title: Post-synaptic density-93 mediates tyrosine-phosphorylation of the N-methyl-D-aspartate receptors.
abstract: Src family protein kinases (SFKs) -mediated tyrosine-phosphorylation regulates N-methyl-D-aspartate (NMDA) receptor synaptic function. Some members of the membrane-associated guanylate kinase (MAGUK) family of proteins bind to both SFKs and NMDA receptors, but it is unclear whether the MAGUK family of proteins is required for SFKs-mediated tyrosine-phosphorylation of the NMDA receptors. Here, we showed by co-immunoprecipitation that post-synaptic density (PSD) -93, a member of the MAGUK family of proteins, interacts with the NMDA receptor subunits NR2A and NR2B as well as with Fyn, a member of the SFKs, in mouse cerebral cortex. Using a biochemical fractionation approach to isolate subcellular compartments revealed that the expression of Fyn, but not of other members of the SFKs (Lyn, Src, and Yes), was significantly decreased in synaptosomal membrane fractions derived from the cerebral cortex of PSD-93 knockout mice. Interestingly, we found that PSD-93 disruption causes reduction of tyrosine-phosphorylated NR2A and NR2B in the same fraction. Moreover, PSD-93 deletion markedly blocked the SFKs-mediated increase in tyrosine-phosphorylated NR2A and NR2B through the protein kinase C pathway after induction with 4-phorbol 12-myristate 13-acetate in cultured cortical neurons. Our findings indicate that PSD-93 appears to mediate tyrosine-phosphorylation of the NMDA receptors and synaptic localization of Fyn.
authors.affiliation: Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Sato
authors.forename: Y-X
authors.initials: YX
authors.lastname: Tao
authors.forename: Q
authors.initials: Q
authors.lastname: Su
authors.forename: R A
authors.initials: RA
authors.lastname: Johns
mesh_terms: D000818:Animals; D002540:Cerebral Cortex / Q000378:metabolism*; D051528:Guanylate Kinases; D047468:Immunoprecipitation; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism*; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D010766:Phosphorylation; D051076:Proto-Oncogene Proteins c-fyn / Q000378:metabolism; D016194:Receptors, N-Methyl-D-Aspartate / Q000378:metabolism*; D013574:Synaptosomes / Q000378:metabolism; D019061:src-Family Kinases / Q000378:metabolism
chemical_list: D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; C120997:NR2A NMDA receptor; C121001:NR2B NMDA receptor; D016194:Receptors, N-Methyl-D-Aspartate; C494960:Fyn protein, mouse; D051076:Proto-Oncogene Proteins c-fyn; D019061:src-Family Kinases; C501445:Dlg2 protein, mouse; D051528:Guanylate Kinases