title: Aβ and NMDAR activation cause mitochondrial dysfunction involving ER calcium release.
abstract: Early cognitive deficits in Alzheimer's disease (AD) seem to be correlated to dysregulation of glutamate receptors evoked by amyloid-beta (Aβ) peptide. Aβ interference with the activity of N-methyl-d-aspartate receptors (NMDARs) may be a relevant factor for Aβ-induced mitochondrial toxicity and neuronal dysfunction. To evaluate the role of mitochondria in NMDARs activation mediated by Aβ, we followed in situ single-cell simultaneous measurement of cytosolic free Ca(2+)(Cai(2+)) and mitochondrial membrane potential in primary cortical neurons. Our results show that direct exposure to Aβ + NMDA largely increased Cai(2+) and induced immediate mitochondrial depolarization, compared with Aβ or NMDA alone. Mitochondrial depolarization induced by rotenone strongly inhibited the rise in Cai(2+) evoked by Aβ or NMDA, suggesting that mitochondria control Ca(2+) entry through NMDARs. However, incubation with rotenone did not preclude mitochondrial Ca(2+) (mitCa(2+)) retention in cells treated with Aβ. Aβ-induced Cai(2+) and mitCa(2+) rise were inhibited by ifenprodil, an antagonist of GluN2B-containing NMDARs. Exposure to Aβ + NMDA further evoked a higher mitCa(2+) retention, which was ameliorated in GluN2B(-/-) cortical neurons, largely implicating the involvement of this NMDAR subunit. Moreover, pharmacologic inhibition of endoplasmic reticulum (ER) inositol-1,4,5-triphosphate receptor (IP3R) and mitCa(2+) uniporter (MCU) evidenced that Aβ + NMDA-induced mitCa(2+) rise involves ER Ca(2+) release through IP3R and mitochondrial entry by the MCU. Altogether, data highlight mitCa(2+) dyshomeostasis and subsequent dysfunction as mechanisms relevant for early neuronal dysfunction in AD linked to Aβ-mediated GluN2B-composed NMDARs activation.
authors.affiliation: Center for Neuroscience and Cell Biology (CNC), University of Coimbra, Coimbra, Portugal; Institute for Interdisciplinary Research of the University of Coimbra (IIIUC), Coimbra, Portugal.
authors.forename: Ildete Luísa
authors.initials: IL
authors.lastname: Ferreira
authors.affiliation: Center for Neuroscience and Cell Biology (CNC), University of Coimbra, Coimbra, Portugal; Institute for Interdisciplinary Research of the University of Coimbra (IIIUC), Coimbra, Portugal.
authors.forename: Elisabete
authors.initials: E
authors.lastname: Ferreiro
authors.affiliation: Center for Neuroscience and Cell Biology (CNC), University of Coimbra, Coimbra, Portugal; Institute for Interdisciplinary Research of the University of Coimbra (IIIUC), Coimbra, Portugal; PhD Programme in Experimental Biology and Biomedicine (PDBEB), Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal.
authors.forename: Jeannette
authors.initials: J
authors.lastname: Schmidt
authors.affiliation: Instrumentation Center, Physics Department, University of Coimbra, Coimbra, Portugal.
authors.forename: João M
authors.initials: JM
authors.lastname: Cardoso
authors.affiliation: Center for Neuroscience and Cell Biology (CNC), University of Coimbra, Coimbra, Portugal; Institute for Interdisciplinary Research of the University of Coimbra (IIIUC), Coimbra, Portugal; Faculty of Medicine, University of Coimbra, Coimbra, Portugal.
authors.forename: Cláudia M F
authors.initials: CM
authors.lastname: Pereira
authors.affiliation: Center for Neuroscience and Cell Biology (CNC), University of Coimbra, Coimbra, Portugal; Institute for Interdisciplinary Research of the University of Coimbra (IIIUC), Coimbra, Portugal; Department of Life Sciences, University of Coimbra, Coimbra, Portugal.
authors.forename: Ana Luísa
authors.initials: AL
authors.lastname: Carvalho
authors.affiliation: Center for Neuroscience and Cell Biology (CNC), University of Coimbra, Coimbra, Portugal; Institute for Interdisciplinary Research of the University of Coimbra (IIIUC), Coimbra, Portugal; Faculty of Medicine, University of Coimbra, Coimbra, Portugal.
authors.forename: Catarina R
authors.initials: CR
authors.lastname: Oliveira
authors.affiliation: Center for Neuroscience and Cell Biology (CNC), University of Coimbra, Coimbra, Portugal; Institute for Interdisciplinary Research of the University of Coimbra (IIIUC), Coimbra, Portugal; Faculty of Medicine, University of Coimbra, Coimbra, Portugal. Electronic address: a.cristina.rego@gmail.com.
authors.forename: A Cristina
authors.initials: AC
authors.lastname: Rego
mesh_terms: D000544:Alzheimer Disease / Q000209:etiology / Q000523:psychology; D016229:Amyloid beta-Peptides / Q000378:metabolism* / Q000633:toxicity; D000818:Animals; D001507:Beclomethasone; D002118:Calcium / Q000378:metabolism*; D002540:Cerebral Cortex / Q000166:cytology; D003071:Cognition; D003600:Cytosol / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D053496:Inositol 1,4,5-Trisphosphate Receptors / Q000187:drug effects; D053078:Membrane Potential, Mitochondrial; D008822:Mice, Transgenic; D008928:Mitochondria / Q000378:metabolism*; D009474:Neurons / Q000648:ultrastructure; D010880:Piperidines / Q000494:pharmacology; D017208:Rats, Wistar; D016194:Receptors, N-Methyl-D-Aspartate / Q000037:antagonists & inhibitors / Q000378:metabolism*; D012402:Rotenone / Q000494:pharmacology
chemical_list: D016229:Amyloid beta-Peptides; D053496:Inositol 1,4,5-Trisphosphate Receptors; C121001:NR2B NMDA receptor; D010880:Piperidines; D016194:Receptors, N-Methyl-D-Aspartate; D012402:Rotenone; D001507:Beclomethasone; C010739:ifenprodil; D002118:Calcium
keywords: Alzheimer's disease; Amyloid-β oligomers; Calcium; GluN2B subunit; Mitochondria; N-methyl-d-aspartate receptor