Casein kinase 1α governs antigen-receptor-induced NF-κB activation and human lymphoma cell survival

Molecular Development Section, Laboratory of Immunology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA.
Nature (Impact Factor: 41.46). 03/2009; 458(7234):92-6. DOI: 10.1038/nature07613
Source: PubMed


The transcription factor NF-kappaB is required for lymphocyte activation and proliferation as well as the survival of certain lymphoma types. Antigen receptor stimulation assembles an NF-kappaB activating platform containing the scaffold protein CARMA1 (also called CARD11), the adaptor BCL10 and the paracaspase MALT1 (the CBM complex), linked to the inhibitor of NF-kappaB kinase complex, but signal transduction is not fully understood. We conducted parallel screens involving a mass spectrometry analysis of CARMA1 binding partners and an RNA interference screen for growth inhibition of the CBM-dependent 'activated B-cell-like' (ABC) subtype of diffuse large B-cell lymphoma (DLBCL). Here we report that both screens identified casein kinase 1alpha (CK1alpha) as a bifunctional regulator of NF-kappaB. CK1alpha dynamically associates with the CBM complex on T-cell-receptor (TCR) engagement to participate in cytokine production and lymphocyte proliferation. However, CK1alpha kinase activity has a contrasting role by subsequently promoting the phosphorylation and inactivation of CARMA1. CK1alpha has thus a dual 'gating' function which first promotes and then terminates receptor-induced NF-kappaB. ABC DLBCL cells required CK1alpha for constitutive NF-kappaB activity, indicating that CK1alpha functions as a conditionally essential malignancy gene-a member of a new class of potential cancer therapeutic targets.

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Available from: Zhaojing Meng, Oct 31, 2014
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    • "Because inhibition of kinase activity is the most straightforward way to target Csnk1a1 pharmacologically, we tested whether the kinase function of Csnk1a1 is essential for leukemia cells. We introduced a known mutation that inactivates the kinase domain (Csnk1a1(D136N); Peters et al., 1999; Davidson et al., 2005; Bidère et al., 2009) into the shRNAresistant Csnk1a1 cDNA. We found that the kinase-dead cDNA did not rescue the effect of the Csnk1a1 shRNAs, demonstrating that Csnk1a1 kinase function is essential for leukemia cells (Fig. 1 F). "
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    ABSTRACT: Despite extensive insights into the underlying genetics and biology of acute myeloid leukemia (AML), overall survival remains poor and new therapies are needed. We found that casein kinase 1 α (Csnk1a1), a serine-threonine kinase, is essential for AML cell survival in vivo. Normal hematopoietic stem and progenitor cells (HSPCs) were relatively less affected by shRNA-mediated knockdown of Csnk1a1. To identify downstream mediators of Csnk1a1 critical for leukemia cells, we performed an in vivo pooled shRNA screen and gene expression profiling. We found that Csnk1a1 knockdown results in decreased Rps6 phosphorylation, increased p53 activity, and myeloid differentiation. Consistent with these observations, p53-null leukemias were insensitive to Csnk1a1 knockdown. We further evaluated whether D4476, a casein kinase 1 inhibitor, would exhibit selective antileukemic effects. Treatment of leukemia stem cells (LSCs) with D4476 showed highly selective killing of LSCs over normal HSPCs. In summary, these findings demonstrate that Csnk1a1 inhibition causes reduced Rps6 phosphorylation and activation of p53, resulting in selective elimination of leukemia cells, revealing Csnk1a1 as a potential therapeutic target for the treatment of AML.
    Journal of Experimental Medicine 03/2014; 211(4). DOI:10.1084/jem.20131033 · 12.52 Impact Factor
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    • "The kinesin GAKIN negatively regulates occupancy of CARMA1 at the center of the immunological synapse, and limits the extent of signaling [47]. Casein kinase 1α (CK1α), which is reported to be a bifunctional regulator, also interacts with CARMA1 and terminates signaling by phosphorylating CARMA1 [48]. Although CKIP-1 interacts with CARMA1 as GAKIN and CK1α do, CKIP-1 shows several different aspects. "
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    ABSTRACT: The transcription factor NF-κB plays a key regulatory role in lymphocyte activation and generation of immune response. Stimulation of T cell receptor (TCR) induces phosphorylation of CARMA1 by PKCθ, resulting in formation of CARMA1-Bcl10-MALT1 (CBM) complex at lipid rafts and subsequently leading to NF-κB activation. While many molecular events leading to NF-κB activation have been reported, it is less understood how this activation is negatively regulated. We performed a cell-based screening for negative regulators of TCR-mediated NF-κB activation, using mutagenesis and complementation cloning strategies. Here we show that casein kinase-2 interacting protein-1 (CKIP-1) suppresses PKCθ-CBM-NF-κB signaling. We found that CKIP-1 interacts with CARMA1 and competes with PKCθ for association. We further confirmed that a PH domain of CKIP-1 is required for association with CARMA1 and its inhibitory effect. CKIP-1 represses NF-κB activity in unstimulated cells, and inhibits NF-κB activation induced by stimulation with PMA or constitutively active PKCθ, but not by stimulation with TNFα. Interestingly, CKIP-1 does not inhibit NF-κB activation induced by CD3/CD28 costimulation, which caused dissociation of CKIP-1 from lipid rafts. These data suggest that CKIP-1 contributes maintenance of a resting state on NF-κB activity or prevents T cells from being activated by inadequate signaling. In conclusion, we demonstrate that CKIP-1 interacts with CARMA1 and has an inhibitory effect on PKCθ-CBM-NF-κB signaling.
    PLoS ONE 01/2014; 9(1):e85762. DOI:10.1371/journal.pone.0085762 · 3.23 Impact Factor
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    • "In lymphocytes, the ligation of antigen receptors assembles the so-called CBM complex that consists of the scaffold CARMA1 and the heterodimer BCL10/MALT1 [3]. The CBM microenvironment drives oligomerized BCL10 and MALT1 to undergo K63-linked non-degradative ubiquitinylation [4-7]. This authorizes the recruitment and activation of the IκB kinase (IKK) complex that comprises two catalytic subunits (IKKα and IKKβ) and a regulatory subunit (NEMO, also called IKKγ) [8]. "
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    ABSTRACT: Background NF-κB is a master gene regulator involved in plethora of biological processes, including lymphocyte activation and proliferation. Reversible ubiquitinylation of key adaptors is required to convey the optimal activation of NF-κB. However the deubiquitinylases (DUBs), which catalyze the removal of these post-translational modifications and participate to reset the system to basal level following T-Cell receptor (TCR) engagement continue to be elucidated. Findings Here, we performed an unbiased siRNA library screen targeting the DUBs encoded by the human genome to uncover new regulators of TCR-mediated NF-κB activation. We present evidence that knockdown of Ubiquitin-Specific Protease 34 (USP34) selectively enhanced NF-κB activation driven by TCR engagement, similarly to siRNA against the well-characterized DUB cylindromatosis (CYLD). From a molecular standpoint, USP34 silencing spared upstream signaling but led to a more pronounced degradation of the NF-κB inhibitor IκBα, and culminated with an increased DNA binding activity of the transcription factor. Conclusions Collectively, our data unveils USP34 as a new player involved in the fine-tuning of NF-κB upon TCR stimulation.
    Cell Communication and Signaling 04/2013; 11(1):25. DOI:10.1186/1478-811X-11-25 · 3.38 Impact Factor
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