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Wang DP, Zhang M, Li M, Yang XN, Li C, Cao P, Zhu MX, Tian Y, Yu Y, Lei YT. Druggable site near the upper vestibule determines the high affinity and P2X3 homotrimer selectivity of sivopixant/S-600918 and its analogue DDTPA. Br J Pharmacol 2024; 181:1203-1220. [PMID: 37921202 DOI: 10.1111/bph.16273] [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: 01/30/2023] [Revised: 09/13/2023] [Accepted: 10/14/2023] [Indexed: 11/04/2023] Open
Abstract
BACKGROUND AND PURPOSE The P2X3 receptor, a trimeric ionotropic purinergic receptor, has emerged as a potential therapeutic target for refractory chronic cough (RCC). Nevertheless, gefapixant/AF-219, the only marketed P2X3 receptor antagonist, might lead taste disorders by modulating the human P2X2/3 (hP2X2/3) heterotrimer. Hence, in RCC drug development, compounds exhibiting strong affinity for the hP2X3 homotrimer and a weak affinity for the hP2X2/3 heterotrimer hold promise. An example of such a molecule is sivopixant/S-600918, a clinical Phase II RCC candidate with a reduced incidence of taste disturbance compared to gefapixant. Sivopixant and its analogue, (3-(4-([3-chloro-4-isopropoxyphenyl]amino)-3-(4-methylbenzyl)-2,6-dioxo-3,6-dihydro-1,3,5-triazin-1(2H)-yl)propanoic acid (DDTPA), exhibit both high affinity and high selectivity for hP2X3 homotrimers, compared with hP2X2/3 heterotrimers. The mechanism underlying the druggable site and its high selectivity remains unclear. EXPERIMENTAL APPROACH To analyse mechanisms that distinguish this drug candidate from other inhibitors of the P2X3 receptors we used a combination of chimera construction, site covalent occupation, metadynamics, mutagenesis and whole-cell recording. KEY RESULTS The high affinity and selectivity of sivopixant/DDTPA for hP2X3 receptors was determined by the tri-symmetric site located close to the upper vestibule. Substitution of only four amino acids inside the upper body domain of hP2X2 with those of hP2X3, enabled the hP2X2/3 heterotrimer to exhibit a similar level of apparent affinity for sivopixant/DDTPA as the hP2X3 homotrimer. CONCLUSION AND IMPLICATIONS From the receptor-ligand recognition perspective, we have elucidated the molecular basis of novel RCC clinical candidates' cough-suppressing properties and reduced side effects, offering a promising approach to the discovery of novel drugs that specifically target P2X3 receptors.
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Affiliation(s)
- Dong-Ping Wang
- College of Bioscience and Biotechnology, Hunan Agricultural University, Changsha, China
- School of Sciences and State Key Laboratory of Natural Medicines, China Pharmaceutical University, Nanjing, China
| | - Meng Zhang
- College of Bioscience and Biotechnology, Hunan Agricultural University, Changsha, China
- School of Sciences and State Key Laboratory of Natural Medicines, China Pharmaceutical University, Nanjing, China
| | - Ming Li
- School of Sciences and State Key Laboratory of Natural Medicines, China Pharmaceutical University, Nanjing, China
| | - Xiao-Na Yang
- College of Bioscience and Biotechnology, Hunan Agricultural University, Changsha, China
- School of Sciences and State Key Laboratory of Natural Medicines, China Pharmaceutical University, Nanjing, China
| | - Changzhu Li
- State Key Laboratory of Utilization of Woody Oil Resource, Hunan Academy of Forestry, Changsha, China
| | - Peng Cao
- Hospital of Integrated Traditional Chinese and Western Medicine, Nanjing University of Chinese Medicine, Nanjing, China
| | - Michael X Zhu
- Department of Integrative Biology and Pharmacology, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, Texas, USA
| | - Yun Tian
- College of Bioscience and Biotechnology, Hunan Agricultural University, Changsha, China
| | - Ye Yu
- School of Sciences and State Key Laboratory of Natural Medicines, China Pharmaceutical University, Nanjing, China
| | - Yun-Tao Lei
- School of Sciences and State Key Laboratory of Natural Medicines, China Pharmaceutical University, Nanjing, China
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Wu YY, Wang Q, Zhang PA, Zhu C, Xu GY. miR-1306-3p directly activates P2X3 receptors in primary sensory neurons to induce visceral pain in rats. Pain 2023; 164:1555-1565. [PMID: 36633528 PMCID: PMC10281022 DOI: 10.1097/j.pain.0000000000002853] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Revised: 10/23/2022] [Accepted: 11/08/2022] [Indexed: 01/13/2023]
Abstract
ABSTRACT Mounting evidence indicates that microRNAs (miRNAs) play critical roles in various pathophysiological conditions and diseases, but the physiological roles of extracellular miRNAs on the disease-related ion channels remain largely unknown. Here, we showed that miR-1306-3p evoked action potentials and induced inward currents of the acutely isolated rat dorsal root ganglion (DRG) neurons. The miR-1306-3p-induced effects were significantly inhibited by A317491, a potent inhibitor of the P2X3 receptor (P2X3R), or disappeared after the knockdown of P2X3Rs in DRG neurons. We further identified R180, K315, and R52 as the miR-1306-3p interaction sites on the extracellular domain of P2X3Rs, which were distinct from the orthosteric ATP-binding sites. Intrathecal injection of miR-1306-3p produced visceral pain but not somatic pain in normal control rats. Conversely, intrathecal application of a miR-1306-3p antagomir and A317491 significantly alleviated visceral pain in a rat model of chronic visceral pain. Together, our findings suggest that miR-1306-3p might function as an endogenous ligand to activate P2X3Rs, eventually leading to chronic visceral pain.
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Affiliation(s)
- Yan-Yan Wu
- Jiangsu Key Laboratory of Neuropsychiatric Diseases and Institute of Neuroscience, Soochow University, Suzhou, Jiangsu, P.R. China
- School of Life Sciences and Research Center for Resource Peptide Drugs, Shaanxi Engineering and Technological Research Center for Conversation and Utilization of Regional Biological Resources, Yanan University, Yanan, P. R. China
| | - Qian Wang
- Department of Anesthesiology, Children's Hospital of Soochow University, Suzhou, P.R. China
| | - Ping-An Zhang
- Jiangsu Key Laboratory of Neuropsychiatric Diseases and Institute of Neuroscience, Soochow University, Suzhou, Jiangsu, P.R. China
| | - Cheng Zhu
- Tianjin Key Laboratory of Function and Application of Biological Macromolecular Structures, School of Life Sciences, Tianjin University, Tianjin, P.R. China
| | - Guang-Yin Xu
- Jiangsu Key Laboratory of Neuropsychiatric Diseases and Institute of Neuroscience, Soochow University, Suzhou, Jiangsu, P.R. China
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3
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Volonté C, Amadio S. Rethinking purinergic concepts and updating the emerging role of P2X7 and P2X4 in amyotrophic lateral sclerosis. Neuropharmacology 2022; 221:109278. [PMID: 36202258 DOI: 10.1016/j.neuropharm.2022.109278] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2022] [Revised: 09/27/2022] [Accepted: 09/29/2022] [Indexed: 11/08/2022]
Abstract
The topic of the present review regards the ubiquitous and phylogenetically most ancient prototype of intercellular signaling, the one mediated by extracellular nucleosides and nucleotides, bearing a strong influence on pathophysiological processes in the nervous system. Not by chance, purine and pyrimidine molecules are the most prevalent and ubiquitous chemical messengers in the animal and plant kingdoms, operating through a large plethora of purinergic metabolizing enzymes, P1 and P2 receptors, nucleoside and nucleotide channels and transporters. Because ectonucleotidases degrade the agonists of P2 receptors while simultaneously generate the agonists for P1 receptors, and because several agonists, or antagonists, simultaneously bind and activate, or inhibit, more than one receptor subtype, it follows that an all-inclusive "purinergic network" perspective should be better considered when looking at purinergic actions. This becomes particularly crucial during pathological conditions as for instance amyotrophic lateral sclerosis, where the contribution of purinergic signaling has been demonstrated to differ according to each target cell phenotype and stage of disease progression. Here we will present some newly updated results about P2X7 and P2X4 as the most thoroughly investigated P2 receptors in amyotrophic lateral sclerosis, being aware that the comprehension of their actions is still in progress, and that the purinergic rationale for studying this disease must be however wide-ranging and all-inclusive. This article is part of the Special Issue on 'Purinergic Signaling: 50 years'.
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Affiliation(s)
- Cinzia Volonté
- CNR-Institute for Systems Analysis and Computer Science "Antonio Ruberti", Via Dei Taurini 19, 00185, Rome, Italy; IRCCS Fondazione Santa Lucia-Cellular Neurobiology Unit, Via Del Fosso di Fiorano 65, 00143, Rome, Italy.
| | - Susanna Amadio
- IRCCS Fondazione Santa Lucia-Cellular Neurobiology Unit, Via Del Fosso di Fiorano 65, 00143, Rome, Italy
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4
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Sattler C, Benndorf K. Enlightening activation gating in P2X receptors. Purinergic Signal 2022; 18:177-191. [PMID: 35188598 PMCID: PMC9123132 DOI: 10.1007/s11302-022-09850-w] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Accepted: 02/04/2022] [Indexed: 12/20/2022] Open
Abstract
P2X receptors are trimeric nonselective cation channels gated by ATP. They assemble from seven distinct subunit isoforms as either homo- or heteromeric complexes and contain three extracellularly located binding sites for ATP. P2X receptors are expressed in nearly all tissues and are there involved in physiological processes like synaptic transmission, pain, and inflammation. Thus, they are a challenging pharmacological target. The determination of crystal and cryo-EM structures of several isoforms in the last decade in closed, open, and desensitized states has provided a firm basis for interpreting the huge amount of functional and biochemical data. Electrophysiological characterization in conjugation with optical approaches has generated significant insights into structure–function relationships of P2X receptors. This review focuses on novel optical and related approaches to better understand the conformational changes underlying the activation of these receptors.
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Affiliation(s)
- Christian Sattler
- Institut Für Physiologie II, Universitätsklinikum Jena, Friedrich-Schiller-Universität Jena, 07740, Jena, Germany.
| | - Klaus Benndorf
- Institut Für Physiologie II, Universitätsklinikum Jena, Friedrich-Schiller-Universität Jena, 07740, Jena, Germany.
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5
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Andriani RT, Kubo Y. Voltage-clamp fluorometry analysis of structural rearrangements of ATP-gated channel P2X2 upon hyperpolarization. eLife 2021; 10:65822. [PMID: 34009126 PMCID: PMC8184218 DOI: 10.7554/elife.65822] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Accepted: 05/18/2021] [Indexed: 12/17/2022] Open
Abstract
Gating of the ATP-activated channel P2X2 has been shown to be dependent not only on [ATP] but also on membrane voltage, despite the absence of a canonical voltage-sensor domain. We aimed to investigate the structural rearrangements of rat P2X2 during ATP- and voltage-dependent gating, using a voltage-clamp fluorometry technique. We observed fast and linearly voltage-dependent fluorescence intensity (F) changes at Ala337 and Ile341 in the TM2 domain, which could be due to the electrochromic effect, reflecting the presence of a converged electric field. We also observed slow and voltage-dependent F changes at Ala337, which reflect structural rearrangements. Furthermore, we determined that the interaction between Ala337 in TM2 and Phe44 in TM1, which are in close proximity in the ATP-bound open state, is critical for activation. Taking these results together, we propose that the voltage dependence of the interaction within the converged electric field underlies the voltage-dependent gating.
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Affiliation(s)
- Rizki Tsari Andriani
- Division of Biophysics and Neurobiology, National Institute for Physiological Sciences, Aichi, Japan.,Department of Physiological Sciences, The Graduate University for Advanced Studies, School of Life Science, Kanagawa, Japan
| | - Yoshihiro Kubo
- Division of Biophysics and Neurobiology, National Institute for Physiological Sciences, Aichi, Japan.,Department of Physiological Sciences, The Graduate University for Advanced Studies, School of Life Science, Kanagawa, Japan
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6
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Jiang LH, Caseley EA, Muench SP, Roger S. Structural basis for the functional properties of the P2X7 receptor for extracellular ATP. Purinergic Signal 2021; 17:331-344. [PMID: 33987781 PMCID: PMC8410900 DOI: 10.1007/s11302-021-09790-x] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Accepted: 04/19/2021] [Indexed: 02/06/2023] Open
Abstract
The P2X7 receptor, originally known as the P2Z receptor due to its distinctive functional properties, has a structure characteristic of the ATP-gated ion channel P2X receptor family. The P2X7 receptor is an important mediator of ATP-induced purinergic signalling and is involved the pathogenesis of numerous conditions as well as in the regulation of diverse physiological functions. Functional characterisations, in conjunction with site-directed mutagenesis, molecular modelling, and, recently, structural determination, have provided significant insights into the structure–function relationships of the P2X7 receptor. This review discusses the current understanding of the structural basis for the functional properties of the P2X7 receptor.
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Affiliation(s)
- Lin-Hua Jiang
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, UK.
| | - Emily A Caseley
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, UK
- Faculty of Medicine and Health, Leeds Institute of Rheumatic and Musculoskeletal Medicine, St James's University Hospital, Leeds, UK
| | - Steve P Muench
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, UK
| | - Sébastien Roger
- EA4245, Transplantation, Immunology and Inflammation, Faculty of Medicine, University of Tours, Tours, France
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7
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Huang Z, Xie N, Illes P, Di Virgilio F, Ulrich H, Semyanov A, Verkhratsky A, Sperlagh B, Yu SG, Huang C, Tang Y. From purines to purinergic signalling: molecular functions and human diseases. Signal Transduct Target Ther 2021; 6:162. [PMID: 33907179 PMCID: PMC8079716 DOI: 10.1038/s41392-021-00553-z] [Citation(s) in RCA: 172] [Impact Index Per Article: 57.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Revised: 01/24/2021] [Accepted: 02/24/2021] [Indexed: 02/06/2023] Open
Abstract
Purines and their derivatives, most notably adenosine and ATP, are the key molecules controlling intracellular energy homoeostasis and nucleotide synthesis. Besides, these purines support, as chemical messengers, purinergic transmission throughout tissues and species. Purines act as endogenous ligands that bind to and activate plasmalemmal purinoceptors, which mediate extracellular communication referred to as "purinergic signalling". Purinergic signalling is cross-linked with other transmitter networks to coordinate numerous aspects of cell behaviour such as proliferation, differentiation, migration, apoptosis and other physiological processes critical for the proper function of organisms. Pathological deregulation of purinergic signalling contributes to various diseases including neurodegeneration, rheumatic immune diseases, inflammation, and cancer. Particularly, gout is one of the most prevalent purine-related disease caused by purine metabolism disorder and consequent hyperuricemia. Compelling evidence indicates that purinoceptors are potential therapeutic targets, with specific purinergic agonists and antagonists demonstrating prominent therapeutic potential. Furthermore, dietary and herbal interventions help to restore and balance purine metabolism, thus addressing the importance of a healthy lifestyle in the prevention and relief of human disorders. Profound understanding of molecular mechanisms of purinergic signalling provides new and exciting insights into the treatment of human diseases.
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Grants
- National Key R&D Program of China (2019YFC1709101,2020YFA0509400, 2020YFC2002705), the National Natural Science Foundation of China (81821002, 81790251, 81373735, 81972665), Guangdong Basic and Applied Basic Research Foundation (2019B030302012), the Project First-Class Disciplines Development of Chengdu University of Traditional Chinese Medicine (CZYHW1901), São Paulo Research Foundation (FAPESP 2018/07366-4), Russian Science Foundation grant 20-14-00241, NSFC-BFBR;and Science and Technology Program of Sichuan Province, China (2019YFH0108)
- National Key R&D Program of China (2020YFA0509400, 2020YFC2002705), the National Natural Science Foundation of China (81821002, 81790251).
- National Key R&D Program of China (2020YFA0509400, 2020YFC2002705), the National Natural Science Foundation of China (81821002, 81790251), Guangdong Basic and Applied Basic Research Foundation (2019B030302012).
- the Project First-Class Disciplines Development of Chengdu University of Traditional Chinese Medicine (CZYHW1901) and Science and Technology Program of Sichuan Province, China (2019YFH0108).
- the Project First-Class Disciplines Development of Chengdu University of Traditional Chinese Medicine (CZYHW1901), and Science and Technology Program of Sichuan Province, China (2019YFH0108).
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Affiliation(s)
- Zhao Huang
- State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, and West China School of Basic Medical Sciences & Forensic Medicine, Sichuan University, and Collaborative Innovation Center for Biotherapy, Chengdu, China
| | - Na Xie
- State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, and West China School of Basic Medical Sciences & Forensic Medicine, Sichuan University, and Collaborative Innovation Center for Biotherapy, Chengdu, China
| | - Peter Illes
- International Collaborative Centre on Big Science Plan for Purinergic Signalling, Chengdu University of Traditional Chinese Medicine, Chengdu, China
- Rudolf-Boehm-Institut für Pharmakologie und Toxikologie, Universitaet Leipzig, Leipzig, Germany
| | | | - Henning Ulrich
- International Collaborative Centre on Big Science Plan for Purinergic Signalling, Chengdu University of Traditional Chinese Medicine, Chengdu, China
- Department of Biochemistry, Institute of Chemistry, University of São Paulo, São Paulo, Brazil
| | - Alexey Semyanov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, Russia
- Sechenov First Moscow State Medical University, Moscow, Russia
| | - Alexei Verkhratsky
- International Collaborative Centre on Big Science Plan for Purinergic Signalling, Chengdu University of Traditional Chinese Medicine, Chengdu, China
- Sechenov First Moscow State Medical University, Moscow, Russia
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK
| | - Beata Sperlagh
- Department of Pharmacology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary
| | - Shu-Guang Yu
- International Collaborative Centre on Big Science Plan for Purinergic Signalling, Chengdu University of Traditional Chinese Medicine, Chengdu, China
- Acupuncture and Chronobiology Key Laboratory of Sichuan Province, Chengdu, China
| | - Canhua Huang
- State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, and West China School of Basic Medical Sciences & Forensic Medicine, Sichuan University, and Collaborative Innovation Center for Biotherapy, Chengdu, China.
- School of Basic Medical Sciences, Chengdu University of Traditional Chinese Medicine, Chengdu, China.
| | - Yong Tang
- International Collaborative Centre on Big Science Plan for Purinergic Signalling, Chengdu University of Traditional Chinese Medicine, Chengdu, China.
- Acupuncture and Chronobiology Key Laboratory of Sichuan Province, Chengdu, China.
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8
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Purinergic Regulation of Endothelial Barrier Function. Int J Mol Sci 2021; 22:ijms22031207. [PMID: 33530557 PMCID: PMC7865261 DOI: 10.3390/ijms22031207] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Revised: 01/10/2021] [Accepted: 01/22/2021] [Indexed: 12/12/2022] Open
Abstract
Increased vascular permeability is a hallmark of several cardiovascular anomalies, including ischaemia/reperfusion injury and inflammation. During both ischaemia/reperfusion and inflammation, massive amounts of various nucleotides, particularly adenosine 5'-triphosphate (ATP) and adenosine, are released that can induce a plethora of signalling pathways via activation of several purinergic receptors and may affect endothelial barrier properties. The nature of the effects on endothelial barrier function may depend on the prevalence and type of purinergic receptors activated in a particular tissue. In this review, we discuss the influence of the activation of various purinergic receptors and downstream signalling pathways on vascular permeability during pathological conditions.
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9
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Illes P, Müller CE, Jacobson KA, Grutter T, Nicke A, Fountain SJ, Kennedy C, Schmalzing G, Jarvis MF, Stojilkovic SS, King BF, Di Virgilio F. Update of P2X receptor properties and their pharmacology: IUPHAR Review 30. Br J Pharmacol 2020; 178:489-514. [PMID: 33125712 PMCID: PMC8199792 DOI: 10.1111/bph.15299] [Citation(s) in RCA: 164] [Impact Index Per Article: 41.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Revised: 10/20/2020] [Accepted: 10/22/2020] [Indexed: 12/20/2022] Open
Abstract
The known seven mammalian receptor subunits (P2X1–7) form cationic channels gated by ATP. Three subunits compose a receptor channel. Each subunit is a polypeptide consisting of two transmembrane regions (TM1 and TM2), intracellular N- and C-termini, and a bulky extracellular loop. Crystallization allowed the identification of the 3D structure and gating cycle of P2X receptors. The agonist-binding pocket is located at the intersection of two neighbouring subunits. In addition to the mammalian P2X receptors, their primitive ligand-gated counterparts with little structural similarity have also been cloned. Selective agonists for P2X receptor subtypes are not available, but medicinal chemistry supplied a range of subtype-selective antagonists, as well as positive and negative allosteric modulators. Knockout mice and selective antagonists helped to identify pathological functions due to defective P2X receptors, such as male infertility (P2X1), hearing loss (P2X2), pain/cough (P2X3), neuropathic pain (P2X4), inflammatory bone loss (P2X5), and faulty immune reactions (P2X7).
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Affiliation(s)
- Peter Illes
- Rudolf Boehm Institute for Pharmacology and Toxicology, University of Leipzig, Leipzig, Germany.,International Collaborative Centre on Big Science Plan for Purinergic Signalling, Chengdu University of Traditional Chinese Medicine, Chengdu, China
| | - Christa E Müller
- PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical & Medicinal Chemistry, University of Bonn, Bonn, Germany
| | - Kenneth A Jacobson
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Thomas Grutter
- University of Strasbourg, Centre National de la Recherche Scientifique, CAMB UMR 7199, Strasbourg, France
| | - Annette Nicke
- Walther Straub Institute for Pharmacology and Toxicology, Ludwig-Maximilians-Universität München, Munich, Germany
| | | | - Charles Kennedy
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, UK
| | - Günther Schmalzing
- Institute of Clinical Pharmacology, RWTH Aachen University, Aachen, Germany
| | | | - Stanko S Stojilkovic
- Section on Cellular Signaling, The Eunice Kennedy Shiver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Brian F King
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, UK
| | - Francesco Di Virgilio
- Department of Medical Sciences, Section of Experimental Medicine, University of Ferrara, Ferrara, Italy
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10
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Unravelling the intricate cooperativity of subunit gating in P2X2 ion channels. Sci Rep 2020; 10:21751. [PMID: 33303878 PMCID: PMC7729398 DOI: 10.1038/s41598-020-78672-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Accepted: 11/25/2020] [Indexed: 01/23/2023] Open
Abstract
Ionotropic purinergic (P2X) receptors are trimeric channels that are activated by the binding of ATP. They are involved in multiple physiological functions, including synaptic transmission, pain and inflammation. The mechanism of activation is still elusive. Here we kinetically unraveled and quantified subunit activation in P2X2 receptors by an extensive global fit approach with four complex and intimately coupled kinetic schemes to currents obtained from wild type and mutated receptors using ATP and its fluorescent derivative 2-[DY-547P1]-AET-ATP (fATP). We show that the steep concentration-activation relationship in wild type channels is caused by a subunit flip reaction with strong positive cooperativity, overbalancing a pronounced negative cooperativity for the three ATP binding steps, that the net probability fluxes in the model generate a marked hysteresis in the activation-deactivation cycle, and that the predicted fATP binding matches the binding measured by fluorescence. Our results shed light into the intricate activation process of P2X channels.
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11
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Sattler C, Schmauder R, Schwabe T, Schweinitz A, Unzeitig C, Schwede F, Otte M, Benndorf K. Relating ligand binding to activation gating in P2X2 receptors using a novel fluorescent ATP derivative. J Neurochem 2020; 154:251-262. [PMID: 31883343 DOI: 10.1111/jnc.14948] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Revised: 11/29/2019] [Accepted: 12/18/2019] [Indexed: 11/28/2022]
Abstract
Ionotropic purinergic receptors (P2X receptors) are non-specific cation channels that are activated by the binding of ATP at their extracellular side. P2X receptors contribute to multiple functions, including the generation of pain, inflammation, or synaptic transmission. The channels are trimers and structural information on several of their isoforms is available. In contrast, the cooperation of the subunits in the activation process is poorly understood. We synthesized a novel fluorescent ATP derivative, 2-[DY-547P1]-AET-ATP (fATP) to unravel the complex activation process in P2X2 and mutated P2X2 H319K channels with enhanced apparent affinity by characterizing the relation between ligand binding and activation gating. fATP is a full agonist with respect to ATP that reports the degree of binding by bright fluorescence. For quantifying the binding, a fast automated algorithm was employed on human embryonic kidney cell culture images. The concentrations of half maximum occupancy and activation as well as the respective Hill coefficients were determined. All Hill coefficients exceeded unity, even at an occupancy <10%, suggesting cooperativity of the binding even for the first and second binding step. fATP shows promise for continuative functional studies on other purinergic receptors and, beyond, any other ATP-binding proteins.
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Affiliation(s)
- Christian Sattler
- Institut für Physiologie II, Universitätsklinikum Jena, Friedrich-Schiller-Universität Jena, Jena, Germany
| | - Ralf Schmauder
- Institut für Physiologie II, Universitätsklinikum Jena, Friedrich-Schiller-Universität Jena, Jena, Germany
| | - Tina Schwabe
- Institut für Physiologie II, Universitätsklinikum Jena, Friedrich-Schiller-Universität Jena, Jena, Germany
| | - Andrea Schweinitz
- Institut für Physiologie II, Universitätsklinikum Jena, Friedrich-Schiller-Universität Jena, Jena, Germany
| | - Christopher Unzeitig
- Institut für Physiologie II, Universitätsklinikum Jena, Friedrich-Schiller-Universität Jena, Jena, Germany
| | - Frank Schwede
- BIOLOG Life Science Institute GmbH & Co. KG, Bremen, Germany
| | - Maik Otte
- Institut für Physiologie II, Universitätsklinikum Jena, Friedrich-Schiller-Universität Jena, Jena, Germany
| | - Klaus Benndorf
- Institut für Physiologie II, Universitätsklinikum Jena, Friedrich-Schiller-Universität Jena, Jena, Germany
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12
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Cao F, Hu LQ, Yao SR, Hu Y, Wang DG, Fan YG, Pan GX, Tao SS, Zhang Q, Pan HF, Wu GC. P2X7 receptor: A potential therapeutic target for autoimmune diseases. Autoimmun Rev 2019; 18:767-777. [PMID: 31181327 DOI: 10.1016/j.autrev.2019.06.009] [Citation(s) in RCA: 63] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2019] [Accepted: 02/15/2019] [Indexed: 12/20/2022]
Abstract
P2X7 receptor (P2X7R), a distinct ligand-gated ion channel, is a member of purinergic type 2 receptor family with ubiquitous expression in human body. Previous studies have revealed a pivotal role of P2X7R in innate and adaptive immunity. Once activated, it will meditate some vital cascaded responses including the assembly of nucleotide-binding domain (NOD) like receptor protein 3 (NLRP3) inflammasome, non-classical secretion of IL-1β, modulation of cytokine-independent pathways in inflammation such as P2X7R- transglutaminase-2 (TG2) and P2X7R-cathepsin pathway, activation and regulation of T cells, etc. In fact, above responses have been identified to be involved in the development of autoimmunity, specifically, the NLRP3 inflammasome could promote inflammation in massive autoimmune diseases and TG2, as well as cathepsin may contribute to joint destruction and degeneration in inflammatory arthritis. Recently, numerous evidences further suggested the significance of P2X7R in the pathogenesis of autoimmune diseases, including systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), inflammatory bowel disease (IBD), multiple sclerosis (MS), etc. In this review, we will succinctly discuss the biological characteristics and summarize the recent progress of the involvement of P2X7R in the development and pathogenesis of autoimmune diseases, as well as its clinical implications and therapeutic potential.
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Affiliation(s)
- Fan Cao
- Department of Clinical Medicine, The second School of Clinical Medicine, Anhui Medical University, 81 Meishan Road, Hefei, Anhui, China
| | - Li-Qin Hu
- School of Nursing, Anhui Medical University, 15 Feicui Road, Hefei, Anhui, China
| | - Shu-Ran Yao
- Department of Clinical Medicine, The second School of Clinical Medicine, Anhui Medical University, 81 Meishan Road, Hefei, Anhui, China
| | - Yan Hu
- School of Nursing, Anhui Medical University, 15 Feicui Road, Hefei, Anhui, China
| | - De-Guang Wang
- Department of Nephrology, The Second Affiliated Hospital of Anhui Medical University, 678 Furong Road, Hefei 230601, Anhui, China
| | - Yin-Guang Fan
- Department of Epidemiology and Biostatistics, School of Public Health, Anhui Medical University, 81 Meishan Road, Hefei, Anhui, China; Anhui Province Key Laboratory of Major Autoimmune Diseases, 81 Meishan Road, Hefei, Anhui, China
| | - Gui-Xia Pan
- Department of Epidemiology and Biostatistics, School of Public Health, Anhui Medical University, 81 Meishan Road, Hefei, Anhui, China; Anhui Province Key Laboratory of Major Autoimmune Diseases, 81 Meishan Road, Hefei, Anhui, China
| | - Sha-Sha Tao
- Department of Epidemiology and Biostatistics, School of Public Health, Anhui Medical University, 81 Meishan Road, Hefei, Anhui, China; Anhui Province Key Laboratory of Major Autoimmune Diseases, 81 Meishan Road, Hefei, Anhui, China
| | - Qin Zhang
- Department of Epidemiology and Biostatistics, School of Public Health, Anhui Medical University, 81 Meishan Road, Hefei, Anhui, China; Anhui Province Key Laboratory of Major Autoimmune Diseases, 81 Meishan Road, Hefei, Anhui, China
| | - Hai-Feng Pan
- Department of Epidemiology and Biostatistics, School of Public Health, Anhui Medical University, 81 Meishan Road, Hefei, Anhui, China; Anhui Province Key Laboratory of Major Autoimmune Diseases, 81 Meishan Road, Hefei, Anhui, China
| | - Guo-Cui Wu
- School of Nursing, Anhui Medical University, 15 Feicui Road, Hefei, Anhui, China.
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13
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Schmid R, Evans RJ. ATP-Gated P2X Receptor Channels: Molecular Insights into Functional Roles. Annu Rev Physiol 2018; 81:43-62. [PMID: 30354932 DOI: 10.1146/annurev-physiol-020518-114259] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
In the nervous system, ATP is co-stored in vesicles with classical transmitters and released in a regulated manner. ATP from the intracellular compartment can also exit the cell through hemichannels and following shear stress or membrane damage. In the past 30 years, the action of ATP as an extracellular transmitter at cell-surface receptors has evolved from somewhat of a novelty that was treated with skepticism to purinergic transmission being accepted as having widespread important functional roles mediated by ATP-gated ionotropic P2X receptors (P2XRs). This review focuses on work published in the last five years and provides an overview of ( a) structural studies, ( b) the molecular basis of channel properties and regulation of P2XRs, and ( c) the physiological and pathophysiological roles of ATP acting at defined P2XR subtypes.
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Affiliation(s)
- Ralf Schmid
- Department of Molecular and Cell Biology, University of Leicester, Leicester LE1 7RH, United Kingdom; .,Leicester Institute of Structural and Chemical Biology, University of Leicester, Leicester LE1 7RH, United Kingdom
| | - Richard J Evans
- Department of Molecular and Cell Biology, University of Leicester, Leicester LE1 7RH, United Kingdom;
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14
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Abstract
Extracellular ATP-gated P2X receptors are trimeric non-selective cation channels important for many physiological events including immune response and neural transmission. These receptors belong to a unique class of ligand-gated ion channels composed of only six transmembrane helices and a relatively small extracellular domain that harbors three ATP-binding pockets. The crystal structures of P2X receptors, including the recent P2X3 structures representing three different stages of the gating cycle, have provided a compelling structural foundation for understanding how this class of ligand-gated ion channels function. These structures, in combination with numerous functional studies ranging from classic mutagenesis and electrophysiology to modern optogenetic pharmacology, have uncovered unique molecular mechanisms of P2X receptor function. This review article summarizes the current knowledge in P2X receptor activation, especially focusing on the mechanisms underlying ATP-binding, conformational changes in the extracellular domain, and channel gating and desensitization.
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15
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Cyclin-dependent kinase 5 modulates the P2X2a receptor channel gating through phosphorylation of C-terminal threonine 372. Pain 2018; 158:2155-2168. [PMID: 28809765 DOI: 10.1097/j.pain.0000000000001021] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The purinergic P2X2 receptor (P2X2R) is an adenosine triphosphate-gated ion channel widely expressed in the nervous system. Here, we identified a putative cyclin-dependent kinase 5 (Cdk5) phosphorylation site in the full-size variant P2X2aR (TPKH), which is absent in the splice variant P2X2bR. We therefore investigated the effects of Cdk5 and its neuronal activator, p35, on P2X2aR function. We found an interaction between P2X2aR and Cdk5/p35 by co-immunofluorescence and co-immunoprecipitation in HEK293 cells. We also found that threonine phosphorylation was significantly increased in HEK293 cells co-expressing P2X2aR and p35 as compared to cells expressing only P2X2aR. Moreover, P2X2aR-derived peptides encompassing the Cdk5 consensus motif were phosphorylated by Cdk5/p35. Whole-cell patch-clamp recordings indicated a delay in development of use-dependent desensitization (UDD) of P2X2aR but not of P2X2bR in HEK293 cells co-expressing P2X2aR and p35. In Xenopus oocytes, P2X2aRs showed a slower UDD than in HEK293 cells and Cdk5 activation prevented this effect. A similar effect was found in P2X2a/3R heteromeric currents in HEK293 cells. The P2X2aR-T372A mutant was resistant to UDD. In endogenous cells, we observed similar distribution between P2X2R and Cdk5/p35 by co-localization using immunofluorescence in primary culture of nociceptive neurons. Moreover, co-immunoprecipitation experiments showed an interaction between Cdk5 and P2X2R in mouse trigeminal ganglia. Finally, endogenous P2X2aR-mediated currents in PC12 cells and P2X2/3R mediated increases of intracellular Ca in trigeminal neurons were Cdk5 dependent, since inhibition with roscovitine accelerated the desensitization kinetics of these responses. These results indicate that the P2X2aR is a novel target for Cdk5-mediated phosphorylation, which might play important physiological roles including pain signaling.
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16
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Björkgren I, Lishko PV. Purinergic signaling in testes revealed. J Gen Physiol 2018; 148:207-11. [PMID: 27574291 PMCID: PMC5004342 DOI: 10.1085/jgp.201611676] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2016] [Accepted: 08/08/2016] [Indexed: 12/14/2022] Open
Affiliation(s)
- Ida Björkgren
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720
| | - Polina V Lishko
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720
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17
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Bonvini SJ, Belvisi MG. Cough and airway disease: The role of ion channels. Pulm Pharmacol Ther 2017; 47:21-28. [PMID: 28669932 DOI: 10.1016/j.pupt.2017.06.009] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Revised: 06/27/2017] [Accepted: 06/29/2017] [Indexed: 01/07/2023]
Abstract
Cough is the most common reason for patients to visit a primary care physician, yet it remains an unmet medical need. It can be idiopathic in nature but can also be a troublesome symptom across chronic lung diseases such as asthma, COPD and idiopathic pulmonary fibrosis (IPF). Chronic cough affects up to 12% of the population and yet there are no safe and effective therapies. The cough reflex is regulated by vagal, sensory afferent nerves which innervate the airway. The Transient Receptor Potential (TRP) family of ion channels are expressed on sensory nerve terminals, and when activated can evoke cough. This review focuses on the role of 4 TRP channels; TRP Vannilloid 1 (TRPV1), TRP Ankyrin 1 (TRPA1), TRP Vannilloid 4 (TRPV4) and TRP Melastatin 8 (TRPM8) and the purinergic P2X3 receptor and their possible role in chronic cough. We conclude that these ion channels, given their expression profile and their role in the activation of sensory afferents and the cough reflex, may represent excellent therapeutic targets for the treatment of respiratory symptoms in chronic lung disease.
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Affiliation(s)
- Sara J Bonvini
- Respiratory Pharmacology Group, Airway Disease Section, National Heart & Lung Institute, Imperial College, Exhibition Road, London SW7 2AZ, UK
| | - Maria G Belvisi
- Respiratory Pharmacology Group, Airway Disease Section, National Heart & Lung Institute, Imperial College, Exhibition Road, London SW7 2AZ, UK.
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18
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Zhu Y, Beudez J, Yu N, Grutter T, Zhao HB. P2X2 Dominant Deafness Mutations Have No Negative Effect on Wild-Type Isoform: Implications for Functional Rescue and in Deafness Mechanism. Front Mol Neurosci 2017; 10:371. [PMID: 29180951 PMCID: PMC5693881 DOI: 10.3389/fnmol.2017.00371] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2017] [Accepted: 10/26/2017] [Indexed: 11/13/2022] Open
Abstract
The P2X2 receptor is an ATP-gated ion channel, assembled by three subunits. Recently, it has been found that heterozygous mutations of P2X2 V60L and G353R can cause autosomal dominant nonsyndromic hearing loss. However, the underlying mechanism remains unclear. The fact that heterozygous mutations cause deafness suggests that the mutations may have dominant-negative effect (DNE) on wild-type (WT) P2X2 isoforms and/or other partners leading to hearing loss. In this study, the effect of these dominant deafness P2X2 mutations on WT P2X2 was investigated. We found that sole transfection of both V60L and G353R deafness mutants could efficiently target to the plasma membrane, like WT P2X2, but exhibit a significantly reduced response to ATP stimulation. Both mutants reduced the channel conductance, but G353R mutation also altered the voltage dependency. Co-expression with WT P2X2 could restore the response to ATP. As the ratio of WT P2X2 vs. mutants increased, the response to ATP was also increased. Computer modeling confirmed that both V60L and G353R dominant-deafness mutant subunits do not have any negative effect on WT P2X2 subunit, when assembled as a heterotrimer. Improper docking or defective gating is the more likely mechanism for impaired channel function by these P2X2 deafness mutations. These results suggest that P2X2 dominant deafness mutations do not have negative effects on WT P2X2 isoforms, and that adding additional WT P2X2 could rescue the lost channel function caused by the deafness mutations. These P2X2 dominant deafness mutations may have negative-effects on other partners leading to hearing loss.
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Affiliation(s)
- Yan Zhu
- Department of Otolaryngology, University of Kentucky Medical Center, Lexington, KY, United States
| | - Juline Beudez
- Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7199, Laboratoire de Conception et Application de Molécules Bioactives, Équipe de Chimie et Neurobiologie Moléculaire, Strasbourg, France.,Faculté de Pharmacie, Université de Strasbourg, Strasbourg, France
| | - Ning Yu
- Department of Otolaryngology, University of Kentucky Medical Center, Lexington, KY, United States.,Department of Otolaryngology, Institute of Otolaryngology, Chinese PLA General Hospital, Beijing, China
| | - Thomas Grutter
- Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7199, Laboratoire de Conception et Application de Molécules Bioactives, Équipe de Chimie et Neurobiologie Moléculaire, Strasbourg, France.,Faculté de Pharmacie, Université de Strasbourg, Strasbourg, France
| | - Hong-Bo Zhao
- Department of Otolaryngology, University of Kentucky Medical Center, Lexington, KY, United States
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19
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North RA. P2X receptors. Philos Trans R Soc Lond B Biol Sci 2017; 371:rstb.2015.0427. [PMID: 27377721 DOI: 10.1098/rstb.2015.0427] [Citation(s) in RCA: 113] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/23/2016] [Indexed: 12/23/2022] Open
Abstract
Extracellular adenosine 5'-triphosphate (ATP) activates cell surface P2X and P2Y receptors. P2X receptors are membrane ion channels preferably permeable to sodium, potassium and calcium that open within milliseconds of the binding of ATP. In molecular architecture, they form a unique structural family. The receptor is a trimer, the binding of ATP between subunits causes them to flex together within the ectodomain and separate in the membrane-spanning region so as to open a central channel. P2X receptors have a widespread tissue distribution. On some smooth muscle cells, P2X receptors mediate the fast excitatory junction potential that leads to depolarization and contraction. In the central nervous system, activation of P2X receptors allows calcium to enter neurons and this can evoke slower neuromodulatory responses such as the trafficking of receptors for the neurotransmitter glutamate. In primary afferent nerves, P2X receptors are critical for the initiation of action potentials when they respond to ATP released from sensory cells such as taste buds, chemoreceptors or urothelium. In immune cells, activation of P2X receptors triggers the release of pro-inflammatory cytokines such as interleukin 1β. The development of selective blockers of different P2X receptors has led to clinical trials of their effectiveness in the management of cough, pain, inflammation and certain neurodegenerative diseases.This article is part of the themed issue 'Evolution brings Ca(2+) and ATP together to control life and death'.
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Affiliation(s)
- R Alan North
- Faculty of Medical and Human Sciences, University of Manchester, Oxford Road, Manchester M13 9PL, UK
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20
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Ishchenko Y, Shakirzyanova A, Giniatullina R, Skorinkin A, Bart G, Turhanen P, Määttä JA, Mönkkönen J, Giniatullin R. Selective Calcium-Dependent Inhibition of ATP-Gated P2X3 Receptors by Bisphosphonate-Induced Endogenous ATP Analog ApppI. J Pharmacol Exp Ther 2017; 361:472-481. [PMID: 28404687 DOI: 10.1124/jpet.116.238840] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Accepted: 04/07/2017] [Indexed: 12/30/2022] Open
Abstract
Pain is the most unbearable symptom accompanying primary bone cancers and bone metastases. Bone resorptive disorders are often associated with hypercalcemia, contributing to the pathologic process. Nitrogen-containing bisphosphonates (NBPs) are efficiently used to treat bone cancers and metastases. Apart from their toxic effect on cancer cells, NBPs also provide analgesia via poorly understood mechanisms. We previously showed that NBPs, by inhibiting the mevalonate pathway, induced formation of novel ATP analogs such as ApppI [1-adenosin-5'-yl ester 3-(3-methylbut-3-enyl) triphosphoric acid diester], which can potentially be involved in NBP analgesia. In this study, we used the patch-clamp technique to explore the action of ApppI on native ATP-gated P2X receptors in rat sensory neurons and rat and human P2X3, P2X2, and P2X7 receptors expressed in human embryonic kidney cells. We found that although ApppI has weak agonist activity, it is a potent inhibitor of P2X3 receptors operating in the nanomolar range. The inhibitory action of ApppI was completely blocked in hypercalcemia-like conditions and was stronger in human than in rat P2X3 receptors. In contrast, P2X2 and P2X7 receptors were insensitive to ApppI, suggesting a high selectivity of ApppI for the P2X3 receptor subtype. NBP, metabolite isopentenyl pyrophosphate, and endogenous AMP did not exert any inhibitory action, indicating that only intact ApppI has inhibitory activity. Ca2+-dependent inhibition was stronger in trigeminal neurons preferentially expressing desensitizing P2X3 subunits than in nodose ganglia neurons, which also express nondesensitizing P2X2 subunits. Altogether, we characterized previously unknown purinergic mechanisms of NBP-induced metabolites and suggest ApppI as the endogenous pain inhibitor contributing to cancer treatment with NBPs.
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Affiliation(s)
- Yevheniia Ishchenko
- A. I. Virtanen Institute (Y.I., A.Sh., Rai.G., G.B., Ras.G.) and School of Pharmacy (P.T., J. M.), University of Eastern Finland, Kuopio, Finland; Kazan Institute of Biochemistry and Biophysics, Kazan, Russia (A.Sh., A.Sk.); Institute of Biomedicine, University of Turku, Turku, Finland (J.A.M.); and Kazan Federal University, Kazan, Russia (A.Sh., A.Sk., R.Gas.)
| | - Anastasia Shakirzyanova
- A. I. Virtanen Institute (Y.I., A.Sh., Rai.G., G.B., Ras.G.) and School of Pharmacy (P.T., J. M.), University of Eastern Finland, Kuopio, Finland; Kazan Institute of Biochemistry and Biophysics, Kazan, Russia (A.Sh., A.Sk.); Institute of Biomedicine, University of Turku, Turku, Finland (J.A.M.); and Kazan Federal University, Kazan, Russia (A.Sh., A.Sk., R.Gas.)
| | - Raisa Giniatullina
- A. I. Virtanen Institute (Y.I., A.Sh., Rai.G., G.B., Ras.G.) and School of Pharmacy (P.T., J. M.), University of Eastern Finland, Kuopio, Finland; Kazan Institute of Biochemistry and Biophysics, Kazan, Russia (A.Sh., A.Sk.); Institute of Biomedicine, University of Turku, Turku, Finland (J.A.M.); and Kazan Federal University, Kazan, Russia (A.Sh., A.Sk., R.Gas.)
| | - Andrei Skorinkin
- A. I. Virtanen Institute (Y.I., A.Sh., Rai.G., G.B., Ras.G.) and School of Pharmacy (P.T., J. M.), University of Eastern Finland, Kuopio, Finland; Kazan Institute of Biochemistry and Biophysics, Kazan, Russia (A.Sh., A.Sk.); Institute of Biomedicine, University of Turku, Turku, Finland (J.A.M.); and Kazan Federal University, Kazan, Russia (A.Sh., A.Sk., R.Gas.)
| | - Genevieve Bart
- A. I. Virtanen Institute (Y.I., A.Sh., Rai.G., G.B., Ras.G.) and School of Pharmacy (P.T., J. M.), University of Eastern Finland, Kuopio, Finland; Kazan Institute of Biochemistry and Biophysics, Kazan, Russia (A.Sh., A.Sk.); Institute of Biomedicine, University of Turku, Turku, Finland (J.A.M.); and Kazan Federal University, Kazan, Russia (A.Sh., A.Sk., R.Gas.)
| | - Petri Turhanen
- A. I. Virtanen Institute (Y.I., A.Sh., Rai.G., G.B., Ras.G.) and School of Pharmacy (P.T., J. M.), University of Eastern Finland, Kuopio, Finland; Kazan Institute of Biochemistry and Biophysics, Kazan, Russia (A.Sh., A.Sk.); Institute of Biomedicine, University of Turku, Turku, Finland (J.A.M.); and Kazan Federal University, Kazan, Russia (A.Sh., A.Sk., R.Gas.)
| | - Jorma A Määttä
- A. I. Virtanen Institute (Y.I., A.Sh., Rai.G., G.B., Ras.G.) and School of Pharmacy (P.T., J. M.), University of Eastern Finland, Kuopio, Finland; Kazan Institute of Biochemistry and Biophysics, Kazan, Russia (A.Sh., A.Sk.); Institute of Biomedicine, University of Turku, Turku, Finland (J.A.M.); and Kazan Federal University, Kazan, Russia (A.Sh., A.Sk., R.Gas.)
| | - Jukka Mönkkönen
- A. I. Virtanen Institute (Y.I., A.Sh., Rai.G., G.B., Ras.G.) and School of Pharmacy (P.T., J. M.), University of Eastern Finland, Kuopio, Finland; Kazan Institute of Biochemistry and Biophysics, Kazan, Russia (A.Sh., A.Sk.); Institute of Biomedicine, University of Turku, Turku, Finland (J.A.M.); and Kazan Federal University, Kazan, Russia (A.Sh., A.Sk., R.Gas.)
| | - Rashid Giniatullin
- A. I. Virtanen Institute (Y.I., A.Sh., Rai.G., G.B., Ras.G.) and School of Pharmacy (P.T., J. M.), University of Eastern Finland, Kuopio, Finland; Kazan Institute of Biochemistry and Biophysics, Kazan, Russia (A.Sh., A.Sk.); Institute of Biomedicine, University of Turku, Turku, Finland (J.A.M.); and Kazan Federal University, Kazan, Russia (A.Sh., A.Sk., R.Gas.)
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21
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Conformational changes during human P2X7 receptor activation examined by structural modelling and cysteine-based cross-linking studies. Purinergic Signal 2016; 13:135-141. [PMID: 28025718 PMCID: PMC5334206 DOI: 10.1007/s11302-016-9553-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2016] [Accepted: 12/15/2016] [Indexed: 12/23/2022] Open
Abstract
The P2X7 receptor (P2X7R) is important in mediating a range of physiological functions and pathologies associated with tissue damage and inflammation and represents an attractive therapeutic target. However, in terms of their structure-function relationships, the mammalian P2X7Rs remain poorly characterised compared to some of their other P2XR counterparts. In this study, combining cysteine-based cross-linking and whole-cell patch-clamp recording, we examined six pairs of residues (A44/I331, D48/I331, I58/F311, S60/L320, I75/P177 and K81/V304) located in different parts of the extracellular and transmembrane domains of the human P2X7R. These residues are predicted to undergo substantial movement during the transition of the receptor ion channel from the closed to the open state, predictions which are made based on structural homology models generated from the crystal structures of the zebrafish P2X4R. Our results provide evidence that among the six pairs of cysteine mutants, D48C/I133C and K81C/V304C formed disulphide bonds that impaired the channel gating to support the notion that such conformational changes, particularly those in the outer ends of the transmembrane domains, are critical for human P2X7R activation.
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22
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Purinergic signalling in autoimmunity: A role for the P2X7R in systemic lupus erythematosus? Biomed J 2016; 39:326-338. [PMID: 27884379 PMCID: PMC6138817 DOI: 10.1016/j.bj.2016.08.006] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2016] [Revised: 07/29/2016] [Accepted: 08/08/2016] [Indexed: 12/11/2022] Open
Abstract
Purinergic signalling plays a crucial role in immunity and autoimmunity. Among purinergic receptors, the P2X7 receptor (P2X7R) has an undisputed role as it is expressed to high level by immune cells, triggers cytokine release and modulates immune cell differentiation. In this review, we focus on evidence supporting a possible role of the P2X7R in the pathogenesis of systemic lupus erythematosus (SLE).
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23
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Tsuda M. P2 receptors, microglial cytokines and chemokines, and neuropathic pain. J Neurosci Res 2016; 95:1319-1329. [DOI: 10.1002/jnr.23816] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Revised: 05/19/2016] [Accepted: 06/13/2016] [Indexed: 01/12/2023]
Affiliation(s)
- Makoto Tsuda
- Department of Life Innovation, Department of Molecular and System Pharmacology, Graduate School of Pharmaceutical Sciences; Kyushu University; Fukuoka Japan
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24
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Jaramillo-Polanco J, Liñán-Rico A, Espinosa-Luna R, Jiménez-Bremont JF, Montaño LM, Miranda-Morales M, Barajas-López C. Heteromeric channels with different phenotypes are generated when coexpressing two P2X2 receptor isoforms. Biochem Biophys Res Commun 2016; 477:54-61. [PMID: 27282483 DOI: 10.1016/j.bbrc.2016.06.020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2016] [Accepted: 06/04/2016] [Indexed: 10/21/2022]
Abstract
To investigate if channels with different stoichiometry are formed from P2X2 receptor isoforms during their heterologous co-expression. The two-electrode voltage-clamp technique was used to measured ATP induced currents in Xenopus laevis oocytes. We used a mutant (P2X2-2bm) because its ATP sensitivity is lower than P2X2-2b receptors, which highlights the differences with its splice variant P2X2-1a.Currents through homomeric channels had significantly different Hill coefficients. P2XR are trimeric proteins with three agonist binding sites; therefore, only two homomeric and two heteromeric stoichiometries are possible when both P2X2 isoforms are coexpressed, the heteromeric channels might be formed by: i) 2(P2X2-1a)+1(P2X2-2bm); or ii) 1(P2X2-1a)+2(P2X2-2bm). Because P2X2 channels open when two binding sites are occupied, these stoichiometries are expected to have different ATP sensitivities. Thus, co-expressing both P2X2 isoforms, two oocyte populations were distinguished based on their sensitivity to ATP and Hill coefficients. For the first population (P2X2-1a like), the ATP EC50 and the Hill coefficient were not different than those of homomeric P2X2-1a channels similarly, for the second population (P2X2-2bm like), these variables were also not different than for those of homomeric P2X2-2bm channels. Various findings indicate that homomeric channel expression is not responsible for such differences. Our observations indicate that two heteromeric channels can be assembled from two P2X2 receptor isoforms. Our data support a current model, according to which, ATP activation of two subunits can open P2X2 channel. However, PPADS appears to bind to all three subunits in order to inhibit ATP effects on P2X2 receptors.
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Affiliation(s)
- Josue Jaramillo-Polanco
- División de Biología Molecular, Instituto Potosino de Investigación Científica y Tecnológica, San Luís Potosí, San Luís Potosí, Mexico
| | - Andrómeda Liñán-Rico
- División de Biología Molecular, Instituto Potosino de Investigación Científica y Tecnológica, San Luís Potosí, San Luís Potosí, Mexico
| | - Rosa Espinosa-Luna
- División de Biología Molecular, Instituto Potosino de Investigación Científica y Tecnológica, San Luís Potosí, San Luís Potosí, Mexico
| | - Juan F Jiménez-Bremont
- División de Biología Molecular, Instituto Potosino de Investigación Científica y Tecnológica, San Luís Potosí, San Luís Potosí, Mexico
| | - Luis M Montaño
- Departamento de Farmacología, Facultad de Medicina, Universidad Nacional Autónoma de México, México DF, Mexico
| | | | - Carlos Barajas-López
- División de Biología Molecular, Instituto Potosino de Investigación Científica y Tecnológica, San Luís Potosí, San Luís Potosí, Mexico.
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25
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Shcherbatko A, Foletti D, Poulsen K, Strop P, Zhu G, Hasa-Moreno A, Melton Witt J, Loo C, Krimm S, Pios A, Yu J, Brown C, Lee JK, Stroud R, Rajpal A, Shelton D. Modulation of P2X3 and P2X2/3 Receptors by Monoclonal Antibodies. J Biol Chem 2016; 291:12254-70. [PMID: 27129281 DOI: 10.1074/jbc.m116.722330] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Indexed: 01/06/2023] Open
Abstract
Purinergic homomeric P2X3 and heteromeric P2X2/3 receptors are ligand-gated cation channels activated by ATP. Both receptors are predominantly expressed in nociceptive sensory neurons, and an increase in extracellular ATP concentration under pathological conditions, such as tissue damage or visceral distension, induces channel opening, membrane depolarization, and initiation of pain signaling. Hence, these receptors are considered important therapeutic targets for pain management, and development of selective antagonists is currently progressing. To advance the search for novel analgesics, we have generated a panel of monoclonal antibodies directed against human P2X3 (hP2X3). We have found that these antibodies produce distinct functional effects, depending on the homomeric or heteromeric composition of the target, its kinetic state, and the duration of antibody exposure. The most potent antibody, 12D4, showed an estimated IC50 of 16 nm on hP2X3 after short term exposure (up to 18 min), binding to the inactivated state of the channel to inhibit activity. By contrast, with the same short term application, 12D4 potentiated the slow inactivating current mediated by the heteromeric hP2X2/3 channel. Extending the duration of exposure to ∼20 h resulted in a profound inhibition of both homomeric hP2X3 and heteromeric hP2X2/3 receptors, an effect mediated by efficient antibody-induced internalization of the channel from the plasma membrane. The therapeutic potential of mAb12D4 was assessed in the formalin, complete Freund's adjuvant, and visceral pain models. The efficacy of 12D4 in the visceral hypersensitivity model indicates that antibodies against P2X3 may have therapeutic potential in visceral pain indications.
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Affiliation(s)
- Anatoly Shcherbatko
- From the Rinat Laboratories, Pfizer Inc., South San Francisco, California 94080,
| | - Davide Foletti
- From the Rinat Laboratories, Pfizer Inc., South San Francisco, California 94080
| | - Kris Poulsen
- From the Rinat Laboratories, Pfizer Inc., South San Francisco, California 94080
| | - Pavel Strop
- From the Rinat Laboratories, Pfizer Inc., South San Francisco, California 94080
| | - Guoyun Zhu
- From the Rinat Laboratories, Pfizer Inc., South San Francisco, California 94080
| | - Adela Hasa-Moreno
- From the Rinat Laboratories, Pfizer Inc., South San Francisco, California 94080
| | - Jody Melton Witt
- From the Rinat Laboratories, Pfizer Inc., South San Francisco, California 94080
| | - Carole Loo
- From the Rinat Laboratories, Pfizer Inc., South San Francisco, California 94080
| | - Stellanie Krimm
- From the Rinat Laboratories, Pfizer Inc., South San Francisco, California 94080
| | - Ariel Pios
- From the Rinat Laboratories, Pfizer Inc., South San Francisco, California 94080
| | - Jessica Yu
- From the Rinat Laboratories, Pfizer Inc., South San Francisco, California 94080
| | - Colleen Brown
- From the Rinat Laboratories, Pfizer Inc., South San Francisco, California 94080
| | - John K Lee
- the Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, Minnesota 55455, and
| | - Robert Stroud
- the Department of Biochemistry and Biophysics, University of California, San Francisco, California 94158
| | - Arvind Rajpal
- From the Rinat Laboratories, Pfizer Inc., South San Francisco, California 94080
| | - David Shelton
- From the Rinat Laboratories, Pfizer Inc., South San Francisco, California 94080
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26
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Aprile-Garcia F, Metzger MW, Paez-Pereda M, Stadler H, Acuña M, Liberman AC, Senin SA, Gerez J, Hoijman E, Refojo D, Mitkovski M, Panhuysen M, Stühmer W, Holsboer F, Deussing JM, Arzt E. Co-Expression of Wild-Type P2X7R with Gln460Arg Variant Alters Receptor Function. PLoS One 2016; 11:e0151862. [PMID: 26986975 PMCID: PMC4795689 DOI: 10.1371/journal.pone.0151862] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2015] [Accepted: 03/04/2016] [Indexed: 01/04/2023] Open
Abstract
The P2X7 receptor is a member of the P2X family of ligand-gated ion channels. A single-nucleotide polymorphism leading to a glutamine (Gln) by arginine (Arg) substitution at codon 460 of the purinergic P2X7 receptor (P2X7R) has been associated with mood disorders. No change in function (loss or gain) has been described for this SNP so far. Here we show that although the P2X7R-Gln460Arg variant per se is not compromised in its function, co-expression of wild-type P2X7R with P2X7R-Gln460Arg impairs receptor function with respect to calcium influx, channel currents and intracellular signaling in vitro. Moreover, co-immunoprecipitation and FRET studies show that the P2X7R-Gln460Arg variant physically interacts with P2X7R-WT. Specific silencing of either the normal or polymorphic variant rescues the heterozygous loss of function phenotype and restores normal function. The described loss of function due to co-expression, unique for mutations in the P2RX7 gene so far, explains the mechanism by which the P2X7R-Gln460Arg variant affects the normal function of the channel and may represent a mechanism of action for other mutations.
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Affiliation(s)
- Fernando Aprile-Garcia
- Instituto de Investigación en Biomedicina de Buenos Aires (IBioBA)-CONICET- Partner Institute of the Max Planck Society, Buenos Aires, Argentina
- Departamento de Fisiología y Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
| | | | | | | | - Matías Acuña
- Instituto de Investigación en Biomedicina de Buenos Aires (IBioBA)-CONICET- Partner Institute of the Max Planck Society, Buenos Aires, Argentina
| | - Ana C. Liberman
- Instituto de Investigación en Biomedicina de Buenos Aires (IBioBA)-CONICET- Partner Institute of the Max Planck Society, Buenos Aires, Argentina
| | - Sergio A. Senin
- Instituto de Investigación en Biomedicina de Buenos Aires (IBioBA)-CONICET- Partner Institute of the Max Planck Society, Buenos Aires, Argentina
| | - Juan Gerez
- Instituto de Investigación en Biomedicina de Buenos Aires (IBioBA)-CONICET- Partner Institute of the Max Planck Society, Buenos Aires, Argentina
| | - Esteban Hoijman
- Centro de Microscopías Avanzadas, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Damian Refojo
- Max Planck Institute of Psychiatry, 80804, Munich, Germany
| | - Mišo Mitkovski
- Max Planck Institute of Experimental Medicine, 37075, Göttingen, Germany
| | | | - Walter Stühmer
- Max Planck Institute of Experimental Medicine, 37075, Göttingen, Germany
| | - Florian Holsboer
- Max Planck Institute of Psychiatry, 80804, Munich, Germany
- HMNC Brain Health, Munich, Germany
| | | | - Eduardo Arzt
- Instituto de Investigación en Biomedicina de Buenos Aires (IBioBA)-CONICET- Partner Institute of the Max Planck Society, Buenos Aires, Argentina
- Departamento de Fisiología y Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
- Max Planck Institute of Psychiatry, 80804, Munich, Germany
- * E-mail:
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27
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Stephan G, Kowalski-Jahn M, Zens C, Schmalzing G, Illes P, Hausmann R. Inter-subunit disulfide locking of the human P2X3 receptor elucidates ectodomain movements associated with channel gating. Purinergic Signal 2016; 12:221-33. [PMID: 26825305 DOI: 10.1007/s11302-016-9496-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2015] [Accepted: 01/19/2016] [Indexed: 11/27/2022] Open
Abstract
P2X3 receptors (P2X3R) are trimeric ATP-gated cation channels involved in sensory neurotransmission and inflammatory pain. We used homology modeling and molecular dynamic simulations of the hP2X3R to identify inter-subunit interactions of residues that are instrumental to elucidate conformational changes associated with gating of the hPX3R. We identified an ionic interaction between E112 and R198 of the head domain and dorsal fin domain, respectively, and E57 and T263 of the lower body domains of adjacent subunits and detected a marked rearrangement of these domains during gating of the hP3X3R. Double-mutant cycle analysis of the inter-subunit residue pairs E112/R198 and E57/T263 revealed significant interaction-free energies. Disulfide locking of the hP2X3R E112C/R198C or the E57C/T263C double cysteine mutants markedly reduced the ATP-induced current responses. The decreased current amplitude following inter-subunit disulfide cross-linking indicates that disulfide locking of the head and dorsal fin domains or at the level of the lower body domains of the hP2X3R prevents the gating-induced conformational rearrangement of the subunits with respect to each other. The distinct reorganization of the subunit interfaces during gating of the hP2X3R is generally consistent with the gating mechanism of other P2XRs. Charge-reversal mutagenesis and methanethiosulfonate (MTS)-modification of substituted cysteines demonstrated that E112 and R198 interact electrostatically. Both disulfide locking and salt bridge breaking of the E112/R198 interaction reduced the hP2X3R function. We conclude that the inter-subunit salt bridge between E112 and R198 of the head and dorsal fin domains, respectively, serves to control the mobility of these domains during agonist-activation of the hP2X3R.
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Affiliation(s)
- Gabriele Stephan
- Rudolf Boehm Institute of Pharmacology and Toxicology, University of Leipzig, Haertelstrasse 16-18, 04107, Leipzig, Germany
| | - Maria Kowalski-Jahn
- Rudolf Boehm Institute of Pharmacology and Toxicology, University of Leipzig, Haertelstrasse 16-18, 04107, Leipzig, Germany
| | - Christopher Zens
- Rudolf Boehm Institute of Pharmacology and Toxicology, University of Leipzig, Haertelstrasse 16-18, 04107, Leipzig, Germany
| | - Günther Schmalzing
- Department of Molecular Pharmacology, RWTH Aachen University, Wendlingweg 2, 52074, Aachen, Germany
| | - Peter Illes
- Rudolf Boehm Institute of Pharmacology and Toxicology, University of Leipzig, Haertelstrasse 16-18, 04107, Leipzig, Germany.
| | - Ralf Hausmann
- Department of Molecular Pharmacology, RWTH Aachen University, Wendlingweg 2, 52074, Aachen, Germany.
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28
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Habermacher C, Martz A, Calimet N, Lemoine D, Peverini L, Specht A, Cecchini M, Grutter T. Photo-switchable tweezers illuminate pore-opening motions of an ATP-gated P2X ion channel. eLife 2016; 5:e11050. [PMID: 26808983 PMCID: PMC4739762 DOI: 10.7554/elife.11050] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2015] [Accepted: 10/27/2015] [Indexed: 11/13/2022] Open
Abstract
P2X receptors function by opening a transmembrane pore in response to extracellular ATP. Recent crystal structures solved in apo and ATP-bound states revealed molecular motions of the extracellular domain following agonist binding. However, the mechanism of pore opening still remains controversial. Here we use photo-switchable cross-linkers as ‘molecular tweezers’ to monitor a series of inter-residue distances in the transmembrane domain of the P2X2 receptor during activation. These experimentally based structural constraints combined with computational studies provide high-resolution models of the channel in the open and closed states. We show that the extent of the outer pore expansion is significantly reduced compared to the ATP-bound structure. Our data further reveal that the inner and outer ends of adjacent pore-lining helices come closer during opening, likely through a hinge-bending motion. These results provide new insight into the gating mechanism of P2X receptors and establish a versatile strategy applicable to other membrane proteins. DOI:http://dx.doi.org/10.7554/eLife.11050.001 Protein receptors in the cell membrane play an important role transmitting signals from outside to inside the cell. Members of the P2X family of receptors are ion channels that form pores through the membrane. When a molecule of ATP binds to the external region of the receptor, it activates it and causes the receptor to change from a closed to an open shape. Once opened, ions flow through the channel’s pore and trigger a response inside the cell. P2X receptors are found on most animal cells (including nerve cells) and are involved in both normal cellular activity and processes linked to disease, including inflammation and chronic pain. The P2X receptor has three parts or subunits, and each contributes to the channel’s pore. Recent research using a technique called X-ray crystallography has revealed how ATP binding causes shape changes in the external region of the receptor. But these three-dimensional structures did not reveal details of how the subunits move to open or close the channel’s pore. Habermacher et al. have now added light-sensitive linkers onto the P2X receptor in a way that meant that different colors of light could be used to force parts of the receptor to come closer together or move apart. This allowed the pore to be opened and closed in response to changes in light. Habermacher et al. then studied the behavior of these modified receptors within a natural membrane and found that the light stimulated movements were similar to those seen with ATP. When the behavior of the receptor and light-sensitive linkers was studied using computer simulations, it led to new models of the P2X pore in the open and closed state. In these models, the open channel was more tightly packed than in the previous structure and an unexpected hinge-bending movement was seen to accompany the opening of the channel. It is hoped that this new approach will also be useful for probing how other membrane proteins change their shape when activated. DOI:http://dx.doi.org/10.7554/eLife.11050.002
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Affiliation(s)
- Chloé Habermacher
- Université de Strasbourg, Faculté de Pharmacie, Illkirch, France.,Centre National de la Recherche Scientifique, Laboratoire de Conception et Application de Molécules Bioactives, Unité Mixte de Recherche 7199, Équipe de Chimie et Neurobiologie Moléculaire, Illkirch, France
| | - Adeline Martz
- Université de Strasbourg, Faculté de Pharmacie, Illkirch, France.,Centre National de la Recherche Scientifique, Laboratoire de Conception et Application de Molécules Bioactives, Unité Mixte de Recherche 7199, Équipe de Chimie et Neurobiologie Moléculaire, Illkirch, France
| | - Nicolas Calimet
- ISIS, Unité Mixte de Recherche 7006, Laboratoire d'Ingénierie des Fonctions Moléculaires, Strasbourg, France
| | - Damien Lemoine
- Université de Strasbourg, Faculté de Pharmacie, Illkirch, France.,Centre National de la Recherche Scientifique, Laboratoire de Conception et Application de Molécules Bioactives, Unité Mixte de Recherche 7199, Équipe de Chimie et Neurobiologie Moléculaire, Illkirch, France
| | - Laurie Peverini
- Université de Strasbourg, Faculté de Pharmacie, Illkirch, France.,Centre National de la Recherche Scientifique, Laboratoire de Conception et Application de Molécules Bioactives, Unité Mixte de Recherche 7199, Équipe de Chimie et Neurobiologie Moléculaire, Illkirch, France
| | - Alexandre Specht
- Université de Strasbourg, Faculté de Pharmacie, Illkirch, France.,Centre National de la Recherche Scientifique, Laboratoire de Conception et Application de Molécules Bioactives, Unité Mixte de Recherche 7199, Équipe de Chimie et Neurobiologie Moléculaire, Illkirch, France
| | - Marco Cecchini
- ISIS, Unité Mixte de Recherche 7006, Laboratoire d'Ingénierie des Fonctions Moléculaires, Strasbourg, France
| | - Thomas Grutter
- Université de Strasbourg, Faculté de Pharmacie, Illkirch, France.,Centre National de la Recherche Scientifique, Laboratoire de Conception et Application de Molécules Bioactives, Unité Mixte de Recherche 7199, Équipe de Chimie et Neurobiologie Moléculaire, Illkirch, France
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29
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Insights into the channel gating of P2X receptors from structures, dynamics and small molecules. Acta Pharmacol Sin 2016; 37:44-55. [PMID: 26725734 DOI: 10.1038/aps.2015.127] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2015] [Accepted: 11/02/2015] [Indexed: 12/16/2022] Open
Abstract
P2X receptors, as ATP-gated non-selective trimeric ion channels, are permeable to Na(+), K(+) and Ca(2+). Comparing with other ligand-gated ion channel families, P2X receptors are distinct in their unique gating properties and pathophysiological roles, and have attracted attention as promising drug targets for a variety of diseases, such as neuropathic pain, multiple sclerosis, rheumatoid arthritis and thrombus. Several small molecule inhibitors for distinct P2X subtypes have entered into clinical trials. However, many questions regarding the gating mechanism of P2X remain unsolved. The structural determinations of P2X receptors at the resting and ATP-bound open states revealed that P2X receptor gating is a cooperative allosteric process involving multiple domains, which marks the beginning of the post-structure era of P2X research at atomic level. Here, we review the current knowledge on the structure-function relationship of P2X receptors, depict the whole picture of allosteric changes during the channel gating, and summarize the active sites that may contribute to new strategies for developing novel allosteric drugs targeting P2X receptors.
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30
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Morton-Jones RT, Vlajkovic SM, Thorne PR, Cockayne DA, Ryan AF, Housley GD. Properties of ATP-gated ion channels assembled from P2X2 subunits in mouse cochlear Reissner's membrane epithelial cells. Purinergic Signal 2015; 11:551-60. [PMID: 26424615 DOI: 10.1007/s11302-015-9473-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2015] [Accepted: 09/16/2015] [Indexed: 12/26/2022] Open
Abstract
In the cochlea, Reissner's membrane separates the scala media endolymphatic compartment that sustains the positive endocochlear potential and ion composition necessary for sound transduction, from the scala vestibuli perilymphatic compartment. It is known that with sustained elevated sound levels, adenosine 5'-triphosphate (ATP) is released into the endolymph and ATP-gated ion channels on the epithelial cells lining the endolymphatic compartment shunt the electrochemical driving force, contributing to protective purinergic hearing adaptation. This study characterises the properties of epithelial cell P2X(2)-type ATP-activated membrane conductance in the mouse Reissner's membrane, which forms a substantial fraction of the scale media surface. The cells were found to express two isoforms (a and b) of the P2X(2) subunit arising from alternative splicing of the messenger RNA (mRNA) transcript that could contribute to the trimeric subunit assembly. The ATP-activated conductance demonstrated both immediate and delayed desensitisation consistent with incorporation of the combination of P2X(2) subunit isoforms. Activation by the ATP analogue 2meSATP had equipotency to ATP, whereas α,β-meATP and adenosine 5'-diphosphate (ADP) were ineffective. Positive allosteric modulation of the P2X(2) channels by protons was profound. This native conductance was blocked by the P2X(2)-selective blocker pyridoxal-phosphate-6-azophenyl-2',4'-disulphonic acid (PPADS) and the conductance was absent in these cells isolated from mice null for the P2rX2 gene encoding the P2X(2) receptor subunit. The activation and desensitisation properties of the Reissner's membrane epithelial cell ATP-gated P2X(2) channels likely contribute to the sensitivity and kinetics of purinergic control of the electrochemical driving force for sound transduction invoked by noise exposure.
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Affiliation(s)
| | - Srdjan M Vlajkovic
- Department of Physiology, University of Auckland, Auckland, New Zealand.,Centre for Brain Research, School of Medical Sciences, University of Auckland, Auckland, New Zealand
| | - Peter R Thorne
- Department of Physiology, University of Auckland, Auckland, New Zealand.,Centre for Brain Research, School of Medical Sciences, University of Auckland, Auckland, New Zealand.,Section of Audiology, School of Population Health, University of Auckland, Private Bag 92019, Auckland, New Zealand
| | | | - Allen F Ryan
- Departments of Surgery and Neurosciences, VA Medical Center, University of California San Diego, La Jolla, CA, 92037, USA
| | - Gary D Housley
- Translational Neuroscience Facility and Department of Physiology, School of Medical Sciences, UNSW Australia, Sydney, NSW, 2052, Australia.
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31
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Habermacher C, Dunning K, Chataigneau T, Grutter T. Molecular structure and function of P2X receptors. Neuropharmacology 2015; 104:18-30. [PMID: 26231831 DOI: 10.1016/j.neuropharm.2015.07.032] [Citation(s) in RCA: 79] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2015] [Revised: 07/23/2015] [Accepted: 07/26/2015] [Indexed: 12/22/2022]
Abstract
ATP-gated P2X receptors are trimeric ion channels selective to cations. Recent progress in the molecular biophysics of these channels enables a better understanding of their function. In particular, data obtained from biochemical, electrophysiogical and molecular engineering in the light of recent X-ray structures now allow delineation of the principles of ligand binding, channel opening and allosteric modulation. However, although a picture emerges as to how ATP triggers channel opening, there are a number of intriguing questions that remain to be answered, in particular how the pore itself opens in response to ATP and how the intracellular domain, for which structural information is limited, moves during activation. In this review, we provide a summary of functional studies in the context of the post-structure era, aiming to clarify our understanding of the way in which P2X receptors function in response to ATP binding, as well as the mechanism by which allosteric modulators are able to regulate receptor function. This article is part of the Special Issue entitled 'Purines in Neurodegeneration and Neuroregeneration'.
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Affiliation(s)
- Chloé Habermacher
- Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7199, Laboratoire de Conception et Application de Molécules Bioactives, Équipe de Chimie et Neurobiologie Moléculaire, F-67400, Illkirch, France; Université de Strasbourg, Faculté de Pharmacie, F-67400, Illkirch, France
| | - Kate Dunning
- Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7199, Laboratoire de Conception et Application de Molécules Bioactives, Équipe de Chimie et Neurobiologie Moléculaire, F-67400, Illkirch, France; Université de Strasbourg, Faculté de Pharmacie, F-67400, Illkirch, France
| | - Thierry Chataigneau
- Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7199, Laboratoire de Conception et Application de Molécules Bioactives, Équipe de Chimie et Neurobiologie Moléculaire, F-67400, Illkirch, France; Université de Strasbourg, Faculté de Pharmacie, F-67400, Illkirch, France
| | - Thomas Grutter
- Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7199, Laboratoire de Conception et Application de Molécules Bioactives, Équipe de Chimie et Neurobiologie Moléculaire, F-67400, Illkirch, France; Université de Strasbourg, Faculté de Pharmacie, F-67400, Illkirch, France.
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32
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Kowalski M, Hausmann R, Schmid J, Dopychai A, Stephan G, Tang Y, Schmalzing G, Illes P, Rubini P. Flexible subunit stoichiometry of functional human P2X2/3 heteromeric receptors. Neuropharmacology 2015; 99:115-30. [PMID: 26184350 DOI: 10.1016/j.neuropharm.2015.07.008] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2015] [Revised: 07/01/2015] [Accepted: 07/09/2015] [Indexed: 11/27/2022]
Abstract
The aim of the present work was to clarify whether heterotrimeric P2X2/3 receptors have a fixed subunit stoichiometry consisting of one P2X2 and two P2X3 subunits as previously suggested, or a flexible stoichiometry containing also the inverse subunit composition. For this purpose we transfected HEK293 cells with P2X2 and P2X3 encoding cDNA at the ratios of 1:2 and 4:1, and analysed the biophysical and pharmacological properties of the generated receptors by means of the whole-cell patch-clamp technique. The concentration-response curves for the selective agonist α,β-meATP did not differ from each other under the two transfection ratios. However, co-expression of an inactive P2X2 mutant and the wild type P2X3 subunit and vice versa resulted in characteristic distortions of the α,β-meATP concentration-response relationships, depending on which subunit was expressed in excess, suggesting that HEK293 cells express mixtures of (P2X2)1/(P2X3)2 and (P2X2)2/(P2X3)1 receptors. Whereas the allosteric modulators H+ and Zn2+ failed to discriminate between the two possible heterotrimeric receptor variants, the α,β-meATP-induced responses were blocked more potently by the competitive antagonist A317491, when the P2X2 subunit was expressed in deficit of the P2X3 subunit. Furthermore, blue-native PAGE analysis of P2X2 and P2X3 subunits co-expressed in Xenopus laevis oocytes and HEK293 cells revealed that plasma membrane-bound P2X2/3 receptors appeared in two clearly distinct heterotrimeric complexes: a (P2X2-GFP)2/(P2X3)1 complex and a (P2X2-GFP)1/(P2X3)2 complex. These data strongly indicate that the stoichiometry of the heteromeric P2X2/3 receptor is not fixed, but determined in a permutational manner by the relative availability of P2X2 and P2X3 subunits.
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Affiliation(s)
- Maria Kowalski
- Rudolf-Boehm-Institute of Pharmacology and Toxicology, University of Leipzig, 04107 Leipzig, Germany
| | - Ralf Hausmann
- Molecular Pharmacology, RWTH Aachen University, 52074 Aachen, Germany
| | - Julia Schmid
- Rudolf-Boehm-Institute of Pharmacology and Toxicology, University of Leipzig, 04107 Leipzig, Germany
| | - Anke Dopychai
- Molecular Pharmacology, RWTH Aachen University, 52074 Aachen, Germany
| | - Gabriele Stephan
- Rudolf-Boehm-Institute of Pharmacology and Toxicology, University of Leipzig, 04107 Leipzig, Germany
| | - Yong Tang
- Acupuncture and Tuina School, Chengdu University of Traditional Chinese Medicine, 610075 Chengdu, China
| | | | - Peter Illes
- Rudolf-Boehm-Institute of Pharmacology and Toxicology, University of Leipzig, 04107 Leipzig, Germany
| | - Patrizia Rubini
- Rudolf-Boehm-Institute of Pharmacology and Toxicology, University of Leipzig, 04107 Leipzig, Germany.
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33
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Kwon TH, Jung H, Cho EJ, Jeong JH, Sohn UD. The Signaling Mechanism of Contraction Induced by ATP and UTP in Feline Esophageal Smooth Muscle Cells. Mol Cells 2015; 38:616-23. [PMID: 26013385 PMCID: PMC4507027 DOI: 10.14348/molcells.2015.2357] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2014] [Revised: 04/07/2015] [Accepted: 04/16/2015] [Indexed: 11/29/2022] Open
Abstract
P2 receptors are membrane-bound receptors for extracellular nucleotides such as ATP and UTP. P2 receptors have been classified as ligand-gated ion channels or P2X receptors and G protein-coupled P2Y receptors. Recently, purinergic signaling has begun to attract attention as a potential therapeutic target for a variety of diseases especially associated with gastroenterology. This study determined the ATP and UTP-induced receptor signaling mechanism in feline esophageal contraction. Contraction of dispersed feline esophageal smooth muscle cells was measured by scanning micrometry. Phosphorylation of MLC20 was determined by western blot analysis. ATP and UTP elicited maximum esophageal contraction at 30 s and 10 μM concentration. Contraction of dispersed cells treated with 10 μM ATP was inhibited by nifedipine. However, contraction induced by 0.1 μM ATP, 0.1 μM UTP and 10 μM UTP was decreased by U73122, chelerythrine, ML-9, PTX and GDPβS. Contraction induced by 0.1 μM ATP and UTP was inhibited by Gαi3 or Gαq antibodies and by PLCβ1 or PLCβ3 antibodies. Phosphorylated MLC20 was increased by ATP and UTP treatment. In conclusion, esophageal contraction induced by ATP and UTP was preferentially mediated by P2Y receptors coupled to Gαi3 and G q proteins, which activate PLCβ1 and PLCβ3. Subsequently, increased intracellular Ca(2+) and activated PKC triggered stimulation of MLC kinase and inhibition of MLC phosphatase. Finally, increased pMLC20 generated esophageal contraction.
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Affiliation(s)
- Tae Hoon Kwon
- Department of Pharmacology, College of Pharmacy, Chung-Ang University, Seoul 156-756,
Korea
| | - Hyunwoo Jung
- Department of Pharmacology, College of Pharmacy, Chung-Ang University, Seoul 156-756,
Korea
| | - Eun Jeong Cho
- Department of Pharmacology, College of Pharmacy, Chung-Ang University, Seoul 156-756,
Korea
| | - Ji Hoon Jeong
- Department of Pharmacology, College of Medicine, Chung-Ang University, Seoul 156-756,
Korea
| | - Uy Dong Sohn
- Department of Pharmacology, College of Pharmacy, Chung-Ang University, Seoul 156-756,
Korea
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Abstract
There are nineteen different receptor proteins for adenosine, adenine and uridine nucleotides, and nucleotide sugars, belonging to three families of G protein-coupled adenosine and P2Y receptors, and ionotropic P2X receptors. The majority are functionally expressed in blood vessels, as purinergic receptors in perivascular nerves, smooth muscle and endothelial cells, and roles in regulation of vascular contractility, immune function and growth have been identified. The endogenous ligands for purine receptors, ATP, ADP, UTP, UDP and adenosine, can be released from different cell types within the vasculature, as well as from circulating blood cells, including erythrocytes and platelets. Many purine receptors can be activated by two or more of the endogenous ligands. Further complexity arises because of interconversion between ligands, notably adenosine formation from the metabolism of ATP, leading to complex integrated responses through activation of different subtypes of purine receptors. The enzymes responsible for this conversion, ectonucleotidases, are present on the surface of smooth muscle and endothelial cells, and may be coreleased with neurotransmitters from nerves. What selectivity there is for the actions of purines/pyrimidines comes from differential expression of their receptors within the vasculature. P2X1 receptors mediate the vasocontractile actions of ATP released as a neurotransmitter with noradrenaline (NA) from sympathetic perivascular nerves, and are located on the vascular smooth muscle adjacent to the nerve varicosities, the sites of neurotransmitter release. The relative contribution of ATP and NA as functional cotransmitters varies with species, type and size of blood vessel, neuronal firing pattern, the tone/pressure of the blood vessel, and in ageing and disease. ATP is also a neurotransmitter in non-adrenergic non-cholinergic perivascular nerves and mediates vasorelaxation via smooth muscle P2Y-like receptors. ATP and adenosine can act as neuromodulators, with the most robust evidence being for prejunctional inhibition of neurotransmission via A1 adenosine receptors, but also prejunctional excitation and inhibition of neurotransmission via P2X and P2Y receptors, respectively. P2Y2, P2Y4 and P2Y6 receptors expressed on the vascular smooth muscle are coupled to vasocontraction, and may have a role in pathophysiological conditions, when purines are released from damaged cells, or when there is damage to the protective barrier that is the endothelium. Adenosine is released during hypoxia to increase blood flow via vasodilator A2A and A2B receptors expressed on the endothelium and smooth muscle. ATP is released from endothelial cells during hypoxia and shear stress and can act at P2Y and P2X4 receptors expressed on the endothelium to increase local blood flow. Activation of endothelial purine receptors leads to the release of nitric oxide, hyperpolarising factors and prostacyclin, which inhibits platelet aggregation and thus ensures patent blood flow. Vascular purine receptors also regulate endothelial and smooth muscle growth, and inflammation, and thus are involved in the underlying processes of a number of cardiovascular diseases.
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Affiliation(s)
- Vera Ralevic
- School of Life Sciences, Queen's Medical Centre, University of Nottingham, Nottingham NG7 2UH, United Kingdom.
| | - William R Dunn
- School of Life Sciences, Queen's Medical Centre, University of Nottingham, Nottingham NG7 2UH, United Kingdom
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Pathophysiological role of extracellular purinergic mediators in the control of intestinal inflammation. Mediators Inflamm 2015; 2015:427125. [PMID: 25944982 PMCID: PMC4405224 DOI: 10.1155/2015/427125] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2014] [Accepted: 09/30/2014] [Indexed: 12/19/2022] Open
Abstract
Purinergic mediators such as adenosine 5′-triphosphate (ATP) are released into the extracellular compartment from damaged tissues and activated immune cells. They are then recognized by multiple purinergic P2X and P2Y receptors. Release and recognition of extracellular ATP are associated with both the development and the resolution of inflammation and infection. Accumulating evidence has recently suggested the potential of purinergic receptors as novel targets for drugs for treating intestinal disorders, including intestinal inflammation and irritable bowel syndrome. In this review, we highlight recent findings regarding the pathophysiological role of purinergic mediators in the development of intestinal inflammation.
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Ase AR, Honson NS, Zaghdane H, Pfeifer TA, Séguéla P. Identification and characterization of a selective allosteric antagonist of human P2X4 receptor channels. Mol Pharmacol 2015; 87:606-16. [PMID: 25597706 DOI: 10.1124/mol.114.096222] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
P2X4 is an ATP-gated nonselective cation channel highly permeable to calcium. There is increasing evidence that this homomeric purinoceptor, which is expressed in several neuronal and immune cell types, is involved in chronic pain and inflammation. The current paucity of unambiguous pharmacological tools available to interrogate or modulate P2X4 function led us to pursue the search for selective antagonists. In the high-throughput screen of a compound library, we identified the phenylurea BX430 (1-(2,6-dibromo-4-isopropyl-phenyl)-3-(3-pyridyl)urea, molecular weight = 413), with antagonist properties on human P2X4-mediated calcium uptake. Patch-clamp electrophysiology confirmed direct inhibition of P2X4 currents by extracellular BX430, with submicromolar potency (IC50 = 0.54 µM). BX430 is highly selective, having virtually no functional impact on all other P2X subtypes, namely, P2X1-P2X3, P2X5, and P2X7, at 10-100 times its IC50. Unexpected species differences were noticed, as BX430 is a potent antagonist of zebrafish P2X4 but has no effect on rat and mouse P2X4 orthologs. The concentration-response curve for ATP on human P2X4 in the presence of BX430 shows an insurmountable blockade, indicating a noncompetitive allosteric mechanism of action. Using a fluorescent dye uptake assay, we observed that BX430 also effectively suppresses ATP-evoked and ivermectin-potentiated membrane permeabilization induced by P2X4 pore dilation. Finally, in single-cell calcium imaging, we validated its selective inhibitory effects on native P2X4 channels at the surface of human THP-1 cells that were differentiated into macrophages. In summary, this ligand provides a novel molecular probe to assess the specific role of P2X4 in inflammatory and neuropathic conditions, where ATP signaling has been shown to be dysfunctional.
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Affiliation(s)
- Ariel R Ase
- Montreal Neurological Institute, Alan Edwards Centre for Research on Pain, Department of Neurology and Neurosurgery, McGill University, Montreal, Canada (A.R.A., P.S.); Screening Division, The Centre for Drug Research and Discovery, Vancouver, Canada (N.S.H., T.A.P.); and Zamboni Chemical Solutions, Department of Chemistry, McGill University, Montreal, Canada (H.Z.)
| | - Nicolette S Honson
- Montreal Neurological Institute, Alan Edwards Centre for Research on Pain, Department of Neurology and Neurosurgery, McGill University, Montreal, Canada (A.R.A., P.S.); Screening Division, The Centre for Drug Research and Discovery, Vancouver, Canada (N.S.H., T.A.P.); and Zamboni Chemical Solutions, Department of Chemistry, McGill University, Montreal, Canada (H.Z.)
| | - Helmi Zaghdane
- Montreal Neurological Institute, Alan Edwards Centre for Research on Pain, Department of Neurology and Neurosurgery, McGill University, Montreal, Canada (A.R.A., P.S.); Screening Division, The Centre for Drug Research and Discovery, Vancouver, Canada (N.S.H., T.A.P.); and Zamboni Chemical Solutions, Department of Chemistry, McGill University, Montreal, Canada (H.Z.)
| | - Tom A Pfeifer
- Montreal Neurological Institute, Alan Edwards Centre for Research on Pain, Department of Neurology and Neurosurgery, McGill University, Montreal, Canada (A.R.A., P.S.); Screening Division, The Centre for Drug Research and Discovery, Vancouver, Canada (N.S.H., T.A.P.); and Zamboni Chemical Solutions, Department of Chemistry, McGill University, Montreal, Canada (H.Z.)
| | - Philippe Séguéla
- Montreal Neurological Institute, Alan Edwards Centre for Research on Pain, Department of Neurology and Neurosurgery, McGill University, Montreal, Canada (A.R.A., P.S.); Screening Division, The Centre for Drug Research and Discovery, Vancouver, Canada (N.S.H., T.A.P.); and Zamboni Chemical Solutions, Department of Chemistry, McGill University, Montreal, Canada (H.Z.)
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Roger S, Jelassi B, Couillin I, Pelegrin P, Besson P, Jiang LH. Understanding the roles of the P2X7 receptor in solid tumour progression and therapeutic perspectives. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2014; 1848:2584-602. [PMID: 25450340 DOI: 10.1016/j.bbamem.2014.10.029] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2014] [Revised: 10/13/2014] [Accepted: 10/20/2014] [Indexed: 01/05/2023]
Abstract
P2X7 is an intriguing ionotropic receptor for which the activation by extracellular ATP induces rapid inward cationic currents and intracellular signalling pathways associated with numerous physiological processes such as the induction of the inflammatory cascade, the survival and proliferation of cells. In contrast, long-term stimulation of P2X7 is generally associated with membrane permeabilisation and cell death. Recently, P2X7 has attracted great attention in the cancer field, and particularly in the neoplastic transformation and the progression of solid tumours. A growing number of studies were published; however they often appeared contradictory in their results and conclusions. As such, the involvement of P2X7 in the oncogenic process remains unclear so far. The present review aims to discuss the current knowledge and hypotheses on the involvement of the P2X7 receptor in the development and progression of solid tumours, and highlight the different aspects that require further clarification in order to decipher whether P2X7 could be considered as a cancer biomarker or as a target for pharmacological intervention. This article is part of a Special Issue entitled: Membrane channels and transporters in cancers.
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Affiliation(s)
- Sébastien Roger
- Inserm UMR1069 Nutrition, Croissance et Cancer, Université François-Rabelais de Tours, 10 Boulevard Tonnellé, 37032 Tours, France; Département de Physiologie Animale, UFR Sciences et Techniques, Université François-Rabelais de Tours, Avenue Monge, 37200 Tours, France.
| | - Bilel Jelassi
- Inserm UMR1069 Nutrition, Croissance et Cancer, Université François-Rabelais de Tours, 10 Boulevard Tonnellé, 37032 Tours, France
| | - Isabelle Couillin
- UMR CNRS 7355 Experimental and Molecular Immunology and Neurogenetics, Université d'Orléans, 3B rue de la Ferollerie, F-45071 Orléans, France
| | - Pablo Pelegrin
- Inflammation and Experimental Surgery Research Unit, CIBERehd, Clinical University Hospital "Virgen de la Arrixaca", Murcia's BioHealth Research Institute IMIB-Arrixaca, Carretera Cartagena-Madrid s/n, 30120 Murcia, Spain
| | - Pierre Besson
- Inserm UMR1069 Nutrition, Croissance et Cancer, Université François-Rabelais de Tours, 10 Boulevard Tonnellé, 37032 Tours, France
| | - Lin-Hua Jiang
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, United Kingdom
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38
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Alexander SPH, Benson HE, Faccenda E, Pawson AJ, Sharman JL, Spedding M, Peters JA, Harmar AJ. The Concise Guide to PHARMACOLOGY 2013/14: ligand-gated ion channels. Br J Pharmacol 2014; 170:1582-606. [PMID: 24528238 PMCID: PMC3892288 DOI: 10.1111/bph.12446] [Citation(s) in RCA: 113] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The Concise Guide to PHARMACOLOGY 2013/14 provides concise overviews of the key properties of over 2000 human drug targets with their pharmacology, plus links to an open access knowledgebase of drug targets and their ligands (www.guidetopharmacology.org), which provides more detailed views of target and ligand properties. The full contents can be found at http://onlinelibrary.wiley.com/doi/10.1111/bph.12444/full. Ligand-gated ion channels are one of the seven major pharmacological targets into which the Guide is divided, with the others being G protein-coupled receptors, ion channels, catalytic receptors, nuclear hormone receptors, transporters and enzymes. These are presented with nomenclature guidance and summary information on the best available pharmacological tools, alongside key references and suggestions for further reading. A new landscape format has easy to use tables comparing related targets. It is a condensed version of material contemporary to late 2013, which is presented in greater detail and constantly updated on the website www.guidetopharmacology.org, superseding data presented in previous Guides to Receptors and Channels. It is produced in conjunction with NC-IUPHAR and provides the official IUPHAR classification and nomenclature for human drug targets, where appropriate. It consolidates information previously curated and displayed separately in IUPHAR-DB and the Guide to Receptors and Channels, providing a permanent, citable, point-in-time record that will survive database updates.
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Affiliation(s)
- Stephen P H Alexander
- School of Life Sciences, University of Nottingham Medical School, Nottingham, NG7 2UH, UK
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Abramowski P, Ogrodowczyk C, Martin R, Pongs O. A truncation variant of the cation channel P2RX5 is upregulated during T cell activation. PLoS One 2014; 9:e104692. [PMID: 25181038 PMCID: PMC4152149 DOI: 10.1371/journal.pone.0104692] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2014] [Accepted: 07/10/2014] [Indexed: 01/11/2023] Open
Abstract
Members of the P2X family of ligand-gated cation channels (P2RX) are expressed by various cell types including neurons, smooth- and cardiac muscle cells, and leukocytes. The channels mediate signalling in response to extracellular ATP. Seven subunit isoforms (P2RX1-P2RX7) have been identified and these can assemble as homo- and heterotrimeric molecules. In humans, P2RX5 exists as a natural deletion mutant lacking amino acids 328–349 of exon 10, which are part of transmembrane (TM) 2 and pre-TM2 regions in other organisms like rat, chicken and zebrafish. We show that P2RX5 gene expression of human T lymphocytes is upregulated during activation. P2RX5 is recruited to the cell surface. P2RX5-siRNA-transfected CD4+ T cells produced twofold more IL-10 than controls. Surface and intracellular P2RX5 expression was upregulated in activated antigen-specific CD4+ T cell clones. These data indicate a functional role of the human P2RX5 splice variant in T cell activation and immunoregulation.
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Affiliation(s)
- Pierre Abramowski
- Institute for Neuroimmunology and Clinical Multiple Sclerosis Research (inims), ZMNH, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
- Research Department Cell and Gene Therapy, Clinic for Stem Cell Transplantation, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Christoph Ogrodowczyk
- Institute for Neural Signaltransduction, ZMNH, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Roland Martin
- Institute for Neuroimmunology and Clinical Multiple Sclerosis Research (inims), ZMNH, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
- Neuroimmunology and MS Research, Department of Neurology, University Hospital Zurich, Zurich, Switzerland
- * E-mail:
| | - Olaf Pongs
- Institute for Neural Signaltransduction, ZMNH, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
- Institute for Physiology, University Hospital Homburg, Homburg/Saar, Germany
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40
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Wang WS, Tu WZ, Cheng RD, He R, Ruan LH, Zhang L, Gong YS, Fan XF, Hu J, Cheng B, Lai YP, Zou EM, Jiang SH. Electroacupuncture and A-317491 depress the transmission of pain on primary afferent mediated by the P2X3 receptor in rats with chronic neuropathic pain states. J Neurosci Res 2014; 92:1703-13. [PMID: 25041872 DOI: 10.1002/jnr.23451] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2013] [Revised: 06/04/2014] [Accepted: 06/10/2014] [Indexed: 12/14/2022]
Abstract
P2X is a family of ligand-gated ion channels that act through adenosine ATP. The P2X3 receptor plays a key role in the transmission of neuropathic pain at peripheral and spinal sites. Electroacupuncture (EA) has been used to treat neuropathic pain effectively. To determine the role of EA in neuropathic pain mediated through the P2X3 receptor in dorsal root ganglion neurons and the spinal cord, a chronic constriction injury (CCI) model was used. Sprague-Dawley rats were divided into four groups: sham CCI, CCI, CCI plus contralateral EA, and CCI plus ipsilateral EA. The mechanical withdrawal threshold (MWT) and thermal withdrawal latency (TWL) were recorded. Furthermore, the expression of the P2X3 receptor was evaluated through Western blotting and immunofluorescence. The effects of EA and A-317491 were investigated through the whole-cell patch-clamp method and intrathecal administration. Our results show that the MWT and TWL of EA groups were higher than those in the CCI group, whereas the expression of the P2X3 receptor was lower than that in the CCI group. However, no significant difference was detected between the two EA groups. EA depressed the currents created by ATP and the upregulation of the P2X3 receptor in CCI rats. Additionally, EA was more potent in reducing mechanical allodynia and thermal hyperalgesia when combined with A-317491 through intrathecal administration. These results show that both contralateral and ipsilateral EA might inhibit the primary afferent transmission of neuropathic pain induced through the P2X3 receptor. In addition, EA and A-317491 might have an additive effect in inhibiting the transmission of pain mediated by the P2X3 receptor.
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Affiliation(s)
- Wan-Sheng Wang
- Department of Physical Medicine and Rehabilitation, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, China
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41
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Zhao WS, Wang J, Ma XJ, Yang Y, Liu Y, Huang LD, Fan YZ, Cheng XY, Chen HZ, Wang R, Yu Y. Relative motions between left flipper and dorsal fin domains favour P2X4 receptor activation. Nat Commun 2014; 5:4189. [PMID: 24943126 DOI: 10.1038/ncomms5189] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2014] [Accepted: 05/22/2014] [Indexed: 01/09/2023] Open
Abstract
Channel gating in response to extracellular ATP is a fundamental process for the physiological functions of P2X receptors. Here we identify coordinated allosteric changes in the left flipper (LF) and dorsal fin (DF) domains that couple ATP-binding to channel gating. Engineered disulphide crosslinking or zinc bridges between the LF and DF domains that constrain their relative motions significantly influence channel gating of P2X4 receptors, confirming the essential role of these allosteric changes. ATP-binding-induced alterations in interdomain hydrophobic interactions among I208, L217, V291 and the aliphatic chain of K193 correlate well with these coordinated relative movements. Mutations on those four residues lead to impaired or fully abolished channel activations of P2X4 receptors. Our data reveal that ATP-binding-induced altered interdomain hydrophobic interactions and the concomitant coordinated motions of LF and DF domains are allosteric events essential for the channel gating of P2X4 receptors.
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Affiliation(s)
- Wen-Shan Zhao
- 1] Institute of Medical Sciences and Department of Pharmacology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China [2] Key Laboratory of Preclinical Study for New Drugs of Gansu Province, School of Basic Medical Sciences, Lanzhou University, Lanzhou 730000, China [3]
| | - Jin Wang
- 1] Institute of Medical Sciences and Department of Pharmacology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China [2]
| | - Xiao-Juan Ma
- 1] Institute of Medical Sciences and Department of Pharmacology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China [2] Key Laboratory of Preclinical Study for New Drugs of Gansu Province, School of Basic Medical Sciences, Lanzhou University, Lanzhou 730000, China [3]
| | - Yang Yang
- Institute of Medical Sciences and Department of Pharmacology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Yan Liu
- Institute of Medical Sciences and Department of Pharmacology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Li-Dong Huang
- Institute of Medical Sciences and Department of Pharmacology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Ying-Zhe Fan
- Putuo District Center Hospital, Shanghai University of Chinese Traditional Medicine, Shanghai 200062, China
| | - Xiao-Yang Cheng
- Institute of Medical Sciences and Department of Pharmacology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Hong-Zhuan Chen
- Institute of Medical Sciences and Department of Pharmacology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Rui Wang
- Key Laboratory of Preclinical Study for New Drugs of Gansu Province, School of Basic Medical Sciences, Lanzhou University, Lanzhou 730000, China
| | - Ye Yu
- 1] Institute of Medical Sciences and Department of Pharmacology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China [2] College of Bioscience and Biotechnology, Hunan Agricultural University, Changsha 410128, China
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42
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Kellenberger S, Grutter T. Architectural and functional similarities between trimeric ATP-gated P2X receptors and acid-sensing ion channels. J Mol Biol 2014; 427:54-66. [PMID: 24937752 DOI: 10.1016/j.jmb.2014.06.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2014] [Revised: 06/05/2014] [Accepted: 06/09/2014] [Indexed: 12/17/2022]
Abstract
ATP-gated P2X receptors and acid-sensing ion channels are two distinct ligand-gated ion channels that assemble into trimers. They are involved in many important physiological functions such as pain sensation and are recognized as important therapeutic targets. They have unrelated primary structures and respond to different ligands (ATP and protons) and are thus considered as two different ion channels. As a consequence, comparisons of the biophysical properties and underlying mechanisms have only been rarely made between these two channels. However, the recent determination of their molecular structures by X-ray crystallography has revealed unexpected parallels in the architecture of the two pores, providing a basis for possible functional analogies. In this review, we analyze the structural and functional similarities that are shared by these trimeric ion channels, and we outline key unanswered questions that, if addressed experimentally, may help us to elucidate how two unrelated ion channels have adopted a similar fold of the pore.
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Affiliation(s)
- Stephan Kellenberger
- Département de Pharmacologie et de Toxicologie, Université de Lausanne, Rue du Bugnon 27, CH-1005 Lausanne, Switzerland.
| | - Thomas Grutter
- Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7199, Laboratoire de Conception et Application de Molécules Bioactives, Équipe de Chimie et Neurobiologie Moléculaire, F-67400 Illkirch, France; Université de Strasbourg, Faculté de Pharmacie, F-67400 Illkirch, France.
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43
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Antonio LS, Stewart AP, Varanda WA, Edwardson JM. Identification of P2X2/P2X4/P2X6 heterotrimeric receptors using atomic force microscopy (AFM) imaging. FEBS Lett 2014; 588:2125-8. [PMID: 24815693 DOI: 10.1016/j.febslet.2014.04.048] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2014] [Accepted: 04/22/2014] [Indexed: 10/25/2022]
Abstract
Seven P2X purinergic receptor subunits have been identified: P2X1-P2X7. The overlapping expression of P2X2, P2X4 and P2X6 subunits has been shown in different cell types, and functional analysis of P2X receptors in Leydig cells suggests that the three subunits might interact. Here, His6-tagged P2X2, HA-tagged P2X4 and FLAG-tagged P2X6 subunits were co-expressed in tsA 201 cells. After sequential co-immunoprecipitation using anti-HA and anti-FLAG beads, all three subunits were present, demonstrating their interaction. Atomic force microscopy (AFM) imaging revealed receptors that were specifically decorated by both an anti-His6 antibody and an anti-HA Fab fragment, indicating the presence of a P2X2/4/6 heterotrimer. To our knowledge, this is the first report of a P2X receptor containing three different subunits.
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Affiliation(s)
- Ligia S Antonio
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, United Kingdom; Department of Physiology, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, São Paulo, Brazil
| | - Andrew P Stewart
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, United Kingdom
| | - Wamberto A Varanda
- Department of Physiology, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, São Paulo, Brazil
| | - J Michael Edwardson
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, United Kingdom.
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Expression of P2X3 and P2X5 Myenteric Receptors Varies During the Intestinal Postnatal Development in the Guinea Pig. Cell Mol Neurobiol 2014; 34:727-36. [DOI: 10.1007/s10571-014-0055-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2014] [Accepted: 03/25/2014] [Indexed: 12/22/2022]
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45
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Stelmashenko O, Compan V, Browne LE, North RA. Ectodomain movements of an ATP-gated ion channel (P2X2 receptor) probed by disulfide locking. J Biol Chem 2014; 289:9909-17. [PMID: 24515105 PMCID: PMC3975035 DOI: 10.1074/jbc.m113.542811] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The ectodomain of the P2X receptor is formed mainly from two- or three-stranded β-sheets provided symmetrically by each of the three subunits. These enclose a central cavity that is closed off furthest from the plasma membrane (the turret) and that joins with the transmembrane helices to form the ion permeation pathway. Comparison of closed and open crystal structures indicates that ATP binds in a pocket positioned between strands provided by different subunits and that this flexes the β-sheets of the lower body and enlarges the central cavity: this pulls apart the outer ends of the transmembrane helices and thereby opens an aperture, or gate, where they intersect within the membrane bilayer. In the present work, we examined this opening model by introducing pairs of cysteines into the rat P2X2 receptor that might form disulfide bonds within or between subunits. Receptors were expressed in human embryonic kidney cells, and disulfide formation was assessed by observing the effect of dithiothreitol on currents evoked by ATP. Substitutions in the turret (P90C, P89C/S97C), body wall (S65C/S190C, S65C/D315C) and the transmembrane domains (V48C/I328C, V51C/I328C, S54C/I328C) strongly inhibited ATP-evoked currents prior to reduction with dithiothreitol. Western blotting showed that these channels also formed predominately as dimers and/or trimers rather than monomers. The results strongly support the channel opening mechanism proposed on the basis of available crystal structures.
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Optical control of trimeric P2X receptors and acid-sensing ion channels. Proc Natl Acad Sci U S A 2013; 111:521-6. [PMID: 24367083 DOI: 10.1073/pnas.1318582111] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
P2X receptors are trimeric membrane proteins that function as ion channels gated by extracellular ATP. We have engineered a P2X2 receptor that opens within milliseconds by irradiation at 440 nm, and rapidly closes at 360 nm. This requires bridging receptor subunits via covalent attachment of 4,4'-bis(maleimido)azobenzene to a cysteine residue (P329C) introduced into each second transmembrane domain. The cis-trans isomerization of the azobenzene pushes apart the outer ends of the transmembrane helices and opens the channel in a light-dependent manner. Light-activated channels exhibited similar unitary currents, rectification, calcium permeability, and dye uptake as P2X2 receptors activated by ATP. P2X3 receptors with an equivalent mutation (P320C) were also light sensitive after chemical modification. They showed typical rapid desensitization, and they could coassemble with native P2X2 subunits in pheochromocytoma cells to form light-activated heteromeric P2X2/3 receptors. A similar approach was used to open and close human acid-sensing ion channels (ASICs), which are also trimers but are unrelated in sequence to P2X receptors. The experiments indicate that the opening of the permeation pathway requires similar and substantial movements of the transmembrane helices in both P2X receptors and ASICs, and the method will allow precise optical control of P2X receptors or ASICs in intact tissues.
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Subtype-specific control of P2X receptor channel signaling by ATP and Mg2+. Proc Natl Acad Sci U S A 2013; 110:E3455-63. [PMID: 23959888 DOI: 10.1073/pnas.1308088110] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The identity and forms of activating ligands for ion channels are fundamental to their physiological roles in rapid electrical signaling. P2X receptor channels are ATP-activated cation channels that serve important roles in sensory signaling and inflammation, yet the active forms of the nucleotide are unknown. In physiological solutions, ATP is ionized and primarily found in complex with Mg(2+). Here we investigated the active forms of ATP and found that the action of MgATP(2-) and ATP(4-) differs between subtypes of P2X receptors. The slowly desensitizing P2X2 receptor can be activated by free ATP, but MgATP(2-) promotes opening with very low efficacy. In contrast, both free ATP and MgATP(2-) robustly open the rapidly desensitizing P2X3 subtype. A further distinction between these two subtypes is the ability of Mg(2+) to regulate P2X3 through a distinct allosteric mechanism. Importantly, heteromeric P2X2/3 channels present in sensory neurons exhibit a hybrid phenotype, characterized by robust activation by MgATP(2-) and weak regulation by Mg(2+). These results reveal the existence of two classes of homomeric P2X receptors with differential sensitivity to MgATP(2-) and regulation by Mg(2+), and demonstrate that both restraining mechanisms can be disengaged in heteromeric channels to form fast and sensitive ATP signaling pathways in sensory neurons.
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Liang X, Xu H, Li C, Yin S, Xu T, Liu J, Li Z. Functional identification of close proximity amino acid side chains within the transmembrane-spanning helixes of the P2X2 receptor. PLoS One 2013; 8:e70629. [PMID: 23936459 PMCID: PMC3735612 DOI: 10.1371/journal.pone.0070629] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2013] [Accepted: 06/20/2013] [Indexed: 01/15/2023] Open
Abstract
The transition from the closed to open state greatly alters the intra- and inter-subunit interactions of the P2X receptor (P2XR). The interactions that occur in the transmembrane domain of the P2X2R remain unclear. We used substituted cysteine mutagenesis disulfide mapping to identify pairs of residues that are in close proximity within the transmembrane domain of rP2X2R and compared our results to the predicted positions of these amino acids obtained from a rat P2X2R homology model of the available open and closed zebrafish P2X4R structures. Alternations in channel function were measured as a change in the ATP-gated current before and after exposure to dithiothreitol. Thirty-six pairs of double mutants of rP2X2R expressed in HEK293 cells produced normal functioning channels. Thirty-five pairs of these mutants did not exhibit a functionally detectable disulfide bond. The double mutant H33C/S345C formed redox-dependent cross-links in the absence of ATP. Dithiothreitol ruptured the disulfide bond of H33C/S345C and induced a 2 to 3-fold increase in current. The EC50 for H33C/S345C before dithiothreitol treatment was ∼2-fold higher than that after dithiothreitol treatment. Dithiothreitol reduced the EC50 to wild-type levels. Furthermore, expression of trimeric concatamer receptors with Cys mutations at some but not all six positions showed that the more disulfide bond formation sites within the concatamer, the greater current potentiation after dithiothreitol incubation. Immunoblot analysis of H33C/S345C revealed one monomer band under nonreducing conditions strongly suggesting that disulfide bonds are formed within single subunits (intra-subunit) and not between two subunits (inter-subunit). Taken together, these data indicate that His33 and Ser345 are proximal to each other across an intra-subunit interface. The relative movement between the first transmembrane and the second transmembrane in the intra-subunit is likely important for transmitting the action of ATP binding to the opening of the channel.
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Affiliation(s)
- Xin Liang
- Key Laboratory of Regenerative Biology, South China Institute for Stem Cell Biology and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, University of Chinese Academy of Sciences, Guangzhou, Guangdong, China
| | - Huijuan Xu
- Key Laboratory of Regenerative Biology, South China Institute for Stem Cell Biology and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, University of Chinese Academy of Sciences, Guangzhou, Guangdong, China
| | - Caiyue Li
- Key Laboratory of Regenerative Biology, South China Institute for Stem Cell Biology and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, University of Chinese Academy of Sciences, Guangzhou, Guangdong, China
| | - Shikui Yin
- The School of Life Science, University of Science and Technology of China, Hefei, Anhui, China
| | - Tingting Xu
- State Key Laboratory of Respiratory Disease, Guangzhou Institutes of Biomedicine and Health, University of Chinese Academy of Sciences, Guangzhou, Guangdong, China
| | - Jinsong Liu
- State Key Laboratory of Respiratory Disease, Guangzhou Institutes of Biomedicine and Health, University of Chinese Academy of Sciences, Guangzhou, Guangdong, China
| | - Zhiyuan Li
- Key Laboratory of Regenerative Biology, South China Institute for Stem Cell Biology and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, University of Chinese Academy of Sciences, Guangzhou, Guangdong, China
- * E-mail:
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Cysteine-based cross-linking approach to study inter-domain interactions in ion channels. Methods Mol Biol 2013. [PMID: 23529437 DOI: 10.1007/978-1-62703-351-0_21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/16/2023]
Abstract
Cysteine contains a highly reactive thiol group and therefore under oxidizing conditions a disulfide bond can form between a pair of cysteines that are juxtaposed in the close vicinity, which can be only reversed by reducing agents. These attributes have been elegantly exploited to study the functional role of an interaction or contact between two adjacent domains that are present in ion channels or virtually in any proteins, by introducing double cysteine substitutions at the domain interface and measuring changes in the ion channel functions arising from cross-linking the two substituted cysteines via formation of a disulfide bond. Here I describe this cysteine-based cross-linking approach.
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50
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Mutation of the ATP-gated P2X(2) receptor leads to progressive hearing loss and increased susceptibility to noise. Proc Natl Acad Sci U S A 2013; 110:2228-33. [PMID: 23345450 DOI: 10.1073/pnas.1222285110] [Citation(s) in RCA: 104] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Age-related hearing loss and noise-induced hearing loss are major causes of human morbidity. Here we used genetics and functional studies to show that a shared cause of these disorders may be loss of function of the ATP-gated P2X(2) receptor (ligand-gated ion channel, purinergic receptor 2) that is expressed in sensory and supporting cells of the cochlea. Genomic analysis of dominantly inherited, progressive sensorineural hearing loss DFNA41 in a six-generation kindred revealed a rare heterozygous allele, P2RX2 c.178G > T (p.V60L), at chr12:133,196,029, which cosegregated with fully penetrant hearing loss in the index family, and also appeared in a second family with the same phenotype. The mutation was absent from more than 7,000 controls. P2RX2 p.V60L abolishes two hallmark features of P2X(2) receptors: ATP-evoked inward current response and ATP-stimulated macropore permeability, measured as loss of ATP-activated FM1-43 fluorescence labeling. Coexpression of mutant and WT P2X(2) receptor subunits significantly reduced ATP-activated membrane permeability. P2RX2-null mice developed severe progressive hearing loss, and their early exposure to continuous moderate noise led to high-frequency hearing loss as young adults. Similarly, among family members heterozygous for P2RX2 p.V60L, noise exposure exacerbated high-frequency hearing loss in young adulthood. Our results suggest that P2X(2) function is required for life-long normal hearing and for protection from exposure to noise.
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