title: Interactions between NEEP21, GRIP1 and GluR2 regulate sorting and recycling of the glutamate receptor subunit GluR2.
abstract: Trafficking of AMPA-type glutamate receptors (AMPAR) between endosomes and the postsynaptic plasma membrane of neurons plays a central role in the control of synaptic strength associated with learning and memory. The molecular mechanisms of its regulation remain poorly understood, however. Here we show by biochemical and atomic force microscopy analyses that NEEP21, a neuronal endosomal protein necessary for receptor recycling including AMPAR, is associated with the scaffolding protein GRIP1 and the AMPAR subunit GluR2. Moreover, the interaction between NEEP21 and GRIP1 is regulated by neuronal activity. Expression of a NEEP21 fragment containing the GRIP1-binding site decreases surface GluR2 levels and delays recycling of internalized GluR2, which accumulates in early endosomes and lysosomes. Infusion of this fragment into pyramidal neurons of hippocampal slices induces inward rectification of AMPAR-mediated synaptic responses, suggesting decreased GluR2 expression at synapses. These results indicate that NEEP21-GRIP1 binding is crucial for GluR2-AMPAR sorting through endosomes and their recruitment to the plasma membrane, providing a first molecular mechanism to differentially regulate AMPAR subunit cycling in internal compartments.
authors.affiliation: Brain Mind Institute, Faculté des Sciences de la Vie, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland.
authors.forename: Pascal
authors.initials: P
authors.lastname: Steiner
authors.forename: Stefano
authors.initials: S
authors.lastname: Alberi
authors.forename: Karina
authors.initials: K
authors.lastname: Kulangara
authors.forename: Alexandre
authors.initials: A
authors.lastname: Yersin
authors.forename: Juan-Carlos Floyd
authors.initials: JC
authors.lastname: Sarria
authors.forename: Etienne
authors.initials: E
authors.lastname: Regulier
authors.forename: Sandor
authors.initials: S
authors.lastname: Kasas
authors.forename: Giovanni
authors.initials: G
authors.lastname: Dietler
authors.forename: Dominique
authors.initials: D
authors.lastname: Muller
authors.forename: Stefan
authors.initials: S
authors.lastname: Catsicas
authors.forename: Harald
authors.initials: H
authors.lastname: Hirling
mesh_terms: D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism*; D002850:Chromatography, Gel; D004594:Electrophysiology; D011992:Endosomes / Q000378:metabolism*; D005455:Fluorescent Antibody Technique; D005786:Gene Expression Regulation; D006624:Hippocampus / Q000378:metabolism; D047468:Immunoprecipitation; D047908:Intracellular Signaling Peptides and Proteins; D018625:Microscopy, Atomic Force; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D009474:Neurons / Q000378:metabolism*; D021381:Protein Transport / Q000502:physiology; D051381:Rats; D018091:Receptors, AMPA / Q000378:metabolism*; D013569:Synapses / Q000378:metabolism*
chemical_list: D002352:Carrier Proteins; C491308:Grip1 protein, rat; D047908:Intracellular Signaling Peptides and Proteins; D009419:Nerve Tissue Proteins; C461339:Nsg1 protein, rat; D018091:Receptors, AMPA; C104722:glutamate receptor ionotropic, AMPA 2