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Diego García L, Sebastián-Serrano Á, Hernández IH, Pintor J, Lucas JJ, Díaz-Hernández M. The regulation of proteostasis in glial cells by nucleotide receptors is key in acute neuroinflammation. FASEB J 2018; 32:3020-3032. [DOI: 10.1096/fj.201701064rr] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Affiliation(s)
- Laura Diego García
- Department of Biochemistry and Molecular BiologyFaculty of Optic and OptometryUniversidad Complutense of Madrid Madrid Spain
- Instituto de Investigación Sanitaria del Hospital Clínico San Carlos (IdlSSC) Madrid Spain
| | - Álvaro Sebastián-Serrano
- Department of Biochemistry and Molecular BiologyFaculty of Optic and OptometryUniversidad Complutense of Madrid Madrid Spain
- Instituto de Investigación Sanitaria del Hospital Clínico San Carlos (IdlSSC) Madrid Spain
- Instituto de Investigaciones Biomedicas “Alberto Sols, ” Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid (CSIC–UAM) Madrid Spain
- Centro de Investigacioí n Biomeí dica en Red sobre Enfermedades Neurodegenerativas (CIBERNED)Instituto de Salud Carlos III Madrid Spain
| | - Ivó H. Hernández
- Centro de Biología Molecular Severo OchoaConsejo Superior de Investigaciones Científicas–Universidad Autónoma de Madrid (CSIC–UAM) Madrid Spain
- Departamento de BiologíaFacultad de CienciasUAM Madrid Spain
- Networking Research Center on Neurodegenerative Diseases (CIBERNED)Instituto de Salud Carlos III Madrid Spain
| | - Jesús Pintor
- Faculty of Optic and OptometryUniversidad Complutense of Madrid Madrid Spain
| | - José J. Lucas
- Centro de Biología Molecular Severo OchoaConsejo Superior de Investigaciones Científicas–Universidad Autónoma de Madrid (CSIC–UAM) Madrid Spain
- Departamento de BiologíaFacultad de CienciasUAM Madrid Spain
| | - Miguel Díaz-Hernández
- Department of Biochemistry and Molecular BiologyFaculty of Optic and OptometryUniversidad Complutense of Madrid Madrid Spain
- Instituto de Investigación Sanitaria del Hospital Clínico San Carlos (IdlSSC) Madrid Spain
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2
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Horakova D, Cela P, Krejci P, Balek L, Moravcova Balkova S, Matalova E, Buchtova M. Effect of FGFR inhibitors on chicken limb development. Dev Growth Differ 2014; 56:555-72. [DOI: 10.1111/dgd.12156] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2013] [Revised: 07/30/2014] [Accepted: 08/07/2014] [Indexed: 11/26/2022]
Affiliation(s)
- Dana Horakova
- Department of Anatomy, Histology and Embryology; Faculty of Veterinary Medicine; University of Veterinary and Pharmaceutical Sciences; Brno Czech Republic
| | - Petra Cela
- Institute of Animal Physiology and Genetics, v.v.i.; Academy of Sciences of the Czech Republic; Brno Czech Republic
- Department of Animal Physiology and Immunology; Institute of Experimental Biology; Masaryk University; Brno Czech Republic
| | - Pavel Krejci
- Department of Animal Physiology and Immunology; Institute of Experimental Biology; Masaryk University; Brno Czech Republic
- Department of Biology; Faculty of Medicine; Masaryk University; Brno Czech Republic
| | - Lukas Balek
- Department of Animal Physiology and Immunology; Institute of Experimental Biology; Masaryk University; Brno Czech Republic
- Department of Biology; Faculty of Medicine; Masaryk University; Brno Czech Republic
| | - Simona Moravcova Balkova
- Institute of Animal Physiology and Genetics, v.v.i.; Academy of Sciences of the Czech Republic; Brno Czech Republic
- Clinic of Stomatology, St. Anne's Faculty Hospital and Faculty of Medicine; Masaryk University; Brno Czech Republic
| | - Eva Matalova
- Institute of Animal Physiology and Genetics, v.v.i.; Academy of Sciences of the Czech Republic; Brno Czech Republic
- Department of Physiology; Faculty of Veterinary Medicine; University of Veterinary and Pharmaceutical Sciences; Brno Czech Republic
| | - Marcela Buchtova
- Department of Anatomy, Histology and Embryology; Faculty of Veterinary Medicine; University of Veterinary and Pharmaceutical Sciences; Brno Czech Republic
- Institute of Animal Physiology and Genetics, v.v.i.; Academy of Sciences of the Czech Republic; Brno Czech Republic
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3
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Weisman GA, Camden JM, Peterson TS, Ajit D, Woods LT, Erb L. P2 receptors for extracellular nucleotides in the central nervous system: role of P2X7 and P2Y₂ receptor interactions in neuroinflammation. Mol Neurobiol 2012; 46:96-113. [PMID: 22467178 DOI: 10.1007/s12035-012-8263-z] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2012] [Accepted: 03/21/2012] [Indexed: 12/16/2022]
Abstract
Extracellular nucleotides induce cellular responses in the central nervous system (CNS) through the activation of ionotropic P2X and metabotropic P2Y nucleotide receptors. Activation of these receptors regulates a wide range of physiological and pathological processes. In this review, we present an overview of the current literature regarding P2X and P2Y receptors in the CNS with a focus on the contribution of P2X7 and P2Y(2) receptor-mediated responses to neuroinflammatory and neuroprotective mechanisms.
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Affiliation(s)
- Gary A Weisman
- Department of Biochemistry, University of Missouri, 540E Life Sciences Center, 1201 Rollins Road, Columbia, MO 65211-7310, USA.
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4
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Tanaka K, Swanson SJ, Gilroy S, Stacey G. Extracellular nucleotides elicit cytosolic free calcium oscillations in Arabidopsis. PLANT PHYSIOLOGY 2010; 154:705-19. [PMID: 20671112 PMCID: PMC2949047 DOI: 10.1104/pp.110.162503] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2010] [Accepted: 07/28/2010] [Indexed: 05/19/2023]
Abstract
Extracellular ATP induces a rise in the level of cytosolic free calcium ([Ca(2+)](cyt)) in plant cells. To expand our knowledge about the function of extracellular nucleotides in plants, the effects of several nucleotide analogs and pharmacological agents on [Ca(2+)](cyt) changes were studied using transgenic Arabidopsis (Arabidopsis thaliana) expressing aequorin or the fluorescence resonance energy transfer-based Ca(2+) sensor Yellow Cameleon 3.6. Exogenously applied CTP caused elevations in [Ca(2+)](cyt) that displayed distinct time- and dose-dependent kinetics compared with the purine nucleotides ATP and GTP. The inhibitory effects of antagonists of mammalian P2 receptors and calcium influx inhibitors on nucleotide-induced [Ca(2+)](cyt) elevations were distinct between CTP and purine nucleotides. These results suggest that distinct recognition systems may exist for the respective types of nucleotides. Interestingly, a mutant lacking the heterotrimeric G protein Gβ-subunit exhibited a remarkably higher [Ca(2+)](cyt) elevation in response to all tested nucleotides in comparison with the wild type. These data suggest a role for Gβ in negatively regulating extracellular nucleotide signaling and point to an important role for heterotrimeric G proteins in modulating the cellular effects of extracellular nucleotides. The addition of extracellular nucleotides induced multiple temporal [Ca(2+)](cyt) oscillations, which could be localized to specific root cells. The oscillations were attenuated by a vesicle-trafficking inhibitor, indicating that the oscillations likely require ATP release via exocytotic secretion. The results reveal new molecular details concerning extracellular nucleotide signaling in plants and the importance of fine control of extracellular nucleotide levels to mediate specific plant cell responses.
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Affiliation(s)
| | | | | | - Gary Stacey
- National Center for Soybean Biotechnology, Division of Plant Sciences (K.T., G.S.), and Division of Biochemistry (G.S.), University of Missouri, Columbia, Missouri 65211; Botany Department, University of Wisconsin, Madison, Wisconsin 53706 (S.J.S., S.G.)
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5
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Boucher I, Rich C, Lee A, Marcincin M, Trinkaus-Randall V. The P2Y2 receptor mediates the epithelial injury response and cell migration. Am J Physiol Cell Physiol 2010; 299:C411-21. [PMID: 20427708 DOI: 10.1152/ajpcell.00100.2009] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
Injury to epithelial cells results in the release of ATP and stimulation of purinergic receptors and is thought to alter cell migration and wound repair. Medium from the injured cells triggers Ca(2+) mobilization and phosphorylation of ERK, both of which are inhibited if the medium is pretreated with apyrase. To understand the wound repair mechanism that occurs with injury, our goal was to determine which purinergic receptor(s) was the critical player in the wound response. We hypothesize that the P2Y(2) receptor is the key player in the response of corneal epithelial cells to cell damage and subsequent repair events. Cells transfected with short interfering RNA to either P2Y(2) or P2Y(4) were stimulated either by injury or addition of UTP and imaged using fluo 3-AM to monitor changes in fluorescence. When cells with downregulated P2Y(2) receptors were injured or stimulated with UTP, the intensity of the Ca(2+) release was reduced significantly. However, when cells with downregulated P2Y(4) receptors were stimulated, only the UTP-induced Ca(2+) response was reduced significantly. In addition, downregulation of the P2Y(2) receptor inhibited wound closure compared with unstimulated cells or cells transfected with nontargeting sequence. This downregulation resulted also in an attenuation in phosphorylation of Src and ERK. Together, these data indicate that the P2Y(2) receptor plays a major biological role in the corneal injury response and repair mechanisms.
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Affiliation(s)
- Ilene Boucher
- Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts 02118, USA
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6
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Button B, Boucher RC. Role of mechanical stress in regulating airway surface hydration and mucus clearance rates. Respir Physiol Neurobiol 2008; 163:189-201. [PMID: 18585484 DOI: 10.1016/j.resp.2008.04.020] [Citation(s) in RCA: 106] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2008] [Revised: 04/11/2008] [Accepted: 04/11/2008] [Indexed: 11/16/2022]
Abstract
Effective clearance of mucus is a critical innate airway defense mechanism, and under appropriate conditions, can be stimulated to enhance clearance of inhaled pathogens. It has become increasingly clear that extracellular nucleotides (ATP and UTP) and nucleosides (adenosine) are important regulators of mucus clearance in the airways as a result of their ability to stimulate fluid secretion, mucus hydration, and cilia beat frequency (CBF). One ubiquitous mechanism to stimulate ATP release is through external mechanical stress. This article addresses the role of physiologically relevant mechanical forces in the lung and their effects on regulating mucociliary clearance (MCC). The effects of mechanical forces on the stimulating ATP release, fluid secretion, CBF, and MCC are discussed. Also discussed is evidence suggesting that airway hydration and stimulation of MCC by stress-mediated ATP release may play a role in several therapeutic strategies directed at improving mucus clearance in patients with obstructive lung diseases, including cystic fibrosis (CF) and chronic obstructive pulmonary disease (COPD).
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Affiliation(s)
- Brian Button
- Cystic Fibrosis Research and Treatment Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7248, USA.
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7
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Selective loss of P2Y2 nucleotide receptor immunoreactivity is associated with Alzheimer's disease neuropathology. J Neural Transm (Vienna) 2008; 115:1165-72. [PMID: 18506388 DOI: 10.1007/s00702-008-0067-y] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2008] [Accepted: 05/05/2008] [Indexed: 10/22/2022]
Abstract
The uridine nucleotide-activated P2Y2, P2Y4 and P2Y6 receptors are widely expressed in the brain and are involved in many CNS processes, including those which malfunction in Alzheimer's disease (AD). However, the status of these receptors in the AD neocortex, as well as their putative roles in the pathogenesis of neuritic plaques and neurofibrillary tangles, remain unclear. In this study, we used immunoblotting to measure P2Y2, P2Y4 and P2Y6 receptors in two regions of the postmortem neocortex of neuropathologically assessed AD patients and aged controls. P2Y2 immunoreactivity was found to be selectively reduced in the AD parietal cortex, while P2Y4 and P2Y6 levels were unchanged. In contrast, all three receptors were preserved in the occipital cortex, which is known to be minimally affected by AD neuropathology. Furthermore, reductions in parietal P2Y2 immunoreactivity correlated both with neuropathologic scores and markers of synapse loss. These results provide a basis for considering P2Y2 receptor changes as a neurochemical substrate of AD, and point towards uridine nucleotide-activated P2Y receptors as novel targets for disease-modifying AD pharmacotherapeutic strategies.
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Stokes L, Surprenant A. Purinergic P2Y2 receptors induce increased MCP-1/CCL2 synthesis and release from rat alveolar and peritoneal macrophages. THE JOURNAL OF IMMUNOLOGY 2007; 179:6016-23. [PMID: 17947675 DOI: 10.4049/jimmunol.179.9.6016] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Macrophages play a key role in inflammation by synthesis and release of proinflammatory cytokines and chemokines. Extracellular nucleotides released at sites of tissue damage may be an early danger signal for immune cells, and ATP-gated P2X(7) receptors are well known to mediate the rapid release of proinflammatory IL-18 and IL-1beta. However, there is little direct evidence for the involvement of other purine receptor subtypes in the release of other cytokines or chemokines. We initially used protein arrays to address whether extracellular ATP can release cytokines and/or chemokines from rat NR8383 alveolar macrophage, which lack the P2X(7) receptor. ATPgammaS increased the release of the proinflammatory chemokine, MCP-1 (MCP-1/CCL2). Pharmacological profiling identified the receptor responsible as the P2Y(2) receptor. Brief activation (10 min) of P2Y(2) receptors increased MCP-1 mRNA levels within 30 min and increased its release at 60 min. Similar results were obtained from rat peritoneal macrophages. We investigated likely downstream signaling cascades that may be involved, specifically the canonical G(q)-mediated phospholipase C (PLC) and subsequent MAP kinase pathways, and G(i)/G(o)-mediated signaling. We could find no evidence for these pathways being involved in the P2Y(2)R-induced increase in mRNA levels although inhibition of PLC blocked the UTP-induced increased release of MCP-1. Thus, the PLC-activated pathway can account for the increased release of MCP-1, but a novel signaling pathway may be involved in the increase in MCP-1 mRNA by activation of P2Y(2) receptors in alveolar and peritoneal macrophage.
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Affiliation(s)
- Leanne Stokes
- Department of Biomedical Science, University of Sheffield, Addison Building Western Bank, Sheffield, United Kingdom
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D'Alimonte I, Ciccarelli R, Di Iorio P, Nargi E, Buccella S, Giuliani P, Rathbone MP, Jiang S, Caciagli F, Ballerini P. Activation of P2X(7) receptors stimulates the expression of P2Y(2) receptor mRNA in astrocytes cultured from rat brain. Int J Immunopathol Pharmacol 2007; 20:301-16. [PMID: 17624242 DOI: 10.1177/039463200702000210] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Under pathological conditions brain cells release ATP at concentrations reported to activate P2X(7) ionotropic receptor subtypes expressed in both neuronal and glial cells. In the present study we report that the most potent P2X(7) receptor agonist BzATP stimulates the expression of the metabotropic ATP receptor P2Y(2) in cultured rat brain astrocytes. In other cell types several kinds of stimulation, including stress or injury, induce P2Y(2) expression that, in turn, is involved in different cell reactions. Similarly, it has recently been found that in astrocytes and astrocytoma cells P2Y(2) sites can trigger neuroprotective pathways through the activation of several mechanisms, including the induction of genes for antiapoptotic factors, neurotrophins, growth factors and neuropeptides. Here we present evidence that P2Y(2) mRNA expression in cultured astrocytes peaks 6 h after BzATP exposure and returns to basal levels after 24 h. This effect was mimicked by high ATP concentrations (1 mM) and was abolished by P2X(7)-antagonists oATP and BBG. The BzATP-evoked P2Y(2) receptor up-regulation in cultured astrocytes was coupled to an increased UTP-mediated intracellular calcium response. This effect was inhibited by oATP and BBG and by P2Y(2)siRNA, thus supporting evidence of increased P2Y(2) activity. To further investigate the mechanisms by which P2X(7) receptors mediated the P2Y(2) mRNA up-regulation, the cells were pre-treated with the chelating agent EGTA, or with inhibitors of mitogen-activated kinase (MAPK) (PD98059) or protein kinase C, (GF109203X). Each inhibitor significantly reduced the extent to which BzATP induced P2Y(2) mRNA. Both BzATP and ATP (1 mM) increased ERK1/2 activation. P2X(7)-induced ERK1/2 phosphorylation was unaffected by pre-treatment of astrocytes with EGTA whereas it was inhibited by GF109203X. Phorbol-12-myristate-13-acetate (PMA), an activator of PKCs, rapidly increased ERK1/2 activation. We conclude that activation of P2X(7) receptors in astrocytes enhances P2Y(2) mRNA expression by a mechanism involving both calcium influx and PKC/MAPK signalling pathways.
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Affiliation(s)
- I D'Alimonte
- Department of Biomedical Sciences, University of Chieti-Pescara, Chieti, Italy
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10
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Chorna NE, Chevres M, Santos-Berrios C, Orellano EA, Erb L, González FA. P2Y2 receptors induced cell surface redistribution of alpha(v) integrin is required for activation of ERK 1/2 in U937 cells. J Cell Physiol 2007; 211:410-22. [PMID: 17186500 DOI: 10.1002/jcp.20946] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Nucleotides released from cells due to stress, injury or inflammation, induce mitogenic effects in monocytes via activation of P2Y(2) nucleotide receptors (P2Y(2)Rs). Here we show that P2Y(2) nucleotide receptors in U937 monocytic cells regulate the activation of extracellular signal-regulated kinases 1 and 2 (ERK 1/2) by inducing the clustering of alpha(v) integrins. The activation of phosphatidylinositol 3-kinase by P2Y(2)R ligands was required for alpha(v) clustering, suggesting a means whereby two different classes of receptors communicate to induce mitogenic responses in monocytic cells. P2Y(2)R-induced alpha(v) clustering was also associated with a flattened phenotype of the U937 cells, consistent with the role of the P2Y(2)R in regulating early events in cell migration.
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Affiliation(s)
- Nataliya E Chorna
- Department of Chemistry, Río Piedras Campus, University of Puerto Rico, San Juan, Puerto Rico, USA
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11
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Nucleotide receptor signalling and the generation of reactive oxygen species. Purinergic Signal 2007; 3:39-51. [PMID: 18404417 PMCID: PMC2096761 DOI: 10.1007/s11302-006-9035-x] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2006] [Accepted: 03/15/2006] [Indexed: 12/21/2022] Open
Abstract
Elevated levels of extracellular nucleotides are present at sites of inflammation, platelet degranulation and cellular damage or lysis. These extracellular nucleotides can lead to the activation of purinergic (nucleotide) receptors on various leukocytes, including monocytes, macrophages, eosinophils, and neutrophils. In turn, nucleotide receptor activation has been linked to increased cellular production and release of multiple inflammatory mediators, including superoxide anion, nitric oxide and other reactive oxygen species (ROS). In the present review, we will summarize the evidence that extracellular nucleotides can facilitate the generation of multiple ROS by leukocytes. In addition, we will discuss several potential mechanisms by which nucleotide-enhanced ROS production may occur. Delineation of these mechanisms is important for understanding the processes associated with nucleotide-induced antimicrobial activities, cell signalling, apoptosis, and pathology.
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12
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D'Alimonte I, Flati V, D'Auro M, Toniato E, Martinotti S, Rathbone MP, Jiang S, Ballerini P, Di Iorio P, Caciagli F, Ciccarelli R. Guanosine Inhibits CD40 Receptor Expression and Function Induced by Cytokines and β Amyloid in Mouse Microglia Cells. THE JOURNAL OF IMMUNOLOGY 2007; 178:720-31. [PMID: 17202332 DOI: 10.4049/jimmunol.178.2.720] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Growing evidence implicates CD40, a member of the TNFR superfamily, as contributing to the pathogenesis of many neurodegenerative diseases. Thus, strategies to suppress its expression may be of benefit in those disorders. To this aim, we investigated the effect of guanosine, a purine nucleoside that exerts neurotrophic and neuroprotective effects. CD40 expression and function are increased by exposure of mouse microglia cultures or the N9 microglia cell line to IFN-gamma (10 ng/ml) plus TNF-alpha (50 ng/ml) or beta amyloid (Abeta) peptide (Abeta(1-42); 500 nM). Culture pretreatment with guanosine (10-300 microM), starting 1 h before cytokine or Abeta addition, dose-dependently inhibited the CD40-induced expression as well as functional CD40 signaling by suppressing IL-6 production promoted by IFN-gamma/TNF-alpha challenge in the presence of CD40 cross-linking. Moreover, guanosine abrogated IFN-gamma-induced phosphorylation on Ser(727) and translocation of STAT-1alpha to the nucleus as well as TNF-alpha-/Abeta-induced IkappaBalpha and NF-kappaB p65/RelA subunit phosphorylation, thus inhibiting NF-kappaB-induced nuclear translocation. Guanosine effects were mediated by an increased phosphorylation of Akt, a PI3K downstream effector, as well as of ERK1/2 and p38 in the MAPK system, because culture pretreatment with selective ERK1/2, p38 MAPK, and PI3K antagonists (U0126, SB203580, or LY294002, respectively) counteracted guanosine inhibition on IFN-gamma/TNF-alpha-induced CD40 expression and function as well as on STAT-1alpha or NF-kappaB nuclear translocation. These findings suggest a role for guanosine as a potential drug in the experimental therapy of neuroinflammatory/neurodegenerative diseases, particularly Alzheimer's disease.
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Affiliation(s)
- Iolanda D'Alimonte
- Department of Biomedical Sciences, Section of Pharmacology, University of Chieti, Via dei Vestini 29, 66013 Chieti, Italy
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13
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Ballerini P, Di Iorio P, Caciagli F, Rathbone MP, Jiang S, Nargi E, Buccella S, Giuliani P, D'Alimonte I, Fischione G, Masciulli A, Romano S, Ciccarelli R. P2Y2 receptor up-regulation induced by guanosine or UTP in rat brain cultured astrocytes. Int J Immunopathol Pharmacol 2006; 19:293-308. [PMID: 16831297 DOI: 10.1177/039463200601900207] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Among P2 metabotropic ATP receptors, P2Y2 subtype seems to be peculiar as its upregulation triggers important biological events in different cells types. In non-stimulated cells including astrocytes, P2Y2 receptors are usually expressed at levels lower than P2Y1 sites, however the promoter region of the P2Y2 receptors has not yet been studied and little is known about the mechanisms underlying the regulation of the expression of this ATP receptor. We showed that not only UTP and ATP are the most potent and naturally occurring agonist for P2Y2 sites, but also guanosine induced an up-regulation of astrocyte P2Y2 receptor mRNA evaluated by Northern blot analysis. We also focused our attention on this nucleoside since in our previous studies it was reported to be released by cultured astrocytes and to exert different neuroprotective effects. UTP and guanosine-evoked P2Y2 receptor up-regulation in rat brain cultured astrocytes was linked to an increased P2Y2-mediated intracellular calcium response, thus suggesting an increased P2Y2 activity. Actinomycin D, a RNA polymerase inhibitor, abrogated both UTP and guanosine-mediated P2Y2 up-regulation, thus indicating that de novo transcription was required. The effect of UTP and guanosine was also evaluated in astrocytes pretreated with different inhibitors of signal transduction pathways including ERK, PKC and PKA reported to be involved in the regulation of other cell surface receptor mRNAs. The results show that ERK1-2/MAPK pathway play a key role in the P2Y2 receptor up-regulation mediated by either UTP or guanosine. Moreover, our data suggest that PKA is also involved in guanosine-induced transcriptional activation of P2Y2 mRNA and that increased intracellular calcium levels and PKC activation may also mediate P2Y2 receptor up-regulation triggered by UTP. The extracellular release of ATP under physiological and pathological conditions has been widely studied. On the contrary, little is known about the release of pyrimidines and in particular of UTP. Here we show that astrocytes are able to release UTP, either at rest or during and following hypoxia/hypoglycemia obtained by submitting the cells to glucose-oxygen deprivation (OGD). Interestingly, also P2Y2 receptor mRNA increased by about two-fold the control values when the cultures were submitted to OGD. It has been recently reported that P2Y2 receptors can play a protective role in astrocytes, thus either guanosine administration or increased extracellular concentrations of guanosine and UTP reached locally following CNS injury may increase P2Y2-mediated biological events aimed at promoting a protective astrocyte response.
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Affiliation(s)
- P Ballerini
- Dept. of Biomedical Sciences, Section of Pharmacology and Toxicology, Medical School, University G. D'Annunzio of Chieti-Pescara, Via dei Vestini 29, 66013 Chieti, Italy.
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14
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Franke H, Krügel U, Illes P. P2 receptors and neuronal injury. Pflugers Arch 2006; 452:622-44. [PMID: 16645849 DOI: 10.1007/s00424-006-0071-8] [Citation(s) in RCA: 128] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2006] [Accepted: 03/09/2006] [Indexed: 02/08/2023]
Abstract
Extracellular adenosine 5'-triphosphate (ATP) was proposed to be an activity-dependent signaling molecule that regulates glia-glia and glia-neuron communications. ATP is a neurotransmitter of its own right and, in addition, a cotransmitter of other classical transmitters such as glutamate or GABA. The effects of ATP are mediated by two receptor families belonging either to the P2X (ligand-gated cationic channels) or P2Y (G protein-coupled receptors) types. P2X receptors are responsible for rapid synaptic responses, whereas P2Y receptors mediate slow synaptic responses and other types of purinergic signaling involved in neuronal damage/regeneration. ATP may act at pre- and postsynaptic sites and therefore, it may participate in the phenomena of long-term potentiation and long-term depression of excitatory synaptic transmission. The release of ATP into the extracellular space, e.g., by exocytosis, membrane transporters, and connexin hemichannels, is a widespread physiological process. However, ATP may also leave cells through their plasma membrane damaged by inflammation, ischemia, and mechanical injury. Functional responses to the activation of multiple P2 receptors were found in neurons and glial cells under normal and pathophysiological conditions. P2 receptor-activation could either be a cause or a consequence of neuronal cell death/glial activation and may be related to detrimental and/or beneficial effects. The present review aims at demonstrating that purinergic mechanisms correlate with the etiopathology of brain insults, especially because of the massive extracellular release of ATP, adenosine, and other neurotransmitters after brain injury. We will focus in this review on the most important P2 receptor-mediated neurodegenerative and neuroprotective processes and their beneficial modulation by possible therapeutic manipulations.
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Affiliation(s)
- Heike Franke
- Rudolf-Boehm Institute of Pharmacology and Toxicology, University of Leipzig, Härtelstrasse 16-18, 04107, Leipzig, Germany.
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15
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Arthur DB, Georgi S, Akassoglou K, Insel PA. Inhibition of apoptosis by P2Y2 receptor activation: novel pathways for neuronal survival. J Neurosci 2006; 26:3798-804. [PMID: 16597733 PMCID: PMC6674138 DOI: 10.1523/jneurosci.5338-05.2006] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Cell survival is an essential function in the development and maintenance of the nervous system. We demonstrate here a previously unappreciated role for extracellular nucleotide signaling through the P2Y2 receptor in the survival of neurons: PC12 (pheochromocytoma 12) cells and dorsal root ganglion neurons are protected from serum starvation-induced apoptosis by ATP, UTP, and ATPgammaS, an effect mediated via P2Y2 receptors, as demonstrated by small interfering RNA and genetic knock-out models. This protection occurs independently of neurophin signaling but requires Src activation of ERK (extracellular signal-regulated kinase) and Akt. Moreover, ATPgammaS and NGF act synergistically to enhance neuronal survival through enhanced TrkA signaling. The results, which define a novel mechanism for inhibition of apoptosis, implicate parallel, interacting systems--extracellular nucleotides/P2Y2 receptors and neurotrophin/TrkA--to sustain neuronal survival.
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Trujillo CA, Nery AA, Martins AHB, Majumder P, Gonzalez FA, Ulrich H. Inhibition mechanism of the recombinant rat P2X(2) receptor in glial cells by suramin and TNP-ATP. Biochemistry 2006; 45:224-33. [PMID: 16388598 DOI: 10.1021/bi051517w] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
P2X receptors play an important role in communication between cells in the nervous system. Therefore, understanding the mechanisms of inhibition of these receptors is important for the development of new tools for drug discovery. Our objective has been to determine the pharmacological activity of the antagonist suramin, the most important antagonist of purinergic receptor function, as well as to demonstrate its noncompetitive inhibition and confirm a competitive mechanism between ATP and TNP-ATP in 1321N1 glial cells stably transfected with the recombinant rat P2X(2) receptor. A radioligand binding assay was employed to determine whether suramin, TNP-ATP, and ATP compete for the same binding site on the receptor. TNP-ATP displaced [alpha-32P]ATP, whereas suramin did not interfere with [alpha-32P]ATP-receptor binding. To determine the inhibition mechanism relevant for channel opening, currents obtained in fast kinetic whole-cell recording experiments, following stimulation of cells by ATP in the presence of suramin, were compared to those obtained by ATP in the presence of TNP-ATP. Supported by a mathematical model for receptor kinetics [Breitinger, H. G., Geetha, N., and Hess, G. P. (2001) Biochemistry 40, 8419-8429], the inhibition factors were plotted as functions of inhibitor or agonist concentrations. Analysis of the data indicated a competitive inhibition mechanism for TNP-ATP and a noncompetitive inhibition for suramin. Taken together, both data support a noncompetitive inhibition mechanism of the rat recombinant P2X(2) receptor by suramin, confirm the competitive inhibition by TNP-ATP, and allow the prediction of a model for P2X(2) receptor inhibition.
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Affiliation(s)
- Cleber A Trujillo
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo 05508-900, Brazil
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Büscher R, Hoerning A, Patel HH, Zhang S, Arthur DB, Grasemann H, Ratjen F, Insel PA. P2Y2 receptor polymorphisms and haplotypes in cystic fibrosis and their impact on Ca2+ influx. Pharmacogenet Genomics 2006; 16:199-205. [PMID: 16495779 DOI: 10.1097/01.fpc.0000189798.11468.6a] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE Activation of P2Y2 receptors in airway epithelia by ATP and UTP stimulates a Ca2+-regulated Cl- channel, which regulates Cl- secretion in cystic fibrosis (CF). We hypothesized that genetic alterations in the P2Y2 receptor may act as disease modifiers in CF and thus analyzed the coding region of this gene for polymorphisms in 146 CF patients and 64 healthy controls. We also assessed the impact of the genetic variants on Ca2+-influx of P2Y2-null cells transfected with several P2Y2 receptor haplotypes. RESULTS We identified three frequent nonsynonymous P2Y2 receptor polymorphisms: Leu46Pro; Arg312Ser and Arg334Cys, of which only Arg312Ser was significantly more common in CF: Arg = 0.80, Ser = 0.20 (CF) vs. Arg = 0.72, Ser = 0.28 (controls), P < 0.05; for Leu46Pro, Leu = 0.92, Pro = 0.08 (CF) vs. Leu = 0.96, Pro = 0.04 (controls), P = 0.65 and for Arg334Cys, Arg = 0.79, Cys = 0.21 (CF) vs. Arg = 0.84, Cys = 0.16 (controls), P = 0.79. The most frequent haplotype was Leu46Leu/Arg312Arg/Arg334Arg (28% in CF, 31% in controls) but 6% of CF patients and none of the controls had Leu46Leu/Ser312Ser/Arg334Cys or Leu46Leu/Arg312Arg/Cys334Cys. To assess function of the receptor haplotypes, we stably transfected 1321N1 (P2Y-null) cells to similar levels of mRNA expression with Leu46Leu/Arg312Arg/Arg334Arg (wild-type), Leu46Leu/Ser312Ser/Arg334Arg and Leu46Leu/Arg312Arg/Cys334Cys and measured ATP-stimulated transient Ca2+-influx. Cells expressing the homozygous Cys334 variant had significantly increased Ca2+-influx compared to wild-type (P<0.01). The increase in Ca2+-influx was more pronounced in cells carrying the homozygous Ser312 variant than in cells with the other two genotypes (P<0.01). CONCLUSIONS These data indicate that P2Y2 receptor gene haplotypes influence intracellular Ca2+-release. Such genetic variants might therefore represent modifiers of Cl- secretion or of response to P2Y2 agonist therapy in CF.
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Affiliation(s)
- Rainer Büscher
- Department of Pediatrics, University Children's Hospital, Hufelandstr. 55, 45122 Essen, Germany.
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Kannan S. Molecular basis of the clinical failure of Clopidogrel therapy. Med Hypotheses 2006; 67:200-1. [PMID: 16504412 DOI: 10.1016/j.mehy.2006.01.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2005] [Accepted: 01/10/2006] [Indexed: 11/22/2022]
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