Protein Kinase D1–Mediated Phosphorylation and Subcellular Localization of β-Catenin
ABSTRACT beta-Catenin is essential for E-cadherin-mediated cell adhesion in epithelial cells and also acts as a key cofactor for transcription activity. We previously showed that protein kinase D1 (PKD1), founding member of the PKD family of signal transduction proteins, is down-regulated in advanced prostate cancer and interacts with E-cadherin. This study provides evidence that PKD1 interacts with and phosphorylates beta-catenin at Thr(112) and Thr(120) residues in vitro and in vivo; mutation of Thr(112) and Thr(120) results in increased nuclear localization of beta-catenin and is associated with altered beta-catenin-mediated transcription activity. It is known that mutation of Thr(120) residue abolishes binding of beta-catenin to alpha-catenin, which links to cytoskeleton, suggesting that PKD1 phosphorylation of Thr(120) could be critical for cell-cell adhesion. Overexpression of PKD1 represses beta-catenin-mediated transcriptional activity and cell proliferation. Epistatic studies suggest that PKD1 and E-cadherin are within the same signaling pathway. Understanding the molecular basis of PKD1-beta-catenin interaction provides a novel strategy to target beta-catenin function in cells including prostate cancer.
- SourceAvailable from: Susan F Steinberg
[Show abstract] [Hide abstract]
- "These docking interactions may serve two functions. First, by tethering or orienting protein substrates on the enzyme, they may facilitate phosphorylation of sites that do not conform to optimal consensus phosphorylation motifs (perhaps explaining the known effects of PKD1 to phosphorylate sites in c-Jun, ␤-catenin, c-TnI, and type II␣ phosphatidylinositol 4-phosphate kinase that do not conform to LxRxxpS/T motifs) (Hinchliffe and Irvine, 2006; Qin et al., 2006; Waldron et al., 2007; Du et al., 2009). Second, a docking interaction with a protein substrate or scaffold may influence inhibitor sensitivity ; there is recent evidence that PKC is rendered insensitive to inhibitors that compete with ATP when anchored to AKAP79 (Hoshi et al., 2010). "
ABSTRACT: Protein kinase D1 (PKD1) is a stress-activated serine/threonine kinase that plays a vital role in various physiologically important biological processes, including cell growth, apoptosis, adhesion, motility, and angiogenesis. Dysregulated PKD1 expression also contributes to the pathogenesis of certain cancers and cardiovascular disorders. Studies to date have focused primarily on the canonical membrane-delimited pathway for PKD1 activation by G protein-coupled receptors or peptide growth factors. Here, agonist-dependent increases in diacylglycerol accumulation lead to the activation of protein kinase C (PKC) and PKC-dependent phosphorylation of PKD1 at two highly conserved serine residues in the activation loop; this modification increases PKD1 catalytic activity, as assessed by PKD1 autophosphorylation at a consensus phosphorylation motif at the extreme C terminus. However, recent studies expose additional controls and consequences for PKD1 activation loop and C-terminal phosphorylation as well as additional autophosphorylation reactions and trans-phosphorylations (by PKC and other cellular enzymes) that contribute to the spatiotemporal control of PKD1 signaling in cells. This review focuses on the multisite phosphorylations that are known or predicted to influence PKD1 catalytic activity and may also influence docking interactions with cellular scaffolds and trafficking to signaling microdomains in various subcellular compartments. These modifications represent novel targets for the development of PKD1-directed pharmaceuticals for the treatment of cancers and cardiovascular disorders.Molecular pharmacology 12/2011; 81(3):284-91. DOI:10.1124/mol.111.075986 · 4.12 Impact Factor
[Show abstract] [Hide abstract]
- "Hsp27 mediates repression of AR by PKD1 in PC cells S Hassan et al mutagenesis of T120 and/or T112 decreases b-catenin transcriptional activity (Du et al., 2009). Although the effect of T120 or T112 nonphosphorylation mutant on AR activity is not known, PKD1 may influence AR activity through multiple mechanisms, including Hsp27 and b-catenin-mediated pathways. "
ABSTRACT: We have previously shown that protein kinase D1 (PKD1), charter member of PKD protein family, is downregulated in advanced prostate cancer (PC) and influences androgen receptor (AR) function in PC cells. Other independent studies showed that serine 82 residue in heat shock protein 27 (Hsp27) undergoes substrate phosphorylation by PKD1 and is associated with nuclear transport of AR resulting in increased AR transcriptional activity. In this study, we show that PKD1 interacts and phosphorylates Hsp27 at Ser82 in PC cells, which is mediated by p38-dependent mitogen-activated protein kinase pathway and is necessary for PKD1 repression of AR transcriptional activity and androgen-dependent proliferation of PC cells. The study provides first in vivo evidence that Hsp27 is a mediator of repression of AR function by PKD1 in PC cells, thereby linking the data in the published literature.Oncogene 09/2009; 28(49):4386-96. DOI:10.1038/onc.2009.291 · 8.56 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: Protein kinase D (PKD) transduces an abundance of signals downstream of diacylglycerol production. The mammalian PKD family consists of three isoforms, PKD1, PKD2, and PKD3; of these PKD1 and PKD2 contain PDZ-binding motifs at their carboxyl termini. Here we show that membrane-localized NHERF scaffold proteins provide a nexus for tightly controlled PKD signaling via a PDZ domain interaction. Using a proteomic array containing 96 purified PDZ domains, we have identified the first PDZ domain of NHERF-1 as an interaction partner for the PDZ-binding motifs of both PKD1 and PKD2. A fluorescence resonance energy transfer-based translocation assay reveals a transient association of PKD1 and PKD2 with NHERF-1 in live cells that is triggered by phorbol ester stimulation and, importantly, differs strikingly from the sustained translocation to plasma membrane. Targeting a fluorescence resonance energy transfer-based kinase activity reporter for PKD to NHERF scaffolds reveals a unique signature of PKD activation at the scaffold that is distinct from that of general cytosolic or plasma membrane activity. Specifically, agonist-evoked activation of PKD at the scaffold is rapid and sustained but blunted in magnitude when compared with cytosolic PKD. Thus, live cell imaging of PKD activity demonstrates ultrasensitive control of kinase signaling at the scaffold compared with bulk activity in the cytosol or at the plasma membrane.Journal of Biological Chemistry 08/2009; 284(36):24653-61. DOI:10.1074/jbc.M109.024547 · 4.57 Impact Factor