1
|
Hitt DM, Zwicker JD, Chao CK, Patel SA, Gerdes JM, Bridges RJ, Thompson CM. Inhibition of the Vesicular Glutamate Transporter (VGLUT) with Congo Red Analogs: New Binding Insights. Neurochem Res 2021; 46:494-503. [PMID: 33398639 DOI: 10.1007/s11064-020-03182-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Revised: 09/11/2020] [Accepted: 11/17/2020] [Indexed: 11/24/2022]
Abstract
The vesicular glutamate transporter (VGLUT) facilitates the uptake of glutamate (Glu) into neuronal vesicles. VGLUT has not yet been fully characterized pharmacologically but a body of work established that certain azo-dyes bearing two Glu isosteres via a linker were potent inhibitors. However, the distance between the isostere groups that convey potent inhibition has not been delineated. This report describes the synthesis and pharmacologic assessment of Congo Red analogs that contain one or two glutamate isostere or mimic groups; the latter varied in the interatomic distance and spacer properties to probe strategic binding interactions within VGLUT. The more potent inhibitors had two glutamate isosteres symmetrically linked to a central aromatic group and showed IC50 values ~ 0.3-2.0 μM at VGLUT. These compounds contained phenyl, diphenyl ether (PhOPh) or 1,2-diphenylethane as the linker connecting 4-aminonaphthalene sulfonic acid groups. A homology model for VGLUT2 using D-galactonate transporter (DgoT) to dock and identify R88, H199 and F219 as key protein interactions with Trypan Blue, Congo Red and selected potent analogs prepared and tested in this report.
Collapse
Affiliation(s)
- David M Hitt
- Department of Biomedical and Pharmaceutical Sciences, Center for Structural and Functional Neuroscience, College of Health Professions and Biomedical Sciences, University of Montana, Missoula, MT, 59812, USA.,Department of Chemistry, Carroll College, 1601 N Benton Ave., Helena, MT, 59625, USA
| | - Jeffery D Zwicker
- Department of Biomedical and Pharmaceutical Sciences, Center for Structural and Functional Neuroscience, College of Health Professions and Biomedical Sciences, University of Montana, Missoula, MT, 59812, USA.,Deciphera Pharmaceuticals, 643 Massachusetts St, Lawrence, KS, 66044, USA
| | - Chih-Kai Chao
- Department of Biomedical and Pharmaceutical Sciences, Center for Structural and Functional Neuroscience, College of Health Professions and Biomedical Sciences, University of Montana, Missoula, MT, 59812, USA
| | - Sarjubhai A Patel
- Department of Biomedical and Pharmaceutical Sciences, Center for Structural and Functional Neuroscience, College of Health Professions and Biomedical Sciences, University of Montana, Missoula, MT, 59812, USA
| | - John M Gerdes
- Department of Biomedical and Pharmaceutical Sciences, Center for Structural and Functional Neuroscience, College of Health Professions and Biomedical Sciences, University of Montana, Missoula, MT, 59812, USA
| | - Richard J Bridges
- Department of Biomedical and Pharmaceutical Sciences, Center for Structural and Functional Neuroscience, College of Health Professions and Biomedical Sciences, University of Montana, Missoula, MT, 59812, USA
| | - Charles M Thompson
- Department of Biomedical and Pharmaceutical Sciences, Center for Structural and Functional Neuroscience, College of Health Professions and Biomedical Sciences, University of Montana, Missoula, MT, 59812, USA.
| |
Collapse
|
2
|
Poirel O, Mamer LE, Herman MA, Arnulf-Kempcke M, Kervern M, Potier B, Miot S, Wang J, Favre-Besse FC, Brabet I, Laras Y, Bertrand HO, Acher F, Pin JP, Puel JL, Giros B, Epelbaum J, Rosenmund C, Dutar P, Daumas S, El Mestikawy S, Pietrancosta N. LSP5-2157 a new inhibitor of vesicular glutamate transporters. Neuropharmacology 2019; 164:107902. [PMID: 31811873 DOI: 10.1016/j.neuropharm.2019.107902] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2019] [Revised: 10/08/2019] [Accepted: 12/02/2019] [Indexed: 11/19/2022]
Abstract
Vesicular glutamate transporters (VGLUT1-3) mediate the uptake of glutamate into synaptic vesicles. VGLUTs are pivotal actors of excitatory transmission and of almost all brain functions. Their implication in various pathologies has been clearly documented. Despite their functional importance, the pharmacology of VGLUTs is limited to a few dyes such as Trypan Blue, Rose Bengal or Brilliant Yellow type. Here, we report the design and evaluation of new potent analogs based on Trypan Blue scaffold. Our best compound, named LSP5-2157, has an EC50 of 50 nM on glutamate vesicular uptake. Using a 3D homology model of VGLUT1 and docking experiments, we determined its putative binding subdomains within vesicular glutamate transporters and validated the structural requirement for VGLUT inhibition. To better estimate the specificity and potency of LSP5-2157, we also investigated its ability to block glutamatergic transmission in autaptic hippocampal cells. Neither glutamate receptors nor GABAergic transmission or transmission machinery were affected by LSP5-2157. Low doses of compound reversibly reduce glutamatergic neurotransmission in hippocampal autpases. LSP5-2157 had a low and depressing effect on synaptic efficacy in hippocampal slice. Furthermore, LSP5-2157 had no effect on NMDA-R- mediated fEPSP but reduce synaptic plasticity induced by 3 trains of 100 Hz. Finally, LSP5-2157 had the capacity to inhibit VGLUT3-dependent auditory synaptic transmission in the guinea pig cochlea. In this model, it abolished the compound action potential of auditory nerve at high concentration showing the limited permeation of LSP5-2157 in an in-vivo model. In summary, the new ligand LSP5-2157, has a high affinity and specificity for VGLUTs and shows some permeability in isolated neuron, tissue preparations or in vivo in the auditory system. These findings broaden the field of VGLUTs inhibitors and open the way to their use to assess glutamatergic functions in vitro and in vivo.
Collapse
Affiliation(s)
- Odile Poirel
- Sorbonne Université, INSERM, CNRS, Neurosciences Paris Seine - Institut de Biologie Paris Seine (NPS - IBPS), 75005, Paris, France
| | - Lauren E Mamer
- Institut für Neurophysiologie, Charité Universitätsmedizin, Charitéplatz 1, 10117, Berlin, Germany; The Ohio State University College of Medicine, The Ohio State University, Columbus, OH, 43210, USA
| | - Melissa A Herman
- Institut für Neurophysiologie, Charité Universitätsmedizin, Charitéplatz 1, 10117, Berlin, Germany
| | - Marie Arnulf-Kempcke
- Centre de Psychiatrie et Neurosciences, Université Paris Descartes, Sorbonne Paris Cité, UMR 894, Paris, 75014, France
| | - Myriam Kervern
- Centre de Psychiatrie et Neurosciences, Université Paris Descartes, Sorbonne Paris Cité, UMR 894, Paris, 75014, France
| | - Brigitte Potier
- Centre de Psychiatrie et Neurosciences, Université Paris Descartes, Sorbonne Paris Cité, UMR 894, Paris, 75014, France; Present address: Laboratoire Aimée Cotton, CNRS, Université Paris-Sud, ENS Paris-Saclay, 91405, Orsay, France
| | - Stephanie Miot
- Sorbonne Université, INSERM, CNRS, Neurosciences Paris Seine - Institut de Biologie Paris Seine (NPS - IBPS), 75005, Paris, France; Institute for Neuroscience Montpellier (INM), INSERM U1051, Université Montpellier, 34091, Montpellier, France
| | - Jing Wang
- Institute for Neuroscience Montpellier (INM), INSERM U1051, Université Montpellier, 34091, Montpellier, France
| | | | - Isabelle Brabet
- Institut de Génomique Fonctionnelle UMR 5203 CNRS - U 1191 INSERM - Univ. Montpellier, 30094, Montpellier, France
| | - Younès Laras
- LCBPT, Université Paris Descartes, Sorbonne Paris Cité, UMR 8601, CNRS, Paris, 75006, France
| | - Hugues-Olivier Bertrand
- BIOVIA, Dassault Systèmes, 10 rue Marcel Dassault, CS 40501, 78946, Velizy-Villacoublay Cedex, France
| | - Francine Acher
- LCBPT, Université Paris Descartes, Sorbonne Paris Cité, UMR 8601, CNRS, Paris, 75006, France
| | - Jean-Philippe Pin
- Institut de Génomique Fonctionnelle UMR 5203 CNRS - U 1191 INSERM - Univ. Montpellier, 30094, Montpellier, France
| | - Jean-Luc Puel
- Institute for Neuroscience Montpellier (INM), INSERM U1051, Université Montpellier, 34091, Montpellier, France
| | - Bruno Giros
- Sorbonne Université, INSERM, CNRS, Neurosciences Paris Seine - Institut de Biologie Paris Seine (NPS - IBPS), 75005, Paris, France; Douglas Hospital Research Center, Department of Psychiatry, McGill University, 6875, boulevard Lasalle Verdun, QC, Canada
| | - Jacques Epelbaum
- Centre de Psychiatrie et Neurosciences, Université Paris Descartes, Sorbonne Paris Cité, UMR 894, Paris, 75014, France
| | - Christian Rosenmund
- Institut für Neurophysiologie, Charité Universitätsmedizin, Charitéplatz 1, 10117, Berlin, Germany
| | - Patrick Dutar
- Centre de Psychiatrie et Neurosciences, Université Paris Descartes, Sorbonne Paris Cité, UMR 894, Paris, 75014, France; Present address: Laboratoire Aimée Cotton, CNRS, Université Paris-Sud, ENS Paris-Saclay, 91405, Orsay, France
| | - Stephanie Daumas
- Sorbonne Université, INSERM, CNRS, Neurosciences Paris Seine - Institut de Biologie Paris Seine (NPS - IBPS), 75005, Paris, France
| | - Salah El Mestikawy
- Sorbonne Université, INSERM, CNRS, Neurosciences Paris Seine - Institut de Biologie Paris Seine (NPS - IBPS), 75005, Paris, France; Douglas Hospital Research Center, Department of Psychiatry, McGill University, 6875, boulevard Lasalle Verdun, QC, Canada.
| | - Nicolas Pietrancosta
- Sorbonne Université, INSERM, CNRS, Neurosciences Paris Seine - Institut de Biologie Paris Seine (NPS - IBPS), 75005, Paris, France; LCBPT, Université Paris Descartes, Sorbonne Paris Cité, UMR 8601, CNRS, Paris, 75006, France; Sorbonne Université, École normale supérieure, PSL University, CNRS, Laboratoire des Biomolécules, LBM, 75005 Paris, France.
| |
Collapse
|
3
|
McKenzie C, Spanova M, Johnson A, Kainrath S, Zheden V, Sitte HH, Janovjak H. Isolation of synaptic vesicles from genetically engineered cultured neurons. J Neurosci Methods 2018; 312:114-121. [PMID: 30496761 DOI: 10.1016/j.jneumeth.2018.11.018] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2018] [Revised: 11/19/2018] [Accepted: 11/20/2018] [Indexed: 12/18/2022]
Abstract
BACKGROUND Synaptic vesicles (SVs) are an integral part of the neurotransmission machinery, and isolation of SVs from their host neuron is necessary to reveal their most fundamental biochemical and functional properties in in vitro assays. Isolated SVs from neurons that have been genetically engineered, e.g. to introduce genetically encoded indicators, are not readily available but would permit new insights into SV structure and function. Furthermore, it is unclear if cultured neurons can provide sufficient starting material for SV isolation procedures. NEW METHOD Here, we demonstrate an efficient ex vivo procedure to obtain functional SVs from cultured rat cortical neurons after genetic engineering with a lentivirus. RESULTS We show that ∼108 plated cortical neurons allow isolation of suitable SV amounts for functional analysis and imaging. We found that SVs isolated from cultured neurons have neurotransmitter uptake comparable to that of SVs isolated from intact cortex. Using total internal reflection fluorescence (TIRF) microscopy, we visualized an exogenous SV-targeted marker protein and demonstrated the high efficiency of SV modification. COMPARISON WITH EXISTING METHODS Obtaining SVs from genetically engineered neurons currently generally requires the availability of transgenic animals, which is constrained by technical (e.g. cost and time) and biological (e.g. developmental defects and lethality) limitations. CONCLUSIONS These results demonstrate the modification and isolation of functional SVs using cultured neurons and viral transduction. The ability to readily obtain SVs from genetically engineered neurons will permit linking in situ studies to in vitro experiments in a variety of genetic contexts.
Collapse
Affiliation(s)
- Catherine McKenzie
- Institute of Science and Technology Austria (IST Austria), Am Campus 1, 3400 Klosterneuburg, Austria
| | - Miroslava Spanova
- Institute of Science and Technology Austria (IST Austria), Am Campus 1, 3400 Klosterneuburg, Austria
| | - Alexander Johnson
- Institute of Science and Technology Austria (IST Austria), Am Campus 1, 3400 Klosterneuburg, Austria
| | - Stephanie Kainrath
- Institute of Science and Technology Austria (IST Austria), Am Campus 1, 3400 Klosterneuburg, Austria
| | - Vanessa Zheden
- Institute of Science and Technology Austria (IST Austria), Am Campus 1, 3400 Klosterneuburg, Austria
| | - Harald H Sitte
- Medical University of Vienna, Center for Physiology and Pharmacology, Institute of Pharmacology, Waehringerstrasse 13A, 1090, Vienna, Austria
| | - Harald Janovjak
- Institute of Science and Technology Austria (IST Austria), Am Campus 1, 3400 Klosterneuburg, Austria; Australian Regenerative Medicine Institute (ARMI), Faculty of Medicine, Nursing and Health Sciences, Monash University, 15 Innovation Walk, Clayton, Melbourne, VIC 3800, Australia; European Molecular Biology Laboratory Australia (EMBL Australia), Monash University, 15 Innovation Walk, Clayton, Melbourne, VIC 3800, Australia.
| |
Collapse
|
4
|
Kehrl J, Althaus JC, Showalter HD, Rudzinski DM, Sutton MA, Ueda T. Vesicular Glutamate Transporter Inhibitors: Structurally Modified Brilliant Yellow Analogs. Neurochem Res 2017; 42:1823-1832. [DOI: 10.1007/s11064-017-2198-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2016] [Revised: 01/27/2017] [Accepted: 01/30/2017] [Indexed: 12/22/2022]
|
5
|
3-aminoglutarate is a “silent” false transmitter for glutamate neurons. Neuropharmacology 2015; 97:436-46. [DOI: 10.1016/j.neuropharm.2015.05.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2015] [Revised: 04/25/2015] [Accepted: 05/08/2015] [Indexed: 11/27/2022]
|
6
|
Favre-Besse FC, Poirel O, Bersot T, Kim-Grellier E, Daumas S, El Mestikawy S, Acher FC, Pietrancosta N. Design, synthesis and biological evaluation of small-azo-dyes as potent Vesicular Glutamate Transporters inhibitors. Eur J Med Chem 2014; 78:236-47. [PMID: 24686010 DOI: 10.1016/j.ejmech.2014.03.056] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2013] [Revised: 03/04/2014] [Accepted: 03/17/2014] [Indexed: 12/01/2022]
Abstract
Vesicular Glutamate Transporters (VGLUTs) allow the loading of presynapic glutamate vesicles and thus play a critical role in glutamatergic synaptic transmission. VGLUTs have proved to be involved in several major neuropathologies and directly correlated to clinical dementia in Alzheimer and Parkinson's disease. Accordingly VGLUT represent a key biological target or biomarker for neuropathology treatment or diagnostic. Yet, despite the pivotal role of VGLUTs, their pharmacology appears quite limited. Known competitive inhibitors are restricted to some dyes as Trypan Blue (TB) and glutamate mimics. This lack of pharmacological tools has heavily hampered VGLUT investigations. Here we report a rapid access to small molecules that combine benefits of TB and dicarboxylic quinolines (DCQs). Their ability to block vesicular glutamate uptake was evaluated. Several compounds displayed low micromolar inhibitory potency when size related compounds are thirty to forty times less potent (i.e. DCQ). We then confirmed the VGLUT selectivity by measuring the effect of the series on vesicular monoamine transport and on metabotropic glutamate receptor activity. These inhibitors are synthesized in only two steps and count among the best pharmacological tools for VGLUTs studies.
Collapse
Affiliation(s)
- Franck-Cyril Favre-Besse
- Laboratoire de Chimie et Biochimie Pharmacologiques et Toxicologiques, UMR8601 CNRS, Université Paris Descartes, Sorbonne Paris Cité, 45 rue des Saints-Pères, 75270 Paris 06, France
| | - Odile Poirel
- Institut National de la Santé et de la Recherche Médicale (INSERM), U952, Université Pierre et Marie Curie, 9 quai Saint Bernard, 75005 Paris, France; Centre National de la Recherche Scientifique (CNRS) UMR 7224, 9 quai Saint Bernard, 75005 Paris, France; Université Pierre et Marie Curie (UPMC) Paris 06, Pathophysiology of Central Nervous System Disorders, 9 quai Saint Bernard, 75005 Paris, France
| | - Tiphaine Bersot
- Institut National de la Santé et de la Recherche Médicale (INSERM), U952, Université Pierre et Marie Curie, 9 quai Saint Bernard, 75005 Paris, France; Centre National de la Recherche Scientifique (CNRS) UMR 7224, 9 quai Saint Bernard, 75005 Paris, France; Université Pierre et Marie Curie (UPMC) Paris 06, Pathophysiology of Central Nervous System Disorders, 9 quai Saint Bernard, 75005 Paris, France
| | - Elodie Kim-Grellier
- Institut National de la Santé et de la Recherche Médicale (INSERM), U952, Université Pierre et Marie Curie, 9 quai Saint Bernard, 75005 Paris, France; Centre National de la Recherche Scientifique (CNRS) UMR 7224, 9 quai Saint Bernard, 75005 Paris, France; Université Pierre et Marie Curie (UPMC) Paris 06, Pathophysiology of Central Nervous System Disorders, 9 quai Saint Bernard, 75005 Paris, France
| | - Stephanie Daumas
- Institut National de la Santé et de la Recherche Médicale (INSERM), U952, Université Pierre et Marie Curie, 9 quai Saint Bernard, 75005 Paris, France; Centre National de la Recherche Scientifique (CNRS) UMR 7224, 9 quai Saint Bernard, 75005 Paris, France; Université Pierre et Marie Curie (UPMC) Paris 06, Pathophysiology of Central Nervous System Disorders, 9 quai Saint Bernard, 75005 Paris, France
| | - Salah El Mestikawy
- Institut National de la Santé et de la Recherche Médicale (INSERM), U952, Université Pierre et Marie Curie, 9 quai Saint Bernard, 75005 Paris, France; Centre National de la Recherche Scientifique (CNRS) UMR 7224, 9 quai Saint Bernard, 75005 Paris, France; Université Pierre et Marie Curie (UPMC) Paris 06, Pathophysiology of Central Nervous System Disorders, 9 quai Saint Bernard, 75005 Paris, France; Douglas Hospital Research Center, Department of Psychiatry, McGill University, 6875 boulevard Lasalle Verdun, QC, Canada
| | - Francine C Acher
- Laboratoire de Chimie et Biochimie Pharmacologiques et Toxicologiques, UMR8601 CNRS, Université Paris Descartes, Sorbonne Paris Cité, 45 rue des Saints-Pères, 75270 Paris 06, France.
| | - Nicolas Pietrancosta
- Laboratoire de Chimie et Biochimie Pharmacologiques et Toxicologiques, UMR8601 CNRS, Université Paris Descartes, Sorbonne Paris Cité, 45 rue des Saints-Pères, 75270 Paris 06, France.
| |
Collapse
|
7
|
Tamura Y, Ogita K, Ueda T. A new VGLUT-specific potent inhibitor: pharmacophore of Brilliant Yellow. Neurochem Res 2014; 39:117-28. [PMID: 24248859 PMCID: PMC4025951 DOI: 10.1007/s11064-013-1196-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2013] [Revised: 11/05/2013] [Accepted: 11/07/2013] [Indexed: 10/26/2022]
Abstract
The increased concentration of glutamate in synaptic vesicles, mediated by the vesicular glutamate transporter (VGLUT), is an initial vital step in glutamate synaptic transmission. Evidence indicates that aberrant overexpression of VGLUT is involved in certain pathophysiologies of the central nervous system. VGLUT is subject to inhibition by various types of agents. The most potent VGLUT-specific inhibitor currently known is Trypan Blue, which is highly charged, hence membrane-impermeable. We have sought a potent, VGLUT-specific agent amenable to easy modification to a membrane-permeable analog. We provide evidence that Brilliant Yellow exhibits potent, VGLUT-specific inhibition, with a Ki value of 12 nM. Based upon structure-activity relationship studies and molecular modeling, we have defined the potent inhibitory pharmacophore of Brilliant Yellow. This study provides new insight into development of a membrane-permeable agent to lead to specific blockade, with high potency, of accumulation of glutamate into synaptic vesicles in neurons.
Collapse
Affiliation(s)
- Yutaka Tamura
- Molecular and Behavioral Neuroscience Institute, Medical School, The University of Michigan, 109 Zina Pitcher Place, Ann Arbor, Michigan 48109-2200, USA
| | - Kiyokazu Ogita
- Molecular and Behavioral Neuroscience Institute, Medical School, The University of Michigan, 109 Zina Pitcher Place, Ann Arbor, Michigan 48109-2200, USA
| | - Tetsufumi Ueda
- Molecular and Behavioral Neuroscience Institute, Medical School, The University of Michigan, 109 Zina Pitcher Place, Ann Arbor, Michigan 48109-2200, USA
- Department of Pharmacology, Medical School, The University of Michigan, Ann Arbor, Michigan 48109, USA
- Department of Psychiatry, Medical School, The University of Michigan, Ann Arbor, Michigan 48109, USA
| |
Collapse
|
8
|
Takeda K, Ishida A, Takahashi K, Ueda T. Synaptic vesicles are capable of synthesizing the VGLUT substrate glutamate from α-ketoglutarate for vesicular loading. J Neurochem 2012; 121:184-96. [PMID: 22309504 DOI: 10.1111/j.1471-4159.2012.07684.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Synaptic vesicle loading of glutamate is a pivotal step in glutamate synaptic transmission. The molecular machinery responsible for this step is comprised of v-type proton-pump ATPase and a vesicular glutamate transporter. Recent evidence indicates that synaptic vesicles are endowed with glycolytic ATP-synthesizing enzymes, providing energy for immediate use by vesicle-bound proton-pump ATPase. In this study, we provide evidence that synaptic vesicles are also capable of synthesizing the vesicular glutamate transporter substrate glutamate, from α-ketoglutarate and l-aspartate (as the amino group donor); glutamate thus produced is taken up into vesicles. We also report a finding that α-ketoglutarate-derived glutamate uptake into synaptic vesicles and aspartate aminotransferase are inhibited by 2,3-pyrazinedicarboxylate. Evidence is given that this is a selective inhibitor for aspartate aminotransferase. These observations provide insight into understanding the nerve endings' mechanism for high efficiency in glutamate transmission. Finding this inhibitor may have implications for further experimentation on the role of α-ketoglutarate-derived glutamate in glutamate transmission.
Collapse
Affiliation(s)
- Kouji Takeda
- Molecular & Behavioral Neuroscience Institute, Medical School, The University of Michigan, Ann Arbor, Michigan, USA
| | | | | | | |
Collapse
|
9
|
Xue Y, Liao SF, Strickland JR, Boling JA, Matthews JC. Bovine neuronal vesicular glutamate transporter activity is inhibited by ergovaline and other ergopeptines. J Dairy Sci 2011; 94:3331-41. [PMID: 21700019 DOI: 10.3168/jds.2010-3612] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2010] [Accepted: 03/12/2011] [Indexed: 11/19/2022]
Abstract
l-Glutamate (Glu) is a major excitatory neurotransmitter responsible for neurotransmission in the vertebrate central nervous system. Vesicular Glu transporters VGLUT1 and VGLUT2 concentrate (50mM) Glu [Michaelis constant (measuring affinity), or K(m),=1 to 4mM] into synaptic vesicles (SV) for subsequent release into the synaptic cleft of glutamatergic neurons. Vesicular Glu transporter activity is dependent on vacuolar H(+)-ATPase function. Previous research has shown that ergopeptines contained in endophyte-infected tall fescue interact with dopaminergic and serotoninergic receptors, thereby affecting physiology regulated by these neuron types. To test the hypothesis that ergopeptine alkaloids inhibit VGLUT activity of bovine cerebral SV, SV were isolated from cerebral tissue of Angus-cross steers that were naive to ergot alkaloids. Immunoblot analysis validated the enrichment of VGLUT1, VGLUT2, synaptophysin 1, and vacuolar H(+)-ATPase in purified SV. Glutamate uptake assays demonstrated the dependence of SV VGLUT-like activity on the presence of ATP, H(+)-gradients, and H(+)-ATPase function. The effect of ergopeptines on VGLUT activity was evaluated by ANOVA. Inhibitory competition (IC(50)) experiments revealed that VGLUT-mediated Glu uptake (n=9) was inhibited by ergopeptine alkaloids: bromocriptine (2.83±0.59μM)<ergotamine (20.5±2.77μM)<ergocornine (114±23.1μM)<ergovaline (137±6.55μM). Subsequent ergovaline kinetic inhibition analysis (n=9; Glu=0.05, 0.10, 0.50, 1, 2, 4, 5mM) demonstrated no change in apparent K(m). However, the maximum reaction rate (V(max)) of Glu uptake was decreased when evaluated in the presence of 50, 100, and 200μM ergovaline, suggesting that ergovaline inhibited SV VGLUT activity through a noncompetitive mechanism. The findings of this study suggest cattle with fescue toxicosis may have a decreased glutamatergic neurotransmission capacity due to consumption of ergopeptine alkaloids.
Collapse
Affiliation(s)
- Y Xue
- Department of Animal and Food Sciences, University of Kentucky, Lexington 40546, USA
| | | | | | | | | |
Collapse
|
10
|
Ahmed SK, Etoga JLG, Patel SA, Bridges RJ, Thompson CM. Use of the hydantoin isostere to produce inhibitors showing selectivity toward the vesicular glutamate transporter versus the obligate exchange transporter system x(c)(-). Bioorg Med Chem Lett 2011; 21:4358-62. [PMID: 21669531 DOI: 10.1016/j.bmcl.2011.05.018] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2011] [Revised: 05/04/2011] [Accepted: 05/06/2011] [Indexed: 12/20/2022]
Abstract
Evidence was acquired prior to suggest that the vesicular glutamate transporter (VGLUT) but not other glutamate transporters were inhibited by structures containing a weakly basic α-amino group. To test this hypothesis, a series of analogs using a hydantoin (pK(a)∼9.1) isostere were synthesized and analyzed as inhibitors of VGLUT and the obligate cystine-glutamate transporter (system x(c)(-)). Of the hydantoin analogs tested, a thiophene-5-carboxaldehyde analog 2l and a bis-hydantoin 4b were relatively strong inhibitors of VGLUT reducing uptake to less than 6% of control at 5mM but few inhibited system x(c)(-) greater than 50% of control. The benzene-2,4-disulfonic acid analog 2b and p-diaminobenzene analog 2e were also good hydantoin-based inhibitors of VGLUT reducing uptake by 11% and 23% of control, respectively, but neither analog was effective as a system x(c)(-) inhibitor. In sum, a hydantoin isostere adds the requisite chemical properties needed to produce selective inhibitors of VGLUT.
Collapse
Affiliation(s)
- S Kaleem Ahmed
- Core Laboratory for Neuromolecular Production, Department of Biomedical and Pharmaceutical Sciences, The University of Montana, Missoula, MT 59812, USA
| | | | | | | | | |
Collapse
|
11
|
Pietrancosta N, Kessler A, Favre-Besse FC, Triballeau N, Quentin T, Giros B, El Mestikawy S, Acher FC. Rose Bengal analogs and vesicular glutamate transporters (VGLUTs). Bioorg Med Chem 2010; 18:6922-33. [PMID: 20708942 DOI: 10.1016/j.bmc.2010.06.069] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2010] [Revised: 06/21/2010] [Accepted: 06/21/2010] [Indexed: 10/19/2022]
Abstract
Vesicular glutamate transporters (VGLUTs) allow the loading of presynaptic glutamate vesicles and thus play a critical role in glutamatergic synaptic transmission. Rose Bengal (RB) is the most potent known VGLUT inhibitor (Ki 25 nM); therefore we designed, synthesized and tested in brain preparations, a series of analogs based on this scaffold. We showed that among the two tautomers of RB, the carboxylic and not the lactonic form is active against VGLUTs and generated a pharmacophore model to determine the minimal structure requirements. We also tested RB specificity in other neurotransmitter uptake systems. RB proved to potently inhibit VMAT (Ki 64 nM) but weakly VACHT (Ki>9.7 microM) and may be a useful tool in glutamate/acetylcholine co-transmission studies.
Collapse
Affiliation(s)
- Nicolas Pietrancosta
- Laboratoire de Chimie et Biochimie Pharmacologiques et Toxicologiques, UMR8601 CNRS, Université Paris Descartes, 45 rue des Saints-Pères, 75270 Paris 06, France
| | | | | | | | | | | | | | | |
Collapse
|
12
|
Conformationally-restricted amino acid analogues bearing a distal sulfonic acid show selective inhibition of system x(c)(-) over the vesicular glutamate transporter. Bioorg Med Chem Lett 2009; 20:2680-3. [PMID: 20303751 DOI: 10.1016/j.bmcl.2009.10.020] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2009] [Revised: 10/05/2009] [Accepted: 10/05/2009] [Indexed: 11/22/2022]
Abstract
A panel of amino acid analogs and conformationally-restricted amino acids bearing a sulfonic acid were synthesized and tested for their ability to preferentially inhibit the obligate cysteine-glutamate transporter system x(c)(-) versus the vesicular glutamate transporter (VGLUT). Several promising candidate molecules were identified: R/S-4-[4'-carboxyphenyl]-phenylglycine, a biphenyl substituted analog of 4-carboxyphenylglycine and 2-thiopheneglycine-5-sulfonic acid both of which reduced glutamate uptake at system x(c)(-) by 70-75% while having modest to no effect on glutamate uptake at VGLUT.
Collapse
|
13
|
Synaptic vesicle-bound pyruvate kinase can support vesicular glutamate uptake. Neurochem Res 2008; 34:807-18. [PMID: 18751889 DOI: 10.1007/s11064-008-9833-3] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2008] [Accepted: 08/07/2008] [Indexed: 10/21/2022]
Abstract
Glucose metabolism is essential for normal brain function and plays a vital role in synaptic transmission. Recent evidence suggests that ATP synthesized locally by glycolysis, particularly via glyceraldehyde 3-phosphate dehydrogenase/3-phosphoglycerate kinase, is critical for synaptic transmission. We present evidence that ATP generated by synaptic vesicle-associated pyruvate kinase is harnessed to transport glutamate into synaptic vesicles. Isolated synaptic vesicles incorporated [(3)H]glutamate in the presence of phosphoenolpyruvate (PEP) and ADP. Pyruvate kinase activators and inhibitors stimulated and reduced PEP/ADP-dependent glutamate uptake, respectively. Membrane potential was also formed in the presence of pyruvate kinase activators. "ATP-trapping" experiments using hexokinase and glucose suggest that ATP produced by vesicle-associated pyruvate kinase is more readily used than exogenously added ATP. Other neurotransmitters such as GABA, dopamine, and serotonin were also taken up into crude synaptic vesicles in a PEP/ADP-dependent manner. The possibility that ATP locally generated by glycolysis supports vesicular accumulation of neurotransmitters is discussed.
Collapse
|
14
|
Ogita K, Hirata K, Bole DG, Yoshida S, Tamura Y, Leckenby AM, Ueda T. Inhibition of vesicular glutamate storage and exocytotic release by Rose Bengal. J Neurochem 2008. [DOI: 10.1046/j.1471-4159.2001.00200.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
|
15
|
Winter HC, Ueda T. The glutamate uptake system in presynaptic vesicles: further characterization of structural requirements for inhibitors and substrates. Neurochem Res 2007; 33:223-31. [PMID: 17940888 DOI: 10.1007/s11064-007-9493-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2007] [Accepted: 08/28/2007] [Indexed: 12/01/2022]
Abstract
Noncyclic fluorine-substituted and cyclic analogs of glutamic acid were tested for their ability to inhibit glutamate uptake in isolated bovine presynaptic vesicles, in order to assess the specific structural requirements of the glutamate translocation system in the vesicle membrane. Cyclic analogs that permitted close interaction between the positive and negative charges of the glutamate molecule were effective inhibitors; maximum inhibitory potency was observed with L-trans-1-aminocyclopentane-1,3-dicarboxylic acid (L-t-ACPD), while D-t-ACPD was less active. Analogs with a larger or smaller ring (as in trans-1-aminocyclohexane-1,3-dicarboxylic acid or trans-1-aminocyclobutane-1,3-dicarboxylic acid) were also inhibitory, but somewhat less so. trans-ACPD was also taken up by the vesicles with a time course and ATP dependence similar to uptake of glutamate, and this uptake was inhibited by glutamate. The K(m) value for t-ACPD uptake was similar to its K(i) for inhibition of glutamate uptake, while its rate of uptake was lower than that of glutamate. Fluorine-substituted noncyclic analogs with substitutions at the 4-carbon were less effective than glutamic acid itself, although 4,4-difluoroglutamic acid was equal in activity to the unsubstituted compound. Inhibition by these derivatives appeared to be competitive in nature, and they probably were also transported by the vesicle uptake system.
Collapse
Affiliation(s)
- Harry C Winter
- Molecular and Behavioral Neuroscience Institute, The University of Michigan Medical School, 109 Zina Pitcher Place, Ann Arbor, MI 48109-2200, USA
| | | |
Collapse
|
16
|
Patel SA, Nagy JO, Bolstad ED, Gerdes JM, Thompson CM. Tetrapeptide inhibitors of the glutamate vesicular transporter (VGLUT). Bioorg Med Chem Lett 2007; 17:5125-8. [PMID: 17662605 PMCID: PMC2001293 DOI: 10.1016/j.bmcl.2007.07.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2007] [Revised: 07/01/2007] [Accepted: 07/03/2007] [Indexed: 11/25/2022]
Abstract
Quinoline-2,4-dicarboxylic acids (QDCs) bearing lipophilic substituents in the 6- or 7-position were shown to be inhibitors of the glutamate vesicular transporter (VGLUT). Using the arrangement of the QDC lipophilic substituents as a template, libraries of X(1)X(2)EF and X(1)X(2)EW tetrapeptides were synthesized and tested as VGLUT inhibitors. The peptides QIEW and WNEF were found to be the most potent. Further stereochemical deconvolution of these two peptides showed dQlIdElW to be the best inhibitor (K(i)=828+/-252 microM). Modeling and overlay of the tetrapeptide inhibitors with the existing pharmacophore showed that H-bonding and lipophilic residues are important for VGLUT binding.
Collapse
Affiliation(s)
- Sarjubhai A Patel
- Center for Structural and Functional Neuroscience, Department of Biomedical and Pharmaceutical Sciences, The University of Montana, Missoula, MT 59812, USA
| | | | | | | | | |
Collapse
|
17
|
Goracke-Postle CJ, Overland AC, Riedl MS, Stone LS, Fairbanks CA. Potassium- and capsaicin-induced release of agmatine from spinal nerve terminals. J Neurochem 2007; 102:1738-1748. [PMID: 17539920 DOI: 10.1111/j.1471-4159.2007.04647.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Agmatine (decarboxylated arginine) was originally identified in the CNS as an imidazoline receptor ligand. Further studies demonstrated that agmatine antagonizes NMDA receptors and inhibits nitric oxide synthase. Intrathecally administered agmatine inhibits opioid tolerance and hyperalgesia evoked by inflammation, nerve injury, and intrathecally administered NMDA. These actions suggest an anti-glutamatergic role for agmatine in the spinal cord. We have previously reported that radiolabeled agmatine is transported into spinal synaptosomes in an energy- and temperature-dependent manner. In the present study, we demonstrate that agmatine is releasable from purified spinal nerve terminals upon depolarization. When exposed to either elevated potassium or capsaicin, tritiated agmatine (but not its precursor L-arginine or its metabolite putrescine) is released in a calcium-dependent manner. Control experiments confirmed that the observed release was specific to depolarization and not due to permeabilization of or degradation of synaptosomes. That capsaicin-evoked stimulation results in agmatine release implicates the participation of primary afferent nerve terminals. Radiolabeled agmatine also accumulates in purified spinal synaptosomal vesicles in a temperature-dependent manner, suggesting that the source of releasable agmatine may be vesicular in origin. These results support the proposal that agmatine may serve as a spinal neuromodulator involved in pain processing.
Collapse
Affiliation(s)
- Cory J Goracke-Postle
- Department of Pharmaceutics, University of Minnesota, Minneapolis, Minnesota, USADepartment of Pharmacology, University of Minnesota, Minneapolis, Minnesota, USADepartment of Neuroscience, University of Minnesota, Minneapolis, Minnesota, USADepartment of Anesthesiology, University of Minnesota, Minneapolis, Minnesota, USACenter for Pain Research, University of Minnesota, Minneapolis, Minnesota, USA
| | - Aaron C Overland
- Department of Pharmaceutics, University of Minnesota, Minneapolis, Minnesota, USADepartment of Pharmacology, University of Minnesota, Minneapolis, Minnesota, USADepartment of Neuroscience, University of Minnesota, Minneapolis, Minnesota, USADepartment of Anesthesiology, University of Minnesota, Minneapolis, Minnesota, USACenter for Pain Research, University of Minnesota, Minneapolis, Minnesota, USA
| | - Maureen S Riedl
- Department of Pharmaceutics, University of Minnesota, Minneapolis, Minnesota, USADepartment of Pharmacology, University of Minnesota, Minneapolis, Minnesota, USADepartment of Neuroscience, University of Minnesota, Minneapolis, Minnesota, USADepartment of Anesthesiology, University of Minnesota, Minneapolis, Minnesota, USACenter for Pain Research, University of Minnesota, Minneapolis, Minnesota, USA
| | - Laura S Stone
- Department of Pharmaceutics, University of Minnesota, Minneapolis, Minnesota, USADepartment of Pharmacology, University of Minnesota, Minneapolis, Minnesota, USADepartment of Neuroscience, University of Minnesota, Minneapolis, Minnesota, USADepartment of Anesthesiology, University of Minnesota, Minneapolis, Minnesota, USACenter for Pain Research, University of Minnesota, Minneapolis, Minnesota, USA
| | - Carolyn A Fairbanks
- Department of Pharmaceutics, University of Minnesota, Minneapolis, Minnesota, USADepartment of Pharmacology, University of Minnesota, Minneapolis, Minnesota, USADepartment of Neuroscience, University of Minnesota, Minneapolis, Minnesota, USADepartment of Anesthesiology, University of Minnesota, Minneapolis, Minnesota, USACenter for Pain Research, University of Minnesota, Minneapolis, Minnesota, USA
| |
Collapse
|
18
|
Bole DG, Ueda T. Inhibition of Vesicular Glutamate Uptake by Rose Bengal-Related Compounds: Structure–Activity Relationship. Neurochem Res 2005; 30:363-9. [PMID: 16018580 DOI: 10.1007/s11064-005-2610-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Synaptic vesicular accumulation of glutamate is a vital initial step in glutamate transmission. We have previously shown that Rose Bengal, a polyhalogenated fluorescein analog, is a potent inhibitor of glutamate uptake into synaptic vesicles. Here, we report the structural features of Rose Bengal required for this inhibition. Various Rose Bengal-related compounds, with systematic structural variations, were tested. Results indicate that the four iodo groups and the phenyl group attached to the xanthene moiety are critical for potent inhibitory activity. Replacement of these groups with two iodo groups and an alkyl group, respectively, results in substantial reduction in potency. Of further interest in creating high potency is the critical nature of the oxygen atom which links the two benzene rings of xanthene. Thus, the phenyl group and multiple iodo groups, as well as the bridging oxygen of xanthene, are crucial elements of Rose Bengal required for its potent inhibitory action.
Collapse
Affiliation(s)
- David G Bole
- Mental Health Research Institute, University of Michigan Medical School, Ann Arbor, Michigan 48109-0669, USA
| | | |
Collapse
|
19
|
Bai L, Zhang X, Ghishan FK. Characterization of vesicular glutamate transporter in pancreatic alpha - and beta -cells and its regulation by glucose. Am J Physiol Gastrointest Liver Physiol 2003; 284:G808-14. [PMID: 12444014 DOI: 10.1152/ajpgi.00333.2002] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Glutamate has been suggested to play an important role in the release of insulin and glucagon from pancreatic cells via exocytosis. Vesicular glutamate transporter is a rate-limiting step for glutamate release and is involved in the glutamate-evoked exocytosis. Two vesicular glutamate transporters (VGLUT1 and -2) have recently been cloned from the brain. In this report, we first functionally characterized vesicular glutamate transporter in cultured pancreatic alpha- and beta-cells, and then detected mRNA expression of VGLUT1 and -2 in these cells. We also investigated the effect of high or low level of glucose on vesicular glutamate transport in cultured pancreas cells. Our results suggest that both alpha- and beta-cells contain functional vesicular glutamate transporter. The transport characteristics are similar to the cloned neuronal VGLUT1 and -2 in regard to ATP dependence, substrate specificity, kinetics, and chloride dependence. VGLUT2 mRNA is expressed in both alpha- and beta-cells, whereas VGLUT1 is only expressed in beta-cells. High (12.8 mM) and low (2.8 mM) concentrations of glucose increased vesicular glutamate transport in beta- and alpha-cells, respectively. VGLUT2 mRNA was significantly increased in beta- and alpha-cells by high and low glucose concentration, respectively. This increase in VGLUT2 mRNA was suppressed by actinomycin D. We conclude that both alpha- and beta-cells possess functional vesicular glutamate transporters regulated by alteration in glucose concentration, partly via the transcriptional mechanism.
Collapse
Affiliation(s)
- Liqun Bai
- Departments of Pediatrics and Physiology, Steele Memorial Children's Research Center, University of Arizona Health Sciences Center, Tucson, Arizona 85724, USA.
| | | | | |
Collapse
|
20
|
Ikemoto A, Bole DG, Ueda T. Glycolysis and glutamate accumulation into synaptic vesicles. Role of glyceraldehyde phosphate dehydrogenase and 3-phosphoglycerate kinase. J Biol Chem 2003; 278:5929-40. [PMID: 12488440 DOI: 10.1074/jbc.m211617200] [Citation(s) in RCA: 142] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Glucose is the major source of brain energy and is essential for maintaining normal brain and neuronal function. Hypoglycemia causes impaired synaptic transmission. This occurs even before significant reduction in global cellular ATP concentration, and relationships among glycolysis, ATP supply, and synaptic transmission are not well understood. We demonstrate that the glycolytic enzymes glyceraldehyde phosphate dehydrogenase (GAPDH) and 3-phosphoglycerate kinase (3-PGK) are enriched in synaptic vesicles, forming a functional complex, and that synaptic vesicles are capable of accumulating the excitatory neurotransmitter glutamate by harnessing ATP produced by vesicle-bound GAPDH/3-PGK at the expense of their substrates. The GAPDH inhibitor iodoacetate suppressed GAPDH/3-PGK-dependent, but not exogenous ATP-dependent, [(3)H]glutamate uptake into isolated synaptic vesicles. It also decreased vesicular [(3)H]glutamate content in the nerve ending preparation synaptosome; this decrease was reflected in reduction of depolarization-induced [(3)H]glutamate release. In contrast, oligomycin, a mitochondrial ATP synthase inhibitor, had minimal effect on any of these parameters. ADP at concentrations above 0.1 mm inhibited vesicular glutamate and dissipated membrane potential. This suggests that the coupled GAPDH/3-PGK system, which converts ADP to ATP, ensures maximal glutamate accumulation into presynaptic vesicles. Together, these observations provide insight into the essential nature of glycolysis in sustaining normal synaptic transmission.
Collapse
Affiliation(s)
- Atsushi Ikemoto
- Mental Health Research Institute, University of Michigan Medical School, Ann Arbor, Michigan 48109-0669, USA
| | | | | |
Collapse
|
21
|
Zhang L, Tinette S, Robichon A. Phosphorylation of proteins in neuron terminals: specificity depends on coincidental signaling. J Cell Biochem 2003; 88:589-98. [PMID: 12532334 DOI: 10.1002/jcb.10363] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
We investigate the role of neuronal coincidental signaling mediated by the second messengers, on phosphorylation of three major proteins of neurosecretory vesicles. Our data show that different combinations of coincidental signaling generate specific pattern of phosphoproteins and not strictly additional effects. This suggests that an added phosphate on a site might 'mask' or 'unmask' the next sites for specific kinases and phosphatases action by inducing conformation change or protein association. We show that a function of vesicles such as the uptake of glutamate is highly regulated by coincidental signaling.
Collapse
Affiliation(s)
- Lixing Zhang
- CNRS, Centre Européen des Sciences du Goût, DIJON 21000, France
| | | | | |
Collapse
|
22
|
Masuko T, Kusama-Eguchi K, Sakata K, Kusama T, Chaki S, Okuyama S, Williams K, Kashiwagi K, Igarashi K. Polyamine transport, accumulation, and release in brain. J Neurochem 2003; 84:610-7. [PMID: 12558981 DOI: 10.1046/j.1471-4159.2003.01558.x] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Cycling of polyamines (spermine and spermidine) in the brain was examined by measuring polyamine transport in synaptic vesicles, synaptosomes and glial cells, and the release of spermine from hippocampal slices. It was found that membrane potential-dependent polyamine transport systems exist in synaptosomes and glial cells, and a proton gradient-dependent polyamine transport system exists in synaptic vesicles. The glial cell transporter had high affinities for both spermine and spermidine, whereas the transporters in synaptosomes and synaptic vesicles had a much higher affinity for spermine than for spermidine. Polyamine transport by synaptosomes was inhibited by putrescine, agmatine, histidine, and histamine. Transport by glial cells was also inhibited by these four compounds and additionally by norepinephrine. On the other hand, polyamine transport by synaptic vesicles was inhibited only by putrescine and histamine. These results suggest that the polyamine transporters present in glial cells, neurons, and synaptic vesicles each have different properties and are, presumably, different molecular entities. Spermine was found to be accumulated in synaptic vesicles and was released from rat hippocampal slices by depolarization using a high concentration of KCl. Polyamines, in particular spermine, may function as neuromodulators in the brain.
Collapse
Affiliation(s)
- Takashi Masuko
- Graduate School of Pharmaceutical Sciences, Chiba University, Chiba, Japan
| | | | | | | | | | | | | | | | | |
Collapse
|
23
|
Amano T, Matsubayashi H, Ozkan ED, Sasa M, Serikawa T, Ueda T. Aberrant reduction of an inhibitory protein factor in a rat epileptic model. Epilepsy Res 2002; 51:81-91. [PMID: 12350384 DOI: 10.1016/s0920-1211(02)00122-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Certain forms of seizure involve excessive glutamate transmission. We have recently identified a protein, referred to as the inhibitory protein factor (IPF), which potently inhibits glutamate uptake into isolated synaptic vesicles. In an effort to understand the mechanism underlying excessive glutamate transmission associated with seizure, we have analyzed IPF content in various brain regions of the spontaneously epileptic rat, SER (tm/tm, zi/zi), the absence-seizure tremor rat, TM (tm/tm), and the seizure-free control rats zitter ZI (zi/zi) and Wistar tremor control, each at 13 weeks of age. IPF content was found to be markedly reduced in the hippocampus, but not in the other brain regions, of SER, compared to the control and TM rats. TM rats also exhibited reduced IPF content compared to seizure-free controls. These changes appear developmentally regulated; no such alteration was observed in 8-week-old rats, which rarely show seizure. These observations indicate that an aberrant decrease in IPF is associated with certain forms of seizure; this decrease could lead to an abnormal increase in the amount of exocytotically released glutamate through its excessive accumulation in synaptic vesicles.
Collapse
Affiliation(s)
- Taku Amano
- Mental Health Research Institute, Medical School, The University of Michigan, Ann Arbor, MI 48109-0669, USA
| | | | | | | | | | | |
Collapse
|
24
|
Gonçalves PP, Meireles SM, Neves P, Vale MG. Ca2+ sensitivity of synaptic vesicle dopamine, gamma-aminobutyric acid, and glutamate transport systems. Neurochem Res 2001; 26:75-81. [PMID: 11358285 DOI: 10.1023/a:1007684716964] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The effect of Ca2+ on the uptake of neurotransmitters by synaptic vesicles was investigated in a synaptic vesicle enriched fraction isolated from sheep brain cortex. We observed that dopamine uptake, which is driven at expenses of the proton concentration gradient generated across the membrane by the H+-ATPase activity, is strongly inhibited (70%) by 500 microM Ca2+. Conversely, glutamate uptake, which essentially requires the electrical potential in the presence of low Cl- concentrations, is not affected by Ca2+, even when the proton concentration gradient greatly contributes for the proton electrochemical gradient. These observations were checked by adding Ca2+ to dopamine or glutamate loaded vesicles, which promoted dopamine release, whereas glutamate remained inside the vesicles. Furthermore, similar effects were obtained by adding 150 microM Zn2+ that, like Ca2+, dissipates the proton concentration gradient by exchanging with H+. With respect to gamma-aminobutyric acid transport, which utilizes either the proton concentration gradient or the electrical potential as energy sources, we observed that Ca2+ or Zn2+ do not induce great alterations in the gamma-aminobutyric acid accumulation by synaptic vesicles. These results clarify the nature of the energy source for accumulation of main neurotransmitters and suggest that stressing concentrations of Ca2+ or Zn2+ inhibit the proton concentration gradient-dependent neurotransmitter accumulation by inducing H+ pump uncoupling rather than by interacting with the neurotransmitter transporter molecules.
Collapse
Affiliation(s)
- P P Gonçalves
- Centro de Biologia Celular, Departamento de Biologia, Universidade de Aveiro, Portugal.
| | | | | | | |
Collapse
|
25
|
Bai L, Xu H, Collins JF, Ghishan FK. Molecular and functional analysis of a novel neuronal vesicular glutamate transporter. J Biol Chem 2001; 276:36764-9. [PMID: 11432869 DOI: 10.1074/jbc.m104578200] [Citation(s) in RCA: 164] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Glutamate is the major excitatory neurotransmitter in the mammalian central nervous system. Packaging and storage of glutamate into glutamatergic neuronal vesicles requires ATP-dependent vesicular glutamate uptake systems, which utilize the electrochemical proton gradient as a driving force. VGLUT1, the first identified vesicular glutamate transporter, is only expressed in a subset of glutamatergic neurons. We report here the molecular cloning and functional characterization of a novel glutamate transporter, VGLUT2, from mouse brain. VGLUT2 has all major functional characteristics of a synaptic vesicle glutamate transporter, including ATP dependence, chloride stimulation, substrate specificity, and substrate affinity. It has 75 and 79% amino acid identity with human and rat VGLUT1, respectively. However, expression patterns of VGLUT2 in brain are different from that of VGLUT1. In addition, VGLUT2 activity is dependent on both membrane potential and pH gradient of the electrochemical proton gradient, whereas VGLUT1 is primarily dependent on only membrane potential. The presence of VGLUT2 in brain regions lacking VGLUT1 suggests that the two isoforms together play an important role in vesicular glutamate transport in glutamatergic neurons.
Collapse
Affiliation(s)
- L Bai
- Department of Pediatrics, Steele Memorial Children's Research Center, University of Arizona Health Sciences Center, Tucson, Arizona 85724, USA.
| | | | | | | |
Collapse
|
26
|
Israël M, Tomasi M, Bostel S, Meunier FM. Cellular resistance to Evans blue toxicity involves an up-regulation of a phosphate transporter implicated in vesicular glutamate storage. J Neurochem 2001; 78:658-63. [PMID: 11483669 DOI: 10.1046/j.1471-4159.2001.00449.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
It has recently been suggested that the brain-specific Na+-dependent phosphate inorganic co-transporter (BNPI) is able to support glutamate transport and storage in synaptic vesicles. A procedure for measuring the vesicular pool of glutamate is described and was used to select cell lines according to their glutamate storage capacity. Two cell lines were selected: C6BU-1, with a large intracellular glutamate storage capacity, and NG108-15, devoid of it. Their contents in BNPI mRNA were compared by RT-PCR. We found that both cell lines had BNPI, but in addition C6BU-1 alone expresses the other isoform, DNPI. We also carried out a clonal selection of NG108-15 cells in the presence of the dye Evans blue, a competitive inhibitor of vesicular glutamate transport, very toxic for cells in culture. It was assumed that only those that sequester and eliminate the drug by overexpressing a vesicular glutamate transporter would survive. We found that the NG108-15 clones resistant to Evans blue had an increased storage capacity for glutamate. These cells also up-regulated the BNPI isoform of the phosphate transporter as shown by RT-PCR and northern blot.
Collapse
Affiliation(s)
- M Israël
- Laboratoire de Neurobiologie Cellulaire et Moléculaire, CNRS, Gif-sur-Yvette, France
| | | | | | | |
Collapse
|
27
|
Li H, Li SH, Johnston H, Shelbourne PF, Li XJ. Amino-terminal fragments of mutant huntingtin show selective accumulation in striatal neurons and synaptic toxicity. Nat Genet 2000; 25:385-9. [PMID: 10932179 DOI: 10.1038/78054] [Citation(s) in RCA: 208] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Huntington disease (HD) is caused by expansion of a glutamine repeat in the amino-terminal region of huntingtin. Despite its widespread expression, mutant huntingtin induces selective neuronal loss in striatal neurons. Here we report that, in mutant mice expressing HD repeats, the production and aggregation of N-terminal huntingtin fragments preferentially occur in HD-affected neurons and their processes and axonal terminals. N-terminal fragments of mutant huntingtin form aggregates and induce neuritic degeneration in cultured striatal neurons. N-terminal mutant huntingtin also binds to synaptic vesicles and inhibits their glutamate uptake in vitro. The specific processing and accumulation of toxic fragments of N-terminal huntingtin in HD-affected striatal neurons, especially in their neuronal processes and axonal terminals, may contribute to the selective neuropathology of HD.
Collapse
Affiliation(s)
- H Li
- Department of Genetics, Emory University School of Medicine, Atlanta, Georgia, USA
| | | | | | | | | |
Collapse
|
28
|
Gonçalves PP, Meireles SM, Neves P, Vale MG. Methods for analysis of Ca(2+)/H(+) antiport activity in synaptic vesicles isolated from sheep brain cortex. BRAIN RESEARCH. BRAIN RESEARCH PROTOCOLS 2000; 5:102-8. [PMID: 10719271 DOI: 10.1016/s1385-299x(99)00061-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
The involvement of Ca(2+)-storage organelles in the modulation of synaptic transmission is well-established [M.K. Bennett, Ca(2+) and the regulation of neurotransmitter secretion, Curr. Opin. Neurobiol. 7 (1997) 316-322 [1]; M.J. Berridge, Neuronal calcium signaling, Neuron 21 (1998) 13-26 [2]; Ph. Fossier, L. Tauc, G. Baux, Calcium transients and neurotransmitter release at an identified synapse, Trends Neurosci. 22 (1999) 161-166 [7] ]. Various Ca(2+) sequestering reservoirs (mitochondria, endoplasmic reticulum and synaptic vesicles) have been reported at the level of brain nerve terminals [P. Kostyuk, A. Verkhratsky, Calcium stores in neurons and glia, Neuroscience 63 (1994) 381-404 [18]; V. Mizuhira, H. Hasegawa, Microwave fixation and localization of calcium in synaptic terminals using X-ray microanalysis and electron energy loss spectroscopy imaging, Brain Res. Bull. 43 (1997) 53-58 [21]; A. Parducz, Y. Dunant, Transient increase of calcium in synaptic vesicles after stimulation, Neuroscience 52 (1993) 27-33 [23]; O.H. Petersen, Can Ca(2+) be released from secretory granules or synaptic vesicles?, Trends Neurosci. 19 (1996) 411-413 [24] ]. However, the knowledge of the specific contribution of each compartment for spatial and temporal control of the cytoplasmic Ca(2+) concentration requires detailed characterization of the Ca(2+) uptake and Ca(2+) release mechanisms by the distinct intracellular stores. In this work, we described rapid and simple experimental procedures for analysis of a Ca(2+)/H(+) antiport system that transport Ca(2+) into synaptic vesicles at expenses of the energy of a DeltapH generated either by activity of the proton pump or by a pH jumping of the vesicles passively loaded with protons. This secondary active Ca(2+) transport system requires high Ca(2+)100 microM) for activation, it is dependent on the chemical component (DeltapH) of the proton electrochemical gradient across the synaptic vesicle membrane and its selectivity is essentially determined by the size of the transported cation [P.P. Gonçalves, S.M. Meireles, C. Gravato, M.G. P. Vale, Ca(2+)-H(+)-Antiport activity in synaptic vesicles isolated from sheep brain cortex, Neurosci. Lett. 247 (1998) 87-90 [10]; P.P. Gonçalves, S.M. Meireles, P. Neves, M.G.P. Vale, Ionic selectivity of the Ca(2+)/H(+) antiport in synaptic vesicles of sheep brain cortex, Mol. Brain Res. 67 (1999) 283-291 [11]; P.P. Gonçalves, S.M. Meireles, P. Neves, M.G.P. Vale, Synaptic vesicle Ca(2+)/H(+) antiport: dependence on the proton electrochemical gradient, Mol. Brain Res. 71 (1999) 178-184 [12] ]. The protocols described here allow to ascertain the characteristics of the Ca(2+)/H(+) antiport in synaptic vesicles and, therefore, may be useful for clarification of the physiological role of synaptic vesicles in fast buffering of Ca(2+) at various sites of the neurotransmission machinery.
Collapse
Affiliation(s)
- P P Gonçalves
- Centro de Biologia Celular, Departamento de Biologia, Universidade de Aveiro, 3810-193, Aveiro, Portugal.
| | | | | | | |
Collapse
|
29
|
Carrigan CN, Esslinger CS, Bartlett RD, Bridges RJ, Thompson CM. Quinoline-2,4-dicarboxylic acids: synthesis and evaluation as inhibitors of the glutamate vesicular transport system. Bioorg Med Chem Lett 1999; 9:2607-12. [PMID: 10498218 DOI: 10.1016/s0960-894x(99)00444-8] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Twenty-six quinoline-2,4-dicarboxylic acids (QDC's) were synthesized by a modified Doebner-von Miller pathway and tested as inhibitors against the glutamate vesicular transport (GVT) protein. The QDC's were active as inhibitors with the most potent QDC's found to contain halogens at the 6-/8-position, a hydroxyl at the 8-position, or a tethered aromatic moiety at the 6- or 7-position of the quinoline.
Collapse
Affiliation(s)
- C N Carrigan
- Department of Pharmaceutical Sciences, The University of Montana, Missoula 59812, USA
| | | | | | | | | |
Collapse
|
30
|
Vaccari A, Ruiu S, Mocci I, Saba P. Selected pyrethroid insecticides stimulate glutamate uptake in brain synaptic vesicles. Neuroreport 1998; 9:3519-23. [PMID: 9855310 DOI: 10.1097/00001756-199810260-00034] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
We aimed to ascertain whether pyrethroid insecticides could influence the vesicular transport of the excitatory amino acid glutamate. The incubation of rat cortical synaptic vesicles with resmethrin and permethrin, consistently stimulated both ATP-dependent and -independent uptake of [3H]glutamate, while not evoking depletion of its vesicular content. Both processes were counteracted by valinomycin, a dissipator of the transmembrane potential gradient (deltapsi(sv)). Meanwhile, the vesicular influx of 36Cl- anions was impaired by pyrethroid concentrations which did not affect the ATP-dependent uptake of [14C]methylamine, as a marker for the proton gradient (deltapH). Thus, the stimulation of glutamate transport appeared to involve mainly the deltapsi(sv). A self-attenuating effect of selected pyrethroids on putatively enhanced excitatory transmission in severe intoxication is suggested.
Collapse
Affiliation(s)
- A Vaccari
- Bernard B. Brodie Department of Neuroscience, Cagliari, Italy
| | | | | | | |
Collapse
|
31
|
Lewis SM, Ueda T. Solubilization and reconstitution of synaptic vesicle glutamate transport system. Methods Enzymol 1998; 296:125-44. [PMID: 9779445 DOI: 10.1016/s0076-6879(98)96011-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Affiliation(s)
- S M Lewis
- Department of Veterans Affairs Medical Center, University of Minnesota Medical School, Minneapolis 55417, USA
| | | |
Collapse
|
32
|
Bartlett RD, Esslinger CS, Thompson CM, Bridges RJ. Substituted quinolines as inhibitors of L-glutamate transport into synaptic vesicles. Neuropharmacology 1998; 37:839-46. [PMID: 9776380 DOI: 10.1016/s0028-3908(98)00080-x] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
This study investigated the structure-activity relationships and kinetic properties of a library of kynurenate analogues as inhibitors of 3H-L-glutamate transport into rat forebrain synaptic vesicles. The lack of inhibitory activity observed with the majority of the monocyclic pyridine derivatives suggested that the second aromatic ring of the quinoline-based compounds played a significant role in binding to the transporter. A total of two kynurenate derivatives, xanthurenate and 7-chloro-kynurenate, differing only in the carbocyclic ring substituents, were identified as potent competitive inhibitors, exhibiting Ki values of 0.19 and 0.59 mM, respectively. The Km value for L-glutamate was found to be 2.46 mM. Parallel experiments demonstrated that while none of the kynurenate analogues tested effectively inhibited the synaptosomal transport of 3H-D-aspartate, some cross-reactivity was observed with the EAA ionotropic receptors. Molecular modeling studies were carried out with the identified inhibitors and glutamate in an attempt to preliminarily define the pharmacophore of the vesicular transporter. It is hypothesized that the ability of the kynurenate analogues to bind to the transporter may be tied to the capacity of the quinoline carbocyclic ring to mimic the negative charge of the gamma-carboxylate of glutamate. A total of two low energy solution conformers of glutamate were identified that exhibited marked functional group overlap with the most potent inhibitor, xanthurenate. These results help to further refine the pharmacological specificity of the glutamate binding site on the vesicular transporter and identify a series of inhibitors with which to investigate transporter function.
Collapse
Affiliation(s)
- R D Bartlett
- Department of Pharmaceutical Sciences, University of Montana, Missoula 59812, USA
| | | | | | | |
Collapse
|
33
|
Ozkan ED, Ueda T. Glutamate transport and storage in synaptic vesicles. JAPANESE JOURNAL OF PHARMACOLOGY 1998; 77:1-10. [PMID: 9639055 DOI: 10.1254/jjp.77.1] [Citation(s) in RCA: 75] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Glutamate plays an important metabolic role in virtually every vertebrate cell. In particular, glutamate is the most common excitatory neurotransmitter in the vertebrate central nervous system. As such, the mechanism by which glutamate is diverted from its normal metabolic activities toward its role as a neurotransmitter has, in recent years, been systematically investigated. In glutamatergic nerve endings, synaptic vesicles accumulate and store a proportion of the cellular glutamate pool and, in response to appropriate signals, release glutamate into the synaptic cleft by exocytosis. Glutamate accumulation is accomplished by virtue of a glutamate uptake system present in the synaptic vesicle membrane. The uptake system consists of a transport protein, remarkably specific for glutamate, and a vacuolar-type H+-ATPase, which provides the coupling between ATP hydrolysis and glutamate transport. The precise manner in which the glutamate transporter and H+-ATPase operate is currently the subject of debate. Recent data relevant to this debate are reviewed in this article. Additionally, pharmacological agents thought to specifically interact with the vesicular glutamate transporter are discussed. Finally, a newly discovered, endogenous inhibitor of vesicular uptake, inhibitory protein factor (IPF), is discussed with some speculations as to its potential role as a presynaptic modulator of neurotransmission.
Collapse
Affiliation(s)
- E D Ozkan
- Mental Health Research Institute, Medical School, The University of Michigan, Ann Arbor 48109, USA
| | | |
Collapse
|
34
|
Thoidis G, Chen P, Pushkin AV, Vallega G, Leeman SE, Fine RE, Kandror KV. Two distinct populations of synaptic-like vesicles from rat brain. Proc Natl Acad Sci U S A 1998; 95:183-8. [PMID: 9419350 PMCID: PMC18168 DOI: 10.1073/pnas.95.1.183] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
In nonneuronal cells, several plasma membrane proteins such as exofacial enzymes, receptors, and ion channels recycle between their intracellular compartment(s) and the cell surface via an endosomal pathway. In neurons, however, this pathway has not been extensively characterized. In particular, it remains unclear whether or not it is related to the recycling of small synaptic vesicles, the major pathway of membrane traffic in nerve terminals. To approach this problem, we purified and studied a vesicular fraction from rat brain synaptosomes. Two distinct populations of vesicles with different buoyant densities and sedimentation coefficients were detected in this fraction by sucrose gradient centrifugation and Western blot analysis of the individual proteins. Both populations contain proteins that are markers of synaptic vesicles, namely, SV2, synaptotagmin, synaptophysin, secretory carrier membrane proteins (SCAMPs), synaptobrevin, and rab3a. A striking difference between the two populations is the presence of arginine aminopeptidase activity (a previously suggested marker for the regulated endosomal recycling pathway) exclusively in the lighter less-dense vesicles. The same two vesicular populations were also detected in the preparation of clathrin-coated vesicles isolated from whole rat brain or purified synaptosomes after removal of their clathrin coats by incubation at pH 8.5. We conclude, therefore, that both types of vesicles recycle in synaptosomes via a clathrin-mediated pathway. These data present experimental evidence for biochemical heterogeneity of synaptic-like vesicles in rat brain.
Collapse
Affiliation(s)
- G Thoidis
- Department of Biochemistry, Boston University School of Medicine, 80 East Concord Street, Boston, MA 02118, USA
| | | | | | | | | | | | | |
Collapse
|
35
|
Xu CJ, Kanfer JN, Klunk WE, Xiong Q, McClure RJ, Pettegrew JW. Effect of phosphomonoesters, phosphodiesters, and phosphocreatine on glutamate uptake by synaptic vesicles. MOLECULAR AND CHEMICAL NEUROPATHOLOGY 1997; 32:89-99. [PMID: 9437660 DOI: 10.1007/bf02815169] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
L-Glutamate, a major excitatory amino acid, plays an important role in learning and memory. L-Glutamate uptake into synaptic vesicles is an ATP-dependent process. Exposure of neurons to high, sustained extracellular concentrations of glutamate results in excitotoxicity. Elevated levels of phosphomonoesters (PMEs), phosphodiesters (PDEs), and phosphocreatine (PCr) have been reported in Alzheimer disease (AD). In this article, the effects of selected PMEs, PDEs, and PCr on vesicular L-[3H]glutamate uptake into isolated bovine synaptic vesicles are investigated. D-myo-Inositol-1-monophosphate (I1P), D-myo-inositol-2-monophosphate (I2P), sn-glycero-3-phosphate, (alpha-GP) and PCr significantly stimulated L-[3H]glutamate uptake into synaptic vesicles. Phosphoethanolamine (PE), phosphocholine (PC), L-phosphoserine (L-PS) sn-glycero-3-phosphocholine (GPC), and sn-glycero-3-phosphoethanolamine (GPE) had little or no effect on vesicular L-glutamate uptake. These observations suggested that the vesicular uptake of glutamate can be regulated by endogenous PMEs and PCr. The mechanism of activation by I1P, I2P, and alpha-GP appears to be stimulation of Mg(2+)-ATPase activity. These effects on vesicular glutamate uptake may be important in diseases in which the levels of these metabolites are altered, as they are in AD.
Collapse
Affiliation(s)
- C J Xu
- Department of Psychiatry, Western Psychiatric Institute and Clinic, University of Pittsburgh Medical Center, PA 15261, USA
| | | | | | | | | | | |
Collapse
|
36
|
Abstract
Rapid membrane recycling in nerve terminals is required to maintain rapid synaptic transmission. Following the fusion of synaptic vesicles with synaptic plasma membranes, recycling can occur via clathrin-coated vesicles (CCVs) [1-3]. The fate of these vesicles is uncertain: they could simply uncoat and acquire other proteins from the cytosol to regenerate synaptic vesicles or they may fuse with endosomal structures from which synaptic vesicles could then bud. We have purified both CCVs and synaptic vesicles from rat brain, and measured the ability of these vesicle fractions to take up the excitatory neurotransmitter glutamic acid. We found that the normalized levels of glutamate uptake by the two types of vesicle were very similar. For each vesicle fraction, uptake required ATP and Cl- and could be fully inhibited by the specific vacuolar proton pump (v-ATPase) inhibitor concanamycin. We suggest that this ability to refill vesicles with neurotransmitter at the earliest intermediate on the recycling pathway - the CCV - may allow uncoated vesicles to immediately enter the releasable pool without sacrificing the quantal nature of neurotransmitter release.
Collapse
Affiliation(s)
- I A Prior
- Physiological Laboratory, University of Liverpool, Crown Street, Liverpool, L69 3BX, UK
| | | |
Collapse
|
37
|
Ozkan ED, Lee FS, Ueda T. A protein factor that inhibits ATP-dependent glutamate and gamma-aminobutyric acid accumulation into synaptic vesicles: purification and initial characterization. Proc Natl Acad Sci U S A 1997; 94:4137-42. [PMID: 9108118 PMCID: PMC20581 DOI: 10.1073/pnas.94.8.4137] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/1996] [Accepted: 02/06/1997] [Indexed: 02/04/2023] Open
Abstract
Glutamate, the major excitatory neurotransmitter in the mammalian central nervous system, is transported into and stored in synaptic vesicles. We have purified to apparent homogeneity a protein from brain cytosol that inhibits glutamate and gamma-aminobutyric acid uptake into synaptic vesicles and have termed this protein "inhibitory protein factor" (IPF). IPF refers to three distinct proteins with relative molecular weights of 138,000 (IPF alpha), 135,000 (IPF beta), and 132,000 (IPF gamma), respectively. Gel filtration and sedimentation data suggest that all three proteins share an elongated structure, identical Stokes radius (60 A), and identical sedimentation coefficient (4.3 S). Using these values and a partial specific volume of 0.716 ml/g, we determined the native molecular weight for IPF alpha to be 103,000. Partial sequence analysis shows that IPF alpha is derived from alpha fodrin, a protein implicated in several diverse cellular activities. IPF alpha inhibits ATP-dependent glutamate uptake into purified synaptic vesicles with an IC50 of approximately 26 nM, while showing no ability to inhibit ATP-independent uptake at concentrations up to 100 nM. Moreover, IPF alpha inhibited neither norepinephrine uptake into chromaffin vesicles nor Na+-dependent glutamate uptake into synaptosomes. However, IPF alpha inhibited uptake of gamma-aminobutyric acid into synaptic vesicles derived from spinal cord, suggesting that inhibition may not be limited to glutamatergic systems. We propose that IPF could be a novel component of a presynaptic regulatory system. Such a system might modulate neurotransmitter accumulation into synaptic vesicles and thus regulate the overall efficacy of neurotransmission.
Collapse
Affiliation(s)
- E D Ozkan
- Mental Health Research Institute, University of Michigan, Ann Arbor 48109-0720, USA
| | | | | |
Collapse
|
38
|
Xu CJ, Klunk WE, Kanfer JN, Xiong Q, Miller G, Pettegrew JW. Phosphocreatine-dependent glutamate uptake by synaptic vesicles. A comparison with atp-dependent glutamate uptake. J Biol Chem 1996; 271:13435-40. [PMID: 8662761 DOI: 10.1074/jbc.271.23.13435] [Citation(s) in RCA: 72] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
ATP-dependent uptake of glutamate into synaptic vesicles has been well documented. Stimulation of glutamate uptake into synaptic vesicles by other high-energy phosphates has not been described. In this paper, we examine the stimulation of phosphocreatine (PCr)-induced glutamate uptake and determine whether this stimulation is secondary to conversion of PCr to ATP. We found the following. 1) PCr stimulates glutamate uptake into synaptic vesicles in the absence of added ATP. 2) At a glutamate concentration of 50 microM, no concentration of added ATP could produce the degree of stimulation seen in the presence of PCr. 3) 0.5 mM iodoacetamide completely inhibits synaptic vesicle creatine kinase activity but does not inhibit PCr-stimulated glutamate uptake. 4) PCr-dependent glutamate uptake, unlike ATP-dependent uptake, is not magnesium- or chloride-dependent. 5) 0.5 mM N-ethylmaleimide, a selective H+-ATPase inhibitor, completely inhibits ATP-dependent glutamate uptake but only slightly inhibits PCr-dependent glutamate uptake. 6) PCr-dependent glutamate uptake is sensitive to valinomycin, a K+/H+ translocator, whereas the ATP-dependent uptake is not. Therefore, it appears that in addition to the well-known ATP-dependent glutamate uptake system, there is a previously unreported PCr-dependent glutamate uptake system in synaptic vesicles. The total glutamate uptake by synaptic vesicles is likely the sum of both ATP- and PCr-dependent glutamate uptake.
Collapse
Affiliation(s)
- C J Xu
- Laboratory of Neurophysics, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania 15213, USA
| | | | | | | | | | | |
Collapse
|
39
|
Kechagias S, Broman J. Immunocytochemical evidence for vesicular storage of glutamate in cat spinocervical and cervicothalamic tract terminals. Brain Res 1995; 675:316-20. [PMID: 7796145 DOI: 10.1016/0006-8993(95)00122-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The densities of synaptic vesicles and gold particles, signaling fixed glutamate, were examined in spinocervical and cervicothalamic tract terminals. Statistically significant positive correlations between these parameters were detected in both terminal populations, whereas presumed inhibitory profiles displayed insignificant or negative correlations. These findings indicate a vesicular storage of glutamate in spinocervical and cervicothalamic tract terminals, and thus provide further evidence for glutamate as a neurotransmitter in the spinocervicothalamic pathway.
Collapse
Affiliation(s)
- S Kechagias
- Department of Cell Biology, Faculty of Health Sciences, Linköping University, Sweden
| | | |
Collapse
|
40
|
Hong RM, Mori H, Fukui T, Moriyama Y, Futai M, Yamamoto A, Tashiro Y, Tagaya M. Association of N-ethylmaleimide-sensitive factor with synaptic vesicles. FEBS Lett 1994; 350:253-7. [PMID: 8070574 DOI: 10.1016/0014-5793(94)00778-0] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
N-Ethylmaleimide-sensitive factor (NSF) mediates docking and/or fusion of transport vesicles in the multi-pathways of vesicular transport. NSF was highly expressed in brain and adrenal gland. Immunostaining of cerebellum with an anti-NSF monoclonal antibody showed that NSF is predominantly localized in the molecular layers and the glomeruli of the granule cell layers. This distribution coincided well with that of synaptophysin, a marker protein of synaptic vesicles. Purification and immunoprecipitation revealed that NSF is associated with brain synaptic vesicles. The present results suggest that NSF is associated with synaptic vesicles without Ca2+ influx.
Collapse
Affiliation(s)
- R M Hong
- Institute of Scientific and Industrial Research, Osaka University, Japan
| | | | | | | | | | | | | | | |
Collapse
|
41
|
Ohashi M, Amano S, Hazama F, Handa J. Hypoxic effects on glutamate uptake in cultured glial cells. ACTA PATHOLOGICA JAPONICA 1993; 43:154-9. [PMID: 8098565 DOI: 10.1111/j.1440-1827.1993.tb01126.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Hypoxic effects on glutamate uptake and ATP content in glial cells were investigated by using cultured C6 glioma cells. Mild regressive changes were found depending on the duration of the hypoxic insult, but necrosis or detachment of the cells from the substratum was rarely observed. Glutamate uptake was relatively well preserved after a short hypoxic insult, while a marked decrease in glutamate uptake was observed after hypoxia of long duration. The uptake of sucrose was reduced in a similar pattern to glutamate uptake. Hypoxic insult resulted in a significant reduction of the ATP content in glial cells. Therefore, the decrease in glutamate uptake by glial cells under hypoxia is likely to be due to ATP dependency, and not to the failure of a specific glutamate uptake system, but the failure of a general uptake of the glial cells owing to the energy-dependent membrane dysfunction by ATP depletion. These findings suggest that there are phased changes of astrocytic functions in a hypoxic condition, a preservative phase in the initial stages and then a dysfunctional phase in the later stages of hypoxia.
Collapse
Affiliation(s)
- M Ohashi
- Department of Neurosurgery, Shiga University of Medical Science, Otsu, Japan
| | | | | | | |
Collapse
|
42
|
Burger PM, Hell J, Mehl E, Krasel C, Lottspeich F, Jahn R. GABA and glycine in synaptic vesicles: storage and transport characteristics. Neuron 1991; 7:287-93. [PMID: 1678614 DOI: 10.1016/0896-6273(91)90267-4] [Citation(s) in RCA: 138] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
gamma-Aminobutyric acid (GABA) and glycine are major inhibitory neurotransmitters that are released from nerve terminals by exocytosis via synaptic vesicles. Here we report that synaptic vesicles immunoisolated from rat cerebral cortex contain high amounts of GABA in addition to glutamate. Synaptic vesicles from the rat medulla oblongata also contain glycine and exhibit a higher GABA and a lower glutamate concentration than cortical vesicles. No other amino acids were detected. In addition, the uptake activities of synaptic vesicles for GABA and glycine were compared. Both were very similar with respect to substrate affinity and specificity, bioenergetic properties, and regional distribution. We conclude that GABA, glycine, and glutamate are the only major amino acid neurotransmitters stored in synaptic vesicles and that GABA and glycine are transported by similar, if not identical, transporters.
Collapse
Affiliation(s)
- P M Burger
- Department of Neurochemistry, Max-Planck Institute for Psychiatry, Martinsried, Germany
| | | | | | | | | | | |
Collapse
|
43
|
Lobur AT, Kish PE, Ueda T. Synaptic vesicular glutamate uptake: modulation by a synaptosomal cytosolic factor. J Neurochem 1990; 54:1614-8. [PMID: 1969936 DOI: 10.1111/j.1471-4159.1990.tb01212.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
We have demonstrated previously that L-glutamate is taken up into isolated synaptic vesicles in an ATP-dependent manner, supporting the neurotransmitter role of this acidic amino acid. We now report that a nerve terminal cytosolic factor inhibits the ATP-dependent vesicular uptake of glutamate in a dose-dependent manner. This factor appears to be a protein with a molecular weight greater than 100,000, as estimated by size exclusion chromatography, and is precipitated by ammonium sulfate (40% saturation). The inhibitory factor is inactivated by heating to 100 degrees C. Proteolytic digestion of the ammonium sulfate fraction by trypsin or chymotrypsin did not reduce, but rather increased slightly, the inhibition of glutamate uptake. Unlike the native factor, the digest retained inhibitory activity after heating, suggesting that proteolytic digestion may generate active fragments. The inhibition of ATP-dependent vesicular glutamate uptake is not species-specific, as the factor obtained from both rat and bovine brains produced an equal degree of inhibition of glutamate uptake into vesicles of each species. These observations raise the possibility that vesicular uptake of glutamate may be regulated by an endogenous factor in vivo.
Collapse
Affiliation(s)
- A T Lobur
- Department of Pharmacology, University of Michigan, Ann Arbor 48109
| | | | | |
Collapse
|
44
|
Carlson MD, Ueda T. Accumulated glutamate levels in the synaptic vesicle are not maintained in the absence of active transport. Neurosci Lett 1990; 110:325-30. [PMID: 1970147 DOI: 10.1016/0304-3940(90)90868-a] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
We have investigated factors which may affect accumulated glutamate levels in synaptic vesicles and glutamate efflux. Agents which dissipate the electrochemical proton gradient resulted in a rapid reduction of steady-state vesicular glutamate levels, which was prevented by N-ethylmaleimide. Glutamate efflux was found to occur even in the presence of an electrochemical proton gradient, but was effectively inhibited by N-ethylmaleimide. These results suggest that accumulated glutamate levels in synaptic vesicles are not maintained unless glutamate is taken up continuously by an active transport mechanism, and they could provide an explanation for the lack of convincing evidence for the enrichment of endogenous glutamate in isolated synaptic vesicles.
Collapse
Affiliation(s)
- M D Carlson
- Department of Pharmacology, University of Michigan, Ann Arbor 48109
| | | |
Collapse
|