title: ATP-P2X7 Receptor Modulates Axon Initial Segment Composition and Function in Physiological Conditions and Brain Injury.
abstract: Axon properties, including action potential initiation and modulation, depend on both AIS integrity and the regulation of ion channel expression in the AIS. Alteration of the axon initial segment (AIS) has been implicated in neurodegenerative, psychiatric, and brain trauma diseases, thus identification of the physiological mechanisms that regulate the AIS is required to understand and circumvent AIS alterations in pathological conditions. Here, we show that the purinergic P2X7 receptor and its agonist, adenosine triphosphate (ATP), modulate both structural proteins and ion channel density at the AIS in cultured neurons and brain slices. In cultured hippocampal neurons, an increment of extracellular ATP concentration or P2X7-green fluorescent protein (GFP) expression reduced the density of ankyrin G and voltage-gated sodium channels at the AIS. This effect is mediated by P2X7-regulated calcium influx and calpain activation, and impaired by P2X7 inhibition with Brilliant Blue G (BBG), or P2X7 suppression. Electrophysiological studies in brain slices showed that P2X7-GFP transfection decreased both sodium current amplitude and intrinsic neuronal excitability, while P2X7 inhibition had the opposite effect. Finally, inhibition of P2X7 with BBG prevented AIS disruption after ischemia/reperfusion in rats. In conclusion, our study demonstrates an involvement of P2X7 receptors in the regulation of AIS mediated neuronal excitability in physiological and pathological conditions.
authors.affiliation: Instituto Cajal, CSIC, Department of Cellular, Molecular and Developmental Neurobiology, Madrid 28002, Spain Centro de Investigación Biomédica en Red Sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain.
authors.forename: Ana
authors.initials: A
authors.lastname: Del Puerto
authors.affiliation: Institut National de la Santé et de la Recherche Médicale, U1072, Marseille F-13344 France Aix-Marseille Université, Faculté de Médecine Secteur Nord, Marseille F-13344 France.
authors.forename: Laure
authors.initials: L
authors.lastname: Fronzaroli-Molinieres
authors.affiliation: Departamento de Biología (Unidad Docente Fisiología Animal), Universidad Autónoma de Madrid, Madrid 28049, Spain.
authors.forename: María José
authors.initials: MJ
authors.lastname: Perez-Alvarez
authors.affiliation: Institut National de la Santé et de la Recherche Médicale, U1072, Marseille F-13344 France Aix-Marseille Université, Faculté de Médecine Secteur Nord, Marseille F-13344 France.
authors.forename: Pierre
authors.initials: P
authors.lastname: Giraud
authors.affiliation: Institut National de la Santé et de la Recherche Médicale, U1072, Marseille F-13344 France Aix-Marseille Université, Faculté de Médecine Secteur Nord, Marseille F-13344 France.
authors.forename: Edmond
authors.initials: E
authors.lastname: Carlier
authors.affiliation: Centro de Investigación Biomédica en Red Sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain Centro de Biología Molecular, CSIC-UAM, Madrid 28049 Spain.
authors.forename: Francisco
authors.initials: F
authors.lastname: Wandosell
authors.affiliation: Institut National de la Santé et de la Recherche Médicale, U1072, Marseille F-13344 France Aix-Marseille Université, Faculté de Médecine Secteur Nord, Marseille F-13344 France.
authors.forename: Dominique
authors.initials: D
authors.lastname: Debanne
authors.affiliation: Instituto Cajal, CSIC, Department of Cellular, Molecular and Developmental Neurobiology, Madrid 28002, Spain Centro de Investigación Biomédica en Red Sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain.
authors.forename: Juan José
authors.initials: JJ
authors.lastname: Garrido
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism*; D000818:Animals; D017487:Ankyrins / Q000378:metabolism; D001369:Axons / Q000473:pathology / Q000502:physiology*; D001557:Benzenesulfonates / Q000494:pharmacology; D001921:Brain / Q000473:pathology / Q000503:physiopathology*; D002545:Brain Ischemia / Q000473:pathology / Q000503:physiopathology*; D002118:Calcium / Q000378:metabolism; D002154:Calpain / Q000378:metabolism; D015687:Cell Hypoxia / Q000502:physiology; D002478:Cells, Cultured; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D051379:Mice; D058920:Purinergic P2X Receptor Antagonists / Q000494:pharmacology; D017208:Rats, Wistar; D058486:Receptors, Purinergic P2X7 / Q000378:metabolism*; D046509:Tissue Culture Techniques; D061566:Voltage-Gated Sodium Channels / Q000378:metabolism
chemical_list: C094681:Ank3 protein, mouse; D017487:Ankyrins; D001557:Benzenesulfonates; C546469:P2rx7 protein, mouse; C546470:P2rx7 protein, rat; D058920:Purinergic P2X Receptor Antagonists; D058486:Receptors, Purinergic P2X7; D061566:Voltage-Gated Sodium Channels; D049452:Green Fluorescent Proteins; D000255:Adenosine Triphosphate; D002154:Calpain; C006796:brilliant blue; D002118:Calcium
keywords: BBG; P2X7 receptor; ankyrin G; axon initial segment; brain ischemia; sodium channels