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Germann AL, Pierce SR, Tateiwa H, Sugasawa Y, Reichert DE, Evers AS, Steinbach JH, Akk G. Intrasubunit and Intersubunit Steroid Binding Sites Independently and Additively Mediate α1 β2 γ2L GABA A Receptor Potentiation by the Endogenous Neurosteroid Allopregnanolone. Mol Pharmacol 2021; 100:19-31. [PMID: 33958479 DOI: 10.1124/molpharm.121.000268] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2021] [Accepted: 04/22/2021] [Indexed: 12/18/2022] Open
Abstract
Prior work employing functional analysis, photolabeling, and X-ray crystallography have identified three distinct binding sites for potentiating steroids in the heteromeric GABAA receptor. The sites are located in the membrane-spanning domains of the receptor at the β-α subunit interface (site I) and within the α (site II) and β subunits (site III). Here, we have investigated the effects of mutations to these sites on potentiation of the rat α1β2γ2L GABAA receptor by the endogenous neurosteroid allopregnanolone (3α5αP). The mutations were introduced alone or in combination to probe the additivity of effects. We show that the effects of amino acid substitutions in sites I and II are energetically additive, indicating independence of the actions of the two steroid binding sites. In site III, none of the mutations tested reduced potentiation by 3α5αP, nor did a mutation in site III modify the effects of mutations in sites I or II. We infer that the binding sites for 3α5αP act independently. The independence of steroid action at each site is supported by photolabeling data showing that mutations in either site I or site II selectively change steroid orientation in the mutated site without affecting labeling at the unmutated site. The findings are discussed in the context of linking energetic additivity to empirical changes in receptor function and ligand binding. SIGNIFICANCE STATEMENT: Prior work has identified three distinct binding sites for potentiating steroids in the heteromeric γ-aminobutyric acid type A receptor. This study shows that the sites act independently and additively in the presence of the steroid allopregnanolone and provide estimates of energetic contributions made by steroid binding to each site.
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Affiliation(s)
- Allison L Germann
- Departments of Anesthesiology (A.L.G., S.R.P., H.T., A.S.E., J.H.S., G.A.) and Radiology (D.E.R.), and the Taylor Family Institute for Innovative Psychiatric Research (D.E.R., A.S.E., J.H.S., G.A.), Washington University School of Medicine, St. Louis, Missouri; and Department of Anesthesiology and Pain Medicine, Juntendo University School of Medicine, Tokyo, Japan (Y.S.)
| | - Spencer R Pierce
- Departments of Anesthesiology (A.L.G., S.R.P., H.T., A.S.E., J.H.S., G.A.) and Radiology (D.E.R.), and the Taylor Family Institute for Innovative Psychiatric Research (D.E.R., A.S.E., J.H.S., G.A.), Washington University School of Medicine, St. Louis, Missouri; and Department of Anesthesiology and Pain Medicine, Juntendo University School of Medicine, Tokyo, Japan (Y.S.)
| | - Hiroki Tateiwa
- Departments of Anesthesiology (A.L.G., S.R.P., H.T., A.S.E., J.H.S., G.A.) and Radiology (D.E.R.), and the Taylor Family Institute for Innovative Psychiatric Research (D.E.R., A.S.E., J.H.S., G.A.), Washington University School of Medicine, St. Louis, Missouri; and Department of Anesthesiology and Pain Medicine, Juntendo University School of Medicine, Tokyo, Japan (Y.S.)
| | - Yusuke Sugasawa
- Departments of Anesthesiology (A.L.G., S.R.P., H.T., A.S.E., J.H.S., G.A.) and Radiology (D.E.R.), and the Taylor Family Institute for Innovative Psychiatric Research (D.E.R., A.S.E., J.H.S., G.A.), Washington University School of Medicine, St. Louis, Missouri; and Department of Anesthesiology and Pain Medicine, Juntendo University School of Medicine, Tokyo, Japan (Y.S.)
| | - David E Reichert
- Departments of Anesthesiology (A.L.G., S.R.P., H.T., A.S.E., J.H.S., G.A.) and Radiology (D.E.R.), and the Taylor Family Institute for Innovative Psychiatric Research (D.E.R., A.S.E., J.H.S., G.A.), Washington University School of Medicine, St. Louis, Missouri; and Department of Anesthesiology and Pain Medicine, Juntendo University School of Medicine, Tokyo, Japan (Y.S.)
| | - Alex S Evers
- Departments of Anesthesiology (A.L.G., S.R.P., H.T., A.S.E., J.H.S., G.A.) and Radiology (D.E.R.), and the Taylor Family Institute for Innovative Psychiatric Research (D.E.R., A.S.E., J.H.S., G.A.), Washington University School of Medicine, St. Louis, Missouri; and Department of Anesthesiology and Pain Medicine, Juntendo University School of Medicine, Tokyo, Japan (Y.S.)
| | - Joe Henry Steinbach
- Departments of Anesthesiology (A.L.G., S.R.P., H.T., A.S.E., J.H.S., G.A.) and Radiology (D.E.R.), and the Taylor Family Institute for Innovative Psychiatric Research (D.E.R., A.S.E., J.H.S., G.A.), Washington University School of Medicine, St. Louis, Missouri; and Department of Anesthesiology and Pain Medicine, Juntendo University School of Medicine, Tokyo, Japan (Y.S.)
| | - Gustav Akk
- Departments of Anesthesiology (A.L.G., S.R.P., H.T., A.S.E., J.H.S., G.A.) and Radiology (D.E.R.), and the Taylor Family Institute for Innovative Psychiatric Research (D.E.R., A.S.E., J.H.S., G.A.), Washington University School of Medicine, St. Louis, Missouri; and Department of Anesthesiology and Pain Medicine, Juntendo University School of Medicine, Tokyo, Japan (Y.S.)
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Niu C, Leavitt LS, Lin Z, Paguigan ND, Sun L, Zhang J, Torres JP, Raghuraman S, Chase K, Cadeddu R, Karthikeyan M, Bortolato M, Reilly CA, Hughen RW, Light AR, Olivera BM, Schmidt EW. Neuroactive Type-A γ-Aminobutyric Acid Receptor Allosteric Modulator Steroids from the Hypobranchial Gland of Marine Mollusk, Conus geographus. J Med Chem 2021; 64:7033-7043. [PMID: 33949869 DOI: 10.1021/acs.jmedchem.1c00562] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In a program to identify pain treatments with low addiction potential, we isolated five steroids, conosteroids A-E (1-5), from the hypobranchial gland of the mollusk Conus geographus. Compounds 1-5 were active in a mouse dorsal root ganglion (DRG) assay that suggested that they might be analgesic. A synthetic analogue 6 was used for a detailed pharmacological study. Compound 6 significantly increased the pain threshold in mice in the hot-plate test at 2 and 50 mg/kg. Compound 6 at 500 nM antagonizes type-A γ-aminobutyric acid receptors (GABAARs). In a patch-clamp experiment, out of the six subunit combinations tested, 6 exhibited subtype selectivity, most strongly antagonizing α1β1γ2 and α4β3γ2 receptors (IC50 1.5 and 1.0 μM, respectively). Although the structures of 1-6 differ from those of known neuroactive steroids, they are cell-type-selective modulators of GABAARs, expanding the known chemical space of neuroactive steroids.
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Affiliation(s)
- Changshan Niu
- Department of Medicinal Chemistry, University of Utah, Salt Lake City, Utah 84112, United States
| | - Lee S Leavitt
- School of Biological Sciences, University of Utah, Salt Lake City, Utah 84112, United States
| | - Zhenjian Lin
- Department of Medicinal Chemistry, University of Utah, Salt Lake City, Utah 84112, United States
| | - Noemi D Paguigan
- Department of Medicinal Chemistry, University of Utah, Salt Lake City, Utah 84112, United States
| | - Lili Sun
- Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, Utah 84112, United States
| | - Jie Zhang
- Department of Anesthesiology, School of Medicine, University of Utah, Salt Lake City, Utah 84112, United States
| | - Joshua P Torres
- Department of Medicinal Chemistry, University of Utah, Salt Lake City, Utah 84112, United States
| | - Shrinivasan Raghuraman
- School of Biological Sciences, University of Utah, Salt Lake City, Utah 84112, United States
| | - Kevin Chase
- School of Biological Sciences, University of Utah, Salt Lake City, Utah 84112, United States
| | - Roberto Cadeddu
- Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, Utah 84112, United States
| | - Manju Karthikeyan
- School of Biological Sciences, University of Utah, Salt Lake City, Utah 84112, United States
| | - Marco Bortolato
- Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, Utah 84112, United States
| | - Christopher A Reilly
- Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, Utah 84112, United States
| | - Ronald W Hughen
- Department of Anesthesiology, School of Medicine, University of Utah, Salt Lake City, Utah 84112, United States
| | - Alan R Light
- Department of Anesthesiology, School of Medicine, University of Utah, Salt Lake City, Utah 84112, United States
| | - Baldomero M Olivera
- School of Biological Sciences, University of Utah, Salt Lake City, Utah 84112, United States
| | - Eric W Schmidt
- Department of Medicinal Chemistry, University of Utah, Salt Lake City, Utah 84112, United States
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Field M, Dorovykh V, Thomas P, Smart TG. Physiological role for GABA A receptor desensitization in the induction of long-term potentiation at inhibitory synapses. Nat Commun 2021; 12:2112. [PMID: 33837214 PMCID: PMC8035410 DOI: 10.1038/s41467-021-22420-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Accepted: 03/03/2021] [Indexed: 01/03/2023] Open
Abstract
GABAA receptors (GABAARs) are pentameric ligand-gated ion channels distributed throughout the brain where they mediate synaptic and tonic inhibition. Following activation, these receptors undergo desensitization which involves entry into long-lived agonist-bound closed states. Although the kinetic effects of this state are recognised and its structural basis has been uncovered, the physiological impact of desensitization on inhibitory neurotransmission remains unknown. Here we describe an enduring form of long-term potentiation at inhibitory synapses that elevates synaptic current amplitude for 24 h following desensitization of GABAARs in response to agonist exposure or allosteric modulation. Using receptor mutants and allosteric modulators we demonstrate that desensitization of GABAARs facilitates their phosphorylation by PKC, which increases the number of receptors at inhibitory synapses. These observations provide a physiological relevance to the desensitized state of GABAARs, acting as a signal to regulate the efficacy of inhibitory synapses during prolonged periods of inhibitory neurotransmission.
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Affiliation(s)
- Martin Field
- Department of Neuroscience, Physiology and Pharmacology, UCL, London, UK
- Department of Pharmacology, University of Oxford, Oxford, UK
| | - Valentina Dorovykh
- Department of Neuroscience, Physiology and Pharmacology, UCL, London, UK
| | - Philip Thomas
- Department of Neuroscience, Physiology and Pharmacology, UCL, London, UK
| | - Trevor G Smart
- Department of Neuroscience, Physiology and Pharmacology, UCL, London, UK.
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54
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ATP7A-Regulated Enzyme Metalation and Trafficking in the Menkes Disease Puzzle. Biomedicines 2021; 9:biomedicines9040391. [PMID: 33917579 PMCID: PMC8067471 DOI: 10.3390/biomedicines9040391] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2021] [Revised: 04/01/2021] [Accepted: 04/02/2021] [Indexed: 12/12/2022] Open
Abstract
Copper is vital for numerous cellular functions affecting all tissues and organ systems in the body. The copper pump, ATP7A is critical for whole-body, cellular, and subcellular copper homeostasis, and dysfunction due to genetic defects results in Menkes disease. ATP7A dysfunction leads to copper deficiency in nervous tissue, liver, and blood but accumulation in other tissues. Site-specific cellular deficiencies of copper lead to loss of function of copper-dependent enzymes in all tissues, and the range of Menkes disease pathologies observed can now be explained in full by lack of specific copper enzymes. New pathways involving copper activated lysosomal and steroid sulfatases link patient symptoms usually related to other inborn errors of metabolism to Menkes disease. Additionally, new roles for lysyl oxidase in activation of molecules necessary for the innate immune system, and novel adapter molecules that play roles in ERGIC trafficking of brain receptors and other proteins, are emerging. We here summarize the current knowledge of the roles of copper enzyme function in Menkes disease, with a focus on ATP7A-mediated enzyme metalation in the secretory pathway. By establishing mechanistic relationships between copper-dependent cellular processes and Menkes disease symptoms in patients will not only increase understanding of copper biology but will also allow for the identification of an expanding range of copper-dependent enzymes and pathways. This will raise awareness of rare patient symptoms, and thus aid in early diagnosis of Menkes disease patients.
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55
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Kim JJ, Hibbs RE. Direct Structural Insights into GABA A Receptor Pharmacology. Trends Biochem Sci 2021; 46:502-517. [PMID: 33674151 DOI: 10.1016/j.tibs.2021.01.011] [Citation(s) in RCA: 44] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Revised: 01/08/2021] [Accepted: 01/25/2021] [Indexed: 12/18/2022]
Abstract
GABAA receptors are pentameric ligand-gated ion channels that mediate most fast neuronal inhibition in the brain. In addition to their important physiological roles, they are noteworthy in their rich pharmacology; prominent drugs used for anxiety, insomnia, and general anesthesia act through positive modulation of GABAA receptors. Direct structural information for how these drugs work was absent until recently. Efforts in structural biology over the past few years have revealed how important drug classes and natural products interact with the GABAA receptor, providing a foundation for studies in dynamics and structure-guided drug design. Here, we review recent developments in GABAA receptor structural pharmacology, focusing on subunit assemblies of the receptor found at synapses.
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Affiliation(s)
- Jeong Joo Kim
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Ryan E Hibbs
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
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56
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Relationship between Delta Rhythm, Seizure Occurrence and Allopregnanolone Hippocampal Levels in Epileptic Rats Exposed to the Rebound Effect. Pharmaceuticals (Basel) 2021; 14:ph14020127. [PMID: 33561937 PMCID: PMC7914513 DOI: 10.3390/ph14020127] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Revised: 01/29/2021] [Accepted: 02/03/2021] [Indexed: 11/24/2022] Open
Abstract
Abrupt withdrawal from antiepileptic drugs is followed by increased occurrence of epileptic seizures, a phenomenon known as the “rebound effect”. By stopping treatment with levetiracetam (LEV 300 mg/kg/day, n = 15; vs. saline, n = 15), we investigated the rebound effect in adult male Sprague-Dawley rats. LEV was continuously administered using osmotic minipumps, 7 weeks after the intraperitoneal administration of kainic acid (15 mg/kg). The effects of LEV were determined by comparing time intervals, treatments, and interactions between these main factors. Seizures were evaluated by video-electrocorticographic recordings and power band spectrum analysis. Furthermore, we assessed endogenous neurosteroid levels by liquid chromatography-electrospray-tandem mass spectrometry. LEV significantly reduced the percentage of rats experiencing seizures, reduced the seizure duration, and altered cerebral levels of neurosteroids. In the first week of LEV discontinuation, seizures increased abruptly up to 700% (p = 0.002, Tukey’s test). The power of delta band in the seizure postictal component was related to the seizure occurrence after LEV withdrawal (r2 = 0.73, p < 0.001). Notably, allopregnanolone hippocampal levels were positively related to the seizure occurrence (r2 = 0.51, p = 0.02) and to the power of delta band (r2 = 0.67, p = 0.004). These findings suggest a role for the seizure postictal component in the rebound effect, which involves an imbalance of hippocampal neurosteroid levels.
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57
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Lee J, Hitzenberger M, Rieger M, Kern NR, Zacharias M, Im W. CHARMM-GUI supports the Amber force fields. J Chem Phys 2021; 153:035103. [PMID: 32716185 DOI: 10.1063/5.0012280] [Citation(s) in RCA: 150] [Impact Index Per Article: 50.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
As part of our ongoing efforts to support diverse force fields and simulation programs in CHARMM-GUI, this work presents the development of FF-Converter to prepare Amber simulation inputs with various Amber force fields within the current CHARMM-GUI workflow. The currently supported Amber force fields are ff14SB/ff19SB (protein), Bsc1 (DNA), OL3 (RNA), GLYCAM06 (carbohydrate), Lipid17 (lipid), GAFF/GAFF2 (small molecule), TIP3P/TIP4P-EW/OPC (water), and 12-6-4 ions, and more will be added if necessary. The robustness and usefulness of this new CHARMM-GUI extension are demonstrated by two exemplary systems: a protein/N-glycan/ligand/membrane system and a protein/DNA/RNA system. Currently, CHARMM-GUI supports the Amber force fields only for the Amber program, but we will expand the FF-Converter functionality to support other simulation programs that support the Amber force fields.
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Affiliation(s)
- Jumin Lee
- Departments of Biological Sciences, Chemistry, and Bioengineering, Lehigh University, Bethlehem, Pennsylvania 18015, USA
| | - Manuel Hitzenberger
- Physics Department (T38), Technical University of Munich, James-Franck-Str. 1, 85748 Garching, Germany
| | - Manuel Rieger
- Physics Department (T38), Technical University of Munich, James-Franck-Str. 1, 85748 Garching, Germany
| | - Nathan R Kern
- Departments of Biological Sciences, Chemistry, and Bioengineering, Lehigh University, Bethlehem, Pennsylvania 18015, USA
| | - Martin Zacharias
- Physics Department (T38), Technical University of Munich, James-Franck-Str. 1, 85748 Garching, Germany
| | - Wonpil Im
- Departments of Biological Sciences, Chemistry, and Bioengineering, Lehigh University, Bethlehem, Pennsylvania 18015, USA
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Castellano D, Shepard RD, Lu W. Looking for Novelty in an "Old" Receptor: Recent Advances Toward Our Understanding of GABA ARs and Their Implications in Receptor Pharmacology. Front Neurosci 2021; 14:616298. [PMID: 33519367 PMCID: PMC7841293 DOI: 10.3389/fnins.2020.616298] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2020] [Accepted: 12/14/2020] [Indexed: 12/16/2022] Open
Abstract
Diverse populations of GABAA receptors (GABAARs) throughout the brain mediate fast inhibitory transmission and are modulated by various endogenous ligands and therapeutic drugs. Deficits in GABAAR signaling underlie the pathophysiology behind neurological and neuropsychiatric disorders such as epilepsy, anxiety, and depression. Pharmacological intervention for these disorders relies on several drug classes that target GABAARs, such as benzodiazepines and more recently neurosteroids. It has been widely demonstrated that subunit composition and receptor stoichiometry impact the biophysical and pharmacological properties of GABAARs. However, current GABAAR-targeting drugs have limited subunit selectivity and produce their therapeutic effects concomitantly with undesired side effects. Therefore, there is still a need to develop more selective GABAAR pharmaceuticals, as well as evaluate the potential for developing next-generation drugs that can target accessory proteins associated with native GABAARs. In this review, we briefly discuss the effects of benzodiazepines and neurosteroids on GABAARs, their use as therapeutics, and some of the pitfalls associated with their adverse side effects. We also discuss recent advances toward understanding the structure, function, and pharmacology of GABAARs with a focus on benzodiazepines and neurosteroids, as well as newly identified transmembrane proteins that modulate GABAARs.
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Affiliation(s)
- David Castellano
- Synapse and Neural Circuit Research Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, United States
| | - Ryan David Shepard
- Synapse and Neural Circuit Research Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, United States
| | - Wei Lu
- Synapse and Neural Circuit Research Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, United States
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Uchański T, Masiulis S, Fischer B, Kalichuk V, López-Sánchez U, Zarkadas E, Weckener M, Sente A, Ward P, Wohlkönig A, Zögg T, Remaut H, Naismith JH, Nury H, Vranken W, Aricescu AR, Pardon E, Steyaert J. Megabodies expand the nanobody toolkit for protein structure determination by single-particle cryo-EM. Nat Methods 2021; 18:60-68. [PMID: 33408403 PMCID: PMC7611088 DOI: 10.1038/s41592-020-01001-6] [Citation(s) in RCA: 66] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Accepted: 10/22/2020] [Indexed: 01/28/2023]
Abstract
Nanobodies are popular and versatile tools for structural biology. They have a compact single immunoglobulin domain organization, bind target proteins with high affinities while reducing their conformational heterogeneity and stabilize multi-protein complexes. Here we demonstrate that engineered nanobodies can also help overcome two major obstacles that limit the resolution of single-particle cryo-electron microscopy reconstructions: particle size and preferential orientation at the water-air interfaces. We have developed and characterized constructs, termed megabodies, by grafting nanobodies onto selected protein scaffolds to increase their molecular weight while retaining the full antigen-binding specificity and affinity. We show that the megabody design principles are applicable to different scaffold proteins and recognition domains of compatible geometries and are amenable for efficient selection from yeast display libraries. Moreover, we demonstrate that megabodies can be used to obtain three-dimensional reconstructions for membrane proteins that suffer from severe preferential orientation or are otherwise too small to allow accurate particle alignment.
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Affiliation(s)
- Tomasz Uchański
- Structural Biology Brussels, Vrije Universiteit Brussel, VUB, Brussels, Belgium
- VIB-VUB Center for Structural Biology, VIB, Brussels, Belgium
| | - Simonas Masiulis
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge, UK
| | - Baptiste Fischer
- Structural Biology Brussels, Vrije Universiteit Brussel, VUB, Brussels, Belgium
- VIB-VUB Center for Structural Biology, VIB, Brussels, Belgium
| | - Valentina Kalichuk
- Structural Biology Brussels, Vrije Universiteit Brussel, VUB, Brussels, Belgium
- VIB-VUB Center for Structural Biology, VIB, Brussels, Belgium
| | - Uriel López-Sánchez
- CNRS, Université Grenoble Alpes, CEA, Institut de Biologie Structurale, Grenoble, France
| | - Eleftherios Zarkadas
- CNRS, Université Grenoble Alpes, CEA, Institut de Biologie Structurale, Grenoble, France
| | - Miriam Weckener
- Rosalind Franklin Institute, Rutherford Appleton Laboratory, Didcot, UK
| | - Andrija Sente
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge, UK
| | - Philip Ward
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Oxford, UK
| | - Alexandre Wohlkönig
- Structural Biology Brussels, Vrije Universiteit Brussel, VUB, Brussels, Belgium
- VIB-VUB Center for Structural Biology, VIB, Brussels, Belgium
| | - Thomas Zögg
- Structural Biology Brussels, Vrije Universiteit Brussel, VUB, Brussels, Belgium
- VIB-VUB Center for Structural Biology, VIB, Brussels, Belgium
| | - Han Remaut
- Structural Biology Brussels, Vrije Universiteit Brussel, VUB, Brussels, Belgium
- VIB-VUB Center for Structural Biology, VIB, Brussels, Belgium
| | - James H Naismith
- Rosalind Franklin Institute, Rutherford Appleton Laboratory, Didcot, UK
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Oxford, UK
| | - Hugues Nury
- CNRS, Université Grenoble Alpes, CEA, Institut de Biologie Structurale, Grenoble, France
| | - Wim Vranken
- Structural Biology Brussels, Vrije Universiteit Brussel, VUB, Brussels, Belgium
- VIB-VUB Center for Structural Biology, VIB, Brussels, Belgium
- Interuniversity Institute of Bioinformatics in Brussels, ULB-VUB, Brussels, Belgium
| | - A Radu Aricescu
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge, UK.
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Oxford, UK.
| | - Els Pardon
- Structural Biology Brussels, Vrije Universiteit Brussel, VUB, Brussels, Belgium
- VIB-VUB Center for Structural Biology, VIB, Brussels, Belgium
| | - Jan Steyaert
- Structural Biology Brussels, Vrije Universiteit Brussel, VUB, Brussels, Belgium.
- VIB-VUB Center for Structural Biology, VIB, Brussels, Belgium.
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Lucchi C, Costa AM, Rustichelli C, Biagini G. Allopregnanolone and Pregnanolone Are Reduced in the Hippocampus of Epileptic Rats, but Only Allopregnanolone Correlates with Seizure Frequency. Neuroendocrinology 2021; 111:536-541. [PMID: 32492675 DOI: 10.1159/000509093] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Accepted: 06/02/2020] [Indexed: 11/19/2022]
Abstract
BACKGROUND Neurosteroids modulate epileptic activity by interacting with the γ-aminobutyric acid type A receptor, but their brain levels are still undetermined. OBJECTIVES We aimed to establish neurosteroid levels in the neocortex and hippocampus by liquid chromatography/mass spectrometry in epileptic rats. METHODS Kainic acid-treated rats were continuously monitored up to 9 weeks to determine seizure frequency by video electrocorticography (n = 23) and compared to age-matched controls monitored in the same manner (n = 11). RESULTS Decreased allopregnanolone (-50%; p < 0.05, Mann-Whitney test) and pregnanolone levels (-64%; p < 0.01) were found in the hippocampus, whereas pregnenolone sulfate, pregnenolone, progesterone, and 5α-dihydroprogesterone were nonsignificantly reduced. No changes were found in the neocortex. Moreover, allopregnanolone (but not pregnanolone) levels were positively correlated with seizure frequency (r2 = 0.4606, p < 0.01). CONCLUSION These findings indicate a selective reduction in hippocampal levels of 3α-reduced neurosteroids. This reduction was partially mitigated by seizures in the case of allopregnanolone.
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Affiliation(s)
- Chiara Lucchi
- Department of Biomedical, Metabolic, and Neural Sciences, University of Modena and Reggio Emilia, Modena, Italy
| | - Anna Maria Costa
- Department of Biomedical, Metabolic, and Neural Sciences, University of Modena and Reggio Emilia, Modena, Italy
| | - Cecilia Rustichelli
- Department of Life Sciences, University of Modena and Reggio Emilia, Modena, Italy
| | - Giuseppe Biagini
- Department of Biomedical, Metabolic, and Neural Sciences, University of Modena and Reggio Emilia, Modena, Italy,
- Center for Neuroscience and Neurotechnology, University of Modena and Reggio Emilia, Modena, Italy,
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Gao Y, Zhang Y, Wu F, Pei J, Luo X, Ju X, Zhao C, Liu G. Exploring the Interaction Mechanism of Desmethyl-broflanilide in Insect GABA Receptors and Screening Potential Antagonists by In Silico Simulations. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2020; 68:14768-14780. [PMID: 33274636 DOI: 10.1021/acs.jafc.0c05728] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Broflanilide, a novel insecticide, is classified as a negative allosteric modulator (NAM) of insect γ-aminobutyric acid (GABA) receptors (GABARs) as desmethyl-broflanilide (DMBF) allosterically inhibits the GABA-induced responses. The G277M mutation of the Drosophila melanogaster GABAR subunit has been reported to abolish the inhibitory activity of DMBF. The binding mode of DMBF in insect GABARs needs to be clarified to understand the underlying mechanism of this mutation and to develop novel, efficient NAMs of insect GABARs. Here, we found that a hydrogen bond formed between DMBF and G277 of the D. melanogaster GABAR model might be the key interaction for the antagonism of DMBF by in silico simulations. The volume increase induced by the G277M mutation blocks the entrance of the binding pocket, making it difficult for DMBF to enter the binding pocket and thereby decreasing its activity. The following virtual screening and bioassay results identified a novel NAM candidate of insect GABARs. Overall, we reported a possible binding mode of DMBF in insect GABARs and proposed the insensitivity mechanism of the G277M mutant GABAR to DMBF using molecular simulations. The identified NAM candidates might provide more alternatives or potentials for the design of GABAR-targeting insecticides.
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Affiliation(s)
- Ya Gao
- Hubei Key Laboratory of Novel Reactor and Green Chemical Technology, School of Chemical Engineering and Pharmacy, Wuhan Institute of Technology, Wuhan 430205, P. R. China
| | - Yichi Zhang
- Education Ministry Key Laboratory of Integrated Management of Crop Diseases and Pests, College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, P. R. China
| | - Fengshou Wu
- Hubei Key Laboratory of Novel Reactor and Green Chemical Technology, School of Chemical Engineering and Pharmacy, Wuhan Institute of Technology, Wuhan 430205, P. R. China
| | - Jianfeng Pei
- Center for Quantitative Biology, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, P. R. China
| | - Xiaogang Luo
- Hubei Key Laboratory of Novel Reactor and Green Chemical Technology, School of Chemical Engineering and Pharmacy, Wuhan Institute of Technology, Wuhan 430205, P. R. China
- School of Materials Science and Engineering, Zhengzhou University, Zhengzhou 450001, P. R. China
| | - Xiulian Ju
- Hubei Key Laboratory of Novel Reactor and Green Chemical Technology, School of Chemical Engineering and Pharmacy, Wuhan Institute of Technology, Wuhan 430205, P. R. China
| | - Chunqing Zhao
- Education Ministry Key Laboratory of Integrated Management of Crop Diseases and Pests, College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, P. R. China
| | - Genyan Liu
- Hubei Key Laboratory of Novel Reactor and Green Chemical Technology, School of Chemical Engineering and Pharmacy, Wuhan Institute of Technology, Wuhan 430205, P. R. China
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Pressly B, Lee RD, Barnych B, Hammock BD, Wulff H. Identification of the Functional Binding Site for the Convulsant Tetramethylenedisulfotetramine in the Pore of the α 2 β 3 γ 2 GABA A Receptor. Mol Pharmacol 2020; 99:78-91. [PMID: 33109687 PMCID: PMC7746976 DOI: 10.1124/molpharm.120.000090] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Accepted: 10/06/2020] [Indexed: 11/22/2022] Open
Abstract
Tetramethylenedisulfotetramine (TETS) is a so-called "caged" convulsant that is responsible for thousands of accidental and malicious poisonings. Similar to the widely used GABA receptor type A (GABAA) antagonist picrotoxinin, TETS has been proposed to bind to the noncompetitive antagonist (NCA) site in the pore of the receptor channel. However, the TETS binding site has never been experimentally mapped, and we here set out to gain atomistic level insights into how TETS inhibits the human α 2 β 3 γ 2 GABAA receptor. Using the Rosetta molecular modeling suite, we generated three homology models of the α 2 β 3 γ 2 receptor in the open, desensitized, and closed/resting state. Three different ligand-docking algorithms (RosettaLigand, Glide, and Swissdock) identified two possible TETS binding sites in the channel pore. Using a combination of site-directed mutagenesis, electrophysiology, and modeling to probe both sites, we demonstrate that TETS binds at the T6' ring in the closed/resting-state model, in which it shows perfect space complementarity and forms hydrogen bonds or makes hydrophobic interactions with all five pore-lining threonine residues of the pentameric receptor. Mutating T6' in either the α 2 or β 3 subunit reduces the IC50 of TETS by ∼700-fold in whole-cell patch-clamp experiments. TETS is thus interacting at the NCA site in the pore of the GABAA receptor at a location that is overlapping but not identical to the picrotoxinin binding site. SIGNIFICANCE STATEMENT: Our study identifies the binding site of the highly toxic convulsant tetramethylenedisulfotetramine (TETS), which is classified as a threat agent by the World Health Organization. Using a combination of homology protein modeling, ligand docking, site-directed mutagenesis, and electrophysiology, we show that TETS is binding in the pore of the α2β3γ2 GABA receptor type A receptor at the so-called T6' ring, wherein five threonine residues line the permeation pathway of the pentameric receptor channel.
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Affiliation(s)
- Brandon Pressly
- Departments of Pharmacology (B.P., R.D.L, H.W.) and Entomology and Nematology, and Comprehensive Cancer Center (B.B., B.D.H.), University of California, Davis, California
| | - Ruth D Lee
- Departments of Pharmacology (B.P., R.D.L, H.W.) and Entomology and Nematology, and Comprehensive Cancer Center (B.B., B.D.H.), University of California, Davis, California
| | - Bogdan Barnych
- Departments of Pharmacology (B.P., R.D.L, H.W.) and Entomology and Nematology, and Comprehensive Cancer Center (B.B., B.D.H.), University of California, Davis, California
| | - Bruce D Hammock
- Departments of Pharmacology (B.P., R.D.L, H.W.) and Entomology and Nematology, and Comprehensive Cancer Center (B.B., B.D.H.), University of California, Davis, California
| | - Heike Wulff
- Departments of Pharmacology (B.P., R.D.L, H.W.) and Entomology and Nematology, and Comprehensive Cancer Center (B.B., B.D.H.), University of California, Davis, California
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63
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Gielen M, Barilone N, Corringer PJ. The desensitization pathway of GABA A receptors, one subunit at a time. Nat Commun 2020; 11:5369. [PMID: 33097732 PMCID: PMC7585415 DOI: 10.1038/s41467-020-19218-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Accepted: 09/17/2020] [Indexed: 01/05/2023] Open
Abstract
GABAA receptors mediate most inhibitory synaptic transmission in the brain of vertebrates. Following GABA binding and fast activation, these receptors undergo a slower desensitization, the conformational pathway of which remains largely elusive. To explore the mechanism of desensitization, we used concatemeric α1β2γ2 GABAA receptors to selectively introduce gain-of-desensitization mutations one subunit at a time. A library of twenty-six mutant combinations was generated and their bi-exponential macroscopic desensitization rates measured. Introducing mutations at the different subunits shows a strongly asymmetric pattern with a key contribution of the γ2 subunit, and combining mutations results in marked synergistic effects indicating a non-concerted mechanism. Kinetic modelling indeed suggests a pathway where subunits move independently, the desensitization of two subunits being required to occlude the pore. Our work thus hints towards a very diverse and labile conformational landscape during desensitization, with potential implications in physiology and pharmacology.
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Affiliation(s)
- Marc Gielen
- Channel Receptors Unit, Institut Pasteur, CNRS UMR 3571, 25 rue du Docteur Roux, 75015, Paris, France.
- Sorbonne Université, 21 rue de l'École de Médecine, 75006, Paris, France.
| | - Nathalie Barilone
- Channel Receptors Unit, Institut Pasteur, CNRS UMR 3571, 25 rue du Docteur Roux, 75015, Paris, France
| | - Pierre-Jean Corringer
- Channel Receptors Unit, Institut Pasteur, CNRS UMR 3571, 25 rue du Docteur Roux, 75015, Paris, France
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64
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de Oliveira TM, van Beek L, Shilliday F, Debreczeni JÉ, Phillips C. Cryo-EM: The Resolution Revolution and Drug Discovery. SLAS DISCOVERY 2020; 26:17-31. [PMID: 33016175 DOI: 10.1177/2472555220960401] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Single-particle cryogenic electron microscopy (cryo-EM) has been elevated to the mainstream of structural biology propelled by technological advancements in numerous fronts, including imaging analysis and the development of direct electron detectors. The drug discovery field has watched with (initial) skepticism and wonder at the progression of the technique and how it revolutionized the molecular understanding of previously intractable targets. This article critically assesses how cryo-EM has impacted drug discovery in diverse therapeutic areas. Targets that have been brought into the realm of structure-based drug design by cryo-EM and are thus reviewed here include membrane proteins like the GABAA receptor, several TRP channels, and G protein-coupled receptors, and multiprotein complexes like the ribosomes, the proteasome, and eIF2B. We will describe these studies highlighting the achievements, challenges, and caveats.
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Affiliation(s)
| | - Lotte van Beek
- Structure, Biophysics and FBLG, Discovery Sciences, AstraZeneca R&D, Cambridge, UK
| | - Fiona Shilliday
- Structure, Biophysics and FBLG, Discovery Sciences, AstraZeneca R&D, Cambridge, UK
| | - Judit É Debreczeni
- Structure, Biophysics and FBLG, Discovery Sciences, AstraZeneca R&D, Cambridge, UK
| | - Chris Phillips
- Structure, Biophysics and FBLG, Discovery Sciences, AstraZeneca R&D, Cambridge, UK
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Sugasawa Y, Cheng WW, Bracamontes JR, Chen ZW, Wang L, Germann AL, Pierce SR, Senneff TC, Krishnan K, Reichert DE, Covey DF, Akk G, Evers AS. Site-specific effects of neurosteroids on GABA A receptor activation and desensitization. eLife 2020; 9:55331. [PMID: 32955433 PMCID: PMC7532004 DOI: 10.7554/elife.55331] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Accepted: 09/20/2020] [Indexed: 12/16/2022] Open
Abstract
This study examines how site-specific binding to three identified neurosteroid-binding sites in the α1β3 GABAA receptor (GABAAR) contributes to neurosteroid allosteric modulation. We found that the potentiating neurosteroid, allopregnanolone, but not its inhibitory 3β-epimer epi-allopregnanolone, binds to the canonical β3(+)–α1(-) intersubunit site that mediates receptor activation by neurosteroids. In contrast, both allopregnanolone and epi-allopregnanolone bind to intrasubunit sites in the β3 subunit, promoting receptor desensitization and the α1 subunit promoting effects that vary between neurosteroids. Two neurosteroid analogues with diazirine moieties replacing the 3-hydroxyl (KK148 and KK150) bind to all three sites, but do not potentiate GABAAR currents. KK148 is a desensitizing agent, whereas KK150 is devoid of allosteric activity. These compounds provide potential chemical scaffolds for neurosteroid antagonists. Collectively, these data show that differential occupancy and efficacy at three discrete neurosteroid-binding sites determine whether a neurosteroid has potentiating, inhibitory, or competitive antagonist activity on GABAARs.
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Affiliation(s)
- Yusuke Sugasawa
- Department of Anesthesiology, Washington University in St. Louis, St. Louis, United States
| | - Wayland Wl Cheng
- Department of Anesthesiology, Washington University in St. Louis, St. Louis, United States
| | - John R Bracamontes
- Department of Anesthesiology, Washington University in St. Louis, St. Louis, United States
| | - Zi-Wei Chen
- Department of Anesthesiology, Washington University in St. Louis, St. Louis, United States.,Taylor Family Institute for Innovative Psychiatric Research, Washington University in St. Louis, St. Louis, United States
| | - Lei Wang
- Department of Anesthesiology, Washington University in St. Louis, St. Louis, United States
| | - Allison L Germann
- Department of Anesthesiology, Washington University in St. Louis, St. Louis, United States
| | - Spencer R Pierce
- Department of Anesthesiology, Washington University in St. Louis, St. Louis, United States
| | - Thomas C Senneff
- Department of Anesthesiology, Washington University in St. Louis, St. Louis, United States
| | - Kathiresan Krishnan
- Department of Developmental Biology, Washington University in St. Louis, St. Louis, United States
| | - David E Reichert
- Taylor Family Institute for Innovative Psychiatric Research, Washington University in St. Louis, St. Louis, United States.,Department of Radiology, Washington University in St. Louis, St. Louis, United States
| | - Douglas F Covey
- Department of Anesthesiology, Washington University in St. Louis, St. Louis, United States.,Taylor Family Institute for Innovative Psychiatric Research, Washington University in St. Louis, St. Louis, United States.,Department of Developmental Biology, Washington University in St. Louis, St. Louis, United States.,Department of Psychiatry, Washington University in St. Louis, St. Louis, United States
| | - Gustav Akk
- Department of Anesthesiology, Washington University in St. Louis, St. Louis, United States.,Taylor Family Institute for Innovative Psychiatric Research, Washington University in St. Louis, St. Louis, United States
| | - Alex S Evers
- Department of Anesthesiology, Washington University in St. Louis, St. Louis, United States.,Taylor Family Institute for Innovative Psychiatric Research, Washington University in St. Louis, St. Louis, United States.,Department of Developmental Biology, Washington University in St. Louis, St. Louis, United States
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66
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Thompson MJ, Baenziger JE. Structural basis for the modulation of pentameric ligand-gated ion channel function by lipids. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2020; 1862:183304. [DOI: 10.1016/j.bbamem.2020.183304] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2019] [Revised: 03/20/2020] [Accepted: 04/05/2020] [Indexed: 10/24/2022]
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Germann AL, Reichert DE, Burbridge AB, Pierce SR, Evers AS, Steinbach JH, Akk G. Analysis of Modulation of the ρ1 GABA A Receptor by Combinations of Inhibitory and Potentiating Neurosteroids Reveals Shared and Distinct Binding Sites. Mol Pharmacol 2020; 98:280-291. [PMID: 32675382 DOI: 10.1124/mol.120.119842] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Accepted: 07/07/2020] [Indexed: 11/22/2022] Open
Abstract
The ρ1 GABAA receptor is prominently expressed in the retina and is present at lower levels in several brain regions and other tissues. Although the ρ1 receptor is insensitive to many anesthetic drugs that modulate the heteromeric GABAA receptor, it maintains a rich and multifaceted steroid pharmacology. The receptor is negatively modulated by 5β-reduced steroids, sulfated or carboxylated steroids, and β-estradiol, whereas many 5α-reduced steroids potentiate the receptor. In this study, we analyzed modulation of the human ρ1 GABAA receptor by several neurosteroids, individually and in combination, in the framework of the coagonist concerted transition model. Experiments involving coapplication of two or more steroids revealed that the receptor contains at least three classes of distinct, nonoverlapping sites for steroids, one each for the inhibitory steroids pregnanolone (3α5βP), 3α5βP sulfate, and β-estradiol. The site for 3α5βP can accommodate the potentiating steroid 5αTHDOC. The findings are discussed with respect to receptor modulation by combinations of endogenous neurosteroids. SIGNIFICANCE STATEMENT: The study describes modulation of the ρ1 GABAA receptor by neurosteroids. The coagonist concerted transition model was used to determine overlap of binding sites for several inhibitory and potentiating steroids.
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Affiliation(s)
- Allison L Germann
- Departments of Anesthesiology (A.L.G., A.B.B., S.R.P., A.S.E., J.H.S., G.A.) and Radiology (D.E.R.) and the Taylor Family Institute for Innovative Psychiatric Research (D.E.R., A.S.E., J.H.S., G.A.), Washington University School of Medicine, St. Louis, Missouri
| | - David E Reichert
- Departments of Anesthesiology (A.L.G., A.B.B., S.R.P., A.S.E., J.H.S., G.A.) and Radiology (D.E.R.) and the Taylor Family Institute for Innovative Psychiatric Research (D.E.R., A.S.E., J.H.S., G.A.), Washington University School of Medicine, St. Louis, Missouri
| | - Ariel B Burbridge
- Departments of Anesthesiology (A.L.G., A.B.B., S.R.P., A.S.E., J.H.S., G.A.) and Radiology (D.E.R.) and the Taylor Family Institute for Innovative Psychiatric Research (D.E.R., A.S.E., J.H.S., G.A.), Washington University School of Medicine, St. Louis, Missouri
| | - Spencer R Pierce
- Departments of Anesthesiology (A.L.G., A.B.B., S.R.P., A.S.E., J.H.S., G.A.) and Radiology (D.E.R.) and the Taylor Family Institute for Innovative Psychiatric Research (D.E.R., A.S.E., J.H.S., G.A.), Washington University School of Medicine, St. Louis, Missouri
| | - Alex S Evers
- Departments of Anesthesiology (A.L.G., A.B.B., S.R.P., A.S.E., J.H.S., G.A.) and Radiology (D.E.R.) and the Taylor Family Institute for Innovative Psychiatric Research (D.E.R., A.S.E., J.H.S., G.A.), Washington University School of Medicine, St. Louis, Missouri
| | - Joe Henry Steinbach
- Departments of Anesthesiology (A.L.G., A.B.B., S.R.P., A.S.E., J.H.S., G.A.) and Radiology (D.E.R.) and the Taylor Family Institute for Innovative Psychiatric Research (D.E.R., A.S.E., J.H.S., G.A.), Washington University School of Medicine, St. Louis, Missouri
| | - Gustav Akk
- Departments of Anesthesiology (A.L.G., A.B.B., S.R.P., A.S.E., J.H.S., G.A.) and Radiology (D.E.R.) and the Taylor Family Institute for Innovative Psychiatric Research (D.E.R., A.S.E., J.H.S., G.A.), Washington University School of Medicine, St. Louis, Missouri
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68
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Arias HR, Do Rego JL, Do Rego JC, Chen Z, Anouar Y, Scholze P, Gonzales EB, Huang R, Chagraoui A. Coronaridine congeners potentiate GABA A receptors and induce sedative activity in mice in a benzodiazepine-insensitive manner. Prog Neuropsychopharmacol Biol Psychiatry 2020; 101:109930. [PMID: 32194202 DOI: 10.1016/j.pnpbp.2020.109930] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/2019] [Revised: 03/13/2020] [Accepted: 03/15/2020] [Indexed: 12/23/2022]
Abstract
To determine whether (+)-catharanthine induces sedative- or anxiolytic/anxiogenic-like activity in male mice, proper animal paradigms were used. The results showed that (+)-catharanthine induces sedative-like activity in the 63-72 mg/Kg dose range in a flumazenil-insensitive manner, but neither this effect nor anxiolytic/anxiogenic-like activity was observed at lower doses. To determine the underlying molecular mechanism of the sedative-like activity, electrophysiological and radioligand binding experiments were performed with (+)-catharanthine and (±)-18-methoxycoronaridine [(±)-18-MC] on GABAA (GABAARs) and glycine receptors (GlyRs). Coronaridine congeners both activated and potentiated a variety of human (h) GABAARs, except hρ1. (+)-Catharanthine-induced potentiation followed this receptor selectivity (EC50's in μM): hα1β2 (4.6 ± 0.8) > hα2β2γ2 (12.6 ± 3.8) ~ hα1β2γ2 (14.4 ± 4.6) indicating that both α1 and α2 are equally important, whereas γ2 is not necessary. (+)-Catharanthine was >2-fold more potent and efficient than (±)-18-MC at hα1β2γ2. (+)-Catharanthine also potentiated, whereas (±)-18-MC inhibited, hα1 GlyRs with very low potency. Additional [3H]-flunitrazepam competition binding experiments using rat cerebellum membranes clearly demonstrated that these ligands do not bind to the benzodiazepine site. This is supported by the observed activity at hα1β2 (lacking the BDZ site) and similar effects between α1- and α2-containing GABAARs. Our study shows, for the first time, that (+)-catharanthine induced sedative-like effects in mice, and coronaridine congeners potentiated human α1β2γ2, α1β2, and hα2β2γ2, but not ρ1, GABAARs, both in a benzodiazepine-insensitive fashion, whereas only (+)-catharanthine slightly potentiated GlyRs.
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Affiliation(s)
- Hugo R Arias
- Department of Pharmacology and Physiology, Oklahoma State University College of Osteopathic Medicine, Tahlequah, OK, USA.
| | - Jean Luc Do Rego
- Behavioral Analysis Platform SCAC, Institute for Research and Innovation in Biomedicine (IRIB), University of Rouen Normandy, Rouen, France
| | - Jean Claude Do Rego
- Behavioral Analysis Platform SCAC, Institute for Research and Innovation in Biomedicine (IRIB), University of Rouen Normandy, Rouen, France
| | - Zhenglan Chen
- Department of Pharmacology and Neuroscience, Institute for Health Aging, University of North Texas Health Science Center at Fort Worth, TX, USA
| | - Youssef Anouar
- Laboratory of Neuronal and Neuroendocrine Differentiation and Communication, Normandie University, UNIROUEN, INSERM U1239, Institute for Research and Innovation in Biomedicine of Normandy (IRIB) Rouen, France
| | - Petra Scholze
- Department of Pathobiology of the Nervous System, Center for Brain Research, Medical University of Vienna, Vienna, Austria
| | - Eric B Gonzales
- Department of Pharmacology and Neuroscience, Institute for Health Aging, University of North Texas Health Science Center at Fort Worth, TX, USA
| | - Renqi Huang
- Department of Pharmacology and Neuroscience, Institute for Health Aging, University of North Texas Health Science Center at Fort Worth, TX, USA
| | - Abdeslam Chagraoui
- Laboratory of Neuronal and Neuroendocrine Differentiation and Communication, Normandie University, UNIROUEN, INSERM U1239, Institute for Research and Innovation in Biomedicine of Normandy (IRIB) Rouen, France; Department of Medical Biochemistry, Rouen University Hospital, CHU de Rouen, France.
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69
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Jayakar SS, Chiara DC, Zhou X, Wu B, Bruzik KS, Miller KW, Cohen JB. Photoaffinity labeling identifies an intersubunit steroid-binding site in heteromeric GABA type A (GABA A) receptors. J Biol Chem 2020; 295:11495-11512. [PMID: 32540960 DOI: 10.1074/jbc.ra120.013452] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Revised: 06/09/2020] [Indexed: 12/11/2022] Open
Abstract
Allopregnanolone (3α5α-P), pregnanolone, and their synthetic derivatives are potent positive allosteric modulators (PAMs) of GABAA receptors (GABAARs) with in vivo anesthetic, anxiolytic, and anti-convulsant effects. Mutational analysis, photoaffinity labeling, and structural studies have provided evidence for intersubunit and intrasubunit steroid-binding sites in the GABAAR transmembrane domain, but revealed only little definition of their binding properties. Here, we identified steroid-binding sites in purified human α1β3 and α1β3γ2 GABAARs by photoaffinity labeling with [3H]21-[4-(3-(trifluoromethyl)-3H-diazirine-3-yl)benzoxy]allopregnanolone ([3H]21-pTFDBzox-AP), a potent GABAAR PAM. Protein microsequencing established 3α5α-P inhibitable photolabeling of amino acids near the cytoplasmic end of the β subunit M4 (β3Pro-415, β3Leu-417, and β3Thr-418) and M3 (β3Arg-309) helices located at the base of a pocket in the β+-α- subunit interface that extends to the level of αGln-242, a steroid sensitivity determinant in the αM1 helix. Competition photolabeling established that this site binds with high affinity a structurally diverse group of 3α-OH steroids that act as anesthetics, anti-epileptics, and anti-depressants. The presence of a 3α-OH was crucial: 3-acetylated, 3-deoxy, and 3-oxo analogs of 3α5α-P, as well as 3β-OH analogs that are GABAAR antagonists, bound with at least 1000-fold lower affinity than 3α5α-P. Similarly, for GABAAR PAMs with the C-20 carbonyl of 3α5α-P or pregnanolone reduced to a hydroxyl, binding affinity is reduced by 1,000-fold, whereas binding is retained after deoxygenation at the C-20 position. These results provide a first insight into the structure-activity relationship at the GABAAR β+-α- subunit interface steroid-binding site and identify several steroid PAMs that act via other sites.
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Affiliation(s)
- Selwyn S Jayakar
- Department of Neurobiology, Harvard Medical School, Boston, Massachusetts
| | - David C Chiara
- Department of Neurobiology, Harvard Medical School, Boston, Massachusetts
| | - Xiaojuan Zhou
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, Massachusetts
| | - Bo Wu
- Department of Medicinal Chemistry and Pharmacognosy, University of Illinois at Chicago, Chicago, Illinois
| | - Karol S Bruzik
- Department of Medicinal Chemistry and Pharmacognosy, University of Illinois at Chicago, Chicago, Illinois
| | - Keith W Miller
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, Massachusetts
| | - Jonathan B Cohen
- Department of Neurobiology, Harvard Medical School, Boston, Massachusetts
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Cerdan AH, Sisquellas M, Pereira G, Barreto Gomes DE, Changeux JP, Cecchini M. The Glycine Receptor Allosteric Ligands Library (GRALL). Bioinformatics 2020; 36:3379-3384. [PMID: 32163115 PMCID: PMC7267813 DOI: 10.1093/bioinformatics/btaa170] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Revised: 02/19/2020] [Accepted: 03/09/2020] [Indexed: 01/01/2023] Open
Abstract
MOTIVATION Glycine receptors (GlyRs) mediate fast inhibitory neurotransmission in the brain and have been recognized as key pharmacological targets for pain. A large number of chemically diverse compounds that are able to modulate GlyR function both positively and negatively have been reported, which provides useful information for the development of pharmacological strategies and models for the allosteric modulation of these ion channels. RESULTS Based on existing literature, we have collected 218 unique chemical entities with documented modulatory activities at homomeric GlyR-α1 and -α3 and built a database named GRALL. This collection includes agonists, antagonists, positive and negative allosteric modulators and a number of experimentally inactive compounds. Most importantly, for a large fraction of them a structural annotation based on their putative binding site on the receptor is provided. This type of annotation, which is currently missing in other drug banks, along with the availability of cooperativity factors from radioligand displacement experiments are expected to improve the predictivity of in silico methodologies for allosteric drug discovery and boost the development of conformation-based pharmacological approaches. AVAILABILITY AND IMPLEMENTATION The GRALL library is distributed as a web-accessible database at the following link: https://ifm.chimie.unistra.fr/grall. For each molecular entry, it provides information on the chemical structure, the ligand-binding site, the direction of modulation, the potency, the 3D molecular structure and quantum-mechanical charges as determined by our in-house pipeline. CONTACT mcecchini@unistra.fr. SUPPLEMENTARY INFORMATION Supplementary data are available at Bioinformatics online.
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Affiliation(s)
- Adrien H Cerdan
- Institut de Chimie de Strasbourg, UMR7177, CNRS, Université de Strasbourg, F-67083 Strasbourg Cedex, France
- Channel-Receptors Unit, Institut Pasteur, 75015 Paris, France
| | - Marion Sisquellas
- Institut de Chimie de Strasbourg, UMR7177, CNRS, Université de Strasbourg, F-67083 Strasbourg Cedex, France
| | - Gilberto Pereira
- Institut de Chimie de Strasbourg, UMR7177, CNRS, Université de Strasbourg, F-67083 Strasbourg Cedex, France
| | - Diego E Barreto Gomes
- Diretoria de Metrologia Aplicada às Ciências da Vida-Instituto Nacional de Metrologia, Qualidade e Tecnologia, Duque de Caxias 25.250-020, Brazil
| | - Jean-Pierre Changeux
- CNRS, URA 2182, F-75015, Collège de France, F-75005 Paris, France
- Kavli Institute for Brain & Mind, University of California San Diego, La Jolla, CA 92093, USA
| | - Marco Cecchini
- Institut de Chimie de Strasbourg, UMR7177, CNRS, Université de Strasbourg, F-67083 Strasbourg Cedex, France
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71
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Wan L, Li Z, Liu T, Chen X, Xu Q, Yao W, Zhang C, Zhang Y. Epoxyeicosatrienoic acids: Emerging therapeutic agents for central post-stroke pain. Pharmacol Res 2020; 159:104923. [PMID: 32461186 DOI: 10.1016/j.phrs.2020.104923] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Revised: 05/05/2020] [Accepted: 05/08/2020] [Indexed: 01/23/2023]
Abstract
Central post-stroke pain (CPSP) is chronic neuropathic pain due to a lesion or dysfunction of the central nervous system following cerebrovascular insult. This syndrome is characterized by chronic somatosensory abnormalities including spontaneous pain, hyperalgesia and allodynia, which localize to body areas corresponding to the injured brain region. However, despite its potential to impair activities of daily life and cause mood disorders after stroke, it is probably the least recognized complication of stroke. All currently approved treatments for CPSP have limited efficacy but troublesome side effects. The detailed mechanism underlying CPSP is still under investigation; however, its diverse clinical features indicate excessive central neuronal excitability, which is attributed to loss of inhibition and excessive neuroinflammation. Recently, exogenous epoxyeicosatrienoic acids (EETs) have been used to attenuate the mechanical allodynia in CPSP rats and proven to provide a quicker onset and superior pain relief compared to the current first line drug gabapentin. This anti-nociceptive effect is mediated by reserving the normal thalamic inhibition state through neurosteroid-GABA signaling. Moreover, mounting evidence has revealed that EETs exert anti-inflammatory effects by inhibiting the expression of vascular adhesion molecules, activating NFκB, inflammatory cytokines secretion and COX-2 gene induction. The present review focuses on the extensive evidence supporting the potential of EETs to be a multi-functional therapeutic approach for CPSP. Additionally, the role of EETs in the crosstalk between anti-CPSP and the comorbid mood disorder is reviewed herein.
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Affiliation(s)
- Li Wan
- Department of Anaesthesiology and Pain Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Zuofan Li
- Department of Anaesthesiology and Pain Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Tongtong Liu
- Department of Anaesthesiology and Pain Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Xuhui Chen
- Department of Ophthalmology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Qiaoqiao Xu
- Department of Anaesthesiology and Pain Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Wenlong Yao
- Department of Anaesthesiology and Pain Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Chuanhan Zhang
- Department of Anaesthesiology and Pain Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Yue Zhang
- Department of Anaesthesiology and Pain Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China.
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72
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Liu G, Wu Y, Gao Y, Ju X, Ozoe Y. Potential of Competitive Antagonists of Insect Ionotropic γ-Aminobutyric Acid Receptors as Insecticides. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2020; 68:4760-4768. [PMID: 32243147 DOI: 10.1021/acs.jafc.9b08189] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Ionotropic γ-aminobutyric acid (GABA) receptors (GABARs) represent an important insecticide target. Currently used GABAR-targeting insecticides are non-competitive antagonists (NCAs) of these receptors. Recent studies have demonstrated that competitive antagonists (CAs) of GABARs have functions of inhibiting insect GABARs similar to NCAs and that they also exhibit insecticidal activity. CAs have different binding sites and different mechanisms of action compared to those of NCAs. Therefore, GABAR CAs should have the potential to be developed into novel insecticides, which could be used to overcome the developed resistance of insect pests to conventional NCA insecticides. Although research on insect GABAR CAs has lagged behind that on mammalian GABAR CAs, research on the CAs of insect ionotropic GABARs has made great progress in recent years, and several series of heterocyclic compounds, such as 3-isoxazolols and 6-iminopyridazines, have been identified as insect GABAR CAs. In this review, we briefly summarize the design strategies, structures, and biological activities of the novel GABAR CAs that have been found in the past decade. Updated information about GABAR CAs may benefit the design and development of novel GABAR-targeting insecticides.
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Affiliation(s)
- Genyan Liu
- Key Laboratory for Green Chemical Process of Ministry of Education, School of Chemical Engineering and Pharmacy, Wuhan Institute of Technology, Wuhan, Hubei 430205, People's Republic of China
| | - Yun Wu
- Key Laboratory for Green Chemical Process of Ministry of Education, School of Chemical Engineering and Pharmacy, Wuhan Institute of Technology, Wuhan, Hubei 430205, People's Republic of China
| | - Ya Gao
- Key Laboratory for Green Chemical Process of Ministry of Education, School of Chemical Engineering and Pharmacy, Wuhan Institute of Technology, Wuhan, Hubei 430205, People's Republic of China
| | - Xiulian Ju
- Key Laboratory for Green Chemical Process of Ministry of Education, School of Chemical Engineering and Pharmacy, Wuhan Institute of Technology, Wuhan, Hubei 430205, People's Republic of China
| | - Yoshihisa Ozoe
- Faculty of Life and Environmental Science, Shimane University, Matsue, Shimane 690-8504, Japan
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73
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Yamato K, Nakata Y, Takashima M, Ozoe F, Asahi M, Kobayashi M, Ozoe Y. Effects of intersubunit amino acid substitutions on GABA receptor sensitivity to the ectoparasiticide fluralaner. PESTICIDE BIOCHEMISTRY AND PHYSIOLOGY 2020; 163:123-129. [PMID: 31973848 DOI: 10.1016/j.pestbp.2019.11.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Revised: 10/17/2019] [Accepted: 11/03/2019] [Indexed: 06/10/2023]
Abstract
The isoxazoline ectoparasiticide fluralaner exerts antiparasitic effects by inhibiting the function of γ-aminobutyric acid (GABA) receptors (GABARs). The present study was conducted to identify the amino acid residues that contribute to the high sensitivity of insect GABARs to fluralaner. We generated housefly (Musca domestica) GABARs with amino acid substitutions in the first through third α-helical transmembrane segments (TM1-TM3) of the RDL subunit using site-directed mutagenesis and examined the effects of the substitutions on the sensitivity of GABARs expressed in Xenopus oocytes to fluralaner using two-electrode voltage clamp electrophysiology. The Q271L substitution in TM1 caused a significant reduction in the sensitivity to fluralaner. Although the I274A and I274F substitutions in TM1 did not affect fluralaner sensitivity, the I274C substitution significantly enhanced the sensitivity to fluralaner. In contrast, the L278C substitution in TM1 reduced fluralaner sensitivity. Substitutions of Gly333 in TM3 led to substantial reductions in the sensitivity to fluralaner. These findings indicate that Gln271, Ile274, Leu278, and Gly333, which are situated in the outer half of the transmembrane subunit interface, are closely related to the antagonism of GABARs by fluralaner.
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Affiliation(s)
- Kohei Yamato
- Faculty of Life and Environmental Science, Shimane University, Matsue, Shimane 690-8504, Japan
| | - Yunosuke Nakata
- Faculty of Life and Environmental Science, Shimane University, Matsue, Shimane 690-8504, Japan
| | - Madoka Takashima
- Faculty of Life and Environmental Science, Shimane University, Matsue, Shimane 690-8504, Japan
| | - Fumiyo Ozoe
- Faculty of Life and Environmental Science, Shimane University, Matsue, Shimane 690-8504, Japan
| | - Miho Asahi
- Biological Research Laboratories, Nissan Chemical Corporation, Shiraoka, Saitama 349-0294, Japan
| | - Masaki Kobayashi
- Biological Research Laboratories, Nissan Chemical Corporation, Shiraoka, Saitama 349-0294, Japan
| | - Yoshihisa Ozoe
- Faculty of Life and Environmental Science, Shimane University, Matsue, Shimane 690-8504, Japan.
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74
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Brams M, Govaerts C, Kambara K, Price KL, Spurny R, Gharpure A, Pardon E, Evans GL, Bertrand D, Lummis SCR, Hibbs RE, Steyaert J, Ulens C. Modulation of the Erwinia ligand-gated ion channel (ELIC) and the 5-HT 3 receptor via a common vestibule site. eLife 2020; 9:e51511. [PMID: 31990273 PMCID: PMC7015668 DOI: 10.7554/elife.51511] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Accepted: 01/27/2020] [Indexed: 01/13/2023] Open
Abstract
Pentameric ligand-gated ion channels (pLGICs) or Cys-loop receptors are involved in fast synaptic signaling in the nervous system. Allosteric modulators bind to sites that are remote from the neurotransmitter binding site, but modify coupling of ligand binding to channel opening. In this study, we developed nanobodies (single domain antibodies), which are functionally active as allosteric modulators, and solved co-crystal structures of the prokaryote (Erwinia) channel ELIC bound either to a positive or a negative allosteric modulator. The allosteric nanobody binding sites partially overlap with those of small molecule modulators, including a vestibule binding site that is not accessible in some pLGICs. Using mutagenesis, we extrapolate the functional importance of the vestibule binding site to the human 5-HT3 receptor, suggesting a common mechanism of modulation in this protein and ELIC. Thus we identify key elements of allosteric binding sites, and extend drug design possibilities in pLGICs with an accessible vestibule site.
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Affiliation(s)
- Marijke Brams
- Laboratory of Structural Neurobiology, Department of Cellular and Molecular Medicine, Faculty of Medicine, KU LeuvenLeuvenBelgium
| | - Cedric Govaerts
- Laboratory for the Structure and Function of Biological Membranes, Center for Structural Biology and Bioinformatics, Université libre de BruxellesBrusselsBelgium
| | | | - Kerry L Price
- Department of Biochemistry, University of CambridgeCambridgeUnited Kingdom
| | - Radovan Spurny
- Laboratory of Structural Neurobiology, Department of Cellular and Molecular Medicine, Faculty of Medicine, KU LeuvenLeuvenBelgium
| | - Anant Gharpure
- Department of Neuroscience, University of Texas Southwestern Medical CenterDallasUnited States
- Department of Biophysics, University of Texas Southwestern Medical CenterDallasUnited States
| | - Els Pardon
- Structural Biology Brussels, Vrije Universiteit BrusselBrusselsBelgium
- VIB-VUB Center for Structural Biology, VIBBrusselsBelgium
| | - Genevieve L Evans
- Laboratory of Structural Neurobiology, Department of Cellular and Molecular Medicine, Faculty of Medicine, KU LeuvenLeuvenBelgium
| | | | - Sarah CR Lummis
- Department of Biochemistry, University of CambridgeCambridgeUnited Kingdom
| | - Ryan E Hibbs
- Department of Neuroscience, University of Texas Southwestern Medical CenterDallasUnited States
- Department of Biophysics, University of Texas Southwestern Medical CenterDallasUnited States
| | - Jan Steyaert
- Structural Biology Brussels, Vrije Universiteit BrusselBrusselsBelgium
- VIB-VUB Center for Structural Biology, VIBBrusselsBelgium
| | - Chris Ulens
- Laboratory of Structural Neurobiology, Department of Cellular and Molecular Medicine, Faculty of Medicine, KU LeuvenLeuvenBelgium
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75
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Várnai C, Irwin BWJ, Payne MC, Csányi G, Chau PL. Functional movements of the GABA type A receptor. Phys Chem Chem Phys 2020; 22:16023-16031. [DOI: 10.1039/d0cp01128b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We have performed a Monte Carlo simulation of the GABA type A receptor. We have analysed the configurations and developed a correlation tensor method to predict receptor gating.
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Affiliation(s)
- Csilla Várnai
- Centre for Computational Biology
- University of Birmingham
- Birmingham
- UK
| | - B. W. J. Irwin
- Theory of Condensed Matter Group
- Cavendish Laboratory, Department of Physics
- University of Cambridge
- Cambridge CB3 0HE
- UK
| | - M. C. Payne
- Theory of Condensed Matter Group
- Cavendish Laboratory, Department of Physics
- University of Cambridge
- Cambridge CB3 0HE
- UK
| | - Gábor Csányi
- Department of Engineering
- University of Cambridge
- Cambridge CB2 1PZ
- UK
| | - P.-L. Chau
- Bioinformatique Structurale
- Institut Pasteur CNRS URA 3528
- CB3I CNRS USR 3756
- 75724 Paris
- France
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76
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Kent DE, Savechenkov PY, Bruzik KS, Miller KW. Binding site location on GABA A receptors determines whether mixtures of intravenous general anaesthetics interact synergistically or additively in vivo. Br J Pharmacol 2019; 176:4760-4772. [PMID: 31454409 DOI: 10.1111/bph.14843] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2019] [Revised: 07/24/2019] [Accepted: 08/14/2019] [Indexed: 02/05/2023] Open
Abstract
BACKGROUND AND PURPOSE General anaesthetics can act on synaptic GABAA receptors by binding to one of three classes of general anaesthetic sites. Canonical drugs that bind selectively to only one class of site are etomidate, alphaxalone, and the mephobarbital derivative, R-mTFD-MPAB. We tested the hypothesis that the general anaesthetic potencies of mixtures of such site-selective agents binding to the same or to different sites would combine additively or synergistically respectively. EXPERIMENTAL APPROACH The potency of general anaesthetics individually or in combinations to cause loss of righting reflexes in tadpoles was determined, and the results were analysed using isobolographic methods. KEY RESULTS The potencies of combinations of two or three site-selective anaesthetics that all acted on a single class of site were strictly additive, regardless of which single site was involved. Combinations of two or three site-selective anaesthetics that all bound selectively to different sites always interacted synergistically. The strength of the synergy increased with the number of separate sites involved such that the percentage of each agent's EC50 required to cause anaesthesia was just 35% and 14% for two or three sites respectively. Propofol, which binds non-selectively to the etomidate and R-mTFD-MPAB sites, interacted synergistically with each of these agents. CONCLUSIONS AND IMPLICATIONS The established pharmacology of the three anaesthetic binding sites on synaptic GABAA receptors was sufficient to predict whether a mixture of anaesthetics interacted additively or synergistically to cause loss of righting reflexes in vivo. The principles established here have implications for clinical practice.
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Affiliation(s)
- Daniel E Kent
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital and Department of Anaesthesia, Harvard Medical School, Boston, Massachusetts.,Department of Health Sciences, Northeastern University, Boston, Massachusetts
| | | | - Karol S Bruzik
- Department of Medicinal Chemistry and Pharmacognosy, University of Illinois at Chicago, Chicago, Illinois
| | - Keith W Miller
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital and Department of Anaesthesia, Harvard Medical School, Boston, Massachusetts
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77
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Verbe J, Dubertret C, El-Hage W, Bonnet-Brilhault F, Duriez P. [GABAergic approach of postpartum depression: A translational review of literature]. Encephale 2019; 46:123-134. [PMID: 31767256 DOI: 10.1016/j.encep.2019.09.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2019] [Revised: 09/22/2019] [Accepted: 09/28/2019] [Indexed: 01/22/2023]
Abstract
INTRODUCTION Prevalence of postpartum depression (PPD) ranges from 10 to 15 % of parturients. The impact of the PPD is major on the maternal bond and the health of both mother and child. Its physiopathological mechanisms appear to differ from other types of depression. Today, pharmacotherapy is based on nonspecific treatment, and recent therapeutic advances in this field require a comprehensive approach of the implication of the GABAergic system in the development of PPD. Neurosteroid levels during pregnancy and after parturition and the GABA-A-r modulation are thought to be involved in PPD. OBJECTIVE To evaluate if the GABAergic approach is relevant in postpartum depression management. METHODS We conducted a systematic review of literature based on the MEDLINE database with the following Medical Subject Headings (MeSH): "postpartum depression", "GABA", "ganaxolone", "brexanolone", "allopregnanolone", prior to September 2019. We selected articles in English: preclinical and clinical studies, literature review, observational and therapeutic studies. RESULTS Preclinical models (mouse and rat) show changes in GABAergic inhibition in the peripartum period and correlation between allopregnanolone and GABA-A-r plasticity. This plasticity in the peripartum period maintains levels of inhibition adapted despite increased neurosteroid levels. KO models for the GABA-A-r δ subunit develop depression and anxiety symptoms in the postpartum period, and a change in the expression of the gene coding for the GABA-R alpha-4 subunit was found. Artificial inhibition of progesterone metabolism during post-partum increased depression symptoms. GABAergic fluctuation seems to be interrelated with other systems such as those of oxytocins. A synthetic neurosteroid (SGE-516) was tested on mouse models of PPD, KO for δ-GABA-A-r or KCC2, and showed decreased depressive symptoms and better mothering. Clinical studies confirm neurosteroid fluctuation and changes in the GABAergic system during the peripartum period. Allopregnanolone is the neurosteroid the most studied in PPD, and it is elevated in the brain during the pregnancy. Studies disagree on the presence of significant differences in allopregnanolone plasma levels during pregnancy or postpartum between women with PPD or not. Women with a history of PPD have greater susceptibility to neurosteroid withdrawal. Imagery and genetical data also show a link between allopregnanolone and PPD. The GABA-A-r may not recover in time following a reduced number during pregnancy, and this mismatch between neurosteroid levels and their receptor may trigger PPD. Several randomized controlled trials investigated brexanolone administrated IV, a synthetic formulation of allopregnanolone, and demonstrated a rapid and well tolerated reduction in depressive symptoms. In March 2019 brexanolone obtained FDA approval in PPD indication under the name Zulresso. However, there are differences in the time of beginning of PPD, which could constitute different subgroups of this disease, and which physiopathology could respond to different mechanisms. Prenatal depression does not respond to a GABAergic approach, but women without any risk factor or previous mood disorder developing PPD in the weeks following childbirth could be particularly responsive to this kind of treatment. CONCLUSION Disability to modulate GABA-A-r expression during pregnancy and restore its previous state after parturition appears to trigger PPD. The GABAergic system is a promising pharmacotherapy target. From preclinical to clinical studies for about twenty years the GABAergic system has been incriminated and targeted in this challenging mental disease.
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Affiliation(s)
- J Verbe
- Pôle de psychiatrie addictologie, clinique psychiatrique universitaire, CHRU de Tours, Tours, France
| | - C Dubertret
- Hôpital Louis-Mourier, AP-HP, Paris, France; Inserm 1266, institut de psychiatrie et de neurosciences de Paris, Paris, France
| | - W El-Hage
- Pôle de psychiatrie addictologie, clinique psychiatrique universitaire, CHRU de Tours, Tours, France
| | - F Bonnet-Brilhault
- Pôle de pédopsychiatrie, centre universitaire de pédopsychiatrie, CHRU de Tours, Tours, France
| | - P Duriez
- Inserm 1266, institut de psychiatrie et de neurosciences de Paris, Paris, France; Clinique des maladies mentales et de l'encéphale, GHU Paris psychiatrie et neurosciences, Paris, France.
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78
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Maramai S, Benchekroun M, Ward SE, Atack JR. Subtype Selective γ-Aminobutyric Acid Type A Receptor (GABAAR) Modulators Acting at the Benzodiazepine Binding Site: An Update. J Med Chem 2019; 63:3425-3446. [DOI: 10.1021/acs.jmedchem.9b01312] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Samuele Maramai
- Sussex Drug Discovery Centre, University of Sussex, Brighton BN1 9QJ, U.K
| | - Mohamed Benchekroun
- Sussex Drug Discovery Centre, University of Sussex, Brighton BN1 9QJ, U.K
- Équipe de Chimie Moléculaire, Laboratoire de Génomique Bioinformatique et Chimie Moléculaire, GBCM, EA7528, Conservatoire National des Arts et Métiers, 2 rue Conté, 75003 Paris, France
| | - Simon E. Ward
- Medicines Discovery Institute, Cardiff University, Main Building, Park Place, Cardiff CF10 3AT, U.K
| | - John R. Atack
- Medicines Discovery Institute, Cardiff University, Main Building, Park Place, Cardiff CF10 3AT, U.K
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79
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Tong A, Petroff JT, Hsu FF, Schmidpeter PA, Nimigean CM, Sharp L, Brannigan G, Cheng WW. Direct binding of phosphatidylglycerol at specific sites modulates desensitization of a ligand-gated ion channel. eLife 2019; 8:50766. [PMID: 31724949 PMCID: PMC6855808 DOI: 10.7554/elife.50766] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Accepted: 10/09/2019] [Indexed: 12/31/2022] Open
Abstract
Pentameric ligand-gated ion channels (pLGICs) are essential determinants of synaptic transmission, and are modulated by specific lipids including anionic phospholipids. The exact modulatory effect of anionic phospholipids in pLGICs and the mechanism of this effect are not well understood. Using native mass spectrometry, coarse-grained molecular dynamics simulations and functional assays, we show that the anionic phospholipid, 1-palmitoyl-2-oleoyl phosphatidylglycerol (POPG), preferentially binds to and stabilizes the pLGIC, Erwinia ligand-gated ion channel (ELIC), and decreases ELIC desensitization. Mutations of five arginines located in the interfacial regions of the transmembrane domain (TMD) reduce POPG binding, and a subset of these mutations increase ELIC desensitization. In contrast, a mutation that decreases ELIC desensitization, increases POPG binding. The results support a mechanism by which POPG stabilizes the open state of ELIC relative to the desensitized state by direct binding at specific sites.
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Affiliation(s)
- Ailing Tong
- Department of Anesthesiology, Washington University, Saint Louis, United States
| | - John T Petroff
- Department of Anesthesiology, Washington University, Saint Louis, United States
| | - Fong-Fu Hsu
- Department of Internal Medicine, Mass Spectrometry Resource, Division of Endocrinology, Diabetes, Metabolism, and Lipid Research, Washington University, Saint Louis, United States
| | | | - Crina M Nimigean
- Department of Anesthesiology, Weill Cornell Medical College, New York, United States
| | - Liam Sharp
- Center for Computational and Integrative Biology, Rutgers University, Camden, United States
| | - Grace Brannigan
- Center for Computational and Integrative Biology, Rutgers University, Camden, United States.,Department of Physics, Rutgers University, Camden, United States
| | - Wayland Wl Cheng
- Department of Anesthesiology, Washington University, Saint Louis, United States
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80
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Liao M, Kundap U, Rosch RE, Burrows DRW, Meyer MP, Ouled Amar Bencheikh B, Cossette P, Samarut É. Targeted knockout of GABA-A receptor gamma 2 subunit provokes transient light-induced reflex seizures in zebrafish larvae. Dis Model Mech 2019; 12:dmm.040782. [PMID: 31582559 PMCID: PMC6899022 DOI: 10.1242/dmm.040782] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Accepted: 09/24/2019] [Indexed: 12/29/2022] Open
Abstract
Epilepsy is a common primary neurological disorder characterized by the chronic tendency of a patient to experience epileptic seizures, which are abnormal body movements or cognitive states that result from excessive, hypersynchronous brain activity. Epilepsy has been found to have numerous etiologies and, although about two-thirds of epilepsies were classically considered idiopathic, the majority of those are now believed to be of genetic origin. Mutations in genes involved in gamma-aminobutyric acid (GABA)-mediated inhibitory neurotransmission have been associated with a broad range of epilepsy syndromes. Mutations in the GABA-A receptor gamma 2 subunit gene (GABRG2), for example, have been associated with absence epilepsy and febrile seizures in humans. Several rodent models of GABRG2 loss of function depict clinical features of the disease; however, alternative genetic models more amenable for the study of ictogenesis and for high-throughput screening purposes are still needed. In this context, we generated a gabrg2 knockout (KO) zebrafish model (which we called R23X) that displayed light/dark-induced reflex seizures. Through high-resolution in vivo calcium imaging of the brain, we showed that this phenotype is associated with widespread increases in neuronal activity that can be effectively alleviated by the anti-epileptic drug valproic acid. Moreover, these seizures only occur at the larval stages but disappear after 1 week of age. Interestingly, our whole-transcriptome analysis showed that gabrg2 KO does not alter the expression of genes in the larval brain. As a result, the gabrg2−/− zebrafish is a novel in vivo genetic model of early epilepsies that opens new doors to investigate ictogenesis and for further drug-screening assays. Summary: The authors present a novel in vivo genetic model of idiopathic epilepsy in zebrafish (gabrg2−/−) to aid the study of ictogenesis and provide a convenient genetic tool for drug screening.
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Affiliation(s)
- Meijiang Liao
- Research Center of the University of Montreal Hospital Center (CRCHUM), Department of Neurosciences, Université de Montréal, Montréal, QC H2X 0A9, Canada
| | - Uday Kundap
- Research Center of the University of Montreal Hospital Center (CRCHUM), Department of Neurosciences, Université de Montréal, Montréal, QC H2X 0A9, Canada
| | - Richard E Rosch
- Department for Developmental Neurobiology, MRC Centre for Neurodevelopmental Disorders, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE1 1UL, UK.,Department of Bioengineering, University of Pennsylvania, Philadelphia, PA 19104, USA.,Department of Paediatric Neurology, Great Ormond Street Hospital for Children NHS Foundation Trust, London WC1N 3JH, UK
| | - Dominic R W Burrows
- Department for Developmental Neurobiology, MRC Centre for Neurodevelopmental Disorders, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE1 1UL, UK
| | - Martin P Meyer
- Department for Developmental Neurobiology, MRC Centre for Neurodevelopmental Disorders, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE1 1UL, UK.,Department for Developmental Neurobiology, Centre for Developmental Neurobiology, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE1 1UL, UK
| | - Bouchra Ouled Amar Bencheikh
- Montreal Neurological Institute and Hospital, McGill University, Montréal, QC H3A 2B4, Canada.,Neuroscience Department, Centre de Recherche, Centre Hospitalier de l'Université de Montréal, Montréal, QC H2X 0A9, Canada
| | - Patrick Cossette
- Research Center of the University of Montreal Hospital Center (CRCHUM), Department of Neurosciences, Université de Montréal, Montréal, QC H2X 0A9, Canada
| | - Éric Samarut
- Research Center of the University of Montreal Hospital Center (CRCHUM), Department of Neurosciences, Université de Montréal, Montréal, QC H2X 0A9, Canada .,Modelis Inc., Montréal, QC H2X 0A9, Canada
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81
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Zorumski CF, Paul SM, Covey DF, Mennerick S. Neurosteroids as novel antidepressants and anxiolytics: GABA-A receptors and beyond. Neurobiol Stress 2019; 11:100196. [PMID: 31649968 PMCID: PMC6804800 DOI: 10.1016/j.ynstr.2019.100196] [Citation(s) in RCA: 78] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Accepted: 09/24/2019] [Indexed: 01/22/2023] Open
Abstract
The recent FDA approval of the neurosteroid, brexanolone (allopregnanolone), as a treatment for women with postpartum depression, and successful trials of a related neuroactive steroid, SGE-217, for men and women with major depressive disorder offer the hope of a new era in treating mood and anxiety disorders based on the potential of neurosteroids as modulators of brain function. This review considers potential mechanisms contributing to antidepressant and anxiolytic effects of allopregnanolone and other GABAergic neurosteroids focusing on their actions as positive allosteric modulators of GABAA receptors. We also consider their roles as endogenous "stress" modulators and possible additional mechanisms contributing to their therapeutic effects. We argue that further understanding of the molecular, cellular, network and psychiatric effects of neurosteroids offers the hope of further advances in the treatment of mood and anxiety disorders.
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Affiliation(s)
- Charles F. Zorumski
- Department of Psychiatry, Washington University School of Medicine, St. Louis, MO, USA
- Department of Neuroscience, Washington University School of Medicine, St. Louis, MO, USA
- The Taylor Family Institute for Innovative Psychiatric Research, Washington University School of Medicine, St. Louis, MO, USA
| | - Steven M. Paul
- Department of Psychiatry, Washington University School of Medicine, St. Louis, MO, USA
- Department of Neurology, Washington University School of Medicine, St. Louis, MO, USA
- The Taylor Family Institute for Innovative Psychiatric Research, Washington University School of Medicine, St. Louis, MO, USA
| | - Douglas F. Covey
- Department of Psychiatry, Washington University School of Medicine, St. Louis, MO, USA
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO, USA
- The Taylor Family Institute for Innovative Psychiatric Research, Washington University School of Medicine, St. Louis, MO, USA
| | - Steven Mennerick
- Department of Psychiatry, Washington University School of Medicine, St. Louis, MO, USA
- Department of Neuroscience, Washington University School of Medicine, St. Louis, MO, USA
- The Taylor Family Institute for Innovative Psychiatric Research, Washington University School of Medicine, St. Louis, MO, USA
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82
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Hénault CM, Govaerts C, Spurny R, Brams M, Estrada-Mondragon A, Lynch J, Bertrand D, Pardon E, Evans GL, Woods K, Elberson BW, Cuello LG, Brannigan G, Nury H, Steyaert J, Baenziger JE, Ulens C. A lipid site shapes the agonist response of a pentameric ligand-gated ion channel. Nat Chem Biol 2019; 15:1156-1164. [PMID: 31591563 DOI: 10.1038/s41589-019-0369-4] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2018] [Accepted: 08/21/2019] [Indexed: 12/11/2022]
Abstract
Phospholipids are key components of cellular membranes and are emerging as important functional regulators of different membrane proteins, including pentameric ligand-gated ion channels (pLGICs). Here, we take advantage of the prokaryote channel ELIC (Erwinia ligand-gated ion channel) as a model to understand the determinants of phospholipid interactions in this family of receptors. A high-resolution structure of ELIC in a lipid-bound state reveals a phospholipid site at the lower half of pore-forming transmembrane helices M1 and M4 and at a nearby site for neurosteroids, cholesterol or general anesthetics. This site is shaped by an M4-helix kink and a Trp-Arg-Pro triad that is highly conserved in eukaryote GABAA/C and glycine receptors. A combined approach reveals that M4 is intrinsically flexible and that M4 deletions or disruptions of the lipid-binding site accelerate desensitization in ELIC, suggesting that lipid interactions shape the agonist response. Our data offer a structural context for understanding lipid modulation in pLGICs.
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Affiliation(s)
- Camille M Hénault
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Ontario, Canada
| | - Cedric Govaerts
- Laboratory for the Structure and Function of Biological Membranes, Center for Structural Biology and Bioinformatics, Université libre de Bruxelles, Brussels, Belgium
| | - Radovan Spurny
- Laboratory of Structural Neurobiology, Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
| | - Marijke Brams
- Laboratory of Structural Neurobiology, Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
| | | | - Joseph Lynch
- Queensland Brain Institute, University of Queensland, Brisbane, Queensland, Australia
| | | | - Els Pardon
- Structural Biology Brussels, Vrije Universiteit Brussel, Brussels, Belgium.,VIB-VUB Center for Structural Biology, VIB, Brussels, Belgium
| | - Genevieve L Evans
- Laboratory of Structural Neurobiology, Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
| | - Kristen Woods
- Center for Computational and Integrative Biology, Rutgers University-Camden, Camden, NJ, USA.,Department of Physics, Rutgers University-Camden, Camden, NJ, USA
| | - Benjamin W Elberson
- Department of Cell Physiology and Molecular Biophysics, Center for Membrane Protein Research, TTUHSC, Lubbock, TX, USA
| | - Luis G Cuello
- Department of Cell Physiology and Molecular Biophysics, Center for Membrane Protein Research, TTUHSC, Lubbock, TX, USA
| | - Grace Brannigan
- Center for Computational and Integrative Biology, Rutgers University-Camden, Camden, NJ, USA.,Department of Physics, Rutgers University-Camden, Camden, NJ, USA
| | - Hugues Nury
- University Grenoble Alpes, CNRS, IBS, Grenoble, France
| | - Jan Steyaert
- Structural Biology Brussels, Vrije Universiteit Brussel, Brussels, Belgium.,VIB-VUB Center for Structural Biology, VIB, Brussels, Belgium
| | - John E Baenziger
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Ontario, Canada.
| | - Chris Ulens
- Laboratory of Structural Neurobiology, Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium.
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83
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Duncan AL, Song W, Sansom MSP. Lipid-Dependent Regulation of Ion Channels and G Protein-Coupled Receptors: Insights from Structures and Simulations. Annu Rev Pharmacol Toxicol 2019; 60:31-50. [PMID: 31506010 DOI: 10.1146/annurev-pharmtox-010919-023411] [Citation(s) in RCA: 94] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Ion channels and G protein-coupled receptors (GPCRs) are regulated by lipids in their membrane environment. Structural studies combined with biophysical and molecular simulation investigations reveal interaction sites for specific lipids on membrane protein structures. For K channels, PIP2 plays a key role in regulating Kv and Kir channels. Likewise, several recent cryo-EM structures of TRP channels have revealed bound lipids, including PIP2 and cholesterol. Among the pentameric ligand-gated ion channel family, structural and biophysical studies suggest the M4 TM helix may act as a lipid sensor, e.g., forming part of the binding sites for neurosteroids on the GABAA receptor. Structures of GPCRs have revealed multiple cholesterol sites, which may modulate both receptor dynamics and receptor oligomerization. PIP2 also interacts with GPCRs and may modulate their interactions with G proteins. Overall, it is evident that multiple lipid binding sites exist on channels and receptors that modulate their function allosterically and are potential druggable sites.
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Affiliation(s)
- Anna L Duncan
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, United Kingdom;
| | - Wanling Song
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, United Kingdom;
| | - Mark S P Sansom
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, United Kingdom;
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84
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Sugasawa Y, Bracamontes JR, Krishnan K, Covey DF, Reichert DE, Akk G, Chen Q, Tang P, Evers AS, Cheng WWL. The molecular determinants of neurosteroid binding in the GABA(A) receptor. J Steroid Biochem Mol Biol 2019; 192:105383. [PMID: 31150831 PMCID: PMC6708749 DOI: 10.1016/j.jsbmb.2019.105383] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/26/2019] [Revised: 05/11/2019] [Accepted: 05/26/2019] [Indexed: 10/26/2022]
Abstract
Neurosteroids positively modulate GABA-A receptor (GABAAR) channel activity by binding to a transmembrane domain intersubunit site. Understanding the interactions in this site that determine neurosteroid binding and its effect is essential for the design of neurosteroid-based therapeutics. Using photo-affinity labeling and an ELIC-α1GABAAR chimera, we investigated the impact of mutations (Q242L, Q242W and W246L) within the intersubunit site on neurosteroid binding. These mutations, which abolish the thermal stabilizing effect of allopregnanolone on the chimera, reduce neither photolabeling within the intersubunit site nor competitive prevention of labeling by allopregnanolone. Instead, these mutations change the orientation of neurosteroid photolabeling. Molecular docking of allopregnanolone in WT and Q242W receptors confirms that the mutation favors re-orientation of allopregnanolone within the binding pocket. Collectively, the data indicate that mutations at Gln242 or Trp246 that eliminate neurosteroid effects do not eliminate neurosteroid binding within the intersubunit site, but significantly alter the preferred orientation of the neurosteroid within the site. The interactions formed by Gln242 and Trp246 within this pocket play a vital role in determining the orientation of the neurosteroid that may be necessary for its functional effect.
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Affiliation(s)
- Yusuke Sugasawa
- Department of Anesthesiology, Washington University in St. Louis, St. Louis, MO 63110, USA.
| | - John R Bracamontes
- Department of Anesthesiology, Washington University in St. Louis, St. Louis, MO 63110, USA.
| | - Kathiresan Krishnan
- Department of Developmental Biology, Washington University in St. Louis, St. Louis, MO 63110, USA.
| | - Douglas F Covey
- Department of Anesthesiology, Washington University in St. Louis, St. Louis, MO 63110, USA; Department of Developmental Biology, Washington University in St. Louis, St. Louis, MO 63110, USA; Department of Psychiatry, Washington University in St. Louis, St. Louis, MO 63110, USA; Taylor Family Institute for Innovative Psychiatric Research, Washington University in St. Louis, St. Louis, MO 63110, USA.
| | - David E Reichert
- Department of Radiology, Washington University in St. Louis, St. Louis, MO 63110, USA; Taylor Family Institute for Innovative Psychiatric Research, Washington University in St. Louis, St. Louis, MO 63110, USA.
| | - Gustav Akk
- Department of Anesthesiology, Washington University in St. Louis, St. Louis, MO 63110, USA; Taylor Family Institute for Innovative Psychiatric Research, Washington University in St. Louis, St. Louis, MO 63110, USA.
| | - Qiang Chen
- Department of Anesthesiology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15260, USA.
| | - Pei Tang
- Department of Anesthesiology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15260, USA; Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15260, USA; Department of Computational and Systems Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15260, USA.
| | - Alex S Evers
- Department of Anesthesiology, Washington University in St. Louis, St. Louis, MO 63110, USA; Department of Developmental Biology, Washington University in St. Louis, St. Louis, MO 63110, USA; Taylor Family Institute for Innovative Psychiatric Research, Washington University in St. Louis, St. Louis, MO 63110, USA.
| | - Wayland W L Cheng
- Department of Anesthesiology, Washington University in St. Louis, St. Louis, MO 63110, USA.
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85
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Kasaragod VB, Schindelin H. Structure of Heteropentameric GABA A Receptors and Receptor-Anchoring Properties of Gephyrin. Front Mol Neurosci 2019; 12:191. [PMID: 31440140 PMCID: PMC6693554 DOI: 10.3389/fnmol.2019.00191] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Accepted: 07/22/2019] [Indexed: 12/20/2022] Open
Abstract
γ-Aminobutyric acid type A receptors (GABAARs) mediate the majority of fast synaptic inhibition in the central nervous system (CNS). GABAARs belong to the Cys-loop superfamily of pentameric ligand-gated ion channels (pLGIC) and are assembled from 19 different subunits. As dysfunctional GABAergic neurotransmission manifests itself in neurodevelopmental disorders including epilepsy and anxiety, GABAARs are key drug targets. The majority of synaptic GABAARs are anchored at the inhibitory postsynaptic membrane by the principal scaffolding protein gephyrin, which acts as the central organizer in maintaining the architecture of the inhibitory postsynaptic density (iPSD). This interaction is mediated by the long intracellular loop located in between transmembrane helices 3 and 4 (M3–M4 loop) of the receptors and a universal receptor-binding pocket residing in the C-terminal domain of gephyrin. In 2014, the crystal structure of the β3-homopentameric GABAAR provided crucial information regarding the architecture of the receptor; however, an understanding of the structure and assembly of heteropentameric receptors at the atomic level was lacking. This review article will highlight recent advances in understanding the structure of heteropentameric synaptic GABAARs and how these structures have provided fundamental insights into the assembly of these multi-subunit receptors as well as their modulation by diverse ligands including the physiological agonist GABA. We will further discuss the role of gephyrin in the anchoring of synaptic GABAARs and glycine receptors (GlyRs), which are crucial for maintaining the architecture of the iPSD. Finally, we will also summarize how anti-malarial artemisinin drugs modulate gephyrin-mediated inhibitory neurotransmission.
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Affiliation(s)
- Vikram Babu Kasaragod
- Institute of Structural Biology, Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, Würzburg, Germany
| | - Hermann Schindelin
- Institute of Structural Biology, Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, Würzburg, Germany
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86
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García-Nafría J, Tate CG. Cryo-Electron Microscopy: Moving Beyond X-Ray Crystal Structures for Drug Receptors and Drug Development. Annu Rev Pharmacol Toxicol 2019; 60:51-71. [PMID: 31348870 DOI: 10.1146/annurev-pharmtox-010919-023545] [Citation(s) in RCA: 68] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Electron cryo-microscopy (cryo-EM) has revolutionized structure determination of membrane proteins and holds great potential for structure-based drug discovery. Here we discuss the potential of cryo-EM in the rational design of therapeutics for membrane proteins compared to X-ray crystallography. We also detail recent progress in the field of drug receptors, focusing on cryo-EM of two protein families with established therapeutic value, the γ-aminobutyric acid A receptors (GABAARs) and G protein-coupled receptors (GPCRs). GABAARs are pentameric ion channels, and cryo-EM structures of physiological heteromeric receptors in a lipid environment have uncovered the molecular basis of receptor modulation by drugs such as diazepam. The structures of ten GPCR-G protein complexes from three different classes of GPCRs have now been determined by cryo-EM. These structures give detailed insights into molecular interactions with drugs, GPCR-G protein selectivity, how accessory membrane proteins alter receptor-ligand pharmacology, and the mechanism by which HIV uses GPCRs to enter host cells.
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Affiliation(s)
- Javier García-Nafría
- MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, United Kingdom; .,Current affiliation: Institute for Biocomputation and Physics of Complex Systems (BIFI) and Laboratorio de Microscopias Avanzadas, University of Zaragoza, 50018 Zaragoza, Spain;
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87
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Oliveira ASF, Shoemark DK, Campello HR, Wonnacott S, Gallagher T, Sessions RB, Mulholland AJ. Identification of the Initial Steps in Signal Transduction in the α4β2 Nicotinic Receptor: Insights from Equilibrium and Nonequilibrium Simulations. Structure 2019; 27:1171-1183.e3. [PMID: 31130483 DOI: 10.1016/j.str.2019.04.008] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2018] [Revised: 01/28/2019] [Accepted: 04/10/2019] [Indexed: 02/02/2023]
Abstract
Nicotinic acetylcholine receptors (nAChRs) modulate synaptic transmission in the nervous system. These receptors have emerged as therapeutic targets in drug discovery for treating several conditions, including Alzheimer's disease, pain, and nicotine addiction. In this in silico study, we use a combination of equilibrium and nonequilibrium molecular dynamics simulations to map dynamic and structural changes induced by nicotine in the human α4β2 nAChR. They reveal a striking pattern of communication between the extracellular binding pockets and the transmembrane domains (TMDs) and show the sequence of conformational changes associated with the initial steps in this process. We propose a general mechanism for signal transduction for Cys-loop receptors: the mechanistic steps for communication proceed firstly through loop C in the principal subunit, and are subsequently transmitted, gradually and cumulatively, to loop F of the complementary subunit, and then to the TMDs through the M2-M3 linker.
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Affiliation(s)
- A Sofia F Oliveira
- School of Biochemistry, University of Bristol, Bristol BS8 1DT, UK; Centre for Computational Chemistry, School of Chemistry, University of Bristol, Bristol BS8 1TS, UK
| | | | - Hugo Rego Campello
- Centre for Computational Chemistry, School of Chemistry, University of Bristol, Bristol BS8 1TS, UK
| | - Susan Wonnacott
- Department of Biology and Biochemistry, University of Bath, Bath BA2 7AY, UK
| | - Timothy Gallagher
- Centre for Computational Chemistry, School of Chemistry, University of Bristol, Bristol BS8 1TS, UK
| | | | - Adrian J Mulholland
- Centre for Computational Chemistry, School of Chemistry, University of Bristol, Bristol BS8 1TS, UK.
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88
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Al-Harrasi A, Khan A, Rehman NU, Al-Shidhani S, Karim N, Khan I, Halim SA, Al-Rawahi A, Hussain J, Csuk R. Evidence for the involvement of a GABAergic mechanism in the effectiveness of natural and synthetically modified incensole derivatives in neuropharmacological disorders: A computational and pharmacological approach. PHYTOCHEMISTRY 2019; 163:58-74. [PMID: 31015070 DOI: 10.1016/j.phytochem.2019.04.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2018] [Revised: 03/19/2019] [Accepted: 04/14/2019] [Indexed: 06/09/2023]
Abstract
In the course of our continuing exploration for novel bioactive lead compounds (s) from the species Boswellia, we have recently reported incensole derivatives isolated from Boswellia papyrifera Hochst. Given the known antidepressant-like effects of incensole and incensole acetate, we herein present that the low dose intraperitoneal administration of incensole derivatives, namely, incensfuran and incensone, showed significant antidepressant-like effects in the forced swim test (FST) and tail suspension test (TST). Furthermore, these compounds were evaluated for their anxiolytic potential in the elevated plus maze (EPM) and light dark box (LDB) tests and anticonvulsant effects in pentylenetetrazole (PTZ)-induced seizure tests. In the EPM test, administration of these compounds led to dose-dependent increases in open arm entries and in the time spent in EPM open arms. Similar results were obtained in the LDB test, wherein compounds these caused significant increases in the number of transitions between lit and dark compartments and the time spent in the lit compartment. The anxiolytic-like effects in the EPM were not reversed by pretreatment with flumazenil, whereas PTZ and bicuculline (BIC) completely abolished the anxiolytic effects, showing the involvement of the non-benzodiazepine binding sites of GABAA receptors. All four compounds induced significantly elevated brain GABA levels, indicating the involvement of a GABAergic mechanism. Additionally, molecular docking was conducted to elucidate the mode of action for the anxiolytic and anticonvulsant effects of these derivatives. Moreover, these compounds also possess drug-like properties and excellent ADMET profiles.
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Affiliation(s)
- Ahmed Al-Harrasi
- Natural and Medical Sciences Research Center, University of Nizwa, PO Box 33, 616 Birkat Al Mauz, Nizwa, Oman.
| | - Ajmal Khan
- Natural and Medical Sciences Research Center, University of Nizwa, PO Box 33, 616 Birkat Al Mauz, Nizwa, Oman
| | - Najeeb Ur Rehman
- Natural and Medical Sciences Research Center, University of Nizwa, PO Box 33, 616 Birkat Al Mauz, Nizwa, Oman
| | - Sulaiman Al-Shidhani
- Natural and Medical Sciences Research Center, University of Nizwa, PO Box 33, 616 Birkat Al Mauz, Nizwa, Oman
| | - Nasiara Karim
- Department of Pharmacy, University of Malakand, Chakdara, Dir (Lower), KPK, Pakistan
| | - Imran Khan
- Department of Pharmacy, University of Swabi, KPK, Pakistan; Department of Biochemistry, Kinnaird College for Women, 93-Jail Road, Lahore, 53700, Pakistan
| | - Sobia Ahsan Halim
- Natural and Medical Sciences Research Center, University of Nizwa, PO Box 33, 616 Birkat Al Mauz, Nizwa, Oman
| | - Ahmed Al-Rawahi
- Natural and Medical Sciences Research Center, University of Nizwa, PO Box 33, 616 Birkat Al Mauz, Nizwa, Oman
| | - Javid Hussain
- Natural and Medical Sciences Research Center, University of Nizwa, PO Box 33, 616 Birkat Al Mauz, Nizwa, Oman
| | - Rene Csuk
- Martin-Luther-University Halle-Wittenberg, Organic Chemistry, Kurt-Mothes-Str. 2, D-06120 Halle (Saale) Germany
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89
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Khayenko V, Maric HM. Targeting GABA AR-Associated Proteins: New Modulators, Labels and Concepts. Front Mol Neurosci 2019; 12:162. [PMID: 31293385 PMCID: PMC6606717 DOI: 10.3389/fnmol.2019.00162] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2019] [Accepted: 06/12/2019] [Indexed: 12/21/2022] Open
Abstract
γ-aminobutyric acid type A receptors (GABAARs) are the major mediators of synaptic inhibition in the brain. Aberrant GABAAR activity or regulation is observed in various neurodevelopmental disorders, neurodegenerative diseases and mental illnesses, including epilepsy, Alzheimer’s and schizophrenia. Benzodiazepines, anesthetics and other pharmaceutics targeting these receptors find broad clinical use, but their inherent lack of receptor subtype specificity causes unavoidable side effects, raising a need for new or adjuvant medications. In this review article, we introduce a new strategy to modulate GABAeric signaling: targeting the intracellular protein interactors of GABAARs. Of special interest are scaffolding, anchoring and supporting proteins that display high GABAAR subtype specificity. Recent efforts to target gephyrin, the major intracellular integrator of GABAergic signaling, confirm that GABAAR-associated proteins can be successfully targeted through diverse molecules, including recombinant proteins, intrabodies, peptide-based probes and small molecules. Small-molecule artemisinins and peptides derived from endogenous interactors, that specifically target the universal receptor binding site of gephyrin, acutely affect synaptic GABAAR numbers and clustering, modifying neuronal transmission. Interference with GABAAR trafficking provides another way to modulate inhibitory signaling. Peptides blocking the binding site of GABAAR to AP2 increase the surface concentration of GABAAR clusters and enhance GABAergic signaling. Engineering of gephyrin binding peptides delivered superior means to interrogate neuronal structure and function. Fluorescent peptides, designed from gephyrin binders, enable live neuronal staining and visualization of gephyrin in the post synaptic sites with submicron resolution. We anticipate that in the future, novel fluorescent probes, with improved size and binding efficiency, may find wide application in super resolution microscopy studies, enlightening the nanoscale architecture of the inhibitory synapse. Broader studies on GABAAR accessory proteins and the identification of the exact molecular binding interfaces and affinities will advance the development of novel GABAAR modulators and following in vivo studies will reveal their clinical potential as adjuvant or stand-alone drugs.
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Affiliation(s)
- Vladimir Khayenko
- Institute of Structural Biology, Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, Würzburg, Germany.,Department of Biotechnology and Biophysics, Biocenter, University of Würzburg, Würzburg, Germany
| | - Hans Michael Maric
- Institute of Structural Biology, Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, Würzburg, Germany.,Department of Biotechnology and Biophysics, Biocenter, University of Würzburg, Würzburg, Germany
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90
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Lüscher B, Möhler H. Brexanolone, a neurosteroid antidepressant, vindicates the GABAergic deficit hypothesis of depression and may foster resilience. F1000Res 2019; 8. [PMID: 31275559 PMCID: PMC6544078 DOI: 10.12688/f1000research.18758.1] [Citation(s) in RCA: 53] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 05/22/2019] [Indexed: 12/18/2022] Open
Abstract
The GABAergic deficit hypothesis of depression states that a deficit of GABAergic transmission in defined neural circuits is causal for depression. Conversely, an enhancement of GABA transmission, including that triggered by selective serotonin reuptake inhibitors or ketamine, has antidepressant effects. Brexanolone, an intravenous formulation of the endogenous neurosteroid allopregnanolone, showed clinically significant antidepressant activity in postpartum depression. By allosterically enhancing GABA
A receptor function, the antidepressant activity of allopregnanolone is attributed to an increase in GABAergic inhibition. In addition, allopregnanolone may stabilize normal mood by decreasing the activity of stress-responsive dentate granule cells and thereby sustain resilience behavior. Therefore, allopregnanolone may augment and extend its antidepressant activity by fostering resilience. The recent structural resolution of the neurosteroid binding domain of GABA
A receptors will expedite the development of more selective ligands as a potential new class of central nervous system drugs.
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Affiliation(s)
- Bernhard Lüscher
- Department of Biology and Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, PA, 16802, USA.,Center for Molecular Investigation of Neurological Disorders, The Huck Institutes for the Life Sciences, Pennsylvania State University, University Park, PA, 16802, USA
| | - Hanns Möhler
- Institute of Pharmacology and Neuroscience Center, University of Zurich, Zurich, 8057, Switzerland.,Department of Chemistry and Applied Biosciences, Swiss Federal Institute of Technology (ETH), Zurich, 8057, Switzerland
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91
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Hemmings HC, Riegelhaupt PM, Kelz MB, Solt K, Eckenhoff RG, Orser BA, Goldstein PA. Towards a Comprehensive Understanding of Anesthetic Mechanisms of Action: A Decade of Discovery. Trends Pharmacol Sci 2019; 40:464-481. [PMID: 31147199 DOI: 10.1016/j.tips.2019.05.001] [Citation(s) in RCA: 118] [Impact Index Per Article: 23.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Revised: 04/11/2019] [Accepted: 05/03/2019] [Indexed: 12/30/2022]
Abstract
Significant progress has been made in the 21st century towards a comprehensive understanding of the mechanisms of action of general anesthetics, coincident with progress in structural biology and molecular, cellular, and systems neuroscience. This review summarizes important new findings that include target identification through structural determination of anesthetic binding sites, details of receptors and ion channels involved in neurotransmission, and the critical roles of neuronal networks in anesthetic effects on memory and consciousness. These recent developments provide a comprehensive basis for conceptualizing pharmacological control of amnesia, unconsciousness, and immobility.
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Affiliation(s)
- Hugh C Hemmings
- Departments of Anesthesiology, Weill Cornell Medicine, 1300 York Avenue, New York, NY 10065, USA; Departments of Pharmacology, Weill Cornell Medicine, 1300 York Avenue, New York, NY 10065, USA
| | - Paul M Riegelhaupt
- Departments of Anesthesiology, Weill Cornell Medicine, 1300 York Avenue, New York, NY 10065, USA
| | - Max B Kelz
- Department of Anesthesiology and Critical Care, University of Pennsylvania Perelman School of Medicine, 3620 Hamilton Walk, 305 John Morgan, Philadelphia, PA 19104, USA
| | - Ken Solt
- Department of Anaesthesia, Harvard Medical School, GRB 444, 55 Fruit St., Boston, MA 02114, USA; Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, 55 Fruit Street, Boston, MA 02114, USA
| | - Roderic G Eckenhoff
- Department of Anesthesiology and Critical Care, University of Pennsylvania Perelman School of Medicine, 3620 Hamilton Walk, 305 John Morgan, Philadelphia, PA 19104, USA
| | - Beverley A Orser
- Departments of Anesthesia and Physiology, Room 3318 Medical Sciences Building, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - Peter A Goldstein
- Departments of Anesthesiology, Weill Cornell Medicine, 1300 York Avenue, New York, NY 10065, USA; Departments of Medicine, Weill Cornell Medicine, 1300 York Avenue, New York, NY 10065, USA.
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92
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Scott S, Aricescu AR. A structural perspective on GABA A receptor pharmacology. Curr Opin Struct Biol 2019; 54:189-197. [PMID: 31129381 DOI: 10.1016/j.sbi.2019.03.023] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Revised: 03/14/2019] [Accepted: 03/19/2019] [Indexed: 10/26/2022]
Abstract
GABAA receptors are pentameric ligand-gated chloride channels of crucial importance for the vertebrate nervous system physiology. They typically modulate the fast inhibitory neurotransmission, and represent the target receptors for major classes of drugs used in the clinic, such as benzodiazepines and general anesthetics. Recent technological progress in structural biology, in particular single-particle cryo-electron microscopy, has led to fundamental advances in understanding the detailed organization and signalling mechanisms of major GABAA receptor subtypes. This effort culminated with the high-resolution structural analysis of an intact, full-length human heteropentameric receptor, α1β3γ2, in a lipid bilayer and in complex with small molecule ligands including the commonly used benzodiazepines diazepam (Valium) and alprazolam (Xanax). These structures reveal multiple aspects of receptor activation and provide a path for rational design of subunit-specific GABAA receptor modulators.
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Affiliation(s)
- Suzanne Scott
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, CB2 0QH, UK; Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, OX1 3PT, UK.
| | - Alexandru Radu Aricescu
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, CB2 0QH, UK; Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Oxford, OX3 7BN, UK.
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93
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Jayakar SS, Zhou X, Chiara DC, Jarava-Barrera C, Savechenkov PY, Bruzik KS, Tortosa M, Miller KW, Cohen JB. Identifying Drugs that Bind Selectively to Intersubunit General Anesthetic Sites in the α1 β3 γ2 GABA AR Transmembrane Domain. Mol Pharmacol 2019; 95:615-628. [PMID: 30952799 DOI: 10.1124/mol.118.114975] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2018] [Accepted: 03/29/2019] [Indexed: 12/19/2022] Open
Abstract
GABAA receptors (GABAARs) are targets for important classes of clinical agents (e.g., anxiolytics, anticonvulsants, and general anesthetics) that act as positive allosteric modulators (PAMs). Previously, using photoreactive analogs of etomidate ([3H]azietomidate) and mephobarbital [[3H]1-methyl-5-allyl-5-(m-trifluoromethyl-diazirynylphenyl)barbituric acid ([3H]R-mTFD-MPAB)], we identified two homologous but pharmacologically distinct classes of general anesthetic binding sites in the α1β3γ2 GABAAR transmembrane domain at β +-α - (β + sites) and α +-β -/γ +-β - (β - sites) subunit interfaces. We now use competition photolabeling with [3H]azietomidate and [3H]R-mTFD-MPAB to identify para-substituted propofol analogs and other drugs that bind selectively to intersubunit anesthetic sites. Propofol and 4-chloro-propofol bind with 5-fold selectivity to β +, while derivatives with bulkier lipophilic substitutions [4-(tert-butyl)-propofol and 4-(hydroxyl(phenyl)methyl)-propofol] bind with ∼10-fold higher affinity to β - sites. Similar to R-mTFD-MPAB and propofol, these drugs bind in the presence of GABA with similar affinity to the α +-β - and γ +-β - sites. However, we discovered four compounds that bind with different affinities to the two β - interface sites. Two of these bind with higher affinity to one of the β - sites than to the β + sites. We deduce that 4-benzoyl-propofol binds with >100-fold higher affinity to the γ +-β - site than to the α +-β - or β +-α - sites, whereas loreclezole, an anticonvulsant, binds with 5- and 100-fold higher affinity to the α +-β - site than to the β + and γ +-β - sites. These studies provide a first identification of PAMs that bind selectively to a single intersubunit site in the GABAAR transmembrane domain, a property that may facilitate the development of subtype selective GABAAR PAMs.
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Affiliation(s)
- Selwyn S Jayakar
- Department of Neurobiology, Harvard Medical School, Boston, Massachusetts (S.S.J., D.C.C., J.B.C.); Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, Massachusetts (X.Z., K.W.M.); Department of Medicinal Chemistry and Pharmacognosy, University of Illinois at Chicago, Chicago, Illinois (P.Y.S., K.S.B.); and the Departamento de Quimica Orgánica, Universidad Autónoma de Madrid, Madrid, Spain (C.J.-B., M.T.)
| | - Xiaojuan Zhou
- Department of Neurobiology, Harvard Medical School, Boston, Massachusetts (S.S.J., D.C.C., J.B.C.); Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, Massachusetts (X.Z., K.W.M.); Department of Medicinal Chemistry and Pharmacognosy, University of Illinois at Chicago, Chicago, Illinois (P.Y.S., K.S.B.); and the Departamento de Quimica Orgánica, Universidad Autónoma de Madrid, Madrid, Spain (C.J.-B., M.T.)
| | - David C Chiara
- Department of Neurobiology, Harvard Medical School, Boston, Massachusetts (S.S.J., D.C.C., J.B.C.); Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, Massachusetts (X.Z., K.W.M.); Department of Medicinal Chemistry and Pharmacognosy, University of Illinois at Chicago, Chicago, Illinois (P.Y.S., K.S.B.); and the Departamento de Quimica Orgánica, Universidad Autónoma de Madrid, Madrid, Spain (C.J.-B., M.T.)
| | - Carlos Jarava-Barrera
- Department of Neurobiology, Harvard Medical School, Boston, Massachusetts (S.S.J., D.C.C., J.B.C.); Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, Massachusetts (X.Z., K.W.M.); Department of Medicinal Chemistry and Pharmacognosy, University of Illinois at Chicago, Chicago, Illinois (P.Y.S., K.S.B.); and the Departamento de Quimica Orgánica, Universidad Autónoma de Madrid, Madrid, Spain (C.J.-B., M.T.)
| | - Pavel Y Savechenkov
- Department of Neurobiology, Harvard Medical School, Boston, Massachusetts (S.S.J., D.C.C., J.B.C.); Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, Massachusetts (X.Z., K.W.M.); Department of Medicinal Chemistry and Pharmacognosy, University of Illinois at Chicago, Chicago, Illinois (P.Y.S., K.S.B.); and the Departamento de Quimica Orgánica, Universidad Autónoma de Madrid, Madrid, Spain (C.J.-B., M.T.)
| | - Karol S Bruzik
- Department of Neurobiology, Harvard Medical School, Boston, Massachusetts (S.S.J., D.C.C., J.B.C.); Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, Massachusetts (X.Z., K.W.M.); Department of Medicinal Chemistry and Pharmacognosy, University of Illinois at Chicago, Chicago, Illinois (P.Y.S., K.S.B.); and the Departamento de Quimica Orgánica, Universidad Autónoma de Madrid, Madrid, Spain (C.J.-B., M.T.)
| | - Mariola Tortosa
- Department of Neurobiology, Harvard Medical School, Boston, Massachusetts (S.S.J., D.C.C., J.B.C.); Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, Massachusetts (X.Z., K.W.M.); Department of Medicinal Chemistry and Pharmacognosy, University of Illinois at Chicago, Chicago, Illinois (P.Y.S., K.S.B.); and the Departamento de Quimica Orgánica, Universidad Autónoma de Madrid, Madrid, Spain (C.J.-B., M.T.)
| | - Keith W Miller
- Department of Neurobiology, Harvard Medical School, Boston, Massachusetts (S.S.J., D.C.C., J.B.C.); Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, Massachusetts (X.Z., K.W.M.); Department of Medicinal Chemistry and Pharmacognosy, University of Illinois at Chicago, Chicago, Illinois (P.Y.S., K.S.B.); and the Departamento de Quimica Orgánica, Universidad Autónoma de Madrid, Madrid, Spain (C.J.-B., M.T.)
| | - Jonathan B Cohen
- Department of Neurobiology, Harvard Medical School, Boston, Massachusetts (S.S.J., D.C.C., J.B.C.); Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, Massachusetts (X.Z., K.W.M.); Department of Medicinal Chemistry and Pharmacognosy, University of Illinois at Chicago, Chicago, Illinois (P.Y.S., K.S.B.); and the Departamento de Quimica Orgánica, Universidad Autónoma de Madrid, Madrid, Spain (C.J.-B., M.T.)
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94
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Antkowiak B, Rammes G. GABA(A) receptor-targeted drug development -New perspectives in perioperative anesthesia. Expert Opin Drug Discov 2019; 14:683-699. [DOI: 10.1080/17460441.2019.1599356] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- Bernd Antkowiak
- Department of Anesthesiology and Intensive Care, Experimental Anesthesiology Section, Eberhard-Karls-University,
Tübingen, Germany
- Department of Anaesthesiology and Intensive Care, Experimental Anaesthesiology Section, Werner Reichardt Center for Integrative Neuroscience, Tübingen,
Germany
| | - Gerhard Rammes
- University Hospital rechts der Isar, Department of Anesthesiology, München,
Germany
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95
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Yu Z, Chiara DC, Savechenkov PY, Bruzik KS, Cohen JB. A photoreactive analog of allopregnanolone enables identification of steroid-binding sites in a nicotinic acetylcholine receptor. J Biol Chem 2019; 294:7892-7903. [PMID: 30923128 DOI: 10.1074/jbc.ra118.007172] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Revised: 03/27/2019] [Indexed: 11/06/2022] Open
Abstract
Many neuroactive steroids potently and allosterically modulate pentameric ligand-gated ion channels, including GABAA receptors (GABAAR) and nicotinic acetylcholine receptors (nAChRs). Allopregnanolone and its synthetic analog alphaxalone are GABAAR-positive allosteric modulators (PAMs), whereas alphaxalone and most neuroactive steroids are nAChR inhibitors. In this report, we used 11β-(p-azidotetrafluorobenzoyloxy)allopregnanolone (F4N3Bzoxy-AP), a general anesthetic and photoreactive allopregnanolone analog that is a potent GABAAR PAM, to characterize steroid-binding sites in the Torpedo α2βγδ nAChR in its native membrane environment. We found that F4N3Bzoxy-AP (IC50 = 31 μm) is 7-fold more potent than alphaxalone in inhibiting binding of the channel blocker [3H]tenocyclidine to nAChRs in the desensitized state. At 300 μm, neither steroid inhibited binding of [3H]tetracaine, a closed-state selective channel blocker, or of [3H]acetylcholine. Photolabeling identified three distinct [3H]F4N3Bzoxy-AP-binding sites in the nAChR transmembrane domain: 1) in the ion channel, identified by photolabeling in the M2 helices of βVal-261 and δVal-269 (position M2-13'); 2) at the interface between the αM1 and αM4 helices, identified by photolabeling in αM1 (αCys-222/αLeu-223); and 3) at the lipid-protein interface involving γTrp-453 (M4), a residue photolabeled by small lipophilic probes and promegestone, a steroid nAChR antagonist. Photolabeling in the ion channel and αM1 was higher in the nAChR-desensitized state than in the resting state and inhibitable by promegestone. These results directly indicate a steroid-binding site in the nAChR ion channel and identify additional steroid-binding sites also occupied by other lipophilic nAChR antagonists.
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Affiliation(s)
- Zhiyi Yu
- From the Department of Neurobiology, Harvard Medical School, Boston, Massachusetts 02115 and
| | - David C Chiara
- From the Department of Neurobiology, Harvard Medical School, Boston, Massachusetts 02115 and
| | - Pavel Y Savechenkov
- the Department of Medicinal Chemistry and Pharmacognosy, University of Illinois at Chicago, Chicago, Illinois 60612
| | - Karol S Bruzik
- the Department of Medicinal Chemistry and Pharmacognosy, University of Illinois at Chicago, Chicago, Illinois 60612
| | - Jonathan B Cohen
- From the Department of Neurobiology, Harvard Medical School, Boston, Massachusetts 02115 and
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96
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Chen ZW, Bracamontes JR, Budelier MM, Germann AL, Shin DJ, Kathiresan K, Qian MX, Manion B, Cheng WWL, Reichert DE, Akk G, Covey DF, Evers AS. Multiple functional neurosteroid binding sites on GABAA receptors. PLoS Biol 2019; 17:e3000157. [PMID: 30845142 PMCID: PMC6424464 DOI: 10.1371/journal.pbio.3000157] [Citation(s) in RCA: 67] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2018] [Revised: 03/19/2019] [Accepted: 02/05/2019] [Indexed: 11/18/2022] Open
Abstract
Neurosteroids are endogenous modulators of neuronal excitability and nervous system development and are being developed as anesthetic agents and treatments for psychiatric diseases. While gamma amino-butyric acid Type A (GABAA) receptors are the primary molecular targets of neurosteroid action, the structural details of neurosteroid binding to these proteins remain ill defined. We synthesized neurosteroid analogue photolabeling reagents in which the photolabeling groups were placed at three positions around the neurosteroid ring structure, enabling identification of binding sites and mapping of neurosteroid orientation within these sites. Using middle-down mass spectrometry (MS), we identified three clusters of photolabeled residues representing three distinct neurosteroid binding sites in the human α1β3 GABAA receptor. Novel intrasubunit binding sites were identified within the transmembrane helical bundles of both the α1 (labeled residues α1-N408, Y415) and β3 (labeled residue β3-Y442) subunits, adjacent to the extracellular domains (ECDs). An intersubunit site (labeled residues β3-L294 and G308) in the interface between the β3(+) and α1(−) subunits of the GABAA receptor pentamer was also identified. Computational docking studies of neurosteroid to the three sites predicted critical residues contributing to neurosteroid interaction with the GABAA receptors. Electrophysiological studies of receptors with mutations based on these predictions (α1-V227W, N408A/Y411F, and Q242L) indicate that both the α1 intrasubunit and β3-α1 intersubunit sites are critical for neurosteroid action. Novel neurosteroid analogue photolabeling reagents identify three specific neurosteroid binding sites on α1β3 GABAA receptors, showing that a site between the α and β subunits, as well as a site within the α-subunit, contribute to neurosteroid-mediated enhancement of GABAA currents. Neurosteroids are cholesterol metabolites produced by neurons and glial cells that participate in central nervous system (CNS) development, regulate neuronal excitability, and modulate complex behaviors such as mood. Exogenously administered neurosteroid analogues are effective sedative hypnotics and are being developed as antidepressants and anticonvulsants. Gamma amino-butyric acid Type A (GABAA) receptors, the principal ionotropic inhibitory neurotransmitter receptors in the brain, are the primary functional target of neurosteroids. Understanding the molecular details of neurosteroid interactions with GABAA receptors is critical to understanding their mechanism of action and developing specific and effective therapeutic agents. In the current study, we developed a suite of neurosteroid analogue affinity labeling reagents, which we used to identify three distinct binding sites on GABAA receptors and to determine the orientation of neurosteroid binding in each site. Electrophysiological studies performed on receptors with mutations designed to disrupt the identified binding sites showed that two of the three sites contribute to neurosteroid modulation of GABAA currents. The distinct patterns of neurosteroid affinity, binding orientation, and effect provide the potential for the development of isoform-specific agonists, partial agonists, and antagonists with targeted therapeutic effects.
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Affiliation(s)
- Zi-Wei Chen
- Department of Anesthesiology, Washington University in St Louis, St Louis, Missouri, United States of America.,Taylor Family Institute for Innovative Psychiatric Research, St Louis, Missouri, United States of America
| | - John R Bracamontes
- Department of Anesthesiology, Washington University in St Louis, St Louis, Missouri, United States of America
| | - Melissa M Budelier
- Department of Anesthesiology, Washington University in St Louis, St Louis, Missouri, United States of America
| | - Allison L Germann
- Department of Anesthesiology, Washington University in St Louis, St Louis, Missouri, United States of America
| | - Daniel J Shin
- Department of Anesthesiology, Washington University in St Louis, St Louis, Missouri, United States of America
| | - Krishnan Kathiresan
- Department of Developmental Biology, Washington University in St Louis, St Louis, Missouri, United States of America
| | - Ming-Xing Qian
- Department of Developmental Biology, Washington University in St Louis, St Louis, Missouri, United States of America
| | - Brad Manion
- Department of Anesthesiology, Washington University in St Louis, St Louis, Missouri, United States of America
| | - Wayland W L Cheng
- Department of Anesthesiology, Washington University in St Louis, St Louis, Missouri, United States of America
| | - David E Reichert
- Taylor Family Institute for Innovative Psychiatric Research, St Louis, Missouri, United States of America.,Department of Radiology, Washington University in St Louis, St Louis, Missouri, United States of America
| | - Gustav Akk
- Department of Anesthesiology, Washington University in St Louis, St Louis, Missouri, United States of America
| | - Douglas F Covey
- Department of Anesthesiology, Washington University in St Louis, St Louis, Missouri, United States of America.,Taylor Family Institute for Innovative Psychiatric Research, St Louis, Missouri, United States of America.,Department of Developmental Biology, Washington University in St Louis, St Louis, Missouri, United States of America
| | - Alex S Evers
- Department of Anesthesiology, Washington University in St Louis, St Louis, Missouri, United States of America.,Taylor Family Institute for Innovative Psychiatric Research, St Louis, Missouri, United States of America.,Department of Developmental Biology, Washington University in St Louis, St Louis, Missouri, United States of America
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97
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Coughlin Q, Hopper AT, Blanco MJ, Tirunagaru V, Robichaud AJ, Doller D. Allosteric Modalities for Membrane-Bound Receptors: Insights from Drug Hunting for Brain Diseases. J Med Chem 2019; 62:5979-6002. [PMID: 30721063 DOI: 10.1021/acs.jmedchem.8b01651] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Medicinal chemists are accountable for embedding the appropriate drug target profile into the molecular architecture of a clinical candidate. An accurate characterization of the functional effects following binding of a drug to its biological target is a fundamental step in the discovery of new medicines, informing the translation of preclinical efficacy and safety observations into human trials. Membrane-bound proteins, particularly ion channels and G protein-coupled receptors (GPCRs), are biological targets prone to allosteric modulation. Investigations using allosteric drug candidates and chemical tools suggest that their functional effects may be tailored with a high degree of translational alignment, making them molecular tools to correct pathophysiological functional tone and enable personalized medicine when a causative target-to-disease link is known. We present select examples of functional molecular fine-tuning of allosterism and discuss consequences relevant to drug design.
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98
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Abstract
The pentameric γ-aminobutyric acid type A receptors are ion channels activated by ligands, which intervene in the rapid inhibitory transmission in the mammalian CNS. Due to their rich pharmacology and therapeutic potential, it is essential to understand their structure and function thoroughly. This deep characterization was hampered by the lack of experimental structural information for many years. Thus, computational techniques have been extensively combined with experimental data, in order to undertake the study of γ-aminobutyric acid type A receptors and their interaction with drugs. Here, we review the exciting journey made to assess the structures of these receptors and outline major outcomes. Finally, we discuss the brand new structure of the α1β2γ2 subtype and the amazing advances it brings to the field.
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99
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Simpson J, Pálvölgyi A, Antoni FA. Direct stimulation of adenylyl cyclase 9 by the fungicide imidazole miconazole. Naunyn Schmiedebergs Arch Pharmacol 2019; 392:497-504. [PMID: 30607468 DOI: 10.1007/s00210-018-01610-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2018] [Accepted: 12/21/2018] [Indexed: 10/27/2022]
Abstract
In mammals, nine genes encode trans-membrane adenylyl cyclase (tmAC) isoforms that synthesize the intracellular messenger compound cAMP from ATP. As cAMP is produced in virtually all types of cell, isoform-selective modulators of tmAC would have major research and therapeutic potential. This study investigated the effects of fungicide imidazoles previously shown to suppress cAMP production in various tissues on the activities of tmAC isoforms AC1, 2, or 9 stably expressed in human embryonic kidney 293 cells. Intact cells, as well as crude membranes, were exposed to various imidazoles or known stimulators of tmAC and the ensuing changes in the production of cAMP analyzed. In crude membranes, the activity of AC9 in the presence of GDP-β-S was enhanced by miconazole with an EC50 of ~ 8 μM, while AC1 and AC2 were inhibited with an IC50 of ~ 20 μM. Clotrimazole (10-100 μM) was an inhibitor of all the ACs tested. Substrate saturation analysis indicated that miconazole increased the Vmax of AC9 by 3-fold while having no effect on the Km. In intact cells, the effect of miconazole on cAMP production through AC9 was additive with that of isoproterenol. The stimulation of cAMP production by miconazole was inhibited by Ca2+, and this could be prevented by the calcineurin blocker FK506. In sum, activation of AC9 by miconazole is through a mechanism distinct from that of forskolin, activated G proteins, or the COOH-terminal mediated autoinhibition. However, it is subject to the AC9 isoform-specific inhibition by Ca2+/calcineurin. Differential modulation of mammalian tmAC paralogs appears to be achievable by an imidazole with phenylated side chains. Optimization of the lead compound and exploration of the underlying mechanism(s) of action in more detail could exploit this further.
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Affiliation(s)
- James Simpson
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, Scotland, EH8 9XD, UK
| | - Adrienn Pálvölgyi
- Division of Preclinical Research, Egis Pharmaceuticals PLC, Budapest, Hungary
| | - Ferenc A Antoni
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, Scotland, EH8 9XD, UK. .,Division of Preclinical Research, Egis Pharmaceuticals PLC, Budapest, Hungary.
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100
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Ratner MH, Kumaresan V, Farb DH. Neurosteroid Actions in Memory and Neurologic/Neuropsychiatric Disorders. Front Endocrinol (Lausanne) 2019; 10:169. [PMID: 31024441 PMCID: PMC6465949 DOI: 10.3389/fendo.2019.00169] [Citation(s) in RCA: 62] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/24/2018] [Accepted: 02/28/2019] [Indexed: 12/24/2022] Open
Abstract
Memory dysfunction is a symptomatic feature of many neurologic and neuropsychiatric disorders; however, the basic underlying mechanisms of memory and altered states of circuitry function associated with disorders of memory remain a vast unexplored territory. The initial discovery of endogenous neurosteroids triggered a quest to elucidate their role as neuromodulators in normal and diseased brain function. In this review, based on the perspective of our own research, the advances leading to the discovery of positive and negative neurosteroid allosteric modulators of GABA type-A (GABAA), NMDA, and non-NMDA type glutamate receptors are brought together in a historical and conceptual framework. We extend the analysis toward a state-of-the art view of how neurosteroid modulation of neural circuitry function may affect memory and memory deficits. By aggregating the results from multiple laboratories using both animal models for disease and human clinical research on neuropsychiatric and age-related neurodegenerative disorders, elements of a circuitry level view begins to emerge. Lastly, the effects of both endogenously active and exogenously administered neurosteroids on neural networks across the life span of women and men point to a possible underlying pharmacological connectome by which these neuromodulators might act to modulate memory across diverse altered states of mind.
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