Functional characterisation of the regulation of CAAT enhancer binding protein alpha by GSK-3 phosphorylation of Threonines 222/226

Hk, Liu; Perrier, Sébastien; Lipina, Christopher; Finlay, David K.; McLauchlan, Hilary; Hastie, C. James; Hundal, HS; Sutherland, Calum

doi:10.1186/1471-2199-7-14

Cited by 21 publications

(11 citation statements)

References 52 publications

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“…Hematopoietic cell lines have also been a productive source for studying effects of phosphorylation on C/EBP␣ function, and phosphorylation of Ser-248 through protein kinase C was found to promote interaction between Ras and C/EBP␣, leading to increased granulopoiesis (29). In addition, GSK-3 phosphorylation of C/EBP␣ on Thr-222 and Thr-226 has been explored (30,31). Studies indicate that phosphorylation at these sites is important for C/EBP␣ function in adipocytes and hepatocytes in both in vitro and in vivo models (30,31).…”

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confidence: 99%

“…How this aspect of C/EBP␣ function may be regulated has yet to be determined; however, recent insights into the effects of post-translational modifications of C/EBP␣ in modulating its function suggest a role for phosphorylation (25)(26)(27)(28)(29)(30)(31)(32)(33)(34).…”

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confidence: 99%

“…In addition, GSK-3 phosphorylation of C/EBP␣ on Thr-222 and Thr-226 has been explored (30,31). Studies indicate that phosphorylation at these sites is important for C/EBP␣ function in adipocytes and hepatocytes in both in vitro and in vivo models (30,31).…”

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confidence: 99%

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Phosphorylation of CCAAT/Enhancer-binding Protein α Regulates GLUT4 Expression and Glucose Transport in Adipocytes

Hyuk

Oak

Kang

et al. 2008

Journal of Biological Chemistry

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The transcription factor CCAAT/enhancer-binding protein ␣ (C/EBP␣) is required during adipogenesis for development of insulin-stimulated glucose uptake. Modes for regulating this function of C/EBP␣ have yet to be determined. Phosphorylation of C/EBP␣ on Ser-21 has been implicated in the regulation of granulopoiesis and hepatic gene expression. To explore the role of Ser-21 phosphorylation on C/EBP␣ function during adipogenesis, we developed constructs in which Ser-21 was mutated to alanine (S21A) to model dephosphorylation. In two cell culture models deficient in endogenous C/EBP␣, enforced expression of S21A-C/EBP␣ resulted in normal lipid accumulation and expression of many adipogenic markers. However, S21A-C/ EBP␣ had impaired ability to activate the Glut4 promoter specifically, and S21A-C/EBP␣ expression resulted in diminished GLUT4 and adiponectin expression, as well as reduced insulinstimulated glucose uptake. No defects in insulin signaling or GLUT4 vesicle trafficking were identified with S21A-C/EBP␣ expression, and when exogenous GLUT4 expression was enforced to normalize expression in S21A-C/EBP␣ cells, insulin-responsive glucose transport was reconstituted, suggesting that the primary defect was a deficit in GLUT4 levels. Mice in which endogenous C/EBP␣ was replaced with S21A-C/EBP␣ displayed reduced GLUT4 and adiponectin protein expression in epididymal adipose tissue and increased blood glucose compared with wild-type littermates. These results suggest that phosphorylation of C/EBP␣ on Ser-21 may regulate adipocyte gene expression and whole body glucose homeostasis.Although adipocytes were initially thought to be passive storage vessels for caloric excess, it is now known that adipose tissue acts as an important metabolic and endocrine organ (1-4). One of the major regulatory hormones for fat cell function is insulin, which regulates whole body energy balance by increasing glucose uptake into muscle and adipose tissue via translocation of the glucose transporter GLUT4 to the cell surface and by inhibiting hepatic gluconeogenesis (4 -7). Several studies have identified C/EBP␣ 2 as a critical factor for development of insulin-sensitive glucose uptake in developing adipocytes (8 -11).Adipogenesis is a coordinated transcriptional cascade of gene expression regulated by many transcription factors, including PPAR␥ and members of the C/EBP and KLF families of transcription factors (12-17). Mouse models suggest that C/EBP␣ and PPAR␥ are each required for complete development of adipose tissue in vivo (18 -20). In vitro cell culture studies determined that although constitutive expression of either PPAR␥ or C/EBP␣ is sufficient to convert fibroblasts into fatladen, adipocyte-like cells (21), C/EBP␣ is required for the establishment of insulin-stimulated glucose uptake in adipocytes (10, 11). In both C/EBP␣ Ϫ/Ϫ mouse embryonic fibroblasts (MEFs) and NIH-3T3 fibroblasts, which are also deficient in C/EBP␣, overexpression of PPAR␥ is sufficient to induce lipid accumulation, but these "adipocytes" do not transpo...

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Phosphorylation of CCAAT/Enhancer-binding Protein α Regulates GLUT4 Expression and Glucose Transport in Adipocytes

Hyuk

Oak

Kang

et al. 2008

Journal of Biological Chemistry

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“…6A). Mutation at Ser-21 has been reported to be imperative in detecting ERK signaling (36,37); Thr-222, Thr-226, and Ser-230 are phosphorylated by GSK3 signaling (38); and Ser-248 is phosphorylated by RAS signaling (39). A single mutation at Ser-21, Ser-230, or Ser-248 did not show any significant effects on C/EBP␣-driven Il4 promoter-luciferase activity.…”

Section: Pi3k Signaling and Calcium Signaling Pathways Are Required Fmentioning

confidence: 89%

CCAAT/Enhancer-binding Protein α (C/EBPα) Is Critical for Interleukin-4 Expression in Response to FcϵRI Receptor Cross-linking

Nishida

Chaves

et al. 2011

Journal of Biological Chemistry

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Basophils mediate many of their biological functions by producing IL-4. However, it is unknown how the Il4 gene is regulated in basophils. Here, we report that CCAAT/enhancer-binding protein ␣ (C/EBP␣), a major myeloid transcription factor, was highly expressed in basophils. We show that C/EBP␣ selectively activated Il4 promoter-luciferase reporter gene transcription in response to IgE cross-linking, but C/EBP␣ did not activate other known Th2 or mast cell enhancers. We found that the PI3K pathway and calcineurin were essential in C/EBP␣-driven Il4 promoter-luciferase gene transcription. Our mutation analyses revealed that C/EBP␣ drove Il4 promoter-luciferase activity depending on its DNA binding domain. Mutation of the C/EBP␣-binding site in the Il4 promoter region abolished C/EBP␣-driven Il4 promoter-luciferase activity. Our results further showed that a mutation in nuclear factor of activated T cells (NFAT)-binding sites in the Il4 promoter also negated C/EBP␣-driven Il4 promoter-luciferase activity. Our study demonstrates that C/EBP␣, in cooperation with NFAT, directly regulates Il4 gene transcription.Basophils are a minor cell population, constituting less than 1% of peripheral blood and bone marrow cells. Basophils have been linked to allergic diseases because of their presence at the site of allergic inflammation. Basophils are found in the lung and sputum of allergic asthmatics, in the nasal mucosa and secretions of allergic rhinitis patients, in the skin lesions of atopic dermatitis patients during allergic late phase reactions, and in various other chronic allergic disease conditions (1). Akashi and co-workers (14,15) showed that the order of expression of GATA2, an essential transcription factor for early hematopoietic stem cell development (14), and C/EBP␣, a required transcription factor for all myeloid cell differentiation (15), has been implicated as the deciding factor in determining the fate of basophils. If GATA2 expression precedes C/EBP␣ expression at the granulocyte-monocyte progenitor stage, then GATA2 together with C/EBP␣ will drive basophil differentiation. Conversely, if C/EBP␣ expression precedes GATA2 expression, then C/EBP␣ and GATA2 will drive eosinophil differentiation (14). However, it remains to be determined whether or not C/EBP␣ can directly regulate the Il4 gene along the basophil development pathway. * This work was supported, in whole or in part, by National Institutes of Health Grants RO1 AI05917 and RO1 AI068083 (to H. H.). □ S The on-line version of this article (available at http://www.jbc.org) contains supplemental Fig. S1 and Tables S1 and S2

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“…Such peak distortion can lead to a severe demolition of the potentially high separation efficiency of CZE. This is still an actual problem, as can be seen from the current literature about just this topic, most papers dealing with the analysis of proteins [35][36][37][38][39][40][41][42][43][44][45][46][47][48][49][50][51] or biological assemblies [52], but taking into small ions as well [53][54][55]. Adsorption with slow kinetics causes peak broadening; it results in symmetrical peaks in case of a linear adsorption isotherm, and in asymmetrical peaks in case of a nonlinear isotherm.…”

Section: Introductionmentioning

confidence: 99%

CE of tricyclic antidepressant clomipramine and metabolites: Electromigration and wall adsorption

et al. 2007

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CE of tricyclic antidepressants clomipramine and its metabolites demethylclomipramine, didemethylclomipramine and 8-hydroxyclomipramine resulted in partly extremely tailing peaks in bare fused-silica capillaries. Especially at high pH of the BGE this behavior was not unexpected as adsorption of the cationic analytes onto the negatively charged wall due to electrostatic attraction can be supposed. Less expected was the observation that peak tailing could not be overcome neither by using a capillary with dynamic coating with cationic CTAB added to the BGE, nor by the usage of a capillary permanently coated with polyvinyl alcohol (PVA), both operated at acidic pH. As this tailing was even more pronounced than with bare fused silica, and was suppressed upon addition of MeCN to the BGE, another source of adsorption than pure ion-ion interaction seems plausible. In the bare silica capillary the mobility, mu, of the analytes followed roughly the pH dependence of a monoacidic base, but two deviations from the sigmoid theoretical curve were evident: (i) even at low pH the mobilities were not constant; they decreased in contrary with pH over the entire range; (ii) the apparent pK(a) values of two analytes, derived at the pH with halve the mobility at low pH, are significantly smaller than the thermodynamic pK(a). Upon modifying the expression for mu = f(pH), and considering the pH dependence of the negative charge density at the wall by an additional term which takes chromatographic retention into account, an equation was derived which enables the description of the observed electromigration of the analytes as function of pH, pK(a) of analytes and surface silanol groups, actual mobility of analytes, distribution coefficient (or retention factor) due to adsorption including its pH dependence. The interplay of electrophoretic movement and residual adsorptive retention allowed to resolve the analytes finally in an uncoated capillary, namely at pH 7.65 (30 mM ionic strength), whereas at the cost of the robustness of the separation system.

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Functional characterisation of the regulation of CAAT enhancer binding protein alpha by GSK-3 phosphorylation of Threonines 222/226

Cited by 21 publications

References 52 publications

Phosphorylation of CCAAT/Enhancer-binding Protein α Regulates GLUT4 Expression and Glucose Transport in Adipocytes

Phosphorylation of CCAAT/Enhancer-binding Protein α Regulates GLUT4 Expression and Glucose Transport in Adipocytes

CCAAT/Enhancer-binding Protein α (C/EBPα) Is Critical for Interleukin-4 Expression in Response to FcϵRI Receptor Cross-linking

CE of tricyclic antidepressant clomipramine and metabolites: Electromigration and wall adsorption

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