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Ballestín R, Torres J, Ponsoda X. TSQ Incubation Enhances Autometallographic Zinc Detection in Cultured Astrocytes. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2024; 30:759-770. [PMID: 39027929 DOI: 10.1093/mam/ozae060] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2023] [Revised: 04/01/2024] [Accepted: 06/18/2024] [Indexed: 07/20/2024]
Abstract
Zinc is a critical ion for a large number of cellular functions. In the central nervous system, zinc ions are involved in synaptic transmission. Therefore, zinc homeostasis is essential, and cells have developed a variety of mechanisms to control cellular zinc concentration, including the zincosome formation. Alterations of free zinc levels have been associated with brain dysfunction and are present in many illnesses and syndromes. Astrocytes are implicated in the maintenance of the neuronal milleu and brain homeostasis. In this work, we have analyzed the combination of direct (TSQ) and indirect (autometallography) zinc detection methods to increase sensitivity for studying zinc uptake by rat astrocytes in vitro. Zincosome formation was visualized with the zinc fluorochrome TSQ by light microscopy. Additionally, we improved both zinc precipitation and cellular fixation methods to preserve zinc ions and make them suitable for autometallography development. Our tests pinpointed paraformaldehyde and sodium sulfide as the more adequate methods for cellular fixation and zinc precipitation, respectively. TSQ incubation and pH of the fixative were shown to be crucial for autometallography. Using this improved method, we visualized the zinc content of zincosomes at the ultrastructural level both as silver autometallographic precipitates and as electrodense sulfide-osmium zinc precipitates.
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Affiliation(s)
- Raúl Ballestín
- Departamento Biología Celular, Biología Funcional y Antropología Física, Universitat de València, 46100 Burjassot, Valencia, Spain
| | - Josema Torres
- Departamento Biología Celular, Biología Funcional y Antropología Física, Universitat de València, 46100 Burjassot, Valencia, Spain
| | - Xavier Ponsoda
- Departamento Biología Celular, Biología Funcional y Antropología Física, Universitat de València, 46100 Burjassot, Valencia, Spain
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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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Sameei P, Fatehfar S, Abdollahzadeh N, Chodari L, Saboory E, Roshan-Milani S. The effects of forced exercise and zinc supplementation during pregnancy on prenatally stress-induced behavioral and neurobiological consequences in adolescent female rat offspring. Dev Psychobiol 2023; 65:e22411. [PMID: 37607889 DOI: 10.1002/dev.22411] [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: 04/09/2022] [Revised: 04/10/2023] [Accepted: 06/23/2023] [Indexed: 08/24/2023]
Abstract
Prenatal manipulations can lead to neurobehavioral changes in the offspring. In this study, individual and combined effects of forced exercise and zinc supplementation during pregnancy on prenatally restraint stress (PRS)-induced behavioral impairments, neuro-inflammatory responses, and oxidative stress have been investigated in adolescent female rat offspring. Pregnant rats were divided into five groups: control; restraint stress (RS); RS + exercise stress (RS + ES), RS + zinc supplementation (RS + Zn); and RS + ES + Zn. All the pregnant rats (except control) were exposed to RS from gestational days 15 to 19. Pregnant rats in ES groups were subjected to forced treadmill exercise (30 min/daily), and in Zn groups to zinc sulfate (30 mg/kg/orally), throughout the pregnancy. At postnatal days 25-27, anxiety-like and stress-coping behaviors were recorded, and the gene expressions of interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) and the concentration of total antioxidant capacity were measured in the prefrontal cortex. PRS significantly enhanced anxiety, generated passive coping behaviors, increased IL-1β and TNF-α expression, and decreased the antioxidant capacity. ES potentiated while zinc reversed PRS-induced behavioral impairments. Prenatal zinc also restored the anti-inflammatory and antioxidant capacity but had no effect on additive responses imposed by the combination of RS and ES. Suppression of PRS-induced behavioral and neurobiological impairments by zinc suggests the probable clinical importance of zinc on PRS-induced changes on child temperament.
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Affiliation(s)
- Parsa Sameei
- Student Research Committee, Urmia University of Medical Sciences, Urmia, Iran
| | - Sina Fatehfar
- Student Research Committee, Urmia University of Medical Sciences, Urmia, Iran
- School of Pharmacy, Urmia University of Medical Sciences, Urmia, Iran
- Cellular and Molecular Research Center, Cellular and Molecular Medicine Research Institute, Urmia University of Medical Sciences, Urmia, Iran
| | - Naseh Abdollahzadeh
- Neurophysiology Research Center, Cellular and Molecular Medicine Research Institute, Urmia University of Medical Sciences, Urmia, Iran
| | - Leila Chodari
- Neurophysiology Research Center, Cellular and Molecular Medicine Research Institute, Urmia University of Medical Sciences, Urmia, Iran
| | - Ehsan Saboory
- Zanjan Metabolic Diseases Research Center, Zanjan University of Medical Sciences, Zanjan, Iran
| | - Shiva Roshan-Milani
- Neurophysiology Research Center, Cellular and Molecular Medicine Research Institute, Urmia University of Medical Sciences, Urmia, Iran
- Department of Physiology, School of Medicine, Urmia University of Medical Sciences, Urmia, Iran
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4
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Zhou C, Tajima N. Structural insights into NMDA receptor pharmacology. Biochem Soc Trans 2023; 51:1713-1731. [PMID: 37431773 PMCID: PMC10586783 DOI: 10.1042/bst20230122] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2023] [Revised: 06/12/2023] [Accepted: 06/16/2023] [Indexed: 07/12/2023]
Abstract
N-methyl-d-aspartate receptors (NMDARs) comprise a subfamily of ionotropic glutamate receptors that form heterotetrameric ligand-gated ion channels and play fundamental roles in neuronal processes such as synaptic signaling and plasticity. Given their critical roles in brain function and their therapeutic importance, enormous research efforts have been devoted to elucidating the structure and function of these receptors and developing novel therapeutics. Recent studies have resolved the structures of NMDARs in multiple functional states, and have revealed the detailed gating mechanism, which was found to be distinct from that of other ionotropic glutamate receptors. This review provides a brief overview of the recent progress in understanding the structures of NMDARs and the mechanisms underlying their function, focusing on subtype-specific, ligand-induced conformational dynamics.
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Affiliation(s)
- Changping Zhou
- Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, OH, U.S.A
| | - Nami Tajima
- Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, OH, U.S.A
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5
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Paudyal N, Das A, Carrillo E, Berka V, Jayaraman V. Partial agonism in heteromeric GLUK2/GLUK5 kainate receptor. Proteins 2023:10.1002/prot.26565. [PMID: 37526035 PMCID: PMC10830895 DOI: 10.1002/prot.26565] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Revised: 07/13/2023] [Accepted: 07/21/2023] [Indexed: 08/02/2023]
Abstract
Kainate receptors are a subtype of ionotropic glutamate receptors that form transmembrane channels upon binding glutamate. Here, we have investigated the mechanism of partial agonism in heteromeric GluK2/K5 receptors, where the GluK2 and GluK5 subunits have distinct agonist binding profiles. Using single-molecule Förster resonance energy transfer, we found that at the bi-lobed agonist-binding domain, the partial agonist AMPA-bound receptor occupied intermediate cleft closure conformational states at the GluK2 cleft, compared to the more open cleft conformations in apo form and more closed cleft conformations in the full agonist glutamate-bound form. In contrast, there is no significant difference in cleft closure states at the GluK5 agonist-binding domain between the partial agonist AMPA- and full agonist glutamate-bound states. Additionally, unlike the glutamate-bound state, the dimer interface at the agonist-binding domain is not decoupled in the AMPA-bound state. Our findings suggest that partial agonism observed with AMPA binding is mediated primarily due to differences in the GluK2 subunit, highlighting the distinct contributions of the subunits towards activation.
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Affiliation(s)
- Nabina Paudyal
- Center for Membrane Biology, Department of Biochemistry and Molecular Biology, University of Texas Health Science Center at Houston, Houston, TX 77030
- MD Anderson Cancer Center UTHealth Graduate School of Biomedical Sciences, University of Texas Health Science Center at Houston, Houston, TX 77030
| | - Anindita Das
- Center for Membrane Biology, Department of Biochemistry and Molecular Biology, University of Texas Health Science Center at Houston, Houston, TX 77030
| | - Elisa Carrillo
- Center for Membrane Biology, Department of Biochemistry and Molecular Biology, University of Texas Health Science Center at Houston, Houston, TX 77030
| | - Vladimir Berka
- Center for Membrane Biology, Department of Biochemistry and Molecular Biology, University of Texas Health Science Center at Houston, Houston, TX 77030
| | - Vasanthi Jayaraman
- Center for Membrane Biology, Department of Biochemistry and Molecular Biology, University of Texas Health Science Center at Houston, Houston, TX 77030
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6
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Tian M, Stroebel D, Piot L, David M, Ye S, Paoletti P. GluN2A and GluN2B NMDA receptors use distinct allosteric routes. Nat Commun 2021; 12:4709. [PMID: 34354080 PMCID: PMC8342458 DOI: 10.1038/s41467-021-25058-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Accepted: 07/21/2021] [Indexed: 11/17/2022] Open
Abstract
Allostery represents a fundamental mechanism of biological regulation that involves long-range communication between distant protein sites. It also provides a powerful framework for novel therapeutics. NMDA receptors (NMDARs), glutamate-gated ionotropic receptors that play central roles in synapse maturation and plasticity, are prototypical allosteric machines harboring large extracellular N-terminal domains (NTDs) that provide allosteric control of key receptor properties with impact on cognition and behavior. It is commonly thought that GluN2A and GluN2B receptors, the two predominant NMDAR subtypes in the adult brain, share similar allosteric transitions. Here, combining functional and structural interrogation, we reveal that GluN2A and GluN2B receptors utilize different long-distance allosteric mechanisms involving distinct subunit-subunit interfaces and molecular rearrangements. NMDARs have thus evolved multiple levels of subunit-specific allosteric control over their transmembrane ion channel pore. Our results uncover an unsuspected diversity in NMDAR molecular mechanisms with important implications for receptor physiology and precision drug development. NMDA receptors are glutamate-gated ion channels essential for synapse maturation and plasticity. Here the authors show that GluN2A and GluN2B NMDA receptors — the two principal subtypes NMDARs in the adult CNS — operate through distinct long range allosteric mechanisms.
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Affiliation(s)
- Meilin Tian
- Institut de Biologie de l'Ecole Normale Supérieure (IBENS), Ecole Normale Supérieure, Université PSL, CNRS, INSERM, Paris, France
| | - David Stroebel
- Institut de Biologie de l'Ecole Normale Supérieure (IBENS), Ecole Normale Supérieure, Université PSL, CNRS, INSERM, Paris, France
| | - Laura Piot
- Institut de Biologie de l'Ecole Normale Supérieure (IBENS), Ecole Normale Supérieure, Université PSL, CNRS, INSERM, Paris, France
| | - Mélissa David
- Institut de Biologie de l'Ecole Normale Supérieure (IBENS), Ecole Normale Supérieure, Université PSL, CNRS, INSERM, Paris, France
| | - Shixin Ye
- Unité INSERM U1195, Hôpital de Bicêtre, Université Paris-Saclay, Paris, Le Kremlin-Bicêtre, France.
| | - Pierre Paoletti
- Institut de Biologie de l'Ecole Normale Supérieure (IBENS), Ecole Normale Supérieure, Université PSL, CNRS, INSERM, Paris, France.
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7
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Bhatia NK, Carrillo E, Durham RJ, Berka V, Jayaraman V. Allosteric Changes in the NMDA Receptor Associated with Calcium-Dependent Inactivation. Biophys J 2020; 119:2349-2359. [PMID: 33098865 DOI: 10.1016/j.bpj.2020.08.045] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Revised: 08/14/2020] [Accepted: 08/20/2020] [Indexed: 01/07/2023] Open
Abstract
N-methyl-D-aspartate (NMDA) receptors mediate synaptic excitatory signaling in the mammalian central nervous system by forming calcium-permeable transmembrane channels upon binding glutamate and coagonist glycine. Ca2+ influx through NMDA receptors leads to channel inactivation through a process mediated by resident calmodulin bound to the intracellular C-terminal segment of the GluN1 subunit of the receptor. Using single-molecule FRET investigations, we show that in the presence of calcium-calmodulin, the distance across the two GluN1 subunits at the entrance of the first transmembrane segment is shorter and the bilobed cleft of the glycine-binding domain in GluN1 is more closed when bound to glycine and glutamate relative to what is observed in the presence of barium-calmodulin. Consistent with these observations, the glycine deactivation rate is slower in the presence of calcium-calmodulin. Taken together, these results show that the binding of calcium-calmodulin to the C-terminus has long-range allosteric effects on the extracellular segments of the receptor that may contribute to the calcium-dependent inactivation.
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Affiliation(s)
- Nidhi Kaur Bhatia
- Center for Membrane Biology, Department of Biochemistry and Molecular Biology, University of Texas Health Science Center at Houston, Houston, Texas
| | - Elisa Carrillo
- Center for Membrane Biology, Department of Biochemistry and Molecular Biology, University of Texas Health Science Center at Houston, Houston, Texas
| | - Ryan J Durham
- Center for Membrane Biology, Department of Biochemistry and Molecular Biology, University of Texas Health Science Center at Houston, Houston, Texas; MD Anderson Cancer Center UTHealth Graduate School of Biomedical Sciences, University of Texas Health Science Center at Houston, Houston, Texas
| | - Vladimir Berka
- Center for Membrane Biology, Department of Biochemistry and Molecular Biology, University of Texas Health Science Center at Houston, Houston, Texas
| | - Vasanthi Jayaraman
- Center for Membrane Biology, Department of Biochemistry and Molecular Biology, University of Texas Health Science Center at Houston, Houston, Texas; MD Anderson Cancer Center UTHealth Graduate School of Biomedical Sciences, University of Texas Health Science Center at Houston, Houston, Texas.
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8
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Durham RJ, Paudyal N, Carrillo E, Bhatia NK, Maclean DM, Berka V, Dolino DM, Gorfe AA, Jayaraman V. Conformational spread and dynamics in allostery of NMDA receptors. Proc Natl Acad Sci U S A 2020; 117:3839-3847. [PMID: 32015122 PMCID: PMC7035515 DOI: 10.1073/pnas.1910950117] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Allostery can be manifested as a combination of repression and activation in multidomain proteins allowing for fine tuning of regulatory mechanisms. Here we have used single molecule fluorescence resonance energy transfer (smFRET) and molecular dynamics simulations to study the mechanism of allostery underlying negative cooperativity between the two agonists glutamate and glycine in the NMDA receptor. These data show that binding of one agonist leads to conformational flexibility and an increase in conformational spread at the second agonist site. Mutational and cross-linking studies show that the dimer-dimer interface at the agonist-binding domain mediates the allostery underlying the negative cooperativity. smFRET on the transmembrane segments shows that they are tightly coupled in the unliganded and single agonist-bound form and only upon binding both agonists the transmembrane domain explores looser packing which would facilitate activation.
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Affiliation(s)
- Ryan J Durham
- Center for Membrane Biology, Department of Biochemistry and Molecular Biology, University of Texas Health Science Center at Houston, Houston, TX 77030
- MD Anderson Cancer Center UTHealth Graduate School of Biomedical Sciences, University of Texas Health Science Center at Houston, Houston, TX 77030
| | - Nabina Paudyal
- Center for Membrane Biology, Department of Biochemistry and Molecular Biology, University of Texas Health Science Center at Houston, Houston, TX 77030
- MD Anderson Cancer Center UTHealth Graduate School of Biomedical Sciences, University of Texas Health Science Center at Houston, Houston, TX 77030
| | - Elisa Carrillo
- Center for Membrane Biology, Department of Biochemistry and Molecular Biology, University of Texas Health Science Center at Houston, Houston, TX 77030
| | - Nidhi Kaur Bhatia
- Center for Membrane Biology, Department of Biochemistry and Molecular Biology, University of Texas Health Science Center at Houston, Houston, TX 77030
| | - David M Maclean
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, NY 14642
| | - Vladimir Berka
- Center for Membrane Biology, Department of Biochemistry and Molecular Biology, University of Texas Health Science Center at Houston, Houston, TX 77030
| | - Drew M Dolino
- Center for Membrane Biology, Department of Biochemistry and Molecular Biology, University of Texas Health Science Center at Houston, Houston, TX 77030
- MD Anderson Cancer Center UTHealth Graduate School of Biomedical Sciences, University of Texas Health Science Center at Houston, Houston, TX 77030
| | - Alemayehu A Gorfe
- MD Anderson Cancer Center UTHealth Graduate School of Biomedical Sciences, University of Texas Health Science Center at Houston, Houston, TX 77030
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center at Houston, Houston, TX 77030
| | - Vasanthi Jayaraman
- Center for Membrane Biology, Department of Biochemistry and Molecular Biology, University of Texas Health Science Center at Houston, Houston, TX 77030;
- MD Anderson Cancer Center UTHealth Graduate School of Biomedical Sciences, University of Texas Health Science Center at Houston, Houston, TX 77030
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9
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Alizadeh F, Davoodian N, Kazemi H, Ghasemi-Kasman M, Shaerzadeh F. Prenatal zinc supplementation attenuates lipopolysaccharide-induced behavioral impairments in maternal immune activation model. Behav Brain Res 2019; 377:112247. [PMID: 31545978 DOI: 10.1016/j.bbr.2019.112247] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2019] [Revised: 09/05/2019] [Accepted: 09/16/2019] [Indexed: 11/16/2022]
Abstract
Maternal infection during pregnancy is considered a key risk factor for developing schizophrenia in offspring. There is evidence that maternal exposure to infectious agents is associated with fetal zinc deficiency. Due to the essential role of zinc in brain function and development, in the present study, we activated maternal immune system using lipopolysaccharide (LPS) as a model of schizophrenia to examine whether zinc supplementation throughout pregnancy can reverse LPS-induced deleterious effects. To test the hypothesis, pregnant rats were treated with intraperitoneal injection of either saline or LPS (0.5 mg/kg) at gestational day 15 and 16, and zinc supplementation (30 mg/kg) was administered throughout pregnancy by gavage. At postnatal day 60, Y-maze was used to evaluate working memory of offspring. Moreover, the expression levels of catechol O-methyltransferase (COMT) and glutamate decarboxylase 67 (GAD67) were measured in the frontal cortex of the brain samples. Only male offspring prenatally exposed to LPS showed a significant impairment in working memory. In addition, prenatal LPS exposure causes a moderate decrease in GAD67 expression level in the male pups, while COMT expression was found unchanged. Interestingly, zinc supplementation restored the alterations in working memory as well as GAD67 mRNA level in the male rats. No alteration was detected for neither working memory nor COMT/GAD67 genes expression in female offspring. This study demonstrates that zinc supplementation during pregnancy can attenuate LPS-induced impairments in male pups. These results support the idea to consume zinc supplementation during pregnancy to limit neurodevelopmental deficits induced by infections in offspring.
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Affiliation(s)
- Faezeh Alizadeh
- Endocrinology and Metabolism Research Center, Hormozgan University of Medical Sciences, Bandar Abbas, Iran
| | - Nahid Davoodian
- Molecular Medicine Research Center, Hormozgan Health Institute, Hormozgan University of Medical Sciences, Bandar Abbas, Iran; Department of Clinical Biochemistry, Faculty of Medicine, Hormozgan University of Medical Sciences, Bandar Abbas, Iran.
| | - Haniyeh Kazemi
- Molecular Medicine Research Center, Hormozgan Health Institute, Hormozgan University of Medical Sciences, Bandar Abbas, Iran
| | - Maryam Ghasemi-Kasman
- Infertility and Reproductive Health Research Center, Health Research Institute, Babol University of Medical Science, Babol, Iran; Cellular and Molecular Biology Research Center, Health Research Institute, Babol University of Medical Sciences, Babol, Iran
| | - Fatemeh Shaerzadeh
- Department of Neuroscience, University of Florida College of Medicine and McKnight Brain Institute, Gainesville, FL, 32610, USA
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10
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Jalali-Yazdi F, Chowdhury S, Yoshioka C, Gouaux E. Mechanisms for Zinc and Proton Inhibition of the GluN1/GluN2A NMDA Receptor. Cell 2019; 175:1520-1532.e15. [PMID: 30500536 DOI: 10.1016/j.cell.2018.10.043] [Citation(s) in RCA: 77] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Revised: 08/26/2018] [Accepted: 10/19/2018] [Indexed: 11/19/2022]
Abstract
N-methyl-D-aspartate receptors (NMDARs) play essential roles in memory formation, neuronal plasticity, and brain development, with their dysfunction linked to a range of disorders from ischemia to schizophrenia. Zinc and pH are physiological allosteric modulators of NMDARs, with GluN2A-containing receptors inhibited by nanomolar concentrations of divalent zinc and by excursions to low pH. Despite the widespread importance of zinc and proton modulation of NMDARs, the molecular mechanism by which these ions modulate receptor activity has proven elusive. Here, we use cryoelectron microscopy to elucidate the structure of the GluN1/GluN2A NMDAR in a large ensemble of conformations under a range of physiologically relevant zinc and proton concentrations. We show how zinc binding to the amino terminal domain elicits structural changes that are transduced though the ligand-binding domain and result in constriction of the ion channel gate.
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Affiliation(s)
- Farzad Jalali-Yazdi
- Vollum Institute, Oregon Health and Science University, Portland, OR 97239, USA
| | - Sandipan Chowdhury
- Vollum Institute, Oregon Health and Science University, Portland, OR 97239, USA
| | - Craig Yoshioka
- Vollum Institute, Oregon Health and Science University, Portland, OR 97239, USA
| | - Eric Gouaux
- Vollum Institute, Oregon Health and Science University, Portland, OR 97239, USA; Department of Biomedical Engineering, Oregon Health and Science University, Portland, OR 97239, USA; Howard Hughes Medical Institute, Oregon Health and Science University, Portland, OR 97239, USA.
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11
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Chen J, Li L, Chen SR, Chen H, Xie JD, Sirrieh RE, MacLean DM, Zhang Y, Zhou MH, Jayaraman V, Pan HL. The α2δ-1-NMDA Receptor Complex Is Critically Involved in Neuropathic Pain Development and Gabapentin Therapeutic Actions. Cell Rep 2019; 22:2307-2321. [PMID: 29490268 PMCID: PMC5873963 DOI: 10.1016/j.celrep.2018.02.021] [Citation(s) in RCA: 173] [Impact Index Per Article: 34.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Revised: 12/20/2017] [Accepted: 02/06/2018] [Indexed: 12/13/2022] Open
Abstract
α2δ-1, commonly known as a voltage-activated Ca2+ channel subunit, is a binding site of gabapentinoids used to treat neuropathic pain and epilepsy. However, it is unclear how α2δ-1 contributes to neuropathic pain and gabapentinoid actions. Here, we show that Cacna2d1 overexpression potentiates presynaptic and postsynaptic NMDAR activity of spinal dorsal horn neurons to cause pain hypersensitivity. Conversely, Cacna2d1 knockdown or ablation normalizes synaptic NMDAR activity increased by nerve injury. α2δ-1 forms a heteromeric complex with NMDARs in rodent and human spinal cords. The α2δ-1-NMDAR interaction predominantly occurs through the C terminus of α2δ-1 and promotes surface trafficking and synaptic targeting of NMDARs. Gabapentin or an α2δ-1 C terminus-interfering peptide normalizes NMDAR synaptic targeting and activity increased by nerve injury. Thus, α2δ-1 is an NMDAR-interacting protein that increases NMDAR synaptic delivery in neuropathic pain. Gabapentinoids reduce neuropathic pain by inhibiting forward trafficking of α2δ-1-NMDAR complexes.
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Affiliation(s)
- Jinjun Chen
- Center for Neuroscience and Pain Research, Department of Anesthesiology and Perioperative Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA; College of Bioscience and Biotechnology, Hunan Agricultural University, Changsha, Hunan 410128, China
| | - Lingyong Li
- Center for Neuroscience and Pain Research, Department of Anesthesiology and Perioperative Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Shao-Rui Chen
- Center for Neuroscience and Pain Research, Department of Anesthesiology and Perioperative Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Hong Chen
- Center for Neuroscience and Pain Research, Department of Anesthesiology and Perioperative Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Jing-Dun Xie
- Center for Neuroscience and Pain Research, Department of Anesthesiology and Perioperative Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA; Department of Anesthesiology, Sun Yat-Sen University Cancer Center, Guangzhou, Guangdong 510060, China
| | - Rita E Sirrieh
- Department of Biochemistry and Molecular Biology, The University of Texas Health Science Center, Houston, TX 77030, USA
| | - David M MacLean
- Department of Biochemistry and Molecular Biology, The University of Texas Health Science Center, Houston, TX 77030, USA
| | - Yuhao Zhang
- Center for Neuroscience and Pain Research, Department of Anesthesiology and Perioperative Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Meng-Hua Zhou
- Center for Neuroscience and Pain Research, Department of Anesthesiology and Perioperative Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Vasanthi Jayaraman
- Department of Biochemistry and Molecular Biology, The University of Texas Health Science Center, Houston, TX 77030, USA
| | - Hui-Lin Pan
- Center for Neuroscience and Pain Research, Department of Anesthesiology and Perioperative Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA.
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12
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Dissecting diverse functions of NMDA receptors by structural biology. Curr Opin Struct Biol 2019; 54:34-42. [PMID: 30703613 DOI: 10.1016/j.sbi.2018.12.009] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2018] [Revised: 12/09/2018] [Accepted: 12/20/2018] [Indexed: 12/18/2022]
Abstract
N-Methyl-d-aspartate receptors (NMDARs) are glutamate-gated ion channels, which are critically involved in brain development, learning and memory, cognition, as well as a number of neurological diseases and disorders. Structural biology of NMDARs has been challenging due to technical difficulties associated with assembling a number of different membrane protein subunits. Here, we review historical X-ray crystallographic studies on isolated extracellular domains, which are still the most effective mean to delineate compound binding modes, as well as the most recent studies using electron cryo-microscopy (cryo-EM). A number of NMDAR structures accumulated over the past 15 years provide insights into the hetero-tetrameric assembly pattern, pharmacological specificities elicited by subtypes and alternative splicing, and potential patterns of conformational dynamics; however, many more important unanswered questions remain.
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13
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MacLean DM, Durham RJ, Jayaraman V. Mapping the Conformational Landscape of Glutamate Receptors Using Single Molecule FRET. Trends Neurosci 2018; 42:128-139. [PMID: 30385052 DOI: 10.1016/j.tins.2018.10.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Revised: 09/27/2018] [Accepted: 10/02/2018] [Indexed: 10/28/2022]
Abstract
The ionotropic glutamate receptors mediate excitatory neurotransmission in the mammalian central nervous system. These receptors provide a range of temporally diverse signals which stem from subunit composition and also from the inherent ability of each member to occupy multiple functional states, the distribution of which can be altered by small molecule modulators and binding partners. Hence it becomes essential to characterize the conformational landscape of the receptors under this variety of different conditions. This has recently become possible due to single molecule fluorescence resonance energy transfer measurements, along with the rich foundation of existing structures allowing for direct correlations between conformational and functional diversity.
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Affiliation(s)
- David M MacLean
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, NY 14642, USA
| | - Ryan J Durham
- Center for Membrane Biology, Department of Biochemistry and Molecular Biology, University of Texas Health Science Center at Houston, Houston, TX 77030, USA; Biochemistry and Cell Biology Graduate Program, Graduate School of Biomedical Sciences, University of Texas Health Science Center at Houston, Houston, TX 77030, USA
| | - Vasanthi Jayaraman
- Center for Membrane Biology, Department of Biochemistry and Molecular Biology, University of Texas Health Science Center at Houston, Houston, TX 77030, USA.
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14
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Hansen KB, Yi F, Perszyk RE, Furukawa H, Wollmuth LP, Gibb AJ, Traynelis SF. Structure, function, and allosteric modulation of NMDA receptors. J Gen Physiol 2018; 150:1081-1105. [PMID: 30037851 PMCID: PMC6080888 DOI: 10.1085/jgp.201812032] [Citation(s) in RCA: 321] [Impact Index Per Article: 53.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2018] [Accepted: 07/03/2018] [Indexed: 12/22/2022] Open
Abstract
Hansen et al. review recent structural data that have provided insight into the function and allosteric modulation of NMDA receptors. NMDA-type glutamate receptors are ligand-gated ion channels that mediate a Ca2+-permeable component of excitatory neurotransmission in the central nervous system (CNS). They are expressed throughout the CNS and play key physiological roles in synaptic function, such as synaptic plasticity, learning, and memory. NMDA receptors are also implicated in the pathophysiology of several CNS disorders and more recently have been identified as a locus for disease-associated genomic variation. NMDA receptors exist as a diverse array of subtypes formed by variation in assembly of seven subunits (GluN1, GluN2A-D, and GluN3A-B) into tetrameric receptor complexes. These NMDA receptor subtypes show unique structural features that account for their distinct functional and pharmacological properties allowing precise tuning of their physiological roles. Here, we review the relationship between NMDA receptor structure and function with an emphasis on emerging atomic resolution structures, which begin to explain unique features of this receptor.
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Affiliation(s)
- Kasper B Hansen
- Department of Biomedical and Pharmaceutical Sciences and Center for Biomolecular Structure and Dynamics, University of Montana, Missoula, MT
| | - Feng Yi
- Department of Biomedical and Pharmaceutical Sciences and Center for Biomolecular Structure and Dynamics, University of Montana, Missoula, MT
| | - Riley E Perszyk
- Department of Pharmacology, Emory University School of Medicine, Atlanta, GA
| | - Hiro Furukawa
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY
| | - Lonnie P Wollmuth
- Departments of Neurobiology & Behavior and Biochemistry & Cell Biology, Stony Brook University, Stony Brook, NY
| | - Alasdair J Gibb
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, UK
| | - Stephen F Traynelis
- Department of Pharmacology, Emory University School of Medicine, Atlanta, GA
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15
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Krieger J, Lee JY, Greger IH, Bahar I. Activation and desensitization of ionotropic glutamate receptors by selectively triggering pre-existing motions. Neurosci Lett 2018; 700:22-29. [PMID: 29481851 PMCID: PMC6107436 DOI: 10.1016/j.neulet.2018.02.050] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2017] [Revised: 02/15/2018] [Accepted: 02/22/2018] [Indexed: 01/03/2023]
Abstract
Ionotropic glutamate receptors (iGluRs) are ligand-gated ion channels that are key players in synaptic transmission and plasticity. They are composed of four subunits, each containing four functional domains, the quaternary packing and collective structural dynamics of which are important determinants of their molecular mechanism of function. With the explosion of structural studies on different members of the family, including the structures of activated open channels, the mechanisms of action of these central signaling machines are now being elucidated. We review the current state of computational studies on two major members of the family, AMPA and NMDA receptors, with focus on molecular simulations and elastic network model analyses that have provided insights into the coupled movements of extracellular and transmembrane domains. We describe the newly emerging mechanisms of activation, allosteric signaling and desensitization, as mainly a selective triggering of pre-existing soft motions, as deduced from computational models and analyses that leverage structural data on intact AMPA and NMDA receptors in different states.
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Affiliation(s)
- James Krieger
- Department of Computational and Systems Biology, School of Medicine, University of Pittsburgh, 3501 Fifth Ave, Suite 3064 BST3, Pittsburgh, PA, 15260, United States
| | - Ji Young Lee
- Department of Computational and Systems Biology, School of Medicine, University of Pittsburgh, 3501 Fifth Ave, Suite 3064 BST3, Pittsburgh, PA, 15260, United States
| | - Ingo H Greger
- Neurobiology Division, MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge, CB2 0QH, United Kingdom
| | - Ivet Bahar
- Department of Computational and Systems Biology, School of Medicine, University of Pittsburgh, 3501 Fifth Ave, Suite 3064 BST3, Pittsburgh, PA, 15260, United States.
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16
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Shaikh SA, Dolino DM, Lee G, Chatterjee S, MacLean DM, Flatebo C, Landes CF, Jayaraman V. Stargazin Modulation of AMPA Receptors. Cell Rep 2017; 17:328-335. [PMID: 27705782 DOI: 10.1016/j.celrep.2016.09.014] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2016] [Revised: 08/08/2016] [Accepted: 09/02/2016] [Indexed: 02/03/2023] Open
Abstract
Fast excitatory synaptic signaling in the mammalian brain is mediated by AMPA-type ionotropic glutamate receptors. In neurons, AMPA receptors co-assemble with auxiliary proteins, such as stargazin, which can markedly alter receptor trafficking and gating. Here, we used luminescence resonance energy transfer measurements to map distances between the full-length, functional AMPA receptor and stargazin expressed in HEK293 cells and to determine the ensemble structural changes in the receptor due to stargazin. In addition, we used single-molecule fluorescence resonance energy transfer to study the structural and conformational distribution of the receptor and how this distribution is affected by stargazin. Our nanopositioning data place stargazin below the AMPA receptor ligand-binding domain, where it is well poised to act as a scaffold to facilitate the long-range conformational selection observations seen in single-molecule experiments. These data support a model of stargazin acting to stabilize or select conformational states that favor activation.
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Affiliation(s)
- Sana A Shaikh
- Center for Membrane Biology, Department of Biochemistry and Molecular Biology, University of Texas Health Science Center at Houston, Houston, TX 77030, USA
| | - Drew M Dolino
- Center for Membrane Biology, Department of Biochemistry and Molecular Biology, University of Texas Health Science Center at Houston, Houston, TX 77030, USA; Biochemistry and Molecular Biology Graduate Program, Graduate School of Biomedical Sciences, University of Texas Health Science Center at Houston, Houston, TX 77030, USA
| | - Garam Lee
- Center for Membrane Biology, Department of Biochemistry and Molecular Biology, University of Texas Health Science Center at Houston, Houston, TX 77030, USA
| | | | - David M MacLean
- Center for Membrane Biology, Department of Biochemistry and Molecular Biology, University of Texas Health Science Center at Houston, Houston, TX 77030, USA
| | - Charlotte Flatebo
- Department of Chemistry, Rice University, Houston, TX 77251, USA; Applied Physics Graduate Program, Rice University, Houston, TX 77251, USA
| | - Christy F Landes
- Department of Chemistry, Rice University, Houston, TX 77251, USA; Department of Electrical and Computer Engineering, Rice University, Houston, TX 77251, USA; Applied Physics Graduate Program, Rice University, Houston, TX 77251, USA
| | - Vasanthi Jayaraman
- Center for Membrane Biology, Department of Biochemistry and Molecular Biology, University of Texas Health Science Center at Houston, Houston, TX 77030, USA; Biochemistry and Molecular Biology Graduate Program, Graduate School of Biomedical Sciences, University of Texas Health Science Center at Houston, Houston, TX 77030, USA.
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17
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The structure-energy landscape of NMDA receptor gating. Nat Chem Biol 2017; 13:1232-1238. [PMID: 28991238 PMCID: PMC5698143 DOI: 10.1038/nchembio.2487] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2017] [Accepted: 08/28/2017] [Indexed: 01/26/2023]
Abstract
N-Methyl-D-aspartate (NMDA) receptors are the main calcium-permeable excitatory receptors in the mammalian central nervous system. The NMDA receptor gating is complex, exhibiting multiple closed, open, and desensitized states; however, central questions regarding the conformations and energetics of the transmembrane domains as they relate to the gating states are still unanswered. Here, using single-molecule Förster resonance energy transfer (smFRET), we map the energy landscape of the first transmembrane segment of the Rattus norvegicus NMDA receptor under resting and various liganded conditions. These results show kinetically and structurally distinct changes associated with apo, agonist-bound, and inhibited receptors linked by a linear mechanism of gating at this site. Furthermore, the smFRET data suggest that allosteric inhibition by zinc occurs by an uncoupling of the agonist-induced changes at the extracellular domains from the gating motions leading to an apo-like state, while dizocilpine, a pore blocker, stabilizes multiple closely packed transmembrane states.
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18
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Zoghbi ME, Altenberg GA. Luminescence resonance energy transfer spectroscopy of ATP-binding cassette proteins. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2017; 1860:854-867. [PMID: 28801111 DOI: 10.1016/j.bbamem.2017.08.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 06/02/2017] [Revised: 07/31/2017] [Accepted: 08/01/2017] [Indexed: 12/11/2022]
Abstract
The ATP-binding cassette (ABC) superfamily includes regulatory and transport proteins. Most human ABC exporters pump substrates out of cells using energy from ATP hydrolysis. Although major advances have been made toward understanding the molecular mechanism of ABC exporters, there are still many issues unresolved. During the last few years, luminescence resonance energy transfer has been used to detect conformational changes in real time, with atomic resolution, in isolated ABC nucleotide binding domains (NBDs) and full-length ABC exporters. NBDs are particularly interesting because they provide the power stroke for substrate transport. Luminescence resonance energy transfer (LRET) is a spectroscopic technique that can provide dynamic information with atomic-resolution of protein conformational changes under physiological conditions. Using LRET, it has been shown that NBD dimerization, a critical step in ABC proteins catalytic cycle, requires binding of ATP to two nucleotide binding sites. However, hydrolysis at just one of the sites can drive dissociation of the NBD dimer. It was also found that the NBDs of the bacterial ABC exporter MsbA reconstituted in a lipid bilayer membrane and studied at 37°C never separate as much as suggested by crystal structures. This observation stresses the importance of performing structural/functional studies of ABC exporters under physiologic conditions. This article is part of a Special Issue entitled: Beyond the Structure-Function Horizon of Membrane Proteins edited by Ute Hellmich, Rupak Doshi and Benjamin McIlwain.
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Affiliation(s)
- Maria E Zoghbi
- School of Natural Sciences, University of California, Merced, 4225 N. Hospital Road, Atwater, CA, USA
| | - Guillermo A Altenberg
- Department of Cell Physiology and Molecular Biophysics, and Center for Membrane Protein Research, Texas Tech University Health Sciences Center, Lubbock, TX 79423-6551, USA.
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19
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Iacobucci GJ, Popescu GK. NMDA receptors: linking physiological output to biophysical operation. Nat Rev Neurosci 2017; 18:236-249. [PMID: 28303017 DOI: 10.1038/nrn.2017.24] [Citation(s) in RCA: 96] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
NMDA receptors are preeminent neurotransmitter-gated channels in the CNS, which respond to glutamate in a manner that integrates multiple external and internal cues. They belong to the ionotropic glutamate receptor family and fulfil unique and crucial roles in neuronal development and function. These roles depend on characteristic response kinetics, which reflect the operation of the receptors. Here, we review biologically salient features of the NMDA receptor signal and its mechanistic origins. Knowledge of distinctive NMDA receptor biophysical properties, their structural determinants and physiological roles is necessary to understand the physiological and neurotoxic actions of glutamate and to design effective therapeutics.
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Affiliation(s)
- Gary J Iacobucci
- Department of Biochemistry, University of Buffalo, State University of New York (SUNY), 144 Farber Hall, 3435 Main street, Buffalo, New York 14214, USA
| | - Gabriela K Popescu
- Department of Biochemistry, University of Buffalo, State University of New York (SUNY), 144 Farber Hall, 3435 Main street, Buffalo, New York 14214, USA
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20
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Lü W, Du J, Goehring A, Gouaux E. Cryo-EM structures of the triheteromeric NMDA receptor and its allosteric modulation. Science 2017; 355:science.aal3729. [PMID: 28232581 DOI: 10.1126/science.aal3729] [Citation(s) in RCA: 113] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2016] [Accepted: 02/02/2017] [Indexed: 11/02/2022]
Abstract
N-methyl-d-aspartate receptors (NMDARs) are heterotetrameric ion channels assembled as diheteromeric or triheteromeric complexes. Here, we report structures of the triheteromeric GluN1/GluN2A/GluN2B receptor in the absence or presence of the GluN2B-specific allosteric modulator Ro 25-6981 (Ro), determined by cryogenic electron microscopy (cryo-EM). In the absence of Ro, the GluN2A and GluN2B amino-terminal domains (ATDs) adopt "closed" and "open" clefts, respectively. Upon binding Ro, the GluN2B ATD clamshell transitions from an open to a closed conformation. Consistent with a predominance of the GluN2A subunit in ion channel gating, the GluN2A subunit interacts more extensively with GluN1 subunits throughout the receptor, in comparison with the GluN2B subunit. Differences in the conformation of the pseudo-2-fold-related GluN1 subunits further reflect receptor asymmetry. The triheteromeric NMDAR structures provide the first view of the most common NMDA receptor assembly and show how incorporation of two different GluN2 subunits modifies receptor symmetry and subunit interactions, allowing each subunit to uniquely influence receptor structure and function, thus increasing receptor complexity.
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Affiliation(s)
- Wei Lü
- Vollum Institute, Oregon Health and Science University, 3181 Southwest Sam Jackson Park Road, Portland, OR 97239, USA
| | - Juan Du
- Vollum Institute, Oregon Health and Science University, 3181 Southwest Sam Jackson Park Road, Portland, OR 97239, USA
| | - April Goehring
- Vollum Institute, Oregon Health and Science University, 3181 Southwest Sam Jackson Park Road, Portland, OR 97239, USA
| | - Eric Gouaux
- Vollum Institute, Oregon Health and Science University, 3181 Southwest Sam Jackson Park Road, Portland, OR 97239, USA. .,Howard Hughes Medical Institute, Oregon Health and Science University, 3181 Southwest Sam Jackson Park Road, Portland, OR 97239, USA
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21
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Romero-Hernandez A, Simorowski N, Karakas E, Furukawa H. Molecular Basis for Subtype Specificity and High-Affinity Zinc Inhibition in the GluN1-GluN2A NMDA Receptor Amino-Terminal Domain. Neuron 2016; 92:1324-1336. [PMID: 27916457 DOI: 10.1016/j.neuron.2016.11.006] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2016] [Revised: 10/05/2016] [Accepted: 11/02/2016] [Indexed: 10/20/2022]
Abstract
Zinc is vastly present in the mammalian brain and controls functions of various cell surface receptors to regulate neurotransmission. A distinctive characteristic of N-methyl-D-aspartate (NMDA) receptors containing a GluN2A subunit is that their ion channel activity is allosterically inhibited by a nano-molar concentration of zinc that binds to an extracellular domain called an amino-terminal domain (ATD). Despite physiological importance, the molecular mechanism underlying the high-affinity zinc inhibition has been incomplete because of the lack of a GluN2A ATD structure. Here we show the first crystal structures of the heterodimeric GluN1-GluN2A ATD, which provide the complete map of the high-affinity zinc-binding site and reveal distinctive features from the ATD of the GluN1-GluN2B subtype. Perturbation of hydrogen bond networks at the hinge of the GluN2A bi-lobe structure affects both zinc inhibition and open probability, supporting the general model in which the bi-lobe motion in ATD regulates the channel activity in NMDA receptors.
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Affiliation(s)
- Annabel Romero-Hernandez
- WM Keck Structural Biology Laboratory, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA; Watson School of Biological Sciences, Cold Spring Harbor, NY 11724, USA
| | - Noriko Simorowski
- WM Keck Structural Biology Laboratory, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA
| | - Erkan Karakas
- WM Keck Structural Biology Laboratory, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA
| | - Hiro Furukawa
- WM Keck Structural Biology Laboratory, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA; Watson School of Biological Sciences, Cold Spring Harbor, NY 11724, USA.
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22
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Tian M, Ye S. Allosteric regulation in NMDA receptors revealed by the genetically encoded photo-cross-linkers. Sci Rep 2016; 6:34751. [PMID: 27713495 PMCID: PMC5054432 DOI: 10.1038/srep34751] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Accepted: 09/16/2016] [Indexed: 11/09/2022] Open
Abstract
Allostery is essential to neuronal receptor function, but its transient nature poses a challenge for characterization. The N-terminal domains (NTDs) distinct from ligand binding domains are a major locus for allosteric regulation of NMDA receptors (NMDARs), where different modulatory binding sites have been observed. The inhibitor ifenprodil, and related phenylethanoamine compounds specifically targeting GluN1/GluN2B NMDARs have neuroprotective activity. However, whether they use differential structural pathways than the endogenous inhibitor Zn2+ for regulation is unknown. We applied genetically encoded unnatural amino acids (Uaas) and monitored the functional changes in living cells with photo-cross-linkers specifically incorporated at the ifenprodil binding interface between GluN1 and GluN2B subunits. We report constraining the NTD domain movement, by a light induced crosslinking bond that introduces minimal perturbation to the ligand binding, specifically impedes the transduction of ifenprodil but not Zn2+ inhibition. Subtle distance changes reveal interfacial flexibility and NTD rearrangements in the presence of modulators. Our results present a much richer dynamic picture of allostery than conventional approaches targeting the same interface, and highlight key residues that determine functional and subtype specificity of NMDARs. The light-sensitive mutant neuronal receptors provide complementary tools to the photo-switchable ligands for opto-neuropharmacology.
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Affiliation(s)
- Meilin Tian
- Shanghai Key Laboratory of Brain Functional Genomics, East China Normal University, Shanghai, China.,Ecole Normale Supérieure, Institut de Biologie de l'Ecole Normale Supérieure (IBENS), Paris, France.,Institut National de la Santé et de la Recherche Médicale, U1024, Paris, France.,Centre National de la Recherche Scientifique, UMR 8197, Paris, France
| | - Shixin Ye
- Ecole Normale Supérieure, Institut de Biologie de l'Ecole Normale Supérieure (IBENS), Paris, France.,Institut National de la Santé et de la Recherche Médicale, U1024, Paris, France.,Centre National de la Recherche Scientifique, UMR 8197, Paris, France
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23
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A structural biology perspective on NMDA receptor pharmacology and function. Curr Opin Struct Biol 2015; 33:68-75. [PMID: 26282925 DOI: 10.1016/j.sbi.2015.07.012] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2015] [Revised: 07/08/2015] [Accepted: 07/27/2015] [Indexed: 01/09/2023]
Abstract
N-methyld-aspartate receptors (NMDARs) belong to the large family of ionotropic glutamate receptors (iGluRs), which are critically involved in basic brain functions as well as multiple neurological diseases and disorders. The NMDARs are large heterotetrameric membrane protein complexes. The extensive extracellular domains recognize neurotransmitter ligands and allosteric compounds and translate the binding information to regulate activity of the transmembrane ion channel. Here, we review recent advances in the structural biology of NMDARs with a focus on pharmacology and function. Structural analysis of the isolated extracellular domains in combination with the intact heterotetrameric NMDAR structure provides important insights into how this sophisticated ligand-gated ion channel may function.
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24
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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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25
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MacLean DM, Ramaswamy SS, Du M, Howe JR, Jayaraman V. Stargazin promotes closure of the AMPA receptor ligand-binding domain. ACTA ACUST UNITED AC 2015; 144:503-12. [PMID: 25422502 PMCID: PMC4242809 DOI: 10.1085/jgp.201411287] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Stargazin enhances closure of the AMPA receptor ligand-binding domain, thereby facilitating channel activation. Transmembrane AMPA receptor (AMPAR) regulatory proteins (TARPs) markedly enhance AMPAR function, altering ligand efficacy and receptor gating kinetics and thereby shaping the postsynaptic response. The structural mechanism underlying TARP effects on gating, however, is unknown. Here we find that the prototypical member of the TARP family, stargazin or γ-2, rescues gating deficits in AMPARs carrying mutations that destabilize the closed-cleft states of the ligand-binding domain (LBD), suggesting that stargazin reverses the effects of these mutations and likely stabilizes closed LBD states. Furthermore, stargazin promotes a more closed conformation of the LBD, as indicated by reduced accessibility to the large antagonist NBQX. Consistent with the functional studies, luminescence resonance energy transfer experiments directly demonstrate that the AMPAR LBD is on average more closed in the presence of stargazin, in both the apo and agonist-bound states. The additional cleft closure and/or stabilization of the more closed-cleft states of the LBD is expected to translate to higher agonist efficacy and could contribute to the structural mechanism for stargazin modulation of AMPAR function.
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Affiliation(s)
- David M MacLean
- Department of Biochemistry and Molecular Biology, Center for Membrane Biology, University of Texas Health Science Center, Houston, TX 77030
| | - Swarna S Ramaswamy
- Department of Biochemistry and Molecular Biology, Center for Membrane Biology, University of Texas Health Science Center, Houston, TX 77030
| | - Mei Du
- Department of Biochemistry and Molecular Biology, Center for Membrane Biology, University of Texas Health Science Center, Houston, TX 77030
| | - James R Howe
- Department of Pharmacology, Yale University School of Medicine, New Haven, CT 06530
| | - 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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26
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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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Emerging structural insights into the function of ionotropic glutamate receptors. Trends Biochem Sci 2015; 40:328-37. [PMID: 25941168 DOI: 10.1016/j.tibs.2015.04.002] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2015] [Revised: 04/07/2015] [Accepted: 04/08/2015] [Indexed: 01/16/2023]
Abstract
Ionotropic glutamate receptors (iGluRs) are ligand-gated ion channels that mediate excitatory neurotransmission crucial for brain development and function, including learning and memory formation. Recently a wealth of structural studies on iGluRs including AMPA receptors (AMPARs), kainate receptors, and NMDA receptors (NMDARs) became available. These studies showed structures of non-NMDARs including AMPAR and kainate receptor in various functional states, thereby providing the first visual sense of how non-NMDAR iGluRs may function in the context of homotetramers. Furthermore, they provided the first view of heterotetrameric NMDAR ion channels, and this illuminated the similarities with and differences from non-NMDARs, thus raising a mechanistic distinction between the two groups of iGluRs. We review mechanistic insights into iGluR functions gained through structural studies of multiple groups.
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28
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Zhu S, Paoletti P. Allosteric modulators of NMDA receptors: multiple sites and mechanisms. Curr Opin Pharmacol 2015; 20:14-23. [DOI: 10.1016/j.coph.2014.10.009] [Citation(s) in RCA: 112] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2014] [Accepted: 10/23/2014] [Indexed: 12/24/2022]
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29
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Lee G, MacLean D, Ulrich H, Zhao X, Aronowski J, Jayaraman V. RNA based antagonist of NMDA receptors. ACS Chem Neurosci 2014; 5:559-67. [PMID: 24708087 PMCID: PMC4102967 DOI: 10.1021/cn500041k] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2014] [Revised: 04/07/2014] [Indexed: 11/30/2022] Open
Abstract
The N-methyl d-aspartate (NMDA) class of ionotropic glutamate receptors plays important roles in learning and memory as well as in a number of neurological disorders including Huntington's disease and cerebral ischemia. Here, we describe the isolation and characterization of a 2' F-modified RNA aptamers directed against GluN2A-containing NMDA receptors. By adding a negative selection step toward the closely related AMPA and kainate receptors, the RNA aptamers specifically recognize NMDA receptors with dissociation constants in the nanomolar range. Electrophysiological characterization of these aptamers using rapid perfusion in outside-out patches reveals that they selectively inhibit the GluN2A containing subtype of NMDA receptors with little effect on the AMPA and kainate receptor subtypes. We also demonstrate that this RNA aptamer significantly reduces neurotoxicity in an in vitro model of cerebral ischemia. Given that the RNA based antagonist can be readily modified, it can be used as a tool in targeted drug delivery or for imaging purposes in addition to having the potential use as a therapeutic intervention in disorders involving glutamate receptors.
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MESH Headings
- Animals
- Aptamers, Nucleotide/chemistry
- Aptamers, Nucleotide/genetics
- Aptamers, Nucleotide/pharmacology
- Base Sequence
- Cell Hypoxia/drug effects
- Cell Survival/drug effects
- Cells, Cultured
- Cerebral Cortex/drug effects
- Cerebral Cortex/physiology
- Consensus Sequence
- Glucose/deficiency
- Molecular Sequence Data
- Neurons/drug effects
- Neurons/physiology
- Neuroprotective Agents/chemistry
- Neuroprotective Agents/pharmacology
- Nucleic Acid Conformation
- Patch-Clamp Techniques
- Radioligand Assay
- Rats
- Receptors, AMPA/antagonists & inhibitors
- Receptors, AMPA/metabolism
- Receptors, Kainic Acid/antagonists & inhibitors
- Receptors, Kainic Acid/metabolism
- Receptors, N-Methyl-D-Aspartate/antagonists & inhibitors
- Receptors, N-Methyl-D-Aspartate/metabolism
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Affiliation(s)
- Garam Lee
- Center for Membrane Biology, Department of Biochemistry
and Molecular Biology, and Department of Neurology, University of Texas Health Science Center, 6431 Fannin, Houston, Texas 77030, United States
| | - David
M. MacLean
- Center for Membrane Biology, Department of Biochemistry
and Molecular Biology, and Department of Neurology, University of Texas Health Science Center, 6431 Fannin, Houston, Texas 77030, United States
| | - Henning Ulrich
- Department
of Biochemistry, Instituto de Química, Universidade de São Paulo, São Paulo, Av. Prof. Lineu Prestes 748, São Paulo, S.P. 05508-900, Brazil
| | - Xiurong Zhao
- Center for Membrane Biology, Department of Biochemistry
and Molecular Biology, and Department of Neurology, University of Texas Health Science Center, 6431 Fannin, Houston, Texas 77030, United States
| | - Jaroslaw Aronowski
- Center for Membrane Biology, Department of Biochemistry
and Molecular Biology, and Department of Neurology, University of Texas Health Science Center, 6431 Fannin, Houston, Texas 77030, United States
| | - Vasanthi Jayaraman
- Center for Membrane Biology, Department of Biochemistry
and Molecular Biology, and Department of Neurology, University of Texas Health Science Center, 6431 Fannin, Houston, Texas 77030, United States
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30
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Hancock SM, Finkelstein DI, Adlard PA. Glia and zinc in ageing and Alzheimer's disease: a mechanism for cognitive decline? Front Aging Neurosci 2014; 6:137. [PMID: 25009495 PMCID: PMC4069481 DOI: 10.3389/fnagi.2014.00137] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2014] [Accepted: 06/09/2014] [Indexed: 11/13/2022] Open
Abstract
Normal ageing is characterized by cognitive decline across a range of neurological functions, which are further impaired in Alzheimer’s disease (AD). Recently, alterations in zinc (Zn) concentrations, particularly at the synapse, have emerged as a potential mechanism underlying the cognitive changes that occur in both ageing and AD. Zn is now accepted as a potent neuromodulator, affecting a variety of signaling pathways at the synapse that are critical to normal cognition. While the focus has principally been on the neuron: Zn interaction, there is a growing literature suggesting that glia may also play a modulatory role in maintaining both Zn ion homeostasis and the normal function of the synapse. Indeed, zinc transporters (ZnT’s) have been demonstrated in glial cells where Zn has also been shown to have a role in signaling. Furthermore, there is increasing evidence that the pathogenesis of AD critically involves glial cells (such as astrocytes), which have been reported to contribute to amyloid-beta (Aβ) neurotoxicity. This review discusses the current evidence supporting a complex interplay of glia, Zn dyshomeostasis and synaptic function in ageing and AD.
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Affiliation(s)
- Sara M Hancock
- Synaptic Neurobiology Laboratory, Florey Institute of Neuroscience and Mental Health Parkville, VIC, Australia
| | - David I Finkelstein
- Parkinson's Disease Laboratory, Florey Institute of Neuroscience and Mental Health Parkville, VIC, Australia
| | - Paul A Adlard
- Synaptic Neurobiology Laboratory, Florey Institute of Neuroscience and Mental Health Parkville, VIC, Australia
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31
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Möykkynen T, Coleman SK, Semenov A, Keinänen K. The N-terminal domain modulates α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor desensitization. J Biol Chem 2014; 289:13197-205. [PMID: 24652293 DOI: 10.1074/jbc.m113.526301] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
AMPA receptors are tetrameric glutamate-gated ion channels that mediate fast synaptic neurotransmission in mammalian brain. Their subunits contain a two-lobed N-terminal domain (NTD) that comprises over 40% of the mature polypeptide. The NTD is not obligatory for the assembly of tetrameric receptors, and its functional role is still unclear. By analyzing full-length and NTD-deleted GluA1-4 AMPA receptors expressed in HEK 293 cells, we found that the removal of the NTD leads to a significant reduction in receptor transport to the plasma membrane, a higher steady state-to-peak current ratio of glutamate responses, and strongly increased sensitivity to glutamate toxicity in cell culture. Further analyses showed that NTD-deleted receptors display both a slower onset of desensitization and a faster recovery from desensitization of agonist responses. Our results indicate that the NTD promotes the biosynthetic maturation of AMPA receptors and, for membrane-expressed channels, enhances the stability of the desensitized state. Moreover, these findings suggest that interactions of the NTD with extracellular/synaptic ligands may be able to fine-tune AMPA receptor-mediated responses, in analogy with the allosteric regulatory role demonstrated for the NTD of NMDA receptors.
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Affiliation(s)
- Tommi Möykkynen
- From the Division of Biochemistry and Biotechnology, Department of Biosciences, University of Helsinki, 00014 Helsinki, Finland
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