Casein Kinase II Phosphorylation Regulates αNAC Subcellular Localization and Transcriptional Coactivating Activity

Quélo, Isabelle; Gauthier, Claude; St‐Arnaud, René

doi:10.3727/000000005783992070

Cited by 16 publications

(15 citation statements)

References 50 publications

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“…Furthermore, in the CK2␣ screen, most of the binding partners found were CK2␤ (97.5% as determined by PCR screen), in line with previous work (20). In addition, in this screen, various proteins already known to interact with, or to be phosphorylated by, CK2, such as calmodulin (21) or ␣NAC (nascent-polypeptide associated complex alpha) (22) were also found. Taken together, these binding partners confirmed that the folding of the bait proteins in-fusion with GAL4 was comparable to that of the native protein.…”

Section: Ck2 Interacts With G␣s and G␣olfsupporting

confidence: 85%

CK2 negatively regulates Gα _s signaling

Rebholz

Nishi²,

Liebscher³

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

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We present evidence, using biochemical and cellular approaches, that the kinase, CK2, negatively controls signaling via G␣ s (or G␣olf) coupled to dopamine D1 and adenosine A2A receptors. Pharmacological inhibition of CK2 or CK2 knockdown by RNAi lead to elevated cAMP levels in dopamine D1 receptor-activated neuroblastoma cells. Phosphorylation levels of protein kinase A substrates were increased in the presence of CK2 inhibitors in mouse striatal slices. The effect of D1 receptor and A2A receptor agonists on the phosphorylation of protein kinase A sites was potentiated upon CK2 inhibition. Furthermore, in cell lines, we observed that reduction in CK2 activity, pharmacologically or genetically, reduced the amount of D1 receptor that was internalized in response to dopamine. Finally, the ␤ subunit of CK2 was found to interact specifically with the G␣ s subunit through protein interaction analyses. Thus CK2 can inhibit G protein-coupled receptor action by enabling faster receptor internalization, possibly through a direct association with G␣ s.dopamine 1 receptor ͉ GPCR ͉ striatum ͉ casein kinase 2 ͉ adenosine A2A receptor G protein coupled receptors (GPCRs) make up the largest protein family in the human genome and consist of approximately 1,000 members. These receptors mediate the biological actions of neurotransmitters, hormones, pheromones, light, and calcium through the activation of 1 or more of the 4 G protein families G␣ i/o , G␣ q/11 , G␣ s , and G␣ 12/13 . Roughly 15% of 170 well-studied non-olfactory GPCRs signal via G␣ s which activates adenylyl cyclase (1).GPCR cell surface expression and coupling to G-proteins are regulated by phosphorylation of their third intracellular loop and/or their C-terminal region by various Ser-Thr kinases, such as G protein-coupled receptor kinases (GRKs1-7) (2). Binding of arrestins to GRK-phosphorylated receptors results in uncoupling of the receptor and in desensitization of the response (2). The phosphorylated GPCR/arrestin complex is then ready for endocytosis and is targeted to clathrin-coated pits, internalized, and either dephosphorylated before recycling to the plasma membrane, or targeted to lysosomes for degradation (3). In addition to the GRKs, second messenger-dependent protein kinases, such as protein kinase A (PKA) and protein kinase C (PKC), are involved in GPCR desensitization (3). Kinases including CK1␣ have been shown to phosphorylate other GPCRs, such as the M3-muscarinic receptor (4).In the current study, we sought to examine the possible role of additional protein kinases in GPCR signaling. In particular, we wished to examine the regulation of dopamine-coupled GPCRs in neurons. Dopamine signaling is of major importance for the biology of the striatum and is altered in various neurological and psychiatric diseases such as Parkinson's disease (PD), schizophrenia, attention deficit hyperactivity disorder (ADHD), and drug abuse (5). The dopamine D1 and D5 receptors signal via G␣ olf (a G␣ s subtype of G protein) to activate adenylyl cyclase, whereas D2, D...

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Section: Ck2 Interacts With G␣s and G␣olfsupporting

confidence: 85%

CK2 negatively regulates Gα _s signaling

Rebholz

Nishi²,

Liebscher³

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

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“…1-3). Protein activity and subcellular localization are known to be regulated by phosphorylation (51)(52)(53)(54). We have repeatedly detected Htt Thr-3 phosphorylation by mass spectrometry and immunoblot analysis using a phospho-T3 specific antibody.…”

Section: Poly(q) Toxicity and Proteinmentioning

confidence: 96%

Phosphorylation of Threonine 3

Aiken

Steffan

Guerrero

et al. 2009

Journal of Biological Chemistry

156

100

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Huntingtin (Htt) is a widely expressed protein that causes tissue-specific degeneration when mutated to contain an expanded polyglutamine (poly(Q)) domain. Although Htt is large, 350 kDa, the appearance of amino-terminal fragments of Htt in extracts of postmortem brain tissue from patients with Huntington disease (HD), and the fact that an amino-terminal fragment, Htt exon 1 protein (Httex1p), is sufficient to cause disease in models of HD, points to the importance of the aminoterminal region of Htt in the disease process. The first exon of Htt encodes 17 amino acids followed by a poly(Q) repeat of variable length and culminating with a proline-rich domain of 50 amino acids. Because modifications to this fragment have the potential to directly affect pathogenesis in several ways, we have surveyed this fragment for potential post-translational modifications that might affect Htt behavior and detected several modifications of Httex1p. Here we report that the most prevalent modifications of Httex1p are NH 2 -terminal acetylation and phosphorylation of threonine 3 (pThr-3). We demonstrate that pThr-3 occurs on full-length Htt in vivo, and that this modification affects the aggregation and pathogenic properties of Htt. Thus, therapeutic strategies that modulate these events could in turn affect Htt pathogenesis.Aberrant behavior of mutant Huntingtin protein (Htt), 2 caused by an expansion of the CAG triplet repeat sequence within the first exon of the huntingtin (IT15) gene, results in neurodegeneration and leads to Huntington disease (HD) (1).Full-length Htt protein is 350 kDa in size, but a truncated form of Htt (Httex1p), which includes the expanded polyglutamine region, is sufficient to cause pathology in animal models (2-4). Moreover, an amino-terminal fragment of Htt is detected in nuclear extracts from patient brain and is not detected in control cortex samples (5). In fact, recent studies suggest that production of truncated fragments is essential for disease (6, 7).The first 17 amino acids of Htt, MATLEKLMKAFESLKSF, are highly conserved throughout mammalian evolution (8, 9), suggesting an important function for these residues. It is well established that post-translational modifications of a protein can affect activity state, intracellular localization, turnover rate, and protein-protein interactions. Several modifications of Htt, without the addition of exogenous modifiers, have been identified (10 -18) and implicated in HD (18, 19), but to date, none of these occur within the pathogenic Httex1p fragment. Given that this domain is sufficient to cause HD-like phenotypes, modifications that occur within this pathologic fragment may directly affect either its biophysical properties or its interaction with cellular components that affect pathology. Within the first 17 amino acids of Httex1p, there are several candidate amino acids for post-translational modification. Whereas genetic mutation of the lysines in this region alters HD pathology (20, 21), direct evidence for modifications of the amino-terminal fragm...

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“…31 The protein kinases that could introduce this priming phosphoserine vary depending on the substrates, and GSK-3b and casein kinase II may be the candidates for aNAC. 46 However, at present, the aNAC protein does not fulfill all the requirements as a physiological substrate for GSK-3b. 27,28 Further studies are required for determining whether aNAC is a target of GSK-3b.…”

Section: Discussionmentioning

confidence: 99%

αNAC depletion as an initiator of ER stress-induced apoptosis in hypoxia

Hotokezaka

Leyen

et al. 2009

Cell Death Differ

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Accumulation of unfolded proteins triggers endoplasmic reticulum (ER) stress and is considered a part of the cellular responses to hypoxia. The nascent polypeptide-associated complex (NAC) participates in the proper maturation of newly synthesized proteins. However, thus far, there have been no comprehensive studies on NAC involvement in hypoxic stress. Here, we show that hypoxia activates glycogen synthase kinase-3b (GSK-3b) and that the activated GSK-3b destabilizes aNAC with the subsequent apoptosis of the cell. Hypoxia of various cell types and the mouse ischemic brain was associated with rapid downregulation of aNAC and ER stress responses involving PERK, ATF4, c-taxilin, elF2a, Bip, and CHOP. Depletion of aNAC by RNA interference specifically activated ER stress responses and caused mitochondrial dysfunction, which resulted in apoptosis through caspase activation. Interestingly, we found that the hypoxic conditions activated GSK-3b, and that GSK-3b inhibition prevented aNAC protein downregulation in hypoxic cells and rescued the cells from apoptosis. In addition, aNAC overexpression increased the viability of hypoxic cells. Taken together, these results suggest that aNAC degradation triggers ER stress responses and initiates apoptotic processes in hypoxic cells, and that GSK-3b may participate upstream in this mechanism.

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Casein Kinase II Phosphorylation Regulates αNAC Subcellular Localization and Transcriptional Coactivating Activity

Cited by 16 publications

References 50 publications

CK2 negatively regulates Gα _s signaling

CK2 negatively regulates Gα _s signaling

Phosphorylation of Threonine 3

αNAC depletion as an initiator of ER stress-induced apoptosis in hypoxia

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Casein Kinase II Phosphorylation Regulates αNAC Subcellular Localization and Transcriptional Coactivating Activity

Cited by 16 publications

References 50 publications

CK2 negatively regulates Gα s signaling

CK2 negatively regulates Gα s signaling

Phosphorylation of Threonine 3

αNAC depletion as an initiator of ER stress-induced apoptosis in hypoxia

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CK2 negatively regulates Gα _s signaling

CK2 negatively regulates Gα _s signaling