title: Phosphorylation of GluR4 AMPA-type glutamate receptor subunit by protein kinase C in cultured retina amacrine neurons.
abstract: We have previously reported that the activity of alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA) receptors is potentiated by protein kinase C (PKC) in cultured chick retina amacrine neurons, and that constitutive PKC activity is necessary for basal AMPA receptor activity (Carvalho et al., 1998). In this study, we evaluated the phosphorylation of the GluR4 subunit, which is very abundant in cultured amacrine neurons, to correlate it with the effects of PKC on AMPA receptor activity in these cells. 32P-labelling of GluR4 increased upon AMPA receptor stimulation or cell treatment with phorbol 12-myristate 13-acetate (PMA) before stimulating with kainate. By contrast, phosphorylation of GluR4 was not changed when PKC was inhibited by treating the cells with the selective PKC inhibitor GF 109203X before stimulation with kainate. We conclude that GluR4 is phosphorylated upon PKC activation and/or stimulation of AMPA receptors in cultured amacrine cells. Additionally, AMPA receptor activation with kainate in cultured chick amacrine cells leads to translocation of conventional and novel PKC isoforms to the cell membrane, suggesting that PKC could be activated upon AMPA receptor stimulation in these cells.
authors.affiliation: Centre for Neuroscience and Cell Biology, University of Coimbra, Portugal. alc@imagem.ibili.uc.pt
authors.forename: Ana Luísa
authors.initials: AL
authors.lastname: Carvalho
authors.forename: Susana
authors.initials: S
authors.lastname: Correia
authors.forename: Carlos J
authors.initials: CJ
authors.lastname: Faro
authors.forename: Carlos B
authors.initials: CB
authors.lastname: Duarte
authors.forename: Arsélio P
authors.initials: AP
authors.lastname: Carvalho
authors.forename: Euclides M V
authors.initials: EM
authors.lastname: Pires
mesh_terms: D025042:Amacrine Cells / Q000166:cytology / Q000187:drug effects / Q000201:enzymology*; D000818:Animals; D002478:Cells, Cultured; D002642:Chick Embryo; D004791:Enzyme Inhibitors / Q000494:pharmacology; D018698:Glutamic Acid / Q000378:metabolism*; D007608:Kainic Acid / Q000494:pharmacology; D010766:Phosphorylation; D020033:Protein Isoforms / Q000378:metabolism; D011493:Protein Kinase C / Q000378:metabolism* / Q000494:pharmacology; D021381:Protein Transport / Q000187:drug effects / Q000502:physiology; D018091:Receptors, AMPA / Q000187:drug effects / Q000378:metabolism*; D018092:Kainic Acid Receptors / Q000378:metabolism; D013569:Synapses / Q000187:drug effects / Q000201:enzymology*; D013570:Synaptic Membranes / Q000187:drug effects / Q000378:metabolism; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology*
chemical_list: D004791:Enzyme Inhibitors; D018698:Glutamic Acid; D007608:Kainic Acid; D020033:Protein Isoforms; D011493:Protein Kinase C; D018091:Receptors, AMPA; D018092:Kainic Acid Receptors; C104724:glutamate receptor ionotropic, AMPA 4