title: CLIC1 function is required for beta-amyloid-induced generation of reactive oxygen species by microglia.
abstract: The Alzheimer's disease (AD) brain is characterized by plaques containing beta-amyloid (Abeta) protein surrounded by astrocytes and reactive microglia. Activation of microglia by Abeta initiates production of reactive oxygen species (ROS) by the plasmalemmal NADPH oxidase; the resultant oxidative stress is thought to contribute to neurodegeneration in AD. We have previously shown that Abeta upregulates a chloride current mediated by the chloride intracellular channel 1 (CLIC1) protein in microglia. We now demonstrate that Abeta promotes the acute translocation of CLIC1 from the cytosol to the plasma membrane of microglia, where it mediates a chloride conductance. Both the Abeta induced Cl(-) conductance and ROS generation were prevented by pharmacological inhibition of CLIC1, by replacement of chloride with impermeant anions, by an anti-CLIC1 antibody and by suppression of CLIC1 expression using siRNA. Thus, the CLIC1-mediated Cl(-) conductance is required for Abeta-induced generation of neurotoxic ROS by microglia. Remarkably, CLIC1 activation is itself dependent on oxidation by ROS derived from the activated NADPH oxidase. We therefore propose that CLIC1 translocation from the cytosol to the plasma membrane, in response to redox modulation by NADPH oxidase-derived ROS, provides a feedforward mechanism that facilitates sustained microglial ROS generation by the NAPDH oxidase.
authors.affiliation: Department of Physiology, University College London, London, United Kingdom.
authors.forename: Rosemary H
authors.initials: RH
authors.lastname: Milton
authors.forename: Rosella
authors.initials: R
authors.lastname: Abeti
authors.forename: Stefania
authors.initials: S
authors.lastname: Averaimo
authors.forename: Silvia
authors.initials: S
authors.lastname: DeBiasi
authors.forename: Laura
authors.initials: L
authors.lastname: Vitellaro
authors.forename: Lele
authors.initials: L
authors.lastname: Jiang
authors.forename: Paul M G
authors.initials: PM
authors.lastname: Curmi
authors.forename: Samuel N
authors.initials: SN
authors.lastname: Breit
authors.forename: Michael R
authors.initials: MR
authors.lastname: Duchen
authors.forename: Michele
authors.initials: M
authors.lastname: Mazzanti
mesh_terms: D016229:Amyloid beta-Peptides / Q000494:pharmacology*; D016564:Amyloid beta-Protein Precursor / Q000235:genetics; D000818:Animals; D000906:Antibodies / Q000494:pharmacology; D001921:Brain / Q000166:cytology* / Q000378:metabolism; D002478:Cells, Cultured; D018118:Chloride Channels / Q000276:immunology / Q000502:physiology*; D006016:Glycolates / Q000494:pharmacology; D049452:Green Fluorescent Proteins / Q000096:biosynthesis; D006801:Humans; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D051379:Mice; D008822:Mice, Transgenic; D017628:Microglia / Q000187:drug effects*; D009154:Mutation / Q000502:physiology; D018408:Patch-Clamp Techniques; D010446:Peptide Fragments / Q000494:pharmacology*; D053764:Presenilin-1 / Q000235:genetics; D021381:Protein Transport / Q000187:drug effects / Q000502:physiology; D034741:RNA, Small Interfering / Q000494:pharmacology; D051381:Rats; D017382:Reactive Oxygen Species / Q000378:metabolism*; D016875:tau Proteins / Q000235:genetics
chemical_list: D016229:Amyloid beta-Peptides; D016564:Amyloid beta-Protein Precursor; D000906:Antibodies; D018118:Chloride Channels; C501967:Clic1 protein, mouse; D006016:Glycolates; D010446:Peptide Fragments; D053764:Presenilin-1; D034741:RNA, Small Interfering; D017382:Reactive Oxygen Species; C075222:amyloid beta-protein (1-42); C074636:amyloid beta-protein (25-35); D016875:tau Proteins; D049452:Green Fluorescent Proteins; C015765:MK 473