The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform

Katherine W Roche - One of the best experts on this subject based on the ideXlab platform.

  • Casein Kinase 2 phosphorylates glua1 and regulates its surface expression
    European Journal of Neuroscience, 2014
    Co-Authors: Marc P Lussier, Katherine W Roche
    Abstract:

    Controlling the density of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (AMPARs) at synapses is essential for regulating the strength of excitatory neurotransmission. In particular, the phosphorylation of AMPARs is important for defining both synaptic expression and intracellular routing of receptors. Phosphorylation is a post-translational modification known to regulate many cellular events and the C-termini of glutamate receptors are important targets. Recently, the first intracellular loop1 region of the GluA1 subunit of AMPARs was reported to regulate synaptic targeting through phosphorylation of S567 by Ca2+ /calmodulin-dependent protein Kinase II (CaMKII). Intriguingly, the loop1 region of all four AMPAR subunits contains many putative phosphorylation sites (S/T/Y), leaving the possibility that other Kinases may regulate AMPAR surface expression via phosphorylation of the loop regions. To explore this hypothesis, we used in vitro phosphorylation assays with a small panel of purified Kinases and found that Casein Kinase 2 (CK2) phosphorylates the GluA1 and GluA2 loop1 regions, but not GluA3 or GluA4. Interestingly, when we reduced the endogenous expression of CK2 using a specific short hairpin RNA against the regulatory subunit CK2β, we detected a reduction of GluA1 surface expression, whereas GluA2 was unchanged. Furthermore, we identified S579 of GluA1 as a substrate of CK2, and the expression of GluA1 phosphodeficient mutants in hippocampal neurons displayed reduced surface expression. Therefore, our study identifies CK2 as a regulator of GluA1 surface expression by phosphorylating the intracellular loop1 region.

  • activated camkii couples glun2b and Casein Kinase 2 to control synaptic nmda receptors
    Cell Reports, 2013
    Co-Authors: Antonio Sanzclemente, John A Gray, Kyle A Ogilvie, Roger A Nicoll, Katherine W Roche
    Abstract:

    Synaptic activity triggers a profound reorganization of the molecular composition of excitatory synapses. For example, NMDA receptors are removed from synapses in an activity- and calcium-dependent manner, via Casein Kinase 2 (CK2) phosphorylation of the PDZ ligand of the GluN2B subunit (S1480). However, how synaptic activity drives this process remains unclear because CK2 is a constitutively active Kinase, which is not directly regulated by calcium. We show here that activated CaMKII couples GluN2B and CK2 to form a trimolecular complex and increases CK2-mediated phosphorylation of GluN2B S1480. In addition, a GluN2B mutant, which contains an insert to mimic the GluN2A sequence and cannot bind to CaMKII, displays reduced S1480 phosphorylation and increased surface expression. We find that although disrupting GluN2B/CaMKII binding reduces synapse number, it increases synaptic-GluN2B content. Therefore, the GluN2B/CaMKII association controls synapse density and PSD composition in an activity-dependent manner, including recruitment of CK2 for the removal of GluN2B from synapses.

  • Casein Kinase 2 regulates the nr2 subunit composition of synaptic nmda receptors
    Neuron, 2010
    Co-Authors: Antonio Sanzclemente, Jose A Matta, Joh T R Isaac, Katherine W Roche
    Abstract:

    N-methyl-D-aspartate (NMDA) receptors (NMDARs) play a central role in development, synaptic plasticity, and neurological disease. NMDAR subunit composition defines their biophysical properties and downstream signaling. Casein Kinase 2 (CK2) phosphorylates the NR2B subunit within its PDZ-binding domain; however, the consequences for NMDAR localization and function are unclear. Here we show that CK2 phosphorylation of NR2B regulates synaptic NR2B and NR2A in response to activity. We find that CK2 phosphorylates NR2B, but not NR2A, to drive NR2B-endocytosis and remove NR2B from synapses resulting in an increase in synaptic NR2A expression. During development there is an activity-dependent switch from NR2B to NR2A at cortical synapses. We observe an increase in CK2 expression and NR2B phosphorylation over this same critical period and show that the acute activity-dependent switch in NR2 subunit composition at developing hippocampal synapses requires CK2 activity. Thus, CK2 plays a central role in determining the NR2 subunit content of synaptic NMDARs.

Jing Xu - One of the best experts on this subject based on the ideXlab platform.

  • Casein Kinase 2 reverses tail independent inactivation of kinesin 1
    Nature Communications, 2012
    Co-Authors: Jing Xu, Babu J N Reddy, Preetha Anand, Silvia Cermelli, Michelle K Mattson, Suvranta K Tripathy, Matthew T Hoss, Nikita S James, Stephen J King
    Abstract:

    Kinesin-1 is a motor protein that transports cargo along microtubules and defects in this process can result in neurodegeneration. In this study, a role for Casein Kinase 2 in regulating the activity of Kinesin-1 is reported, suggesting that signalling molecules can modulate this transport process.

  • Casein Kinase 2 reverses tail independent inactivation of kinesin 1
    Biophysical Journal, 2011
    Co-Authors: Jing Xu, Babu J N Reddy, Preetha Anand, Silvia Cermelli, Michelle K Mattson, Suvranta K Tripathy, Matthew T Hoss, Nikita S James, Stephen J King, Lan Huang
    Abstract:

    Kinesin-1 is a plus-end microtubule-based motor, and defects in kinesin-based transport are linked to diseases including neurodegeneration. Kinesin can auto-inhibit via a head- tail interaction, but is believed to be active otherwise. Here we report a tail-independent inactivation of kinesin, reversible by the disease-relevant signalling protein, Casein Kinase 2 (CK2). The majority of initially active kinesin (native or tail-less) loses its ability to interact with microtubules in vitro, and CK2 reverses this inactivation (approximately fourfold) without altering kinesin's single motor properties. This activation pathway does not require motor phosphorylation, and is independent of head-tail auto-inhibition. In cultured mammalian cells, reducing CK2 expression, but not its Kinase activity, decreases the force required to stall lipid droplet transport, consistent with a decreased number of active kinesin motors. our results provide the first direct evidence of a protein Kinase upregulating kinesin-based transport, and suggest a novel pathway for regulating the activity of cargo-bound kinesin.

Richard E Lloyd - One of the best experts on this subject based on the ideXlab platform.

  • Casein Kinase 2 is linked to stress granule dynamics through phosphorylation of the stress granule nucleating protein g3bp1
    Molecular and Cellular Biology, 2017
    Co-Authors: Lucas C Reineke, Weichih Tsai, Antrix Jain, Jason T Kaelber, Sung Yun Jung, Richard E Lloyd
    Abstract:

    Stress granules (SGs) are large macromolecular aggregates that contain translation initiation complexes and mRNAs. Stress granule formation coincides with translational repression, and stress granules actively signal to mediate cell fate decisions by signaling to the translation apparatus to (i) maintain translational repression, (ii) mount various transcriptional responses, including innate immunity, and (iii) repress apoptosis. Previous work showed that G3BP1 is phosphorylated at serine 149, which regulates G3BP1 oligomerization, stress granule assembly, and RNase activity intrinsic to G3BP1. However, the Kinase that phosphorylates G3BP1 was not identified, leaving a key step in stress granule regulation uncharacterized. Here, using chemical inhibition, genetic depletion, and overexpression experiments, we show that Casein Kinase 2 (CK2) promotes stress granule dynamics. These results link CK2 activity with SG disassembly. We also show that Casein Kinase 2 phosphorylates G3BP1 at serine 149 in vitro and in cells. These data support a role for Casein Kinase 2 in regulation of protein synthesis by downregulating stress granule formation through G3BP1.

Antonio Sanzclemente - One of the best experts on this subject based on the ideXlab platform.

  • activated camkii couples glun2b and Casein Kinase 2 to control synaptic nmda receptors
    Cell Reports, 2013
    Co-Authors: Antonio Sanzclemente, John A Gray, Kyle A Ogilvie, Roger A Nicoll, Katherine W Roche
    Abstract:

    Synaptic activity triggers a profound reorganization of the molecular composition of excitatory synapses. For example, NMDA receptors are removed from synapses in an activity- and calcium-dependent manner, via Casein Kinase 2 (CK2) phosphorylation of the PDZ ligand of the GluN2B subunit (S1480). However, how synaptic activity drives this process remains unclear because CK2 is a constitutively active Kinase, which is not directly regulated by calcium. We show here that activated CaMKII couples GluN2B and CK2 to form a trimolecular complex and increases CK2-mediated phosphorylation of GluN2B S1480. In addition, a GluN2B mutant, which contains an insert to mimic the GluN2A sequence and cannot bind to CaMKII, displays reduced S1480 phosphorylation and increased surface expression. We find that although disrupting GluN2B/CaMKII binding reduces synapse number, it increases synaptic-GluN2B content. Therefore, the GluN2B/CaMKII association controls synapse density and PSD composition in an activity-dependent manner, including recruitment of CK2 for the removal of GluN2B from synapses.

  • Casein Kinase 2 regulates the nr2 subunit composition of synaptic nmda receptors
    Neuron, 2010
    Co-Authors: Antonio Sanzclemente, Jose A Matta, Joh T R Isaac, Katherine W Roche
    Abstract:

    N-methyl-D-aspartate (NMDA) receptors (NMDARs) play a central role in development, synaptic plasticity, and neurological disease. NMDAR subunit composition defines their biophysical properties and downstream signaling. Casein Kinase 2 (CK2) phosphorylates the NR2B subunit within its PDZ-binding domain; however, the consequences for NMDAR localization and function are unclear. Here we show that CK2 phosphorylation of NR2B regulates synaptic NR2B and NR2A in response to activity. We find that CK2 phosphorylates NR2B, but not NR2A, to drive NR2B-endocytosis and remove NR2B from synapses resulting in an increase in synaptic NR2A expression. During development there is an activity-dependent switch from NR2B to NR2A at cortical synapses. We observe an increase in CK2 expression and NR2B phosphorylation over this same critical period and show that the acute activity-dependent switch in NR2 subunit composition at developing hippocampal synapses requires CK2 activity. Thus, CK2 plays a central role in determining the NR2 subunit content of synaptic NMDARs.

Lorenzo A Pinna - One of the best experts on this subject based on the ideXlab platform.

  • Casein Kinase 2 (CK2) phosphorylates the deubiquitylase OTUB1 at Ser16 to trigger its nuclear localization.
    Science signaling, 2015
    Co-Authors: Lina Herhaus, Lorenzo A Pinna, Ana B. Perez-oliva, Giorgio Cozza, Robert Gourlay, Simone Weidlich, David G. Campbell, Gopal P. Sapkota
    Abstract:

    The deubiquitylating enzyme OTUB1 is present in all tissues and targets many substrates, in both the cytosol and nucleus. We found that Casein Kinase 2 (CK2) phosphorylated OTUB1 at Ser 16 to promote its nuclear accumulation in cells. Pharmacological inhibition or genetic ablation of CK2 blocked the phosphorylation of OTUB1 at Ser 16 , causing its nuclear exclusion in various cell types. Whereas we detected unphosphorylated OTUB1 mainly in the cytosol, we detected Ser 16 -phosphorylated OTUB1 only in the nucleus. In vitro, Ser 16 -phosphorylated OTUB1 and nonphosphorylated OTUB1 exhibited similar catalytic activity, bound K63-linked ubiquitin chains, and interacted with the E2 enzyme UBE2N. CK2-mediated phosphorylation and subsequent nuclear localization of OTUB1 promoted the formation of 53BP1 (p53-binding protein 1) DNA repair foci in the nucleus of osteosarcoma cells exposed to ionizing radiation. Our findings indicate that the activity of CK2 is necessary for the nuclear translocation and subsequent function of OTUB1 in DNA damage repair.

  • toward the rational design of protein Kinase Casein Kinase 2 inhibitors
    Pharmacology & Therapeutics, 2002
    Co-Authors: Stefania Sarno, Flavio Meggio, Stefano Moro, Giuseppe Zagotto, Diego Dal Ben, Paola Ghisellini, Roberto Battistutta, Giuseppe Zanotti, Lorenzo A Pinna
    Abstract:

    Casein Kinase-2 (CK2) probably is the most pleiotropic member of the protein Kinase family, with more than 200 substrates known to date. Unlike the great majority of protein Kinases, which are tightly regulated enzymes, CK2 is endowed with high constitutive activity, a feature that is suspected to underlie its oncogenic potential and possible implication in viral infections. This makes CK2 an attractive target for anti-neoplastic and antiviral drugs. Here, we present an overview of our present knowledge about CK2 inhibitors, with special reference to the information drawn from two recently solved crystal structures of CK2alpha in complex with emodin and with 4,5,6,7-tetrabromo-2-azabenzimidazole (TBB), this latter being the most specific CK2 inhibitor known to date. A comparison with a series of anthraquinone and xanthenone derivatives highlights the crucial relevance of the hydroxyl group at position 3 for inhibition by emodin, and discloses the possibility of increasing the inhibitory potency by placing an electron withdrawing group at position 5. We also present mutational data corroborating the relevance of two hydrophobic residues unique to CK2, Val66 and Ile174, for the interactions with emodin and TBB, but not with the flavonoid inhibitors quercetin and fisetin. In particular, the CK2alpha mutant V66A displays 27- and 11-fold higher IC(50) values with emodin and TBB, respectively, as compared with the wild-type, while the IC(50) value with quercetin is unchanged. The data presented pave the road toward the rational design of more potent and selective inhibitors of CK2 and the generation of CK2 mutants refractory to inhibition, useful to probe the implication of CK2 in specific cellular functions.

  • selectivity of 4 5 6 7 tetrabromobenzotriazole an atp site directed inhibitor of protein Kinase ck2 Casein Kinase 2
    FEBS Letters, 2001
    Co-Authors: Stefania Sarno, Flavio Meggio, Helen Reddy, Maria Ruzzene, Stephen P Davies, Arianna Donelladeana, David Shugar, Lorenzo A Pinna
    Abstract:

    The specificity of 4,5,6,7-tetrabromo-2-azabenzimidazole (TBB), an ATP/GTP competitive inhibitor of protein Kinase Casein Kinase-2 (CK2), has been examined against a panel of 33 protein Kinases, either Ser/Thr- or Tyr-specific. In the presence of 10 μM TBB (and 100 μM ATP) only CK2 was drastically inhibited (>85%) whereas three Kinases (phosphorylase Kinase, glycogen synthase Kinase 3β and cyclin-dependent Kinase 2/cyclin A) underwent moderate inhibition, with IC50 values one–two orders of magnitude higher than CK2 (IC50=0.9 μM). TBB also inhibits endogenous CK2 in cultured Jurkat cells. A CK2 mutant in which Val66 has been replaced by alanine is much less susceptible to inhibition by TBB as well as by another ATP competitive inhibitor, emodin. These data show that TBB is a quite selective inhibitor of CK2, that can be used in cell-based assays.

  • protein Kinase ck2 Casein Kinase 2 and its implication in cell division and proliferation
    Progress in cell cycle research, 1997
    Co-Authors: Lorenzo A Pinna, Flavio Meggio
    Abstract:

    Protein Kinase CK2 (also termed Casein Kinase-2 or -II) is a ubiquitous Ser/Thr-specific protein Kinase required for viability and for cell cycle progression. CK2 is especially elevated in proliferating tissues, either normal or transformed, and the expression of its catalytic subunit in transgenic mice is causative of lymphomas. CK2 is highly pleiotropic: more than 160 proteins phosphorylated by it at sites specified by multiple acidic residues are known. Despite its heterotetrameric structure generally composed by two catalytic (α and/or α’) and two non catalytic β-subunits, the regulation of CK2 is still enigmatic. A number of functional features of the β-subunit which could cooperate to the modulation of CK2 targeting/activity will be discussed.

  • the ste locus a component of the parasitic cry ste system of drosophila melanogaster encodes a protein that forms crystals in primary spermatocytes and mimics properties of the beta subunit of Casein Kinase 2
    Proceedings of the National Academy of Sciences of the United States of America, 1995
    Co-Authors: Maria Pia Bozzetti, Lorenzo A Pinna, Flavio Meggio, S Massari, Palma Finelli, B Boldyreff, O G Issinger, G Palumbo, C Ciriaco, S Bonaccorsi
    Abstract:

    Males of Drosophila melanogaster lacking the Y chromosome-linked crystal locus show multiple meiotic alterations including chromosome disorganization and prominent crystal formation in primary spermatocytes. These alterations are due to the derepression of the X chromosome-linked Stellate sequences. To understand how the derepression of the Stellate elements gives rise to these abnormalities, we have expressed the protein encoded by the Stellate sequences in bacteria and produced an antibody against the fusion protein. Immunostaining of crystal- testes has clearly shown that the Stellate protein is a major component of the crystals. Moreover, in vitro experiments have shown that this protein can interact with the catalytic alpha subunit of Casein Kinase 2 enzyme, altering its activity.