title: Sequential delivery of synaptic GluA1- and GluA4-containing AMPA receptors (AMPARs) by SAP97 anchored protein complexes in classical conditioning.
abstract: Multiple signaling pathways are involved in AMPAR trafficking to synapses during synaptic plasticity and learning. The mechanisms for how these pathways are coordinated in parallel but maintain their functional specificity involves subcellular compartmentalization of kinase function by scaffolding proteins, but how this is accomplished is not well understood. Here, we focused on characterizing the molecular machinery that functions in the sequential synaptic delivery of GluA1- and GluA4-containing AMPARs using an in vitro model of eyeblink classical conditioning. We show that conditioning induces the interaction of selective protein complexes with the key structural protein SAP97, which tightly regulates the synaptic delivery of GluA1 and GluA4 AMPAR subunits. The results demonstrate that in the early stages of conditioning the initial activation of PKA stimulates the formation of a SAP97-AKAP/PKA-GluA1 protein complex leading to synaptic delivery of GluA1-containing AMPARs through a SAP97-PSD95 interaction. This is followed shortly thereafter by generation of a SAP97-KSR1/PKC-GluA4 complex for GluA4 AMPAR subunit delivery again through a SAP97-PSD95 interaction. These data suggest that SAP97 forms the molecular backbone of a protein scaffold critical for delivery of AMPARs to the PSD during conditioning. Together, the findings reveal a cooperative interaction of multiple scaffolding proteins for appropriately timed delivery of subunit-specific AMPARs to synapses and support a sequential two-stage model of AMPAR synaptic delivery during classical conditioning.
authors.affiliation: Neuroscience Group, Division of Basic Biomedical Sciences University of South Dakota Sanford School of Medicine, Vermillion, South Dakota 57010.
authors.forename: Zhaoqing
authors.initials: Z
authors.lastname: Zheng
authors.affiliation: Neuroscience Group, Division of Basic Biomedical Sciences University of South Dakota Sanford School of Medicine, Vermillion, South Dakota 57010. Electronic address: jkeifer@usd.edu.
authors.forename: Joyce
authors.initials: J
authors.lastname: Keifer
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism*; D000818:Animals; D001522:Behavior, Animal; D019921:Biotinylation; D002462:Cell Membrane / Q000378:metabolism; D003214:Conditioning, Classical; D051528:Guanylate Kinases / Q000378:metabolism*; D007858:Learning; D018613:Microscopy, Confocal; D009473:Neuronal Plasticity; D010455:Peptides / Q000378:metabolism; D011485:Protein Binding; D018091:Receptors, AMPA / Q000378:metabolism*; D017470:Receptors, Glutamate / Q000378:metabolism*; D016194:Receptors, N-Methyl-D-Aspartate / Q000378:metabolism*; D015398:Signal Transduction; D013569:Synapses / Q000502:physiology*; D009435:Synaptic Transmission; D014426:Turtles
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D051528:Guanylate Kinases; D010455:Peptides; D018091:Receptors, AMPA; D017470:Receptors, Glutamate; D016194:Receptors, N-Methyl-D-Aspartate
keywords: Cell Surface Receptor; Confocal Microscopy; Glutamate Receptors Ionotropic (AMPA, NMDA); Neuroscience; Protein Targeting; Signal Transduction