High impact information on GRIA4

• Our data show that GluR4 phosphorylation at Ser842 by PKA, and its recruitment to the plasma membrane upon phosphorylation, is regulated by metabotropic receptors [1].
• Metabotropic glutamate and dopamine receptors co-regulate AMPA receptor activity through PKA in cultured chick retinal neurones: effect on GluR4 phosphorylation and surface expression [1].
• These results indicate that there is a functional cross-talk between dopamine D1 receptors and group II mGluR in the regulation of GluR4 phosphorylation and AMPA receptor activity [1].
• 4. We conclude that the AMPA receptors of auditory neurons acquire rapid kinetics from their high content of GluR3 flop and GluR4 flop subunits and their high permeability to Ca2+ from selective post-transcriptional suppression of GluR2 expression [2].
• Moreover, GluR2/3 and GluR4 receptor subunit clusters in principal cell bodies and dendrites were localized at sites contacted by biocytin-labeled vestibular nerve terminals and synaptotagmin-labeled terminals [3].

Biological context of GRIA4

• In summary, these results indicate that GluR3 and GluR4 are the major AMPA receptor subunits involved in excitatory synaptic transmission in principal cells during the perinatal period [3].
• To identify chick GluR4 isoforms, we used PCR to amplify a C-terminal region that is the site of alternative splicing in rat [4].

Anatomical context of GRIA4

• Pre-incubation of the cells with (2S,2'R,3'R)-2-(2',3'-dicarboxycyclopropyl)glycine (DCG-IV), an agonist of group II metabotropic glutamate receptors (mGluR), which are coupled to inhibition of AC, inhibited the effect of FSK and of SKF38393 on AMPA receptor activity, GluR4 phosphorylation and expression at the plasma membrane [1].
• We conclude that GluR4 is phosphorylated upon PKC activation and/or stimulation of AMPA receptors in cultured amacrine cells [5].
• GluR1-positive neurons and fibers were found in the nucleus lentiformis mesencephali, but only GluR2/3-positive neurons and GluR4-positive fibers were detected into that nucleus [6].
• Finally, we found that the expression levels of GluR4 at the neurites increased between 5 h in vitro and 7 DIV, near the period of synapse formation [7].
• The functionality of alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate (AMPA) receptors in chick embryo retina cells during development in vitro was studied by using Co(2+) uptake, and these data were correlated with the expression of the AMPA receptor subunit GluR4 [7].

Associations of GRIA4 with chemical compounds

• 32P-labelling of GluR4 increased upon AMPA receptor stimulation or cell treatment with phorbol 12-myristate 13-acetate (PMA) before stimulating with kainate [5].
• 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 [5].
• This study was undertaken to characterize the AMPA (GluR1, GluR2/3, and GluR4), KA (GluR5/6/7), and NMDA (NR1) ionotropic glutamate receptor subunits and to determine their distribution during the development of the chick retina by Western blotting and immunohistochemistry [8].

Other interactions of GRIA4

• Using confocal microscopy, we quantified immunolabeling for AMPA receptor subunits GluR1, GluR2, GluR2/3, and GluR4 in principal cells that were identified by the neuronal marker, microtubule-associated protein 2 (MAP2) [3].

Analytical, diagnostic and therapeutic context of GRIA4

• The expression of the AMPA receptor subunit GluR4 during development was detected by immunofluorescence mainly at the perinuclear region of the cells, and the number of positive cells increased from 5 h in vitro to 7 DIV, and remained relatively constant until 14 DIV [7].

References