1
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Zhao C, Wang C, Zhang H, Yan W. A mini-review of the role of vesicular glutamate transporters in Parkinson's disease. Front Mol Neurosci 2023; 16:1118078. [PMID: 37251642 PMCID: PMC10211467 DOI: 10.3389/fnmol.2023.1118078] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Accepted: 04/06/2023] [Indexed: 05/31/2023] Open
Abstract
Parkinson's disease (PD) is a common neurodegenerative disease implicated in multiple interacting neurotransmitter pathways. Glutamate is the central excitatory neurotransmitter in the brain and plays critical influence in the control of neuronal activity. Impaired Glutamate homeostasis has been shown to be closely associated with PD. Glutamate is synthesized in the cytoplasm and stored in synaptic vesicles by vesicular glutamate transporters (VGLUTs). Following its exocytotic release, Glutamate activates Glutamate receptors (GluRs) and mediates excitatory neurotransmission. While Glutamate is quickly removed by excitatory amino acid transporters (EAATs) to maintain its relatively low extracellular concentration and prevent excitotoxicity. The involvement of GluRs and EAATs in the pathophysiology of PD has been widely studied, but little is known about the role of VGLUTs in the PD. In this review, we highlight the role of VGLUTs in neurotransmitter and synaptic communication, as well as the massive alterations in Glutamate transmission and VGLUTs levels in PD. Among them, adaptive changes in the expression level and function of VGLUTs may exert a crucial role in excitatory damage in PD, and VGLUTs are considered as novel potential therapeutic targets for PD.
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Affiliation(s)
- Cheng Zhao
- Department of Neurology, The Second Xiangya Hospital, Central South University, Changsha, China
- National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, China
- Department of Urology, Xiangya Hospital, Central South University, Changsha, China
| | - Chunyu Wang
- Department of Neurology, The Second Xiangya Hospital, Central South University, Changsha, China
| | - Hainan Zhang
- Department of Neurology, The Second Xiangya Hospital, Central South University, Changsha, China
| | - Weiqian Yan
- Department of Neurology, The Second Xiangya Hospital, Central South University, Changsha, China
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2
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Cuellar-Santoyo AO, Ruiz-Rodríguez VM, Mares-Barbosa TB, Patrón-Soberano A, Howe AG, Portales-Pérez DP, Miquelajáuregui Graf A, Estrada-Sánchez AM. Revealing the contribution of astrocytes to glutamatergic neuronal transmission. Front Cell Neurosci 2023; 16:1037641. [PMID: 36744061 PMCID: PMC9893894 DOI: 10.3389/fncel.2022.1037641] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2022] [Accepted: 12/20/2022] [Indexed: 01/20/2023] Open
Abstract
Research on glutamatergic neurotransmission has focused mainly on the function of presynaptic and postsynaptic neurons, leaving astrocytes with a secondary role only to ensure successful neurotransmission. However, recent evidence indicates that astrocytes contribute actively and even regulate neuronal transmission at different levels. This review establishes a framework by comparing glutamatergic components between neurons and astrocytes to examine how astrocytes modulate or otherwise influence neuronal transmission. We have included the most recent findings about the role of astrocytes in neurotransmission, allowing us to understand the complex network of neuron-astrocyte interactions. However, despite the knowledge of synaptic modulation by astrocytes, their contribution to specific physiological and pathological conditions remains to be elucidated. A full understanding of the astrocyte's role in neuronal processing could open fruitful new frontiers in the development of therapeutic applications.
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Affiliation(s)
- Ares Orlando Cuellar-Santoyo
- División de Biología Molecular, Laboratorio de Neurobiología, Instituto Potosino de Investigación Científica y Tecnológica (IPICYT), San Luis Potosí, Mexico
| | - Victor Manuel Ruiz-Rodríguez
- División de Biología Molecular, Laboratorio de Neurobiología, Instituto Potosino de Investigación Científica y Tecnológica (IPICYT), San Luis Potosí, Mexico
| | - Teresa Belem Mares-Barbosa
- División de Biología Molecular, Laboratorio de Neurobiología, Instituto Potosino de Investigación Científica y Tecnológica (IPICYT), San Luis Potosí, Mexico,Translational and Molecular Medicine Laboratory, Research Center for Health Sciences and Biomedicine, Autonomous University of San Luis Potosí, San Luis Potosí, Mexico
| | - Araceli Patrón-Soberano
- División de Biología Molecular, Laboratorio de Neurobiología, Instituto Potosino de Investigación Científica y Tecnológica (IPICYT), San Luis Potosí, Mexico
| | - Andrew G. Howe
- Intelligent Systems Laboratory, HRL Laboratories, LLC, Malibu, CA, United States
| | - Diana Patricia Portales-Pérez
- Translational and Molecular Medicine Laboratory, Research Center for Health Sciences and Biomedicine, Autonomous University of San Luis Potosí, San Luis Potosí, Mexico
| | | | - Ana María Estrada-Sánchez
- División de Biología Molecular, Laboratorio de Neurobiología, Instituto Potosino de Investigación Científica y Tecnológica (IPICYT), San Luis Potosí, Mexico,*Correspondence: Ana María Estrada-Sánchez
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3
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Rostamipour K, Talandashti R, Mehrnejad F. Atomistic insight into the luminal allosteric regulation of vesicular glutamate transporter 2 by chloride and protons: An
all‐atom
molecular dynamics simulation study. Proteins 2022; 90:2045-2057. [DOI: 10.1002/prot.26396] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Revised: 05/27/2022] [Accepted: 06/28/2022] [Indexed: 11/08/2022]
Affiliation(s)
- Kiana Rostamipour
- Department of Life Sciences Engineering, Faculty of New Sciences and Technologies University of Tehran Tehran Iran
| | - Reza Talandashti
- Department of Life Sciences Engineering, Faculty of New Sciences and Technologies University of Tehran Tehran Iran
| | - Faramarz Mehrnejad
- Department of Life Sciences Engineering, Faculty of New Sciences and Technologies University of Tehran Tehran Iran
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4
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Hori T, Takamori S. Physiological Perspectives on Molecular Mechanisms and Regulation of Vesicular Glutamate Transport: Lessons From Calyx of Held Synapses. Front Cell Neurosci 2022; 15:811892. [PMID: 35095427 PMCID: PMC8793065 DOI: 10.3389/fncel.2021.811892] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Accepted: 12/07/2021] [Indexed: 12/02/2022] Open
Abstract
Accumulation of glutamate, the primary excitatory neurotransmitter in the mammalian central nervous system, into presynaptic synaptic vesicles (SVs) depends upon three vesicular glutamate transporters (VGLUTs). Since VGLUTs are driven by a proton electrochemical gradient across the SV membrane generated by vacuolar-type H+-ATPases (V-ATPases), the rate of glutamate transport into SVs, as well as the amount of glutamate in SVs at equilibrium, are influenced by activities of both VGLUTs and V-ATPase. Despite emerging evidence that suggests various factors influencing glutamate transport by VGLUTs in vitro, little has been reported in physiological or pathological contexts to date. Historically, this was partially due to a lack of appropriate methods to monitor glutamate loading into SVs in living synapses. Furthermore, whether or not glutamate refilling of SVs can be rate-limiting for synaptic transmission is not well understood, primarily due to a lack of knowledge concerning the time required for vesicle reuse and refilling during repetitive stimulation. In this review, we first introduce a unique electrophysiological method to monitor glutamate refilling by VGLUTs in a giant model synapse from the calyx of Held in rodent brainstem slices, and we discuss the advantages and limitations of the method. We then introduce the current understanding of factors that potentially alter the amount and rate of glutamate refilling of SVs in this synapse, and discuss open questions from physiological viewpoints.
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Affiliation(s)
- Tetsuya Hori
- Cellular and Molecular Synaptic Function Unit, Okinawa Institute of Science and Technology Graduate University, Okinawa, Japan
- *Correspondence: Tetsuya Hori Shigeo Takamori
| | - Shigeo Takamori
- Laboratory of Neural Membrane Biology, Graduate School of Brain Science, Doshisha University, Kyoto, Japan
- *Correspondence: Tetsuya Hori Shigeo Takamori
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5
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Abstract
Synaptic vesicles (SVs) store neurotransmitters and undergo a fine-tuned regulatory and dynamic cycle of exo- and endocytosis, which is essential for neurotransmission at chemical synapses. The development of protocols for isolating SVs from biological extracts was a fundamental accomplishment since it allowed for characterizing the molecular properties of SVs using biochemical methods. In this chapter, we describe a modified procedure for isolating SVs from a few g of rodent brain and that can be completed within ~12 h. The protocol involves the preparation of isolated nerve terminals from which SVs are released by osmotic shock and then enriched via various centrifugation steps, followed by size exclusion chromatography as final purification step. The final vesicle fraction is 22-fold enriched in SVs over the starting material, and the final yield of SVs obtained using this protocol is approximately 20 μg of protein per gram of mouse brain. The degree of contamination by other organelles and particles monitored by morphology and immunolabeling compares well with that of the classical protocols.
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Affiliation(s)
- Marcelo Ganzella
- Laboratory of Neurobiology, Max-Planck-Institute for Biophysical Chemistry, Göttingen, Germany.
| | - Momchil Ninov
- Laboratory of Neurobiology, Max-Planck-Institute for Biophysical Chemistry, Göttingen, Germany
- Bioanalytical Mass Spectrometry, Max-Planck-Institute for Biophysical Chemistry, Göttingen, Germany
| | - Dietmar Riedel
- Facility for Transmission Electron Microscopy, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Reinhard Jahn
- Laboratory of Neurobiology, Max-Planck-Institute for Biophysical Chemistry, Göttingen, Germany
- Georg-August University, Göttingen, Germany
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6
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Andersen JV, Markussen KH, Jakobsen E, Schousboe A, Waagepetersen HS, Rosenberg PA, Aldana BI. Glutamate metabolism and recycling at the excitatory synapse in health and neurodegeneration. Neuropharmacology 2021; 196:108719. [PMID: 34273389 DOI: 10.1016/j.neuropharm.2021.108719] [Citation(s) in RCA: 139] [Impact Index Per Article: 46.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Revised: 07/01/2021] [Accepted: 07/13/2021] [Indexed: 02/08/2023]
Abstract
Glutamate is the primary excitatory neurotransmitter of the brain. Cellular homeostasis of glutamate is of paramount importance for normal brain function and relies on an intricate metabolic collaboration between neurons and astrocytes. Glutamate is extensively recycled between neurons and astrocytes in a process known as the glutamate-glutamine cycle. The recycling of glutamate is closely linked to brain energy metabolism and is essential to sustain glutamatergic neurotransmission. However, a considerable amount of glutamate is also metabolized and serves as a metabolic hub connecting glucose and amino acid metabolism in both neurons and astrocytes. Disruptions in glutamate clearance, leading to neuronal overstimulation and excitotoxicity, have been implicated in several neurodegenerative diseases. Furthermore, the link between brain energy homeostasis and glutamate metabolism is gaining attention in several neurological conditions. In this review, we provide an overview of the dynamics of synaptic glutamate homeostasis and the underlying metabolic processes with a cellular focus on neurons and astrocytes. In particular, we review the recently discovered role of neuronal glutamate uptake in synaptic glutamate homeostasis and discuss current advances in cellular glutamate metabolism in the context of Alzheimer's disease and Huntington's disease. Understanding the intricate regulation of glutamate-dependent metabolic processes at the synapse will not only increase our insight into the metabolic mechanisms of glutamate homeostasis, but may reveal new metabolic targets to ameliorate neurodegeneration.
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Affiliation(s)
- Jens V Andersen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark.
| | - Kia H Markussen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark; Department of Molecular and Cellular Biochemistry, College of Medicine, University of Kentucky, Lexington, KY, USA
| | - Emil Jakobsen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark
| | - Arne Schousboe
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark
| | - Helle S Waagepetersen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark
| | - Paul A Rosenberg
- Department of Neurology and the F.M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA, USA; Program in Neuroscience, Harvard Medical School, Boston, MA, USA
| | - Blanca I Aldana
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark.
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7
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Nakakubo Y, Abe S, Yoshida T, Takami C, Isa M, Wojcik SM, Brose N, Takamori S, Hori T. Vesicular Glutamate Transporter Expression Ensures High-Fidelity Synaptic Transmission at the Calyx of Held Synapses. Cell Rep 2021; 32:108040. [PMID: 32814044 DOI: 10.1016/j.celrep.2020.108040] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Revised: 07/01/2020] [Accepted: 07/24/2020] [Indexed: 12/26/2022] Open
Abstract
Recycling of synaptic vesicles (SVs) at presynaptic terminals is required for sustained neurotransmitter release. Although SV endocytosis is a rate-limiting step for synaptic transmission, it is unclear whether the rate of the subsequent SV refilling with neurotransmitter also influences synaptic transmission. By analyzing vesicular glutamate transporter 1 (VGLUT1)-deficient calyx of Held synapses, in which both VGLUT1 and VGLUT2 are co-expressed in wild-type situation, we found that VGLUT1 loss causes a drastic reduction in SV refilling rate down to ∼25% of wild-type values, with only subtle changes in basic synaptic parameters. Strikingly, VGLUT1-deficient synapses exhibited abnormal synaptic failures within a few seconds during high-frequency repetitive firing, which was recapitulated by manipulating presynaptic Cl- concentrations to retard SV refilling. Our data show that the speed of SV refilling can be rate limiting for synaptic transmission under certain conditions that entail reduced VGLUT levels during development as well as various neuropathological processes.
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Affiliation(s)
- Yutaro Nakakubo
- Department of Neurophysiology, Graduate School of Life and Medical Sciences, Doshisha University, Kyoto 610-0394, Japan
| | - Saeka Abe
- Department of Neurophysiology, Graduate School of Life and Medical Sciences, Doshisha University, Kyoto 610-0394, Japan
| | - Tomofumi Yoshida
- Laboratory of Neural Membrane Biology, Graduate School of Brain Science, Doshisha University, Kyoto 610-0394, Japan
| | - Chihiro Takami
- Laboratory of Neural Membrane Biology, Graduate School of Brain Science, Doshisha University, Kyoto 610-0394, Japan
| | - Masayuki Isa
- Laboratory of Neural Membrane Biology, Graduate School of Brain Science, Doshisha University, Kyoto 610-0394, Japan
| | - Sonja M Wojcik
- Department of Molecular Neurobiology, Max Planck Institute for Experimental Medicine, Göttingen 37075, Germany
| | - Nils Brose
- Department of Molecular Neurobiology, Max Planck Institute for Experimental Medicine, Göttingen 37075, Germany
| | - Shigeo Takamori
- Laboratory of Neural Membrane Biology, Graduate School of Brain Science, Doshisha University, Kyoto 610-0394, Japan.
| | - Tetsuya Hori
- Department of Neurophysiology, Graduate School of Life and Medical Sciences, Doshisha University, Kyoto 610-0394, Japan.
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8
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Rodríguez-Campuzano AG, Ortega A. Glutamate transporters: Critical components of glutamatergic transmission. Neuropharmacology 2021; 192:108602. [PMID: 33991564 DOI: 10.1016/j.neuropharm.2021.108602] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Revised: 04/09/2021] [Accepted: 04/27/2021] [Indexed: 02/06/2023]
Abstract
Glutamate is the major excitatory neurotransmitter in the vertebrate central nervous system. Once released, it binds to specific membrane receptors and transporters activating a wide variety of signal transduction cascades, as well as its removal from the synaptic cleft in order to avoid its extracellular accumulation and the overstimulation of extra-synaptic receptors that might result in neuronal death through a process known as excitotoxicity. Although neurodegenerative diseases are heterogenous in clinical phenotypes and genetic etiologies, a fundamental mechanism involved in neuronal degeneration is excitotoxicity. Glutamate homeostasis is critical for brain physiology and Glutamate transporters are key players in maintaining low extracellular Glutamate levels. Therefore, the characterization of Glutamate transporters has been an active area of glutamatergic research for the last 40 years. Transporter activity its regulated at different levels: transcriptional and translational control, transporter protein trafficking and membrane mobility, and through extensive post-translational modifications. The elucidation of these mechanisms has emerged as an important piece to shape our current understanding of glutamate actions in the nervous system.
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Affiliation(s)
- Ada G Rodríguez-Campuzano
- Departamento de Toxicología, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Apartado Postal 14-740, Ciudad de México, 07000, Mexico
| | - Arturo Ortega
- Departamento de Toxicología, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Apartado Postal 14-740, Ciudad de México, 07000, Mexico.
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9
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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: 0] [Impact Index Per Article: 0] [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.
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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.
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10
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Li F, Eriksen J, Finer-Moore J, Chang R, Nguyen P, Bowen A, Myasnikov A, Yu Z, Bulkley D, Cheng Y, Edwards RH, Stroud RM. Ion transport and regulation in a synaptic vesicle glutamate transporter. Science 2020; 368:893-897. [PMID: 32439795 DOI: 10.1126/science.aba9202] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Accepted: 03/27/2020] [Indexed: 12/28/2022]
Abstract
Synaptic vesicles accumulate neurotransmitters, enabling the quantal release by exocytosis that underlies synaptic transmission. Specific neurotransmitter transporters are responsible for this activity and therefore are essential for brain function. The vesicular glutamate transporters (VGLUTs) concentrate the principal excitatory neurotransmitter glutamate into synaptic vesicles, driven by membrane potential. However, the mechanism by which they do so remains poorly understood owing to a lack of structural information. We report the cryo-electron microscopy structure of rat VGLUT2 at 3.8-angstrom resolution and propose structure-based mechanisms for substrate recognition and allosteric activation by low pH and chloride. A potential permeation pathway for chloride intersects with the glutamate binding site. These results demonstrate how the activity of VGLUTs can be coordinated with large shifts in proton and chloride concentrations during the synaptic vesicle cycle to ensure normal synaptic transmission.
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Affiliation(s)
- Fei Li
- Department of Biochemistry and Biophysics, University of California San Francisco (UCSF) School of Medicine, San Francisco, CA, USA.,Departments of Neurology and Physiology, UCSF School of Medicine, San Francisco, CA, USA
| | - Jacob Eriksen
- Departments of Neurology and Physiology, UCSF School of Medicine, San Francisco, CA, USA
| | - Janet Finer-Moore
- Department of Biochemistry and Biophysics, University of California San Francisco (UCSF) School of Medicine, San Francisco, CA, USA
| | - Roger Chang
- Departments of Neurology and Physiology, UCSF School of Medicine, San Francisco, CA, USA.,Graduate Program in Biomedical Sciences, UCSF, San Francisco, CA, USA
| | - Phuong Nguyen
- Department of Biochemistry and Biophysics, University of California San Francisco (UCSF) School of Medicine, San Francisco, CA, USA
| | - Alisa Bowen
- Department of Biochemistry and Biophysics, University of California San Francisco (UCSF) School of Medicine, San Francisco, CA, USA
| | - Alexander Myasnikov
- Department of Biochemistry and Biophysics, University of California San Francisco (UCSF) School of Medicine, San Francisco, CA, USA
| | - Zanlin Yu
- Department of Biochemistry and Biophysics, University of California San Francisco (UCSF) School of Medicine, San Francisco, CA, USA
| | - David Bulkley
- Department of Biochemistry and Biophysics, University of California San Francisco (UCSF) School of Medicine, San Francisco, CA, USA
| | - Yifan Cheng
- Department of Biochemistry and Biophysics, University of California San Francisco (UCSF) School of Medicine, San Francisco, CA, USA.,Howard Hughes Medical Institute, UCSF, San Francisco, CA, USA
| | - Robert H Edwards
- Departments of Neurology and Physiology, UCSF School of Medicine, San Francisco, CA, USA.
| | - Robert M Stroud
- Department of Biochemistry and Biophysics, University of California San Francisco (UCSF) School of Medicine, San Francisco, CA, USA.
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11
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Pietrancosta N, Djibo M, Daumas S, El Mestikawy S, Erickson JD. Molecular, Structural, Functional, and Pharmacological Sites for Vesicular Glutamate Transporter Regulation. Mol Neurobiol 2020; 57:3118-3142. [PMID: 32474835 PMCID: PMC7261050 DOI: 10.1007/s12035-020-01912-7] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Accepted: 03/30/2020] [Indexed: 12/11/2022]
Abstract
Vesicular glutamate transporters (VGLUTs) control quantal size of glutamatergic transmission and have been the center of numerous studies over the past two decades. VGLUTs contain two independent transport modes that facilitate glutamate packaging into synaptic vesicles and phosphate (Pi) ion transport into the synaptic terminal. While a transmembrane proton electrical gradient established by a vacuolar-type ATPase powers vesicular glutamate transport, recent studies indicate that binding sites and flux properties for chloride, potassium, and protons within VGLUTs themselves regulate VGLUT activity as well. These intrinsic ionic binding and flux properties of VGLUTs can therefore be modulated by neurophysiological conditions to affect levels of glutamate available for release from synapses. Despite their extraordinary importance, specific and high-affinity pharmacological compounds that interact with these sites and regulate VGLUT function, distinguish between the various modes of transport, and the different isoforms themselves, are lacking. In this review, we provide an overview of the physiologic sites for VGLUT regulation that could modulate glutamate release in an over-active synapse or in a disease state.
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Affiliation(s)
- Nicolas Pietrancosta
- Neuroscience Paris Seine - Institut de Biologie Paris Seine (NPS - IBPS) INSERM, CNRS, Sorbonne Université, Paris, France. .,Laboratoire des Biomolécules, Sorbonne Université, CNRS, ENS, LBM, 75005, Paris, France.
| | - Mahamadou Djibo
- Sorbonne Paris Cité, Université Paris Descartes, LCBPT, UMR 8601, 75006, Paris, France
| | - Stephanie Daumas
- Neuroscience Paris Seine - Institut de Biologie Paris Seine (NPS - IBPS) INSERM, CNRS, Sorbonne Université, Paris, France
| | - Salah El Mestikawy
- Neuroscience Paris Seine - Institut de Biologie Paris Seine (NPS - IBPS) INSERM, CNRS, Sorbonne Université, Paris, France. .,Douglas Hospital Research Center, Department of Psychiatry, McGill University, 6875 boulevard Lasalle, Verdun, Montreal, QC, Canada.
| | - Jeffrey D Erickson
- Neuroscience Center, Louisiana State University, New Orleans, LA, 70112, USA. .,Department of Pharmacology, Louisiana State University, New Orleans, LA, 70112, USA.
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12
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Eriksen J, Li F, Edwards RH. The mechanism and regulation of vesicular glutamate transport: Coordination with the synaptic vesicle cycle. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2020; 1862:183259. [PMID: 32147354 DOI: 10.1016/j.bbamem.2020.183259] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2020] [Revised: 03/02/2020] [Accepted: 03/02/2020] [Indexed: 01/30/2023]
Abstract
The transport of classical neurotransmitters into synaptic vesicles generally relies on a H+ electrochemical gradient (∆μH+). Synaptic vesicle uptake of glutamate depends primarily on the electrical component ∆ψ as the driving force, rather than the chemical component ∆pH. However, the vesicular glutamate transporters (VGLUTs) belong to the solute carrier 17 (SLC17) family, which includes closely related members that function as H+ cotransporters. Recent work has also shown that the VGLUTs undergo allosteric regulation by H+ and Cl-, and exhibit an associated Cl- conductance. These properties appear to coordinate VGLUT activity with the large ionic shifts that accompany the rapid recycling of synaptic vesicles driven by neural activity. Recent structural information also suggests common mechanisms that underlie the apparently divergent function of SLC17 family members, and that confer allosteric regulation.
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Affiliation(s)
- Jacob Eriksen
- Department of Physiology, UCSF School of Medicine, United States of America; Department of Neurology, UCSF School of Medicine, United States of America
| | - Fei Li
- Department of Physiology, UCSF School of Medicine, United States of America; Department of Neurology, UCSF School of Medicine, United States of America
| | - Robert H Edwards
- Department of Physiology, UCSF School of Medicine, United States of America; Department of Neurology, UCSF School of Medicine, United States of America.
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13
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Zhang F, Ma C, Jiao Z, Mu S, Zhang Y, Liu X, Zhang H. A NIR Turn-on Fluorescent Sensor For Detection of Chloride Ions in vitro and in vivo. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2020; 228:117729. [PMID: 31740122 DOI: 10.1016/j.saa.2019.117729] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Revised: 10/21/2019] [Accepted: 10/28/2019] [Indexed: 06/10/2023]
Abstract
As the most abundant and significant anions in biosystem, chloride ions (Cl-) participate in many important physiological processes. Thus, designing and synthesizing of a simple, sensitive, selective and long wavelength turn-on sensor for the detection and imaging of Cl- in vitro and in vivo is very necessary. Herein, we have developed a simple porphyrin turn-on sensor 5, 10, 15, 20-Tetrakis (4-hydroxyphenyl) porphyrin (THPP) with near infrared emission wavelength (657 nm) for sensing chloride ions with remarkable sensitivity and selectivity. The detection of chloride ions was according to metal displacement assay (MDA) under physiological condition with a detection limit of 7.5 μM, and was applied to image Cl- in vitro and in vivo successfully.
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Affiliation(s)
- Fengyuan Zhang
- State Key Laboratory of Applied Organic Chemistry and College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou, 730000, China; School of Basic Medical Science, Ningxia Medical University, Yinchuan, 750004, China
| | - Chen Ma
- State Key Laboratory of Applied Organic Chemistry and College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou, 730000, China
| | - Zhijuan Jiao
- State Key Laboratory of Applied Organic Chemistry and College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou, 730000, China
| | - Shuai Mu
- State Key Laboratory of Applied Organic Chemistry and College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou, 730000, China
| | - Yida Zhang
- State Key Laboratory of Applied Organic Chemistry and College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou, 730000, China
| | - Xiaoyan Liu
- State Key Laboratory of Applied Organic Chemistry and College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou, 730000, China
| | - Haixia Zhang
- State Key Laboratory of Applied Organic Chemistry and College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou, 730000, China.
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14
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Thompson CM, Chao CK. VGLUT substrates and inhibitors: A computational viewpoint. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2020; 1862:183175. [PMID: 31923412 DOI: 10.1016/j.bbamem.2020.183175] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Revised: 12/30/2019] [Accepted: 12/31/2019] [Indexed: 02/07/2023]
Abstract
The vesicular glutamate transporters (VGLUTs) bind and move glutamate (Glu) from the cytosol into the lumen of synaptic vesicles using a H+-electrochemical gradient (ΔpH and Δψ) generated by the vesicular H+-ATPase. VGLUTs show very low Glu binding and to date, no three-dimensional structure has been elucidated. Prior studies have attempted to identify the key residues involved in binding VGLUT substrates and inhibitors using homology models and docking experiments. Recently, the inward and outward oriented crystal structures of d-galactonate transporter (DgoT) emerged as possible structure templates for VGLUT. In this review, a new homology model for VGLUT2 based on DgoT has been developed and used to conduct docking experiments to identify and differentiate residues and binding orientations involved in ligand interactions. This review describes small molecule-ligand interactions including docking using a VGLUT2 homology model derived from DgoT.
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Affiliation(s)
- Charles M Thompson
- Center for Structural and Functional Neurosciences, Department of Biomedical and Pharmaceutical Sciences, The University of Montana, Missoula, MT 59812, United States.
| | - Chih-Kai Chao
- Center for Structural and Functional Neurosciences, Department of Biomedical and Pharmaceutical Sciences, The University of Montana, Missoula, MT 59812, United States
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15
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Amino acid transporters in the regulation of insulin secretion and signalling. Biochem Soc Trans 2019; 47:571-590. [PMID: 30936244 DOI: 10.1042/bst20180250] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2018] [Revised: 02/24/2019] [Accepted: 02/25/2019] [Indexed: 01/02/2023]
Abstract
Amino acids are increasingly recognised as modulators of nutrient disposal, including their role in regulating blood glucose through interactions with insulin signalling. More recently, cellular membrane transporters of amino acids have been shown to form a pivotal part of this regulation as they are primarily responsible for controlling cellular and circulating amino acid concentrations. The availability of amino acids regulated by transporters can amplify insulin secretion and modulate insulin signalling in various tissues. In addition, insulin itself can regulate the expression of numerous amino acid transporters. This review focuses on amino acid transporters linked to the regulation of insulin secretion and signalling with a focus on those of the small intestine, pancreatic β-islet cells and insulin-responsive tissues, liver and skeletal muscle. We summarise the role of the amino acid transporter B0AT1 (SLC6A19) and peptide transporter PEPT1 (SLC15A1) in the modulation of global insulin signalling via the liver-secreted hormone fibroblast growth factor 21 (FGF21). The role of vesicular vGLUT (SLC17) and mitochondrial SLC25 transporters in providing glutamate for the potentiation of insulin secretion is covered. We also survey the roles SNAT (SLC38) family and LAT1 (SLC7A5) amino acid transporters play in the regulation of and by insulin in numerous affective tissues. We hypothesise the small intestine amino acid transporter B0AT1 represents a crucial nexus between insulin, FGF21 and incretin hormone signalling pathways. The aim is to give an integrated overview of the important role amino acid transporters have been found to play in insulin-regulated nutrient signalling.
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16
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Zhang F, Ma C, Wang Y, Liu W, Liu X, Zhang H. Fluorescent probes for chloride ions in biological samples. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2018; 205:428-434. [PMID: 30053636 DOI: 10.1016/j.saa.2018.07.060] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2018] [Revised: 07/16/2018] [Accepted: 07/20/2018] [Indexed: 06/08/2023]
Abstract
As one of the most widespread anions, chloride ion largely existed in the water sources as well as living organism. Therefore, determination of chloride ions in biological samples is evidently important. Herein, we developed two analogous fluorescence probes BeQ1 and BeQ2 for the sensitive detection of chloride ions. The chloride ions in biological samples were determined by a direct and simple method with the detection limit of 46 and 66 μM respectively. In addition, the probes were found having the two-photon excitation property.
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Affiliation(s)
- Fengyuan Zhang
- College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, China; School of Basic Medical Science, Ningxia Medical University, Yinchuan 750004, China
| | - Chen Ma
- College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, China
| | - Yaya Wang
- College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, China
| | - Wei Liu
- College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, China
| | - Xiaoyan Liu
- College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, China
| | - Haixia Zhang
- College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, China.
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17
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Zhang FX, Ge SN, Dong YL, Shi J, Feng YP, Li Y, Li YQ, Li JL. Vesicular glutamate transporter isoforms: The essential players in the somatosensory systems. Prog Neurobiol 2018; 171:72-89. [PMID: 30273635 DOI: 10.1016/j.pneurobio.2018.09.006] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2018] [Revised: 08/28/2018] [Accepted: 09/23/2018] [Indexed: 02/08/2023]
Abstract
In nervous system, glutamate transmission is crucial for centripetal conveyance and cortical perception of sensory signals of different modalities, which necessitates vesicular glutamate transporters 1-3 (VGLUT 1-3), the three homologous membrane-bound protein isoforms, to load glutamate into the presysnaptic vesicles. These VGLUTs, especially VGLUT1 and VGLUT2, selectively label and define functionally distinct neuronal subpopulations at each relay level of the neural hierarchies comprising spinal and trigeminal sensory systems. In this review, by scrutinizing each structure of the organism's fundamental hierarchies including dorsal root/trigeminal ganglia, spinal dorsal horn/trigeminal sensory nuclear complex, somatosensory thalamic nuclei and primary somatosensory cortex, we summarize and characterize in detail within each relay the neuronal clusters expressing distinct VGLUT protein/transcript isoforms, with respect to their regional distribution features (complementary distribution in some structures), axonal terminations/peripheral innervations and physiological functions. Equally important, the distribution pattern and characteristics of VGLUT1/VGLUT2 axon terminals within these structures are also epitomized. Finally, the correlation of a particular VGLUT isoform and its physiological role, disclosed thus far largely via studying the peripheral receptors, is generalized by referring to reports on global and conditioned VGLUT-knockout mice. Also, researches on VGLUTs relating to future direction are tentatively proposed, such as unveiling the elusive differences between distinct VGLUTs in mechanism and/or pharmacokinetics at ionic/molecular level, and developing VGLUT-based pain killers.
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Affiliation(s)
- Fu-Xing Zhang
- Department of Anatomy and K.K. Leung Brain Research Centre, School of Basic Medicine, The Fourth Military Medical University, Xi'an 710032, PR China
| | - Shun-Nan Ge
- Department of Anatomy and K.K. Leung Brain Research Centre, School of Basic Medicine, The Fourth Military Medical University, Xi'an 710032, PR China; Department of Neurosurgery, Tangdu Hospital, The Fourth Military Medical University, Xi'an 710038, PR China
| | - Yu-Lin Dong
- Department of Anatomy and K.K. Leung Brain Research Centre, School of Basic Medicine, The Fourth Military Medical University, Xi'an 710032, PR China
| | - Juan Shi
- Department of Anatomy and K.K. Leung Brain Research Centre, School of Basic Medicine, The Fourth Military Medical University, Xi'an 710032, PR China
| | - Yu-Peng Feng
- Department of Anatomy and K.K. Leung Brain Research Centre, School of Basic Medicine, The Fourth Military Medical University, Xi'an 710032, PR China
| | - Yang Li
- Department of Neurosurgery, Tangdu Hospital, The Fourth Military Medical University, Xi'an 710038, PR China
| | - Yun-Qing Li
- Department of Anatomy and K.K. Leung Brain Research Centre, School of Basic Medicine, The Fourth Military Medical University, Xi'an 710032, PR China; Collaborative Innovation Center for Brain Science, Fudan University, Shanghai 200032, PR China.
| | - Jin-Lian Li
- Department of Anatomy and K.K. Leung Brain Research Centre, School of Basic Medicine, The Fourth Military Medical University, Xi'an 710032, PR China.
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18
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Chang R, Eriksen J, Edwards RH. The dual role of chloride in synaptic vesicle glutamate transport. eLife 2018; 7:e34896. [PMID: 30040066 PMCID: PMC6057745 DOI: 10.7554/elife.34896] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2018] [Accepted: 06/07/2018] [Indexed: 01/23/2023] Open
Abstract
The transport of glutamate into synaptic vesicles exhibits an unusual form of regulation by Cl- as well as an associated Cl- conductance. To distinguish direct effects of Cl- on the transporter from indirect effects via the driving force Δψ, we used whole endosome recording and report the first currents due to glutamate flux by the vesicular glutamate transporters (VGLUTs). Chloride allosterically activates the VGLUTs from both sides of the membrane, and we find that neutralization of an arginine in transmembrane domain four suffices for the lumenal activation. The dose dependence suggests that Cl- permeates through a channel and glutamate through a transporter. Competition between the anions nonetheless indicates that they use a similar permeation pathway. By controlling both ionic gradients and Δψ, endosome recording isolates different steps in the process of synaptic vesicle filling, suggesting distinct roles for Cl- in both allosteric activation and permeation.
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Affiliation(s)
- Roger Chang
- Department of PhysiologyUCSF School of MedicineSan FranciscoUnited States
- Department of NeurologyUCSF School of MedicineSan FranciscoUnited States
- Graduate Program in Biomedical SciencesUCSF School of MedicineSan FranciscoUnited States
| | - Jacob Eriksen
- Department of PhysiologyUCSF School of MedicineSan FranciscoUnited States
- Department of NeurologyUCSF School of MedicineSan FranciscoUnited States
| | - Robert H Edwards
- Department of PhysiologyUCSF School of MedicineSan FranciscoUnited States
- Department of NeurologyUCSF School of MedicineSan FranciscoUnited States
- Graduate Program in Biomedical SciencesUCSF School of MedicineSan FranciscoUnited States
- Kavli Institute for Fundamental NeuroscienceUCSF School of MedicineSan FranciscoUnited States
- Weill Institute for NeurosciencesUCSF School of MedicineSan FranciscoUnited States
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19
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Preobraschenski J, Cheret C, Ganzella M, Zander JF, Richter K, Schenck S, Jahn R, Ahnert-Hilger G. Dual and Direction-Selective Mechanisms of Phosphate Transport by the Vesicular Glutamate Transporter. Cell Rep 2018; 23:535-545. [DOI: 10.1016/j.celrep.2018.03.055] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2017] [Revised: 02/13/2018] [Accepted: 03/14/2018] [Indexed: 11/30/2022] Open
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20
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Martineau M, Guzman RE, Fahlke C, Klingauf J. VGLUT1 functions as a glutamate/proton exchanger with chloride channel activity in hippocampal glutamatergic synapses. Nat Commun 2017; 8:2279. [PMID: 29273736 PMCID: PMC5741633 DOI: 10.1038/s41467-017-02367-6] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Accepted: 11/24/2017] [Indexed: 12/18/2022] Open
Abstract
Glutamate is the major excitatory transmitter in the vertebrate nervous system. To maintain synaptic efficacy, recycling synaptic vesicles (SV) are refilled with glutamate by vesicular glutamate transporters (VGLUTs). The dynamics and mechanism of glutamate uptake in intact neurons are still largely unknown. Here, we show by live-cell imaging with pH- and chloride-sensitive fluorescent probes in cultured hippocampal neurons of wild-type and VGLUT1-deficient mice that in SVs VGLUT functions as a glutamate/proton exchanger associated with a channel-like chloride conductance. After endocytosis most internalized Cl− is substituted by glutamate in an electrically, and presumably osmotically, neutral manner, and this process is driven by both the Cl− gradient itself and the proton motive force provided by the vacuolar H+-ATPase. Our results shed light on the transport mechanism of VGLUT under physiological conditions and provide a framework for how modulation of glutamate transport via Cl− and pH can change synaptic strength. During neurotransmission synaptic vesicles are filled with glutamate by vesicular glutamate transporters (VGLUTs). Here, authors image intact neurons and show that in synaptic vesicles VGLUT functions as a glutamate/proton exchanger associated with a channel-like chloride conductance.
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Affiliation(s)
- Magalie Martineau
- Department of Cellular Biophysics, Institute for Medical Physics and Biophysics, University of Muenster, 48149, Muenster, Germany. .,University of Bordeaux and Centre National de la Recherche Scientifique, Interdisciplinary Institute for Neuroscience, UMR 5297, F-33000, Bordeaux, France.
| | - Raul E Guzman
- Institute of Complex Systems, Zelluläre Biophysik (ICS-4), Forschungszentrum Jülich, 52425, Jülich, Germany
| | - Christoph Fahlke
- Institute of Complex Systems, Zelluläre Biophysik (ICS-4), Forschungszentrum Jülich, 52425, Jülich, Germany
| | - Jürgen Klingauf
- Department of Cellular Biophysics, Institute for Medical Physics and Biophysics, University of Muenster, 48149, Muenster, Germany. .,IZKF Münster and Cluster of Excellence EXC 1003, Cells in Motion (CiM), 48149, Muenster, Germany.
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21
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Farsi Z, Jahn R, Woehler A. Proton electrochemical gradient: Driving and regulating neurotransmitter uptake. Bioessays 2017; 39. [PMID: 28383767 DOI: 10.1002/bies.201600240] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Accumulation of neurotransmitters in the lumen of synaptic vesicles (SVs) relies on the activity of the vacuolar-type H+ -ATPase. This pump drives protons into the lumen, generating a proton electrochemical gradient (ΔμH+ ) across the membrane. Recent work has demonstrated that the balance between the chemical (ΔpH) and electrical (ΔΨ) components of ΔμH+ is regulated differently by some distinct vesicle types. As different neurotransmitter transporters use ΔpH and ΔΨ with different relative efficiencies, regulation of this gradient balance has the potential to influence neurotransmitter uptake. Nevertheless, the underlying mechanisms responsible for this regulation remain poorly understood. In this review, we provide an overview of current neurotransmitter uptake models, with a particular emphasis on the distinct roles of the electrical and chemical gradients and current hypotheses for regulatory mechanisms.
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Affiliation(s)
- Zohreh Farsi
- Max-Delbrück Center for Molecular Medicine, Berlin Institute for Medical Systems Biology, Berlin, Germany
| | - Reinhard Jahn
- Department of Neurobiology, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Andrew Woehler
- Max-Delbrück Center for Molecular Medicine, Berlin Institute for Medical Systems Biology, Berlin, Germany
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22
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Neuronal energy consumption: biophysics, efficiency and evolution. Curr Opin Neurobiol 2016; 41:129-135. [DOI: 10.1016/j.conb.2016.09.004] [Citation(s) in RCA: 70] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Revised: 08/25/2016] [Accepted: 09/05/2016] [Indexed: 12/20/2022]
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23
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Effective Mechanism for Synthesis of Neurotransmitter Glutamate and its Loading into Synaptic Vesicles. Neurochem Res 2016; 42:64-76. [DOI: 10.1007/s11064-016-2037-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2016] [Revised: 08/14/2016] [Accepted: 08/17/2016] [Indexed: 01/14/2023]
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24
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Paredes JM, Idilli AI, Mariotti L, Losi G, Arslanbaeva LR, Sato SS, Artoni P, Szczurkowska J, Cancedda L, Ratto GM, Carmignoto G, Arosio D. Synchronous Bioimaging of Intracellular pH and Chloride Based on LSS Fluorescent Protein. ACS Chem Biol 2016; 11:1652-60. [PMID: 27031242 DOI: 10.1021/acschembio.6b00103] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Ion homeostasis regulates critical physiological processes in the living cell. Intracellular chloride concentration not only contributes in setting the membrane potential of quiescent cells but it also plays a role in modulating the dynamic voltage changes during network activity. Dynamic chloride imaging demands new tools, allowing faster acquisition rates and correct accounting of concomitant pH changes. Joining a long-Stokes-shift red-fluorescent protein to a GFP variant with high sensitivity to pH and chloride, we obtained LSSmClopHensor, a genetically encoded fluorescent biosensor optimized for the simultaneous chloride and pH imaging and requiring only two excitation wavelengths (458 and 488 nm). LSSmClopHensor allowed us to monitor the dynamic changes of intracellular pH and chloride concentration during seizure like discharges in neocortical brain slices. Only cells with tightly controlled resting potential revealed a narrow distribution of chloride concentration peaking at about 5 and 8 mM, in neocortical neurons and SK-N-SH cells, respectively. We thus showed that LSSmClopHensor represents a new versatile tool for studying the dynamics of chloride and proton concentration in living systems.
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Affiliation(s)
- Jose M. Paredes
- Institute of Biophysics, CNR, Via
alla Cascata 56/C, 38123 Trento, Italy
- Bruno Kessler Foundation, Via
Sommarive 18, 38123 Trento, Italy
| | - Aurora I. Idilli
- Institute of Biophysics, CNR, Via
alla Cascata 56/C, 38123 Trento, Italy
| | - Letizia Mariotti
- Neuroscience Institute, CNR, Viale
G. Colombo 3, 35121 Padova, Italy
| | - Gabriele Losi
- Neuroscience Institute, CNR, Viale
G. Colombo 3, 35121 Padova, Italy
| | - Lyaysan R. Arslanbaeva
- Institute of Biophysics, CNR, Via
alla Cascata 56/C, 38123 Trento, Italy
- CIBIO, University of Trento, Via delle Regole 101, 38123 Trento, Italy
| | | | | | | | | | - Gian Michele Ratto
- Nanoscience Institute, CNR, Pisa, Italy
- Scuola Normale Superiore, Pisa, Italy
| | | | - Daniele Arosio
- Institute of Biophysics, CNR, Via
alla Cascata 56/C, 38123 Trento, Italy
- CIBIO, University of Trento, Via delle Regole 101, 38123 Trento, Italy
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25
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Eriksen J, Chang R, McGregor M, Silm K, Suzuki T, Edwards RH. Protons Regulate Vesicular Glutamate Transporters through an Allosteric Mechanism. Neuron 2016; 90:768-80. [PMID: 27133463 DOI: 10.1016/j.neuron.2016.03.026] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Revised: 02/25/2016] [Accepted: 03/21/2016] [Indexed: 11/25/2022]
Abstract
The quantal nature of synaptic transmission requires a mechanism to transport neurotransmitter into synaptic vesicles without promoting non-vesicular efflux across the plasma membrane. Indeed, the vesicular transport of most classical transmitters involves a mechanism of H(+) exchange, which restricts flux to acidic membranes such as synaptic vesicles. However, vesicular transport of the principal excitatory transmitter glutamate depends primarily on membrane potential, which would drive non-vesicular efflux, and the role of protons is unclear. Adapting electrophysiology to record currents associated with the vesicular glutamate transporters (VGLUTs), we characterize a chloride conductance that is gated by lumenal protons and chloride and supports glutamate uptake. Rather than coupling stoichiometrically to glutamate flux, lumenal protons and chloride allosterically activate vesicular glutamate transport. Gating by protons serves to inhibit what would otherwise be substantial non-vesicular glutamate efflux at the plasma membrane, thereby restricting VGLUT activity to synaptic vesicles.
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Affiliation(s)
- Jacob Eriksen
- Department of Physiology, UCSF School of Medicine, San Francisco, CA 94143, USA; Department of Neurology, UCSF School of Medicine, San Francisco, CA 94143, USA
| | - Roger Chang
- Department of Physiology, UCSF School of Medicine, San Francisco, CA 94143, USA; Department of Neurology, UCSF School of Medicine, San Francisco, CA 94143, USA; Graduate Program in Biomedical Sciences, UCSF School of Medicine, San Francisco, CA 94143, USA
| | - Matt McGregor
- Department of Physiology, UCSF School of Medicine, San Francisco, CA 94143, USA; Department of Neurology, UCSF School of Medicine, San Francisco, CA 94143, USA; Graduate Program in Neuroscience, UCSF School of Medicine, San Francisco, CA 94143, USA
| | - Katlin Silm
- Department of Physiology, UCSF School of Medicine, San Francisco, CA 94143, USA; Department of Neurology, UCSF School of Medicine, San Francisco, CA 94143, USA
| | - Toshiharu Suzuki
- Faculty of Science and Engineering, Waseda University, Shinjuku-ku, Tokyo 169-8555, Japan
| | - Robert H Edwards
- Department of Physiology, UCSF School of Medicine, San Francisco, CA 94143, USA; Department of Neurology, UCSF School of Medicine, San Francisco, CA 94143, USA; Graduate Program in Biomedical Sciences, UCSF School of Medicine, San Francisco, CA 94143, USA; Graduate Program in Neuroscience, UCSF School of Medicine, San Francisco, CA 94143, USA.
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26
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Takamori S. Presynaptic Molecular Determinants of Quantal Size. Front Synaptic Neurosci 2016; 8:2. [PMID: 26903855 PMCID: PMC4744840 DOI: 10.3389/fnsyn.2016.00002] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2015] [Accepted: 01/25/2016] [Indexed: 01/22/2023] Open
Abstract
The quantal hypothesis for the release of neurotransmitters at the chemical synapse has gained wide acceptance since it was first worked out at the motor endplate in frog skeletal muscle in the 1950’s. Considering the morphological identification of synaptic vesicles (SVs) at the nerve terminals that appeared to be homogeneous in size, the hypothesis proposed that signal transduction at synapses is mediated by the release of neurotransmitters packed in SVs that are individually uniform in size; the amount of transmitter in a synaptic vesicle is called a quantum. Although quantal size—the amplitude of the postsynaptic response elicited by the release of neurotransmitters from a single vesicle—clearly depends on the number and sensitivity of the postsynaptic receptors, accumulating evidence has also indicated that the amount of neurotransmitters stored in SVs can be altered by various presynaptic factors. Here, I provide an overview of the concepts and underlying presynaptic molecular underpinnings that may regulate quantal size.
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Affiliation(s)
- Shigeo Takamori
- Laboratory of Neural Membrane Biology, Graduate School of Brain Science, Doshisha University Kyoto, Japan
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27
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28
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Vesicular glutamate transporters as anion channels? Pflugers Arch 2015; 468:513-8. [DOI: 10.1007/s00424-015-1760-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2015] [Revised: 11/05/2015] [Accepted: 11/12/2015] [Indexed: 01/13/2023]
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29
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Omote H, Miyaji T, Hiasa M, Juge N, Moriyama Y. Structure, Function, and Drug Interactions of Neurotransmitter Transporters in the Postgenomic Era. Annu Rev Pharmacol Toxicol 2015; 56:385-402. [PMID: 26514205 DOI: 10.1146/annurev-pharmtox-010814-124816] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Vesicular neurotransmitter transporters are responsible for the accumulation of neurotransmitters in secretory vesicles and play essential roles in chemical transmission. The SLC17 family contributes to sequestration of anionic neurotransmitters such as glutamate, aspartate, and nucleotides. Identification and subsequent cellular and molecular biological studies of SLC17 transporters unveiled the principles underlying the actions of these transporters. Recent progress in reconstitution methods in combination with postgenomic approaches has advanced studies on neurotransmitter transporters. This review summarizes the molecular properties of SLC17-type transporters and recent findings regarding the novel SLC18 transporter.
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Affiliation(s)
- Hiroshi Omote
- Department of Membrane Biochemistry, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama 700-8530, Japan; ,
| | - Takaaki Miyaji
- Advanced Science Research Center, Okayama University, Okayama 700-8530, Japan
| | - Miki Hiasa
- Department of Membrane Biochemistry, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama 700-8530, Japan; ,
| | - Narinobu Juge
- Advanced Science Research Center, Okayama University, Okayama 700-8530, Japan
| | - Yoshinori Moriyama
- Department of Membrane Biochemistry, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama 700-8530, Japan; , .,Advanced Science Research Center, Okayama University, Okayama 700-8530, Japan
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30
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Hackett JT, Ueda T. Glutamate Release. Neurochem Res 2015; 40:2443-60. [PMID: 26012367 DOI: 10.1007/s11064-015-1622-1] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2015] [Revised: 05/17/2015] [Accepted: 05/20/2015] [Indexed: 12/18/2022]
Abstract
Our aim was to review the processes of glutamate release from both biochemical and neurophysiological points of view. A large body of evidence now indicates that glutamate is specifically accumulated into synaptic vesicles, which provides strong support for the concept that glutamate is released from synaptic vesicles and is the major excitatory neurotransmitter. Evidence suggests the notion that synaptic vesicles, in order to sustain the neurotransmitter pool of glutamate, are endowed with an efficient mechanism for vesicular filling of glutamate. Glutamate-loaded vesicles undergo removal of Synapsin I by CaM kinase II-mediated phosphorylation, transforming to the release-ready pool. Vesicle docking to and fusion with the presynaptic plasma membrane are thought to be mediated by the SNARE complex. The Ca(2+)-dependent step in exocytosis is proposed to be mediated by synaptotagmin.
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Affiliation(s)
- John T Hackett
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA, 22908-0736, USA
| | - Tetsufumi Ueda
- Molecular and Behavioral Neuroscience Institute, The University of Michigan, 109 Zina Pitcher Place, Ann Arbor, MI, 48109-2200, USA. .,Department of Pharmacology, Medical School, The University of Michigan, Ann Arbor, MI, 48109, USA. .,Department of Psychiatry, Medical School, The University of Michigan, Ann Arbor, MI, 48109, USA.
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31
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Influence of Glucose Deprivation on Membrane Potentials of Plasma Membranes, Mitochondria and Synaptic Vesicles in Rat Brain Synaptosomes. Neurochem Res 2015; 40:1188-96. [DOI: 10.1007/s11064-015-1579-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2015] [Revised: 04/02/2015] [Accepted: 04/08/2015] [Indexed: 12/26/2022]
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32
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Preobraschenski J, Zander JF, Suzuki T, Ahnert-Hilger G, Jahn R. Vesicular Glutamate Transporters Use Flexible Anion and Cation Binding Sites for Efficient Accumulation of Neurotransmitter. Neuron 2014; 84:1287-301. [DOI: 10.1016/j.neuron.2014.11.008] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/04/2014] [Indexed: 11/16/2022]
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33
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Omote H, Moriyama Y. Vesicular neurotransmitter transporters: an approach for studying transporters with purified proteins. Physiology (Bethesda) 2014; 28:39-50. [PMID: 23280356 DOI: 10.1152/physiol.00033.2012] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Vesicular storage and subsequent release of neurotransmitters are the key processes of chemical signal transmission. In this process, vesicular neurotransmitter transporters are responsible for loading the signaling molecules. The use of a "clean biochemical" approach with purified, recombinant transporters has helped in the identification of novel vesicular neurotransmitter transporters and in the analysis of the control of signal transmission.
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Affiliation(s)
- Hiroshi Omote
- Department of Membrane Biochemistry, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama University, Okayama, Japan
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34
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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.
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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
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35
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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: 37] [Impact Index Per Article: 3.7] [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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36
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Abstract
After releasing neurotransmitter, synaptic vesicles are retrieved by endocytosis and recycled via fast and slow pathways to be reused for synaptic transmission. To maintain the synaptic efficacy, vesicles must be refilled with neurotransmitter during recycling. However, the refilling speed estimated in isolated or reconstructed vesicles is, thus far, too slow to fill up vesicles within the period of recycling. Here, we re-examined the vesicle refilling rate directly at central glutamatergic synapses in slices, using simultaneous presynaptic and postsynaptic whole-cell recording combined with caged glutamate photolysis. After washing out vesicular glutamate, refilling of vesicles with uncaged glutamate caused a recovery of EPSCs with a time constant of 15 s that varied depending upon temperature, age, and cytosolic Cl(-) concentrations. This time constant is faster than that of the slow recycling pathway (∼30 s) after clathrin-mediated endocytosis but is much too slow to fill up vesicles replenished through fast recycling pathways (<1 s).
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37
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Enhanced glutamate uptake into synaptic vesicles fueled by vesicle-generated ATP from phosphoenolpyruvate and ADP. Proposed role of a novel enzyme. Neurochem Res 2012; 37:2731-7. [PMID: 22915206 DOI: 10.1007/s11064-012-0864-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2012] [Revised: 07/28/2012] [Accepted: 07/31/2012] [Indexed: 10/28/2022]
Abstract
Glycolytic ATP synthesis by synaptic vesicles provides an efficient mechanism for fueling vesicular loading of the neurotransmitter glutamate. This is achieved in part by vesicle-bound pyruvate kinase. However, we have found that vesicular glutamate uptake, in the presence of the pyruvate kinase substrates ADP and phosphoenolpyruvate (PEP), substantially exceeds that caused by exogenous ATP. We propose that this much enhanced uptake is in part due to extra ATP produced via a mechanism involving a novel enzyme, PEP-dependent ADP synthase. We discuss implications for this enzyme in energy homeostasis and pathophysiology, as well as in efficient synaptic glutamate transmission.
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38
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Melkikh AV, Seleznev VD. Mechanisms and models of the active transport of ions and the transformation of energy in intracellular compartments. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2012; 109:33-57. [DOI: 10.1016/j.pbiomolbio.2012.04.008] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2011] [Revised: 04/23/2012] [Accepted: 04/25/2012] [Indexed: 11/26/2022]
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Abreu BJ, Leite LF, Oliveira DL, Amaral E. Synaptic vesicle cycling is not impaired in a glutamatergic and a cholinergic synapse that exhibit deficits in acidification and filling. BRAZ J PHARM SCI 2012. [DOI: 10.1590/s1984-82502012000100017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The purpose of the present work was to investigate synaptic vesicle trafficking when vesicles exhibit alterations in filling and acidification in two different synapses: a cholinergic frog neuromuscular junction and a glutamatergic ribbon-type nerve terminal in the retina. These synapses display remarkable structural and functional differences, and the mechanisms regulating synaptic vesicle cycling might also differ between them. The lipophilic styryl dye FM1-43 was used to monitor vesicle trafficking. Both preparations were exposed to pharmacological agents that collapse ΔpH (NH4Cl and methylamine) or the whole ΔµH+ (bafilomycin), a necessary situation to provide the driving force for neurotransmitter accumulation into synaptic vesicles. The results showed that FM1-43 loading and unloading in neuromuscular junctions did not differ statistically between control and experimental conditions (P > 0.05). Also, FM1-43 labeling in bipolar cell terminals proved highly similar under all conditions tested. Despite remarkable differences in both experimental models, the present findings show that acidification and filling are not required for normal vesicle trafficking in either synapse.
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40
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Blakely RD, Edwards RH. Vesicular and plasma membrane transporters for neurotransmitters. Cold Spring Harb Perspect Biol 2012; 4:a005595. [PMID: 22199021 PMCID: PMC3281572 DOI: 10.1101/cshperspect.a005595] [Citation(s) in RCA: 100] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The regulated exocytosis that mediates chemical signaling at synapses requires mechanisms to coordinate the immediate response to stimulation with the recycling needed to sustain release. Two general classes of transporter contribute to release, one located on synaptic vesicles that loads them with transmitter, and a second at the plasma membrane that both terminates signaling and serves to recycle transmitter for subsequent rounds of release. Originally identified as the target of psychoactive drugs, these transport systems have important roles in transmitter release, but we are only beginning to understand their contribution to synaptic transmission, plasticity, behavior, and disease. Recent work has started to provide a structural basis for their activity, to characterize their trafficking and potential for regulation. The results indicate that far from the passive target of psychoactive drugs, neurotransmitter transporters undergo regulation that contributes to synaptic plasticity.
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Affiliation(s)
- Randy D Blakely
- Department of Pharmacology and Psychiatry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-8548, USA
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41
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Budzinski KL, Zeigler M, Fujimoto BS, Bajjalieh SM, Chiu DT. Measurements of the acidification kinetics of single SynaptopHluorin vesicles. Biophys J 2012; 101:1580-9. [PMID: 21961583 DOI: 10.1016/j.bpj.2011.08.032] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2011] [Revised: 08/15/2011] [Accepted: 08/19/2011] [Indexed: 11/29/2022] Open
Abstract
Uptake of neurotransmitters into synaptic vesicles is driven by the proton gradient established across the vesicle membrane. The acidification of synaptic vesicles, therefore, is a crucial component of vesicle function. Here we present measurements of acidification rate constants from isolated, single synaptic vesicles. Vesicles were purified from mice expressing a fusion protein termed SynaptopHluorin created by the fusion of VAMP/synaptobrevin to the pH-sensitive super-ecliptic green fluorescent protein. We calibrated SynaptopHluorin fluorescence to determine the relationship between fluorescence intensity and internal vesicle pH, and used these values to measure the rate constant of vesicle acidification. We also measured the effects of ATP, glutamate, and chloride on acidification. We report acidification time constants of 500 ms to 1 s. The rate of acidification increased with increasing extravesicular concentrations of ATP and glutamate. These data provide an upper and a lower bound for vesicle acidification and indicate that vesicle readiness can be regulated by changes in energy and transmitter availability.
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Affiliation(s)
- Kristi L Budzinski
- Department of Chemistry, University of Washington, Seattle, Washington, USA
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42
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Abstract
In the human brain, ≈30% of the energy is spent on synaptic transmission. Disappearance of synaptic activity is the earliest consequence of cerebral ischemia. The changes of synaptic function are generally assumed to be reversible and persistent damage is associated with membrane failure and neuronal death. However, there is overwhelming experimental evidence of isolated, but persistent, synaptic failure resulting from mild or moderate cerebral ischemia. Early failure results from presynaptic damage with impaired transmitter release. Proposed mechanisms include dysfunction of adenosine triphosphate-dependent calcium channels and a disturbed docking of glutamate-containing vesicles resulting from impaired phosphorylation. We review energy distribution among neuronal functions, focusing on energy usage of synaptic transmission. We summarize the effect of ischemia on neurotransmission and the evidence of long-lasting synaptic failure as a cause of persistent symptoms in patients with cerebral ischemia. Finally, we discuss the implications of synaptic failure in the diagnosis of cerebral ischemia, including the limited sensitivity of diffusion-weighted MRI in those cases in which damage is presumably limited to the synapses.
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Affiliation(s)
- Jeannette Hofmeijer
- Department of Neurology, Rijnstate Hospital, Wagnerlaan 55, 6815 AD Arnhem, The Netherlands.
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43
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Abstract
Neurotransmitter identity is a defining feature of all neurons because it constrains the type of information they convey, but many neurons release multiple transmitters. Although the physiological role for corelease has remained poorly understood, the vesicular uptake of one transmitter can regulate filling with the other by influencing expression of the H(+) electrochemical driving force. In addition, the sorting of vesicular neurotransmitter transporters and other synaptic vesicle proteins into different vesicle pools suggests the potential for distinct modes of release. Corelease thus serves multiple roles in synaptic transmission.
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Affiliation(s)
- Thomas S Hnasko
- Departments of Physiology & Neurology, University of California, San Francisco, California 94158-2517, USA.
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44
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Presynaptic regulation of quantal size: K+/H+ exchange stimulates vesicular glutamate transport. Nat Neurosci 2011; 14:1285-92. [PMID: 21874016 PMCID: PMC3183113 DOI: 10.1038/nn.2898] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2011] [Accepted: 07/11/2011] [Indexed: 11/29/2022]
Abstract
The amount of neurotransmitter stored in a single synaptic vesicle can determine the size of the postsynaptic response, but the factors that regulate vesicle filling remain poorly understood. A proton electrochemical gradient (ΔμH+) generated by the vacuolar H+-ATPase drives the accumulation of classical transmitters into synaptic vesicles. The chemical component of ΔμH+ (ΔpH) has received particular attention for its role in the vesicular transport of cationic transmitters as well as protein sorting and degradation. Thus, considerable work has addressed the factors that promote ΔpH. However, synaptic vesicle uptake of the principal excitatory transmitter glutamate depends on the electrical component of ΔμH+ (Δψ). We now find that rat brain synaptic vesicles express monovalent cation/H+ exchange activity that converts ΔpH into Δψ, and this promotes synaptic vesicle filling with glutamate. Manipulating presynaptic K+ at a glutamatergic synapse influences quantal size, demonstrating that synaptic vesicle K+/H+ exchange regulates glutamate release and synaptic transmission.
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45
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Omote H, Miyaji T, Juge N, Moriyama Y. Vesicular Neurotransmitter Transporter: Bioenergetics and Regulation of Glutamate Transport. Biochemistry 2011; 50:5558-65. [DOI: 10.1021/bi200567k] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Affiliation(s)
- Hiroshi Omote
- Department of Membrane Biochemistry, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama 700-8530, Japan
| | - Takaaki Miyaji
- Advanced Science Research Center, Okayama University, Okayama 700-8530, Japan
| | - Narinobu Juge
- Department of Membrane Biochemistry, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama 700-8530, Japan
| | - Yoshinori Moriyama
- Department of Membrane Biochemistry, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama 700-8530, Japan
- Advanced Science Research Center, Okayama University, Okayama 700-8530, Japan
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46
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Glutamine is required for persistent epileptiform activity in the disinhibited neocortical brain slice. J Neurosci 2010; 30:1288-300. [PMID: 20107056 DOI: 10.1523/jneurosci.0106-09.2010] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The neurotransmitter glutamate is recycled through an astrocytic-neuronal glutamate-glutamine cycle in which synaptic glutamate is taken up by astrocytes, metabolized to glutamine, and transferred to neurons for conversion back to glutamate and subsequent release. The extent to which neuronal glutamate release is dependent upon this pathway remains unclear. Here we provide electrophysiological and biochemical evidence that in acutely disinhibited rat neocortical slices, robust release of glutamate during sustained epileptiform activity requires that neurons be provided a continuous source of glutamine. We demonstrate that the uptake of glutamine into neurons for synthesis of glutamate destined for synaptic release is not strongly dependent on the system A transporters, but requires another unidentified glutamine transporter or transporters. Finally, we find that the attenuation of network activity through inhibition of neuronal glutamine transport is associated with reduced frequency and amplitude of spontaneous events detected at the single-cell level. These results indicate that availability of glutamine influences neuronal release of glutamate during periods of intense network activity.
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Hnasko TS, Chuhma N, Zhang H, Goh GY, Sulzer D, Palmiter RD, Rayport S, Edwards RH. Vesicular glutamate transport promotes dopamine storage and glutamate corelease in vivo. Neuron 2010; 65:643-56. [PMID: 20223200 DOI: 10.1016/j.neuron.2010.02.012] [Citation(s) in RCA: 299] [Impact Index Per Article: 21.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/09/2010] [Indexed: 01/03/2023]
Abstract
Dopamine neurons in the ventral tegmental area (VTA) play an important role in the motivational systems underlying drug addiction, and recent work has suggested that they also release the excitatory neurotransmitter glutamate. To assess a physiological role for glutamate corelease, we disrupted the expression of vesicular glutamate transporter 2 selectively in dopamine neurons. The conditional knockout abolishes glutamate release from midbrain dopamine neurons in culture and severely reduces their excitatory synaptic output in mesoaccumbens slices. Baseline motor behavior is not affected, but stimulation of locomotor activity by cocaine is impaired, apparently through a selective reduction of dopamine stores in the projection of VTA neurons to ventral striatum. Glutamate co-entry promotes monoamine storage by increasing the pH gradient that drives vesicular monoamine transport. Remarkably, low concentrations of glutamate acidify synaptic vesicles more slowly but to a greater extent than equimolar Cl(-), indicating a distinct, presynaptic mechanism to regulate quantal size.
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Affiliation(s)
- Thomas S Hnasko
- Departments of Physiology and Neurology, University of California, San Francisco, San Francisco, CA 94158, USA
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48
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A chloride conductance in VGLUT1 underlies maximal glutamate loading into synaptic vesicles. Nat Neurosci 2009; 12:156-62. [DOI: 10.1038/nn.2248] [Citation(s) in RCA: 111] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2008] [Accepted: 12/02/2008] [Indexed: 11/08/2022]
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49
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Schober MS, Chidlow G, Wood JP, Casson RJ. Bioenergetic-based neuroprotection and glaucoma. Clin Exp Ophthalmol 2008; 36:377-85. [PMID: 18700928 DOI: 10.1111/j.1442-9071.2008.01740.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Primary open-angle glaucoma (POAG) is a pressure-sensitive optic neuropathy which results in the death of retinal ganglion cells and causes associated loss of vision. Presently, the only accepted treatment strategy is to lower the intraocular pressure; however, for some patients this is insufficient to prevent progressive disease. Although the pathogenesis of POAG remains unclear, there is considerable evidence that energy failure at the optic nerve head may be involved. Neuroprotection, a strategy which directly enhances the survival of neurons, is desirable, but remains clinically elusive. One particular form of neuroprotection involves the notion of enhancing the energy supply of neurons. These 'bioenergetic' methods of neuroprotection have proven successful in animal models of other neurodegenerative diseases and conditions, including Parkinson's disease, Huntington's disease, amyotrophic lateral sclerosis and traumatic brain injury, but have been relatively unexplored in glaucoma models. This review focuses on some of the potential approaches for bioenergetic neuroprotection in the retina, including increasing the energy buffering capacity of damaged cells, decreasing the permeability of the mitochondrial membrane pore and free radical scavenging.
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Affiliation(s)
- Michael S Schober
- South Australian Institute of Ophthalmology, Adelaide, South Australia, Australia.
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50
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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: 23] [Impact Index Per Article: 1.4] [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.
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