The P2X7 Receptor Drives Microglial Activation and Proliferation: A Trophic Role for P2X7R Pore

Microglial activation is an integral part of neuroinflammation associated with many neurodegenerative conditions. Interestingly, a number of neurodegenerative conditions exhibit enhanced P2X7 receptor (P2X7R) expression in the neuroinflammatory foci where activated microglia are a coexisting feature. Whether P2X7R overexpression is driving microglial activation or, conversely, P2X7R overexpression is a consequence of microglial activation is not known. We report that overexpression alone of a purinergic P2X7R, in the absence of pathological insults, is sufficient to drive the activation and proliferation of microglia in rat primary hippocampal cultures. The trophic responses observed in microglia were found to be P2X7R specific as the P2X7R antagonist, oxidized ATP (oxATP), was effective in markedly attenuating microgliosis. oxATP treatment of primary hippocampal cultures expressing exogenous P2X7Rs resulted in a significant decrease in the number of activated microglia. P2X7R is unusual in exhibiting two conductance states, a cation channel and a plasma membrane pore, and there are no pharmacological agents capable of cleanly discriminating between these two states. We used a point mutant of P2X7R (P2X7RG345Y) with intact channel function but ablated pore-forming capacity to establish that the trophic effects of increased P2X7R expression are exclusively mediated by the pore conductance. Collectively, and contrary to previous reports describing P2X7R as a “death receptor,” we provide evidence for a novel trophic role for P2X7R pore in microglia.

[1]  D. Spray,et al.  P2X7 receptor-Pannexin1 complex: pharmacology and signaling. , 2008, American journal of physiology. Cell physiology.

[2]  B. Duling,et al.  Functional role of gap junctions in cytokine-induced leukocyte adhesion to endothelium in vivo. , 2008, American journal of physiology. Heart and circulatory physiology.

[3]  A. Suzumura,et al.  Macrophage-induced neurotoxicity is mediated by glutamate and attenuated by glutaminase inhibitors and gap junction inhibitors. , 2008, Life sciences.

[4]  S. Shimada,et al.  Cellular localization of P2X7 receptor mRNA in the rat brain , 2008, Brain Research.

[5]  Hyun B Choi,et al.  Modulation of the Purinergic P2X7 Receptor Attenuates Lipopolysaccharide-Mediated Microglial Activation and Neuronal Damage in Inflamed Brain , 2007, The Journal of Neuroscience.

[6]  R. Dringen,et al.  Gap junction hemichannel-mediated release of glutathione from cultured rat astrocytes , 2007, Neuroscience Letters.

[7]  D. Spray,et al.  Pannexin1 is part of the pore forming unit of the P2X7 receptor death complex , 2007, FEBS letters.

[8]  Hyun B Choi,et al.  Upregulated Expression of Purinergic P2X7 Receptor in Alzheimer Disease and Amyloid-&bgr; Peptide-Treated Microglia and in Peptide-Injected Rat Hippocampus , 2006, Journal of neuropathology and experimental neurology.

[9]  Shijie Jin,et al.  Tumor Necrosis Factor-α Induces Neurotoxicity via Glutamate Release from Hemichannels of Activated Microglia in an Autocrine Manner* , 2006, Journal of Biological Chemistry.

[10]  P. Mander,et al.  Journal of Neuroinflammation Activation of Microglial Nadph Oxidase Is Synergistic with Glial Inos Expression in Inducing Neuronal Death: a Dual-key Mechanism of Inflammatory Neurodegeneration , 2005 .

[11]  F. Di Virgilio,et al.  A novel recombinant plasma membrane-targeted luciferase reveals a new pathway for ATP secretion. , 2005, Molecular biology of the cell.

[12]  L. Bonewald,et al.  Mechanical strain opens connexin 43 hemichannels in osteocytes: a novel mechanism for the release of prostaglandin. , 2005, Molecular biology of the cell.

[13]  F. Helmchen,et al.  Resting Microglial Cells Are Highly Dynamic Surveillants of Brain Parenchyma in Vivo , 2005, Science.

[14]  J. Deuchars,et al.  Differential co-localisation of the P2X7 receptor subunit with vesicular glutamate transporters VGLUT1 and VGLUT2 in rat CNS , 2004, Neuroscience.

[15]  L. Deng,et al.  High Ca2+-phosphate transfection efficiency enables single neuron gene analysis , 2004, Gene Therapy.

[16]  H. Kubo,et al.  Effects of carbenoxolone on alveolar fluid clearance and lung inflammation in the rat , 2004, Critical care medicine.

[17]  R. Mrak,et al.  Microglia and neuroinflammation: a pathological perspective , 2004 .

[18]  S. Goldman,et al.  P2X7 receptor inhibition improves recovery after spinal cord injury , 2004, Nature Medicine.

[19]  J. Wiley,et al.  Glu496 to Ala Polymorphism in the P2X7 Receptor Impairs ATP-Induced IL-1β Release from Human Monocytes1 , 2004, The Journal of Immunology.

[20]  Kazuhide Inoue,et al.  Production and Release of Neuroprotective Tumor Necrosis Factor by P2X7 Receptor-Activated Microglia , 2004, The Journal of Neuroscience.

[21]  Albert E. Ayoub,et al.  Increased Morphological Diversity of Microglia in the Activated Hypothalamic Supraoptic Nucleus , 2003, The Journal of Neuroscience.

[22]  B. Robertson,et al.  P2X7 Mediates Superoxide Production in Primary Microglia and Is Up-regulated in a Transgenic Mouse Model of Alzheimer's Disease* , 2003, The Journal of Biological Chemistry.

[23]  S. Petrou,et al.  P2X7 Receptor Cell Surface Expression and Cytolytic Pore Formation Are Regulated by a Distal C-terminal Region* , 2003, The Journal of Biological Chemistry.

[24]  D. Spray,et al.  Prospects for rational development of pharmacological gap junction channel blockers. , 2002, Current drug targets.

[25]  S. Tsirka,et al.  Microglial activation and recruitment, but not proliferation, suffice to mediate neurodegeneration , 2002, Cell Death and Differentiation.

[26]  B. MacVicar,et al.  Activation of Presynaptic P2X7-Like Receptors Depresses Mossy Fiber–CA3 Synaptic Transmission through p38 Mitogen-Activated Protein Kinase , 2002, The Journal of Neuroscience.

[27]  N. Rothwell,et al.  Extracellular ATP and P2X7 receptors in neurodegeneration. , 2002, European journal of pharmacology.

[28]  J. Deuchars,et al.  Involvement of P2X7 receptors in the regulation of neurotransmitter release in the rat hippocampus , 2002, Journal of neurochemistry.

[29]  Wen-rong Gong,et al.  Stimulation of Ca2+ influx through ATP receptors on rat brain synaptosomes: identification of functional P2X7 receptor subtypes , 2002 .

[30]  S. Gründer,et al.  The P2X7 receptor from Xenopus laevis: formation of a large pore in Xenopus oocytes , 2002, FEBS letters.

[31]  Wenjie Xie,et al.  Microglial Activation and Dopaminergic Cell Injury: An In Vitro Model Relevant to Parkinson's Disease , 2001, The Journal of Neuroscience.

[32]  J. Deuchars,et al.  Neuronal P2X7 Receptors Are Targeted to Presynaptic Terminals in the Central and Peripheral Nervous Systems , 2001, The Journal of Neuroscience.

[33]  Guy C. Brown,et al.  Inflammatory Neurodegeneration Mediated by Nitric Oxide from Activated Glia-Inhibiting Neuronal Respiration, Causing Glutamate Release and Excitotoxicity , 2001, The Journal of Neuroscience.

[34]  M. Matteoli,et al.  ATP Mediates Calcium Signaling Between Astrocytes and Microglial Cells: Modulation by IFN-γ1 , 2001, The Journal of Immunology.

[35]  Beverly H. Koller,et al.  Altered Cytokine Production in Mice Lacking P2X7Receptors* , 2001, The Journal of Biological Chemistry.

[36]  G. Levi,et al.  Two different ionotropic receptors are activated by ATP in rat microglia , 1999, The Journal of physiology.

[37]  Baljit S Khakh,et al.  Dynamic Selectivity Filters in Ion Channels , 1999, Neuron.

[38]  M. Cuzner,et al.  Apoptotic Pathways Mobilized in Microglia and Neurones as a Consequence of Chromogranin A‐Induced Microglial Activation , 1999, Journal of neurochemistry.

[39]  K. Davis,et al.  Neurofibrillary tangles in nondemented elderly subjects and mild Alzheimer disease. , 1999, Archives of neurology.

[40]  W. Volknandt,et al.  A plethora of presynaptic proteins associated with ATP‐storing organelles in cultured astrocytes , 1999, Glia.

[41]  W. Streit,et al.  Reactive microgliosis , 1999, Progress in Neurobiology.

[42]  F. de Zegher,et al.  Male Pseudohermaphroditism Related to Complications at Conception, in Early Pregnancy or in Prenatal Growth , 1999, Hormone Research in Paediatrics.

[43]  G. Frisoni,et al.  Hippocampal and entorhinal cortex atrophy in frontotemporal dementia and Alzheimer’s disease , 1999, Neurology.

[44]  G Burnstock,et al.  Receptors for purines and pyrimidines. , 1998, Pharmacological reviews.

[45]  K. Davis,et al.  Regional distribution of neuritic plaques in the nondemented elderly and subjects with very mild Alzheimer disease. , 1998, Archives of neurology.

[46]  D. Ferrari,et al.  Cytolytic P2X purinoceptors , 1998, Cell Death and Differentiation.

[47]  E. Kawashima,et al.  Tissue distribution of the P2X7 receptor , 1997, Neuropharmacology.

[48]  J. Kaye,et al.  Volume loss of the hippocampus and temporal lobe in healthy elderly persons destined to develop dementia , 1997, Neurology.

[49]  J. Bekkers,et al.  Nonuniform Distribution of Ca2+ Channel Subtypes on Presynaptic Terminals of Excitatory Synapses in Hippocampal Cultures , 1997, The Journal of Neuroscience.

[50]  E. Benveniste Role of macrophages/microglia in multiple sclerosis and experimental allergic encephalomyelitis , 1997, Journal of Molecular Medicine.

[51]  Stefania Hanau,et al.  Purinergic Modulation of Interleukin-1 ␤ Release from Microglial Cells Stimulated with Bacterial Endotoxin Materials and Methods , 1997 .

[52]  E. Kawashima,et al.  The Cytolytic P2Z Receptor for Extracellular ATP Identified as a P2X Receptor (P2X7) , 1996, Science.

[53]  G. Kreutzberg,et al.  Microglia: Intrinsic immuneffector cell of the brain , 1995, Brain Research Reviews.

[54]  K. Starke,et al.  Co-release of noradrenaline and ATP from cultured sympathetic neurons , 1994, Neuroscience.

[55]  F. Di Virgilio,et al.  Oxidized ATP. An irreversible inhibitor of the macrophage purinergic P2Z receptor. , 1993, The Journal of biological chemistry.

[56]  G. Kreutzberg,et al.  Cytotoxicity of microglia , 1992, Journal of Neuroimmunology.

[57]  E. Unanue,et al.  Interleukin 1 is processed and released during apoptosis. , 1991, Proceedings of the National Academy of Sciences of the United States of America.

[58]  M. Graeber,et al.  New expression of myelomonocytic antigens by microglia and perivascular cells following lethal motor neuron injury , 1990, Journal of Neuroimmunology.

[59]  J. Swanson,et al.  ATP4- permeabilizes the plasma membrane of mouse macrophages to fluorescent dyes. , 1987, The Journal of biological chemistry.

[60]  E. Harley,et al.  Reversible inhibition of intercellular junctional communication by glycyrrhetinic acid. , 1986, Biochemical and biophysical research communications.

[61]  B. Gomperts,et al.  ATP induces nucleotide permeability in rat mast cells , 1979, Nature.

[62]  Wen-rong Gong,et al.  Stimulation of Ca(2+) influx through ATP receptors on rat brain synaptosomes: identification of functional P2X(7) receptor subtypes. , 2002, British journal of pharmacology.

[63]  B. Pessac,et al.  [Microglia: origin and development]. , 2001, Bulletin de l'Academie nationale de medecine.

[64]  R. Pawlinski,et al.  Morphology of reactive microglia in the injured cerebral cortex. Fractal analysis and complementary quantitative methods , 2001, Journal of neuroscience research.

[65]  H. Lester,et al.  Gain of function mutants: ion channels and G protein-coupled receptors. , 2000, Annual review of neuroscience.

[66]  H. Soininen,et al.  Comparative MR analysis of the entorhinal cortex and hippocampus in diagnosing Alzheimer disease. , 1999, AJNR. American journal of neuroradiology.

[67]  M. Woodroofe,et al.  Chemokines induce migration and changes in actin polymerization in adult rat brain microglia and a human fetal microglial cell line in vitro , 1999, Journal of neuroscience research.

[68]  J. Zimmer,et al.  Development of microglia in the postnatal rat hippocampus , 1998, Hippocampus.

[69]  P. Mcgeer,et al.  Mechanisms of cell death in Alzheimer disease--immunopathology. , 1998, Journal of neural transmission. Supplementum.