title: The upregulation of NR2A-containing N-methyl-D-aspartate receptor function by tyrosine phosphorylation of postsynaptic density 95 via facilitating Src/proline-rich tyrosine kinase 2 activation.
abstract: The activation of postsynaptic N-methyl-D-aspartate (NMDA) receptors is required for long-term potentiation (LTP) of synaptic transmission. Postsynaptic density 95 (PSD-95) serves as a scaffold protein that tethers NMDA receptor subunits, kinases, and signal molecules. Our previous study proves that PSD-95 is a substrate of Src/Fyn and identifies Y523 on PSD-95 as a principal phosphorylation site. In this paper, we try to define an involvement and molecular consequences of PSD-95 phosphorylation by Src in NMDA receptor regulation. We found that either NMDA or chemical LTP induction leads to rapid phosphorylation of PSD-95 by Src in cultured cortical neurons. The phosphorylation of Y523 on PSD-95 potentiates NR2A-containing NMDA receptor current amplitude, implying an important role of Src-mediated PSD-95 phosphorylation in NMDA receptor activation. Comparing to wild-type PSD-95, overexpression of nonphosphorylatable mutant PSD-95Y523F attenuated the NMDA-stimulated NR2A tyrosine phosphorylation that enhances electrophysiological responses of NMDA receptor channels, while did not affect the membrane localization of NR2A subunits. PSD-95Y523D, a phosphomimetic mutant of PSD-95, induced NR2A tyrosine phosphorylation even if there was no NMDA treatment. In addition, the deficiency of Y523 phosphorylation on PSD-95 impaired the facilitatory effect of PSD-95 on the activation of Src and proline-rich tyrosine kinase 2 (Pyk2) and decreased the binding of Pyk2 with PSD-95. These results indicate that PSD-95 phosphorylation by Src facilitates the integration of Pyk2 to PSD-95 signal complex, the activation of Pyk2/Src, as well as the subsequent tyrosine phosphorylation of NR2A, which ultimately results in the upregulation of NMDA receptor function and synaptic transmission.
authors: Jiangsu Key Laboratory of Brain Disease Bioinformation, Research Center for Biochemistry and Molecular Biology, Xuzhou Medical College, 209 Tongshan Road, Xuzhou, Jiangsu, 221004, China.
authors: Chao
authors: C
authors: Zhao
authors: Cai-Ping
authors: CP
authors: Du
authors: Yan
authors: Y
authors: Peng
authors: Zhen
authors: Z
authors: Xu
authors: Chang-Cheng
authors: CC
authors: Sun
authors: Yong
authors: Y
authors: Liu
authors: Xiao-Yu
authors: XY
authors: Hou
mesh_terms: D000818:Animals; D000076122:Disks Large Homolog 4 Protein; D004789:Enzyme Activation / Q000502:physiology; D051418:Focal Adhesion Kinase 2 / Q000378:metabolism*; D057809:HEK293 Cells; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism*; D010766:Phosphorylation / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D016194:Receptors, N-Methyl-D-Aspartate / Q000096:biosynthesis*; D014443:Tyrosine / Q000378:metabolism*; D015854:Up-Regulation / Q000502:physiology*; D019061:src-Family Kinases / Q000378:metabolism*
chemical_list: D000076122:Disks Large Homolog 4 Protein; D051418:Focal Adhesion Kinase 2; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D016194:Receptors, N-Methyl-D-Aspartate; D014443:Tyrosine; D019061:src-Family Kinases; C501449:Dlg4 protein, rat