1
|
Neumann J, Hußler W, Hofmann B, Gergs U. Contractile Effects of Amphetamine, Pseudoephedrine, Nor-pseudoephedrine (Cathine), and Cathinone on Atrial Preparations of Mice and Humans. J Cardiovasc Pharmacol 2024; 83:243-250. [PMID: 38181215 DOI: 10.1097/fjc.0000000000001536] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/05/2023] [Accepted: 12/11/2023] [Indexed: 01/07/2024]
Abstract
ABSTRACT Amphetamine derivatives are used worldwide legally or illegally and intoxications may be accompanied by cardiac arrhythmias. Here, we tested contractile effects of cumulative applied (±)-amphetamine, pseudoephedrine, nor-pseudoephedrine (cathine), and cathinone in electrically stimulated (1 Hz) human right atrial preparations (HAP) and mouse left atrial preparations and in spontaneously beating mouse right atrial preparations. In mouse atrial preparations, amphetamine increased force of contraction and beating rate in a concentration- and time-dependent manner, starting at 1 µM in left atrial preparations to 157.1% ± 3.0% and right atrial preparations to 146.6% ± 9.8% at 10 µM, respectively [mean ± standard error of the mean (SEM); n = 5; P < 0.05]. Pseudoephedrine, cathine, or cathinone alone were ineffective in mouse atrial preparations but after pre-incubation with the phosphodiesterase IV inhibitor rolipram (0.1 µM), a positive inotropic effect was noted (mean ± SEM: pseudoephedrine: 112.3% ± 9.8%; cathine: 109.0% ± 4.3%; cathinone: 138.3% ± 21.2%). The effects of all drugs were greatly attenuated by 10 µM cocaine or 10 µM propranolol treatments. However, In HAP, not only amphetamine (to a mean ± SEM of 208% ± 32%) but also pseudoephedrine (to a mean ± SEM of 287% ± 60%), cathine (to a mean ± SEM of 234% ± 52%), and cathinone (to a mean ± SEM of 217% ± 65%) increased force of contraction without the need of phosphodiesterase inhibition. The contractile effects in HAP were attenuated by 10 µM cocaine and antagonized by 10 µM propranolol. We conclude that amphetamine, pseudoephedrine, cathine, and cathinone act probably via release of noradrenaline from cardiac stores as indirect sympathomimetic agents in mouse and more pronounced in human atrial preparations.
Collapse
Affiliation(s)
- Joachim Neumann
- Institute for Pharmacology and Toxicology, Medical Faculty, Martin Luther University Halle-Wittenberg, Halle, Germany; and
| | - Wilhelm Hußler
- Institute for Pharmacology and Toxicology, Medical Faculty, Martin Luther University Halle-Wittenberg, Halle, Germany; and
| | - Britt Hofmann
- Department of Cardiac Surgery, Mid-German Heart Center, University Hospital Halle, Halle, Germany
| | - Ulrich Gergs
- Institute for Pharmacology and Toxicology, Medical Faculty, Martin Luther University Halle-Wittenberg, Halle, Germany; and
| |
Collapse
|
2
|
Chen R. Cholesterol modulation of interactions between psychostimulants and dopamine transporters. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2023; 99:35-59. [PMID: 38467486 DOI: 10.1016/bs.apha.2023.09.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/13/2024]
Abstract
The dopamine transporter (DAT) is a key site of action for cocaine and amphetamines. Dysfunctional DAT is associated with aberrant synaptic dopamine transmission and enhanced drug-seeking and taking behavior. Studies in cultured cells and ex vivo suggest that DAT function is sensitive to membrane cholesterol content. Although it is largely unknown whether psychostimulants alter cholesterol metabolism in the brain, emerging evidence indicates that peripheral cholesterol metabolism is altered in patients with psychostimulant use disorder and circulating cholesterol levels are associated with vulnerability to relapse. Cholesterol interacts with sphingolipids forming lipid raft microdomains on the membrane. These cholesterol-rich lipid raft microdomains serve to recruit and assemble other lipids and proteins to initiate signal transduction. There are two spatially and functionally distinct populations of the DAT segregated by cholesterol-rich lipid raft microdomains and cholesterol-scarce non-raft microdomains on the plasma membrane. These two DAT populations are differentially regulated by DAT blockers (e.g. cocaine), substrates (e.g. amphetamine), and protein kinase C providing distinct cholesterol-dependent modulation of dopamine uptake and efflux. In this chapter, we summarize the impact of depletion and addition of membrane cholesterol on DAT conformational changes between the outward-facing and the inward-facing states, lipid raft-associated DAT localization, basal and induced DAT internalization, and DAT function. In particular, we focus on how the interactions of the DAT with cocaine and amphetamine are influenced by membrane cholesterol. Lastly, we discuss the therapeutic potential of cholesterol-modifying drugs as a new avenue to normalize DAT function and dopamine transmission in patients with psychostimulant use disorder.
Collapse
Affiliation(s)
- Rong Chen
- Department of Physiology & Pharmacology, Wake Forest University School of Medicine, Winston Salem, NC, United States.
| |
Collapse
|
3
|
Nguyen VT, Harris AC, Eltit JM. Structural and functional perspectives on interactions between synthetic cathinones and monoamine transporters. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2023; 99:83-124. [PMID: 38467490 DOI: 10.1016/bs.apha.2023.09.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/13/2024]
Abstract
Synthetic cathinone derivatives comprise a family of psychoactive compounds structurally related to amphetamine. Over the last decade, clandestine chemists have synthesized a consistent stream of innovative cathinone derivatives to outpace governmental regulatory restrictions. Many of these unregulated substances are produced and distributed as designer drugs. Two of the principal chemical scaffolds exploited to expand the synthetic cathinone family are methcathinone and α-pyrrolidinopentiophenone (or α-pyrrolidinovalerophenone, α-PVP). These compounds' main physiological targets are monoamine transporters, where they promote addiction by potentiating dopaminergic neurotransmission. This chapter describes techniques used to study the pharmacodynamic properties of cathinones at monoamine transporters in vitro. Biochemical techniques described include uptake inhibition and release assays in rat brain synaptosomes and in mammalian expression systems. Electrophysiological techniques include current measurements using the voltage clamp technique. We describe a Ca2+ mobilization assay wherein voltage-gated Ca2+ channels function as reporters to study the action of synthetic cathinones at monoamine transporters. We discuss results from systematic structure-activity relationship studies on simple and complex cathinones at monoamine transporters with an emphasis on identifying structural moieties that modulate potency and selectivity at these transporters. Moreover, different profiles of selectivity at monoamine transporters directly predict compounds associated with behavioral and subjective effects within animals and humans. In conclusion, clarification of the structural aspects of compounds which modulate potency and selectivity at monoamine transporters is critical to identify and predict potential addictive drugs. This knowledge may allow prompt allocation of resources toward drugs that represent the greatest threats after drugs are identified by forensic laboratories.
Collapse
Affiliation(s)
- Vy T Nguyen
- Department of Physiology and Biophysics, School of Medicine, Virginia Commonwealth University, Richmond, VA, United States
| | - Alan C Harris
- Department of Physiology and Biophysics, School of Medicine, Virginia Commonwealth University, Richmond, VA, United States
| | - Jose M Eltit
- Department of Physiology and Biophysics, School of Medicine, Virginia Commonwealth University, Richmond, VA, United States.
| |
Collapse
|
4
|
Yang D, Zhao Z, Tajkhorshid E, Gouaux E. Structures and membrane interactions of native serotonin transporter in complexes with psychostimulants. Proc Natl Acad Sci U S A 2023; 120:e2304602120. [PMID: 37436958 PMCID: PMC10629533 DOI: 10.1073/pnas.2304602120] [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: 03/20/2023] [Accepted: 05/03/2023] [Indexed: 07/14/2023] Open
Abstract
The serotonin transporter (SERT) is a member of the SLC6 neurotransmitter transporter family that mediates serotonin reuptake at presynaptic nerve terminals. SERT is the target of both therapeutic antidepressant drugs and psychostimulant substances such as cocaine and methamphetamines, which are small molecules that perturb normal serotonergic transmission by interfering with serotonin transport. Despite decades of studies, important functional aspects of SERT such as the oligomerization state of native SERT and its interactions with potential proteins remain unresolved. Here, we develop methods to isolate SERT from porcine brain (pSERT) using a mild, nonionic detergent, utilize fluorescence-detection size-exclusion chromatography to investigate its oligomerization state and interactions with other proteins, and employ single-particle cryo-electron microscopy to elucidate the structures of pSERT in complexes with methamphetamine or cocaine, providing structural insights into psychostimulant recognition and accompanying pSERT conformations. Methamphetamine and cocaine both bind to the central site, stabilizing the transporter in an outward open conformation. We also identify densities attributable to multiple cholesterol or cholesteryl hemisuccinate (CHS) molecules, as well as to a detergent molecule bound to the pSERT allosteric site. Under our conditions of isolation, we find that pSERT is best described as a monomeric entity, isolated without interacting proteins, and is ensconced by multiple cholesterol or CHS molecules.
Collapse
Affiliation(s)
- Dongxue Yang
- Vollum Institute, Oregon Health and Science University, Portland, OR97239
| | - Zhiyu Zhao
- Department of Biochemistry, NIH Center for Macromolecular Modeling and Visualization, Beckman Institute for Advanced Science and Technology, and Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, IL61801
| | - Emad Tajkhorshid
- Department of Biochemistry, NIH Center for Macromolecular Modeling and Visualization, Beckman Institute for Advanced Science and Technology, and Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, IL61801
| | - Eric Gouaux
- Vollum Institute, Oregon Health and Science University, Portland, OR97239
- HHMI, Oregon Health and Science University, Portland, OR97239
| |
Collapse
|
5
|
Wilson JR, Garner EM, Mashayekhi M, Hubers SA, Ramirez Bustamante CE, Kerman SJ, Nian H, Shibao CA, Brown NJ. DPP4 (Dipeptidyl Peptidase-4) Inhibition Increases Catecholamines Without Increasing Blood Pressure During Sustained ACE (Angiotensin-Converting Enzyme) Inhibitor Treatment. Hypertension 2022; 79:827-835. [PMID: 35045722 PMCID: PMC8917054 DOI: 10.1161/hypertensionaha.121.18348] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND DPP4 (dipeptidyl peptidase-4) inhibitors comprise a class of oral diabetes medication that have the potential for off-target cardiovascular effects. We previously showed that DPP4 inhibition attenuates the hypotensive effect of acute ACE (angiotensin-converting enzyme) inhibition and increases norepinephrine. Here, we investigated the effects of DPP4 during sustained ACE inhibition compared with during therapy with an ARB (angiotensin receptor blocker) or calcium channel blocker (neutral comparator) in a randomized, double-blinded crossover study. METHODS We enrolled 106 adults with type 2 diabetes and hypertension and 100 received intervention. Subjects were randomized to one of 3 blood pressure arms: ramipril, valsartan, or amlodipine for a total of 15 weeks and received 3 one-week crossover therapies in random order: placebo + placebo, sitagliptin + placebo, and sitagliptin + aprepitant separated by 4-week washout. RESULTS We found that DPP4 inhibition increased norepinephrine during ramipril but did not increase blood pressure. Aprepitant, a NK1 (substance P) receptor blocker, lowered standing heart rate during renin-angiotensin-aldosterone system blockade with ramipril or valsartan. CONCLUSIONS Increased catecholamines during concurrent ACE and DPP4 inhibition may contribute to cardiovascular complications in patients predisposed to heart failure.
Collapse
Affiliation(s)
- Jessica R Wilson
- Division of Clinical Pharmacology, Vanderbilt Department of Medicine. (J.R.W., S.A.H., C.E.R.B., S.J.K., N.J.B.).,Division of Endocrinology, Diabetes, and Metabolism, Vanderbilt Department of Medicine. (J.R.W., E.M.G., M.M., C.A.S.).,Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, Mayo Clinic Florida (J.R.W.)
| | - Erica M Garner
- Division of Endocrinology, Diabetes, and Metabolism, Vanderbilt Department of Medicine. (J.R.W., E.M.G., M.M., C.A.S.)
| | - Mona Mashayekhi
- Division of Endocrinology, Diabetes, and Metabolism, Vanderbilt Department of Medicine. (J.R.W., E.M.G., M.M., C.A.S.)
| | - Scott A Hubers
- Division of Clinical Pharmacology, Vanderbilt Department of Medicine. (J.R.W., S.A.H., C.E.R.B., S.J.K., N.J.B.).,Division of Cardiology, Department of Medicine, University of Minnesota (S.A.H.)
| | - Claudia E Ramirez Bustamante
- Division of Clinical Pharmacology, Vanderbilt Department of Medicine. (J.R.W., S.A.H., C.E.R.B., S.J.K., N.J.B.).,Department of Medicine, Baylor College of Medicine (C.E.R.B.)
| | - Scott Jafarian Kerman
- Division of Clinical Pharmacology, Vanderbilt Department of Medicine. (J.R.W., S.A.H., C.E.R.B., S.J.K., N.J.B.)
| | - Hui Nian
- Department of Biostatistics, Vanderbilt University (H.N.)
| | - Cyndya A Shibao
- Division of Endocrinology, Diabetes, and Metabolism, Vanderbilt Department of Medicine. (J.R.W., E.M.G., M.M., C.A.S.)
| | - Nancy J Brown
- Division of Clinical Pharmacology, Vanderbilt Department of Medicine. (J.R.W., S.A.H., C.E.R.B., S.J.K., N.J.B.).,Department of Medicine, Yale School of Medicine (N.J.B.)
| |
Collapse
|
6
|
Pino JA, Nuñez-Vivanco G, Hidalgo G, Reyes Parada M, Khoshbouei H, Torres GE. Identification of Critical Residues in the Carboxy Terminus of the Dopamine Transporter Involved in the G Protein βγ-Induced Dopamine Efflux. Front Pharmacol 2021; 12:642881. [PMID: 33841159 PMCID: PMC8025876 DOI: 10.3389/fphar.2021.642881] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Accepted: 02/11/2021] [Indexed: 11/13/2022] Open
Abstract
The dopamine transporter (DAT) plays a crucial role in the regulation of brain dopamine (DA) homeostasis through the re-uptake of DA back into the presynaptic terminal. In addition to re-uptake, DAT is also able to release DA through a process referred to as DAT-mediated DA efflux. This is the mechanism by which potent and highly addictive psychostimulants, such as amphetamine (AMPH) and its analogues, increase extracellular DA levels in motivational and reward areas of the brain. Recently, we discovered that G protein βγ subunits (Gβγ) binds to the DAT, and that activation of Gβγ results in DAT-mediated efflux - a similar mechanism as AMPH. Previously, we have shown that Gβγ binds directly to a stretch of 15 residues within the intracellular carboxy terminus of DAT (residues 582-596). Additionally, a TAT peptide containing residues 582 to 596 of DAT was able to block the Gβγ-induced DA efflux through DAT. Here, we use a combination of computational biology, mutagenesis, biochemical, and functional assays to identify the amino acid residues within the 582-596 sequence of the DAT carboxy terminus involved in the DAT-Gβγ interaction and Gβγ-induced DA efflux. Our in-silico protein-protein docking analysis predicted the importance of F587 and R588 residues in a network of interactions with residues in Gβγ. In addition, we observed that mutating R588 to alanine residue resulted in a mutant DAT which exhibited attenuated DA efflux induced by Gβγ activation. We demonstrate that R588, and to a lesser extent F5837, located within the carboxy terminus of DAT play a critical role in the DAT-Gβγ physical interaction and promotion of DA efflux. These results identify a potential new pharmacological target for the treatment of neuropsychiatric conditions in which DAT functionality is implicated including ADHD and substance use disorder.
Collapse
Affiliation(s)
- José A Pino
- Departamento de Medicina, Facultad de Medicina, Universidad de Atacama, Copiapó, Chile
| | - Gabriel Nuñez-Vivanco
- Centro de Bioinformática, Simulación y Modelado, Facultad de Ingeniería, Universidad de Talca, Talca, Chile
| | - Gabriela Hidalgo
- Department of Pharmacology and Therapeutics, University of Florida College of Medicine, Gainesville, FL, United States
| | - Miguel Reyes Parada
- Centro de Investigación Biomédica y Aplicada (CIBAP), Escuela de Medicina, Facultad de Ciencias Médicas, Universidad de Santiago de Chile, Santiago, Chile.,Facultad de Ciencias de la Salud, Universidad Autónoma de Chile, Talca, Chile
| | - Habibeh Khoshbouei
- Department of Neuroscience, University of Florida College of Medicine, Gainesville, FL, United States
| | - Gonzalo E Torres
- Department of Molecular, Cellular and Biomedical Sciences, CUNY School of Medicine at City College of New York, New York, NY, United States
| |
Collapse
|
7
|
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.
Collapse
|
8
|
Chen R, Ferris MJ, Wang S. Dopamine D2 autoreceptor interactome: Targeting the receptor complex as a strategy for treatment of substance use disorder. Pharmacol Ther 2020; 213:107583. [PMID: 32473160 PMCID: PMC7434700 DOI: 10.1016/j.pharmthera.2020.107583] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2019] [Accepted: 05/11/2020] [Indexed: 02/06/2023]
Abstract
Dopamine D2 autoreceptors (D2ARs), located in somatodendritic and axon terminal compartments of dopamine (DA) neurons, function to provide a negative feedback regulatory control on DA neuron firing, DA synthesis, reuptake and release. Dysregulation of D2AR-mediated DA signaling is implicated in vulnerability to substance use disorder (SUD). Due to the extreme low abundance of D2ARs compared to postsynaptic D2 receptors (D2PRs) and the lack of experimental tools to differentiate the signaling of D2ARs from D2PRs, the regulation of D2ARs by drugs of abuse is poorly understood. The recent availability of conditional D2AR knockout mice and newly developed virus-mediated gene delivery approaches have provided means to specifically study the function of D2ARs at the molecular, cellular and behavioral levels. There is a growing revelation of novel mechanisms and new proteins that mediate D2AR activity, suggesting that D2ARs act cooperatively with an array of membrane and intracellular proteins to tightly control DA transmission. This review highlights D2AR-interacting partners including transporters, G-protein-coupled receptors, ion channels, intracellular signaling modulators, and protein kinases. The complexity of the D2AR interaction network illustrates the functional divergence of D2ARs. Pharmacological targeting of multiple D2AR-interacting partners may be more effective to restore disrupted DA homeostasis by drugs of abuse.
Collapse
Affiliation(s)
- Rong Chen
- Dept. of Physiology & Pharmacology, Wake Forest School of Medicine, Winston Salem, NC 27157, United States of America; Center for the Neurobiology of Addiction Treatment, Wake Forest School of Medicine, Winston Salem, NC 27157, United States of America.
| | - Mark J Ferris
- Dept. of Physiology & Pharmacology, Wake Forest School of Medicine, Winston Salem, NC 27157, United States of America; Center for the Neurobiology of Addiction Treatment, Wake Forest School of Medicine, Winston Salem, NC 27157, United States of America
| | - Shiyu Wang
- Dept. of Physiology & Pharmacology, Wake Forest School of Medicine, Winston Salem, NC 27157, United States of America
| |
Collapse
|
9
|
Zhang-James Y, Vaudel M, Mjaavatten O, Berven FS, Haavik J, Faraone SV. Effect of disease-associated SLC9A9 mutations on protein-protein interaction networks: implications for molecular mechanisms for ADHD and autism. ACTA ACUST UNITED AC 2019; 11:91-105. [PMID: 30927234 DOI: 10.1007/s12402-018-0281-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2018] [Accepted: 11/27/2018] [Indexed: 12/20/2022]
Abstract
Na+/H+ Exchanger 9 (NHE9) is an endosomal membrane protein encoded by the Solute Carrier 9A, member 9 gene (SLC9A9). SLC9A9 has been implicated in attention deficit hyperactivity disorder (ADHD), autism spectrum disorders (ASDs), epilepsy, multiple sclerosis and cancers. To better understand the function of NHE9 and the effects of disease-associated variants on protein-protein interactions, we conducted a quantitative analysis of the NHE9 interactome using co-immunoprecipitation and isobaric labeling-based quantitative mass spectrometry. We identified 100 proteins that interact with NHE9. These proteins were enriched in known functional pathways for NHE9: the endocytosis, protein ubiquitination and phagosome pathways, as well as some novel pathways including oxidative stress, mitochondrial dysfunction, mTOR signaling, cell death and RNA processing pathways. An ADHD-associated mutation (A409P) significantly altered NHE9's interactions with a subset of proteins involved in caveolae-mediated endocytosis and MAP2K2-mediated downstream signaling. An ASD nonsense mutation in SLC9A9, R423X, produced no-detectable amount of NHE9, suggesting the overall loss of NHE9 functional networks. In addition, seven of the NHE9 interactors are products of known autism candidate genes (Simons Foundation Autism Research Initiative, SFARI Gene) and 90% of the NHE9 interactome overlap with SFARI protein interaction network PIN (p < 0.0001), supporting the role of NHE9 interactome in ASDs molecular mechanisms. Our results provide a detailed understanding of the functions of protein NHE9 and its disrupted interactions, possibly underlying ADHD and ASDs. Furthermore, our methodological framework proved useful for functional characterization of disease-associated genetic variants and suggestion of druggable targets.
Collapse
Affiliation(s)
- Yanli Zhang-James
- Departments of Psychiatry, SUNY Upstate Medical University, 750 East Adams St., Syracuse, NY, 13210, USA
| | - Marc Vaudel
- Department of Clinical Science, University of Bergen, Bergen, Norway
| | - Olav Mjaavatten
- Department of Biomedicine, University of Bergen, Bergen, Norway
| | - Frode S Berven
- Department of Biomedicine, University of Bergen, Bergen, Norway
| | - Jan Haavik
- Department of Biomedicine, University of Bergen, Bergen, Norway.,K.G. Jebsen Centre for Research on Neuropsychiatric Disorders, University of Bergen, Bergen, Norway.,Division of Psychiatry, Haukeland University Hospital, Bergen, Norway
| | - Stephen V Faraone
- Departments of Psychiatry, SUNY Upstate Medical University, 750 East Adams St., Syracuse, NY, 13210, USA. .,Neuroscience and Physiology, SUNY Upstate Medical University, 750 East Adams St., Syracuse, NY, 13210, USA.
| |
Collapse
|
10
|
Bartolomé-Martín D, Ibáñez I, Piniella D, Martínez-Blanco E, Pelaz SG, Zafra F. Identification of potassium channel proteins Kv7.2/7.3 as common partners of the dopamine and glutamate transporters DAT and GLT-1. Neuropharmacology 2019; 161:107568. [PMID: 30885609 DOI: 10.1016/j.neuropharm.2019.03.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2018] [Revised: 02/19/2019] [Accepted: 03/06/2019] [Indexed: 12/12/2022]
Abstract
Dopamine and glutamate transporters (DAT and GLT-1, respectively) share some biophysical characteristics, as both are secondary active carriers coupled to electrochemical ion gradients. In order to identify common or specific components of their respective proteomes, we performed a proximity labelling assay (BioID) in the hippocampal cell line HT22. While most of the identified proteins were specific for each transporter (and will be analyzed elsewhere), we detected two membrane proteins in the shared interactome of GLT-1 and DAT: the transmembrane protein 263 (Tmem263) and the potassium channel protein Kv7.3. However, only Kv7.3 formed immunoprecipitable complexes with GLT-1 and DAT in lysates of transfected HEK293 cells. Moreover, either DAT or GLT-1 co-clustered with Kv7.2/7.3 along the axonal tracts in co-transfected primary neurons, indicating a close spatial proximity between these proteins. Kv7.3, forming heterotetramers with the closely related subunit Kv7.2, underlies the M-currents that control the resting membrane potential and spiking activity in neurons. To investigate whether the presence of the potassium channel affected DAT or GLT-1 function, we performed uptake determinations using radioactive substrate and electrophysiological measurements. Uptake through both transporters was mildly stimulated by the presence of the channel, an effect that was reversed by the potassium channel blocker XE-991. Electrophysiological recording (in transfected HT22 and differentiated SH-SY5Y cells) indicated that the depolarizing effect induced by the presence of the neurotransmitter was reverted by the activity of the potassium channel. Altogether, these data suggest a tight spatial and functional relationship between the DAT/GLT-1 transporters and the Kv7.2/7.3 potassium channel that immediately readjusts the membrane potential of the neuron, probably to limit the neurotransmitter-mediated neuronal depolarization. This article is part of the issue entitled 'Special Issue on Neurotransmitter Transporters'.
Collapse
Affiliation(s)
- David Bartolomé-Martín
- Centro de Biología Molecular Severo Ochoa, Facultad de Ciencias, Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, Madrid, Spain; IdiPAZ, Instituto de Salud Carlos III, Madrid, Spain
| | - Ignacio Ibáñez
- Centro de Biología Molecular Severo Ochoa, Facultad de Ciencias, Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, Madrid, Spain; IdiPAZ, Instituto de Salud Carlos III, Madrid, Spain
| | - Dolores Piniella
- Centro de Biología Molecular Severo Ochoa, Facultad de Ciencias, Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, Madrid, Spain; IdiPAZ, Instituto de Salud Carlos III, Madrid, Spain
| | - Elena Martínez-Blanco
- Centro de Biología Molecular Severo Ochoa, Facultad de Ciencias, Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, Madrid, Spain; IdiPAZ, Instituto de Salud Carlos III, Madrid, Spain
| | - Sara G Pelaz
- Centro de Biología Molecular Severo Ochoa, Facultad de Ciencias, Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, Madrid, Spain
| | - Francisco Zafra
- Centro de Biología Molecular Severo Ochoa, Facultad de Ciencias, Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, Madrid, Spain; IdiPAZ, Instituto de Salud Carlos III, Madrid, Spain.
| |
Collapse
|
11
|
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]
|
12
|
Markos S, Failla MD, Ritter AC, Dixon CE, Conley YP, Ricker JH, Arenth PM, Juengst SB, Wagner AK. Genetic Variation in the Vesicular Monoamine Transporter: Preliminary Associations With Cognitive Outcomes After Severe Traumatic Brain Injury. J Head Trauma Rehabil 2018; 32:E24-E34. [PMID: 26828714 PMCID: PMC4967045 DOI: 10.1097/htr.0000000000000224] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
INTRODUCTION Traumatic brain injury (TBI) frequently results in impaired cognition, a function that can be modulated by monoaminergic signaling. Genetic variation among monoaminergic genes may affect post-TBI cognitive performance. The vesicular monoamine transporter-2 (VMAT2) gene may be a novel source of genetic variation important for cognitive outcomes post-TBI given VMAT2's role in monoaminergic neurotransmission. OBJECTIVE To evaluate associations between VMAT2 variability and cognitive outcomes post-TBI. METHODS We evaluated 136 white adults with severe TBI for variation in VMAT2 using a tagging single nucleotide polymorphism (tSNP) approach (rs363223, rs363226, rs363251, and rs363341). We show genetic variation interacts with assessed cognitive impairment (cognitive composite [Comp-Cog] T-scores) to influence functional cognition (functional independence measure cognitive [FIM-Cog] subscale] 6 and 12 months postinjury. RESULTS Multivariate analyses at 6 months postinjury showed rs363226 genotype was associated with Comp-Cog (P = .040) and interacted with Comp-Cog to influence functional cognition (P < .001). G-homozygotes had the largest cognitive impairment, and their cognitive impairment had the greatest adverse effect on functional cognition. DISCUSSION We provide the first evidence that genetic variation within VMAT2 is associated with cognitive outcomes after TBI. Further work is needed to validate this finding and elucidate mechanisms by which genetic variation affects monoaminergic signaling, mediating differences in cognitive outcomes.
Collapse
Affiliation(s)
- Steven Markos
- Department of Physical Medicine & Rehabilitation, University of Pittsburgh, School of Medicine, Pittsburgh PA
| | - Michelle D. Failla
- Department of Physical Medicine & Rehabilitation, University of Pittsburgh, School of Medicine, Pittsburgh PA
- Department of Neuroscience, University of Pittsburgh, Pittsburgh, PA
| | - Anne C Ritter
- Department of Physical Medicine & Rehabilitation, University of Pittsburgh, School of Medicine, Pittsburgh PA
| | - C. Edward Dixon
- Department of Physical Medicine & Rehabilitation, University of Pittsburgh, School of Medicine, Pittsburgh PA
- Center for Neuroscience, University of Pittsburgh
- Pittsburgh VA Healthcare System
- Department of Neurological Surgery, School of Medicine, University of Pittsburgh
| | - Yvette P. Conley
- Department of Human Genetics, University of Pittsburgh, School of Public Health, Pittsburgh, PA
- Health Promotion & Development, University of Pittsburgh, School of Nursing, Pittsburgh, PA
| | - Joseph H Ricker
- Department of Rehabilitation Medicine, New York University, School of Medicine, New York, NY
| | - Patricia M. Arenth
- Department of Physical Medicine & Rehabilitation, University of Pittsburgh, School of Medicine, Pittsburgh PA
| | - Shannon B. Juengst
- Department of Physical Medicine & Rehabilitation, University of Pittsburgh, School of Medicine, Pittsburgh PA
| | - Amy K. Wagner
- Department of Physical Medicine & Rehabilitation, University of Pittsburgh, School of Medicine, Pittsburgh PA
- Department of Neuroscience, University of Pittsburgh, Pittsburgh, PA
- Center for Neuroscience, University of Pittsburgh
- Safar Center for Resuscitation Research, University of Pittsburgh, Pittsburgh, PA
| |
Collapse
|
13
|
Morissette M, Morin N, Rouillard C, Di Paolo T. Membrane cholesterol removal and replenishment affect rat and monkey brain monoamine transporters. Neuropharmacology 2018; 133:289-306. [PMID: 29407218 DOI: 10.1016/j.neuropharm.2018.01.039] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Revised: 01/10/2018] [Accepted: 01/25/2018] [Indexed: 12/16/2022]
Abstract
The dopamine transporter (DAT) is abundantly expressed in the striatum where it removes extracellular dopamine into the cytosol of presynaptic nerve terminals. It is the target of drugs of abuse and antidepressants. There is a loss of the DAT in Parkinson's disease affecting release of levodopa implicated in levodopa-induced dyskinesias. This study investigated the effect of cholesterol on DAT, serotonin transporter (SERT) and vesicular monoamine transporter 2 (VMAT2) in monkey and rat brains in vitro. DAT protein levels measured by Western blot remained unchanged with in vitro methyl-β-cyclodextrin (MCD) incubations to remove membrane cholesterol or with incubations to increase membrane cholesterol content. By contrast, striatal DAT specific binding labelled with [125I]RTI-121 or with [125I]RTI-55 decreased with increasing concentrations of MCD and increased with cholesterol loading. Moreover, [125I]RTI-121 specific binding of striatal membranes depleted of cholesterol with MCD was restored to initial DAT content with addition of cholesterol showing its rapid and reversible effect. By contrast, striatal VMAT2 and SERT specific binding showed no or limited changes by cholesterol manipulations. Similar results were obtained for monkey caudate nucleus, putamen and nucleus accumbens. Membrane microviscosity was assessed by fluorescence polarization spectroscopy, using the probe 1,6-diphenyl-1,3,5-hexatriene. DAT changes positively correlated with changes of membrane microviscosity in rat and monkey brain regions investigated and with membrane cholesterol contents. Similar findings were observed with desmosterol but to a lower extent than with cholesterol. These results show an important effect of cholesterol on the DAT associated with microviscosity changes that should be considered in drug therapies.
Collapse
Affiliation(s)
- Marc Morissette
- Neuroscience Research Unit, Centre Hospitalier Universitaire de Québec, CHUL, Quebec City G1V 4G2, Canada
| | - Nicolas Morin
- Neuroscience Research Unit, Centre Hospitalier Universitaire de Québec, CHUL, Quebec City G1V 4G2, Canada; Faculty of Pharmacy, Université Laval, Quebec City G1K 7P4, Canada
| | - Claude Rouillard
- Neuroscience Research Unit, Centre Hospitalier Universitaire de Québec, CHUL, Quebec City G1V 4G2, Canada; Department of Psychiatry and Neuroscience, Faculty of Medicine, Université Laval, Quebec City G1K 7P4, Canada
| | - Thérèse Di Paolo
- Neuroscience Research Unit, Centre Hospitalier Universitaire de Québec, CHUL, Quebec City G1V 4G2, Canada; Faculty of Pharmacy, Université Laval, Quebec City G1K 7P4, Canada.
| |
Collapse
|
14
|
Garcia-Olivares J, Baust T, Harris S, Hamilton P, Galli A, Amara SG, Torres GE. Gβγ subunit activation promotes dopamine efflux through the dopamine transporter. Mol Psychiatry 2017; 22:1673-1679. [PMID: 28894302 PMCID: PMC5996372 DOI: 10.1038/mp.2017.176] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Revised: 07/05/2017] [Accepted: 07/28/2017] [Indexed: 01/30/2023]
Abstract
The dopamine transporter (DAT) is an important regulator of brain dopamine (DA) homeostasis, controlling the intensity and duration of DA signaling. DAT is the target for psychostimulants-like cocaine and amphetamine-and plays an important role in neuropsychiatric disorders, including attention-deficit hyperactivity disorder and drug addiction. Thus, a thorough understanding of the mechanisms that regulate DAT function is necessary for the development of clinical interventions to treat DA-related brain disorders. Previous studies have revealed a plethora of protein-protein interactions influencing DAT cellular localization and activity, suggesting that the fine-tuning of DA homeostasis involves multiple mechanisms. We recently reported that G-protein beta-gamma (Gβγ) subunits bind directly to DAT and decrease DA clearance. Here we show that Gβγ induces the release of DA through DAT. Specifically, a Gβγ-binding/activating peptide, mSIRK, increases DA efflux through DAT in heterologous cells and primary dopaminergic neurons in culture. Addition of the Gβγ inhibitor gallein or DAT inhibitors prevents this effect. Residues 582 to 596 in the DAT carboxy terminus were identified as the primary binding site of Gβγ. A TAT peptide containing the Gβγ-interacting domain of DAT blocked the ability of mSIRK to induce DA efflux, consistent with a direct interaction of Gβγ with the transporter. Finally, activation of a G-protein-coupled receptor, the muscarinic M5R, results in DAT-mediated DA efflux through a Gβγ-dependent mechanism. Collectively, our data show that Gβγ interacts with DAT to promote DA efflux. This novel mechanism may have important implications in the regulation of brain DA homeostasis.
Collapse
Affiliation(s)
- J Garcia-Olivares
- Laboratory of Cellular and Molecular Neurobiology, National Institute of Mental Health, Bethesda, MD, USA
| | - T Baust
- Department of Pharmacology and Therapeutics, University of Florida College of Medicine, Gainesville, FL, USA
| | - S Harris
- Department of Pharmacology and Therapeutics, University of Florida College of Medicine, Gainesville, FL, USA
| | - P Hamilton
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - A Galli
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - SG Amara
- Laboratory of Cellular and Molecular Neurobiology, National Institute of Mental Health, Bethesda, MD, USA
| | - GE Torres
- Department of Pharmacology and Therapeutics, University of Florida College of Medicine, Gainesville, FL, USA
| |
Collapse
|
15
|
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: 45] [Impact Index Per Article: 6.4] [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.
Collapse
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.
| |
Collapse
|
16
|
Garcia R, Cotter AR, Leslie K, Olive MF, Neisewander JL. Preclinical Evidence That 5-HT1B Receptor Agonists Show Promise as Medications for Psychostimulant Use Disorders. Int J Neuropsychopharmacol 2017; 20:644-653. [PMID: 28444326 PMCID: PMC5570061 DOI: 10.1093/ijnp/pyx025] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/13/2016] [Accepted: 04/18/2017] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND 5-HT1B receptor agonists enhance cocaine intake during daily self-administration sessions but decrease cocaine intake when tested after prolonged abstinence. We examined if 5-HT1B receptor agonists produce similar abstinence-dependent effects on methamphetamine intake. METHODS Male rats were trained to self-administer methamphetamine (0.1 mg/kg, i.v.) on low (fixed ratio 5 and variable ratio 5) and high (progressive ratio) effort schedules of reinforcement until intake was stable. Rats were then tested for the effects of the selective 5-HT1B receptor agonist, CP 94,253 (5.6 or 10 mg/kg), or the less selective but clinically available 5-HT1B/1D receptor agonist, zolmitriptan (10 mg/kg), on methamphetamine self-administration both before and after a 21-day forced abstinence period during which the rats remained in their home cages. RESULTS The inverted U-shaped, methamphetamine dose-response function for intake on the fixed ratio 5 schedule was shifted downward by CP 94,253 both before and after abstinence. The CP 94,253-induced decrease in methamphetamine intake was replicated in rats tested on a variable ratio 5 schedule, and the 5-HT1B receptor antagonist SB 224,289 (10 mg/kg) reversed this effect. CP 94,253 also attenuated methamphetamine intake on a progressive ratio schedule both pre- and postabstinence. Similarly, zolmitriptan attenuated methamphetamine intake on a variable ratio 5 schedule both pre- and postabstinence, and the latter effect was sustained after each of 2 more treatments given every 2 to 3 days prior to daily sessions. CONCLUSIONS Unlike the abstinence-dependent effect of 5-HT1B receptor agonists on cocaine intake reported previously, both CP 94,253 and zolmitriptan decreased methamphetamine intake regardless of abstinence. These findings suggest that 5-HT1B receptor agonists may have clinical efficacy for psychostimulant use disorders.
Collapse
Affiliation(s)
- Raul Garcia
- School of Life Sciences (Mr Garcia, Mr Cotter, Mr Leslie, and Dr Neisewander), and Psychology Department (Dr Olive), Arizona State University, Tempe, Arizona
| | - Austin R Cotter
- School of Life Sciences (Mr Garcia, Mr Cotter, Mr Leslie, and Dr Neisewander), and Psychology Department (Dr Olive), Arizona State University, Tempe, Arizona
| | - Kenneth Leslie
- School of Life Sciences (Mr Garcia, Mr Cotter, Mr Leslie, and Dr Neisewander), and Psychology Department (Dr Olive), Arizona State University, Tempe, Arizona
| | - M Foster Olive
- School of Life Sciences (Mr Garcia, Mr Cotter, Mr Leslie, and Dr Neisewander), and Psychology Department (Dr Olive), Arizona State University, Tempe, Arizona
| | - Janet L Neisewander
- School of Life Sciences (Mr Garcia, Mr Cotter, Mr Leslie, and Dr Neisewander), and Psychology Department (Dr Olive), Arizona State University, Tempe, Arizona
| |
Collapse
|
17
|
Budygin EA, Oleson EB, Lee YB, Blume LC, Bruno MJ, Howlett AC, Thompson AC, Bass CE. Acute Depletion of D2 Receptors from the Rat Substantia Nigra Alters Dopamine Kinetics in the Dorsal Striatum and Drug Responsivity. Front Behav Neurosci 2017; 10:248. [PMID: 28154530 PMCID: PMC5243821 DOI: 10.3389/fnbeh.2016.00248] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2016] [Accepted: 12/19/2016] [Indexed: 01/20/2023] Open
Abstract
Recent studies have used conditional knockout mice to selectively delete the D2 autoreceptor; however, these approaches result in global deletion of D2 autoreceptors early in development. The present study takes a different approach using RNA interference (RNAi) to knockdown the expression of the D2 receptors (D2R) in the substantia nigra (SN), including dopaminergic neurons, which project primarily to the dorsal striatum (dStr) in adult rats. This approach restricts the knockdown primarily to nigrostriatal pathways, leaving mesolimbic D2 autoreceptors intact. Analyses of dopamine (DA) kinetics in the dStr reveal a decrease in DA transporter (DAT) function in the knockdown rats, an effect not observed in D2 autoreceptor knockout mouse models. SN D2 knockdown rats exhibit a behavioral phenotype characterized by persistent enhancement of locomotor activity in a familiar open field, reduced locomotor responsiveness to high doses of cocaine and the ability to overcome haloperidol-induced immobility on the bar test. Together these results demonstrate that presynaptic D2R can be depleted from specific neuronal populations and implicates nigrostriatal D2R in different behavioral responses to psychotropic drugs.
Collapse
Affiliation(s)
- Evgeny A Budygin
- Department of Neurobiology and Anatomy, Wake Forest School of MedicineWinston Salem, NC, USA; Institute of Translational Biomedicine, St. Petersburg State UniversitySt. Petersburg, Russia
| | - Erik B Oleson
- Department of Physiology and Pharmacology, Wake Forest School of Medicine Winston Salem, NC, USA
| | - Yun Beom Lee
- Department of Pharmacology and Toxicology, School of Medicine and Biomedical Sciences, University at Buffalo Buffalo, NY, USA
| | - Lawrence C Blume
- Department of Physiology and Pharmacology, Wake Forest School of Medicine Winston Salem, NC, USA
| | - Michael J Bruno
- Department of Pharmacology and Toxicology, School of Medicine and Biomedical Sciences, University at Buffalo Buffalo, NY, USA
| | - Allyn C Howlett
- Department of Physiology and Pharmacology, Wake Forest School of Medicine Winston Salem, NC, USA
| | - Alexis C Thompson
- Research Institute on Addictions, University at Buffalo Buffalo, NY, USA
| | - Caroline E Bass
- Department of Pharmacology and Toxicology, School of Medicine and Biomedical Sciences, University at Buffalo Buffalo, NY, USA
| |
Collapse
|
18
|
Sequence determinants of the Caenhorhabditis elegans dopamine transporter dictating in vivo axonal export and synaptic localization. Mol Cell Neurosci 2016; 78:41-51. [PMID: 27913309 DOI: 10.1016/j.mcn.2016.11.011] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Revised: 11/25/2016] [Accepted: 11/28/2016] [Indexed: 02/06/2023] Open
Abstract
The monoamine neurotransmitter dopamine (DA) acts across phylogeny to modulate both simple and complex behaviors. The presynaptic DA transporter (DAT) is a major determinant of DA signaling capacity in ensuring efficient extracellular DA clearance. In humans, DAT is also a major target for prescribed and abused psychostimulants. Multiple structural determinants of DAT function and regulation have been defined, though largely these findings have arisen from heterologous expression or ex vivo cell culture studies. Loss of function mutations in the gene encoding the Caenhorhabditis elegans DAT (dat-1) produces rapid immobility when animals are placed in water, a phenotype termed swimming-induced paralysis (Swip). The ability of a DA neuron-expressed, GFP-tagged DAT-1 fusion protein (GFP::DAT-1) to localize to synapses and rescue Swip in these animals provides a facile approach to define sequences supporting DAT somatic export and function in vivo. In prior studies, we found that truncation of the last 25 amino acids of the DAT-1 C-terminus (Δ25) precludes Swip rescue, supported by a deficit in GFP::DAT-1 synaptic localization. Here, we further defined the elements within Δ25 required for DAT-1 export and function in vivo. We identified two conserved motifs (584KW585 and 591PYRKR595) where mutation results in a failure of GFP::DAT-1 to be efficiently exported to synapses and restore DAT-1 function. The 584KW585 motif conforms to a sequence proposed to support SEC24 binding, ER export from the endoplasmic reticulum (ER), and surface expression of mammalian DAT proteins, whereas the 591PYRKR595 sequence conforms to a 3R motif identified as a SEC24 binding site in vertebrate G-protein coupled receptors. Consistent with a potential role of SEC24 orthologs in DAT-1 export, we demonstrated DA neuron-specific expression of a sec-24.2 transcriptional reporter. Mutations of the orthologous C-terminal sequences in human DAT (hDAT) significantly reduced transporter surface expression and DA uptake, despite normal hDAT protein expression. Although, hDAT mutants retained SEC24 interactions, as defined in co-immunoprecipitation studies. However, these mutations disrupted the ability of SEC24D to enhance hDAT surface expression. Our studies document an essential role of conserved DAT C-terminal sequences in transporter somatic export and synaptic localization in vivo, that add further support for important roles for SEC24 family members in efficient transporter trafficking.
Collapse
|
19
|
Bermingham DP, Blakely RD. Kinase-dependent Regulation of Monoamine Neurotransmitter Transporters. Pharmacol Rev 2016; 68:888-953. [PMID: 27591044 PMCID: PMC5050440 DOI: 10.1124/pr.115.012260] [Citation(s) in RCA: 72] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Modulation of neurotransmission by the monoamines dopamine (DA), norepinephrine (NE), and serotonin (5-HT) is critical for normal nervous system function. Precise temporal and spatial control of this signaling in mediated in large part by the actions of monoamine transporters (DAT, NET, and SERT, respectively). These transporters act to recapture their respective neurotransmitters after release, and disruption of clearance and reuptake has significant effects on physiology and behavior and has been linked to a number of neuropsychiatric disorders. To ensure adequate and dynamic control of these transporters, multiple modes of control have evolved to regulate their activity and trafficking. Central to many of these modes of control are the actions of protein kinases, whose actions can be direct or indirectly mediated by kinase-modulated protein interactions. Here, we summarize the current state of our understanding of how protein kinases regulate monoamine transporters through changes in activity, trafficking, phosphorylation state, and interacting partners. We highlight genetic, biochemical, and pharmacological evidence for kinase-linked control of DAT, NET, and SERT and, where applicable, provide evidence for endogenous activators of these pathways. We hope our discussion can lead to a more nuanced and integrated understanding of how neurotransmitter transporters are controlled and may contribute to disorders that feature perturbed monoamine signaling, with an ultimate goal of developing better therapeutic strategies.
Collapse
Affiliation(s)
- Daniel P Bermingham
- Department of Pharmacology (D.P.B., R.D.B.) and Psychiatry (R.D.B.), Vanderbilt University Medical Center, Nashville, Tennessee; and Department of Biomedical Sciences, Charles E. Schmidt College of Medicine and Brain Institute, Florida Atlantic University, Jupiter, Florida (R.D.B.)
| | - Randy D Blakely
- Department of Pharmacology (D.P.B., R.D.B.) and Psychiatry (R.D.B.), Vanderbilt University Medical Center, Nashville, Tennessee; and Department of Biomedical Sciences, Charles E. Schmidt College of Medicine and Brain Institute, Florida Atlantic University, Jupiter, Florida (R.D.B.)
| |
Collapse
|
20
|
Jia X, Wang F, Han Y, Geng X, Li M, Shi Y, Lu L, Chen Y. miR-137 and miR-491 Negatively Regulate Dopamine Transporter Expression and Function in Neural Cells. Neurosci Bull 2016; 32:512-522. [PMID: 27628529 DOI: 10.1007/s12264-016-0061-6] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2016] [Accepted: 07/13/2016] [Indexed: 12/14/2022] Open
Abstract
The dopamine transporter (DAT) is involved in the regulation of extracellular dopamine levels. A 40-bp variable-number tandem repeat (VNTR) polymorphism in the 3'-untranslated region (3'UTR) of the DAT has been reported to be associated with various phenotypes that are involved in the aberrant regulation of dopaminergic neurotransmission. In the present study, we found that miR-137 and miR-491 caused a marked reduction of DAT expression, thereby influencing neuronal dopamine transport. Moreover, the regulation of miR-137 and miR-491 on this transport disappeared after the DAT was silenced. The miR-491 seed region that is located on the VNTR sequence in the 3'UTR of the DAT and the regulatory effect of miR-491 on the DAT depended on the VNTR copy-number. These data indicate that miR-137 and miR-491 regulate DAT expression and dopamine transport at the post-transcriptional level, suggesting that microRNA may be targeted for the treatment of diseases associated with DAT dysfunction.
Collapse
Affiliation(s)
- Xiaojian Jia
- Shenzhen Key Laboratory for Drug Addiction and Medication Safety, Department of Ultrasound, Peking University Shenzhen Hospital, Biomedical Research Institute, Shenzhen Peking University - The Hong Kong University of Science and Technology Medical Center, Shenzhen, 518036, China
| | - Feng Wang
- Shenzhen Key Laboratory for Drug Addiction and Medication Safety, Department of Ultrasound, Peking University Shenzhen Hospital, Biomedical Research Institute, Shenzhen Peking University - The Hong Kong University of Science and Technology Medical Center, Shenzhen, 518036, China.,Department of Physiology and Neurobiology, Xinxiang Medical University, Xinxiang, 453000, China
| | - Ying Han
- Institute of Mental Health, Peking University Sixth Hospital and Key Laboratory of Mental Health, National Institute on Drug Dependence, Peking University, Beijing, 100191, China
| | - Xuewen Geng
- Shenzhen Key Laboratory for Drug Addiction and Medication Safety, Department of Ultrasound, Peking University Shenzhen Hospital, Biomedical Research Institute, Shenzhen Peking University - The Hong Kong University of Science and Technology Medical Center, Shenzhen, 518036, China
| | - Minghua Li
- Shenzhen Key Laboratory for Drug Addiction and Medication Safety, Department of Ultrasound, Peking University Shenzhen Hospital, Biomedical Research Institute, Shenzhen Peking University - The Hong Kong University of Science and Technology Medical Center, Shenzhen, 518036, China
| | - Yu Shi
- Shenzhen Key Laboratory for Drug Addiction and Medication Safety, Department of Ultrasound, Peking University Shenzhen Hospital, Biomedical Research Institute, Shenzhen Peking University - The Hong Kong University of Science and Technology Medical Center, Shenzhen, 518036, China
| | - Lin Lu
- Institute of Mental Health, Peking University Sixth Hospital and Key Laboratory of Mental Health, National Institute on Drug Dependence, Peking University, Beijing, 100191, China.
| | - Yun Chen
- Shenzhen Key Laboratory for Drug Addiction and Medication Safety, Department of Ultrasound, Peking University Shenzhen Hospital, Biomedical Research Institute, Shenzhen Peking University - The Hong Kong University of Science and Technology Medical Center, Shenzhen, 518036, China.
| |
Collapse
|
21
|
Parra LA, Baust TB, Smith AD, Jaumotte JD, Zigmond MJ, Torres S, Leak RK, Pino JA, Torres GE. The Molecular Chaperone Hsc70 Interacts with Tyrosine Hydroxylase to Regulate Enzyme Activity and Synaptic Vesicle Localization. J Biol Chem 2016; 291:17510-22. [PMID: 27365397 DOI: 10.1074/jbc.m116.728782] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Indexed: 12/25/2022] Open
Abstract
We previously reported that the vesicular monoamine transporter 2 (VMAT2) is physically and functionally coupled with Hsc70 as well as with the dopamine synthesis enzymes tyrosine hydroxylase (TH) and aromatic amino acid decarboxylase, providing a novel mechanism for dopamine homeostasis regulation. Here we expand those findings to demonstrate that Hsc70 physically and functionally interacts with TH to regulate the enzyme activity and synaptic vesicle targeting. Co-immunoprecipitation assays performed in brain tissue and heterologous cells demonstrated that Hsc70 interacts with TH and aromatic amino acid decarboxylase. Furthermore, in vitro binding assays showed that TH directly binds the substrate binding and carboxyl-terminal domains of Hsc70. Immunocytochemical studies indicated that Hsc70 and TH co-localize in midbrain dopaminergic neurons. The functional significance of the Hsc70-TH interaction was then investigated using TH activity assays. In both dopaminergic MN9D cells and mouse brain synaptic vesicles, purified Hsc70 facilitated an increase in TH activity. Neither the closely related protein Hsp70 nor the unrelated Hsp60 altered TH activity, confirming the specificity of the Hsc70 effect. Overexpression of Hsc70 in dopaminergic MN9D cells consistently resulted in increased TH activity whereas knockdown of Hsc70 by short hairpin RNA resulted in decreased TH activity and dopamine levels. Finally, in cells with reduced levels of Hsc70, the amount of TH associated with synaptic vesicles was decreased. This effect was rescued by addition of purified Hsc70. Together, these data demonstrate a novel interaction between Hsc70 and TH that regulates the activity and localization of the enzyme to synaptic vesicles, suggesting an important role for Hsc70 in dopamine homeostasis.
Collapse
Affiliation(s)
| | | | - Amanda D Smith
- Neurology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261
| | - Juliann D Jaumotte
- Neurology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261
| | - Michael J Zigmond
- Neurology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261
| | - Soledad Torres
- the Centro de Investigación y Modelamiento de Fenómenos Aleatorios Valparaíso, Faculty of Engineering, Universidad de Valparaíso, 2362905 Valparaíso, Chile
| | - Rehana K Leak
- the Division of Pharmaceutical Sciences, Duquesne University, Pittsburgh, Pennsylvania 15282, and
| | - Jose A Pino
- the Department of Pharmacology and Therapeutics, University of Florida College of Medicine, Gainesville, Florida 32610
| | - Gonzalo E Torres
- the Department of Pharmacology and Therapeutics, University of Florida College of Medicine, Gainesville, Florida 32610
| |
Collapse
|
22
|
Fricks-Gleason AN, German CL, Hoonakker AJ, Friend DM, Ganesh KK, Carver AS, Hanson GR, Fleckenstein AE, Keefe KA. An acute, epitope-specific modification in the dopamine transporter associated with methamphetamine-induced neurotoxicity. Synapse 2016; 70:139-46. [PMID: 26799527 DOI: 10.1002/syn.21891] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2015] [Revised: 12/08/2015] [Accepted: 01/18/2016] [Indexed: 11/12/2022]
Abstract
Preclinical studies demonstrate that repeated, high-dose methamphetamine administrations rapidly decrease plasmalemmal dopamine uptake, which may contribute to aberrant dopamine accumulation, reactive species generation, and long-term dopaminergic deficits. The present study extends these findings by demonstrating a heretofore unreported, epitope-specific modification in the dopamine transporter caused by a methamphetamine regimen that induces these deficits. Specifically, repeated, high-dose methamphetamine injections (4 × 10 mg/kg/injection, 2-h intervals) rapidly decreased immunohistochemical detection of striatal dopamine transporter as assessed 1 h after the final methamphetamine exposure. In contrast, neither a single high dose (1 × 10 mg/kg) nor repeated injections of a lower dose (4 × 2 mg/kg/injection) induced this change. The high-dose regimen-induced alteration was only detected using antibodies directed against the N-terminus. Immunohistochemical staining using antibodies directed against the C-terminus did not reveal any changes. The high-dose regimen also did not alter dopamine transporter expression as assessed using [(125) I]RTI-55 autoradiography. These data suggest that the repeated, high-dose methamphetamine regimen alters the N-terminus of the dopamine transporter. Further, these data may be predictive of persistent dopamine deficits caused by the stimulant. Future studies of the signaling cascades involved should provide novel insight into potential mechanisms underlying the physiological and pathophysiological regulation of the dopamine transporter.
Collapse
Affiliation(s)
| | | | | | - Danielle M Friend
- Eating and Addiction Section, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, Maryland, 20892.,Interdepartmental Program in Neuroscience, University of Utah, Salt Lake City, Utah, 84112
| | - Kamala K Ganesh
- Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, Utah, 84112
| | - Aaron S Carver
- Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, Utah, 84112
| | - Glen R Hanson
- School of Dentistry, University of Utah, Salt Lake City, Utah, 84108.,Interdepartmental Program in Neuroscience, University of Utah, Salt Lake City, Utah, 84112
| | - Annette E Fleckenstein
- School of Dentistry, University of Utah, Salt Lake City, Utah, 84108.,Interdepartmental Program in Neuroscience, University of Utah, Salt Lake City, Utah, 84112
| | - Kristen A Keefe
- Interdepartmental Program in Neuroscience, University of Utah, Salt Lake City, Utah, 84112.,Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, Utah, 84112
| |
Collapse
|
23
|
Ye R, Quinlan MA, Iwamoto H, Wu HH, Green NH, Jetter CS, McMahon DG, Veestra-VanderWeele J, Levitt P, Blakely RD. Physical Interactions and Functional Relationships of Neuroligin 2 and Midbrain Serotonin Transporters. Front Synaptic Neurosci 2016; 7:20. [PMID: 26793096 PMCID: PMC4707279 DOI: 10.3389/fnsyn.2015.00020] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2015] [Accepted: 12/14/2015] [Indexed: 12/31/2022] Open
Abstract
The neurotransmitter serotonin [5-hydroxytryptamine (5-HT)] modulates many key brain functions including those subserving sensation, emotion, reward, and cognition. Efficient clearance of 5-HT after release is achieved by the antidepressant-sensitive 5-HT transporter (SERT, SLC6A4). To identify novel SERT regulators, we pursued a proteomic analysis of mouse midbrain SERT complexes, evaluating findings in the context of prior studies that established a SERT-linked transcriptome. Remarkably, both efforts converged on a relationship of SERT with the synaptic adhesion protein neuroligin 2 (NLGN2), a post-synaptic partner for presynaptic neurexins, and a protein well-known to organize inhibitory GABAergic synapses. Western blots of midbrain reciprocal immunoprecipitations confirmed SERT/NLGN2 associations, and also extended to other NLGN2 associated proteins [e.g., α-neurexin (NRXN), gephyrin]. Midbrain SERT/NLGN2 interactions were found to be Ca(2+)-independent, supporting cis vs. trans-synaptic interactions, and were absent in hippocampal preparations, consistent with interactions arising in somatodendritic compartments. Dual color in situ hybridization confirmed co-expression of Tph2 and Nlgn2 mRNA in the dorsal raphe, with immunocytochemical studies confirming SERT:NLGN2 co-localization in raphe cell bodies but not axons. Consistent with correlative mRNA expression studies, loss of NLGN2 expression in Nlgn2 null mice produced significant reductions in midbrain and hippocampal SERT expression and function. Additionally, dorsal raphe 5-HT neurons from Nlgn2 null mice exhibit reduced excitability, a loss of GABAA receptor-mediated IPSCs, and increased 5-HT1A autoreceptor sensitivity. Finally, Nlgn2 null mice display significant changes in behaviors known to be responsive to SERT and/or 5-HT receptor manipulations. We discuss our findings in relation to the possible coordination of intrinsic and extrinsic regulation afforded by somatodendritic SERT:NLGN2 complexes.
Collapse
Affiliation(s)
- Ran Ye
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville TN, USA
| | - Meagan A Quinlan
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville TN, USA
| | - Hideki Iwamoto
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville TN, USA
| | - Hsiao-Huei Wu
- Department of Psychiatry, Vanderbilt University School of Medicine, Nashville TN, USA
| | - Noah H Green
- Department of Biological Sciences, Vanderbilt University School of Medicine, Nashville TN, USA
| | - Christopher S Jetter
- Department of Psychiatry, Vanderbilt University School of Medicine, Nashville TN, USA
| | - Douglas G McMahon
- Department of Pharmacology, Vanderbilt University School of Medicine, NashvilleTN, USA; Department of Biological Sciences, Vanderbilt University School of Medicine, NashvilleTN, USA
| | - Jeremy Veestra-VanderWeele
- Department of Psychiatry, NYS Psychiatric Institute, Columbia University Medical Center, New York NY, USA
| | - Pat Levitt
- Department of Psychiatry, Vanderbilt University School of Medicine, Nashville TN, USA
| | - Randy D Blakely
- Department of Pharmacology, Vanderbilt University School of Medicine, NashvilleTN, USA; Department of Psychiatry, Vanderbilt University School of Medicine, NashvilleTN, USA
| |
Collapse
|
24
|
Hussain SA, Sulaiman AA, Alhaddad H, Alhadidi Q. Natural polyphenols: Influence on membrane transporters. JOURNAL OF COMPLEMENTARY MEDICINE RESEARCH 2016; 5:97-104. [PMID: 27069731 PMCID: PMC4805155 DOI: 10.5455/jice.20160118062127] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2015] [Accepted: 01/18/2016] [Indexed: 02/02/2023]
Abstract
Accumulated evidence has focused on the use of natural polyphenolic compounds as nutraceuticals since they showed a wide range of bioactivities and exhibited protection against variety of age-related disorders. Polyphenols have variable potencies to interact, and hence alter the activities of various transporter proteins, many of them classified as anion transporting polypeptide-binding cassette transporters like multidrug resistance protein and p-glycoprotein. Some of the efflux transporters are, generally, linked with anticancer and antiviral drug resistance; in this context, polyphenols may be beneficial in modulating drug resistance by increasing the efficacy of anticancer and antiviral drugs. In addition, these effects were implicated to explain the influence of dietary polyphenols on drug efficacy as result of food-drug interactions. However, limited data are available about the influence of these components on uptake transporters. Therefore, the objective of this article is to review the potential efficacies of polyphenols in modulating the functional integrity of uptake transporter proteins, including those terminated the effect of neurotransmitters, and their possible influence in neuropharmacology.
Collapse
Affiliation(s)
- Saad Abdulrahman Hussain
- Department of Pharmacology and Toxicology, College of Pharmacy, University of Baghdad, Baghdad, Iraq
| | - Amal Ajaweed Sulaiman
- Department of Pharmacology and Toxicology, College of Pharmacy, University of Baghdad, Baghdad, Iraq
| | - Hasan Alhaddad
- Department of Pharmacology and Toxicology, College of Pharmacy, University of Baghdad, Baghdad, Iraq
| | - Qasim Alhadidi
- Department of Medicinal and Biological Chemistry, College of Pharmacy and Pharmaceutical Sciences, University of Toledo, 3000 Arlington Avenue, Toledo, OH, 43614, USA
| |
Collapse
|
25
|
Shih AM, Varghese L, Bittar A, Park SH, Chung JM, Shin OH. Dysregulation of Norepinephrine Release in the Absence of Functional Synaptotagmin 7. J Cell Biochem 2015; 117:1446-53. [PMID: 27043247 DOI: 10.1002/jcb.25436] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2015] [Accepted: 11/10/2015] [Indexed: 01/28/2023]
Abstract
Synaptotagmin 7 (Syt7) is expressed in cardiac sympathetic nerve terminals where norepinephrine (NE) is released in both Ca(2+)-dependent exocytosis and Ca(2+)-independent norepinephrine transporter (NET)-mediated overflow. The role of Syt7 in the regulation of NE release from cardiac sympathetic nerve terminals is tested by employing a Syt7 knock-in mouse line that expresses a non-functional mutant form of Syt7. In cardiac sympathetic nerve terminals prepared from these Syt7 knock-in mice, the Ca(2+)-dependent component of NE release was diminished. However, these terminals displayed upregulated function of NET (∼130% of controls) and a significant increase in Ca(2+)-independent NE overflow (∼140% of controls), which is greater than the Ca(2+)-dependent component of NE exocytosis occurring in wild-type controls. Consistent with a significant increase in NE overflow, the Syt7 knock-in mice showed significantly higher blood pressures compared to those of littermate wild-type and heterozygous mice. Our results indicate that the lack of functional Syt7 dysregulates NE release from cardiac sympathetic nerve terminals.
Collapse
Affiliation(s)
- Alvin M Shih
- Department of Neuroscience and Cell Biology, University of Texas Medical Branch, Galveston, Texas, 77555
| | - Lincy Varghese
- Department of Neuroscience and Cell Biology, University of Texas Medical Branch, Galveston, Texas, 77555
| | - Alice Bittar
- Department of Neuroscience and Cell Biology, University of Texas Medical Branch, Galveston, Texas, 77555
| | - Sung-Hoon Park
- Department of Neuroscience and Cell Biology, University of Texas Medical Branch, Galveston, Texas, 77555
| | - Jin Mo Chung
- Department of Neuroscience and Cell Biology, University of Texas Medical Branch, Galveston, Texas, 77555
| | - Ok-Ho Shin
- Department of Neuroscience and Cell Biology, University of Texas Medical Branch, Galveston, Texas, 77555
| |
Collapse
|
26
|
Butler B, Saha K, Rana T, Becker JP, Sambo D, Davari P, Goodwin JS, Khoshbouei H. Dopamine Transporter Activity Is Modulated by α-Synuclein. J Biol Chem 2015; 290:29542-54. [PMID: 26442590 DOI: 10.1074/jbc.m115.691592] [Citation(s) in RCA: 74] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2015] [Indexed: 12/24/2022] Open
Abstract
The duration and strength of the dopaminergic signal are regulated by the dopamine transporter (DAT). Drug addiction and neurodegenerative and neuropsychiatric diseases have all been associated with altered DAT activity. The membrane localization and the activity of DAT are regulated by a number of intracellular proteins. α-Synuclein, a protein partner of DAT, is implicated in neurodegenerative disease and drug addiction. Little is known about the regulatory mechanisms of the interaction between DAT and α-synuclein, the cellular location of this interaction, and the functional consequences of this interaction on the basal, amphetamine-induced DAT-mediated dopamine efflux, and membrane microdomain distribution of the transporter. Here, we found that the majority of DAT·α-synuclein protein complexes are found at the plasma membrane of dopaminergic neurons or mammalian cells and that the amphetamine-mediated increase in DAT activity enhances the association of these proteins at the plasma membrane. Further examination of the interaction of DAT and α-synuclein revealed a transient interaction between these two proteins at the plasma membrane. Additionally, we found DAT-induced membrane depolarization enhances plasma membrane localization of α-synuclein, which in turn increases dopamine efflux and enhances DAT localization in cholesterol-rich membrane microdomains.
Collapse
Affiliation(s)
- Brittany Butler
- From the Departments of Neuroscience and Psychiatry University of Florida, Gainesville, Florida 32611 and
| | - Kaustuv Saha
- From the Departments of Neuroscience and Psychiatry University of Florida, Gainesville, Florida 32611 and
| | - Tanu Rana
- the Department of Biochemistry and Cancer Biology, Meharry Medical College, Nashville, Tennessee 37208
| | - Jonas P Becker
- From the Departments of Neuroscience and Psychiatry University of Florida, Gainesville, Florida 32611 and
| | - Danielle Sambo
- From the Departments of Neuroscience and Psychiatry University of Florida, Gainesville, Florida 32611 and
| | - Paran Davari
- From the Departments of Neuroscience and Psychiatry University of Florida, Gainesville, Florida 32611 and
| | - J Shawn Goodwin
- the Department of Biochemistry and Cancer Biology, Meharry Medical College, Nashville, Tennessee 37208
| | - Habibeh Khoshbouei
- From the Departments of Neuroscience and Psychiatry University of Florida, Gainesville, Florida 32611 and
| |
Collapse
|
27
|
Rahbek-Clemmensen T, Bay T, Eriksen J, Gether U, Jørgensen TN. The serotonin transporter undergoes constitutive internalization and is primarily sorted to late endosomes and lysosomal degradation. J Biol Chem 2014; 289:23004-23019. [PMID: 24973209 DOI: 10.1074/jbc.m113.495754] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The serotonin transporter (SERT) plays a critical role in regulating serotonin signaling by mediating reuptake of serotonin from the extracellular space. The molecular and cellular mechanisms controlling SERT levels in the membrane remain poorly understood. To study trafficking of the surface resident SERT, two functional epitope-tagged variants were generated. Fusion of a FLAG-tagged one-transmembrane segment protein Tac to the SERT N terminus generated a transporter with an extracellular epitope suited for trafficking studies (TacSERT). Likewise, a construct with an extracellular antibody epitope was generated by introducing an HA (hemagglutinin) tag in the extracellular loop 2 of SERT (HA-SERT). By using TacSERT and HA-SERT in antibody-based internalization assays, we show that SERT undergoes constitutive internalization in a dynamin-dependent manner. Confocal images of constitutively internalized SERT demonstrated that SERT primarily co-localized with the late endosomal/lysosomal marker Rab7, whereas little co-localization was observed with the Rab11, a marker of the "long loop" recycling pathway. This sorting pattern was distinct from that of a prototypical recycling membrane protein, the β2-adrenergic receptor. Furthermore, internalized SERT co-localized with the lysosomal marker LysoTracker and not with transferrin. The sorting pattern was further confirmed by visualizing internalization of SERT using the fluorescent cocaine analog JHC1-64 and by reversible and pulse-chase biotinylation assays showing evidence for lysosomal degradation of the internalized transporter. Finally, we found that SERT internalized in response to stimulation with 12-myristate 13-acetate co-localized primarily with Rab7- and LysoTracker-positive compartments. We conclude that SERT is constitutively internalized and that the internalized transporter is sorted mainly to degradation.
Collapse
Affiliation(s)
- Troels Rahbek-Clemmensen
- Molecular Neuropharmacology Laboratory, Department of Neuroscience and Pharmacology, Faculty of Health Sciences, Panum Institute, and University of Copenhagen, DK-2200 Copenhagen, Denmark; Lundbeck Foundation Center for Biomembranes in Nanomedicine, University of Copenhagen, DK-2200 Copenhagen, Denmark
| | - Tina Bay
- Molecular Neuropharmacology Laboratory, Department of Neuroscience and Pharmacology, Faculty of Health Sciences, Panum Institute, and University of Copenhagen, DK-2200 Copenhagen, Denmark
| | - Jacob Eriksen
- Molecular Neuropharmacology Laboratory, Department of Neuroscience and Pharmacology, Faculty of Health Sciences, Panum Institute, and University of Copenhagen, DK-2200 Copenhagen, Denmark; Lundbeck Foundation Center for Biomembranes in Nanomedicine, University of Copenhagen, DK-2200 Copenhagen, Denmark
| | - Ulrik Gether
- Molecular Neuropharmacology Laboratory, Department of Neuroscience and Pharmacology, Faculty of Health Sciences, Panum Institute, and University of Copenhagen, DK-2200 Copenhagen, Denmark; Lundbeck Foundation Center for Biomembranes in Nanomedicine, University of Copenhagen, DK-2200 Copenhagen, Denmark.
| | - Trine Nygaard Jørgensen
- Molecular Neuropharmacology Laboratory, Department of Neuroscience and Pharmacology, Faculty of Health Sciences, Panum Institute, and University of Copenhagen, DK-2200 Copenhagen, Denmark
| |
Collapse
|
28
|
Drosophila melanogaster as a genetic model system to study neurotransmitter transporters. Neurochem Int 2014; 73:71-88. [PMID: 24704795 DOI: 10.1016/j.neuint.2014.03.015] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2013] [Revised: 03/20/2014] [Accepted: 03/24/2014] [Indexed: 12/30/2022]
Abstract
The model genetic organism Drosophila melanogaster, commonly known as the fruit fly, uses many of the same neurotransmitters as mammals and very similar mechanisms of neurotransmitter storage, release and recycling. This system offers a variety of powerful molecular-genetic methods for the study of transporters, many of which would be difficult in mammalian models. We review here progress made using Drosophila to understand the function and regulation of neurotransmitter transporters and discuss future directions for its use.
Collapse
|
29
|
Arapulisamy O, Mannangatti P, Jayanthi LD. Regulated norepinephrine transporter interaction with the neurokinin-1 receptor establishes transporter subcellular localization. J Biol Chem 2013; 288:28599-610. [PMID: 23979140 DOI: 10.1074/jbc.m113.472878] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Neurokinin-1 receptor (NK1R) mediates down-regulation of human norepinephrine (NE) transporter (hNET) via protein kinase C (PKC). However, native NET regulation by NK1R and the mechanism by which NK1R targets NET among other potential effectors are unknown. Effect of NK1R activation on native NET regulation and NET/NK1R interaction were studied using rat brain synaptosomes expressing native NET and NK1R as well as human placental trophoblast (HTR) cells coexpressing WT-hNET or NK1R/PKC-resistant hNET-T258A,S259A double mutant (NET-DM) and hNK1R. The selective NK1R agonist, GR73632, and Substance-P (SP) inhibited NE transport and reduced plasma membrane expression of NET and NK1R. Pretreatment with the NK1R antagonist, EMEND (aprepitant) prevented these NK1R-mediated effects. Immunoprecipitation experiments showed that NET forms stable complexes with NK1R. In HTR cells, combined biotinylation and immunoprecipitation studies revealed plasma membrane localization of NET·NK1R complexes. Receptor activation resulted in the internalization of NET·NK1R complexes. Lipid raft and immunoprecipitation analyses revealed the presence of NET·NK1R complexes exclusively in non-raft membrane fractions under basal/unstimulated conditions. However, NK1R activation led to translocation of NET·NK1R complexes to raft-rich membrane fractions. Importantly, PKCα was found in association with raft-localized NET following SP treatment. Similar to WT-NET, PKC-resistant NET-DM was found in association with NK1R exclusively in non-raft fractions. However, SP treatment failed to translocate NET-DM·NK1R complexes from non-raft fractions to raft fractions. Collectively, these results suggest that NK1R forms physical complexes with NET and that the receptor-mediated Thr(258) + Ser(259) motif-dependent translocation of NET·NK1R complexes into raft-rich microdomains facilitates NET/NK1R interaction with PKCα to coordinate spatially restricted NET regulation.
Collapse
Affiliation(s)
- Obulakshmi Arapulisamy
- From the Department of Neurosciences, Division of Neuroscience Research, Medical University of South Carolina, Charleston, South Carolina 29425 and
| | | | | |
Collapse
|
30
|
Rickhag M, Owens WA, Winkler MT, Strandfelt KN, Rathje M, Sørensen G, Andresen B, Madsen KL, Jørgensen TN, Wörtwein G, Woldbye DPD, Sitte H, Daws LC, Gether U. Membrane-permeable C-terminal dopamine transporter peptides attenuate amphetamine-evoked dopamine release. J Biol Chem 2013; 288:27534-27544. [PMID: 23884410 DOI: 10.1074/jbc.m112.441295] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The dopamine transporter (DAT) is responsible for sequestration of extracellular dopamine (DA). The psychostimulant amphetamine (AMPH) is a DAT substrate, which is actively transported into the nerve terminal, eliciting vesicular depletion and reversal of DA transport via DAT. Here, we investigate the role of the DAT C terminus in AMPH-evoked DA efflux using cell-permeant dominant-negative peptides. A peptide, which corresponded to the last 24 C-terminal residues of DAT (TAT-C24 DAT) and thereby contained the Ca(2+)-calmodulin-dependent protein kinase IIα (CaMKIIα) binding domain and the PSD-95/Discs-large/ZO-1 (PDZ)-binding sequence of DAT, was made membrane-permeable by fusing it to the cell membrane transduction domain of the HIV-1 Tat protein (TAT-C24WT). The ability of TAT-C24WT but not a scrambled peptide (TAT-C24Scr) to block the CaMKIIα-DAT interaction was supported by co-immunoprecipitation experiments in heterologous cells. In heterologous cells, we also found that TAT-C24WT, but not TAT-C24Scr, decreased AMPH-evoked 1-methyl-4-phenylpyridinium efflux. Moreover, chronoamperometric recordings in striatum revealed diminished AMPH-evoked DA efflux in mice preinjected with TAT-C24WT. Both in heterologous cells and in striatum, the peptide did not further inhibit efflux upon KN-93-mediated inhibition of CaMKIIα activity, consistent with a dominant-negative action preventing binding of CaMKIIα to the DAT C terminus. This was further supported by the ability of a peptide with perturbed PDZ-binding sequence, but preserved CaMKIIα binding (TAT-C24AAA), to diminish AMPH-evoked DA efflux in vivo to the same extent as TAT-C24WT. Finally, AMPH-induced locomotor hyperactivity was attenuated following systemic administration of TAT-C24WT but not TAT-C24Scr. Summarized, our findings substantiate that DAT C-terminal protein-protein interactions are critical for AMPH-evoked DA efflux and suggest that it may be possible to target protein-protein interactions to modulate transporter function and interfere with psychostimulant effects.
Collapse
Affiliation(s)
- Mattias Rickhag
- Molecular Neuropharmacology Laboratory, Lundbeck Foundation Center for Biomembranes in Nanomedicine, Department of Neuroscience and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, DK-2200 Copenhagen, Denmark
| | - William A Owens
- Department of Physiology, University of Texas Health Science Center at San Antonio, San Antonio, Texas 78229
| | - Marie-Therese Winkler
- Institute of Pharmacology, Center for Physiology and Pharmacology, Medical University Vienna, A-1090 Vienna, Austria
| | - Kristine Nørgaard Strandfelt
- Molecular Neuropharmacology Laboratory, Lundbeck Foundation Center for Biomembranes in Nanomedicine, Department of Neuroscience and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, DK-2200 Copenhagen, Denmark
| | - Mette Rathje
- Molecular Neuropharmacology Laboratory, Lundbeck Foundation Center for Biomembranes in Nanomedicine, Department of Neuroscience and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, DK-2200 Copenhagen, Denmark
| | - Gunnar Sørensen
- Molecular Neuropharmacology Laboratory, Lundbeck Foundation Center for Biomembranes in Nanomedicine, Department of Neuroscience and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, DK-2200 Copenhagen, Denmark; Laboratory of Neuropsychiatry, Faculty of Health and Medical Sciences, Department of Neuroscience and Pharmacology, University of Copenhagen, DK-2200 Copenhagen, Denmark
| | - Bjørn Andresen
- Molecular Neuropharmacology Laboratory, Lundbeck Foundation Center for Biomembranes in Nanomedicine, Department of Neuroscience and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, DK-2200 Copenhagen, Denmark
| | - Kenneth L Madsen
- Molecular Neuropharmacology Laboratory, Lundbeck Foundation Center for Biomembranes in Nanomedicine, Department of Neuroscience and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, DK-2200 Copenhagen, Denmark
| | - Trine Nygaard Jørgensen
- Molecular Neuropharmacology Laboratory, Lundbeck Foundation Center for Biomembranes in Nanomedicine, Department of Neuroscience and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, DK-2200 Copenhagen, Denmark
| | - Gitta Wörtwein
- Laboratory of Neuropsychiatry, Faculty of Health and Medical Sciences, Department of Neuroscience and Pharmacology, University of Copenhagen, DK-2200 Copenhagen, Denmark
| | - David P D Woldbye
- Laboratory of Neuropsychiatry, Faculty of Health and Medical Sciences, Department of Neuroscience and Pharmacology, University of Copenhagen, DK-2200 Copenhagen, Denmark
| | - Harald Sitte
- Institute of Pharmacology, Center for Physiology and Pharmacology, Medical University Vienna, A-1090 Vienna, Austria
| | - Lynette C Daws
- Department of Physiology, University of Texas Health Science Center at San Antonio, San Antonio, Texas 78229
| | - Ulrik Gether
- Molecular Neuropharmacology Laboratory, Lundbeck Foundation Center for Biomembranes in Nanomedicine, Department of Neuroscience and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, DK-2200 Copenhagen, Denmark.
| |
Collapse
|
31
|
Garcia-Olivares J, Torres-Salazar D, Owens WA, Baust T, Siderovski DP, Amara SG, Zhu J, Daws LC, Torres GE. Inhibition of dopamine transporter activity by G protein βγ subunits. PLoS One 2013; 8:e59788. [PMID: 23555781 PMCID: PMC3608556 DOI: 10.1371/journal.pone.0059788] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2012] [Accepted: 02/18/2013] [Indexed: 12/15/2022] Open
Abstract
Uptake through the Dopamine Transporter (DAT) is the primary mechanism of terminating dopamine signaling within the brain, thus playing an essential role in neuronal homeostasis. Deregulation of DAT function has been linked to several neurological and psychiatric disorders including ADHD, schizophrenia, Parkinson’s disease, and drug addiction. Over the last 15 years, several studies have revealed a plethora of mechanisms influencing the activity and cellular distribution of DAT; suggesting that fine-tuning of dopamine homeostasis occurs via an elaborate interplay of multiple pathways. Here, we show for the first time that the βγ subunits of G proteins regulate DAT activity. In heterologous cells and brain tissue, a physical association between Gβγ subunits and DAT was demonstrated by co-immunoprecipitation. Furthermore, in vitro pull-down assays using purified proteins established that this association occurs via a direct interaction between the intracellular carboxy-terminus of DAT and Gβγ. Functional assays performed in the presence of the non-hydrolyzable GTP analog GTP-γ-S, Gβγ subunit overexpression, or the Gβγ activator mSIRK all resulted in rapid inhibition of DAT activity in heterologous systems. Gβγ activation by mSIRK also inhibited dopamine uptake in brain synaptosomes and dopamine clearance from mouse striatum as measured by high-speed chronoamperometry in vivo. Gβγ subunits are intracellular signaling molecules that regulate a multitude of physiological processes through interactions with enzymes and ion channels. Our findings add neurotransmitter transporters to the growing list of molecules regulated by G-proteins and suggest a novel role for Gβγ signaling in the control of dopamine homeostasis.
Collapse
Affiliation(s)
- Jennie Garcia-Olivares
- Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
| | - Delany Torres-Salazar
- Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
| | - William A. Owens
- Department of Physiology, University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America
| | - Tracy Baust
- Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
| | - David P. Siderovski
- Department of Pharmacology and UNC Neuroscience Center, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Susan G. Amara
- Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
| | - Jun Zhu
- Department of Pharmaceutical and Biomedical Sciences, South Carolina College of Pharmacy, University of South Carolina, Columbia, South Carolina, United States of America
| | - Lynette C. Daws
- Department of Physiology, University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America
| | - Gonzalo E. Torres
- Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
- * E-mail:
| |
Collapse
|
32
|
Raffel DM, Chen W, Jung YW, Jang KS, Gu G, Cozzi NV. Radiotracers for cardiac sympathetic innervation: transport kinetics and binding affinities for the human norepinephrine transporter. Nucl Med Biol 2013; 40:331-7. [PMID: 23306137 DOI: 10.1016/j.nucmedbio.2012.11.014] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2012] [Revised: 11/16/2012] [Accepted: 11/28/2012] [Indexed: 02/07/2023]
Abstract
INTRODUCTION Most radiotracers for imaging of cardiac sympathetic innervation are substrates of the norepinephrine transporter (NET). The goal of this study was to characterize the NET transport kinetics and binding affinities of several sympathetic nerve radiotracers, including [(11)C]-(-)-meta-hydroxyephedrine, [(11)C]-(-)-epinephrine, and a series of [(11)C]-labeled phenethylguanidines under development in our laboratory. For comparison, the NET transport kinetics and binding affinities of some [(3)H]-labeled biogenic amines were also determined. METHODS Transport kinetics studies were performed using rat C6 glioma cells stably transfected with the human norepinephrine transporter (C6-hNET cells). For each radiolabeled NET substrate, saturation transport assays with C6-hNET cells measured the Michaelis-Menten transport constants Km and Vmax for NET transport. Competitive inhibition binding assays with homogenized C6-hNET cells and [(3)H]mazindol provided estimates of binding affinities (KI) for NET. RESULTS Km, Vmax and KI values were determined for each NET substrate with a high degree of reproducibility. Interestingly, C6-hNET transport rates for 'tracer concentrations' of substrate, given by the ratio Vmax/Km, were found to be highly correlated with neuronal transport rates measured previously in isolated rat hearts (r(2)=0.96). This suggests that the transport constants Km and Vmax measured using the C6-hNET cells accurately reflect in vivo transport kinetics. CONCLUSION The results of these studies show how structural changes in NET substrates influence NET binding and transport constants, providing valuable insights that can be used in the design of new tracers with more optimal kinetics for quantifying regional sympathetic nerve density.
Collapse
Affiliation(s)
- David M Raffel
- Division of Nuclear Medicine, Department of Radiology, 2276 Medical Sciences I Building, University of Michigan Medical School, 1301 Catherine Street, SPC 5610, Ann Arbor, MI 48109, USA.
| | | | | | | | | | | |
Collapse
|
33
|
Sucic S, Koban F, El-Kasaby A, Kudlacek O, Stockner T, Sitte HH, Freissmuth M. Switching the clientele: a lysine residing in the C terminus of the serotonin transporter specifies its preference for the coat protein complex II component SEC24C. J Biol Chem 2013; 288:5330-41. [PMID: 23288844 PMCID: PMC3581386 DOI: 10.1074/jbc.m112.408237] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
The serotonin transporter (SERT) maintains serotonergic neurotransmission via rapid reuptake of serotonin from the synaptic cleft. SERT relies exclusively on the coat protein complex II component SEC24C for endoplasmic reticulum (ER) export. The closely related transporters for noradrenaline and dopamine depend on SEC24D. Here, we show that discrimination between SEC24C and SEC24D is specified by the residue at position +2 downstream from the ER export motif (607RI608 in SERT). Substituting Lys610 with tyrosine, the corresponding residue found in the noradrenaline and dopamine transporters, switched the SEC24 isoform preference: SERT-K610Y relied solely on SEC24D to reach the cell surface. This analysis was extended to other SLC6 (solute carrier 6) transporter family members: siRNA-dependent depletion of SEC24C, but not of SEC24D, reduced surface levels of the glycine transporter-1a, the betaine/GABA transporter and the GABA transporter-4. Experiments with dominant negative versions of SEC24C and SEC24D recapitulated these findings. We also verified that the presence of two ER export motifs (in concatemers of SERT and GABA transporter-1) supported recruitment of both SEC24C and SEC24D. To the best of our knowledge, this is the first report to document a change in SEC24 specificity by mutation of a single residue in the client protein. Our observations allowed for deducing a rule for SLC6 family members: a hydrophobic residue (Tyr or Val) in the +2 position specifies interaction with SEC24D, and a hydrophilic residue (Lys, Asn, or Gln) recruits SEC24C. Variations in SEC24C are linked to neuropsychiatric disorders. The present findings provide a mechanistic explanation. Variations in SEC24C may translate into distinct surface levels of neurotransmitter transporters.
Collapse
Affiliation(s)
- Sonja Sucic
- Institute of Pharmacology, Center of Physiology and Pharmacology, Medical University of Vienna, A-1090 Vienna, Austria
| | | | | | | | | | | | | |
Collapse
|
34
|
Fernandes MJG, Costa SPG, Gonçalves MST. Synthesis and light triggered release of catecholamines from pyrenylmethyl carbamate cages. NEW J CHEM 2013. [DOI: 10.1039/c3nj00247k] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
35
|
Transport of biogenic amine neurotransmitters at the mouse blood-retina and blood-brain barriers by uptake1 and uptake2. J Cereb Blood Flow Metab 2012; 32:1989-2001. [PMID: 22850405 PMCID: PMC3493996 DOI: 10.1038/jcbfm.2012.109] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Uptake1 and uptake2 transporters are involved in the extracellular clearance of biogenic amine neurotransmitters at synaptic clefts. We looked for them at the blood-brain barrier (BBB) and blood-retina barriers (BRB), where they could be involved in regulating the neurotransmitter concentration and modulate/terminate receptor-mediated effects within the neurovascular unit (NVU). Uptake2 (Oct1-3/Slc22a1-3, Pmat/Slc29a4) and Mate1/Slc47a1 transporters are also involved in the transport of xenobiotics. We used in situ carotid perfusion of prototypic substrates like [(3)H]-1-methyl-4-phenylpyridinium ([(3)H]-MPP(+)), [(3)H]-histamine, [(3)H]-serotonin, and [(3)H]-dopamine, changes in ionic composition and genetic deletion of Oct1-3 carriers to detect uptake1 and uptake2 at the BBB and BRB. We showed that uptake1 and uptake2 are involved in the transport of [(3)H]-dopamine and [(3)H]-MPP(+) at the blood luminal BRB, but not at the BBB. These functional studies, together with quantitative RT-PCR and confocal imaging, suggest that the mouse BBB lacks uptake1 (Net/Slc6a2, Dat/Slc6a3, Sert/Slc6a4), uptake2, and Mate1 on both the luminal and abluminal sides. However, we found evidence for functional Net and Oct1 transporters at the luminal BRB. These heterogeneous transport properties of the brain and retina NVUs suggest that the BBB helps protect the brain against biogenic amine neurotransmitters in the plasma while the BRB has more of a metabolic/endocrine role.
Collapse
|
36
|
Ohadi M, Mirabzadeh A, Esmaeilzadeh-Gharehdaghi E, Rezazadeh M, Hosseinkhanni S, Oladnabi M, Firouzabadi SG, Darvish H. Novel evidence of the involvement of calreticulin in major psychiatric disorders. Prog Neuropsychopharmacol Biol Psychiatry 2012; 37:276-81. [PMID: 22507216 DOI: 10.1016/j.pnpbp.2012.02.007] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/16/2012] [Revised: 02/12/2012] [Accepted: 02/14/2012] [Indexed: 12/20/2022]
Abstract
Calreticulin (CALR) is a multi-functional protein that is strictly conserved across species. Two mRNA transcripts have been recognized for the CALR gene in humans, which use a common promoter sequence. We have recently reported mutations in the CALR promoter that co-occur with psychosis. One of those mutations at -220A increases gene expression in human BE(2)-C and HEK-293 cell lines. This mutation is the first instance of a functional cognition-deficit mutation reversing a human gene promoter to the primitive type. In the current study, we analyzed the effect of the most widely-used mood-stabilizing drug, valproic acid (VPA), on nucleotide -220 in two neuronal cell lines, LAN-5 and N2A. Remarkably, VPA increased gene expression in the cells with the wild-type -220C construct, whereas a dramatic decrease in gene expression was observed in the cell lines with the mutant construct (p<0.000004 and p<0.016, respectively). We also sequenced the 600-bp CALR promoter, and the highly conserved intron 1 sequence in an independent sample of patients afflicted with major psychiatric disorders and controls. A new case of major depressive disorder with psychotic features with the -220A mutation was identified. A novel 1-bp insertion was also detected in intron 1 at IVSI-310, in a case of amphetamine-induced psychosis. As for the psychosis-linked CALR promoter mutations identified to-date, the IVSI mutation was not detected in the control pool. This mutation creates a RREB-1 transcription factor binding site within the first intron. Our present findings identify the site of action of VPA in the CALR promoter, and introduce a novel mutation in a case of substance-induced psychosis in the first intron of CALR.
Collapse
Affiliation(s)
- M Ohadi
- Genetics Research Center, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran.
| | | | | | | | | | | | | | | |
Collapse
|
37
|
HIV-1 Tat protein decreases dopamine transporter cell surface expression and vesicular monoamine transporter-2 function in rat striatal synaptosomes. J Neuroimmune Pharmacol 2012; 7:629-39. [PMID: 22570010 DOI: 10.1007/s11481-012-9369-9] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2012] [Accepted: 04/16/2012] [Indexed: 12/13/2022]
Abstract
The dopamine (DA) transporter (DAT) and vesicular monoamine transporter (VMAT2) proteins interact as a biochemical complex to regulate dopaminergic neurotransmission. We have reported that HIV-1Tat(1-86) decreases the specific [(3)H]DA uptake and [(3)H]WIN 35,428 binding sites without a change in total DAT immunoreactivity in rat striatum (Zhu et al., 2009b). The present study determined the effects of Tat on DAT phosphorylation and trafficking, and vesicular [(3)H]DA uptake. Pre-incubation of rat striatal synaptosomes with the protein kinase C (PKC) inhibitor bisindolylmaleimide I (1 μM) completely blocked Tat(1-86)-induced reduction of [(3)H]DA uptake, indicating that Tat regulates DAT function through a PKC-dependent mechanism. After exposure of synaptosomes to Tat(1-86) (1 μM), DAT immunoreactivity was decreased in plasma membrane enriched fractions (P3) and increased in vesicle-enriched fractions (P4) relative to controls without change in total synaptosomal fractions (P2), suggesting that Tat-induced inhibition of DA uptake is attributable to DAT internalization. Although both DAT and VMAT2 proteins are essential for the regulation of DA disposition in synapse and cytosol, Tat inhibited the specific [(3)H]DA uptake into vesicles (P4) and synaptosomes (P2) by 35 % and 26 %, respectively, inferring that the inhibitory effect of Tat was more profound in VMAT2 protein than in DAT protein. Taken together, the current study reveals that Tat inhibits DAT function through a PKC and trafficking-dependent mechanism and that Tat impacts the dopaminergic tone by regulating both DAT and VMAT2 proteins. These findings provide new insight into understanding the pharmacological mechanisms of HIV-1 viral protein-induced dysfunction of DA neurotransmission in HIV-infected patients.
Collapse
|
38
|
Bryant CD, Kole LA, Guido MA, Sokoloff G, Palmer AA. Congenic dissection of a major QTL for methamphetamine sensitivity implicates epistasis. GENES BRAIN AND BEHAVIOR 2012; 11:623-32. [PMID: 22487465 DOI: 10.1111/j.1601-183x.2012.00795.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
We previously used the C57BL/6J (B6) × A/J mouse chromosome substitution strain (CSS) panel to identify a major quantitative trait locus (QTL) on chromosome 11 influencing methamphetamine (MA)-induced locomotor activity. We then made an F(2) cross between CSS-11 and B6 and narrowed the locus (Bayes credible interval: 79-109 Mb) which was inherited dominantly and accounted for 14% of the phenotypic variance in the CSS panel. In the present study, we created congenic and subcongenic lines possessing heterozygous portions of this QTL to narrow the interval. We identified one line (84-96 Mb) that recapitulated the QTL, thus narrowing the region to 12 Mb. This interval also produced a small decrease in locomotor activity following prior saline treatment. When we generated subcongenic lines spanning the entire 12-Mb region, the phenotypic difference in MA sensitivity abruptly disappeared, suggesting an epistatic mechanism. We also evaluated the rewarding properties of MA (2 mg/kg, i.p.) in the 84- to 96-Mb congenic line using the conditioned place preference (CPP) test. We replicated the locomotor difference in the MA-paired CPP chamber yet observed no effect of genotype on MA-CPP, supporting the specificity of this QTL for MA-induced locomotor activity under these conditions. Lastly, to aid in prioritizing candidate genes responsible for this QTL, we used the Affymetrix GeneChip(®) Mouse Gene 1.0ST Array to identify genes containing expression QTLs (eQTL) in the striatum of drug-naÏve, congenic mice. These findings highlight the difficulty of using congenic lines to fine map QTLs and illustrate how epistasis may thwart such efforts.
Collapse
Affiliation(s)
- C D Bryant
- Department of Human Genetics, University of Chicago, IL 60637, USA
| | | | | | | | | |
Collapse
|
39
|
Yamakado H, Moriwaki Y, Yamasaki N, Miyakawa T, Kurisu J, Uemura K, Inoue H, Takahashi M, Takahashi R. α-Synuclein BAC transgenic mice as a model for Parkinson's disease manifested decreased anxiety-like behavior and hyperlocomotion. Neurosci Res 2012; 73:173-7. [PMID: 22475625 DOI: 10.1016/j.neures.2012.03.010] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2011] [Revised: 03/03/2012] [Accepted: 03/19/2012] [Indexed: 12/31/2022]
Abstract
α-Synuclein (α-syn), the main component of Lewy bodies, was identified as a genetic risk factor for idiopathic Parkinson's disease (PD). As a model for PD, we generated human α-syn bacterial artificial chromosome transgenic mice (BAC tg mice) harboring the entire human α-syn gene and its gene expression regulatory regions. The α-syn BAC tg mice manifested decreased anxiety-like behaviors which may reflect non-motor symptoms of early PD, and they exhibited increased SERT expression that may be responsible for decreased anxiety-like behaviors. Our α-syn BAC tg mice could be a valuable tool to evaluate α-syn gene dosage effects in vivo.
Collapse
Affiliation(s)
- Hodaka Yamakado
- Department of Neurology, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | | | | | | | | | | | | | | | | |
Collapse
|
40
|
Wu PH, Schulz KM. Advancing addiction treatment: what can we learn from animal studies? ILAR J 2012; 53:4-13. [PMID: 23520595 DOI: 10.1093/ilar.53.1.4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Substance addiction is a maladaptive behavior characterized by compulsive and uncontrolled self-administration of a substance (drug). Years of research indicate that addictive behavior is the result of complex interactions between the drug, the user, and the environment in which the drug is used; therefore, addiction cannot simply be attributed to the neurobiological actions of a drug. However, despite the obvious complexity of addictive behavior, animal models have both advanced understanding of addiction and contributed importantly to the development of medications to treat this disease. We briefly review recent animal models used to study drug addiction and the contribution of data generated by these animal models for the clinical treatment of addictive disorders.
Collapse
Affiliation(s)
- Peter H Wu
- Department of Psychiatry, University of Colorado Anschutz Medical Campus, Research Complex-1 North, Mail Stop 8344, 12800 East 19th Avenue, Aurora, Colorado 80045, USA.
| | | |
Collapse
|