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Moriyama Y, Hatano R, Moriyama S, Uehara S. Vesicular polyamine transporter as a novel player in amine-mediated chemical transmission. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2020; 1862:183208. [PMID: 32004521 DOI: 10.1016/j.bbamem.2020.183208] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2019] [Revised: 01/23/2020] [Accepted: 01/26/2020] [Indexed: 02/06/2023]
Abstract
The solute carrier 18B1 (SLC18B1) is the most recently identified gene of the vesicular amine transporter family and is conserved in the animal kingdom from insects to humans. Proteoliposomes containing the purified human SLC18B1 protein transport not only monoamines, but also polyamines, such as spermidine (Spd) and spermine (Spm), using an electrochemical gradient of H+ established by vacuolar H+-ATPase (V-ATPase) as the driving force. SLC18B1 gene knockdown abolished the exocytosis of polyamines from mast cells, which affected the secretion of histamine. SLC18B1 gene knockout decreased polyamine levels by ~20% in the brain, and impaired short- and long-term memory. Thus, the SLC18B1 protein is responsible for the vesicular storage and release of polyamines, and functions as a vesicular polyamine transporter (VPAT). VPAT may define when, where, and how polyamine-mediated chemical transmission occurs, providing insights into the more versatile and complex features of amine-mediated chemical transmission than currently considered.
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Affiliation(s)
- Yoshinori Moriyama
- Department of Biochemistry, Matsumoto Dental University, Shiojiri 399-0781, Japan; Division of Endocrinology and Metabolism, Department of Internal Medicine, Kurume University School of Medicine, Kurume 830-0011, Japan; CYRIC Tohoku University, Sendai 980-8578, Japan.
| | - Ryo Hatano
- Department of Medicinal Physiology, Graduate School of Medicine, Chiba University, Chiba 260-8670, Japan
| | - Satomi Moriyama
- Laboratory of Bio-Molecular Dynamics, Department of Collaborative Research, Nara Medical University, Kashihara 634-8521, Japan
| | - Shunsuke Uehara
- Department of Biochemistry, Matsumoto Dental University, Shiojiri 399-0781, Japan
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2
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Lauriano ER, Faggio C, Capillo G, Spanò N, Kuciel M, Aragona M, Pergolizzi S. Immunohistochemical characterization of epidermal dendritic-like cells in giant mudskipper, Periophthalmodon schlosseri. FISH & SHELLFISH IMMUNOLOGY 2018; 74:380-385. [PMID: 29337248 DOI: 10.1016/j.fsi.2018.01.014] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2017] [Revised: 12/21/2017] [Accepted: 01/11/2018] [Indexed: 06/07/2023]
Abstract
Giant Mudskipper, Periophthalmodon schlosseri (Pallas, 1770), is euryhaline, amphibious, and air-breathing fish. These fishes live in close association to mangrove forests and often spend over 90% of time out of water, in adjacent mudflats. They have developed morphological and physiological adaptations to satisfy their unique lifestyles. The skin is the primary interface between the body and the environment, and has a central role in host defence. The initiation of immune responses to antigens in the vertebrate skin has often been attributed to epidermal Langerhans'cells (LC) that are dendritic cells (DC), antigen-presenting cells (APC) which reside in the epidermis. Dendritic cells have been characterized morphologically and functionally in the teleost fish tissues such as rainbow trout, salmonids, medaka, African catfish and zebrafish. However, there is no evidence of the presence of DCs and their role in mudskippers immunity. The aim of this preliminary study was to characterize, through use of specific antibodies: Toll-like receptor 2, S100, serotonin (5-HT), and Vesicular acetylcholine transporter VAChT, a specific DC-like subpopulation in Pn. schlosseri's epidermis.
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Affiliation(s)
- E R Lauriano
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, Viale F. Stagno d'Alcontres 31, 98166 Messina, Italy
| | - C Faggio
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, Viale F. Stagno d'Alcontres 31, 98166 Messina, Italy.
| | - G Capillo
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, Viale F. Stagno d'Alcontres 31, 98166 Messina, Italy
| | - N Spanò
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, Viale F. Stagno d'Alcontres 31, 98166 Messina, Italy
| | - M Kuciel
- Poison Information Centre, Department of Toxicology and Environmental Disease, Jagiellonian University Medical College, ul. Kopernika 15, 31-105 Krakow, Poland
| | - M Aragona
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, Viale F. Stagno d'Alcontres 31, 98166 Messina, Italy
| | - S Pergolizzi
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, Viale F. Stagno d'Alcontres 31, 98166 Messina, Italy
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3
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Liu M, Heng J, Gao Y, Wang X. Crystal structures of MdfA complexed with acetylcholine and inhibitor reserpine. BIOPHYSICS REPORTS 2016; 2:78-85. [PMID: 28018966 PMCID: PMC5138259 DOI: 10.1007/s41048-016-0028-1] [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: 04/07/2016] [Accepted: 06/15/2016] [Indexed: 11/24/2022] Open
Abstract
The DHA12 family of transporters contains a number of prokaryotic and eukaryote membrane proteins. Some of these proteins share conserved sites intrinsic to substrate recognition, structural stabilization and conformational changes. For this study, we chose the MdfA transporter as a model DHA12 protein to study some general characteristics of the vesicular neurotransmitter transporters (VNTs), which all belong to the DHA12 family. Two crystal structures were produced for E. coli MdfA, one in complex with acetylcholine and the other with potential reserpine, which are substrate and inhibitor of VNTs, respectively. These structures show that the binding sites of these two molecules are different. The Ach-binding MfdA is mainly dependent on D34, while reserpine-binding site is more hydrophobic. Based on sequence alignment and homology modelling, we were able to provide mechanistic insights into the association between the inhibition and the conformational changes of these transporters.
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Affiliation(s)
- Ming Liu
- College of Biotechnology, Tianjin University of Science and Technology, Tianjin, 300457 China
| | - Jie Heng
- National Laboratory of Macromolecules, National Center of Protein Science - Beijing, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101 China
| | - Yuan Gao
- National Laboratory of Macromolecules, National Center of Protein Science - Beijing, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101 China
| | - Xianping Wang
- National Laboratory of Macromolecules, National Center of Protein Science - Beijing, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101 China
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Roy A, Dakroub M, Tezini GCSV, Liu Y, Guatimosim S, Feng Q, Salgado HC, Prado VF, Prado MAM, Gros R. Cardiac acetylcholine inhibits ventricular remodeling and dysfunction under pathologic conditions. FASEB J 2015; 30:688-701. [PMID: 26481308 DOI: 10.1096/fj.15-277046] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Accepted: 09/28/2015] [Indexed: 12/11/2022]
Abstract
Autonomic dysfunction is a characteristic of cardiac disease and decreased vagal activity is observed in heart failure. Rodent cardiomyocytes produce de novo ACh, which is critical in maintaining cardiac homeostasis. We report that this nonneuronal cholinergic system is also found in human cardiomyocytes, which expressed choline acetyltransferase (ChAT) and the vesicular acetylcholine transporter (VAChT). Furthermore, VAChT expression was increased 3- and 1.5-fold at the mRNA and protein level, respectively, in ventricular tissue from patients with heart failure, suggesting increased ACh secretion in disease. We used mice with genetic deletion of cardiomyocyte-specific VAChT or ChAT and mice overexpressing VAChT to test the functional significance of cholinergic signaling. Mice deficient for VAChT displayed an 8% decrease in fractional shortening and 13% decrease in ejection fraction compared with angiotensin II (Ang II)-treated control animals, suggesting enhanced ventricular dysfunction and pathologic remodeling in response to Ang II. Similar results were observed in ChAT-deficient mice. Conversely, no decline in ventricular function was observed in Ang II-treated VAChT overexpressors. Furthermore, the fibrotic area was significantly greater (P < 0.05) in Ang II-treated VAChT-deficient mice (3.61 ± 0.64%) compared with wild-type animals (2.24 ± 0.11%). In contrast, VAChT overexpressing mice did not display an increase in collagen deposition. Our results provide new insight into cholinergic regulation of cardiac function, suggesting that a compensatory increase in cardiomyocyte VAChT levels may help offset cardiac remodeling in heart failure.
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Affiliation(s)
- Ashbeel Roy
- *Robarts Research Institute, Department of Physiology and Pharmacology, Department of Medicine, and Department of Anatomy and Cell Biology, The University of Western Ontario, London, Ontario, Canada; Department of Physiology, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, Brazil; and Department of Physiology and Biophysics, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, Brazil
| | - Mouhamed Dakroub
- *Robarts Research Institute, Department of Physiology and Pharmacology, Department of Medicine, and Department of Anatomy and Cell Biology, The University of Western Ontario, London, Ontario, Canada; Department of Physiology, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, Brazil; and Department of Physiology and Biophysics, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, Brazil
| | - Geisa C S V Tezini
- *Robarts Research Institute, Department of Physiology and Pharmacology, Department of Medicine, and Department of Anatomy and Cell Biology, The University of Western Ontario, London, Ontario, Canada; Department of Physiology, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, Brazil; and Department of Physiology and Biophysics, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, Brazil
| | - Yin Liu
- *Robarts Research Institute, Department of Physiology and Pharmacology, Department of Medicine, and Department of Anatomy and Cell Biology, The University of Western Ontario, London, Ontario, Canada; Department of Physiology, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, Brazil; and Department of Physiology and Biophysics, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, Brazil
| | - Silvia Guatimosim
- *Robarts Research Institute, Department of Physiology and Pharmacology, Department of Medicine, and Department of Anatomy and Cell Biology, The University of Western Ontario, London, Ontario, Canada; Department of Physiology, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, Brazil; and Department of Physiology and Biophysics, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, Brazil
| | - Qingping Feng
- *Robarts Research Institute, Department of Physiology and Pharmacology, Department of Medicine, and Department of Anatomy and Cell Biology, The University of Western Ontario, London, Ontario, Canada; Department of Physiology, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, Brazil; and Department of Physiology and Biophysics, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, Brazil
| | - Helio C Salgado
- *Robarts Research Institute, Department of Physiology and Pharmacology, Department of Medicine, and Department of Anatomy and Cell Biology, The University of Western Ontario, London, Ontario, Canada; Department of Physiology, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, Brazil; and Department of Physiology and Biophysics, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, Brazil
| | - Vania F Prado
- *Robarts Research Institute, Department of Physiology and Pharmacology, Department of Medicine, and Department of Anatomy and Cell Biology, The University of Western Ontario, London, Ontario, Canada; Department of Physiology, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, Brazil; and Department of Physiology and Biophysics, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, Brazil
| | - Marco A M Prado
- *Robarts Research Institute, Department of Physiology and Pharmacology, Department of Medicine, and Department of Anatomy and Cell Biology, The University of Western Ontario, London, Ontario, Canada; Department of Physiology, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, Brazil; and Department of Physiology and Biophysics, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, Brazil
| | - Robert Gros
- *Robarts Research Institute, Department of Physiology and Pharmacology, Department of Medicine, and Department of Anatomy and Cell Biology, The University of Western Ontario, London, Ontario, Canada; Department of Physiology, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, Brazil; and Department of Physiology and Biophysics, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, Brazil
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5
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Identification of a mammalian vesicular polyamine transporter. Sci Rep 2014; 4:6836. [PMID: 25355561 PMCID: PMC4213795 DOI: 10.1038/srep06836] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2014] [Accepted: 10/10/2014] [Indexed: 01/11/2023] Open
Abstract
Spermine and spermidine act as neuromodulators upon binding to the extracellular site(s) of various ionotropic receptors, such as N-methyl-d-aspartate receptors. To gain access to the receptors, polyamines synthesized in neurons and astrocytes are stored in secretory vesicles and released upon depolarization. Although vesicular storage is mediated in an ATP-dependent, reserpine-sensitive fashion, the transporter responsible for this process remains unknown. SLC18B1 is the fourth member of the SLC18 transporter family, which includes vesicular monoamine transporters and vesicular acetylcholine transporter. Proteoliposomes containing purified human SLC18B1 protein actively transport spermine and spermidine by exchange of H(+). SLC18B1 protein is predominantly expressed in the hippocampus and is associated with vesicles in astrocytes. SLC18B1 gene knockdown decreased both SLC18B1 protein and spermine/spermidine contents in astrocytes. These results indicated that SLC18B1 encodes a vesicular polyamine transporter (VPAT).
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Anne C, Gasnier B. Vesicular neurotransmitter transporters: mechanistic aspects. CURRENT TOPICS IN MEMBRANES 2014; 73:149-74. [PMID: 24745982 DOI: 10.1016/b978-0-12-800223-0.00003-7] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
Secondary transporters driven by a V-type H⁺-ATPase accumulate nonpeptide neurotransmitters into synaptic vesicles. Distinct transporter families are involved depending on the neurotransmitter. Monoamines and acetylcholine on the one hand, and glutamate and ATP on the other hand, are accumulated by SLC18 and SLC17 transporters, respectively, which belong to the major facilitator superfamily (MFS). GABA and glycine accumulate through a common SLC32 transporter from the amino acid/polyamine/organocation (APC) superfamily. Although crystallographic structures are not yet available for any vesicular transporter, homology modeling studies of MFS-type vesicular transporters based on distantly related bacterial structures recently provided significant advances, such as the characterization of substrate-binding pockets or the identification of spatial clusters acting as hinge points during the alternating-access cycle. However, several basic issues, such as the ion stoichiometry of vesicular amino acid transporters, remain unsettled.
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Affiliation(s)
- Christine Anne
- Université Paris Descartes, Sorbonne Paris Cité, Centre National de la Recherche Scientifique, Unité Mixte de Recherche 8192, Centre Universitaire des Saints-Pères, Paris, France
| | - Bruno Gasnier
- Université Paris Descartes, Sorbonne Paris Cité, Centre National de la Recherche Scientifique, Unité Mixte de Recherche 8192, Centre Universitaire des Saints-Pères, Paris, France.
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Alexander SPH, Benson HE, Faccenda E, Pawson AJ, Sharman JL, Spedding M, Peters JA, Harmar AJ. The Concise Guide to PHARMACOLOGY 2013/14: transporters. Br J Pharmacol 2013; 170:1706-96. [PMID: 24528242 PMCID: PMC3892292 DOI: 10.1111/bph.12450] [Citation(s) in RCA: 120] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The Concise Guide to PHARMACOLOGY 2013/14 provides concise overviews of the key properties of over 2000 human drug targets with their pharmacology, plus links to an open access knowledgebase of drug targets and their ligands (www.guidetopharmacology.org), which provides more detailed views of target and ligand properties. The full contents can be found at http://onlinelibrary.wiley.com/doi/10.1111/bph.12444/full. Transporters are one of the seven major pharmacological targets into which the Guide is divided, with the others being G protein-coupled receptors, ligand-gated ion channels, ion channels, catalytic receptors, nuclear hormone receptors and enzymes. These are presented with nomenclature guidance and summary information on the best available pharmacological tools, alongside key references and suggestions for further reading. A new landscape format has easy to use tables comparing related targets. It is a condensed version of material contemporary to late 2013, which is presented in greater detail and constantly updated on the website www.guidetopharmacology.org, superseding data presented in previous Guides to Receptors and Channels. It is produced in conjunction with NC-IUPHAR and provides the official IUPHAR classification and nomenclature for human drug targets, where appropriate. It consolidates information previously curated and displayed separately in IUPHAR-DB and the Guide to Receptors and Channels, providing a permanent, citable, point-in-time record that will survive database updates.
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Affiliation(s)
- Stephen PH Alexander
- School of Life Sciences, University of Nottingham Medical SchoolNottingham, NG7 2UH, UK
| | - Helen E Benson
- The University/BHF Centre for Cardiovascular Science, University of EdinburghEdinburgh, EH16 4TJ, UK
| | - Elena Faccenda
- The University/BHF Centre for Cardiovascular Science, University of EdinburghEdinburgh, EH16 4TJ, UK
| | - Adam J Pawson
- The University/BHF Centre for Cardiovascular Science, University of EdinburghEdinburgh, EH16 4TJ, UK
| | - Joanna L Sharman
- The University/BHF Centre for Cardiovascular Science, University of EdinburghEdinburgh, EH16 4TJ, UK
| | | | - John A Peters
- Neuroscience Division, Medical Education Institute, Ninewells Hospital and Medical School, University of DundeeDundee, DD1 9SY, UK
| | - Anthony J Harmar
- The University/BHF Centre for Cardiovascular Science, University of EdinburghEdinburgh, EH16 4TJ, UK
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8
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Abstract
Acetylcholine, the first chemical to be identified as a neurotransmitter, is packed in synaptic vesicles by the activity of VAChT (vesicular acetylcholine transporter). A decrease in VAChT expression has been reported in a number of diseases, and this has consequences for the amount of acetylcholine loaded in synaptic vesicles as well as for neurotransmitter release. Several genetically modified mice targeting the VAChT gene have been generated, providing novel models to understand how changes in VAChT affect transmitter release. A surprising finding is that most cholinergic neurons in the brain also can express a second type of vesicular neurotransmitter transporter that allows these neurons to secrete two distinct neurotransmitters. Thus a given neuron can use two neurotransmitters to regulate different physiological functions. In addition, recent data indicate that non-neuronal cells can also express the machinery used to synthesize and release acetylcholine. Some of these cells rely on VAChT to secrete acetylcholine with potential physiological consequences in the periphery. Hence novel functions for the oldest neurotransmitter known are emerging with the potential to provide new targets for the treatment of several pathological conditions.
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Rocha-Resende C, Roy A, Resende R, Ladeira MS, Lara A, de Morais Gomes ER, Prado VF, Gros R, Guatimosim C, Prado MAM, Guatimosim S. Non-neuronal cholinergic machinery present in cardiomyocytes offsets hypertrophic signals. J Mol Cell Cardiol 2012; 53:206-16. [PMID: 22587993 DOI: 10.1016/j.yjmcc.2012.05.003] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/23/2012] [Revised: 04/17/2012] [Accepted: 05/03/2012] [Indexed: 12/19/2022]
Abstract
Recent work has provided compelling evidence that increased levels of acetylcholine (ACh) can be protective in heart failure, whereas reduced levels of ACh secretion can cause heart malfunction. Previous data show that cardiomyocytes themselves can actively secrete ACh, raising the question of whether this cardiomyocyte derived ACh may contribute to the protective effects of ACh in the heart. To address the functionality of this non-neuronal ACh machinery, we used cholinesterase inhibitors and a siRNA targeted to AChE (acetylcholinesterase) as a way to increase the availability of ACh secreted by cardiac cells. By using nitric oxide (NO) formation as a biological sensor for released ACh, we showed that cholinesterase inhibition increased NO levels in freshly isolated ventricular myocytes and that this effect was prevented by atropine, a muscarinic receptor antagonist, and by inhibition of ACh synthesis or vesicular storage. Functionally, cholinesterase inhibition prevented the hypertrophic effect as well as molecular changes and calcium transient alterations induced by adrenergic overstimulation in cardiomyocytes. Moreover, inhibition of ACh storage or atropine blunted the anti-hypertrophic action of cholinesterase inhibition. Altogether, our results show that cardiomyocytes possess functional cholinergic machinery that offsets deleterious effects of hyperadrenergic stimulation. In addition, we show that adrenergic stimulation upregulates expression levels of cholinergic components. We propose that this cardiomyocyte cholinergic signaling could amplify the protective effects of the parasympathetic nervous system in the heart and may counteract or partially neutralize hypertrophic adrenergic effects.
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Affiliation(s)
- Cibele Rocha-Resende
- Department of Physiology and Biophysics, Institute of Biological Sciences, Universidade Federal de Minas Gerais, Belo Horizonte, MG, CEP 31270-901, Brazil.
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10
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Khare P, Mulakaluri A, Parsons SM. Search for the acetylcholine and vesamicol binding sites in vesicular acetylcholine transporter: the region around the lumenal end of the transport channel. J Neurochem 2010; 115:984-93. [PMID: 20831599 DOI: 10.1111/j.1471-4159.2010.06990.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Vesicular acetylcholine transporter (VAChT; TC 2.A.1.2.13) mediates storage of acetylcholine (ACh) by synaptic vesicles. A three-dimensional homology model of VAChT is available, but the binding sites for ACh and the allosteric inhibitor (-)-trans-2-(4-phenylpiperidino)cyclohexanol (vesamicol) are unknown. In previous work, mutations of invariant W331 in the lumenal beginning of transmembrane helix VIII (TM VIII) of rat VAChT led to as much as ninefold loss in equilibrium affinity for ACh and no loss in affinity for vesamicol. The current work investigates the effects of additional mutations in and around W331 and the nearby lumenal end of the substrate transport channel. Mutants of human VAChT were expressed in the PC12(A123.7) cell line and characterized using radiolabeled ligands and filtration assays for binding and transport. Properties of a new and a repeat mutation in W331 are consistent with the original observations. Of 16 additional mutations in 13 other residues (Y60 in the beginning of lumenal Loop I/II, F231 in the lumenal end of TM V, W315, M316, K317, in the lumenal end of TM VII, M320, A321, W325, A330 in lumenal Loop VII/VIII, A334 in the lumenal beginning of TM VIII, and C388, C391, F392 in the lumenal beginning of TM X), only A334F impairs binding. This mutation decreases ACh and vesamicol equilibrium binding affinities by 14- and 4-fold, respectively. The current results, combined with previous results, demonstrate existence of a spatial cluster of residues close to vesicular lumen that decreases affinity for ACh and/or vesamicol when the cluster is mutated. The cluster is composed of invariant W331, highly conserved A334, and invariant F335 in TM VIII and invariant C391 in TM X. Different models for the locations of the ACh and vesamicol binding sites relative to this cluster are discussed.
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Affiliation(s)
- Parul Khare
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106-9510, USA
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11
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EmrE, a model for studying evolution and mechanism of ion-coupled transporters. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2009; 1794:748-62. [DOI: 10.1016/j.bbapap.2008.12.018] [Citation(s) in RCA: 130] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2008] [Revised: 12/16/2008] [Accepted: 12/17/2008] [Indexed: 11/23/2022]
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12
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Chaudhry FA, Edwards RH, Fonnum F. Vesicular neurotransmitter transporters as targets for endogenous and exogenous toxic substances. Annu Rev Pharmacol Toxicol 2008; 48:277-301. [PMID: 17883368 DOI: 10.1146/annurev.pharmtox.46.120604.141146] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Exocytotic release of neurotransmitters requires their accumulation inside preformed secretory vesicles. Distinct vesicular transport activities translocate classical transmitters into synaptic vesicles energized by a H+ electrochemical gradient (Delta(mu(H+))), with subtle but important differences in dependence on the electrical and chemical components. The vesicular transporters also interact with toxic compounds and drugs. They mediate neuroprotection by sequestering toxic compounds as well as neurotransmitters into vesicles, reducing their concentration in the cytosol where they may have detrimental effects. Both therapeutic agents and psychostimulants interfering with vesicular transport have yielded insight into the pathogenesis of psychiatric as well as neurodegenerative diseases. Thus, specific inhibitors have helped to characterize both the physiological role and mechanism of vesicular neurotransmitter transport.
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Affiliation(s)
- Farrukh A Chaudhry
- Centre for Molecular Biology and Neuroscience, The Biotechnology Centre of Oslo, University of Oslo, Oslo, Norway.
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13
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Chaudhry FA, Boulland JL, Jenstad M, Bredahl MKL, Edwards RH. Pharmacology of neurotransmitter transport into secretory vesicles. Handb Exp Pharmacol 2008:77-106. [PMID: 18064412 DOI: 10.1007/978-3-540-74805-2_4] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Many neuropsychiatric disorders appear to involve a disturbance of chemical neurotransmission, and the mechanism of available therapeutic agents supports this impression. Postsynaptic receptors have received considerable attention as drug targets, but some of the most successful agents influence presynaptic processes, in particular neurotransmitter reuptake. The pharmacological potential of many other presynaptic elements, and in particular the machinery responsible for loading transmitter into vesicles, has received only limited attention. The similarity of vesicular transporters to bacterial drug resistance proteins and the increasing evidence for regulation of vesicle filling and recycling suggest that the pharmacological potential of vesicular transporters has been underestimated. In this review, we discuss the pharmacological effects of psychostimulants and therapeutic agents on transmitter release.
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Affiliation(s)
- Farrukh A Chaudhry
- The Biotechnology Centre of Oslo, University of Oslo, 1125, Blindern, Oslo, 0317, Norway.
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