51
|
Affiliation(s)
- Derek Bowie
- Department of Pharmacology and TherapeuticsMcGill UniversityMontréalQuébec H3G 1Y6Canada
| |
Collapse
|
52
|
Imaging the glutamate receptor subtypes-Much achieved, and still much to do. DRUG DISCOVERY TODAY. TECHNOLOGIES 2017; 25:27-36. [PMID: 29233264 DOI: 10.1016/j.ddtec.2017.10.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Revised: 10/17/2017] [Accepted: 10/24/2017] [Indexed: 11/20/2022]
Abstract
Functional imaging of glutamate receptors using PET imaging modality can be used to study numerous CNS disorders and also to select appropriate doses of clinically relevant glutamate-receptor-targeting candidate drugs. Great strides have been made in developing PET imaging probes for the non-invasive detection of glutamate receptors in the brain. This review highlights recent progress made towards the development of glutamatergic PET imaging agents. Focus is placed on PET imaging probes that have been labelled with either carbon-11 or fluorine-18.
Collapse
|
53
|
Tamborini L, Mastronardi F, Lo Presti L, Nielsen B, De Micheli C, Conti P, Pinto A. Synthesis of l-Tricholomic Acid Analogues and Pharmacological Characterization at Ionotropic Glutamate Receptors. ChemistrySelect 2017. [DOI: 10.1002/slct.201702154] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Lucia Tamborini
- Department of Pharmaceutical Sciences; University of Milan; Via Mangiagalli 25 20133 Milan, Italy
| | - Federica Mastronardi
- Department of Pharmaceutical Sciences; University of Milan; Via Mangiagalli 25 20133 Milan, Italy
| | - Leonardo Lo Presti
- Department of Chemistry; University of Milan; Via Golgi 19 20133 Milan Italy
| | - Birgitte Nielsen
- Department of Drug Design and Pharmacology; Faculty of Health and Medical Sciences; University of Copenhagen; Universitetsparken 2 2100 Copenhagen OE Denmark
| | - Carlo De Micheli
- Department of Pharmaceutical Sciences; University of Milan; Via Mangiagalli 25 20133 Milan, Italy
| | - Paola Conti
- Department of Pharmaceutical Sciences; University of Milan; Via Mangiagalli 25 20133 Milan, Italy
| | - Andrea Pinto
- Department of Food, Environmental and Nutritional Sciences; University of Milan; Via Mangiagalli 25 20133 Milan Italy
| |
Collapse
|
54
|
Szymańska E, Nielsen B, Johansen TN, Cuñado Moral AM, Pickering DS, Szczepańska K, Mickowska A, Kieć-Kononowicz K. Pharmacological characterization and binding modes of novel racemic and optically active phenylalanine-based antagonists of AMPA receptors. Eur J Med Chem 2017; 138:874-883. [PMID: 28738307 DOI: 10.1016/j.ejmech.2017.07.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2017] [Revised: 06/29/2017] [Accepted: 07/05/2017] [Indexed: 01/01/2023]
Abstract
In order to map out molecular determinants for the competitive blockade of AMPA receptor subtypes, a series of racemic aryl-substituted phenylalanines was synthesized and pharmacologically characterized in vitro at native rat ionotropic glutamate receptors. Most of the compounds showed micromolar affinity and preference for AMPA receptors. Individual stereoisomers of selected compounds were further evaluated at recombinant homomeric rat GluA2 and GluA3 receptors. The most potent compound, (-)-2-amino-3-(6-chloro-2',5'-dihydroxy-5-nitro-[1,1'-biphenyl]-3-yl)propanoic acid, the expected R-isomer showing Ki of 1.71 μM at the GluA2 subtype, was found to competitively antagonize GluA2(Q)i receptors in TEVC electrophysiological experiments (Kb = 2.13 μM). Molecular docking experiments allowed us to compare two alternative antagonist binding modes for the synthesized phenylalanines at the GluA2 binding core, showing the direction for further structural modifications.
Collapse
Affiliation(s)
- Ewa Szymańska
- Department of Technology and Biotechnology of Drugs, Jagiellonian University Medical College, Medyczna 9, PL 30-688 Kraków, Poland.
| | - Birgitte Nielsen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen Ø, Denmark
| | - Tommy N Johansen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen Ø, Denmark
| | - Ana Maria Cuñado Moral
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen Ø, Denmark
| | - Darryl S Pickering
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen Ø, Denmark
| | - Katarzyna Szczepańska
- Department of Technology and Biotechnology of Drugs, Jagiellonian University Medical College, Medyczna 9, PL 30-688 Kraków, Poland
| | - Anna Mickowska
- Department of Technology and Biotechnology of Drugs, Jagiellonian University Medical College, Medyczna 9, PL 30-688 Kraków, Poland
| | - Katarzyna Kieć-Kononowicz
- Department of Technology and Biotechnology of Drugs, Jagiellonian University Medical College, Medyczna 9, PL 30-688 Kraków, Poland
| |
Collapse
|
55
|
Zhang X, Kumata K, Yamasaki T, Cheng R, Hatori A, Ma L, Zhang Y, Xie L, Wang L, Kang HJ, Sheffler DJ, Cosford NDP, Zhang MR, Liang SH. Synthesis and Preliminary Studies of a Novel Negative Allosteric Modulator, 7-((2,5-Dioxopyrrolidin-1-yl)methyl)-4-(2-fluoro-4-[ 11C]methoxyphenyl) quinoline-2-carboxamide, for Imaging of Metabotropic Glutamate Receptor 2. ACS Chem Neurosci 2017; 8:1937-1948. [PMID: 28565908 PMCID: PMC5607115 DOI: 10.1021/acschemneuro.7b00098] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Metabotropic glutamate 2 receptors (mGlu2) are involved in the pathogenesis of several CNS disorders and neurodegenerative diseases. Pharmacological modulation of this target represents a potential disease-modifying approach for the treatment of substance abuse, depression, schizophrenia, and dementias. While quantification of mGlu2 receptors in the living brain by positron emission tomography (PET) would help us better understand signaling pathways relevant to these conditions, few successful examples have been demonstrated to image mGlu2 in vivo, and a suitable PET tracer is yet to be identified. Herein we report the design and synthesis of a radiolabeled negative allosteric modulator (NAM) for mGlu2 PET tracer development based on a quinoline 2-carboxamide scaffold. The most promising candidate, 7-((2,5-dioxopyrrolidin-1-yl)methyl)-4-(2-fluoro-4-[11C]methoxyphenyl) quinoline-2-carboxamide ([11C]QCA) was prepared in 13% radiochemical yield (non-decay-corrected at the end of synthesis) with >99% radiochemical purity and >74 GBq/μmol (2 Ci/μmol) specific activity. While the tracer showed limited brain uptake (0.3 SUV), probably attributable to effects on PgP/Bcrp efflux pump, in vitro autoradiography studies demonstrated heterogeneous brain distribution and specific binding. Thus, [11C]QCA is a chemical probe that provides the basis for the development of a new generation mGlu2 PET tracers.
Collapse
MESH Headings
- ATP Binding Cassette Transporter, Subfamily G, Member 2/deficiency
- ATP Binding Cassette Transporter, Subfamily G, Member 2/genetics
- Adhesins, Escherichia coli
- Allosteric Regulation
- Animals
- Autoradiography
- Brain/diagnostic imaging
- Brain/metabolism
- Drug Design
- Humans
- Magnetic Resonance Imaging
- Male
- Mice, Knockout
- Mice, Mutant Strains
- Microsomes, Liver/drug effects
- Microsomes, Liver/metabolism
- Molecular Structure
- Positron-Emission Tomography
- Preliminary Data
- Pyrrolidines/chemistry
- Quinolines/chemistry
- Radiopharmaceuticals/chemical synthesis
- Rats, Sprague-Dawley
- Receptors, Metabotropic Glutamate/metabolism
- Tissue Distribution
Collapse
Affiliation(s)
- Xiaofei Zhang
- Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA, 02114, USA
- State Key Laboratory and Institute of Elemento-Organic Chemistry, Collaborative Innovation Center of Chemical Science and Engineering, Nankai Unviersity, Tianjin 300071, China
| | - Katsushi Kumata
- Department of Radiopharmaceutics Development, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba, 263-8555, Japan
| | - Tomoteru Yamasaki
- Department of Radiopharmaceutics Development, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba, 263-8555, Japan
| | - Ran Cheng
- Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA, 02114, USA
| | - Akiko Hatori
- Department of Radiopharmaceutics Development, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba, 263-8555, Japan
| | - Longle Ma
- Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA, 02114, USA
| | - Yiding Zhang
- Department of Radiopharmaceutics Development, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba, 263-8555, Japan
| | - Lin Xie
- Department of Radiopharmaceutics Development, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba, 263-8555, Japan
| | - Lu Wang
- Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA, 02114, USA
| | - Hye Jin Kang
- Department of Pharmacology & National Institute of Mental Health Psychoactive Drug Screening Program, University of North Carolina at Chapel Hill, North Carolina, 27515, USA
| | - Douglas J. Sheffler
- Cell Death and Survival Networks Program and Conrad Prebys Center for Chemical Genomics, Sanford-Burnham Medical Research Institute, La Jolla, CA, 92037, USA
| | - Nicholas D. P. Cosford
- Cell Death and Survival Networks Program and Conrad Prebys Center for Chemical Genomics, Sanford-Burnham Medical Research Institute, La Jolla, CA, 92037, USA
| | - Ming-Rong Zhang
- Department of Radiopharmaceutics Development, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba, 263-8555, Japan
| | - Steven H. Liang
- Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA, 02114, USA
| |
Collapse
|
56
|
Møllerud S, Pinto A, Marconi L, Frydenvang K, Thorsen TS, Laulumaa S, Venskutonytė R, Winther S, Moral AMC, Tamborini L, Conti P, Pickering DS, Kastrup JS. Structure and Affinity of Two Bicyclic Glutamate Analogues at AMPA and Kainate Receptors. ACS Chem Neurosci 2017; 8:2056-2064. [PMID: 28691798 DOI: 10.1021/acschemneuro.7b00201] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Ionotropic glutamate receptors (iGluRs) are involved in most of the fast excitatory synaptic transmission in the central nervous system. These receptors are important for learning and memory formation, but are also involved in the development of diseases such as Alzheimer's disease, epilepsy and depression. To understand the function of different types of iGluRs, selective agonists are invaluable as pharmacological tool compounds. Here, we report binding affinities of two bicyclic, conformationally restricted analogues of glutamate (CIP-AS and LM-12b) at AMPA (GluA2 and GluA3) and kainate receptor subunits (GluK1-3 and GluK5). Both CIP-AS and LM-12b were found to be GluK3-preferring agonists, with Ki of 6 and 22 nM, respectively, at recombinant GluK3 receptors. The detailed binding mode of CIP-AS and LM-12b in the ligand-binding domains of the AMPA receptor subunit GluA2 (GluA2-LBD) and the kainate receptor subunits GluK1 (GluK1-LBD) and GluK3 (GluK3-LBD) was investigated by X-ray crystallography. CIP-AS stabilized all three receptor constructs in conformations similar to those with kainate. Remarkably, whereas LM-12b bound in a similar manner to CIP-AS in GluA2-LBD and GluK3-LBD, it introduced full closure of the ligand-binding domain in GluK1-LBD and formation of a D1-D2 interlobe hydrogen bond between Glu441 and Ser721, as also observed with glutamate. As the binding affinity of LM-12b at GluK1 is ∼8-fold better than that for CIP-AS (Ki of 85 and 656 nM, respectively), it shows that small changes in agonist structure can lead to prominent differences in structure and function.
Collapse
Affiliation(s)
- Stine Møllerud
- Department of Drug
Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Andrea Pinto
- Department of Food, Environmental and Nutritional Sciences, Università degli Studi di Milano, 20133 Milano, Italy
| | - Laura Marconi
- Department of Drug
Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen, Denmark
- Department of Pharmaceutical Sciences, Università degli Studi di Milano, 20133 Milano, Italy
| | - Karla Frydenvang
- Department of Drug
Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Thor Seneca Thorsen
- Department of Drug
Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Saara Laulumaa
- Department of Drug
Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Raminta Venskutonytė
- Department of Drug
Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Sebastian Winther
- Department of Drug
Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Ana Maria Cuñado Moral
- Department of Drug
Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Lucia Tamborini
- Department of Pharmaceutical Sciences, Università degli Studi di Milano, 20133 Milano, Italy
| | - Paola Conti
- Department of Pharmaceutical Sciences, Università degli Studi di Milano, 20133 Milano, Italy
| | - Darryl S. Pickering
- Department of Drug
Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Jette Sandholm Kastrup
- Department of Drug
Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen, Denmark
| |
Collapse
|
57
|
Channel opening and gating mechanism in AMPA-subtype glutamate receptors. Nature 2017; 549:60-65. [PMID: 28737760 PMCID: PMC5743206 DOI: 10.1038/nature23479] [Citation(s) in RCA: 162] [Impact Index Per Article: 23.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2017] [Accepted: 07/14/2017] [Indexed: 01/03/2023]
Abstract
AMPA-subtype ionotropic glutamate receptors mediate fast excitatory neurotransmission throughout the central nervous system. Gated by the neurotransmitter glutamate, AMPA receptors are critical for synaptic strength and dysregulation of AMPA receptor-mediated signaling is linked to numerous neurological diseases. Here, we use cryo-electron microscopy to solve the structures of AMPA receptor-auxiliary subunit complexes in the apo, antagonist and agonist-bound states and elucidate the iris-like mechanism of ion channel opening. The ion channel selectivity filter is formed by the extended portions of the re-entrant M2 loops, while the helical portions of M2 contribute to extensive hydrophobic interfaces between AMPA receptor subunits in the ion channel. We show how the permeation pathway changes upon channel opening and identify conformational changes throughout the entire AMPA receptor that accompany activation and desensitization. Our findings provide a framework for understanding gating across the family of ionotropic glutamate receptors and the role of AMPA receptors in excitatory neurotransmission.
Collapse
|
58
|
Abstract
In the last decade, a large number of neuronal cell-surface antibodies have been described which are responsible for a range of neuroimmunological central nervous system disorders. Unlike the paraneoplastic antibodies which target intracellular antigens, these antibodies appear to be pathogenic and hence identification and prompt treatment can make a substantial impact on clinical outcomes of these patients. We review the common antibodies against the ionotropic glutamate receptors (NMDAR, AMPAR), metabotropic glutamate receptors (mGluR1 and mGluR5), voltage-gated potassium channel-complex proteins (LGI1, CASPR2), and other antibodies targeted against glycine receptor, glutamic acid decarboxylase, gamma-amino butyric acid B, dopamine-2-receptor and dipeptidyl-peptidase-like protein 6.
Collapse
Affiliation(s)
- A R Karim
- 1 Neuroimmunology, Clinical Immunology Service, University of Birmingham, Birmingham, UK
| | - S Jacob
- 2 Queen Elizabeth Neurosciences Centre, 1732 University Hospital Birmingham NHS Foundation Trust , Birmingham, UK
| |
Collapse
|
59
|
Tobi D. Dynamical differences of hemoglobin and the ionotropic glutamate receptor in different states revealed by a new dynamics alignment method. Proteins 2017; 85:1507-1517. [PMID: 28459140 DOI: 10.1002/prot.25311] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2017] [Revised: 04/02/2017] [Accepted: 04/24/2017] [Indexed: 12/26/2022]
Abstract
A new algorithm for comparison of protein dynamics is presented. Compared protein structures are superposed and their modes of motions are calculated using the anisotropic network model. The obtained modes are aligned using the dynamic programming algorithm of Needleman and Wunsch, commonly used for sequence alignment. Dynamical comparison of hemoglobin in the T and R2 states reveals that the dynamics of the allosteric effector 2,3-bisphosphoglycerate binding site is different in the two states. These differences can contribute to the selectivity of the effector to the T state. Similar comparison of the ionotropic glutamate receptor in the kainate+(R,R)-2b and ZK bound states reveals that the kainate+(R,R)-2b bound states slow modes describe upward motions of ligand binding domain and the transmembrane domain regions. Such motions may lead to the opening of the receptor. The upper lobes of the LBDs of the ZK bound state have a smaller interface with the amino terminal domains above them and have a better ability to move together. The present study exemplifies the use of dynamics comparison as a tool to study protein function. Proteins 2017; 85:1507-1517. © 2014 Wiley Periodicals, Inc.
Collapse
Affiliation(s)
- Dror Tobi
- Department of Computer Sciences, Ariel University, Ariel, 40700, Israel.,Department of Molecular Biology, Ariel University, Ariel, 40700, Israel
| |
Collapse
|
60
|
Twomey EC, Yelshanskaya MV, Grassucci RA, Frank J, Sobolevsky AI. Structural Bases of Desensitization in AMPA Receptor-Auxiliary Subunit Complexes. Neuron 2017; 94:569-580.e5. [PMID: 28472657 PMCID: PMC5492975 DOI: 10.1016/j.neuron.2017.04.025] [Citation(s) in RCA: 83] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Revised: 04/10/2017] [Accepted: 04/17/2017] [Indexed: 02/09/2023]
Abstract
Fast excitatory neurotransmission is mediated by AMPA-subtype ionotropic glutamate receptors (AMPARs). AMPARs, localized at post-synaptic densities, are regulated by transmembrane auxiliary subunits that modulate AMPAR assembly, trafficking, gating, and pharmacology. Aberrancies in AMPAR-mediated signaling are associated with numerous neurological disorders. Here, we report cryo-EM structures of an AMPAR in complex with the auxiliary subunit GSG1L in the closed and desensitized states. GSG1L favors the AMPAR desensitized state, where channel closure is facilitated by profound structural rearrangements in the AMPAR extracellular domain, with ligand-binding domain dimers losing their local 2-fold rotational symmetry. Our structural and functional experiments suggest that AMPAR auxiliary subunits share a modular architecture and use a common transmembrane scaffold for distinct extracellular modules to differentially regulate AMPAR gating. By comparing the AMPAR-GSG1L complex structures, we map conformational changes accompanying AMPAR recovery from desensitization and reveal structural bases for regulation of synaptic transmission by auxiliary subunits.
Collapse
Affiliation(s)
- Edward C Twomey
- Department of Biochemistry and Molecular Biophysics, Columbia University, 650 West 168(th) Street, New York, NY 10032, USA; Integrated Program in Cellular, Molecular, and Biomedical Studies, Columbia University, 650 West 168(th) Street, New York, NY 10032, USA
| | - Maria V Yelshanskaya
- Department of Biochemistry and Molecular Biophysics, Columbia University, 650 West 168(th) Street, New York, NY 10032, USA
| | - Robert A Grassucci
- Department of Biochemistry and Molecular Biophysics, Columbia University, 650 West 168(th) Street, New York, NY 10032, USA; Howard Hughes Medical Institute, 650 West 168(th) Street, New York, NY 10032, USA
| | - Joachim Frank
- Department of Biochemistry and Molecular Biophysics, Columbia University, 650 West 168(th) Street, New York, NY 10032, USA; Department of Biological Sciences, Columbia University, 650 West 168(th) Street, New York, NY 10032, USA; Howard Hughes Medical Institute, 650 West 168(th) Street, New York, NY 10032, USA.
| | - Alexander I Sobolevsky
- Department of Biochemistry and Molecular Biophysics, Columbia University, 650 West 168(th) Street, New York, NY 10032, USA.
| |
Collapse
|
61
|
Greger IH, Watson JF, Cull-Candy SG. Structural and Functional Architecture of AMPA-Type Glutamate Receptors and Their Auxiliary Proteins. Neuron 2017; 94:713-730. [DOI: 10.1016/j.neuron.2017.04.009] [Citation(s) in RCA: 169] [Impact Index Per Article: 24.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2017] [Revised: 04/04/2017] [Accepted: 04/05/2017] [Indexed: 12/20/2022]
|
62
|
Yelshanskaya MV, Mesbahi-Vasey S, Kurnikova MG, Sobolevsky AI. Role of the Ion Channel Extracellular Collar in AMPA Receptor Gating. Sci Rep 2017; 7:1050. [PMID: 28432359 PMCID: PMC5430913 DOI: 10.1038/s41598-017-01146-z] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2017] [Accepted: 03/21/2017] [Indexed: 11/09/2022] Open
Abstract
AMPA subtype ionotropic glutamate receptors mediate fast excitatory neurotransmission and are implicated in numerous neurological diseases. Ionic currents through AMPA receptor channels can be allosterically regulated via different sites on the receptor protein. We used site-directed mutagenesis and patch-clamp recordings to probe the ion channel extracellular collar, the binding region for noncompetitive allosteric inhibitors. We found position and substitution-dependent effects for introduced mutations at this region on AMPA receptor gating. The results of mutagenesis suggested that the transmembrane domains M1, M3 and M4, which contribute to the ion channel extracellular collar, undergo significant relative displacement during gating. We used molecular dynamics simulations to predict an AMPA receptor open state structure and rationalize the results of mutagenesis. We conclude that the ion channel extracellular collar plays a distinct role in gating and represents a hub for powerful allosteric modulation of AMPA receptor function that can be used for developing novel therapeutics.
Collapse
Affiliation(s)
- Maria V Yelshanskaya
- Department of Biochemistry and Molecular Biophysics, Columbia University, 650 West 168th Street, New York, NY, 10032, USA
| | - Samaneh Mesbahi-Vasey
- Chemistry Department, Carnegie Mellon University, 4400 Fifth Ave, Pittsburgh, PA, 15213, USA
| | - Maria G Kurnikova
- Chemistry Department, Carnegie Mellon University, 4400 Fifth Ave, Pittsburgh, PA, 15213, USA.
| | - Alexander I Sobolevsky
- Department of Biochemistry and Molecular Biophysics, Columbia University, 650 West 168th Street, New York, NY, 10032, USA.
| |
Collapse
|
63
|
Berlin S, Isacoff EY. Synapses in the spotlight with synthetic optogenetics. EMBO Rep 2017; 18:677-692. [PMID: 28396573 DOI: 10.15252/embr.201744010] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2017] [Revised: 03/02/2017] [Accepted: 03/09/2017] [Indexed: 12/15/2022] Open
Abstract
Membrane receptors and ion channels respond to various stimuli and relay that information across the plasma membrane by triggering specific and timed processes. These include activation of second messengers, allowing ion permeation, and changing cellular excitability, to name a few. Gaining control over equivalent processes is essential to understand neuronal physiology and pathophysiology. Recently, new optical techniques have emerged proffering new remote means to control various functions of defined neuronal populations by light, dubbed optogenetics. Still, optogenetic tools do not typically address the activity of receptors and channels native to neurons (or of neuronal origin), nor gain access to their signaling mechanisms. A related method-synthetic optogenetics-bridges this gap by endowing light sensitivity to endogenous neuronal receptors and channels by the appending of synthetic, light-receptive molecules, or photoswitches. This provides the means to photoregulate neuronal receptors and channels and tap into their native signaling mechanisms in select regions of the neurons, such as the synapse. This review discusses the development of synthetic optogenetics as a means to study neuronal receptors and channels remotely, in their natural environment, with unprecedented spatial and temporal precision, and provides an overview of tool design, mode of action, potential clinical applications and insights and achievements gained.
Collapse
Affiliation(s)
- Shai Berlin
- The Ruth and Bruce Rappaport Faculty of Medicine, Technion- Israel Institute of Technology, Haifa, Israel
| | - Ehud Y Isacoff
- Helen Wills Neuroscience Institute, University of California, Berkeley, CA, USA.,Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA.,Physical Bioscience Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| |
Collapse
|
64
|
Salazar H, Eibl C, Chebli M, Plested A. Mechanism of partial agonism in AMPA-type glutamate receptors. Nat Commun 2017; 8:14327. [PMID: 28211453 PMCID: PMC5321683 DOI: 10.1038/ncomms14327] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2016] [Accepted: 12/19/2016] [Indexed: 02/04/2023] Open
Abstract
Neurotransmitters trigger synaptic currents by activating ligand-gated ion channel receptors. Whereas most neurotransmitters are efficacious agonists, molecules that activate receptors more weakly-partial agonists-also exist. Whether these partial agonists have weak activity because they stabilize less active forms, sustain active states for a lesser fraction of the time or both, remains an open question. Here we describe the crystal structure of an α-amino-3-hydroxy-5-methyl-4-isoxazolepropionate receptor (AMPAR) ligand binding domain (LBD) tetramer in complex with the partial agonist 5-fluorowillardiine (FW). We validate this structure, and others of different geometry, using engineered intersubunit bridges. We establish an inverse relation between the efficacy of an agonist and its promiscuity to drive the LBD layer into different conformations. These results suggest that partial agonists of the AMPAR are weak activators of the receptor because they stabilize multiple non-conducting conformations, indicating that agonism is a function of both the space and time domains.
Collapse
Affiliation(s)
- Hector Salazar
- Leibniz-Institut für Molekulare Pharmakologie, Robert-Rössle-Strasse 10, 13125 Berlin, Germany
- Cluster of Excellence NeuroCure, Charité-Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany
| | - Clarissa Eibl
- Leibniz-Institut für Molekulare Pharmakologie, Robert-Rössle-Strasse 10, 13125 Berlin, Germany
- Cluster of Excellence NeuroCure, Charité-Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany
| | - Miriam Chebli
- Leibniz-Institut für Molekulare Pharmakologie, Robert-Rössle-Strasse 10, 13125 Berlin, Germany
- Cluster of Excellence NeuroCure, Charité-Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany
| | - Andrew Plested
- Leibniz-Institut für Molekulare Pharmakologie, Robert-Rössle-Strasse 10, 13125 Berlin, Germany
- Cluster of Excellence NeuroCure, Charité-Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany
| |
Collapse
|
65
|
Haglerød C, Hussain S, Nakamura Y, Xia J, Haug FMS, Ottersen OP, Henley JM, Davanger S. Presynaptic PICK1 facilitates trafficking of AMPA-receptors between active zone and synaptic vesicle pool. Neuroscience 2017; 344:102-112. [PMID: 28057533 DOI: 10.1016/j.neuroscience.2016.12.042] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2016] [Revised: 12/09/2016] [Accepted: 12/22/2016] [Indexed: 11/30/2022]
Abstract
Previous studies have indicated that presynaptic α-amino-3-hydroxy-5-methyl-4-isoxazole propionate receptors (AMPARs) contribute to the regulation of neurotransmitter release. In hippocampal synapses, the presynaptic surface expression of several AMPAR subunits, including GluA2, is regulated in a ligand-dependent manner. However, the molecular mechanisms underlying the presynaptic trafficking of AMPARs are still unknown. Here, using bright-field immunocytochemistry, western blots, and quantitative immunogold electron microscopy of the hippocampal CA1 area from intact adult rat brain, we demonstrate the association of AMPA receptors with the presynaptic active zone and with small presynaptic vesicles, in Schaffer collateral synapses in CA1 of the hippocampus. Furthermore, we show that GluA2 and protein interacting with C kinase 1 (PICK1) are colocalized at presynaptic vesicles. Similar to postsynaptic mechanisms, overexpression of either PICK1 or pep2m, which inhibit the N-ethylmaleimide sensitive fusion protein (NSF)-GluA2 interaction, decreases the concentration of GluA2 in the presynaptic active zone membrane. These data suggest that the interacting proteins PICK1 and NSF act as regulators of presynaptic GluA2-containing AMPAR trafficking between the active zone and a vesicle pool that may provide the basis of presynaptic components of synaptic plasticity.
Collapse
Affiliation(s)
- C Haglerød
- Institute of Basic Medical Sciences, Division of Anatomy, University of Oslo, Oslo, Norway
| | - S Hussain
- Institute of Basic Medical Sciences, Division of Anatomy, University of Oslo, Oslo, Norway
| | - Y Nakamura
- School of Biochemistry, Centre for Synaptic Plasticity, Biomedical Sciences Building, University of Bristol, Bristol BS8 1TD, UK
| | - J Xia
- Division of Life Science, Division of Biomedical Engineering and State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - F-M S Haug
- Institute of Basic Medical Sciences, Division of Anatomy, University of Oslo, Oslo, Norway
| | - O P Ottersen
- Institute of Basic Medical Sciences, Division of Anatomy, University of Oslo, Oslo, Norway
| | - J M Henley
- School of Biochemistry, Centre for Synaptic Plasticity, Biomedical Sciences Building, University of Bristol, Bristol BS8 1TD, UK
| | - S Davanger
- Institute of Basic Medical Sciences, Division of Anatomy, University of Oslo, Oslo, Norway.
| |
Collapse
|
66
|
Tamborini L, Cullia G, Nielsen B, De Micheli C, Conti P, Pinto A. Synthesis and pharmacological evaluation of conformationally constrained glutamic acid higher homologues. Bioorg Med Chem 2016; 24:5741-5747. [PMID: 27658797 DOI: 10.1016/j.bmc.2016.09.029] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2016] [Revised: 09/08/2016] [Accepted: 09/11/2016] [Indexed: 11/26/2022]
Abstract
Homologation of glutamic acid chain together with conformational constraint is a commonly used strategy to achieve selectivity towards different types of glutamate receptors. In the present work, starting from two potent and selective unnatural amino acids previously developed by us, we investigated the effects on the activity/selectivity profile produced by a further increase in the distance between the amino acidic moiety and the distal carboxylate group. Interestingly, the insertion of an aromatic ring as a spacer produced a low micromolar affinity NMDA ligand that might represent a lead for the development of a new class of NMDA antagonists.
Collapse
Affiliation(s)
- Lucia Tamborini
- Department of Pharmaceutical Sciences, University of Milan, Via Mangiagalli 25, 20133 Milan, Italy
| | - Gregorio Cullia
- Department of Pharmaceutical Sciences, University of Milan, Via Mangiagalli 25, 20133 Milan, Italy
| | - Birgitte Nielsen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Universitetsparken 2, 2100 Copenhagen OE, Denmark
| | - Carlo De Micheli
- Department of Pharmaceutical Sciences, University of Milan, Via Mangiagalli 25, 20133 Milan, Italy
| | - Paola Conti
- Department of Pharmaceutical Sciences, University of Milan, Via Mangiagalli 25, 20133 Milan, Italy
| | - Andrea Pinto
- Department of Pharmaceutical Sciences, University of Milan, Via Mangiagalli 25, 20133 Milan, Italy.
| |
Collapse
|
67
|
Szymańska E, Chałupnik P, Szczepańska K, Cuñado Moral AM, Pickering DS, Nielsen B, Johansen TN, Kieć-Kononowicz K. Design, synthesis and structure-activity relationships of novel phenylalanine-based amino acids as kainate receptors ligands. Bioorg Med Chem Lett 2016; 26:5568-5572. [PMID: 27765511 DOI: 10.1016/j.bmcl.2016.09.075] [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: 07/18/2016] [Revised: 09/28/2016] [Accepted: 09/29/2016] [Indexed: 10/20/2022]
Abstract
A new series of carboxyaryl-substituted phenylalanines was designed, synthesized and pharmacologically characterized in vitro at native rat ionotropic glutamate receptors as well as at cloned homomeric kainate receptors GluK1-GluK3. Among them, six compounds bound to GluK1 receptor subtypes with reasonable affinity (Ki values in the range of 4.9-7.5μM). A structure-activity relationship (SAR) for the obtained series, focused mainly on the pharmacological effect of structural modifications in the 4- and 5-position of the phenylalanine ring, was established. To illustrate the results, molecular docking of the synthesized series to the X-ray structure of GluK1 ligand binding core was performed. The influence of individual substituents at the phenylalanine ring for both the affinity and selectivity at AMPA, GluK1 and GluK3 receptors was analyzed, giving directions for future studies.
Collapse
Affiliation(s)
- Ewa Szymańska
- Department of Technology and Biotechnology of Drugs, Jagiellonian University Medical College, Medyczna 9, PL 30-688 Kraków, Poland.
| | - Paulina Chałupnik
- Department of Technology and Biotechnology of Drugs, Jagiellonian University Medical College, Medyczna 9, PL 30-688 Kraków, Poland
| | - Katarzyna Szczepańska
- Department of Technology and Biotechnology of Drugs, Jagiellonian University Medical College, Medyczna 9, PL 30-688 Kraków, Poland
| | - Ana Maria Cuñado Moral
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, DK 2100 Copenhagen Ø, Denmark
| | - Darryl S Pickering
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, DK 2100 Copenhagen Ø, Denmark
| | - Birgitte Nielsen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, DK 2100 Copenhagen Ø, Denmark
| | - Tommy N Johansen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, DK 2100 Copenhagen Ø, Denmark
| | - Katarzyna Kieć-Kononowicz
- Department of Technology and Biotechnology of Drugs, Jagiellonian University Medical College, Medyczna 9, PL 30-688 Kraków, Poland
| |
Collapse
|
68
|
Abstract
Pain is a complex disease which can progress into a debilitating condition. The effective treatment of pain remains a challenge as current therapies often lack the desired level of efficacy or tolerability. One therapeutic avenue, the modulation of ion channel signaling by small molecules, has shown the ability to treat pain. However, of the 215 ion channels that exist in the human genome, with 85 ion channels having a strong literature link to pain, only a small number of these channels have been successfully drugged for pain. The focus of future research will be to fully explore the possibilities surrounding these unexplored ion channels. Toward this end, a greater understanding of ion channel modulation will be the greatest tool we have in developing the next generation of drugs for the treatment of pain.
Collapse
Affiliation(s)
- Sarah E Skerratt
- a Worldwide Medicinal Chemistry; Pfizer Global R&D ; Cambridge , UK
| | | |
Collapse
|
69
|
Soriano S, Ripoll C, Alonso-Magdalena P, Fuentes E, Quesada I, Nadal A, Martinez-Pinna J. Effects of Bisphenol A on ion channels: Experimental evidence and molecular mechanisms. Steroids 2016; 111:12-20. [PMID: 26930576 DOI: 10.1016/j.steroids.2016.02.020] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/28/2016] [Revised: 02/21/2016] [Accepted: 02/25/2016] [Indexed: 02/03/2023]
Abstract
Bisphenol A (BPA) is an endocrine-disrupting chemical (EDC) produced in huge quantities in the manufacture of polycarbonate plastics and epoxy resins. It is present in most humans in developed countries, acting as a xenoestrogen and it is considered an environmental risk factor associated to several diseases. Among the whole array of identified mechanisms by which BPA can interfere with physiological processes in living organisms, changes on ion channel activity is one of the most poorly understood. There is still little evidence about BPA regulation of ion channel expression and function. However, this information is key to understand how BPA disrupts excitable and non-excitable cells, including neurons, endocrine cells and muscle cells. This report is the result of a comprehensive literature review on the effects of BPA on ion channels. We conclude that there is evidence to say that these important molecules may be key end-points for EDCs acting as xenoestrogens. However, more research on channel-mediated BPA effects is needed. Particularly, mechanistic studies to unravel the pathophysiological actions of BPA on ion channels at environmentally relevant doses.
Collapse
Affiliation(s)
- Sergi Soriano
- Departamento de Fisiología, Genética y Microbiología, Universidad de Alicante, Spain
| | - Cristina Ripoll
- Instituto de Bioingeniería and CIBER de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Universidad Miguel Hernández de Elche, Spain
| | - Paloma Alonso-Magdalena
- Departamento de Biología Aplicada and CIBER de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Universidad Miguel Hernández de Elche, Spain
| | - Esther Fuentes
- Instituto de Bioingeniería and CIBER de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Universidad Miguel Hernández de Elche, Spain
| | - Ivan Quesada
- Instituto de Bioingeniería and CIBER de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Universidad Miguel Hernández de Elche, Spain
| | - Angel Nadal
- Instituto de Bioingeniería and CIBER de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Universidad Miguel Hernández de Elche, Spain.
| | - Juan Martinez-Pinna
- Departamento de Fisiología, Genética y Microbiología, Universidad de Alicante, Spain.
| |
Collapse
|
70
|
Bjørn-Yoshimoto WE, Underhill SM. The importance of the excitatory amino acid transporter 3 (EAAT3). Neurochem Int 2016; 98:4-18. [PMID: 27233497 DOI: 10.1016/j.neuint.2016.05.007] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2015] [Revised: 05/09/2016] [Accepted: 05/17/2016] [Indexed: 12/21/2022]
Abstract
The neuronal excitatory amino acid transporter 3 (EAAT3) is fairly ubiquitously expressed in the brain, though it does not necessarily maintain the same function everywhere. It is important in maintaining low local concentrations of glutamate, where its predominant post-synaptic localization can buffer nearby glutamate receptors and modulate excitatory neurotransmission and synaptic plasticity. It is also the main neuronal cysteine uptake system acting as the rate-limiting factor for the synthesis of glutathione, a potent antioxidant, in EAAT3 expressing neurons, while on GABAergic neurons, it is important in supplying glutamate as a precursor for GABA synthesis. Several diseases implicate EAAT3, and modulation of this transporter could prove a useful therapeutic approach. Regulation of EAAT3 could be targeted at several points for functional modulation, including the level of transcription, trafficking and direct pharmacological modulation, and indeed, compounds and experimental treatments have been identified that regulate EAAT3 function at different stages, which together with observations of EAAT3 regulation in patients is giving us insight into the endogenous function of this transporter, as well as the consequences of altered function. This review summarizes work done on elucidating the role and regulation of EAAT3.
Collapse
Affiliation(s)
- Walden E Bjørn-Yoshimoto
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Universitetsparken 2, 2100 København Ø, Denmark
| | - Suzanne M Underhill
- National Institute of Mental Health, National Institutes of Health, 35 Convent Drive Room 3A: 210 MSC3742, Bethesda, MD 20892-3742, USA.
| |
Collapse
|
71
|
García-Nafría J, Herguedas B, Watson JF, Greger IH. The dynamic AMPA receptor extracellular region: a platform for synaptic protein interactions. J Physiol 2016; 594:5449-58. [PMID: 26891027 DOI: 10.1113/jp271844] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2015] [Accepted: 01/21/2016] [Indexed: 12/27/2022] Open
Abstract
AMPA receptors (AMPARs) are glutamate-gated cation channels that mediate fast excitatory neurotransmission and synaptic plasticity. Structures of GluA2 homotetramers in distinct functional states, together with simulations, emphasise the loose architecture of the AMPAR extracellular region (ECR). The ECR encompasses ∼80% of the receptor, and consists of the membrane-distal N-terminal domain (NTD) and ligand-binding domain (LBD), which is fused to the ion channel domain. Minimal contacts within and between layers, together with flexible peptide linkers connecting these three domains give rise to an organisation capable of dynamic rearrangements. This building plan is uniquely suited to engage interaction partners in the crowded environment of synapses, permitting the formation of new binding sites and the loss of existing ones. ECR motions are thereby expected to impact signalling as well as synaptic anchorage and may thereby influence AMPAR clustering during synaptic plasticity.
Collapse
Affiliation(s)
- J García-Nafría
- Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, UK
| | - B Herguedas
- Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, UK
| | - J F Watson
- Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, UK
| | - I H Greger
- Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, UK.
| |
Collapse
|
72
|
Herguedas B, García-Nafría J, Cais O, Fernández-Leiro R, Krieger J, Ho H, Greger IH. Structure and organization of heteromeric AMPA-type glutamate receptors. Science 2016; 352:aad3873. [PMID: 26966189 DOI: 10.1126/science.aad3873] [Citation(s) in RCA: 83] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2015] [Accepted: 02/24/2016] [Indexed: 12/22/2022]
Abstract
AMPA-type glutamate receptors (AMPARs), which are central mediators of rapid neurotransmission and synaptic plasticity, predominantly exist as heteromers of the subunits GluA1 to GluA4. Here we report the first AMPAR heteromer structures, which deviate substantially from existing GluA2 homomer structures. Crystal structures of the GluA2/3 and GluA2/4 N-terminal domains reveal a novel compact conformation with an alternating arrangement of the four subunits around a central axis. This organization is confirmed by cysteine cross-linking in full-length receptors, and it permitted us to determine the structure of an intact GluA2/3 receptor by cryogenic electron microscopy. Two models in the ligand-free state, at resolutions of 8.25 and 10.3 angstroms, exhibit substantial vertical compression and close associations between domain layers, reminiscent of N-methyl-D-aspartate receptors. Model 1 resembles a resting state and model 2 a desensitized state, thus providing snapshots of gating transitions in the nominal absence of ligand. Our data reveal organizational features of heteromeric AMPARs and provide a framework to decipher AMPAR architecture and signaling.
Collapse
Affiliation(s)
- Beatriz Herguedas
- Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, UK
| | | | - Ondrej Cais
- Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, UK
| | | | - James Krieger
- Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, UK
| | - Hinze Ho
- Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, UK
| | - Ingo H Greger
- Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, UK
| |
Collapse
|
73
|
Fachim HA, Pereira AC, Iyomasa-Pilon MM, Rosa MLNM. Differential Expression of AMPA Subunits Induced by NMDA Intrahippocampal Injection in Rats. Front Neurosci 2016; 10:32. [PMID: 26912994 PMCID: PMC4753315 DOI: 10.3389/fnins.2016.00032] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2015] [Accepted: 01/26/2016] [Indexed: 11/13/2022] Open
Abstract
Glutamate is involved in excitotoxic mechanisms by interacting with different receptors. Such interactions result in neuronal death associated with several neurodegenerative disorders of the central nervous system (CNS). The aim of this work was to study the time course of changes in the expression of GluR1 and GluR2 subunits of glutamate amino-acid-3-hydroxy-5-methyl-isoxazol-4-propionic acid (AMPA) receptors in rat hippocampus induced by NMDA intrahippocampal injection. Rats were submitted to stereotaxic surgery for NMDA or saline (control) microinjection into dorsal hippocampus and the parameters were evaluated 24 h, 1, 2, and 4 weeks after injection. The extension and efficacy of the NMDA-induced injury were evaluated by Morris water maze (MWM) behavioral test and Nissl staining. The expression of GluR1 and GluR2 receptors, glial fibrillary acidic protein (GFAP), and neuronal marker (NeuN) was analyzed by immunohistochemistry. It was observed the impairment of learning and memory functions, loss of neuronal cells, and glial proliferation in CA1 area of NMDA compared with control groups, confirming the injury efficacy. In addition, NMDA injection induced distinct changes in GluR1 and GluR2 expression over the time. In conclusion, such changes may be related to the complex mechanism triggered in response to NMDA injection resulting in a local injury and in the activation of neuronal plasticity.
Collapse
Affiliation(s)
- Helene A Fachim
- Department of Biology, Faculty of Philosophy, Sciences and Letters of Ribeirao Preto, University of Sao PauloRibeirão Preto, Brazil; Institute of Neuroscience and BehaviorRibeirão Preto, Brazil
| | - Adriana C Pereira
- Department of Biology, Faculty of Philosophy, Sciences and Letters of Ribeirao Preto, University of Sao PauloRibeirão Preto, Brazil; Institute of Neuroscience and BehaviorRibeirão Preto, Brazil
| | | | - Maria L N M Rosa
- Institute of Neuroscience and BehaviorRibeirão Preto, Brazil; Barretos School of Health Sciences, Faculdade de Ciências da Saúde de Barretos Dr. Paulo Prata (FACISB)Barretos, Brazil
| |
Collapse
|
74
|
Probing Intersubunit Interfaces in AMPA-subtype Ionotropic Glutamate Receptors. Sci Rep 2016; 6:19082. [PMID: 26739260 PMCID: PMC4703952 DOI: 10.1038/srep19082] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2015] [Accepted: 12/07/2015] [Indexed: 01/09/2023] Open
Abstract
AMPA subtype ionotropic glutamate receptors (iGluRs) mediate the majority of fast neurotransmission across excitatory synapses in the central nervous system. Each AMPA receptor is composed of four multi-domain subunits that are organized into layers of two amino-terminal domain (ATD) dimers, two ligand-binding domain (LBD) dimers, transmembrane domains and carboxy-terminal domains. We introduced cysteine substitutions at the intersubunit interfaces of AMPA receptor subunit GluA2 and confirmed substituted cysteine crosslink formation by SDS-PAGE. The functional consequence of intersubunit crosslinks was assessed by recording GluA2-mediated currents in reducing and non-reducing conditions. Strong redox-dependent changes in GluA2-mediated currents were observed for cysteine substitutions at the LBD dimer-dimer interface but not at the ATD dimer-dimer interface. We conclude that during gating, LBD dimers undergo significant relative displacement, while ATD dimers either maintain their relative positioning, or their relative displacement has no appreciable effect on AMPA receptor function.
Collapse
|
75
|
Tobi D. Dynamics and allostery of the ionotropic glutamate receptors and the ligand binding domain. Proteins 2015; 84:267-77. [PMID: 26677170 DOI: 10.1002/prot.24977] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2015] [Revised: 10/19/2015] [Accepted: 12/10/2015] [Indexed: 12/31/2022]
Abstract
The dynamics of the ligand-binding domain (LBD) and the intact ionotropic glutamate receptor (iGluR) were studied using Gaussian Network Model (GNM) analysis. The dynamics of LBDs with various allosteric modulators is compared using a novel method of multiple alignment of GNM modes of motion. The analysis reveals that allosteric effectors change the dynamics of amino acids at the upper lobe interface of the LBD dimer as well as at the hinge region between the upper- and lower- lobes. For the intact glutamate receptor the analysis show that the clamshell-like movement of the LBD upper and lower lobes is coupled to the bending of the trans-membrane domain (TMD) helices which may open the channel pore. The results offer a new insight on the mechanism of action of allosteric modulators on the iGluR and support the notion of TMD helices bending as a possible mechanism for channel opening. In addition, the study validates the methodology of multiple GNM modes alignment as a useful tool to study allosteric effect and its relation to proteins dynamics.
Collapse
Affiliation(s)
- Dror Tobi
- Department of Computer Sciences and Mathematics, Department of Molecular Biology, Ariel University, Ariel, 40700, Israel
| |
Collapse
|
76
|
Kovács AD, Hof C, Pearce DA. Abnormally increased surface expression of AMPA receptors in the cerebellum, cortex and striatum of Cln3(-/-) mice. Neurosci Lett 2015; 607:29-34. [PMID: 26375929 DOI: 10.1016/j.neulet.2015.09.012] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2015] [Revised: 09/02/2015] [Accepted: 09/09/2015] [Indexed: 11/16/2022]
Abstract
Mutations in the CLN3 gene cause a fatal neurodegenerative disorder, juvenile CLN3 disease. Exploring the cause of the motor coordination deficit in the Cln3(-/-) mouse model of the disease we have previously found that attenuation of AMPA receptor activity in 1-month-old Cln3(-/-) mice significantly improves their motor coordination [20]. To elucidate the mechanism of the abnormally increased AMPA receptor function in Cln3(-/-) mice, we examined the surface expression of AMPA receptors using surface cross-linking in brain slices from 1-month-old wild type (WT) and Cln3(-/-) mice. In surface cross-linked brain samples, Western blotting for AMPA receptor subunits revealed significantly increased surface levels of GluA1 and GluA2 in the cerebellum, and of GluA2 in the cortex and striatum of Cln3(-/-) mice as compared to WT mice. Expression levels of the GluA4 subunit were similar in the cerebellum of WT and Cln3(-/-) mice. While intracellular GluA1 levels in the WT and Cln3(-/-) cerebellum or cortex were similar, the intracellular expression of GluA1 in the Cln3(-/-) striatum was decreased to 56% of the WT level. Our results show a prominent increase in AMPA receptor surface expression in the brain of Cln3(-/-) mice and suggest that CLN3 is involved in the regulation of AMPA receptor surface expression.
Collapse
Affiliation(s)
- Attila D Kovács
- Sanford Children's Health Research Center, Sanford Research, Sioux Falls, SD 57104, USA
| | - Caitlin Hof
- Sanford Children's Health Research Center, Sanford Research, Sioux Falls, SD 57104, USA
| | - David A Pearce
- Sanford Children's Health Research Center, Sanford Research, Sioux Falls, SD 57104, USA; Department of Pediatrics, Sanford School of Medicine, University of South Dakota, Sioux Falls, SD 57104, USA.
| |
Collapse
|
77
|
Structure, Dynamics, and Allosteric Potential of Ionotropic Glutamate Receptor N-Terminal Domains. Biophys J 2015; 109:1136-48. [PMID: 26255587 PMCID: PMC4576161 DOI: 10.1016/j.bpj.2015.06.061] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Revised: 06/22/2015] [Accepted: 06/30/2015] [Indexed: 12/26/2022] Open
Abstract
Ionotropic glutamate receptors (iGluRs) are tetrameric cation channels that mediate synaptic transmission and plasticity. They have a unique modular architecture with four domains: the intracellular C-terminal domain (CTD) that is involved in synaptic targeting, the transmembrane domain (TMD) that forms the ion channel, the membrane-proximal ligand-binding domain (LBD) that binds agonists such as L-glutamate, and the distal N-terminal domain (NTD), whose function is the least clear. The extracellular portion, comprised of the LBD and NTD, is loosely arranged, mediating complex allosteric regulation and providing a rich target for drug development. Here, we briefly review recent work on iGluR NTD structure and dynamics, and further explore the allosteric potential for the NTD in AMPA-type iGluRs using coarse-grained simulations. We also investigate mechanisms underlying the established NTD allostery in NMDA-type iGluRs, as well as the fold-related metabotropic glutamate and GABAB receptors. We show that the clamshell motions intrinsically favored by the NTD bilobate fold are coupled to dimeric and higher-order rearrangements that impact the iGluR LBD and ultimately the TMD. Finally, we explore the dynamics of intact iGluRs and describe how it might affect receptor operation in a synaptic environment.
Collapse
|
78
|
Cooperative Dynamics of Intact AMPA and NMDA Glutamate Receptors: Similarities and Subfamily-Specific Differences. Structure 2015; 23:1692-1704. [PMID: 26256538 DOI: 10.1016/j.str.2015.07.002] [Citation(s) in RCA: 65] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2015] [Revised: 06/19/2015] [Accepted: 07/01/2015] [Indexed: 01/03/2023]
Abstract
Ionotropic glutamate receptors (iGluRs) are tetrameric ion channels that mediate excitatory neurotransmission. Recent structures of α-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA) and N-methyl-D-aspartate (NMDA) receptors permit a comparative analysis of whole-receptor dynamics for the first time. Despite substantial differences in the packing of their two-domain extracellular region, the two iGluRs share similar dynamics, elucidated by elastic network models. Motions accessible to either structure enable conformational interconversion, such as compression of the AMPA receptor toward the more tightly packed NMDA receptor conformation, which has been linked to allosteric regulation. Pivoting motions coupled to concerted rotations of the transmembrane ion channel are prominent between dimers of distal N-terminal domains in the loosely packed AMPA receptor. The occurrence and functional relevance of these motions is verified by cross-linking experiments designed to probe the computationally predicted distance changes. Together with the identification of hotspot residues acting as mediators of allosteric communication, our data provide a glimpse into the dynamic spectrum of iGluRs.
Collapse
|
79
|
Joshi DC, Tewari BP, Singh M, Joshi PG, Joshi NB. AMPA receptor activation causes preferential mitochondrial Ca2+ load and oxidative stress in motor neurons. Brain Res 2015; 1616:1-9. [DOI: 10.1016/j.brainres.2015.04.042] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2014] [Revised: 04/18/2015] [Accepted: 04/22/2015] [Indexed: 01/05/2023]
|
80
|
Vorobyeva DV, Peregudov AS, Röschenthaler GV, Osipov SN. Synthesis of α-CF3-containing triazolyl amino acids as potential neurotransmitters via click-reaction. J Fluor Chem 2015. [DOI: 10.1016/j.jfluchem.2015.03.012] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
|
81
|
Schiavini P, Dawe GB, Bowie D, Moitessier N. Discovery of novel small-molecule antagonists for GluK2. Bioorg Med Chem Lett 2015; 25:2416-20. [PMID: 25913117 DOI: 10.1016/j.bmcl.2015.04.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2015] [Revised: 03/30/2015] [Accepted: 04/01/2015] [Indexed: 11/27/2022]
Abstract
KA receptors have shown to be potential therapeutic targets in CNS diseases such as schizophrenia, depression, neuropathic pain and epilepsy. Through the use of our docking tool Fitted, we investigated the relationship between ligand activity towards GluK2 and the conformational state induced at the receptor level. By focusing our rational design on the interaction between the ligand and a tyrosine residue in the binding site, we synthesized a series of molecules based on a glutamate scaffold, and carried out electrophysiological recordings. The observed ability of some of these molecules to inhibit receptor activation shows the potential of our design for the development of effective antagonists with a molecular size comparable to that of the endogenous neurotransmitter L-glutamate.
Collapse
Affiliation(s)
- Paolo Schiavini
- Department of Chemistry, McGill University, 801 Sherbrooke Street West, Montréal, Québec H3A 0B8, Canada
| | - G Brent Dawe
- Integrated Program in Neuroscience, McGill University, Canada; Department of Pharmacology, McGill University, 3649 Promenade Sir William Osler, Montréal, Québec H3G 0B1, Canada
| | - Derek Bowie
- Department of Pharmacology, McGill University, 3649 Promenade Sir William Osler, Montréal, Québec H3G 0B1, Canada
| | - Nicolas Moitessier
- Department of Chemistry, McGill University, 801 Sherbrooke Street West, Montréal, Québec H3A 0B8, Canada.
| |
Collapse
|
82
|
Development of PET and SPECT probes for glutamate receptors. ScientificWorldJournal 2015; 2015:716514. [PMID: 25874256 PMCID: PMC4385697 DOI: 10.1155/2015/716514] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2014] [Accepted: 08/29/2014] [Indexed: 01/16/2023] Open
Abstract
l-Glutamate and its receptors (GluRs) play a key role in excitatory neurotransmission within the mammalian central nervous system (CNS). Impaired regulation of GluRs has also been implicated in various neurological disorders. GluRs are classified into two major groups: ionotropic GluRs (iGluRs), which are ligand-gated ion channels, and metabotropic GluRs (mGluRs), which are coupled to heterotrimeric guanosine nucleotide binding proteins (G-proteins). Positron emission tomography (PET) and single photon emission computed tomography (SPECT) imaging of GluRs could provide a novel view of CNS function and of a range of brain disorders, potentially leading to the development of new drug therapies. Although no satisfactory imaging agents have yet been developed for iGluRs, several PET ligands for mGluRs have been successfully employed in clinical studies. This paper reviews current progress towards the development of PET and SPECT probes for GluRs.
Collapse
|
83
|
Dawe GB, Aurousseau MR, Daniels BA, Bowie D. Retour aux sources: defining the structural basis of glutamate receptor activation. J Physiol 2015; 593:97-110. [PMID: 25556791 PMCID: PMC4293057 DOI: 10.1113/jphysiol.2014.277921] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2014] [Accepted: 09/05/2014] [Indexed: 01/12/2023] Open
Abstract
Ionotropic glutamate receptors (iGluRs) are the major excitatory neurotransmitter receptor in the vertebrate CNS and, as a result, their activation properties lie at the heart of much of the neuronal network activity observed in the developing and adult brain. iGluRs have also been implicated in many nervous system disorders associated with postnatal development (e.g. autism, schizophrenia), cerebral insult (e.g. stroke, epilepsy), and disorders of the ageing brain (e.g. Alzheimer's disease, Parkinsonism). In view of this, an emphasis has been placed on understanding how iGluRs activate and desensitize in functional and structural terms. Early structural models of iGluRs suggested that the strength of the agonist response was primarily governed by the degree of closure induced in the ligand-binding domain (LBD). However, recent studies have suggested a more nuanced role for the LBD with current evidence identifying the iGluR LBD interface as a "hotspot" regulating agonist behaviour. Such ideas remain to be consolidated with recently solved structures of full-length iGluRs to account for the global changes that underlie channel activation and desensitization.
Collapse
Affiliation(s)
- G Brent Dawe
- Integrated Program in Neuroscience, McGill UniversityMontréal, Québec, Canada
- Department of Pharmacology and Therapeutics, McGill UniversityMontréal, Québec, Canada
| | - Mark R Aurousseau
- Graduate Program in Pharmacology, McGill UniversityMontréal, Québec, Canada
- Department of Pharmacology and Therapeutics, McGill UniversityMontréal, Québec, Canada
| | - Bryan A Daniels
- Department of Pharmacology and Therapeutics, McGill UniversityMontréal, Québec, Canada
| | - Derek Bowie
- Department of Pharmacology and Therapeutics, McGill UniversityMontréal, Québec, Canada
| |
Collapse
|
84
|
Partin KM. AMPA receptor potentiators: from drug design to cognitive enhancement. Curr Opin Pharmacol 2014; 20:46-53. [PMID: 25462292 DOI: 10.1016/j.coph.2014.11.002] [Citation(s) in RCA: 64] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2014] [Revised: 11/08/2014] [Accepted: 11/10/2014] [Indexed: 11/17/2022]
Abstract
Positive allosteric modulators of ionotropic glutamate receptors have emerged as a target for treating cognitive impairment and neurodegeneration, but also mental illnesses such as major depressive disorder. The possibility of creating a new class of pharmaceutical agent to treat refractive mental health issues has compelled researchers to redouble their efforts to develop a safe, effective treatment for memory and cognition impairments. Coupled with the more robust research methodologies that have emerged, including more sophisticated high-throughput-screens, higher resolution structural biology techniques, and more focused assessment on pharmacokinetics, the development of positive modulators of AMPA receptors holds great promise. We describe recent approaches that improve our understanding of the basic physiology underlying memory and cognition, and their application toward promoting human health.
Collapse
Affiliation(s)
- Kathryn M Partin
- Department of Biomedical Sciences, Colorado State University, Fort Collins, Co 80523-1617, United States.
| |
Collapse
|
85
|
Madeo M, Kovács AD, Pearce DA. The human synaptic vesicle protein, SV2A, functions as a galactose transporter in Saccharomyces cerevisiae. J Biol Chem 2014; 289:33066-71. [PMID: 25326386 DOI: 10.1074/jbc.c114.584516] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
SV2A is a synaptic vesicle membrane protein expressed in neurons and endocrine cells and involved in the regulation of neurotransmitter release. Although the exact function of SV2A still remains elusive, it was identified as the specific binding site for levetiracetam, a second generation antiepileptic drug. Our sequence analysis demonstrates that SV2A has significant homology with several yeast transport proteins belonging to the major facilitator superfamily (MFS). Many of these transporters are involved in sugar transport into yeast cells. Here we present evidence showing, for the first time, that SV2A is a galactose transporter. We expressed human SV2A in hexose transport-deficient EBY.VW4000 yeast cells and demonstrated that these cells are able to grow on galactose-containing medium but not on other fermentable carbon sources. Furthermore, the addition of the SV2A-binding antiepileptic drug levetiracetam to the medium inhibited the galactose-dependent growth of hexose transport-deficient EBY.VW4000 yeast cells expressing human SV2A. Most importantly, direct measurement of galactose uptake in the same strain verified that SV2A is able to transport extracellular galactose inside the cells. The newly identified galactose transport capability of SV2A may have an important role in regulating/modulating synaptic function.
Collapse
Affiliation(s)
- Marianna Madeo
- From the Sanford Children's Health Research Center, Sanford Research, Sioux Falls, South Dakota 57104 and
| | - Attila D Kovács
- From the Sanford Children's Health Research Center, Sanford Research, Sioux Falls, South Dakota 57104 and
| | - David A Pearce
- From the Sanford Children's Health Research Center, Sanford Research, Sioux Falls, South Dakota 57104 and the Department of Pediatrics, Sanford School of Medicine, University of South Dakota, Sioux Falls, South Dakota, 57104
| |
Collapse
|
86
|
Venskutonytė R, Larsen AP, Frydenvang K, Gajhede M, Sagot E, Assaf Z, Gefflaut T, Pickering DS, Bunch L, Kastrup JS. Molecular recognition of two 2,4-syn-functionalized (S)-glutamate analogues by the kainate receptor GluK3 ligand binding domain. ChemMedChem 2014; 9:2254-9. [PMID: 25044437 DOI: 10.1002/cmdc.201402204] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2014] [Indexed: 11/11/2022]
Abstract
The kainate receptors are the least studied subfamily of ionotropic glutamate receptors. These receptors are thought to have a neuromodulatory role and have been associated with a variety of disorders in the central nervous system. This makes kainate receptors interesting potential drug targets. Today, structures of the ligand binding domain (LBD) of the kainate receptor GluK3 are only known in complex with the endogenous agonist glutamate, the natural product kainate, and two synthetic agonists. Herein we report structures of GluK3 LBD in complex with two 2,4-syn-functionalized (S)-glutamate analogues to investigate their structural potential as chemical scaffolds. Similar binding affinities at GluK3 were determined for the 2-(methylcarbamoyl)ethyl analogue (Ki =4.0 μM) and the 2-(methoxycarbonyl)ethyl analogue (Ki =1.7 μM), in agreement with the similar positioning of the compounds within the binding pocket. As the binding affinity is similar to that of glutamate, this type of Cγ substituent could be used as a scaffold for introduction of even larger substituents reaching into unexplored binding site regions to achieve subtype selectivity.
Collapse
Affiliation(s)
- Raminta Venskutonytė
- Department of Drug Design & Pharmacology, Faculty of Health & Medical Sciences, University of Copenhagen, 2100 Copenhagen (Denmark)
| | | | | | | | | | | | | | | | | | | |
Collapse
|
87
|
Mutant β-III spectrin causes mGluR1α mislocalization and functional deficits in a mouse model of spinocerebellar ataxia type 5. J Neurosci 2014; 34:9891-904. [PMID: 25057192 DOI: 10.1523/jneurosci.0876-14.2014] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Spinocerebellar ataxia type 5 (SCA5), a dominant neurodegenerative disease characterized by profound Purkinje cell loss, is caused by mutations in SPTBN2, a gene that encodes β-III spectrin. SCA5 is the first neurodegenerative disorder reported to be caused by mutations in a cytoskeletal spectrin gene. We have developed a mouse model to understand the mechanistic basis for this disease and show that expression of mutant but not wild-type β-III spectrin causes progressive motor deficits and cerebellar degeneration. We show that endogenous β-III spectrin interacts with the metabotropic glutamate receptor 1α (mGluR1α) and that mice expressing mutant β-III spectrin have cerebellar dysfunction with altered mGluR1α localization at Purkinje cell dendritic spines, decreased mGluR1-mediated responses, and deficient mGluR1-mediated long-term potentiation. These results indicate that mutant β-III spectrin causes mislocalization and dysfunction of mGluR1α at dendritic spines and connects SCA5 with other disorders involving glutamatergic dysfunction and synaptic plasticity abnormalities.
Collapse
|
88
|
Yelshanskaya MV, Li M, Sobolevsky AI. Structure of an agonist-bound ionotropic glutamate receptor. Science 2014; 345:1070-4. [PMID: 25103407 DOI: 10.1126/science.1256508] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Ionotropic glutamate receptors (iGluRs) mediate most excitatory neurotransmission in the central nervous system and function by opening their ion channel in response to binding of agonist glutamate. Here, we report a structure of a homotetrameric rat GluA2 receptor in complex with partial agonist (S)-5-nitrowillardiine. Comparison of this structure with the closed-state structure in complex with competitive antagonist ZK 200775 suggests conformational changes that occur during iGluR gating. Guided by the structures, we engineered disulfide cross-links to probe domain interactions that are important for iGluR gating events. The combination of structural information, kinetic modeling, and biochemical and electrophysiological experiments provides insight into the mechanism of iGluR gating.
Collapse
Affiliation(s)
- Maria V Yelshanskaya
- Department of Biochemistry and Molecular Biophysics, Columbia University, 650 West 168th Street, New York, NY 10032, USA
| | - Minfen Li
- Department of Biochemistry and Molecular Biophysics, Columbia University, 650 West 168th Street, New York, NY 10032, USA
| | - Alexander I Sobolevsky
- Department of Biochemistry and Molecular Biophysics, Columbia University, 650 West 168th Street, New York, NY 10032, USA.
| |
Collapse
|
89
|
de Carvalho D, Patrone LGA, Taxini CL, Biancardi V, Vicente MC, Gargaglioni LH. Neurochemical and electrical modulation of the locus coeruleus: contribution to CO2drive to breathe. Front Physiol 2014; 5:288. [PMID: 25183958 PMCID: PMC4135231 DOI: 10.3389/fphys.2014.00288] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2014] [Accepted: 07/14/2014] [Indexed: 11/13/2022] Open
Abstract
The locus coeruleus (LC) is a dorsal pontine region, situated bilaterally on the floor of the fourth ventricle. It is considered to be the major source of noradrenergic innervation in the brain. These neurons are highly sensitive to CO2/pH, and chemical lesions of LC neurons largely attenuate the hypercapnic ventilatory response in unanesthetized adult rats. Developmental dysfunctions in these neurons are linked to pathological conditions such as Rett and sudden infant death syndromes, which can impair the control of the cardio-respiratory system. LC is densely innervated by fibers that contain glutamate, serotonin, and adenosine triphosphate, and these neurotransmitters strongly affect LC activity, including central chemoreflexes. Aside from neurochemical modulation, LC neurons are also strongly electrically coupled, specifically through gap junctions, which play a role in the CO2 ventilatory response. This article reviews the available data on the role of chemical and electrical neuromodulation of the LC in the control of ventilation.
Collapse
Affiliation(s)
- Débora de Carvalho
- Department of Animal Morphology and Physiology, Faculty of Agricultural and Veterinarian Sciences, Universidade Estadual Paulista - São Paulo State University Jaboticabal, Brazil
| | - Luis G A Patrone
- Department of Animal Morphology and Physiology, Faculty of Agricultural and Veterinarian Sciences, Universidade Estadual Paulista - São Paulo State University Jaboticabal, Brazil
| | - Camila L Taxini
- Department of Animal Morphology and Physiology, Faculty of Agricultural and Veterinarian Sciences, Universidade Estadual Paulista - São Paulo State University Jaboticabal, Brazil
| | - Vivian Biancardi
- Department of Animal Morphology and Physiology, Faculty of Agricultural and Veterinarian Sciences, Universidade Estadual Paulista - São Paulo State University Jaboticabal, Brazil
| | - Mariane C Vicente
- Department of Animal Morphology and Physiology, Faculty of Agricultural and Veterinarian Sciences, Universidade Estadual Paulista - São Paulo State University Jaboticabal, Brazil
| | - Luciane H Gargaglioni
- Department of Animal Morphology and Physiology, Faculty of Agricultural and Veterinarian Sciences, Universidade Estadual Paulista - São Paulo State University Jaboticabal, Brazil
| |
Collapse
|
90
|
Su JG, Qi LS, Li CH, Zhu YY, Du HJ, Hou YX, Hao R, Wang JH. Prediction of allosteric sites on protein surfaces with an elastic-network-model-based thermodynamic method. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2014; 90:022719. [PMID: 25215770 DOI: 10.1103/physreve.90.022719] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2014] [Indexed: 06/03/2023]
Abstract
Allostery is a rapid and efficient way in many biological processes to regulate protein functions, where binding of an effector at the allosteric site alters the activity and function at a distant active site. Allosteric regulation of protein biological functions provides a promising strategy for novel drug design. However, how to effectively identify the allosteric sites remains one of the major challenges for allosteric drug design. In the present work, a thermodynamic method based on the elastic network model was proposed to predict the allosteric sites on the protein surface. In our method, the thermodynamic coupling between the allosteric and active sites was considered, and then the allosteric sites were identified as those where the binding of an effector molecule induces a large change in the binding free energy of the protein with its ligand. Using the proposed method, two proteins, i.e., the 70 kD heat shock protein (Hsp70) and GluA2 alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptor, were studied and the allosteric sites on the protein surface were successfully identified. The predicted results are consistent with the available experimental data, which indicates that our method is a simple yet effective approach for the identification of allosteric sites on proteins.
Collapse
Affiliation(s)
- Ji Guo Su
- College of Science, Yanshan University, Qinhuangdao 066004, China
| | - Li Sheng Qi
- Shandong Provincial Key Laboratory of Functional Macromolecular Biophysics, Institute of Biophysics, Dezhou University, Dezhou 253023, China
| | - Chun Hua Li
- College of Life Science and Bioengineering, Beijing University of Technology, Beijing 100022, China
| | - Yan Ying Zhu
- College of Science, Yanshan University, Qinhuangdao 066004, China
| | - Hui Jing Du
- College of Science, Yanshan University, Qinhuangdao 066004, China
| | - Yan Xue Hou
- College of Science, Yanshan University, Qinhuangdao 066004, China
| | - Rui Hao
- College of Science, Yanshan University, Qinhuangdao 066004, China
| | - Ji Hua Wang
- Shandong Provincial Key Laboratory of Functional Macromolecular Biophysics, Institute of Biophysics, Dezhou University, Dezhou 253023, China
| |
Collapse
|
91
|
Green T, Nayeem N. The multifaceted subunit interfaces of ionotropic glutamate receptors. J Physiol 2014; 593:73-81. [PMID: 25556789 DOI: 10.1113/jphysiol.2014.273409] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2014] [Accepted: 05/30/2014] [Indexed: 01/14/2023] Open
Abstract
The past fifteen years has seen a revolution in our understanding of ionotropic glutamate receptor (iGluR) structure, starting with the first view of the ligand binding domain (LBD) published in 1998, and in many ways culminating in the publication of the full-length structure of GluA2 in 2009. These reports have revealed not only the central role played by subunit interfaces in iGluR function, but also myriad binding sites within interfaces for endogenous and exogenous factors. Changes in the conformation of inter-subunit interfaces are central to transmission of ligand gating into pore opening (itself a rearrangement of interfaces), and subsequent closure through desensitization. With the exception of the agonist binding site, which is located entirely within individual subunits, almost all modulatory factors affecting iGluRs appear to bind to sites in subunit interfaces. This review seeks to summarize what we currently understand about the diverse roles interfaces play in iGluR function, and to highlight questions for future research.
Collapse
Affiliation(s)
- Tim Green
- Department of Pharmacology, University of Liverpool, Ashton Street, Liverpool L69 3GE, UK
| | | |
Collapse
|
92
|
Mele M, Alò R, Avolio E, Canonaco M. Bcl-2/Bax Expression Levels Tend to Influence AMPAergic Trafficking Mechanisms During Hibernation in Mesocricetus auratus. J Mol Neurosci 2014; 55:374-84. [DOI: 10.1007/s12031-014-0342-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2014] [Accepted: 05/23/2014] [Indexed: 01/13/2023]
|
93
|
Liubinas SV, O'Brien TJ, Moffat BM, Drummond KJ, Morokoff AP, Kaye AH. Tumour associated epilepsy and glutamate excitotoxicity in patients with gliomas. J Clin Neurosci 2014; 21:899-908. [PMID: 24746886 DOI: 10.1016/j.jocn.2014.02.012] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2014] [Accepted: 02/22/2014] [Indexed: 02/04/2023]
Abstract
Tumour associated epilepsy (TAE) is common, debilitating and often not successfully controlled by surgical resection of the tumour and administration of multiple anti-epileptic drugs. It represents a cause of significant lost quality of life in an incurable disease and is therefore an important subject for ongoing research. The pathogenesis of TAE is likely to be multifactorial and involve, on the microscopic level, the interaction of genetic factors, changes in the peritumoural microenvironment, alterations in synaptic neurotransmitter release and re-uptake, and the excitotoxic effects of glutamate. On a macroscopic level, the occurrence of TAE is likely to be influenced by tumour size, location and interaction with environmental factors. The optimal treatment of TAE requires a multi-disciplinary approach with input from neurosurgeons, neurologists, radiologists, pathologists and basic scientists. This article reviews the current literature regarding the incidence, treatment, and aetiology of TAE.
Collapse
Affiliation(s)
- Simon V Liubinas
- Department of Neurosurgery, The Royal Melbourne Hospital, Grattan Street, Parkville, VIC 3050, Australia; Department of Surgery (RMH/WH), The University of Melbourne, Parkville, VIC, Australia.
| | - Terence J O'Brien
- Department of Medicine (RMH/WH), The University of Melbourne, Parkville, VIC, Australia
| | - Bradford M Moffat
- Department of Radiology (RMH/WH), The University of Melbourne, Parkville, VIC, Australia
| | - Katharine J Drummond
- Department of Neurosurgery, The Royal Melbourne Hospital, Grattan Street, Parkville, VIC 3050, Australia; Department of Surgery (RMH/WH), The University of Melbourne, Parkville, VIC, Australia
| | - Andrew P Morokoff
- Department of Neurosurgery, The Royal Melbourne Hospital, Grattan Street, Parkville, VIC 3050, Australia; Department of Surgery (RMH/WH), The University of Melbourne, Parkville, VIC, Australia
| | - Andrew H Kaye
- Department of Neurosurgery, The Royal Melbourne Hospital, Grattan Street, Parkville, VIC 3050, Australia; Department of Surgery (RMH/WH), The University of Melbourne, Parkville, VIC, Australia
| |
Collapse
|
94
|
Pinto A, Tamborini L, Mastronardi F, Ettari R, Safoz Y, Bunch L, Nielsen B, Jensen AA, De Micheli C, Conti P. Synthesis of (3-hydroxy-pyrazolin-5-yl)glycine based ligands interacting with ionotropic glutamate receptors. Eur J Med Chem 2014; 75:151-8. [PMID: 24531228 DOI: 10.1016/j.ejmech.2014.01.029] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2013] [Revised: 11/27/2013] [Accepted: 01/20/2014] [Indexed: 11/18/2022]
Abstract
Following the concept that increasing the molecular complexity may enhance the receptor selectivity, we replaced the 3-hydroxy-isoxazoline ring of model compound tricholomic acid with a 3-hydroxy-pyrazoline ring, which could be variously decorated at the N1 position, inserting groups characterized by different electronic and steric properties. Binding assays on rat brain synaptic membranes showed that, depending on the nature of the substituent, some of the new synthesized ligands interacted with either AMPA or KA receptors, with affinities in the mid-micromolar range.
Collapse
Affiliation(s)
- Andrea Pinto
- Dipartimento di Scienze Farmaceutiche, Università degli Studi di Milano, Via Mangiagalli 25, 20133 Milano, Italy.
| | - Lucia Tamborini
- Dipartimento di Scienze Farmaceutiche, Università degli Studi di Milano, Via Mangiagalli 25, 20133 Milano, Italy
| | - Federica Mastronardi
- Dipartimento di Scienze Farmaceutiche, Università degli Studi di Milano, Via Mangiagalli 25, 20133 Milano, Italy
| | - Roberta Ettari
- Dipartimento di Scienze Farmaceutiche, Università degli Studi di Milano, Via Mangiagalli 25, 20133 Milano, Italy
| | - Yeliz Safoz
- Dipartimento di Scienze Farmaceutiche, Università degli Studi di Milano, Via Mangiagalli 25, 20133 Milano, Italy; Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Universitetsparken 2, 2100 Copenhagen OE, Denmark
| | - Lennart Bunch
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Universitetsparken 2, 2100 Copenhagen OE, Denmark
| | - Birgitte Nielsen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Universitetsparken 2, 2100 Copenhagen OE, Denmark
| | - Anders A Jensen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Universitetsparken 2, 2100 Copenhagen OE, Denmark
| | - Carlo De Micheli
- Dipartimento di Scienze Farmaceutiche, Università degli Studi di Milano, Via Mangiagalli 25, 20133 Milano, Italy
| | - Paola Conti
- Dipartimento di Scienze Farmaceutiche, Università degli Studi di Milano, Via Mangiagalli 25, 20133 Milano, Italy
| |
Collapse
|
95
|
Probing for Improved Potency and In Vivo Bioavailability of Excitatory Amino Acid Transporter Subtype 1 Inhibitors UCPH-101 and UCPH-102: Design, Synthesis and Pharmacological Evaluation of Substituted 7-Biphenyl Analogs. Neurochem Res 2014; 39:1964-79. [DOI: 10.1007/s11064-014-1264-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2013] [Revised: 02/19/2014] [Accepted: 02/20/2014] [Indexed: 02/02/2023]
|
96
|
The developmental regulation of glutamate receptor-mediated calcium signaling in primary cultured rat hippocampal neurons. Neuroreport 2013; 24:492-7. [PMID: 23660635 DOI: 10.1097/wnr.0b013e32836206b5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
We have studied the developmental changes of glutamate-induced calcium (Ca²⁺) response in primary cultured hippocampal neurons at three different stages of cultures, 3, 7-8, and 14-16 days in vitro (DIV), using fura-2 single-cell digital micro-fluorimetry. We found that glutamate-induced Ca²⁺ signaling was altered during development, and that two different ionotropic glutamate receptors, α-amino-3-hydroxy-5-methyl-4-isoxazole propionate receptors (AMPARs) and N-methyl-D-aspartate receptors (NMDARs), were differently involved in the modulation of calcium response at different stages of neuronal culture. In the stages of culture at 3 and 8 DIV, glutamate-induced Ca²⁺ influx was mostly because of AMPAR activation and subsequent opening of voltage-dependent calcium channels, as Ca²⁺ response can be largely reduced by 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) and by nifedipine. In the advanced culture (14-17 DIV), glutamate-induced Ca²⁺ response was less sensitive to 6-cyano-7-nitroquinoxaline-2,3-dione and nifedipine. Furthermore, AMPA-induced Ca²⁺ response increased in a time-dependent manner during the cultures of 3-8 DIV and then reduced in the advanced culture of 14-17 DIV. NMDA-induced Ca²⁺ influx increased in a time-dependent manner, with a marked increase in the advanced culture (14-17 DIV). These results suggest that glutamate-induced Ca²⁺ signaling switched from AMPA-voltage-dependent calcium channel to NMDA-calcium signaling during development.
Collapse
|
97
|
Trigeminal Medullary Dorsal Horn Neurons Activated by Nasal Stimulation Coexpress AMPA, NMDA, and NK1 Receptors. ISRN NEUROSCIENCE 2013; 2013:152567. [PMID: 24967301 PMCID: PMC4045565 DOI: 10.1155/2013/152567] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/16/2013] [Accepted: 10/07/2013] [Indexed: 11/25/2022]
Abstract
Afferent information initiating the cardiorespiratory responses during nasal stimulation projects from the nasal passages to neurons within the trigeminal medullary dorsal horn (MDH) via the anterior ethmoidal nerve (AEN). Central AEN terminals are thought to release glutamate to activate the MDH neurons. This study was designed to determine which neurotransmitter receptors (AMPA, kainate, or NMDA glutamate receptor subtypes or the Substance P receptor NK1) are expressed by these activated MDH neurons. Fos was used as a neuronal marker of activated neurons, and immunohistochemistry combined with epifluorescent microscopy was used to determine which neurotransmitter receptor subunits were coexpressed by activated MDH neurons. Results indicate that, during nasal stimulation with ammonia vapors in urethane-anesthetized Sprague-Dawley rats, activated neurons within the superficial MDH coexpress the AMPA glutamate receptor subunits GluA1 (95.8%) and GluA2/3 (88.2%), the NMDA glutamate receptor subunits GluN1 (89.1%) and GluN2A (41.4%), and NK1 receptors (64.0%). It is therefore likely that during nasal stimulation the central terminals of the AEN release glutamate and substance P that then produces activation of these MDH neurons. The involvement of AMPA and NMDA receptors may mediate fast and slow neurotransmission, respectively, while NK1 receptor involvement may indicate activation of a nociceptive pathway.
Collapse
|
98
|
Sobolevsky AI. Structure and gating of tetrameric glutamate receptors. J Physiol 2013; 593:29-38. [PMID: 25556785 DOI: 10.1113/jphysiol.2013.264911] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2013] [Accepted: 10/25/2013] [Indexed: 11/08/2022] Open
Abstract
Ionotropic glutamate receptors (iGluRs) are ligand-gated ion channels that open their ion-conducting pores in response to the binding of agonist glutamate. In recent years, significant progress has been achieved in studies of iGluRs by determining numerous structures of isolated water-soluble ligand-binding and amino-terminal domains, as well as solving the first crystal structure of the full-length AMPA receptor in the closed, antagonist-bound state. These structural data combined with electrophysiological and fluorescence recordings, biochemical experiments, mutagenesis and molecular dynamics simulations have greatly improved our understanding of iGluR assembly, activation and desensitization processes. This article reviews the recent structural and functional advances in the iGluR field and summarizes them in a simplified model of full-length iGluR gating.
Collapse
Affiliation(s)
- Alexander I Sobolevsky
- Department of Biochemistry & Molecular Biophysics, Columbia University, 650 West 168th Street, Black Bldg. 513, New York, NY, 10032, USA
| |
Collapse
|
99
|
Krintel C, Harpsøe K, Zachariassen LG, Peters D, Frydenvang K, Pickering DS, Gajhede M, Kastrup JS. Structural analysis of the positive AMPA receptor modulators CX516 and Me-CX516 in complex with the GluA2 ligand-binding domain. ACTA CRYSTALLOGRAPHICA SECTION D: BIOLOGICAL CRYSTALLOGRAPHY 2013; 69:1645-52. [PMID: 23999288 DOI: 10.1107/s0907444913011839] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2013] [Accepted: 04/30/2013] [Indexed: 11/10/2022]
Abstract
Positive allosteric modulators of the ionotropic glutamate receptor A2 (GluA2) can serve as lead compounds for the development of cognitive enhancers. Several benzamide-type (S)-2-amino-3-(3-hydroxy-5-methyl-4-isoxazolyl)propionic acid (AMPA) receptor modulators such as aniracetam, CX516 and CX614 have been shown to inhibit the deactivation of AMPA receptors with a less pronounced effect on desensitization. Despite CX516 being an extensively investigated AMPA receptor modulator and one of the few clinically evaluated compounds, the binding mode of CX516 to AMPA receptors has not been reported. Here, the structures of a GluA2 ligand-binding domain mutant in complex with CX516 and the 3-methylpiperidine analogue of CX516 (Me-CX516) are reported. The structures show that the binding modes of CX516 and Me-CX516 are similar to those of aniracetam and CX614 and that there is limited space for substitution at the piperidine ring of CX516. The results therefore support that CX516, like aniracetam and CX614, modulates deactivation of AMPA receptors.
Collapse
Affiliation(s)
- Christian Krintel
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen, Denmark
| | | | | | | | | | | | | | | |
Collapse
|
100
|
Su JG, Du HJ, Hao R, Xu XJ, Li CH, Chen WZ, Wang CX. Identification of functionally key residues in AMPA receptor with a thermodynamic method. J Phys Chem B 2013; 117:8689-96. [PMID: 23822189 DOI: 10.1021/jp402290t] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
AMPA receptor mediates the fast excitatory synaptic transmission in the central nervous system, and it is activated by the binding of glutamate that results in the opening of the transmembrane ion channel. In the present work, the thermodynamic method developed by our group was improved and then applied to identify the functionally key residues that regulate the glutamate-binding affinity of AMPA receptor. In our method, the key residues are identified as those whose perturbation largely changes the ligand binding free energy of the protein. It is found that besides the ligand binding sites, other residues distant from the binding cleft can also influence the glutamate binding affinity through a long-range allosteric regulation. These allosteric sites include the hinge region of the ligand binding cleft, the dimer interface of the ligand binding domain, the linkers between the ligand binding domain and the transmembrane domain, and the interface between the N-terminal domain and the ligand binding domain. Our calculation results are consistent with the available experimental data. The results are helpful for our understanding of the mechanism of long-range allosteric communication in the AMPA receptor and the mechanism of channel opening triggered by glutamate binding.
Collapse
Affiliation(s)
- Ji Guo Su
- College of Science, Yanshan University, Qinhuangdao, China
| | | | | | | | | | | | | |
Collapse
|