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Baliova M, Jursky F. Manganese- and zinc-coordinated interaction of Schistosoma japonicum glutathione S-transferase with neurotransmitter transporters GlyT1 and GAT3 in vitro. Exp Parasitol 2024; 259:108721. [PMID: 38369179 DOI: 10.1016/j.exppara.2024.108721] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2023] [Revised: 02/13/2024] [Accepted: 02/15/2024] [Indexed: 02/20/2024]
Abstract
Glutathione S-transferases (GSTs) are a family of multifunctional isoenzymes involved in the neutralization of toxic compounds, drug resistance and several other cellular functions. The glutathione S-transferase enzyme of Schistosoma japonicum (SjGST-26) plays a role in human schistosomiasis and is also a frequently used fusion partner in mammalian and bacterial expression and pull-down systems. GSTs seem not to be naturally associated with metal ions. Exceptionally, in vitro, metal binding sites have been previously described in some schistosome GSTs; however, their possible physiological role is unclear. Molecules of several neurotransmitter transporters also contain a regulatory zinc binding site, which affects their transport cycle. Here we show that among several metals, manganese and zinc are able to induce a specific protein interaction of SjGST-26 with the glycine transporter GlyT1 and the GABA transporter GAT3 in vitro. The results suggest that metal-binding sites on SjGST-26 and neurotransmitter transporters might function in metal-coordinated interactions with other metalloproteins. Our results additionally indicate that the presence of metal ions in SjGST-26-based GST protein pull-down assays may lead to a false-positive interaction if the potential interacting target is the metalloprotein.
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Affiliation(s)
- Martina Baliova
- Laboratory of Neurobiology, Institute of Molecular Biology, Slovak Academy of Sciences, Dubravska Cesta 21, 845 51, Bratislava, Slovakia
| | - Frantisek Jursky
- Laboratory of Neurobiology, Institute of Molecular Biology, Slovak Academy of Sciences, Dubravska Cesta 21, 845 51, Bratislava, Slovakia.
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2
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Shen Z, Haragopal H, Li YV. Zinc modulates synaptic transmission by differentially regulating synaptic glutamate homeostasis in hippocampus. Eur J Neurosci 2020; 52:3710-3722. [PMID: 32302450 DOI: 10.1111/ejn.14749] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Revised: 02/29/2020] [Accepted: 04/10/2020] [Indexed: 12/27/2022]
Abstract
A subset of presynaptic glutamatergic vesicles in the brain co-releases zinc (Zn2+ ) with glutamate into the synapse. However, the role of synaptically released Zn2+ is still under investigation. Here, we studied the effect of Zn2+ on glutamate homeostasis by measuring the evoked extracellular glutamate level (EGL) and the probability of evoked action potential (PEAP ) at the Zn2+ -containing or zincergic mossy fiber-CA3 synapses of the rat hippocampus. We found that the application of Zn2+ (ZnCl2 ) exerted bidirectional effects on both EGL and PEAP : facilitatory at low concentration (~1 µM) while repressive at high concentration (~50 µM). To determine the action of endogenous Zn2+ , we also used extracellular Zn2+ chelator to remove the synaptically released Zn2+ . Zn2+ chelation reduced both EGL and PEAP , suggesting that endogenous Zn2+ has mainly a facilitative role in glutamate secretion on physiological condition. We revealed that calcium/calmodulin-dependent protein kinase II was integral to the mechanism by which Zn2+ facilitated the release of glutamate. Moreover, a glutamate transporter was the molecular entity for the action of Zn2+ on glutamate uptake by which Zn2+ decreases glutamate availability. Taken together, we show a novel action of Zn2+ , which is to biphasically regulate glutamate homeostasis via Zn2+ concentration-dependent synaptic facilitation and depression. Thus, co-released Zn2+ is physiologically important for enhancing weak stimulation, but potentially mitigates excessive stimulation to keep synaptic transmission within optimal physiological range.
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Affiliation(s)
- Zhijun Shen
- Departments of Biological Sciences and Biomedical Sciences, Ohio University, Athens, OH, USA
| | - Hariprakash Haragopal
- Departments of Biological Sciences and Biomedical Sciences, Ohio University, Athens, OH, USA
| | - Yang V Li
- Departments of Biological Sciences and Biomedical Sciences, Ohio University, Athens, OH, USA
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3
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Challasivakanaka S, Zhen J, Smith ME, Reith MEA, Foster JD, Vaughan RA. Dopamine transporter phosphorylation site threonine 53 is stimulated by amphetamines and regulates dopamine transport, efflux, and cocaine analog binding. J Biol Chem 2017; 292:19066-19075. [PMID: 28939767 DOI: 10.1074/jbc.m117.787002] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2017] [Revised: 08/29/2017] [Indexed: 11/06/2022] Open
Abstract
The dopamine transporter (DAT) controls the spatial and temporal dynamics of dopamine neurotransmission through reuptake of extracellular transmitter and is a target for addictive compounds such as cocaine, amphetamine (AMPH), and methamphetamine (METH). Reuptake is regulated by kinase pathways and drug exposure, allowing for fine-tuning of clearance in response to specific conditions, and here we examine the impact of transporter ligands on DAT residue Thr-53, a proline-directed phosphorylation site previously implicated in AMPH-stimulated efflux mechanisms. Our findings show that Thr-53 phosphorylation is stimulated in a transporter-dependent manner by AMPH and METH in model cells and rat striatal synaptosomes, and in striatum of rats given subcutaneous injection of METH. Rotating disc electrode voltammetry revealed that initial rates of uptake and AMPH-induced efflux were elevated in phosphorylation-null T53A DAT relative to WT and charge-substituted T53D DATs, consistent with functions related to charge or polarity. These effects occurred without alterations of surface transporter levels, and mutants also showed reduced cocaine analog binding affinity that was not rescued by Zn2+ Together these findings support a role for Thr-53 phosphorylation in regulation of transporter kinetic properties that could impact DAT responses to amphetamines and cocaine.
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Affiliation(s)
- Sathya Challasivakanaka
- From the Department of Biomedical Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, North Dakota 58201 and
| | | | - Margaret E Smith
- From the Department of Biomedical Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, North Dakota 58201 and
| | - Maarten E A Reith
- the Departments of Psychiatry and.,Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, New York 10016
| | - James D Foster
- From the Department of Biomedical Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, North Dakota 58201 and
| | - Roxanne A Vaughan
- From the Department of Biomedical Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, North Dakota 58201 and
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4
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Zinc in the Monoaminergic Theory of Depression: Its Relationship to Neural Plasticity. Neural Plast 2017; 2017:3682752. [PMID: 28299207 PMCID: PMC5337390 DOI: 10.1155/2017/3682752] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2016] [Accepted: 01/24/2017] [Indexed: 12/21/2022] Open
Abstract
Preclinical and clinical studies have demonstrated that zinc possesses antidepressant properties and that it may augment the therapy with conventional, that is, monoamine-based, antidepressants. In this review we aim to discuss the role of zinc in the pathophysiology and treatment of depression with regard to the monoamine hypothesis of the disease. Particular attention will be paid to the recently described zinc-sensing GPR39 receptor as well as aspects of zinc deficiency. Furthermore, an attempt will be made to give a possible explanation of the mechanisms by which zinc interacts with the monoamine system in the context of depression and neural plasticity.
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5
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Marszałek I, Krężel A, Goch W, Zhukov I, Paczkowska I, Bal W. Revised stability constant, spectroscopic properties and binding mode of Zn(II) to FluoZin-3, the most common zinc probe in life sciences. J Inorg Biochem 2016; 161:107-14. [PMID: 27216451 DOI: 10.1016/j.jinorgbio.2016.05.009] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2016] [Revised: 05/04/2016] [Accepted: 05/13/2016] [Indexed: 01/01/2023]
Abstract
2-[2-[2-[2-[bis(carboxylatomethyl)amino]-5-methoxyphenoxy]ethoxy]-4-(2,7-difluoro-3-oxido-6-oxo-4a,9a-dihydroxanthen-9-yl)anilino]acetate (FluoZin-3) is used very broadly in life sciences as intra- and extracellular Zn(II) sensor selective for Zn(II) over Co(II), Ca(II) and Mg(II) ions at their physiological concentrations. It has been used for determination of relative and absolute levels of exchangeable Zn(II) in cells and extracellular fluids. Despite its popularity, the knowledge of its acid/base and Zn(II) coordination abilities and of its spectroscopic properties remained very limited. Also the published conditional dissociation constant ((C)Kd) values at pH7.4 are slightly discrepant, (15nM or 8.9nM). In this work we determined the (C)Kd for Zn(II) complexation by FluoZin-3 at pH7.4 with nitrilotriacetic acid (NTA) as competitor using two independent methods: fluorimetry and UV-Vis spectroscopy. For the first time, we investigated FluoZin-3 alone and complexed with Zn(II) in the wide range of pH, determining the total of eight pKa values from fluorescence spectra and from various regions of UV-Vis spectra. The validated values of (C)Kd (9.1±0.4nM; -log (C)Kd=8.04) and of the absolute (pH-independent) stability constant log βZnL (8.16±0.05) were provided by fluorescence spectroscopy experiments performed at 1μM concentrations. Our experiments demonstrated that both of aminocarboxylate moieties of FluoZin-3 bind the Zn(II) ion synergistically.
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Affiliation(s)
- I Marszałek
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a, 02-106 Warsaw, Poland
| | - A Krężel
- Laboratory of Chemical Biology, Faculty of Biotechnology, University of Wroclaw, Joliot-Curie 14a, 50-383 Wroclaw, Poland
| | - W Goch
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a, 02-106 Warsaw, Poland
| | - I Zhukov
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a, 02-106 Warsaw, Poland; NanoBioMedical Centre, Adam Mickiewicz University, Umultowska 85, 61-614 Poznań, Poland
| | - I Paczkowska
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a, 02-106 Warsaw, Poland
| | - W Bal
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a, 02-106 Warsaw, Poland.
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6
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Mitsuya H, Omata N, Kiyono Y, Mizuno T, Murata T, Mita K, Okazawa H, Wada Y. The co-occurrence of zinc deficiency and social isolation has the opposite effects on mood compared with either condition alone due to changes in the central norepinephrine system. Behav Brain Res 2015; 284:125-30. [PMID: 25680677 DOI: 10.1016/j.bbr.2015.02.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2014] [Revised: 02/02/2015] [Accepted: 02/03/2015] [Indexed: 01/22/2023]
Abstract
Nutritional and social environmental problems during the early stages of life are closely associated with the pathophysiology of mood disorders such as depression. Disruption or dysfunction of the central norepinephrine (NE) system is also considered to play a role in mood disorders. Therefore, we evaluated the effects of zinc deficiency and/or social isolation on mood and changes in the central NE system using rats. Compared with the controls, the rats subjected to zinc deficiency or social isolation alone exhibited increased anxiety-related behavior in the elevated plus maze and greater depression-like behavior in the forced swim test. However, the co-occurrence of zinc deficiency and social isolation resulted in decreased anxiety-related behavior and control levels of depression-like behavior. Social isolation alone decreased the rats' cerebral NE concentrations. The expression of the NE transporter was not affected by social isolation alone, but its expression in the locus coeruleus was markedly decreased by the co-occurrence of social isolation and zinc deficiency, and this change was accompanied by an increase in the blood concentration of 3-methoxy-4-hydroxyphenylglycol, which is a marker of central NE system activity. These findings suggest that zinc deficiency or social isolation alone induce anxious or depressive symptoms, but the presence of both conditions has anxiolytic or antidepressive effects. Furthermore, these opposing effects of mood-related behaviors were found to be associated with changes in the central NE system.
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Affiliation(s)
- Hironori Mitsuya
- Department of Neuropsychiatry, Faculty of Medical Sciences, University of Fukui, 23-3 Matsuokashimoaizuki, Eiheiji-cho, Yoshida-gun, Fukui 910-1193, Japan
| | - Naoto Omata
- Department of Neuropsychiatry, Faculty of Medical Sciences, University of Fukui, 23-3 Matsuokashimoaizuki, Eiheiji-cho, Yoshida-gun, Fukui 910-1193, Japan.
| | - Yasushi Kiyono
- Biomedical Imaging Research Center, University of Fukui, 23-3 Matsuokashimoaizuki, Eiheiji-cho, Yoshida-gun, Fukui 910-1193, Japan; Research and Education Program for Life Science, University of Fukui, 23-3 Matsuokashimoaizuki, Eiheiji-cho, Yoshida-gun, Fukui 910-1193, Japan
| | - Tomoyuki Mizuno
- Department of Neuropsychiatry, Faculty of Medical Sciences, University of Fukui, 23-3 Matsuokashimoaizuki, Eiheiji-cho, Yoshida-gun, Fukui 910-1193, Japan; Psychiatric Medical Center, Fukui Prefectural Hospital, 2-8-1 Yotsui, Fukui, Fukui 910-8526, Japan
| | - Tetsuhito Murata
- Department of Neuropsychiatry, Faculty of Medical Sciences, University of Fukui, 23-3 Matsuokashimoaizuki, Eiheiji-cho, Yoshida-gun, Fukui 910-1193, Japan; Psychiatric Medical Center, Fukui Prefectural Hospital, 2-8-1 Yotsui, Fukui, Fukui 910-8526, Japan
| | - Kayo Mita
- Department of Neuropsychiatry, Faculty of Medical Sciences, University of Fukui, 23-3 Matsuokashimoaizuki, Eiheiji-cho, Yoshida-gun, Fukui 910-1193, Japan
| | - Hidehiko Okazawa
- Biomedical Imaging Research Center, University of Fukui, 23-3 Matsuokashimoaizuki, Eiheiji-cho, Yoshida-gun, Fukui 910-1193, Japan
| | - Yuji Wada
- Department of Neuropsychiatry, Faculty of Medical Sciences, University of Fukui, 23-3 Matsuokashimoaizuki, Eiheiji-cho, Yoshida-gun, Fukui 910-1193, Japan
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7
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Zinc and Zinc Chelators Modify Taurine Transport in Rat Retinal Cells. Neurochem Res 2014; 39:2234-9. [DOI: 10.1007/s11064-014-1425-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2014] [Revised: 08/22/2014] [Accepted: 08/25/2014] [Indexed: 11/26/2022]
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8
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Gaffaney JD, Shetty M, Felts B, Pramod AB, Foster JD, Henry LK, Vaughan RA. Antagonist-induced conformational changes in dopamine transporter extracellular loop two involve residues in a potential salt bridge. Neurochem Int 2013; 73:16-26. [PMID: 24269640 DOI: 10.1016/j.neuint.2013.11.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2013] [Revised: 11/04/2013] [Accepted: 11/06/2013] [Indexed: 10/26/2022]
Abstract
Ligand-induced changes in the conformation of extracellular loop (EL) 2 in the rat (r) dopamine transporter (DAT) were examined using limited proteolysis with endoproteinase Asp-N and detection of cleavage products by epitope-specific immunoblotting. The principle N-terminal fragment produced by Asp-N was a 19kDa peptide likely derived by proteolysis of EL2 residue D174, which is present just past the extracellular end of TM3. Production of this fragment was significantly decreased by binding of cocaine and other uptake blockers, but was not affected by substrates or Zn(2+), indicating the presence of a conformational change at D174 that may be related to the mechanism of transport inhibition. DA transport activity and cocaine analog binding were decreased by Asp-N treatment, suggesting a requirement for EL2 integrity in these DAT functions. In a previous study we demonstrated that ligand-induced protease resistance also occurred at R218 on the C-terminal side of rDAT EL2. Here using substituted cysteine accessibility analysis of human (h) DAT we confirm cocaine-induced alterations in reactivity of the homologous R219 and identify conformational sensitivity of V221. Focused molecular modeling of D174 and R218 based on currently available Aquifex aeolicus leucine transporter crystal structures places these residues within 2.9Å of one another, suggesting their proximity as a structural basis for their similar conformational sensitivities and indicating their potential to form a salt bridge. These findings extend our understanding of DAT EL2 and its role in transport and binding functions.
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Affiliation(s)
- Jon D Gaffaney
- Department of Basic Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, ND 58202, United States
| | - Madhur Shetty
- Department of Basic Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, ND 58202, United States
| | - Bruce Felts
- Department of Basic Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, ND 58202, United States
| | - Akula-Bala Pramod
- Department of Basic Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, ND 58202, United States
| | - James D Foster
- Department of Basic Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, ND 58202, United States
| | - L Keith Henry
- Department of Basic Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, ND 58202, United States.
| | - Roxanne A Vaughan
- Department of Basic Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, ND 58202, United States.
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9
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Müller A, Kleinau G, Piechowski CL, Müller TD, Finan B, Pratzka J, Grüters A, Krude H, Tschöp M, Biebermann H. G-protein coupled receptor 83 (GPR83) signaling determined by constitutive and zinc(II)-induced activity. PLoS One 2013; 8:e53347. [PMID: 23335960 PMCID: PMC3546042 DOI: 10.1371/journal.pone.0053347] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2012] [Accepted: 11/27/2012] [Indexed: 12/31/2022] Open
Abstract
The G-protein coupled receptor 83 (GPR83) is an orphan G-protein coupled receptor for which the natural ligand(s) and signaling pathway(s) remain to be identified. Previous studies suggest a role of GPR83 in the regulation of thermogenesis and the control of circulating adiponectin. The aim of this study was to gain insights into the molecular underpinnings underlying GPR83 signaling. In particular, we aimed to assess the underlying G-protein activated signaling pathway of GPR83 and how this pathway is affected by mutational activation and zinc(II) challenge. Finally, we assessed the capacity of GPR83 for homodimerization. Our results show for the first time that mouse (m) GPR83 has high basal Gq/11 activity without affecting Gi or Gs signaling. Furthermore, we found that, under physiological conditions, zinc(II) (but not calcium(II) and magnesium(II)) potently activates mGPR83, thus identifying zinc(II) as an endogenous molecule with agonistic capability to activate mGPR83. In line with the observation that zinc(II)-ions activate mGPR83, we identified a cluster of ion-binding sensitive amino acids (e.g. His145, His204, Cys207, Glu217) in an activation sensitive receptor region of mGPR83. The occurrence of a constitutive activating mutant and a zinc(II)-binding residue at the N-terminal part corroborate the importance of this region in mGPR83 signal regulation. Finally, our results indicate that mGPR83 forms homodimers, which extend the current knowledge and molecular facets of GPR83 signaling.
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Affiliation(s)
- Anne Müller
- Institute of Experimental Pediatric Endocrinology, Charité Universitätsmedizin Berlin, Berlin, Germany
| | - Gunnar Kleinau
- Institute of Experimental Pediatric Endocrinology, Charité Universitätsmedizin Berlin, Berlin, Germany
| | - Carolin L. Piechowski
- Institute of Experimental Pediatric Endocrinology, Charité Universitätsmedizin Berlin, Berlin, Germany
| | - Timo D. Müller
- Institute of Diabetes and Obesity, Helmholtz Center Munich, German Research Center for Environmental Health (GmbH), Munich, Germany
| | - Brian Finan
- Institute of Diabetes and Obesity, Helmholtz Center Munich, German Research Center for Environmental Health (GmbH), Munich, Germany
| | - Juliane Pratzka
- Institute of Experimental Pediatric Endocrinology, Charité Universitätsmedizin Berlin, Berlin, Germany
| | - Annette Grüters
- Institute of Experimental Pediatric Endocrinology, Charité Universitätsmedizin Berlin, Berlin, Germany
| | - Heiko Krude
- Institute of Experimental Pediatric Endocrinology, Charité Universitätsmedizin Berlin, Berlin, Germany
| | - Matthias Tschöp
- Institute of Diabetes and Obesity, Helmholtz Center Munich, German Research Center for Environmental Health (GmbH), Munich, Germany
- Department of Metabolic Diseases, Technical University, Munich, Germany
| | - Heike Biebermann
- Institute of Experimental Pediatric Endocrinology, Charité Universitätsmedizin Berlin, Berlin, Germany
- * E-mail:
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10
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García-Colunga J, Godoy-García U, Vázquez-Gómez E. Interaction of bupropion and zinc with neuronal nicotinic acetylcholine receptors. Neuropharmacology 2011; 61:1202-9. [DOI: 10.1016/j.neuropharm.2011.07.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2010] [Revised: 06/06/2011] [Accepted: 07/10/2011] [Indexed: 12/28/2022]
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11
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Kristensen AS, Andersen J, Jørgensen TN, Sørensen L, Eriksen J, Loland CJ, Strømgaard K, Gether U. SLC6 neurotransmitter transporters: structure, function, and regulation. Pharmacol Rev 2011; 63:585-640. [PMID: 21752877 DOI: 10.1124/pr.108.000869] [Citation(s) in RCA: 591] [Impact Index Per Article: 45.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The neurotransmitter transporters (NTTs) belonging to the solute carrier 6 (SLC6) gene family (also referred to as the neurotransmitter-sodium-symporter family or Na(+)/Cl(-)-dependent transporters) comprise a group of nine sodium- and chloride-dependent plasma membrane transporters for the monoamine neurotransmitters serotonin (5-hydroxytryptamine), dopamine, and norepinephrine, and the amino acid neurotransmitters GABA and glycine. The SLC6 NTTs are widely expressed in the mammalian brain and play an essential role in regulating neurotransmitter signaling and homeostasis by mediating uptake of released neurotransmitters from the extracellular space into neurons and glial cells. The transporters are targets for a wide range of therapeutic drugs used in treatment of psychiatric diseases, including major depression, anxiety disorders, attention deficit hyperactivity disorder and epilepsy. Furthermore, psychostimulants such as cocaine and amphetamines have the SLC6 NTTs as primary targets. Beginning with the determination of a high-resolution structure of a prokaryotic homolog of the mammalian SLC6 transporters in 2005, the understanding of the molecular structure, function, and pharmacology of these proteins has advanced rapidly. Furthermore, intensive efforts have been directed toward understanding the molecular and cellular mechanisms involved in regulation of the activity of this important class of transporters, leading to new methodological developments and important insights. This review provides an update of these advances and their implications for the current understanding of the SLC6 NTTs.
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Affiliation(s)
- Anders S Kristensen
- Department of Medicinal Chemistry, Faculty of Pharmaceutical Sciences, University of Copenhagen, Copenhagen, Denmark.
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12
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Bishop GM, Scheiber IF, Dringen R, Robinson SR. Synergistic accumulation of iron and zinc by cultured astrocytes. J Neural Transm (Vienna) 2010; 117:809-17. [DOI: 10.1007/s00702-010-0420-9] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2010] [Accepted: 05/12/2010] [Indexed: 12/01/2022]
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13
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Sucic S, Dallinger S, Zdrazil B, Weissensteiner R, Jørgensen TN, Holy M, Kudlacek O, Seidel S, Cha JH, Gether U, Newman AH, Ecker GF, Freissmuth M, Sitte HH. The N terminus of monoamine transporters is a lever required for the action of amphetamines. J Biol Chem 2010; 285:10924-38. [PMID: 20118234 PMCID: PMC2856298 DOI: 10.1074/jbc.m109.083154] [Citation(s) in RCA: 100] [Impact Index Per Article: 7.1] [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) terminates neurotransmission by removing serotonin from the synaptic cleft. In addition, it is the site of action of antidepressants (which block the transporter) and of amphetamines (which induce substrate efflux). We explored the functional importance of the N terminus in mediating the action of amphetamines by focusing initially on the highly conserved threonine residue at position 81, a candidate site for phosphorylation by protein kinase C. Molecular dynamics simulations of the wild type SERT, compared with its mutations SERTT81A and SERTT81D, suggested structural changes in the inner vestibule indicative of an opening of the inner vestibule. Predictions from this model (e.g. the preferential accumulation of SERTT81A in the inward conformation, its reduced turnover number, and a larger distance between its N and C termini) were verified. Most importantly, SERTT81A (and the homologous mutations in noradrenaline and dopamine) failed to support amphetamine-induced efflux, and this was not remedied by aspartate at this position. Amphetamine-induced currents through SERTT81A were comparable with those through the wild type transporter. Both abundant Na+ entry and accumulation of SERTT81A in the inward facing conformation ought to favor amphetamine-induced efflux. Thus, we surmised that the N terminus must play a direct role in driving the transporter into a state that supports amphetamine-induced efflux. This hypothesis was verified by truncating the first 64 amino acids and by tethering the N terminus to an additional transmembrane helix. Either modification abolished amphetamine-induced efflux. We therefore conclude that the N terminus of monoamine transporters acts as a lever that sustains reverse transport.
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Affiliation(s)
- Sonja Sucic
- Center of Biomolecular Medicine and Pharmacology, Institute of Pharmacology, Medical University Vienna, A-1090 Vienna, Austria
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14
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Storjohann L, Holst B, Schwartz TW. Molecular mechanism of Zn2+ agonism in the extracellular domain of GPR39. FEBS Lett 2008; 582:2583-8. [PMID: 18588883 DOI: 10.1016/j.febslet.2008.06.030] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2008] [Revised: 05/14/2008] [Accepted: 06/17/2008] [Indexed: 11/18/2022]
Abstract
Ala substitution of potential metal-ion binding residues in the main ligand-binding pocket of the Zn2+-activated G protein-coupled receptor 39 (GPR39) receptor did not decrease Zn2+ potency. In contrast, Zn2+ stimulation was eliminated by combined substitution of His17 and His19, located in the N-terminal segment. Surprisingly, substitution of Asp313 located in extracellular loop 3 greatly increased ligand-independent signaling and apparently eliminated Zn2+-induced activation. It is proposed that Zn2+ acts as an agonist for GPR39, not in the classical manner by directly stabilizing an active conformation of the transmembrane domain, but instead by binding to His17 and His19 in the extracellular domain and potentially by diverting Asp313 from functioning as a tethered inverse agonist through engaging this residue in a tridentate metal-ion binding site.
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Affiliation(s)
- Laura Storjohann
- University of Copenhagen, Faculty of Health Sciences, Department of Neuroscience and Pharmacology, Laboratory for Molecular Pharmacology, Blegdamsvej 3b, Copenhagen N, Denmark
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Lobato KR, Binfaré RW, Budni J, Rosa AO, Santos ARS, Rodrigues ALS. Involvement of the adenosine A1 and A2A receptors in the antidepressant-like effect of zinc in the forced swimming test. Prog Neuropsychopharmacol Biol Psychiatry 2008; 32:994-9. [PMID: 18289757 DOI: 10.1016/j.pnpbp.2008.01.012] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/19/2007] [Revised: 01/04/2008] [Accepted: 01/15/2008] [Indexed: 12/23/2022]
Abstract
It was previously shown that the acute administration of zinc chloride elicits an antidepressant-like effect in the mouse forced swimming test (FST). We have also shown that the activation of adenosine A(1) and A(2A) receptors produces an antidepressant-like effect in FST. Thus, this study investigated the involvement of adenosine receptors in the antidepressant-like effect of zinc in the FST. The antidepressant-like effect of ZnCl(2) (30 mg/kg, i.p.) in the FST was prevented by the pretreatment of animals with caffeine (3 mg/kg, i.p., a non-selective adenosine receptor antagonist), DPCPX (2 mg/kg, i.p., a selective adenosine A(1) receptor antagonist) or ZM241385 (1 mg/kg, i.p., a selective adenosine A(2A) receptor antagonist), administered at doses that per se produced no anti-immobility effect. Moreover, the treatment of mice with CHA (0.05 mg/kg, i.p., a selective adenosine A(1) receptor agonist), DPMA (0.1 mg/kg, i.p., a selective adenosine A(2A) receptor agonist) or dipyridamole (0.1 microg/site, i.c.v., an adenosine transporter inhibitor) was able to potentiate the action of sub-effective doses of ZnCl(2). Taken together, the results suggest that the antidepressant-like effect of zinc in the mouse FST might involve a direct or indirect activation of adenosine A(1) and A(2A) receptors.
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Affiliation(s)
- Kelly R Lobato
- Departamento de Bioquímica, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Campus Universitário - Trindade - 88040-900, Florianópolis-SC, Brazil
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