Article

PICK1 interacts with PACSIN to regulate AMPA receptor internalization and cerebellar long-term depression

The Solomon H. Snyder Department of Neuroscience and Howard Hughes Medical Institute, The Johns Hopkins University School of Medicine, Baltimore, MD 21205.
Proceedings of the National Academy of Sciences (Impact Factor: 9.67). 08/2013; 110(34). DOI: 10.1073/pnas.1312467110
Source: PubMed

ABSTRACT

The dynamic trafficking of AMPA receptors (AMPARs) into and out of synapses is crucial for synaptic transmission, plasticity, learning, and memory. The protein interacting with C-kinase 1 (PICK1) directly interacts with GluA2/3 subunits of the AMPARs. Although the role of PICK1 in regulating AMPAR trafficking and multiple forms of synaptic plasticity is known, the exact molecular mechanisms underlying this process remain unclear. Here, we report a unique interaction between PICK1 and all three members of the protein kinase C and casein kinase II substrate in neurons (PACSIN) family and show that they form a complex with AMPARs. Our results reveal that knockdown of the neuronal-specific protein, PACSIN1, leads to a significant reduction in AMPAR internalization following the activation of NMDA receptors in hippocampal neurons. The interaction between PICK1 and PACSIN1 is regulated by PACSIN1 phosphorylation within the variable region and is required for AMPAR endocytosis. Similarly, the binding of PICK1 to the ubiquitously expressed PACSIN2 is also regulated by the homologous phosphorylation sites within the PACSIN2-variable region. Genetic deletion of PACSIN2, which is highly expressed in Purkinje cells, eliminates cerebellar long-term depression. This deficit can be fully rescued by overexpressing wild-type PACSIN2, but not by a PACSIN2 phosphomimetic mutant, which does not bind PICK1 efficiently. Taken together, our data demonstrate that the interaction of PICK1 and PACSIN is required for the activity-dependent internalization of AMPARs and for the expression of long-term depression in the cerebellum.

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Available from: Victor Anggono, Jan 08, 2015
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    • "AMPARs that lack the GRIP interaction are unable to stably incorporate into synapses [27]. PICK1 actively promotes AMPAR endocytosis in cerebellar Purkinje cells [6, 26, 28] and the PICK1-AMPAR interaction is indispensable for PF-PC LTD expression [6, 10,282930. PICK1 also associates with the active form of PKCα [31] , which phosphorylates the S880 C-terminus residue of the AMPAR-GluA2 subunit [32, 33] sustained by positive feedback mechanisms for at least 20 minutes during LTD induction [34, 35]. "
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    ABSTRACT: The expression of long-term depression (LTD) in cerebellar Purkinje cells results from the internalisation of α-amino-3-hydroxy-5-methylisoxazole-4-propionic acid receptors (AMPARs) from the postsynaptic membrane. This process is regulated by a complex signalling pathway involving sustained protein kinase C (PKC) activation, inhibition of serine/threonine phosphatase, and an active protein tyrosine phosphatase, PTPMEG. In addition, two AMPAR-interacting proteins-glutamate receptor-interacting protein (GRIP) and protein interacting with C kinase 1 (PICK1)-regulate the availability of AMPARs for trafficking between the postsynaptic membrane and the endosome. Here we present a new computational model of these overlapping signalling pathways. The model reveals how PTPMEG cooperates with PKC to drive LTD expression by facilitating the effect of PKC on the dissociation of AMPARs from GRIP and thus their availability for trafficking. Model simulations show that LTD expression is increased by serine/threonine phosphatase inhibition, and negatively regulated by Src-family tyrosine kinase activity, which restricts the dissociation of AMPARs from GRIP under basal conditions. We use the model to expose the dynamic balance between AMPAR internalisation and reinsertion, and the phosphorylation switch responsible for the perturbation of this balance and for the rapid plasticity initiation and regulation. Our model advances the understanding of PF-PC LTD regulation and induction, and provides a validated extensible platform for more detailed studies of this fundamental synaptic process.
    Full-text · Article · Jan 2016 · PLoS Computational Biology
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    • "PACSIN1/Syndapin I phosphorylation has also been reported to weaken membrane association, resulting in a significant change in neuronal morphology (Quan et al., 2012). Furthermore, phosphorylation in the linker regions of mammalian PACSIN1 and 2 was shown to regulate the interactions with PICK1, a BAR-domain containing adaptor protein (Anggono et al., 2013). However, the effect of this phosphorylation on membrane binding was not examined, and the kinases responsible for phosphorylation were not investigated. "
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    ABSTRACT: PACSIN2, a membrane-sculpting BAR domain protein, localizes to caveolae. Here, we found that PKC phosphorylates PACSIN2 at serine 313, thereby decreasing its membrane binding and tubulation capacities. Concomitantly, phosphorylation decreased the time span for which caveolae could be tracked at the plasma membrane (the 'tracking-duration'). Analyses of the phospho-mimetic S313E mutant suggested that PACSIN2 phosphorylation is sufficient to reduce caveolar tracking-durations. Both hypotonic treatment and isotonic drug-induced PKC activation increased PACSIN2 phosphorylation at serine 313 and shortened caveolar tracking-durations. Caveolar tracking-durations were also reduced upon the expression of other membrane-binding deficient PACSIN2 mutants or RNAi-mediated PACSIN2 depletion, pointing to a role of PACSIN2 levels for the lifetime of caveolae. Interestingly, the decrease in membrane-bound PACSIN2 was inversely correlated with the recruitment and activity of dynamin 2, a GTPase mediating membrane scission. Furthermore, expression of EHD2, which stabilizes caveolae and binds to PACSIN2, restored the tracking-durations of cells with reduced PACSIN2 levels. These findings suggest that the PACSIN2 phosphorylation decreases its membrane-binding activity, thereby decreasing its stabilizing effect on caveolae and triggering dynamin-mediated removal of caveolae. © 2015. Published by The Company of Biologists Ltd.
    Full-text · Article · Jun 2015 · Journal of Cell Science
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    • "Pick1 has been reported to bind to F-actin and the Arp2/3 complex, and thereby inhibit Arp2/3-mediated actin polymerization [12]. Pick1 has also been shown to regulate trafficking and function of some membrane proteins, such as AMPA receptor and ephrinB1 [9] [13]. Pick1 binds to PKC, which has been reported to participate in TJ disassembly , whereas PKC and aPKC are involved in TJ formation in epithelial cells [14]. "
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    ABSTRACT: Members of the Eph family have been implicated in the formation of cell-cell boundaries, cell movement, and positioning during development in the context of cancer progression. De-regulation of this signaling system is linked to the promotion of more aggressive and metastatic tumor phenotypes in a large variety of human cancers, including breast, lung, and prostate cancer, melanoma, and leukemia. Thus, it is interesting to consider the case of cancer progression where de-regulation of the Eph/ephrin signaling system results in invasion and metastasis. Here, we present evidence that Pick1, one of the essential components of the adherens junction, recovers ephrinB1-induced cell-cell de-adhesion. Loss of Pick1 leads to dissociation of epithelial cells via disruption of the adherens junction, a phenotype similar to ephrinB1 overexpression. In addition, overexpressed ephrinB1-induced disruption of the adherens junction is rescued via binding to Pick1. These data indicate that Pick1 is involved in regulating the cell-cell junction in epithelial cells, and this may influence therapeutic strategy decisions with regards to cell adhesion molecules in metastatic disease.
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