title: Characterization of the intracellular transport of GluR1 and GluR2 alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptor subunits in hippocampal neurons.
abstract: Little is known about the dynamics of the dendritic transport of alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptors (AMPARs) to synapses. Here, using virally expressed green fluorescent protein (GFP)-GluR1 and GFP-GluR2 and confocal photobleach techniques we show near real-time movement of these subunits in living cultured hippocampal neurons. GFP-GluR1 fluorescence was widely distributed throughout the extranuclear compartment with no evidence for discrete intracellular stores. GFP-GluR1 transport was predominantly proximal to distal at rates of 0.2-0.4 mum.s-1. GFP-GluR2 fluorescence was more punctate and localized at or close to the plasma membrane. Overall, GFP-GluR2 movement was less dynamic with distinct mobile and immobile pools. Neither activation nor inhibition of surface-expressed N-methyl-d-aspartate receptors or AMPARs had any significant effect on the rates of GFP-GluR1 or GFP-GluR2 dendritic transport. These results demonstrate that GluR1 is constitutively and rapidly transported throughout the neuron. GluR2, on the other hand, is less mobile, with a majority retained in relatively immobile membrane-associated clusters, with approximately 40% showing synaptic co-localization. Furthermore, the transport of both subunits is activity-independent, suggesting that the regulated delivery of AMPARs to the vicinity of synapses is not a mechanism that is involved in processes such as synaptic plasticity.
authors.affiliation: Medical Research Council Centre for Synaptic Plasticity, Department of Anatomy, University of Bristol, School of Medical Sciences, University Walk, Bristol BS8 1TD, United Kingdom.
authors.forename: Pavel V
authors.initials: PV
authors.lastname: Perestenko
authors.forename: Jeremy M
authors.initials: JM
authors.lastname: Henley
mesh_terms: D000818:Animals; D001692:Biological Transport; D015153:Blotting, Western; D002462:Cell Membrane / Q000378:metabolism; D002467:Cell Nucleus / Q000378:metabolism; D002478:Cells, Cultured; D004247:DNA / Q000378:metabolism; D049452:Green Fluorescent Proteins; D006624:Hippocampus / Q000196:embryology / Q000378:metabolism*; D007150:Immunohistochemistry; D008164:Luminescent Proteins / Q000378:metabolism; D018613:Microscopy, Confocal; D009474:Neurons / Q000378:metabolism*; D011233:Precipitin Tests; D021381:Protein Transport; D051381:Rats; D018091:Receptors, AMPA / Q000737:chemistry* / Q000378:metabolism*; D013997:Time Factors
chemical_list: D004247:DNA; D049452:Green Fluorescent Proteins; D008164:Luminescent Proteins; D018091:Receptors, AMPA; C104722:glutamate receptor ionotropic, AMPA 2