Identification of a small-molecule inhibitor of the PICK1 PDZ domain that inhibits hippocampal LTP and LTD

Abstract

Proteins containing PSD-95/Discs-large/ZO-1 homology (PDZ) domains play key roles in the assembly and regulation of cellular signaling pathways and represent putative targets for new pharmacotherapeutics. Here we describe the first small-molecule inhibitor (FSC231) of the PDZ domain in protein interacting with C kinase 1 (PICK1) identified by a screening of~44,000 compounds in a fluorescent polarization assay. The inhibitor bound the PICK1 PDZ domain with an affinity similar to that observed for endogenous peptide ligands (K i~1 0.1 μM). Mutational analysis, together with computational docking of the compound in simulations starting from the PDZ domain structure, identified the binding mode of FSC231. The specificity of FSC231 for the PICK1 PDZ domain was supported by the lack of binding to PDZ domains of postsynaptic density protein 95 (PSD-95) and glutamate receptor interacting protein 1 (GRIP1). Pretreatment of cultured hippocampal neurons with FSC231 inhibited coimmunopreciptation of the AMPA receptor GluR2 subunit with PICK1. In agreement with inhibiting the role of PICK1 in GluR2 trafficking, FSC231 accelerated recycling of pHluorin-tagged GluR2 in hippocampal neurons after internalization in response to NMDA receptor activation. FSC231 blocked the expression of both long-term depression and long-term potentiation in hippocampal CA1 neurons from acute slices, consistent with inhibition of the bidirectional function of PICK1 in synaptic plasticity. Given the proposed role of the PICK1/AMPA receptor interaction in neuropathic pain, excitotoxicity, and cocaine addiction, FSC231 might serve as a lead in the future development of new therapeutics against these conditions. drug discovery | fluorescence polarization | protein-protein interactions | synaptic plasticity | AMPA receptors

Protein Interacting with C Kinase 1 (PICK1) Reduces Reinsertion Rates of Interaction Partners Sorted to Rab11-dependent Slow Recycling Pathway

“…In contrast, recycling of pHluorinGluR2 was accelerated in neurons from knock-out mice in agreement with a role of PICK1 in diminishing recycling (38). More recently, this was further supported by our observation that a small molecule inhibitor of the PICK1 PDZ domain accelerated recycling of pHluorinGluR2 in the same setup (67). In this study, we generalize these observations by showing that the effect on recycling also can be observed for an unrelated integral membrane protein (␤ 2 AR) in a heterologous cell line if an appropriate PDZ binding sequence is transferred to the C terminus of the protein and if the protein is sorted to a Rab11-positive recycling pathway.…”

“…In relation to the AMPAR, it is tempting to speculate that the clusters not only contain the AMPAR accumulated intracellularly during LTD but also could be considered an equivalent of the functional reservoirs of AMPARs that are recruited to the plasma membrane during long term potentiation. Thus, in the absence of PICK1, an intracellular recruitable pool of AMPAR will never develop in concurrence with the recent finding that long term potentiation is compromised in PICK1 knock-out mice and can be reduced by a specific blocker of the PICK1 PDZ domain (28,29,67).…”

PICK1 promotes caveolin-dependent degradation of TGF-β type I receptor

“…Although the Smad2 level was lower in Pick1 +/+ MEFs, stronger phosphorylation was observed in Pick1 -/-MEFs upon TGF-β treatment ( Figure 1G), while overexpression of PICK1 decreased TGF-β-induced Smad2 phosphorylation in NMuMG cells ( Figure 1H). FSC231 is a small-molecule inhibitor of PICK1, which abolishes the interaction of PICK1 PDZ domain with other proteins [30]. As shown in Figure 1I, FSC231 enhanced TGF-β-induced Smad2 phosphorylation.…”

Susceptibility to chronic pain following nerve injury is genetically affected by CACNG2

“…We also carried out a PubMed search on the 155 genes using ''AEgene nameae and pain'' as keywords. Only nine genes showed potential relevance to pain based on current knowledge: Mb (Brown et al 2007), Cacng2 (Tao et al 2006), Il2rb (Yao et al 2002), Lgals1 (McGraw et al 2005, Galr3 (Mitsukawa et al 2008), Hsf1 (Saban et al 2007), Pick1 (Thorsen et al 2010), Pla2g6 (Ma et al 2010), and Kcnj4 (Dai et al 2008).…”