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Brunori M. Wandering about allostery. Biol Direct 2024; 19:64. [PMID: 39113091 PMCID: PMC11308221 DOI: 10.1186/s13062-024-00502-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2024] [Accepted: 07/15/2024] [Indexed: 08/10/2024] Open
Abstract
It was a Lucky Strike to be working with Eraldo Antonini on hemoglobin and myoglobin when Jeffries Wyman arrived in Rome in 1961. I found myself connected with a number of creative scientists when the concept of allosteric control was conceived and gifted to the life science community. In retrospect, this was a demonstration of the skill and imagination of a few intelligent scientists that I happened to be close to. Those talents demonstrated the power of creativity as pictured by the motto "Mens agitat molem"; a celebration of humanism and intellect that paved the way to novel discoveries in the field of structure function relationships in proteins. I have presented hereby some of the events and the people as emerged from my memory over three decades of exciting scientific life.
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Affiliation(s)
- Maurizio Brunori
- Dipartimento di Scienze Biochimiche, Presidente emerito della Classe di Scienze FMN, Accademia Nazionale dei Lincei; Professore emerito di Chimica e Biochimica, Sapienza Università di Roma, Rome, Italy.
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2
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Paul I, Valiyev I, Ghosh A, Schmittel M. Dynamic negative allosteric effect: regulation of catalysis via multicomponent rotor speed. Chem Commun (Camb) 2024; 60:7085-7088. [PMID: 38896476 DOI: 10.1039/d4cc02144d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/21/2024]
Abstract
Nanorotor R1 (420 kHz) was assembled from five components utilizing three orthogonal interactions. Post-modification at the distal position generated the advanced six component rotor R2 (45 kHz). The decrease in R2 speed leads to the inhibition of a three-component reaction by reducing catalyst release.
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Affiliation(s)
- Indrajit Paul
- Center of Micro and Nanochemistry and (Bio)Technology, Organische Chemie I, School of Science and Technology, University of Siegen, Adolf-Reichwein-Str. 2, D-57068 Siegen, Germany.
| | - Isa Valiyev
- Center of Micro and Nanochemistry and (Bio)Technology, Organische Chemie I, School of Science and Technology, University of Siegen, Adolf-Reichwein-Str. 2, D-57068 Siegen, Germany.
| | - Amit Ghosh
- Center of Micro and Nanochemistry and (Bio)Technology, Organische Chemie I, School of Science and Technology, University of Siegen, Adolf-Reichwein-Str. 2, D-57068 Siegen, Germany.
| | - Michael Schmittel
- Center of Micro and Nanochemistry and (Bio)Technology, Organische Chemie I, School of Science and Technology, University of Siegen, Adolf-Reichwein-Str. 2, D-57068 Siegen, Germany.
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3
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Munafó JP, Biscussi B, Obiol D, Costabel M, Bouzat C, Murray AP, Antollini S. New Multitarget Molecules Derived from Caffeine as Potentiators of the Cholinergic System. ACS Chem Neurosci 2024; 15:994-1009. [PMID: 38407056 DOI: 10.1021/acschemneuro.3c00710] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/27/2024] Open
Abstract
Cholinergic deficit is a characteristic factor of several pathologies, such as myasthenia gravis, some types of congenital myasthenic syndromes, and Alzheimer's Disease. Two molecular targets for its treatment are acetylcholinesterase (AChE) and nicotinic acetylcholine receptor (nAChR). In previous studies, we found that caffeine behaves as a partial nAChR agonist and confirmed that it inhibits AChE. Here, we present new bifunctional caffeine derivatives consisting of a theophylline ring connected to amino groups by different linkers. All of them were more potent AChE inhibitors than caffeine. Furthermore, although some of them also activated muscle nAChR as partial agonists, not all of them stabilized nAChR in its desensitized conformation. To understand the molecular mechanism underlying these results, we performed docking studies on AChE and nAChR. The nAChR agonist behavior of the compounds depends on their accessory group, whereas their ability to stabilize the receptor in a desensitized state depends on the interactions of the linker at the binding site. Our results show that the new compounds can inhibit AChE and activate nAChR with greater potency than caffeine and provide further information on the modulation mechanisms of pharmacological targets for the design of novel therapeutic interventions in cholinergic deficit.
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Affiliation(s)
- Juan Pablo Munafó
- Instituto de Investigaciones Bioquímicas de Bahía Blanca, Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur and Consejo Nacional de Investigaciones Científicas y Técnicas, Camino La Carrindanga km 7, Bahía Blanca 8000, Argentina
| | - Brunella Biscussi
- Instituto de Química del Sur, Departamento de Química, Universidad Nacional del Sur and Consejo Nacional de Investigaciones Científicas y Técnicas, Avda. Alem 1253, Bahía Blanca 8000, Argentina
| | - Diego Obiol
- Grupo de Biofísica, Instituto de Física del Sur, Departamento de Física, Universidad Nacional del Sur and Consejo Nacional de Investigaciones Científicas y Técnicas, Avda. Alem 1253, Bahía Blanca 8000, Argentina
| | - Marcelo Costabel
- Grupo de Biofísica, Instituto de Física del Sur, Departamento de Física, Universidad Nacional del Sur and Consejo Nacional de Investigaciones Científicas y Técnicas, Avda. Alem 1253, Bahía Blanca 8000, Argentina
| | - Cecilia Bouzat
- Instituto de Investigaciones Bioquímicas de Bahía Blanca, Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur and Consejo Nacional de Investigaciones Científicas y Técnicas, Camino La Carrindanga km 7, Bahía Blanca 8000, Argentina
| | - Ana Paula Murray
- Instituto de Química del Sur, Departamento de Química, Universidad Nacional del Sur and Consejo Nacional de Investigaciones Científicas y Técnicas, Avda. Alem 1253, Bahía Blanca 8000, Argentina
| | - Silvia Antollini
- Instituto de Investigaciones Bioquímicas de Bahía Blanca, Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur and Consejo Nacional de Investigaciones Científicas y Técnicas, Camino La Carrindanga km 7, Bahía Blanca 8000, Argentina
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4
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Antollini SS, Barrantes FJ. Carlos Gutiérrez-Merino: Synergy of Theory and Experimentation in Biological Membrane Research. Molecules 2024; 29:820. [PMID: 38398572 PMCID: PMC10893188 DOI: 10.3390/molecules29040820] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2024] [Revised: 02/06/2024] [Accepted: 02/07/2024] [Indexed: 02/25/2024] Open
Abstract
Professor Carlos Gutiérrez-Merino, a prominent scientist working in the complex realm of biological membranes, has made significant theoretical and experimental contributions to the field. Contemporaneous with the development of the fluid-mosaic model of Singer and Nicolson, the Förster resonance energy transfer (FRET) approach has become an invaluable tool for studying molecular interactions in membranes, providing structural insights on a scale of 1-10 nm and remaining important alongside evolving perspectives on membrane structures. In the last few decades, Gutiérrez-Merino's work has covered multiple facets in the field of FRET, with his contributions producing significant advances in quantitative membrane biology. His more recent experimental work expanded the ground concepts of FRET to high-resolution cell imaging. Commencing in the late 1980s, a series of collaborations between Gutiérrez-Merino and the authors involved research visits and joint investigations focused on the nicotinic acetylcholine receptor and its relation to membrane lipids, fostering a lasting friendship.
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Affiliation(s)
- Silvia S. Antollini
- Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur, Instituto de Investigaciones Bioquímicas de Bahía Blanca (CONICET-UNS), Bahía Blanca 8000, Argentina;
| | - Francisco J. Barrantes
- Laboratory of Molecular Neurobiology, BIOMED UCA-CONICET, Buenos Aires C1107AAZ, Argentina
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5
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Yang Y, Arai T, Sasaki D, Kuramochi M, Inagaki H, Ohashi S, Sekiguchi H, Mio K, Kubo T, Sasaki YC. Real-time tilting and twisting motions of ligand-bound states of α7 nicotinic acetylcholine receptor. EUROPEAN BIOPHYSICS JOURNAL : EBJ 2024; 53:15-25. [PMID: 38233601 PMCID: PMC10853312 DOI: 10.1007/s00249-023-01693-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2023] [Revised: 11/29/2023] [Accepted: 12/01/2023] [Indexed: 01/19/2024]
Abstract
The α7 nicotinic acetylcholine receptor is a member of the nicotinic acetylcholine receptor family and is composed of five α7 subunits arranged symmetrically around a central pore. It is localized in the central nervous system and immune cells and could be a target for treating Alzheimer's disease and schizophrenia. Acetylcholine is a ligand that opens the channel, although prolonged application rapidly decreases the response. Ivermectin was reported as one of the positive allosteric modulators, since the binding of Ivermectin to the channel enhances acetylcholine-evoked α7 currents. One research has suggested that tilting motions of the nicotinic acetylcholine receptor are responsible for channel opening and activation. To verify this hypothesis applies to α7 nicotinic acetylcholine receptor, we utilized a diffracted X-ray tracking method to monitor the stable twisting and tilting motion of nAChR α7 without a ligand, with acetylcholine, with Ivermectin, and with both of them. The results show that the α7 nicotinic acetylcholine receptor twists counterclockwise with the channel transiently opening, transitioning to a desensitized state in the presence of acetylcholine and clockwise without the channel opening in the presence of Ivermectin. We propose that the conformational transition of ACh-bound nAChR α7 may be due to the collective twisting of the five α7 subunits, resulting in the compression and movement, either downward or upward, of one or more subunits, thus manifesting tilting motions. These tilting motions possibly represent the transition from the resting state to channel opening and potentially to the desensitized state.
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Affiliation(s)
- Yue Yang
- Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa, 277-8561, Japan
| | - Tatsuya Arai
- Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa, 277-8561, Japan
- AIST-UTokyo Advanced Operando-Measurement Technology Open Innovation Laboratory (OPERANDO-OIL), National Institute of Advanced Industrial Science and Technology (AIST), Kashiwa, 277-8565, Japan
| | - Daisuke Sasaki
- Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa, 277-8561, Japan
| | - Masahiro Kuramochi
- Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa, 277-8561, Japan
- Graduate School of Science and Engineering, Ibaraki University, Hitachi, 316-8511, Japan
| | - Hidetoshi Inagaki
- Biomedical Research Insitute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, 305-8566, Japan
| | - Sumiko Ohashi
- Biomedical Research Insitute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, 305-8566, Japan
| | - Hiroshi Sekiguchi
- Center for Synchrotron Radiation Research, Japan Synchrotron Radiation Research Institute, 1-1-1, Kouto, Sayo-cho, Sayo-gun, Hyogo, 679-5198, Japan
| | - Kazuhiro Mio
- AIST-UTokyo Advanced Operando-Measurement Technology Open Innovation Laboratory (OPERANDO-OIL), National Institute of Advanced Industrial Science and Technology (AIST), Kashiwa, 277-8565, Japan
| | - Tai Kubo
- Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa, 277-8561, Japan
- AIST-UTokyo Advanced Operando-Measurement Technology Open Innovation Laboratory (OPERANDO-OIL), National Institute of Advanced Industrial Science and Technology (AIST), Kashiwa, 277-8565, Japan
| | - Yuji C Sasaki
- Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa, 277-8561, Japan.
- AIST-UTokyo Advanced Operando-Measurement Technology Open Innovation Laboratory (OPERANDO-OIL), National Institute of Advanced Industrial Science and Technology (AIST), Kashiwa, 277-8565, Japan.
- Center for Synchrotron Radiation Research, Japan Synchrotron Radiation Research Institute, 1-1-1, Kouto, Sayo-cho, Sayo-gun, Hyogo, 679-5198, Japan.
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6
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Stereoselective Synthesis of 1-Substituted Homotropanones, including Natural Alkaloid (-)-Adaline. Molecules 2023; 28:molecules28052414. [PMID: 36903657 PMCID: PMC10005508 DOI: 10.3390/molecules28052414] [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: 02/16/2023] [Revised: 03/01/2023] [Accepted: 03/03/2023] [Indexed: 03/09/2023] Open
Abstract
The stereocontrolled synthesis of 1-substituted homotropanones, using chiral N-tert-butanesulfinyl imines as reaction intermediates, is described. The reaction of organolithium and Grignard reagents with hydroxy Weinreb amides, chemoselective N-tert-butanesulfinyl aldimine formation from keto aldehydes, decarboxylative Mannich reaction with β-keto acids of these aldimines, and organocatalyzed L-proline intramolecular Mannich cyclization are key steps of this methodology. The utility of the method was demonstrated with a synthesis of the natural product (-)-adaline, and its enantiomer, (+)-adaline.
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7
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Kundu S, Mondal D, Elramadi E, Valiyev I, Schmittel M. Parallel Allosteric Inhibition of Shuttling Motion and Catalysis in a Silver(I)-loaded [2]Rotaxane. Org Lett 2022; 24:6609-6613. [PMID: 36053156 DOI: 10.1021/acs.orglett.2c02609] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
A dynamic silver(I)-loaded [2]rotaxane shuttle (k298 = 135 kHz) was converted allosterically into a conformationally restricted [2]rotaxane due to the creation of a bulky imine in the center of the axle component. Only the dynamic silver(I)-loaded [2]rotaxane was able to catalyze a 6-endo-cyclization reaction, whereas the static one was catalytically quiet. The mechanism of catalyst deactivation was elucidated.
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Affiliation(s)
- Sohom Kundu
- Center of Micro- and Nanochemistry and (Bio)Technology, Universität Siegen, Organische Chemie I, Adolf-Reichwein-Str. 2, D-57068 Siegen, Germany
| | - Debabrata Mondal
- Center of Micro- and Nanochemistry and (Bio)Technology, Universität Siegen, Organische Chemie I, Adolf-Reichwein-Str. 2, D-57068 Siegen, Germany
| | - Emad Elramadi
- Center of Micro- and Nanochemistry and (Bio)Technology, Universität Siegen, Organische Chemie I, Adolf-Reichwein-Str. 2, D-57068 Siegen, Germany
| | - Isa Valiyev
- Center of Micro- and Nanochemistry and (Bio)Technology, Universität Siegen, Organische Chemie I, Adolf-Reichwein-Str. 2, D-57068 Siegen, Germany
| | - Michael Schmittel
- Center of Micro- and Nanochemistry and (Bio)Technology, Universität Siegen, Organische Chemie I, Adolf-Reichwein-Str. 2, D-57068 Siegen, Germany
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8
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Membrane lipid organization and nicotinic acetylcholine receptor function: A two-way physiological relationship. Arch Biochem Biophys 2022; 730:109413. [DOI: 10.1016/j.abb.2022.109413] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Revised: 09/07/2022] [Accepted: 09/20/2022] [Indexed: 11/21/2022]
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9
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Coleman BD, d'Aquino AI, Kean Z, Wang Y, Hedlund Orbeck JK, Stern CL, Mirkin CA. Structurally Dynamic Crystalline 1D Coordination Polymers Enabled via the Weak-Link Approach. Polyhedron 2022. [DOI: 10.1016/j.poly.2022.116116] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
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10
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Yu J, Zhu H, Lape R, Greiner T, Du J, Lü W, Sivilotti L, Gouaux E. Mechanism of gating and partial agonist action in the glycine receptor. Cell 2021; 184:957-968.e21. [PMID: 33567265 PMCID: PMC8115384 DOI: 10.1016/j.cell.2021.01.026] [Citation(s) in RCA: 68] [Impact Index Per Article: 22.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Revised: 10/16/2020] [Accepted: 01/15/2021] [Indexed: 12/14/2022]
Abstract
Ligand-gated ion channels mediate signal transduction at chemical synapses and transition between resting, open, and desensitized states in response to neurotransmitter binding. Neurotransmitters that produce maximum open channel probabilities (Po) are full agonists, whereas those that yield lower than maximum Po are partial agonists. Cys-loop receptors are an important class of neurotransmitter receptors, yet a structure-based understanding of the mechanism of partial agonist action has proven elusive. Here, we study the glycine receptor with the full agonist glycine and the partial agonists taurine and γ-amino butyric acid (GABA). We use electrophysiology to show how partial agonists populate agonist-bound, closed channel states and cryo-EM reconstructions to illuminate the structures of intermediate, pre-open states, providing insights into previously unseen conformational states along the receptor reaction pathway. We further correlate agonist-induced conformational changes to Po across members of the receptor family, providing a hypothetical mechanism for partial and full agonist action at Cys-loop receptors.
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Affiliation(s)
- Jie Yu
- Vollum Institute, Oregon Health & Science University, Portland, OR 97239, USA
| | - Hongtao Zhu
- Vollum Institute, Oregon Health & Science University, Portland, OR 97239, USA
| | - Remigijus Lape
- Department of Neuroscience, Physiology and Pharmacology, University College London, Medical Sciences Building, Gower Street, London WC1E 6BT, UK
| | - Timo Greiner
- Department of Neuroscience, Physiology and Pharmacology, University College London, Medical Sciences Building, Gower Street, London WC1E 6BT, UK
| | - Juan Du
- Vollum Institute, Oregon Health & Science University, Portland, OR 97239, USA
| | - Wei Lü
- Vollum Institute, Oregon Health & Science University, Portland, OR 97239, USA
| | - Lucia Sivilotti
- Department of Neuroscience, Physiology and Pharmacology, University College London, Medical Sciences Building, Gower Street, London WC1E 6BT, UK.
| | - Eric Gouaux
- Vollum Institute, Oregon Health & Science University, Portland, OR 97239, USA; Howard Hughes Medical Institute, Oregon Health & Science University, Portland, OR 97239, USA.
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11
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Cao Y, Tian R, Jiao Y, Zheng Z, Wang Q, Deng Y, Du X. Novel nicotinic acetylcholine receptor involved in immune regulation in pearl oyster (Pinctada fucata martensii). Comp Biochem Physiol B Biochem Mol Biol 2021; 252:110512. [DOI: 10.1016/j.cbpb.2020.110512] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Revised: 09/16/2020] [Accepted: 09/29/2020] [Indexed: 01/31/2023]
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12
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Wang SC, Cheng KY, Fu JH, Cheng YC, Chan YT. Conformational Regulation of Multivalent Terpyridine Ligands for Self-Assembly of Heteroleptic Metallo-Supramolecules. J Am Chem Soc 2020; 142:16661-16667. [PMID: 32881485 DOI: 10.1021/jacs.0c06618] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
A two-ligand system composed of the predesigned multivalent and complementary terpyridine-based ligands was exploited to construct heteroleptic metallo-supramolecules and to investigate the self-assembly mechanism. Molecular stellation of the trimeric hexagon [Cd6L23] gave rise to the exclusive self-assembly of the star hexagon [Cd18L16L33] through complementary ligand pairing between the ditopic and octatopic tectons. To understand how the intermolecular heteroleptic complexation influenced the self-assembly pathway, the star hexagon was truncated into two triangular fragments: [Cd12L13L43] and [Cd12L13L53]. In the self-assembly of [Cd12L13L43], the conformational movements of hexatopic ligand L4 could be regulated by L1 to promote the subsequent coordination event, which was the key step to the successful multicomponent self-assembly. In contrast, the formation of [Cd12L13L53] was hampered by the geometrically mismatched intermediates.
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Affiliation(s)
- Shi-Cheng Wang
- Department of Chemistry, National Taiwan University, Taipei 10617, Taiwan
| | - Kai-Yu Cheng
- Department of Chemistry, National Taiwan University, Taipei 10617, Taiwan
| | - Jun-Hao Fu
- Department of Chemistry, National Taiwan University, Taipei 10617, Taiwan
| | - Yuan-Chung Cheng
- Department of Chemistry, National Taiwan University, Taipei 10617, Taiwan
| | - Yi-Tsu Chan
- Department of Chemistry, National Taiwan University, Taipei 10617, Taiwan
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Moerke MJ, McMahon LR, Wilkerson JL. More than Smoke and Patches: The Quest for Pharmacotherapies to Treat Tobacco Use Disorder. Pharmacol Rev 2020; 72:527-557. [PMID: 32205338 DOI: 10.1124/pr.119.018028] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Tobacco use is a persistent public health issue. It kills up to half its users and is the cause of nearly 90% of all lung cancers. The main psychoactive component of tobacco is nicotine, primarily responsible for its abuse-related effects. Accordingly, most pharmacotherapies for smoking cessation target nicotinic acetylcholine receptors (nAChRs), nicotine's major site of action in the brain. The goal of the current review is twofold: first, to provide a brief overview of the most commonly used behavioral procedures for evaluating smoking cessation pharmacotherapies and an introduction to pharmacokinetic and pharmacodynamic properties of nicotine important for consideration in the development of new pharmacotherapies; and second, to discuss current and potential future pharmacological interventions aimed at decreasing tobacco use. Attention will focus on the potential for allosteric modulators of nAChRs to offer an improvement over currently approved pharmacotherapies. Additionally, given increasing public concern for the potential health consequences of using electronic nicotine delivery systems, which allow users to inhale aerosolized solutions as an alternative to smoking tobacco, an effort will be made throughout this review to address the implications of this relatively new form of nicotine delivery, specifically as it relates to smoking cessation. SIGNIFICANCE STATEMENT: Despite decades of research that have vastly improved our understanding of nicotine and its effects on the body, only a handful of pharmacotherapies have been successfully developed for use in smoking cessation. Thus, investigation of alternative pharmacological strategies for treating tobacco use disorder remains active; allosteric modulators of nicotinic acetylcholine receptors represent one class of compounds currently under development for this purpose.
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Affiliation(s)
- M J Moerke
- Division of Preclinical Pharmacology, National Institute on Drug Abuse, National Institutes of Health, Baltimore, Maryland (M.J.M.) and Department of Pharmacodynamics, College of Pharmacy, University of Florida, Gainesville, Florida (L.R.M., J.L.W.)
| | - L R McMahon
- Division of Preclinical Pharmacology, National Institute on Drug Abuse, National Institutes of Health, Baltimore, Maryland (M.J.M.) and Department of Pharmacodynamics, College of Pharmacy, University of Florida, Gainesville, Florida (L.R.M., J.L.W.)
| | - J L Wilkerson
- Division of Preclinical Pharmacology, National Institute on Drug Abuse, National Institutes of Health, Baltimore, Maryland (M.J.M.) and Department of Pharmacodynamics, College of Pharmacy, University of Florida, Gainesville, Florida (L.R.M., J.L.W.)
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14
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Houchat JN, Cartereau A, Le Mauff A, Taillebois E, Thany SH. An Overview on the Effect of Neonicotinoid Insecticides on Mammalian Cholinergic Functions through the Activation of Neuronal Nicotinic Acetylcholine Receptors. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2020; 17:ijerph17093222. [PMID: 32384754 PMCID: PMC7246883 DOI: 10.3390/ijerph17093222] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Revised: 04/27/2020] [Accepted: 04/30/2020] [Indexed: 01/04/2023]
Abstract
Neonicotinoid insecticides are used worldwide and have been demonstrated as toxic to beneficial insects such as honeybees. Their effectiveness is predominantly attributed to their high affinity for insect neuronal nicotinic acetylcholine receptors (nAChRs). Mammalian neuronal nAChRs are of major importance because cholinergic synaptic transmission plays a key role in rapid neurotransmission, learning and memory processes, and neurodegenerative diseases. Because of the low agonist effects of neonicotinoid insecticides on mammalian neuronal nAChRs, it has been suggested that they are relatively safe for mammals, including humans. However, several lines of evidence have demonstrated that neonicotinoid insecticides can modulate cholinergic functions through neuronal nAChRs. Major studies on the influence of neonicotinoid insecticides on cholinergic functions have been conducted using nicotine low-affinity homomeric α7 and high-affinity heteromeric α4β2 receptors, as they are the most abundant in the nervous system. It has been found that the neonicotinoids thiamethoxam and clothianidin can activate the release of dopamine in rat striatum. In some contexts, such as neurodegenerative diseases, they can disturb the neuronal distribution or induce oxidative stress, leading to neurotoxicity. This review highlights recent studies on the mode of action of neonicotinoid insecticides on mammalian neuronal nAChRs and cholinergic functions.
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15
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Pandhare A, Pirayesh E, Stuebler AG, Jansen M. Triple arginines as molecular determinants for pentameric assembly of the intracellular domain of 5-HT 3A receptors. J Gen Physiol 2019; 151:1135-1145. [PMID: 31409663 PMCID: PMC6719409 DOI: 10.1085/jgp.201912421] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2019] [Accepted: 07/15/2019] [Indexed: 11/20/2022] Open
Abstract
Serotonin type 3A receptors are homopentameric ligand-gated ion channels that are thought to assemble via interactions involving the subunits’ extracellular and transmembrane domains. Pandhare et al. reveal that channel assembly is also determined by three arginine residues in the receptor’s intracellular domain. Serotonin type 3 receptors (5-HT3Rs) are cation-conducting pentameric ligand-gated ion channels and members of the Cys-loop superfamily in eukaryotes. 5-HT3Rs are found in the peripheral and central nervous system, and they are targets for drugs used to treat anxiety, drug dependence, and schizophrenia, as well as chemotherapy-induced and postoperative nausea and emesis. Decades of research of Cys-loop receptors have identified motifs in both the extracellular and transmembrane domains that mediate pentameric assembly. Those efforts have largely ignored the most diverse domain of these channels, the intracellular domain (ICD). Here we identify molecular determinants within the ICD of serotonin type 3A (5-HT3A) subunits for pentameric assembly by first identifying the segments contributing to pentamerization using deletion constructs of, and finally by making defined amino acid substitutions within, an isolated soluble ICD. Our work provides direct experimental evidence for the contribution of three intracellular arginines, previously implicated in governing the low conductance of 5-HT3ARs, in structural features such as pentameric assembly.
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Affiliation(s)
- Akash Pandhare
- Department of Cell Physiology and Molecular Biophysics and Center for Membrane Protein Research, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX
| | - Elham Pirayesh
- Department of Cell Physiology and Molecular Biophysics and Center for Membrane Protein Research, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX
| | - Antonia G Stuebler
- Department of Cell Physiology and Molecular Biophysics and Center for Membrane Protein Research, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX
| | - Michaela Jansen
- Department of Cell Physiology and Molecular Biophysics and Center for Membrane Protein Research, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX
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Silva GM, Barcelos MP, Poiani JGC, Hage-Melim LIDS, da Silva CHTDP. Allosteric Modulators of Potential Targets Related to Alzheimer's Disease: a Review. ChemMedChem 2019; 14:1467-1483. [PMID: 31310701 DOI: 10.1002/cmdc.201900299] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Revised: 07/05/2019] [Indexed: 12/15/2022]
Abstract
Among neurodegenerative disorders, Alzheimer's disease (AD) is the most common type of dementia, and there is an urgent need to discover new and efficacious forms of treatment for it. Pathological patterns of AD include cholinergic dysfunction, increased β-amyloid (Aβ) peptide concentration, the appearance of neurofibrillary tangles, among others, all of which are strongly associated with specific biological targets. Interactions observed between these targets and potential drug candidates in AD most often occur by competitive mechanisms driven by orthosteric ligands that sometimes result in the production of side effects. In this context, the allosteric mechanism represents a key strategy; this can be regarded as the selective modulation of such targets by allosteric modulators in an advantageous manner, as this may decrease the likelihood of side effects. The purpose of this review is to present an overview of compounds that act as allosteric modulators of the main biological targets related to AD.
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Affiliation(s)
- Guilherme Martins Silva
- Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Av. do Café, s/n, 14040-903, Ribeirão Preto, Brazil.,Departamento de Química, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Av. Bandeirantes, 3900, 14090-901, Ribeirão Preto, Brazil
| | - Mariana Pegrucci Barcelos
- Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Av. do Café, s/n, 14040-903, Ribeirão Preto, Brazil.,Departamento de Química, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Av. Bandeirantes, 3900, 14090-901, Ribeirão Preto, Brazil
| | - João Gabriel Curtolo Poiani
- Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Av. do Café, s/n, 14040-903, Ribeirão Preto, Brazil
| | - Lorane Izabel da Silva Hage-Melim
- Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Av. do Café, s/n, 14040-903, Ribeirão Preto, Brazil.,Departamento de Ciências Biológicas e da Saúde, Curso de Farmácia, Universidade Federal do Amapá, Rod. Juscelino Kubitschek, KM-02, 68903-419, Macapá, Brazil
| | - Carlos Henrique Tomich de Paula da Silva
- Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Av. do Café, s/n, 14040-903, Ribeirão Preto, Brazil.,Departamento de Química, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Av. Bandeirantes, 3900, 14090-901, Ribeirão Preto, Brazil
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17
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Fabiani C, Antollini SS. Alzheimer's Disease as a Membrane Disorder: Spatial Cross-Talk Among Beta-Amyloid Peptides, Nicotinic Acetylcholine Receptors and Lipid Rafts. Front Cell Neurosci 2019; 13:309. [PMID: 31379503 PMCID: PMC6657435 DOI: 10.3389/fncel.2019.00309] [Citation(s) in RCA: 90] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Accepted: 06/25/2019] [Indexed: 12/17/2022] Open
Abstract
Biological membranes show lateral and transverse asymmetric lipid distribution. Cholesterol (Chol) localizes in both hemilayers, but in the external one it is mostly condensed in lipid-ordered microdomains (raft domains), together with saturated phosphatidyl lipids and sphingolipids (including sphingomyelin and glycosphingolipids). Membrane asymmetries induce special membrane biophysical properties and behave as signals for several physiological and/or pathological processes. Alzheimer’s disease (AD) is associated with a perturbation in different membrane properties. Amyloid-β (Aβ) plaques and neurofibrillary tangles of tau protein together with neuroinflammation and neurodegeneration are the most characteristic cellular changes observed in this disease. The extracellular presence of Aβ peptides forming senile plaques, together with soluble oligomeric species of Aβ, are considered the major cause of the synaptic dysfunction of AD. The association between Aβ peptide and membrane lipids has been extensively studied. It has been postulated that Chol content and Chol distribution condition Aβ production and posterior accumulation in membranes and, hence, cell dysfunction. Several lines of evidence suggest that Aβ partitions in the cell membrane accumulate mostly in raft domains, the site where the cleavage of the precursor AβPP by β- and γ- secretase is also thought to occur. The main consequence of the pathogenesis of AD is the disruption of the cholinergic pathways in the cerebral cortex and in the basal forebrain. In parallel, the nicotinic acetylcholine receptor has been extensively linked to membrane properties. Since its transmembrane domain exhibits extensive contacts with the surrounding lipids, the acetylcholine receptor function is conditioned by its lipid microenvironment. The nicotinic acetylcholine receptor is present in high-density clusters in the cell membrane where it localizes mainly in lipid-ordered domains. Perturbations of sphingomyelin or cholesterol composition alter acetylcholine receptor location. Therefore, Aβ processing, Aβ partitioning, and acetylcholine receptor location and function can be manipulated by changes in membrane lipid biophysics. Understanding these mechanisms should provide insights into new therapeutic strategies for prevention and/or treatment of AD. Here, we discuss the implications of lipid-protein interactions at the cell membrane level in AD.
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Affiliation(s)
- Camila Fabiani
- Instituto de Investigaciones Bioquímicas de Bahía Blanca CONICET-UNS, Bahía Blanca, Argentina.,Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur, Bahía Blanca, Argentina
| | - Silvia S Antollini
- Instituto de Investigaciones Bioquímicas de Bahía Blanca CONICET-UNS, Bahía Blanca, Argentina.,Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur, Bahía Blanca, Argentina
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18
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Rodríguez-Soacha DA, Scheiner M, Decker M. Multi-target-directed-ligands acting as enzyme inhibitors and receptor ligands. Eur J Med Chem 2019; 180:690-706. [PMID: 31401465 DOI: 10.1016/j.ejmech.2019.07.040] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2019] [Revised: 07/04/2019] [Accepted: 07/11/2019] [Indexed: 12/20/2022]
Abstract
In this review, we present the latest advances in the field of multi-target-directed ligand (MTDL) design for the treatment of various complex pathologies of multifactorial origin. In particular, latest findings in the field of MTDL design targeting both an enzyme and a receptor are presented for different diseases such as Alzheimer's disease (AD), depression, addiction, glaucoma, non-alcoholic steatohepatitis and pain and inflammation. The ethology of the diseases is briefly described, with special emphasis on how the MTDL can evolve into novel therapies that replace the classic pharmacological dogma "one target one disease". Considering the current needs for therapy adherence improvement, it is exposed as from the medicinal chemistry, different molecular scaffolds are studied. With the use of structure activity relationship studies and molecular optimization, new hybrid molecules are generated with improved biological properties acting at two biologically very distinct targets.
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Affiliation(s)
- Diego Alejandro Rodríguez-Soacha
- Pharmaceutical and Medicinal Chemistry, Institute of Pharmacy and Food Chemistry, Julius Maximilian University of Würzburg, Am Hubland, 97074, Würzburg, Germany
| | - Matthias Scheiner
- Pharmaceutical and Medicinal Chemistry, Institute of Pharmacy and Food Chemistry, Julius Maximilian University of Würzburg, Am Hubland, 97074, Würzburg, Germany
| | - Michael Decker
- Pharmaceutical and Medicinal Chemistry, Institute of Pharmacy and Food Chemistry, Julius Maximilian University of Würzburg, Am Hubland, 97074, Würzburg, Germany.
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19
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Vivekanandarajah A, Waters KA, Machaalani R. Cigarette smoke exposure effects on the brainstem expression of nicotinic acetylcholine receptors (nAChRs), and on cardiac, respiratory and sleep physiologies. Respir Physiol Neurobiol 2018; 259:1-15. [PMID: 30031221 DOI: 10.1016/j.resp.2018.07.007] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Revised: 07/16/2018] [Accepted: 07/17/2018] [Indexed: 12/15/2022]
Abstract
Cigarette smoking during pregnancy is the largest modifiable risk factor for adverse outcomes in the infant. Investigations have focused on the psychoactive component of cigarettes, nicotine. One proposed mechanism leading to adverse effects is the interaction between nicotine and its nicotinic acetylcholine receptors (nAChRs). Much data has been generated over the past three decades on the effects of cigarette smoke exposure (CSE) on the expression of the nAChRs in the brainstem and physiological parameters related to cardiac, respiration and sleep, in the offspring of smoking mothers and animal models of nicotine exposure. This review summarises this data and discusses the main findings, highlighting that findings in animal models closely correlate with those from human studies, and that the major brainstem sites where the expression level for the nAChRs are consistently affected include those that play vital roles in cardiorespiration (hypoglossal nucleus, dorsal motor nucleus of the vagus, nucleus of the solitary tract), chemosensation (nucleus of the solitary tract, arcuate nucleus) and arousal (rostral mesopontine sites such as the locus coeruleus and nucleus pontis oralis). These findings provide evidence for the adverse effects of CSE during and after pregnancy to the infant and the need to continue with the health campaign advising against CSE.
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Affiliation(s)
- Arunnjah Vivekanandarajah
- SIDS and Sleep Apnea Laboratory, Sydney Medical School, Medical Foundation Building K25, University of Sydney, NSW 2006, Australia.
| | - Karen A Waters
- SIDS and Sleep Apnea Laboratory, Sydney Medical School, Medical Foundation Building K25, University of Sydney, NSW 2006, Australia; Discipline of Paediatrics and Child Health, Children's Hospital Westmead, NSW, Australia
| | - Rita Machaalani
- SIDS and Sleep Apnea Laboratory, Sydney Medical School, Medical Foundation Building K25, University of Sydney, NSW 2006, Australia; Discipline of Paediatrics and Child Health, Children's Hospital Westmead, NSW, Australia
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20
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Amundarain MJ, Viso JF, Zamarreño F, Giorgetti A, Costabel M. Orthosteric and benzodiazepine cavities of the α 1β 2γ 2 GABA A receptor: insights from experimentally validated in silico methods. J Biomol Struct Dyn 2018; 37:1597-1615. [PMID: 29633901 DOI: 10.1080/07391102.2018.1462733] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
γ-aminobutyric acid-type A (GABAA) receptors mediate fast synaptic inhibition in the central nervous system of mammals. They are modulated via several sites by numerous compounds, which include GABA, benzodiazepines, ethanol, neurosteroids and anaesthetics among others. Due to their potential as targets of novel drugs, a detailed knowledge of their structure-function relationships is needed. Here, we present the model of the α1β2γ2 subtype GABAA receptor in the APO state and in complex with selected ligands, including agonists, antagonists and allosteric modulators. The model is based on the crystallographic structure of the human β3 homopentamer GABAA receptor. The complexes were refined using atomistic molecular dynamics simulations. This allowed a broad description of the binding modes and the detection of important interactions in agreement with experimental information. From the best of our knowledge, this is the only model of the α1β2γ2 GABAA receptor that represents altogether the desensitized state of the channel and comprehensively describes the interactions of ligands of the orthosteric and benzodiazepines binding sites in agreement with the available experimental data. Furthermore, it is able to explain small differences regarding the binding of a variety of chemically divergent ligands. Finally, this new model may pave the way for the design of focused experimental studies that will allow a deeper description of the receptor.
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Affiliation(s)
- María Julia Amundarain
- a Departamento de Física, Instituto de Física del Sur (IFISUR) , Universidad Nacional del Sur (UNS), CONICET , Bahía Blanca , Argentina
| | - Juan Francisco Viso
- a Departamento de Física, Instituto de Física del Sur (IFISUR) , Universidad Nacional del Sur (UNS), CONICET , Bahía Blanca , Argentina
| | - Fernando Zamarreño
- a Departamento de Física, Instituto de Física del Sur (IFISUR) , Universidad Nacional del Sur (UNS), CONICET , Bahía Blanca , Argentina
| | - Alejandro Giorgetti
- b Faculty of Mathematical, Physical and Natural Sciences, Department of Biotechnology , University of Verona , Verona , Italy.,c Computational Biomedicine, Institute for Advanced Simulation IAS-5 and Computational Biomedicine, Institute of Neuroscience and Medicine INM-9 , Forschungszentrum Jülich , Jülich , Germany
| | - Marcelo Costabel
- a Departamento de Física, Instituto de Física del Sur (IFISUR) , Universidad Nacional del Sur (UNS), CONICET , Bahía Blanca , Argentina
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21
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Akk G, Shin DJ, Germann AL, Steinbach JH. GABA Type A Receptor Activation in the Allosteric Coagonist Model Framework: Relationship between EC 50 and Basal Activity. Mol Pharmacol 2017; 93:90-100. [PMID: 29150461 DOI: 10.1124/mol.117.110569] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2017] [Accepted: 11/15/2017] [Indexed: 01/08/2023] Open
Abstract
The concerted transition model for multimeric proteins is a simple formulation for analyzing the behavior of transmitter-gated ion channels. We used the model to examine the relationship between the EC50 for activation of the GABA type A (GABAA) receptor by the transmitter GABA and basal activity employing concatemeric ternary GABAA receptors expressed in Xenopus oocytes. Basal activity, reflecting the receptor function in the absence of the transmitter, can be changed either by mutation to increase constitutive activity or by the addition of a second agonist (acting at a different site) to increase background activity. The model predicts that either mechanism for producing a change in basal activity will result in identical effects on the EC50 We examined receptor activation by GABA while changing the level of basal activity with the allosterically acting anesthetics propofol, pentobarbital, or alfaxalone. We found that the relationship between EC50 and basal activity was well described by the concerted transition model. Changes in the basal activity by gain-of-function mutations also resulted in predictable changes in the EC50 Finally, we altered the number of GABA-binding sites by a mutation and again found that the relationship could be well described by the model. Overall, the results support the idea that interactions between the transmitter GABA and the allosteric agonists propofol, pentobarbital, or alfaxalone can be understood as reflecting additive and independent free energy changes, without assuming any specific interactions.
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Affiliation(s)
- Gustav Akk
- Department of Anesthesiology (G.A., D.J.S., A.L.G., J.H.S.) and Taylor Family Institute for Innovative Psychiatric Research (G.A., J.H.S.), Washington University School of Medicine, St. Louis, Missouri
| | - Daniel J Shin
- Department of Anesthesiology (G.A., D.J.S., A.L.G., J.H.S.) and Taylor Family Institute for Innovative Psychiatric Research (G.A., J.H.S.), Washington University School of Medicine, St. Louis, Missouri
| | - Allison L Germann
- Department of Anesthesiology (G.A., D.J.S., A.L.G., J.H.S.) and Taylor Family Institute for Innovative Psychiatric Research (G.A., J.H.S.), Washington University School of Medicine, St. Louis, Missouri
| | - Joe Henry Steinbach
- Department of Anesthesiology (G.A., D.J.S., A.L.G., J.H.S.) and Taylor Family Institute for Innovative Psychiatric Research (G.A., J.H.S.), Washington University School of Medicine, St. Louis, Missouri
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22
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Prinston JE, Emlaw JR, Dextraze MF, Tessier CJG, Pérez-Areales FJ, McNulty MS, daCosta CJB. Ancestral Reconstruction Approach to Acetylcholine Receptor Structure and Function. Structure 2017; 25:1295-1302.e3. [PMID: 28689969 DOI: 10.1016/j.str.2017.06.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2017] [Revised: 05/10/2017] [Accepted: 06/08/2017] [Indexed: 12/23/2022]
Abstract
Acetylcholine receptors (AChRs) are members of a superfamily of proteins called pentameric ligand-gated ion channels, which are found in almost all forms of life and thus have a rich evolutionary history. Muscle-type AChRs are heteropentameric complexes assembled from four related subunits (α, β, δ, and ɛ). Here we reconstruct the amino acid sequence of a β subunit ancestor shared by humans and cartilaginous fishes (i.e., Torpedo). Then, by resurrecting this ancestral β subunit and co-expressing it with human α, δ, and ɛ subunits, we show that despite 132 substitutions, the ancestral subunit is capable of forming human/ancestral hybrid AChRs. Whole-cell currents demonstrate that the agonist acetylcholine has reduced potency for hybrid receptors, while single-channel recordings reveal that hybrid receptors display reduced conductance and open probability. Our results outline a promising strategy for studies of AChR evolution aimed at identifying the amino acid origins of AChR structure and function.
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Affiliation(s)
- Jethro E Prinston
- Department of Chemistry and Biomolecular Sciences, Centre for Chemical and Synthetic Biology, University of Ottawa, 10 Marie-Curie, Ottawa, ON K1N 6N5, Canada
| | - Johnathon R Emlaw
- Department of Chemistry and Biomolecular Sciences, Centre for Chemical and Synthetic Biology, University of Ottawa, 10 Marie-Curie, Ottawa, ON K1N 6N5, Canada
| | - Mathieu F Dextraze
- Department of Chemistry and Biomolecular Sciences, Centre for Chemical and Synthetic Biology, University of Ottawa, 10 Marie-Curie, Ottawa, ON K1N 6N5, Canada
| | - Christian J G Tessier
- Department of Chemistry and Biomolecular Sciences, Centre for Chemical and Synthetic Biology, University of Ottawa, 10 Marie-Curie, Ottawa, ON K1N 6N5, Canada
| | - F Javier Pérez-Areales
- Department of Chemistry and Biomolecular Sciences, Centre for Chemical and Synthetic Biology, University of Ottawa, 10 Marie-Curie, Ottawa, ON K1N 6N5, Canada
| | - Melissa S McNulty
- Department of Chemistry and Biomolecular Sciences, Centre for Chemical and Synthetic Biology, University of Ottawa, 10 Marie-Curie, Ottawa, ON K1N 6N5, Canada
| | - Corrie J B daCosta
- Department of Chemistry and Biomolecular Sciences, Centre for Chemical and Synthetic Biology, University of Ottawa, 10 Marie-Curie, Ottawa, ON K1N 6N5, Canada.
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23
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A Novel Lid-Covering Peptide Inhibitor of Nicotinic Acetylcholine Receptors Derived from αD-Conotoxin GeXXA. Mar Drugs 2017; 15:md15060164. [PMID: 28587231 PMCID: PMC5484114 DOI: 10.3390/md15060164] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Revised: 05/28/2017] [Accepted: 05/31/2017] [Indexed: 12/12/2022] Open
Abstract
Nicotinic acetylcholine receptors (nAChRs) play a fundamental role in nervous signal transmission, therefore various antagonists and agonists are highly desired to explore the structure and function of nAChRs. Recently, a novel dimeric αD-conotoxin GeXXA was identified to inhibit nAChRs by binding at the top surface of the receptors, and the monomeric C-terminal domain (CTD) of αD-GeXXA retains some inhibitory activity. In this study, the internal dimeric N-terminal domain (NTD) of this conopeptide was further investigated. We first developed a regio-selective protection strategy to chemically prepare the anti-parallel dimeric NTD, and found that the isolated NTD part of GeXXA possesses the nAChR-inhibitory activity, the subtype-dependence of which implies a preferred binding of NTD to the β subunits of nAChR. Deletion of the NTD N-terminal residues did not affect the activity of NTD, indicating that the N-terminus is not involved in the interaction with nAChRs. By optimizing the sequence of NTD, we obtained a fully active single-chain cyclic NTD, based on which 4 Arg residues were found to interact with nAChRs. These results demonstrate that the NTD part of αD-GeXXA is a “lid-covering” nAChR inhibitor, displaying a novel inhibitory mechanism distinct from other allosteric ligands of nAChRs.
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24
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Mariottini D, Idili A, Vallée-Bélisle A, Plaxco KW, Ricci F. A DNA Nanodevice That Loads and Releases a Cargo with Hemoglobin-Like Allosteric Control and Cooperativity. NANO LETTERS 2017; 17:3225-3230. [PMID: 28387120 DOI: 10.1021/acs.nanolett.7b00814] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Here we report the rational design of a synthetic molecular nanodevice that is directly inspired from hemoglobin, a highly evolved protein whose oxygen-carrying activity is finely regulated by a sophisticated network of control mechanisms. Inspired by the impressive performance of hemoglobin we have designed and engineered in vitro a synthetic DNA-based nanodevice containing up to four interacting binding sites that, like hemoglobin, can load and release a cargo over narrow concentration ranges, and whose affinity can be finely controlled via both allosteric effectors and environmental cues like pH and temperature. As the first example of a synthetic DNA nanodevice that undergoes a complex network of nature-inspired control mechanisms, this represents an important step toward the use of similar nanodevices for diagnostic and drug-delivery applications.
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Affiliation(s)
- Davide Mariottini
- Department of Chemistry, University of Rome, Tor Vergata , Via della Ricerca Scientifica, 00133, Rome, Italy
| | - Andrea Idili
- Department of Chemistry, University of Rome, Tor Vergata , Via della Ricerca Scientifica, 00133, Rome, Italy
| | - Alexis Vallée-Bélisle
- Laboratory of Biosensors & Nanomachines, Département de Chimie, Université de Montréal , C.P. 6128, Succursale Centre-Ville, Montréal, Québec, Canada H3C 3J7
| | | | - Francesco Ricci
- Department of Chemistry, University of Rome, Tor Vergata , Via della Ricerca Scientifica, 00133, Rome, Italy
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Degennaro L, Zenzola M, Laurino A, Cavalluzzi MM, Franchini C, Habtemariam S, Matucci R, Luisi R, Lentini G. 2-Arylazetidines as ligands for nicotinic acetylcholine receptors. Chem Heterocycl Compd (N Y) 2017. [DOI: 10.1007/s10593-017-2061-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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26
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Tolu S, Marti F, Morel C, Perrier C, Torquet N, Pons S, de Beaurepaire R, Faure P. Nicotine enhances alcohol intake and dopaminergic responses through β2* and β4* nicotinic acetylcholine receptors. Sci Rep 2017; 7:45116. [PMID: 28332590 PMCID: PMC5362818 DOI: 10.1038/srep45116] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2016] [Accepted: 02/17/2017] [Indexed: 12/25/2022] Open
Abstract
Alcohol and nicotine are the most widely co-abused drugs. Both modify the activity of dopaminergic (DA) neurons of the Ventral Tegmental Area (VTA) and lead to an increase in DA release in the Nucleus Accumbens, thereby affecting the reward system. Evidences support the hypothesis that distinct nicotinic acetylcholine receptors (nAChRs), the molecular target of acetylcholine (ACh) and exogenous nicotine, are also in addition implicated in the response to alcohol. The precise molecular and neuronal substrates of this interaction are however not well understood. Here we used in vivo electrophysiology in the VTA to characterise acute and chronic interactions between nicotine and alcohol. Simultaneous injections of the two drugs enhanced their responses on VTA DA neuron firing and chronic exposure to nicotine increased alcohol-induced DA responses and alcohol intake. Then, we assessed the role of β4 * nAChRs, but not β2 * nAChRs, in mediating acute responses to alcohol using nAChR subtypes knockout mice (β2-/- and β4-/- mice). Finally, we showed that nicotine-induced modifications of alcohol responses were absent in β2-/- and β4-/- mice, suggesting that nicotine triggers β2* and β4 * nAChR-dependent neuroadaptations that subsequently modify the responses to alcohol and thus indicating these receptors as key mediators in the complex interactions between these two drugs.
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Affiliation(s)
- Stefania Tolu
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, CNRS, Neurosciences Paris Seine - Institut de Biologie Paris Seine (NPS - IBPS), 75005, Paris, France
| | - Fabio Marti
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, CNRS, Neurosciences Paris Seine - Institut de Biologie Paris Seine (NPS - IBPS), 75005, Paris, France
| | - Carole Morel
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, CNRS, Neurosciences Paris Seine - Institut de Biologie Paris Seine (NPS - IBPS), 75005, Paris, France
| | - Carole Perrier
- Groupe Hospitalier Paul Guiraud, BP 20065, F-94806, Villejuif, France
| | - Nicolas Torquet
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, CNRS, Neurosciences Paris Seine - Institut de Biologie Paris Seine (NPS - IBPS), 75005, Paris, France
| | - Stephanie Pons
- Institut Pasteur, Unité Neurobiologie Intégrative des Systèmes Cholinergiques, Département de Neuroscience, F-75724, Paris, France.,CNRS, UMR 3571, F-75724, Paris, France
| | | | - Philippe Faure
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, CNRS, Neurosciences Paris Seine - Institut de Biologie Paris Seine (NPS - IBPS), 75005, Paris, France
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27
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Pinheiro-Dardis CM, Erbereli BT, Gigo-Benato D, Castro PATS, Russo TL. Electrical stimulation delays reinnervation in denervated rat muscle. Muscle Nerve 2017; 56:E108-E118. [PMID: 28120411 DOI: 10.1002/mus.25589] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2016] [Revised: 01/09/2017] [Accepted: 01/18/2017] [Indexed: 02/05/2023]
Abstract
INTRODUCTION It is not clear if electrical stimulation (ES) can affect muscle reinnervation. This study aimed to verify if ES affects neuromuscular recovery after nerve crush injury in rats. METHODS Denervated muscles were electrically stimulated daily for 6 or 14 days. Neuromuscular performance and excitability, and muscle morphology were determined. Muscle trophism markers (atrogin-1, MuRF-1, and myoD), as well as neuromuscular junction (NMJ) organization (muscle-specific receptor tyrosine kinase [MuSK], cytoplasmic protein downstream of kinase-7 [Dok-7], nicotinic ACh receptor [nAChR], and neural cell adhesion molecule [N-CAM]) were assessed. RESULTS ES impaired neuromuscular recovery at day 14 postdenervation. Muscle hypoexcitability was accentuated by ES at 6 and 14 days postdenervation. Although ES reduced the accumulation of atrogin-1, MuRF1, and myoD mRNAs, it increased muscle atrophy. Gene expression of MuSK, Dok-7, nAChR, and the content of N-CAM protein were altered by ES. DISCUSSION ES can delay the reinnervation process by modulating factors related to NMJ stability and organization, and inducing dysfunction, hypoexcitability, and muscle atrophy. Muscle Nerve 56: E108-E118, 2017.
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Affiliation(s)
- Clara M Pinheiro-Dardis
- Fisioterapia Neurológica (LaFiN), Departamento de Fisioterapia, Universidade Federal de São Carlos (UFSCar), Rodovia Washington Luis, Km 235, C.P. 676 - CEP: 13565-905, São Carlos, SP, Brazil
| | - Bruna T Erbereli
- Fisioterapia Neurológica (LaFiN), Departamento de Fisioterapia, Universidade Federal de São Carlos (UFSCar), Rodovia Washington Luis, Km 235, C.P. 676 - CEP: 13565-905, São Carlos, SP, Brazil
| | - Davilene Gigo-Benato
- Fisioterapia Neurológica (LaFiN), Departamento de Fisioterapia, Universidade Federal de São Carlos (UFSCar), Rodovia Washington Luis, Km 235, C.P. 676 - CEP: 13565-905, São Carlos, SP, Brazil
| | - Paula A T S Castro
- Laboratory of Muscle Plasticity, DFisio, UFSCar, São Carlos, São Paulo, Brazil
| | - Thiago L Russo
- Fisioterapia Neurológica (LaFiN), Departamento de Fisioterapia, Universidade Federal de São Carlos (UFSCar), Rodovia Washington Luis, Km 235, C.P. 676 - CEP: 13565-905, São Carlos, SP, Brazil
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Einav T, Phillips R. Monod-Wyman-Changeux Analysis of Ligand-Gated Ion Channel Mutants. J Phys Chem B 2017; 121:3813-3824. [PMID: 28134524 DOI: 10.1021/acs.jpcb.6b12672] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
We present a framework for computing the gating properties of ligand-gated ion channel mutants using the Monod-Wyman-Changeux (MWC) model of allostery. We derive simple analytic formulas for key functional properties such as the leakiness, dynamic range, half-maximal effective concentration ([EC50]), and effective Hill coefficient, and explore the full spectrum of phenotypes that are accessible through mutations. Specifically, we consider mutations in the channel pore of nicotinic acetylcholine receptor (nAChR) and the ligand binding domain of a cyclic nucleotide-gated (CNG) ion channel, demonstrating how each mutation can be characterized as only affecting a subset of the biophysical parameters. In addition, we show how the unifying perspective offered by the MWC model allows us, perhaps surprisingly, to collapse the plethora of dose-response data from different classes of ion channels into a universal family of curves.
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Affiliation(s)
- Tal Einav
- Department of Physics, California Institute of Technology , Pasadena, California 91125, United States
| | - Rob Phillips
- Department of Applied Physics and Division of Biology and Biological Engineering, California Institute of Technology , Pasadena, California 91125, United States
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Kalinnikova TB, Kolsanova RR, Belova EB, Shagidullin RR, Gainutdinov MK. Opposite effects of moderate heat stress and hyperthermia on cholinergic system of soil nematodes Caenorhabditis elegans and Caenorhabditis briggsae. J Therm Biol 2016; 62:37-49. [PMID: 27839548 DOI: 10.1016/j.jtherbio.2016.05.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2015] [Revised: 05/26/2016] [Accepted: 05/29/2016] [Indexed: 10/20/2022]
Abstract
Cholinergic system plays important role in all functions of organisms of free-living soil nematodes C. elegans and C. briggsae. Using pharmacological analysis we showed the existence of two opposite responses of nematodes cholinergic system to moderate and extreme heat stress. Short-term (15min) noxious heat (31-32°C) caused activation of cholinergic synaptic transmission in C. elegans and C. briggsae organisms by sensitization of nicotinic ACh receptors. In contrast, hyperthermia blocked cholinergic synaptic transmission by inhibition of ACh secretion by neurons. The resistance of behavior to extreme high temperature (36-37°C) was significantly higher in C. briggsae than in C. elegans, and thermostability of cholinergic transmission correlated with resistance of behavior to hyperthermia. Activation of cholinergic transmission by moderate heat stress can be the reason of movement speed increase in such adaptive behavior as noxious heat escape. Inhibition of ACh release is one of reasons for behavior failure caused by extreme high temperature since partial inhibition of ACh-esterase by aldicarb protected C. elegans and C. briggsae behavior against hyperthermia. Antagonist of mAChRs atropine almost completely prevented the rise in behavior thermotolerance caused by aldicarb. Pilocarpine, agonist of mAChRs, protected nematodes behavior against hyperthermia similarly with aldicarb. Therefore it is evident that it is the deficiency of mAChRs activity that is the reason for nematodes' behavior failure by hyperthermia.
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Affiliation(s)
- Tatiana B Kalinnikova
- Research Institute for Problems of Ecology and Mineral Wealth Use of Tatarstan Academy of Sciences, Daurskaya str., 28, 420087 Kazan, Russia.
| | - Rufina R Kolsanova
- Research Institute for Problems of Ecology and Mineral Wealth Use of Tatarstan Academy of Sciences, Daurskaya str., 28, 420087 Kazan, Russia
| | - Evgenia B Belova
- Research Institute for Problems of Ecology and Mineral Wealth Use of Tatarstan Academy of Sciences, Daurskaya str., 28, 420087 Kazan, Russia
| | - Rifgat R Shagidullin
- Research Institute for Problems of Ecology and Mineral Wealth Use of Tatarstan Academy of Sciences, Daurskaya str., 28, 420087 Kazan, Russia
| | - Marat Kh Gainutdinov
- Research Institute for Problems of Ecology and Mineral Wealth Use of Tatarstan Academy of Sciences, Daurskaya str., 28, 420087 Kazan, Russia
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Echeverria V, Yarkov A, Aliev G. Positive modulators of the α7 nicotinic receptor against neuroinflammation and cognitive impairment in Alzheimer's disease. Prog Neurobiol 2016; 144:142-57. [DOI: 10.1016/j.pneurobio.2016.01.002] [Citation(s) in RCA: 67] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2015] [Revised: 11/07/2015] [Accepted: 01/06/2016] [Indexed: 01/08/2023]
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Crystal structure of a human neuronal nAChR extracellular domain in pentameric assembly: Ligand-bound α2 homopentamer. Proc Natl Acad Sci U S A 2016; 113:9635-40. [PMID: 27493220 DOI: 10.1073/pnas.1602619113] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In this study we report the X-ray crystal structure of the extracellular domain (ECD) of the human neuronal α2 nicotinic acetylcholine receptor (nAChR) subunit in complex with the agonist epibatidine at 3.2 Å. Interestingly, α2 was crystallized as a pentamer, revealing the intersubunit interactions in a wild type neuronal nAChR ECD and the full ligand binding pocket conferred by two adjacent α subunits. The pentameric assembly presents the conserved structural scaffold observed in homologous proteins, as well as distinctive features, providing unique structural information of the binding site between principal and complementary faces. Structure-guided mutagenesis and electrophysiological data confirmed the presence of the α2(+)/α2(-) binding site on the heteromeric low sensitivity α2β2 nAChR and validated the functional importance of specific residues in α2 and β2 nAChR subunits. Given the pathological importance of the α2 nAChR subunit and the high sequence identity with α4 (78%) and other neuronal nAChR subunits, our findings offer valuable information for modeling several nAChRs and ultimately for structure-based design of subtype specific drugs against the nAChR associated diseases.
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32
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Competitive antagonists facilitate the recovery from desensitization of α1β2γ2 GABAA receptors expressed in Xenopus oocytes. Acta Pharmacol Sin 2016; 37:1020-30. [PMID: 27374488 DOI: 10.1038/aps.2016.50] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2015] [Accepted: 03/07/2016] [Indexed: 01/22/2023] Open
Abstract
AIM The continuous presence of an agonist drives its receptor into a refractory state, termed desensitization. In this study, we tested the hypothesis that a competitive antagonist, SR95531, could facilitate the recovery of α1β2γ2 GABAA receptor from functional desensitization. METHODS α1β2γ2 GABAA receptors were expressed in Xenopus oocytes. GABA-evoked currents were recorded using two-electrode voltage-clamp technique. Drugs were applied through perfusion. RESULTS Long application of GABA (100 μmol/L) evoked a large peak current followed by a small amplitude steady-state current (desensitization). Co-application of SR95531 during the desensitization caused a larger rebound of GABA current after removal of SR95531. Furthermore, application of SR95531 after removal of GABA increased the rate of receptor recovery from desensitization, and the recovery time constant was decreased from 59±3.2 s to 33±1.6 s. SR95531-facilitated receptor recovery from desensitization was dependent on the perfusion duration of SR95531. It was also dependent on the concentration of SR95531, and the curve fitting with Hill equation revealed two potency components, which were similar to the two potency components in inhibition of the steady-state current by SR95531. Bicuculline caused similar facilitation of desensitization recovery. CONCLUSION SR95531 facilitates α1β2γ2 GABAA receptor recovery from desensitization, possibly through two mechanisms: binding to the desensitized receptor and converting it to the non-desensitized state, and binding to the resting state receptor and preventing re-desensitization.
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Activation of the sigma receptor 1 modulates AMPA receptor-mediated light-evoked excitatory postsynaptic currents in rat retinal ganglion cells. Neuroscience 2016; 332:53-60. [PMID: 27373906 DOI: 10.1016/j.neuroscience.2016.06.045] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2016] [Revised: 06/15/2016] [Accepted: 06/24/2016] [Indexed: 11/20/2022]
Abstract
Sigma receptor (σR), a unique receptor family, is classified into three subtypes: σR1, σR2 and σR3. It was previously shown that σR1 activation induced by 1μM SKF10047 (SKF) suppressed N-methyl-d-aspartate (NMDA) receptor-mediated responses of rat retinal ganglion cells (GCs) and the suppression was mediated by a distinct Ca(2+)-dependent phospholipase C (PLC)-protein kinase C (PKC) pathway. In the present work, using whole-cell patch-clamp techniques in rat retinal slice preparations, we further demonstrate that SKF of higher dosage (50μM) significantly suppressed AMPA receptor (AMPAR)-mediated light-evoked excitatory postsynaptic currents (L-EPSCs) of retinal ON-type GCs (ON GCs), and the effect was reversed by the σR1 antagonist BD1047, suggesting the involvement of σR1. The SKF (50μM) effect was unlikely due to a change in glutamate release from bipolar cells, as suggested by the unaltered paired-pulse ratio (PPR) of AMPAR-mediated EPSCs of ON GCs. SKF (50μM) did not change L-EPSCs of ON GCs when the G protein inhibitor GDP-β-S or the protein kinase G (PKG) inhibitor KT5823 was intracellularly infused. Calcium imaging further revealed that SKF (50μM) did not change intracellular calcium concentration in GCs and persisted to suppress L-EPSCs when intracellular calcium was chelated by BAPTA. The SKF (50μM) effect was intact when protein kinase A (PKA) and phosphatidylinostiol (PI)-PLC signaling pathways were both blocked. We conclude that the SKF (50μM) effect is Ca(2+)-independent, PKG-dependent, but not involving PKA, PI-PLC pathways.
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35
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Zheng F, Robertson AP, Abongwa M, Yu EW, Martin RJ. The Ascaris suum nicotinic receptor, ACR-16, as a drug target: Four novel negative allosteric modulators from virtual screening. INTERNATIONAL JOURNAL FOR PARASITOLOGY-DRUGS AND DRUG RESISTANCE 2016; 6:60-73. [PMID: 27054065 PMCID: PMC4805779 DOI: 10.1016/j.ijpddr.2016.02.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/06/2015] [Revised: 01/28/2016] [Accepted: 02/05/2016] [Indexed: 12/22/2022]
Abstract
Soil-transmitted helminth infections in humans and livestock cause significant debility, reduced productivity and economic losses globally. There are a limited number of effective anthelmintic drugs available for treating helminths infections, and their frequent use has led to the development of resistance in many parasite species. There is an urgent need for novel therapeutic drugs for treating these parasites. We have chosen the ACR-16 nicotinic acetylcholine receptor of Ascaris suum (Asu-ACR-16), as a drug target and have developed three-dimensional models of this transmembrane protein receptor to facilitate the search for new bioactive compounds. Using the human α7 nAChR chimeras and Torpedo marmorata nAChR for homology modeling, we defined orthosteric and allosteric binding sites on the Asu-ACR-16 receptor for virtual screening. We identified four ligands that bind to sites on Asu-ACR-16 and tested their activity using electrophysiological recording from Asu-ACR-16 receptors expressed in Xenopus oocytes. The four ligands were acetylcholine inhibitors (SB-277011-A, IC50, 3.12 ± 1.29 μM; (+)-butaclamol Cl, IC50, 9.85 ± 2.37 μM; fmoc-1, IC50, 10.00 ± 1.38 μM; fmoc-2, IC50, 16.67 ± 1.95 μM) that behaved like negative allosteric modulators. Our work illustrates a structure-based in silico screening method for seeking anthelmintic hits, which can then be tested electrophysiologically for further characterization. Three-dimensional structural models of the Ascaris nicotinic (Asu-ACR-16) receptor made by homology modeling. High affinity ligands selected by in silico screening. Four ligands validated by electrophysiological studies as negative allosteric modulators.
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Affiliation(s)
- Fudan Zheng
- Department of Chemistry, College of Liberal Arts and Sciences, Iowa State University, Ames, IA 50011, USA
| | - Alan P Robertson
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA 50011, USA
| | - Melanie Abongwa
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA 50011, USA
| | - Edward W Yu
- Department of Chemistry, College of Liberal Arts and Sciences, Iowa State University, Ames, IA 50011, USA; Department of Physics and Astronomy, College of Liberal Arts and Sciences, Iowa State University, Ames, IA 50011, USA
| | - Richard J Martin
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA 50011, USA.
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Barwich AS. What is so special about smell? Olfaction as a model system in neurobiology. Postgrad Med J 2015; 92:27-33. [PMID: 26534994 DOI: 10.1136/postgradmedj-2015-133249] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2015] [Accepted: 10/05/2015] [Indexed: 11/04/2022]
Abstract
Neurobiology studies mechanisms of cell signalling. A key question is how cells recognise specific signals. In this context, olfaction has become an important experimental system over the past 25 years. The olfactory system responds to an array of structurally diverse stimuli. The discovery of the olfactory receptors (ORs), recognising these stimuli, established the olfactory pathway as part of a greater group of signalling mechanisms mediated by G-protein-coupled receptors (GPCRs). GPCRs are the largest protein family in the mammalian genome and involved in numerous fundamental physiological processes. The OR family exhibits two characteristics that make them an excellent model system to understand GPCRs: its size and the structural diversity of its members. Research on the OR binding site investigates what amino acid sequences determine the receptor-binding capacity. This promises a better understanding of how the basic genetic makeup of GPCRs relates to their diversification in ligand-binding capacities.
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37
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Conotoxin αD-GeXXA utilizes a novel strategy to antagonize nicotinic acetylcholine receptors. Sci Rep 2015; 5:14261. [PMID: 26395518 PMCID: PMC4585798 DOI: 10.1038/srep14261] [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: 05/14/2015] [Accepted: 08/21/2015] [Indexed: 11/19/2022] Open
Abstract
Nicotinic acetylcholine receptors (nAChRs) play essential roles in transmitting acetylcholine-mediated neural signals across synapses and neuromuscular junctions, and are also closely linked to various diseases and clinical conditions. Therefore, novel nAChR-specific compounds have great potential for both neuroscience research and clinical applications. Conotoxins, the peptide neurotoxins produced by cone snails, are a rich reservoir of novel ligands that target receptors, ion channels and transporters in the nervous system. From the venom of Conus generalis, we identified a novel dimeric nAChR-inhibiting αD-conotoxin GeXXA. By solving the crystal structure and performing structure-guided dissection of this toxin, we demonstrated that the monomeric C-terminal domain of αD-GeXXA, GeXXA-CTD, retains inhibitory activity against the α9α10 nAChR subtype. Furthermore, we identified that His7 of the rat α10 nAChR subunit determines the species preference of αD-GeXXA, and is probably part of the binding site of this toxin. These results together suggest that αD-GeXXA cooperatively binds to two inter-subunit interfaces on the top surface of nAChR, thus allosterically disturbing the opening of the receptor. The novel antagonistic mechanism of αD-GeXXA via a new binding site on nAChRs provides a valuable basis for the rational design of new nAChR-targeting compounds.
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Pirri JK, Rayes D, Alkema MJ. A Change in the Ion Selectivity of Ligand-Gated Ion Channels Provides a Mechanism to Switch Behavior. PLoS Biol 2015; 13:e1002238. [PMID: 26348462 PMCID: PMC4562599 DOI: 10.1371/journal.pbio.1002238] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2015] [Accepted: 07/30/2015] [Indexed: 11/19/2022] Open
Abstract
Behavioral output of neural networks depends on a delicate balance between excitatory and inhibitory synaptic connections. However, it is not known whether network formation and stability is constrained by the sign of synaptic connections between neurons within the network. Here we show that switching the sign of a synapse within a neural circuit can reverse the behavioral output. The inhibitory tyramine-gated chloride channel, LGC-55, induces head relaxation and inhibits forward locomotion during the Caenorhabditis elegans escape response. We switched the ion selectivity of an inhibitory LGC-55 anion channel to an excitatory LGC-55 cation channel. The engineered cation channel is properly trafficked in the native neural circuit and results in behavioral responses that are opposite to those produced by activation of the LGC-55 anion channel. Our findings indicate that switches in ion selectivity of ligand-gated ion channels (LGICs) do not affect network connectivity or stability and may provide an evolutionary and a synthetic mechanism to change behavior.
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Affiliation(s)
- Jennifer K. Pirri
- Department of Neurobiology, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Diego Rayes
- Department of Neurobiology, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
- Instituto de Investigaciones Bioquímicas de Bahía Blanca, UNS-CONICET, Bahía Blanca, Argentina
| | - Mark J. Alkema
- Department of Neurobiology, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
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Glycine receptor mechanism elucidated by electron cryo-microscopy. Nature 2015; 526:224-9. [PMID: 26344198 DOI: 10.1038/nature14853] [Citation(s) in RCA: 309] [Impact Index Per Article: 34.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Accepted: 06/23/2015] [Indexed: 12/12/2022]
Abstract
The strychnine-sensitive glycine receptor (GlyR) mediates inhibitory synaptic transmission in the spinal cord and brainstem and is linked to neurological disorders, including autism and hyperekplexia. Understanding of molecular mechanisms and pharmacology of glycine receptors has been hindered by a lack of high-resolution structures. Here we report electron cryo-microscopy structures of the zebrafish α1 GlyR with strychnine, glycine, or glycine and ivermectin (glycine/ivermectin). Strychnine arrests the receptor in an antagonist-bound closed ion channel state, glycine stabilizes the receptor in an agonist-bound open channel state, and the glycine/ivermectin complex adopts a potentially desensitized or partially open state. Relative to the glycine-bound state, strychnine expands the agonist-binding pocket via outward movement of the C loop, promotes rearrangement of the extracellular and transmembrane domain 'wrist' interface, and leads to rotation of the transmembrane domain towards the pore axis, occluding the ion conduction pathway. These structures illuminate the GlyR mechanism and define a rubric to interpret structures of Cys-loop receptors.
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40
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Zhang Q, Du Y, Zhang J, Xu X, Xue F, Guo C, Huang Y, Lukas RJ, Chang Y. Functional Impact of 14 Single Nucleotide Polymorphisms Causing Missense Mutations of Human α7 Nicotinic Receptor. PLoS One 2015; 10:e0137588. [PMID: 26340537 PMCID: PMC4560414 DOI: 10.1371/journal.pone.0137588] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2015] [Accepted: 08/18/2015] [Indexed: 01/17/2023] Open
Abstract
The α7nicotinic receptor (nAChR) is a major subtype of the nAChRs in the central nervous system, and the receptor plays an important role in brain function. In the dbSNP database, there are 55 single nucleotide polymorphisms (SNPs) that cause missense mutations of the human α7nAChR in the coding region. In this study, we tested the impact of 14 SNPs that cause missense mutations in the agonist binding site or the coupling region between binding site and channel gate on the receptor function. The wild type or mutant receptors were expressed or co-expressed in Xenopus oocytes, and the agonist-induced currents were tested using two-electrode voltage clamp. Our results demonstrated that 6 mutants were nonfunctional, 4 mutants had reduced current expression, and 1 mutants altered ACh and nicotine efficacy in the opposite direction, and one additional mutant had slightly reduced agonist sensitivity. Interestingly, the function of most of these nonfunctional mutants could be rescued by α7nAChR positive allosteric modulator PNU-120596 and agonist-PAM 4BP-TQS. Finally, when coexpressed with the wild type, the nonfunctional mutants could also influence the receptor function. These changes of the receptor properties by the mutations could potentially have an impact on the physiological function of the α7nAChR-mediated cholinergic synaptic transmission and anti-inflammatory effects in the human SNP carriers. Rescuing the nonfunctional mutants could provide a novel way to treat the related disorders.
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Affiliation(s)
- Qinhui Zhang
- Department of Zoology, College of Life Sciences, Sichuan University, Chengdu, Sichuan Province, 610064, China
- Chengdu institute of Biology, Chinese Academy of Sciences, Chengdu, Sichuan 610041, China
- Division of Neurobiology, Barrow Neurological Institute, St. Joseph’s Hospital and Medical Center, Phoenix, Arizona 85013, United States of America
| | - Yingjie Du
- University of California Los Angeles, Henry Samueli School of Engineering and Applied Science, Los Angeles, California 90095, United States of America
| | - Jianliang Zhang
- Division of Neurobiology, Barrow Neurological Institute, St. Joseph’s Hospital and Medical Center, Phoenix, Arizona 85013, United States of America
- Department of Neurobiology, Beijing Institute of Brain Disorders, Capital Medical University, Key Laboratory for Neurodegenerative Disease of the Ministry of Education, Beijing Center of Neural Regeneration and Repair, Beijing Key Laboratory of Brain Major Disorders; State Key Lab Incubation Base, Beijing Neuroscience Disciplines, Beijing 100069, China
| | - Xiaojun Xu
- Division of Neurobiology, Barrow Neurological Institute, St. Joseph’s Hospital and Medical Center, Phoenix, Arizona 85013, United States of America
| | - Fenqin Xue
- Division of Neurobiology, Barrow Neurological Institute, St. Joseph’s Hospital and Medical Center, Phoenix, Arizona 85013, United States of America
- Core Facilities for Electrophysiology, Core Facilities Center, Capital Medical University, Beijing 100069, China
| | - Cong Guo
- Department of Zoology, College of Life Sciences, Sichuan University, Chengdu, Sichuan Province, 610064, China
- Chengdu institute of Biology, Chinese Academy of Sciences, Chengdu, Sichuan 610041, China
| | - Yao Huang
- Department of Obstetrics and Gynecology, St. Joseph’s Hospital and Medical Center, Phoenix, Arizona 85013, United States of America
| | - Ronald J. Lukas
- Division of Neurobiology, Barrow Neurological Institute, St. Joseph’s Hospital and Medical Center, Phoenix, Arizona 85013, United States of America
| | - Yongchang Chang
- Division of Neurobiology, Barrow Neurological Institute, St. Joseph’s Hospital and Medical Center, Phoenix, Arizona 85013, United States of America
- * E-mail:
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Nuclear Localization of the DNA Repair Scaffold XRCC1: Uncovering the Functional Role of a Bipartite NLS. Sci Rep 2015; 5:13405. [PMID: 26304019 PMCID: PMC4548243 DOI: 10.1038/srep13405] [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: 03/27/2015] [Accepted: 07/17/2015] [Indexed: 12/23/2022] Open
Abstract
We have characterized the nuclear localization signal (NLS) of XRCC1 structurally using X-ray crystallography and functionally using fluorescence imaging. Crystallography and binding studies confirm the bipartite nature of the XRCC1 NLS interaction with Importin α (Impα) in which the major and minor binding motifs are separated by >20 residues, and resolve previous inconsistent determinations. Binding studies of peptides corresponding to the bipartite NLS, as well as its major and minor binding motifs, to both wild-type and mutated forms of Impα reveal pronounced cooperative binding behavior that is generated by the proximity effect of the tethered major and minor motifs of the NLS. The cooperativity stems from the increased local concentration of the second motif near its cognate binding site that is a consequence of the stepwise binding behavior of the bipartite NLS. We predict that the stepwise dissociation of the NLS from Impα facilitates unloading by providing a partially complexed intermediate that is available for competitive binding by Nup50 or the Importin β binding domain. This behavior provides a basis for meeting the intrinsically conflicting high affinity and high flux requirements of an efficient nuclear transport system.
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Lanig H, Reisen F, Whitley D, Schneider G, Banting L, Clark T. In Silico Adoption of an Orphan Nuclear Receptor NR4A1. PLoS One 2015; 10:e0135246. [PMID: 26270486 PMCID: PMC4535767 DOI: 10.1371/journal.pone.0135246] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2015] [Accepted: 07/20/2015] [Indexed: 11/24/2022] Open
Abstract
A 4.1μs molecular dynamics simulation of the NR4A1 (hNur77) apo-protein has been undertaken and a previously undetected druggable pocket has become apparent that is located remotely from the ‘traditional’ nuclear receptor ligand-binding site. A NR4A1/bis-indole ligand complex at this novel site has been found to be stable over 1 μs of simulation and to result in an interesting conformational transmission to a remote loop that has the capacity to communicate with a NBRE within a RXR-α/NR4A1 heterodimer. Several features of the simulations undertaken indicate how NR4A1 can be affected by alternate-site modulators.
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Affiliation(s)
- Harald Lanig
- Computer-Chemie-Centrum der Friedrich-Alexander-Universität Erlangen-Nürnberg, Nägelsbachstraße 25, 91052, Erlangen, Germany
| | - Felix Reisen
- ETH Zürich, Institute of Pharmaceutical Sciences, Wolfgang-Pauli-Straße 10, 8093, Zürich, Switzerland
| | - David Whitley
- Centre for Molecular Design, School of Pharmacy and Biomolecular Sciences, University of Portsmouth, King Henry Building, Portsmouth, PO1 2DY, United Kingdom
| | - Gisbert Schneider
- ETH Zürich, Institute of Pharmaceutical Sciences, Wolfgang-Pauli-Straße 10, 8093, Zürich, Switzerland
| | - Lee Banting
- School of Pharmacy and Biomolecular Sciences, University of Portsmouth, St. Michael’s Building, White Swan Road, Portsmouth, PO1 2DT, United Kingdom
- * E-mail: (LB); (TC)
| | - Timothy Clark
- Computer-Chemie-Centrum der Friedrich-Alexander-Universität Erlangen-Nürnberg, Nägelsbachstraße 25, 91052, Erlangen, Germany
- Centre for Molecular Design, School of Pharmacy and Biomolecular Sciences, University of Portsmouth, King Henry Building, Portsmouth, PO1 2DY, United Kingdom
- * E-mail: (LB); (TC)
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Báez-Pagán CA, Delgado-Vélez M, Lasalde-Dominicci JA. Activation of the Macrophage α7 Nicotinic Acetylcholine Receptor and Control of Inflammation. J Neuroimmune Pharmacol 2015; 10:468-76. [PMID: 25870122 DOI: 10.1007/s11481-015-9601-5] [Citation(s) in RCA: 144] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2013] [Accepted: 03/12/2015] [Indexed: 01/03/2023]
Abstract
Inflammatory responses to stimuli are essential body defenses against foreign threats. However, uncontrolled inflammation may result in serious health problems, which can be life-threatening. The α7 nicotinic acetylcholine receptor, a ligand-gated ion channel expressed in the nervous and immune systems, has an essential role in the control of inflammation. Activation of the macrophage α7 receptor by acetylcholine, nicotine, or other agonists, selectively inhibits production of pro-inflammatory cytokines while leaving anti-inflammatory cytokines undisturbed. The neural control of this regulation pathway was discovered recently and it was named the cholinergic anti-inflammatory pathway (CAP). When afferent vagus nerve terminals are activated by cytokines or other pro-inflammatory stimuli, the message travels through the afferent vagus nerve, resulting in action potentials traveling down efferent vagus nerve fibers in a process that eventually leads to macrophage α7 activation by acetylcholine and inhibition of pro-inflammatory cytokines production. The mechanism by which activation of α7 in macrophages regulates pro-inflammatory responses is subject of intense research, and important insights have thus been made. The results suggest that activation of the macrophage α7 controls inflammation by inhibiting NF-κB nuclear translocation, and activating the JAK2/STAT3 pathway among other suggested pathways. While the α7 is well characterized as a ligand-gated ion channel in neurons, whole-cell patch clamp experiments suggest that α7's ion channel activity, defined as the translocation of ions across the membrane in response to ligands, is absent in leukocytes, and therefore, ion channel activity is generally assumed not to be required for the operation of the CAP. In this perspective, we briefly review macrophage α7 activation as it relates to the control of inflammation, and broaden the current view by providing single-channel currents as evidence that the α7 expressed in macrophages retains its ion translocation activity despite the absence of whole-cell currents. Whether this ion-translocating activity is relevant for the proper operation of the CAP or other important physiological processes remains obscure.
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Affiliation(s)
- Carlos A Báez-Pagán
- Department of Biology, University of Puerto Rico, Río Piedras Campus, PO Box 23360, San Juan, Puerto Rico, 00931,
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van der Westhuizen ET, Valant C, Sexton PM, Christopoulos A. Endogenous Allosteric Modulators of G Protein–Coupled Receptors. J Pharmacol Exp Ther 2015; 353:246-60. [DOI: 10.1124/jpet.114.221606] [Citation(s) in RCA: 106] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
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Saika F, Kiguchi N, Kobayashi Y, Kishioka S. Peripheral alpha4beta2 nicotinic acetylcholine receptor signalling attenuates tactile allodynia and thermal hyperalgesia after nerve injury in mice. Acta Physiol (Oxf) 2015; 213:462-71. [PMID: 25491757 DOI: 10.1111/apha.12437] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2014] [Revised: 07/22/2014] [Accepted: 12/02/2014] [Indexed: 01/03/2023]
Abstract
AIM Neuropathic pain is often refractory to conventional analgesics including opioids and non-steroidal anti-inflammatory drugs. Evidence suggests nicotinic acetylcholine receptor ligands regulate pain transmission. Effects of α4β2 nicotinic acetylcholine receptor activation on pain behaviours after nerve injury were studied. METHODS Mice were subjected to partial sciatic nerve ligation (PSL). Nicotinic acetylcholine receptor α4 and β2 subunits localization in injured nerves were evaluated by immunohistochemistry. Neuropathic pain, assessed by tactile allodynia and thermal hyperalgesia, was examined by von Frey test and Hargreaves test respectively. RESULTS Nicotinic acetylcholine receptor α4 and β2 subunits were up-regulated in injured nerves and were expressed on F4/80-positive macrophages. When nicotine was perineurally administered daily for 4 days (day 7-10; maintenance phase) after nerve injury, pain behaviours were significantly alleviated. The inhibitory effects of nicotine were reversed by co-administration of mecamylamine (non-selective nicotinic acetylcholine receptor antagonist) and dihydro-β-erythroidine (selective α4β2 nicotinic acetylcholine receptor antagonist). Likewise, when α4β2 nicotinic acetylcholine receptor agonists (TC2559 or ABT418) were administered daily for 4 days (day 7-10) after nerve injury, pain behaviours were significantly attenuated. On the other hand, nicotine administered daily for 4 days (day 0-3; initiation phase) after nerve injury alleviated pain behaviours, which were antagonized by co-administration of dihydro-β-erythroidine. TC2559 administered daily for 4 days (day 0-3) also attenuated nerve injury-induced pain behaviours. CONCLUSION The activation of α4β2 nicotinic acetylcholine receptor expressed on infiltrating macrophages in injured nerves may participate in the relief of PSL-induced neuropathic pain during maintenance and initiation phases.
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Affiliation(s)
- F. Saika
- Department of Pharmacology; Wakayama Medical University; Wakayama Japan
| | - N. Kiguchi
- Department of Pharmacology; Wakayama Medical University; Wakayama Japan
| | - Y. Kobayashi
- Department of Pharmacology; Wakayama Medical University; Wakayama Japan
| | - S. Kishioka
- Department of Pharmacology; Wakayama Medical University; Wakayama Japan
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Dutta-Roy R, Rosenmund C, Edelstein SJ, Le Novère N. Ligand-dependent opening of the multiple AMPA receptor conductance states: a concerted model. PLoS One 2015; 10:e0116616. [PMID: 25629405 PMCID: PMC4309570 DOI: 10.1371/journal.pone.0116616] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2014] [Accepted: 11/21/2014] [Indexed: 01/27/2023] Open
Abstract
Modulation of the properties of AMPA receptors at the post-synaptic membrane is one of the main suggested mechanisms underlying fast synaptic transmission in the central nervous system of vertebrates. Electrophysiological recordings of single channels stimulated with agonists showed that both recombinant and native AMPA receptors visit multiple conductance states in an agonist concentration dependent manner. We propose an allosteric model of the multiple conductance states based on concerted conformational transitions of the four subunits, as an iris diaphragm. Our model predicts that the thermodynamic behaviour of the conductance states upon full and partial agonist stimulations can be described with increased affinity of receptors as they progress to higher conductance states. The model also predicts the existence of AMPA receptors in non-liganded conductive substates. However, the probability of spontaneous openings decreases with increasing conductances. Finally, we predict that the large conductance states are stabilized within the rise phase of a whole-cell EPSC in glutamatergic hippocampal neurons. Our model provides a mechanistic link between ligand concentration and conductance states that can explain thermodynamic and kinetic features of AMPA receptor gating.
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Affiliation(s)
- Ranjita Dutta-Roy
- Department of Medicine Solna, Karolinska Insitutet, 171 76 Stockholm, Sweden
- NWFZ, Charite Universitatsmedizin, 101 17 Berlin, Germany
- European Bioinformatics Institute (EMBL-EBI), Wellcome Trust Genome Campus, Hinxton, Cambridgeshire CB10 1SD, UK
| | | | | | - Nicolas Le Novère
- European Bioinformatics Institute (EMBL-EBI), Wellcome Trust Genome Campus, Hinxton, Cambridgeshire CB10 1SD, UK
- The Babraham Institute, Babraham, Cambridgeshire CB22 3AT, UK
- * E-mail:
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Geng Y, Magleby KL. Single-channel kinetics of BK (Slo1) channels. Front Physiol 2015; 5:532. [PMID: 25653620 PMCID: PMC4300911 DOI: 10.3389/fphys.2014.00532] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2014] [Accepted: 12/31/2014] [Indexed: 11/16/2022] Open
Abstract
Single-channel kinetics has proven a powerful tool to reveal information about the gating mechanisms that control the opening and closing of ion channels. This introductory review focuses on the gating of large conductance Ca2+- and voltage-activated K+ (BK or Slo1) channels at the single-channel level. It starts with single-channel current records and progresses to presentation and analysis of single-channel data and the development of gating mechanisms in terms of discrete state Markov (DSM) models. The DSM models are formulated in terms of the tetrameric modular structure of BK channels, consisting of a central transmembrane pore-gate domain (PGD) attached to four surrounding transmembrane voltage sensing domains (VSD) and a large intracellular cytosolic domain (CTD), also referred to as the gating ring. The modular structure and data analysis shows that the Ca2+ and voltage dependent gating considered separately can each be approximated by 10-state two-tiered models with five closed states on the upper tier and five open states on the lower tier. The modular structure and joint Ca2+ and voltage dependent gating are consistent with a 50 state two-tiered model with 25 closed states on the upper tier and 25 open states on the lower tier. Adding an additional tier of brief closed (flicker states) to the 10-state or 50-state models improved the description of the gating. For fixed experimental conditions a channel would gate in only a subset of the potential number of states. The detected number of states and the correlations between adjacent interval durations are consistent with the tiered models. The examined models can account for the single-channel kinetics and the bursting behavior of gating. Ca2+ and voltage activate BK channels by predominantly increasing the effective opening rate of the channel with a smaller decrease in the effective closing rate. Ca2+ and depolarization thus activate by mainly destabilizing the closed states.
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Affiliation(s)
- Yanyan Geng
- Department of Physiology and Biophysics, University of Miami Miller School of Medicine Miami, FL, USA
| | - Karl L Magleby
- Department of Physiology and Biophysics, University of Miami Miller School of Medicine Miami, FL, USA ; Neuroscience Program, University of Miami Miller School of Medicine Miami, FL, USA
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Mine N, Taniguchi W, Nishio N, Izumi N, Miyazaki N, Yamada H, Nakatsuka T, Yoshida M. Synaptic modulation of excitatory synaptic transmission by nicotinic acetylcholine receptors in spinal ventral horn neurons. Neuroscience 2015; 290:18-30. [PMID: 25613686 DOI: 10.1016/j.neuroscience.2015.01.015] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2014] [Revised: 01/09/2015] [Accepted: 01/10/2015] [Indexed: 12/18/2022]
Abstract
Nicotinic acetylcholine receptors (nAChRs) are distributed widely in the central nervous system and play important roles in higher brain functions, including learning, memory, and recognition. However, functions of the cholinergic system in spinal motoneurons remain poorly understood. In this study, we investigated the actions of presynaptic and postsynaptic nAChRs in spinal ventral horn neurons by performing whole-cell patch-clamp recordings on lumbar slices from male rats. The application of nicotine or acetylcholine generated slow inward currents and increased the frequency and amplitude of spontaneous excitatory postsynaptic currents (sEPSCs). Slow inward currents by acetylcholine or nicotine were not inhibited by tetrodotoxin (TTX) or glutamate receptor antagonists. In the presence of TTX, the frequency and amplitude of miniature excitatory postsynaptic currents (mEPSCs) were also increased by acetylcholine or nicotine. A selective α4β2 nicotinic receptor antagonist, dihydro-β-erythroidine hydrobromide (DhβE), significantly decreased nicotine-induced inward currents without affecting the enhancement of sEPSCs and mEPSCs. In addition, a selective α7 nicotinic receptor antagonist, methyllycaconitine, did not affect either nicotine-induced inward currents or the enhancement of sEPSCs and mEPSCs. These results suggest that α4β2 AChRs are localized at postsynaptic sites in the spinal ventral horn, non-α4β2 and non-α7 nAChRs are located presynaptically, and nAChRs enhance excitatory synaptic transmission in the spinal ventral horn.
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Affiliation(s)
- N Mine
- Department of Orthopedic Surgery, Wakayama Medical University, Wakayama 641-8510, Japan
| | - W Taniguchi
- Pain Research Center, Kansai University of Health Sciences, Kumatori, Osaka 590-0482, Japan.
| | - N Nishio
- Pain Research Center, Kansai University of Health Sciences, Kumatori, Osaka 590-0482, Japan
| | - N Izumi
- Department of Orthopedic Surgery, Wakayama Medical University, Wakayama 641-8510, Japan
| | - N Miyazaki
- Department of Orthopedic Surgery, Wakayama Medical University, Wakayama 641-8510, Japan
| | - H Yamada
- Department of Orthopedic Surgery, Wakayama Medical University, Wakayama 641-8510, Japan
| | - T Nakatsuka
- Pain Research Center, Kansai University of Health Sciences, Kumatori, Osaka 590-0482, Japan
| | - M Yoshida
- Department of Orthopedic Surgery, Wakayama Medical University, Wakayama 641-8510, Japan
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Drug-dependent behaviors and nicotinic acetylcholine receptor expressions in Caenorhabditis elegans following chronic nicotine exposure. Neurotoxicology 2014; 47:27-36. [PMID: 25530353 DOI: 10.1016/j.neuro.2014.12.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2014] [Revised: 12/09/2014] [Accepted: 12/11/2014] [Indexed: 12/18/2022]
Abstract
Nicotine, the major psychoactive compound in tobacco, targets nicotinic acetylcholine receptors (nAChRs) and results in drug dependence. The nematode Caenorhabditis elegans' (C. elegans) genome encodes conserved and extensive nicotinic receptor subunits, representing a useful system to investigate nicotine-induced nAChR expressions in the context of drug dependence. However, the in vivo expression pattern of nAChR genes under chronic nicotine exposure has not been fully investigated. To define the role of nAChR genes involved in nicotine-induced locomotion changes and the development of tolerance to these effects, we characterized the locomotion behavior combining the use of two systems: the Worm Tracker hardware and the WormLab software. Our results indicate that the combined system is an advantageous alternative to define drug-dependent locomotion behavior in C. elegans. Chronic (24-h dosing) nicotine exposure at 6.17 and 61.7μM induced nicotine-dependent behaviors, including drug stimulation, tolerance/adaption, and withdrawal responses. Specifically, the movement speed of naïve worms on nicotine-containing environments was significantly higher than on nicotine-free environments, suggesting locomotion stimulation by nicotine. In contrast, the 24-h 6.17μM nicotine-treated worms exhibited significantly higher speeds on nicotine-free plates than on nicotine-containing plates. Furthermore significantly increased locomotion behavior during nicotine cessation was observed in worms treated with a higher nicotine concentration of 61.7μM. The relatively low locomotion speed of nicotine-treated worms on nicotine-containing environments also indicates adaption/tolerance of worms to nicotine following chronic nicotine exposure. In addition, this study provides useful information regarding the comprehensive in vivo expression profile of the 28 "core" nAChRs following different dosages of chronic nicotine treatments. Eleven genes (lev-1, acr-6, acr-7, acr-11, lev-8, acr-14, acr-16, acr-20, acr-21, ric-3, and unc-29) were significantly up-regulated following 61.7μM nicotine treatment, in which worms showed significantly increased locomotion behavior. This study provides insights into the linkage between nicotine-induced locomotion behavior and the regulation of nicotinic acetylcholine receptors.
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Cecchini M, Changeux JP. The nicotinic acetylcholine receptor and its prokaryotic homologues: Structure, conformational transitions & allosteric modulation. Neuropharmacology 2014; 96:137-49. [PMID: 25529272 DOI: 10.1016/j.neuropharm.2014.12.006] [Citation(s) in RCA: 94] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2014] [Revised: 11/27/2014] [Accepted: 12/03/2014] [Indexed: 10/24/2022]
Abstract
Pentameric ligand-gated ion channels (pLGICs) play a central role in intercellular communications in the nervous system by converting the binding of a chemical messenger - a neurotransmitter - into an ion flux through the postsynaptic membrane. Here, we present an overview of the most recent advances on the signal transduction mechanism boosted by X-ray crystallography of both prokaryotic and eukaryotic homologues of the nicotinic acetylcholine receptor (nAChR) in conjunction with time-resolved analyses based on single-channel electrophysiology and Molecular Dynamics simulations. The available data consistently point to a global mechanism of gating that involves a large reorganization of the receptor mediated by two distinct quaternary transitions: a global twisting and a radial expansion/contraction of the extracellular domain. These transitions profoundly modify the organization of the interface between subunits, which host several sites for orthosteric and allosteric modulatory ligands. The same mechanism may thus mediate both positive and negative allosteric modulations of pLGICs ligand binding at topographically distinct sites. The emerging picture of signal transduction is expected to pave the way to new pharmacological strategies for the development of allosteric modulators of nAChR and pLGICs in general. This article is part of the Special Issue entitled 'The Nicotinic Acetylcholine Receptor: From Molecular Biology to Cognition'.
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Affiliation(s)
- Marco Cecchini
- ISIS, UMR 7006 CNRS, Université de Strasbourg, F-67083 Strasbourg Cedex, France.
| | - Jean-Pierre Changeux
- CNRS, URA 2182, F-75015 Paris, France; Collège de France, F-75005 Paris, France; Kavli Institute for Brain & Mind University of California, San Diego La Jolla, CA 92093, USA.
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