Article

Regulation of stargazin synaptic trafficking by C-terminal PDZ ligand phosphorylation in bidirectional synaptic plasticity.

Davee Department of Neurology and Clinical Neurosciences, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611-3008, USA.
Journal of Neurochemistry (Impact Factor: 3.97). 12/2009; 113(1):42-53. DOI: 10.1111/j.1471-4159.2009.06529.x
Source: PubMed

ABSTRACT Stargazin is a transmembrane alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor regulatory protein that controls the surface and synaptic expression of AMPA-type glutamate receptors (AMPARs). Synaptic anchoring of AMPARs is influenced by the interaction between stargazin's C-terminal post-synaptic density-95 (PSD-95)/discs large/zona occludens-1 (PDZ) ligand and the synaptic scaffolding protein PSD-95. Phosphorylation of the stargazin PDZ ligand by protein kinase A (PKA) disrupts stargazin's interaction with PSD-95, but whether this phosphorylation plays a role in activity-dependent regulation of stargazin/AMPAR synaptic trafficking is unknown. Here, we show that stargazin is phosphorylated within the PDZ ligand at threonine residue 321 (T321) by mitogen-activated protein kinases (MAPKs) as well as PKA. By expressing constructs that selectively block T321 phosphorylation by either PKA or MAPKs, we show that stargazin T321 phosphorylation is required for activity-dependent changes in stargazin synaptic clustering in dissociated rat hippocampal neuron cultures. Specifically, we find that mutations that block stargazin T321 phosphorylation by PKA prevent activity-dependent increases in stargazin synaptic clustering, whereas a point mutant that blocks MAPK phosphorylation of T321 prevents activity-dependent decreases in stargazin synaptic clustering. Taken together, our studies implicate phosphorylation of stargazin T321 by PKA and MAPKs in bidirectional control of stargazin/AMPAR synaptic clustering during synaptic plasticity.

0 Bookmarks
 · 
112 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We previously described - studying transcriptional signatures of hippocampal CA3 explants - that febrile (FS) and afebrile (NFS) forms of refractory mesial temporal lobe epilepsy constitute two distinct genomic phenotypes. That network analysis was based on a limited number (hundreds) of differentially expressed genes (DE networks) among a large set of valid transcripts (close to two tens of thousands). Here we developed a methodology for complex network visualization (3D) and analysis that allows the categorization of network nodes according to distinct hierarchical levels of gene-gene connections (node degree) and of interconnection between node neighbors (concentric node degree). Hubs are highly connected nodes, VIPs have low node degree but connect only with hubs, and high-hubs have VIP status and high overall number of connections. Studying the whole set of CA3 valid transcripts we: i) obtained complete transcriptional networks (CO) for FS and NFS phenotypic groups; ii) examined how CO and DE networks are related; iii) characterized genomic and molecular mechanisms underlying FS and NFS phenotypes, identifying potential novel targets for therapeutic interventions. We found that: i) DE hubs and VIPs are evenly distributed inside the CO networks; ii) most DE hubs and VIPs are related to synaptic transmission and neuronal excitability whereas most CO hubs, VIPs and high hubs are related to neuronal differentiation, homeostasis and neuroprotection, indicating compensatory mechanisms. Complex network visualization and analysis is a useful tool for systems biology approaches to multifactorial diseases. Network centrality observed for hubs, VIPs and high hubs of CO networks, is consistent with the network disease model, where a group of nodes whose perturbation leads to a disease phenotype occupies a central position in the network. Conceivably, the chance for exerting therapeutic effects through the modulation of particular genes will be higher if these genes are highly interconnected in transcriptional networks.
    PLoS ONE 01/2013; 8(11):e79913. · 3.53 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Ionotropic glutamate receptors (iGluRs) underlie rapid, excitatory synaptic signaling throughout the CNS. After years of intense research, our picture of iGluRs has evolved from them being companionless in the postsynaptic membrane to them being the hub of dynamic supramolecular signaling complexes, interacting with an ever-expanding litany of other proteins that regulate their trafficking, scaffolding, stability, signaling, and turnover. In particular, the discovery that transmembrane AMPA receptor regulatory proteins (TARPs) are AMPA receptor auxiliary subunits that are critical determinants of their trafficking, gating, and pharmacology has changed the way we think about iGluR function. Recently, a number of novel transmembrane proteins have been uncovered that may also serve as iGluR auxiliary proteins. Here we review pivotal developments in our understanding of the role of TARPs in AMPA receptor trafficking and gating, and provide an overview of how newly discovered transmembrane proteins expand our view of iGluR function in the CNS.
    Neuron 04/2011; 70(2):178-99. · 15.77 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Glutamatergic systems, including AMPA receptors (AMPARs), are involved in opiate-induced neuronal and behavioral plasticity, although the mechanisms underlying these effects are not fully understood. In the present study, we investigated the effects of repeated morphine administration on AMPAR expression, synaptic plasticity, and context-dependent behavioral sensitization to morphine. We found that morphine treatment produced changes of synaptic AMPAR expression in the hippocampus, a brain area that is critically involved in learning and memory. These changes could be observed 1 week after the treatment, but only when mice developed context-dependent behavioral sensitization to morphine in which morphine treatment was associated with drug administration environment. Context-dependent behavioral sensitization to morphine was also associated with increased basal synaptic transmission and disrupted hippocampal long-term potentiation (LTP), whereas these effects were less robust when morphine administration was not paired with the drug administration environment. Interestingly, some effects may be related to the prior history of morphine exposure in the drug-associated environment, since alterations of AMPAR expression, basal synaptic transmission, and LTP were observed in mice that received a saline challenge 1 week after discontinuation of morphine treatment. Furthermore, we demonstrated that phosphorylation of GluA1 AMPAR subunit plays a critical role in the acquisition and expression of context-dependent behavioral sensitization, as this behavior is blocked by a viral vector that disrupts GluA1 phosphorylation. These data provide evidence that glutamatergic signaling in the hippocampus plays an important role in context-dependent sensitization to morphine and supports further investigation of glutamate-based strategies for treating opiate addiction.
    Journal of Neuroscience 11/2011; 31(45):16279-91. · 6.91 Impact Factor

Full-text

View
0 Downloads