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Szymańska E, Chałupnik P, Johansen TN, Nielsen B, Cuñado Moral AM, Pickering DS, Więckowska A, Kieć-Kononowicz K. Aryl- and heteroaryl-substituted phenylalanines as AMPA receptor ligands. Chem Biol Drug Des 2017. [PMID: 28636281 DOI: 10.1111/cbdd.13048] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
A series of racemic unnatural amino acids was rationally designed on the basis of recently published X-ray structures of the GluA2 LBD with bound phenylalanine-based antagonists. Twelve new diaryl- or aryl/heteroaryl-substituted phenylalanine derivatives were synthesized and evaluated in vitro in radioligand binding assays at native rat ionotropic glutamate receptors. The most interesting compound in this series, (RS)-2-amino-3-(3'-hydroxy-5-(1H-pyrazol-4-yl)-[1,1'-biphenyl]-3-yl)propanoic acid 7e, showed the binding affinity of 4.6 μm for native AMPA receptors and over fourfold lower affinity for kainic acid receptors. Furthermore, 7e was evaluated at recombinant homomeric rat GluA2 and GluA3 receptors. Recently reported X-ray structures 5CBR and 5CBS, representing two distinct antagonist binding modes, were used as templates for molecular docking of the synthesized series. Binding data supported with molecular modeling confirmed that aryl/heteroaryl-substituted phenylalanine analogues effectively bind to AMPA receptors with low micromolar affinity and high selectivity over native NMDA and kainate receptors. These properties make 7e a promising lead for the further development of new AMPA receptor ligands.
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Affiliation(s)
- Ewa Szymańska
- Department of Technology and Biotechnology of Drugs, Jagiellonian University Medical College, Kraków, Poland
| | - Paulina Chałupnik
- Department of Technology and Biotechnology of Drugs, Jagiellonian University Medical College, Kraków, Poland
| | - Tommy N Johansen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Birgitte Nielsen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Ana Maria Cuñado Moral
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Darryl S Pickering
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Anna Więckowska
- Department of Medicinal Chemistry, Jagiellonian University Medical College, Kraków, Poland
| | - Katarzyna Kieć-Kononowicz
- Department of Technology and Biotechnology of Drugs, Jagiellonian University Medical College, Kraków, Poland
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2
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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] [What about the content of this article? (0)] [Affiliation(s)] [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.
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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
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3
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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] [What about the content of this article? (0)] [Affiliation(s)] [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.
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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
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4
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Szymanska E, Frydenvang K, Pickering DS, Krintel C, Nielsen B, Kooshki A, Zachariassen LG, Olsen L, Kastrup JS, Johansen TN. Studies on Aryl-Substituted Phenylalanines: Synthesis, Activity, and Different Binding Modes at AMPA Receptors. J Med Chem 2015; 59:448-61. [PMID: 26653877 DOI: 10.1021/acs.jmedchem.5b01666] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A series of racemic aryl-substituted phenylalanines was synthesized and evaluated in vitro at recombinant rat GluA1-3, at GluK1-3, and at native AMPA receptors. The individual enantiomers of two target compounds, (RS)-2-amino-3-(3,4-dichloro-5-(5-hydroxypyridin-3-yl)phenyl)propanoic acid 37 and (RS)-2-amino-3-(3'-hydroxybiphenyl-3-yl)propanoic acid 38, were characterized. (S)-37 and (R)-38 were identified as the only biologically active isomers, both being antagonists at GluA2 receptors with Kb of 1.80 and 3.90 μM, respectively. To address this difference in enantiopharmacology, not previously seen for amino acid-based AMPA receptor antagonists, X-ray crystal structures of both eutomers in complex with the GluA2 ligand binding domain were solved. The cocrystal structures of (S)-37 and (R)-38 showed similar interactions of the amino acid parts but unexpected and different orientations and interactions of the biaromatic parts of the ligands inside the binding site, with (R)-38 having a binding mode not previously identified for amino acid-based antagonists.
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Affiliation(s)
- Ewa Szymanska
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen , 2100 Copenhagen, Denmark
| | - Karla Frydenvang
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen , 2100 Copenhagen, Denmark
| | - Darryl S Pickering
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen , 2100 Copenhagen, Denmark
| | - Christian Krintel
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen , 2100 Copenhagen, Denmark
| | - Birgitte Nielsen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen , 2100 Copenhagen, Denmark
| | - Ayesheh Kooshki
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen , 2100 Copenhagen, Denmark
| | - Linda G Zachariassen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen , 2100 Copenhagen, Denmark
| | - Lars Olsen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen , 2100 Copenhagen, Denmark
| | - Jette S Kastrup
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen , 2100 Copenhagen, Denmark
| | - Tommy N Johansen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen , 2100 Copenhagen, Denmark
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Alexander SPH, Benson HE, Faccenda E, Pawson AJ, Sharman JL, Spedding M, Peters JA, Harmar AJ. The Concise Guide to PHARMACOLOGY 2013/14: G protein-coupled receptors. Br J Pharmacol 2013; 170:1459-581. [PMID: 24517644 PMCID: PMC3892287 DOI: 10.1111/bph.12445] [Citation(s) in RCA: 505] [Impact Index Per Article: 45.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The Concise Guide to PHARMACOLOGY 2013/14 provides concise overviews of the key properties of over 2000 human drug targets with their pharmacology, plus links to an open access knowledgebase of drug targets and their ligands (www.guidetopharmacology.org), which provides more detailed views of target and ligand properties. The full contents can be found at http://onlinelibrary.wiley.com/doi/10.1111/bph.12444/full. G protein-coupled receptors are one of the seven major pharmacological targets into which the Guide is divided, with the others being G protein-coupled receptors, ligand-gated ion channels, ion channels, catalytic receptors, nuclear hormone receptors, transporters and enzymes. These are presented with nomenclature guidance and summary information on the best available pharmacological tools, alongside key references and suggestions for further reading. A new landscape format has easy to use tables comparing related targets. It is a condensed version of material contemporary to late 2013, which is presented in greater detail and constantly updated on the website www.guidetopharmacology.org, superseding data presented in previous Guides to Receptors and Channels. It is produced in conjunction with NC-IUPHAR and provides the official IUPHAR classification and nomenclature for human drug targets, where appropriate. It consolidates information previously curated and displayed separately in IUPHAR-DB and the Guide to Receptors and Channels, providing a permanent, citable, point-in-time record that will survive database updates.
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Affiliation(s)
- Stephen PH Alexander
- School of Life Sciences, University of Nottingham Medical SchoolNottingham, NG7 2UH, UK
| | - Helen E Benson
- The University/BHF Centre for Cardiovascular Science, University of EdinburghEdinburgh, EH16 4TJ, UK
| | - Elena Faccenda
- The University/BHF Centre for Cardiovascular Science, University of EdinburghEdinburgh, EH16 4TJ, UK
| | - Adam J Pawson
- The University/BHF Centre for Cardiovascular Science, University of EdinburghEdinburgh, EH16 4TJ, UK
| | - Joanna L Sharman
- The University/BHF Centre for Cardiovascular Science, University of EdinburghEdinburgh, EH16 4TJ, UK
| | | | - John A Peters
- Neuroscience Division, Medical Education Institute, Ninewells Hospital and Medical School, University of DundeeDundee, DD1 9SY, UK
| | - Anthony J Harmar
- The University/BHF Centre for Cardiovascular Science, University of EdinburghEdinburgh, EH16 4TJ, UK
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Serafimoska Z, N. Johansen T, Frydenvang K, Suturkova L. Ionotropic Glutamate Receptors (iGluRs): Overview of iGluR2 ligand binding domain in complex with agonists and antagonists. Maced Pharm Bull 2011. [DOI: 10.33320/maced.pharm.bull.2011.57.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Ionotropic glutamate receptors (iGluRs) constitute a family of ligand gated ion channels subdivided in three classes, NMDA, AMPA (iGluA1-4) and KA (1-5) according to the agonists that selectively activate them. iGluRs are tetrameric assemblies of highly homologous
receptor subunits. They are critically important for normal brain function and are considered to be involved on neurological disorders and degenerative diseases such as schizophrenia, Alzheimer’s disease, brain damage following stroke and epilepsy. Since the first publication of the structure of recombinant soluble protein of ligand binding domain of GluA2 extensive studies on this group of receptors were performed and many crystal structures as complexes of GluA2-LBD with agonists, partial agonists and antagonists were obtained. The structural information in combination with functional data makes good platform for consecutive investigation and design of new selective drugs
which will be used in treatment of neurodegerative diseases.
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Abstract
Glutamate receptors are the most prevalent excitatory neurotransmitter receptors in the vertebrate central nervous system. Determining the structural differences between the binding sites of different subtypes is crucial to our understanding of neuronal circuits and to the development of subtype specific drugs. The structures of the binding domain (S1S2) of the GluR3 (flip) AMPA receptor subunit bound to glutamate and AMPA and the GluR2 (flop) subunit bound to glutamate were determined by X-ray crystallography to 1.9, 2.1, and 1.55 A, respectively. Overall, the structure of GluR3 (flip) S1S2 is very similar to GluR2 (flop) S1S2 (backbone RMSD of 0.30 +/- 0.05 for glutamate-bound and 0.26 +/- 0.01 for AMPA-bound). The differences in the flip and flop isoforms are subtle and largely arise from one hydrogen bond across the dimer interface and associated water molecules. Comparison of the binding affinity for various agonists and partial agonists suggest that the S1S2 domains of GluR2 and GluR3 show only small differences in affinity, unlike what is found for the intact receptors (with the exception of one ligand, Cl-HIBO, which has a 10-fold difference in affinity for GluR2 vs. GluR3).
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Affiliation(s)
- Ahmed H Ahmed
- Department of Molecular Medicine, Cornell University, Ithaca, NY 14853, USA
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Kasper C, Frydenvang K, Naur P, Gajhede M, Pickering DS, Kastrup JS. Molecular mechanism of agonist recognition by the ligand-binding core of the ionotropic glutamate receptor 4. FEBS Lett 2008; 582:4089-94. [PMID: 19022251 DOI: 10.1016/j.febslet.2008.11.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2008] [Revised: 11/09/2008] [Accepted: 11/10/2008] [Indexed: 11/16/2022]
Abstract
The alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) class of ionotropic glutamate receptors comprises four different subunits: iGluR1/iGluR2 and iGluR3/iGluR4 forming two subgroups. Three-dimensional structures have been reported only of the ligand-binding core of iGluR2. Here, we present two X-ray structures of a soluble construct of the R/G unedited flip splice variant of the ligand-binding core of iGluR4 (iGluR4(i)(R)-S1S2) in complex with glutamate or AMPA. Subtle, but important differences are found in the ligand-binding cavity between the two AMPA receptor subgroups at position 724 (Tyr in iGluR1/iGluR2 and Phe in iGluR3/iGluR4), which in iGluR4 may lead to displacement of a water molecule and hence points to the possibility to make subgroup specific ligands.
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Affiliation(s)
- Christina Kasper
- Department of Medicinal Chemistry, Faculty of Pharmaceutical Sciences, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen, Denmark
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Beich-Frandsen M, Pickering DS, Mirza O, Johansen TN, Greenwood J, Vestergaard B, Schousboe A, Gajhede M, Liljefors T, Kastrup JS. Structures of the Ligand-Binding Core of iGluR2 in Complex with the Agonists (R)- and (S)-2-Amino-3-(4-hydroxy-1,2,5-thiadiazol-3-yl)propionic Acid Explain Their Unusual Equipotency. J Med Chem 2008; 51:1459-63. [DOI: 10.1021/jm701126w] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Mads Beich-Frandsen
- Department of Medicinal Chemistry (Biostructural Research), Department of Medicinal Chemistry (Neuromedicinal Chemistry), and Department of Pharmacology and Pharmacotherapy, Faculty of Pharmaceutical Sciences, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen, Denmark
| | - Darryl S. Pickering
- Department of Medicinal Chemistry (Biostructural Research), Department of Medicinal Chemistry (Neuromedicinal Chemistry), and Department of Pharmacology and Pharmacotherapy, Faculty of Pharmaceutical Sciences, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen, Denmark
| | - Osman Mirza
- Department of Medicinal Chemistry (Biostructural Research), Department of Medicinal Chemistry (Neuromedicinal Chemistry), and Department of Pharmacology and Pharmacotherapy, Faculty of Pharmaceutical Sciences, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen, Denmark
| | - Tommy N. Johansen
- Department of Medicinal Chemistry (Biostructural Research), Department of Medicinal Chemistry (Neuromedicinal Chemistry), and Department of Pharmacology and Pharmacotherapy, Faculty of Pharmaceutical Sciences, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen, Denmark
| | - Jeremy Greenwood
- Department of Medicinal Chemistry (Biostructural Research), Department of Medicinal Chemistry (Neuromedicinal Chemistry), and Department of Pharmacology and Pharmacotherapy, Faculty of Pharmaceutical Sciences, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen, Denmark
| | - Bente Vestergaard
- Department of Medicinal Chemistry (Biostructural Research), Department of Medicinal Chemistry (Neuromedicinal Chemistry), and Department of Pharmacology and Pharmacotherapy, Faculty of Pharmaceutical Sciences, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen, Denmark
| | - Arne Schousboe
- Department of Medicinal Chemistry (Biostructural Research), Department of Medicinal Chemistry (Neuromedicinal Chemistry), and Department of Pharmacology and Pharmacotherapy, Faculty of Pharmaceutical Sciences, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen, Denmark
| | - Michael Gajhede
- Department of Medicinal Chemistry (Biostructural Research), Department of Medicinal Chemistry (Neuromedicinal Chemistry), and Department of Pharmacology and Pharmacotherapy, Faculty of Pharmaceutical Sciences, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen, Denmark
| | - Tommy Liljefors
- Department of Medicinal Chemistry (Biostructural Research), Department of Medicinal Chemistry (Neuromedicinal Chemistry), and Department of Pharmacology and Pharmacotherapy, Faculty of Pharmaceutical Sciences, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen, Denmark
| | - Jette S. Kastrup
- Department of Medicinal Chemistry (Biostructural Research), Department of Medicinal Chemistry (Neuromedicinal Chemistry), and Department of Pharmacology and Pharmacotherapy, Faculty of Pharmaceutical Sciences, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen, Denmark
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Hald H, Naur P, Pickering DS, Sprogøe D, Madsen U, Timmermann DB, Ahring PK, Liljefors T, Schousboe A, Egebjerg J, Gajhede M, Kastrup JS. Partial Agonism and Antagonism of the Ionotropic Glutamate Receptor iGLuR5. J Biol Chem 2007; 282:25726-36. [PMID: 17581823 DOI: 10.1074/jbc.m700137200] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
More than 50 structures have been reported on the ligand-binding core of the ionotropic glutamate receptor iGluR2 that belongs to the 2-amino-3-(3-hydroxy-5-methyl-4-isoxazolyl)propionic acid-type of receptors. In contrast, the ligand-binding core of the kainic acid-type receptor iGluR5 has only been crystallized with three different ligands. Hence, additional structures of iGluR5 are needed to broaden the understanding of the ligand-binding properties of iGluR5, and the conformational changes leading to channel opening and closing. Here, we present two structures of the ligand-binding core of iGluR5; one as a complex with the partial agonist (2S,3S,4S)-3-carboxymethyl-4-[(1Z,3E,5R)-5-carboxy-1-methyl-hexa-1,3-dienyl]-pyrrolidine-2-carboxylic acid (domoic acid) and one as a complex with the antagonist (S)-2-amino-3-[5-tert-butyl-3-(phosphonomethoxy)-4-isoxazolyl]propionic acid ((S)-ATPO). In agreement with the partial agonist activity of domoic acid, the ligand-binding core of the iGluR5 complex is stabilized by domoic acid in a conformation that is 11 degrees more open than the conformation observed in the full agonist (S)-glutamic acid complex. This is primarily caused by the 5-carboxy-1-methyl-hexa-1,3-dienyl moiety of domoic acid and residues Val685-Thr690 of iGluR5. An even larger domain opening of 28 degrees is introduced upon binding of the antagonist (S)-ATPO. It appears that the span of domain opening is much larger in the ligand-binding core of iGluR5 (30 degrees) compared with what has been observed in iGluR2 (19 degrees ). Similarly, much larger variation in the distances between transmembrane linker residues in the two protomers comprising the dimer is observed in iGluR5 as compared with iGluR2.
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Affiliation(s)
- Helle Hald
- Department of Medicinal Chemistry, Faculty of Pharmaceutical Sciences, University of Copenhagen, Universitetsparken 2, DK-2100, Copenhagen, Denmark
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11
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Greenwood JR, Mewett KN, Allan RD, Martín BO, Pickering DS. 3-Hydroxypyridazine 1-oxides as carboxylate bioisosteres: A new series of subtype-selective AMPA receptor agonists. Neuropharmacology 2006; 51:52-9. [PMID: 16631211 DOI: 10.1016/j.neuropharm.2006.02.013] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2005] [Revised: 01/28/2006] [Accepted: 02/24/2006] [Indexed: 11/19/2022]
Abstract
Three positional isomers (compounds 1, 2, and 3) of 1-uracilylalanine (willardiine) based on a 3-hydroxypyridazine 1-oxide scaffold with an alanine side-chain at positions 4 (1), 5 (2) or 6 (3) were tested for binding to recombinant homomeric AMPA receptor (AMPA-R) subtypes GluR1-4, as well for excitatory activity on the rat cortical wedge preparation. 1 had approximately 30 times higher affinity than willardiine while showing a similar selectivity profile, i.e. 22-fold selectivity for GluR1/2 over GluR3/4. The GluR1-4 affinities of 3 were similar to 1, however, its 31-fold selectivity for GluR1/2 over GluR3/4 is the highest yet observed among azine-based glutamate analogues. The non-isosteric congener 2 showed weaker binding to AMPA-Rs. In the cortical wedge, 1 evokes similar responses to AMPA, while 3 and 2 are 10- and 100-fold weaker, respectively. Dose-response curves on Xenopus laevis oocytes expressing GluR1-4(flip) confirmed that 1 and 3 are potent GluR1/2 receptor agonists (EC(50)s from 0.26 to 1.7microM) but are 10- to 160-fold less potent at GluR3/4. The structures, potencies and selectivities of this new class of AMPA agonists are compared with those of willardiine, 5-fluorowillardiine and azawillardiine, referring to the binding mode observed in the crystal structure of willardiine bound to GluR2-S1S2. The results indicate that the 3-hydroxypyridazine 1-oxide moiety can function as an outstanding carboxylate mimic at AMPA-Rs, leading the way to further fine-tuning of subtype selectivity. This little-explored molecular motif may find wider application in medicinal chemistry.
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Affiliation(s)
- Jeremy R Greenwood
- Department of Medicinal Chemistry, Danish University of Pharmaceutical Sciences, Universitetsparken 2, DK 2100 Copenhagen, Denmark
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