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Huffer K, Tan XF, Fernández-Mariño AI, Dhingra S, Swartz KJ. Dilation of ion selectivity filters in cation channels. Trends Biochem Sci 2024; 49:417-430. [PMID: 38514273 PMCID: PMC11069442 DOI: 10.1016/j.tibs.2024.02.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2023] [Revised: 02/19/2024] [Accepted: 02/23/2024] [Indexed: 03/23/2024]
Abstract
Ion channels establish the voltage gradient across cellular membranes by providing aqueous pathways for ions to selectively diffuse down their concentration gradients. The selectivity of any given channel for its favored ions has conventionally been viewed as a stable property, and in many cation channels, it is determined by an ion-selectivity filter within the external end of the ion-permeation pathway. In several instances, including voltage-activated K+ (Kv) channels, ATP-activated P2X receptor channels, and transient receptor potential (TRP) channels, the ion-permeation pathways have been proposed to dilate in response to persistent activation, dynamically altering ion permeation. Here, we discuss evidence for dynamic ion selectivity, examples where ion selectivity filters exhibit structural plasticity, and opportunities to fill gaps in our current understanding.
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Affiliation(s)
- Kate Huffer
- Molecular Physiology and Biophysics Section, Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
| | - Xiao-Feng Tan
- Molecular Physiology and Biophysics Section, Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
| | - Ana I Fernández-Mariño
- Molecular Physiology and Biophysics Section, Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
| | - Surbhi Dhingra
- Molecular Physiology and Biophysics Section, Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
| | - Kenton J Swartz
- Molecular Physiology and Biophysics Section, Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA.
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2
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Kaur J, Dora S. Purinergic signaling: Diverse effects and therapeutic potential in cancer. Front Oncol 2023; 13:1058371. [PMID: 36741002 PMCID: PMC9889871 DOI: 10.3389/fonc.2023.1058371] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Accepted: 01/02/2023] [Indexed: 01/19/2023] Open
Abstract
Regardless of improved biological insights and therapeutic advances, cancer is consuming multiple lives worldwide. Cancer is a complex disease with diverse cellular, metabolic, and physiological parameters as its hallmarks. This instigates a need to uncover the latest therapeutic targets to advance the treatment of cancer patients. Purines are building blocks of nucleic acids but also function as metabolic intermediates and messengers, as part of a signaling pathway known as purinergic signaling. Purinergic signaling comprises primarily adenosine triphosphate (ATP) and adenosine (ADO), their analogous membrane receptors, and a set of ectonucleotidases, and has both short- and long-term (trophic) effects. Cells release ATP and ADO to modulate cellular function in an autocrine or paracrine manner by activating membrane-localized purinergic receptors (purinoceptors, P1 and P2). P1 receptors are selective for ADO and have four recognized subtypes-A1, A2A, A2B, and A3. Purines and pyrimidines activate P2 receptors, and the P2X subtype is ligand-gated ion channel receptors. P2X has seven subtypes (P2X1-7) and forms homo- and heterotrimers. The P2Y subtype is a G protein-coupled receptor with eight subtypes (P2Y1/2/4/6/11/12/13/14). ATP, its derivatives, and purinoceptors are widely distributed in all cell types for cellular communication, and any imbalance compromises the homeostasis of the cell. Neurotransmission, neuromodulation, and secretion employ fast purinergic signaling, while trophic purinergic signaling regulates cell metabolism, proliferation, differentiation, survival, migration, invasion, and immune response during tumor progression. Thus, purinergic signaling is a prospective therapeutic target in cancer and therapy resistance.
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Affiliation(s)
- Jasmeet Kaur
- Department of Biophysics, Postgraduate Institute of Medical Education and Research (PGIMER), Chandigarh, India
| | - Sanchit Dora
- Department of Biophysics, Postgraduate Institute of Medical Education and Research (PGIMER), Chandigarh, India
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3
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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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4
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He X, Zhang Y, Xu Y, Xie L, Yu Z, Zheng J. Function of the P2X7 receptor in hematopoiesis and leukemogenesis. Exp Hematol 2021; 104:40-47. [PMID: 34687808 DOI: 10.1016/j.exphem.2021.10.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Revised: 10/04/2021] [Accepted: 10/08/2021] [Indexed: 10/20/2022]
Abstract
Adenosine triphosphate (ATP) accumulates at tissue injury and inflammation sites. The P2X7 receptor is an ATP-gated ion channel known for its cytotoxic activity. However, P2X7 receptors also play important roles in the growth of cancer and the immune regulation. Functional P2X7 receptor is widely expressed in murine and human hematopoietic stem cells and their lineages, including monocytes, macrophages, mast cells, and B or T lymphocytes, and participates in various physiological and pathologic activities. Therefore, it is not surprising that the P2X7 receptor is important for the normal hematopoiesis and leukemogenesis. Here, we summarize the biological functions of P2X7 receptor during both normal hematopoiesis and leukemogenesis. In particular, we found that ATP levels are dramatically increased in the leukemic bone marrow niche and the fates of leukemia-initiating cells of acute myeloid leukemia are tightly controlled by P2X7 expression and ATP-P2X7-mediated signaling pathways. These findings strongly indicate that the P2X7 receptor may be considered a potential biomarker of hematological malignancies in bone marrow niches, and its antagonists may be useful for the leukemia treatment in addition to the traditional chemotherapy.
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Affiliation(s)
- Xiaoxiao He
- Hongqiao International Institute of Medicine, Shanghai Tongren Hospital, Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Faculty of Basic Medicine, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
| | - Yaping Zhang
- Hongqiao International Institute of Medicine, Shanghai Tongren Hospital, Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Faculty of Basic Medicine, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Yilu Xu
- Hongqiao International Institute of Medicine, Shanghai Tongren Hospital, Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Faculty of Basic Medicine, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Li Xie
- Hongqiao International Institute of Medicine, Shanghai Tongren Hospital, Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Faculty of Basic Medicine, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Zhuo Yu
- Hongqiao International Institute of Medicine, Shanghai Tongren Hospital, Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Faculty of Basic Medicine, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Junke Zheng
- Hongqiao International Institute of Medicine, Shanghai Tongren Hospital, Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Faculty of Basic Medicine, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
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5
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Inoue H, Kuroda H, Ofusa W, Oyama S, Kimura M, Ichinohe T, Shibukawa Y. Functional Coupling between the P2X 7 Receptor and Pannexin-1 Channel in Rat Trigeminal Ganglion Neurons. Int J Mol Sci 2021; 22:ijms22115978. [PMID: 34205953 PMCID: PMC8198496 DOI: 10.3390/ijms22115978] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Revised: 05/19/2021] [Accepted: 05/27/2021] [Indexed: 11/16/2022] Open
Abstract
The ionotropic P2X receptor, P2X7, is believed to regulate and/or generate nociceptive pain, and pain in several neuropathological diseases. Although there is a known relationship between P2X7 receptor activity and pain sensing, its detailed functional properties in trigeminal ganglion (TG) neurons remains unclear. We examined the electrophysiological and pharmacological characteristics of the P2X7 receptor and its functional coupling with other P2X receptors and pannexin-1 (PANX1) channels in primary cultured rat TG neurons, using whole-cell patch-clamp recordings. Application of ATP and Bz-ATP induced long-lasting biphasic inward currents that were more sensitive to extracellular Bz-ATP than ATP, indicating that the current was carried by P2X7 receptors. While the biphasic current densities of the first and second components were increased by Bz-ATP in a concentration dependent manner; current duration was only affected in the second component. These currents were significantly inhibited by P2X7 receptor antagonists, while only the second component was inhibited by P2X1, 3, and 4 receptor antagonists, PANX1 channel inhibitors, and extracellular ATPase. Taken together, our data suggests that autocrine or paracrine signaling via the P2X7-PANX1-P2X receptor/channel complex may play important roles in several pain sensing pathways via long-lasting neuronal activity driven by extracellular high-concentration ATP following tissue damage in the orofacial area.
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Affiliation(s)
- Hiroyuki Inoue
- Department of Physiology, Tokyo Dental College, Tokyo 101-0061, Japan; (H.I.); (H.K.); (W.O.); (S.O.); (M.K.)
- Department of Dental Anesthesiology, Tokyo Dental College, Tokyo 101-0061, Japan;
| | - Hidetaka Kuroda
- Department of Physiology, Tokyo Dental College, Tokyo 101-0061, Japan; (H.I.); (H.K.); (W.O.); (S.O.); (M.K.)
- Department of Dental Anesthesiology, Kanagawa Dental University, Kanagawa 238-8580, Japan
| | - Wataru Ofusa
- Department of Physiology, Tokyo Dental College, Tokyo 101-0061, Japan; (H.I.); (H.K.); (W.O.); (S.O.); (M.K.)
| | - Sadao Oyama
- Department of Physiology, Tokyo Dental College, Tokyo 101-0061, Japan; (H.I.); (H.K.); (W.O.); (S.O.); (M.K.)
| | - Maki Kimura
- Department of Physiology, Tokyo Dental College, Tokyo 101-0061, Japan; (H.I.); (H.K.); (W.O.); (S.O.); (M.K.)
| | - Tatsuya Ichinohe
- Department of Dental Anesthesiology, Tokyo Dental College, Tokyo 101-0061, Japan;
| | - Yoshiyuki Shibukawa
- Department of Physiology, Tokyo Dental College, Tokyo 101-0061, Japan; (H.I.); (H.K.); (W.O.); (S.O.); (M.K.)
- Correspondence:
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6
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Filippin KJ, de Souza KFS, de Araujo Júnior RT, Torquato HFV, Dias DA, Parisotto EB, Ferreira AT, Paredes-Gamero EJ. Involvement of P2 receptors in hematopoiesis and hematopoietic disorders, and as pharmacological targets. Purinergic Signal 2020; 16:1-15. [PMID: 31863258 PMCID: PMC7166233 DOI: 10.1007/s11302-019-09684-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2019] [Accepted: 11/12/2019] [Indexed: 12/11/2022] Open
Abstract
Several reports have shown the presence of P2 receptors in hematopoietic stem cells (HSCs). These receptors are activated by extracellular nucleotides released from different sources. In the hematopoietic niche, the release of purines and pyrimidines in the milieu by lytic and nonlytic mechanisms has been described. The expression of P2 receptors from HSCs until maturity is still intriguing scientists. Several reports have shown the participation of P2 receptors in events associated with modulation of the immune system, but their participation in other physiological processes is under investigation. The presence of P2 receptors in HSCs and their ability to modulate this population have awakened interest in exploring the involvement of P2 receptors in hematopoiesis and their participation in hematopoietic disorders. Among the P2 receptors, the receptor P2X7 is of particular interest, because of its different roles in hematopoietic cells (e.g., infection, inflammation, cell death and survival, leukemias and lymphomas), making the P2X7 receptor a promising pharmacological target. Additionally, the role of P2Y12 receptor in platelet activation has been well-documented and is the main example of the importance of the pharmacological modulation of P2 receptor activity. In this review, we focus on the role of P2 receptors in the hematopoietic system, addressing these receptors as potential pharmacological targets.
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Affiliation(s)
- Kelly Juliana Filippin
- Faculdade de Ciências Farmacêuticas, Alimentos e Nutrição, Universidade Federal de Mato Grosso do Sul, Campo Grande, MS, 79070-900, Brazil
| | - Kamylla F S de Souza
- Departamento de Bioquímica, Universidade Federal de São Paulo, R. Três de Maio 100, São Paulo, SP, 04044-020, Brazil
| | | | - Heron Fernandes Vieira Torquato
- Departamento de Bioquímica, Universidade Federal de São Paulo, R. Três de Maio 100, São Paulo, SP, 04044-020, Brazil
- Universidade Braz Cubas, Av. Francisco Rodrigues Filho 1233, Mogi das Cruzes, SP, 08773-380, Brazil
| | - Dhébora Albuquerque Dias
- Faculdade de Ciências Farmacêuticas, Alimentos e Nutrição, Universidade Federal de Mato Grosso do Sul, Campo Grande, MS, 79070-900, Brazil
| | - Eduardo Benedetti Parisotto
- Faculdade de Ciências Farmacêuticas, Alimentos e Nutrição, Universidade Federal de Mato Grosso do Sul, Campo Grande, MS, 79070-900, Brazil
| | - Alice Teixeira Ferreira
- Departamento de Biofísica, Universidade Federal de São Paulo, R. Botucatu 862, São Paulo, SP, 04023-062, Brazil.
- Faculdade de Ciências Farmacêuticas, Alimentos e Nutrição (FACFAN), Laboratório de Biologia Molecular e Culturas Celulares, Av. Costa e Silva, s/n Bairro Universitário, Campo Grande, MS, CEP: 79070-900, Brazil.
| | - Edgar J Paredes-Gamero
- Faculdade de Ciências Farmacêuticas, Alimentos e Nutrição, Universidade Federal de Mato Grosso do Sul, Campo Grande, MS, 79070-900, Brazil.
- Departamento de Bioquímica, Universidade Federal de São Paulo, R. Três de Maio 100, São Paulo, SP, 04044-020, Brazil.
- Faculdade de Ciências Farmacêuticas, Alimentos e Nutrição (FACFAN), Laboratório de Biologia Molecular e Culturas Celulares, Av. Costa e Silva, s/n Bairro Universitário, Campo Grande, MS, CEP: 79070-900, Brazil.
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7
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McCarthy AE, Yoshioka C, Mansoor SE. Full-Length P2X 7 Structures Reveal How Palmitoylation Prevents Channel Desensitization. Cell 2019; 179:659-670.e13. [PMID: 31587896 DOI: 10.1016/j.cell.2019.09.017] [Citation(s) in RCA: 153] [Impact Index Per Article: 30.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2019] [Revised: 07/30/2019] [Accepted: 09/13/2019] [Indexed: 12/24/2022]
Abstract
P2X receptors are trimeric, non-selective cation channels activated by extracellular ATP. The P2X7 receptor subtype is a pharmacological target because of involvement in apoptotic, inflammatory, and tumor progression pathways. It is the most structurally and functionally distinct P2X subtype, containing a unique cytoplasmic domain critical for the receptor to initiate apoptosis and not undergo desensitization. However, lack of structural information about the cytoplasmic domain has hindered understanding of the molecular mechanisms underlying these processes. We report cryoelectron microscopy structures of full-length rat P2X7 receptor in apo and ATP-bound states. These structures reveal how one cytoplasmic element, the C-cys anchor, prevents desensitization by anchoring the pore-lining helix to the membrane with palmitoyl groups. They show a second cytoplasmic element with a unique fold, the cytoplasmic ballast, which unexpectedly contains a zinc ion complex and a guanosine nucleotide binding site. Our structures provide first insights into the architecture and function of a P2X receptor cytoplasmic domain.
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Affiliation(s)
- Alanna E McCarthy
- Vollum Institute, Oregon Health and Science University, Portland, OR 97239, USA; Knight Cardiovascular Institute, Oregon Health and Science University, Portland, OR 97239, USA
| | - Craig Yoshioka
- Department of Biomedical Engineering, Oregon Health and Science University, Portland, OR 97201, USA
| | - Steven E Mansoor
- Vollum Institute, Oregon Health and Science University, Portland, OR 97239, USA; Knight Cardiovascular Institute, Oregon Health and Science University, Portland, OR 97239, USA.
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8
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Abstract
Adenosine 5′-triphosphate acts as an extracellular signalling molecule (purinergic signalling), as well as an intracellular energy source. Adenosine 5′-triphosphate receptors have been cloned and characterised. P1 receptors are selective for adenosine, a breakdown product of adenosine 5′-triphosphate after degradation by ectonucleotidases. Four subtypes are recognised, A1, A2A, A2B and A3 receptors. P2 receptors are activated by purine and by pyrimidine nucleotides. P2X receptors are ligand-gated ion channel receptors (seven subunits (P2X1-7)), which form trimers as both homomultimers and heteromultimers. P2Y receptors are G protein-coupled receptors (eight subtypes (P2Y1/2/4/6/11/12/13/14)). There is both purinergic short-term signalling and long-term (trophic) signalling. The cloning of P2X-like receptors in primitive invertebrates suggests that adenosine 5′-triphosphate is an early evolutionary extracellular signalling molecule. Selective purinoceptor agonists and antagonists with therapeutic potential have been developed for a wide range of diseases, including thrombosis and stroke, dry eye, atherosclerosis, kidney failure, osteoporosis, bladder incontinence, colitis, neurodegenerative diseases and cancer.
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Affiliation(s)
- Geoffrey Burnstock
- Autonomic Neuroscience Centre, University College Medical School, London, UK.,Department of Pharmacology and Therapeutics, The University of Melbourne, Melbourne, VIC, Australia
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9
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Peverini L, Beudez J, Dunning K, Chataigneau T, Grutter T. New Insights Into Permeation of Large Cations Through ATP-Gated P2X Receptors. Front Mol Neurosci 2018; 11:265. [PMID: 30108481 PMCID: PMC6080412 DOI: 10.3389/fnmol.2018.00265] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Accepted: 07/13/2018] [Indexed: 11/28/2022] Open
Abstract
The permeability of large cations through the P2X pore has remained arguably the most controversial and complicated topic in P2X-related research, with the emergence of conflicting studies on the existence, mechanism and physiological relevance of a so-called “dilated” state. Due to the important role of several “dilating” P2X subtypes in numerous diseases, a clear and detailed understanding of this phenomenon represents a research priority. Recent advances, however, have challenged the existence of a progressive, ATP-induced pore dilation, by demonstrating that this phenomenon is an artifact of the method employed. Here, we discuss briefly the history of this controversial and enigmatic dilated state, from its initial discovery to its recent reconsideration. We will discuss the literature in which mechanistic pathways to a large cation-permeable state are proposed, as well as important advances in the methodology employed to study this elusive state. Considering recent literature, we will also open the discussion as to whether an intrinsically dilating P2X pore exists, as well as the physiological relevance of such a large cation-permeable pore and its potential use as therapeutic pathway.
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Affiliation(s)
- Laurie Peverini
- CNRS, CAMB UMR 7199, Équipe de Chimie et Neurobiologie Moléculaire, Université de Strasbourg, Strasbourg, France
| | - Juline Beudez
- CNRS, CAMB UMR 7199, Équipe de Chimie et Neurobiologie Moléculaire, Université de Strasbourg, Strasbourg, France
| | - Kate Dunning
- CNRS, CAMB UMR 7199, Équipe de Chimie et Neurobiologie Moléculaire, Université de Strasbourg, Strasbourg, France
| | - Thierry Chataigneau
- CNRS, CAMB UMR 7199, Équipe de Chimie et Neurobiologie Moléculaire, Université de Strasbourg, Strasbourg, France
| | - Thomas Grutter
- CNRS, CAMB UMR 7199, Équipe de Chimie et Neurobiologie Moléculaire, Université de Strasbourg, Strasbourg, France
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10
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Li S, Bjelobaba I, Stojilkovic SS. Interactions of Pannexin1 channels with purinergic and NMDA receptor channels. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2018; 1860:166-173. [PMID: 28389204 PMCID: PMC5628093 DOI: 10.1016/j.bbamem.2017.03.025] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/28/2016] [Revised: 03/28/2017] [Accepted: 03/29/2017] [Indexed: 12/31/2022]
Abstract
Pannexins are a three-member family of vertebrate plasma membrane spanning molecules that have homology to the invertebrate gap junction forming proteins, the innexins. However, pannexins do not form gap junctions but operate as plasma membrane channels. The best-characterized member of these proteins, Pannexin1 (Panx1) was suggested to be functionally associated with purinergic P2X and N-methyl-D-aspartate (NMDA) receptor channels. Activation of these receptor channels by their endogenous ligands leads to cross-activation of Panx1 channels. This in turn potentiates P2X and NMDA receptor channel signaling. Two potentiation concepts have been suggested: enhancement of the current responses and/or sustained receptor channel activation by ATP released through Panx1 pore and adenosine generated by ectonucleotidase-dependent dephosphorylation of ATP. Here we summarize the current knowledge and hypotheses about interactions of Panx1 channels with P2X and NMDA receptor channels. This article is part of a Special Issue entitled: Gap Junction Proteins edited by Jean Claude Herve.
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Affiliation(s)
- Shuo Li
- Tianjin Key Laboratory of Animal and Plant Resistance, College of Life Sciences, Tianjin Normal University, Tianjin 300387, China
| | - Ivana Bjelobaba
- Institute for Biological Research "Sinisa Stankovic", University of Belgrade, 11000 Belgrade, Serbia
| | - Stanko S Stojilkovic
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH, Bethesda, MD 20892, USA.
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11
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Nowodworska A, van den Maagdenberg AMJM, Nistri A, Fabbretti E. In situ imaging reveals properties of purinergic signalling in trigeminal sensory ganglia in vitro. Purinergic Signal 2017; 13:511-520. [PMID: 28822016 PMCID: PMC5714839 DOI: 10.1007/s11302-017-9576-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2017] [Accepted: 08/01/2017] [Indexed: 12/22/2022] Open
Abstract
Chronic pain is supported by sterile inflammation that induces sensitisation of sensory neurons to ambient stimuli including extracellular ATP acting on purinergic P2X receptors. The development of in vitro methods for drug screening would be useful to investigate cell crosstalk and plasticity mechanisms occurring during neuronal sensitisation and sterile neuroinflammation. Thus, we studied, at single-cell level, membrane pore dilation based on the uptake of a fluorescent probe following sustained ATP-gated P2X receptor function in neurons and non-neuronal cells of trigeminal ganglion cultures from wild-type (WT) and R192Q CaV2.1 knock-in (KI) mice, a model of familial hemiplegic migraine type 1 characterised by neuronal sensitisation and higher release of soluble mediators. In WT cultures, pore responses were mainly evoked by ATP rather than benzoyl-ATP (BzATP) and partly inhibited by the P2X antagonist TNP-ATP. P2X7 receptors were expressed in trigeminal ganglia mainly by non-neuronal cells. In contrast, KI cultures showed higher expression of P2X7 receptors, stronger responses to BzATP, an effect largely prevented by prior administration of CaV2.1 blocker ω-agatoxin IVA, small interfering RNA (siRNA)-based silencing of P2X7 receptors or the P2X7 antagonist A-804598. No cell toxicity was detected with the protocols. Calcitonin gene-related peptide (CGRP), a well-known migraine mediator, potentiated BzATP-evoked membrane permeability in WT as well as R192Q KI cultures, demonstrating its modulatory role on trigeminal sensory ganglia. Our results show an advantageous experimental approach to dissect pharmacological properties potentially relevant to chronic pain and suggest that CGRP is a soluble mediator influencing purinergic P2X pore dilation and regulating inflammatory responses.
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Affiliation(s)
- Arletta Nowodworska
- Neuroscience Department, International School for Advanced Studies (SISSA), Via Bonomea 265, 34136, Trieste, Italy
| | | | - Andrea Nistri
- Neuroscience Department, International School for Advanced Studies (SISSA), Via Bonomea 265, 34136, Trieste, Italy
| | - Elsa Fabbretti
- Center for Biomedical Sciences and Engineering, University of Nova Gorica, Vipavska 13, 5000, Nova Gorica, Slovenia.
- Department of Life Sciences, University of Trieste, via Giorgieri 5, 34127, Trieste, Italy.
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12
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Fenwick AJ, Fowler DK, Wu SW, Shaffer FJ, Lindberg JEM, Kinch DC, Peters JH. Direct Anandamide Activation of TRPV1 Produces Divergent Calcium and Current Responses. Front Mol Neurosci 2017; 10:200. [PMID: 28680392 PMCID: PMC5478686 DOI: 10.3389/fnmol.2017.00200] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2017] [Accepted: 06/07/2017] [Indexed: 01/22/2023] Open
Abstract
In the brainstem nucleus of the solitary tract (NTS), primary vagal afferent neurons express the transient receptor potential vanilloid subfamily member 1 (TRPV1) at their central terminals where it contributes to quantal forms of glutamate release. The endogenous membrane lipid anandamide (AEA) is a putative TRPV1 agonist in the brain, yet the extent to which AEA activation of TRPV1 has a neurophysiological consequence is not well established. We investigated the ability of AEA to activate TRPV1 in vagal afferent neurons in comparison to capsaicin (CAP). Using ratiometric calcium imaging and whole-cell patch clamp recordings we confirmed that AEA excitatory activity requires TRPV1, binds competitively at the CAP binding site, and has low relative affinity. While AEA-induced increases in peak cytosolic calcium were similar to CAP, AEA-induced membrane currents were significantly smaller. Removal of bath calcium increased the AEA current with no change in peak CAP currents revealing a calcium sensitive difference in specific ligand activation of TRPV1. Both CAP- and AEA-activated TRPV1 currents maintained identical reversal potentials, arguing against a major difference in ion selectivity to resolve the AEA differences in signaling. In contrast with CAP, AEA did not alter spontaneous glutamate release at NTS synapses. We conclude: (1) AEA activation of TRPV1 is markedly different from CAP and produces different magnitudes of calcium influx from whole-cell current; and (2) exogenous AEA does not alter spontaneous glutamate release onto NTS neurons. As such, AEA may convey modulatory changes to calcium-dependent processes, but does not directly facilitate glutamate release.
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Affiliation(s)
- Axel J Fenwick
- Department of Integrative Physiology and Neuroscience, Washington State UniversityPullman, WA, United States
| | - Daniel K Fowler
- Department of Integrative Physiology and Neuroscience, Washington State UniversityPullman, WA, United States
| | - Shaw-Wen Wu
- Department of Integrative Physiology and Neuroscience, Washington State UniversityPullman, WA, United States
| | - Forrest J Shaffer
- Department of Integrative Physiology and Neuroscience, Washington State UniversityPullman, WA, United States
| | - Jonathan E M Lindberg
- Department of Integrative Physiology and Neuroscience, Washington State UniversityPullman, WA, United States
| | - Dallas C Kinch
- Department of Integrative Physiology and Neuroscience, Washington State UniversityPullman, WA, United States
| | - James H Peters
- Department of Integrative Physiology and Neuroscience, Washington State UniversityPullman, WA, United States
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13
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On the permeation of large organic cations through the pore of ATP-gated P2X receptors. Proc Natl Acad Sci U S A 2017; 114:E3786-E3795. [PMID: 28442564 DOI: 10.1073/pnas.1701379114] [Citation(s) in RCA: 72] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Pore dilation is thought to be a hallmark of purinergic P2X receptors. The most commonly held view of this unusual process posits that under prolonged ATP exposure the ion pore expands in a striking manner from an initial small-cation conductive state to a dilated state, which allows the passage of larger synthetic cations, such as N-methyl-d-glucamine (NMDG+). However, this mechanism is controversial, and the identity of the natural large permeating cations remains elusive. Here, we provide evidence that, contrary to the time-dependent pore dilation model, ATP binding opens an NMDG+-permeable channel within milliseconds, with a conductance that remains stable over time. We show that the time course of NMDG+ permeability superimposes that of Na+ and demonstrate that the molecular motions leading to the permeation of NMDG+ are very similar to those that drive Na+ flow. We found, however, that NMDG+ "percolates" 10 times slower than Na+ in the open state, likely due to a conformational and orientational selection of permeating molecules. We further uncover that several P2X receptors, including those able to desensitize, are permeable not only to NMDG+ but also to spermidine, a large natural cation involved in ion channel modulation, revealing a previously unrecognized P2X-mediated signaling. Altogether, our data do not support a time-dependent dilation of the pore on its own but rather reveal that the open pore of P2X receptors is wide enough to allow the permeation of large organic cations, including natural ones. This permeation mechanism has considerable physiological significance.
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14
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Pettengill MA, Abdul-Sater A, Coutinho-Silva R, Ojcius DM. Danger signals, inflammasomes, and the intricate intracellular lives of chlamydiae. Biomed J 2016; 39:306-315. [PMID: 27884377 PMCID: PMC6138786 DOI: 10.1016/j.bj.2016.07.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2016] [Accepted: 07/13/2016] [Indexed: 12/20/2022] Open
Abstract
Chlamydiae are obligate intracellular bacterial pathogens, and as such are sensitive to alterations in the cellular physiology of their hosts. Chlamydial infections often cause pathologic consequences due to prolonged localized inflammation. Considerable advances have been made in the last few years regarding our understanding of how two key inflammation-associated signaling pathways influence the biology of Chlamydia infections: inflammation regulating purinergic signaling pathways significantly impact intracellular chlamydial development, and inflammasome activation modulates both chlamydial growth and infection mediated pro-inflammatory cytokine production. We review here elements of both pathways, presenting the latest developments contributing to our understanding of how chlamydial infections are influenced by inflammasomes and purinergic signaling.
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Affiliation(s)
| | - Ali Abdul-Sater
- School of Kinesiology and Health Science, York University, Toronto, Ontario, Canada
| | - Robson Coutinho-Silva
- Laboratory of Immunophysiology, Carlos Chagas Filho Biophysics Institute of the Federal University of Rio de Janeiro, Brazil
| | - David M Ojcius
- Laboratory of Immunophysiology, Carlos Chagas Filho Biophysics Institute of the Federal University of Rio de Janeiro, Brazil; Department of Biomedical Sciences, University of the Pacific, Arthur Dugoni School of Dentistry, San Francisco, USA.
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15
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Migita K, Ozaki T, Shimoyama S, Yamada J, Nikaido Y, Furukawa T, Shiba Y, Egan TM, Ueno S. HSP90 Regulation of P2X7 Receptor Function Requires an Intact Cytoplasmic C-Terminus. Mol Pharmacol 2016; 90:116-26. [PMID: 27301716 PMCID: PMC11037447 DOI: 10.1124/mol.115.102988] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2016] [Accepted: 06/10/2016] [Indexed: 12/19/2022] Open
Abstract
P2X7 receptors (P2X7Rs) are ATP-gated ion channels that display the unusual property of current facilitation during long applications of agonists. Here we show that facilitation disappears in chimeric P2X7Rs containing the C-terminus of the P2X2 receptor (P2X2R), and in a truncated P2X7R missing the cysteine-rich domain of the C-terminus. The chimeric and truncated receptors also show an apparent decreased permeability to N-methyl-d-glucamine(+) (NMDG(+)). The effects of genetic modification of the C-terminus on NMDG(+) permeability were mimicked by preapplication of the HSP90 antagonist geldanamycin to the wild-type receptor. Further, the geldanamycin decreased the shift in the reversal potential of the ATP-gated current measured under bi-ionic NMDG(+)/Na(+) condition without affecting the ability of the long application of agonist to facilitate current amplitude. Taken together, the results suggest that HSP90 may be essential for stabilization and function of P2X7Rs through an action on the cysteine-rich domain of the cytoplasmic the C-terminus.
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Affiliation(s)
- Keisuke Migita
- Department of Drug Informatics, Faculty of Pharmaceutical Sciences, Fukuoka University, Fukuoka, Japan (K.M.); Department of Neurophysiology (T.O., S.S., Y.N., T.F., Y.S., S.U.) and Research Center for Child Mental Development (T.O., S.S., S.U.), Hirosaki University Graduate School of Medicine, Hirosaki, Aomori, Japan; Department of Biomedical Sciences, Hirosaki University Graduate School of Health Sciences, Hirosaki, Aomori, Japan (J.Y.); and Department of Pharmacology and Physiology, and The Center for Neuroscience, Saint Louis University School of Medicine, St. Louis, Missouri (T.M.E.)
| | - Taku Ozaki
- Department of Drug Informatics, Faculty of Pharmaceutical Sciences, Fukuoka University, Fukuoka, Japan (K.M.); Department of Neurophysiology (T.O., S.S., Y.N., T.F., Y.S., S.U.) and Research Center for Child Mental Development (T.O., S.S., S.U.), Hirosaki University Graduate School of Medicine, Hirosaki, Aomori, Japan; Department of Biomedical Sciences, Hirosaki University Graduate School of Health Sciences, Hirosaki, Aomori, Japan (J.Y.); and Department of Pharmacology and Physiology, and The Center for Neuroscience, Saint Louis University School of Medicine, St. Louis, Missouri (T.M.E.)
| | - Shuji Shimoyama
- Department of Drug Informatics, Faculty of Pharmaceutical Sciences, Fukuoka University, Fukuoka, Japan (K.M.); Department of Neurophysiology (T.O., S.S., Y.N., T.F., Y.S., S.U.) and Research Center for Child Mental Development (T.O., S.S., S.U.), Hirosaki University Graduate School of Medicine, Hirosaki, Aomori, Japan; Department of Biomedical Sciences, Hirosaki University Graduate School of Health Sciences, Hirosaki, Aomori, Japan (J.Y.); and Department of Pharmacology and Physiology, and The Center for Neuroscience, Saint Louis University School of Medicine, St. Louis, Missouri (T.M.E.)
| | - Junko Yamada
- Department of Drug Informatics, Faculty of Pharmaceutical Sciences, Fukuoka University, Fukuoka, Japan (K.M.); Department of Neurophysiology (T.O., S.S., Y.N., T.F., Y.S., S.U.) and Research Center for Child Mental Development (T.O., S.S., S.U.), Hirosaki University Graduate School of Medicine, Hirosaki, Aomori, Japan; Department of Biomedical Sciences, Hirosaki University Graduate School of Health Sciences, Hirosaki, Aomori, Japan (J.Y.); and Department of Pharmacology and Physiology, and The Center for Neuroscience, Saint Louis University School of Medicine, St. Louis, Missouri (T.M.E.)
| | - Yoshikazu Nikaido
- Department of Drug Informatics, Faculty of Pharmaceutical Sciences, Fukuoka University, Fukuoka, Japan (K.M.); Department of Neurophysiology (T.O., S.S., Y.N., T.F., Y.S., S.U.) and Research Center for Child Mental Development (T.O., S.S., S.U.), Hirosaki University Graduate School of Medicine, Hirosaki, Aomori, Japan; Department of Biomedical Sciences, Hirosaki University Graduate School of Health Sciences, Hirosaki, Aomori, Japan (J.Y.); and Department of Pharmacology and Physiology, and The Center for Neuroscience, Saint Louis University School of Medicine, St. Louis, Missouri (T.M.E.)
| | - Tomonori Furukawa
- Department of Drug Informatics, Faculty of Pharmaceutical Sciences, Fukuoka University, Fukuoka, Japan (K.M.); Department of Neurophysiology (T.O., S.S., Y.N., T.F., Y.S., S.U.) and Research Center for Child Mental Development (T.O., S.S., S.U.), Hirosaki University Graduate School of Medicine, Hirosaki, Aomori, Japan; Department of Biomedical Sciences, Hirosaki University Graduate School of Health Sciences, Hirosaki, Aomori, Japan (J.Y.); and Department of Pharmacology and Physiology, and The Center for Neuroscience, Saint Louis University School of Medicine, St. Louis, Missouri (T.M.E.)
| | - Yuko Shiba
- Department of Drug Informatics, Faculty of Pharmaceutical Sciences, Fukuoka University, Fukuoka, Japan (K.M.); Department of Neurophysiology (T.O., S.S., Y.N., T.F., Y.S., S.U.) and Research Center for Child Mental Development (T.O., S.S., S.U.), Hirosaki University Graduate School of Medicine, Hirosaki, Aomori, Japan; Department of Biomedical Sciences, Hirosaki University Graduate School of Health Sciences, Hirosaki, Aomori, Japan (J.Y.); and Department of Pharmacology and Physiology, and The Center for Neuroscience, Saint Louis University School of Medicine, St. Louis, Missouri (T.M.E.)
| | - Terrance M Egan
- Department of Drug Informatics, Faculty of Pharmaceutical Sciences, Fukuoka University, Fukuoka, Japan (K.M.); Department of Neurophysiology (T.O., S.S., Y.N., T.F., Y.S., S.U.) and Research Center for Child Mental Development (T.O., S.S., S.U.), Hirosaki University Graduate School of Medicine, Hirosaki, Aomori, Japan; Department of Biomedical Sciences, Hirosaki University Graduate School of Health Sciences, Hirosaki, Aomori, Japan (J.Y.); and Department of Pharmacology and Physiology, and The Center for Neuroscience, Saint Louis University School of Medicine, St. Louis, Missouri (T.M.E.)
| | - Shinya Ueno
- Department of Drug Informatics, Faculty of Pharmaceutical Sciences, Fukuoka University, Fukuoka, Japan (K.M.); Department of Neurophysiology (T.O., S.S., Y.N., T.F., Y.S., S.U.) and Research Center for Child Mental Development (T.O., S.S., S.U.), Hirosaki University Graduate School of Medicine, Hirosaki, Aomori, Japan; Department of Biomedical Sciences, Hirosaki University Graduate School of Health Sciences, Hirosaki, Aomori, Japan (J.Y.); and Department of Pharmacology and Physiology, and The Center for Neuroscience, Saint Louis University School of Medicine, St. Louis, Missouri (T.M.E.)
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16
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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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17
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Qudrat A, Kim JI, Truong K. The spatiotemporal relationship between local Ca(2+) signaling and P2X2R-activated membrane blebbing. Cell Calcium 2016; 59:164-71. [PMID: 26846906 DOI: 10.1016/j.ceca.2016.01.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2015] [Revised: 01/12/2016] [Accepted: 01/12/2016] [Indexed: 12/24/2022]
Abstract
Mammalian P2X receptors (P2XRs), a family of seven ionotropic purinergic receptors, function as ion channels modulating diverse cellular processes such as secretion, apoptosis and proliferation in response to extracellular ATP. Previously, it was shown that upon ATP stimulus, the P2X7 receptor (a member of P2XR family) triggers plasma membrane (PM) blebbing in HEK293 cells. In this study, we demonstrate that this phenomenon extends to another member of the P2XR family-P2X2 receptor (P2X2R). Similar to P2X7 receptor, P2X2R blebbing is dependent on Ca(2+)-calmodulin and ROCK-I. To elucidate the spatiotemporal relationship between Ca(2+) signaling and blebbing, protein biosensors and switches were used to image and generate Ca(2+) signals, respectively, while observing PM blebbing in cells. Blebbing cannot be initiated by Ca(2+) influx from the endoplasmic reticulum or by Ca(2+) transport across the PM by other Ca(2+) channels. To trigger blebbing, it is necessary for Ca(2+) to enter specifically through the P2X2R. Lastly, a local Ca(2+) signal near a fragment that encodes the intracellular P2X2R C-terminus tail is sufficient to trigger blebbing.
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Affiliation(s)
- Anam Qudrat
- Institute of Biomaterials and Biomedical Engineering, University of Toronto, 164 College Street, Toronto, ON, Canada M5S 3G9
| | - Jae Ik Kim
- Institute of Biomaterials and Biomedical Engineering, University of Toronto, 164 College Street, Toronto, ON, Canada M5S 3G9
| | - Kevin Truong
- Institute of Biomaterials and Biomedical Engineering, University of Toronto, 164 College Street, Toronto, ON, Canada M5S 3G9; Edward S. Rogers, Sr. Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Circle, Toronto, ON, Canada M5S 3G4.
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18
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Affiliation(s)
- Bruce P Bean
- Department of Neurobiology, Harvard Medical School, Boston, Massachusetts, USA
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19
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Physical basis of apparent pore dilation of ATP-activated P2X receptor channels. Nat Neurosci 2015; 18:1577-83. [PMID: 26389841 DOI: 10.1038/nn.4120] [Citation(s) in RCA: 95] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2015] [Accepted: 08/25/2015] [Indexed: 12/11/2022]
Abstract
The selectivity of ion channels is fundamental for their roles in electrical and chemical signaling and in ion homeostasis. Although most ion channels exhibit stable ion selectivity, the prevailing view of purinergic P2X receptor channels, transient receptor potential V1 (TRPV1) channels and acid-sensing ion channels (ASICs) is that their ion conduction pores dilate upon prolonged activation. We investigated this mechanism in P2X receptors and found that the hallmark shift in equilibrium potential observed with prolonged channel activation does not result from pore dilation, but from time-dependent alterations in the concentration of intracellular ions. We derived a physical model to calculate ion concentration changes during patch-clamp recordings, which validated our experimental findings and provides a quantitative guideline for effectively controlling ion concentration. Our results have fundamental implications for understanding ion permeation and gating in P2X receptor channels, as well as more broadly for using patch-clamp techniques to study ion channels and neuronal excitability.
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20
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Caza F, Betoulle S, Auffret M, Brousseau P, Fournier M, St-Pierre Y. Comparative analysis of hemocyte properties from Mytilus edulis desolationis and Aulacomya ater in the Kerguelen Islands. MARINE ENVIRONMENTAL RESEARCH 2015; 110:174-182. [PMID: 26382607 DOI: 10.1016/j.marenvres.2015.09.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2015] [Revised: 08/31/2015] [Accepted: 09/01/2015] [Indexed: 06/05/2023]
Abstract
The capability of bivalve molluscs to respond to environmental stresses largely depends upon their cellular immunity. Accordingly, shift in habitat conditions following thermal stress or exposure to pollutants may harm sensitive species differently, thereby modulating the biodiversity of a given ecosystem by favoring stress-tolerant species. Here, we have compared the sensitivity of hemocytes from Mytilus edulis desolationis (M. edulis desolationis) and Aulacomya ater (A. ater) to acute thermal stress and exposure to cadmium. The two subantarctic species are commonly found in the same habitat in the isolated Kerguelen archipelago. Our results showed that the phagocytic activity and viability of hemocytes from both species were equally sensitive to increasing concentrations of cadmium. However, although in vitro exposure to cadmium induced apoptosis in hemocytes of M. edulis desolationis and A. ater, flow cytometric analyses showed that the apoptotic profile of both species differed greatly when using Annexin V and YO-PRO-1 as apoptotic markers. We also found that the total hemocyte counts decreased strongly in A. ater but not in M. edulis desolationis following an acute thermal stress. Taken together, these results showed that stress responses differed significantly in hemocytes from both species. This suggests that the co-existence of both species may be at risk following exposure to pollutants and/or changes in temperature.
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Affiliation(s)
- France Caza
- INRS-Institut Armand-Frappier, 531 Boul. des Prairies, Laval, Québec H7V 1B7, Canada
| | - Stéphane Betoulle
- Université Reims Champagne-Ardenne, UMR-I 02 SEBIO Stress environnementaux et Biosurveillance des milieux aquatiques, Campus Moulin de la Housse, 51687 Reims, France
| | - Michel Auffret
- Laboratoire des Sciences de l'Environnement Marin, UMR CNRS 6539-LEMAR, Technopôle Brest-Iroise, 29280 Plouzane, France
| | - Pauline Brousseau
- INRS-Institut Armand-Frappier, 531 Boul. des Prairies, Laval, Québec H7V 1B7, Canada
| | - Michel Fournier
- INRS-Institut Armand-Frappier, 531 Boul. des Prairies, Laval, Québec H7V 1B7, Canada
| | - Yves St-Pierre
- INRS-Institut Armand-Frappier, 531 Boul. des Prairies, Laval, Québec H7V 1B7, Canada.
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21
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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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22
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Coddou C, Yan Z, Stojilkovic SS. Role of domain calcium in purinergic P2X2 receptor channel desensitization. Am J Physiol Cell Physiol 2015; 308:C729-36. [PMID: 25673774 DOI: 10.1152/ajpcell.00399.2014] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Accepted: 02/10/2015] [Indexed: 11/22/2022]
Abstract
Activation of P2X2 receptor channels (P2X2Rs) is characterized by a rapid current growth accompanied by a decay of current during sustained ATP application, a phenomenon known as receptor desensitization. Using rat, mouse, and human receptors, we show here that two processes contribute to receptor desensitization: bath calcium-independent desensitization and calcium-dependent desensitization. Calcium-independent desensitization is minor and comparable during repetitive agonist application in cells expressing the full size of the receptor but is pronounced in cells expressing shorter versions of receptors, indicating a role of the COOH terminus in control of receptor desensitization. Calcium-dependent desensitization is substantial during initial agonist application and progressively increases during repetitive agonist application in bath ATP and calcium concentration-dependent manners. Experiments with substitution of bath Na(+) with N-methyl-d-glucamine (NMDG(+)), a large organic cation, indicate that receptor pore dilation is a calcium-independent process in contrast to receptor desensitization. A decrease in the driving force for calcium by changing the holding potential from -60 to +120 mV further indicates that calcium influx through the channel pores at least partially accounts for receptor desensitization. Experiments with various receptor chimeras also indicate that the transmembrane and/or intracellular domains of P2X2R are required for development of calcium-dependent desensitization and that a decrease in the amplitude of current slows receptor desensitization. Simultaneous calcium and current recording shows development of calcium-dependent desensitization without an increase in global intracellular calcium concentrations. Combined with experiments with clamping intrapipette concentrations of calcium at various levels, these experiments indicate that domain calcium is sufficient to establish calcium-dependent receptor desensitization in experiments with whole-cell recordings.
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Affiliation(s)
- Claudio Coddou
- From the Section on Cellular Signaling, Program in Developmental Neuroscience, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland; Department of Biomedical Sciences, Faculty of Medicine, Universidad Católica del Norte, Coquimbo, Chile
| | - Zonghe Yan
- From the Section on Cellular Signaling, Program in Developmental Neuroscience, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland
| | - Stanko S Stojilkovic
- From the Section on Cellular Signaling, Program in Developmental Neuroscience, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland
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Bartlett R, Stokes L, Sluyter R. The P2X7 receptor channel: recent developments and the use of P2X7 antagonists in models of disease. Pharmacol Rev 2015; 66:638-75. [PMID: 24928329 DOI: 10.1124/pr.113.008003] [Citation(s) in RCA: 320] [Impact Index Per Article: 35.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The P2X7 receptor is a trimeric ATP-gated cation channel found predominantly, but not exclusively, on immune cells. P2X7 activation results in a number of downstream events, including the release of proinflammatory mediators and cell death and proliferation. As such, P2X7 plays important roles in various inflammatory, immune, neurologic and musculoskeletal disorders. This review focuses on the use of P2X7 antagonists in rodent models of neurologic disease and injury, inflammation, and musculoskeletal and other disorders. The cloning and characterization of human, rat, mouse, guinea pig, dog, and Rhesus macaque P2X7, as well as recent observations regarding the gating and permeability of P2X7, are discussed. Furthermore, this review discusses polymorphic and splice variants of P2X7, as well as the generation and use of P2X7 knockout mice. Recent evidence for emerging signaling pathways downstream of P2X7 activation and the growing list of negative and positive modulators of P2X7 activation and expression are also described. In addition, the use of P2X7 antagonists in numerous rodent models of disease is extensively summarized. Finally, the use of P2X7 antagonists in clinical trials in humans and future directions exploring P2X7 as a therapeutic target are described.
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Affiliation(s)
- Rachael Bartlett
- School of Biological Sciences, University of Wollongong, New South Wales, Australia and Illawarra Health and Medical Research Institute, Wollongong, New South Wales, Australia (R.B., R.S.); and Health Innovations Research Institute, School of Medical Sciences, RMIT University, Bundoora, Victoria, Australia (L.S.)
| | - Leanne Stokes
- School of Biological Sciences, University of Wollongong, New South Wales, Australia and Illawarra Health and Medical Research Institute, Wollongong, New South Wales, Australia (R.B., R.S.); and Health Innovations Research Institute, School of Medical Sciences, RMIT University, Bundoora, Victoria, Australia (L.S.)
| | - Ronald Sluyter
- School of Biological Sciences, University of Wollongong, New South Wales, Australia and Illawarra Health and Medical Research Institute, Wollongong, New South Wales, Australia (R.B., R.S.); and Health Innovations Research Institute, School of Medical Sciences, RMIT University, Bundoora, Victoria, Australia (L.S.)
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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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Burnstock G, Nistri A, Khakh BS, Giniatullin R. ATP-gated P2X receptors in health and disease. Front Cell Neurosci 2014; 8:204. [PMID: 25104924 PMCID: PMC4109572 DOI: 10.3389/fncel.2014.00204] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2014] [Accepted: 07/07/2014] [Indexed: 12/18/2022] Open
Affiliation(s)
- Geoffrey Burnstock
- Division of Biosciences, Autonomic Neuroscience Centre, University College Medical School London, UK ; Department of Pharmacology and Therapeutics, The University of Melbourne Parkville, VIC, Australia
| | - Andrea Nistri
- Neuroscience Department, International School for Advanced Studies (SISSA) Trieste, Italy
| | - Baljit S Khakh
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles Los Angeles, CA, USA
| | - Rashid Giniatullin
- Department Neurobiology, A. I. Virtanen Institute, University of Eastern Finland Kuopio, Finland ; Laboratory of Neurobiology, Department of Physiology, Kazan Federal University Kazan, Russia
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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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Zemkova H, Khadra A, Rokic MB, Tvrdonova V, Sherman A, Stojilkovic SS. Allosteric regulation of the P2X4 receptor channel pore dilation. Pflugers Arch 2014; 467:713-26. [PMID: 24917516 DOI: 10.1007/s00424-014-1546-7] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2014] [Revised: 05/20/2014] [Accepted: 05/26/2014] [Indexed: 11/28/2022]
Abstract
Allosteric modulators of ligand-gated receptor channels induce conformational changes of the entire protein that alter potencies and efficacies for orthosteric ligands, expressed as the half maximal effective concentration (EC50) and maximum current amplitude, respectively. Here, we studied the influence of allostery on channel pore dilation, an issue not previously addressed. Experiments were done using the rat P2X4 receptor expressed in human embryonic kidney 293T cells and gated by adenosine 5'-triphosphate (ATP) in the presence and absence of ivermectin (IVM), an established positive allosteric regulator of this channel. In the absence of IVM, this channel activates and deactivates rapidly, does not show transition from open to dilated states, desensitizes completely with a moderate rate, and recovers only fractionally during washout. IVM treatment increases the efficacy of ATP to activate the channel and slows receptor desensitization during sustained ATP application and receptor deactivation after ATP washout. The rescue of the receptor from desensitization temporally coincides with pore dilation, and the dilated channel can be reactivated after washout of ATP. Experiments with vestibular and transmembrane domain receptor mutants further established that IVM has distinct effects on opening and dilation of the channel pore, the first accounting for increased peak current amplitude and the latter correlating with changes in the EC50 and kinetics of receptor deactivation. The corresponding kinetic (Markov state) model indicates that the IVM-dependent transition from open to dilated state is coupled to receptor sensitization, which rescues the receptor from desensitization and subsequent internalization. Allosterically induced sensitization of P2X4R thus provides sustained signaling during prolonged and repetitive ATP stimulation.
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Affiliation(s)
- Hana Zemkova
- Department of Cellular and Molecular Neuroendocrinology, Institute of Physiology Academy of Sciences of the Czech Republic, Prague, Czech Republic
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