported in a number of human disorders, particularly in cancer, psychiatric and neurological diseases. In the central nervous system (CNS), TSPO is usually expressed in glial cells, but also in some neuronal cell types. Interestingly, the expression of TSPO on glial cells rises after brain injury and increased TSPO expression is often observed in neurological disorders, gliomas, encephalitis and traumatic injury. Since TSPO is up-regulated in brain diseases, several structurally different classes of ligands targeting TSPO have been described as potential diagnostic or therapeutic agents. Recent researches have reported that TSPO ligands might be valuable in the treatment of brain diseases. This review focuses on currently available TSPO ligands, as useful tools for the treatment of neurodegeneration, neuro-inflammation and neurotrauma.
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Papadopoulos V, Aghazadeh Y, Fan J, Campioli E, Zirkin B, Midzak A. Translocator protein-mediated pharmacology of cholesterol transport and steroidogenesis. Mol Cell Endocrinol 2015; 408:90-8. [PMID: 25818881 PMCID: PMC4417383 DOI: 10.1016/j.mce.2015.03.014] [Citation(s) in RCA: 92] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/09/2014] [Revised: 03/16/2015] [Accepted: 03/17/2015] [Indexed: 12/17/2022]
Abstract
Steroidogenesis begins with cholesterol transfer into mitochondria through the transduceosome, a complex composed of cytosolic proteins that include steroidogenesis acute regulatory protein (STAR), 14-3-3 adaptor proteins, and the outer mitochondrial membrane proteins Translocator Protein (TSPO) and Voltage-Dependent Anion Channel (VDAC). TSPO is a drug- and cholesterol-binding protein found at particularly high levels in steroid synthesizing cells. Its aberrant expression has been linked to cancer, neurodegeneration, neuropsychiatric disorders and primary hypogonadism. Brain steroids serve as local regulators of neural development and excitability. Reduced levels of these steroids have been linked to depression, anxiety and neurodegeneration. Reduced serum testosterone is common among subfertile young men and aging men, and is associated with depression, metabolic syndrome and reduced sexual function. Although testosterone-replacement therapy is available, there are undesired side-effects. TSPO drug ligands have been proposed as therapeutic agents to regulate steroid levels in the brain and testis.
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Affiliation(s)
- Vassilios Papadopoulos
- The Research Institute of the McGill University Health Centre, Montreal, Quebec, Canada; Department of Medicine, McGill University, Montreal, Quebec, Canada; Department of Pharmacology & Therapeutics, McGill University, Montreal, Quebec, Canada; Departments of Biochemistry, McGill University, Montreal, Quebec, Canada.
| | - Yasaman Aghazadeh
- The Research Institute of the McGill University Health Centre, Montreal, Quebec, Canada; Department of Medicine, McGill University, Montreal, Quebec, Canada
| | - Jinjiang Fan
- The Research Institute of the McGill University Health Centre, Montreal, Quebec, Canada; Department of Medicine, McGill University, Montreal, Quebec, Canada
| | - Enrico Campioli
- The Research Institute of the McGill University Health Centre, Montreal, Quebec, Canada; Department of Medicine, McGill University, Montreal, Quebec, Canada
| | - Barry Zirkin
- Department of Biochemistry and Molecular Biology, Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD, USA
| | - Andrew Midzak
- The Research Institute of the McGill University Health Centre, Montreal, Quebec, Canada; Departments of Biochemistry, McGill University, Montreal, Quebec, Canada
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Graham A, Allen AM. Mitochondrial function and regulation of macrophage sterol metabolism and inflammatory responses. World J Cardiol 2015; 7:277-286. [PMID: 26015858 PMCID: PMC4438467 DOI: 10.4330/wjc.v7.i5.277] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/13/2014] [Revised: 02/25/2015] [Accepted: 03/18/2015] [Indexed: 02/06/2023] Open
Abstract
The aim of this review is to explore the role of mitochondria in regulating macrophage sterol homeostasis and inflammatory responses within the aetiology of atherosclerosis. Macrophage generation of oxysterol activators of liver X receptors (LXRs), via sterol 27-hydroxylase, is regulated by the rate of flux of cholesterol to the inner mitochondrial membrane, via a complex of cholesterol trafficking proteins. Oxysterols are key signalling molecules, regulating the transcriptional activity of LXRs which coordinate macrophage sterol metabolism and cytokine production, key features influencing the impact of these cells within atherosclerotic lesions. The precise identity of the complex of proteins mediating mitochondrial cholesterol trafficking in macrophages remains a matter of debate, but may include steroidogenic acute regulatory protein and translocator protein. There is clear evidence that targeting either of these proteins enhances removal of cholesterol via LXRα-dependent induction of ATP binding cassette transporters (ABCA1, ABCG1) and limits the production of inflammatory cytokines; interventions which influence mitochondrial structure and bioenergetics also impact on removal of cholesterol from macrophages. Thus, molecules which can sustain or improve mitochondrial structure, the function of the electron transport chain, or increase the activity of components of the protein complex involved in cholesterol transfer, may therefore have utility in limiting or regressing atheroma development, reducing the incidence of coronary heart disease and myocardial infarction.
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Midzak AS, Akula N, Rone MB, Papadopoulos V. Computational modeling and biological validation of novel non-steroidal ligands for the cholesterol recognition/interaction amino acid consensus (CRAC) motif of the mitochondrial translocator protein (TSPO). Pharmacol Res 2015; 99:393-403. [PMID: 25936508 DOI: 10.1016/j.phrs.2015.03.023] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/23/2014] [Revised: 03/27/2015] [Accepted: 03/27/2015] [Indexed: 01/24/2023]
Abstract
Mitochondria play a critical role in the physiological homeostasis of the cell, contributing to numerous cellular processes, including bioenergetics, metabolism and cell life and death. Owing to their keystone role, mitochondria have gained much attention as pharmacological targets. The outer mitochondrial integral membrane translocator protein (TSPO) has attracted a significant degree of pharmacological interest owing to its ability to bind a number of classes of drugs with high affinity and specificity. In addition to its well-characterized drug binding site, TSPO possess an additional high-affinity ligand binding site, originally identified for its ability to bind the lipid cholesterol, which was named the cholesterol recognition/interaction amino acid consensus (CRAC) motif. Previous investigations from our laboratory identified additional ligands targeted to TSPO's CRAC motif which are able to potently inhibit mitochondrial cholesterol transport and steroid biosynthesis, processes for which TSPO has been well-characterized. However, all of these compounds possessed the steroidal backbone common to cholesterol and steroid hormones. In our efforts to expand our understanding of TSPO's CRAC motif, we performed studies aimed at identifying non-steroidal ligands for this motif. Molecular modeling and in silico screening of large chemical libraries identified a panel of compounds which were subsequently screened for bioactivity in a number of steroidogenic model systems. These efforts identified a family of non-steroidal CRAC ligands able to potently inhibit steroidogenesis, and at higher concentrations, promote apoptosis. In addition, the best candidate in this family was able to suppress testosterone synthesis when administered to rats, indicating that this novel family of non-steroidal CRAC ligands may serve as prototypes for the development of drugs useful for treatment of diseases of steroid overproduction, such as Cushing's syndrome and steroidogenic cell tumors in humans and animals.
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Affiliation(s)
- Andrew S Midzak
- The Research Institute of the McGill University Health Centre and Department of Medicine, McGill University, Montreal, Quebec, Canada
| | - Nagaraju Akula
- The Research Institute of the McGill University Health Centre and Department of Medicine, McGill University, Montreal, Quebec, Canada
| | - Malena B Rone
- The Research Institute of the McGill University Health Centre and Department of Medicine, McGill University, Montreal, Quebec, Canada
| | - Vassilios Papadopoulos
- The Research Institute of the McGill University Health Centre and Department of Medicine, McGill University, Montreal, Quebec, Canada; Departments of Biochemistry and Pharmacology & Therapeutics, McGill University, Montreal, Quebec, Canada.
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Li F, Liu J, Garavito RM, Ferguson-Miller S. Evolving understanding of translocator protein 18 kDa (TSPO). Pharmacol Res 2015; 99:404-9. [PMID: 25882248 DOI: 10.1016/j.phrs.2015.03.022] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/02/2015] [Revised: 03/25/2015] [Accepted: 03/27/2015] [Indexed: 02/01/2023]
Abstract
The translocator protein 18 kDa (TSPO) has been the focus of intense research by the biomedical community and the pharmaceutical industry because of its apparent involvement in many disease-related processes. These include steroidogenesis, apoptosis, inflammation, neurological disease and cancer, resulting in the use of TSPO as a biomarker and its potential as a drug target. Despite more than 30 years of study, the precise function of TSPO remains elusive. A recent breakthrough in determining the high-resolution crystal structures of bacterial homologs of mitochondrial TSPO provides new insight into the structural and functional properties at a molecular level and new opportunities for investigating the significance of this ancient and highly conserved protein family. The availability of atomic level structural information from different species also provides a platform for structure-based drug development. Here we briefly review current knowledge regarding TSPO and the implications of the new structures with respect to hypotheses and controversies in the field.
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Affiliation(s)
- Fei Li
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824, USA
| | - Jian Liu
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824, USA
| | - R Michael Garavito
- Department of Biochemistry and Molecular Biology, 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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Vállez Garcia D, de Vries EFJ, Toyohara J, Ishiwata K, Hatano K, Dierckx RAJO, Doorduin J. Evaluation of [(11)C]CB184 for imaging and quantification of TSPO overexpression in a rat model of herpes encephalitis. Eur J Nucl Med Mol Imaging 2015; 42:1106-18. [PMID: 25771904 PMCID: PMC4424274 DOI: 10.1007/s00259-015-3021-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2014] [Accepted: 02/16/2015] [Indexed: 02/04/2023]
Abstract
Purpose Evaluation of translocator protein (TSPO) overexpression is considered an attractive research tool for monitoring neuroinflammation in several neurological and psychiatric disorders. [11C]PK11195 PET imaging has been widely used for this purpose. However, it has a low sensitivity and a poor signal-to-noise ratio. For these reasons, [11C]CB184 was evaluated as a potentially more sensitive PET tracer. Methods A model of herpes simplex encephalitis (HSE) was induced in male Wistar rats. On day 6 or 7 after virus inoculation, [11C]CB184 PET scans were acquired followed by ex vivo evaluation of biodistribution. In addition, [11C]CB184 and [11C]PK11195 PET scans with arterial blood sampling were acquired to generate input for pharmacokinetic modelling. Differences between the saline-treated control group and the virus-treated HSE group were explored using volumes of interest and voxel-based analysis. Results The biodistribution study showed significantly higher [11C]CB184 uptake in the amygdala, olfactory bulb, medulla, pons and striatum (p < 0.05) in HSE rats than in control rats, and the voxel-based analysis showed higher bilateral uptake in the pons and medulla (p < 0.05, corrected at the cluster level). A high correlation was found between tracer uptake in the biodistribution study and on the PET scans (p < 0.001, r2 = 0.71). Pretreatment with 5 mg/kg of unlabelled PK11195 effectively reduced (p < 0.001) [11C]CB184 uptake in the whole brain. Both, [11C]CB184 and [11C]PK11195, showed similar amounts of metabolites in plasma, and the binding potential (BPND) was not significantly different between the HSE rats and the control rats. In HSE rats BPND for [11C]CB184 was significantly higher (p < 0.05) in the amygdala, hypothalamus, medulla, pons and septum than in control rats, whereas higher uptake of [11C]PK11195 was only detected in the medulla. Conclusion [11C]CB184 showed nonspecific binding to healthy tissue comparable to that observed for [11C]PK11195, but it displayed significantly higher specific binding in those brain regions affected by the HSE. Our results suggest that [11C]CB184 PET is a good alternative for imaging of neuroinflammatory processes.
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Affiliation(s)
- David Vállez Garcia
- Department of Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, University of Groningen, PO Box 30.001, 9700 RB, Groningen, The Netherlands,
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Vicidomini C, Panico M, Greco A, Gargiulo S, Coda ARD, Zannetti A, Gramanzini M, Roviello GN, Quarantelli M, Alfano B, Tavitian B, Dollé F, Salvatore M, Brunetti A, Pappatà S. In vivo imaging and characterization of [(18)F]DPA-714, a potential new TSPO ligand, in mouse brain and peripheral tissues using small-animal PET. Nucl Med Biol 2014; 42:309-16. [PMID: 25537727 DOI: 10.1016/j.nucmedbio.2014.11.009] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2014] [Revised: 11/18/2014] [Accepted: 11/19/2014] [Indexed: 02/05/2023]
Abstract
INTRODUCTION The translocator protein 18 kDa (TSPO), a biochemical marker of neuroinflammation, is highly expressed in the brain activated microglia and it is also expressed by peripheral inflammatory cells and normal peripheral tissues. Thus, development of radioligands for the TSPO may contribute to further understanding the in vivo TSPO function in central and peripheral inflammatory processes and other pathologies. Here, we report the biodistribution, the specific binding and the radiometabolites of [(18)F]DPA-714, a promising fluorinated PET radiotracer, in normal mice using a microPET/CT scanner. METHODS The in vivo biodistribution and kinetics of [(18)F]DPA-714 were measured in mice brain and peripheral tissues. Specific binding to TSPO sites was assessed using pharmacological competitive studies by means of saturation experiments performed by i.v. injection of 1mg/kg of unlabeled DPA-714 or 3mg/kg of unlabeled PK11195. A region of interest analysis was performed to generate time-activity curves in the brain, heart, lung, kidney, spleen and liver. Metabolites assay was performed in the plasma and peripheral organs by radio-HPLC. RESULTS [(18)F]DPA-714 reached high concentration in lung, heart, kidney and spleen, tissues well known to be rich in TSPO sites. [(18)F]DPA-714 kinetics were faster in the lung and slower in the kidney. Pre-injection of unlabeled DPA-714 or PK11195 inhibited about 80% of [(18)F]DPA-714 uptake in the lung and heart (p<0.0005). The percentage of inhibition in the kidney was lower and achieved at later times only with DPA-714 (p<0.05) but not with PK11195. Sixty minutes after radiotracer injection only unmetabolized radioligand was found in the brain, lung, heart and spleen. CONCLUSION These results suggest that [(18)F]DPA-714 is a suitable PET ligand for imaging in mice brain and peripheral tissues since it binds with high specificity TSPO binding sites and it is almost unchanged at 60 minutes after radiotracer injection in the brain and TSPO-rich regions.
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Affiliation(s)
- Caterina Vicidomini
- Institute of Biostructure and Bioimaging, CNR, Naples, Italy; CEINGE, Biotecnologie Avanzate, s.c.a.r.l., Naples, Italy
| | - Mariarosaria Panico
- Institute of Biostructure and Bioimaging, CNR, Naples, Italy; CEINGE, Biotecnologie Avanzate, s.c.a.r.l., Naples, Italy
| | - Adelaide Greco
- Department of Advanced Biomedical Sciences, Federico II University, Naples, Italy; CEINGE, Biotecnologie Avanzate, s.c.a.r.l., Naples, Italy
| | - Sara Gargiulo
- Institute of Biostructure and Bioimaging, CNR, Naples, Italy; CEINGE, Biotecnologie Avanzate, s.c.a.r.l., Naples, Italy
| | - Anna Rita Daniela Coda
- Institute of Biostructure and Bioimaging, CNR, Naples, Italy; CEINGE, Biotecnologie Avanzate, s.c.a.r.l., Naples, Italy
| | - Antonella Zannetti
- Institute of Biostructure and Bioimaging, CNR, Naples, Italy; CEINGE, Biotecnologie Avanzate, s.c.a.r.l., Naples, Italy
| | - Matteo Gramanzini
- Institute of Biostructure and Bioimaging, CNR, Naples, Italy; CEINGE, Biotecnologie Avanzate, s.c.a.r.l., Naples, Italy
| | | | | | - Bruno Alfano
- Institute of Biostructure and Bioimaging, CNR, Naples, Italy
| | - Bertrand Tavitian
- Inserm U970, PARCC, Université Paris Descartes, Hôpital Européen Georges Pompidou, Paris, France; CEA, I2BM, Service Hospitalier Frédéric Joliot, Orsay, France
| | - Frederic Dollé
- CEA, I2BM, Service Hospitalier Frédéric Joliot, Orsay, France
| | - Marco Salvatore
- Department of Advanced Biomedical Sciences, Federico II University, Naples, Italy
| | - Arturo Brunetti
- Department of Advanced Biomedical Sciences, Federico II University, Naples, Italy; CEINGE, Biotecnologie Avanzate, s.c.a.r.l., Naples, Italy
| | - Sabina Pappatà
- Institute of Biostructure and Bioimaging, CNR, Naples, Italy.
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Moehle MS, West AB. M1 and M2 immune activation in Parkinson's Disease: Foe and ally? Neuroscience 2014; 302:59-73. [PMID: 25463515 DOI: 10.1016/j.neuroscience.2014.11.018] [Citation(s) in RCA: 144] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2014] [Revised: 10/03/2014] [Accepted: 11/06/2014] [Indexed: 12/20/2022]
Abstract
Parkinson's Disease (PD) is a chronic and progressive neurodegenerative disorder of unknown etiology. Autopsy findings, genetics, retrospective studies, and molecular imaging all suggest a role for inflammation in the neurodegenerative process. However, relatively little is understood about the causes and implications of neuroinflammation in PD. Understanding how inflammation arises in PD, in particular the activation state of cells of the innate immune system, may provide an exciting opportunity for novel neuroprotective therapeutics. We analyze the evidence of immune system involvement in PD susceptibility, specifically in the context of M1 and M2 activation states. Tracking and modulating these activation states may provide new insights into both PD etiology and therapeutic strategies.
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Affiliation(s)
- M S Moehle
- Center for Neurodegeneration and Experimental Therapeutics, Department of Neurology, The University of Alabama at Birmingham, Birmingham, AL, United States.
| | - A B West
- Center for Neurodegeneration and Experimental Therapeutics, Department of Neurology, The University of Alabama at Birmingham, Birmingham, AL, United States
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Yoder KK, Territo PR, Hutchins GD, Hannestad J, Morris ED, Gallezot JD, Normandin MD, Cosgrove KP. Comparison of standardized uptake values with volume of distribution for quantitation of [(11)C]PBR28 brain uptake. Nucl Med Biol 2014; 42:305-8. [PMID: 25487553 DOI: 10.1016/j.nucmedbio.2014.11.003] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2014] [Revised: 11/04/2014] [Accepted: 11/11/2014] [Indexed: 12/11/2022]
Abstract
INTRODUCTION [(11)C]PBR28 is a high-affinity ligand for the Translocator Protein 18 kDa (TSPO), which is considered to be a marker for microglial activation. Volume of distribution (VT) estimated with an arterial plasma input function is the gold standard for quantitation of [(11)C]PBR28 binding. However, arterial sampling is impractical at many PET sites for multiple reasons. Reference region modeling approaches are not ideal for TSPO tracers, as the existence of a true reference region cannot be assumed. Given that it would be desirable to have a non-invasive index of [(11)C]PBR28 binding, we elected to study the utility of the semi-quantitative metric, standardized uptake value (SUV) for use in brain [(11)C]PBR PET studies. The primary goal of this study was to determine the relationship between SUV and VT. METHODS We performed a retrospective analysis of data from sixteen [(11)C]PBR28 PET scans acquired in baboons at baseline and at multiple time points after IV injection of lipopolysaccharide, an endotoxin that transiently induces neuroinflammation. For each scan, data from 14 brain regions of interest were studied. VT was estimated with the Logan plot, using metabolite-corrected input functions. SUV was calculated with data from 30 to 60 minutes after [(11)C]PBR28 injection. RESULTS Within individual PET studies, SUV tended to correlate well with VT. Across studies, the relationship between SUV and VT was variable. CONCLUSIONS From study to study, there was variability in the degree of correlation between [(11)C]PBR28 VT and SUV. There are multiple physiological factors that may contribute to this variance. ADVANCES IN KNOWLEDGE As currently applied, the non-invasive measurement of SUV does not appear to be a reliable outcome variable for [(11)C]PBR28. Additional work is needed to discover the source of the discrepancy in SUV between [(11)C]PBR28 scans. IMPLICATIONS FOR PATIENT CARE There is a need to develop alternatives to arterial plasma input functions for TSPO ligands in order to facilitate multi-center trials.
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Affiliation(s)
- Karmen K Yoder
- Radiology & Imaging Sciences, Indiana University School of Medicine, Indianapolis IN; Center for Neuroimaging, Indiana University School of Medicine, Indianapolis IN; Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN.
| | - Paul R Territo
- Radiology & Imaging Sciences, Indiana University School of Medicine, Indianapolis IN
| | - Gary D Hutchins
- Radiology & Imaging Sciences, Indiana University School of Medicine, Indianapolis IN; Center for Neuroimaging, Indiana University School of Medicine, Indianapolis IN
| | - Jonas Hannestad
- Yale PET Center, Yale University School of Medicine, New Haven CT
| | - Evan D Morris
- Yale PET Center, Yale University School of Medicine, New Haven CT
| | | | - Marc D Normandin
- Center for Advanced Medical Imaging Sciences, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston MA
| | - Kelly P Cosgrove
- Yale PET Center, Yale University School of Medicine, New Haven CT
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93
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Coughlin JM, Wang Y, Munro CA, Ma S, Yue C, Chen S, Airan R, Kim PK, Adams AV, Garcia C, Higgs C, Sair HI, Sawa A, Smith G, Lyketsos CG, Caffo B, Kassiou M, Guilarte TR, Pomper MG. Neuroinflammation and brain atrophy in former NFL players: An in vivo multimodal imaging pilot study. Neurobiol Dis 2014; 74:58-65. [PMID: 25447235 DOI: 10.1016/j.nbd.2014.10.019] [Citation(s) in RCA: 177] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Revised: 10/10/2014] [Accepted: 10/22/2014] [Indexed: 12/14/2022] Open
Abstract
There are growing concerns about potential delayed, neuropsychiatric consequences (e.g, cognitive decline, mood or anxiety disorders) of sports-related traumatic brain injury (TBI). Autopsy studies of brains from a limited number of former athletes have described characteristic, pathologic changes of chronic traumatic encephalopathy (CTE) leading to questions about the relationship between these pathologic and the neuropsychiatric disturbances seen in former athletes. Research in this area will depend on in vivo methods that characterize molecular changes in the brain, linking CTE and other sports-related pathologies with delayed emergence of neuropsychiatric symptoms. In this pilot project we studied former National Football League (NFL) players using new neuroimaging techniques and clinical measures of cognitive functioning. We hypothesized that former NFL players would show molecular and structural changes in medial temporal and parietal lobe structures as well as specific cognitive deficits, namely those of verbal learning and memory. We observed a significant increase in binding of [(11)C]DPA-713 to the translocator protein (TSPO), a marker of brain injury and repair, in several brain regions, such as the supramarginal gyrus and right amygdala, in 9 former NFL players compared to 9 age-matched, healthy controls. We also observed significant atrophy of the right hippocampus. Finally, we report that these same former players had varied performance on a test of verbal learning and memory, suggesting that these molecular and pathologic changes may play a role in cognitive decline. These results suggest that localized brain injury and repair, indicated by increased [(11)C]DPA-713 binding to TSPO, may be linked to history of NFL play. [(11)C]DPA-713 PET is a promising new tool that can be used in future study design to examine further the relationship between TSPO expression in brain injury and repair, selective regional brain atrophy, and the potential link to deficits in verbal learning and memory after NFL play.
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Affiliation(s)
- Jennifer M Coughlin
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins Medical Institutions, Baltimore, MD, USA
| | - Yuchuan Wang
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutions, Baltimore, MD, USA
| | - Cynthia A Munro
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins Medical Institutions, Baltimore, MD, USA.,Department of Neurology, Johns Hopkins Medical Institutions,Baltimore, MD, USA
| | - Shuangchao Ma
- Department of Health Sciences Informatics, Johns Hopkins Medical Institutions, Baltimore, MD, USA
| | - Chen Yue
- Department of Biostatistics, Johns Hopkins Medical Institutions,Baltimore, MD, USA
| | - Shaojie Chen
- Department of Biostatistics, Johns Hopkins Medical Institutions,Baltimore, MD, USA
| | - Raag Airan
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutions, Baltimore, MD, USA
| | - Pearl K Kim
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins Medical Institutions, Baltimore, MD, USA
| | - Ashley V Adams
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins Medical Institutions, Baltimore, MD, USA
| | - Cinthya Garcia
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins Medical Institutions, Baltimore, MD, USA
| | - Cecilia Higgs
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins Medical Institutions, Baltimore, MD, USA
| | - Haris I Sair
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutions, Baltimore, MD, USA
| | - Akira Sawa
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins Medical Institutions, Baltimore, MD, USA
| | - Gwenn Smith
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins Medical Institutions, Baltimore, MD, USA
| | - Constantine G Lyketsos
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins Medical Institutions, Baltimore, MD, USA
| | - Brian Caffo
- Department of Biostatistics, Johns Hopkins Medical Institutions,Baltimore, MD, USA
| | - Michael Kassiou
- School of Chemistry, The University of Sydney, NSW 2006, Sydney, Australia.,Discipline of Medical Radiation Sciences, The University of Sydney, NSW 2006, Sydney, Australia
| | - Tomas R Guilarte
- Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, NY, USA
| | - Martin G Pomper
- 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
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94
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Chua SW, Kassiou M, Ittner LM. The translocator protein as a drug target in Alzheimer's disease. Expert Rev Neurother 2014; 14:439-48. [PMID: 24625007 DOI: 10.1586/14737175.2014.896201] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The translocator protein (TSPO) recently emerged as a potential drug target in Alzheimer's disease (AD). This has been fuelled mainly by positron emission topography studies that show the upregulation of TSPO in AD, especially in relation to microgliosis and astrogliosis in amyloid-β and tau pathology. Although data as to the exact role of TSPO in AD is still inconclusive, TSPO appears to be involved in neuroinflammatory processes and AD has been shown to involve substantial inflammation. Therefore, further development and investigation of the pharmacological effect of TSPO ligands in AD pathology are warranted.
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Affiliation(s)
- Sook W Chua
- Dementia Research Unit, School of Medical Sciences, Wallace Wurth Building, University of New South Wales, Sydney, NSW 2052, Australia
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95
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Midzak A, Papadopoulos V. Binding domain-driven intracellular trafficking of sterols for synthesis of steroid hormones, bile acids and oxysterols. Traffic 2014; 15:895-914. [PMID: 24890942 DOI: 10.1111/tra.12177] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2014] [Revised: 05/28/2014] [Accepted: 05/28/2014] [Indexed: 12/16/2022]
Abstract
Steroid hormones, bioactive oxysterols and bile acids are all derived from the biological metabolism of lipid cholesterol. The enzymatic pathways generating these compounds have been an area of intense research for almost a century, as cholesterol and its metabolites have substantial impacts on human health. Owing to its high degree of hydrophobicity and the chemical properties that it confers to biological membranes, the distribution of cholesterol in cells is tightly controlled, with subcellular organelles exhibiting highly divergent levels of cholesterol. The manners in which cells maintain such sterol distributions are of great interest in the study of steroid and bile acid synthesis, as limiting cholesterol substrate to the enzymatic pathways is the principal mechanism by which production of steroids and bile acids is regulated. The mechanisms by which cholesterol moves within cells, however, remain poorly understood. In this review, we examine the subcellular machinery involved in cholesterol metabolism to steroid hormones and bile acid, relating it to both lipid- and protein-based mechanisms facilitating intracellular and intraorganellar cholesterol movement and delivery to these pathways. In particular, we examine evidence for the involvement of specific protein domains involved in cholesterol binding, which impact cholesterol movement and metabolism in steroidogenesis and bile acid synthesis. A better understanding of the physical mechanisms by which these protein- and lipid-based systems function is of fundamental importance to understanding physiological homeostasis and its perturbation.
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Affiliation(s)
- Andrew Midzak
- Research Institute of the McGill University Health Centre, McGill University, Montreal, Quebec, Canada
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96
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R K, D M A, C N, S N W, C D. Oxidative imbalance and anxiety disorders. Curr Neuropharmacol 2014; 12:193-204. [PMID: 24669212 PMCID: PMC3964749 DOI: 10.2174/1570159x11666131120223530] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2013] [Revised: 05/15/2013] [Accepted: 11/02/2013] [Indexed: 01/22/2023] Open
Abstract
The oxidative imbalance appears to have an important role in anxiety development. Studies in both humans and animals have shown a strong correlation between anxiety and oxidative stress. In humans, for example, the increased malondialdehyde levels and discrepancies in antioxidant enzymes in erythrocytes have been observed. In animals, several studies also show that anxiety-like behavior is related to the oxidative imbalance. Moreover, anxiety-like behavior can be caused by pharmacological-induced oxidative stress. Studies using knockout or overexpression of antioxidant enzymes have shown a relationship between anxiety-like behavior and oxidative stress. Related factors of oxidative stress that could influence anxious behavior are revised, including impaired function of different mitochondrial proteins, inflammatory cytokines, and neurotrophic factors. It has been suggested that a therapy specifically focus in reducing reactive species production may have a beneficial effect in reducing anxiety. However, the neurobiological pathways underlying the effect of oxidative stress on anxiety symptoms are not fully comprehended. The challenge now is to identify the oxidative stress mechanisms likely to be involved in the induction of anxiety symptoms. Understanding these pathways could help to clarify the neurobiology of the anxiety disorder and provide tools for new discovery in therapies and preventive strategies.
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Affiliation(s)
- Krolow R
- Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, UFRGS, Porto Alegre, Rio Grande do Sul, Brazil
| | - Arcego D M
- Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, UFRGS, Porto Alegre, Rio Grande do Sul, Brazil
| | - Noschang C
- Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, UFRGS, Porto Alegre, Rio Grande do Sul, Brazil
| | - Weis S N
- Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, UFRGS, Porto Alegre, Rio Grande do Sul, Brazil
| | - Dalmaz C
- Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, UFRGS, Porto Alegre, Rio Grande do Sul, Brazil
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Signal Transduction in Astrocytes during Chronic or Acute Treatment with Drugs (SSRIs, Antibipolar Drugs, GABA-ergic Drugs, and Benzodiazepines) Ameliorating Mood Disorders. JOURNAL OF SIGNAL TRANSDUCTION 2014; 2014:593934. [PMID: 24707399 PMCID: PMC3953578 DOI: 10.1155/2014/593934] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/30/2013] [Accepted: 12/16/2013] [Indexed: 01/29/2023]
Abstract
Chronic treatment with fluoxetine or other so-called serotonin-specific reuptake inhibitor antidepressants (SSRIs) or with a lithium salt “lithium”, carbamazepine, or valproic acid, the three classical antibipolar drugs, exerts a multitude of effects on astrocytes, which in turn modulate astrocyte-neuronal interactions and brain function. In the case of the SSRIs, they are to a large extent due to 5-HT2B-mediated upregulation and editing of genes. These alterations induce alteration in effects of cPLA2, GluK2, and the 5-HT2B receptor, probably including increases in both glucose metabolism and glycogen turnover, which in combination have therapeutic effect on major depression. The ability of increased levels of extracellular K+ to increase [Ca2+]i is increased as a sign of increased K+-induced excitability in astrocytes. Acute anxiolytic drug treatment with benzodiazepines or GABAA receptor stimulation has similar glycogenolysis-enhancing effects. The antibipolar drugs induce intracellular alkalinization in astrocytes with lithium acting on one acid extruder and carbamazepine and valproic acid on a different acid extruder. They inhibit K+-induced and transmitter-induced increase of astrocytic [Ca2+]i and thereby probably excitability. In several cases, they exert different changes in gene expression than SSRIs, determined both in cultured astrocytes and in freshly isolated astrocytes from drug-treated animals.
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Morohaku K, Pelton SH, Daugherty DJ, Butler WR, Deng W, Selvaraj V. Translocator protein/peripheral benzodiazepine receptor is not required for steroid hormone biosynthesis. Endocrinology 2014; 155:89-97. [PMID: 24174323 PMCID: PMC3868810 DOI: 10.1210/en.2013-1556] [Citation(s) in RCA: 186] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Molecular events that regulate cellular biosynthesis of steroid hormones have been a topic of intense research for more than half a century. It has been established that transport of cholesterol into the mitochondria forms the rate-limiting step in steroid hormone production. In current models, both the steroidogenic acute regulatory protein (StAR) and the translocator protein (TSPO) have been implicated to have a concerted and indispensable effort in this cholesterol transport. Deletion of StAR in mice resulted in a critical failure of steroid hormone production, but deletion of TSPO in mice was found to be embryonic lethal. As a result, the role of TSPO in cholesterol transport has been established only using pharmacologic and genetic tools in vitro. To allow us to explore in more detail the function of TSPO in cell type-specific experimental manipulations in vivo, we generated mice carrying TSPO floxed alleles (TSPOfl/fl). In this study we made conditional knockout mice (TSPOcΔ/Δ) with TSPO deletion in testicular Leydig cells by crossing with an anti-Mullerian hormone receptor type II cre/+ mouse line. Genetic ablation of TSPO in steroidogenic Leydig cells in mice did not affect testosterone production, gametogenesis, and reproduction. Expression of StAR, cytochrome P450 side chain cleavage enzyme, 3β-hydroxysteroid dehydrogenase/Δ5-Δ4 isomerase type I, and TSPO2 in TSPOcΔ/Δ testis was unaffected. These results challenge the prevailing dogma that claims an essential role for TSPO in steroid hormone biosynthesis and force reexamination of functional interpretations made for this protein. This is the first study examining conditional TSPO gene deletion in mice. The results show that TSPO function is not essential for steroid hormone biosynthesis.
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Affiliation(s)
- Kanako Morohaku
- Department of Animal Science, College of Agriculture and Life Sciences (K.M., S.H.P., W.R.B., V.S.), Cornell University, Ithaca, New York 14853; and Department of Biochemistry and Molecular Medicine, School of Medicine (D.J.D., W.D.), University of California at Davis, Sacramento, California 95618
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Abstract
Ligands of the translocator protein (TSPO) elicit pleiotropic neuroprotective effects that represent emerging treatment strategies for several neurodegenerative conditions. To investigate the potential of TSPO as a therapeutic target for Alzheimer's disease (AD), the current study assessed the effects of the TSPO ligand Ro5-4864 on the development of neuropathology in 3xTgAD mice. The effects of the TSPO ligand on neurosteroidogenesis and AD-related neuropathology, including β-amyloid accumulation, gliosis, and behavioral impairment, were examined under both early intervention (7-month-old young-adult male mice with low pathology) and treatment (24-month-old, aged male mice with advanced neuropathology) conditions. Ro5-4864 treatment not only effectively attenuated development of neuropathology and behavioral impairment in young-adult mice but also reversed these indices in aged 3xTgAD mice. Reduced levels of soluble β-amyloid were also observed by the combination of TSPO ligands Ro5-4864 and PK11195 in nontransgenic mice. These findings suggest that TSPO is a promising target for the development of pleiotropic treatment strategies for the management of AD.
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