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Design, synthesis, anticancer activity and molecular docking analysis of novel dinitrophenylpyrazole bearing 1,2,3-triazoles. J Mol Struct 2021. [DOI: 10.1016/j.molstruc.2021.130865] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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2
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El-Subbagh HI. Novel GABA A Agonist Entities: Pharmacological Investigation and Molecular Modeling Study of Thiazolo- and Thiadiazolo-[3,2-a][1,3]diazepine Analogs. Mini Rev Med Chem 2021; 21:1048-1057. [PMID: 33390131 DOI: 10.2174/1389557521999201230195733] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2020] [Revised: 10/07/2020] [Accepted: 10/16/2020] [Indexed: 11/22/2022]
Abstract
Thiazolo- and thiadiazolo-[3,2-a][1,3]diazepines and their patented derivatives, tested with diverse CNS pharmacological activities, constitute an important class of compounds for new drug development. Therefore, research efforts were continued to design, synthesize, and evaluate compounds for their ultra-short, short-acting hypnotic, anticonvulsant, and neuromuscular blocking activities. The present review provides a summary of the work accomplished by these heterocycles and their biological evaluation.
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Affiliation(s)
- Hussein I El-Subbagh
- Department of Medicinal Chemistry, College of Pharmacy, Mansoura University, Mansoura 35516, Egypt
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3
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Platholi J, Hemmings HC. Effects of general anesthetics on synaptic transmission and plasticity. Curr Neuropharmacol 2021; 20:27-54. [PMID: 34344292 PMCID: PMC9199550 DOI: 10.2174/1570159x19666210803105232] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Revised: 07/26/2021] [Accepted: 08/02/2021] [Indexed: 11/22/2022] Open
Abstract
General anesthetics depress excitatory and/or enhance inhibitory synaptic transmission principally by modulating the function of glutamatergic or GABAergic synapses, respectively, with relative anesthetic agent-specific mechanisms. Synaptic signaling proteins, including ligand- and voltage-gated ion channels, are targeted by general anesthetics to modulate various synaptic mechanisms, including presynaptic neurotransmitter release, postsynaptic receptor signaling, and dendritic spine dynamics to produce their characteristic acute neurophysiological effects. As synaptic structure and plasticity mediate higher-order functions such as learning and memory, long-term synaptic dysfunction following anesthesia may lead to undesirable neurocognitive consequences depending on the specific anesthetic agent and the vulnerability of the population. Here we review the cellular and molecular mechanisms of transient and persistent general anesthetic alterations of synaptic transmission and plasticity.
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Affiliation(s)
- Jimcy Platholi
- Cornell University Joan and Sanford I Weill Medical College Ringgold standard institution - Anesthesiology New York, New York. United States
| | - Hugh C Hemmings
- Cornell University Joan and Sanford I Weill Medical College Ringgold standard institution - Anesthesiology New York, New York. United States
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4
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Elephants in the Dark: Insights and Incongruities in Pentameric Ligand-gated Ion Channel Models. J Mol Biol 2021; 433:167128. [PMID: 34224751 DOI: 10.1016/j.jmb.2021.167128] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2021] [Revised: 06/25/2021] [Accepted: 06/25/2021] [Indexed: 02/06/2023]
Abstract
The superfamily of pentameric ligand-gated ion channels (pLGICs) comprises key players in electrochemical signal transduction across evolution, including historic model systems for receptor allostery and targets for drug development. Accordingly, structural studies of these channels have steadily increased, and now approach 250 depositions in the protein data bank. This review contextualizes currently available structures in the pLGIC family, focusing on morphology, ligand binding, and gating in three model subfamilies: the prokaryotic channel GLIC, the cation-selective nicotinic acetylcholine receptor, and the anion-selective glycine receptor. Common themes include the challenging process of capturing and annotating channels in distinct functional states; partially conserved gating mechanisms, including remodeling at the extracellular/transmembrane-domain interface; and diversity beyond the protein level, arising from posttranslational modifications, ligands, lipids, and signaling partners. Interpreting pLGIC structures can be compared to describing an elephant in the dark, relying on touch alone to comprehend the many parts of a monumental beast: each structure represents a snapshot in time under specific experimental conditions, which must be integrated with further structure, function, and simulations data to build a comprehensive model, and understand how one channel may fundamentally differ from another.
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5
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Xie L, Hu Y, Yan D, McQuillan P, Liu Y, Zhu S, Zhu Z, Jiang Y, Hu Z. The relationship between exposure to general anesthetic agents and the risk of developing an impulse control disorder. Pharmacol Res 2021; 165:105440. [PMID: 33493656 DOI: 10.1016/j.phrs.2021.105440] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Revised: 01/13/2021] [Accepted: 01/16/2021] [Indexed: 12/18/2022]
Abstract
Most studies examining the effect of extended exposure to general anesthetic agents (GAAs) have demonstrated that extended exposure induces both structural and functional changes in the central nervous system. These changes are frequently accompanied by neurobehavioral changes that include impulse control disorders that are generally characterized by deficits in behavioral inhibition and executive function. In this review, we will.
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Affiliation(s)
- Linghua Xie
- Department of Anesthesiology, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Yuhan Hu
- Department of Cell Biology, Yale University, New Haven, CT, USA
| | - Dandan Yan
- Department of Anesthesiology, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - P McQuillan
- Department of Anesthesiology, Penn State Hershey Medical Centre, Penn State College of Medicine, Hershey, PA, USA
| | - Yue Liu
- Department of Anesthesiology, The Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Shengmei Zhu
- Department of Anesthesiology, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Zhirui Zhu
- Department of Anesthesiology, The Children Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Yilei Jiang
- Department of Anesthesiology, The Children Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Zhiyong Hu
- Department of Anesthesiology, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China.
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6
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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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7
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Do Nicotinic Receptors Modulate High-Order Cognitive Processing? Trends Neurosci 2020; 43:550-564. [DOI: 10.1016/j.tins.2020.06.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Revised: 05/19/2020] [Accepted: 06/01/2020] [Indexed: 12/19/2022]
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8
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Donat CK, Hansen HH, Hansen HD, Mease RC, Horti AG, Pomper MG, L’Estrade ET, Herth MM, Peters D, Knudsen GM, Mikkelsen JD. In Vitro and In Vivo Characterization of Dibenzothiophene Derivatives [ 125I]Iodo-ASEM and [ 18F]ASEM as Radiotracers of Homo- and Heteromeric α7 Nicotinic Acetylcholine Receptors. Molecules 2020; 25:molecules25061425. [PMID: 32245032 PMCID: PMC7144377 DOI: 10.3390/molecules25061425] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2020] [Revised: 02/25/2020] [Accepted: 02/27/2020] [Indexed: 12/18/2022] Open
Abstract
The α7 nicotinic acetylcholine receptor (α7 nAChR) is involved in several cognitive and physiologic processes; its expression levels and patterns change in neurologic and psychiatric diseases, such as schizophrenia and Alzheimer’s disease, which makes it a relevant drug target. Development of selective radioligands is important for defining binding properties and occupancy of novel molecules targeting the receptor. We tested the in vitro binding properties of [125I]Iodo-ASEM [(3-(1,4-diazabycyclo[3.2.2]nonan-4-yl)-6-(125I-iododibenzo[b,d]thiopentene 5,5-dioxide)] in the mouse, rat and pig brain using autoradiography. The in vivo binding properties of [18F]ASEM were investigated using positron emission tomography (PET) in the pig brain. [125I]Iodo-ASEM showed specific and displaceable high affinity (~1 nM) binding in mouse, rat, and pig brain. Binding pattern overlapped with [125I]α-bungarotoxin, specific binding was absent in α7 nAChR gene-deficient mice and binding was blocked by a range of α7 nAChR orthosteric modulators in an affinity-dependent order in the pig brain. Interestingly, relative to the wild-type, binding in β2 nAChR gene-deficient mice was lower for [125I]Iodo-ASEM (58% ± 2.7%) than [125I]α-bungarotoxin (23% ± 0.2%), potentially indicating different binding properties to heteromeric α7β2 nAChR. [18F]ASEM PET in the pig showed high brain uptake and reversible tracer kinetics with a similar spatial distribution as previously reported for α7 nAChR. Blocking with SSR-180,711 resulted in a significant decrease in [18F]ASEM binding. Our findings indicate that [125I]Iodo-ASEM allows sensitive and selective imaging of α7 nAChR in vitro, with better signal-to-noise ratio than previous tracers. Preliminary data of [18F]ASEM in the pig brain demonstrated principal suitable kinetic properties for in vivo quantification of α7 nAChR, comparable to previously published data.
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Affiliation(s)
- Cornelius K. Donat
- Neurobiology Research Unit, Copenhagen University Hospital, Rigshospitalet, DK-2100 Copenhagen, Denmark; (H.H.H.); (H.D.H.); (E.T.L.); (G.M.K.)
- Department of Brain Sciences, Imperial College London, London W12 0 LS, UK
- Correspondence: (C.K.D.); (J.D.M.); Tel.: +45-40205378 (J.D.M)
| | - Henrik H. Hansen
- Neurobiology Research Unit, Copenhagen University Hospital, Rigshospitalet, DK-2100 Copenhagen, Denmark; (H.H.H.); (H.D.H.); (E.T.L.); (G.M.K.)
| | - Hanne D. Hansen
- Neurobiology Research Unit, Copenhagen University Hospital, Rigshospitalet, DK-2100 Copenhagen, Denmark; (H.H.H.); (H.D.H.); (E.T.L.); (G.M.K.)
| | - Ronnie C. Mease
- Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA; (R.C.M.); (A.G.H.); (M.G.P.)
| | - Andrew G. Horti
- Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA; (R.C.M.); (A.G.H.); (M.G.P.)
| | - Martin G. Pomper
- Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA; (R.C.M.); (A.G.H.); (M.G.P.)
| | - Elina T. L’Estrade
- Neurobiology Research Unit, Copenhagen University Hospital, Rigshospitalet, DK-2100 Copenhagen, Denmark; (H.H.H.); (H.D.H.); (E.T.L.); (G.M.K.)
- Department of Drug Design and Pharmacology, University of Copenhagen, Jagtvej 162, 2100 Copenhagen, Denmark;
- Department of Clinical Physiology, Nuclear Medicine & PET, Rigshospitalet, Blegdamsvej 9, 2100 Copenhagen, Denmark
| | - Matthias M. Herth
- Department of Drug Design and Pharmacology, University of Copenhagen, Jagtvej 162, 2100 Copenhagen, Denmark;
- Department of Clinical Physiology, Nuclear Medicine & PET, Rigshospitalet, Blegdamsvej 9, 2100 Copenhagen, Denmark
| | | | - Gitte M. Knudsen
- Neurobiology Research Unit, Copenhagen University Hospital, Rigshospitalet, DK-2100 Copenhagen, Denmark; (H.H.H.); (H.D.H.); (E.T.L.); (G.M.K.)
| | - Jens D. Mikkelsen
- Neurobiology Research Unit, Copenhagen University Hospital, Rigshospitalet, DK-2100 Copenhagen, Denmark; (H.H.H.); (H.D.H.); (E.T.L.); (G.M.K.)
- Correspondence: (C.K.D.); (J.D.M.); Tel.: +45-40205378 (J.D.M)
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9
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Al Rawashdah S, Hamrouni A, Sadek B, Amer R, Metwaly M, Atatreh N, Ghattas MA. Molecular modelling studies on ɑ7 nicotinic receptor allosteric modulators yields novel filter-based virtual screening protocol. J Mol Graph Model 2019; 92:44-54. [DOI: 10.1016/j.jmgm.2019.07.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Revised: 06/30/2019] [Accepted: 07/01/2019] [Indexed: 11/26/2022]
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10
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Silva AR, Grosso C, Delerue-Matos C, Rocha JM. Comprehensive review on the interaction between natural compounds and brain receptors: Benefits and toxicity. Eur J Med Chem 2019; 174:87-115. [PMID: 31029947 DOI: 10.1016/j.ejmech.2019.04.028] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2018] [Revised: 04/10/2019] [Accepted: 04/11/2019] [Indexed: 02/06/2023]
Abstract
Given their therapeutic activity, natural products have been used in traditional medicines throughout the centuries. The growing interest of the scientific community in phytopharmaceuticals, and more recently in marine products, has resulted in a significant number of research efforts towards understanding their effect in the treatment of neurodegenerative diseases, such as Alzheimer's (AD), Parkinson (PD) and Huntington (HD). Several studies have shown that many of the primary and secondary metabolites of plants, marine organisms and others, have high affinities for various brain receptors and may play a crucial role in the treatment of diseases affecting the central nervous system (CNS) in mammalians. Actually, such compounds may act on the brain receptors either by agonism, antagonism, allosteric modulation or other type of activity aimed at enhancing a certain effect. The current manuscript comprehensively reviews the state of the art on the interactions between natural compounds and brain receptors. This information is of foremost importance when it is intended to investigate and develop cutting-edge drugs, more effective and with alternative mechanisms of action to the conventional drugs presently used for the treatment of neurodegenerative diseases. Thus, we reviewed the effect of 173 natural products on neurotransmitter receptors, diabetes related receptors, neurotrophic factor related receptors, immune system related receptors, oxidative stress related receptors, transcription factors regulating gene expression related receptors and blood-brain barrier receptors.
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Affiliation(s)
- Ana R Silva
- Centre of Molecular and Environmental Biology (CBMA), Department of Biology (DB), University of Minho (UM), Campus Gualtar, P-4710-057, Braga, Portugal
| | - Clara Grosso
- REQUIMTE/LAQV, Instituto Superior de Engenharia do Instituto Politécnico do Porto, Rua Dr. António Bernardino de Almeida, 431, P-4249-015, Porto, Portugal.
| | - Cristina Delerue-Matos
- REQUIMTE/LAQV, Instituto Superior de Engenharia do Instituto Politécnico do Porto, Rua Dr. António Bernardino de Almeida, 431, P-4249-015, Porto, Portugal
| | - João M Rocha
- Centre of Molecular and Environmental Biology (CBMA), Department of Biology (DB), University of Minho (UM), Campus Gualtar, P-4710-057, Braga, Portugal; REQUIMTE/LAQV, Grupo de investigação de Química Orgânica Aplicada (QUINOA), Laboratório de polifenóis alimentares, Departamento de Química e Bioquímica (DQB), Faculdade de Ciências da Universidade do Porto (FCUP), Rua do Campo Alegre, s/n, P-4169-007, Porto, Portugal
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11
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Abstract
Inhalants are a loosely organized category of abused compounds defined entirely by their common route of administration. Inhalants include volatile solvents, fuels, volatile anesthetics, gasses, and liquefied refrigerants, among others. They are ubiquitous in modern society as ingredients in a wide variety of household, commercial, and medical products. Persons of all ages abuse inhalants but the highest prevalence of abuse is in younger adolescents. Although inhalants have been shown to act upon a host of neurotransmitter receptors, the stimulus effects of the few inhalants which have been trained or tested in drug discrimination procedures suggest that their discriminative stimulus properties are mediated by a few key neurotransmitter receptor systems. Abused volatile solvent inhalants have stimulus effects that are similar to a select group of GABAA positive modulators comprised of benzodiazepines and barbiturates. In contrast the stimulus effects of nitrous oxide gas appear to be at least partially mediated by uncompetitive antagonism of NMDA receptors. Finally, volatile anesthetic inhalants have stimulus effects in common with both GABAA positive modulators as well as competitive NMDA antagonists. In addition to a review of the pharmacology underlying the stimulus effects of inhalants, the chapter also discusses the scientific value of utilizing drug discrimination as a means of functionally grouping inhalants according to their abuse-related pharmacological properties.
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Affiliation(s)
- Keith L Shelton
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, 410 North 12th Street, Room 746, P.O. Box 980613, Richmond, VA, 23298-0613, USA.
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12
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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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13
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Wang Y, Yang E, Wells MM, Bondarenko V, Woll K, Carnevale V, Granata D, Klein ML, Eckenhoff RG, Dailey WP, Covarrubias M, Tang P, Xu Y. Propofol inhibits the voltage-gated sodium channel NaChBac at multiple sites. J Gen Physiol 2018; 150:1317-1331. [PMID: 30018039 PMCID: PMC6122922 DOI: 10.1085/jgp.201811993] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2018] [Revised: 05/02/2018] [Accepted: 06/15/2018] [Indexed: 12/24/2022] Open
Abstract
Voltage-gated sodium (NaV) channels are important targets of general anesthetics, including the intravenous anesthetic propofol. Electrophysiology studies on the prokaryotic NaV channel NaChBac have demonstrated that propofol promotes channel activation and accelerates activation-coupled inactivation, but the molecular mechanisms of these effects are unclear. Here, guided by computational docking and molecular dynamics simulations, we predict several propofol-binding sites in NaChBac. We then strategically place small fluorinated probes at these putative binding sites and experimentally quantify the interaction strengths with a fluorinated propofol analogue, 4-fluoropropofol. In vitro and in vivo measurements show that 4-fluoropropofol and propofol have similar effects on NaChBac function and nearly identical anesthetizing effects on tadpole mobility. Using quantitative analysis by 19F-NMR saturation transfer difference spectroscopy, we reveal strong intermolecular cross-relaxation rate constants between 4-fluoropropofol and four different regions of NaChBac, including the activation gate and selectivity filter in the pore, the voltage sensing domain, and the S4-S5 linker. Unlike volatile anesthetics, 4-fluoropropofol does not bind to the extracellular interface of the pore domain. Collectively, our results show that propofol inhibits NaChBac at multiple sites, likely with distinct modes of action. This study provides a molecular basis for understanding the net inhibitory action of propofol on NaV channels.
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Affiliation(s)
- Yali Wang
- Department of Anesthesiology, University of Pittsburgh School of Medicine, Pittsburgh, PA
| | - Elaine Yang
- Department of Neuroscience and Vickie and Jack Farber Institute for Neuroscience, Sidney Kimmel Medical College and Jefferson College of Biomedical Sciences, Thomas Jefferson University, Philadelphia, PA
| | - Marta M Wells
- Department of Anesthesiology, University of Pittsburgh School of Medicine, Pittsburgh, PA
- Department of Computational and Systems Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA
| | - Vasyl Bondarenko
- Department of Anesthesiology, University of Pittsburgh School of Medicine, Pittsburgh, PA
| | - Kellie Woll
- Department of Anesthesiology and Critical Care, University of Pennsylvania, Philadelphia, PA
| | - Vincenzo Carnevale
- Institute for Computational Molecular Science, College of Science and Technology, Temple University, Philadelphia, PA
| | - Daniele Granata
- Institute for Computational Molecular Science, College of Science and Technology, Temple University, Philadelphia, PA
| | - Michael L Klein
- Institute for Computational Molecular Science, College of Science and Technology, Temple University, Philadelphia, PA
| | - Roderic G Eckenhoff
- Department of Anesthesiology and Critical Care, University of Pennsylvania, Philadelphia, PA
| | - William P Dailey
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA
| | - Manuel Covarrubias
- Department of Neuroscience and Vickie and Jack Farber Institute for Neuroscience, Sidney Kimmel Medical College and Jefferson College of Biomedical Sciences, Thomas Jefferson University, Philadelphia, PA
| | - Pei Tang
- Department of Anesthesiology, University of Pittsburgh School of Medicine, Pittsburgh, PA
- Department of Computational and Systems Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA
| | - Yan Xu
- Department of Anesthesiology, University of Pittsburgh School of Medicine, Pittsburgh, PA
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA
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14
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Nielsen BE, Minguez T, Bermudez I, Bouzat C. Molecular function of the novel α7β2 nicotinic receptor. Cell Mol Life Sci 2018; 75:2457-2471. [PMID: 29313059 PMCID: PMC11105712 DOI: 10.1007/s00018-017-2741-4] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2017] [Revised: 11/30/2017] [Accepted: 12/27/2017] [Indexed: 01/03/2023]
Abstract
The α7 nicotinic receptor is a promising drug target for neurological and inflammatory disorders. Although it is the homomeric member of the family, a novel α7β2 heteromeric receptor has been discovered. To decipher the functional contribution of the β2 subunit, we generated heteromeric receptors with fixed stoichiometry by two different approaches comprising concatenated and unlinked subunits. Receptors containing up to three β2 subunits are functional. As the number of β2 subunits increases in the pentameric arrangement, the durations of channel openings and activation episodes increase progressively probably due to decreased desensitization. The prolonged activation episodes conform the kinetic signature of α7β2 and may have an impact on neuronal excitability. For activation of α7β2 receptors, an α7/α7 binding-site interface is required, thus indicating that the three β2 subunits are located consecutively in the pentameric arrangement. α7-positive allosteric modulators (PAMs) are emerging as novel therapeutic drugs. The presence of β2 in the pentamer affects neither type II PAM potentiation nor activation by an allosteric agonist whereas it impairs type I PAM potentiation. This first single-channel study provides fundamental basis required to decipher the role and function of the novel α7β2 receptor and opens doors to develop selective therapeutic drugs.
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Affiliation(s)
- Beatriz E Nielsen
- Instituto de Investigaciones Bioquímicas de Bahía Blanca, Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur-Consejo Nacional de Investigaciones Científicas y Técnicas (UNS-CONICET), 8000, Bahía Blanca, Argentina
| | - Teresa Minguez
- Department of Medical and Biological Sciences, Oxford Brookes University, Oxford, OX3 0BP, UK
| | - Isabel Bermudez
- Department of Medical and Biological Sciences, Oxford Brookes University, Oxford, OX3 0BP, UK
| | - Cecilia Bouzat
- Instituto de Investigaciones Bioquímicas de Bahía Blanca, Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur-Consejo Nacional de Investigaciones Científicas y Técnicas (UNS-CONICET), 8000, Bahía Blanca, Argentina.
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15
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Bondarenko V, Wells M, Xu Y, Tang P. Solution NMR Studies of Anesthetic Interactions with Ion Channels. Methods Enzymol 2018; 603:49-66. [PMID: 29673534 DOI: 10.1016/bs.mie.2018.01.018] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
NMR spectroscopy is one of the major tools to provide atomic resolution protein structural information. It has been used to elucidate the molecular details of interactions between anesthetics and ion channels, to identify anesthetic binding sites, and to characterize channel dynamics and changes introduced by anesthetics. In this chapter, we present solution NMR methods essential for investigating interactions between ion channels and general anesthetics, including both volatile and intravenous anesthetics. Case studies are provided with a focus on pentameric ligand-gated ion channels and the voltage-gated sodium channel NaChBac.
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Affiliation(s)
- Vasyl Bondarenko
- University of Pittsburgh School of Medicine, Pittsburgh, PA, United States
| | - Marta Wells
- University of Pittsburgh School of Medicine, Pittsburgh, PA, United States
| | - Yan Xu
- University of Pittsburgh School of Medicine, Pittsburgh, PA, United States
| | - Pei Tang
- University of Pittsburgh School of Medicine, Pittsburgh, PA, United States.
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16
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Newcombe J, Chatzidaki A, Sheppard TD, Topf M, Millar NS. Diversity of Nicotinic Acetylcholine Receptor Positive Allosteric Modulators Revealed by Mutagenesis and a Revised Structural Model. Mol Pharmacol 2017; 93:128-140. [PMID: 29196491 PMCID: PMC5767682 DOI: 10.1124/mol.117.110551] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2017] [Accepted: 11/30/2017] [Indexed: 01/26/2023] Open
Abstract
By combining electrophysiological and computational approaches we have examined a series of positive allosteric modulators (PAMs) acting on the human α7 nicotinic acetylcholine receptor (nAChR). Electrophysiological studies have focused on three α7-selective PAMs (A-867744, TBS-516, and TQS) that display similar effects on wild-type α7 nAChRs. In addition to potentiating agonist-evoked responses, all three compounds reduce receptor desensitization and, consequently, are classed as type II PAMs. Despite having similar effects on wild-type receptors, A-867744 was found to have profoundly differing effects on mutated receptors compared with TBS-516 and TQS, a finding that is consistent with previous studies indicating that A-867744 may have a different mechanism of action compare with other α7-selective type II PAMs. Due to evidence that these PAMs bind within the α7 nAChR transmembrane region, we generated and validated new structural models of α7. Importantly, we have corrected a previously identified error in the transmembrane region of the original cryo–electron microscopy Torpedo model; the only pentameric ligand-gated ion channel imaged in a native lipid membrane. Real-space refinement was used to generate closed and open conformations on which the α7 models were based. Consensus docking with an extended series of PAMs with chemical similarity to A-867744, TBS-516, and TQS suggests that all bind to a broadly similar intersubunit transmembrane site. However, differences in the predicted binding of A-867744, compared with TBS-516 and TQS, may help to explain the distinct functional effects of A-867744. Thus, our revised structural models may provide a useful tool for interpreting functional effects of PAMs.
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Affiliation(s)
- Joseph Newcombe
- Departments of Chemistry (J.N., T.D.S.) and Neuroscience, Physiology and Pharmacology (A.C., N.S.M.), University College London, London, United Kingdom; and Institute of Structural and Molecular Biology, Birkbeck, University of London, London, United Kingdom (J.N., M.T.)
| | - Anna Chatzidaki
- Departments of Chemistry (J.N., T.D.S.) and Neuroscience, Physiology and Pharmacology (A.C., N.S.M.), University College London, London, United Kingdom; and Institute of Structural and Molecular Biology, Birkbeck, University of London, London, United Kingdom (J.N., M.T.)
| | - Tom D Sheppard
- Departments of Chemistry (J.N., T.D.S.) and Neuroscience, Physiology and Pharmacology (A.C., N.S.M.), University College London, London, United Kingdom; and Institute of Structural and Molecular Biology, Birkbeck, University of London, London, United Kingdom (J.N., M.T.)
| | - Maya Topf
- Departments of Chemistry (J.N., T.D.S.) and Neuroscience, Physiology and Pharmacology (A.C., N.S.M.), University College London, London, United Kingdom; and Institute of Structural and Molecular Biology, Birkbeck, University of London, London, United Kingdom (J.N., M.T.)
| | - Neil S Millar
- Departments of Chemistry (J.N., T.D.S.) and Neuroscience, Physiology and Pharmacology (A.C., N.S.M.), University College London, London, United Kingdom; and Institute of Structural and Molecular Biology, Birkbeck, University of London, London, United Kingdom (J.N., M.T.)
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17
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Thiadiazolodiazepine analogues as a new class of neuromuscular blocking agents: Synthesis, biological evaluation and molecular modeling study. Eur J Med Chem 2017; 126:15-23. [DOI: 10.1016/j.ejmech.2016.09.096] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2016] [Revised: 09/28/2016] [Accepted: 09/29/2016] [Indexed: 12/17/2022]
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18
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Nicotine versus 6-hydroxy-l-nicotine against chlorisondamine induced memory impairment and oxidative stress in the rat hippocampus. Biomed Pharmacother 2016; 86:102-108. [PMID: 27951416 DOI: 10.1016/j.biopha.2016.12.008] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2016] [Revised: 11/28/2016] [Accepted: 12/04/2016] [Indexed: 11/21/2022] Open
Abstract
6-Hydroxy-l-nicotine (6HLN), a nicotine derivative from nicotine degradation by Arthrobacter nicotinovorans pAO1 strain was found to improve behavioral deficits and to reverse oxidative stress in the rat hippocampus. Rats were given CHL (10mg/kg, i.p.) were used as an Alzheimer's disease-like model. The nicotine (0.3mg/kg) and 6HLN (0.3mg/kg) were administered alone or in combination in the CHL-treated rats. Memory-related behaviors were evaluated using Y-maze and radial arm-maze tests. The antioxidant enzymes activity and the levels of the biomarkers of oxidative stress were measured in the hippocampus. Statistical analyses were performed using two-way ANOVA and Tukey's post hoc test. F values for which p<0.05 were regarded as statistically significant. CHL-caused memory deficits and oxidative stress enhancing were observed. Both nicotine and 6HLN administration attenuated the cognitive deficits and recovered the antioxidant capacity in the rat hippocampus of the CHL rat model. Our results suggest that 6HLN versus nicotine confers anti-amnesic properties in the CHL-induced a rat model of memory impairment via reversing cholinergic function and decreasing brain oxidative stress, suggesting the use of this compound as an alternative agent in AD treatment.
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19
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Tillman TS, Alvarez FJD, Reinert NJ, Liu C, Wang D, Xu Y, Xiao K, Zhang P, Tang P. Functional Human α7 Nicotinic Acetylcholine Receptor (nAChR) Generated from Escherichia coli. J Biol Chem 2016; 291:18276-82. [PMID: 27385587 DOI: 10.1074/jbc.m116.729970] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2016] [Indexed: 11/06/2022] Open
Abstract
Human Cys-loop receptors are important therapeutic targets. High-resolution structures are essential for rational drug design, but only a few are available due to difficulties in obtaining sufficient quantities of protein suitable for structural studies. Although expression of proteins in E. coli offers advantages of high yield, low cost, and fast turnover, this approach has not been thoroughly explored for full-length human Cys-loop receptors because of the conventional wisdom that E. coli lacks the specific chaperones and post-translational modifications potentially required for expression of human Cys-loop receptors. Here we report the successful production of full-length wild type human α7nAChR from E. coli Chemically induced chaperones promote high expression levels of well-folded proteins. The choice of detergents, lipids, and ligands during purification determines the final protein quality. The purified α7nAChR not only forms pentamers as imaged by negative-stain electron microscopy, but also retains pharmacological characteristics of native α7nAChR, including binding to bungarotoxin and positive allosteric modulators specific to α7nAChR. Moreover, the purified α7nAChR injected into Xenopus oocytes can be activated by acetylcholine, choline, and nicotine, inhibited by the channel blockers QX-222 and phencyclidine, and potentiated by the α7nAChR specific modulators PNU-120596 and TQS. The successful generation of functional human α7nAChR from E. coli opens a new avenue for producing mammalian Cys-loop receptors to facilitate structure-based rational drug design.
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Affiliation(s)
| | | | | | | | | | - Yan Xu
- From the Departments of Anesthesiology, Structural Biology, Pharmacology and Chemical Biology, and
| | | | | | - Pei Tang
- From the Departments of Anesthesiology, Pharmacology and Chemical Biology, and Computational & Systems Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15260
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20
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Burgos CF, Yévenes GE, Aguayo LG. Structure and Pharmacologic Modulation of Inhibitory Glycine Receptors. Mol Pharmacol 2016; 90:318-25. [PMID: 27401877 DOI: 10.1124/mol.116.105726] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2016] [Accepted: 07/08/2016] [Indexed: 01/08/2023] Open
Abstract
Glycine receptors (GlyR) are inhibitory Cys-loop ion channels that contribute to the control of excitability along the central nervous system (CNS). GlyR are found in the spinal cord and brain stem, and more recently they were reported in higher regions of the CNS such as the hippocampus and nucleus accumbens. GlyR are involved in motor coordination, respiratory rhythms, pain transmission, and sensory processing, and they are targets for relevant physiologic and pharmacologic modulators. Several studies with protein crystallography and cryoelectron microscopy have shed light on the residues and mechanisms associated with the activation, blockade, and regulation of pentameric Cys-loop ion channels at the atomic level. Initial studies conducted on the extracellular domain of acetylcholine receptors, ion channels from prokaryote homologs-Erwinia chrysanthemi ligand-gated ion channel (ELIC), Gloeobacter violaceus ligand-gated ion channel (GLIC)-and crystallized eukaryotic receptors made it possible to define the overall structure and topology of the Cys-loop receptors. For example, the determination of pentameric GlyR structures bound to glycine and strychnine have contributed to visualizing the structural changes implicated in the transition between the open and closed states of the Cys-loop receptors. In this review, we summarize how the new information obtained in functional, mutagenesis, and structural studies have contributed to a better understanding of the function and regulation of GlyR.
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Affiliation(s)
- Carlos F Burgos
- Laboratory of Neurophysiology (C.F.B., L.G.A.), and Laboratory of Neuropharmacology (G.E.Y.), Department of Physiology, University of Concepción, Concepción, Chile
| | - Gonzalo E Yévenes
- Laboratory of Neurophysiology (C.F.B., L.G.A.), and Laboratory of Neuropharmacology (G.E.Y.), Department of Physiology, University of Concepción, Concepción, Chile
| | - Luis G Aguayo
- Laboratory of Neurophysiology (C.F.B., L.G.A.), and Laboratory of Neuropharmacology (G.E.Y.), Department of Physiology, University of Concepción, Concepción, Chile
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21
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Abstract
BACKGROUND Identifying functionally relevant anesthetic-binding sites in pentameric ligand-gated ion channels (pLGICs) is an important step toward understanding the molecular mechanisms underlying anesthetic action. The anesthetic propofol is known to inhibit cation-conducting pLGICs, including a prokaryotic pLGIC from Erwinia chrysanthemi (ELIC), but the sites responsible for functional inhibition remain undetermined. METHODS We photolabeled ELIC with a light-activated derivative of propofol (AziPm) and performed fluorine-19 nuclear magnetic resonance experiments to support propofol binding to a transmembrane domain (TMD) intrasubunit pocket. To differentiate sites responsible for propofol inhibition from those that are functionally irrelevant, we made an ELIC-γ-aminobutyric acid receptor (GABAAR) chimera that replaced the ELIC-TMD with the α1β3GABAAR-TMD and compared functional responses of ELIC-GABAAR and ELIC with propofol modulations. RESULTS Photolabeling showed multiple AziPm-binding sites in the extracellular domain (ECD) but only one site in the TMD with labeled residues M265 and F308 in the resting state of ELIC. Notably, this TMD site is an intrasubunit pocket that overlaps with binding sites for anesthetics, including propofol, found previously in other pLGICs. Fluorine-19 nuclear magnetic resonance experiments supported propofol binding to this TMD intrasubunit pocket only in the absence of agonist. Functional measurements of ELIC-GABAAR showed propofol potentiation of the agonist-elicited current instead of inhibition observed on ELIC. CONCLUSIONS The distinctly different responses of ELIC and ELIC-GABAAR to propofol support the functional relevance of propofol binding to the TMD. Combining the newly identified TMD intrasubunit pocket in ELIC with equivalent TMD anesthetic sites found previously in other cationic pLGICs, we propose this TMD pocket as a common site for anesthetic inhibition of pLGICs.
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22
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Wu J, Liu Q, Tang P, Mikkelsen JD, Shen J, Whiteaker P, Yakel JL. Heteromeric α7β2 Nicotinic Acetylcholine Receptors in the Brain. Trends Pharmacol Sci 2016; 37:562-574. [PMID: 27179601 DOI: 10.1016/j.tips.2016.03.005] [Citation(s) in RCA: 64] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2016] [Revised: 03/27/2016] [Accepted: 03/30/2016] [Indexed: 10/21/2022]
Abstract
The α7 nicotinic acetylcholine receptor (α7 nAChR) is highly expressed in the brain, where it maintains various neuronal functions including (but not limited to) learning and memory. In addition, the protein expression levels of α7 nAChRs are altered in various brain disorders. The classic rule governing α7 nAChR assembly in the mammalian brain was that it was assembled from five α7 subunits to form a homomeric receptor pentamer. However, emerging evidence demonstrates the presence of heteromeric α7 nAChRs in heterologously expressed systems and naturally in brain neurons, where α7 subunits are co-assembled with β2 subunits to form a novel type of α7β2 nAChR. Interestingly, the α7β2 nAChR exhibits distinctive function and pharmacology from traditional homomeric α7 nAChRs. We review recent advances in probing the distribution, function, pharmacology, pathophysiology, and stoichiometry of the heteromeric α7β2 nAChR, which have provided new insights into the understanding of a novel target of cholinergic signaling.
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Affiliation(s)
- Jie Wu
- Department of Physiology, Shantou University Medicine College, Shantou, Guangdong, China; Divisions of Neurology and Neurobiology, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, AZ 85013-4496, USA.
| | - Qiang Liu
- Divisions of Neurology and Neurobiology, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, AZ 85013-4496, USA
| | - Pei Tang
- Department of Anesthesiology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15260, USA
| | - Jens D Mikkelsen
- Neurobiology Research Unit, University Hospital Copenhagen, Rigshospitalet, Copenhagen, Denmark
| | - Jianxin Shen
- Department of Physiology, Shantou University Medicine College, Shantou, Guangdong, China
| | - Paul Whiteaker
- Divisions of Neurology and Neurobiology, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, AZ 85013-4496, USA
| | - Jerrel L Yakel
- Neurobiology Laboratory, National Institute of Environmental Health Sciences (NIEHS), National Institutes of Health (NIH)/DHHS, Research Triangle Park, North Carolina 27709, USA
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23
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Corradi J, Bouzat C. Understanding the Bases of Function and Modulation of α7 Nicotinic Receptors: Implications for Drug Discovery. Mol Pharmacol 2016; 90:288-99. [PMID: 27190210 DOI: 10.1124/mol.116.104240] [Citation(s) in RCA: 118] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2016] [Accepted: 05/05/2016] [Indexed: 01/01/2023] Open
Abstract
The nicotinic acetylcholine receptor (nAChR) belongs to a superfamily of pentameric ligand-gated ion channels involved in many physiologic and pathologic processes. Among nAChRs, receptors comprising the α7 subunit are unique because of their high Ca(2+) permeability and fast desensitization. nAChR agonists elicit a transient ion flux response that is further sustained by the release of calcium from intracellular sources. Owing to the dual ionotropic/metabotropic nature of α7 receptors, signaling pathways are activated. The α7 subunit is highly expressed in the nervous system, mostly in regions implicated in cognition and memory and has therefore attracted attention as a novel drug target. Additionally, its dysfunction is associated with several neuropsychiatric and neurologic disorders, such as schizophrenia and Alzheimer's disease. α7 is also expressed in non-neuronal cells, particularly immune cells, where it plays a role in immunity, inflammation, and neuroprotection. Thus, α7 potentiation has emerged as a therapeutic strategy for several neurologic and inflammatory disorders. With unique activation properties, the receptor is a sensitive drug target carrying different potential binding sites for chemical modulators, particularly agonists and positive allosteric modulators. Although macroscopic and single-channel recordings have provided significant information about the underlying molecular mechanisms and binding sites of modulatory compounds, we know just the tip of the iceberg. Further concerted efforts are necessary to effectively exploit α7 as a drug target for each pathologic situation. In this article, we focus mainly on the molecular basis of activation and drug modulation of α7, key pillars for rational drug design.
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Affiliation(s)
- Jeremías Corradi
- Instituto de Investigaciones Bioquímicas de Bahía Blanca, Universidad Nacional del Sur, CONICET/UNS, Bahía Blanca, Argentina
| | - Cecilia Bouzat
- Instituto de Investigaciones Bioquímicas de Bahía Blanca, Universidad Nacional del Sur, CONICET/UNS, Bahía Blanca, Argentina
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24
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Osaki Y, Nodera H, Banzrai C, Endo S, Takayasu H, Mori A, Shimatani Y, Kaji R. Effects of anesthetic agents on in vivo axonal HCN current in normal mice. Clin Neurophysiol 2015; 126:2033-9. [DOI: 10.1016/j.clinph.2014.12.025] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2014] [Revised: 12/01/2014] [Accepted: 12/29/2014] [Indexed: 12/17/2022]
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25
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Direct Pore Binding as a Mechanism for Isoflurane Inhibition of the Pentameric Ligand-gated Ion Channel ELIC. Sci Rep 2015; 5:13833. [PMID: 26346220 PMCID: PMC4561908 DOI: 10.1038/srep13833] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2015] [Accepted: 08/10/2015] [Indexed: 12/22/2022] Open
Abstract
Pentameric ligand-gated ion channels (pLGICs) are targets of general anesthetics, but molecular mechanisms underlying anesthetic action remain debatable. We found that ELIC, a pLGIC from Erwinia chrysanthemi, can be functionally inhibited by isoflurane and other anesthetics. Structures of ELIC co-crystallized with isoflurane in the absence or presence of an agonist revealed double isoflurane occupancies inside the pore near T237(6′) and A244(13′). A pore-radius contraction near the extracellular entrance was observed upon isoflurane binding. Electrophysiology measurements with a single-point mutation at position 6′ or 13′ support the notion that binding at these sites renders isoflurane inhibition. Molecular dynamics simulations suggested that isoflurane binding was more stable in the resting than in a desensitized pore conformation. This study presents compelling evidence for a direct pore-binding mechanism of isoflurane inhibition, which has a general implication for inhibitory action of general anesthetics on pLGICs.
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26
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Allosteric modulation of nicotinic acetylcholine receptors. Biochem Pharmacol 2015; 97:408-417. [PMID: 26231943 DOI: 10.1016/j.bcp.2015.07.028] [Citation(s) in RCA: 69] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2015] [Accepted: 07/24/2015] [Indexed: 12/12/2022]
Abstract
Nicotinic acetylcholine receptors (nAChRs) are receptors for the neurotransmitter acetylcholine and are members of the 'Cys-loop' family of pentameric ligand-gated ion channels (LGICs). Acetylcholine binds in the receptor extracellular domain at the interface between two subunits and research has identified a large number of nAChR-selective ligands, including agonists and competitive antagonists, that bind at the same site as acetylcholine (commonly referred to as the orthosteric binding site). In addition, more recent research has identified ligands that are able to modulate nAChR function by binding to sites that are distinct from the binding site for acetylcholine, including sites located in the transmembrane domain. These include positive allosteric modulators (PAMs), negative allosteric modulators (NAMs), silent allosteric modulators (SAMs) and compounds that are able to activate nAChRs via an allosteric binding site (allosteric agonists). Our aim in this article is to review important aspects of the pharmacological diversity of nAChR allosteric modulators and to describe recent evidence aimed at identifying binding sites for allosteric modulators on nAChRs.
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27
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Cheng Q, Yakel JL. The effect of α7 nicotinic receptor activation on glutamatergic transmission in the hippocampus. Biochem Pharmacol 2015. [PMID: 26212541 DOI: 10.1016/j.bcp.2015.07.015] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Nicotinic acetylcholine receptors (nAChRs) are expressed widely in the CNS, and mediate both synaptic and perisynaptic activities of endogenous cholinergic inputs and pharmacological actions of exogenous compounds (e.g., nicotine and choline). Behavioral studies indicate that nicotine improves such cognitive functions as learning and memory, however the cellular mechanism of these actions remains elusive. With help from newly developed biosensors and optogenetic tools, recent studies provide new insights on signaling mechanisms involved in the activation of nAChRs. Here we will review α7 nAChR's action in the tri-synaptic pathway in the hippocampus. The effects of α7 nAChR activation via either exogenous compounds or endogenous cholinergic innervation are detailed for spontaneous and evoked glutamatergic synaptic transmission and synaptic plasticity, as well as the underlying signaling mechanisms. In summary, α7 nAChRs trigger intracellular calcium rise and calcium-dependent signaling pathways to enhance glutamate release and induce glutamatergic synaptic plasticity.
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Affiliation(s)
- Qing Cheng
- Neurobiology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, Research Triangle Park, NC 27709, USA
| | - Jerrel L Yakel
- Neurobiology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, Research Triangle Park, NC 27709, USA
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28
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Inhalational anesthetics disrupt postsynaptic density protein-95, Drosophila disc large tumor suppressor, and zonula occludens-1 domain protein interactions critical to action of several excitatory receptor channels related to anesthesia. Anesthesiology 2015; 122:776-86. [PMID: 25654436 DOI: 10.1097/aln.0000000000000609] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
BACKGROUND The authors have shown previously that inhaled anesthetics disrupt the interaction between the second postsynaptic density protein-95, Drosophila disc large tumor suppressor, and zonula occludens-1 (PDZ) domain of postsynaptic density protein-95 (PSD-95) and the C-terminus of N-methyl-D-aspartate receptor subunits NR2A and NR2B. The study data indicate that PDZ domains may serve as a molecular target for inhaled anesthetics. However, the underlying molecular mechanisms remain to be illustrated. METHODS Glutathione S-transferase pull-down assay, coimmunoprecipitation, and yeast two-hybrid analysis were used to assess PDZ domain-mediated protein-protein interactions in different conditions. Nuclear magnetic resonance spectroscopy was used to investigate isoflurane-induced chemical shift changes in the PDZ1-3 domains of PSD-95. A surface plasmon resonance-based BIAcore (Sweden) assay was used to examine the ability of isoflurane to inhibit the PDZ domain-mediated protein-protein interactions in real time. RESULTS Halothane and isoflurane dose-dependently inhibited PDZ domain-mediated interactions between PSD-95 and Shaker-type potassium channel Kv1.4 and between α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor subunit GluA2 and its interacting proteins-glutamate receptor-interacting protein or protein interacting with c kinase 1. However, halothane and isoflurane had no effect on PDZ domain-mediated interactions between γ-aminobutyric acid type B receptor and its interacting proteins. The inhaled anesthetic isoflurane mostly affected the residues close to or in the peptide-binding groove of PSD-95 PDZ1 and PDZ2 (especially PDZ2), while barely affecting the peptide-binding groove of PSD-95 PDZ3. CONCLUSION These results suggest that inhaled anesthetics interfere with PDZ domain-mediated protein-protein interactions at several receptors important to neuronal excitation, anesthesia, and pain processing.
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29
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Thomsen MS, Zwart R, Ursu D, Jensen MM, Pinborg LH, Gilmour G, Wu J, Sher E, Mikkelsen JD. α7 and β2 Nicotinic Acetylcholine Receptor Subunits Form Heteromeric Receptor Complexes that Are Expressed in the Human Cortex and Display Distinct Pharmacological Properties. PLoS One 2015; 10:e0130572. [PMID: 26086615 PMCID: PMC4472343 DOI: 10.1371/journal.pone.0130572] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2015] [Accepted: 05/21/2015] [Indexed: 12/03/2022] Open
Abstract
The existence of α7β2 nicotinic acetylcholine receptors (nAChRs) has recently been demonstrated in both the rodent and human brain. Since α7-containing nAChRs are promising drug targets for schizophrenia and Alzheimer’s disease, it is critical to determine whether α7β2 nAChRs are present in the human brain, in which brain areas, and whether they differ functionally from α7 nAChR homomers. We used α-bungarotoxin to affinity purify α7-containing nAChRs from surgically excised human temporal cortex, and found that α7 subunits co-purify with β2 subunits, indicating the presence of α7β2 nAChRs in the human brain. We validated these results by demonstrating co-purification of β2 from wild-type, but not α7 or β2 knock-out mice. The pharmacology and kinetics of human α7β2 nAChRs differed significantly from that of α7 homomers in response to nAChR agonists when expressed in Xenopus oocytes and HEK293 cells. Notably, α7β2 heteromers expressed in HEK293 cells display markedly slower rise and decay phases. These results demonstrate that α7 subunits in the human brain form heteromeric complexes with β2 subunits, and that human α7β2 nAChR heteromers respond to nAChR agonists with a unique pharmacology and kinetic profile. α7β2 nAChRs thus represent an alternative mechanism for the reported clinical efficacy of α7 nAChR ligands.
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Affiliation(s)
- Morten Skøtt Thomsen
- Neurobiology Research Unit, University Hospital Copenhagen, Rigshospitalet, Copenhagen, Denmark
| | - Ruud Zwart
- Lilly Research Centre, Eli Lilly and Company Limited, Erl Wood Manor, United Kingdom
| | - Daniel Ursu
- Lilly Research Centre, Eli Lilly and Company Limited, Erl Wood Manor, United Kingdom
| | - Majbrit Myrup Jensen
- Neurobiology Research Unit, University Hospital Copenhagen, Rigshospitalet, Copenhagen, Denmark
| | - Lars Hageman Pinborg
- Neurobiology Research Unit, University Hospital Copenhagen, Rigshospitalet, Copenhagen, Denmark
- Epilepsy Clinic, University Hospital Copenhagen, Rigshospitalet, Copenhagen, Denmark
| | - Gary Gilmour
- Lilly Research Centre, Eli Lilly and Company Limited, Erl Wood Manor, United Kingdom
| | - Jie Wu
- Divisions of Neurology, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, United States of America
| | - Emanuele Sher
- Lilly Research Centre, Eli Lilly and Company Limited, Erl Wood Manor, United Kingdom
| | - Jens Damsgaard Mikkelsen
- Neurobiology Research Unit, University Hospital Copenhagen, Rigshospitalet, Copenhagen, Denmark
- * E-mail:
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30
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Kinde MN, Chen Q, Lawless MJ, Mowrey DD, Xu J, Saxena S, Xu Y, Tang P. Conformational Changes Underlying Desensitization of the Pentameric Ligand-Gated Ion Channel ELIC. Structure 2015; 23:995-1004. [PMID: 25960405 DOI: 10.1016/j.str.2015.03.017] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2014] [Revised: 03/24/2015] [Accepted: 03/30/2015] [Indexed: 11/18/2022]
Abstract
Structural rearrangements underlying functional transitions of pentameric ligand-gated ion channels (pLGICs) are not fully understood. Using (19)F nuclear magnetic resonance and electron spin resonance spectroscopy, we found that ELIC, a pLGIC from Erwinia chrysanthemi, expanded the extracellular end and contracted the intracellular end of its pore during transition from the resting to an apparent desensitized state. Importantly, the contraction at the intracellular end of the pore likely forms a gate to restrict ion transport in the desensitized state. This gate differs from the hydrophobic gate present in the resting state. Conformational changes of the TM2-TM3 loop were limited to the N-terminal end. The TM4 helices and the TM3-TM4 loop appeared relatively insensitive to agonist-mediated structural rearrangement. These results indicate that conformational changes accompanying functional transitions are not uniform among different ELIC regions. This work also revealed the co-existence of multiple conformations for a given state and suggested asymmetric conformational arrangements in a homomeric pLGIC.
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Affiliation(s)
- Monica N Kinde
- Department of Anesthesiology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15260, USA
| | - Qiang Chen
- Department of Anesthesiology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15260, USA
| | - Matthew J Lawless
- Department of Chemistry, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - David D Mowrey
- Department of Anesthesiology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15260, USA; Department of Computational & Systems Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15260, USA
| | - Jiawei Xu
- Department of Anesthesiology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15260, USA
| | - Sunil Saxena
- Department of Chemistry, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Yan Xu
- Department of Anesthesiology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15260, USA; Department of Pharmacology & Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15260, USA; Department of Structural Biology, 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 & Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15260, USA; Department of Computational & Systems Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15260, USA.
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31
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Durrant JD, Votapka L, Sørensen J, Amaro RE. POVME 2.0: An Enhanced Tool for Determining Pocket Shape and Volume Characteristics. J Chem Theory Comput 2014; 10:5047-5056. [PMID: 25400521 PMCID: PMC4230373 DOI: 10.1021/ct500381c] [Citation(s) in RCA: 173] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2014] [Indexed: 02/08/2023]
Abstract
![]()
Analysis of macromolecular/small-molecule
binding pockets can provide
important insights into molecular recognition and receptor dynamics.
Since its release in 2011, the POVME (POcket Volume MEasurer) algorithm
has been widely adopted as a simple-to-use tool for measuring and
characterizing pocket volumes and shapes. We here present POVME 2.0,
which is an order of magnitude faster, has improved accuracy, includes
a graphical user interface, and can produce volumetric density maps
for improved pocket analysis. To demonstrate the utility of the algorithm,
we use it to analyze the binding pocket of RNA editing ligase 1 from
the unicellular parasite Trypanosoma brucei, the
etiological agent of African sleeping sickness. The POVME analysis
characterizes the full dynamics of a potentially druggable transient
binding pocket and so may guide future antitrypanosomal drug-discovery
efforts. We are hopeful that this new version will be a useful tool
for the computational- and medicinal-chemist community.
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Affiliation(s)
- Jacob D Durrant
- Department of Chemistry & Biochemistry, University of California San Diego , La Jolla, California 92093, United States ; National Biomedical Computation Resource, Center for Research in Biological Systems, University of California San Diego , La Jolla, California 92093, United States
| | - Lane Votapka
- Department of Chemistry & Biochemistry, University of California San Diego , La Jolla, California 92093, United States
| | - Jesper Sørensen
- Department of Chemistry & Biochemistry, University of California San Diego , La Jolla, California 92093, United States
| | - Rommie E Amaro
- Department of Chemistry & Biochemistry, University of California San Diego , La Jolla, California 92093, United States ; National Biomedical Computation Resource, Center for Research in Biological Systems, University of California San Diego , La Jolla, California 92093, United States
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32
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Mowrey DD, Kinde MN, Xu Y, Tang P. Atomistic insights into human Cys-loop receptors by solution NMR. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2014; 1848:307-14. [PMID: 24680782 DOI: 10.1016/j.bbamem.2014.03.014] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2014] [Revised: 03/12/2014] [Accepted: 03/20/2014] [Indexed: 12/13/2022]
Abstract
Cys-loop receptors are pentameric ligand-gated ion channels (pLGICs) mediating fast neurotransmission in the central and peripheral nervous systems. They are important targets for many currently used clinical drugs, such as general anesthetics, and for allosteric modulators with potential therapeutic applications. Here, we provide an overview of advances in the use of solution NMR in structural and dynamic characterization of ion channels, particularly human Cys-loop receptors. We present challenges to overcome and realistic solutions for achieving high-resolution structural information for this family of receptors. We discuss how subtle structural differences among homologous channels define unique channel pharmacological properties and advocate the necessity to determine high-resolution structures for individual receptor subtypes. Finally, we describe drug binding to the TMDs of Cys-loop receptors identified by solution NMR and the associated dynamics changes relevant to channel functions.
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Affiliation(s)
- David D Mowrey
- Department of Anesthesiology, University of Pittsburgh School of Medicine, USA; Department of Computational & Systems Biology, University of Pittsburgh School of Medicine, USA
| | - Monica N Kinde
- Department of Anesthesiology, University of Pittsburgh School of Medicine, USA
| | - Yan Xu
- Department of Anesthesiology, University of Pittsburgh School of Medicine, USA; Department of Structural Biology, University of Pittsburgh School of Medicine, USA; Department of Pharmacology & Chemical Biology, University of Pittsburgh School of Medicine, USA.
| | - Pei Tang
- Department of Anesthesiology, University of Pittsburgh School of Medicine, USA; Department of Computational & Systems Biology, University of Pittsburgh School of Medicine, USA; Department of Pharmacology & Chemical Biology, University of Pittsburgh School of Medicine, USA.
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Bondarenko V, Mowrey DD, Tillman TS, Seyoum E, Xu Y, Tang P. NMR structures of the human α7 nAChR transmembrane domain and associated anesthetic binding sites. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2013; 1838:1389-95. [PMID: 24384062 DOI: 10.1016/j.bbamem.2013.12.018] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2013] [Revised: 11/19/2013] [Accepted: 12/23/2013] [Indexed: 12/11/2022]
Abstract
The α7 nicotinic acetylcholine receptor (nAChR), assembled as homomeric pentameric ligand-gated ion channels, is one of the most abundant nAChR subtypes in the brain. Despite its importance in memory, learning and cognition, no structure has been determined for the α7 nAChR TM domain, a target for allosteric modulators. Using solution state NMR, we determined the structure of the human α7 nAChR TM domain (PDB ID: 2MAW) and demonstrated that the α7 TM domain formed functional channels in Xenopus oocytes. We identified the associated binding sites for the anesthetics halothane and ketamine; the former cannot sensitively inhibit α7 function, but the latter can. The α7 TM domain folds into the expected four-helical bundle motif, but the intra-subunit cavity at the extracellular end of the α7 TM domain is smaller than the equivalent cavity in the α4β2 nAChRs (PDB IDs: 2LLY; 2LM2). Neither drug binds to the extracellular end of the α7 TM domain, but two halothane molecules or one ketamine molecule binds to the intracellular end of the α7 TM domain. Halothane and ketamine binding sites are partially overlapped. Ketamine, but not halothane, perturbed the α7 channel-gate residue L9'. Furthermore, halothane did not induce profound dynamics changes in the α7 channel as observed in α4β2. The study offers a novel high-resolution structure for the human α7 nAChR TM domain that is invaluable for developing α7-specific therapeutics. It also provides evidence to support the hypothesis: only when anesthetic binding perturbs the channel pore or alters the channel motion, can binding generate functional consequences.
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Affiliation(s)
- Vasyl Bondarenko
- Department of Anesthesiology, University of Pittsburgh School of Medicine, USA
| | - David D Mowrey
- Department of Anesthesiology, University of Pittsburgh School of Medicine, USA; Department of Computational & Systems Biology, University of Pittsburgh School of Medicine, USA
| | - Tommy S Tillman
- Department of Anesthesiology, University of Pittsburgh School of Medicine, USA
| | - Edom Seyoum
- Department of Anesthesiology, University of Pittsburgh School of Medicine, USA
| | - Yan Xu
- Department of Anesthesiology, University of Pittsburgh School of Medicine, USA; Department of Structural Biology, University of Pittsburgh School of Medicine, USA; Department of Pharmacology & Chemical Biology, University of Pittsburgh School of Medicine, USA
| | - Pei Tang
- Department of Anesthesiology, University of Pittsburgh School of Medicine, USA; Department of Computational & Systems Biology, University of Pittsburgh School of Medicine, USA; Department of Pharmacology & Chemical Biology, University of Pittsburgh School of Medicine, USA.
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