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Görgülü I, Jagannath V, Pons S, Koniuszewski F, Groszer M, Maskos U, Huck S, Scholze P. The human-specific nicotinic receptor subunit CHRFAM7A reduces α7 receptor function in human induced pluripotent stem cells-derived and transgenic mouse neurons. Eur J Neurosci 2024; 60:4893-4906. [PMID: 39073048 DOI: 10.1111/ejn.16474] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2023] [Revised: 06/12/2024] [Accepted: 07/07/2024] [Indexed: 07/30/2024]
Abstract
We investigated the impact of the human-specific gene CHRFAM7A on the function of α7 nicotinic acetylcholine receptors (α7 nAChRs) in two different types of neurons: human-induced pluripotent stem cell (hiPSC)-derived cortical neurons, and superior cervical ganglion (SCG) neurons, taken from transgenic mice expressing CHRFAM7A. dupα7, the gene product of CHRFAM7A, which lacks a major part of the extracellular N-terminal ligand-binding domain, co-assembles with α7, the gene product of CHRNA7. We assessed the receptor function in hiPSC-derived cortical and SCG neurons with Fura-2 calcium imaging and three different α7-specific ligands: PNU282987, choline, and 4BP-TQS. Given the short-lived open state of α7 receptors, we combined the two orthosteric agonists PNU282987 and choline with the type-2 positive allosteric modulator (PAM II) PNU120596. In line with different cellular models used previously, we demonstrate that CHRFAM7A has a major impact on nicotinic α7 nAChRs by reducing calcium transients in response to all three agonists.
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Affiliation(s)
- Ilayda Görgülü
- Center for Brain Research, Medical University of Vienna, Vienna, Austria
| | - Vinita Jagannath
- Institut du Fer à Moulin, Sorbonne University, UMR-S 1270, Paris, France
- MSD R&D Innovation Centre, London, UK
| | - Stephanie Pons
- Integrative Neurobiology of Cholinergic Systems, Institut Pasteur, Université Paris Cité, UMR 3571, Paris, France
| | - Filip Koniuszewski
- Center for Brain Research, Medical University of Vienna, Vienna, Austria
| | - Matthias Groszer
- Institut du Fer à Moulin, Sorbonne University, UMR-S 1270, Paris, France
| | - Uwe Maskos
- Integrative Neurobiology of Cholinergic Systems, Institut Pasteur, Université Paris Cité, UMR 3571, Paris, France
| | - Sigismund Huck
- Center for Brain Research, Medical University of Vienna, Vienna, Austria
| | - Petra Scholze
- Center for Brain Research, Medical University of Vienna, Vienna, Austria
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2
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Mukhtasimova N, Bouzat C, Sine SM. Novel interplay between agonist and calcium binding sites modulates drug potentiation of α7 acetylcholine receptor. Cell Mol Life Sci 2024; 81:332. [PMID: 39110172 PMCID: PMC11335256 DOI: 10.1007/s00018-024-05374-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2024] [Revised: 07/15/2024] [Accepted: 07/18/2024] [Indexed: 08/22/2024]
Abstract
Drug modulation of the α7 acetylcholine receptor has emerged as a therapeutic strategy for neurological, neurodegenerative, and inflammatory disorders. α7 is a homo-pentamer containing topographically distinct sites for agonists, calcium, and drug modulators with each type of site present in five copies. However, functional relationships between agonist, calcium, and drug modulator sites remain poorly understood. To investigate these relationships, we manipulated the number of agonist binding sites, and monitored potentiation of ACh-elicited single-channel currents through α7 receptors by PNU-120596 (PNU) both in the presence and absence of calcium. When ACh is present alone, it elicits brief, sub-millisecond channel openings, however when ACh is present with PNU it elicits long clusters of potentiated openings. In receptors harboring five agonist binding sites, PNU potentiates regardless of the presence or absence of calcium, whereas in receptors harboring one agonist binding site, PNU potentiates in the presence but not the absence of calcium. By varying the numbers of agonist and calcium binding sites we show that PNU potentiation of α7 depends on a balance between agonist occupancy of the orthosteric sites and calcium occupancy of the allosteric sites. The findings suggest that in the local cellular environment, fluctuations in the concentrations of neurotransmitter and calcium may alter this balance and modulate the ability of PNU to potentiate α7.
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Affiliation(s)
- Nuriya Mukhtasimova
- Department of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine and Science, Rochester, MN, USA
| | - Cecilia Bouzat
- Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur and Instituto de Investigaciones Bioquímicas de Bahía Blanca, Consejo Nacional de Investigaciones Científicas y Técnicas, Bahía Blanca, Argentina
| | - Steven M Sine
- Department of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine and Science, Rochester, MN, USA.
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic College of Medicine and Science, Rochester, MN, USA.
- Department of Neurology, Mayo Clinic College of Medicine and Science, Rochester, MN, USA.
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3
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Chen F, Zhang Z, Zhang H, Guo P, Feng J, Shen H, Liu X. Activation of α7 Nicotinic Acetylcholine Receptor Improves Muscle Endurance by Upregulating Orosomucoid Expression and Glycogen Content in Mice. J Cell Biochem 2024:e30630. [PMID: 39014907 DOI: 10.1002/jcb.30630] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2024] [Revised: 06/13/2024] [Accepted: 07/01/2024] [Indexed: 07/18/2024]
Abstract
There are presently no acknowledged therapeutic targets or official drugs for the treatment of muscle fatigue. The alpha7 nicotinic acetylcholine receptor (α7nAChR) is expressed in skeletal muscle, with an unknown role in muscle endurance. Here, we try to explore whether α7nAChR could act as a potential therapeutic target for the treatment of muscle fatigue. Results showed that nicotine and PNU-282987 (PNU), as nonspecific and specific agonists of α7nAChR, respectively, could both significantly increase C57BL6/J mice treadmill-running time in a time- and dose-dependent manner. The improvement effect of PNU on running time and ex vivo muscle fatigue index disappeared when α7nAChR deletion. RNA sequencing revealed that the differential mRNAs affected by PNU were enriched in glycolysis/gluconeogenesis signaling pathways. Further studies found that PNU treatment significantly elevates glycogen content and ATP level in the muscle tissues of α7nAChR+/+ mice but not α7nAChR-/- mice. α7nAChR activation specifically increased endogenous glycogen-targeting protein orosomucoid (ORM) expression both in vivo skeletal muscle tissues and in vitro C2C12 skeletal muscle cells. In ORM1 deficient mice, the positive effects of PNU on running time, glycogen and ATP content, as well as muscle fatigue index, were abolished. Therefore, the activation of α7nAChR could enhance muscle endurance via elevating endogenous anti-fatigue protein ORM and might act as a promising therapeutic strategy for the treatment of muscle fatigue.
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Affiliation(s)
- Fei Chen
- Department of Clinical Pharmacy, School of Pharmacy, Second Military Medical University, Shanghai, China
| | - Zhen Zhang
- Department of Clinical Pharmacy, School of Pharmacy, Second Military Medical University, Shanghai, China
- Department of Nutrition and Food Hygiene, Second Military Medical University, Shanghai, China
| | - Huimin Zhang
- Department of Clinical Pharmacy, School of Pharmacy, Second Military Medical University, Shanghai, China
| | - Pengyue Guo
- Department of Clinical Pharmacy, School of Pharmacy, Second Military Medical University, Shanghai, China
| | - Jiayi Feng
- Department of Clinical Pharmacy, School of Pharmacy, Second Military Medical University, Shanghai, China
| | - Hui Shen
- Department of Nutrition and Food Hygiene, Second Military Medical University, Shanghai, China
| | - Xia Liu
- Department of Clinical Pharmacy, School of Pharmacy, Second Military Medical University, Shanghai, China
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4
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Dallanoce C, Richter K, Stokes C, Papotto C, Andleeb H, Thakur GA, Kerr A, Grau V, Papke RL. New Alpha9 nAChR Ligands Based on a 5-(Quinuclidin-3-ylmethyl)-1,2,4-oxadiazole Scaffold. ACS Chem Neurosci 2024; 15:827-843. [PMID: 38335726 PMCID: PMC11274740 DOI: 10.1021/acschemneuro.3c00720] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/12/2024] Open
Abstract
Several lines of evidence have indicated that nicotinic acetylcholine receptors (nAChR) that contain α9 subunits, probably in combination with α10 subunits, may be valuable targets for the management of pain associated with inflammatory diseases through a cholinergic anti-inflammatory system (CAS), which has also been associated with α7 nAChR. Both α7- and α9-containing neuronal nAChR can be pharmacologically distinguished from the high-affinity nicotinic receptors of the brain by their sensitivity to α-bungarotoxin, but in other ways, they have quite distinct pharmacological profiles. The early association of α7 with CAS led to the development of numerous new ligands, variously characterized as α7 agonists, partial agonists, or silent agonists that desensitized α7 receptors without activation. Subsequent reinvestigation of one such family of α7 ligands based on an N,N-diethyl-N'-phenylpiperazine scaffold led to the identification of potent agonists and antagonists for α9. In this paper, we characterize the α9/α10 activity of a series of compounds based on a 5-(quinuclidin-3-ylmethyl)-1,2,4-oxadiazole (QMO) scaffold and identify two new potent ligands of α9, QMO-28, an agonist, and QMO-17, an antagonist. We separated the stereoisomers of these compounds to identify the most potent agonist and discovered that only the 3R isomer of QMO-17 was an α9 antagonist, permitting an in silico model of α9 antagonism to be developed. The α9 activity of these compounds was confirmed to be potentially useful for CAS management of inflammatory pain in cell-based assays of cytokine release.
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Affiliation(s)
- Clelia Dallanoce
- Department of Pharmaceutical Sciences, Medicinal Chemistry Section "Pietro Pratesi″, University of Milan, Via L. Mangiagalli 25, 20133 Milan, Italy
| | - Katrin Richter
- Department of General and Thoracic Surgery, Laboratory of Experimental Surgery, Justus-Liebig-University, German Center for Lung Research [DZL], Cardio-Pulmonary Institute [CPI], Giessen 35390, Germany
| | - Clare Stokes
- Department of Pharmacology and Therapeutics, University of Florida, PO Box 100267, Gainesville, Florida 32610 United States
| | - Claudio Papotto
- Department of Pharmaceutical Sciences, Medicinal Chemistry Section "Pietro Pratesi″, University of Milan, Via L. Mangiagalli 25, 20133 Milan, Italy
| | - Hina Andleeb
- Department of Pharmaceutical Sciences, School of Pharmacy and Pharmaceutical Sciences, Bouvé College of Health Sciences, Northeastern University, Boston, Massachusetts 02115, United States
| | - Ganesh A Thakur
- Department of Pharmaceutical Sciences, School of Pharmacy and Pharmaceutical Sciences, Bouvé College of Health Sciences, Northeastern University, Boston, Massachusetts 02115, United States
| | - Andrew Kerr
- United States Naval Research Laboratory, 6920 Washington, District of Columbia, United States
| | - Veronika Grau
- Department of General and Thoracic Surgery, Laboratory of Experimental Surgery, Justus-Liebig-University, German Center for Lung Research [DZL], Cardio-Pulmonary Institute [CPI], Giessen 35390, Germany
| | - Roger L Papke
- Department of Pharmacology and Therapeutics, University of Florida, PO Box 100267, Gainesville, Florida 32610 United States
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5
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Sansone L, Milani F, Fabrizi R, Belli M, Cristina M, Zagà V, de Iure A, Cicconi L, Bonassi S, Russo P. Nicotine: From Discovery to Biological Effects. Int J Mol Sci 2023; 24:14570. [PMID: 37834017 PMCID: PMC10572882 DOI: 10.3390/ijms241914570] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2023] [Revised: 09/21/2023] [Accepted: 09/23/2023] [Indexed: 10/15/2023] Open
Abstract
Nicotine, the primary psychoactive agent in tobacco leaves, has led to the widespread use of tobacco, with over one billion smokers globally. This article provides a historical overview of tobacco and discusses tobacco dependence, as well as the biological effects induced by nicotine on mammalian cells. Nicotine induces various biological effects, such as neoangiogenesis, cell division, and proliferation, and it affects neural and non-neural cells through specific pathways downstream of nicotinic receptors (nAChRs). Specific effects mediated by α7 nAChRs are highlighted. Nicotine is highly addictive and hazardous. Public health initiatives should prioritize combating smoking and its associated risks. Understanding nicotine's complex biological effects is essential for comprehensive research and informed health policies. While potential links between nicotine and COVID-19 severity warrant further investigation, smoking remains a significant cause of morbidity and mortality globally. Effective public health strategies are vital to promote healthier lifestyles.
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Affiliation(s)
- Luigi Sansone
- Department of Human Sciences and Quality, Life Promotion San Raffaele University, Via di Val Cannuta 247, 00166 Rome, Italy; (L.S.); (M.B.); (M.C.); (A.d.I.); (S.B.)
- MEBIC Consortium, San Raffaele University, 00166 Rome, Italy
| | - Francesca Milani
- Clinical and Molecular Epidemiology, IRCCS San Raffaele Roma, Via di Val Cannuta 247, 00166 Rome, Italy; (F.M.); (R.F.); (L.C.)
| | - Riccardo Fabrizi
- Clinical and Molecular Epidemiology, IRCCS San Raffaele Roma, Via di Val Cannuta 247, 00166 Rome, Italy; (F.M.); (R.F.); (L.C.)
| | - Manuel Belli
- Department of Human Sciences and Quality, Life Promotion San Raffaele University, Via di Val Cannuta 247, 00166 Rome, Italy; (L.S.); (M.B.); (M.C.); (A.d.I.); (S.B.)
- MEBIC Consortium, San Raffaele University, 00166 Rome, Italy
| | - Mario Cristina
- Department of Human Sciences and Quality, Life Promotion San Raffaele University, Via di Val Cannuta 247, 00166 Rome, Italy; (L.S.); (M.B.); (M.C.); (A.d.I.); (S.B.)
- Department of Molecular Medicine, University La Sapienza, Viale del Policlinico 155, 00161 Rome, Italy
| | - Vincenzo Zagà
- Italian Society of Tabaccology (SITAB), 00136 Bologna, Italy;
| | - Antonio de Iure
- Department of Human Sciences and Quality, Life Promotion San Raffaele University, Via di Val Cannuta 247, 00166 Rome, Italy; (L.S.); (M.B.); (M.C.); (A.d.I.); (S.B.)
- Experimental Neurophysiology IRCCS San Raffaele Roma, Via di Val Cannuta 247, 00166 Rome, Italy
| | - Luca Cicconi
- Clinical and Molecular Epidemiology, IRCCS San Raffaele Roma, Via di Val Cannuta 247, 00166 Rome, Italy; (F.M.); (R.F.); (L.C.)
| | - Stefano Bonassi
- Department of Human Sciences and Quality, Life Promotion San Raffaele University, Via di Val Cannuta 247, 00166 Rome, Italy; (L.S.); (M.B.); (M.C.); (A.d.I.); (S.B.)
- Clinical and Molecular Epidemiology, IRCCS San Raffaele Roma, Via di Val Cannuta 247, 00166 Rome, Italy; (F.M.); (R.F.); (L.C.)
| | - Patrizia Russo
- Department of Human Sciences and Quality, Life Promotion San Raffaele University, Via di Val Cannuta 247, 00166 Rome, Italy; (L.S.); (M.B.); (M.C.); (A.d.I.); (S.B.)
- MEBIC Consortium, San Raffaele University, 00166 Rome, Italy
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6
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Viscarra F, Chrestia JF, Sanchez Y, Pérez EG, Biggin PC, Bouzat C, Bermudez I, López JJ. Side Groups Convert the α7 Nicotinic Receptor Agonist Ether Quinuclidine into a Type I Positive Allosteric Modulator. ACS Chem Neurosci 2023; 14:2876-2887. [PMID: 37535446 DOI: 10.1021/acschemneuro.3c00225] [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: 08/05/2023] Open
Abstract
The quinuclidine scaffold has been extensively used for the development of nicotinic acetylcholine receptor (nAChR) agonists, with hydrophobic substituents at position 3 of the quinuclidine framework providing selectivity for α7 nAChRs. In this study, six new ligands (4-9) containing a 3-(pyridin-3-yloxy)quinuclidine moiety (ether quinuclidine) were synthesized to gain a better understanding of the structural-functional properties of ether quinuclidines. To evaluate the pharmacological activity of these ligands, two-electrode voltage-clamp and single-channel recordings were performed. Only ligand 4 activated α7 nAChR. Ligands 5 and 7 had no effects on α7 nAChR, but ligands 6, 8, and 9 potentiated the currents evoked by ACh. Ligand 6 was the most potent and efficacious of the potentiating ligands, with an estimated EC50 for potentiation of 12.6 ± 3.32 μM and a maximal potentiation of EC20 ACh responses of 850 ± 120%. Ligand 6 increased the maximal ACh responses without changing the kinetics of the current responses. At the single-channel level, the potentiation exerted by ligand 6 was evidenced in the low micromolar concentration range by the appearance of prolonged bursts of channel openings. Furthermore, computational studies revealed the preference of ligand 6 for an intersubunit site in the transmembrane domain and highlighted some putative key interactions that explain the different profiles of the synthesized ligands. Notably, Met276 in the 15' position of the transmembrane domain 2 almost abolished the effects of ligand 6 when mutated to Leu. We conclude that ligand 6 is a novel type I positive allosteric modulator (PAM-I) of α7 nAChR.
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Affiliation(s)
- Franco Viscarra
- Department of Biological and Medical Sciences, Oxford Brookes University, Gipsy Lane, Oxford OX3 0BP, U.K
- Structural Bioinformatics and Computational Biochemistry, Department of Biochemistry, Oxford University, South Parks Road, Oxford OX1 3QU, U.K
| | - Juan Facundo Chrestia
- Departamento de Biología, Bioquímica y Farmacia, Instituto de Investigaciones Bioquímicas de Bahía Blanca, Universidad Nacional del Sur-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Camino La Carrindanga Km 7, Bahía Blanca 8000, Argentina
| | - Yaima Sanchez
- Department of Organic Chemistry, Faculty of Chemistry, Universidad de Concepción, Edmundo Larenas 129, Concepción 4070371, Chile
| | - Edwin G Pérez
- Department of Organic Chemistry, Faculty of Chemistry and Pharmacy, Pontificia Universidad Católica de Chile, Av. Vicuña Mackenna 4860, Santiago 7820436, Chile
| | - Philip C Biggin
- Structural Bioinformatics and Computational Biochemistry, Department of Biochemistry, Oxford University, South Parks Road, Oxford OX1 3QU, U.K
| | - Cecilia Bouzat
- Departamento de Biología, Bioquímica y Farmacia, Instituto de Investigaciones Bioquímicas de Bahía Blanca, Universidad Nacional del Sur-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Camino La Carrindanga Km 7, Bahía Blanca 8000, Argentina
| | - Isabel Bermudez
- Department of Biological and Medical Sciences, Oxford Brookes University, Gipsy Lane, Oxford OX3 0BP, U.K
| | - Jhon J López
- Department of Organic Chemistry, Faculty of Chemistry, Universidad de Concepción, Edmundo Larenas 129, Concepción 4070371, Chile
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7
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Schreiber JA, Derksen A, Goerges G, Schütte S, Sörgel J, Kiper AK, Strutz-Seebohm N, Ruck T, Meuth SG, Decher N, Seebohm G. Cloxyquin activates hTRESK by allosteric modulation of the selectivity filter. Commun Biol 2023; 6:745. [PMID: 37464013 PMCID: PMC10354012 DOI: 10.1038/s42003-023-05114-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Accepted: 07/07/2023] [Indexed: 07/20/2023] Open
Abstract
The TWIK-related spinal cord K+ channel (TRESK, K2P18.1) is a K2P channel contributing to the maintenance of membrane potentials in various cells. Recently, physiological TRESK function was identified as a key player in T-cell differentiation rendering the channel a new pharmacological target for treatment of autoimmune diseases. The channel activator cloxyquin represents a promising lead compound for the development of a new class of immunomodulators. Identification of cloxyquin binding site and characterization of the molecular activation mechanism can foster the future drug development. Here, we identify the cloxyquin binding site at the M2/M4 interface by mutational scan and analyze the molecular mechanism of action by protein modeling as well as in silico and in vitro electrophysiology using different permeating ion species (K+ / Rb+). In combination with kinetic analyses of channel inactivation, our results suggest that cloxyquin allosterically stabilizes the inner selectivity filter facilitating the conduction process subsequently activating hTRESK.
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Affiliation(s)
- Julian Alexander Schreiber
- Institute for Genetics of Heart Diseases (IfGH), Department of Cardiovascular Medicine, University Hospital Münster, Robert-Koch-Str. 45, Münster, Germany.
- Westfälische Wilhelms-Universität Münster, Institut für Pharmazeutische und Medizinische Chemie, Corrensstr. 48, Münster, Germany.
| | - Anastasia Derksen
- Westfälische Wilhelms-Universität Münster, Institut für Pharmazeutische und Medizinische Chemie, Corrensstr. 48, Münster, Germany
| | - Gunnar Goerges
- Institute for Genetics of Heart Diseases (IfGH), Department of Cardiovascular Medicine, University Hospital Münster, Robert-Koch-Str. 45, Münster, Germany
| | - Sven Schütte
- Institute of Physiology and Pathophysiology, Vegetative Physiology, Philipps-University Marburg, Marburg, Germany
| | - Jasmin Sörgel
- Westfälische Wilhelms-Universität Münster, Institut für Pharmazeutische und Medizinische Chemie, Corrensstr. 48, Münster, Germany
| | - Aytug K Kiper
- Institute of Physiology and Pathophysiology, Vegetative Physiology, Philipps-University Marburg, Marburg, Germany
| | - Nathalie Strutz-Seebohm
- Institute for Genetics of Heart Diseases (IfGH), Department of Cardiovascular Medicine, University Hospital Münster, Robert-Koch-Str. 45, Münster, Germany
| | - Tobias Ruck
- Department of Neurology, Medical Faculty, Heinrich-Heine University, Düsseldorf, Germany
| | - Sven G Meuth
- Department of Neurology, Medical Faculty, Heinrich-Heine University, Düsseldorf, Germany
| | - Niels Decher
- Institute of Physiology and Pathophysiology, Vegetative Physiology, Philipps-University Marburg, Marburg, Germany
| | - Guiscard Seebohm
- Institute for Genetics of Heart Diseases (IfGH), Department of Cardiovascular Medicine, University Hospital Münster, Robert-Koch-Str. 45, Münster, Germany
- Westfälische Wilhelms-Universität Münster, GRK 2515, Chemical biology of ion channels (Chembion), Münster, Germany
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8
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Giraudo A, Pallavicini M, Bolchi C. Small molecule ligands for α9* and α7 nicotinic receptors: a survey and an update, respectively. Pharmacol Res 2023; 193:106801. [PMID: 37236412 DOI: 10.1016/j.phrs.2023.106801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Revised: 05/16/2023] [Accepted: 05/19/2023] [Indexed: 05/28/2023]
Abstract
The α9- and α7-containing nicotinic acetylcholine receptors (nAChRs) mediate numerous physiological and pathological processes by complex mechanisms that are currently the subject of intensive study and debate. In this regard, selective ligands serve as invaluable investigative tools and, in many cases, potential therapeutics for the treatment of various CNS disfunctions and diseases, neuropathic pain, inflammation, and cancer. However, the present scenario differs significantly between the two aforementioned nicotinic subtypes. Over the past few decades, a large number of selective α7-nAChR ligands, including full, partial and silent agonists, antagonists, and allosteric modulators, have been described and reviewed. Conversely, reports on selective α9-containing nAChR ligands are relatively scarce, also due to a more recent characterization of this receptor subtype, and hardly any focusing on small molecules. In this review, we focus on the latter, providing a comprehensive overview, while providing only an update over the last five years for α7-nAChR ligands.
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Affiliation(s)
- Alessandro Giraudo
- Department of Pharmaceutical Sciences, University of Milan, via Mangiagalli 25, I-20133 Milano, Italy
| | - Marco Pallavicini
- Department of Pharmaceutical Sciences, University of Milan, via Mangiagalli 25, I-20133 Milano, Italy
| | - Cristiano Bolchi
- Department of Pharmaceutical Sciences, University of Milan, via Mangiagalli 25, I-20133 Milano, Italy.
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9
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Tessier CJG, Emlaw JR, Sturgeon RM, daCosta CJB. Derepression may masquerade as activation in ligand-gated ion channels. Nat Commun 2023; 14:1907. [PMID: 37019877 PMCID: PMC10076327 DOI: 10.1038/s41467-023-36770-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2022] [Accepted: 02/16/2023] [Indexed: 04/07/2023] Open
Abstract
Agonists are ligands that bind to receptors and activate them. In the case of ligand-gated ion channels, such as the muscle-type nicotinic acetylcholine receptor, mechanisms of agonist activation have been studied for decades. Taking advantage of a reconstructed ancestral muscle-type β-subunit that forms spontaneously activating homopentamers, here we show that incorporation of human muscle-type α-subunits appears to repress spontaneous activity, and furthermore that the presence of agonist relieves this apparent α-subunit-dependent repression. Our results demonstrate that rather than provoking channel activation/opening, agonists may instead 'inhibit the inhibition' of intrinsic spontaneous activity. Thus, agonist activation may be the apparent manifestation of agonist-induced derepression. These results provide insight into intermediate states that precede channel opening and have implications for the interpretation of agonism in ligand-gated ion channels.
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Affiliation(s)
- Christian J G Tessier
- Department of Chemistry and Biomolecular Sciences, Centre for Chemical and Synthetic Biology, University of Ottawa, Ottawa, ON, Canada
| | - Johnathon R Emlaw
- Department of Chemistry and Biomolecular Sciences, Centre for Chemical and Synthetic Biology, University of Ottawa, Ottawa, ON, Canada
| | - Raymond M Sturgeon
- Department of Chemistry and Biomolecular Sciences, Centre for Chemical and Synthetic Biology, University of Ottawa, Ottawa, ON, Canada
| | - Corrie J B daCosta
- Department of Chemistry and Biomolecular Sciences, Centre for Chemical and Synthetic Biology, University of Ottawa, Ottawa, ON, Canada.
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10
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Papke RL, Quadri M, Gulsevin A. Silent agonists for α7 nicotinic acetylcholine receptors. Pharmacol Res 2023; 190:106736. [PMID: 36940890 DOI: 10.1016/j.phrs.2023.106736] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/10/2022] [Revised: 03/07/2023] [Accepted: 03/14/2023] [Indexed: 03/23/2023]
Abstract
We discuss models for the activation and desensitization of α7 nicotinic acetylcholine receptors (nAChRs) and the effects of efficacious type II positive allosteric modulators (PAMs) that destabilize α7 desensitized states. Type II PAMs such as PNU-120596 can be used to distinguish inactive compounds from silent agonists, compounds that produce little or no channel activation but stabilize the non-conducting conformations associated with desensitization. We discuss the effects of α7 nAChRs in cells of the immune system and their roles in modulating inflammation and pain through what has come to be known as the cholinergic anti-inflammatory system (CAS). Cells controlling CAS do not generate ion channel currents but rather respond to α7 drugs by modulating intracellular signaling pathways analogous to the effects of metabotropic receptors. Metabotropic signaling by α7 receptors appears to be mediated by receptors in nonconducting conformations and can be accomplished by silent agonists. We discuss electrophysiological structure-activity relationships for α7 silent agonists and their use in cell-based and in vivo assays for CAS regulation. We discuss the strongly desensitizing partial agonist GTS-21 and its effectiveness in modulation of CAS. We also review the properties of the silent agonist NS6740, which is remarkably effective at maintaining α7 receptors in PAM-sensitive desensitized states. Most silent agonists bind to sites overlapping those for orthosteric agonists, but some appear to bind to allosteric sites. Finally, we discuss α9⁎ nAChRs and their potential role in CAS, and ligands that will be useful in defining and distinguishing the specific roles of α7 and α9 in CAS.
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Affiliation(s)
- Roger L Papke
- Department of Pharmacology and Therapeutics, University of Florida, PO Box 100267 Gainesville, FL 32610 USA (RLP); Olon S.p.A., Strada Rivoltana, Km 6/7 - 20053 Rodano (MI) - ITALY (MQ); Department of Chemistry, Center for Structural Biology, Vanderbilt University, Nashville, Tennessee, USA, 37212 (AG).
| | - Marta Quadri
- Department of Pharmacology and Therapeutics, University of Florida, PO Box 100267 Gainesville, FL 32610 USA (RLP); Olon S.p.A., Strada Rivoltana, Km 6/7 - 20053 Rodano (MI) - ITALY (MQ); Department of Chemistry, Center for Structural Biology, Vanderbilt University, Nashville, Tennessee, USA, 37212 (AG)
| | - Alican Gulsevin
- Department of Pharmacology and Therapeutics, University of Florida, PO Box 100267 Gainesville, FL 32610 USA (RLP); Olon S.p.A., Strada Rivoltana, Km 6/7 - 20053 Rodano (MI) - ITALY (MQ); Department of Chemistry, Center for Structural Biology, Vanderbilt University, Nashville, Tennessee, USA, 37212 (AG)
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11
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Recent Advances in the Discovery of Nicotinic Acetylcholine Receptor Allosteric Modulators. Molecules 2023; 28:molecules28031270. [PMID: 36770942 PMCID: PMC9920195 DOI: 10.3390/molecules28031270] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Revised: 01/18/2023] [Accepted: 01/26/2023] [Indexed: 01/31/2023] Open
Abstract
Positive allosteric modulators (PAMs), negative allosteric modulators (NAMs), silent agonists, allosteric activating PAMs and neutral or silent allosteric modulators are compounds capable of modulating the nicotinic receptor by interacting at allosteric modulatory sites distinct from the orthosteric sites. This survey is focused on the compounds that have been shown or have been designed to interact with nicotinic receptors as allosteric modulators of different subtypes, mainly α7 and α4β2. Minimal chemical changes can cause a different pharmacological profile, which can then lead to the design of selective modulators. Experimental evidence supports the use of allosteric modulators as therapeutic tools for neurological and non-neurological conditions.
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12
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Cannabidiol as a modulator of α7 nicotinic receptors. Cell Mol Life Sci 2022; 79:564. [DOI: 10.1007/s00018-022-04600-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2022] [Revised: 09/29/2022] [Accepted: 10/14/2022] [Indexed: 11/03/2022]
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13
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Chrestia JF, Oliveira AS, Mulholland AJ, Gallagher T, Bermúdez I, Bouzat C. A Functional Interaction Between Y674-R685 Region of the SARS-CoV-2 Spike Protein and the Human α7 Nicotinic Receptor. Mol Neurobiol 2022; 59:6076-6090. [PMID: 35859025 PMCID: PMC9299415 DOI: 10.1007/s12035-022-02947-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Accepted: 06/28/2022] [Indexed: 11/15/2022]
Abstract
The α7 nicotinic acetylcholine receptor (nAChR) is present in neuronal and non-neuronal cells and has anti-inflammatory actions. Molecular dynamics simulations suggested that α7 nAChR interacts with a region of the SARS-CoV-2 spike protein (S), and a potential contribution of nAChRs to COVID-19 pathophysiology has been proposed. We applied whole-cell and single-channel recordings to determine whether a peptide corresponding to the Y674-R685 region of the S protein can directly affect α7 nAChR function. The S fragment exerts a dual effect on α7. It activates α7 nAChRs in the presence of positive allosteric modulators, in line with our previous molecular dynamics simulations showing favourable binding of this accessible region of the S protein to the nAChR agonist binding site. The S fragment also exerts a negative modulation of α7, which is evidenced by a profound concentration-dependent decrease in the durations of openings and activation episodes of potentiated channels and in the amplitude of macroscopic responses elicited by ACh. Our study identifies a potential functional interaction between α7 nAChR and a region of the S protein, thus providing molecular foundations for further exploring the involvement of nAChRs in COVID-19 pathophysiology.
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Affiliation(s)
- Juan Facundo Chrestia
- Instituto de Investigaciones Bioquímicas de Bahía Blanca, Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur-Consejo Nacional de Investigaciones Científicas Y Técnicas (CONICET), Camino La Carrindanga Km 7-8000, Bahía Blanca, Argentina
| | - Ana Sofia Oliveira
- Centre for Computational Chemistry, School of Chemistry, University of Bristol, Bristol, BS8 1TS, UK
| | - Adrian J Mulholland
- Centre for Computational Chemistry, School of Chemistry, University of Bristol, Bristol, BS8 1TS, UK
| | | | - Isabel Bermúdez
- Department of Biological and Medical Sciences, Oxford Brookes University, Oxford, OX3 0BP, UK.
| | - Cecilia Bouzat
- Instituto de Investigaciones Bioquímicas de Bahía Blanca, Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur-Consejo Nacional de Investigaciones Científicas Y Técnicas (CONICET), Camino La Carrindanga Km 7-8000, Bahía Blanca, Argentina.
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14
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Speculation on How RIC-3 and Other Chaperones Facilitate α7 Nicotinic Receptor Folding and Assembly. MOLECULES (BASEL, SWITZERLAND) 2022; 27:molecules27144527. [PMID: 35889400 PMCID: PMC9318448 DOI: 10.3390/molecules27144527] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Revised: 07/07/2022] [Accepted: 07/09/2022] [Indexed: 11/17/2022]
Abstract
The process of how multimeric transmembrane proteins fold and assemble in the endoplasmic reticulum is not well understood. The alpha7 nicotinic receptor (α7 nAChR) is a good model for multimeric protein assembly since it has at least two independent and specialized chaperones: Resistance to Inhibitors of Cholinesterase 3 (RIC-3) and Nicotinic Acetylcholine Receptor Regulator (NACHO). Recent cryo-EM and NMR data revealed structural features of α7 nAChRs. A ser-ala-pro (SAP) motif precedes a structurally important but unique "latch" helix in α7 nAChRs. A sampling of α7 sequences suggests the SAP motif is conserved from C. elegans to humans, but the latch sequence is only conserved in vertebrates. How RIC-3 and NACHO facilitate receptor subunits folding into their final pentameric configuration is not known. The artificial intelligence program AlphaFold2 recently predicted structures for NACHO and RIC-3. NACHO is highly conserved in sequence and structure across species, but RIC-3 is not. This review ponders how different intrinsically disordered RIC-3 isoforms from C. elegans to humans interact with α7 nAChR subunits despite having little sequence homology across RIC-3 species. Two models from the literature about how RIC-3 assists α7 nAChR assembly are evaluated considering recent structural information about the receptor and its chaperones.
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15
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Tessier CJG, Sturgeon RM, Emlaw JR, McCluskey GD, Pérez-Areales FJ, daCosta CJB. Ancestral acetylcholine receptor β-subunit forms homopentamers that prime before opening spontaneously. eLife 2022; 11:76504. [PMID: 35781368 PMCID: PMC9365395 DOI: 10.7554/elife.76504] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2021] [Accepted: 06/21/2022] [Indexed: 11/13/2022] Open
Abstract
Human adult muscle-type acetylcholine receptors are heteropentameric ion channels formed from two α-subunits, and one each of the β-, d-, and e-subunits. To form functional channels, the subunits must assemble with one another in a precise stoichiometry and arrangement. Despite being different, the four subunits share a common ancestor that is presumed to have formed homopentamers. The extent to which the properties of the modern-day receptor result from its subunit complexity is unknown. Here we discover that a reconstructed ancestral muscle-type β-subunit can form homopentameric ion channels. These homopentamers open spontaneously and display single-channel hallmarks of muscle-type acetylcholine receptor activity. Our findings attest to the homopentameric origin of the muscle-type acetylcholine receptor, and demonstrate that signature features of its function are both independent of agonist and do not necessitate the complex heteropentameric architecture of the modern-day protein.
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Affiliation(s)
| | - R Michel Sturgeon
- Center for Chemical and Synthetic Biology, University of Ottawa, Ottawa, Canada
| | - Johnathon R Emlaw
- Center for Chemical and Synthetic Biology, University of Ottawa, Ottawa, Canada
| | - Gregory D McCluskey
- Center for Chemical and Synthetic Biology, University of Ottawa, Ottawa, Canada
| | | | - Corrie J B daCosta
- Center for Chemical and Synthetic Biology, University of Ottawa, Ottawa, Canada
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16
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Di Lascio S, Fornasari D, Benfante R. The Human-Restricted Isoform of the α7 nAChR, CHRFAM7A: A Double-Edged Sword in Neurological and Inflammatory Disorders. Int J Mol Sci 2022; 23:ijms23073463. [PMID: 35408823 PMCID: PMC8998457 DOI: 10.3390/ijms23073463] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Revised: 03/13/2022] [Accepted: 03/21/2022] [Indexed: 12/13/2022] Open
Abstract
CHRFAM7A is a relatively recent and exclusively human gene arising from the partial duplication of exons 5 to 10 of the α7 neuronal nicotinic acetylcholine receptor subunit (α7 nAChR) encoding gene, CHRNA7. CHRNA7 is related to several disorders that involve cognitive deficits, including neuropsychiatric, neurodegenerative, and inflammatory disorders. In extra-neuronal tissues, α7nAChR plays an important role in proliferation, differentiation, migration, adhesion, cell contact, apoptosis, angiogenesis, and tumor progression, as well as in the modulation of the inflammatory response through the “cholinergic anti-inflammatory pathway”. CHRFAM7A translates the dupα7 protein in a multitude of cell lines and heterologous systems, while maintaining processing and trafficking that are very similar to the full-length form. It does not form functional ion channel receptors alone. In the presence of CHRNA7 gene products, dupα7 can assemble and form heteromeric receptors that, in order to be functional, should include at least two α7 subunits to form the agonist binding site. When incorporated into the receptor, in vitro and in vivo data showed that dupα7 negatively modulated α7 activity, probably due to a reduction in the number of ACh binding sites. Very recent data in the literature report that the presence of the duplicated gene may be responsible for the translational gap in several human diseases. Here, we will review the studies that have been conducted on CHRFAM7A in different pathologies, with the intent of providing evidence regarding when and how the expression of this duplicated gene may be beneficial or detrimental in the pathogenesis, and eventually in the therapeutic response, to CHRNA7-related neurological and non-neurological diseases.
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Affiliation(s)
- Simona Di Lascio
- Department of Medical Biotechnology and Translational Medicine (BIOMETRA), Università degli Studi di Milano, 20129 Milan, Italy; (S.D.L.); (D.F.)
| | - Diego Fornasari
- Department of Medical Biotechnology and Translational Medicine (BIOMETRA), Università degli Studi di Milano, 20129 Milan, Italy; (S.D.L.); (D.F.)
- CNR Institute of Neuroscience, 20845 Vedano al Lambro, Italy
| | - Roberta Benfante
- Department of Medical Biotechnology and Translational Medicine (BIOMETRA), Università degli Studi di Milano, 20129 Milan, Italy; (S.D.L.); (D.F.)
- CNR Institute of Neuroscience, 20845 Vedano al Lambro, Italy
- NeuroMi, Milan Center for Neuroscience, University of Milano Bicocca, 20126 Milan, Italy
- Correspondence:
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17
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Natarajan K, Mukhtasimova N, Corradi J, Lasala M, Bouzat C, Sine SM. Mechanism of calcium potentiation of the α7 nicotinic acetylcholine receptor. J Gen Physiol 2021; 152:151971. [PMID: 32702089 PMCID: PMC7478872 DOI: 10.1085/jgp.202012606] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2020] [Revised: 05/19/2020] [Accepted: 06/22/2020] [Indexed: 12/14/2022] Open
Abstract
The α7 nicotinic acetylcholine receptor (nAChR) is among the most abundant types of nAChR in the brain, yet the ability of nerve-released ACh to activate α7 remains enigmatic. In particular, a major population of α7 resides in extra-synaptic regions where the ACh concentration is reduced, owing to dilution and enzymatic hydrolysis, yet ACh shows low potency in activating α7. Using high-resolution single-channel recording techniques, we show that extracellular calcium is a powerful potentiator of α7 activated by low concentrations of ACh. Potentiation manifests as robust increases in the frequency of channel opening and the average duration of the openings. Molecular dynamics simulations reveal that calcium binds to the periphery of the five ligand binding sites and is framed by a pair of anionic residues from the principal and complementary faces of each site. Mutation of residues identified by simulation prevents calcium from potentiating ACh-elicited channel opening. An anionic residue is conserved at each of the identified positions in all vertebrate species of α7. Thus, calcium associates with a novel structural motif on α7 and is an obligate cofactor in regions of limited ACh concentration.
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Affiliation(s)
- Kathiresan Natarajan
- Receptor Biology Laboratory, Department of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine, Rochester, MN
| | - Nuriya Mukhtasimova
- Receptor Biology Laboratory, Department of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine, Rochester, MN
| | - Jeremías Corradi
- Instituto de Investigaciones Bioquímicas, Departamento de Biologia, Bioquimica y Farmacia, Universidad Nacional del Sur-Consejo Nacional de Investigaciones Científicas y Técnicas, Bahía Blanca, Argentina
| | - Matías Lasala
- Instituto de Investigaciones Bioquímicas, Departamento de Biologia, Bioquimica y Farmacia, Universidad Nacional del Sur-Consejo Nacional de Investigaciones Científicas y Técnicas, Bahía Blanca, Argentina
| | - Cecilia Bouzat
- Instituto de Investigaciones Bioquímicas, Departamento de Biologia, Bioquimica y Farmacia, Universidad Nacional del Sur-Consejo Nacional de Investigaciones Científicas y Técnicas, Bahía Blanca, Argentina
| | - Steven M Sine
- Receptor Biology Laboratory, Department of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine, Rochester, MN.,Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic College of Medicine, Rochester, MN.,Department of Neurology, Mayo Clinic College of Medicine, Rochester, MN
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18
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Borroni V, Barrantes FJ. Homomeric and Heteromeric α7 Nicotinic Acetylcholine Receptors in Health and Some Central Nervous System Diseases. MEMBRANES 2021; 11:membranes11090664. [PMID: 34564481 PMCID: PMC8465519 DOI: 10.3390/membranes11090664] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Revised: 08/24/2021] [Accepted: 08/24/2021] [Indexed: 11/22/2022]
Abstract
Nicotinic acetylcholine receptors (nAChRs) are pentameric ligand-gated ion channels involved in the modulation of essential brain functions such as memory, learning, and attention. Homomeric α7 nAChR, formed exclusively by five identical α7 subunits, is involved in rapid synaptic transmission, whereas the heteromeric oligomers composed of α7 in combination with β subunits display metabotropic properties and operate in slower time frames. At the cellular level, the activation of nAChRs allows the entry of Na+ and Ca2+; the two cations depolarize the membrane and trigger diverse cellular signals, depending on the type of nAChR pentamer and neurons involved, the location of the intervening cells, and the networks of which these neuronal cells form part. These features make the α7 nAChR a central player in neurotransmission, metabolically associated Ca2+-mediated signaling, and modulation of diverse fundamental processes operated by other neurotransmitters in the brain. Due to its ubiquitous distribution and the multiple functions it displays in the brain, the α7 nAChR is associated with a variety of neurological and neuropsychiatric disorders whose exact etiopathogenic mechanisms are still elusive.
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Affiliation(s)
- Virginia Borroni
- Instituto de Tecnología en Polímeros y Nanotecnología (ITPN-UBA-CONICET), Universidad de Buenos Aires, Ciudad Universitaria, Buenos Aires C1127AAR, Argentina;
| | - Francisco J. Barrantes
- Laboratory of Molecular Neurobiology, Institute for Biomedical Research, UCA–CONICET, Faculty of Medical Sciences, Catholic University of Argentina, Av. Alicia Moreau de Justo 1600, Buenos Aires C1107AAZ, Argentina
- Correspondence:
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19
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A single historical substitution drives an increase in acetylcholine receptor complexity. Proc Natl Acad Sci U S A 2021; 118:2018731118. [PMID: 33579823 DOI: 10.1073/pnas.2018731118] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Human adult muscle-type acetylcholine receptors are heteropentameric ion channels formed from four different, but evolutionarily related, subunits. These subunits assemble with a precise stoichiometry and arrangement such that two chemically distinct agonist-binding sites are formed between specific subunit pairs. How this subunit complexity evolved and became entrenched is unclear. Here we show that a single historical amino acid substitution is able to constrain the subunit stoichiometry of functional acetylcholine receptors. Using a combination of ancestral sequence reconstruction, single-channel electrophysiology, and concatenated subunits, we reveal that an ancestral β-subunit can not only replace the extant β-subunit but can also supplant the neighboring δ-subunit. By forward evolving the ancestral β-subunit with a single amino acid substitution, we restore the requirement for a δ-subunit for functional channels. These findings reveal that a single historical substitution necessitates an increase in acetylcholine receptor complexity and, more generally, that simple stepwise mutations can drive subunit entrenchment in this model heteromeric protein.
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20
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Abstract
The α7-type nicotinic acetylcholine receptor is one of the most unique and interesting of all the members of the cys-loop superfamily of ligand-gated ion channels. Since it was first identified initially as a binding site for α-bungarotoxin in mammalian brain and later as a functional homomeric receptor with relatively high calcium permeability, it has been pursued as a potential therapeutic target for numerous indications, from Alzheimer disease to asthma. In this review, we discuss the history and state of the art for targeting α7 receptors, beginning with subtype-selective agonists and the basic pharmacophore for the selective activation of α7 receptors. A key feature of α7 receptors is their rapid desensitization by standard "orthosteric" agonist, and we discuss insights into the conformational landscape of α7 receptors that has been gained by the development of ligands binding to allosteric sites. Some of these sites are targeted by positive allosteric modulators that have a wide range of effects on the activation profile of the receptors. Other sites are targeted by direct allosteric agonist or antagonists. We include a perspective on the potential importance of α7 receptors for metabotropic as well as ionotropic signaling. We outline the challenges that exist for future development of drugs to target this important receptor and approaches that may be considered to address those challenges. SIGNIFICANCE STATEMENT: The α7-type nicotinic acetylcholine receptor (nAChR) is acknowledged as a potentially important therapeutic target with functional properties associated with both ionotropic and metabotropic signaling. The functional properties of α7 nAChR can be regulated in diverse ways with the variety of orthosteric and allosteric ligands described in this review.
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Affiliation(s)
- Roger L Papke
- Departments of Pharmacology and Therapeutics (R.L.P) and Chemistry (N.A.H.), University of Florida, Gainesville, FL
| | - Nicole A Horenstein
- Departments of Pharmacology and Therapeutics (R.L.P) and Chemistry (N.A.H.), University of Florida, Gainesville, FL
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21
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Stone TW. Relationships and Interactions between Ionotropic Glutamate Receptors and Nicotinic Receptors in the CNS. Neuroscience 2021; 468:321-365. [PMID: 34111447 DOI: 10.1016/j.neuroscience.2021.06.007] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2021] [Revised: 06/03/2021] [Accepted: 06/04/2021] [Indexed: 02/07/2023]
Abstract
Although ionotropic glutamate receptors and nicotinic receptors for acetylcholine (ACh) have usually been studied separately, they are often co-localized and functionally inter-dependent. The objective of this review is to survey the evidence for interactions between the two receptor families and the mechanisms underlying them. These include the mutual regulation of subunit expression, which change the NMDA:AMPA response balance, and the existence of multi-functional receptor complexes which make it difficult to distinguish between individual receptor sites, especially in vivo. This is followed by analysis of the functional relationships between the receptors from work on transmitter release, cellular electrophysiology and aspects of behavior where these can contribute to understanding receptor interactions. It is clear that nicotinic receptors (nAChRs) on axonal terminals directly regulate the release of glutamate and other neurotransmitters, α7-nAChRs generally promoting release. Hence, α7-nAChR responses will be prevented not only by a nicotinic antagonist, but also by compounds blocking the indirectly activated glutamate receptors. This accounts for the apparent anticholinergic activity of some glutamate antagonists, including the endogenous antagonist kynurenic acid. The activation of presynaptic nAChRs is by the ambient levels of ACh released from pre-terminal synapses, varicosities and glial cells, acting as a 'volume neurotransmitter' on synaptic and extrasynaptic sites. In addition, ACh and glutamate are released as CNS co-transmitters, including 'cholinergic' synapses onto spinal Renshaw cells. It is concluded that ACh should be viewed primarily as a modulator of glutamatergic neurotransmission by regulating the release of glutamate presynaptically, and the location, subunit composition, subtype balance and sensitivity of glutamate receptors, and not primarily as a classical fast neurotransmitter. These conclusions and caveats should aid clarification of the sites of action of glutamate and nicotinic receptor ligands in the search for new centrally-acting drugs.
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Affiliation(s)
- Trevor W Stone
- The Kennedy Institute of Rheumatology, University of Oxford, Oxford OX3 7FY, UK; Institute of Neuroscience, University of Glasgow, G12 8QQ, UK.
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22
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Liu D, de Souza JV, Ahmad A, Bronowska AK. Structure, Dynamics, and Ligand Recognition of Human-Specific CHRFAM7A (Dupα7) Nicotinic Receptor Linked to Neuropsychiatric Disorders. Int J Mol Sci 2021; 22:5466. [PMID: 34067314 PMCID: PMC8196834 DOI: 10.3390/ijms22115466] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Revised: 05/16/2021] [Accepted: 05/20/2021] [Indexed: 11/16/2022] Open
Abstract
Cholinergic α7 nicotinic receptors encoded by the CHRNA7 gene are ligand-gated ion channels directly related to memory and immunomodulation. Exons 5-7 in CHRNA7 can be duplicated and fused to exons A-E of FAR7a, resulting in a hybrid gene known as CHRFAM7A, unique to humans. Its product, denoted herein as Dupα7, is a truncated subunit where the N-terminal 146 residues of the ligand binding domain of the α7 receptor have been replaced by 27 residues from FAM7. Dupα7 negatively affects the functioning of α7 receptors associated with neurological disorders, including Alzheimer's diseases and schizophrenia. However, the stoichiometry for the α7 nicotinic receptor containing dupα7 monomers remains unknown. In this work, we developed computational models of all possible combinations of wild-type α7 and dupα7 pentamers and evaluated their stability via atomistic molecular dynamics and coarse-grain simulations. We assessed the effect of dupα7 subunits on the Ca2+ conductance using free energy calculations. We showed that receptors comprising of four or more dupα7 subunits are not stable enough to constitute a functional ion channel. We also showed that models with dupα7/α7 interfaces are more stable and are less detrimental for the ion conductance in comparison to dupα7/dupα7 interfaces. Based on these models, we used protein-protein docking to evaluate how such interfaces would interact with an antagonist, α-bungarotoxin, and amyloid Aβ42. Our findings show that the optimal stoichiometry of dupα7/α7 functional pentamers should be no more than three dupα7 monomers, in favour of a dupα7/α7 interface in comparison to a homodimer dupα7/dupα7 interface. We also showed that receptors bearing dupα7 subunits are less sensitive to Aβ42 effects, which may shed light on the translational gap reported for strategies focused on nicotinic receptors in 'Alzheimer's disease research.
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Affiliation(s)
- Danlin Liu
- Chemistry—School of Natural and Environmental Sciences, Newcastle University, Newcastle NE1 7RU, UK; (D.L.); (J.V.d.S.); (A.A.)
| | - João V. de Souza
- Chemistry—School of Natural and Environmental Sciences, Newcastle University, Newcastle NE1 7RU, UK; (D.L.); (J.V.d.S.); (A.A.)
| | - Ayaz Ahmad
- Chemistry—School of Natural and Environmental Sciences, Newcastle University, Newcastle NE1 7RU, UK; (D.L.); (J.V.d.S.); (A.A.)
| | - Agnieszka K. Bronowska
- Chemistry—School of Natural and Environmental Sciences, Newcastle University, Newcastle NE1 7RU, UK; (D.L.); (J.V.d.S.); (A.A.)
- Newcastle University Centre for Cancer, Newcastle University, Newcastle NE1 7RU, UK
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23
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Olson A, Zhang F, Cao H, Baranova A, Slavin M. In silico Gene Set and Pathway Enrichment Analyses Highlight Involvement of Ion Transport in Cholinergic Pathways in Autism: Rationale for Nutritional Intervention. Front Neurosci 2021; 15:648410. [PMID: 33958984 PMCID: PMC8093449 DOI: 10.3389/fnins.2021.648410] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Accepted: 03/22/2021] [Indexed: 12/12/2022] Open
Abstract
Food is the primary human source of choline, an essential precursor to the neurotransmitter acetylcholine, which has a central role in signaling pathways that govern sensorimotor functions. Most Americans do not consume their recommended amount of dietary choline, and populations with neurodevelopmental conditions like autism spectrum disorder (ASD) may be particularly vulnerable to consequences of choline deficiency. This study aimed to identify a relationship between ASD and cholinergic signaling through gene set enrichment analysis and interrogation of existing database evidence to produce a systems biology model. In gene set enrichment analysis, two gene ontologies were identified as overlapping for autism-related and for cholinergic pathways-related functions, both involving ion transport regulation. Subsequent modeling of ion transport intensive cholinergic signaling pathways highlighted the importance of two genes with autism-associated variants: GABBR1, which codes for the gamma aminobutyric acid receptor (GABAB 1), and KCNN2, which codes for calcium-activated, potassium ion transporting SK2 channels responsible for membrane repolarization after cholinergic binding/signal transmission events. Cholinergic signal transmission pathways related to these proteins were examined in the Pathway Studio environment. The ion transport ontological associations indicated feasibility of a dietary choline support as a low-risk therapeutic intervention capable of modulating cholinergic sensory signaling in autism. Further research at the intersection of dietary status and sensory function in autism is warranted.
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Affiliation(s)
- Audrey Olson
- Department of Nutrition and Food Studies, College of Health and Human Services, George Mason University, Fairfax, VA, United States
- School of Systems Biology, College of Science, George Mason University, Manassas, VA, United States
| | - Fuquan Zhang
- Department of Psychiatry, Nanjing Medical University, Nanjing, China
| | - Hongbao Cao
- School of Systems Biology, College of Science, George Mason University, Manassas, VA, United States
- Department of Psychiatry, Shanxi Medical University, Taiyuan, China
| | - Ancha Baranova
- School of Systems Biology, College of Science, George Mason University, Manassas, VA, United States
- Research Centre for Medical Genetics, Moscow, Russia
| | - Margaret Slavin
- Department of Nutrition and Food Studies, College of Health and Human Services, George Mason University, Fairfax, VA, United States
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24
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Moglie MJ, Marcovich I, Corradi J, Carpaneto Freixas AE, Gallino S, Plazas PV, Bouzat C, Lipovsek M, Elgoyhen AB. Loss of Choline Agonism in the Inner Ear Hair Cell Nicotinic Acetylcholine Receptor Linked to the α10 Subunit. Front Mol Neurosci 2021; 14:639720. [PMID: 33613194 PMCID: PMC7892445 DOI: 10.3389/fnmol.2021.639720] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Accepted: 01/11/2021] [Indexed: 11/13/2022] Open
Abstract
The α9α10 nicotinic acetylcholine receptor (nAChR) plays a fundamental role in inner ear physiology. It mediates synaptic transmission between efferent olivocochlear fibers that descend from the brainstem and hair cells of the auditory sensory epithelium. The α9 and α10 subunits have undergone a distinct evolutionary history within the family of nAChRs. Predominantly in mammalian vertebrates, the α9α10 receptor has accumulated changes at the protein level that may ultimately relate to the evolutionary history of the mammalian hearing organ. In the present work, we investigated the responses of α9α10 nAChRs to choline, the metabolite of acetylcholine degradation at the synaptic cleft. Whereas choline is a full agonist of chicken α9α10 receptors it is a partial agonist of the rat receptor. Making use of the expression of α9α10 heterologous receptors, encompassing wild-type, heteromeric, homomeric, mutant, chimeric, and hybrid receptors, and in silico molecular docking, we establish that the mammalian (rat) α10 nAChR subunit underscores the reduced efficacy of choline. Moreover, we show that whereas the complementary face of the α10 subunit does not play an important role in the activation of the receptor by ACh, it is strictly required for choline responses. Thus, we propose that the evolutionary changes acquired in the mammalian α9α10 nAChR resulted in the loss of choline acting as a full agonist at the efferent synapse, without affecting the triggering of ACh responses. This may have accompanied the fine-tuning of hair cell post-synaptic responses to the high-frequency activity of efferent medial olivocochlear fibers that modulate the cochlear amplifier.
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Affiliation(s)
- Marcelo J. Moglie
- Instituto de Investigaciones en Ingeniería Genética y Biología Molecular “Dr. Héctor N. Torres” (INGEBI), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
| | - Irina Marcovich
- Instituto de Investigaciones en Ingeniería Genética y Biología Molecular “Dr. Héctor N. Torres” (INGEBI), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
| | - Jeremías Corradi
- Departamento de Biología, Bioquímica y Farmacia, Instituto de Investigaciones Bioquímicas de Bahía Blanca (INIBIBB), Universidad Nacional del Sur y Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina
| | - Agustín E. Carpaneto Freixas
- Instituto de Investigaciones en Ingeniería Genética y Biología Molecular “Dr. Héctor N. Torres” (INGEBI), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
| | - Sofía Gallino
- Instituto de Investigaciones en Ingeniería Genética y Biología Molecular “Dr. Héctor N. Torres” (INGEBI), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
| | - Paola V. Plazas
- Instituto de Farmacología, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Cecilia Bouzat
- Departamento de Biología, Bioquímica y Farmacia, Instituto de Investigaciones Bioquímicas de Bahía Blanca (INIBIBB), Universidad Nacional del Sur y Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina
| | - Marcela Lipovsek
- Instituto de Investigaciones en Ingeniería Genética y Biología Molecular “Dr. Héctor N. Torres” (INGEBI), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
- Centre for Developmental Neurobiology, King’s College London, Institute of Psychiatry, Psychology, and Neuroscience, Guy’s Campus, London, United Kingdom
| | - Ana Belén Elgoyhen
- Instituto de Investigaciones en Ingeniería Genética y Biología Molecular “Dr. Héctor N. Torres” (INGEBI), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
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Xie H, Yepuri N, Meng Q, Dhawan R, Leech CA, Chepurny OG, Holz GG, Cooney RN. Therapeutic potential of α7 nicotinic acetylcholine receptor agonists to combat obesity, diabetes, and inflammation. Rev Endocr Metab Disord 2020; 21:431-447. [PMID: 32851581 PMCID: PMC7572644 DOI: 10.1007/s11154-020-09584-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 08/21/2020] [Indexed: 12/12/2022]
Abstract
The cholinergic anti-inflammatory reflex (CAIR) represents an important homeostatic regulatory mechanism for sensing and controlling the body's response to inflammatory stimuli. Vagovagal reflexes are an integral component of CAIR whose anti-inflammatory effects are mediated by acetylcholine (ACh) acting at α7 nicotinic acetylcholine receptors (α7nAChR) located on cells of the immune system. Recently, it is appreciated that CAIR and α7nAChR also participate in the control of metabolic homeostasis. This has led to the understanding that defective vagovagal reflex circuitry underlying CAIR might explain the coexistence of obesity, diabetes, and inflammation in the metabolic syndrome. Thus, there is renewed interest in the α7nAChR that mediates CAIR, particularly from the standpoint of therapeutics. Of special note is the recent finding that α7nAChR agonist GTS-21 acts at L-cells of the distal intestine to stimulate the release of two glucoregulatory and anorexigenic hormones: glucagon-like peptide-1 (GLP-1) and peptide YY (PYY). Furthermore, α7nAChR agonist PNU 282987 exerts trophic factor-like actions to support pancreatic β-cell survival under conditions of stress resembling diabetes. This review provides an overview of α7nAChR function as it pertains to CAIR, vagovagal reflexes, and metabolic homeostasis. We also consider the possible usefulness of α7nAChR agonists for treatment of obesity, diabetes, and inflammation.
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Affiliation(s)
- Han Xie
- Departments of Surgery, State University of New York (SUNY), Upstate Medical University, 750 E Adams St., Suite 8141, Syracuse, NY, 13210, USA
| | - Natesh Yepuri
- Departments of Surgery, State University of New York (SUNY), Upstate Medical University, 750 E Adams St., Suite 8141, Syracuse, NY, 13210, USA
| | - Qinghe Meng
- Departments of Surgery, State University of New York (SUNY), Upstate Medical University, 750 E Adams St., Suite 8141, Syracuse, NY, 13210, USA
| | - Ravi Dhawan
- Departments of Surgery, State University of New York (SUNY), Upstate Medical University, 750 E Adams St., Suite 8141, Syracuse, NY, 13210, USA
| | - Colin A Leech
- Departments of Surgery, State University of New York (SUNY), Upstate Medical University, 750 E Adams St., Suite 8141, Syracuse, NY, 13210, USA
| | - Oleg G Chepurny
- Departments of Medicine, State University of New York (SUNY), Upstate Medical University, Syracuse, NY, USA
| | - George G Holz
- Departments of Medicine, State University of New York (SUNY), Upstate Medical University, Syracuse, NY, USA
| | - Robert N Cooney
- Departments of Surgery, State University of New York (SUNY), Upstate Medical University, 750 E Adams St., Suite 8141, Syracuse, NY, 13210, USA.
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Implications of Oligomeric Amyloid-Beta (oAβ 42) Signaling through α7β2-Nicotinic Acetylcholine Receptors (nAChRs) on Basal Forebrain Cholinergic Neuronal Intrinsic Excitability and Cognitive Decline. J Neurosci 2020; 41:555-575. [PMID: 33239400 DOI: 10.1523/jneurosci.0876-20.2020] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Revised: 11/03/2020] [Accepted: 11/15/2020] [Indexed: 01/08/2023] Open
Abstract
Neuronal and network-level hyperexcitability is commonly associated with increased levels of amyloid-β (Aβ) and contribute to cognitive deficits associated with Alzheimer's disease (AD). However, the mechanistic complexity underlying the selective loss of basal forebrain cholinergic neurons (BFCNs), a well-recognized characteristic of AD, remains poorly understood. In this study, we tested the hypothesis that the oligomeric form of amyloid-β (oAβ42), interacting with α7-containing nicotinic acetylcholine receptor (nAChR) subtypes, leads to subnucleus-specific alterations in BFCN excitability and impaired cognition. We used single-channel electrophysiology to show that oAβ42 activates both homomeric α7- and heteromeric α7β2-nAChR subtypes while preferentially enhancing α7β2-nAChR open-dwell times. Organotypic slice cultures were prepared from male and female ChAT-EGFP mice, and current-clamp recordings obtained from BFCNs chronically exposed to pathophysiologically relevant level of oAβ42 showed enhanced neuronal intrinsic excitability and action potential firing rates. These resulted from a reduction in action potential afterhyperpolarization and alterations in the maximal rates of voltage change during spike depolarization and repolarization. These effects were observed in BFCNs from the medial septum diagonal band and horizontal diagonal band, but not the nucleus basalis. Last, aged male and female APP/PS1 transgenic mice, genetically null for the β2 nAChR subunit gene, showed improved spatial reference memory compared with APP/PS1 aged-matched littermates. Combined, these data provide a molecular mechanism supporting a role for α7β2-nAChR in mediating the effects of oAβ42 on excitability of specific populations of cholinergic neurons and provide a framework for understanding the role of α7β2-nAChR in oAβ42-induced cognitive decline.
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Rodriguez Araujo N, Fabiani C, Mazzarini Dimarco A, Bouzat C, Corradi J. Orthosteric and Allosteric Activation of Human 5-HT 3A Receptors. Biophys J 2020; 119:1670-1682. [PMID: 32946769 DOI: 10.1016/j.bpj.2020.08.029] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Revised: 07/18/2020] [Accepted: 08/24/2020] [Indexed: 12/24/2022] Open
Abstract
The serotonin type 3 receptor (5-HT3) is a ligand-gated ion channel that converts the binding of the neurotransmitter serotonin (5-HT) into a transient cation current that mediates fast excitatory responses in peripheral and central nervous systems. Information regarding the activation and modulation of the human 5-HT3 type A receptor has been based only on macroscopic current measurements because of its low ion conductance. By constructing a high-conductance human 5-HT3A receptor, we here revealed mechanistic information regarding the orthosteric activation by 5-HT and by the partial agonist tryptamine, and the allosteric activation by the terpenoids, carvacrol, and thymol. Terpenoids potentiated macroscopic currents elicited by the orthosteric agonist and directly elicited currents with slow-rising phases and submaximal amplitudes. At the single-channel level, activation by orthosteric and allosteric agonists appeared as openings in quick succession (bursts) that showed no ligand concentration dependence. Bursts were grouped into long-duration clusters in the presence of 5-HT and even longer in the presence of terpenoids, whereas they remained isolated in the presence of tryptamine. Kinetic analysis revealed that allosteric and orthosteric activation mechanisms can be described by the same scheme that includes transitions of the agonist-bound receptor to closed intermediate states before opening (priming). Reduced priming explained the partial agonism of tryptamine; however, equilibrium constants for gating and priming were similar for 5-HT and terpenoid activation. Thus, our kinetic analysis revealed that terpenoids are efficacious agonists for 5-HT3A receptors. These findings not only extend our knowledge about the human 5-HT3A molecular function but also provide novel insights into the mechanisms of action of allosteric ligands, which are of increasing interest as therapeutic drugs in all the superfamily.
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Affiliation(s)
- Noelia Rodriguez Araujo
- Instituto de Investigaciones Bioquímicas de Bahía Blanca (INIBIBB), Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur (UNS)-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Bahía Blanca, Argentina
| | - Camila Fabiani
- Instituto de Investigaciones Bioquímicas de Bahía Blanca (INIBIBB), Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur (UNS)-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Bahía Blanca, Argentina
| | - Albano Mazzarini Dimarco
- Instituto de Investigaciones Bioquímicas de Bahía Blanca (INIBIBB), Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur (UNS)-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Bahía Blanca, Argentina
| | - Cecilia Bouzat
- Instituto de Investigaciones Bioquímicas de Bahía Blanca (INIBIBB), Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur (UNS)-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Bahía Blanca, Argentina.
| | - Jeremías Corradi
- Instituto de Investigaciones Bioquímicas de Bahía Blanca (INIBIBB), Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur (UNS)-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Bahía Blanca, Argentina.
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28
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Gulsevin A, Meiler J, Horenstein NA. A Computational Analysis of the Factors Governing the Dynamics of α7 nAChR and Its Homologs. Biophys J 2020; 119:1656-1669. [PMID: 33010233 PMCID: PMC7642335 DOI: 10.1016/j.bpj.2020.09.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Revised: 09/10/2020] [Accepted: 09/10/2020] [Indexed: 12/18/2022] Open
Abstract
The α7 nicotinic acetylcholine receptor is a homopentameric ion channel from the Cys-loop receptor superfamily targeted for psychiatric indications and inflammatory pain. Molecular dynamics studies of the receptor have focused on residue mobility and global conformational changes to address receptor function. However, a comparative analysis of α7 with its homologs that cannot trigger channel opening has not been made so far. To identify the residues involved in α7 activation, we ran triplicate 500-ns molecular dynamics simulations with an α7 extracellular domain homology model and two acetylcholine-binding protein homologs. We tested the effect of ligand binding and amino acid sequence on the structure and dynamics of the three proteins. We found that mobile regions identified based on root mean-square deviation and root mean-square fluctuation values are not always consistent among the individual α7 extracellular domain simulations. Comparison of the replica-average properties of the three proteins based on dynamic cross-correlation maps showed that ligand binding affects the coupling between the C-loop and the Cys-loop, vestibular loop, and β1-β2 loops. In addition, the main-immunogenic-region-like domain of α7 went through correlated motions with multiple domains of the receptor. These correlated motions were absent or diminished in α7 homologs, suggesting a unique role in α7 activation.
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Affiliation(s)
- Alican Gulsevin
- Department of Chemistry, Biochemistry Division, University of Florida, Gainesville, Florida; Department of Chemistry, Vanderbilt University, Nashville, Tennessee.
| | - Jens Meiler
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee; Leipzig University Medical School, Institute for Drug Discovery, Leipzig, Germany
| | - Nicole A Horenstein
- Department of Chemistry, Biochemistry Division, University of Florida, Gainesville, Florida
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Wittenberg RE, Wolfman SL, De Biasi M, Dani JA. Nicotinic acetylcholine receptors and nicotine addiction: A brief introduction. Neuropharmacology 2020; 177:108256. [PMID: 32738308 PMCID: PMC7554201 DOI: 10.1016/j.neuropharm.2020.108256] [Citation(s) in RCA: 55] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Revised: 07/22/2020] [Accepted: 07/26/2020] [Indexed: 12/13/2022]
Abstract
Nicotine is a highly addictive drug found in tobacco that drives its continued use despite the harmful consequences. The initiation of nicotine abuse involves the mesolimbic dopamine system, which contributes to the rewarding sensory stimuli and associative learning processes in the beginning stages of addiction. Nicotine binds to neuronal nicotinic acetylcholine receptors (nAChRs), which come in a diverse collection of subtypes. The nAChRs that contain the α4 and β2 subunits, often in combination with the α6 subunit, are particularly important for nicotine's ability to increase midbrain dopamine neuron firing rates and phasic burst firing. Chronic nicotine exposure results in numerous neuroadaptations, including the upregulation of particular nAChR subtypes associated with long-term desensitization of the receptors. When nicotine is no longer present, for example during attempts to quit smoking, a withdrawal syndrome develops. The expression of physical withdrawal symptoms depends mainly on the α2, α3, α5, and β4 nicotinic subunits in the epithalamic habenular complex and its target regions. Thus, nicotine affects diverse neural systems and an array of nAChR subtypes to mediate the overall addiction process. This article is part of the special issue on 'Contemporary Advances in Nicotine Neuropharmacology'.
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Affiliation(s)
- Ruthie E Wittenberg
- Departments of Neuroscience, Mahoney Institute for Neurosciences, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Shannon L Wolfman
- Departments of Neuroscience, Mahoney Institute for Neurosciences, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Mariella De Biasi
- Departments of Neuroscience, Mahoney Institute for Neurosciences, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA; Department of Psychiatry, Mahoney Institute for Neurosciences, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - John A Dani
- Departments of Neuroscience, Mahoney Institute for Neurosciences, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA.
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Short B. How calcium helps α7 nicotinic acetylcholine receptors fulfill their potential. J Gen Physiol 2020; 152:152038. [PMID: 32820805 PMCID: PMC7478870 DOI: 10.1085/jgp.202012740] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
Study reveals that, at low acetylcholine concentrations, calcium enhances channel opening by binding to a novel motif near the ligand binding site.
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31
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Nielsen BE, Stabile S, Vitale C, Bouzat C. Design, Synthesis, and Functional Evaluation of a Novel Series of Phosphonate-Functionalized 1,2,3-Triazoles as Positive Allosteric Modulators of α7 Nicotinic Acetylcholine Receptors. ACS Chem Neurosci 2020; 11:2688-2704. [PMID: 32786318 DOI: 10.1021/acschemneuro.0c00348] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The α7 nicotinic acetylcholine receptor is a pentameric ligand-gated ion channel widely distributed in the central nervous system, mainly in the hippocampus and cortex. The enhancement of its activity by positive allosteric modulators (PAMs) is a promising therapeutic strategy for cognitive deficits and neurodegenerative disorders. With the aim of developing novel scaffolds with PAM activity, we designed and synthesized a series of phosphonate-functionalized 1,4-disubstituted 1,2,3-triazoles using supported copper nanoparticles as the cycloaddition reaction catalyst and evaluated their activity on α7 receptors by single-channel and whole-cell recordings. We identified several triazole derivatives that displayed PAM activity, with the compound functionalized with the methyl phosphonate group being the most efficacious one. At the macroscopic level, α7 potentiation was evidenced as an increase of the maximal currents elicited by acetylcholine with minimal effects on desensitization, recapitulating the actions of type I PAMs. At the single-channel level, the active compounds did not affect channel amplitude but significantly increased the duration of channel openings and activation episodes. By using chimeric and mutant α7 receptors, we demonstrated that the new α7 PAMs share transmembrane structural determinants of potentiation with other chemically nonrelated PAMs. To gain further insight into the chemical basis of potentiation, we applied structure-activity relationship strategies involving modification of the chain length, inversion of substituent positions in the triazole ring, and changes in the aromatic nucleus. Our findings revealed that the phosphonate-functionalized 1,4-disubstituted 1,2,3-triazole is a novel pharmacophore for the development of therapeutic agents for neurological and neurodegenerative disorders associated with cholinergic dysfunction.
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Affiliation(s)
- Beatriz Elizabeth Nielsen
- Departamento de Biologı́a, Bioquı́mica y Farmacia, Instituto de Investigaciones Bioquı́micas de Bahı́a Blanca (INIBIBB), Departamento de Biologı́a, Bioquı́mica y Farmacia, Universidad Nacional del Sur-Consejo Nacional de Investigaciones Cientı́ficas y Técnicas (CONICET), Bahía Blanca 8000, Buenos Aires, Argentina
| | - Santiago Stabile
- Instituto de Quı́mica del Sur (INQUISUR), Departamento de Quı́mica, Universidad Nacional del Sur-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Bahía Blanca 8000, Buenos Aires, Argentina
| | - Cristian Vitale
- Instituto de Quı́mica del Sur (INQUISUR), Departamento de Quı́mica, Universidad Nacional del Sur-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Bahía Blanca 8000, Buenos Aires, Argentina
| | - Cecilia Bouzat
- Departamento de Biologı́a, Bioquı́mica y Farmacia, Instituto de Investigaciones Bioquı́micas de Bahı́a Blanca (INIBIBB), Departamento de Biologı́a, Bioquı́mica y Farmacia, Universidad Nacional del Sur-Consejo Nacional de Investigaciones Cientı́ficas y Técnicas (CONICET), Bahía Blanca 8000, Buenos Aires, Argentina
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32
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Papke RL, Lindstrom JM. Nicotinic acetylcholine receptors: Conventional and unconventional ligands and signaling. Neuropharmacology 2020; 168:108021. [PMID: 32146229 PMCID: PMC7610230 DOI: 10.1016/j.neuropharm.2020.108021] [Citation(s) in RCA: 66] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2019] [Revised: 02/05/2020] [Accepted: 02/25/2020] [Indexed: 12/28/2022]
Abstract
Postsynaptic nAChRs in the peripheral nervous system are critical for neuromuscular and autonomic neurotransmission. Pre- and peri-synaptic nAChRs in the brain modulate neurotransmission and are responsible for the addictive effects of nicotine. Subtypes of nAChRs in lymphocytes and non-synaptic locations may modulate inflammation and other cellular functions. All AChRs that function as ligand-gated ion channels are formed from five homologous subunits organized to form a central cation channel whose opening is regulated by ACh bound at extracellular subunit interfaces. nAChR subtype subunit composition can range from α7 homomers to α4β2α6β2β3 heteromers. Subtypes differ in affinities for ACh and other agonists like nicotine and in efficiencies with which their channels are opened and desensitized. Subtypes also differ in affinities for antagonists and for positive and negative allosteric modulators. Some agonists are "silent" with respect to channel opening, and AChRs may be able to signal metabotropic pathways by releasing G-proteins independent of channel opening. Electrophysiological studies that can resolve single-channel openings and molecular genetic approaches have allowed characterization of the structures of ligand binding sites, the cation channel, and the linkages between them, as well as the organization of AChR subunits and their contributions to function. Crystallography and cryo-electron-microscopy are providing increasing insights into the structures and functions of AChRs. However, much remains to be learned about both AChR structure and function, the in vivo functional roles of some AChR subtypes, and the development of better pharmacological tools directed at AChRs to treat addiction, pain, inflammation, and other medically important issues. This article is part of the special issue on 'Contemporary Advances in Nicotine Neuropharmacology'.
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Affiliation(s)
- Roger L Papke
- Department of Pharmacology and Therapeutics, University of Florida, P.O. Box 100267, Gainesville, FL, 32610-0267, USA.
| | - Jon M Lindstrom
- Department of Neuroscience, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA
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Tarasenko O, Voytenko S, Koval L, Lykhmus O, Kalashnyk O, Skok M. Unusual properties of α7 nicotinic acetylcholine receptor ion channels in B lymphocyte-derived SP-2/0 cells. Int Immunopharmacol 2020; 82:106373. [PMID: 32163855 DOI: 10.1016/j.intimp.2020.106373] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Revised: 02/25/2020] [Accepted: 03/02/2020] [Indexed: 12/30/2022]
Abstract
This study demonstrates the presence of α7 nicotinic acetylcholine receptors (nAChR) in B lymphocyte-derived SP-2/0 cells by means of flow cytometry and immunocytochemistry. According to lectin and sandwich ELISA, the α7 subunits expressed in SP-2/0 cells are more glycosylated compared to those expressed in the brain or normal B lymphocytes and are combined with β2 subunits. At zero and negative pipette potentials, either acetylcholine or α7-specific agonist PNU282987 stimulated the ion channel activity in SP-2/0 cells revealed by single channel patch-clamp recordings. The conductivity was within the range of 19 to 39 pS and reversal potential was between -17 mV and +28 mV, the currents were potentiated by α7-specific positive allosteric modulator PNU120596 and were partially blocked by α7-specific antagonist methyllicaconitine (MLA). However, they were oriented downwards suggesting that the channels mediated the cation outflux rather than influx. As shown by Ca2+ imaging studies, PNU282987 did not stimulate immediate Ca2+ influx into SP-2/0 cells. Instead, Ca2+ influx through Ca-release-activated channels (CRACs) was observed within minutes after either PNU282987 or MLA application. It is concluded that SP-2/0 express α7β2 nAChRs, which mediate the cation outflux under negative pipette potentials applied, possibly, due to depolarized membrane or negative surface charge formed by carbohydrate residues. In addition, α7β2 nAChRs may influence CRACs in ion-independent way.
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Affiliation(s)
| | - Sergiy Voytenko
- Bogomoletz Institute of Physiology, 4, Bogomoletz Str, 01024 Kyiv, Ukraine
| | - Lyudmyla Koval
- Palladin Institute of Biochemistry, 9, Leontovycha Str., 01030 Kyiv, Ukraine.
| | - Olena Lykhmus
- Palladin Institute of Biochemistry, 9, Leontovycha Str., 01030 Kyiv, Ukraine
| | - Olena Kalashnyk
- Palladin Institute of Biochemistry, 9, Leontovycha Str., 01030 Kyiv, Ukraine
| | - Maryna Skok
- Palladin Institute of Biochemistry, 9, Leontovycha Str., 01030 Kyiv, Ukraine.
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Santoro A, Tomino C, Prinzi G, Lamonaca P, Cardaci V, Fini M, Russo P. Tobacco Smoking: Risk to Develop Addiction, Chronic Obstructive Pulmonary Disease, and Lung Cancer. Recent Pat Anticancer Drug Discov 2019; 14:39-52. [PMID: 30605063 DOI: 10.2174/1574892814666190102122848] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2018] [Revised: 12/11/2018] [Accepted: 12/27/2018] [Indexed: 12/24/2022]
Abstract
BACKGROUND The morbidity and mortality associated with tobacco smoking is well established. Nicotine is the addictive component of tobacco. Nicotine, through the non-neuronal α7nicotinic receptor, induces cell proliferation, neo-angiogenesis, epithelial to mesenchymal transition, and inhibits drug-induced apoptosis. OBJECTIVE To understand the genetic, molecular and cellular biology of addiction, chronic obstructive pulmonary disease and lung cancer. METHODS The search for papers to be included in the review was performed during the months of July- September 2018 in the following databases: PubMed (http://www.ncbi.nlm.nih.gov), Scopus (http://www.scopus.com), EMBASE (http://www.elsevier.com/online-tools/embase), and ISI Web of Knowledge (http://apps.webofknowledge.com/). The following searching terms: "nicotine", "nicotinic receptor", and "addiction" or "COPD" or "lung cancer" were used. Patents were retrieved in clinicaltrials.gov (https://clinicaltrials.gov/). All papers written in English were evaluated. The reference list of retrieved articles was also reviewed to identify other eligible studies that were not indexed by the above-mentioned databases. New experimental data on the ability of nicotine to promote transformation of human bronchial epithelial cells, exposed for one hour to Benzo[a]pyrene-7,8-diol-9-10-epoxide, are reported. RESULTS Nicotinic receptors variants and nicotinic receptors upregulation are involved in addiction, chronic obstructive pulmonary disease and/or lung cancer. Nicotine through α7nicotinic receptor upregulation induces complete bronchial epithelial cells transformation. CONCLUSION Genetic studies highlight the involvement of nicotinic receptors variants in addiction, chronic obstructive pulmonary disease and/or lung cancer. A future important step will be to translate these genetic findings to clinical practice. Interventions able to help smoking cessation in nicotine dependence subjects, under patent, are reported.
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Affiliation(s)
- Alessia Santoro
- Clinical and Molecular Epidemiology, IRCSS San Raffaele Pisana, Via di Valcannuta 247, I-00166 Rome, Italy
| | - Carlo Tomino
- Scientific Direction, IRCSS San Raffaele Pisana, Via di Valcannuta 247, I-00166 Rome, Italy
| | - Giulia Prinzi
- Clinical and Molecular Epidemiology, IRCSS San Raffaele Pisana, Via di Valcannuta 247, I-00166 Rome, Italy
| | - Palma Lamonaca
- Clinical and Molecular Epidemiology, IRCSS San Raffaele Pisana, Via di Valcannuta 247, I-00166 Rome, Italy
| | - Vittorio Cardaci
- Pulmonary Rehabilitation, IRCCS San Raffaele Pisana, Via della Pisana, 235, I-00163 Rome, Italy
| | - Massimo Fini
- Scientific Direction, IRCSS San Raffaele Pisana, Via di Valcannuta 247, I-00166 Rome, Italy
| | - Patrizia Russo
- Clinical and Molecular Epidemiology, IRCSS San Raffaele Pisana, Via di Valcannuta 247, I-00166 Rome, Italy
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Nielsen BE, Bermudez I, Bouzat C. Flavonoids as positive allosteric modulators of α7 nicotinic receptors. Neuropharmacology 2019; 160:107794. [PMID: 31560909 DOI: 10.1016/j.neuropharm.2019.107794] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Revised: 08/09/2019] [Accepted: 09/23/2019] [Indexed: 12/11/2022]
Abstract
The use of positive allosteric modulators (PAM) of α7 nicotinic receptors is a promising therapy for neurodegenerative, inflammatory and cognitive disorders. Flavonoids are polyphenolic compounds showing neuroprotective, anti-inflammatory and pro-cognitive actions. Besides their well-known antioxidant activity, flavonoids trigger intracellular pathways and interact with receptors, including α7. To reveal how the beneficial actions of flavonoids are linked to α7 function, we evaluated the effects of three representative flavonoids -genistein, quercetin and the neoflavonoid 5,7-dihydroxy-4-phenylcoumarin- on whole-cell and single-channel currents. All flavonoids increase the maximal currents elicited by acetylcholine with minimal effects on desensitization and do not reactivate desensitized receptors, a behaviour consistent with type I PAMs. At the single-channel level, they increase the duration of the open state and produce activation in long-duration episodes with a rank order of efficacy of genistein > quercetin ≥ neoflavonoid. By using mutant and chimeric α7 receptors, we demonstrated that flavonoids share transmembrane structural determinants with other PAMs. The α7-PAM activity of flavonoids results in decreased cell levels of reactive oxygen species. Thus, allosteric potentiation of α7 may be an additional mechanism underlying neuroprotective actions of flavonoids, which may be used as scaffolds for designing new therapeutic agents.
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Affiliation(s)
- Beatriz Elizabeth Nielsen
- Instituto de Investigaciones Bioquímicas de Bahía Blanca, Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Bahía Blanca 8000, Argentina
| | - Isabel Bermudez
- Department of Medical and Biological Sciences, Oxford Brookes University, Oxford, OX3 0BP, United Kingdom
| | - Cecilia Bouzat
- Instituto de Investigaciones Bioquímicas de Bahía Blanca, Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Bahía Blanca 8000, Argentina.
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36
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Lasala M, Fabiani C, Corradi J, Antollini S, Bouzat C. Molecular Modulation of Human α7 Nicotinic Receptor by Amyloid-β Peptides. Front Cell Neurosci 2019; 13:37. [PMID: 30800059 PMCID: PMC6376857 DOI: 10.3389/fncel.2019.00037] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Accepted: 01/23/2019] [Indexed: 12/21/2022] Open
Abstract
Amyloid β peptide (Aβ) is a key player in the development of Alzheimer's disease (AD). It is the primary component of senile plaques in AD patients and is also found in soluble forms. Cholinergic activity mediated by α7 nicotinic receptors has been shown to be affected by Aβ soluble forms. To shed light into the molecular mechanism of this effect, we explored the direct actions of oligomeric Aβ1-40 and Aβ1-42 on human α7 by fluorescence spectroscopy and single-channel recordings. Fluorescence measurements using the conformational sensitive probe crystal violet (CrV) revealed that in the presence of Aβ α7 undergoes concentration-dependent conformational changes. Exposure of α7 to 100 pM Aβ changes CrV KD towards that of the desensitized state. However, α7 is still reactive to high carbamylcholine (Carb) concentrations. These observations are compatible with the induction of active/desensitized states as well as of a novel conformational state in the presence of both Aβ and Carb. At 100 nM Aβ, α7 adopts a resting-state-like structure which does not respond to Carb, suggesting stabilization of α7 in a blocked state. In real time, we found that Aβ is capable of eliciting α7 channel activity either in the absence or presence of the positive allosteric modulator (PAM) PNU-120596. Activation by Aβ is favored at picomolar or low nanomolar concentrations and is not detected at micromolar concentrations. At high Aβ concentrations, the mean duration of activation episodes elicited by ACh in the presence of PNU-120596 is significantly reduced, an effect compatible with slow open-channel block. We conclude that Aβ directly affects α7 function by acting as an agonist and a negative modulator. Whereas the capability of low concentrations of Aβ to activate α7 could be beneficial, the reduced α7 activity in the presence of higher Aβ concentrations or its long exposure may contribute to the cholinergic signaling deficit and may be involved in the initiation and development of AD.
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Affiliation(s)
- Matías Lasala
- Instituto de Investigaciones Bioquímicas de Bahía Blanca (INIBIBB), Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Bahía Blanca, Argentina
| | - Camila Fabiani
- Instituto de Investigaciones Bioquímicas de Bahía Blanca (INIBIBB), Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Bahía Blanca, Argentina
| | - Jeremías Corradi
- Instituto de Investigaciones Bioquímicas de Bahía Blanca (INIBIBB), Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Bahía Blanca, Argentina
| | - Silvia Antollini
- Instituto de Investigaciones Bioquímicas de Bahía Blanca (INIBIBB), Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Bahía Blanca, Argentina
| | - Cecilia Bouzat
- Instituto de Investigaciones Bioquímicas de Bahía Blanca (INIBIBB), Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Bahía Blanca, Argentina
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Ladefoged LK, Munro L, Pedersen AJ, Lummis SCR, Bang-Andersen B, Balle T, Schiøtt B, Kristensen AS. Modeling and Mutational Analysis of the Binding Mode for the Multimodal Antidepressant Drug Vortioxetine to the Human 5-HT3A Receptor. Mol Pharmacol 2018; 94:1421-1434. [DOI: 10.1124/mol.118.113530] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Accepted: 09/19/2018] [Indexed: 12/23/2022] Open
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Zoli M, Pucci S, Vilella A, Gotti C. Neuronal and Extraneuronal Nicotinic Acetylcholine Receptors. Curr Neuropharmacol 2018; 16:338-349. [PMID: 28901280 PMCID: PMC6018187 DOI: 10.2174/1570159x15666170912110450] [Citation(s) in RCA: 159] [Impact Index Per Article: 26.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2017] [Revised: 08/08/2017] [Accepted: 09/03/2017] [Indexed: 02/08/2023] Open
Abstract
Neuronal nicotinic acetylcholine receptors (nAChRs) belong to a super-family of Cys-loop ligand-gated ion chan-nels that respond to endogenous acetylcholine (ACh) or other cholinergic ligands. These receptors are also the targets of drugs such as nicotine (the main addictive agent delivered by cigarette smoke) and are involved in a variety of physiological and pathophysiological processes. Numerous studies have shown that the expression and/or function of nAChRs is com-promised in many neurological and psychiatric diseases. Furthermore, recent studies have shown that neuronal nAChRs are found in a large number of non-neuronal cell types in-cluding endothelial cells, glia, immune cells, lung epithelia and cancer cells where they regulate cell differentiation, prolifera-tion and inflammatory responses. The aim of this review is to describe the most recent findings concerning the structure and function of native nAChRs inside and outside the nervous system.
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Affiliation(s)
- Michele Zoli
- Department of Biomedical, Metabolic and Neural Sciences, Center for Neuroscience and Neurotechnology, University of Modena and Reggio Emilia, Modena, Italy
| | - Susanna Pucci
- CNR, Neuroscience Institute-Milano, Biometra University of Milan, Milan, Italy
| | - Antonietta Vilella
- Department of Biomedical, Metabolic and Neural Sciences, Center for Neuroscience and Neurotechnology, University of Modena and Reggio Emilia, Modena, Italy
| | - Cecilia Gotti
- CNR, Neuroscience Institute-Milano, Biometra University of Milan, Milan, Italy
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Richter K, Sagawe S, Hecker A, Küllmar M, Askevold I, Damm J, Heldmann S, Pöhlmann M, Ruhrmann S, Sander M, Schlüter KD, Wilker S, König IR, Kummer W, Padberg W, Hone AJ, McIntosh JM, Zakrzewicz AT, Koch C, Grau V. C-Reactive Protein Stimulates Nicotinic Acetylcholine Receptors to Control ATP-Mediated Monocytic Inflammasome Activation. Front Immunol 2018; 9:1604. [PMID: 30105015 PMCID: PMC6077200 DOI: 10.3389/fimmu.2018.01604] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Accepted: 06/27/2018] [Indexed: 12/20/2022] Open
Abstract
Blood levels of the acute phase reactant C-reactive protein (CRP) are frequently measured as a clinical marker for inflammation, but the biological functions of CRP are still controversial. CRP is a phosphocholine (PC)-binding pentraxin, mainly produced in the liver in response to elevated levels of interleukin-1β (IL-1β) and of the IL-1β-dependent cytokine IL-6. While both cytokines play important roles in host defense, excessive systemic IL-1β levels can cause life-threatening diseases such as trauma-associated systemic inflammation. We hypothesized that CRP acts as a negative feedback regulator of monocytic IL-1β maturation and secretion. Here, we demonstrate that CRP, in association with PC, efficiently reduces ATP-induced inflammasome activation and IL-1β release from human peripheral blood mononuclear leukocytes and monocytic U937 cells. Effective concentrations are in the range of marginally pathologic CRP levels (IC50 = 4.9 µg/ml). CRP elicits metabotropic functions at nicotinic acetylcholine (ACh) receptors (nAChRs) containing subunits α7, α9, and α10 and suppresses the function of ATP-sensitive P2X7 receptors in monocytic cells. Of note, CRP does not induce ion currents at conventional nAChRs, suggesting that CRP is a potent nicotinic agonist controlling innate immunity without entailing the risk of adverse effects in the nervous system. In a prospective study on multiple trauma patients, IL-1β plasma concentrations negatively correlated with preceding CRP levels, whereas inflammasome-independent cytokines IL-6, IL-18, and TNF-α positively correlated. In conclusion, PC-laden CRP is an unconventional nicotinic agonist that potently inhibits ATP-induced inflammasome activation and might protect against trauma-associated sterile inflammation.
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Affiliation(s)
- Katrin Richter
- Laboratory of Experimental Surgery, Department of General and Thoracic Surgery, Justus-Liebig-University Giessen, German Centre for Lung Research (DZL), Giessen, Germany
| | - Sabrina Sagawe
- Laboratory of Experimental Surgery, Department of General and Thoracic Surgery, Justus-Liebig-University Giessen, German Centre for Lung Research (DZL), Giessen, Germany
| | - Andreas Hecker
- Laboratory of Experimental Surgery, Department of General and Thoracic Surgery, Justus-Liebig-University Giessen, German Centre for Lung Research (DZL), Giessen, Germany
| | - Mira Küllmar
- Laboratory of Experimental Surgery, Department of General and Thoracic Surgery, Justus-Liebig-University Giessen, German Centre for Lung Research (DZL), Giessen, Germany
| | - Ingolf Askevold
- Laboratory of Experimental Surgery, Department of General and Thoracic Surgery, Justus-Liebig-University Giessen, German Centre for Lung Research (DZL), Giessen, Germany
| | - Jelena Damm
- Laboratory of Experimental Surgery, Department of General and Thoracic Surgery, Justus-Liebig-University Giessen, German Centre for Lung Research (DZL), Giessen, Germany
| | - Sarah Heldmann
- Laboratory of Experimental Surgery, Department of General and Thoracic Surgery, Justus-Liebig-University Giessen, German Centre for Lung Research (DZL), Giessen, Germany
| | - Michael Pöhlmann
- Department of Anesthesiology and Intensive Care Medicine, Justus-Liebig-University Giessen, Giessen, Germany
| | - Sophie Ruhrmann
- Department of Anesthesiology and Intensive Care Medicine, Justus-Liebig-University Giessen, Giessen, Germany
| | - Michael Sander
- Department of Anesthesiology and Intensive Care Medicine, Justus-Liebig-University Giessen, Giessen, Germany
| | | | - Sigrid Wilker
- Laboratory of Experimental Surgery, Department of General and Thoracic Surgery, Justus-Liebig-University Giessen, German Centre for Lung Research (DZL), Giessen, Germany
| | - Inke R. König
- Institute of Medical Biometry and Statistics, University of Luebeck, Luebeck, Germany
- Airway Research Center North (ARCN), German Center for Lung Research (DZL), Giessen, Germany
| | - Wolfgang Kummer
- Institute of Anatomy and Cell Biology, Justus-Liebig-University Giessen, German Centre for Lung Research, Giessen, Germany
| | - Winfried Padberg
- Laboratory of Experimental Surgery, Department of General and Thoracic Surgery, Justus-Liebig-University Giessen, German Centre for Lung Research (DZL), Giessen, Germany
| | - Arik J. Hone
- Department of Biology, University of Utah, Salt Lake City, UT, United States
| | - J. Michael McIntosh
- Department of Biology, University of Utah, Salt Lake City, UT, United States
- George E. Wahlen Veterans Affairs Medical Center, Salt Lake City, UT, United States
- Department of Psychiatry, University of Utah, Salt Lake City, UT, United States
| | - Anna Teresa Zakrzewicz
- Laboratory of Experimental Surgery, Department of General and Thoracic Surgery, Justus-Liebig-University Giessen, German Centre for Lung Research (DZL), Giessen, Germany
| | - Christian Koch
- Department of Anesthesiology and Intensive Care Medicine, Justus-Liebig-University Giessen, Giessen, Germany
| | - Veronika Grau
- Laboratory of Experimental Surgery, Department of General and Thoracic Surgery, Justus-Liebig-University Giessen, German Centre for Lung Research (DZL), Giessen, Germany
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Nielsen BE, Minguez T, Bermudez I, Bouzat C. Molecular function of the novel α7β2 nicotinic receptor. Cell Mol Life Sci 2018; 75:2457-2471. [PMID: 29313059 PMCID: PMC11105712 DOI: 10.1007/s00018-017-2741-4] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2017] [Revised: 11/30/2017] [Accepted: 12/27/2017] [Indexed: 01/03/2023]
Abstract
The α7 nicotinic receptor is a promising drug target for neurological and inflammatory disorders. Although it is the homomeric member of the family, a novel α7β2 heteromeric receptor has been discovered. To decipher the functional contribution of the β2 subunit, we generated heteromeric receptors with fixed stoichiometry by two different approaches comprising concatenated and unlinked subunits. Receptors containing up to three β2 subunits are functional. As the number of β2 subunits increases in the pentameric arrangement, the durations of channel openings and activation episodes increase progressively probably due to decreased desensitization. The prolonged activation episodes conform the kinetic signature of α7β2 and may have an impact on neuronal excitability. For activation of α7β2 receptors, an α7/α7 binding-site interface is required, thus indicating that the three β2 subunits are located consecutively in the pentameric arrangement. α7-positive allosteric modulators (PAMs) are emerging as novel therapeutic drugs. The presence of β2 in the pentamer affects neither type II PAM potentiation nor activation by an allosteric agonist whereas it impairs type I PAM potentiation. This first single-channel study provides fundamental basis required to decipher the role and function of the novel α7β2 receptor and opens doors to develop selective therapeutic drugs.
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Affiliation(s)
- Beatriz E Nielsen
- Instituto de Investigaciones Bioquímicas de Bahía Blanca, Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur-Consejo Nacional de Investigaciones Científicas y Técnicas (UNS-CONICET), 8000, Bahía Blanca, Argentina
| | - Teresa Minguez
- Department of Medical and Biological Sciences, Oxford Brookes University, Oxford, OX3 0BP, UK
| | - Isabel Bermudez
- Department of Medical and Biological Sciences, Oxford Brookes University, Oxford, OX3 0BP, UK
| | - Cecilia Bouzat
- Instituto de Investigaciones Bioquímicas de Bahía Blanca, Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur-Consejo Nacional de Investigaciones Científicas y Técnicas (UNS-CONICET), 8000, Bahía Blanca, Argentina.
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Bouzat C, Sine SM. Nicotinic acetylcholine receptors at the single-channel level. Br J Pharmacol 2018; 175:1789-1804. [PMID: 28261794 PMCID: PMC5979820 DOI: 10.1111/bph.13770] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Revised: 02/21/2017] [Accepted: 02/24/2017] [Indexed: 01/28/2023] Open
Abstract
Over the past four decades, the patch clamp technique and nicotinic ACh (nACh) receptors have established an enduring partnership. Like all good partnerships, each partner has proven significant in its own right, while their union has spurred innumerable advances in life science research. A member and prototype of the superfamily of pentameric ligand-gated ion channels, the nACh receptor is a chemo-electric transducer, binding ACh released from nerves and rapidly opening its channel to cation flow to elicit cellular excitation. A subject of a Nobel Prize in Physiology or Medicine, the patch clamp technique provides unprecedented resolution of currents through single ion channels in their native cellular environments. Here, focusing on muscle and α7 nACh receptors, we describe the extraordinary contribution of the patch clamp technique towards understanding how they activate in response to neurotransmitter, how subtle structural and mechanistic differences among nACh receptor subtypes translate into significant physiological differences, and how nACh receptors are being exploited as therapeutic drug targets. LINKED ARTICLES This article is part of a themed section on Nicotinic Acetylcholine Receptors. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v175.11/issuetoc/.
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Affiliation(s)
- Cecilia Bouzat
- Instituto de Investigaciones Bioquímicas de Bahía Blanca, INIBIBB (CONICET‐UNS), Departamento de Biología, Bioquímica y FarmaciaUniversidad Nacional del SurBahía BlancaArgentina
| | - Steven M Sine
- Receptor Biology Laboratory, Department of Physiology and Biomedical EngineeringMayo Clinic College of MedicineRochesterMN55905USA
- Department of NeurologyMayo Clinic College of MedicineRochesterMN55905USA
- Department of Pharmacology and Experimental TherapeuticsMayo Clinic College of MedicineRochesterMN55905USA
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Lasala M, Corradi J, Bruzzone A, Esandi MDC, Bouzat C. A human-specific, truncated α7 nicotinic receptor subunit assembles with full-length α7 and forms functional receptors with different stoichiometries. J Biol Chem 2018; 293:10707-10717. [PMID: 29784875 DOI: 10.1074/jbc.ra117.001698] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2017] [Revised: 05/15/2018] [Indexed: 11/06/2022] Open
Abstract
The cholinergic α7 nicotinic receptor gene, CHRNA7, encodes a subunit that forms the homopentameric α7 receptor, involved in learning and memory. In humans, exons 5-10 in CHRNA7 are duplicated and fused to the FAM7A genetic element, giving rise to the hybrid gene CHRFAM7A Its product, dupα7, is a truncated subunit lacking part of the N-terminal extracellular ligand-binding domain and is associated with neurological disorders, including schizophrenia, and immunomodulation. We combined dupα7 expression on mammalian cells with patch clamp recordings to understand its functional role. Transfected cells expressed dupα7 protein, but they exhibited neither surface binding of the α7 antagonist α-bungarotoxin nor responses to acetylcholine (ACh) or to an allosteric agonist that binds to the conserved transmembrane region. To determine whether dupα7 assembles with α7, we generated receptors comprising α7 and dupα7 subunits, one of which was tagged with conductance substitutions that report subunit stoichiometry and monitored ACh-elicited channel openings in the presence of a positive allosteric α7 modulator. We found that α7 and dupα7 subunits co-assemble into functional heteromeric receptors, which require at least two α7 subunits for channel opening, and that dupα7's presence in the pentameric arrangement does not affect the duration of the potentiated events compared with that of α7. Using an α7 subunit mutant, we found that activation of (α7)2(dupα7)3 receptors occurs through ACh binding at the α7/α7 interfacial binding site. Our study contributes to the understanding of the modulation of α7 function by the human specific, duplicated subunit, associated with human disorders.
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Affiliation(s)
- Matías Lasala
- From the Instituto de Investigaciones Bioquímicas de Bahía Blanca, Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), 8000 Bahía Blanca, Argentina
| | - Jeremías Corradi
- From the Instituto de Investigaciones Bioquímicas de Bahía Blanca, Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), 8000 Bahía Blanca, Argentina
| | - Ariana Bruzzone
- From the Instituto de Investigaciones Bioquímicas de Bahía Blanca, Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), 8000 Bahía Blanca, Argentina
| | - María Del Carmen Esandi
- From the Instituto de Investigaciones Bioquímicas de Bahía Blanca, Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), 8000 Bahía Blanca, Argentina
| | - Cecilia Bouzat
- From the Instituto de Investigaciones Bioquímicas de Bahía Blanca, Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), 8000 Bahía Blanca, Argentina
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Affiliation(s)
- Derek Bowie
- Department of Pharmacology and TherapeuticsMcGill UniversityMontréalQuébec H3G 1Y6Canada
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44
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Ren C, Li XH, Wang SB, Wang LX, Dong N, Wu Y, Yao YM. Activation of Central Alpha 7 Nicotinic Acetylcholine Receptor Reverses Suppressed Immune Function of T Lymphocytes and Protects Against Sepsis Lethality. Int J Biol Sci 2018; 14:748-759. [PMID: 29910685 PMCID: PMC6001681 DOI: 10.7150/ijbs.24576] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2017] [Accepted: 04/07/2018] [Indexed: 12/29/2022] Open
Abstract
Sepsis remains the leading cause of high mortality and huge financial burden in intensive care units (ICU), but with scarce effective treatments due to refractory multiple organ dysfunction and persistent immunosuppression. Treatments that aim at modulating immune function and attenuating multiple organ injury will certainly benefit septic cases. Alpha 7 nicotinic acetylcholine receptor (α7nAchR) has been reported with potent immunomodulatory properties in various diseases as the essential mediator of the cholinergic anti-inflammatory pathway (CAP). Few studies have demonstrated the potential effect of central α7nAchR on the progression and prognosis of septic response, while its expression was first discovered on neurons and most abundant in the central nervous system. In the present study, it was found severe damage of multiple organs under the operation of cecal ligation and puncture (CLP) in rats, including heart, liver, kidneys, and lungs, as evidenced by abnormal histomorphology and notable elevation of injury markers. Concurrently, the function of spleen CD4+ T cells was disrupted under septic challenge, accompanied by polarization of helper T cell (Th)2, which exhibited outward signs of immunosuppression. Intracerebroventricular injection of PNU282987, a selective agonist of α7nAchR, significantly alleviated multiple organ injury, reversed immunosuppressive state, and improved the outcome of septic rats, while they were exacerbated by treatment with methyllycaconitine, a selective antagonist of α7nAchR. This study provides the first evidence that activation of central α7nAchR is beneficial for attenuating multiple organ dysfunction as well as abnormal immune response, and improving the prognosis of rats when exposed with sepsis.
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Affiliation(s)
- Chao Ren
- Trauma Research Center, First Hospital Affiliated to the Chinese PLA General Hospital, Beijing 100048, People's Republic of China.,School of Medicine, Nankai University, Tianjin 300071, People's Republic of China
| | - Xiu-Hua Li
- Trauma Research Center, First Hospital Affiliated to the Chinese PLA General Hospital, Beijing 100048, People's Republic of China.,Emergency Department, Jin Hua Municipal Central Hospital, Jinhua 321001, People's Republic of China
| | - Shi-Bin Wang
- Trauma Research Center, First Hospital Affiliated to the Chinese PLA General Hospital, Beijing 100048, People's Republic of China
| | - Li-Xue Wang
- Trauma Research Center, First Hospital Affiliated to the Chinese PLA General Hospital, Beijing 100048, People's Republic of China
| | - Ning Dong
- Trauma Research Center, First Hospital Affiliated to the Chinese PLA General Hospital, Beijing 100048, People's Republic of China
| | - Yao Wu
- Trauma Research Center, First Hospital Affiliated to the Chinese PLA General Hospital, Beijing 100048, People's Republic of China
| | - Yong-Ming Yao
- Trauma Research Center, First Hospital Affiliated to the Chinese PLA General Hospital, Beijing 100048, People's Republic of China.,School of Medicine, Nankai University, Tianjin 300071, People's Republic of China.,State Key Laboratory of Kidney Disease, the Chinese PLA General Hospital, Beijing 100853, People's Republic of China
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45
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Designing selective modulators for the nicotinic receptor subtypes: challenges and opportunities. Future Med Chem 2018; 10:433-459. [PMID: 29451400 DOI: 10.4155/fmc-2017-0169] [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: 12/13/2022] Open
Abstract
Nicotinic receptors are membrane proteins involved in several physiological processes. They are considered suitable drug targets for various CNS disorders or conditions, as shown by the large number of compounds which have entered clinical trials. In recent years, nonconventional agonists have been discovered: positive allosteric modulators, allosteric agonists, site-specific agonists and silent desensitizers are compounds able to modulate the receptor interacting at sites different from the orthodox one, or to desensitize the receptor without prior opening. While these new findings can further complicate the pharmacology of these proteins and the design and optimization of ligands, they undoubtedly offer new opportunities to find drugs for the many therapeutic indications involving nicotinic receptors.
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Bouzat C, Lasala M, Nielsen BE, Corradi J, Esandi MDC. Molecular function of α7 nicotinic receptors as drug targets. J Physiol 2017; 596:1847-1861. [PMID: 29131336 DOI: 10.1113/jp275101] [Citation(s) in RCA: 67] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2017] [Accepted: 11/02/2017] [Indexed: 12/20/2022] Open
Abstract
Nicotinic acetylcholine receptors (nAChRs) are pentameric ligand-gated ion channels involved in many physiological and pathological processes. In vertebrates, there are seventeen different nAChR subunits that combine to yield a variety of receptors with different pharmacology, function, and localization. The homomeric α7 receptor is one of the most abundant nAChRs in the nervous system and it is also present in non-neuronal cells. It plays important roles in cognition, memory, pain, neuroprotection, and inflammation. Its diverse physiological actions and associated disorders have made of α7 an attractive novel target for drug modulation. Potentiation of the α7 receptor has emerged as a novel therapeutic strategy for several neurological diseases, such as Alzheimer's and Parkinson's diseases, and inflammatory disorders. In contrast, increased α7 activity has been associated with cancer cell proliferation. The presence of different drug target sites offers a great potential for α7 modulation in different pathological contexts. In particular, compounds that target allosteric sites offer significant advantages over orthosteric agonists due to higher selectivity and a broader spectrum of degrees and mechanisms of modulation. Heterologous expression of α7, together with chaperone proteins, combined with patch clamp recordings have provided important advances in our knowledge of the molecular basis of α7 responses and their potential modulation for pathological processes. This review gives a synthetic view of α7 and its molecular function, focusing on how its unique activation and desensitization features can be modified by pharmacological agents. This fundamental information offers insights into therapeutic strategies.
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Affiliation(s)
- Cecilia Bouzat
- Instituto de Investigaciones Bioquímicas de Bahía Blanca, Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur, CONICET/UNS, 8000, Bahía Blanca, Argentina
| | - Matías Lasala
- Instituto de Investigaciones Bioquímicas de Bahía Blanca, Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur, CONICET/UNS, 8000, Bahía Blanca, Argentina
| | - Beatriz Elizabeth Nielsen
- Instituto de Investigaciones Bioquímicas de Bahía Blanca, Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur, CONICET/UNS, 8000, Bahía Blanca, Argentina
| | - Jeremías Corradi
- Instituto de Investigaciones Bioquímicas de Bahía Blanca, Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur, CONICET/UNS, 8000, Bahía Blanca, Argentina
| | - María Del Carmen Esandi
- Instituto de Investigaciones Bioquímicas de Bahía Blanca, Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur, CONICET/UNS, 8000, Bahía Blanca, Argentina
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47
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Ion BF, Wells MM, Chen Q, Xu Y, Tang P. Ketamine Inhibition of the Pentameric Ligand-Gated Ion Channel GLIC. Biophys J 2017; 113:605-612. [PMID: 28793215 DOI: 10.1016/j.bpj.2017.06.041] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2017] [Revised: 06/14/2017] [Accepted: 06/22/2017] [Indexed: 12/11/2022] Open
Abstract
Ketamine inhibits pentameric ligand-gated ion channels (pLGICs), including the bacterial pLGIC from Gloeobacter violaceus (GLIC). The crystal structure of GLIC shows R-ketamine bound to an extracellular intersubunit cavity. Here, we performed molecular dynamics simulations of GLIC in the absence and presence of R- or S-ketamine. No stable binding of S-ketamine in the original cavity was observed in the simulations, largely due to its unfavorable access to residue D154, which provides important electrostatic interactions to stabilize R-ketamine binding. Contrary to the symmetric binding shown in the crystal structure, R-ketamine moved away from some of the binding sites and was bound to GLIC asymmetrically at the end of simulations. The asymmetric binding is consistent with the experimentally measured negative cooperativity of ketamine binding to GLIC. In the presence of R-ketamine, all subunits showed changes in structure and dynamics, irrespective of binding stability; the extracellular intersubunit cavity expanded and intersubunit electrostatic interactions involved in channel activation were altered. R-ketamine binding promoted a conformational shift toward closed GLIC. Conformational changes near the ketamine-binding site were propagated to the interface between the extracellular and transmembrane domains, and further to the pore-lining TM2 through two pathways: pre-TM1 and the β1-β2 loop. Both signaling pathways have been predicted previously using the perturbation-based Markovian transmission model. The study provides a structural and dynamics basis for the inhibitory modulation of ketamine on pLGICs.
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Affiliation(s)
- Bogdan F Ion
- Departments of Anesthesiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Marta M Wells
- Departments of Anesthesiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania; Computational and Systems Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Qiang Chen
- Departments of Anesthesiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Yan Xu
- Departments of Anesthesiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania; Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania; Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Pei Tang
- Departments of Anesthesiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania; Computational and Systems Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania; Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania.
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48
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Degani-Katzav N, Klein M, Har-Even M, Gortler R, Tobi R, Paas Y. Trapping of ivermectin by a pentameric ligand-gated ion channel upon open-to-closed isomerization. Sci Rep 2017; 7:42481. [PMID: 28218274 PMCID: PMC5317004 DOI: 10.1038/srep42481] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Accepted: 01/11/2017] [Indexed: 11/09/2022] Open
Abstract
Ivermectin (IVM) is a broad-spectrum anthelmintic drug used to treat human parasitic diseases like river blindness and lymphatic filariasis. By activating invertebrate pentameric glutamate-gated chloride channels (GluCl receptors; GluClRs), IVM induces sustained chloride influx and long-lasting membrane hyperpolarization that inhibit neural excitation in nematodes. Although IVM activates the C. elegans heteromeric GluClα/β receptor, it cannot activate a homomeric receptor composed of the C. elegans GluClβ subunits. To understand this incapability, we generated a homopentameric α7-GluClβ chimeric receptor that consists of an extracellular ligand-binding domain of an α7 nicotinic acetylcholine receptor known to be potentiated by IVM, and a chloride-selective channel domain assembled from GluClβ subunits. Application of IVM prior to acetylcholine inhibited the responses of the chimeric α7-GluClβR. Adding IVM to activated α7-GluClβRs, considerably accelerated the decline of ACh-elicited currents and stabilized the receptors in a non-conducting state. Determination of IVM association and dissociation rate constants and recovery experiments suggest that, following initial IVM binding to open α7-GluClβRs, the drug induces a conformational change and locks the ion channel in a closed state for a long duration. We further found that IVM also inhibits the activation by glutamate of a homomeric receptor assembled from the C. elegans full-length GluClβ subunits.
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Affiliation(s)
- Nurit Degani-Katzav
- Laboratory of Ion Channels, The Mina and Everard Goodman Faculty of Life Sciences and The Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat Gan 52900, Israel
| | - Moshe Klein
- Laboratory of Ion Channels, The Mina and Everard Goodman Faculty of Life Sciences and The Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat Gan 52900, Israel
| | - Moran Har-Even
- Laboratory of Ion Channels, The Mina and Everard Goodman Faculty of Life Sciences and The Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat Gan 52900, Israel
| | - Revital Gortler
- Laboratory of Ion Channels, The Mina and Everard Goodman Faculty of Life Sciences and The Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat Gan 52900, Israel
| | - Ruthi Tobi
- Laboratory of Ion Channels, The Mina and Everard Goodman Faculty of Life Sciences and The Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat Gan 52900, Israel
| | - Yoav Paas
- Laboratory of Ion Channels, The Mina and Everard Goodman Faculty of Life Sciences and The Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat Gan 52900, Israel
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49
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Boffi JC, Marcovich I, Gill-Thind JK, Corradi J, Collins T, Lipovsek MM, Moglie M, Plazas PV, Craig PO, Millar NS, Bouzat C, Elgoyhen AB. Differential Contribution of Subunit Interfaces to α9α10 Nicotinic Acetylcholine Receptor Function. Mol Pharmacol 2017; 91:250-262. [PMID: 28069778 PMCID: PMC5325082 DOI: 10.1124/mol.116.107482] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Accepted: 01/04/2017] [Indexed: 12/31/2022] Open
Abstract
Nicotinic acetylcholine receptors can be assembled from either homomeric or heteromeric pentameric subunit combinations. At the interface of the extracellular domains of adjacent subunits lies the acetylcholine binding site, composed of a principal component provided by one subunit and a complementary component of the adjacent subunit. Compared with neuronal nicotinic acetylcholine cholinergic receptors (nAChRs) assembled from α and β subunits, the α9α10 receptor is an atypical member of the family. It is a heteromeric receptor composed only of α subunits. Whereas mammalian α9 subunits can form functional homomeric α9 receptors, α10 subunits do not generate functional channels when expressed heterologously. Hence, it has been proposed that α10 might serve as a structural subunit, much like a β subunit of heteromeric nAChRs, providing only complementary components to the agonist binding site. Here, we have made use of site-directed mutagenesis to examine the contribution of subunit interface domains to α9α10 receptors by a combination of electrophysiological and radioligand binding studies. Characterization of receptors containing Y190T mutations revealed unexpectedly that both α9 and α10 subunits equally contribute to the principal components of the α9α10 nAChR. In addition, we have shown that the introduction of a W55T mutation impairs receptor binding and function in the rat α9 subunit but not in the α10 subunit, indicating that the contribution of α9 and α10 subunits to complementary components of the ligand-binding site is nonequivalent. We conclude that this asymmetry, which is supported by molecular docking studies, results from adaptive amino acid changes acquired only during the evolution of mammalian α10 subunits.
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Affiliation(s)
- Juan Carlos Boffi
- Instituto de Investigaciones en Ingeniería, Genética y Biología Molecular, Dr Héctor N Torres (J.C.B., I.M., M.M. L., M.M., P.V.P., A.B.E.), Instituto de Química Biológica (P.O.C.), and Instituto de Investigaciones Bioquímicas de Bahía Blanca (J.C., C.B), Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina; Department of Neuroscience, Physiology and Pharmacology, University College London, United Kingdom (J.K.G.-T., T.C., N.S.M.); Departamento de Química Biológica Facultad de Ciencias Exactas y Naturales (P.O.C.), and Instituto de Farmacología, Facultad de Medicina (P.V.P., A.B.E.), Universidad de Buenos Aires, Buenos Aires, Argentina; and Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur, Bahía Blanca, Argentina (J.C., C.B)
| | - Irina Marcovich
- Instituto de Investigaciones en Ingeniería, Genética y Biología Molecular, Dr Héctor N Torres (J.C.B., I.M., M.M. L., M.M., P.V.P., A.B.E.), Instituto de Química Biológica (P.O.C.), and Instituto de Investigaciones Bioquímicas de Bahía Blanca (J.C., C.B), Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina; Department of Neuroscience, Physiology and Pharmacology, University College London, United Kingdom (J.K.G.-T., T.C., N.S.M.); Departamento de Química Biológica Facultad de Ciencias Exactas y Naturales (P.O.C.), and Instituto de Farmacología, Facultad de Medicina (P.V.P., A.B.E.), Universidad de Buenos Aires, Buenos Aires, Argentina; and Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur, Bahía Blanca, Argentina (J.C., C.B)
| | - JasKiran K Gill-Thind
- Instituto de Investigaciones en Ingeniería, Genética y Biología Molecular, Dr Héctor N Torres (J.C.B., I.M., M.M. L., M.M., P.V.P., A.B.E.), Instituto de Química Biológica (P.O.C.), and Instituto de Investigaciones Bioquímicas de Bahía Blanca (J.C., C.B), Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina; Department of Neuroscience, Physiology and Pharmacology, University College London, United Kingdom (J.K.G.-T., T.C., N.S.M.); Departamento de Química Biológica Facultad de Ciencias Exactas y Naturales (P.O.C.), and Instituto de Farmacología, Facultad de Medicina (P.V.P., A.B.E.), Universidad de Buenos Aires, Buenos Aires, Argentina; and Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur, Bahía Blanca, Argentina (J.C., C.B)
| | - Jeremías Corradi
- Instituto de Investigaciones en Ingeniería, Genética y Biología Molecular, Dr Héctor N Torres (J.C.B., I.M., M.M. L., M.M., P.V.P., A.B.E.), Instituto de Química Biológica (P.O.C.), and Instituto de Investigaciones Bioquímicas de Bahía Blanca (J.C., C.B), Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina; Department of Neuroscience, Physiology and Pharmacology, University College London, United Kingdom (J.K.G.-T., T.C., N.S.M.); Departamento de Química Biológica Facultad de Ciencias Exactas y Naturales (P.O.C.), and Instituto de Farmacología, Facultad de Medicina (P.V.P., A.B.E.), Universidad de Buenos Aires, Buenos Aires, Argentina; and Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur, Bahía Blanca, Argentina (J.C., C.B)
| | - Toby Collins
- Instituto de Investigaciones en Ingeniería, Genética y Biología Molecular, Dr Héctor N Torres (J.C.B., I.M., M.M. L., M.M., P.V.P., A.B.E.), Instituto de Química Biológica (P.O.C.), and Instituto de Investigaciones Bioquímicas de Bahía Blanca (J.C., C.B), Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina; Department of Neuroscience, Physiology and Pharmacology, University College London, United Kingdom (J.K.G.-T., T.C., N.S.M.); Departamento de Química Biológica Facultad de Ciencias Exactas y Naturales (P.O.C.), and Instituto de Farmacología, Facultad de Medicina (P.V.P., A.B.E.), Universidad de Buenos Aires, Buenos Aires, Argentina; and Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur, Bahía Blanca, Argentina (J.C., C.B)
| | - María Marcela Lipovsek
- Instituto de Investigaciones en Ingeniería, Genética y Biología Molecular, Dr Héctor N Torres (J.C.B., I.M., M.M. L., M.M., P.V.P., A.B.E.), Instituto de Química Biológica (P.O.C.), and Instituto de Investigaciones Bioquímicas de Bahía Blanca (J.C., C.B), Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina; Department of Neuroscience, Physiology and Pharmacology, University College London, United Kingdom (J.K.G.-T., T.C., N.S.M.); Departamento de Química Biológica Facultad de Ciencias Exactas y Naturales (P.O.C.), and Instituto de Farmacología, Facultad de Medicina (P.V.P., A.B.E.), Universidad de Buenos Aires, Buenos Aires, Argentina; and Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur, Bahía Blanca, Argentina (J.C., C.B)
| | - Marcelo Moglie
- Instituto de Investigaciones en Ingeniería, Genética y Biología Molecular, Dr Héctor N Torres (J.C.B., I.M., M.M. L., M.M., P.V.P., A.B.E.), Instituto de Química Biológica (P.O.C.), and Instituto de Investigaciones Bioquímicas de Bahía Blanca (J.C., C.B), Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina; Department of Neuroscience, Physiology and Pharmacology, University College London, United Kingdom (J.K.G.-T., T.C., N.S.M.); Departamento de Química Biológica Facultad de Ciencias Exactas y Naturales (P.O.C.), and Instituto de Farmacología, Facultad de Medicina (P.V.P., A.B.E.), Universidad de Buenos Aires, Buenos Aires, Argentina; and Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur, Bahía Blanca, Argentina (J.C., C.B)
| | - Paola V Plazas
- Instituto de Investigaciones en Ingeniería, Genética y Biología Molecular, Dr Héctor N Torres (J.C.B., I.M., M.M. L., M.M., P.V.P., A.B.E.), Instituto de Química Biológica (P.O.C.), and Instituto de Investigaciones Bioquímicas de Bahía Blanca (J.C., C.B), Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina; Department of Neuroscience, Physiology and Pharmacology, University College London, United Kingdom (J.K.G.-T., T.C., N.S.M.); Departamento de Química Biológica Facultad de Ciencias Exactas y Naturales (P.O.C.), and Instituto de Farmacología, Facultad de Medicina (P.V.P., A.B.E.), Universidad de Buenos Aires, Buenos Aires, Argentina; and Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur, Bahía Blanca, Argentina (J.C., C.B)
| | - Patricio O Craig
- Instituto de Investigaciones en Ingeniería, Genética y Biología Molecular, Dr Héctor N Torres (J.C.B., I.M., M.M. L., M.M., P.V.P., A.B.E.), Instituto de Química Biológica (P.O.C.), and Instituto de Investigaciones Bioquímicas de Bahía Blanca (J.C., C.B), Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina; Department of Neuroscience, Physiology and Pharmacology, University College London, United Kingdom (J.K.G.-T., T.C., N.S.M.); Departamento de Química Biológica Facultad de Ciencias Exactas y Naturales (P.O.C.), and Instituto de Farmacología, Facultad de Medicina (P.V.P., A.B.E.), Universidad de Buenos Aires, Buenos Aires, Argentina; and Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur, Bahía Blanca, Argentina (J.C., C.B)
| | - Neil S Millar
- Instituto de Investigaciones en Ingeniería, Genética y Biología Molecular, Dr Héctor N Torres (J.C.B., I.M., M.M. L., M.M., P.V.P., A.B.E.), Instituto de Química Biológica (P.O.C.), and Instituto de Investigaciones Bioquímicas de Bahía Blanca (J.C., C.B), Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina; Department of Neuroscience, Physiology and Pharmacology, University College London, United Kingdom (J.K.G.-T., T.C., N.S.M.); Departamento de Química Biológica Facultad de Ciencias Exactas y Naturales (P.O.C.), and Instituto de Farmacología, Facultad de Medicina (P.V.P., A.B.E.), Universidad de Buenos Aires, Buenos Aires, Argentina; and Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur, Bahía Blanca, Argentina (J.C., C.B)
| | - Cecilia Bouzat
- Instituto de Investigaciones en Ingeniería, Genética y Biología Molecular, Dr Héctor N Torres (J.C.B., I.M., M.M. L., M.M., P.V.P., A.B.E.), Instituto de Química Biológica (P.O.C.), and Instituto de Investigaciones Bioquímicas de Bahía Blanca (J.C., C.B), Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina; Department of Neuroscience, Physiology and Pharmacology, University College London, United Kingdom (J.K.G.-T., T.C., N.S.M.); Departamento de Química Biológica Facultad de Ciencias Exactas y Naturales (P.O.C.), and Instituto de Farmacología, Facultad de Medicina (P.V.P., A.B.E.), Universidad de Buenos Aires, Buenos Aires, Argentina; and Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur, Bahía Blanca, Argentina (J.C., C.B)
| | - Ana Belén Elgoyhen
- Instituto de Investigaciones en Ingeniería, Genética y Biología Molecular, Dr Héctor N Torres (J.C.B., I.M., M.M. L., M.M., P.V.P., A.B.E.), Instituto de Química Biológica (P.O.C.), and Instituto de Investigaciones Bioquímicas de Bahía Blanca (J.C., C.B), Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina; Department of Neuroscience, Physiology and Pharmacology, University College London, United Kingdom (J.K.G.-T., T.C., N.S.M.); Departamento de Química Biológica Facultad de Ciencias Exactas y Naturales (P.O.C.), and Instituto de Farmacología, Facultad de Medicina (P.V.P., A.B.E.), Universidad de Buenos Aires, Buenos Aires, Argentina; and Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur, Bahía Blanca, Argentina (J.C., C.B).
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50
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Powell AD, Grafton G, Roberts A, Larkin S, O'Neill N, Palandri J, Otvos R, Cooper AJ, Ulens C, Barnes NM. Novel mechanism of modulation at a ligand-gated ion channel; action of 5-Cl-indole at the 5-HT 3 A receptor. Br J Pharmacol 2016; 173:3467-3479. [PMID: 27677804 DOI: 10.1111/bph.13638] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Revised: 09/09/2016] [Accepted: 09/16/2016] [Indexed: 01/09/2023] Open
Abstract
BACKGROUND AND PURPOSE The 5-HT3 receptor is a prototypical member of the Cys-loop ligand-gated ion channel (LGIC) superfamily and an established therapeutic target. In addition to activation via the orthosteric site, receptor function can be modulated by allosteric ligands. We have investigated the pharmacological action of Cl-indole upon the 5-HT3 A receptor and identified that this positive allosteric modulator possesses a novel mechanism of action for LGICs. EXPERIMENTAL APPROACH The impact of Cl-indole upon the 5-HT3 receptor was assessed using single cell electrophysiological recordings and [3 H]-granisetron binding in HEK293 cells stably expressing the 5-HT3 receptor. KEY RESULTS Cl-indole failed to evoke 5-HT3 A receptor-mediated responses (up to 30 μM) or display affinity for the [3 H]-granisetron binding site. However, in the presence of Cl-indole, termination of 5-HT application revealed tail currents mediated via the 5-HT3 A receptor that were independent of the preceding 5-HT concentration but were antagonized by the 5-HT3 receptor antagonist, ondansetron. These tail currents were absent in the 5-HT3 AB receptor. Furthermore, the presence of 5-HT revealed a concentration-dependent increase in the affinity of Cl-indole for the orthosteric binding site of the human 5-HT3 A receptor. CONCLUSIONS AND IMPLICATIONS Cl-indole acts as both an orthosteric agonist and an allosteric modulator, but the presence of an orthosteric agonist (e.g. 5-HT) is a prerequisite to reveal both actions. Precedent for ago-allosteric action is available, yet the essential additional presence of an orthosteric agonist is now reported for the first time. This widening of the pharmacological mechanisms to modulate LGICs may offer further therapeutic opportunities.
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Affiliation(s)
- Andrew D Powell
- Clinical and Experimental Medicine, College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK.,School of Nursing Midwifery and Social Work, Birmingham City University, Edgbaston, UK
| | - Gillian Grafton
- Clinical and Experimental Medicine, College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK
| | - Alexander Roberts
- Clinical and Experimental Medicine, College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK
| | - Shannon Larkin
- Clinical and Experimental Medicine, College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK
| | - Nathanael O'Neill
- Clinical and Experimental Medicine, College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK
| | - Josephine Palandri
- Clinical and Experimental Medicine, College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK
| | - Reka Otvos
- Department of Molecular and Cellular Neurobiology, VU University Amsterdam, Amsterdam, The Netherlands
| | - Alison J Cooper
- Clinical and Experimental Medicine, College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK
| | - Chris Ulens
- Laboratory of Structural Neurobiology, KU Leuven, Leuven, Belgium
| | - Nicholas M Barnes
- Clinical and Experimental Medicine, College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK.,Department of Pharmacology and Therapeutics, School of Biomedical Sciences, Faculty of Medicine, Dentistry and Health Sciences, The University of Melbourne, Parkville, Victoria, Australia
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