title: Phospho-regulation of synaptic and extrasynaptic N-methyl-d-aspartate receptors in adult hippocampal slices.
abstract: Recent evidence demonstrates that N-methyl-d-aspartate receptor (NMDAR) trafficking contributes to synaptic plasticity in the hippocampus. Phosphorylation of tyrosine residues, especially NR2B tyrosine 1472, appears to be a mechanism by which NMDAR endocytosis is prevented, suggesting that the tyrosine phosphorylation and surface expression of NMDARs are positively correlated. Previous work from our laboratory and others has confirmed that modulation of tyrosine phosphatase and kinase activity alters the surface expression of NMDARs. However, the changes in NMDAR surface expression described in those studies were in terms of total surface membrane versus intracellular receptors. Within the plasma membrane of glutamatergic synapses, distinct populations of NMDARs exist. Namely, receptors at the surface can be differentiated into synaptic and extrasynaptic pools based on their association with the post-synaptic density (PSD) and availability to glutamate. In the present study, we utilized a subcellular fractionation approach coupled with detergent extraction to prepare synaptic and extrasynaptic NMDARs from adult rat hippocampal slices. Using this method, we examined how tyrosine phosphatase and Src-family tyrosine kinase (SFK) inhibitors modulate the phosphorylation and localization of these different pools of NMDARs. We found that both synaptic and extrasynaptic NMDARs were modulated by tyrosine phosphatase and SFK inhibitors; however subunit- and residue-specific effects were observed. Specifically, phosphorylation of NR2B tyrosine 1472 was associated with enrichment of synaptic NMDARs, whereas phosphorylation of NR2B tyrosine 1336 was associated with enrichment of extrasynaptic NMDARs. Using electrophysiological methods, we also reveal that the biochemical modifications produced by these inhibitors were associated with corresponding changes in NMDAR function.
authors.affiliation: University of Colorado Denver Anschutz Medical Campus, Aurora, CO 80045, USA.
authors.forename: S M
authors.initials: SM
authors.lastname: Goebel-Goody
authors.forename: K D
authors.initials: KD
authors.lastname: Davies
authors.forename: R M
authors.initials: RM
authors.lastname: Alvestad Linger
authors.forename: R K
authors.initials: RK
authors.lastname: Freund
authors.forename: M D
authors.initials: MD
authors.lastname: Browning
mesh_terms: D000818:Animals; D001640:Bicuculline / Q000494:pharmacology; D055592:Biophysical Phenomena; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects / Q000502:physiology; D018756:GABA Antagonists / Q000494:pharmacology; D018698:Glutamic Acid / Q000378:metabolism; D006624:Hippocampus / Q000166:cytology*; D047468:Immunoprecipitation / Q000379:methods; D066298:In Vitro Techniques; D008297:Male; D009473:Neuronal Plasticity / Q000502:physiology*; D009474:Neurons / Q000187:drug effects / Q000378:metabolism; D009942:Organometallic Compounds / Q000494:pharmacology; D018408:Patch-Clamp Techniques; D010618:Phenanthrolines / Q000494:pharmacology; D010766:Phosphorylation / Q000187:drug effects; D021122:Protein Subunits / Q000378:metabolism; D021381:Protein Transport; D017027:Protein Tyrosine Phosphatases / Q000037:antagonists & inhibitors; D011810:Quinoxalines / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D016194:Receptors, N-Methyl-D-Aspartate / Q000037:antagonists & inhibitors / Q000378:metabolism*; D013347:Subcellular Fractions / Q000378:metabolism / Q000648:ultrastructure; D013569:Synapses / Q000502:physiology* / Q000648:ultrastructure; D014443:Tyrosine / Q000378:metabolism
chemical_list: D018756:GABA Antagonists; D009942:Organometallic Compounds; D010618:Phenanthrolines; D021122:Protein Subunits; D011810:Quinoxalines; D016194:Receptors, N-Methyl-D-Aspartate; C062865:2,3-dioxo-6-nitro-7-sulfamoylbenzo(f)quinoxaline; D018698:Glutamic Acid; D014443:Tyrosine; C102120:bisperoxo(1,10-phenanthroline)oxovanadate(1-); D017027:Protein Tyrosine Phosphatases; D001640:Bicuculline