1
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Magni L, Yu H, Christensen NM, Poulsen MH, Frueh A, Deshar G, Johansen AZ, Johansen JS, Pless SA, Jørgensen NR, Novak I. Human P2X7 receptor variants Gly150Arg and Arg276His polymorphisms have differential effects on risk association and cellular functions in pancreatic cancer. Cancer Cell Int 2024; 24:148. [PMID: 38664691 PMCID: PMC11044319 DOI: 10.1186/s12935-024-03339-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2024] [Accepted: 04/18/2024] [Indexed: 04/29/2024] Open
Abstract
BACKGROUND The purinergic P2X7 receptor (P2X7R) plays an important role in the crosstalk between pancreatic stellate cells (PSCs) and cancer cells, thus promoting progression of pancreatic ductal adenocarcinoma (PDAC). Single nucleotide polymorphisms (SNPs) in the P2X7R have been reported for several cancers, but have not been explored in PDAC. MATERIALS AND METHODS Blood samples from PDAC patients and controls were genotyped for 11 non-synonymous SNPs in P2X7R and a risk analysis was performed. Relevant P2X7R-SNP GFP variants were expressed in PSCs and cancer cells and their function was assayed in the following tests. Responses in Ca2+ were studied with Fura-2 and dye uptake with YO-PRO-1. Cell migration was monitored by fluorescence microscopy. Released cytokines were measured with MSD assay. RESULTS Risk analysis showed that two SNPs 474G>A and 853G>A (rs28360447, rs7958316), that lead to the Gly150Arg and Arg276His variants, had a significant but opposite risk association with PDAC development, protecting against and predisposing to the disease, respectively. In vitro experiments performed on cancer cells and PSCs expressing the Gly150Arg variant showed reduced intracellular Ca2+ response, fluorescent dye uptake, and cell migration, while the Arg276His variant reduced dye uptake but displayed WT-like Ca2+ responses. As predicted, P2X7R was involved in cytokine release (IL-6, IL-1β, IL-8, TNF-α), but the P2X7R inhibitors displayed varied effects. CONCLUSION In conclusion, we provide evidence for the P2X7R SNPs association with PDAC and propose that they could be considered as potential biomarkers.
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Affiliation(s)
- Lara Magni
- Section for Cell Biology and Physiology, Department of Biology, University of Copenhagen, Universitetsparken 13, 2100, Copenhagen Ø, Denmark
| | - Haoran Yu
- Section for Cell Biology and Physiology, Department of Biology, University of Copenhagen, Universitetsparken 13, 2100, Copenhagen Ø, Denmark
| | - Nynne M Christensen
- Section for Cell Biology and Physiology, Department of Biology, University of Copenhagen, Universitetsparken 13, 2100, Copenhagen Ø, Denmark
| | - Mette H Poulsen
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Alexander Frueh
- Section for Cell Biology and Physiology, Department of Biology, University of Copenhagen, Universitetsparken 13, 2100, Copenhagen Ø, Denmark
| | - Ganga Deshar
- Section for Cell Biology and Physiology, Department of Biology, University of Copenhagen, Universitetsparken 13, 2100, Copenhagen Ø, Denmark
| | - Astrid Z Johansen
- Department of Oncology, Copenhagen University Hospital - Herlev and Gentofte Hospital, Herlev, Denmark
| | - Julia S Johansen
- Department of Oncology, Copenhagen University Hospital - Herlev and Gentofte Hospital, Herlev, Denmark
- Department of Medicine, Copenhagen University Hospital - Herlev and Gentofte, Herlev, Denmark
| | - Stephan A Pless
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Niklas R Jørgensen
- Department of Clinical Biochemistry, Copenhagen University Hospital Rigshospitalet, Copenhagen, Denmark
- Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Ivana Novak
- Section for Cell Biology and Physiology, Department of Biology, University of Copenhagen, Universitetsparken 13, 2100, Copenhagen Ø, Denmark.
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2
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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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3
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Barczyk A, Bauderlique‐Le Roy H, Jouy N, Renault N, Hottin A, Millet R, Vouret‐Craviari V, Adriouch S, Idziorek T, Dezitter X. Flow cytometry: An accurate tool for screening
P2RX7
modulators. Cytometry A 2020. [DOI: 10.1002/cyto.a.24287] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Amélie Barczyk
- Univ. Lille, Inserm, CHU Lille, U1286 – Infinite – Institute for Translational Research in Inflammation Lille France
| | - Hélène Bauderlique‐Le Roy
- Univ. Lille, UMS 2014‐US 41 PLBS BICel, Flow Cytometry Core Facility, Institut Pasteur de Lille Lille cedex France
| | - Nathalie Jouy
- Univ. Lille, UMS 2014‐US 41 PLBS BICel, Flow Cytometry Core Facility, IRCL, 1 place de Verdun Lille cedex France
| | - Nicolas Renault
- Univ. Lille, Inserm, CHU Lille, U1286 – Infinite – Institute for Translational Research in Inflammation Lille France
| | - Audrey Hottin
- Univ. Lille, Inserm, CHU Lille, U1286 – Infinite – Institute for Translational Research in Inflammation Lille France
| | - Régis Millet
- Univ. Lille, Inserm, CHU Lille, U1286 – Infinite – Institute for Translational Research in Inflammation Lille France
| | - Valérie Vouret‐Craviari
- University Cote d'Azur, Institute for Research on Cancer and Aging, IRCAN U1081 UMR CNRS 7284 Nice France
| | - Sahil Adriouch
- Normandie University, UNIROUEN, INSERM, U1234, Pathophysiology, Autoimmunity, Neuromuscular Diseases and Regenerative THERapies (PANTHER) Rouen France
| | - Thierry Idziorek
- Univ. Lille, UMS 2014‐US 41 PLBS BICel, Flow Cytometry Core Facility, IRCL, 1 place de Verdun Lille cedex France
- Univ. Lille, CNRS, Inserm, CHU Lille, Institut de Recherche contre le Cancer de Lille, UMR9020 – UMR‐S 1277 ‐ Canther – Cancer Heterogeneity, Plasticity and Resistance to Therapies Lille France
| | - Xavier Dezitter
- Univ. Lille, Inserm, CHU Lille, U1286 – Infinite – Institute for Translational Research in Inflammation Lille France
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4
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Ishchenko Y, Novosolova N, Khafizov K, Bart G, Timonina A, Fayuk D, Skorinkin A, Giniatullin R. Reconstructed Serine 288 in the Left Flipper Region of the Rat P2X7 Receptor Stabilizes Nonsensitized States. Biochemistry 2017; 56:3394-3402. [PMID: 28616989 DOI: 10.1021/acs.biochem.7b00258] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Serine 275, a conserved residue of the left flipper region of ATP-gated P2X3 receptors, plays a key role in both agonist binding and receptor desensitization. It is conserved in most of the P2X receptors except P2X7 and P2X6. By combining experimental patch-clamp and modeling approaches, we explored the role of the corresponding residue in the rat P2X7 receptor (rP2X7) by replacing the phenylalanine at position 288 with serine and characterizing the membrane currents generated by either the wild-type (WT) or the mutated rP2X7 receptor. F288S, an rP2X7 mutation, slowed the deactivation subsequent to 2 and 20 s applications of 1 mM ATP. F288S also prevented sensitization (a progressive current growth) observed with the WT in response to a 20 s application of 1 mM ATP. Increasing the ATP concentration to 5 mM promoted sensitization also in the mutated rP2X7 receptor, accelerating the deactivation rate to typical WT values. YO-PRO1 uptake in cells expressing either the WT or the F288S P2X7 receptor was consistent with recorded membrane current data. Interestingly, in the human P2X7 (hP2X7) receptor, substitution Y288S did not change the deactivation rate, while the Y288F mutant generated a "rat-like" phenotype with a fast deactivation rate. Our combined experimental, kinetic, and molecular modeling data suggest that the rat F288S novel phenotype is due to a slower rate of ATP binding and/or unbinding and stabilization of nonsensitized receptor states.
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Affiliation(s)
| | | | - Kamil Khafizov
- Moscow Institute of Physics and Technology , Dolgoprudny, Moscow Region, Russian Federation.,Central Research Institute of Epidemiology , Moscow, Russian Federation
| | - Geneviève Bart
- A. I. Virtanen Institute, University of Eastern Finland , Kuopio, Finland.,Faculty of Biochemistry and Molecular Medicine, University of Oulu , Oulu, Finland
| | - Arina Timonina
- A. I. Virtanen Institute, University of Eastern Finland , Kuopio, Finland
| | - Dmitriy Fayuk
- A. I. Virtanen Institute, University of Eastern Finland , Kuopio, Finland
| | - Andrei Skorinkin
- Department of Biophysics of Synaptic Processes, Kazan Institute of Biochemistry and Biophysics, Russian Academy of Sciences , Kazan, Russian Federation.,Lab of Neuropharmacology, Kazan Federal University , Kazan, Russian Federation
| | - Rashid Giniatullin
- A. I. Virtanen Institute, University of Eastern Finland , Kuopio, Finland.,Lab of Neurobiology, Kazan Federal University , Kazan, Russian Federation
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5
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Abstract
The P2X7 receptor is a trimeric ion channel gated by extracellular adenosine 5'-triphosphate. The receptor is present on an increasing number of different cells types including stem, blood, glial, neural, ocular, bone, dental, exocrine, endothelial, muscle, renal and skin cells. The P2X7 receptor induces various downstream events in a cell-specific manner, including inflammatory molecule release, cell proliferation and death, metabolic events, and phagocytosis. As such this receptor plays important roles in heath and disease. Increasing knowledge about the P2X7 receptor has been gained from studies of, but not limited to, protein chemistry including cloning, site-directed mutagenesis, crystal structures and atomic modeling, as well as from studies of primary tissues and transgenic mice. This chapter focuses on the P2X7 receptor itself. This includes the P2RX7 gene and its products including splice and polymorphic variants. This chapter also reviews modulators of P2X7 receptor activation and inhibition, as well as the transcriptional regulation of the P2RX7 gene via its promoter and enhancer regions, and by microRNA and long-coding RNA. Furthermore, this chapter discusses the post-translational modification of the P2X7 receptor by N-linked glycosylation, adenosine 5'-diphosphate ribosylation and palmitoylation. Finally, this chapter reviews interaction partners of the P2X7 receptor, and its cellular localisation and trafficking within cells.
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Affiliation(s)
- Ronald Sluyter
- School of Biological Sciences, University of Wollongong, Wollongong, NSW, 2522, Australia. .,Centre for Medical and Molecular Bioscience, University of Wollongong, Wollongong, NSW, 2522, Australia. .,Illawarra Health and Medical Research Institute, Wollongong, NSW, 2522, Australia.
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6
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Hou Z, Cao J. Comparative study of the P2X gene family in animals and plants. Purinergic Signal 2016; 12:269-81. [PMID: 26874702 PMCID: PMC4854843 DOI: 10.1007/s11302-016-9501-z] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2015] [Accepted: 02/05/2016] [Indexed: 12/22/2022] Open
Abstract
P2X receptors are ligand-gated ion channels that can bind with the adenosine triphosphate (ATP) and have diverse functional roles in neuropathic pain, inflammation, special sense, and so on. In this study, 180 putative P2X genes, including 176 members in 32 animal species and 4 members in 3 species of lower plants, were identified. These genes were divided into 13 groups, including 7 groups in vertebrates and 6 groups in invertebrates and lower plants, through phylogenetic analysis. Their gene organization and motif composition are conserved in most predicted P2X members, while group-specific features were also found. Moreover, synteny relationships of the putative P2X genes in vertebrates are conserved while simultaneously experiencing a series of gene insertion, inversion, and transposition. Recombination signals were detected in almost all of the vertebrates and invertebrates, suggesting that intragenic recombination may play a significant role in the evolution of P2X genes. Selection analysis also identified some positively selected sites that acted on the evolution of most of the predicted P2X proteins. The phenomenon of alternative splicing occurred commonly in the putative P2X genes of vertebrates. This article explored in depth the evolutional relationship among different subtypes of P2X genes in animal and plants and might serve as a solid foundation for deciphering their functions in further studies.
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Affiliation(s)
- Zhuoran Hou
- School of Medicine, Jiangsu University, Zhenjiang, Jiangsu, People's Republic of China
| | - Jun Cao
- Institute of Life Science, Jiangsu University, Zhenjiang, Jiangsu, People's Republic of China.
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7
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Alves LA, da Silva JHM, Ferreira DNM, Fidalgo-Neto AA, Teixeira PCN, de Souza CAM, Caffarena ER, de Freitas MS. Structural and molecular modeling features of P2X receptors. Int J Mol Sci 2014; 15:4531-49. [PMID: 24637936 PMCID: PMC3975412 DOI: 10.3390/ijms15034531] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2013] [Revised: 12/05/2013] [Accepted: 12/10/2013] [Indexed: 01/05/2023] Open
Abstract
Currently, adenosine 5'-triphosphate (ATP) is recognized as the extracellular messenger that acts through P2 receptors. P2 receptors are divided into two subtypes: P2Y metabotropic receptors and P2X ionotropic receptors, both of which are found in virtually all mammalian cell types studied. Due to the difficulty in studying membrane protein structures by X-ray crystallography or NMR techniques, there is little information about these structures available in the literature. Two structures of the P2X4 receptor in truncated form have been solved by crystallography. Molecular modeling has proven to be an excellent tool for studying ionotropic receptors. Recently, modeling studies carried out on P2X receptors have advanced our knowledge of the P2X receptor structure-function relationships. This review presents a brief history of ion channel structural studies and shows how modeling approaches can be used to address relevant questions about P2X receptors.
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Affiliation(s)
- Luiz Anastacio Alves
- Cell Communication Laboratory, Oswaldo Cruz Institute, Oswaldo Cruz Foundation (FIOCRUZ), 4365 Brazil ave, Rio de Janeiro 21045-900, Brazil.
| | - João Herminio Martins da Silva
- Oswaldo Cruz Foundation (FIOCRUZ) Ceará Avenida Santos Dumont, 5753, Torre Saúde, Sala 1303, Papicu, Fortaleza-CE, CEP 60180-900, Brazil.
| | - Dinarte Neto Moreira Ferreira
- Cell Communication Laboratory, Oswaldo Cruz Institute, Oswaldo Cruz Foundation (FIOCRUZ), 4365 Brazil ave, Rio de Janeiro 21045-900, Brazil.
| | - Antonio Augusto Fidalgo-Neto
- Cell Communication Laboratory, Oswaldo Cruz Institute, Oswaldo Cruz Foundation (FIOCRUZ), 4365 Brazil ave, Rio de Janeiro 21045-900, Brazil.
| | - Pedro Celso Nogueira Teixeira
- Cell Communication Laboratory, Oswaldo Cruz Institute, Oswaldo Cruz Foundation (FIOCRUZ), 4365 Brazil ave, Rio de Janeiro 21045-900, Brazil.
| | - Cristina Alves Magalhães de Souza
- Cell Communication Laboratory, Oswaldo Cruz Institute, Oswaldo Cruz Foundation (FIOCRUZ), 4365 Brazil ave, Rio de Janeiro 21045-900, Brazil.
| | - Ernesto Raúl Caffarena
- Scientific Computation Program, Oswaldo Cruz Foundation (FIOCRUZ), 4365 Brazil ave, Rio de Janeiro 21045-900, Brazil.
| | - Mônica Santos de Freitas
- Jiri Jonas Nuclear Magnetic Resonance Center, Science and Technology Institute of Structural Biology and Bioimaging, Leopoldo de Meis Medical Biochemistry Institute, Rio de Janeiro Federal University (UFRJ), Carlos Chagas Filho ave, 373, Rio de Janeiro 21941-901, Brazil.
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8
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Jiang LH, Baldwin JM, Roger S, Baldwin SA. Insights into the Molecular Mechanisms Underlying Mammalian P2X7 Receptor Functions and Contributions in Diseases, Revealed by Structural Modeling and Single Nucleotide Polymorphisms. Front Pharmacol 2013; 4:55. [PMID: 23675347 PMCID: PMC3646254 DOI: 10.3389/fphar.2013.00055] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2013] [Accepted: 04/11/2013] [Indexed: 12/13/2022] Open
Abstract
The mammalian P2X7 receptors (P2X7Rs), a member of the ionotropic P2X receptor family with distinctive functional properties, play an important part in mediating extracellular ATP signaling in health and disease. A clear delineation of the molecular mechanisms underlying the key receptor properties, such as ATP-binding, ion permeation, and large pore formation of the mammalian P2X7Rs, is still lacking, but such knowledge is crucial for a better understanding of their physiological functions and contributions in diseases and for development of therapeutics. The recent breakthroughs in determining the atomic structures of the zebrafish P2X4.1R in the closed and ATP-bound open states have provided the long-awaited structural information. The human P2RX7 gene is abundant with non-synonymous single nucleotide polymorphisms (NS-SNPs), which generate a repertoire of human P2X7Rs with point mutations. Characterizations of the NS-SNPs identified in patients of various disease conditions and the resulting mutations have informed previously unknown molecular mechanisms determining the mammalian P2X7R functions and diseases. In this review, we will discuss the new insights into such mechanisms provided by structural modeling and recent functional and genetic linkage studies of NS-SNPs.
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Affiliation(s)
- Lin-Hua Jiang
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds Leeds, UK
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9
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Adriouch S, Haag F, Boyer O, Seman M, Koch-Nolte F. Extracellular NAD(+): a danger signal hindering regulatory T cells. Microbes Infect 2012; 14:1284-92. [PMID: 22634347 DOI: 10.1016/j.micinf.2012.05.011] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2012] [Revised: 05/02/2012] [Accepted: 05/14/2012] [Indexed: 12/16/2022]
Abstract
Endogenous danger signals released during cell damage contribute to alert the immune system. Typically, their release results in the activation and maturation of innate immune cells, and the production of pro-inflammatory cytokines. In addition, extracellular NAD(+) stimulates immune responses by hindering regulatory T cells (Tregs), and could, therefore, represent the prototype of a new category of danger signals.
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Affiliation(s)
- Sahil Adriouch
- Inserm, U905, 22 boulevard Gambetta, F-76000 Rouen, Normandy, France.
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10
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Liu Y, Xiao Y, Li Z. P2X7 receptor positively regulates MyD88-dependent NF-κB activation. Cytokine 2011; 55:229-36. [PMID: 21621419 DOI: 10.1016/j.cyto.2011.05.003] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2010] [Revised: 03/29/2011] [Accepted: 05/02/2011] [Indexed: 02/03/2023]
Abstract
Recent studies have demonstrated that P2X7 plays a critical role in the immune system. Here, our results showed that P2X7 activated a NF-κB - but not an IFN-β-dependent luciferase reporter gene in HEK293T cells. P2X7 was involved in the LPS- and ATP-induced NF-κB activation but did not significantly impact the response to Zymosan in RAW264.7 cells. The activation of NF-κB and IFN-β induced by myeloid differentiation primary-response protein 88 (MyD88) was enhanced by P2X7 co-expression. The siRNA silencing MyD88 almost abolished the NF-κB activation induced by P2X7, and co-immunoprecipitation showed that P2X7 interacted with MyD88. The amino acids in the C-terminus, especially the LPS-binding region of P2X7, were critical for the cellular localization and immune function of P2X7. P2X7ΔC (190 amino acids deleted in the C-terminus) and P2X7 G586A variants localized throughout the cytoplasma with a little aggregation, which differs from the cell membrane localization of wild type P2X7. Both of them could not localize to Golgi or endoplasmic reticulum. P2X7ΔC and P2X7 G586A had impaired proteolytic cleavage of caspase-1 into the functional p20 subunit, which can activate pro-inflammatory cytokines such as IL-1β. P2X7 G586A also showed a slight interaction with MyD88 in our co-immunoprecipitation experiment. This interaction might result in the attenuated activation of NF-κB and IFN-β induced by MyD88.
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Affiliation(s)
- Yanhui Liu
- Key Laboratory of Regenerative Biology, Guangzhou Institute of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China
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11
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Bradley HJ, Baldwin JM, Goli GR, Johnson B, Zou J, Sivaprasadarao A, Baldwin SA, Jiang LH. Residues 155 and 348 contribute to the determination of P2X7 receptor function via distinct mechanisms revealed by single-nucleotide polymorphisms. J Biol Chem 2011; 286:8176-8187. [PMID: 21205829 DOI: 10.1074/jbc.m110.211284] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
P2X(7) receptors are important in mediating the physiological functions of extracellular ATP, and altered receptor expression and function have a causative role in the disease pathogenesis. Here, we investigated the mechanisms determining the P2X(7) receptor function by following two human single-nucleotide polymorphism (SNP) mutations that replace His-155 and Ala-348 in the human (h) P2X(7) receptor with the corresponding residues, Tyr-155 and Thr-348, in the rat (r) P2X(7) receptor. H155Y and A348T mutations in the hP2X(7) receptor increased ATP-induced currents, whereas the reciprocal mutations, Y155H and T348A, in the rP2X(7) receptor caused the opposite effects. Such a functional switch is a compelling indication that these residues are critical for P2X(7) receptor function. Additional mutations of His-155 and Ala-348 in the hP2X(7) receptor to residues with diverse side chains revealed a different dependence on the side chain properties, supporting the specificity of these two residues. Substitutions of the residues surrounding His-155 and Ala-348 in the hP2X(7) receptor with the equivalent ones in the rP2X(7) receptor also affected ATP-induced currents but were not fully reminiscent of the H155Y and A348T effects. Immunofluorescence imaging and biotin labeling assays showed that H155Y in the hP2X(7) receptor increased and Y155H in the rP2X(7) receptor decreased cell-surface expression. Such contrasting effects were not obvious with the reciprocal mutations of residue 348. Taken together, our results suggest that residues at positions 155 and 348 contribute to P2X(7) receptor function via determining the surface expression and the single-channel function, respectively. Such interpretations are consistent with the locations of the residues in the structural model of the hP2X(7) receptor.
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Affiliation(s)
- Helen J Bradley
- From the Institute of Membrane and Systems Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - Jocelyn M Baldwin
- From the Institute of Membrane and Systems Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - G Ranjan Goli
- From the Institute of Membrane and Systems Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - Brian Johnson
- From the Institute of Membrane and Systems Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - Jie Zou
- From the Institute of Membrane and Systems Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - Asipu Sivaprasadarao
- From the Institute of Membrane and Systems Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - Stephen A Baldwin
- From the Institute of Membrane and Systems Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - Lin-Hua Jiang
- From the Institute of Membrane and Systems Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, United Kingdom.
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12
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Jiang R, Martz A, Gonin S, Taly A, de Carvalho LP, Grutter T. A putative extracellular salt bridge at the subunit interface contributes to the ion channel function of the ATP-gated P2X2 receptor. J Biol Chem 2010; 285:15805-15. [PMID: 20308075 DOI: 10.1074/jbc.m110.101980] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The recent crystal structure of the ATP-gated P2X4 receptor revealed a static view of its architecture, but the molecular mechanisms underlying the P2X channels activation are still unknown. By using a P2X2 model based on the x-ray structure, we sought salt bridges formed between charged residues located in a region that directly connects putative ATP-binding sites to the ion channel. To reveal their significance for ion channel activation, we made systematic charge exchanges and measured the effects on ATP sensitivity. We found that charge reversals at the interfacial residues Glu(63) and Arg(274) produced gain-of-function phenotypes that were cancelled upon paired charge swapping. These results suggest that a putative intersubunit salt bridge formed between Glu(63) and Arg(274) contributes to the ion channel function. Engineered cysteines E63C and R274C formed redox-dependent cross-links in the absence of ATP. By contrast, the presence of ATP reduced the rate of disulfide bond formation, indicating that ATP binding might trigger relative movement of adjacent subunits at the level of Glu(63) and Arg(274), allowing the transmembrane helices to open the channel.
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Affiliation(s)
- Ruotian Jiang
- Laboratoire de Biophysicochimie des Récepteurs Canaux, UMR 7199 CNRS, Conception et Application de Molécules Bioactives, Faculté de Pharmacie, Université de Strasbourg, 74 route du Rhin, BP 24, 67401 Illkirch Cedex, France
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