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Dhuna K, Felgate M, Bidula SM, Walpole S, Bibic L, Cromer BA, Angulo J, Sanderson J, Stebbing MJ, Stokes L. Ginsenosides Act As Positive Modulators of P2X4 Receptors. Mol Pharmacol 2018; 95:210-221. [PMID: 30545933 PMCID: PMC6334005 DOI: 10.1124/mol.118.113696] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Accepted: 12/10/2018] [Indexed: 12/19/2022] Open
Abstract
We investigated the selectivity of protopanaxadiol ginsenosides from Panax ginseng acting as positive allosteric modulators on P2X receptors. ATP-induced responses were measured in stable cell lines overexpressing human P2X4 using a YOPRO-1 dye uptake assay, intracellular calcium measurements, and whole-cell patch-clamp recordings. Ginsenosides CK and Rd were demonstrated to enhance ATP responses at P2X4 by ∼twofold, similar to potentiation by the known positive modulator ivermectin. Investigations into the role of P2X4 in mediating a cytotoxic effect showed that only P2X7 expression in HEK-293 cells induces cell death in response to high concentrations of ATP, and that ginsenosides can enhance this process. Generation of a P2X7-deficient clone of BV-2 microglial cells using CRISPR/Cas9 gene editing enabled an investigation of endogenous P2X4 in a microglial cell line. Compared with parental BV-2 cells, P2X7-deficient BV-2 cells showed minor potentiation of ATP responses by ginsenosides, and insensitivity to ATP− or ATP+ ginsenoside-induced cell death, indicating a primary role for P2X7 receptors in both of these effects. Computational docking to a homology model of human P2X4, based on the open state of zfP2X4, yielded evidence of a putative ginsenoside binding site in P2X4 in the central vestibule region of the large ectodomain.
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Affiliation(s)
- Kshitija Dhuna
- School of Health and Biomedical Sciences, RMIT University, Bundoora, Victoria, Australia (K.D., B.A.C., M.J.S., L.S.); School of Pharmacy, University of East Anglia, Norwich Research Park, Norwich, United Kingdom (M.F., S.M.B., S.W., L.B., J.A., J.S., L.S.); Department of Chemistry and Biotechnology, Swinburne University of Technology, Hawthorn, Victoria, Australia (B.A.C.); and Florey Institute of Neuroscience and Mental Health, Department of Anatomy and Neuroscience, University of Melbourne, Victoria, Australia (M.J.S.)
| | - Matthew Felgate
- School of Health and Biomedical Sciences, RMIT University, Bundoora, Victoria, Australia (K.D., B.A.C., M.J.S., L.S.); School of Pharmacy, University of East Anglia, Norwich Research Park, Norwich, United Kingdom (M.F., S.M.B., S.W., L.B., J.A., J.S., L.S.); Department of Chemistry and Biotechnology, Swinburne University of Technology, Hawthorn, Victoria, Australia (B.A.C.); and Florey Institute of Neuroscience and Mental Health, Department of Anatomy and Neuroscience, University of Melbourne, Victoria, Australia (M.J.S.)
| | - Stefan M Bidula
- School of Health and Biomedical Sciences, RMIT University, Bundoora, Victoria, Australia (K.D., B.A.C., M.J.S., L.S.); School of Pharmacy, University of East Anglia, Norwich Research Park, Norwich, United Kingdom (M.F., S.M.B., S.W., L.B., J.A., J.S., L.S.); Department of Chemistry and Biotechnology, Swinburne University of Technology, Hawthorn, Victoria, Australia (B.A.C.); and Florey Institute of Neuroscience and Mental Health, Department of Anatomy and Neuroscience, University of Melbourne, Victoria, Australia (M.J.S.)
| | - Samuel Walpole
- School of Health and Biomedical Sciences, RMIT University, Bundoora, Victoria, Australia (K.D., B.A.C., M.J.S., L.S.); School of Pharmacy, University of East Anglia, Norwich Research Park, Norwich, United Kingdom (M.F., S.M.B., S.W., L.B., J.A., J.S., L.S.); Department of Chemistry and Biotechnology, Swinburne University of Technology, Hawthorn, Victoria, Australia (B.A.C.); and Florey Institute of Neuroscience and Mental Health, Department of Anatomy and Neuroscience, University of Melbourne, Victoria, Australia (M.J.S.)
| | - Lucka Bibic
- School of Health and Biomedical Sciences, RMIT University, Bundoora, Victoria, Australia (K.D., B.A.C., M.J.S., L.S.); School of Pharmacy, University of East Anglia, Norwich Research Park, Norwich, United Kingdom (M.F., S.M.B., S.W., L.B., J.A., J.S., L.S.); Department of Chemistry and Biotechnology, Swinburne University of Technology, Hawthorn, Victoria, Australia (B.A.C.); and Florey Institute of Neuroscience and Mental Health, Department of Anatomy and Neuroscience, University of Melbourne, Victoria, Australia (M.J.S.)
| | - Brett A Cromer
- School of Health and Biomedical Sciences, RMIT University, Bundoora, Victoria, Australia (K.D., B.A.C., M.J.S., L.S.); School of Pharmacy, University of East Anglia, Norwich Research Park, Norwich, United Kingdom (M.F., S.M.B., S.W., L.B., J.A., J.S., L.S.); Department of Chemistry and Biotechnology, Swinburne University of Technology, Hawthorn, Victoria, Australia (B.A.C.); and Florey Institute of Neuroscience and Mental Health, Department of Anatomy and Neuroscience, University of Melbourne, Victoria, Australia (M.J.S.)
| | - Jesus Angulo
- School of Health and Biomedical Sciences, RMIT University, Bundoora, Victoria, Australia (K.D., B.A.C., M.J.S., L.S.); School of Pharmacy, University of East Anglia, Norwich Research Park, Norwich, United Kingdom (M.F., S.M.B., S.W., L.B., J.A., J.S., L.S.); Department of Chemistry and Biotechnology, Swinburne University of Technology, Hawthorn, Victoria, Australia (B.A.C.); and Florey Institute of Neuroscience and Mental Health, Department of Anatomy and Neuroscience, University of Melbourne, Victoria, Australia (M.J.S.)
| | - Julie Sanderson
- School of Health and Biomedical Sciences, RMIT University, Bundoora, Victoria, Australia (K.D., B.A.C., M.J.S., L.S.); School of Pharmacy, University of East Anglia, Norwich Research Park, Norwich, United Kingdom (M.F., S.M.B., S.W., L.B., J.A., J.S., L.S.); Department of Chemistry and Biotechnology, Swinburne University of Technology, Hawthorn, Victoria, Australia (B.A.C.); and Florey Institute of Neuroscience and Mental Health, Department of Anatomy and Neuroscience, University of Melbourne, Victoria, Australia (M.J.S.)
| | - Martin J Stebbing
- School of Health and Biomedical Sciences, RMIT University, Bundoora, Victoria, Australia (K.D., B.A.C., M.J.S., L.S.); School of Pharmacy, University of East Anglia, Norwich Research Park, Norwich, United Kingdom (M.F., S.M.B., S.W., L.B., J.A., J.S., L.S.); Department of Chemistry and Biotechnology, Swinburne University of Technology, Hawthorn, Victoria, Australia (B.A.C.); and Florey Institute of Neuroscience and Mental Health, Department of Anatomy and Neuroscience, University of Melbourne, Victoria, Australia (M.J.S.)
| | - Leanne Stokes
- School of Health and Biomedical Sciences, RMIT University, Bundoora, Victoria, Australia (K.D., B.A.C., M.J.S., L.S.); School of Pharmacy, University of East Anglia, Norwich Research Park, Norwich, United Kingdom (M.F., S.M.B., S.W., L.B., J.A., J.S., L.S.); Department of Chemistry and Biotechnology, Swinburne University of Technology, Hawthorn, Victoria, Australia (B.A.C.); and Florey Institute of Neuroscience and Mental Health, Department of Anatomy and Neuroscience, University of Melbourne, Victoria, Australia (M.J.S.)
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Inoue K. A state-of-the-art perspective on microgliopathic pain. Open Biol 2018; 8:rsob.180154. [PMID: 30487300 PMCID: PMC6282071 DOI: 10.1098/rsob.180154] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2018] [Accepted: 10/30/2018] [Indexed: 01/01/2023] Open
Abstract
Acute nociceptive pain is an undesirable feeling but has a physiological significance as a warning system for living organisms. Conversely, chronic pain is lacking physiological significance, but rather represents a confusion of nerve functions. The neuropathic pain that occurs after peripheral nerve injury (PNI) is perhaps the most important type of chronic pain because it is refractory to available medications and thus remains a heavy clinical burden. In recent decades, studies have shown that spinal microglia play a principal role in the alterations in synaptic functions evoking this pain. It is also clear that the P2X4 receptor (P2X4R), a subtype of ionotropic ATP receptors, is upregulated exclusively in spinal microglia after PNI and plays a key role in evoking neuropathic pain. Neuropathic pain is caused by several conditions associated with activated microglia without nerve damage. ‘Microgliopathic pain’ is a new concept indicating such abnormal pain related to activated microglia.
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Affiliation(s)
- Kazuhide Inoue
- Department of Molecular and System Pharmacology, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka 812-8582, Japan
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Su WF, Wu F, Jin ZH, Gu Y, Chen YT, Fei Y, Chen H, Wang YX, Xing LY, Zhao YY, Yuan Y, Tang X, Chen G. Overexpression of P2X4 receptor in Schwann cells promotes motor and sensory functional recovery and remyelination via BDNF secretion after nerve injury. Glia 2018; 67:78-90. [DOI: 10.1002/glia.23527] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2018] [Revised: 08/10/2018] [Accepted: 08/10/2018] [Indexed: 02/01/2023]
Affiliation(s)
- Wen-Feng Su
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, Co-innovation Center of Neuroregeneration; Nantong University; Nantong China
| | - Fan Wu
- Medical School of Nantong University; Nantong China
| | - Zi-Han Jin
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, Co-innovation Center of Neuroregeneration; Nantong University; Nantong China
| | - Yun Gu
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, Co-innovation Center of Neuroregeneration; Nantong University; Nantong China
| | - Ying-Ting Chen
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, Co-innovation Center of Neuroregeneration; Nantong University; Nantong China
| | - Ying Fei
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, Co-innovation Center of Neuroregeneration; Nantong University; Nantong China
| | - Hui Chen
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, Co-innovation Center of Neuroregeneration; Nantong University; Nantong China
| | - Ya-Xian Wang
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, Co-innovation Center of Neuroregeneration; Nantong University; Nantong China
| | - Ling-Yan Xing
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, Co-innovation Center of Neuroregeneration; Nantong University; Nantong China
| | - Ya-Yu Zhao
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, Co-innovation Center of Neuroregeneration; Nantong University; Nantong China
| | - Ying Yuan
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, Co-innovation Center of Neuroregeneration; Nantong University; Nantong China
- Affiliated Hospital of Nantong University; Nantong China
| | - Xin Tang
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, Co-innovation Center of Neuroregeneration; Nantong University; Nantong China
| | - Gang Chen
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, Co-innovation Center of Neuroregeneration; Nantong University; Nantong China
- Department of Anesthesiology; Affiliated Hospital of Nantong University; Nantong China
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54
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Kuroda C, Ueda K, Haniu H, Ishida H, Okano S, Takizawa T, Sobajima A, Kamanaka T, Yoshida K, Okamoto M, Tsukahara T, Matsuda Y, Aoki K, Kato H, Saito N. Different aggregation and shape characteristics of carbon materials affect biological responses in RAW264 cells. Int J Nanomedicine 2018; 13:6079-6088. [PMID: 30323595 PMCID: PMC6179726 DOI: 10.2147/ijn.s172493] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Introduction Carbon nanotubes (CNTs) have various shapes, including needle-like shapes and curled shapes, and the cytotoxicity and carcinogenicity of CNTs differ depending on their shapes and surface modifications. However, the biological responses induced by CNTs and related mechanisms according to the dispersion state of CNTs have not been extensively studied. Materials and methods We prepared multiwalled CNTs (MWCNTs) showing different dispersions and evaluated these MWCNTs in RAW264 cells to determine cytotoxicity, cellular uptake, and immune responses. Furthermore, RAW264 cells were also used to compare the cellular uptake and cytotoxicity of fibrous MWCNTs and spherical carbon nanohorns (CNHs) exhibiting the same degree of dispersion. Results Our analysis showed that the cellular uptake, localization, and inflammatory responses of MWCNTs differed depending on the dispersion state. Moreover, there were differences in uptake between MWCNTs and CNHs, even showing the same degree of dispersion. These findings suggested that receptors related to cytotoxicity and immune responses differed depending on the aggregated state of MWCNTs and surface modification with a dispersant. Furthermore, our results suggested that the receptors recognized by the cells differed depending on the particle shape. Conclusion Therefore, to apply MWCNTs as a biomaterial, it is important to determine the carcinogenicity and toxicity of the CNTs and to examine different biological responses induced by varying shapes, dispersion states, and surface modifications of particles.
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Affiliation(s)
- Chika Kuroda
- Institute for Biomedical Sciences, Interdisciplinary Cluster for Cutting Edge Research, Shinshu University, Asahi, Matsumoto, Nagano, Japan, .,Department of Orthopaedic Surgery, Graduate School of Medicine, Shinshu University, Asahi, Matsumoto, Nagano, Japan
| | - Katsuya Ueda
- Institute for Biomedical Sciences, Interdisciplinary Cluster for Cutting Edge Research, Shinshu University, Asahi, Matsumoto, Nagano, Japan, .,Department of Biomedical Engineering, Graduate School of Science and Technology, Shinshu University, Asahi, Matsumoto, Nagano, Japan,
| | - Hisao Haniu
- Institute for Biomedical Sciences, Interdisciplinary Cluster for Cutting Edge Research, Shinshu University, Asahi, Matsumoto, Nagano, Japan, .,Department of Biomedical Engineering, Graduate School of Science and Technology, Shinshu University, Asahi, Matsumoto, Nagano, Japan, .,Department of Biomedical Engineering, Graduate School of Medicine, Science and Technology, Shinshu University, Asahi, Matsumoto, Nagano, Japan, .,Department of Orthopaedic Surgery, Shinshu University School of Medicine, Asahi, Matsumoto, Nagano, Japan,
| | - Haruka Ishida
- Institute for Biomedical Sciences, Interdisciplinary Cluster for Cutting Edge Research, Shinshu University, Asahi, Matsumoto, Nagano, Japan, .,Department of Biomedical Engineering, Graduate School of Medicine, Science and Technology, Shinshu University, Asahi, Matsumoto, Nagano, Japan,
| | - Satomi Okano
- Institute for Biomedical Sciences, Interdisciplinary Cluster for Cutting Edge Research, Shinshu University, Asahi, Matsumoto, Nagano, Japan, .,Department of Biomedical Engineering, Graduate School of Medicine, Science and Technology, Shinshu University, Asahi, Matsumoto, Nagano, Japan,
| | - Takashi Takizawa
- Department of Orthopaedic Surgery, Shinshu University School of Medicine, Asahi, Matsumoto, Nagano, Japan,
| | - Atsushi Sobajima
- Department of Orthopaedic Surgery, Shinshu University School of Medicine, Asahi, Matsumoto, Nagano, Japan,
| | - Takayuki Kamanaka
- Department of Orthopaedic Surgery, Shinshu University School of Medicine, Asahi, Matsumoto, Nagano, Japan,
| | - Kazushige Yoshida
- Department of Orthopaedic Surgery, Shinshu University School of Medicine, Asahi, Matsumoto, Nagano, Japan,
| | - Masanori Okamoto
- Department of Orthopaedic Surgery, Shinshu University School of Medicine, Asahi, Matsumoto, Nagano, Japan,
| | - Tamotsu Tsukahara
- Department of Molecular Pharmacology and Neuroscience, Nagasaki University Graduate School of Biomedical Sciences, Bunkyo-machi, Nagasaki, Japan
| | - Yoshikazu Matsuda
- Clinical Pharmacology Educational Center, Nihon Pharmaceutical University, Komuro, Ina-machi, Saitama, Japan
| | - Kaoru Aoki
- Physical Therapy Division, School of Health Sciences, Shinshu University, Asahi, Matsumoto, Nagano, Japan
| | - Hiroyuki Kato
- Department of Orthopaedic Surgery, Shinshu University School of Medicine, Asahi, Matsumoto, Nagano, Japan,
| | - Naoto Saito
- Institute for Biomedical Sciences, Interdisciplinary Cluster for Cutting Edge Research, Shinshu University, Asahi, Matsumoto, Nagano, Japan, .,Department of Biomedical Engineering, Graduate School of Science and Technology, Shinshu University, Asahi, Matsumoto, Nagano, Japan, .,Department of Biomedical Engineering, Graduate School of Medicine, Science and Technology, Shinshu University, Asahi, Matsumoto, Nagano, Japan, .,Department of Orthopaedic Surgery, Shinshu University School of Medicine, Asahi, Matsumoto, Nagano, Japan,
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55
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Fois G, Föhr KJ, Kling C, Fauler M, Wittekindt OH, Dietl P, Frick M. P2X 4 receptor re-sensitization depends on a protonation/deprotonation cycle mediated by receptor internalization and recycling. J Physiol 2018; 596:4893-4907. [PMID: 30144063 DOI: 10.1113/jp275448] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2018] [Accepted: 08/21/2018] [Indexed: 12/28/2022] Open
Abstract
KEY POINTS Re-sensitization of P2X4 receptors depends on a protonation/de-protonation cycle Protonation and de-protonation of the receptors is achieved by internalization and recycling of P2X4 receptors via acidic compartments Protonation and de-protonation occurs at critical histidine residues within the extracellular loop of P2X4 receptors Re-sensitization is blocked in the presence of the receptor agonist ATP ABSTRACT: P2X4 receptors are members of the P2X receptor family of cation-permeable, ligand-gated ion channels that open in response to the binding of extracellular ATP. P2X4 receptors are implicated in a variety of biological processes, including cardiac function, cell death, pain sensation and immune responses. These physiological functions depend on receptor activation on the cell surface. Receptor activation is followed by receptor desensitization and deactivation upon removal of ATP. Subsequent re-sensitization is required to return the receptor into its resting state. Desensitization and re-sensitization are therefore crucial determinants of P2X receptor signal transduction and responsiveness to ATP. However, the molecular mechanisms controlling desensitization and re-sensitization are not fully understood. In the present study, we provide evidence that internalization and recycling via acidic compartments is essential for P2X4 receptor re-sensitization. Re-sensitization depends on a protonation/de-protonation cycle of critical histidine residues within the extracellular loop of P2X4 receptors that is mediated by receptor internalization and recycling. Interestingly, re-sensitization under acidic conditions is completely revoked by receptor agonist ATP. Our data support the physiological importance of the unique subcellular distribution of P2X4 receptors that is predominantly found within acidic compartments. Based on these findings, we suggest that recycling of P2X4 receptors regulates the cellular responsiveness in the sustained presence of ATP.
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Affiliation(s)
| | - Karl J Föhr
- Department of Anesthesiology, University of Ulm, Ulm, Germany
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56
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Fagerberg SK, Patel P, Andersen LW, Lui X, Donnino MW, Praetorius HA. Erythrocyte P2X 1 receptor expression is correlated with change in haematocrit in patients admitted to the ICU with blood pathogen-positive sepsis. Crit Care 2018; 22:181. [PMID: 30071869 PMCID: PMC6091015 DOI: 10.1186/s13054-018-2100-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2018] [Accepted: 06/19/2018] [Indexed: 12/03/2022] Open
Abstract
Background Pore-forming proteins released from bacteria or formed as result of complement activation are known to produce severe cell damage. Inhibition of purinergic P2X receptors markedly reduces damage inflicted by cytolytic bacterial toxin and after complement activation in both erythrocytes and monocytes. P2X expression generally shows variation throughout the population. Here, we investigate correlation between P2X receptor abundance in blood cell plasma membranes and haematocrit during sepsis, in patients admitted to the emergency department (ED) or intensive care unit (ICU). Method Patients admitted to the ED and successively transferred to ICU with the diagnosis sepsis (< 2 systemic inflammatory response syndrome (SIRS) criteria and suspected infection), were grouped as either blood pathogen-positive (14 patients) or blood pathogen-negative (20 patients). Blood samples drawn at ICU admission were analysed for P2X1 and P2X7 receptor abundance using indirect flow cytometry. Results Here, we find inverse correlation between P2X1 receptor expression and change in haematocrit (rs − 0.80) and haemoglobin (rs − 0.78) levels from admission to ED to arrival at ICU in patients with pathogen-positive sepsis. This correlation was not found in patients without confirmed bacteraemia. Patients with high P2X1 expression had a significantly greater change in both haematocrit (− 0.59 ± 0.36) and haemoglobin levels (− 0.182 ± 0.038 mg/dl) per hour, during the first hours after hospital admission compared to patients with low P2X1 expression (0.007 ± 0.182 and − 0.020 ± 0.058 mg/dl, respectively). Conclusion High levels of P2X1 are correlated with more pronounced reduction in haematocrit and haemoglobin in patients with confirmed bacteraemia. This supports previous in vitro findings of P2X activation as a significant component in cell damage caused by pore-forming bacterial toxins and complement-dependent major attack complex. These data suggest a new potential target for future therapeutics in initial stages of sepsis. Electronic supplementary material The online version of this article (10.1186/s13054-018-2100-3) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Steen K Fagerberg
- Department of Biomedicine, Physiology, Aarhus University, Ole Worms Alle 3, build 1170, 8000, Aarhus C, Denmark.,Department of Emergency Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
| | - Parth Patel
- Department of Emergency Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
| | - Lars W Andersen
- Department of Emergency Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA.,Research Center for Emergency Medicine, Aarhus University Hospital, Aarhus, Denmark
| | - Xiaowen Lui
- Department of Emergency Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
| | - Michael W Donnino
- Department of Emergency Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
| | - Helle A Praetorius
- Department of Biomedicine, Physiology, Aarhus University, Ole Worms Alle 3, build 1170, 8000, Aarhus C, Denmark.
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Di Virgilio F, Sarti AC, Grassi F. Modulation of innate and adaptive immunity by P2X ion channels. Curr Opin Immunol 2018; 52:51-59. [PMID: 29631184 DOI: 10.1016/j.coi.2018.03.026] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Revised: 03/27/2018] [Accepted: 03/27/2018] [Indexed: 12/12/2022]
Abstract
Extracellular ATP is a major component of the inflammatory microenvironment where it accumulates following cell and tissue injury but also as a consequence of non-lytic release from activated inflammatory cells. In the inflammatory microenvironment ATP binds and activates nucleotide receptors of the P2Y and P2X subfamilies expressed by immune cells. P2Y receptors are G-protein-coupled, while P2X receptors are cation-selective channels. Changes in the intracellular ion homeostasis triggered by P2X receptor stimulation trigger multiple key responses crucial for initiation, propagation, and resolution of inflammation. In the P2X receptor family, the P2X7 subtype has an important role in the activation of lymphocyte, granulocyte, macrophage and dendritic cell responses. Although clinical studies have been so far rather inconclusive, it is believed that P2X7 receptor targeting might offer novel perspectives for anti-inflammatory therapy.
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Affiliation(s)
- Francesco Di Virgilio
- Department of Morphology, Surgery and Experimental Medicine, University of Ferrara, Italy.
| | - Alba Clara Sarti
- Department of Morphology, Surgery and Experimental Medicine, University of Ferrara, Italy
| | - Fabio Grassi
- Institute for Research in Biomedicine, Università della Svizzera Italiana, Via Vincenzo Vela 6, CH-6500 Bellinzona, Switzerland; Department of Medical Biotechnology and Translational Medicine (BIOMETRA), Università degli Studi di Milano, Via G.B. Viotti 3/5, 20133 Milan, Italy; Istituto Nazionale Genetica Molecolare "Romeo ed Enrica Invernizzi", Via Francesco Sforza, 35-20122 Milan, Italy.
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Abstract
Cells utilize calcium ions (Ca2+) to signal almost all aspects of cellular life, ranging from cell proliferation to cell death, in a spatially and temporally regulated manner. A key aspect of this regulation is the compartmentalization of Ca2+ in various cytoplasmic organelles that act as intracellular Ca2+ stores. Whereas Ca2+ release from the large-volume Ca2+ stores, such as the endoplasmic reticulum (ER) and Golgi apparatus, are preferred for signal transduction, Ca2+ release from the small-volume individual vesicular stores that are dispersed throughout the cell, such as lysosomes, may be more useful in local regulation, such as membrane fusion and individualized vesicular movements. Conceivably, these two types of Ca2+ stores may be established, maintained or refilled via distinct mechanisms. ER stores are refilled through sustained Ca2+ influx at ER-plasma membrane (PM) membrane contact sites (MCSs). In this review, we discuss the release and refilling mechanisms of intracellular small vesicular Ca2+ stores, with a special focus on lysosomes. Recent imaging studies of Ca2+ release and organelle MCSs suggest that Ca2+ exchange may occur between two types of stores, such that the small stores acquire Ca2+ from the large stores via ER-vesicle MCSs. Hence vesicular stores like lysosomes may be viewed as secondary Ca2+ stores in the cell.
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59
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Abstract
Murrell-Lagnado provides insight into new research revealing the physiological role of lysosomal P2X4 channels.
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Affiliation(s)
- Ruth D Murrell-Lagnado
- Sussex Neuroscience, School of Life Sciences, University of Sussex, Brighton, England, UK
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60
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Patel S. Ins and outs of Ca 2+ transport by acidic organelles and cell migration. Commun Integr Biol 2018. [PMCID: PMC5824967 DOI: 10.1080/19420889.2017.1331800] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Much contemporary evidence underscores the pathophysiological importance of Ca2+ handling by acidic organelles such as lysosomes. Whereas our knowledge of how Ca2+ is released from these acidic Ca2+ stores (the ‘outs’) is advancing, we know relatively little about how Ca2+ uptake is effected (the ‘ins’). Here I highlight new work identifying animal Ca2+/H+ (CAX) exchangers that localize to acidic organelles, mediate Ca2+ uptake and regulate cell migration in vivo. Continued molecular definition of the acidic Ca2+ store toolkit provides new insight into Ca2+-dependent function.
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Affiliation(s)
- Sandip Patel
- Department of Cell and Developmental Biology, University College London, London, UK
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61
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Toll-like receptor-4/p38 MAPK signaling in the dorsal horn contributes to P2X4 receptor activation and BDNF over-secretion in cancer induced bone pain. Neurosci Res 2017; 125:37-45. [DOI: 10.1016/j.neures.2017.06.006] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2016] [Revised: 06/19/2017] [Accepted: 06/22/2017] [Indexed: 12/30/2022]
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62
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Layhadi JA, Fountain SJ. P2X4 Receptor-Dependent Ca 2+ Influx in Model Human Monocytes and Macrophages. Int J Mol Sci 2017; 18:ijms18112261. [PMID: 29077063 PMCID: PMC5713231 DOI: 10.3390/ijms18112261] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2017] [Revised: 10/16/2017] [Accepted: 10/18/2017] [Indexed: 01/01/2023] Open
Abstract
Monocytes and macrophages express a repertoire of cell surface P2 receptors for adenosine 5′-triphosphate (ATP) a damage-associated molecular pattern molecule (DAMP), which are capable of raising cytoplasmic calcium when activated. This is achieved either through direct permeation (ionotropic P2X receptors) or by mobilizing intracellular calcium stores (metabotropic P2Y receptors). Here, a side-by-side comparison to investigate the contribution of P2X4 receptor activation in ATP-evoked calcium responses in model human monocytes and macrophages was performed. The expression of P2X1, P2X4, P2X5 and P2X7 was confirmed by qRT-PCR and immunocytochemistry in both model monocyte and macrophage. ATP evoked a concentration-dependent increase in intracellular calcium in both THP-1 monocyte and macrophages. The sarco/endoplasmic reticulum Ca2+-ATPase inhibitor thasigargin (Tg) responses to the maximal ATP concentration (100 μM) in THP-1 monocytes, and responses in macrophage were significantly attenuated. Tg-resistant ATP-evoked calcium responses in the model macrophage were dependent on extracellular calcium, suggesting a requirement for calcium influx. Ivermectin (IVM) potentiated the magnitude of Tg-resistant component and slowed the decay of response in the model macrophage. The Tg-resistant component was attenuated by P2X4 antagonists 5-BDBD and PSB-12062 but not by the P2X1 antagonist Ro0437626 or the P2X7 antagonist A438079. shRNA-mediated P2X4 knockdown resulted in a significant reduction in Tg-resistant ATP-evoked calcium response as well as reduced sensitivities towards P2X4-specific pharmacological tools, IVM and PSB-12062. Inhibition of endocytosis with dynasore significantly reduced the magnitude of Tg-resistant component but substantially slowed decay response. Inhibition of calcium-dependent exocytosis with vacuolin-1 had no effect on the Tg-resistant component. These pharmacological data suggest that P2X4 receptor activation contributed significantly towards the ionotropic calcium response evoked by ATP of the model human macrophage.
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Affiliation(s)
- Janice A Layhadi
- School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK.
| | - Samuel J Fountain
- School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK.
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63
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Suurväli J, Boudinot P, Kanellopoulos J, Rüütel Boudinot S. P2X4: A fast and sensitive purinergic receptor. Biomed J 2017; 40:245-256. [PMID: 29179879 PMCID: PMC6138603 DOI: 10.1016/j.bj.2017.06.010] [Citation(s) in RCA: 109] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2017] [Revised: 06/28/2017] [Accepted: 06/30/2017] [Indexed: 01/31/2023] Open
Abstract
Extracellular nucleotides have been recognized as important mediators of activation, triggering multiple responses via plasma membrane receptors known as P2 receptors. P2 receptors comprise P2X ionotropic receptors and G protein-coupled P2Y receptors. P2X receptors are expressed in many tissues, where they are involved in a number of functions including synaptic transmission, muscle contraction, platelet aggregation, inflammation, macrophage activation, differentiation and proliferation, neuropathic and inflammatory pain. P2X4 is one of the most sensitive purinergic receptors (at nanomolar ATP concentrations), about one thousand times more than the archetypal P2X7. P2X4 is widely expressed in central and peripheral neurons, in microglia, and also found in various epithelial tissues and endothelial cells. It localizes on the plasma membrane, but also in intracellular compartments. P2X4 is preferentially localized in lysosomes, where it is protected from proteolysis by its glycosylation. High ATP concentration in the lysosomes does not activate P2X4 at low pH; P2X4 gets activated by intra-lysosomal ATP only in its fully dissociated tetra-anionic form, when the pH increases to 7.4. Thus, P2X4 is functioning as a Ca2+-channel after the fusion of late endosomes and lysosomes. P2X4 modulates major neurotransmitter systems and regulates alcohol-induced responses in microglia. P2X4 is one of the key receptors mediating neuropathic pain. However, injury-induced upregulation of P2X4 expression is gender dependent and plays a key role in pain difference between males and females. P2X4 is also involved in inflammation. Extracellular ATP being a pro-inflammatory molecule, P2X4 can trigger inflammation in response to high ATP release. It is therefore involved in multiple pathologies, like post-ischemic inflammation, rheumatoid arthritis, airways inflammation in asthma, neurodegenerative diseases and even metabolic syndrome. Although P2X4 remains poorly characterized, more studies are needed as it is likely to be a potential therapeutic target in these multiple pathologies.
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Affiliation(s)
- Jaanus Suurväli
- Department of Chemistry and Biotechnology, Tallinn University of Technology, Tallinn, Estonia
| | - Pierre Boudinot
- Virologie et Immunologie Moléculaires, INRA, Université Paris-Saclay, Jouy-en-Josas, France
| | - Jean Kanellopoulos
- Institute for Integrative Biology of the Cell (I2BC) CEA, CNRS, Univ. Paris-Sud, Université Paris-Saclay, Gif-sur-Yvette cedex, France
| | - Sirje Rüütel Boudinot
- Department of Chemistry and Biotechnology, Tallinn University of Technology, Tallinn, Estonia.
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64
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Muller MS, Taylor CW. ATP evokes Ca 2+ signals in cultured foetal human cortical astrocytes entirely through G protein-coupled P2Y receptors. J Neurochem 2017; 142:876-885. [PMID: 28677119 PMCID: PMC5601250 DOI: 10.1111/jnc.14119] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Revised: 05/15/2017] [Accepted: 06/29/2017] [Indexed: 01/07/2023]
Abstract
Extracellular ATP plays important roles in coordinating the activities of astrocytes and neurons, and aberrant signalling is associated with neurodegenerative diseases. In rodents, ATP stimulates opening of Ca2+‐permeable channels formed by P2X receptor subunits in the plasma membrane. It is widely assumed, but not verified, that P2X receptors also evoke Ca2+ signals in human astrocytes. Here, we directly assess this hypothesis. We showed that cultured foetal cortical human astrocytes express mRNA for several P2X receptor subunits (P2X4, P2X5, P2X6) and G protein‐coupled P2Y receptors (P2Y1, P2Y2, P2Y6, P2Y11). In these astrocytes, ATP stimulated Ca2+ release from intracellular stores through IP3 receptors and store‐operated Ca2+ entry. These responses were entirely mediated by P2Y1 and P2Y2 receptors. Agonists of P2X receptors did not evoke Ca2+ signals, and nor did ATP when Ca2+ release from intracellular stores and store‐operated Ca2+ entry were inhibited. We conclude that ATP‐evoked Ca2+ signals in cultured human foetal astrocytes are entirely mediated by P2Y1 and P2Y2 receptors, with no contribution from P2X receptors. ![]()
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Affiliation(s)
- Margit S Muller
- Department of Pharmacology, University of Cambridge, Cambridge, UK
| | - Colin W Taylor
- Department of Pharmacology, University of Cambridge, Cambridge, UK
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65
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Methods for monitoring Ca 2+ and ion channels in the lysosome. Cell Calcium 2017; 64:20-28. [DOI: 10.1016/j.ceca.2016.12.001] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2016] [Revised: 12/07/2016] [Accepted: 12/07/2016] [Indexed: 12/22/2022]
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66
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Stokes L, Layhadi JA, Bibic L, Dhuna K, Fountain SJ. P2X4 Receptor Function in the Nervous System and Current Breakthroughs in Pharmacology. Front Pharmacol 2017; 8:291. [PMID: 28588493 PMCID: PMC5441391 DOI: 10.3389/fphar.2017.00291] [Citation(s) in RCA: 100] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Accepted: 05/05/2017] [Indexed: 12/18/2022] Open
Abstract
Adenosine 5′-triphosphate is a well-known extracellular signaling molecule and neurotransmitter known to activate purinergic P2X receptors. Information has been elucidated about the structure and gating of P2X channels following the determination of the crystal structure of P2X4 (zebrafish), however, there is still much to discover regarding the role of this receptor in the central nervous system (CNS). In this review we provide an overview of what is known about P2X4 expression in the CNS and discuss evidence for pathophysiological roles in neuroinflammation and neuropathic pain. Recent advances in the development of pharmacological tools including selective antagonists (5-BDBD, PSB-12062, BX430) and positive modulators (ivermectin, avermectins, divalent cations) of P2X4 will be discussed.
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Affiliation(s)
- Leanne Stokes
- School of Pharmacy, University of East Anglia, Norwich Research ParkNorwich, United Kingdom.,School of Biomedical and Health Sciences, RMIT University, BundooraVIC, Australia
| | - Janice A Layhadi
- Biomedical Research Centre, School of Biological Sciences, University of East AngliaNorwich, United Kingdom
| | - Lucka Bibic
- School of Pharmacy, University of East Anglia, Norwich Research ParkNorwich, United Kingdom
| | - Kshitija Dhuna
- School of Biomedical and Health Sciences, RMIT University, BundooraVIC, Australia
| | - Samuel J Fountain
- Biomedical Research Centre, School of Biological Sciences, University of East AngliaNorwich, United Kingdom
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67
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Inoue K. Neuropharmacological Study of ATP Receptors, Especially in the Relationship between Glia and Pain. YAKUGAKU ZASSHI 2017; 137:563-569. [DOI: 10.1248/yakushi.16-00262] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- Kazuhide Inoue
- Department of Molecular and System Pharmacology Graduate School of Pharmaceutical Sciences, Kyushu University
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68
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Recombinant tandem of pore-domains in a Weakly Inward rectifying K + channel 2 (TWIK2) forms active lysosomal channels. Sci Rep 2017; 7:649. [PMID: 28381826 PMCID: PMC5428834 DOI: 10.1038/s41598-017-00640-8] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2016] [Accepted: 03/07/2017] [Indexed: 12/27/2022] Open
Abstract
Recombinant TWIK2 channels produce weak basal background K+ currents. Current amplitudes depend on the animal species the channels have been isolated from and on the heterologous system used for their re-expression. Here we show that this variability is due to a unique cellular trafficking. We identified three different sequence signals responsible for the preferential expression of TWIK2 in the Lamp1-positive lysosomal compartment. Sequential inactivation of tyrosine-based (Y308ASIP) and di-leucine-like (E266LILL and D282EDDQVDIL) trafficking motifs progressively abolishes the targeting of TWIK2 to lysosomes, and promotes its functional relocation at the plasma membrane. In addition, TWIK2 contains two N-glycosylation sites (N79AS and N85AS) on its luminal side, and glycosylation is necessary for expression in lysosomes. As shown by electrophysiology and electron microscopy, TWIK2 produces functional background K+ currents in the endolysosomes, and its expression affects the number and mean size of the lysosomes. These results show that TWIK2 is expressed in lysosomes, further expanding the registry of ion channels expressed in these organelles.
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69
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Grimm C, Chen CC, Wahl-Schott C, Biel M. Two-Pore Channels: Catalyzers of Endolysosomal Transport and Function. Front Pharmacol 2017; 8:45. [PMID: 28223936 PMCID: PMC5293812 DOI: 10.3389/fphar.2017.00045] [Citation(s) in RCA: 61] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2016] [Accepted: 01/20/2017] [Indexed: 01/17/2023] Open
Abstract
Two-pore channels (TPCs) have recently emerged as a novel class of non-selective cation channels in the endolysosomal system. There are two members in the human genome, TPC1 and TPC2. Studies with TPC knockout and knockdown models have revealed that these channels participate in the regulation of multiple endolysosomal trafficking pathways which when dysregulated can lead to or influence the development of a range of different diseases such as lysosomal storage, metabolic, or infectious diseases. TPCs have been demonstrated to be activated by different endogenous stimuli, PI(3,5)P2 and NAADP, and ATP has been found to block TPC activation via mTOR. Loss of TPCs can lead to obesity and hypercholesterolemia, and to a slow-down of intracellular virus and bacterial toxin trafficking, it can affect VEGF-induced neoangiogenesis, autophagy, human hair pigmentation or the acrosome reaction in sperm. Moreover, physiological roles of TPCs in cardiac myocytes and pancreatic β cells have been postulated.
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Affiliation(s)
- Christian Grimm
- Center for Integrated Protein Science Munich, Ludwig Maximilian University of MunichMunich, Germany
- Department of Pharmacy – Center for Drug Research, Ludwig Maximilian University of MunichMunich, Germany
| | - Cheng-Chang Chen
- Center for Integrated Protein Science Munich, Ludwig Maximilian University of MunichMunich, Germany
- Department of Pharmacy – Center for Drug Research, Ludwig Maximilian University of MunichMunich, Germany
| | - Christian Wahl-Schott
- Center for Integrated Protein Science Munich, Ludwig Maximilian University of MunichMunich, Germany
- Department of Pharmacy – Center for Drug Research, Ludwig Maximilian University of MunichMunich, Germany
| | - Martin Biel
- Center for Integrated Protein Science Munich, Ludwig Maximilian University of MunichMunich, Germany
- Department of Pharmacy – Center for Drug Research, Ludwig Maximilian University of MunichMunich, Germany
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70
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INOUE K. Purinergic signaling in microglia in the pathogenesis of neuropathic pain. PROCEEDINGS OF THE JAPAN ACADEMY. SERIES B, PHYSICAL AND BIOLOGICAL SCIENCES 2017; 93:174-182. [PMID: 28413195 PMCID: PMC5489427 DOI: 10.2183/pjab.93.011] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Nerve injury often causes debilitating chronic pain, referred to as neuropathic pain, which is refractory to currently available analgesics including morphine. Many reports indicate that activated spinal microglia evoke neuropathic pain. The P2X4 receptor (P2X4R), a subtype of ionotropic ATP receptors, is upregulated in spinal microglia after nerve injury by several factors, including CC chemokine receptor CCR2, the extracellular matrix protein fibronectin in the spinal cord, interferon regulatory factor 8 (IRF8) and IRF5. Inhibition of P2X4R function suppresses neuropathic pain, indicating that microglial P2X4R play a key role in evoking neuropathic pain.
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Affiliation(s)
- Kazuhide INOUE
- Department of Molecular and System Pharmacology, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan
- Correspondence should be addressed: K. Inoue, Department of Molecular and System Pharmacology, Graduate School of Pharmaceutical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan (e-mail: )
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71
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Turner CT, Fuller M, Hopwood JJ, Meikle PJ, Brooks DA. Drug induced exocytosis of glycogen in Pompe disease. Biochem Biophys Res Commun 2016; 479:721-727. [PMID: 27693584 DOI: 10.1016/j.bbrc.2016.09.145] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2016] [Accepted: 09/27/2016] [Indexed: 01/11/2023]
Abstract
Pompe disease is caused by a deficiency in the lysosomal enzyme α-glucosidase, and this leads to glycogen accumulation in the autolysosomes of patient cells. Glycogen storage material is exocytosed at a basal rate in cultured Pompe cells, with one study showing up to 80% is released under specific culture conditions. Critically, exocytosis induction may reduce glycogen storage in Pompe patients, providing the basis for a therapeutic strategy whereby stored glycogen is redirected to an extracellular location and subsequently degraded by circulating amylases. The focus of the current study was to identify compounds capable of inducing rapid glycogen exocytosis in cultured Pompe cells. Here, calcimycin, lysophosphatidylcholine and α-l-iduronidase each significantly increased glycogen exocytosis compared to vehicle-treated controls. The most effective compound, calcimycin, induced exocytosis through a Ca2+-dependent mechanism, although was unable to release a pool of vesicular glycogen larger than the calcimycin-induced exocytic pore. There was reduced glycogen release from Pompe compared to unaffected cells, primarily due to increased granule size in Pompe cells. Drug induced exocytosis therefore shows promise as a therapeutic approach for Pompe patients but strategies are required to enhance the release of large molecular weight glycogen granules.
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Affiliation(s)
- Christopher T Turner
- Regenerative Medicine, Future Industries Institute, University of South Australia, Adelaide, Australia
| | - Maria Fuller
- Genetics and Molecular Pathology, SA Pathology, Adelaide, Australia
| | - John J Hopwood
- Lysosomal Diseases Research Unit, SA Health and Medical Research Institute, Adelaide, Australia
| | - Peter J Meikle
- Baker IDI Heart and Diabetes Institute, Melbourne, Australia
| | - Doug A Brooks
- Mechanisms in Cell Biology and Diseases Research Group, School of Pharmacy and Medical Science, Division of Health Sciences, University of South Australia, Adelaide 5001, Australia.
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72
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Besnard A, Gautherot J, Julien B, Tebbi A, Garcin I, Doignon I, Péan N, Gonzales E, Cassio D, Grosse B, Liu B, Safya H, Cauchois F, Humbert L, Rainteau D, Tordjmann T. The P2X4 purinergic receptor impacts liver regeneration after partial hepatectomy in mice through the regulation of biliary homeostasis. Hepatology 2016; 64:941-53. [PMID: 27301647 DOI: 10.1002/hep.28675] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/20/2016] [Accepted: 05/25/2016] [Indexed: 02/06/2023]
Abstract
UNLABELLED Many regulatory pathways are involved in liver regeneration after partial hepatectomy (PH), to initiate growth, protect liver cells, and sustain remnant liver functions. Extracellular adenosine triphosphate rises in blood and bile after PH and contributes to liver regeneration, although purinergic receptors and mechanisms remain to be precisely explored. In this work we analyzed during regeneration after PH the involvement of P2X4 purinergic receptors, highly expressed in the liver. P2X4 receptor expression in the liver, liver histology, hepatocyte proliferation, plasma bile acid concentration, bile flow and composition, and lysosome distribution in hepatocytes were studied in wild-type and P2X4 knockout (KO) mice, before and after PH. P2X4 receptors were expressed in hepatocytes and Kupffer cells; in hepatocytes, P2X4 was concentrated in subcanalicular areas closely costained with lysosomal markers. After PH, delayed regeneration, hepatocyte necrosis, and cholestasis were observed in P2X4-KO mice. In P2X4-KO mice, post-PH biliary adaptation was impaired with a smaller increase in bile flow and HCO3 (-) biliary output, as well as altered biliary composition with reduced adenosine triphosphate and lysosomal enzyme release. In line with these data, lysosome distribution and biogenesis were altered in P2X4-KO compared with wild-type mice. CONCLUSION During liver regeneration after PH, P2X4 contributes to the complex control of biliary homeostasis through mechanisms involving pericanalicular lysosomes, with a resulting impact on hepatocyte protection and proliferation. (Hepatology 2016;64:941-953).
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Affiliation(s)
- Aurore Besnard
- INSERM U1174, Université Paris Sud, Orsay, France.,Université Paris Sud, Orsay, France.,UPMC, Université Paris 06, Paris, France
| | - Julien Gautherot
- INSERM U1174, Université Paris Sud, Orsay, France.,Université Paris Sud, Orsay, France
| | - Boris Julien
- INSERM U1174, Université Paris Sud, Orsay, France.,Université Paris Sud, Orsay, France
| | - Ali Tebbi
- INSERM U1174, Université Paris Sud, Orsay, France.,Université Paris Sud, Orsay, France
| | - Isabelle Garcin
- INSERM U1174, Université Paris Sud, Orsay, France.,Université Paris Sud, Orsay, France
| | - Isabelle Doignon
- INSERM U1174, Université Paris Sud, Orsay, France.,Université Paris Sud, Orsay, France
| | - Noémie Péan
- INSERM U1174, Université Paris Sud, Orsay, France.,Université Paris Sud, Orsay, France
| | - Emmanuel Gonzales
- INSERM U1174, Université Paris Sud, Orsay, France.,Université Paris Sud, Orsay, France.,Hépatologie pédiatrique, Hôpital du Kremlin Bicêtre, Le Kremlin Bicêtre, France
| | - Doris Cassio
- INSERM U1174, Université Paris Sud, Orsay, France.,Université Paris Sud, Orsay, France
| | - Brigitte Grosse
- INSERM U1174, Université Paris Sud, Orsay, France.,Université Paris Sud, Orsay, France
| | - Bingkaï Liu
- INSERM U1174, Université Paris Sud, Orsay, France.,Université Paris Sud, Orsay, France
| | - Hanaa Safya
- INSERM U1174, Université Paris Sud, Orsay, France.,Université Paris Sud, Orsay, France
| | - Florent Cauchois
- INSERM U1174, Université Paris Sud, Orsay, France.,Université Paris Sud, Orsay, France
| | - Lydie Humbert
- UPMC, Université Paris 06, Paris, France.,ERL INSERM U 1057, Faculté de Médecine Pierre et Marie Curie, Paris, France
| | - Dominique Rainteau
- UPMC, Université Paris 06, Paris, France.,ERL INSERM U 1057, Faculté de Médecine Pierre et Marie Curie, Paris, France
| | - Thierry Tordjmann
- INSERM U1174, Université Paris Sud, Orsay, France.,Université Paris Sud, Orsay, France
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73
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Xu J, Bernstein AM, Wong A, Lu XH, Khoja S, Yang XW, Davies DL, Micevych P, Sofroniew MV, Khakh BS. P2X4 Receptor Reporter Mice: Sparse Brain Expression and Feeding-Related Presynaptic Facilitation in the Arcuate Nucleus. J Neurosci 2016; 36:8902-20. [PMID: 27559172 PMCID: PMC4995303 DOI: 10.1523/jneurosci.1496-16.2016] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2016] [Revised: 06/17/2016] [Accepted: 06/20/2016] [Indexed: 11/21/2022] Open
Abstract
UNLABELLED P2X4 receptors are ATP-gated cation channels that are widely expressed in the nervous system. To identify P2X4 receptor-expressing cells, we generated BAC transgenic mice expressing tdTomato under the control of the P2X4 receptor gene (P2rx4). We found sparse populations of tdTomato-positive neurons in most brain areas with patterns that matched P2X4 mRNA distribution. tdTomato expression within microglia was low but was increased by an experimental manipulation that triggered microglial activation. We found surprisingly high tdTomato expression in the hypothalamic arcuate nucleus (Arc) (i.e., within parts of the neural circuitry controlling feeding). Immunohistochemistry and genetic crosses of P2rx4 tdTomato mice with cell-specific GFP reporter lines showed that the tdTomato-expressing cells were mainly AgRP-NPY neurons and tanycytes. There was no electrophysiological evidence for functional expression of P2X4 receptors on AgRP-NPY neuron somata, but instead, we found clear evidence for functional presynaptic P2X4 receptor-mediated responses in terminals of AgRP-NPY neurons onto two of their postsynaptic targets (Arc POMC and paraventricular nucleus neurons), where ATP dramatically facilitated GABA release. The presynaptic responses onto POMC neurons, and the expression of tdTomato in AgRP-NPY neurons and tanycytes, were significantly decreased by food deprivation in male mice in a manner that was partially reversed by the satiety-related peptide leptin. Overall, we provide well-characterized tdTomato reporter mice to study P2X4-expressing cells in the brain, new insights on feeding-related regulation of presynaptic P2X4 receptor responses, and the rationale to explore extracellular ATP signaling in the control of feeding behaviors. SIGNIFICANCE STATEMENT Cells expressing ATP-gated P2X4 receptors have proven problematic to identify and study in brain slice preparations because P2X4 expression is sparse. To address this limitation, we generated and characterized BAC transgenic P2rx4 tdTomato reporter mice. We report the distribution of tdTomato-expressing cells throughout the brain and particularly strong expression in the hypothalamic arcuate nucleus. Together, our studies provide a new, well-characterized tool with which to study P2X4 receptor-expressing cells. The electrophysiological studies enabled by this mouse suggest previously unanticipated roles for ATP and P2X4 receptors in the neural circuitry controlling feeding.
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Affiliation(s)
- Ji Xu
- Departments of Physiology and
| | - Alexander M Bernstein
- Neurobiology, David Geffen School of Medicine, University of California-Los Angeles, Los Angeles, California 90095
| | - Angela Wong
- Neurobiology, David Geffen School of Medicine, University of California-Los Angeles, Los Angeles, California 90095
| | - Xiao-Hong Lu
- Center for Neurobehavioral Genetics, Semel Institute for Neuroscience and Human Behavior, University of California-Los Angeles, Los Angeles, California 90095
| | - Sheraz Khoja
- Department of Pharmacology and Pharmaceutical Sciences, University of Southern California, Los Angeles, California 90089
| | - X William Yang
- Center for Neurobehavioral Genetics, Semel Institute for Neuroscience and Human Behavior, University of California-Los Angeles, Los Angeles, California 90095, Department of Psychiatry and Biobehavioral Sciences, David Geffen School of Medicine, University of California-Los Angeles, Los Angeles, California 90095, and
| | - Daryl L Davies
- Titus Family Department of Clinical Pharmacy, School of Pharmacy, University of Southern California, Los Angeles, California 90089
| | - Paul Micevych
- Neurobiology, David Geffen School of Medicine, University of California-Los Angeles, Los Angeles, California 90095
| | - Michael V Sofroniew
- Neurobiology, David Geffen School of Medicine, University of California-Los Angeles, Los Angeles, California 90095
| | - Baljit S Khakh
- Departments of Physiology and Neurobiology, David Geffen School of Medicine, University of California-Los Angeles, Los Angeles, California 90095,
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74
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Morphine enhances IL-1β release through toll-like receptor 4-mediated endocytic pathway in microglia. Purinergic Signal 2016; 12:637-645. [PMID: 27506813 DOI: 10.1007/s11302-016-9525-4] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Accepted: 04/05/2016] [Indexed: 01/22/2023] Open
Abstract
Morphine creates a neuroinflammatory response and enhances release of the proinflammatory cytokines like interleukin-1β (IL-1β), which compromises morphine analgesia as well as induces morphine tolerance. In this study, we attempted to investigate the mechanisms of morphine induced IL-1β synthesis and release. Microglial cells were treated with morphine (100 μM) once daily for 3 days. Control groups underwent the same procedure but received sterile saline injection instead of morphine. Toll-like receptor 4 (TLR4) and P2X4 receptor (P2X4R) signaling were analyzed using Western blot; immunofluorescence was used to detect the signaling of CD68; real-time RT-PCR and ELISA kit was used to measure the messenger RNA and protein synthesis and release level of IL-1β. Morphine enhanced IL-1β synthesis and P2X4R protein expression. TLR4 were responsible for morphine-induced IL-1β synthesis, while morphine-induced IL-1β release was via P2X4R. Morphine-induced IL-1β release is mediated by endocytosis of TLR4. These results indicated that TLR4 and P2X4R pathways mediated IL-1β synthesis and release in microglia followed chronic morphine. TLR4 internalization is the main mechanism of morphine-induced microglia activation and IL-1β release.
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75
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Regulation of lysosomal ion homeostasis by channels and transporters. SCIENCE CHINA-LIFE SCIENCES 2016; 59:777-91. [PMID: 27430889 PMCID: PMC5147046 DOI: 10.1007/s11427-016-5090-x] [Citation(s) in RCA: 73] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/06/2016] [Accepted: 06/02/2016] [Indexed: 02/05/2023]
Abstract
Lysosomes are the major organelles that carry out degradation functions. They integrate and digest materials compartmentalized by endocytosis, phagocytosis or autophagy. In addition to more than 60 hydrolases residing in the lysosomes, there are also ion channels and transporters that mediate the flux or transport of H+, Ca2+, Na+, K+, and Cl− across the lysosomal membranes. Defects in ionic exchange can lead to abnormal lysosome morphology, defective vesicle trafficking, impaired autophagy, and diseases such as neurodegeneration and lysosomal storage disorders. The latter are characterized by incomplete lysosomal digestion and accumulation of toxic materials inside enlarged intracellular vacuoles. In addition to degradation, recent studies have revealed the roles of lysosomes in metabolic pathways through kinases such as mechanistic target of rapamycin (mTOR) and transcriptional regulation through calcium signaling molecules such as transcription factor EB (TFEB) and calcineurin. Owing to the development of new approaches including genetically encoded fluorescence probes and whole endolysosomal patch clamp recording techniques, studies on lysosomal ion channels have made remarkable progress in recent years. In this review, we will focus on the current knowledge of lysosome-resident ion channels and transporters, discuss their roles in maintaining lysosomal function, and evaluate how their dysfunction can result in disease.
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76
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Tsuda M. P2 receptors, microglial cytokines and chemokines, and neuropathic pain. J Neurosci Res 2016; 95:1319-1329. [DOI: 10.1002/jnr.23816] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Revised: 05/19/2016] [Accepted: 06/13/2016] [Indexed: 01/12/2023]
Affiliation(s)
- Makoto Tsuda
- Department of Life Innovation, Department of Molecular and System Pharmacology, Graduate School of Pharmaceutical Sciences; Kyushu University; Fukuoka Japan
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77
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Abstract
Lysosomes are key acidic Ca2+ stores. The principle Ca2+-permeable channels of the lysosome are TRP mucolipins (TRPMLs) and NAADP-regulated two-pore channels (TPCs). Recent studies, reviewed in this collection, have linked numerous neurodegenerative diseases to both gain and loss of function of TRPMLs/TPCs, as well as to defects in acidic Ca2+ store content. These diseases span rare lysosomal storage disorders such as Mucolipidosis Type IV and Niemann-Pick disease, type C, through to more common ones such as Alzheimer and Parkinson disease. Cellular phenotypes, underpinned by endo-lysosomal trafficking defects, are reversed by chemical or molecular targeting of TRPMLs and TPCs. Lysosomal Ca2+ channels therefore emerge as potential druggable targets in combatting neurodegeneration.
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Affiliation(s)
- Sandip Patel
- Department of Cell and Developmental Biology, University College London, Gower Street, London WC1E 6BT
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78
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Abstract
The neurodegenerative movement disorder Parkinson disease (PD) is prevalent in the aged population. However, the underlying mechanisms that trigger disease are unclear. Increasing work implicates both impaired Ca2+ signalling and lysosomal dysfunction in neuronal demise. Here I aim to connect these distinct processes by exploring the evidence that lysosomal Ca2+ signalling is disrupted in PD. In particular, I highlight defects in lysosomal Ca2+ content and signalling through NAADP-regulated two-pore channels in patient fibroblasts harbouring mutations in the PD-linked genes, GBA1 and LRRK2. As an emerging contributor to PD pathogenesis, the lysosomal Ca2+ signalling apparatus could represent a novel therapeutic target.
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Affiliation(s)
- Bethan S Kilpatrick
- Department of Cell and Developmental Biology, University College London, London, WC1E 6BT, UK
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79
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Feng X, Yang J. Lysosomal Calcium in Neurodegeneration. MESSENGER (LOS ANGELES, CALIF. : PRINT) 2016; 5:56-66. [PMID: 29082116 PMCID: PMC5659362 DOI: 10.1166/msr.2016.1055] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Lysosomes are the central organelles responsible for macromolecule recycling in the cell. Lysosomal dysfunction is the primary cause of lysosomal storage diseases (LSDs), and contributes significantly to the pathogenesis of common neurodegenerative diseases. The lysosomes are also intracellular stores for calcium ions, one of the most common second messenger in the cell. Lysosomal Ca2+ is required for diverse cellular processes including signal transduction, vesicular trafficking, autophagy, nutrient sensing, exocytosis, and membrane repair. In this review, we first summarize some recent progresses in the studies of lysosome Ca2+ regulation, with a focus on the newly discovered lysosomal Ca2+ channels and the mechanisms of lysosomal Ca2+ store refilling. We then discuss how defects in lysosomal Ca2+ release and store maintenance cause lysosomal dysfunction and neurodegeneration.
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Affiliation(s)
- Xinghua Feng
- Collaborative Innovation Center of Yangtze River Delta Region Green Pharmaceuticals, College of Pharmaceutical Sciences, Zhejiang University of Technology, Hangzhou 310014, China
| | - Junsheng Yang
- Collaborative Innovation Center of Yangtze River Delta Region Green Pharmaceuticals, College of Pharmaceutical Sciences, Zhejiang University of Technology, Hangzhou 310014, China
- The Department of Molecular, Cellular, and Developmental Biology, University of Michigan, 3089 Natural Science Building (Kraus), 830 North University, Ann Arbor, MI 48109, USA
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80
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Hayashi Y, Morinaga S, Zhang J, Satoh Y, Meredith AL, Nakata T, Wu Z, Kohsaka S, Inoue K, Nakanishi H. BK channels in microglia are required for morphine-induced hyperalgesia. Nat Commun 2016; 7:11697. [PMID: 27241733 PMCID: PMC4895018 DOI: 10.1038/ncomms11697] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2015] [Accepted: 04/20/2016] [Indexed: 02/01/2023] Open
Abstract
Although morphine is a gold standard medication, long-term opioid use is associated with serious side effects, such as morphine-induced hyperalgesia (MIH) and anti-nociceptive tolerance. Microglia-to-neuron signalling is critically involved in pain hypersensitivity. However, molecules that control microglial cellular state under chronic morphine treatment remain unknown. Here we show that the microglia-specific subtype of Ca2+-activated K+ (BK) channel is responsible for generation of MIH and anti-nociceptive tolerance. We find that, after chronic morphine administration, an increase in arachidonic acid levels through the μ-opioid receptors leads to the sole activation of microglial BK channels in the spinal cord. Silencing BK channel auxiliary β3 subunit significantly attenuates the generation of MIH and anti-nociceptive tolerance, and increases neurotransmission after chronic morphine administration. Therefore, microglia-specific BK channels contribute to the generation of MIH and anti-nociceptive tolerance. Long-term use of opioids can lead to a paradoxical increase in pain sensitivity. Here, Hayashi et al. link activation of potassium channels on microglia with morphine-induced hyperalgesia and anti-nociceptive tolerance in mice.
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Affiliation(s)
- Yoshinori Hayashi
- Department of Aging Science and Pharmacology, Faculty of Dental Sciences, Kyushu University, Fukuoka 812-8582, Japan
| | - Saori Morinaga
- Department of Aging Science and Pharmacology, Faculty of Dental Sciences, Kyushu University, Fukuoka 812-8582, Japan
| | - Jing Zhang
- Department of Aging Science and Pharmacology, Faculty of Dental Sciences, Kyushu University, Fukuoka 812-8582, Japan
| | - Yasushi Satoh
- Department of Anesthesiology, National Defense Medical College, Tokorozawa 359-8513, Japan
| | - Andrea L Meredith
- Department of Physiology and Program in Neuroscience, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA
| | - Takahiro Nakata
- Department of Molecular and Cellular Anatomy, Faculty of Health Promotional Sciences, Tokoha University, Hamamatsu, Shizuoka 431-2102, Japan
| | - Zhou Wu
- Department of Aging Science and Pharmacology, Faculty of Dental Sciences, Kyushu University, Fukuoka 812-8582, Japan
| | - Shinichi Kohsaka
- Department of Neurochemistry, National Institute of Neuroscience, Kodaira, Tokyo 187-8502, Japan
| | - Kazuhide Inoue
- Department of Molecular and System Pharmacology, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka 812-8582, Japan.,AMED-CREST, Japan Agency for Medical Research and Development, 1-7-1, Otemachi, Chiyoda-ku, Tokyo 100-004, Japan
| | - Hiroshi Nakanishi
- Department of Aging Science and Pharmacology, Faculty of Dental Sciences, Kyushu University, Fukuoka 812-8582, Japan.,AMED-CREST, Japan Agency for Medical Research and Development, 1-7-1, Otemachi, Chiyoda-ku, Tokyo 100-004, Japan
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81
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Two-pore channels at the intersection of endolysosomal membrane traffic. Biochem Soc Trans 2016; 43:434-41. [PMID: 26009187 DOI: 10.1042/bst20140303] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Two-pore channels (TPCs) are ancient members of the voltage-gated ion channel superfamily that localize to acidic organelles such as lysosomes. The TPC complex is the proposed target of the Ca2+-mobilizing messenger NAADP, which releases Ca2+ from these acidic Ca2+ stores. Whereas details of TPC activation and native ion permeation remain unclear, a consensus has emerged around their function in regulating endolysosomal trafficking. This role is supported by recent proteomic data showing that TPCs interact with proteins controlling membrane organization and dynamics, including Rab GTPases and components of the fusion apparatus. Regulation of TPCs by PtdIns(3,5)P2 and/or NAADP (nicotinic acid adenine dinucleotide phosphate) together with their functional and physical association with Rab proteins provides a mechanism for coupling phosphoinositide and trafficking protein cues to local ion fluxes. Therefore, TPCs work at the regulatory cross-roads of (patho)physiological cues to co-ordinate and potentially deregulate traffic flow through the endolysosomal network. This review focuses on the native role of TPCs in trafficking and their emerging contributions to endolysosomal trafficking dysfunction.
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82
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Li S, Chen X, Li X, Geng X, Lin R, Li M, Sun J. Molecular characterization of purinergic receptor P2X4 involved in Japanese flounder (Paralichthys olivaceus) innate immune response and its interaction with ATP release channel Pannexin1. FISH & SHELLFISH IMMUNOLOGY 2015; 47:100-109. [PMID: 26321132 DOI: 10.1016/j.fsi.2015.08.029] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Revised: 08/25/2015] [Accepted: 08/26/2015] [Indexed: 06/04/2023]
Abstract
P2X4 receptor (P2X4R) is a member of trimeric ATP-gated receptor channel family. Despite the importance of P2X4R in innate immunity has been addressed in mammals, the immunological significance of P2X4R has not been characterized in fish. In the present study we identified a full-length P2X4R cDNA sequence from Japanese flounder Paralichthys olivaceus (termed poP2X4R) by RT-PCR and RACE approaches and analyzed its gene expression patterns under normal and immune challenge conditions. Qualitative RT-PCR analyses revealed that poP2X4R has a widespread distribution in all examined tissues but dominantly expressed in hepatopancreas. In Japanese flounder head kidney macrophages and peripheral blood lymphocytes, poP2X4R was rapidly and significantly up-regulated by the immune challenges of LPS, poly(I:C) and zymosan. In addition, poP2X4R was up-regulated in spleen, head kidney and gill tissues by Edwardsiella tarda infections. Furthermore, we showed that poP2X4R is a membrane glycoprotein which could interact with ATP release channel Pannexin1, an important component in extracellular ATP-activated purinergic signaling pathways involved in Japanese flounder innate immune response. From a comparative immunological point of view, our results have provided new evidence for the involvement of extracellular ATP-gated P2XRs in fish innate immunity.
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Affiliation(s)
- Shuo Li
- Tianjin Key Laboratory of Animal and Plant Resistance, College of Life Sciences, Tianjin Normal University, 393 West Binshui Road, Xiqing District, Tianjin 300387, China.
| | - Xiaoli Chen
- Tianjin Key Laboratory of Animal and Plant Resistance, College of Life Sciences, Tianjin Normal University, 393 West Binshui Road, Xiqing District, Tianjin 300387, China
| | - Xuejing Li
- Tianjin Key Laboratory of Animal and Plant Resistance, College of Life Sciences, Tianjin Normal University, 393 West Binshui Road, Xiqing District, Tianjin 300387, China
| | - Xuyun Geng
- Tianjin Center for Control and Prevention of Aquatic Animal Infectious Disease, 442 South Jiefang Road, Hexi District, Tianjin 300221, China
| | - Rongxin Lin
- Tianjin Key Laboratory of Animal and Plant Resistance, College of Life Sciences, Tianjin Normal University, 393 West Binshui Road, Xiqing District, Tianjin 300387, China
| | - Ming Li
- Tianjin Key Laboratory of Animal and Plant Resistance, College of Life Sciences, Tianjin Normal University, 393 West Binshui Road, Xiqing District, Tianjin 300387, China
| | - Jinsheng Sun
- Tianjin Key Laboratory of Animal and Plant Resistance, College of Life Sciences, Tianjin Normal University, 393 West Binshui Road, Xiqing District, Tianjin 300387, China.
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83
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Cao Q, Zhong XZ, Zou Y, Murrell-Lagnado R, Zhu MX, Dong XP. Calcium release through P2X4 activates calmodulin to promote endolysosomal membrane fusion. J Cell Biol 2015; 209:879-94. [PMID: 26101220 PMCID: PMC4477861 DOI: 10.1083/jcb.201409071] [Citation(s) in RCA: 100] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
P2X4 and calmodulin form a signaling complex in late endosomes and lysosomes that promotes fusion and vacuolation in a Ca2+-dependent fashion. Intra-endolysosomal Ca2+ release is required for endolysosomal membrane fusion with intracellular organelles. However, the molecular mechanisms for intra-endolysosomal Ca2+ release and the downstream Ca2+ targets involved in the fusion remain elusive. Previously, we demonstrated that endolysosomal P2X4 forms channels activated by luminal adenosine triphosphate in a pH-dependent manner. In this paper, we show that overexpression of P2X4, as well as increasing endolysosomal P2X4 activity by alkalinization of endolysosome lumen, promoted vacuole enlargement in cells and endolysosome fusion in a cell-free assay. These effects were prevented by inhibiting P2X4, expressing a dominant-negative P2X4 mutant, and disrupting the P2X4 gene. We further show that P2X4 and calmodulin (CaM) form a complex at endolysosomal membrane where P2X4 activation recruits CaM to promote fusion and vacuolation in a Ca2+-dependent fashion. Moreover, P2X4 activation-triggered fusion and vacuolation were suppressed by inhibiting CaM. Our data thus suggest a new molecular mechanism for endolysosomal membrane fusion involving P2X4-mediated endolysosomal Ca2+ release and subsequent CaM activation.
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Affiliation(s)
- Qi Cao
- Department of Physiology and Biophysics, Dalhousie University, Halifax B3H 4R2, Nova Scotia, Canada
| | - Xi Zoë Zhong
- Department of Physiology and Biophysics, Dalhousie University, Halifax B3H 4R2, Nova Scotia, Canada
| | - Yuanjie Zou
- Department of Physiology and Biophysics, Dalhousie University, Halifax B3H 4R2, Nova Scotia, Canada
| | - Ruth Murrell-Lagnado
- Department of Pharmacology, University of Cambridge, Cambridge CB2 1PD, England, UK
| | - Michael X Zhu
- Department of Integrative Biology and Pharmacology, The University of Texas Health Science Center at Houston, Houston, TX 77030
| | - Xian-Ping Dong
- Department of Physiology and Biophysics, Dalhousie University, Halifax B3H 4R2, Nova Scotia, Canada
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84
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Tsuda M, Inoue K. Neuron-microglia interaction by purinergic signaling in neuropathic pain following neurodegeneration. Neuropharmacology 2015; 104:76-81. [PMID: 26327676 DOI: 10.1016/j.neuropharm.2015.08.042] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2015] [Accepted: 08/24/2015] [Indexed: 01/23/2023]
Abstract
Neuropathic pain, a chronic pain condition following nerve damage and degeneration, involves aberrant excitability in the dorsal horn of the spinal cord. A growing body of evidence has shown that the aberrant excitability might not be a consequence merely of changes in neurons, but rather of multiple alterations in glial cells, such as microglia, the immune cells of the central nervous system. Extracellular nucleotides play an important role in neuron-microglia communication through purinergic P2X and P2Y receptors expressed in microglia. Importantly, inhibiting the function or expression of these microglial molecules suppresses aberrant excitability of dorsal horn neurons and neuropathic pain, suggesting a crucial role for microglial purinergic signaling in mechanisms of neuropathic pain. Here, we describe recent advances in the understanding of neuron-microglia interactions by purinergic signaling in neuropathic pain following neurodegeneration. This article is part of the Special Issue entitled 'Purines in Neurodegeneration and Neuroregeneration'.
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Affiliation(s)
- Makoto Tsuda
- Department of Life Innovation, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan.
| | - Kazuhide Inoue
- Department of Molecular and System Pharmacology, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan
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85
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Tsuda M. Microglia in the spinal cord and neuropathic pain. J Diabetes Investig 2015; 7:17-26. [PMID: 26813032 PMCID: PMC4718109 DOI: 10.1111/jdi.12379] [Citation(s) in RCA: 172] [Impact Index Per Article: 19.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Revised: 05/13/2015] [Accepted: 05/16/2015] [Indexed: 12/13/2022] Open
Abstract
In contrast to physiological pain, pathological pain is not dependent on the presence of tissue‐damaging stimuli. One type of pathological pain – neuropathic pain – is often a consequence of nerve injury or of diseases such as diabetes. Neuropathic pain can be agonizing, can persist over long periods and is often resistant to known painkillers. A growing body of evidence shows that many pathological processes within the central nervous system are mediated by complex interactions between neurons and glial cells. In the case of painful peripheral neuropathy, spinal microglia react and undergo a series of changes that directly influence the establishment of neuropathic pain states. After nerve damage, purinergic P2X4 receptors (non‐selective cation channels activated by extracellular adenosine triphosphate) are upregulated in spinal microglia in a manner that depends on the transcription factors interferon regulatory factor 8 and 5, both of which are expressed in microglia after peripheral nerve injury. P2X4 receptor expression on the cell surface of microglia is also regulated at the post‐translational level by signaling from CC chemokine receptor chemotactic cytokine receptor 2. Furthermore, spinal microglia in response to extracellular stimuli results in signal transduction through intracellular signaling cascades, such as mitogen‐activated protein kinases, p38 and extracellular signal‐regulated protein kinase. Importantly, inhibiting the function or expression of these microglial molecules suppresses the aberrant excitability of dorsal horn neurons and neuropathic pain. These findings show that spinal microglia are a central player in mechanisms for neuropathic pain, and might be a potential target for treating the chronic pain state.
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Affiliation(s)
- Makoto Tsuda
- Department of Life Innovation Graduate School of Pharmaceutical Sciences Kyushu University Fukuoka Japan
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86
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Intracellular expression of purinoceptors. Purinergic Signal 2015; 11:275-6. [PMID: 26009501 DOI: 10.1007/s11302-015-9455-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2015] [Accepted: 05/15/2015] [Indexed: 10/23/2022] Open
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87
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Neuland K, Frick M. Vesicular control of fusion pore expansion. Commun Integr Biol 2015; 8:e1018496. [PMID: 26479858 PMCID: PMC4594593 DOI: 10.1080/19420889.2015.1018496] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2015] [Revised: 02/02/2015] [Accepted: 02/07/2015] [Indexed: 11/16/2022] Open
Abstract
Exocytic post-fusion events play an important role determining the composition and quantity of cellular secretion. In particular, Ca2+-dependent regulation of fusion pore dilation/closure is a key regulator for fine-tuning vesicle content secretion. This requires a tight temporal and spatial integration of vesicle fusion with the PM, Ca2+ signals and translation of the Ca2+ signal into fusion pore dilation via auxiliary factors. Yet, it is still mostly elusive how this is achieved in slow and non-excitable secretory cells, where initial Ca2+ signals triggering fusions will abate before onset of the post-fusion phase. New results suggest, that the vesicles themselves provide the necessary itinerary to sense and link vesicle fusion to generation of local Ca2+ signals and fusion pore expansion.
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Affiliation(s)
- Kathrin Neuland
- Institute of General Physiology; University of Ulm ; Ulm, Germany
| | - Manfred Frick
- Institute of General Physiology; University of Ulm ; Ulm, Germany
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88
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Abstract
The role of the P2X7 receptor (P2X7R) is being explored with intensive interest in the context of normal bone physiology, bone-related diseases and, to an extent, bone cancer. In this review, we cover the current understanding of P2X7R regulation of bone cell formation, function and survival. We will discuss how the P2X7R drives lineage commitment of undifferentiated bone cell progenitors, the vital role of P2X7R activation in bone mineralisation and its relatively unexplored role in osteocyte function. We also review how P2X7R activation is imperative for osteoclast formation and its role in bone resorption via orchestrating osteoclast apoptosis. Variations in the gene for the P2X7R (P2RX7) have implications for P2X7R-mediated processes and we review the relevance of these genetic variations in bone physiology. Finally, we highlight how targeting P2X7R may have therapeutic potential in bone disease and cancer.
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Affiliation(s)
- Ankita Agrawal
- Department of Human MetabolismThe Mellanby Centre for Bone Research, The University of Sheffield, Beech Hill Road, Sheffield S10 2RX, UK
| | - Alison Gartland
- Department of Human MetabolismThe Mellanby Centre for Bone Research, The University of Sheffield, Beech Hill Road, Sheffield S10 2RX, UK
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89
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Evolution of acidic Ca2+ stores and their resident Ca2+-permeable channels. Cell Calcium 2015; 57:222-30. [DOI: 10.1016/j.ceca.2014.12.005] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2014] [Revised: 12/05/2014] [Accepted: 12/09/2014] [Indexed: 11/18/2022]
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90
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Shear stress modulates endothelial KLF2 through activation of P2X4. Purinergic Signal 2015; 11:139-53. [PMID: 25563726 DOI: 10.1007/s11302-014-9442-3] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2014] [Accepted: 12/16/2014] [Indexed: 12/11/2022] Open
Abstract
Vascular endothelial cells that are in direct contact with blood flow are exposed to fluid shear stress and regulate vascular homeostasis. Studies report endothelial cells to release ATP in response to shear stress that in turn modulates cellular functions via P2 receptors with P2X4 mediating shear stress-induced calcium signaling and vasodilation. A recent study shows that a loss-of-function polymorphism in the human P2X4 resulting in a Tyr315>Cys variant is associated with increased pulse pressure and impaired endothelial vasodilation. Although the importance of shear stress-induced Krüppel-like factor 2 (KLF2) expression in atheroprotection is well studied, whether ATP regulates KLF2 remains unanswered and is the objective of this study. Using an in vitro model, we show that in human umbilical vein endothelial cells (HUVECs), apyrase decreased shear stress-induced KLF2, KLF4, and NOS3 expression but not that of NFE2L2. Exposure of HUVECs either to shear stress or ATPγS under static conditions increased KLF2 in a P2X4-dependent manner as was evident with both the receptor antagonist and siRNA knockdown. Furthermore, transient transfection of static cultures of human endothelial cells with the Tyr315>Cys mutant P2X4 construct blocked ATP-induced KLF2 expression. Also, P2X4 mediated the shear stress-induced phosphorylation of extracellular regulated kinase-5, a known regulator of KLF2. This study demonstrates a major physiological finding that the shear-induced effects on endothelial KLF2 axis are in part dependent on ATP release and P2X4, a previously unidentified mechanism.
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91
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92
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Roger S, Jelassi B, Couillin I, Pelegrin P, Besson P, Jiang LH. Understanding the roles of the P2X7 receptor in solid tumour progression and therapeutic perspectives. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2014; 1848:2584-602. [PMID: 25450340 DOI: 10.1016/j.bbamem.2014.10.029] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2014] [Revised: 10/13/2014] [Accepted: 10/20/2014] [Indexed: 01/05/2023]
Abstract
P2X7 is an intriguing ionotropic receptor for which the activation by extracellular ATP induces rapid inward cationic currents and intracellular signalling pathways associated with numerous physiological processes such as the induction of the inflammatory cascade, the survival and proliferation of cells. In contrast, long-term stimulation of P2X7 is generally associated with membrane permeabilisation and cell death. Recently, P2X7 has attracted great attention in the cancer field, and particularly in the neoplastic transformation and the progression of solid tumours. A growing number of studies were published; however they often appeared contradictory in their results and conclusions. As such, the involvement of P2X7 in the oncogenic process remains unclear so far. The present review aims to discuss the current knowledge and hypotheses on the involvement of the P2X7 receptor in the development and progression of solid tumours, and highlight the different aspects that require further clarification in order to decipher whether P2X7 could be considered as a cancer biomarker or as a target for pharmacological intervention. This article is part of a Special Issue entitled: Membrane channels and transporters in cancers.
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Affiliation(s)
- Sébastien Roger
- Inserm UMR1069 Nutrition, Croissance et Cancer, Université François-Rabelais de Tours, 10 Boulevard Tonnellé, 37032 Tours, France; Département de Physiologie Animale, UFR Sciences et Techniques, Université François-Rabelais de Tours, Avenue Monge, 37200 Tours, France.
| | - Bilel Jelassi
- Inserm UMR1069 Nutrition, Croissance et Cancer, Université François-Rabelais de Tours, 10 Boulevard Tonnellé, 37032 Tours, France
| | - Isabelle Couillin
- UMR CNRS 7355 Experimental and Molecular Immunology and Neurogenetics, Université d'Orléans, 3B rue de la Ferollerie, F-45071 Orléans, France
| | - Pablo Pelegrin
- Inflammation and Experimental Surgery Research Unit, CIBERehd, Clinical University Hospital "Virgen de la Arrixaca", Murcia's BioHealth Research Institute IMIB-Arrixaca, Carretera Cartagena-Madrid s/n, 30120 Murcia, Spain
| | - Pierre Besson
- Inserm UMR1069 Nutrition, Croissance et Cancer, Université François-Rabelais de Tours, 10 Boulevard Tonnellé, 37032 Tours, France
| | - Lin-Hua Jiang
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, United Kingdom
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93
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Robinson LE, Shridar M, Smith P, Murrell-Lagnado RD. Plasma membrane cholesterol as a regulator of human and rodent P2X7 receptor activation and sensitization. J Biol Chem 2014; 289:31983-31994. [PMID: 25281740 PMCID: PMC4231676 DOI: 10.1074/jbc.m114.574699] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
P2X7 receptors are nonselective cation channels gated by high extracellular ATP, but with sustained activation, receptor sensitization occurs, whereby the intrinsic pore dilates, making the cell permeable to large organic cations, which eventually leads to cell death. P2X7 receptors associate with cholesterol-rich lipid rafts, but it is unclear how this affects the properties of the receptor channel. Here we show that pore-forming properties of human and rodent P2X7 receptors are sensitive to perturbations of cholesterol levels. Acute depletion of cholesterol with 5 mm methyl-β-cyclodextrin (MCD) caused a substantial increase in the rate of agonist-evoked pore formation, as measured by the uptake of ethidium dye, whereas cholesterol loading inhibited this process. Patch clamp analysis of P2X7 receptor currents carried by Na+ and N-methyl-d-glucamine (NMDG+) showed enhanced activation and current facilitation following cholesterol depletion. This contrasts with the inhibitory effect of methyl-β-cyclodextrin reported for other P2X subtypes. Mutational analysis suggests the involvement of an N-terminal region and a proximal C-terminal region that comprises multiple cholesterol recognition amino acid consensus (CRAC) motifs, in the cholesterol sensitivity of channel gating. These results reveal cholesterol as a negative regulator of P2X7 receptor pore formation, protecting cells from P2X7-mediated cell death.
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Affiliation(s)
- Lucy E Robinson
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, United Kingdom
| | - Mitesh Shridar
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, United Kingdom
| | - Philip Smith
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, United Kingdom
| | - Ruth D Murrell-Lagnado
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, United Kingdom.
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94
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Shen JB, Yang R, Pappano A, Liang BT. Cardiac P2X purinergic receptors as a new pathway for increasing Na⁺ entry in cardiac myocytes. Am J Physiol Heart Circ Physiol 2014; 307:H1469-77. [PMID: 25239801 DOI: 10.1152/ajpheart.00553.2014] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
P2X4 receptors (P2X4Rs) are ligand-gated ion channels capable of conducting cations such as Na(+). Endogenous cardiac P2X4R can mediate ATP-activated current in adult murine cardiomyocytes. In the present study, we tested the hypothesis that cardiac P2X receptors can induce Na(+) entry and modulate Na(+) handling. We further determined whether P2X receptor-induced stimulation of the Na(+)/Ca(2+) exchanger (NCX) has a role in modulating the cardiac contractile state. Changes in Na(+)-K(+)-ATPase current (Ip) and NCX current (INCX) after agonist stimulation were measured in ventricular myocytes of P2X4 transgenic mice using whole cell patch-clamp techniques. The agonist 2-methylthio-ATP (2-meSATP) increased peak Ip from a basal level of 0.52 ± 0.02 to 0.58 ± 0.03 pA/pF. 2-meSATP also increased the Ca(2+) entry mode of INCX (0.55 ± 0.09 pA/pF under control conditions vs. 0.82 ± 0.14 pA/pF with 2-meSATP) at a membrane potential of +50 mV. 2-meSATP shifted the reversal potential of INCX from -14 ± 2.3 to -25 ± 4.1 mV, causing an estimated intracellular Na(+) concentration increase of 1.28 ± 0.42 mM. These experimental results were closely mimicked by mathematical simulations based on previously established models. KB-R7943 or a structurally different agent preferentially opposing the Ca(2+) entry mode of NCX, YM-244769, could inhibit the 2-meSATP-induced increase in cell shortening in transgenic myocytes. Thus, the Ca(2+) entry mode of INCX participates in P2X agonist-stimulated contractions. In ventricular myocytes from wild-type mice, the P2X agonist could increase INCX, and KB-R7943 was able to inhibit the contractile effect of endogenous P2X4Rs, indicating a physiological role of these receptors in wild-type cells. The data demonstrate a novel Na(+) entry pathway through ligand-gated P2X4Rs in cardiomyocytes.
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Affiliation(s)
- Jian-Bing Shen
- Pat and Jim Calhoun Cardiology Center, University of Connecticut Medical Center, Farmington, Connecticut
| | - Ronghua Yang
- Pat and Jim Calhoun Cardiology Center, University of Connecticut Medical Center, Farmington, Connecticut
| | - Achilles Pappano
- Pat and Jim Calhoun Cardiology Center, University of Connecticut Medical Center, Farmington, Connecticut
| | - Bruce T Liang
- Pat and Jim Calhoun Cardiology Center, University of Connecticut Medical Center, Farmington, Connecticut
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95
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Gofman L, Cenna JM, Potula R. P2X4 receptor regulates alcohol-induced responses in microglia. J Neuroimmune Pharmacol 2014; 9:668-78. [PMID: 25135400 DOI: 10.1007/s11481-014-9559-8] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2014] [Accepted: 07/28/2014] [Indexed: 12/18/2022]
Abstract
Mounting evidence indicates that alcohol-induced neuropathology may result from multicellular responses in which microglia cells play a prominent role. Purinergic receptor signaling plays a key role in regulating microglial function and, more importantly, mediates alcohol-induced effects. Our findings demonstrate that alcohol increases expression of P2X4 receptor (P2X4R), which alters the function of microglia, including calcium mobilization, migration and phagocytosis. Our results show a significant up-regulation of P2X4 gene expression as analyzed by real-time qPCR (***p < 0.002) and protein expression as analyzed by flow cytometry (**p < 0.004) in embryonic stem cell-derived microglial cells (ESdM) after 48 hours of alcohol treatment, as compared to untreated controls. Calcium mobilization in ethanol treated ESdM cells was found to be P2X4R dependent using 5-BDBD, a P2X4R selective antagonist. Alcohol decreased migration of microglia towards fractalkine (CX3CL1) by 75 % following 48 h of treatment compared to control (***p < 0.001). CX3CL1-dependent migration was confirmed to be P2X4 receptor-dependent using the antagonist 5-BDBD, which reversed the effects as compared to alcohol alone (***p < 0.001). Similarly, 48 h of alcohol treatment significantly decreased phagocytosis of microglia by 15 % compared to control (*p < 0.05). 5-BDBD pre-treatment prior to alcohol treatment significantly increased microglial phagocytosis (***p < 0.001). Blocking P2X4R signaling with 5-BDBD decreased the level of calcium mobilization compared to ethanol treatment alone. These findings demonstrate that P2X4 receptor may play a role in modulating microglial function in the context of alcohol abuse.
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Affiliation(s)
- Larisa Gofman
- Department of Pathology and Laboratory Medicine, Temple University School of Medicine, 3500 N. Broad Street, MERB 845A, Philadelphia, PA, 19140, USA
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96
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Xu J, Chai H, Ehinger K, Egan TM, Srinivasan R, Frick M, Khakh BS. Imaging P2X4 receptor subcellular distribution, trafficking, and regulation using P2X4-pHluorin. ACTA ACUST UNITED AC 2014; 144:81-104. [PMID: 24935743 PMCID: PMC4076521 DOI: 10.1085/jgp.201411169] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
A P2X4 receptor labeled with the pH-sensitive GFP superecliptic pHluorin represents a useful probe to investigate P2X4 receptor distribution, trafficking, and up-regulation. P2X4 receptors are adenosine triphosphate (ATP)-gated cation channels present on the plasma membrane (PM) and also within intracellular compartments such as vesicles, vacuoles, lamellar bodies (LBs), and lysosomes. P2X4 receptors in microglia are up-regulated in epilepsy and in neuropathic pain; that is to say, their total and/or PM expression levels increase. However, the mechanisms underlying up-regulation of microglial P2X4 receptors remain unclear, in part because it has not been possible to image P2X4 receptor distribution within, or trafficking between, cellular compartments. Here, we report the generation of pH-sensitive fluorescently tagged P2X4 receptors that permit evaluations of cell surface and total receptor pools. Capitalizing on information gained from zebrafish P2X4.1 crystal structures, we designed a series of mouse P2X4 constructs in which a pH-sensitive green fluorescent protein, superecliptic pHluorin (pHluorin), was inserted into nonconserved regions located within flexible loops of the P2X4 receptor extracellular domain. One of these constructs, in which pHluorin was inserted after lysine 122 (P2X4-pHluorin123), functioned like wild-type P2X4 in terms of its peak ATP-evoked responses, macroscopic kinetics, calcium flux, current–voltage relationship, and sensitivity to ATP. P2X4-pHluorin123 also showed pH-dependent fluorescence changes, and was robustly expressed on the membrane and within intracellular compartments. P2X4-pHluorin123 identified cell surface and intracellular fractions of receptors in HEK-293 cells, hippocampal neurons, C8-B4 microglia, and alveolar type II (ATII) cells. Furthermore, it showed that the subcellular fractions of P2X4-pHluorin123 receptors were cell and compartment specific, for example, being larger in hippocampal neuron somata than in C8-B4 cell somata, and larger in C8-B4 microglial processes than in their somata. In ATII cells, P2X4-pHluorin123 showed that P2X4 receptors were secreted onto the PM when LBs undergo exocytosis. Finally, the use of P2X4-pHluorin123 showed that the modulator ivermectin did not increase the PM fraction of P2X4 receptors and acted allosterically to potentiate P2X4 receptor responses. Collectively, our data suggest that P2X4-pHluorin123 represents a useful optical probe to quantitatively explore P2X4 receptor distribution, trafficking, and up-regulation.
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Affiliation(s)
- Ji Xu
- Department of Physiology and Department of Neurobiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095
| | - Hua Chai
- Department of Physiology and Department of Neurobiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095
| | | | - Terrance M Egan
- Department of Pharmacological and Physiological Science and The Center for Excellence in Neuroscience, Saint Louis University School of Medicine, St. Louis, MO 63130 Department of Pharmacological and Physiological Science and The Center for Excellence in Neuroscience, Saint Louis University School of Medicine, St. Louis, MO 63130
| | - Rahul Srinivasan
- Department of Physiology and Department of Neurobiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095
| | - Manfred Frick
- Institute of General Physiology, University of Ulm, 89081 Ulm, Germany
| | - Baljit S Khakh
- Department of Physiology and Department of Neurobiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095Department of Physiology and Department of Neurobiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095
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97
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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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98
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Huang P, Zou Y, Zhong XZ, Cao Q, Zhao K, Zhu MX, Murrell-Lagnado R, Dong XP. P2X4 forms functional ATP-activated cation channels on lysosomal membranes regulated by luminal pH. J Biol Chem 2014; 289:17658-67. [PMID: 24817123 DOI: 10.1074/jbc.m114.552158] [Citation(s) in RCA: 92] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
P2X receptors are commonly known as plasma membrane cation channels involved in a wide variety of cell functions. The properties of these channels have been extensively studied on the plasma membrane. However, studies in amoeba suggest that P2X receptors are also present intracellularly and involved in vesicle fusion with the plasma membrane. Recently, it was shown that in addition to plasma membrane expression, mammalian P2X4 was also localized intracellularly in lysosomes. However, it was not clear whether the lysosomal P2X4 receptors function as channels and how they are activated and regulated. In this paper, we show that both P2X4 and its natural ligand, ATP, are enriched in lysosomes of COS1 and HEK293 cells. By directly recording membrane currents from enlarged lysosomal vacuoles, we demonstrated that lysosomal P2X4 formed channels activated by ATP from the luminal side in a pH-dependent manner. While the acidic pH at the luminal side inhibited P2X4 activity, increasing the luminal pH in the presence of ATP caused P2X4 activation. We further showed that, as for the plasma membrane P2X4, the lysosomal P2X4 was potentiated by ivermectin but insensitive to suramin and PPADS, and it permeated the large cation N-methyl-d-glucamine upon activation. Our data suggest that P2X4 forms functional ATP-activated cation channels on lysosomal membranes regulated by luminal pH. Together with the reported fusion effect of intracellular P2X in lower organisms, we speculate that the lysosome-localized P2X4 may play specific roles in membrane trafficking of acidic organelles in mammalian cells.
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Affiliation(s)
- Peng Huang
- From the Department of Physiology and Biophysics, Dalhousie University, Sir Charles Tupper Medical Building, 5850 College Street, Halifax, Nova Scotia B3H 4R2, Canada
| | - Yuanjie Zou
- From the Department of Physiology and Biophysics, Dalhousie University, Sir Charles Tupper Medical Building, 5850 College Street, Halifax, Nova Scotia B3H 4R2, Canada
| | - Xi Zoë Zhong
- From the Department of Physiology and Biophysics, Dalhousie University, Sir Charles Tupper Medical Building, 5850 College Street, Halifax, Nova Scotia B3H 4R2, Canada
| | - Qi Cao
- From the Department of Physiology and Biophysics, Dalhousie University, Sir Charles Tupper Medical Building, 5850 College Street, Halifax, Nova Scotia B3H 4R2, Canada
| | - Kexin Zhao
- From the Department of Physiology and Biophysics, Dalhousie University, Sir Charles Tupper Medical Building, 5850 College Street, Halifax, Nova Scotia B3H 4R2, Canada
| | - Michael X Zhu
- the Department of Integrative Biology and Pharmacology, The University of Texas Health Science Center at Houston, Houston, Texas 77030, and
| | - Ruth Murrell-Lagnado
- the Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, United Kingdom
| | - Xian-Ping Dong
- From the Department of Physiology and Biophysics, Dalhousie University, Sir Charles Tupper Medical Building, 5850 College Street, Halifax, Nova Scotia B3H 4R2, Canada,
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99
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Inoue K. [Neuropharmacological study of ATP receptors and their role in neuropathic pain]. YAKUGAKU ZASSHI 2014; 133:1035-9. [PMID: 24088347 DOI: 10.1248/yakushi.13-00191] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A growing body of evidence indicates that extracellular nucleotides released or leaked from non-excitable cells as well as neurons play important roles in the regulation of neuronal and glial functions in the whole body through ATP receptors. ATP receptors (ionotropic P2X and metabotropic P2Y receptors) are the most abundant receptor families in living organisms. In the central nervous system, these receptors participate in synaptic transmission and in intercellular communications between neurons and glia. Glia cells are classified into astrocytes, oligodendrocytes and microglia. There are many reports on the role of ATP receptors (P2X4, P2X7, P2Y6 and P2Y12 receptors) expressed in spinal microglia. We have reported that several molecules presumably activate microglia in neuropathic pain after peripheral nerve injury. P2X4 receptors expressed in microglia in particular play a critical role in neuropathic pain signaling. The expression and activity of P2X4 receptors are up-regulated and enhanced predominantly in activated microglia in the spinal cord where damaged sensory fibers project. These findings provide novel targets for developing new medicines to treat neuropathic pain.
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Affiliation(s)
- Kazuhide Inoue
- Department of Molecular and System Pharmacology, Graduate School of Pharmaceutical Sciences, Kyushu University
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100
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Bourinet E, Altier C, Hildebrand ME, Trang T, Salter MW, Zamponi GW. Calcium-permeable ion channels in pain signaling. Physiol Rev 2014; 94:81-140. [PMID: 24382884 DOI: 10.1152/physrev.00023.2013] [Citation(s) in RCA: 221] [Impact Index Per Article: 22.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The detection and processing of painful stimuli in afferent sensory neurons is critically dependent on a wide range of different types of voltage- and ligand-gated ion channels, including sodium, calcium, and TRP channels, to name a few. The functions of these channels include the detection of mechanical and chemical insults, the generation of action potentials and regulation of neuronal firing patterns, the initiation of neurotransmitter release at dorsal horn synapses, and the ensuing activation of spinal cord neurons that project to pain centers in the brain. Long-term changes in ion channel expression and function are thought to contribute to chronic pain states. Many of the channels involved in the afferent pain pathway are permeable to calcium ions, suggesting a role in cell signaling beyond the mere generation of electrical activity. In this article, we provide a broad overview of different calcium-permeable ion channels in the afferent pain pathway and their role in pain pathophysiology.
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