title: GluN2B-Containing NMDA Receptors Regulate AMPA Receptor Traffic through Anchoring of the Synaptic Proteasome.
abstract: NMDA receptors play a central role in shaping the strength of synaptic connections throughout development and in mediating synaptic plasticity mechanisms that underlie some forms of learning and memory formation in the CNS. In the hippocampus and the neocortex, GluN1 is combined primarily with GluN2A and GluN2B, which are differentially expressed during development and confer distinct molecular and physiological properties to NMDA receptors. The contribution of each subunit to the synaptic traffic of NMDA receptors and therefore to their role during development and in synaptic plasticity is still controversial. We report a critical role for the GluN2B subunit in regulating NMDA receptor synaptic targeting. In the absence of GluN2B, the synaptic levels of AMPA receptors are increased and accompanied by decreased constitutive endocytosis of GluA1-AMPA receptor. We used quantitative proteomic analysis to identify changes in the composition of postsynaptic densities from GluN2B(-/-) mouse primary neuronal cultures and found altered levels of several ubiquitin proteasome system components, in particular decreased levels of proteasome subunits. Enhancing the proteasome activity with a novel proteasome activator restored the synaptic levels of AMPA receptors in GluN2B(-/-) neurons and their endocytosis, revealing that GluN2B-mediated anchoring of the synaptic proteasome is responsible for fine tuning AMPA receptor synaptic levels under basal conditions.
authors.affiliation: Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504 Coimbra, Portugal, Department of Life Sciences, University of Coimbra, 3004-517 Coimbra, Portugal.
authors.forename: Joana S
authors.initials: JS
authors.lastname: Ferreira
authors.affiliation: Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504 Coimbra, Portugal, Doctoral Program in Experimental Biology and Biomedicine, Center for Neuroscience and Cell Biology and Institute for Interdisciplinary Research, University of Coimbra, 3004-504 Coimbra, Portugal.
authors.forename: Jeannette
authors.initials: J
authors.lastname: Schmidt
authors.affiliation: Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504 Coimbra, Portugal, Department of Life Sciences, University of Coimbra, 3004-517 Coimbra, Portugal.
authors.forename: Pedro
authors.initials: P
authors.lastname: Rio
authors.affiliation: Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504 Coimbra, Portugal.
authors.forename: Rodolfo
authors.initials: R
authors.lastname: Águas
authors.affiliation: Brain Research Centre and Department of Psychiatry, University of British Columbia, Vancouver V6T 2B5, Canada, and.
authors.forename: Amanda
authors.initials: A
authors.lastname: Rooyakkers
authors.affiliation: Center for Neurogenomics and Cognitive Research, Neuroscience Campus Amsterdam, VU University, Delaware Boelelaan 1085, 1081 HV, Amsterdam, The Netherlands.
authors.forename: Ka Wan
authors.initials: KW
authors.lastname: Li
authors.affiliation: Center for Neurogenomics and Cognitive Research, Neuroscience Campus Amsterdam, VU University, Delaware Boelelaan 1085, 1081 HV, Amsterdam, The Netherlands.
authors.forename: August B
authors.initials: AB
authors.lastname: Smit
authors.affiliation: Brain Research Centre and Department of Psychiatry, University of British Columbia, Vancouver V6T 2B5, Canada, and.
authors.forename: Ann Marie
authors.initials: AM
authors.lastname: Craig
authors.affiliation: Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504 Coimbra, Portugal, Department of Life Sciences, University of Coimbra, 3004-517 Coimbra, Portugal, alc@cnc.uc.pt.
authors.forename: Ana Luisa
authors.identifier: http://orcid.org/0000-0001-8368-6666
authors.initials: AL
authors.lastname: Carvalho
mesh_terms: D000818:Animals; D001921:Brain / Q000166:cytology*; D002478:Cells, Cultured; D004705:Endocytosis / Q000502:physiology; D018683:Excitatory Amino Acid Agents / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects / Q000235:genetics; D006835:Hydrazones / Q000494:pharmacology; D051379:Mice; D008822:Mice, Transgenic; D009419:Nerve Tissue Proteins / Q000378:metabolism; D009473:Neuronal Plasticity / Q000502:physiology; D009474:Neurons / Q000378:metabolism*; D046988:Proteasome Endopeptidase Complex / Q000235:genetics / Q000378:metabolism; D021122:Protein Subunits / Q000235:genetics / Q000378:metabolism; D021381:Protein Transport / Q000235:genetics; D018091:Receptors, AMPA / Q000378:metabolism*; D016194:Receptors, N-Methyl-D-Aspartate / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D013347:Subcellular Fractions / Q000378:metabolism / Q000648:ultrastructure; D013569:Synapses / Q000187:drug effects / Q000378:metabolism*; D013779:Tetrodotoxin / Q000494:pharmacology; D013997:Time Factors; D020703:ras GTPase-Activating Proteins / Q000378:metabolism
chemical_list: D018683:Excitatory Amino Acid Agents; D006835:Hydrazones; C511794:N'-(3,4-dihydroxybenzylidene)-3-hydroxy-2-naphthahydrazide; C121001:NR2B NMDA receptor; D009419:Nerve Tissue Proteins; D021122:Protein Subunits; D018091:Receptors, AMPA; D016194:Receptors, N-Methyl-D-Aspartate; C484512:Syngap1 protein, mouse; D020703:ras GTPase-Activating Proteins; D013779:Tetrodotoxin; D046988:Proteasome Endopeptidase Complex
keywords: AMPA receptors; GluN2B; NMDA receptors; iTRAQ; postsynaptic density; proteasome