pVHL Acts as an Adaptor to Promote the Inhibitory Phosphorylation of the NF-κB Agonist Card9 by CK2

Harvard University, Cambridge, Massachusetts, United States
Molecular Cell (Impact Factor: 14.02). 11/2007; 28(1):15-27. DOI: 10.1016/j.molcel.2007.09.010
Source: PubMed


The VHL tumor suppressor protein (pVHL) is part of an E3 ubiquitin ligase that targets HIF for destruction. pVHL-defective renal carcinoma cells exhibit increased NF-kappaB activity but the mechanism is unclear. NF-kappaB affects tumorigenesis and therapeutic resistance in some settings. We found that pVHL associates with the NF-kappaB agonist Card9 but does not target Card9 for destruction. Instead, pVHL serves as an adaptor that promotes the phosphorylation of the Card9 C terminus by CK2. Elimination of these sites markedly enhanced Card9's ability to activate NF-kappaB in VHL(+/+) cells, and Card9 siRNA normalized NF-kappaB activity in VHL(-/-) cells and restored their sensitivity to cytokine-induced apoptosis. Furthermore, downregulation of Card9 in VHL(-/-) cancer cells reduced their tumorigenic potential. Therefore pVHL can serve as an adaptor for both a ubiquitin conjugating enzyme and a kinase. The latter activity, which promotes Card9 phosphorylation, links pVHL to control of NF-kappaB activity and tumorigenesis.

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Available from: Susanne Schlisio, Jan 23, 2014
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    • "Loss of pVHL has been shown to result in increased NF-κB activity, indicating that activation of NF-κB may represent a common downstream consequence of VHL-deficiency [15–17,33]. The Kaelin and Rettig laboratories have provided mechanistic insight into how pVHL deficiency results in increased NF-κB activity by elucidating two distinct pathways of pVHL-dependent NF-κB regulation. "
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    ABSTRACT: To determine the expression patterns of NF-κB regulators and target genes in clear cell renal cell carcinoma (ccRCC), their correlation with von Hippel Lindau (VHL) mutational status, and their association with survival outcomes. Meta-analyses were carried out on published ccRCC gene expression datasets by RankProd, a non-parametric statistical method. DEGs with a False Discovery Rate of < 0.05 by this method were considered significant, and intersected with a curated list of NF-κB regulators and targets to determine the nature and extent of NF-κB deregulation in ccRCC. A highly-disproportionate fraction (~40%; p < 0.001) of NF-κB regulators and target genes were found to be up-regulated in ccRCC, indicative of elevated NF-κB activity in this cancer. A subset of these genes, comprising a key NF-κB regulator (IKBKB) and established mediators of the NF-κB cell-survival and pro-inflammatory responses (MMP9, PSMB9, and SOD2), correlated with higher relative risk, poorer prognosis, and reduced overall patient survival. Surprisingly, levels of several interferon regulatory factors (IRFs) and interferon target genes were also elevated in ccRCC, indicating that an 'interferon signature' may represent a novel feature of this disease. Loss of VHL gene expression correlated strongly with the appearance of NF-κB- and interferon gene signatures in both familial and sporadic cases of ccRCC. As NF-κB controls expression of key interferon signaling nodes, our results suggest a causal link between VHL loss, elevated NF-κB activity, and the appearance of an interferon signature during ccRCC tumorigenesis. These findings identify NF-κB and interferon signatures as clinical features of ccRCC, provide strong rationale for the incorporation of NF-κB inhibitors and/or and the exploitation of interferon signaling in the treatment of ccRCC, and supply new NF-κB targets for potential therapeutic intervention in this currently-incurable malignancy.
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    • "Activation of hypoxia-inducible genes leads to a metabolic shift to anerobic glycolysis, increased secretion of pro-angiogenic factors, remodeling of the extracellular matrix, resistance to apoptosis and increased mobility [27]. Additionally , pVHL has functions that are HIF-independent that include: maintenance of the primary cilium, assembly of the extracellular matrix, control of microtubule dynamics, regulation of neuronal apoptosis, transcriptional regulation, NF-jB activity inhibition and possibly stabilization of p53 [28] [29] [30] [31]. ccRCCs are highly vascularized tumors due to the upregulation of vascular endothelial growth factor A (VEGFA or VEGF) and plateletderived growth factor B (PDGFB). "
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    ABSTRACT: Majority of clear cell renal cell carcinomas (ccRCCs) are diagnosed in the advanced metastatic stage resulting in dramatic decrease of patient survival. Thereby, early detection and monitoring of the disease may improve prognosis and treatment results. Recent technological advances enable the identification of genetic events associated with ccRCC and reveal significant molecular heterogeneity of ccRCC tumors. This review summarizes recent findings in ccRCC genomics and epigenomics derived from chromosomal aberrations, DNA sequencing and methylation, mRNA, miRNA expression profiling experiments. We provide a molecular insight into ccRCC pathology and recapitulate possible clinical applications of genomic alterations as predictive and prognostic biomarkers.
    Full-text · Article · Aug 2013 · Cancer letters
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    • "pVHL binds to hydroxylated α-chain of collagen IV [13] and reacts with fibronectin [14]. pVHL is also involved in regulation of NF-κB [15] and Wnt signaling [16]. "
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    ABSTRACT: pVHL, product of von Hippel-Lindau (VHL) tumor suppressor gene, functions as the substrate recognition component of an E3-ubiquitin ligase that targets proteins for ubiquitination and proteasomal degradation. Hypoxia-inducible factor α (HIFα) is the well-known substrate of pVHL. Besides HIFα, pVHL also binds to many other proteins and has multiple functions. In this manuscript, we report that the nuclear clusterin (nCLU) is a target of pVHL. We found that pVHL had a direct interaction with nCLU. nCLU bound to pVHL at pVHL's β domain, the site for recognition of substrate, indicating that nCLU might be a substrate of pVHL. Interestingly, pVHL bound to nCLU but did not lead to nCLU destruction. Further studies indicated that pVHL mediated K63-linked ubiquitination of nCLU and promoted nCLU nuclear translocation. In summary, our results disclose a novel function of pVHL that mediates K63-linked ubiquitination and identify nCLU as a new target of pVHL.
    Full-text · Article · Apr 2012 · PLoS ONE
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