title: Cdk5 regulates the phosphorylation of tyrosine 1472 NR2B and the surface expression of NMDA receptors.
abstract: NMDA receptors (NMDARs) are a major class of ionotropic glutamate receptors that can undergo activity-dependent changes in surface expression. Clathrin-mediated endocytosis is a mechanism by which the surface expression of NR2B-containing NMDA receptors is regulated. The C terminus of the NMDA receptor subunit NR2B contains the internalization motif YEKL, which is the binding site for the clathrin adaptor AP-2. The tyrosine (Y1472) within the YEKL motif is phosphorylated by the Src family of kinases and this phosphorylation inhibits the binding of AP-2 and promotes surface expression of NMDA receptors. Cdk5 is a serine/threonine kinase that has been implicated in synaptic plasticity, learning, and memory. Here we demonstrate that inhibition of Cdk5 results in increased phosphorylation of Y1472 NR2B at synapses and decreased binding of NR2B to beta2-adaptin, a subunit of AP-2, thus blocking the activity-dependent endocytosis of NMDA receptors. Furthermore, we show that inhibition of Cdk5 increases the binding of Src to postsynaptic density-95 (PSD-95), and that expression of PSD-95 facilitates the phosphorylation of Y1472 NR2B by Src. Together, these results suggest a model in which inhibition of Cdk5 increases the binding of Src to PSD-95 and the phosphorylation of Y1472 NR2B by Src, which results in decreased binding of NR2B to AP-2, and NR2B/NMDAR endocytosis. This study provides a novel molecular mechanism for the regulation of the surface expression of NR2B-containing NMDA receptors and gives insight into the Cdk5-dependent regulation of synaptic plasticity.
authors.affiliation: University of Massachusetts Medical School, Department of Cell Biology, Waltham, Massachusetts 02452, USA.
authors.forename: Shuo
authors.initials: S
authors.lastname: Zhang
authors.forename: Lambert
authors.initials: L
authors.lastname: Edelmann
authors.forename: June
authors.initials: J
authors.lastname: Liu
authors.forename: James E
authors.initials: JE
authors.lastname: Crandall
authors.forename: Maria A
authors.initials: MA
authors.lastname: Morabito
mesh_terms: D033962:Adaptor Protein Complex 2 / Q000502:physiology; D000704:Analysis of Variance; D000818:Animals; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000166:cytology; D051360:Cyclin-Dependent Kinase 5 / Q000502:physiology*; D000076122:Disks Large Homolog 4 Protein; D004622:Embryo, Mammalian; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D006801:Humans; D007211:Indoles / Q000494:pharmacology; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D009474:Neurons / Q000187:drug effects / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D011247:Pregnancy; D051381:Rats; D016194:Receptors, N-Methyl-D-Aspartate / Q000378:metabolism*; D054593:SH2 Domain-Containing Protein Tyrosine Phosphatases / Q000378:metabolism; D013449:Sulfonamides / Q000494:pharmacology; D013574:Synaptosomes / Q000187:drug effects / Q000378:metabolism; D014162:Transfection / Q000379:methods; D014443:Tyrosine / Q000378:metabolism*
chemical_list: D033962:Adaptor Protein Complex 2; D000076122:Disks Large Homolog 4 Protein; C501449:Dlg4 protein, rat; D004791:Enzyme Inhibitors; D007211:Indoles; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; C121001:NR2B NMDA receptor; D016194:Receptors, N-Methyl-D-Aspartate; C416927:SU 6656; D013449:Sulfonamides; D014443:Tyrosine; D051360:Cyclin-Dependent Kinase 5; D054593:SH2 Domain-Containing Protein Tyrosine Phosphatases