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Mayer FP, Stewart A, Varman DR, Moritz AE, Foster JD, Owens AW, Areal LB, Gowrishankar R, Velez M, Wickham K, Phelps H, Katamish R, Rabil M, Jayanthi LD, Vaughan RA, Daws LC, Blakely RD, Ramamoorthy S. Kappa Opioid Receptor Antagonism Restores Phosphorylation, Trafficking and Behavior induced by a Disease Associated Dopamine Transporter Variant. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.05.03.539310. [PMID: 37205452 PMCID: PMC10187322 DOI: 10.1101/2023.05.03.539310] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Aberrant dopamine (DA) signaling is implicated in schizophrenia, bipolar disorder (BPD), autism spectrum disorder (ASD), substance use disorder, and attention-deficit/hyperactivity disorder (ADHD). Treatment of these disorders remains inadequate, as exemplified by the therapeutic use of d-amphetamine and methylphenidate for the treatment of ADHD, agents with high abuse liability. In search for an improved and non-addictive therapeutic approach for the treatment of DA-linked disorders, we utilized a preclinical mouse model expressing the human DA transporter (DAT) coding variant DAT Val559, previously identified in individuals with ADHD, ASD, or BPD. DAT Val559, like several other disease-associated variants of DAT, exhibits anomalous DA efflux (ADE) that can be blocked by d-amphetamine and methylphenidate. Kappa opioid receptors (KORs) are expressed by DA neurons and modulate DA release and clearance, suggesting that targeting KORs might also provide an alternative approach to normalizing DA-signaling disrupted by perturbed DAT function. Here we demonstrate that KOR stimulation leads to enhanced surface trafficking and phosphorylation of Thr53 in wildtype DAT, effects achieved constitutively by the Val559 mutant. Moreover, these effects can be rescued by KOR antagonism of DAT Val559 in ex vivo preparations. Importantly, KOR antagonism also corrected in vivo DA release as well as sex-dependent behavioral abnormalities observed in DAT Val559 mice. Given their low abuse liability, our studies with a construct valid model of human DA associated disorders reinforce considerations of KOR antagonism as a pharmacological strategy to treat DA associated brain disorders.
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Affiliation(s)
- Felix P. Mayer
- Department of Biomedical Science, Charles E. Schmidt College of Medicine, Florida Atlantic University, Jupiter, FL, USA
- Stiles-Nicholson Brain Institute, Florida Atlantic University, Jupiter, FL, USA
| | - Adele Stewart
- Department of Biomedical Science, Charles E. Schmidt College of Medicine, Florida Atlantic University, Jupiter, FL, USA
- Stiles-Nicholson Brain Institute, Florida Atlantic University, Jupiter, FL, USA
| | - Durairaj Ragu Varman
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, VA, USA
| | - Amy E. Moritz
- Department of Biomedical Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, ND, USA
| | - James D. Foster
- Department of Biomedical Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, ND, USA
| | - Anthony W. Owens
- Department of Cellular and Integrative Physiology, University of Texas Health Science Center at San Antonio, TX, USA
| | - Lorena B. Areal
- Department of Biomedical Science, Charles E. Schmidt College of Medicine, Florida Atlantic University, Jupiter, FL, USA
| | - Raajaram Gowrishankar
- Department of Biomedical Science, Charles E. Schmidt College of Medicine, Florida Atlantic University, Jupiter, FL, USA
| | - Michelle Velez
- Department of Biomedical Science, Charles E. Schmidt College of Medicine, Florida Atlantic University, Jupiter, FL, USA
| | - Kyria Wickham
- Department of Biomedical Science, Charles E. Schmidt College of Medicine, Florida Atlantic University, Jupiter, FL, USA
| | - Hannah Phelps
- Department of Biomedical Science, Charles E. Schmidt College of Medicine, Florida Atlantic University, Jupiter, FL, USA
| | - Rania Katamish
- Department of Biomedical Science, Charles E. Schmidt College of Medicine, Florida Atlantic University, Jupiter, FL, USA
| | - Maximilian Rabil
- Department of Biomedical Science, Charles E. Schmidt College of Medicine, Florida Atlantic University, Jupiter, FL, USA
| | - Lankupalle D. Jayanthi
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, VA, USA
| | - Roxanne A. Vaughan
- Department of Biomedical Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, ND, USA
| | - Lynette C. Daws
- Department of Cellular and Integrative Physiology, University of Texas Health Science Center at San Antonio, TX, USA
- Department of Pharmacology, University of Texas Health Science Center, San Antonio, TX, USA
| | - Randy D. Blakely
- Department of Biomedical Science, Charles E. Schmidt College of Medicine, Florida Atlantic University, Jupiter, FL, USA
- Stiles-Nicholson Brain Institute, Florida Atlantic University, Jupiter, FL, USA
| | - Sammanda Ramamoorthy
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, VA, USA
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2
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Suzuki N, Hiraide S, Shikanai H, Isshiki T, Yamaguchi T, Izumi T, Iizuka K. Impaired monoamine neural system in the mPFC of SHRSP/Ezo as an animal model of attention-deficit/hyperactivity disorder. J Pharmacol Sci 2024; 154:61-71. [PMID: 38246729 DOI: 10.1016/j.jphs.2023.12.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2023] [Revised: 11/16/2023] [Accepted: 12/07/2023] [Indexed: 01/23/2024] Open
Abstract
Attention-deficit/hyperactivity disorder (ADHD) is the most common childhood-onset psychiatric disorder. We investigated the effects of systemic administration of monoamine reuptake inhibitors on long-term potentiation (LTP) formation and monoamine release in the medial prefrontal cortex (mPFC) of the stroke-prone spontaneously hypertensive rat (SHRSP)/Ezo, an animal model of ADHD, and its genetic control, Wistar Kyoto (WKY)/Ezo, to elucidate the functional changes in the mPFC monoamine neural system. Methylphenidate (dopamine (DA) and noradrenaline (NA) reuptake inhibitor) and desipramine (NA reuptake inhibitor) improved LTP formation defects in the mPFC of SHRSP/Ezo, suggesting that NA or both DA and NA are required for improvement of impaired LTP. Methylphenidate increased mPFC DA in both WKY/Ezo and SHRSP/Ezo, but the increase was greater in the former. GBR-12909 (DA reuptake inhibitor) increased mPFC DA in WKY/Ezo but had no effect in SHRSP/Ezo. This may be because DA transporter in SHRSP/Ezo is functionally impaired and contributes less to DA reuptake, so its inhibition did not increase DA level. Meanwhile, basal DA levels in the mPFC of SHRSP/Ezo were paradoxically decreased. These results suggest that functional changes in the DA and NA neural system in the frontal lobe are involved in the pathology of ADHD.
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Affiliation(s)
- Naoya Suzuki
- Department of Pharmacology, Faculty of Pharmaceutical Sciences, Health Sciences University of Hokkaido, 1757 Kanazawa, Ishikari-Tobetsu, Hokkaido, 061-0293, Japan
| | - Sachiko Hiraide
- Department of Pharmacology, Faculty of Pharmaceutical Sciences, Health Sciences University of Hokkaido, 1757 Kanazawa, Ishikari-Tobetsu, Hokkaido, 061-0293, Japan
| | - Hiroki Shikanai
- Department of Pharmacology, Faculty of Pharmaceutical Sciences, Health Sciences University of Hokkaido, 1757 Kanazawa, Ishikari-Tobetsu, Hokkaido, 061-0293, Japan; Advanced Research Promotion Center, Health Sciences University of Hokkaido, 1757 Kanazawa, Ishikari-Tobetsu, Hokkaido, 061-0293, Japan.
| | - Takeru Isshiki
- Department of Pharmacology, Faculty of Pharmaceutical Sciences, Health Sciences University of Hokkaido, 1757 Kanazawa, Ishikari-Tobetsu, Hokkaido, 061-0293, Japan
| | - Taku Yamaguchi
- Department of Pharmacotherapeutics and Neuropsychopharmacology, Faculty of Pharmaceutical Sciences, Nagasaki International University, Nagasaki, 2825-7 Huis Ten Bosch Sasebo, Nagasaki, 859-3298, Japan
| | - Takeshi Izumi
- Department of Pharmacology, Faculty of Pharmaceutical Sciences, Health Sciences University of Hokkaido, 1757 Kanazawa, Ishikari-Tobetsu, Hokkaido, 061-0293, Japan; Advanced Research Promotion Center, Health Sciences University of Hokkaido, 1757 Kanazawa, Ishikari-Tobetsu, Hokkaido, 061-0293, Japan
| | - Kenji Iizuka
- Department of Pharmacology, Faculty of Pharmaceutical Sciences, Health Sciences University of Hokkaido, 1757 Kanazawa, Ishikari-Tobetsu, Hokkaido, 061-0293, Japan
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3
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Ng J, Barral S, Waddington SN, Kurian MA. Dopamine Transporter Deficiency Syndrome (DTDS): Expanding the Clinical Phenotype and Precision Medicine Approaches. Cells 2023; 12:1737. [PMID: 37443770 PMCID: PMC10341083 DOI: 10.3390/cells12131737] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2023] [Revised: 06/16/2023] [Accepted: 06/23/2023] [Indexed: 07/15/2023] Open
Abstract
Infantile parkinsonism-dystonia due to dopamine transporter deficiency syndrome (DTDS) is an ultrarare childhood movement disorder caused by biallelic loss-of-function mutations in the SLC6A3 gene. Advances in genomic analysis have revealed an evolving spectrum of SLC6A3-related neurological and neuropsychiatric disorders. Since the initial clinical and genetic characterisation of DTDS in 2009, there have been thirty-one published cases with a variety of protein-truncating variants (nonsense variants, splice-site changes, and deletions) and missense changes. Amino acid substitutions result in mutant proteins with impaired dopamine transporter function due to reduced transporter activity, impaired dopamine binding, reduced cell-surface expression, and aberrant posttranslational protein modification with impaired glycosylation. In this review, we provide an overview of the expanding clinical phenotype of DTDS and the precision therapies in development, including pharmacochaperones and gene therapy.
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Affiliation(s)
- Joanne Ng
- Gene Transfer Technology Group, EGA UCL Institute for Women’s Health, University College London, London WC1E 6HX, UK; (J.N.); (S.N.W.)
- Genetic Therapy Accelerator Centre, Queens Square Institute of Neurology, University College London, London WC1N 3BG, UK
| | - Serena Barral
- Developmental Neurosciences, Zayed Centre for Research into Rare Disease in Children, GOS UCL Institute of Child Health, University College London, London WC1N 1DZ, UK;
| | - Simon N. Waddington
- Gene Transfer Technology Group, EGA UCL Institute for Women’s Health, University College London, London WC1E 6HX, UK; (J.N.); (S.N.W.)
- Wits/SAMRC Antiviral Gene Therapy Research Unit, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg 2193, South Africa
| | - Manju A. Kurian
- Developmental Neurosciences, Zayed Centre for Research into Rare Disease in Children, GOS UCL Institute of Child Health, University College London, London WC1N 1DZ, UK;
- Paediatric Neurology, Great Ormond Street Hospital for Children, London WC1N 3JH, UK
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4
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Savchenko A, Targa G, Fesenko Z, Leo D, Gainetdinov RR, Sukhanov I. Dopamine Transporter Deficient Rodents: Perspectives and Limitations for Neuroscience. Biomolecules 2023; 13:806. [PMID: 37238676 PMCID: PMC10216310 DOI: 10.3390/biom13050806] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Revised: 05/04/2023] [Accepted: 05/05/2023] [Indexed: 05/28/2023] Open
Abstract
The key element of dopamine (DA) neurotransmission is undoubtedly DA transporter (DAT), a transmembrane protein responsible for the synaptic reuptake of the mediator. Changes in DAT's function can be a key mechanism of pathological conditions associated with hyperdopaminergia. The first strain of gene-modified rodents with a lack of DAT were created more than 25 years ago. Such animals are characterized by increased levels of striatal DA, resulting in locomotor hyperactivity, increased levels of motor stereotypes, cognitive deficits, and other behavioral abnormalities. The administration of dopaminergic and pharmacological agents affecting other neurotransmitter systems can mitigate those abnormalities. The main purpose of this review is to systematize and analyze (1) known data on the consequences of changes in DAT expression in experimental animals, (2) results of pharmacological studies in these animals, and (3) to estimate the validity of animals lacking DAT as models for discovering new treatments of DA-related disorders.
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Affiliation(s)
- Artem Savchenko
- Valdman Institute of Pharmacology, Pavlov First St. Petersburg State Medical University, Lev Tolstoy Str. 6-8, 197022 St. Petersburg, Russia;
| | - Giorgia Targa
- Department of Pharmacological and Biomolecular Sciences “Rodolfo Paoletti”, Università degli Studi di Milano, Via Balzaretti 9, 20133 Milano, Italy
| | - Zoia Fesenko
- Institute of Translational Biomedicine, St. Petersburg State University, 7/9 Universitetskaya Emb., 199034 St. Petersburg, Russia
| | - Damiana Leo
- Department of Neurosciences, University of Mons, 7000 Mons, Belgium
| | - Raul R. Gainetdinov
- Institute of Translational Biomedicine, St. Petersburg State University, 7/9 Universitetskaya Emb., 199034 St. Petersburg, Russia
- St. Petersburg University Hospital, St. Petersburg State University, Fontanka River Emb. 154, 190121 St. Petersburg, Russia
| | - Ilya Sukhanov
- Valdman Institute of Pharmacology, Pavlov First St. Petersburg State Medical University, Lev Tolstoy Str. 6-8, 197022 St. Petersburg, Russia;
- St. Petersburg University Hospital, St. Petersburg State University, Fontanka River Emb. 154, 190121 St. Petersburg, Russia
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Kearney PJ, Bolden NC, Kahuno E, Conklin TL, Martin GE, Lubec G, Melikian HE. Presynaptic Gq-coupled receptors drive biphasic dopamine transporter trafficking that modulates dopamine clearance and motor function. J Biol Chem 2023; 299:102900. [PMID: 36640864 PMCID: PMC9943899 DOI: 10.1016/j.jbc.2023.102900] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2022] [Revised: 12/23/2022] [Accepted: 01/03/2023] [Indexed: 01/13/2023] Open
Abstract
Extracellular dopamine (DA) levels are constrained by the presynaptic DA transporter (DAT), a major psychostimulant target. Despite its necessity for DA neurotransmission, DAT regulation in situ is poorly understood, and it is unknown whether regulated DAT trafficking impacts dopaminergic signaling and/or behaviors. Leveraging chemogenetics and conditional gene silencing, we found that activating presynaptic Gq-coupled receptors, either hM3Dq or mGlu5, drove rapid biphasic DAT membrane trafficking in ex vivo striatal slices, with region-specific differences between ventral and dorsal striata. DAT insertion required D2 DA autoreceptors and intact retromer, whereas DAT retrieval required PKC activation and Rit2. Ex vivo voltammetric studies revealed that DAT trafficking impacts DA clearance. Furthermore, dopaminergic mGlu5 silencing elevated DAT surface expression and abolished motor learning, which was rescued by inhibiting DAT with a subthreshold CE-158 dose. We discovered that presynaptic DAT trafficking is complex, multimodal, and region specific, and for the first time, we identified cell autonomous mechanisms that govern presynaptic DAT tone. Importantly, the findings are consistent with a role for regulated DAT trafficking in DA clearance and motor function.
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Affiliation(s)
- Patrick J. Kearney
- Brudnick Neuropsychiatric Research Institute, Department of Neurobiology, UMASS Chan Medical School, Worcester, Massachusetts, USA,Morningside Graduate School of Biomedical Sciences, UMASS Chan Medical School, Worcester, Massachusetts, USA
| | - Nicholas C. Bolden
- Brudnick Neuropsychiatric Research Institute, Department of Neurobiology, UMASS Chan Medical School, Worcester, Massachusetts, USA,Morningside Graduate School of Biomedical Sciences, UMASS Chan Medical School, Worcester, Massachusetts, USA
| | - Elizabeth Kahuno
- Brudnick Neuropsychiatric Research Institute, Department of Neurobiology, UMASS Chan Medical School, Worcester, Massachusetts, USA
| | - Tucker L. Conklin
- Brudnick Neuropsychiatric Research Institute, Department of Neurobiology, UMASS Chan Medical School, Worcester, Massachusetts, USA
| | - Gilles E. Martin
- Brudnick Neuropsychiatric Research Institute, Department of Neurobiology, UMASS Chan Medical School, Worcester, Massachusetts, USA
| | - Gert Lubec
- Department of Neuroproteomics, Paracelsus Private Medical University, Salzburg, Austria
| | - Haley E. Melikian
- Brudnick Neuropsychiatric Research Institute, Department of Neurobiology, UMASS Chan Medical School, Worcester, Massachusetts, USA,For correspondence: Haley E. Melikian
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Cabana-Domínguez J, Antón-Galindo E, Fernàndez-Castillo N, Singgih EL, O'Leary A, Norton WH, Strekalova T, Schenck A, Reif A, Lesch KP, Slattery D, Cormand B. The translational genetics of ADHD and related phenotypes in model organisms. Neurosci Biobehav Rev 2023; 144:104949. [PMID: 36368527 DOI: 10.1016/j.neubiorev.2022.104949] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Revised: 11/02/2022] [Accepted: 11/05/2022] [Indexed: 11/10/2022]
Abstract
Attention-deficit/hyperactivity disorder (ADHD) is a highly prevalent neurodevelopmental disorder resulting from the interaction between genetic and environmental risk factors. It is well known that ADHD co-occurs frequently with other psychiatric disorders due, in part, to shared genetics factors. Although many studies have contributed to delineate the genetic landscape of psychiatric disorders, their specific molecular underpinnings are still not fully understood. The use of animal models can help us to understand the role of specific genes and environmental stimuli-induced epigenetic modifications in the pathogenesis of ADHD and its comorbidities. The aim of this review is to provide an overview on the functional work performed in rodents, zebrafish and fruit fly and highlight the generated insights into the biology of ADHD, with a special focus on genetics and epigenetics. We also describe the behavioral tests that are available to study ADHD-relevant phenotypes and comorbid traits in these models. Furthermore, we have searched for new models to study ADHD and its comorbidities, which can be useful to test potential pharmacological treatments.
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Affiliation(s)
- Judit Cabana-Domínguez
- Departament de Genètica, Microbiologia i Estadística, Facultat de Biologia, Universitat de Barcelona, Barcelona, Catalonia, Spain; Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Instituto de Salud Carlos III, Spain; Institut de Biomedicina de la Universitat de Barcelona (IBUB), Barcelona, Catalonia, Spain; Institut de Recerca Sant Joan de Déu (IR-SJD), Esplugues de Llobregat, Catalonia, Spain.
| | - Ester Antón-Galindo
- Departament de Genètica, Microbiologia i Estadística, Facultat de Biologia, Universitat de Barcelona, Barcelona, Catalonia, Spain; Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Instituto de Salud Carlos III, Spain; Institut de Biomedicina de la Universitat de Barcelona (IBUB), Barcelona, Catalonia, Spain; Institut de Recerca Sant Joan de Déu (IR-SJD), Esplugues de Llobregat, Catalonia, Spain
| | - Noèlia Fernàndez-Castillo
- Departament de Genètica, Microbiologia i Estadística, Facultat de Biologia, Universitat de Barcelona, Barcelona, Catalonia, Spain; Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Instituto de Salud Carlos III, Spain; Institut de Biomedicina de la Universitat de Barcelona (IBUB), Barcelona, Catalonia, Spain; Institut de Recerca Sant Joan de Déu (IR-SJD), Esplugues de Llobregat, Catalonia, Spain
| | - Euginia L Singgih
- Department of Human Genetics, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Aet O'Leary
- Department of Psychiatry, Psychosomatic Medicine and Psychotherapy, University Hospital, Goethe University, Frankfurt, Germany; Division of Neuropsychopharmacology, Department of Psychology, University of Tartu, Tartu, Estonia
| | - William Hg Norton
- Department of Genetics and Genome Biology, University of Leicester, Leicester, UK
| | - Tatyana Strekalova
- Division of Molecular Psychiatry, Center of Mental Health, University of Würzburg, Würzburg, Germany, and Department of Neuropsychology and Psychiatry, School for Mental Health and Neuroscience (MHeNS), Maastricht University, Maastricht, the Netherlands
| | - Annette Schenck
- Department of Human Genetics, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Andreas Reif
- Department of Psychiatry, Psychosomatic Medicine and Psychotherapy, University Hospital, Goethe University, Frankfurt, Germany
| | - Klaus-Peter Lesch
- Division of Molecular Psychiatry, Center of Mental Health, University of Würzburg, Würzburg, Germany, and Department of Neuropsychology and Psychiatry, School for Mental Health and Neuroscience (MHeNS), Maastricht University, Maastricht, the Netherlands
| | - David Slattery
- Department of Psychiatry, Psychosomatic Medicine and Psychotherapy, University Hospital, Goethe University, Frankfurt, Germany
| | - Bru Cormand
- Departament de Genètica, Microbiologia i Estadística, Facultat de Biologia, Universitat de Barcelona, Barcelona, Catalonia, Spain; Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Instituto de Salud Carlos III, Spain; Institut de Biomedicina de la Universitat de Barcelona (IBUB), Barcelona, Catalonia, Spain; Institut de Recerca Sant Joan de Déu (IR-SJD), Esplugues de Llobregat, Catalonia, Spain.
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Nepal B, Das S, Reith ME, Kortagere S. Overview of the structure and function of the dopamine transporter and its protein interactions. Front Physiol 2023; 14:1150355. [PMID: 36935752 PMCID: PMC10020207 DOI: 10.3389/fphys.2023.1150355] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2023] [Accepted: 02/21/2023] [Indexed: 03/06/2023] Open
Abstract
The dopamine transporter (DAT) plays an integral role in dopamine neurotransmission through the clearance of dopamine from the extracellular space. Dysregulation of DAT is central to the pathophysiology of numerous neuropsychiatric disorders and as such is an attractive therapeutic target. DAT belongs to the solute carrier family 6 (SLC6) class of Na+/Cl- dependent transporters that move various cargo into neurons against their concentration gradient. This review focuses on DAT (SCL6A3 protein) while extending the narrative to the closely related transporters for serotonin and norepinephrine where needed for comparison or functional relevance. Cloning and site-directed mutagenesis experiments provided early structural knowledge of DAT but our contemporary understanding was achieved through a combination of crystallization of the related bacterial transporter LeuT, homology modeling, and subsequently the crystallization of drosophila DAT. These seminal findings enabled a better understanding of the conformational states involved in the transport of substrate, subsequently aiding state-specific drug design. Post-translational modifications to DAT such as phosphorylation, palmitoylation, ubiquitination also influence the plasma membrane localization and kinetics. Substrates and drugs can interact with multiple sites within DAT including the primary S1 and S2 sites involved in dopamine binding and novel allosteric sites. Major research has centered around the question what determines the substrate and inhibitor selectivity of DAT in comparison to serotonin and norepinephrine transporters. DAT has been implicated in many neurological disorders and may play a role in the pathology of HIV and Parkinson's disease via direct physical interaction with HIV-1 Tat and α-synuclein proteins respectively.
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Affiliation(s)
- Binod Nepal
- Department of Microbiology and Immunology, Drexel University College of Medicine, Philadelphia, PA, United States
| | - Sanjay Das
- Department of Microbiology and Immunology, Drexel University College of Medicine, Philadelphia, PA, United States
| | - Maarten E. Reith
- Department of Psychiatry, New York University School of Medicine, New York City, NY, United States
| | - Sandhya Kortagere
- Department of Microbiology and Immunology, Drexel University College of Medicine, Philadelphia, PA, United States
- *Correspondence: Sandhya Kortagere,
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8
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Male DAT Val559 Mice Exhibit Compulsive Behavior under Devalued Reward Conditions Accompanied by Cellular and Pharmacological Changes. Cells 2022; 11:cells11244059. [PMID: 36552823 PMCID: PMC9777203 DOI: 10.3390/cells11244059] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Revised: 12/05/2022] [Accepted: 12/12/2022] [Indexed: 12/23/2022] Open
Abstract
Identified across multiple psychiatric disorders, the dopamine (DA) transporter (DAT) Ala559Val substitution triggers non-vesicular, anomalous DA efflux (ADE), perturbing DA neurotransmission and behavior. We have shown that DAT Val559 mice display a waiting impulsivity and changes in cognitive performance associated with enhanced reward motivation. Here, utilizing a within-subject, lever-pressing paradigm designed to bias the formation of goal-directed or habitual behavior, we demonstrate that DAT Val559 mice modulate their nose poke behavior appropriately to match context, but demonstrate a perseverative checking behavior. Although DAT Val559 mice display no issues with the cognitive flexibility required to acquire and re-learn a visual pairwise discrimination task, devaluation of reward evoked habitual reward seeking in DAT Val559 mutants in operant tasks regardless of reinforcement schedule. The direct DA agonist apomorphine also elicits locomotor stereotypies in DAT Val559, but not WT mice. Our observation that dendritic spine density is increased in the dorsal medial striatum (DMS) of DAT Val559 mice speaks to an imbalance in striatal circuitry that might underlie the propensity of DAT Val559 mutants to exhibit compulsive behaviors when reward is devalued. Thus, DAT Val559 mice represent a model for dissection of how altered DA signaling perturbs circuits that normally balance habitual and goal-directed behaviors.
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9
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Barata-Antunes C, Talaia G, Broutzakis G, Ribas D, De Beule P, Casal M, Stefan CJ, Diallinas G, Paiva S. Interactions of cytosolic tails in the Jen1 carboxylate transporter are critical for trafficking and transport activity. J Cell Sci 2022; 135:275079. [PMID: 35437607 DOI: 10.1242/jcs.260059] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Accepted: 04/05/2022] [Indexed: 12/26/2022] Open
Abstract
Plasma membrane (PM) transporters of the major facilitator superfamily (MFS) are essential for cell metabolism, growth and response to stress or drugs. In Saccharomyces cerevisiae, Jen1 is a monocarboxylate/H+ symporter that provides a model to dissect the molecular details underlying cellular expression, transport mechanism and turnover of MFS transporters. Here, we present evidence revealing novel roles of the cytosolic N- and C-termini of Jen1 in its biogenesis, PM stability and transport activity, using functional analyses of Jen1 truncations and chimeric constructs with UapA, an endocytosis-insensitive transporter of Aspergillus nidulans. Our results show that both N- and C-termini are critical for Jen1 trafficking to the PM, transport activity and endocytosis. Importantly, we provide evidence that Jen1 N- and C-termini undergo transport-dependent dynamic intramolecular interactions, which affect the transport activity and turnover of Jen1. Our results support an emerging concept where the cytoplasmic termini of PM transporters control transporter cell surface stability and function through flexible intramolecular interactions with each other. These findings might be extended to other MFS members to understand conserved and evolving mechanisms underlying transporter structure-function relationships. This article has an associated First Person interview with the first authors of the paper.
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Affiliation(s)
- Cláudia Barata-Antunes
- Centre of Molecular and Environmental Biology, Department of Biology, University of Minho, 4710-057, Braga, Portugal.,Institute of Science and Innovation for Bio-Sustainability (IB-S), University of Minho, 4710-057, Braga, Portugal
| | - Gabriel Talaia
- Centre of Molecular and Environmental Biology, Department of Biology, University of Minho, 4710-057, Braga, Portugal.,Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06510, USA
| | - George Broutzakis
- Department of Biology, National and Kapodistrian University of Athens, Panepistimiopolis 15784, Athens, Greece
| | - David Ribas
- Centre of Molecular and Environmental Biology, Department of Biology, University of Minho, 4710-057, Braga, Portugal
| | - Pieter De Beule
- International Iberian Nanotechnology Laboratory, Avenida Mestre José Veiga s/n, Braga, Portugal
| | - Margarida Casal
- Centre of Molecular and Environmental Biology, Department of Biology, University of Minho, 4710-057, Braga, Portugal.,Institute of Science and Innovation for Bio-Sustainability (IB-S), University of Minho, 4710-057, Braga, Portugal
| | - Christopher J Stefan
- MRC Laboratory for Molecular Cell Biology, University College London, Gower Street, London WC1E 6BT, UK
| | - George Diallinas
- Department of Biology, National and Kapodistrian University of Athens, Panepistimiopolis 15784, Athens, Greece.,Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology, 70013, Heraklion, Greece
| | - Sandra Paiva
- Centre of Molecular and Environmental Biology, Department of Biology, University of Minho, 4710-057, Braga, Portugal.,Institute of Science and Innovation for Bio-Sustainability (IB-S), University of Minho, 4710-057, Braga, Portugal
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10
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Yeh SHH, Tsai CJ, Yu TH, Chiang YH, Lin SZ, Peng NJ, Huang WS. 99mTc-TRODAT-1 SPECT Revealed That Striatal Dopamine Transport Availability Significantly Decreases in Late Mid-Aged Healthy Taiwanese and Then Remains Stable. Clin Nucl Med 2022; 47:201-208. [PMID: 35081059 PMCID: PMC8820763 DOI: 10.1097/rlu.0000000000004063] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2021] [Revised: 11/12/2021] [Accepted: 11/12/2021] [Indexed: 11/26/2022]
Abstract
OBJECTIVES Neuroimaging studies in the past 20 years have documented an age-related decline in striatal dopamine transporters (DATs), which is a marker of dopaminergic neurodegeneration; however, concerns about ethnic variations in the decline in DAT with age have not been addressed. The purpose of this study was to assess the rate of striatal DAT loss in healthy Taiwanese adults using kit-based 99mTc-TRODAT-1, a radioligand for DAT SPECT. PATIENTS AND METHODS Fifty healthy subjects (mean age ± SD, 63 ± 12 years; range, 30-80 years) were studied. 99mTc-TRODAT-1 was prepared from a lyophilized kit. Brain DAT SPECT imaging was acquired between 165 and 195 minutes postinjection (~740 MBq or 20 mCi) using a dual-head camera equipped with fan-beam collimators (Helix SPX; GE). Specific uptake in the striatum (ST), caudate nucleus (CA), and putamen (PU) were calculated from reconstructed transaxial slices at the level of maximal striatal activity. Occipital cortices were used as reference areas. Data were presented as specific binding ratios. RESULTS Age had a significant moderate to large negative effect on striatal DAT, which declined by -25.7% ± 6.10% between the ages of 30 and 80 years, equivalent to 6.4% loss per decade. The rates of decline in the CA and PU were 6.9% and 7.3% per decade, respectively. CONCLUSIONS This study suggests ethnic variations may not significantly affect the age-related decline in DAT. The data generated in this study could also be used as a reference to estimate DAT loss/occupancy in patients with DAT-related diseases.
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Affiliation(s)
- Skye Hsin-Hsien Yeh
- From the Brain Research Center, National Yang Ming Chaio Tung University
- School of Medicine, National Defense Medical Center
| | - Chi-Jung Tsai
- Department of Nuclear Medicine, Taipei Medical University Hospital
- Department of Nuclear Medicine, Tri-Service General Hospital
| | - Tsung-Hsun Yu
- From the Brain Research Center, National Yang Ming Chaio Tung University
| | | | | | - Nan-Jing Peng
- Department of Nuclear Medicine, Taipei Veterans General Hospital, Taipei, Taiwan
| | - Wen-Sheng Huang
- Department of Nuclear Medicine, Taipei Medical University Hospital
- Department of Nuclear Medicine, Tri-Service General Hospital
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11
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Reith MEA, Kortagere S, Wiers CE, Sun H, Kurian MA, Galli A, Volkow ND, Lin Z. The dopamine transporter gene SLC6A3: multidisease risks. Mol Psychiatry 2022; 27:1031-1046. [PMID: 34650206 PMCID: PMC9008071 DOI: 10.1038/s41380-021-01341-5] [Citation(s) in RCA: 25] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Revised: 09/28/2021] [Accepted: 10/01/2021] [Indexed: 02/02/2023]
Abstract
The human dopamine transporter gene SLC6A3 has been consistently implicated in several neuropsychiatric diseases but the disease mechanism remains elusive. In this risk synthesis, we have concluded that SLC6A3 represents an increasingly recognized risk with a growing number of familial mutants associated with neuropsychiatric and neurological disorders. At least five loci were related to common and severe diseases including alcohol use disorder (high activity variant), attention-deficit/hyperactivity disorder (low activity variant), autism (familial proteins with mutated networking) and movement disorders (both regulatory variants and familial mutations). Association signals depended on genetic markers used as well as ethnicity examined. Strong haplotype selection and gene-wide epistases support multimarker assessment of functional variations and phenotype associations. Inclusion of its promoter region's functional markers such as DNPi (rs67175440) and 5'VNTR (rs70957367) may help delineate condensate-based risk action, testing a locus-pathway-phenotype hypothesis for one gene-multidisease etiology.
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Affiliation(s)
- Maarten E A Reith
- Department of Psychiatry, New York University School of Medicine, New York City, NY, 10016, USA
| | - Sandhya Kortagere
- Department of Microbiology and Immunology, Drexel University College of Medicine, Philadelphia, PA, 19129, USA
| | - Corinde E Wiers
- Laboratory of Neuroimaging, National Institute on Alcohol Abuse and Alcoholism, Bethesda, MD, 20817, USA
- Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Hui Sun
- Laboratory of Neuroimaging, National Institute on Alcohol Abuse and Alcoholism, Bethesda, MD, 20817, USA
| | - Manju A Kurian
- Molecular Neurosciences, Developmental Neurosciences, Zayed Centre for Research into Rare Diseases in Children, UCL Great Ormond Street Institute of Child Health, and Department of Neurology, Great Ormond Street Hospital, London, WC1N 1EH, UK
| | - Aurelio Galli
- Department of Surgery, University of Alabama at Birmingham, Birmingham, AL, 35294, USA
| | - Nora D Volkow
- Laboratory of Neuroimaging, National Institute on Alcohol Abuse and Alcoholism, Bethesda, MD, 20817, USA
- National Institute on Drug Abuse, Bethesda, MD, 20817, USA
| | - Zhicheng Lin
- Laboratory of Psychiatric Neurogenomics, McLean Hospital, and Department of Psychiatry, Harvard Medical School, Belmont, MA, 02478, USA.
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12
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Fagan RR, Kearney PJ, Luethi D, Bolden NC, Sitte HH, Emery P, Melikian HE. Dopaminergic Ric GTPase activity impacts amphetamine sensitivity and sleep quality in a dopamine transporter-dependent manner in Drosophila melanogaster. Mol Psychiatry 2021; 26:7793-7802. [PMID: 34471250 PMCID: PMC8881384 DOI: 10.1038/s41380-021-01275-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Revised: 07/28/2021] [Accepted: 08/20/2021] [Indexed: 02/07/2023]
Abstract
Dopamine (DA) is required for movement, sleep, and reward, and DA signaling is tightly controlled by the presynaptic DA transporter (DAT). Therapeutic and addictive psychostimulants, including methylphenidate (Ritalin; MPH), cocaine, and amphetamine (AMPH), markedly elevate extracellular DA via their actions as competitive DAT inhibitors (MPH, cocaine) and substrates (AMPH). DAT silencing in mice and invertebrates results in hyperactivity, reduced sleep, and blunted psychostimulant responses, highlighting DAT's essential role in DA-dependent behaviors. DAT surface expression is not static; rather it is dynamically regulated by endocytic trafficking. PKC-stimulated DAT endocytosis requires the neuronal GTPase, Rit2, and Rit2 silencing in mouse DA neurons impacts psychostimulant sensitivity. However, it is unknown whether or not Rit2-mediated changes in psychostimulant sensitivity are DAT-dependent. Here, we leveraged Drosophila melanogaster to test whether the Drosophila Rit2 ortholog, Ric, impacts dDAT function, trafficking, and DA-dependent behaviors. Orthologous to hDAT and Rit2, dDAT and Ric directly interact, and the constitutively active Ric mutant Q117L increased dDAT surface levels and function in cell lines and ex vivo Drosophila brains. Moreover, DAergic RicQ117L expression caused sleep fragmentation in a DAT-dependent manner but had no effect on total sleep and daily locomotor activity. Importantly, we found that Rit2 is required for AMPH-stimulated DAT internalization in mouse striatum, and that DAergic RicQ117L expression significantly increased Drosophila AMPH sensitivity in a DAT-dependent manner, suggesting a conserved impact of Ric-dependent DAT trafficking on AMPH sensitivity. These studies support that the DAT/Rit2 interaction impacts both baseline behaviors and AMPH sensitivity, potentially by regulating DAT trafficking.
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Affiliation(s)
- Rita R. Fagan
- Brudnick Neuropsychiatric Research Institute, Department of Neurobiology, UMASS Medical School, Worcester, MA
| | - Patrick J. Kearney
- Brudnick Neuropsychiatric Research Institute, Department of Neurobiology, UMASS Medical School, Worcester, MA
| | - Dino Luethi
- Medical University Vienna, Center for Physiology and Pharmacology, Institute of Pharmacology, Vienna, Austria, A-1090
| | - Nicholas C. Bolden
- Brudnick Neuropsychiatric Research Institute, Department of Neurobiology, UMASS Medical School, Worcester, MA
| | - Harald H. Sitte
- Medical University Vienna, Center for Physiology and Pharmacology, Institute of Pharmacology, Vienna, Austria, A-1090
| | - Patrick Emery
- Department of Neurobiology, UMASS Medical School, Worcester, MA
| | - Haley E. Melikian
- Brudnick Neuropsychiatric Research Institute, Department of Neurobiology, UMASS Medical School, Worcester, MA,Address correspondence to: Haley Melikian, Ph.D., Department of Neurobiology, UMASS Medical School, LRB 726, 364 Plantation St., Worcester, MA 01605, 774-455-4308 (phone), 508-856-6266 (fax),
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13
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Román V, Kedves R, Kelemen K, Némethy Z, Sperlágh B, Lendvai B, Vizi ES. Contribution of analog signaling to neurotransmitter interactions and behavior: Role of transporter-mediated nonquantal dopamine release. Physiol Rep 2021; 9:e15088. [PMID: 34762352 PMCID: PMC8582292 DOI: 10.14814/phy2.15088] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 09/28/2021] [Accepted: 10/08/2021] [Indexed: 11/28/2022] Open
Abstract
Neuronal networks cause changes in behaviorally important information processing through the vesicular release of neurotransmitters governed by the rate and timing of action potentials (APs). Herein, we provide evidence that dopamine (DA), nonquantally released from the cytoplasm, may exert similar effects in vivo. In mouse slice preparations, (+/-)-3,4-methylenedioxy-methamphetamine (MDMA, or ecstasy) and β-phenylethylamine (β-PEA)-induced DA release in the striatum and nucleus accumbens (NAc), two regions of the brain involved in reward-driven and social behavior and inhibited the axonal stimulation-induced release of tritiated acetylcholine ([3 H]ACh) in the striatum. The DA transporter (DAT) inhibitor (GBR-12909) prevented MDMA and β-PEA from causing DA release. GBR-12909 could also restore some of the stimulated acetylcholine release reduced by MDMA or β-PEA in the striatum confirming the fundamental role of DAT. In addition, hypothermia could prevent the β-PEA-induced release in the striatum and in the NAc. Sulpiride, a D2 receptor antagonist, also prevented the inhibitory effects of MDMA or β-PEA on stimulated ACh release, suggesting they act indirectly via binding of DA. Reflecting the neurochemical interactions in brain slices at higher system level, MDMA altered the social behavior of rats by preferentially enhancing passive social behavior. Similar to the in vitro effects, GBR-12909 treatment reversed specific elements of the MDMA-induced changes in behavior, such as passive social behavior, while left others including social play unchanged. The changes in behavior by the high level of extracellular DA-- a significant amount originating from cytoplasmic release--suggest that in addition to digital computation through synapses, the brain also uses analog communication, such as DA signaling, to mediate some elements of complex behaviors, but in a much longer time scale.
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Affiliation(s)
- Viktor Román
- Pharmacology and Drug Safety ResearchGedeon Richter Plc.BudapestHungary
| | - Rita Kedves
- Pharmacology and Drug Safety ResearchGedeon Richter Plc.BudapestHungary
| | - Kristóf Kelemen
- Pharmacology and Drug Safety ResearchGedeon Richter Plc.BudapestHungary
| | - Zsolt Némethy
- Pharmacology and Drug Safety ResearchGedeon Richter Plc.BudapestHungary
| | | | - Balázs Lendvai
- Pharmacology and Drug Safety ResearchGedeon Richter Plc.BudapestHungary
| | - E. Sylvester Vizi
- Institute of Experimental MedicineBudapestHungary
- Department of Pharmacology and PharmacotherapySemmelweis UniversityBudapestHungary
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14
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Fernández G, Krapacher F, Ferreras S, Quassollo G, Mari MM, Pisano MV, Montemerlo A, Rubianes MD, Bregonzio C, Arias C, Paglini MG. Lack of Cdk5 activity is involved on Dopamine Transporter expression and function: Evidences from an animal model of Attention-Deficit Hyperactivity Disorder. Exp Neurol 2021; 346:113866. [PMID: 34537209 DOI: 10.1016/j.expneurol.2021.113866] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2021] [Revised: 09/08/2021] [Accepted: 09/14/2021] [Indexed: 11/29/2022]
Abstract
Attention deficit/Hyperactivity disorder (ADHD) is one of the most diagnosed psychiatric disorders nowadays. The core symptoms of the condition include hyperactivity, impulsiveness and inattention. The main pharmacological treatment consists of psychostimulant drugs affecting Dopamine Transporter (DAT) function. We have previously shown that genetically modified mice lacking p35 protein (p35KO), which have reduced Cdk5 activity, present key hallmarks resembling those described in animal models useful for studying ADHD. The p35KO mouse displays spontaneous hyperactivity and shows a calming effect of methylphenidate or amphetamine treatment. Interestingly, dopaminergic neurotransmission is altered in these mice as they have an increased Dopamine (DA) content together with a low DA turnover. This led us to hypothesize that the lack of Cdk5 activity affects DAT expression and/or function in this animal model. In this study, we performed biochemical assays, cell-based approaches, quantitative fluorescence analysis and functional studies that allowed us to demonstrate that p35KO mice exhibit decreased DA uptake and reduced cell surface DAT expression levels in the striatum (STR). These findings are supported by in vitro observations in which the inhibition of Cdk5 activity in N2a cells induced a significant increase in constitutive DAT endocytosis with a concomitant increase in DAT localization to recycling endosomes. Taken together, these data provide evidences regarding the role of Cdk5/p35 in DAT expression and function, thus contributing to the knowledge of DA neurotransmission physiology and also providing therapeutic options for the treatment of DA pathologies such as ADHD.
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Affiliation(s)
- Guillermo Fernández
- Laboratory of Neurophysiology, Instituto de Investigación Médica Mercedes y Martín Ferreyra, INIMEC-CONICET, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Favio Krapacher
- Laboratory of Neurophysiology, Instituto de Investigación Médica Mercedes y Martín Ferreyra, INIMEC-CONICET, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Soledad Ferreras
- Laboratory of Neurophysiology, Instituto de Investigación Médica Mercedes y Martín Ferreyra, INIMEC-CONICET, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Gonzalo Quassollo
- Laboratory of Neurophysiology, Instituto de Investigación Médica Mercedes y Martín Ferreyra, INIMEC-CONICET, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Macarena Mariel Mari
- Laboratory of Neurophysiology, Instituto de Investigación Médica Mercedes y Martín Ferreyra, INIMEC-CONICET, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - María Victoria Pisano
- Laboratory of Neurophysiology, Instituto de Investigación Médica Mercedes y Martín Ferreyra, INIMEC-CONICET, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Antonella Montemerlo
- Instituto de Investigaciones en Fisicoquímica de Córdoba, INFIQC-CONICET, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - María Dolores Rubianes
- Instituto de Investigaciones en Fisicoquímica de Córdoba, INFIQC-CONICET, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Claudia Bregonzio
- Instituto de Farmacología Experimental Córdoba, IFEC-CONICET, Departamento de Farmacología, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Carlos Arias
- Laboratory of Neurophysiology, Instituto de Investigación Médica Mercedes y Martín Ferreyra, INIMEC-CONICET, Universidad Nacional de Córdoba, Córdoba, Argentina; Instituto de Investigaciones Psicológicas, IIPSI-CONICET, Facultad de Psicología, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - María Gabriela Paglini
- Laboratory of Neurophysiology, Instituto de Investigación Médica Mercedes y Martín Ferreyra, INIMEC-CONICET, Universidad Nacional de Córdoba, Córdoba, Argentina; Instituto de Virología "Dr. J. M. Vanella", Facultad de Ciencias Médicas, Universidad Nacional de Córdoba, Córdoba, Argentina.
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15
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Jhang CL, Lee HY, Chen JC, Liao W. Dopaminergic loss of cyclin-dependent kinase-like 5 recapitulates methylphenidate-remediable hyperlocomotion in mouse model of CDKL5 deficiency disorder. Hum Mol Genet 2021; 29:2408-2419. [PMID: 32588892 DOI: 10.1093/hmg/ddaa122] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2020] [Revised: 05/24/2020] [Accepted: 06/11/2020] [Indexed: 12/20/2022] Open
Abstract
Cyclin-dependent kinase-like 5 (CDKL5), a serine-threonine kinase encoded by an X-linked gene, is highly expressed in the mammalian forebrain. Mutations in this gene cause CDKL5 deficiency disorder, a neurodevelopmental encephalopathy characterized by early-onset seizures, motor dysfunction, and intellectual disability. We previously found that mice lacking CDKL5 exhibit hyperlocomotion and increased impulsivity, resembling the core symptoms in attention-deficit hyperactivity disorder (ADHD). Here, we report the potential neural mechanisms and treatment for hyperlocomotion induced by CDKL5 deficiency. Our results showed that loss of CDKL5 decreases the proportion of phosphorylated dopamine transporter (DAT) in the rostral striatum, leading to increased levels of extracellular dopamine and hyperlocomotion. Administration of methylphenidate (MPH), a DAT inhibitor clinically effective to improve symptoms in ADHD, significantly alleviated the hyperlocomotion phenotype in Cdkl5 null mice. In addition, the improved behavioral effects of MPH were accompanied by a region-specific restoration of phosphorylated dopamine- and cAMP-regulated phosphoprotein Mr 32 kDa, a key signaling protein for striatal motor output. Finally, mice carrying a Cdkl5 deletion selectively in DAT-expressing dopaminergic neurons, but not dopamine receptive neurons, recapitulated the hyperlocomotion phenotype found in Cdkl5 null mice. Our findings suggest that CDKL5 is essential to control locomotor behavior by regulating region-specific dopamine content and phosphorylation of dopamine signaling proteins in the striatum. The direct, as well as indirect, target proteins regulated by CDKL5 may play a key role in movement control and the therapeutic development for hyperactivity disorders.
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Affiliation(s)
- Cian-Ling Jhang
- Institute of Neuroscience, National Cheng-Chi University, Taipei 116, Taiwan
| | - Hom-Yi Lee
- Department of Psychology, Chung Shan Medical University, Taichung 402, Taiwan.,Department of Speech Language Pathology and Audiology, Chung Shan Medical University, Taichung 402, Taiwan
| | - Jin-Chung Chen
- Graduate Institute of Biomedical Sciences, Chang Gung University, Taoyuan 333, Taiwan
| | - Wenlin Liao
- Institute of Neuroscience, National Cheng-Chi University, Taipei 116, Taiwan.,Research Center for Mind, Brain and Learning, National Cheng-Chi University, Taipei 116, Taiwan
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16
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Herborg F, Jensen KL, Tolstoy S, Arends NV, Posselt LP, Shekar A, Aguilar JI, Lund VK, Erreger K, Rickhag M, Lycas MD, Lonsdale MN, Rahbek-Clemmensen T, Sørensen AT, Newman AH, Løkkegaard A, Kjaerulff O, Werge T, Møller LB, Matthies HJ, Galli A, Hjermind LE, Gether U. Dominant-negative actions of a dopamine transporter variant identified in patients with parkinsonism and neuropsychiatric disease. JCI Insight 2021; 6:e151496. [PMID: 34375312 PMCID: PMC8492322 DOI: 10.1172/jci.insight.151496] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Accepted: 07/28/2021] [Indexed: 11/17/2022] Open
Abstract
Dysfunctional dopaminergic neurotransmission is central to movement disorders and mental diseases. The dopamine transporter (DAT) regulates extracellular dopamine levels, but the genetic and mechanistic link between DAT function and dopamine-related pathologies is not clear. Particularly, the pathophysiological significance of monoallelic missense mutations in DAT is unknown. Here, we use clinical information, neuroimaging, and large-scale exome-sequencing data to uncover the occurrence and phenotypic spectrum of a DAT coding variant, DAT-K619N, which localizes to the critical C-terminal PSD-95/Discs-large/ZO-1 homology–binding motif of human DAT (hDAT). We identified the rare but recurrent hDAT-K619N variant in exome-sequenced samples of patients with neuropsychiatric diseases and a patient with early-onset neurodegenerative parkinsonism and comorbid neuropsychiatric disease. In cell cultures, hDAT-K619N displayed reduced uptake capacity, decreased surface expression, and accelerated turnover. Unilateral expression in mouse nigrostriatal neurons revealed differential effects of hDAT-K619N and hDAT-WT on dopamine-directed behaviors, and hDAT-K619N expression in Drosophila led to impairments in dopamine transmission with accompanying hyperlocomotion and age-dependent disturbances of the negative geotactic response. Moreover, cellular studies and viral expression of hDAT-K619N in mice demonstrated a dominant-negative effect of the hDAT-K619N mutant. Summarized, our results suggest that hDAT-K619N can effectuate dopamine dysfunction of pathological relevance in a dominant-negative manner.
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Affiliation(s)
- Freja Herborg
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Kathrine L Jensen
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Sasha Tolstoy
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Natascha V Arends
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Leonie P Posselt
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Aparna Shekar
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, United States of America
| | - Jenny I Aguilar
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, United States of America
| | - Viktor K Lund
- Departmetn of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Kevin Erreger
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, United States of America
| | - Mattias Rickhag
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Matthew D Lycas
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Markus N Lonsdale
- Department of Clinical Physiology and Nuclear Medicine, Bispebjerg Hospital, Copenhagen, Denmark
| | - Troels Rahbek-Clemmensen
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Andreas T Sørensen
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Amy H Newman
- National Institute on Drug Abuse-Intramural Research Program, National Institutes of Health, Baltimore, United States of America
| | | | - Ole Kjaerulff
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Thomas Werge
- Department of Clinical Medicine, University of Copenhagen, Copenhagen, Denmark
| | - Lisbeth B Møller
- Center for Applied Human Genetics, Kennedy Center, Glostrup, Denmark
| | - Heinrich Jg Matthies
- Department of Surgery, University of Alabama at Birmingham, Birmingham, United States of America
| | - Aurelio Galli
- Department of Surgery, University of Alabama at Birmingham, Birmingham, United States of America
| | - Lena E Hjermind
- Department of Neurology, Copenhagen University Hospital, Copenhagen, Denmark
| | - Ulrik Gether
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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17
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Ryan RM, Ingram SL, Scimemi A. Regulation of Glutamate, GABA and Dopamine Transporter Uptake, Surface Mobility and Expression. Front Cell Neurosci 2021; 15:670346. [PMID: 33927596 PMCID: PMC8076567 DOI: 10.3389/fncel.2021.670346] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2021] [Accepted: 03/15/2021] [Indexed: 01/31/2023] Open
Abstract
Neurotransmitter transporters limit spillover between synapses and maintain the extracellular neurotransmitter concentration at low yet physiologically meaningful levels. They also exert a key role in providing precursors for neurotransmitter biosynthesis. In many cases, neurons and astrocytes contain a large intracellular pool of transporters that can be redistributed and stabilized in the plasma membrane following activation of different signaling pathways. This means that the uptake capacity of the brain neuropil for different neurotransmitters can be dynamically regulated over the course of minutes, as an indirect consequence of changes in neuronal activity, blood flow, cell-to-cell interactions, etc. Here we discuss recent advances in the mechanisms that control the cell membrane trafficking and biophysical properties of transporters for the excitatory, inhibitory and modulatory neurotransmitters glutamate, GABA, and dopamine.
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Affiliation(s)
- Renae M. Ryan
- School of Medical Sciences, Faculty of Medicine and Health, University of Sydney, Sydney, NSW, Australia
| | - Susan L. Ingram
- Department of Neurological Surgery, Oregon Health & Science University, Portland, OR, United States
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18
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Alonso IP, Pino JA, Kortagere S, Torres GE, España RA. Dopamine transporter function fluctuates across sleep/wake state: potential impact for addiction. Neuropsychopharmacology 2021; 46:699-708. [PMID: 33032296 PMCID: PMC8026992 DOI: 10.1038/s41386-020-00879-2] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/26/2020] [Revised: 09/13/2020] [Accepted: 09/15/2020] [Indexed: 12/20/2022]
Abstract
The dopamine transporter (DAT) has been implicated in a variety of arousal-related processes including the regulation of motor activity, learning, motivated behavior, psychostimulant abuse, and, more recently, sleep/wake state. We previously demonstrated that DAT uptake regulates fluctuations in extracellular dopamine (DA) in the striatum across the light/dark cycle with DA levels at their highest during the dark phase and lowest during the light phase. Despite this evidence, whether fluctuations in DA uptake across the light/dark cycle are associated with changes in sleep/wake has not been tested. To address this, we employed a combination of sleep/wake recordings, fast scan cyclic voltammetry, and western blotting to examine whether sleep/wake state and/or light/dark phase impact DA terminal neurotransmission in male rats. Further, we assessed whether variations in plasma membrane DAT levels and/or phosphorylation of the threonine 53 site on the DAT accounts for fluctuations in DA neurotransmission. Given the extensive evidence indicating that psychostimulants increase DA through interactions with the DAT, we also examined to what degree the effects of cocaine at inhibiting the DAT vary across sleep/wake state. Results demonstrated a significant association between individual sleep/wake states and DA terminal neurotransmission, with higher DA uptake rate, increased phosphorylation of the DAT, and enhanced cocaine potency observed after periods of sleep. These findings suggest that sleep/wake state influences DA neurotransmission in a manner that is likely to impact a host of DA-dependent processes including a variety of neuropsychiatric disorders.
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Affiliation(s)
- I. P. Alonso
- grid.166341.70000 0001 2181 3113Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA 19129 USA
| | - J. A. Pino
- grid.440631.40000 0001 2228 7602Departamento de Medicina, Facultad de Medicina, Universidad de Atacama, 1532502 Copiapó, Chile
| | - S. Kortagere
- grid.166341.70000 0001 2181 3113Department of Microbiology and Immunology, Drexel University College of Medicine, Philadelphia, PA 19129 USA
| | - G. E. Torres
- grid.254250.40000 0001 2264 7145Department of Molecular, Cellular & Biomedical Sciences, CUNY School of Medicine at the City College of New York, New York, NY 10031 USA
| | - R. A. España
- grid.166341.70000 0001 2181 3113Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA 19129 USA
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19
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Identification by proximity labeling of novel lipidic and proteinaceous potential partners of the dopamine transporter. Cell Mol Life Sci 2021; 78:7733-7756. [PMID: 34709416 PMCID: PMC8629785 DOI: 10.1007/s00018-021-03998-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Revised: 10/07/2021] [Accepted: 10/17/2021] [Indexed: 12/05/2022]
Abstract
Dopamine (DA) transporters (DATs) are regulated by trafficking and modulatory processes that probably rely on stable and transient interactions with neighboring proteins and lipids. Using proximity-dependent biotin identification (BioID), we found novel potential partners for DAT, including several membrane proteins, such as the transmembrane chaperone 4F2hc, the proteolipid M6a and a potential membrane receptor for progesterone (PGRMC2). We also detected two cytoplasmic proteins: a component of the Cullin1-dependent ubiquitination machinery termed F-box/LRR-repeat protein 2 (FBXL2), and the enzyme inositol 5-phosphatase 2 (SHIP2). Immunoprecipitation (IP) and immunofluorescence studies confirmed either a physical association or a close spatial proximity between these proteins and DAT. M6a, SHIP2 and the Cullin1 system were shown to increase DAT activity in coexpression experiments, suggesting a functional role for their association. Deeper analysis revealed that M6a, which is enriched in neuronal protrusions (filopodia or dendritic spines), colocalized with DAT in these structures. In addition, the product of SHIP2 enzymatic activity (phosphatidylinositol 3,4-bisphosphate [PI(3,4)P2]) was tightly associated with DAT, as shown by co-IP and by colocalization of mCherry-DAT with a specific biosensor for this phospholipid. PI(3,4)P2 strongly stimulated transport activity in electrophysiological recordings, and conversely, inhibition of SHIP2 reduced DA uptake in several experimental systems including striatal synaptosomes and the dopaminergic cell line SH-SY5Y. In summary, here we report several potential new partners for DAT and a novel regulatory lipid, which may represent new pharmacological targets for DAT, a pivotal protein in dopaminergic function of the brain.
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20
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Bhat S, El-Kasaby A, Freissmuth M, Sucic S. Functional and Biochemical Consequences of Disease Variants in Neurotransmitter Transporters: A Special Emphasis on Folding and Trafficking Deficits. Pharmacol Ther 2020; 222:107785. [PMID: 33310157 PMCID: PMC7612411 DOI: 10.1016/j.pharmthera.2020.107785] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Accepted: 12/02/2020] [Indexed: 01/30/2023]
Abstract
Neurotransmitters, such as γ-aminobutyric acid, glutamate, acetyl choline, glycine and the monoamines, facilitate the crosstalk within the central nervous system. The designated neurotransmitter transporters (NTTs) both release and take up neurotransmitters to and from the synaptic cleft. NTT dysfunction can lead to severe pathophysiological consequences, e.g. epilepsy, intellectual disability, or Parkinson’s disease. Genetic point mutations in NTTs have recently been associated with the onset of various neurological disorders. Some of these mutations trigger folding defects in the NTT proteins. Correct folding is a prerequisite for the export of NTTs from the endoplasmic reticulum (ER) and the subsequent trafficking to their pertinent site of action, typically at the plasma membrane. Recent studies have uncovered some of the key features in the molecular machinery responsible for transporter protein folding, e.g., the role of heat shock proteins in fine-tuning the ER quality control mechanisms in cells. The therapeutic significance of understanding these events is apparent from the rising number of reports, which directly link different pathological conditions to NTT misfolding. For instance, folding-deficient variants of the human transporters for dopamine or GABA lead to infantile parkinsonism/dystonia and epilepsy, respectively. From a therapeutic point of view, some folding-deficient NTTs are amenable to functional rescue by small molecules, known as chemical and pharmacological chaperones.
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Affiliation(s)
- Shreyas Bhat
- Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug Development, Center of Physiology and Pharmacology, Medical University of Vienna, A-1090 Vienna, Austria
| | - Ali El-Kasaby
- Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug Development, Center of Physiology and Pharmacology, Medical University of Vienna, A-1090 Vienna, Austria
| | - Michael Freissmuth
- Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug Development, Center of Physiology and Pharmacology, Medical University of Vienna, A-1090 Vienna, Austria
| | - Sonja Sucic
- Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug Development, Center of Physiology and Pharmacology, Medical University of Vienna, A-1090 Vienna, Austria.
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21
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Kuge H, Miyamoto I, Yagyu KI, Honke K. PLRP2 selectively localizes synaptic membrane proteins via acyl-chain remodeling of phospholipids. J Lipid Res 2020; 61:1747-1763. [PMID: 32963038 PMCID: PMC7707162 DOI: 10.1194/jlr.ra120001087] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The plasma membrane of neurons consists of distinct domains, each of which carries specialized functions and a characteristic set of membrane proteins. While this compartmentalized membrane organization is essential for neuronal functions, it remains controversial how neurons establish these domains on the laterally fluid membrane. Here, using immunostaining, lipid-MS analysis and gene ablation with the CRISPR/Cas9 system, we report that the pancreatic lipase-related protein 2 (PLRP2), a phospholipase A1 (PLA1), is a key organizer of membrane protein localization at the neurite tips of PC12 cells. PLRP2 produced local distribution of 1-oleoyl-2-palmitoyl-PC at these sites through acyl-chain remodeling of membrane phospholipids. The resulting lipid domain assembled the syntaxin 4 (Stx4) protein within itself by selectively interacting with the transmembrane domain of Stx4. The localized Stx4, in turn, facilitated the fusion of transport vesicles that contained the dopamine transporter with the domain of the plasma membrane, which led to the localized distribution of the transporter to that domain. These results revealed the pivotal roles of PLA1, specifically PLRP2, in the formation of functional domains in the plasma membrane of neurons. In addition, our results suggest a mode of membrane organization in which the local acyl-chain remodeling of membrane phospholipids controls the selective localization of membrane proteins by regulating both lipid-protein interactions and the fusion of transport vesicles to the lipid domain.
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Affiliation(s)
- Hideaki Kuge
- Department of Biochemistry, Kochi University Medical School, Nankoku, Kochi, Japan.
| | - Izumi Miyamoto
- Department of Biochemistry, Kochi University Medical School, Nankoku, Kochi, Japan
| | - Ken-Ichi Yagyu
- Science Research Center, Kochi University Medical School, Nankoku, Kochi, Japan
| | - Koichi Honke
- Department of Biochemistry, Kochi University Medical School, Nankoku, Kochi, Japan.
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22
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Areal LB, Blakely RD. Neurobehavioral changes arising from early life dopamine signaling perturbations. Neurochem Int 2020; 137:104747. [PMID: 32325191 PMCID: PMC7261509 DOI: 10.1016/j.neuint.2020.104747] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Revised: 04/11/2020] [Accepted: 04/14/2020] [Indexed: 12/11/2022]
Abstract
Dopamine (DA) signaling is critical to the modulation of multiple brain functions including locomotion, reinforcement, attention and cognition. The literature provides strong evidence that altered DA availability and actions can impact normal neurodevelopment, with both early and enduring consequences on anatomy, physiology and behavior. An appreciation for the developmental contributions of DA signaling to brain development is needed to guide efforts to preclude and remedy neurobehavioral disorders, such as attention-deficit/hyperactivity disorder, addiction, bipolar disorder, schizophrenia and autism spectrum disorder, each of which exhibits links to DA via genetic, cellular and/or pharmacological findings. In this review, we highlight research pursued in preclinical models that use genetic and pharmacological approaches to manipulate DA signaling at sensitive developmental stages, leading to changes at molecular, circuit and/or behavioral levels. We discuss how these alterations can be aligned with traits displayed by neuropsychiatric diseases. Lastly, we review human studies that evaluate contributions of developmental perturbations of DA systems to increased risk for neuropsychiatric disorders.
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Affiliation(s)
- Lorena B Areal
- Department of Biomedical Science, Florida Atlantic University, Jupiter, FL, 33458, USA
| | - Randy D Blakely
- Department of Biomedical Science, Florida Atlantic University, Jupiter, FL, 33458, USA; Brain Institute, Florida Atlantic University, Jupiter, FL, 33458, USA.
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23
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Quinlan MA, Robson MJ, Ye R, Rose KL, Schey KL, Blakely RD. Ex vivo Quantitative Proteomic Analysis of Serotonin Transporter Interactome: Network Impact of the SERT Ala56 Coding Variant. Front Mol Neurosci 2020; 13:89. [PMID: 32581705 PMCID: PMC7295033 DOI: 10.3389/fnmol.2020.00089] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Accepted: 04/28/2020] [Indexed: 12/15/2022] Open
Abstract
Altered serotonin (5-HT) signaling is associated with multiple brain disorders, including major depressive disorder (MDD), obsessive-compulsive disorder (OCD), and autism spectrum disorder (ASD). The presynaptic, high-affinity 5-HT transporter (SERT) tightly regulates 5-HT clearance after release from serotonergic neurons in the brain and enteric nervous systems, among other sites. Accumulating evidence suggests that SERT is dynamically regulated in distinct activity states as a result of environmental and intracellular stimuli, with regulation perturbed by disease-associated coding variants. Our lab identified a rare, hypermorphic SERT coding substitution, Gly56Ala, in subjects with ASD, finding that the Ala56 variant stabilizes a high-affinity outward-facing conformation (SERT∗) that leads to elevated 5-HT uptake in vitro and in vivo. Hyperactive SERT Ala56 appears to preclude further activity enhancements by p38α mitogen-activated protein kinase (MAPK) and can be normalized by pharmacological p38α MAPK inhibition, consistent with SERT Ala56 mimicking, constitutively, a high-activity conformation entered into transiently by p38α MAPK activation. We hypothesize that changes in SERT-interacting proteins (SIPs) support the shift of SERT into the SERT∗ state which may be captured by comparing the composition of SERT Ala56 protein complexes with those of wildtype (WT) SERT, defining specific interactions through comparisons of protein complexes recovered using preparations from SERT–/– (knockout; KO) mice. Using quantitative proteomic-based approaches, we identify a total of 459 SIPs, that demonstrate both SERT specificity and sensitivity to the Gly56Ala substitution, with a striking bias being a loss of SIP interactions with SERT Ala56 compared to WT SERT. Among this group are previously validated SIPs, such as flotillin-1 (FLOT1) and protein phosphatase 2A (PP2A), whose functions are believed to contribute to SERT microdomain localization and regulation. Interestingly, our studies nominate a number of novel SIPs implicated in ASD, including fragile X mental retardation 1 protein (FMR1) and SH3 and multiple ankyrin repeat domains protein 3 (SHANK3), of potential relevance to long-standing evidence of serotonergic contributions to ASD. Further investigation of these SIPs, and the broader networks they engage, may afford a greater understanding of ASD as well as other brain and peripheral disorders associated with perturbed 5-HT signaling.
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Affiliation(s)
- Meagan A Quinlan
- Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle, WA, United States.,Department of Pharmacology, Vanderbilt University, Nashville, TN, United States.,Department of Biomedical Science, Charles E. Schmidt College of Medicine, Florida Atlantic University, Jupiter, FL, United States
| | - Matthew J Robson
- Division of Pharmaceutical Sciences, James L. Winkle College of Pharmacy, University of Cincinnati, Cincinnati, OH, United States
| | - Ran Ye
- Department of Pharmacology, Vanderbilt University, Nashville, TN, United States
| | - Kristie L Rose
- Department of Biochemistry, Vanderbilt University, Nashville, TN, United States
| | - Kevin L Schey
- Department of Biochemistry, Vanderbilt University, Nashville, TN, United States
| | - Randy D Blakely
- Department of Pharmacology, Vanderbilt University, Nashville, TN, United States.,Brain Institute, Florida Atlantic University, Jupiter, FL, United States
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24
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Combined neurodevelopmental exposure to deltamethrin and corticosterone is associated with Nr3c1 hypermethylation in the midbrain of male mice. Neurotoxicol Teratol 2020; 80:106887. [PMID: 32348866 DOI: 10.1016/j.ntt.2020.106887] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Revised: 04/10/2020] [Accepted: 04/21/2020] [Indexed: 12/21/2022]
Abstract
Attention-Deficit Hyperactivity Disorder (ADHD) is one of the most common neurodevelopmental disorders and manifests inattention, hyperactivity, and impulsivity symptoms in childhood that can last throughout life. Genetic and environmental studies implicate the dopamine system in ADHD pathogenesis. Work from our group and that of others indicates that deltamethrin insecticide and stress exposure during neurodevelopment leads to alterations in dopamine function, and we hypothesized that exposure to both of these factors together would lead to synergistic effects on DNA methylation of key genes within the midbrain, a highly dopaminergic region, that could contribute to these findings. Through targeted next-generation sequencing of a panel of cortisol and dopamine pathway genes, we observed hypermethylation of the glucocorticoid receptor gene, Nr3c1, in the midbrain of C57/BL6N males in response to dual deltamethrin and corticosterone exposures during development. This is the first description of DNA methylation studies of Nr3c1 and key dopaminergic genes within the midbrain in response to a pyrethroid insecticide, corticosterone, and these two exposures together. Our results provide possible connections between environmental exposures that impact the dopamine system and the hypothalamic-pituitary-adrenal axis via changes in DNA methylation and provides new information about the presence of epigenetic effects in adulthood after exposure during neurodevelopment.
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25
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Fagan RR, Kearney PJ, Sweeney CG, Luethi D, Schoot Uiterkamp FE, Schicker K, Alejandro BS, O'Connor LC, Sitte HH, Melikian HE. Dopamine transporter trafficking and Rit2 GTPase: Mechanism of action and in vivo impact. J Biol Chem 2020; 295:5229-5244. [PMID: 32132171 PMCID: PMC7170531 DOI: 10.1074/jbc.ra120.012628] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Revised: 02/20/2020] [Indexed: 12/20/2022] Open
Abstract
Following its evoked release, dopamine (DA) signaling is rapidly terminated by presynaptic reuptake, mediated by the cocaine-sensitive DA transporter (DAT). DAT surface availability is dynamically regulated by endocytic trafficking, and direct protein kinase C (PKC) activation acutely diminishes DAT surface expression by accelerating DAT internalization. Previous cell line studies demonstrated that PKC-stimulated DAT endocytosis requires both Ack1 inactivation, which releases a DAT-specific endocytic brake, and the neuronal GTPase, Rit2, which binds DAT. However, it is unknown whether Rit2 is required for PKC-stimulated DAT endocytosis in DAergic terminals or whether there are region- and/or sex-dependent differences in PKC-stimulated DAT trafficking. Moreover, the mechanisms by which Rit2 controls PKC-stimulated DAT endocytosis are unknown. Here, we directly examined these important questions. Ex vivo studies revealed that PKC activation acutely decreased DAT surface expression selectively in ventral, but not dorsal, striatum. AAV-mediated, conditional Rit2 knockdown in DAergic neurons impacted baseline DAT surface:intracellular distribution in DAergic terminals from female ventral, but not dorsal, striatum. Further, Rit2 was required for PKC-stimulated DAT internalization in both male and female ventral striatum. FRET and surface pulldown studies in cell lines revealed that PKC activation drives DAT-Rit2 surface dissociation and that the DAT N terminus is required for both PKC-mediated DAT-Rit2 dissociation and DAT internalization. Finally, we found that Rit2 and Ack1 independently converge on DAT to facilitate PKC-stimulated DAT endocytosis. Together, our data provide greater insight into mechanisms that mediate PKC-regulated DAT internalization and reveal unexpected region-specific differences in PKC-stimulated DAT trafficking in bona fide DAergic terminals.
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Affiliation(s)
- Rita R Fagan
- Brudnick Neuropsychiatric Research Institute, Department of Neurobiology, University of Massachusetts Medical School, Worcester, Massachusetts 01605
| | - Patrick J Kearney
- Brudnick Neuropsychiatric Research Institute, Department of Neurobiology, University of Massachusetts Medical School, Worcester, Massachusetts 01605
| | - Carolyn G Sweeney
- Brudnick Neuropsychiatric Research Institute, Department of Neurobiology, University of Massachusetts Medical School, Worcester, Massachusetts 01605
| | - Dino Luethi
- Institute of Pharmacology, Center for Physiology and Pharmacology, Medical University Vienna, Vienna A-1090, Austria
| | - Florianne E Schoot Uiterkamp
- Institute of Pharmacology, Center for Physiology and Pharmacology, Medical University Vienna, Vienna A-1090, Austria
| | - Klaus Schicker
- Institute of Pharmacology, Center for Physiology and Pharmacology, Medical University Vienna, Vienna A-1090, Austria
| | - Brian S Alejandro
- Brudnick Neuropsychiatric Research Institute, Department of Neurobiology, University of Massachusetts Medical School, Worcester, Massachusetts 01605
| | - Lauren C O'Connor
- Brudnick Neuropsychiatric Research Institute, Department of Neurobiology, University of Massachusetts Medical School, Worcester, Massachusetts 01605
| | - Harald H Sitte
- Institute of Pharmacology, Center for Physiology and Pharmacology, Medical University Vienna, Vienna A-1090, Austria
| | - Haley E Melikian
- Brudnick Neuropsychiatric Research Institute, Department of Neurobiology, University of Massachusetts Medical School, Worcester, Massachusetts 01605.
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26
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Fagan RR, Kearney PJ, Melikian HE. In Situ Regulated Dopamine Transporter Trafficking: There's No Place Like Home. Neurochem Res 2020; 45:1335-1343. [PMID: 32146647 DOI: 10.1007/s11064-020-03001-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Revised: 02/24/2020] [Accepted: 02/26/2020] [Indexed: 12/13/2022]
Abstract
Dopamine (DA) is critical for motivation, reward, movement initiation, and learning. Mechanisms that control DA signaling have a profound impact on these important behaviors, and additionally play a role in DA-related neuropathologies. The presynaptic SLC6 DA transporter (DAT) limits extracellular DA levels by clearing released DA, and is potently inhibited by addictive and therapeutic psychostimulants. Decades of evidence support that the DAT is subject to acute regulation by a number of signaling pathways, and that endocytic trafficking strongly regulates DAT availability and function. DAT trafficking studies have been performed in a variety of model systems, including both in vitro and ex vivo preparations. In this review, we focus on the breadth of DAT trafficking studies, with specific attention to, and comparison of, how context may influence DAT's response to different stimuli. In particular, this overview highlights that stimulated DAT trafficking not only differs between in vitro and ex vivo environments, but also is influenced by both sex and anatomical subregions.
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Affiliation(s)
- Rita R Fagan
- Brudnick Neuropsychiatric Research Institute, Department of Neurobiology, University of Massachusetts Medical School, Worcester, MA, 01605, USA
| | - Patrick J Kearney
- Brudnick Neuropsychiatric Research Institute, Department of Neurobiology, University of Massachusetts Medical School, Worcester, MA, 01605, USA
| | - Haley E Melikian
- Brudnick Neuropsychiatric Research Institute, Department of Neurobiology, University of Massachusetts Medical School, Worcester, MA, 01605, USA.
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27
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Amphetamine Stimulates Endocytosis of the Norepinephrine and Neuronal Glutamate Transporters in Cultured Locus Coeruleus Neurons. Neurochem Res 2020; 45:1410-1419. [PMID: 31912366 PMCID: PMC7260265 DOI: 10.1007/s11064-019-02939-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Revised: 12/16/2019] [Accepted: 12/18/2019] [Indexed: 12/12/2022]
Abstract
Amphetamines and amphetamine-derivatives elevate neurotransmitter concentrations by competing with endogenous biogenic amines for reuptake. In addition, AMPHs have been shown to activate endocytosis of the dopamine transporter (DAT) which further elevates extracellular dopamine (DA). We previously found that the biochemical cascade leading to this cellular process involves entry of AMPH into the cell through the DAT, stimulation of an intracellular trace amine-associated receptor, TAAR1, and activation of the small GTPase, RhoA. We also showed that the neuronal glutamate transporter, EAAT3, undergoes endocytosis via the same cascade in DA neurons, leading to potentiation of glutamatergic inputs. Since AMPH is a transported inhibitor of both DAT and the norepinephrine transporter (NET), and EAAT3 is also expressed in norepinephrine (NE) neurons, we explored the possibility that this signaling cascade occurs in NE neurons. We found that AMPH can cause endocytosis of NET as well as EAAT3 in NE neurons. NET endocytosis is dependent on TAAR1, RhoA, intracellular calcium and CaMKII activation, similar to DAT. However, EAAT3 endocytosis is similar in all regards except its dependence upon CaMKII activation. RhoA activation is dependent on calcium, but not CaMKII, explaining a divergence in AMPH-mediated endocytosis of DAT and NET from that of EAAT3. These data indicate that AMPHs and other TAAR1 agonists can affect glutamate signaling through internalization of EAAT3 in NE as well as DA neurons.
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28
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Qi X, Wang S, Zhang L, Liu L, Wen Y, Ma M, Cheng S, Li P, Cheng B, Du Y, Liang X, Zhao Y, Ding M, Zhang F. An integrative analysis of transcriptome-wide association study and mRNA expression profile identified candidate genes for attention-deficit/hyperactivity disorder. Psychiatry Res 2019; 282:112639. [PMID: 31685286 DOI: 10.1016/j.psychres.2019.112639] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/18/2019] [Revised: 10/18/2019] [Accepted: 10/24/2019] [Indexed: 02/01/2023]
Abstract
BACKGROUND Attention-deficit/hyperactivity disorder (ADHD) is a common neurodevelopmental disorder, but the genetic mechanism of ADHD remains elusive now. METHODS Tissue specific transcriptome-wide association study (TWAS) of ADHD was performed by FUSION utilizing a genome-wide association study (GWAS) dataset of ADHD (including 20,183 ADHD cases and 35,191 healthy controls) and gene expression reference from brain and blood. Furthermore, the genes identified by TWAS were compared with the differently expressed genes detected by mRNA expression profiles of ADHD rat model and autism spectrum disorders (ASD) patients. Functional enrichment and annotation analysis of the identified genes were performed by DAVID and FUMAGWAS tool. RESULTS For brain tissue, TWAS identified 148 genes with P value < 0.05, such as TDO2 (PTWAS=4.01×10-2), CHD1L (PTWAS=9.64×10-3) and KIAA0319L (PTWAS=4.05×10-4). Further 11 common genes were examined in the mRNA expression datasets, such as ACSM5 (PTWAS=3.62×10-2, PmRNA=0.005), CCDC24 (PTWAS=1.49×10-2, PmRNA=2.35×10-3) and MVP (PTWAS=5.55×10-3, PmRNA=5.40×10-3). Pathway enrichment analysis of the genes identified by TWAS detected 3 pathways for ADHD, including Other glycan degradation (P value=0.021), Viral myocarditis (P value=0.034) and Endocytosis (P value=0.041). CONCLUSIONS Through integrating GWAS and mRNA expression data, we identified a group of ADHD-associated genes and pathways, providing novel clues for understanding the genetic mechanism of ADHD.
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Affiliation(s)
- Xin Qi
- School of Public Health, Health Science Center, Xi'an Jiaotong University, Xi'an, P. R. China
| | - Sen Wang
- School of Public Health, Health Science Center, Xi'an Jiaotong University, Xi'an, P. R. China
| | - Lu Zhang
- School of Public Health, Health Science Center, Xi'an Jiaotong University, Xi'an, P. R. China
| | - Li Liu
- School of Public Health, Health Science Center, Xi'an Jiaotong University, Xi'an, P. R. China
| | - Yan Wen
- School of Public Health, Health Science Center, Xi'an Jiaotong University, Xi'an, P. R. China
| | - Mei Ma
- School of Public Health, Health Science Center, Xi'an Jiaotong University, Xi'an, P. R. China
| | - Shiqiang Cheng
- School of Public Health, Health Science Center, Xi'an Jiaotong University, Xi'an, P. R. China
| | - Ping Li
- School of Public Health, Health Science Center, Xi'an Jiaotong University, Xi'an, P. R. China
| | - Bolun Cheng
- School of Public Health, Health Science Center, Xi'an Jiaotong University, Xi'an, P. R. China
| | - Yanan Du
- School of Public Health, Health Science Center, Xi'an Jiaotong University, Xi'an, P. R. China
| | - Xiao Liang
- School of Public Health, Health Science Center, Xi'an Jiaotong University, Xi'an, P. R. China
| | - Yan Zhao
- School of Public Health, Health Science Center, Xi'an Jiaotong University, Xi'an, P. R. China
| | - Miao Ding
- School of Public Health, Health Science Center, Xi'an Jiaotong University, Xi'an, P. R. China
| | - Feng Zhang
- School of Public Health, Health Science Center, Xi'an Jiaotong University, Xi'an, P. R. China.
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29
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Kovtun O, Tomlinson ID, Ferguson RS, Rosenthal SJ. Quantum dots reveal heterogeneous membrane diffusivity and dynamic surface density polarization of dopamine transporter. PLoS One 2019; 14:e0225339. [PMID: 31751387 PMCID: PMC6872175 DOI: 10.1371/journal.pone.0225339] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2019] [Accepted: 11/01/2019] [Indexed: 12/11/2022] Open
Abstract
The presynaptic dopamine transporter mediates rapid reuptake of synaptic dopamine. Although cell surface DAT trafficking recently emerged as an important component of DAT regulation, it has not been systematically investigated. Here, we apply our single quantum dot (Qdot) tracking approach to monitor DAT plasma membrane dynamics in several heterologous expression cell hosts with nanometer localization accuracy. We demonstrate that Qdot-tagged DAT proteins exhibited highly heterogeneous membrane diffusivity dependent on the local membrane topography. We also show that Qdot-tagged DATs were localized away from the flat membrane regions and were dynamically retained in the membrane protrusions and cell edges for the duration of imaging. Single quantum dot tracking of wildtype DAT and its conformation-defective coding variants (R60A and W63A) revealed a significantly accelerated rate of dysfunctional DAT membrane diffusion. We believe our results warrant an in-depth investigation as to whether compromised membrane dynamics is a common feature of brain disorder-derived DAT mutants.
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Affiliation(s)
- Oleg Kovtun
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee, United States of America
- Vanderbilt Institute of Nanoscale Science and Engineering, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Ian D. Tomlinson
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee, United States of America
- Vanderbilt Institute of Nanoscale Science and Engineering, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Riley S. Ferguson
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Sandra J. Rosenthal
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee, United States of America
- Vanderbilt Institute of Nanoscale Science and Engineering, Vanderbilt University, Nashville, Tennessee, United States of America
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee, United States of America
- Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, Tennessee, United States of America
- Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee, United States of America
- Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee, United States of America
- * E-mail:
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30
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Lebowitz JJ, Khoshbouei H. Heterogeneity of dopamine release sites in health and degeneration. Neurobiol Dis 2019; 134:104633. [PMID: 31698055 DOI: 10.1016/j.nbd.2019.104633] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Revised: 09/12/2019] [Accepted: 10/02/2019] [Indexed: 02/06/2023] Open
Abstract
Despite comprising only ~ 0.001% of all neurons in the human brain, ventral midbrain dopamine neurons exert a profound influence on human behavior and cognition. As a neuromodulator, dopamine selectively inhibits or enhances synaptic signaling to coordinate neural output for action, attention, and affect. Humans invariably lose brain dopamine during aging, and this can be exacerbated in disease states such as Parkinson's Disease. Further, it is well established in multiple disease states that cell loss is selective for a subset of highly sensitive neurons within the nigrostriatal dopamine tract. Regional differences in dopamine tone are regulated pre-synaptically, with subcircuits of projecting dopamine neurons exhibiting distinct molecular and physiological signatures. Specifically, proteins at dopamine release sites that synthesize and package cytosolic dopamine, modulate its release and reuptake, and alter neuronal excitability show regional differences that provide linkages to the observed sensitivity to neurodegeneration. The aim of this review is to outline the major components of dopamine homeostasis at neurotransmitter release sites and describe the regional differences most relevant to understanding why some, but not all, dopamine neurons exhibit heightened vulnerability to neurodegeneration.
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Affiliation(s)
- Joseph J Lebowitz
- Department of Neuroscience, University of Florida College of Medicine, Gainesville, FL 32610, USA
| | - Habibeh Khoshbouei
- Department of Neuroscience, University of Florida College of Medicine, Gainesville, FL 32610, USA.
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Monoamine transporters: structure, intrinsic dynamics and allosteric regulation. Nat Struct Mol Biol 2019; 26:545-556. [PMID: 31270469 DOI: 10.1038/s41594-019-0253-7] [Citation(s) in RCA: 58] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Accepted: 05/14/2019] [Indexed: 12/31/2022]
Abstract
Monoamine transporters (MATs) regulate neurotransmission via the reuptake of dopamine, serotonin and norepinephrine from extra-neuronal regions and thus maintain neurotransmitter homeostasis. As targets of a wide range of compounds, including antidepressants, substances of abuse and drugs for neuropsychiatric and neurodegenerative disorders, their mechanism of action and their modulation by small molecules have long been of broad interest. Recent advances in the structural characterization of dopamine and serotonin transporters have opened the way for structure-based modeling and simulations, which, together with experimental data, now provide mechanistic understanding of their transport function and interactions. Here we review recent progress in the elucidation of the structural dynamics of MATs and their conformational landscape and transitions, as well as allosteric regulation mechanisms.
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Vester AI, Chen M, Marsit CJ, Caudle WM. A Neurodevelopmental Model of Combined Pyrethroid and Chronic Stress Exposure. TOXICS 2019; 7:toxics7020024. [PMID: 31052489 PMCID: PMC6630986 DOI: 10.3390/toxics7020024] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Revised: 04/26/2019] [Accepted: 04/30/2019] [Indexed: 12/14/2022]
Abstract
Attention-deficit hyperactivity disorder (ADHD) is one of the most common neurodevelopmental disorders of childhood and previous studies indicate the dopamine system plays a major role in ADHD pathogenesis. Two environmental exposures independently associated with dopaminergic dysfunction and ADHD risk include exposure to deltamethrin, a pyrethroid insecticide, and chronic stress. We hypothesized that combined neurodevelopmental exposure to both deltamethrin and corticosterone (CORT), the major stress hormone in rodents, would result in additive changes within the dopamine system. To study this, we developed a novel dual exposure paradigm and exposed pregnant C57BL/6 dams to 3 mg/kg deltamethrin through gestation and weaning, and their offspring to 25 μg/mL CORT dissolved in the drinking water through adulthood. Midbrain RNA expression as well as striatal and cortical protein expression of key dopaminergic components were investigated, in addition to ADHD-like behavioral tasks and electrochemical dopamine dynamics via fast-scan cyclic voltammetry. Given the well-described sexual dimorphism of ADHD, males and females were assessed separately. Males exposed to deltamethrin had significantly decreased midbrain Pitx3 expression, decreased cortical tyrosine hydroxylase (TH) expression, increased activity in the Y maze, and increased dopamine uptake rate in the dorsal striatum. These effects did not occur in males exposed to CORT only, or in males exposed to both deltamethrin and CORT, suggesting that CORT may attenuate these effects. Additionally, deltamethrin- and CORT-exposed females did not display these dopaminergic features, which indicates these changes are sex-specific. Our results show dopaminergic changes from the RNA through the functional level. Moreover, these data illustrate the importance of testing multiple environmental exposures together to better understand how combined exposures that occur in certain vulnerable populations could affect similar neurodevelopmental systems, as well as the importance of studying sex differences of these alterations.
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Affiliation(s)
- Aimée I Vester
- Department of Environmental Health Sciences, Emory University Rollins School of Public Health, Atlanta, GA 30329, USA.
| | - Merry Chen
- Department of Environmental Health Sciences, Emory University Rollins School of Public Health, Atlanta, GA 30329, USA.
| | - Carmen J Marsit
- Department of Environmental Health Sciences, Emory University Rollins School of Public Health, Atlanta, GA 30329, USA.
| | - W Michael Caudle
- Department of Environmental Health Sciences, Emory University Rollins School of Public Health, Atlanta, GA 30329, USA.
- Center for Neurodegenerative Disease, Emory University, Atlanta, GA 30322, USA.
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Cartier E, Garcia-Olivares J, Janezic E, Viana J, Moore M, Lin ML, Caplan JL, Torres G, Kim YH. The SUMO-Conjugase Ubc9 Prevents the Degradation of the Dopamine Transporter, Enhancing Its Cell Surface Level and Dopamine Uptake. Front Cell Neurosci 2019; 13:35. [PMID: 30828290 PMCID: PMC6386010 DOI: 10.3389/fncel.2019.00035] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2018] [Accepted: 01/23/2019] [Indexed: 12/12/2022] Open
Abstract
The dopamine transporter (DAT) is a plasma membrane protein responsible for the uptake of released dopamine back to the presynaptic terminal and ending dopamine neurotransmission. The DAT is the molecular target for cocaine and amphetamine as well as a number of pathological conditions including autism spectrum disorders, attention-deficit hyperactivity disorder (ADHD), dopamine transporter deficiency syndrome (DTDS), and Parkinson’s disease. The DAT uptake capacity is dependent on its level in the plasma membrane. In vitro studies show that DAT functional expression is regulated by a balance of endocytosis, recycling, and lysosomal degradation. However, recent reports suggest that DAT regulation by endocytosis in neurons is less significant than previously reported. Therefore, additional mechanisms appear to determine DAT steady-state level and functional expression in the neuronal plasma membrane. Here, we hypothesize that the ubiquitin-like protein small ubiquitin-like modifier 1 (SUMO1) increases the DAT steady-state level in the plasma membrane. In confocal microscopy, fluorescent resonance energy transfer (FRET), and Western blot analyses, we demonstrate that DAT is associated with SUMO1 in the rat dopaminergic N27 and DAT overexpressing Human Embryonic Kidney cells (HEK)-293 cells. The overexpression of SUMO1 and the Ubc9 SUMO-conjugase induces DAT SUMOylation, reduces DAT ubiquitination and degradation, enhancing DAT steady-state level. In addition, the Ubc9 knock-down by interference RNA (RNAi) increases DAT degradation and reduces DAT steady-state level. Remarkably, the Ubc9-mediated SUMOylation increases the expression of DAT in the plasma membrane and dopamine uptake capacity. Our results strongly suggest that SUMOylation is a novel mechanism that plays a central role in regulating DAT proteostasis, dopamine uptake, and dopamine signaling in neurons. For that reason, the SUMO pathway including SUMO1, SUMO2, Ubc9, and DAT SUMOylation, can be critical therapeutic targets in regulating DAT stability and dopamine clearance in health and pathological states.
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Affiliation(s)
- Etienne Cartier
- Department of Biological Sciences, Delaware State University, Dover, DE, United States
| | | | - Eric Janezic
- Department of Biological Sciences, Delaware State University, Dover, DE, United States
| | - Juan Viana
- Department of Biological Sciences, Delaware State University, Dover, DE, United States
| | - Michael Moore
- Imaging Core, Delaware State University, Dover, DE, United States
| | - Min Landon Lin
- Department of Neuroscience and Department of Pharmacology, University of Florida, Gainesville, FL, United States
| | - Jeffrey L Caplan
- BioImaging Center, University of Delaware, Newark, DE, United States
| | - Gonzalo Torres
- Department of Neuroscience and Department of Pharmacology, University of Florida, Gainesville, FL, United States
| | - Yong-Hwan Kim
- Department of Biological Sciences, Delaware State University, Dover, DE, United States
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Kovtun O, Tomlinson ID, Bailey DM, Thal LB, Ross EJ, Harris L, Frankland MP, Ferguson RS, Glaser Z, Greer J, Rosenthal SJ. Single Quantum Dot Tracking Illuminates Neuroscience at the Nanoscale. Chem Phys Lett 2018; 706:741-752. [PMID: 30270931 PMCID: PMC6157616 DOI: 10.1016/j.cplett.2018.06.019] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The use of nanometer-sized semiconductor crystals, known as quantum dots, allows us to directly observe individual biomolecular transactions through a fluorescence microscope. Here, we review the evolution of single quantum dot tracking over the past two decades, highlight key biophysical discoveries facilitated by quantum dots, briefly discuss biochemical and optical implementation strategies for a single quantum dot tracking experiment, and report recent accomplishments of our group at the interface of molecular neuroscience and nanoscience.
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Affiliation(s)
- Oleg Kovtun
- Departments of Chemistry, Chemical Biology, Vanderbilt University
- Departments of Vanderbilt Institute of Nanoscale Science and Engineering
| | - Ian D. Tomlinson
- Departments of Chemistry, Chemical Biology, Vanderbilt University
- Departments of Vanderbilt Institute of Nanoscale Science and Engineering
| | - Danielle M. Bailey
- Departments of Chemistry, Chemical Biology, Vanderbilt University
- Departments of Pharmacology, Chemical Biology, Vanderbilt University
- Departments of Vanderbilt Institute of Nanoscale Science and Engineering
| | - Lucas B. Thal
- Departments of Chemistry, Chemical Biology, Vanderbilt University
- Departments of Vanderbilt Institute of Nanoscale Science and Engineering
- Departments of Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, TN
| | - Emily J. Ross
- Departments of Hudson Alpha Institute for Biotechnology, Huntsville, AL
| | - Lauren Harris
- Departments of Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, TN
| | | | | | - Zachary Glaser
- Departments of Chemistry, Chemical Biology, Vanderbilt University
| | - Jonathan Greer
- Departments of Chemistry, Chemical Biology, Vanderbilt University
| | - Sandra J. Rosenthal
- Departments of Chemistry, Chemical Biology, Vanderbilt University
- Departments of Pharmacology, Chemical Biology, Vanderbilt University
- Departments of Chemical and Biomolecular Engineering, Chemical Biology, Vanderbilt University
- Departments of Physics and Astronomy, Chemical Biology, Vanderbilt University
- Departments of Vanderbilt Institute of Nanoscale Science and Engineering
- Departments of Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, TN
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Refai O, Blakely RD. Blockade and reversal of swimming-induced paralysis in C. elegans by the antipsychotic and D2-type dopamine receptor antagonist azaperone. Neurochem Int 2018; 123:59-68. [PMID: 29800604 DOI: 10.1016/j.neuint.2018.05.013] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2018] [Revised: 05/21/2018] [Accepted: 05/21/2018] [Indexed: 10/16/2022]
Abstract
The catecholamine neurotransmitter dopamine (DA) exerts powerful modulatory control of physiology and behavior across phylogeny. Perturbations of DA signaling in humans are associated with multiple neurodegenerative and behavioral disorders, including Parkinson's disease, attention-deficit/hyperactivity disorder, addiction and schizophrenia. In the nematode C. elegans, DA signaling regulates mating behavior, learning, food seeking and locomotion. Previously, we demonstrated that loss of function mutations in the dat-1 gene that encodes the presynaptic DA transporter (DAT-1) results in a rapid cessation of movement when animals are placed in water, termed Swimming Induced Paralysis (Swip). Loss of function mutations in genes that support DA biosynthesis, DA vesicular packaging and DA action at the extrasynaptic D2-type DA receptor DOP-3 suppress Swip in dat-1 animals, consistent with paralysis as arising from excessive DA signaling. Although animals grown on the vesicular monoamine transporter antagonist reserpine diminish Swip, the drug must be applied chronically, can impact the signaling of multiple biogenic amines, and has been reported to have penetrant, off-target actions. Here, we demonstrate that the antipsychotic drug azaperone potently and rapidly suppresses Swip behavior in either dat-1 mutants, as well as in wildtype animals treated with the DAT-1 antagonist nisoxetine, with genetic experiments consistent with DOP-3 antagonism as the mechanism of Swip suppression. Reversal of Swip in previously paralyzed dat-1 animals by azaperone application demonstrates an otherwise functionally-intact swimming circuit in these mutants. Finally, whereas azaperone suppresses DA-dependent Swip, the drug fails to attenuate the DA-independent paralysis induced by βPEA, aldicarb or genetic disruption of γ-aminobutyric acid (GABA) signaling. We discuss our findings with respect to the use of azaperone as a potent and selective tool in the identification and analysis of presynaptic mechanisms that regulate DA signaling.
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Affiliation(s)
- Osama Refai
- Department of Biomedical Science, Charles E. Schmidt College of Medicine, Florida Atlantic University, FL, USA
| | - Randy D Blakely
- Department of Biomedical Science, Charles E. Schmidt College of Medicine, Florida Atlantic University, FL, USA; Brain Institute, Florida Atlantic University, Jupiter, FL, 33458, USA.
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Region-Specific Regulation of Presynaptic Dopamine Homeostasis by D 2 Autoreceptors Shapes the In Vivo Impact of the Neuropsychiatric Disease-Associated DAT Variant Val559. J Neurosci 2018; 38:5302-5312. [PMID: 29739866 DOI: 10.1523/jneurosci.0055-18.2018] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Revised: 03/19/2018] [Accepted: 04/14/2018] [Indexed: 12/21/2022] Open
Abstract
Disruptions of dopamine (DA) signaling contribute to a broad spectrum of neuropsychiatric disorders, including attention-deficit hyperactivity disorder (ADHD), addiction, bipolar disorder, and schizophrenia. Despite evidence that risk for these disorders derives from heritable variation in DA-linked genes, a better understanding is needed of the molecular and circuit context through which gene variation drives distinct disease traits. Previously, we identified the DA transporter (DAT) variant Val559 in subjects with ADHD and established that the mutation supports anomalous DAT-mediated DA efflux (ADE). Here, we demonstrate that region-specific contributions of D2 autoreceptors (D2AR) to presynaptic DA homeostasis dictate the consequences of Val559 expression in adolescent male mice. We show that activation of D2ARs in the WT dorsal striatum (DS), but not ventral striatum (VS), increases DAT phosphorylation and surface trafficking. In contrast, the activity of tyrosine hydroxylase (TH) is D2AR-dependent in both regions. In the DS but not VS of Val559 mice, tonic activation of D2ARs drives a positive feedback loop that promotes surface expression of efflux-prone DATs, raising extracellular DA levels and overwhelming DAT-mediated DA clearance capacity. Whereas D2ARs that regulate DAT are tonically activated in the Val559 DS, D2ARs that regulate TH become desensitized, allowing maintenance of cytosolic DA needed to sustain ADE. Together with prior findings, our results argue for distinct D2AR pools that regulate DA synthesis versus DA release and inactivation and offer a clear example of how the penetrance of gene variation can be limited to a subset of expression sites based on differences in intersecting regulatory networks.SIGNIFICANCE STATEMENT Altered dopamine (DA) signaling has been linked to multiple neuropsychiatric disorders. In an effort to understand and model disease-associated DAergic disturbances, we previously screened the DA transporter (DAT) in subjects with attention-deficit hyperactivity disorder (ADHD) and identified multiple, functionally impactful, coding variants. One of these variants, Val559, supports anomalous DA efflux (ADE) and in transgenic mice leads to changes in locomotor patterns, psychostimulant sensitivity, and impulsivity. Here, we show that the penetrance of Val559 ADE is dictated by region-specific differences in how presynaptic D2-type autoreceptors (D2ARs) constrain DA signaling, biasing phenotypic effects to dorsal striatal projections. The Val559 model illustrates how the impact of genetic variation underlying neuropsychiatric disorders can be shaped by the differential engagement of synaptic regulatory mechanisms.
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Won JH, Kim SK, Shin IC, Ha HC, Jang JM, Back MJ, Kim DK. Dopamine transporter trafficking is regulated by neutral sphingomyelinase 2/ceramide kinase. Cell Signal 2018; 44:171-187. [DOI: 10.1016/j.cellsig.2018.01.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2017] [Revised: 12/18/2017] [Accepted: 01/07/2018] [Indexed: 12/13/2022]
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Herborg F, Andreassen TF, Berlin F, Loland CJ, Gether U. Neuropsychiatric disease-associated genetic variants of the dopamine transporter display heterogeneous molecular phenotypes. J Biol Chem 2018; 293:7250-7262. [PMID: 29559554 DOI: 10.1074/jbc.ra118.001753] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2018] [Revised: 03/15/2018] [Indexed: 12/14/2022] Open
Abstract
Genetic factors are known to significantly contribute to the etiology of psychiatric diseases such as attention deficit hyperactivity disorder (ADHD) and autism spectrum and bipolar disorders, but the underlying molecular processes remain largely elusive. The dopamine transporter (DAT) has received continuous attention as a potential risk factor for psychiatric disease, as it is critical for dopamine homeostasis and serves as principal target for ADHD medications. Constrain metrics for the DAT-encoding gene, solute carrier family 6 member 3 (SLC6A3), indicate that missense mutations are under strong negative selection, pointing to pathophysiological outcomes when DAT function is compromised. Here, we systematically characterized six rare genetic variants of DAT (I312F, T356M, D421N, A559V, E602G, and R615C) identified in patients with neuropsychiatric disorders. We evaluated dopamine uptake and ligand interactions, along with ion coordination and electrophysiological properties, to elucidate functional phenotypes, and applied Zn2+ exposure and a substituted cysteine-accessibility approach to identify shared structural changes. Three variants (I312F, T356M, and D421N) exhibited impaired dopamine uptake associated with changes in ligand binding, ion coordination, and distinct conformational disturbances. Remarkably, we found that all three variants displayed gain-of-function electrophysiological phenotypes. I312F mediated an increased uncoupled anion conductance previously suggested to modulate neuronal excitability. T356M and D421N both mediated a cocaine-sensitive leakage of cations, which for T356M was potentiated by Zn2+, concurrent with partial functional rescue. Collectively, our findings support that gain of disruptive functions due to missense mutations in SLC6A3 may be key to understanding how dopaminergic dyshomeostasis arises in heterozygous carriers.
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Affiliation(s)
- Freja Herborg
- Molecular Neuropharmacology and Genetics Laboratory, Department of Neuroscience, Faculty of Health and Medical Sciences, Panum Institute-Maersk Tower 07.05, University of Copenhagen, DK-2200 Copenhagen, Denmark.
| | - Thorvald F Andreassen
- Molecular Neuropharmacology and Genetics Laboratory, Department of Neuroscience, Faculty of Health and Medical Sciences, Panum Institute-Maersk Tower 07.05, University of Copenhagen, DK-2200 Copenhagen, Denmark
| | - Frida Berlin
- Molecular Neuropharmacology and Genetics Laboratory, Department of Neuroscience, Faculty of Health and Medical Sciences, Panum Institute-Maersk Tower 07.05, University of Copenhagen, DK-2200 Copenhagen, Denmark
| | - Claus J Loland
- Molecular Neuropharmacology and Genetics Laboratory, Department of Neuroscience, Faculty of Health and Medical Sciences, Panum Institute-Maersk Tower 07.05, University of Copenhagen, DK-2200 Copenhagen, Denmark
| | - Ulrik Gether
- Molecular Neuropharmacology and Genetics Laboratory, Department of Neuroscience, Faculty of Health and Medical Sciences, Panum Institute-Maersk Tower 07.05, University of Copenhagen, DK-2200 Copenhagen, Denmark.
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Abstract
Background Much of the structure-based mechanistic understandings of the function of SLC6A neurotransmitter transporters emerged from the study of their bacterial LeuT-fold homologs. It has become evident, however, that structural differences such as the long N- and C-termini of the eukaryotic neurotransmitter transporters are involved in an expanded set of functional properties to the eukaryotic transporters. These functional properties are not shared by the bacterial homologs, which lack the structural elements that appeared later in evolution. However, mechanistic insights into some of the measured functional properties of the eukaryotic transporters that have been suggested to involve these structural elements are sparse or merely descriptive. Results To learn how the structural elements added in evolution enable mechanisms of the eukaryotic transporters in ways not shared with their bacterial LeuT-like homologs, we focused on the human dopamine transporter (hDAT) as a prototype. We present the results of a study employing large-scale molecular dynamics simulations and comparative Markov state model analysis of experimentally determined properties of the wild-type and mutant hDAT constructs. These offer a quantitative outline of mechanisms in which a rich spectrum of interactions of the hDAT N-terminus and C-terminus contribute to the regulation of transporter function (e.g., by phosphorylation) and/or to entirely new phenotypes (e.g., reverse uptake (efflux)) that were added in evolution. Conclusions The findings are consistent with the proposal that the size of eukaryotic neurotransmitter transporter termini increased during evolution to enable more functions (e.g., efflux) not shared with the bacterial homologs. The mechanistic explanations for the experimental findings about the modulation of function in DAT, the serotonin transporter, and other eukaryotic transporters reveal separate roles for the distal and proximal segments of the much larger N-terminus in eukaryotic transporters compared to the bacterial ones. The involvement of the proximal and distal segments — such as the role of the proximal segment in sustaining transport in phosphatidylinositol 4,5-bisphosphate-depleted membranes and of the distal segment in modulating efflux — may represent an evolutionary adaptation required for the function of eukaryotic transporters expressed in various cell types of the same organism that differ in the lipid composition and protein complement of their membrane environment. Electronic supplementary material The online version of this article (10.1186/s12915-018-0495-6) contains supplementary material, which is available to authorized users.
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Foster JD, Vaughan RA. Phosphorylation mechanisms in dopamine transporter regulation. J Chem Neuroanat 2017; 83-84:10-18. [PMID: 27836487 PMCID: PMC6705611 DOI: 10.1016/j.jchemneu.2016.10.004] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2016] [Revised: 10/26/2016] [Accepted: 10/29/2016] [Indexed: 12/17/2022]
Abstract
The dopamine transporter (DAT) is a plasma membrane phosphoprotein that actively translocates extracellular dopamine (DA) into presynaptic neurons. The transporter is the primary mechanism for control of DA levels and subsequent neurotransmission, and is the target for abused and therapeutic drugs that exert their effects by suppressing reuptake. The transport capacity of DAT is acutely regulated by signaling systems and drug exposure, providing neurons the ability to fine-tune DA clearance in response to specific conditions. Kinase pathways play major roles in these mechanisms, and this review summarizes the current status of DAT phosphorylation characteristics and the evidence linking transporter phosphorylation to control of reuptake and other functions. Greater understanding of these processes may aid in elucidation of their possible contributions to DA disease states and suggest specific phosphorylation sites as targets for therapeutic manipulation of reuptake.
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Affiliation(s)
- James D Foster
- Department of Biomedical Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks ND 58202 United States
| | - Roxanne A Vaughan
- Department of Biomedical Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks ND 58202 United States.
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Challasivakanaka S, Zhen J, Smith ME, Reith MEA, Foster JD, Vaughan RA. Dopamine transporter phosphorylation site threonine 53 is stimulated by amphetamines and regulates dopamine transport, efflux, and cocaine analog binding. J Biol Chem 2017; 292:19066-19075. [PMID: 28939767 DOI: 10.1074/jbc.m117.787002] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2017] [Revised: 08/29/2017] [Indexed: 11/06/2022] Open
Abstract
The dopamine transporter (DAT) controls the spatial and temporal dynamics of dopamine neurotransmission through reuptake of extracellular transmitter and is a target for addictive compounds such as cocaine, amphetamine (AMPH), and methamphetamine (METH). Reuptake is regulated by kinase pathways and drug exposure, allowing for fine-tuning of clearance in response to specific conditions, and here we examine the impact of transporter ligands on DAT residue Thr-53, a proline-directed phosphorylation site previously implicated in AMPH-stimulated efflux mechanisms. Our findings show that Thr-53 phosphorylation is stimulated in a transporter-dependent manner by AMPH and METH in model cells and rat striatal synaptosomes, and in striatum of rats given subcutaneous injection of METH. Rotating disc electrode voltammetry revealed that initial rates of uptake and AMPH-induced efflux were elevated in phosphorylation-null T53A DAT relative to WT and charge-substituted T53D DATs, consistent with functions related to charge or polarity. These effects occurred without alterations of surface transporter levels, and mutants also showed reduced cocaine analog binding affinity that was not rescued by Zn2+ Together these findings support a role for Thr-53 phosphorylation in regulation of transporter kinetic properties that could impact DAT responses to amphetamines and cocaine.
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Affiliation(s)
- Sathya Challasivakanaka
- From the Department of Biomedical Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, North Dakota 58201 and
| | | | - Margaret E Smith
- From the Department of Biomedical Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, North Dakota 58201 and
| | - Maarten E A Reith
- the Departments of Psychiatry and.,Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, New York 10016
| | - James D Foster
- From the Department of Biomedical Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, North Dakota 58201 and
| | - Roxanne A Vaughan
- From the Department of Biomedical Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, North Dakota 58201 and
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Gaskill PJ, Miller DR, Gamble-George J, Yano H, Khoshbouei H. HIV, Tat and dopamine transmission. Neurobiol Dis 2017; 105:51-73. [PMID: 28457951 PMCID: PMC5541386 DOI: 10.1016/j.nbd.2017.04.015] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2017] [Revised: 04/04/2017] [Accepted: 04/16/2017] [Indexed: 01/02/2023] Open
Abstract
Human Immunodeficiency Virus (HIV) is a progressive infection that targets the immune system, affecting more than 37 million people around the world. While combinatorial antiretroviral therapy (cART) has lowered mortality rates and improved quality of life in infected individuals, the prevalence of HIV associated neurocognitive disorders is increasing and HIV associated cognitive decline remains prevalent. Recent research has suggested that HIV accessory proteins may be involved in this decline, and several studies have indicated that the HIV protein transactivator of transcription (Tat) can disrupt normal neuronal and glial function. Specifically, data indicate that Tat may directly impact dopaminergic neurotransmission, by modulating the function of the dopamine transporter and specifically damaging dopamine-rich regions of the CNS. HIV infection of the CNS has long been associated with dopaminergic dysfunction, but the mechanisms remain undefined. The specific effect(s) of Tat on dopaminergic neurotransmission may be, at least partially, a mechanism by which HIV infection directly or indirectly induces dopaminergic dysfunction. Therefore, precisely defining the specific effects of Tat on the dopaminergic system will help to elucidate the mechanisms by which HIV infection of the CNS induces neuropsychiatric, neurocognitive and neurological disorders that involve dopaminergic neurotransmission. Further, this will provide a discussion of the experiments needed to further these investigations, and may help to identify or develop new therapeutic approaches for the prevention or treatment of these disorders in HIV-infected individuals.
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Affiliation(s)
- Peter J Gaskill
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, PA 19102, United States.
| | - Douglas R Miller
- Department of Neuroscience, University of Florida, Gainesville, FL 32611, United States
| | - Joyonna Gamble-George
- Department of Neuroscience, University of Florida, Gainesville, FL 32611, United States
| | - Hideaki Yano
- National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD 21224, United States
| | - Habibeh Khoshbouei
- Department of Neuroscience, University of Florida, Gainesville, FL 32611, United States.
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The Dopamine Transporter Recycles via a Retromer-Dependent Postendocytic Mechanism: Tracking Studies Using a Novel Fluorophore-Coupling Approach. J Neurosci 2017; 37:9438-9452. [PMID: 28847807 DOI: 10.1523/jneurosci.3885-16.2017] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Revised: 07/17/2017] [Accepted: 08/19/2017] [Indexed: 01/28/2023] Open
Abstract
Presynaptic reuptake, mediated by the dopamine (DA) transporter (DAT), terminates DAergic neurotransmission and constrains extracellular DA levels. Addictive and therapeutic psychostimulants inhibit DA reuptake and multiple DAT coding variants have been reported in patients with neuropsychiatric disorders. These findings underscore that DAT is critical for DA neurotransmission and homeostasis. DAT surface availability is regulated acutely by endocytic trafficking, and considerable effort has been directed toward understanding mechanisms that govern DAT's plasma membrane expression and postendocytic fate. Multiple studies have demonstrated DAT endocytic recycling and enhanced surface delivery in response to various stimuli. Paradoxically, imaging studies have not detected DAT targeting to classic recycling endosomes, suggesting that internalized DAT targets to either degradation or an undefined recycling compartment. Here, we leveraged PRIME (PRobe Incorporation Mediated by Enzyme) labeling to couple surface DAT directly to fluorophore, and tracked DAT's postendocytic itinerary in immortalized mesencephalic cells. Following internalization, DAT robustly targeted to retromer-positive endosomes, and DAT/retromer colocalization was observed in male mouse dopaminergic somatodendritic and terminal regions. Short hairpin RNA-mediated Vps35 knockdown revealed that DAT endocytic recycling requires intact retromer. DAT also targeted rab7-positive endosomes with slow, linear kinetics that were unaffected by either accelerating DAT internalization or binding a high-affinity cocaine analog. However, cocaine increased DAT exit from retromer-positive endosomes significantly. Finally, we found that the DAT carboxy-terminal PDZ-binding motif was required for DAT recycling and exit from retromer. These results define the DAT recycling mechanism and provide a unifying explanation for previous, seemingly disparate, DAT endocytic trafficking findings.SIGNIFICANCE STATEMENT The neuronal dopamine (DA) transporter (DAT) recaptures released DA and modulates DAergic neurotransmission, and a number of DAT coding variants have been reported in several DA-related disorders, including infantile parkinsonism, attention-deficit/hyperactivity disorder and autism spectrum disorder. DAT is also competitively inhibited by psychostimulants with high abuse potential. Therefore, mechanisms that acutely affect DAT availability will likely exert significant impact on both normal and pathological DAergic homeostasis. Here, we explore the cellular mechanisms that acutely control DAT surface expression. Our results reveal the intracellular mechanisms that mediate DAT endocytic recycling following constitutive and regulated internalization. In addition to shedding light on this critical process, these findings resolve conflict among multiple, seemingly disparate, previous reports on DAT's postendocytic fate.
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The Atypical MAP Kinase SWIP-13/ERK8 Regulates Dopamine Transporters through a Rho-Dependent Mechanism. J Neurosci 2017; 37:9288-9304. [PMID: 28842414 DOI: 10.1523/jneurosci.1582-17.2017] [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: 06/05/2017] [Revised: 07/31/2017] [Accepted: 08/12/2017] [Indexed: 12/26/2022] Open
Abstract
The neurotransmitter dopamine (DA) regulates multiple behaviors across phylogeny, with disrupted DA signaling in humans associated with addiction, attention-deficit/ hyperactivity disorder, schizophrenia, and Parkinson's disease. The DA transporter (DAT) imposes spatial and temporal limits on DA action, and provides for presynaptic DA recycling to replenish neurotransmitter pools. Molecular mechanisms that regulate DAT expression, trafficking, and function, particularly in vivo, remain poorly understood, though recent studies have implicated rho-linked pathways in psychostimulant action. To identify genes that dictate the ability of DAT to sustain normal levels of DA clearance, we pursued a forward genetic screen in Caenorhabditis elegans based on the phenotype swimming-induced paralysis (Swip), a paralytic behavior observed in hermaphrodite worms with loss-of-function dat-1 mutations. Here, we report the identity of swip-13, which encodes a highly conserved ortholog of the human atypical MAP kinase ERK8. We present evidence that SWIP-13 acts presynaptically to insure adequate levels of surface DAT expression and DA clearance. Moreover, we provide in vitro and in vivo evidence supporting a conserved pathway involving SWIP-13/ERK8 activation of Rho GTPases that dictates DAT surface expression and function.SIGNIFICANCE STATEMENT Signaling by the neurotransmitter dopamine (DA) is tightly regulated by the DA transporter (DAT), insuring efficient DA clearance after release. Molecular networks that regulate DAT are poorly understood, particularly in vivo Using a forward genetic screen in the nematode Caenorhabditis elegans, we implicate the atypical mitogen activated protein kinase, SWIP-13, in DAT regulation. Moreover, we provide in vitro and in vivo evidence that SWIP-13, as well as its human counterpart ERK8, regulate DAT surface availability via the activation of Rho proteins. Our findings implicate a novel pathway that regulates DA synaptic availability and that may contribute to risk for disorders linked to perturbed DA signaling. Targeting this pathway may be of value in the development of therapeutics in such disorders.
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Identifying novel members of the Wntless interactome through genetic and candidate gene approaches. Brain Res Bull 2017; 138:96-105. [PMID: 28734904 DOI: 10.1016/j.brainresbull.2017.07.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Revised: 06/26/2017] [Accepted: 07/06/2017] [Indexed: 02/07/2023]
Abstract
Wnt signaling is an important pathway that regulates several aspects of embryogenesis, stem cell maintenance, and neural connectivity. We have recently determined that opioids decrease Wnt secretion, presumably by inhibiting the recycling of the Wnt trafficking protein Wntless (Wls). This effect appears to be mediated by protein-protein interaction between Wls and the mu-opioid receptor (MOR), the primary cellular target of opioid drugs. The goal of this study was to identify novel protein interactors of Wls that are expressed in the brain and may also play a role in reward or addiction. Using genetic and candidate gene approaches, we show that among a variety of protein, Wls interacts with the dopamine transporter (target of cocaine), cannabinoid receptors (target of THC), Adenosine A2A receptor (target of caffeine), and SGIP1 (endocytic regulator of cannabinoid receptors). Our study shows that aside from opioid receptors, Wntless interacts with additional proteins involved in reward and/or addiction. Future studies will determine whether Wntless and WNT signaling play a more universal role in these processes.
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de la Peña JB, Dela Peña IJ, Custodio RJ, Botanas CJ, Kim HJ, Cheong JH. Exploring the Validity of Proposed Transgenic Animal Models of Attention-Deficit Hyperactivity Disorder (ADHD). Mol Neurobiol 2017; 55:3739-3754. [PMID: 28534274 DOI: 10.1007/s12035-017-0608-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2016] [Accepted: 05/09/2017] [Indexed: 12/31/2022]
Abstract
Attention-deficit/hyperactivity disorder (ADHD) is a common, behavioral, and heterogeneous neurodevelopmental condition characterized by hyperactivity, impulsivity, and inattention. Symptoms of this disorder are managed by treatment with methylphenidate, amphetamine, and/or atomoxetine. The cause of ADHD is unknown, but substantial evidence indicates that this disorder has a significant genetic component. Transgenic animals have become an essential tool in uncovering the genetic factors underlying ADHD. Although they cannot accurately reflect the human condition, they can provide insights into the disorder that cannot be obtained from human studies due to various limitations. An ideal animal model of ADHD must have face (similarity in symptoms), predictive (similarity in response to treatment or medications), and construct (similarity in etiology or underlying pathophysiological mechanism) validity. As the exact etiology of ADHD remains unclear, the construct validity of animal models of ADHD would always be limited. The proposed transgenic animal models of ADHD have substantially increased and diversified over the years. In this paper, we compiled and explored the validity of proposed transgenic animal models of ADHD. Each of the reviewed transgenic animal models has strengths and limitations. Some fulfill most of the validity criteria of an animal model of ADHD and have been extensively used, while there are others that require further validation. Nevertheless, these transgenic animal models of ADHD have provided and will continue to provide valuable insights into the genetic underpinnings of this complex disorder.
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Affiliation(s)
- June Bryan de la Peña
- Uimyung Research Institute for Neuroscience, Department of Pharmacy, Sahmyook University, 815 Hwarang-ro, Nowon-gu, Seoul, 01795, Republic of Korea
| | - Irene Joy Dela Peña
- Uimyung Research Institute for Neuroscience, Department of Pharmacy, Sahmyook University, 815 Hwarang-ro, Nowon-gu, Seoul, 01795, Republic of Korea
| | - Raly James Custodio
- Uimyung Research Institute for Neuroscience, Department of Pharmacy, Sahmyook University, 815 Hwarang-ro, Nowon-gu, Seoul, 01795, Republic of Korea
| | - Chrislean Jun Botanas
- Uimyung Research Institute for Neuroscience, Department of Pharmacy, Sahmyook University, 815 Hwarang-ro, Nowon-gu, Seoul, 01795, Republic of Korea
| | - Hee Jin Kim
- Uimyung Research Institute for Neuroscience, Department of Pharmacy, Sahmyook University, 815 Hwarang-ro, Nowon-gu, Seoul, 01795, Republic of Korea
| | - Jae Hoon Cheong
- Uimyung Research Institute for Neuroscience, Department of Pharmacy, Sahmyook University, 815 Hwarang-ro, Nowon-gu, Seoul, 01795, Republic of Korea.
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Tosh DK, Janowsky A, Eshleman AJ, Warnick E, Gao ZG, Chen Z, Gizewski E, Auchampach JA, Salvemini D, Jacobson KA. Scaffold Repurposing of Nucleosides (Adenosine Receptor Agonists): Enhanced Activity at the Human Dopamine and Norepinephrine Sodium Symporters. J Med Chem 2017; 60:3109-3123. [PMID: 28319392 PMCID: PMC5501184 DOI: 10.1021/acs.jmedchem.7b00141] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
We have repurposed (N)-methanocarba adenosine derivatives (A3 adenosine receptor (AR) agonists) to enhance radioligand binding allosterically at the human dopamine (DA) transporter (DAT) and inhibit DA uptake. We extended the structure-activity relationship of this series with small N6-alkyl substitution, 5'-esters, deaza modifications of adenine, and ribose restored in place of methanocarba. C2-(5-Halothien-2-yl)-ethynyl 5'-methyl 9 (MRS7292) and 5'-ethyl 10 (MRS7232) esters enhanced binding at DAT (EC50 ∼ 35 nM) and at the norepinephrine transporter (NET). 9 and 10 were selective for DAT compared to A3AR in the mouse but not in humans. At DAT, the binding of two structurally dissimilar radioligands was enhanced; NET binding of only one radioligand was enhanced; SERT radioligand binding was minimally affected. 10 was more potent than cocaine at inhibiting DA uptake (IC50 = 107 nM). Ribose analogues were weaker in DAT interaction than the corresponding bicyclics. Thus, we enhanced the neurotransmitter transporter activity of rigid nucleosides while reducing A3AR affinity.
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Affiliation(s)
- Dilip K. Tosh
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892 USA
| | - Aaron Janowsky
- VA Portland Health Care System, Research Service (R&D-22), and Departments of Psychiatry and Behavioral Neuroscience, Oregon Health and Science Univ., Portland, Oregon 97239 USA
| | - Amy J. Eshleman
- VA Portland Health Care System, Research Service (R&D-22), and Departments of Psychiatry and Behavioral Neuroscience, Oregon Health and Science Univ., Portland, Oregon 97239 USA
| | - Eugene Warnick
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892 USA
| | - Zhan-Guo Gao
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892 USA
| | - Zhoumou Chen
- Department of Pharmacology and Physiology, Saint Louis University School of Medicine, St. Louis, Missouri USA 63104
| | - Elizabeth Gizewski
- Department of Pharmacology, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, Wisconsin 53226 USA
| | - John A. Auchampach
- Department of Pharmacology, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, Wisconsin 53226 USA
| | - Daniela Salvemini
- Department of Pharmacology and Physiology, Saint Louis University School of Medicine, St. Louis, Missouri USA 63104
| | - Kenneth A. Jacobson
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892 USA
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Rastedt DE, Vaughan RA, Foster JD. Palmitoylation mechanisms in dopamine transporter regulation. J Chem Neuroanat 2017; 83-84:3-9. [PMID: 28115272 DOI: 10.1016/j.jchemneu.2017.01.002] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Revised: 12/21/2016] [Accepted: 01/17/2017] [Indexed: 02/01/2023]
Abstract
The neurotransmitter dopamine (DA) plays a key role in several biological processes including reward, mood, motor activity and attention. Synaptic DA homeostasis is controlled by the dopamine transporter (DAT) which transports extracellular DA into the presynaptic neuron after release and regulates its availability to receptors. Many neurological disorders such as schizophrenia, bipolar disorder, Parkinson disease and attention-deficit hyperactivity disorder are associated with imbalances in DA homeostasis that may be related to DAT dysfunction. DAT is also a target of psychostimulant and therapeutic drugs that inhibit DA reuptake and lead to elevated dopaminergic neurotransmission. We have recently demonstrated the acute and chronic modulation of DA reuptake activity and DAT stability through S-palmitoylation, the linkage of a 16-carbon palmitate group to cysteine via a thioester bond. This review summarizes the properties and regulation of DAT palmitoylation and describes how it serves to affect various transporter functions. Better understanding of the role of palmitoylation in regulation of DAT function may lead to identification of therapeutic targets for modulation of DA homeostasis in the treatment of dopaminergic disorders.
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Affiliation(s)
- Danielle E Rastedt
- Department of Biomedical Sciences, University of North Dakota, School of Medicine and Health Sciences, Grand Forks, ND 58202, United States
| | - Roxanne A Vaughan
- Department of Biomedical Sciences, University of North Dakota, School of Medicine and Health Sciences, Grand Forks, ND 58202, United States
| | - James D Foster
- Department of Biomedical Sciences, University of North Dakota, School of Medicine and Health Sciences, Grand Forks, ND 58202, United States.
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Lohr KM, Masoud ST, Salahpour A, Miller GW. Membrane transporters as mediators of synaptic dopamine dynamics: implications for disease. Eur J Neurosci 2017; 45:20-33. [PMID: 27520881 PMCID: PMC5209277 DOI: 10.1111/ejn.13357] [Citation(s) in RCA: 73] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2016] [Revised: 07/12/2016] [Accepted: 08/02/2016] [Indexed: 12/14/2022]
Abstract
Dopamine was first identified as a neurotransmitter localized to the midbrain over 50 years ago. The dopamine transporter (DAT; SLC6A3) and the vesicular monoamine transporter 2 (VMAT2; SLC18A2) are regulators of dopamine homeostasis in the presynaptic neuron. DAT transports dopamine from the extracellular space into the cytosol of the presynaptic terminal. VMAT2 then packages this cytosolic dopamine into vesicular compartments for subsequent release upon neurotransmission. Thus, DAT and VMAT2 act in concert to move the transmitter efficiently throughout the neuron. Accumulation of dopamine in the neuronal cytosol can trigger oxidative stress and neurotoxicity, suggesting that the proper compartmentalization of dopamine is critical for neuron function and risk of disease. For decades, studies have examined the effects of reduced transporter function in mice (e.g. DAT-KO, VMAT2-KO, VMAT2-deficient). However, we have only recently been able to assess the effects of elevated transporter expression using BAC transgenic methods (DAT-tg, VMAT2-HI mice). Complemented with in vitro work and neurochemical techniques to assess dopamine compartmentalization, a new focus on the importance of transporter proteins as both models of human disease and potential drug targets has emerged. Here, we review the importance of DAT and VMAT2 function in the delicate balance of neuronal dopamine.
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Affiliation(s)
- Kelly M Lohr
- Department of Environmental Health, Rollins School of Public Health, Emory University, 1518 Clifton Road, Atlanta, GA, 30322, USA
| | - Shababa T Masoud
- Department of Pharmacology and Toxicology, University of Toronto, ON, Canada
| | - Ali Salahpour
- Department of Pharmacology and Toxicology, University of Toronto, ON, Canada
| | - Gary W Miller
- Department of Environmental Health, Rollins School of Public Health, Emory University, 1518 Clifton Road, Atlanta, GA, 30322, USA
- Center for Neurodegenerative Diseases, Emory University, Atlanta, GA, USA
- Department of Pharmacology, Emory University, Atlanta, GA, USA
- Department of Neurology, Emory University, Atlanta, GA, USA
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50
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Sweeney CG, Tremblay BP, Stockner T, Sitte HH, Melikian HE. Dopamine Transporter Amino and Carboxyl Termini Synergistically Contribute to Substrate and Inhibitor Affinities. J Biol Chem 2016; 292:1302-1309. [PMID: 27986813 DOI: 10.1074/jbc.m116.762872] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2016] [Revised: 12/09/2016] [Indexed: 11/06/2022] Open
Abstract
Extracellular dopamine and serotonin concentrations are determined by the presynaptic dopamine (DAT) and serotonin (SERT) transporters, respectively. Numerous studies have investigated the DAT and SERT structural elements contributing to inhibitor and substrate binding. To date, crystallographic studies have focused on conserved transmembrane domains, where multiple substrate binding and translocation features are conserved. However, it is unknown what, if any, role the highly divergent intracellular N and C termini contribute to these processes. Here, we used chimeric proteins to test whether DAT and SERT N and C termini contribute to transporter substrate and inhibitor affinities. Replacing the DAT N terminus with that of SERT had no effect on DA transport Vmax but significantly decreased DAT substrate affinities for DA and amphetamine. Similar losses in uptake inhibition were observed for small DAT inhibitors, whereas substituting the DAT C terminus with that of SERT affected neither substrate nor inhibitor affinities. In contrast, the N-terminal substitution was completely tolerated by the larger DAT inhibitors, which exhibited no loss in apparent affinity. Remarkably, all affinity losses were rescued in DAT chimeras encoding both SERT N and C termini. The sensitivity to amino-terminal substitution was specific for DAT, because replacing the SERT N and/or C termini affected neither substrate nor inhibitor affinities. Taken together, these findings provide compelling experimental evidence that DAT N and C termini synergistically contribute to substrate and inhibitor affinities.
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Affiliation(s)
- Carolyn G Sweeney
- From the Brudnick Neuropsychiatric Research Institute, Department of Psychiatry, University of Massachusetts Medical School, Worcester, Massachusetts 01604 and
| | - Bradford P Tremblay
- From the Brudnick Neuropsychiatric Research Institute, Department of Psychiatry, University of Massachusetts Medical School, Worcester, Massachusetts 01604 and
| | - Thomas Stockner
- the Institute for Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, 1090 Vienna, Austria
| | - Harald H Sitte
- the Institute for Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, 1090 Vienna, Austria
| | - Haley E Melikian
- From the Brudnick Neuropsychiatric Research Institute, Department of Psychiatry, University of Massachusetts Medical School, Worcester, Massachusetts 01604 and
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