title: Downregulation of GABAAReceptor Recycling Mediated by HAP1 Contributes to Neuronal Death in In Vitro Brain Ischemia.
abstract: Downregulation of GABAergic synaptic transmission contributes to the increase in overall excitatory activity in the ischemic brain. A reduction of GABAAreceptor (GABAAR) surface expression partly accounts for this decrease in inhibitory activity, but the mechanisms involved are not fully elucidated. In this work, we investigated the alterations in GABAAR trafficking in cultured rat hippocampal neurons subjected to oxygen/glucose deprivation (OGD), an in vitro model of global brain ischemia, and their impact in neuronal death. The traffic of GABAAR was evaluated after transfection of hippocampal neurons with myc-tagged GABAAR β3 subunits. OGD decreased the rate of GABAAR β3 subunit recycling and reduced the interaction of the receptors with HAP1, a protein involved in the recycling of the receptors. Furthermore, OGD induced a calpain-mediated cleavage of HAP1. Transfection of hippocampal neurons with HAP1A or HAP1B isoforms reduced the OGD-induced decrease in surface expression of GABAAR β3 subunits, and HAP1A maintained the rate of receptor recycling. Furthermore, transfection of hippocampal neurons with HAP1 significantly decreased OGD-induced cell death. These results show a key role for HAP1 protein in the downmodulation of GABAergic neurotransmission during cerebral ischemia, which contributes to neuronal demise.
authors.affiliation: CNC-Center for Neuroscience and Cell Biology, Faculty of Medicine (Polo I), University of Coimbra, Rua Larga, 3004-504, Coimbra, Portugal.|Institute for Interdisciplinary Research (IIIUC), University of Coimbra, Coimbra, 3030-789, Portugal.
authors.forename: Miranda
authors.initials: M
authors.lastname: Mele
authors.affiliation: CNC-Center for Neuroscience and Cell Biology, Faculty of Medicine (Polo I), University of Coimbra, Rua Larga, 3004-504, Coimbra, Portugal.|Department of Science and Technology, University of Sannio, Benevento, 82100, Italy.
authors.forename: Maria Cristina
authors.initials: MC
authors.lastname: Aspromonte
authors.affiliation: CNC-Center for Neuroscience and Cell Biology, Faculty of Medicine (Polo I), University of Coimbra, Rua Larga, 3004-504, Coimbra, Portugal. cbduarte@ci.uc.pt.|Department of Life Sciences, University of Coimbra, Coimbra, 3001-401, Portugal. cbduarte@ci.uc.pt.
authors.forename: Carlos B
authors.initials: CB
authors.lastname: Duarte
mesh_terms: D000818:Animals; D002545:Brain Ischemia / Q000378:metabolism* / Q000473:pathology; D016923:Cell Death / Q000502:physiology*; D002478:Cells, Cultured; D015536:Down-Regulation / Q000502:physiology; D006624:Hippocampus / Q000378:metabolism* / Q000473:pathology; D009419:Nerve Tissue Proteins / Q000502:physiology*; D009474:Neurons / Q000378:metabolism* / Q000473:pathology; D021381:Protein Transport / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D011963:Receptors, GABA-A / Q000378:metabolism*
chemical_list: C490757:Hap1 protein, rat; D009419:Nerve Tissue Proteins; D011963:Receptors, GABA-A
keywords: Cerebral ischemia; GABAA receptors; Huntingtin-associated protein 1 (HAP1); Oxygen/glucose deprivation (OGD); Receptor traffic