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Bleier J, Furtado de Mendonca PR, Habrian CH, Stanley C, Vyklicky V, Isacoff EY. Subtype-specific conformational landscape of NMDA receptor gating. Cell Rep 2024; 43:114634. [PMID: 39154344 DOI: 10.1016/j.celrep.2024.114634] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2024] [Revised: 06/22/2024] [Accepted: 07/30/2024] [Indexed: 08/20/2024] Open
Abstract
N-methyl-D-aspartate receptors are ionotropic glutamate receptors that mediate synaptic transmission and plasticity. Variable GluN2 subunits in diheterotetrameric receptors with identical GluN1 subunits set very different functional properties. To understand this diversity, we use single-molecule fluorescence resonance energy transfer (smFRET) to measure the conformations of the ligand binding domain and modulatory amino-terminal domain of the common GluN1 subunit in receptors with different GluN2 subunits. Our results demonstrate a strong influence of the GluN2 subunits on GluN1 rearrangements, both in non-agonized and partially agonized activation intermediates, which have been elusive to structural analysis, and in the fully liganded state. Chimeric analysis reveals structural determinants that contribute to these subtype differences. Our study provides a framework for understanding the conformational landscape that supports highly divergent levels of activity, desensitization, and agonist potency in receptors with different GluN2s and could open avenues for the development of subtype-specific modulators.
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Affiliation(s)
- Julia Bleier
- Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, CA 94720, USA
| | | | - Chris H Habrian
- Biophysics Graduate Group, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Cherise Stanley
- Department of Molecular & Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Vojtech Vyklicky
- Department of Molecular & Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Ehud Y Isacoff
- Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, CA 94720, USA; Department of Molecular & Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA; Weill Neurohub, University of California, Berkeley, Berkeley, CA 94720, USA; Molecular Biology & Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
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2
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Bender PA, Chakraborty S, Durham RJ, Berka V, Carrillo E, Jayaraman V. Bi-directional allosteric pathway in NMDA receptor activation and modulation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.16.589813. [PMID: 38659769 PMCID: PMC11042370 DOI: 10.1101/2024.04.16.589813] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/26/2024]
Abstract
N-methyl-D-aspartate (NMDA) receptors are ionotropic glutamate receptors involved in learning and memory. NMDA receptors primarily comprise two GluN1 and two GluN2 subunits. The GluN2 subunit dictates biophysical receptor properties, including the extent of receptor activation and desensitization. GluN2A- and GluN2D-containing receptors represent two functional extremes. To uncover the conformational basis of their functional divergence, we utilized single-molecule fluorescence resonance energy transfer to probe the extracellular domains of these receptor subtypes under resting and ligand-bound conditions. We find that the conformational profile of the GluN2 amino-terminal domain correlates with the disparate functions of GluN2A- and GluN2D-containing receptors. Changes at the pre-transmembrane segments inversely correlate with those observed at the amino-terminal domain, confirming direct allosteric communication between these domains. Additionally, binding of a positive allosteric modulator at the transmembrane domain shifts the conformational profile of the amino-terminal domain towards the active state, revealing a bidirectional allosteric pathway between extracellular and transmembrane domains.
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3
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Bleier J, de Mendonca PRF, Habrian C, Stanley C, Vyklicky V, Isacoff EY. Conformational basis of subtype-specific allosteric control of NMDA receptor gating. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.10.579740. [PMID: 38370786 PMCID: PMC10871359 DOI: 10.1101/2024.02.10.579740] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/20/2024]
Abstract
N-methyl-D-aspartate receptors are ionotropic glutamate receptors that are integral to synaptic transmission and plasticity. Variable GluN2 subunits in diheterotetrameric receptors with identical GluN1 subunits set very different functional properties, which support their individual physiological roles in the nervous system. To understand the conformational basis of this diversity, we assessed the conformation of the common GluN1 subunit in receptors with different GluN2 subunits using single-molecule fluorescence resonance energy transfer (smFRET). We established smFRET sensors in the ligand binding domain and modulatory amino-terminal domain to study an apo-like state and partially liganded activation intermediates, which have been elusive to structural analysis. Our results demonstrate a strong, subtype-specific influence of apo and glutamate-bound GluN2 subunits on GluN1 rearrangements, suggesting a conformational basis for the highly divergent levels of receptor activity, desensitization and agonist potency. Chimeric analysis reveals structural determinants that contribute to the subtype differences. Our study provides a framework for understanding GluN2-dependent functional properties and could open new avenues for subtype-specific modulation.
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Affiliation(s)
- Julia Bleier
- Helen Wills Neuroscience Institute, University of California, Berkeley, California, 94720 USA
| | | | - Chris Habrian
- Department of Molecular & Cell Biology, University of California, Berkeley, California, 94720 USA
- Current address: Department of Molecular and Cellular Physiology, Stanford University School of Medicine, 279 Campus Drive, Stanford, CA 94305, USA
| | - Cherise Stanley
- Department of Molecular & Cell Biology, University of California, Berkeley, California, 94720 USA
| | - Vojtech Vyklicky
- Department of Molecular & Cell Biology, University of California, Berkeley, California, 94720 USA
- Current address: DIANA Biotechnologies, a.s. Průmyslová 596, 252 50 Vestec, Czech Republic
| | - Ehud Y. Isacoff
- Helen Wills Neuroscience Institute, University of California, Berkeley, California, 94720 USA
- Department of Molecular & Cell Biology, University of California, Berkeley, California, 94720 USA
- Weill Neurohub, University of California, Berkeley, California, 94720 USA
- Molecular Biology & Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, California, 94720, USA
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4
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Fradley R, Goetghebeur P, Miller D, Burley R, Almond S, Gruart I Massó A, Delgado García JM, Zhu B, Howley E, Neill JC, Grayson B, Gaskin P, Carlton M, Gray I, Serrats J, Davies CH. Luvadaxistat: A Novel Potent and Selective D-Amino Acid Oxidase Inhibitor Improves Cognitive and Social Deficits in Rodent Models for Schizophrenia. Neurochem Res 2023; 48:3027-3041. [PMID: 37289348 PMCID: PMC10471729 DOI: 10.1007/s11064-023-03956-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2023] [Revised: 05/17/2023] [Accepted: 05/21/2023] [Indexed: 06/09/2023]
Abstract
N-methyl-D-aspartate (NMDA) receptor hypofunctionality is a well-studied hypothesis for schizophrenia pathophysiology, and daily dosing of the NMDA receptor co-agonist, D-serine, in clinical trials has shown positive effects in patients. Therefore, inhibition of D-amino acid oxidase (DAAO) has the potential to be a new therapeutic approach for the treatment of schizophrenia. TAK-831 (luvadaxistat), a novel, highly potent inhibitor of DAAO, significantly increases D-serine levels in the rodent brain, plasma, and cerebrospinal fluid. This study shows luvadaxistat to be efficacious in animal tests of cognition and in a translational animal model for cognitive impairment in schizophrenia. This is demonstrated when luvadaxistat is dosed alone and in conjunction with a typical antipsychotic. When dosed chronically, there is a suggestion of change in synaptic plasticity as seen by a leftward shift in the maximum efficacious dose in several studies. This is suggestive of enhanced activation of NMDA receptors in the brain and confirmed by modulation of long-term potentiation after chronic dosing. DAAO is highly expressed in the cerebellum, an area of increasing interest for schizophrenia, and luvadaxistat was shown to be efficacious in a cerebellar-dependent associative learning task. While luvadaxistat ameliorated the deficit seen in sociability in two different negative symptom tests of social interaction, it failed to show an effect in endpoints of negative symptoms in clinical trials. These results suggest that luvadaxistat potentially could be used to improve cognitive impairment in patients with schizophrenia, which is not well addressed with current antipsychotic medications.
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Affiliation(s)
- Rosa Fradley
- Neuroscience Drug Discovery Unit, Takeda, Cambridge, UK
| | | | - David Miller
- Neuroscience Drug Discovery Unit, Takeda, Cambridge, UK
| | | | - Sarah Almond
- Neuroscience Drug Discovery Unit, Takeda, Cambridge, UK
| | | | | | - Bin Zhu
- Neuroscience Drug Discovery Unit, Takeda, Cambridge, UK
| | - Eimear Howley
- Neuroscience Drug Discovery Unit, Takeda, Cambridge, UK
| | - Jo C Neill
- Division of Pharmacy and Optometry, School of Health Sciences, University of Manchester, Manchester, UK
| | - Ben Grayson
- Division of Pharmacy and Optometry, School of Health Sciences, University of Manchester, Manchester, UK
| | - Philip Gaskin
- Neuroscience Drug Discovery Unit, Takeda, Cambridge, UK
| | - Mark Carlton
- Neuroscience Drug Discovery Unit, Takeda, Cambridge, UK
| | - Ian Gray
- Neuroscience Drug Discovery Unit, Takeda, Cambridge, UK
| | - Jordi Serrats
- Neuroscience Drug Discovery Unit, Takeda California, 9625 Towne Centre Dr, San Diego, CA, 92121, USA.
| | - Ceri H Davies
- Takeda Pharmaceuticals Company Limited, Fujisawa, Kanagawa, Japan
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5
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Elmasri M, Hunter DW, Winchester G, Bates EE, Aziz W, Van Der Does DM, Karachaliou E, Sakimura K, Penn AC. Common synaptic phenotypes arising from diverse mutations in the human NMDA receptor subunit GluN2A. Commun Biol 2022; 5:174. [PMID: 35228668 PMCID: PMC8885697 DOI: 10.1038/s42003-022-03115-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Accepted: 01/31/2022] [Indexed: 02/06/2023] Open
Abstract
Dominant mutations in the human gene GRIN2A, encoding NMDA receptor (NMDAR) subunit GluN2A, make a significant and growing contribution to the catalogue of published single-gene epilepsies. Understanding the disease mechanism in these epilepsy patients is complicated by the surprising diversity of effects that the mutations have on NMDARs. Here we have examined the cell-autonomous effect of five GluN2A mutations, 3 loss-of-function and 2 gain-of-function, on evoked NMDAR-mediated synaptic currents (NMDA-EPSCs) in CA1 pyramidal neurons in cultured hippocampal slices. Despite the mutants differing in their functional incorporation at synapses, prolonged NMDA-EPSC current decays (with only marginal changes in charge transfer) were a common effect for both gain- and loss-of-function mutants. Modelling NMDA-EPSCs with mutant properties in a CA1 neuron revealed that the effect of GRIN2A mutations can lead to abnormal temporal integration and spine calcium dynamics during trains of concerted synaptic activity. Investigations beyond establishing the molecular defects of GluN2A mutants are much needed to understand their impact on synaptic transmission. The cell-autonomous effect of five severe loss- or gain-of-function GluN2A (NMDA receptor) mutations is assessed on evoked NMDAR-mediated synaptic currents in CA1 pyramidal neurons in cultured mouse hippocampal slices. Data and modelling suggest that mutant-like NMDA-EPSCs can lead to abnormal temporal summation and spine calcium dynamics.
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Affiliation(s)
- Marwa Elmasri
- Sussex Neuroscience, School of Life Sciences, University of Sussex, Brighton, BN1 9QG, UK
| | - Daniel William Hunter
- Sussex Neuroscience, School of Life Sciences, University of Sussex, Brighton, BN1 9QG, UK
| | - Giles Winchester
- Sussex Neuroscience, School of Life Sciences, University of Sussex, Brighton, BN1 9QG, UK
| | - Ella Emine Bates
- Sussex Neuroscience, School of Life Sciences, University of Sussex, Brighton, BN1 9QG, UK
| | - Wajeeha Aziz
- Sussex Neuroscience, School of Life Sciences, University of Sussex, Brighton, BN1 9QG, UK
| | | | - Eirini Karachaliou
- Sussex Neuroscience, School of Life Sciences, University of Sussex, Brighton, BN1 9QG, UK
| | - Kenji Sakimura
- Department of Cellular Neurobiology, Brain Research Institute, Niigata University, Niigata, 951-8585, Japan
| | - Andrew Charles Penn
- Sussex Neuroscience, School of Life Sciences, University of Sussex, Brighton, BN1 9QG, UK.
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6
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Langer K, Müller-Längle A, Wempe J, Laube B. Analysis of M4 Transmembrane Segments in NMDA Receptor Function: A Negative Allosteric Modulatory Site at the GluN1 M4 is Determining the Efficiency of Neurosteroid Modulation. Front Pharmacol 2021; 12:769046. [PMID: 34658899 PMCID: PMC8517087 DOI: 10.3389/fphar.2021.769046] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Accepted: 09/20/2021] [Indexed: 11/13/2022] Open
Abstract
Ionotropic glutamate receptors (iGluRs) are tetrameric ligand-gated ion channels that play a crucial role in excitatory synaptic transmission in the central nervous system. Each subunit contributes with three helical transmembrane segments (M1, M3, and M4) and a pore loop (M2) to form the channel pore. Recent studies suggest that the architecture of all eukaryotic iGluRs derives from a common prokaryotic ancestral receptor that lacks M4 and consists only of transmembrane segments M1 and M3. Although significant contribution has emerged in the last years, the role of this additionally evolved transmembrane segment in iGluR assembly and function remains unclear. Here, we have investigated how deletions and mutations of M4 in members of the NMDA receptor (NMDAR) subfamily, the conventional heteromeric GluN1/GluN2 and glycine-gated GluN1/GluN3 NMDARs, affect expression and function in Xenopus oocytes. We show that deletion of M4 in the GluN1, GluN2A, or GluN3A subunit, despite retained receptor assembly and cell surface expression, results in nonfunctional membrane receptors. Coexpression of the corresponding M4 as an isolated peptide in M4-deleted receptors rescued receptor function of GluN1/GluN2A NMDARs without altering the apparent affinity of glutamate or glycine. Electrophysiological analyses of agonist-induced receptor function and its modulation by the neurosteroid pregnenolone sulfate (PS) at mutations of the GluN1-M4/GluN2/3-transmembrane interfaces indicate a crucial role of position M813 in M4 of GluN1 for functional coupling to the core receptor and the negative modulatory effects of PS. Substitution of residues and insertion of interhelical disulfide bridges confirmed interhelical interactions of positions in M4 of GluN1 with residues of transmembrane segments of neighboring subunits. Our results show that although M4s in NMDARs are not important for receptor assembly and surface expression, the residues at the subunit interface are substantially involved in M4 recognition of the core receptor and regulation of PS efficacy. Because mutations in the M4 of GluN1 specifically resulted in loss of PS-induced inhibition of GluN1/GluN2A and GluN1/GluN3A NMDAR currents, our results point to distinct roles of M4s in NMDAR modulation and highlight the importance of the evolutionarily newly evolved M4 for selective in vivo modulation of glutamate- and glycine-activated NMDARs by steroids.
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Affiliation(s)
- Kai Langer
- Department of Neurophysiology and Neurosensory Systems, Technische Universität Darmstadt, Darmstadt, Germany
| | - Adriana Müller-Längle
- Department of Neurophysiology and Neurosensory Systems, Technische Universität Darmstadt, Darmstadt, Germany
| | - Jannik Wempe
- Department of Neurophysiology and Neurosensory Systems, Technische Universität Darmstadt, Darmstadt, Germany
| | - Bodo Laube
- Department of Neurophysiology and Neurosensory Systems, Technische Universität Darmstadt, Darmstadt, Germany.,Centre for Synthetic Biology, Technical University of Darmstadt, Darmstadt, Germany
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7
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Postsynaptic Serine Racemase Regulates NMDA Receptor Function. J Neurosci 2020; 40:9564-9575. [PMID: 33158959 DOI: 10.1523/jneurosci.1525-20.2020] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Revised: 10/23/2020] [Accepted: 11/01/2020] [Indexed: 01/03/2023] Open
Abstract
d-serine is the primary NMDAR coagonist at mature forebrain synapses and is synthesized by the enzyme serine racemase (SR). However, our understanding of the mechanisms regulating the availability of synaptic d-serine remains limited. Though early studies suggested d-serine is synthesized and released from astrocytes, more recent studies have demonstrated a predominantly neuronal localization of SR. More specifically, recent work intriguingly suggests that SR may be found at the postsynaptic density, yet the functional implications of postsynaptic SR on synaptic transmission are not yet known. Here, we show an age-dependent dendritic and postsynaptic localization of SR and d-serine by immunohistochemistry and electron microscopy in mouse CA1 pyramidal neurons. In addition, using a single-neuron genetic approach in SR conditional KO mice from both sexes, we demonstrate a cell-autonomous role for SR in regulating synaptic NMDAR function at Schaffer collateral (CA3)-CA1 synapses. Importantly, single-neuron genetic deletion of SR resulted in the elimination of LTP at 1 month of age, which could be rescued by exogenous d-serine. Interestingly, there was a restoration of LTP by 2 months of age that was associated with an upregulation of synaptic GluN2B. Our findings support a cell-autonomous role for postsynaptic neuronal SR in regulating synaptic NMDAR function and suggests a possible autocrine mode of d-serine action.SIGNIFICANCE STATEMENT NMDARs are key regulators of neurodevelopment and synaptic plasticity and are unique in their requirement for binding of a coagonist, which is d-serine at most forebrain synapses. However, our understanding of the mechanisms regulating synaptic d-serine availability remains limited. d-serine is synthesized in the brain by the neuronal enzyme serine racemase (SR). Here, we show dendritic and postsynaptic localization of SR and d-serine in CA1 pyramidal neurons. In addition, using single-neuron genetic deletion of SR, we establish a role of postsynaptic SR in regulating NMDAR function. These results support an autocrine mode of d-serine action at synapses.
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8
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Sengar AS, Li H, Zhang W, Leung C, Ramani AK, Saw NM, Wang Y, Tu Y, Ross PJ, Scherer SW, Ellis J, Brudno M, Jia Z, Salter MW. Control of Long-Term Synaptic Potentiation and Learning by Alternative Splicing of the NMDA Receptor Subunit GluN1. Cell Rep 2020; 29:4285-4294.e5. [PMID: 31875540 DOI: 10.1016/j.celrep.2019.11.087] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2019] [Revised: 10/05/2019] [Accepted: 11/21/2019] [Indexed: 01/09/2023] Open
Abstract
NMDA receptors (NMDARs) are critical for physiological synaptic plasticity, learning, and memory and for pathological plasticity and neuronal death. The GluN1 subunit is encoded by a single gene, GRIN1, with 8 splice variants, but whether the diversity generated by this splicing has physiological consequences remains enigmatic. Here, we generate mice lacking from the GluN1 exon 5-encoded N1 cassette (GluN1a mice) or compulsorily expressing this exon (GluN1b mice). Despite no differences in basal synaptic transmission, long-term potentiation in the hippocampus is significantly enhanced in GluN1a mice compared with that in GluN1b mice. Furthermore, GluN1a mice learn more quickly and have significantly better spatial memory performance than do GluN1b mice. In addition, in human iPSC-derived neurons in autism spectrum disorder NMDARs show characteristics of N1-lacking GluN1. Our findings indicate that alternative splicing of GluN1 is a mechanism for controlling physiological long-lasting synaptic potentiation, learning, and memory.
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Affiliation(s)
- Ameet S Sengar
- Program in Neurosciences & Mental Health, The Hospital for Sick Children, Toronto, ON M5G 1X8, Canada
| | - Hongbin Li
- Program in Neurosciences & Mental Health, The Hospital for Sick Children, Toronto, ON M5G 1X8, Canada
| | - Wenbo Zhang
- Program in Neurosciences & Mental Health, The Hospital for Sick Children, Toronto, ON M5G 1X8, Canada
| | - Celeste Leung
- Program in Neurosciences & Mental Health, The Hospital for Sick Children, Toronto, ON M5G 1X8, Canada; Department of Physiology, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Arun K Ramani
- Centre for Computational Medicine, The Hospital for Sick Children, Toronto, ON M5G 1X8, Canada
| | - Ner Mu Saw
- Program in Neurosciences & Mental Health, The Hospital for Sick Children, Toronto, ON M5G 1X8, Canada; Department of Physiology, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Yongqian Wang
- Program in Neurosciences & Mental Health, The Hospital for Sick Children, Toronto, ON M5G 1X8, Canada
| | - YuShan Tu
- Program in Neurosciences & Mental Health, The Hospital for Sick Children, Toronto, ON M5G 1X8, Canada
| | - P Joel Ross
- Biology Department, University of Prince Edward Island, Charlottetown, PE C1A 4P3, Canada
| | - Stephen W Scherer
- Program in Genetics and Genome Biology, The Hospital for Sick Children, Toronto, ON M5G 1X8, Canada; The Centre for Applied Genomics, The Hospital for Sick Children, Toronto, ON M5G 1X8, Canada; Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 1A8, Canada; McLaughlin Centre, University of Toronto, Toronto, ON M5G 0A4, Canada
| | - James Ellis
- Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 1A8, Canada; Program in Developmental and Stem Cell Biology, The Hospital for Sick Children, Toronto, ON M5G 1X8, Canada
| | - Michael Brudno
- Centre for Computational Medicine, The Hospital for Sick Children, Toronto, ON M5G 1X8, Canada; Program in Genetics and Genome Biology, The Hospital for Sick Children, Toronto, ON M5G 1X8, Canada; Department of Computer Science, University of Toronto, Toronto, ON M5T 3A1, Canada
| | - Zhengping Jia
- Program in Neurosciences & Mental Health, The Hospital for Sick Children, Toronto, ON M5G 1X8, Canada; Department of Physiology, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Michael W Salter
- Program in Neurosciences & Mental Health, The Hospital for Sick Children, Toronto, ON M5G 1X8, Canada; Department of Physiology, University of Toronto, Toronto, ON M5S 1A8, Canada.
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9
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PCDH7 interacts with GluN1 and regulates dendritic spine morphology and synaptic function. Sci Rep 2020; 10:10951. [PMID: 32616769 PMCID: PMC7331671 DOI: 10.1038/s41598-020-67831-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Accepted: 06/12/2020] [Indexed: 01/28/2023] Open
Abstract
The N-terminal domain (NTD) of the GluN1 subunit (GluN1-NTD) is important for NMDA receptor structure and function, but the interacting proteins of the GluN1-NTD are not well understood. Starting with an unbiased screen of ~ 1,500 transmembrane proteins using the purified GluN1-NTD protein as a bait, we identify Protocadherin 7 (PCDH7) as a potential interacting protein. PCDH7 is highly expressed in the brain and has been linked to CNS disorders, including epilepsy. Using primary neurons and brain slice cultures, we find that overexpression and knockdown of PCDH7 induce opposing morphological changes of dendritic structures. We also find that PCDH7 overexpression reduces synaptic NMDA receptor currents. These data show that PCDH7 can regulate dendritic spine morphology and synaptic function, possibly via interaction with the GluN1 subunit.
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10
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Schönrock M, Thiel G, Laube B. Coupling of a viral K +-channel with a glutamate-binding-domain highlights the modular design of ionotropic glutamate-receptors. Commun Biol 2019; 2:75. [PMID: 30820470 PMCID: PMC6385376 DOI: 10.1038/s42003-019-0320-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2018] [Accepted: 01/22/2019] [Indexed: 01/12/2023] Open
Abstract
Ionotropic glutamate receptors (iGluRs) mediate excitatory neuronal signaling in the mammalian CNS. These receptors are critically involved in diverse physiological processes; including learning and memory formation, as well as neuronal damage associated with neurological diseases. Based on partial sequence and structural similarities, these complex cation-permeable iGluRs are thought to descend from simple bacterial proteins emerging from a fusion of a substrate binding protein (SBP) and an inverted potassium (K+)-channel. Here, we fuse the pore module of the viral K+-channel KcvATCV-1 to the isolated glutamate-binding domain of the mammalian iGluR subunit GluA1 which is structural homolog to SBPs. The resulting chimera (GluATCV*) is functional and displays the ligand recognition characteristics of GluA1 and the K+-selectivity of KcvATCV-1. These results are consistent with a conserved activation mechanism between a glutamate-binding domain and the pore-module of a K+-channel and support the expected phylogenetic link between the two protein families.
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Affiliation(s)
- Michael Schönrock
- Department of Biology, Neurophysiology and Neurosensory Systems, Technische Universität Darmstadt, 64289, Darmstadt, Germany
| | - Gerhard Thiel
- Department of Biology, Plant Membrane Biophysics, Technische Universität Darmstadt, 64289, Darmstadt, Germany
| | - Bodo Laube
- Department of Biology, Neurophysiology and Neurosensory Systems, Technische Universität Darmstadt, 64289, Darmstadt, Germany.
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11
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Suzuki M, Imanishi N, Mita M, Hamase K, Aiso S, Sasabe J. Heterogeneity of D-Serine Distribution in the Human Central Nervous System. ASN Neuro 2017; 9:1759091417713905. [PMID: 28604057 PMCID: PMC5470653 DOI: 10.1177/1759091417713905] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
D-serine is an endogenous ligand for N-methyl-D-aspartate glutamate receptors. Accumulating evidence including genetic associations of D-serine metabolism with neurological or psychiatric diseases suggest that D-serine is crucial in human neurophysiology. However, distribution and regulation of D-serine in humans are not well understood. Here, we found that D-serine is heterogeneously distributed in the human central nervous system (CNS). The cerebrum contains the highest level of D-serine among the areas in the CNS. There is heterogeneity in its distribution in the cerebrum and even within the cerebral neocortex. The neocortical heterogeneity is associated with Brodmann or functional areas but is unrelated to basic patterns of cortical layer structure or regional expressional variation of metabolic enzymes for D-serine. Such D-serine distribution may reflect functional diversity of glutamatergic neurons in the human CNS, which may serve as a basis for clinical and pharmacological studies on D-serine modulation.
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Affiliation(s)
- Masataka Suzuki
- 1 Department of Anatomy, Keio University School of Medicine, Tokyo, Japan
| | - Nobuaki Imanishi
- 1 Department of Anatomy, Keio University School of Medicine, Tokyo, Japan
| | | | - Kenji Hamase
- 3 Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan
| | - Sadakazu Aiso
- 1 Department of Anatomy, Keio University School of Medicine, Tokyo, Japan
| | - Jumpei Sasabe
- 1 Department of Anatomy, Keio University School of Medicine, Tokyo, Japan
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12
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Scanlon DP, Bah A, Krzeminski M, Zhang W, Leduc-Pessah HL, Dong YN, Forman-Kay JD, Salter MW. An evolutionary switch in ND2 enables Src kinase regulation of NMDA receptors. Nat Commun 2017; 8:15220. [PMID: 28508887 PMCID: PMC5440837 DOI: 10.1038/ncomms15220] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2016] [Accepted: 03/10/2017] [Indexed: 12/22/2022] Open
Abstract
The non-receptor tyrosine kinase Src is a key signalling hub for upregulating the function of N-methyl D-aspartate receptors (NMDARs). Src is anchored within the NMDAR complex via NADH dehydrogenase subunit 2 (ND2), a mitochondrially encoded adaptor protein. The interacting regions between Src and ND2 have been broadly identified, but the interaction between ND2 and the NMDAR has remained elusive. Here we generate a homology model of ND2 and dock it onto the NMDAR via the transmembrane domain of GluN1. This interaction is enabled by the evolutionary loss of three helices in bilaterian ND2 proteins compared to their ancestral homologues. We experimentally validate our model and demonstrate that blocking this interaction with an ND2 fragment identified in our experimental studies prevents Src-mediated upregulation of NMDAR currents in neurons. Our findings establish the mode of interaction between an NMDAR accessory protein with one of the core subunits of the receptor. N-methyl D-aspartate receptor (NMDAR) activity is modulated by Src tyrosine kinase via the mitochondrial protein NADH dehydrogenase subunit 2 (ND2). Here the authors show that ND2 interacts with the transmembrane region of NMDAR GluN1 subunit, a process that is crucial for Src regulation of NMDAR activity.
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Affiliation(s)
- David P Scanlon
- Program in Neurosciences &Mental Health, The Hospital for Sick Children, 686 Bay St, Toronto, Ontario, Canada M5G 0A4.,Department of Physiology, University of Toronto, 1 King's College Circle, Toronto, Ontario, Canada M5S 1A8
| | - Alaji Bah
- Program in Molecular Medicine, The Hospital for Sick Children, 686 Bay St, Toronto, Ontario, Canada M5G 0A4.,Department of Biochemistry, University of Toronto, 1 King's College Circle, Toronto, Ontario, Canada M5S 1A8
| | - Mickaël Krzeminski
- Program in Molecular Medicine, The Hospital for Sick Children, 686 Bay St, Toronto, Ontario, Canada M5G 0A4.,Department of Biochemistry, University of Toronto, 1 King's College Circle, Toronto, Ontario, Canada M5S 1A8
| | - Wenbo Zhang
- Program in Neurosciences &Mental Health, The Hospital for Sick Children, 686 Bay St, Toronto, Ontario, Canada M5G 0A4.,Department of Physiology, University of Toronto, 1 King's College Circle, Toronto, Ontario, Canada M5S 1A8
| | - Heather L Leduc-Pessah
- Program in Neurosciences &Mental Health, The Hospital for Sick Children, 686 Bay St, Toronto, Ontario, Canada M5G 0A4.,Department of Physiology, University of Toronto, 1 King's College Circle, Toronto, Ontario, Canada M5S 1A8
| | - Yi Na Dong
- Program in Neurosciences &Mental Health, The Hospital for Sick Children, 686 Bay St, Toronto, Ontario, Canada M5G 0A4.,Department of Physiology, University of Toronto, 1 King's College Circle, Toronto, Ontario, Canada M5S 1A8
| | - Julie D Forman-Kay
- Program in Molecular Medicine, The Hospital for Sick Children, 686 Bay St, Toronto, Ontario, Canada M5G 0A4.,Department of Biochemistry, University of Toronto, 1 King's College Circle, Toronto, Ontario, Canada M5S 1A8
| | - Michael W Salter
- Program in Neurosciences &Mental Health, The Hospital for Sick Children, 686 Bay St, Toronto, Ontario, Canada M5G 0A4.,Department of Physiology, University of Toronto, 1 King's College Circle, Toronto, Ontario, Canada M5S 1A8
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13
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The Functional and Molecular Properties, Physiological Functions, and Pathophysiological Roles of GluN2A in the Central Nervous System. Mol Neurobiol 2016; 54:1008-1021. [DOI: 10.1007/s12035-016-9715-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Accepted: 01/11/2016] [Indexed: 11/25/2022]
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14
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Mesic I, Madry C, Geider K, Bernhard M, Betz H, Laube B. The N-terminal domain of the GluN3A subunit determines the efficacy of glycine-activated NMDA receptors. Neuropharmacology 2016; 105:133-141. [PMID: 26777280 DOI: 10.1016/j.neuropharm.2016.01.014] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2015] [Revised: 01/06/2016] [Accepted: 01/07/2016] [Indexed: 12/29/2022]
Abstract
N-methyl-d-aspartate (NMDA) receptors composed of glycine-binding GluN1 and GluN3 subunits function as excitatory glycine receptors that respond to agonist application only with a very low efficacy. Binding of glycine to the high-affinity GluN3 subunits triggers channel opening, whereas glycine binding to the low-affinity GluN1 subunits causes an auto-inhibition of the maximal glycine-inducible receptor current (Imax). Hence, competitive antagonists of the GluN1 subunit strongly potentiate glycine responses of wild type (wt) GluN1/GluN3 receptors. Here, we show that co-expression of N-terminal domain (NTD) deleted GluN1 (GluN1(ΔNTD)) and GluN3 (GluN3(ΔNTD)) subunits in Xenopus oocytes generates GluN1/GluN3 receptors with a large increase in the glycine-inducible Imax accompanied by a strongly impaired GluN1 antagonist-mediated potentiation. Affinity purification after metabolic or surface labeling revealed no differences in subunit stoichiometry and surface expression between wt GluN1/GluN3A and mutant GluN1(ΔNTD)/GluN3A(ΔNTD) receptors, indicating a specific effect of NTD deletions on the efficacy of receptor opening. Notably, GluN1/GluN3A(ΔNTD) receptors showed a similar increase in Imax and a greatly reduced GluN1 antagonist-mediated current potentiation as GluN1(ΔNTD)/GluN3A(ΔNTD) receptors, whereas the glycine-induced currents of GluN1(ΔNTD)/GluN3A receptors resembled those of wt GluN1/GluN3A receptors. Furthermore, oxidative crosslinking of the homophilic GluN3A NTD intersubunit interface in mutant GluN1/GluN3A(R319C) receptors caused both a decrease in the glycine-induced Imax concomitantly with a marked increase in GluN1 antagonist-mediated current potentiation, whilst mutations within the intrasubunit region linking the GluN3A NTD to the ligand binding domain had opposite effects. Together these results show that the GluN3A NTD constitutes a crucial regulatory determinant of GluN1/GluN3A receptor function.
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Affiliation(s)
- Ivana Mesic
- Department of Neurochemistry, Max-Planck-Institute for Brain Research, Deutschordenstrasse 46, 60528 Frankfurt am Main, Germany; Department of Neurophysiology and Neurosensory Systems, Technische Universität Darmstadt, Schnittspahnstrasse 3, 64287 Darmstadt, Germany
| | - Christian Madry
- Department of Neurochemistry, Max-Planck-Institute for Brain Research, Deutschordenstrasse 46, 60528 Frankfurt am Main, Germany
| | - Kirsten Geider
- Department of Neurophysiology and Neurosensory Systems, Technische Universität Darmstadt, Schnittspahnstrasse 3, 64287 Darmstadt, Germany
| | - Max Bernhard
- Department of Neurophysiology and Neurosensory Systems, Technische Universität Darmstadt, Schnittspahnstrasse 3, 64287 Darmstadt, Germany
| | - Heinrich Betz
- Department of Neurochemistry, Max-Planck-Institute for Brain Research, Deutschordenstrasse 46, 60528 Frankfurt am Main, Germany; Max-Planck-Institute for Medical Research, Jahnstrasse 29, 69120 Heidelberg, Germany
| | - Bodo Laube
- Department of Neurochemistry, Max-Planck-Institute for Brain Research, Deutschordenstrasse 46, 60528 Frankfurt am Main, Germany; Department of Neurophysiology and Neurosensory Systems, Technische Universität Darmstadt, Schnittspahnstrasse 3, 64287 Darmstadt, Germany.
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15
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Mothet JP, Le Bail M, Billard JM. Time and space profiling of NMDA receptor co-agonist functions. J Neurochem 2015; 135:210-25. [DOI: 10.1111/jnc.13204] [Citation(s) in RCA: 67] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2015] [Revised: 05/12/2015] [Accepted: 06/02/2015] [Indexed: 02/01/2023]
Affiliation(s)
- Jean-Pierre Mothet
- Team ‘Gliotransmission and Synaptopathies’; Aix-Marseille Université; CNRS; CRN2M UMR7286; Marseille France
| | - Matildé Le Bail
- Team ‘Gliotransmission and Synaptopathies’; Aix-Marseille Université; CNRS; CRN2M UMR7286; Marseille France
| | - Jean-Marie Billard
- Center of Psychiatry and Neuroscience; University Paris Descartes; Sorbonne Paris City; UMR 894; Paris France
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16
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Sirrieh RE, MacLean DM, Jayaraman V. A conserved structural mechanism of NMDA receptor inhibition: A comparison of ifenprodil and zinc. ACTA ACUST UNITED AC 2015; 146:173-81. [PMID: 26170175 PMCID: PMC4516779 DOI: 10.1085/jgp.201511422] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2015] [Accepted: 06/16/2015] [Indexed: 11/30/2022]
Abstract
Zinc and ifenprodil induce similar conformational changes in the NMDA receptor, suggesting a conserved mechanism of inhibition independent of receptor subtype and the site at which the inhibitor binds. N-methyl-d-aspartate (NMDA) receptors, one of the three main types of ionotropic glutamate receptors (iGluRs), are involved in excitatory synaptic transmission, and their dysfunction is implicated in various neurological disorders. NMDA receptors, heterotetramers typically composed of GluN1 and GluN2 subunits, are the only members of the iGluR family that bind allosteric modulators at their amino-terminal domains (ATDs). We used luminescence resonance energy transfer to characterize the conformational changes the receptor undergoes upon binding ifenprodil, a synthetic compound that specifically inhibits activation of NMDA receptors containing GluN2B. We found that ifenprodil induced an overall closure of the GluN2B ATD without affecting conformation of the GluN1 ATD or the upper lobes of the ATDs, the same mechanism whereby zinc inhibits GluN2A. These data demonstrate that the conformational changes induced by zinc and ifenprodil represent a conserved mechanism of NMDA receptor inhibition. Additionally, we compared the structural mechanism of zinc inhibition of GluN1–GluN2A receptors to that of ifenprodil inhibition of GluN1–GluN2B. The similarities in the conformational changes induced by inhibitor binding suggest a conserved structural mechanism of inhibition independent of the binding site of the modulator.
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Affiliation(s)
- Rita E Sirrieh
- Department of Biochemistry and Molecular Biology, Center for Membrane Biology, University of Texas Health Science Center, Houston, TX 77030
| | - David M MacLean
- Department of Biochemistry and Molecular Biology, Center for Membrane Biology, University of Texas Health Science Center, Houston, TX 77030
| | - Vasanthi Jayaraman
- Department of Biochemistry and Molecular Biology, Center for Membrane Biology, University of Texas Health Science Center, Houston, TX 77030
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17
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Sirrieh RE, MacLean DM, Jayaraman V. Subtype-dependent N-methyl-D-aspartate receptor amino-terminal domain conformations and modulation by spermine. J Biol Chem 2015; 290:12812-20. [PMID: 25829490 PMCID: PMC4432297 DOI: 10.1074/jbc.m115.649723] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2015] [Revised: 03/27/2015] [Indexed: 12/30/2022] Open
Abstract
The N-methyl-d-aspartate (NMDA) subtype of the ionotropic glutamate receptors is the primary mediator of calcium-permeable excitatory neurotransmission in the central nervous system. Subunit composition and binding of allosteric modulators to the amino-terminal domain determine the open probability of the channel. By using luminescence resonance energy transfer with functional receptors expressed in CHO cells, we show that the cleft of the amino-terminal domain of the GluN2B subunit, which has a lower channel open probability, is on average more closed than the GluN2A subunit, which has a higher open probability. Furthermore, the GluN1 amino-terminal domain adopts a more open conformation when coassembled with GluN2A than with GluN2B. Binding of spermine, an allosteric potentiator, opens the amino-terminal domain cleft of both the GluN2B subunit and the adjacent GluN1 subunit. These studies provide direct structural evidence that the inherent conformations of the amino-terminal domains vary based on the subunit and match the reported open probabilities for the receptor.
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Affiliation(s)
- Rita E Sirrieh
- From the Center for Membrane Biology, Department of Biochemistry and Molecular Biology, University of Texas Health Science Center, Houston, Texas 77030
| | - David M MacLean
- From the Center for Membrane Biology, Department of Biochemistry and Molecular Biology, University of Texas Health Science Center, Houston, Texas 77030
| | - Vasanthi Jayaraman
- From the Center for Membrane Biology, Department of Biochemistry and Molecular Biology, University of Texas Health Science Center, Houston, Texas 77030
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18
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Lauro C, Catalano M, Di Paolo E, Chece G, de Costanzo I, Trettel F, Limatola C. Fractalkine/CX3CL1 engages different neuroprotective responses upon selective glutamate receptor overactivation. Front Cell Neurosci 2015; 8:472. [PMID: 25653593 PMCID: PMC4301004 DOI: 10.3389/fncel.2014.00472] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2014] [Accepted: 12/30/2014] [Indexed: 11/16/2022] Open
Abstract
Neuronal death induced by overactivation of N-methyl-d-aspartate receptors (NMDARs) is implicated in the pathophysiology of many neurodegenerative diseases such as stroke, epilepsy and traumatic brain injury. This toxic effect is mainly mediated by NR2B-containing extrasynaptic NMDARs, while NR2A-containing synaptic NMDARs contribute to cell survival, suggesting the possibility of therapeutic approaches targeting specific receptor subunits. We report that fractalkine/CX3CL1 protects hippocampal neurons from NMDA-induced cell death with a mechanism requiring the adenosine receptors type 2A (A2AR). This is different from CX3CL1-induced protection from glutamate (Glu)-induced cell death, that fully depends on A1R and requires in part A3R. We show that CX3CL1 neuroprotection against NMDA excitotoxicity involves D-serine, a co-agonist of NR2A/NMDAR, resulting in cyclic AMP-dependent transcription factor cyclic-AMP response element-binding protein (CREB) phosphorylation.
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Affiliation(s)
- Clotilde Lauro
- Department of Physiology and Pharmacology, Istituto Pasteur Fondazione Cenci Bolognetti, Sapienza University of Rome Rome, Italy
| | - Myriam Catalano
- Department of Physiology and Pharmacology, Istituto Pasteur Fondazione Cenci Bolognetti, Sapienza University of Rome Rome, Italy ; Istituto di Ricovero e Cura a Carattere Scientifico NeuroMed Pozzilli, Italy
| | | | - Giuseppina Chece
- Department of Physiology and Pharmacology, Istituto Pasteur Fondazione Cenci Bolognetti, Sapienza University of Rome Rome, Italy
| | - Ida de Costanzo
- Department of Physiology and Pharmacology, Istituto Pasteur Fondazione Cenci Bolognetti, Sapienza University of Rome Rome, Italy
| | - Flavia Trettel
- Department of Physiology and Pharmacology, Istituto Pasteur Fondazione Cenci Bolognetti, Sapienza University of Rome Rome, Italy
| | - Cristina Limatola
- Department of Physiology and Pharmacology, Istituto Pasteur Fondazione Cenci Bolognetti, Sapienza University of Rome Rome, Italy ; Istituto di Ricovero e Cura a Carattere Scientifico NeuroMed Pozzilli, Italy
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19
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Cheriyan J, Mezes C, Zhou N, Balsara RD, Castellino FJ. Heteromerization of ligand binding domains of N-methyl-D-aspartate receptor requires both coagonists, L-glutamate and glycine. Biochemistry 2015; 54:787-94. [PMID: 25544544 PMCID: PMC4310633 DOI: 10.1021/bi501437s] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
NMDA receptors (NMDAR) are voltage- and glutamate-gated heteromeric ion channels found at excitatory neuronal synapses, the functions of which are to mediate the mechanisms of brain plasticity and, thereby, its higher order functions. In addition to Glu, the activation of these heteromeric receptors requires Gly or d-Ser as a coagonist. However, it is not fully known as to why coagonism is required for the opening of NMDAR ion channels. We show herein that the ligand binding domains (LBD) of the GluN1 and GluN2A subunits of the NMDAR heterodimerize only when both coagonists, Glu and Gly/d-Ser, bind to their respective sites on GluN2 and GluN1. In the agonist-free state, these domains form homomeric interactions, which are disrupted by binding of their respective agonists. Also, in a heteromer formed by the LBDs, GluN2A is more sensitized to bind Glu, while the affinity of Gly for GluN1 remains unchanged. We thus provide direct evidence to show that coagonism is necessary for heteromeric pairing of LBDs, which is an essential step in forming functional ion channels in NMDARs.
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Affiliation(s)
- John Cheriyan
- W. M. Keck Center for Transgene Research and the Department of Chemistry and Biochemistry, University of Notre Dame , Notre Dame, Indiana 46556, United States
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20
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An asymmetric approach to the synthesis of a carbon-11 labelled gliotransmitter d-serine. J Radioanal Nucl Chem 2014. [DOI: 10.1007/s10967-014-3670-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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21
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Astroglial d-serine is the endogenous co-agonist at the presynaptic NMDA receptor in rat entorhinal cortex. Neuropharmacology 2014; 83:118-27. [PMID: 24747728 DOI: 10.1016/j.neuropharm.2014.04.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2013] [Revised: 03/17/2014] [Accepted: 04/07/2014] [Indexed: 12/17/2022]
Abstract
Presynaptic NMDA receptors facilitate the release of glutamate at excitatory cortical synapses and are involved in regulation of synaptic dynamics and plasticity. At synapses in the entorhinal cortex these receptors are tonically activated and provide a positive feedback modulation of the level of background excitation. NMDA receptor activation requires obligatory occupation of a co-agonist binding site, and in the present investigation we have examined whether this site on the presynaptic receptor is activated by endogenous glycine or d-serine. We used whole-cell patch clamp recordings of spontaneous AMPA receptor-mediated synaptic currents from rat entorhinal cortex neurones in vitro as a monitor of presynaptic glutamate release. Addition of exogenous glycine or d-serine had minimal effects on spontaneous release, suggesting that the co-agonist site was endogenously activated and likely to be saturated in our slices. This was supported by the observation that a co-agonist site antagonist reduced the frequency of spontaneous currents. Depletion of endogenous glycine by enzymatic breakdown with a bacterial glycine oxidase had little effect on glutamate release, whereas d-serine depletion with a yeast d-amino acid oxidase significantly reduced glutamate release, suggesting that d-serine is the endogenous agonist. Finally, the effects of d-serine depletion were mimicked by compromising astroglial cell function, and this was rescued by exogenous d-serine, indicating that astroglial cells are the provider of the d-serine that tonically activates the presynaptic NMDA receptor. We discuss the significance of these observations for the aetiology of epilepsy and possible targeting of the presynaptic NMDA receptor in anticonvulsant therapy.
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22
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Chen LJ, Sun BH, Cao Y, Yao HD, Qu JP, Liu C, Xu SW, Li S. The effects of avermectin on amino acid neurotransmitters and their receptors in the pigeon brain. PESTICIDE BIOCHEMISTRY AND PHYSIOLOGY 2014; 110:13-19. [PMID: 24759046 DOI: 10.1016/j.pestbp.2014.01.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2013] [Revised: 01/25/2014] [Accepted: 01/28/2014] [Indexed: 06/03/2023]
Abstract
The objective of this study was to examine the effects of avermectin (AVM) on amino acid neurotransmitters and their receptors in the pigeon brain. Four groups two-month-old American king pigeons (n=20/group) were fed either a commercial diet or an AVM-supplemented diet (20mg/kg·diet, 40 mg/kg·diet, or 60 mg/kg·diet) for 30, 60, or 90 days. The contents of aspartic acid (ASP), glutamate (GLU), glycine (GLY), and γ-aminobutyric acid (GABA) in the brain tissues were determined using ultraviolet high-performance liquid chromatography (HPLC). The expression levels of the GLU and GABA receptor genes were analyzed using real-time quantitative polymerase chain reaction (qPCR). The results indicate that AVM exposure significantly enhances the contents of GABA, GLY, GLU, and ASP in the cerebrum, cerebellum, and optic lobe. In addition, AVM exposure increases the mRNA expression levels of γ-aminobutyric acid type A receptor (GABAAR), γ-aminobutyric acid type B receptor (GABABR), N-methyl-d-aspartate 1 receptor (NR1), N-methyl-d-aspartate 2A receptor (NR2A), and N-methyl-d-aspartate 2B receptor (NR2B) in a dose- and time-dependent manner. Moreover, we found that the most damaged organ was the cerebrum, followed by the cerebellum, and then the optic lobe. These results show that the AVM-induced neurotoxicity may be associated with its effects on amino acid neurotransmitters and their receptors. The information presented in this study will help supplement the available data for future AVM toxicity studies.
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Affiliation(s)
- Li-Jie Chen
- College of Veterinary Medicine, Northeast Agricultural University, No. 59 Mucai Street, Xiangfang District, Harbin 150030, China; Department of Neurology, The Second Affiliated Hospital, Harbin Medical University, No. 246 Xuefu Road, Nangang District, Harbin 150001, China
| | - Bao-Hong Sun
- Department of Neurology, The Second Affiliated Hospital, Harbin Medical University, No. 246 Xuefu Road, Nangang District, Harbin 150001, China
| | - Ye Cao
- College of Veterinary Medicine, Northeast Agricultural University, No. 59 Mucai Street, Xiangfang District, Harbin 150030, China
| | - Hai-Dong Yao
- College of Veterinary Medicine, Northeast Agricultural University, No. 59 Mucai Street, Xiangfang District, Harbin 150030, China
| | - Jian-Ping Qu
- College of Veterinary Medicine, Northeast Agricultural University, No. 59 Mucai Street, Xiangfang District, Harbin 150030, China
| | - Ci Liu
- College of Veterinary Medicine, Northeast Agricultural University, No. 59 Mucai Street, Xiangfang District, Harbin 150030, China
| | - Shi-Wen Xu
- College of Veterinary Medicine, Northeast Agricultural University, No. 59 Mucai Street, Xiangfang District, Harbin 150030, China
| | - Shu Li
- College of Veterinary Medicine, Northeast Agricultural University, No. 59 Mucai Street, Xiangfang District, Harbin 150030, China.
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Ladépêche L, Dupuis JP, Groc L. Surface trafficking of NMDA receptors: gathering from a partner to another. Semin Cell Dev Biol 2013; 27:3-13. [PMID: 24177014 DOI: 10.1016/j.semcdb.2013.10.005] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2013] [Revised: 10/11/2013] [Accepted: 10/22/2013] [Indexed: 10/26/2022]
Abstract
Understanding the molecular and cellular pathways by which neurons integrate signals from different neurotransmitter systems has been among the major challenges of modern neuroscience. The ionotropic glutamate NMDA receptor plays a key role in the maturation and plasticity of glutamate synapses, both in physiology and pathology. It recently appeared that the surface distribution of NMDA receptors is dynamically regulated through lateral diffusion, providing for instance a powerful way to rapidly affect the content and composition of synaptic receptors. The ability of various neuromodulators to regulate NMDA receptor signaling revealed that this receptor can also serve as a molecular integrator of the ambient neuronal environment. Although still in its infancy, we here review our current understanding of the cellular regulation of NMDA receptor surface dynamics. We specifically discuss the roles of well-known modulators, such as dopamine, and membrane interactors in these regulatory processes, exemplifying the recent evidence that the direct interaction between NMDAR and dopamine receptors regulates their surface diffusion and distribution. In addition to the well-established modulation of NMDA receptor signaling by intracellular pathways, the surface dynamics of the receptor is now emerging as the first level of regulation, opening new pathophysiological perspectives for innovative therapeutical strategies.
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Affiliation(s)
- Laurent Ladépêche
- Université de Bordeaux, Interdisciplinary Institute for Neuroscience, UMR 5297, F-33000 Bordeaux, France; CNRS, Interdisciplinary Institute for Neuroscience, UMR 5297, F-33000 Bordeaux, France
| | - Julien Pierre Dupuis
- Université de Bordeaux, Interdisciplinary Institute for Neuroscience, UMR 5297, F-33000 Bordeaux, France; CNRS, Interdisciplinary Institute for Neuroscience, UMR 5297, F-33000 Bordeaux, France
| | - Laurent Groc
- Université de Bordeaux, Interdisciplinary Institute for Neuroscience, UMR 5297, F-33000 Bordeaux, France; CNRS, Interdisciplinary Institute for Neuroscience, UMR 5297, F-33000 Bordeaux, France.
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24
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Smothers CT, Jin C, Woodward JJ. Deletion of the N-terminal domain alters the ethanol inhibition of N-methyl-D-aspartate receptors in a subunit-dependent manner. Alcohol Clin Exp Res 2013; 37:1882-90. [PMID: 23905549 DOI: 10.1111/acer.12168] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2012] [Accepted: 03/25/2013] [Indexed: 01/21/2023]
Abstract
BACKGROUND Ethanol (EtOH) inhibition of N-methyl-d-aspartate (NMDA) receptors is poorly understood due in part to the organizational complexity of the receptor that provides ample locations for sites of action. Among these, the N-terminal domain (NTD) of NMDA receptor subunits contains binding sites for a variety of modulatory agents including zinc, protons, and GluN2B selective antagonists such as ifenprodil or Ro-25-6981. EtOH inhibition of neuronal NMDA receptors expressed in some brain areas has been reported to be occluded by the presence of ifenprodil or similar compounds suggesting that the NTD may be important in regulating the EtOH sensitivity of NMDA receptors. METHODS Wild-type GluN1 and GluN2 subunits and those in which the coding sequence for the NTD was deleted were expressed in HEK293 cells. Whole-cell voltage-clamp recording was used to assess EtOH inhibition of wild-type and mutant receptors lacking the NTD. RESULTS As compared to wild-type GluN1/GluN2A receptors, EtOH inhibition was slightly greater in cells expressing GluN2A subunits lacking the NTD. In contrast, GluN2B N-terminal deletion mutants showed normal EtOH inhibition while those lacking the NTD in both GluN1 and GluN2B subunits had decreased EtOH inhibition as compared to wild-type receptors. NTD lacking GluN2B receptors were insensitive to ifenprodil but retained normal sensitivity to EtOH. CONCLUSIONS These findings indicate that the NTD modestly influences the EtOH sensitivity of NMDA receptors in a subunit-dependent manner. They also show that ifenprodil's actions on GluN2B-containing receptors can be dissociated from those of EtOH. These results suggest that while the NTD is not a primary site of action for EtOH on NMDA receptors, it likely affects sensitivity via actions on intrinsic channel properties.
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Affiliation(s)
- Corigan T Smothers
- Division of Neuroscience Research and, Center for Drug and Alcohol Programs, Medical University of South Carolina, Charleston, South Carolina
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25
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Van Horn MR, Sild M, Ruthazer ES. D-serine as a gliotransmitter and its roles in brain development and disease. Front Cell Neurosci 2013; 7:39. [PMID: 23630460 PMCID: PMC3632749 DOI: 10.3389/fncel.2013.00039] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2013] [Accepted: 03/26/2013] [Indexed: 01/05/2023] Open
Abstract
The development of new techniques to study glial cells has revealed that they are active participants in the development of functional neuronal circuits. Calcium imaging studies demonstrate that glial cells actively sense and respond to neuronal activity. Glial cells can produce and release neurotransmitter-like molecules, referred to as gliotransmitters, that can in turn influence the activity of neurons and other glia. One putative gliotransmitter, D-serine is believed to be an endogenous co-agonist for synaptic N-methyl-D-aspartate receptors (NMDARs), modulating synaptic transmission and plasticity mediated by this receptor. The observation that D-serine levels in the mammalian brain increase during early development, suggests a possible role for this gliotransmitter in normal brain development and circuit refinement. In this review we will examine the data that D-serine and its associated enzyme serine racemase are developmentally regulated. We will consider the evidence that D-serine is actively released by glial cells and examine the studies that have implicated D-serine as a critical player involved in regulating NMDAR-mediated synaptic transmission and neuronal migration during development. Furthermore, we will consider how dysregulation of D-serine may play an important role in the etiology of neurological and psychiatric diseases.
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Affiliation(s)
- Marion R Van Horn
- Montreal Neurological Institute, McGill University Montreal, QC, Canada
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26
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Papouin T, Ladépêche L, Ruel J, Sacchi S, Labasque M, Hanini M, Groc L, Pollegioni L, Mothet JP, Oliet SHR. Synaptic and extrasynaptic NMDA receptors are gated by different endogenous coagonists. Cell 2012; 150:633-46. [PMID: 22863013 DOI: 10.1016/j.cell.2012.06.029] [Citation(s) in RCA: 525] [Impact Index Per Article: 43.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2011] [Revised: 04/18/2012] [Accepted: 06/05/2012] [Indexed: 11/20/2022]
Abstract
N-methyl-d-aspartate receptors (NMDARs) are located in neuronal cell membranes at synaptic and extrasynaptic locations, where they are believed to mediate distinct physiological and pathological processes. Activation of NMDARs requires glutamate and a coagonist whose nature and impact on NMDAR physiology remain elusive. We report that synaptic and extrasynaptic NMDARs are gated by different endogenous coagonists, d-serine and glycine, respectively. The regionalized availability of the coagonists matches the preferential affinity of synaptic NMDARs for d-serine and extrasynaptic NMDARs for glycine. Furthermore, glycine and d-serine inhibit NMDAR surface trafficking in a subunit-dependent manner, which is likely to influence NMDARs subcellular location. Taking advantage of this coagonist segregation, we demonstrate that long-term potentiation and NMDA-induced neurotoxicity rely on synaptic NMDARs only. Conversely, long-term depression requires both synaptic and extrasynaptic receptors. Our observations provide key insights into the operating mode of NMDARs, emphasizing functional distinctions between synaptic and extrasynaptic NMDARs in brain physiology.
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Affiliation(s)
- Thomas Papouin
- INSERM U862, Neurocentre Magendie, 33077 Bordeaux, France
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27
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Abstract
The amino-terminal domains of NMDA receptor subunits are important for receptor assembly and desensitization, and incorporate the high-affinity binding sites for zinc and ifenprodil. These amino-terminal ligands are thought of as subunit-specific receptor inhibitors. However, multiple NMDA receptor subtypes contribute to EPSCs at wild-type hippocampal synapses. To understand the action of amino-terminal ligands, we first used cultured hippocampal neurons from N2A and N2B knock-out mice. EPSCs from these neurons have properties that are consistent with N1/N2B and N1/N2A diheteromeric receptors, respectively. As expected, zinc reduced the EPSC peak amplitude from N2B KO neurons, but surprisingly also prolonged the deactivation, resulting in a marked redistribution of charge. Consistent with prolongation of the EPSC, zinc produced a longer latency to first opening of glutamate-bound receptors, which resulted in a decrease in the number of receptors that opened by the peak. Ifenprodil had similar effects on EPSCs from N2A KO neurons. In neurons from wild-type mice, zinc or ifenprodil reduced the EPSC peak, but only zinc caused significant charge redistribution, consistent with a small contribution of N1/N2B diheteromers in these neurons. Our results indicate that ligand binding to amino-terminal domains can alter the behavior of synaptic NMDA receptors under the nonequilibrium conditions of glutamate release during synaptic transmission. By prolonging EPSCs, amino-terminal ligands could markedly affect the computational properties of NMDA receptors and could potentially be exploited for therapeutic purposes.
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28
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Collingridge GL, Volianskis A, Bannister N, France G, Hanna L, Mercier M, Tidball P, Fang G, Irvine MW, Costa BM, Monaghan DT, Bortolotto ZA, Molnár E, Lodge D, Jane DE. The NMDA receptor as a target for cognitive enhancement. Neuropharmacology 2012; 64:13-26. [PMID: 22796429 DOI: 10.1016/j.neuropharm.2012.06.051] [Citation(s) in RCA: 175] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2012] [Revised: 06/22/2012] [Accepted: 06/24/2012] [Indexed: 12/31/2022]
Abstract
NMDA receptors (NMDARs) play an important role in neural plasticity including long-term potentiation and long-term depression, which are likely to explain their importance for learning and memory. Cognitive decline is a major problem facing an ageing human population, so much so that its reversal has become an important goal for scientific research and pharmaceutical development. Enhancement of NMDAR function is a core strategy toward this goal. In this review we indicate some of the major ways of potentiating NMDAR function by both direct and indirect modulation. There is good evidence that both positive and negative modulation can enhance function suggesting that a subtle approach correcting imbalances in particular clinical situations will be required. Excessive activation and the resultant deleterious effects will need to be carefully avoided. Finally we describe some novel positive allosteric modulators of NMDARs, with some subunit selectivity, and show initial evidence of their ability to affect NMDAR mediated events. This article is part of a Special Issue entitled 'Cognitive Enhancers'.
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Affiliation(s)
- Graham L Collingridge
- MRC Centre for Synaptic Plasticity, School of Physiology and Pharmacology, University of Bristol, Bristol BS1 3NY, UK.
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29
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Ng KS, Leung HW, Wong PTH, Low CM. Cleavage of the NR2B subunit amino terminus of N-methyl-D-aspartate (NMDA) receptor by tissue plasminogen activator: identification of the cleavage site and characterization of ifenprodil and glycine affinities on truncated NMDA receptor. J Biol Chem 2012; 287:25520-9. [PMID: 22610100 DOI: 10.1074/jbc.m112.374397] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Thrombolysis using tissue plasminogen activator (tPA) has been the key treatment for patients with acute ischemic stroke for the past decade. Recent studies, however, suggest that this clot-busting protease also plays various roles in brain physiological and pathophysiological glutamatergic-dependent processes, such as synaptic plasticity and neurodegeneration. In addition, increasing evidence implicates tPA as an important neuromodulator of the N-methyl-d-aspartate (NMDA) receptors. Here, we demonstrate that recombinant human tPA cleaves the NR2B subunit of NMDA receptor. Analysis of NR2B in rat brain lysates and cortical neurons treated with tPA revealed concentration- and time-dependent degradation of NR2B proteins. Peptide sequencing studies performed on the cleaved-off products obtained from the tPA treatment on a recombinant fusion protein of the amino-terminal domain of NR2B revealed that tPA-mediated cleavage occurred at arginine 67 (Arg(67)). This cleavage is tPA-specific, plasmin-independent, and removes a predicted ~4-kDa fragment (Arg(27)-Arg(67)) from the amino-terminal domain of the NR2B protein. Site-directed mutagenesis of putative cleavage site Arg(67) to Ala(67) impeded tPA-mediated degradation of recombinant protein. This analysis revealed that NR2B is a novel substrate of tPA and suggested that an Arg(27)-Arg(67)-truncated NR2B-containing NMDA receptor could be formed. Heterologous expression of NR2B with Gln(29)-Arg(67) deleted is functional but exhibits reduced ifenprodil inhibition and increased glycine EC(50) with no change in glutamate EC(50). Our results confirmed NR2B as a novel proteolytic substrate of tPA, where tPA may directly interact with NR2B subunits leading to a change in pharmacological properties of NR2B-containing NMDA receptors.
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Affiliation(s)
- Kay-Siong Ng
- Departments of Pharmacology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA.
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30
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Costa BM, Irvine MW, Fang G, Eaves RJ, Mayo-Martin MB, Laube B, Jane DE, Monaghan DT. Structure-activity relationships for allosteric NMDA receptor inhibitors based on 2-naphthoic acid. Neuropharmacology 2011; 62:1730-6. [PMID: 22155206 DOI: 10.1016/j.neuropharm.2011.11.019] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2011] [Revised: 11/12/2011] [Accepted: 11/28/2011] [Indexed: 10/14/2022]
Abstract
Over-activation of N-methyl-d-aspartate (NMDA) receptors is critically involved in many neurological conditions, thus there has been considerable interest in developing NMDA receptor antagonists. We have recently identified a series of naphthoic and phenanthroic acid compounds that allosterically modulate NMDA receptors through a novel mechanism of action. In the present study, we have determined the structure-activity relationships of 18 naphthoic acid derivatives for the ability to inhibit the four GluN1/GluN2(A-D) NMDA receptor subtypes. 2-Naphthoic acid has low activity at GluN2A-containing receptors and yet lower activity at other NMDA receptors. 3-Amino addition, and especially 3-hydroxy addition, to 2-naphthoic acid increased inhibitory activity at GluN1/GluN2C and GluN1/GluN2D receptors. Further halogen and phenyl substitutions to 2-hydroxy-3-naphthoic acid leads to several relatively potent inhibitors, the most potent of which is UBP618 (1-bromo-2-hydroxy-6-phenylnaphthalene-3-carboxylic acid) with an IC(50) ∼ 2 μM at each of the NMDA receptor subtypes. While UBP618 is non-selective, elimination of the hydroxyl group in UBP618, as in UBP628 and UBP608, leads to an increase in GluN1/GluN2A selectivity. Of the compounds evaluated, specifically those with a 6-phenyl substitution were less able to fully inhibit GluN1/GluN2A, GluN1/GluN2B and GluN1/GluN2C responses (maximal % inhibition of 60-90%). Such antagonists may potentially have reduced adverse effects by not excessively blocking NMDA receptor signaling. Together, these studies reveal discrete structure-activity relationships for the allosteric antagonism of NMDA receptors that may facilitate the development of NMDA receptor modulator agents for a variety of neuropsychiatric and neurological conditions.
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Affiliation(s)
- Blaise Mathias Costa
- Department of Pharmacology and Experimental Neuroscience, 985800 Nebraska Medical Center, Omaha, NE 68198-5800, USA.
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31
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Zinc effects on NMDA receptor gating kinetics. Biophys J 2011; 100:1910-8. [PMID: 21504727 DOI: 10.1016/j.bpj.2011.02.042] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2010] [Revised: 02/14/2011] [Accepted: 02/23/2011] [Indexed: 12/24/2022] Open
Abstract
Zinc accumulates in the synaptic vesicles of certain glutamatergic forebrain neurons and modulates neuronal excitability and synaptic plasticity by multiple poorly understood mechanisms. Zinc directly inhibits NMDA-sensitive glutamate-gated channels by two separate mechanisms: high-affinity binding to N-terminal domains of GluN2A subunits reduces channel open probability, and low-affinity voltage-dependent binding to pore-lining residues blocks the channel. Insight into the high-affinity allosteric effect has been hampered by the receptor's complex gating; multiple, sometimes coupled, modulatory mechanisms; and practical difficulties in avoiding transient block by residual Mg(2+). To sidestep these challenges, we examined how nanomolar zinc concentrations changed the gating kinetics of individual block-resistant receptors. We found that block-insensitive channels had lower intrinsic open probabilities but retained high sensitivity to zinc inhibition. Binding of zinc to these receptors resulted in longer closures and shorter openings within bursts of activity but had no effect on interburst intervals. Based on kinetic modeling of these data, we conclude that zinc-bound receptors have higher energy barriers to opening and less stable open states. We tested this model for its ability to predict zinc-dependent changes in macroscopic responses and to infer the impact of nanomolar zinc concentrations on synaptic currents mediated by 2A-type NMDA receptors.
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32
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Cao JY, Qiu S, Zhang J, Wang JJ, Zhang XM, Luo JH. Transmembrane region of N-methyl-D-aspartate receptor (NMDAR) subunit is required for receptor subunit assembly. J Biol Chem 2011; 286:27698-705. [PMID: 21659529 DOI: 10.1074/jbc.m111.235333] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
N-Methyl-D-aspartate receptors (NMDARs), one of three main classes of ionotropic glutamate receptors, play major roles in synaptic plasticity, synaptogenesis, and excitotoxicity. Unlike non-NMDA receptors, NMDARs are thought to comprise obligatory heterotetrameric complexes mainly composed of GluN1 and GluN2 subunits. When expressed alone in heterogenous cells, such as HEK293 cells, most of the NMDAR subunits can neither leave the endoplasmic reticulum (ER) nor be expressed in the cell membrane because of the ER retention signals. Only when NMDARs are heteromerically assembled can the ER retention signals be masked and NMDARs be expressed in the surface membrane. However, the mechanisms underlying NMDAR assembly remain poorly understood. To identify regions in subunits that mediate this assembly, we made a series of truncated or chimeric cDNA constructs. Using FRET measurement in living cells combined with immunostaining and coimmunoprecipitation analysis, we examined the assembly-determining domains of NMDAR subunits. Our results indicate that the transmembrane region of subunits is necessary for the assembly of NMDAR subunits, both for the homodimer and the heteromer.
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Affiliation(s)
- Jing-yuan Cao
- Department of Neurobiology, Key Laboratory of Medical Neurobiology of Ministry of Health of China, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
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33
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Sugimoto M, Sasaki S, Watanabe T, Nishimura S, Ideta A, Yamazaki M, Matsuda K, Yuzaki M, Sakimura K, Aoyagi Y, Sugimoto Y. Ionotropic glutamate receptor AMPA 1 is associated with ovulation rate. PLoS One 2010; 5:e13817. [PMID: 21072200 PMCID: PMC2972219 DOI: 10.1371/journal.pone.0013817] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2010] [Accepted: 10/14/2010] [Indexed: 11/18/2022] Open
Abstract
Ionotropic glutamate receptors mediate most excitatory neurotransmission in the central nervous system by opening ion channels upon the binding of glutamate. Despite the essential roles of glutamate in the control of reproduction and anterior pituitary hormone secretion, there is a limited understanding of how glutamate receptors control ovulation. Here we reveal the function of the ionotropic glutamate receptor AMPA-1 (GRIA1) in ovulation. Based on a genome-wide association study in Bos taurus, we found that ovulation rate is influenced by a variation in the N-terminal leucine/isoleucine/valine-binding protein (LIVBP) domain of GRIA1, in which serine is replaced by asparagine. GRIA1Asn has a weaker affinity to glutamate than GRIA1Ser, both in Xenopus oocytes and in the membrane fraction of bovine brain. This single amino acid substitution leads to the decreased release of gonadotropin-releasing hormone (GnRH) in immortalized hypothalamic GT1-7 cells. Cows with GRIA1Asn have a slower luteinizing hormone (LH) surge than cows with GRIA1Ser. In addition, cows with GRIA1Asn possess fewer immature ovarian follicles before superovulation and have a lower response to hormone treatment than cows with GRIA1Ser. Our work identified that GRIA1 is a critical mediator of ovulation and that GRIA1 might be a useful target for reproductive therapy.
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Affiliation(s)
| | - Shinji Sasaki
- Shirakawa Institute of Animal Genetics, Nishigo, Japan
| | | | | | | | - Maya Yamazaki
- Brain Research Institute, Niigata University, Niigata, Japan
| | - Keiko Matsuda
- Department of Physiology, Keio University School of Medicine, Tokyo, Japan
| | - Michisuke Yuzaki
- Department of Physiology, Keio University School of Medicine, Tokyo, Japan
| | - Kenji Sakimura
- Brain Research Institute, Niigata University, Niigata, Japan
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34
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Ambert N, Greget R, Haeberlé O, Bischoff S, Berger TW, Bouteiller JM, Baudry M. Computational studies of NMDA receptors: differential effects of neuronal activity on efficacy of competitive and non-competitive antagonists. ACTA ACUST UNITED AC 2010; 2:113-125. [PMID: 21572937 DOI: 10.2147/oab.s7246] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
N-Methyl-D-Aspartate receptors (NMDARs) play important physiological as well as pathological roles in the central nervous system (CNS). While NMDAR competitive antagonists, such as D-2-Amino-5-Phosphopentanoic acid (AP5) have been shown to impair learning and memory, the non-competitive antagonist, memantine, is paradoxically beneficial in mild to moderate Alzheimer's disease (AD) patients. It has been proposed that differences in kinetic properties could account for antagonist functional differences. Here we present a new elaborated kinetic model of NMDARs that incorporates binding sites for the agonist (glutamate) and co-agonist (glycine), channel blockers, such as memantine and magnesium (Mg(2+)), as well as competitive antagonists. We first validated and optimized the parameters used in the model by comparing simulated results with a wide range of experimental data from the literature. We then evaluated the effects of stimulation frequency and membrane potential (Vm) on the characteristics of AP5 and memantine inhibition of NMDARs. Our results indicated that the inhibitory effects of AP5 were independent of Vm but decreased with increasing stimulation frequency. In contrast, memantine inhibitory effects decreased with both increasing Vm and stimulation frequency. They support the idea that memantine could provide tonic blockade of NMDARs under basal stimulation conditions without blocking their activation during learning. Moreover they underline the necessity of considering receptor kinetics and the value of the biosimulation approach to better understand mechanisms of drug action and to identify new ways of regulating receptor function.
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Affiliation(s)
- Nicolas Ambert
- Rhenovia Pharma, 20 C rue de Chemnitz, 68200 Mulhouse, France
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35
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Hansen KB, Furukawa H, Traynelis SF. Control of assembly and function of glutamate receptors by the amino-terminal domain. Mol Pharmacol 2010; 78:535-49. [PMID: 20660085 DOI: 10.1124/mol.110.067157] [Citation(s) in RCA: 88] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
The extracellular amino-terminal domains (ATDs) of the ionotropic glutamate receptor subunits form a semiautonomous component of all glutamate receptors that resides distal to the membrane and controls a surprisingly diverse set of receptor functions. These functions include subunit assembly, receptor trafficking, channel gating, agonist potency, and allosteric modulation. The many divergent features of the different ionotropic glutamate receptor classes and different subunits within a class may stem from differential regulation by the amino-terminal domains. The emerging knowledge of the structure and function of the amino-terminal domains reviewed here may enable targeting of this region for the therapeutic modulation of glutamatergic signaling. Toward this end, NMDA receptor antagonists that interact with the GluN2B ATD show promise in animal models of ischemia, neuropathic pain, and Parkinson's disease.
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Affiliation(s)
- Kasper B Hansen
- Department of Pharmacology, Emory University School of Medicine, Rollins Research Center, 1510 Clifton Road, Atlanta, GA 30322-3090, USA
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36
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Paul S, Connor JA. NR2B-NMDA receptor-mediated increases in intracellular Ca2+ concentration regulate the tyrosine phosphatase, STEP, and ERK MAP kinase signaling. J Neurochem 2010; 114:1107-18. [PMID: 20524968 DOI: 10.1111/j.1471-4159.2010.06835.x] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
NMDA receptors regulate both the activation and inactivation of the extracellular signal-regulated kinase (ERK) signaling cascade, a key pathway involved in neuronal plasticity and survival. This bi-directional regulation of ERK activity by NMDA receptors has been attributed to opposing actions of NR2A- versus NR2B-containing NMDA receptors, but how this is implemented is not understood. Here, we show that glutamate-mediated intracellular Ca(2+) increases occur in two phases, a rapid initial increase followed by a delayed larger increase. Both phases of the Ca(2+) increase were blocked by MK-801, a non-selective NMDA receptor inhibitor. On the other hand, selective inhibition of NR2B-NMDA receptors by Ifenprodil or Ro 25-6981 blocked the delayed larger phase but had only a small effect on the rapid initial increase. The rapid initial increase in Ca(2+), presumably because of NR2A-NMDAR activation, was sufficient to activate ERK, whereas the large delayed increases in Ca(2+) mediated by NR2B-NMDARs were necessary for dephosphorylation and subsequent activation of striatal-enriched phosphatase, a neuron-specific tyrosine phosphatase that in turn mediates the dephosphorylation and inactivation of ERK. We conclude that the magnitude of Ca(2+) increases mediated through NR2B-NMDA receptors plays a critical role in the regulation of the serine/threonine and tyrosine kinases and phosphatases that are involved in the regulation of ERK activity.
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Affiliation(s)
- Surojit Paul
- Department of Neurology, University of New Mexico Health Sciences Center, University of New Mexico, Albuquerque, New Mexico 87131, USA.
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37
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Madry C, Betz H, Geiger JRP, Laube B. Potentiation of Glycine-Gated NR1/NR3A NMDA Receptors Relieves Ca-Dependent Outward Rectification. Front Mol Neurosci 2010; 3:6. [PMID: 20407581 PMCID: PMC2854533 DOI: 10.3389/fnmol.2010.00006] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2009] [Accepted: 03/04/2010] [Indexed: 11/20/2022] Open
Abstract
Glycine has diverse functions within the mammalian central nervous system. It inhibits postsynaptic neurons via strychnine-sensitive glycine receptors (GlyRs) and enhances neuronal excitation through co-activation of N-methyl-D-aspartate (NMDA) receptors. Classical Ca2+-permeable NMDA receptors are composed of glycine-binding NR1 and glutamate-binding NR2 subunits, and hence require both glutamate and glycine for efficient activation. In contrast, recombinant receptors composed of NR1 and the glycine binding NR3A and/or NR3B subunits lack glutamate binding sites and can be activated by glycine alone. Therefore these receptors are also named “excitatory glycine receptors”. Co-application of antagonists of the NR1 glycine-binding site or of the divalent cation Zn2+ markedly enhances the glycine responses of these receptors. To gain further insight into the properties of these glycine-gated NMDA receptors, we investigated their current-voltage (I–V) dependence. Whole-cell current-voltage relations of glycine currents recorded from NR1/NR3B and NR1/NR3A/NR3B expressing oocytes were found to be linear under our recording conditions. In contrast, NR1/NR3A receptors displayed a strong outwardly rectifying I–V relation. Interestingly, the voltage-dependent inward current block was abolished in the presence of NR1 antagonists, Zn2+ or a combination of both. Further analysis revealed that Ca2+ (1.8 mM) present in our recording solutions was responsible for the voltage-dependent inhibition of ion flux through NR1/NR3A receptors. Since physiological concentrations of the divalent cation Mg2+ did not affect the I–V dependence, our data suggest that relief of the voltage-dependent Ca2+ block of NR1/NR3A receptors by Zn2+ may be important for the regulation of excitatory glycinergic transmission, according to the Mg2+-block of conventional NR1/NR2 NMDA receptors.
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Affiliation(s)
- Christian Madry
- Department of Neurochemistry, Max-Planck Institute for Brain Research Frankfurt am Main, Germany
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38
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Torashima T, Iizuka A, Horiuchi H, Mitsumura K, Yamasaki M, Koyama C, Takayama K, Iino M, Watanabe M, Hirai H. Rescue of abnormal phenotypes in δ2 glutamate receptor-deficient mice by the extracellular N-terminal and intracellular C-terminal domains of the δ2 glutamate receptor. Eur J Neurosci 2009; 30:355-65. [DOI: 10.1111/j.1460-9568.2009.06841.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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39
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Schmidt C, Klein C, Hollmann M. Xenopus laevis Oocytes Endogenously Express All Subunits of the Ionotropic Glutamate Receptor Family. J Mol Biol 2009; 390:182-95. [DOI: 10.1016/j.jmb.2009.05.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2009] [Revised: 05/07/2009] [Accepted: 05/07/2009] [Indexed: 01/27/2023]
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40
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Qiu S, Zhang XM, Cao JY, Yang W, Yan YG, Shan L, Zheng J, Luo JH. An endoplasmic reticulum retention signal located in the extracellular amino-terminal domain of the NR2A subunit of N-Methyl-D-aspartate receptors. J Biol Chem 2009; 284:20285-98. [PMID: 19487695 DOI: 10.1074/jbc.m109.004960] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
N-Methyl-d-aspartate (NMDA) receptors play critical roles in complex brain functions as well as pathogenesis of neurodegenerative diseases. There are many NMDA isoforms and subunit types that, together with subtype-specific assembly, give rise to significant functional heterogeneity of NMDA receptors. Conventional NMDA receptors are obligatory heterotetramers composed of two glycine-binding NR1 subunits and two glutamate-binding NR2 subunits. When individually expressed in heterogeneous cells, most of the NR1 splice variants and the NR2 subunits remain in the endoplasmic reticulum (ER) and do not form homomeric channels. The mechanisms underlying NMDA receptor trafficking and functional expression remain uncertain. Using truncated and chimeric NMDA receptor subunits expressed in heterogeneous cells and hippocampal neurons, together with immunostaining, biochemical, and functional analyses, we found that the NR2A amino-terminal domain (ATD) contains an ER retention signal, which can be specifically masked by the NR1a ATD. Interestingly, no such signal was found in the ATD of the NR2B subunit. We further identified the A2 segment of the NR2A ATD to be the primary determinant of ER retention. These findings indicate that NR2A-containing NMDA receptors may undergo a different ER quality control process from NR2B-containing NMDA receptors.
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Affiliation(s)
- Shuang Qiu
- Department of Neurobiology, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
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41
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Gavazzo P, Guida P, Zanardi I, Marchetti C. Molecular Determinants of Multiple Effects of Nickel on NMDA Receptor Channels. Neurotox Res 2009; 15:38-48. [DOI: 10.1007/s12640-009-9003-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2008] [Revised: 10/31/2008] [Accepted: 10/31/2008] [Indexed: 01/08/2023]
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42
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Supralinear potentiation of NR1/NR3A excitatory glycine receptors by Zn2+ and NR1 antagonist. Proc Natl Acad Sci U S A 2008; 105:12563-8. [PMID: 18711142 DOI: 10.1073/pnas.0805624105] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Coassembly of the glycine-binding NMDA receptor subunits NR1 and NR3A results in excitatory glycine receptors of low efficacy. Here, we report that micromolar concentrations of the divalent cation Zn(2+) produce a 10-fold potentiation of NR1/NR3A receptor responses, which resembles that seen upon antagonizing glycine binding to the NR1 subunit. Coapplication of both Zn(2+) and NR1 antagonist caused a supralinear potentiation, resulting in a >120-fold increase of glycine-activated currents. At concentrations >50 microM, Zn(2+) alone generated receptor currents with similar efficacy as glycine, implying that NR1/NR3A receptors can be activated by different agonists. Point mutations in the NR1 and NR3A glycine-binding sites revealed that both the potentiating and agonistic effects of Zn(2+) are mediated by the ligand-binding domain of the NR1 subunit. In conclusion, Zn(2+) acts as a potent positive modulator and agonist at the NR1 subunit of NR1/NR3A receptors. Our results suggest that this unconventional member of the NMDA receptor family may in vivo be gated by the combined action of glycine and Zn(2+) or a yet unknown second ligand.
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Stephenson FA, Cousins SL, Kenny AV. Assembly and forward trafficking of NMDA receptors (Review). Mol Membr Biol 2008; 25:311-20. [PMID: 18446617 DOI: 10.1080/09687680801971367] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
N-Methyl-D-aspartate (NMDA) receptors are a subclass of the excitatory, ionotropic L-glutamate neurotransmitter receptors. They are important for normal brain function being both primary candidates for the molecular basis of learning and memory and in the establishment of synaptic connections during the development of the central nervous system. NMDA receptors are also implicated in neurological and psychiatric disorders. Their dysfunction which is primarily due to either hypo- or hyper-activity is pivotal to these pathological conditions. There is thus a fine balance between NMDA receptor-mediated mechanisms in normal brain and those in diseased states where receptor homeostasis is perturbed. Receptor activity is due in part to the number of surface expressed receptors. Understanding the assembly and trafficking of this complex, heteromeric, neurotransmitter receptor family may therefore, be pivotal to understanding diseases in which their altered activity is evident. This article will review the current understanding of the mechanisms of NMDA receptor assembly, how this assembly is regulated and how assembled receptors are trafficked to their appropriate sites in post-synaptic membranes where they are integral components of a macromolecular signalling complex.
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Gielen M, Le Goff A, Stroebel D, Johnson JW, Neyton J, Paoletti P. Structural rearrangements of NR1/NR2A NMDA receptors during allosteric inhibition. Neuron 2008; 57:80-93. [PMID: 18184566 DOI: 10.1016/j.neuron.2007.11.021] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2007] [Revised: 09/21/2007] [Accepted: 11/07/2007] [Indexed: 10/22/2022]
Abstract
Ionotropic glutamate receptor (iGluR) subunits contain a large N-terminal domain (NTD) that precedes the agonist-binding domain (ABD) and participates in subunit oligomerization. In NMDA receptors (NMDARs), the NTDs of NR2A and NR2B subunits also form binding sites for the endogenous inhibitor Zn(2+) ion. Although these allosteric sites have been characterized in detail, the molecular mechanisms by which the NTDs communicate with the rest of the receptor to promote its inhibition remain unknown. Here, we identify the ABD dimer interface as a major structural determinant that permits coupling between the NTDs and the channel gate. The strength of this interface also controls proton inhibition, another form of allosteric modulation of NMDARs. Conformational rearrangements at the ABD dimer interface thus appear to be a key mechanism conserved in all iGluR subfamilies, but have evolved to fulfill different functions: fast desensitization at AMPA and kainate receptors, allosteric inhibition at NMDARs.
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Affiliation(s)
- Marc Gielen
- Laboratoire de Neurobiologie, Ecole Normale Supérieure, CNRS, 46 rue d'Ulm, 75005 Paris, France
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Schüler T, Mesic I, Madry C, Bartholomäus I, Laube B. Formation of NR1/NR2 and NR1/NR3 Heterodimers Constitutes the Initial Step in N-Methyl-D-aspartate Receptor Assembly. J Biol Chem 2008; 283:37-46. [DOI: 10.1074/jbc.m703539200] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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