Regulation of A-Kinase Anchoring Protein 79/150–cAMP-Dependent Protein Kinase Postsynaptic Targeting by NMDA Receptor Activation of Calcineurin and Remodeling of Dendritic Actin

Abstract

At the postsynaptic membrane of glutamatergic synapses, the cAMP-dependent protein kinase (PKA), protein kinase C (PKC), and calcineurin (CaN) anchoring protein AKAP79/150 is recruited to NMDA and AMPA glutamate receptors by postsynaptic density (PSD)-95 family membrane-associated guanylate kinase (MAGUK) scaffold proteins. These signaling scaffold complexes may function to regulate receptor phosphorylation in synaptic plasticity. Thus, it is important to understand regulation of AKAP79/150 targeting to synapses and recruitment to PSD-MAGUK complexes. AKAP79 is targeted to the plasma membrane by an N-terminal basic domain that binds phosphatidylinositol-4,5-bisphosphate (PI-4,5-P(2)) and is regulated by PKC phosphorylation and calmodulin binding. Here we demonstrate that this same domain also binds F-actin in a calmodulin- and PKC-regulated manner, targets to membrane ruffles enriched in F-actin and PI-4,5-P(2) in COS7 cells, and localizes to dendritic spines with F-actin and PSD-MAGUKs in hippocampal neurons. Inhibition of actin polymerization disrupted AKAP79 targeting of PKA and CaN to ruffles in COS7 cells and endogenous AKAP79/150 dendritic spine localization with PKA, CaN, and PSD-MAGUKs in neurons. AKAP79/150 postsynaptic localization was rapidly regulated by NMDA receptors through CaN activation and F-actin remodeling, further suggesting that AKAP79/150 signaling scaffold targeting depends on actin dynamics. NMDA receptor activation also regulated dendritic spine localization of PKA and CaN and association of the AKAP79/150-PKA complex with PSD-MAGUKs. Because AMPA receptor PKA phosphorylation and synaptic localization are regulated by similar NMDA receptor-CaN signaling pathways linked to hippocampal long-term depression, this regulation of AKAP79/150 postsynaptic targeting might be important for synaptic plasticity.

Protein Phosphatases and Calcium/Calmodulin-Dependent Protein Kinase II-Dependent Synaptic Plasticity: Figure 1.

“…1 A, B) (Colledge et al, 2000). NMDA receptor activation disrupts the colocalization and coimmunoprecipitation of AKAP79/150 with PSD95 family proteins at synapses in cultured neurons, by a mechanism that involves PP2B activity and rearrangement of the actin cytoskeleton (Gomez et al, 2002). This NMDA-induced redistribution of AKAP79/150 appears to be accompanied by parallel changes in PKA localization and a subcellular redistribution of PP2B.…”

“…Because PP2B is activated at lower Ca 2ϩ /calmodulin concentrations than CaMKII, weak synaptic stimulation may preferentially activate PP2B, dephosphorylating inhibitor-1 and thereby activating PP1, whereas stronger stimulation also recruits CaMKII activation (Lisman, 1989). Targeting of PP2B to PSDs can be mediated by binding to AKAP79/150 (Coghlan et al, 1995), a PKA anchoring protein that also binds phosphatidylinositol-4,5-bisphosphate, calmodulin, PKC, and F-actin (Dell'Acqua et al, 1998;Gomez et al, 2002). Additional interactions of AKAP79/ 150 with SAP97 (synapse-associated protein 97) or PSD95 mediate association of PP2B with AMPA-and/or NMDA-type glutamate receptors (Fig.…”

AKAPs (A-kinase anchoring proteins) and molecules that compose their G-protein-coupled receptor signalling complexes

“…In addition to compelling data for inclusion of PKA, PKC, CaN, β 2 AR, Src and GRK2 [69] in the AKAP79/250 signalling complexes, others have reported the association of AMPA/kainate-sensitive glutamate receptors [49,70], NMDA receptors [71], the Kir2.1 ion channel [72], L-type calcium channels [73], GABA A (γ -aminobutyric acid A) receptors [74], as well as cytoskeletal elements [35,71] in these complexes. It is likely that GPCRs other than the β 2 AR make use of AKAPbased signalling complexes, although the reagents available for dependable screening of the multitude of GPCRs are far more limited.…”

Requirement for the RIIβ Isoform of PKA, But Not Calcium-Stimulated Adenylyl Cyclase, in Visual Cortical Plasticity

“…In hippocampus, AKAP150 targets RII-PKA to AMPA receptors (AMPARs), promoting phosphorylation of the Ser845 regulatory site of GluR1 subunits (Colledge et al, 2000;Tavalin et al, 2002). Changes in the phosphorylation state of this GluR1 PKA site regulate both AMPAR function (Banke et al, 2000) and synaptic trafficking (Ehlers, 2000), the two principal mechanisms proposed to account for LTD. NMDA-dependent LTD triggers the protein phosphatase-dependent dissociation of AKAP150/RII␤-PKA complexes from AMPARs (Gomez et al, 2002;Smith and Dell'Acqua, 2003), dephosphorylation of GluR1 Ser845 , and removal of AMPARs from synaptic sites (Carroll et al, 1999;Ehlers, 2000).…”