Interaction of the Tyrosine Kinase Pyk2 with the N-Methyl-d-aspartate Receptor Complex via the Src Homology 3 Domains of PSD-95 and SAP102

Abstract

At low stimulus frequency, synaptic transmission depends largely upon ␣-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) 1 -type glutamate receptors (1, 2). High frequency stimulation promotes Ca 2ϩ influx through N-methyl-D-aspartate (NMDA) receptors, thereby inducing long term potentiation (LTP) (1,3,4). LTP is a lasting increase in synaptic transmission that may underlie learning and memory (5, 6). NMDA receptors likely consist of one or two NR1 and two or three NR2 subunits; each subunit has an extracellular N terminus and an intracellular C terminus (7-10). The very C termini of NR2 subunits interact with the first two PDZ domains of PSD-95/SAP90 and the related proteins SAP102 and PSD-93/chapsyn110. PSD-95 and its homologs (SAP102, PSD-93, and SAP97) are scaffolding proteins consisting of three PDZ domains, one SH3 domain, and one GK domain. PSD-95, PSD-93, and SAP102 are thought to be involved in clustering glutamate receptors together with other proteins at postsynaptic sites (11-15). SAP97 interacts with the AMPA receptor subunit GluR1 (16 -18). SAP97 colocalizes with GluR1, but not GluR2/3, at postsynaptic sites (17). This interaction may already occur early in the secretory pathway and may be involved in trafficking or targeting of AMPA receptors (19).SH3 and GK domains of PSD-95 and its homologs form intramolecular and, to some degree, intermolecular interactions (20 -24). A point mutation in the Drosophila protein Dlg (a homolog of PSD-95) results in the substitution of a conserved leucine in the SH3 domain to a proline; this mutation leads to the loss of septate junction formation and overproliferation of the imaginal disc (25). Replacing the homologous leucine (Leu-460) with a proline in the SH3 domain of PSD-95 inhibits the interaction of the mutant SH3 domain with the GK domain (20,22). Collectively these findings indicate the physiological importance of the SH3-GK domain interaction, but a molecular function of this interaction remains to be established.Tyrosine phosphorylation of NR2B (26, 27) is augmented on LTP induction (28, 29), and several observations suggest that up-regulation of NMDA receptor activity by Src-mediated tyrosine phosphorylation is an important step in the induction of LTP. 1) Src increases NMDA receptor activity (30 -32) by elevating its peak current (33), 2) the activity of Src is up-regulated during LTP (34), 3) inhibition of Src can prevent LTP (30), and 4) an increase in synaptic transmission on Src activation occludes subsequent LTP induction (34).It is well established that Src can be activated by another tyrosine kinase, Pyk2/CAK␤/CADTK (35-38). Pyk2 is stimulated upon Ca 2ϩ influx, activation of PKC by phorbol esters, or stimulation of G q -linked receptors such as the muscarinic acetylcholine receptor M1 or the metabotropic glutamate receptor mGluR1 (35, 37, 39 -48). Neither Ca 2ϩ nor PKC appear to directly regulate Pyk2 in vitro (39); how Ca 2ϩ or PKC activates Pyk2 in vivo is unknown. When stimulated, Pyk2 autophosphorylates itself on tyrosine 402. The...

Signaling Mechanism of HIV-1 gp120 and Virion-Induced IL-1β Release in Primary Human Macrophages

“…Lyn, PI3K, and Pyk2 all possess structural motifs known to facilitate protein-protein interactions. Lyn and PI3K each contain both SH2 domains that may interact with phosphorylated tyrosine residues and SH3 domains that can bind to proline-rich motifs (64,65), whereas PI3K and Pyk2 possess proline-rich motifs that could interact with SH3 domains (66,67). Furthermore, all three kinases contain tyrosine residues that undergo phosphorylation upon activation (68 -70).…”

Non-receptor-tyrosine Kinases Integrate Fast Glucocorticoid Signaling in Hippocampal Neurons

“…Pathway-TKs are expressed in neurons and are particularly enriched in synapses (21)(22)(23)(24) where they phosphorylate and activate a range of substrates (25). A first set of experiments investigated the overall activation of tyrosine kinases after exposure of hippocampal neurons to CORT.…”

Calcineurin is essential for depolarization-induced nuclear translocation and tyrosine phosphorylation of PYK2 in neurons

“…PYK2 regulation by calcineurin Menegon et al, 1999). Although it is likely that PYK2 plays an important role in post-synaptic densities, because of its interaction with NMDA receptors and associated scaffold proteins (Bongiorno-Borbone et al, 2005;Cheung et al, 2000;Heidinger et al, 2002;Liu et al, 2001;Seabold et al, 2003), it does not appear to be enriched in spines. By contrast, deleted or mutated forms of PYK2 accumulate in the nucleus of transfected COS-7 cells (Aoto et al, 2002) and PYK2 is localized in the nucleus in chondrocytes and keratinocytes (Arcucci et al, 2006;Schindler et al, 2007).…”