scholarly journals Glycogen Synthase Kinase 3 Is an Insulin-Regulated C/EBPα Kinase

1999 ◽  
Vol 19 (12) ◽  
pp. 8433-8441 ◽  
Author(s):  
Sarah E. Ross ◽  
Robin L. Erickson ◽  
Nahid Hemati ◽  
Ormond A. MacDougald
Keyword(s):  
Conformational Changes ◽  
Kinase Inhibitor ◽  
Glycogen Synthase ◽  
Glycogen Synthase Kinase ◽  
Glycogen Synthase Kinase 3 ◽  
Phosphatidylinositol 3 Kinase ◽  
Pharmacological Agents ◽  
Enhancer Binding Protein

ABSTRACT CCAAT/enhancer binding protein α (C/EBPα) is a transcription factor involved in creating and maintaining the adipocyte phenotype. We have shown previously that insulin stimulates dephosphorylation of C/EBPα in 3T3-L1 adipocytes. Studies to identify the insulin-sensitive sites of phosphorylation reveal that a C/EBPα peptide (amino acids H215 to K250) is phosphorylated on T222, T226, and S230 in vivo. The context of these phosphoamino acids implicates glycogen synthase kinase 3 (GSK3), whose activity is known to be repressed in response to insulin, as a potential kinase for phosphorylation of T222 and T226. Accordingly, GSK3 phosphorylates the predicted region of C/EBPα on threonine in vitro, and GSK3 uses C/EBPα as a substrate in vivo. In addition, the effect of pharmacological agents on GSK3 activity correlates with regulation of C/EBPα phosphorylation. Treatment of 3T3-L1 adipocytes with the phosphatidylinositol 3-kinase inhibitor wortmannin results in phosphorylation of C/EBPα, whereas treatment with the GSK3 inhibitor lithium results in dephosphorylation of C/EBPα. Collectively, these data indicate that insulin stimulates dephosphorylation of C/EBPα on T222 and T226 through inactivation of GSK3. Since dephosphorylation of C/EBPα in response to lithium is blocked by okadaic acid, strong candidates for the T222 and T226 phosphatase are protein phosphatases 1 and 2a. Treatment of adipocytes with insulin alters the protease accessibility of widespread sites within the N terminus of C/EBPα, consistent with phosphorylation causing profound conformational changes. Finally, phosphorylation of C/EBPα and other substrates by GSK3 may be required for adipogenesis, since treatment of differentiating preadipocytes with lithium inhibits their conversion to adipocytes.

scholarly journals GSK-3β in Pancreatic Cancer: Spotlight on 9-ING-41, Its Therapeutic Potential and Immune Modulatory Properties

Biology ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 610
Author(s):  
Robin Park ◽  
Andrew L. Coveler ◽  
Ludimila Cavalcante ◽  
Anwaar Saeed
Keyword(s):  
Pancreatic Cancer ◽  
Therapeutic Potential ◽  
Glycogen Synthase ◽  
Glycogen Synthase Kinase ◽  
Glycogen Synthase Kinase 3 ◽  
In Vivo Models ◽  
Gsk 3Β ◽  
Early Phase Clinical Trials

Glycogen synthase kinase-3 beta is a ubiquitously and constitutively expressed molecule with pleiotropic function. It acts as a protooncogene in the development of several solid tumors including pancreatic cancer through its involvement in various cellular processes including cell proliferation, survival, invasion and metastasis, as well as autophagy. Furthermore, the level of aberrant glycogen synthase kinase-3 beta expression in the nucleus is inversely correlated with tumor differentiation and survival in both in vitro and in vivo models of pancreatic cancer. Small molecule inhibitors of glycogen synthase kinase-3 beta have demonstrated therapeutic potential in pre-clinical models and are currently being evaluated in early phase clinical trials involving pancreatic cancer patients with interim results showing favorable results. Moreover, recent studies support a rationale for the combination of glycogen synthase kinase-3 beta inhibitors with chemotherapy and immunotherapy, warranting the evaluation of novel combination regimens in the future.

scholarly journals Priming-Dependent Phosphorylation and Regulation of the Tumor Suppressor pVHL by Glycogen Synthase Kinase 3

2006 ◽  
Vol 26 (15) ◽  
pp. 5784-5796 ◽  
Author(s):  
Alexander Hergovich ◽  
Joanna Lisztwan ◽  
Claudio R. Thoma ◽  
Christiane Wirbelauer ◽  
Robert E. Barry ◽  
...  
Keyword(s):  
Tumor Suppressor ◽  
Glycogen Synthase ◽  
Human Cancer ◽  
Suppressor Gene ◽  
Binding Activity ◽  
Glycogen Synthase Kinase ◽  
Normal Operation ◽  
Glycogen Synthase Kinase 3

ABSTRACT Inactivation of the von Hippel-Lindau (VHL) tumor suppressor gene is linked to the development of tumors of the eyes, kidneys, and central nervous system. VHL encodes two gene products, pVHL30 and pVHL19, of which one, pVHL30, associates functionally with microtubules (MTs) to regulate their stability. Here we report that pVHL30 is a novel substrate of glycogen synthase kinase 3 (GSK3) in vitro and in vivo. Phosphorylation of pVHL on serine 68 (S68) by GSK3 requires a priming phosphorylation event at serine 72 (S72) mediated in vitro by casein kinase I. Functional analysis of pVHL species carrying nonphosphorylatable or phosphomimicking mutations at S68 and/or S72 reveals a central role for these phosphorylation events in the regulation of pVHL's MT stabilization (but not binding) activity. Taken together, our results identify pVHL as a novel priming-dependent substrate of GSK3 and suggest a dual-kinase mechanism in the control of pVHL's MT stabilization function. Since GSK3 is a component of multiple signaling pathways that are altered in human cancer, our results further imply that normal operation of the GSK3-pVHL axis may be a critical aspect of pVHL's tumor suppressor mechanism through the regulation of MT dynamics.

scholarly journals Glycogen Synthase Kinase 3 Inhibition Promotes Adult Hippocampal Neurogenesis in Vitro and in Vivo

2012 ◽  
Vol 3 (11) ◽  
pp. 963-971 ◽  
Author(s):  
Jose A. Morales-Garcia ◽  
Rosario Luna-Medina ◽  
Sandra Alonso-Gil ◽  
Marina Sanz-SanCristobal ◽  
Valle Palomo ◽  
...  
Keyword(s):  
Glycogen Synthase ◽  
Hippocampal Neurogenesis ◽  
Adult Hippocampal Neurogenesis ◽  
Glycogen Synthase Kinase ◽  
Glycogen Synthase Kinase 3

scholarly journals Hierarchical phosphorylation at N-terminal transformation-sensitive sites in c-Myc protein is regulated by mitogens and in mitosis.

1994 ◽  
Vol 14 (8) ◽  
pp. 5510-5522 ◽  
Author(s):  
B Lutterbach ◽  
S R Hann
Keyword(s):  
Glycogen Synthase ◽  
Mitogen Activated Protein Kinase ◽  
Glycogen Synthase Kinase ◽  
Glycogen Synthase Kinase 3 ◽  
Terminal Domain ◽  
In Vivo Experiments ◽  
Phosphopeptide Mapping ◽  
Hierarchical Phosphorylation

The N-terminal domain of the c-Myc protein has been reported to be critical for both the transactivation and biological functions of the c-Myc proteins. Through detailed phosphopeptide mapping analyses, we demonstrate that there is a cluster of four regulated and complex phosphorylation events on the N-terminal domain of Myc proteins, including Thr-58, Ser-62, and Ser-71. An apparent enhancement of Ser-62 phosphorylation occurs on v-Myc proteins having a mutation at Thr-58 which has previously been correlated with increased transforming ability. In contrast, phosphorylation of Thr-58 in cells is dependent on a prior phosphorylation of Ser-62. Hierarchical phosphorylation of c-Myc is also observed in vitro with a specific glycogen synthase kinase 3 alpha, unlike the promiscuous phosphorylation observed with other glycogen synthase kinase 3 alpha and 3 beta preparations. Although both p42 mitogen-activated protein kinase and cdc2 kinase specifically phosphorylate Ser-62 in vitro and cellular phosphorylation of Thr-58/Ser-62 is stimulated by mitogens, other in vivo experiments do not support a role for these kinases in the phosphorylation of Myc proteins. Unexpectedly, both the Thr-58 and Ser-62 phosphorylation events, but not other N-terminal phosphorylation events, can occur in the cytoplasm, suggesting that translocation of the c-Myc proteins to the nucleus is not required for phosphorylation at these sites. In addition, there appears to be an unusual block to the phosphorylation of Ser-62 during mitosis. Finally, although the enhanced transforming properties of Myc proteins correlates with the loss of phosphorylation at Thr-58 and an enhancement of Ser-62 phosphorylation, these phosphorylation events do not alter the ability of c-Myc to transactivate through the CACGTG Myc/Max binding site.

In vivo regulation of protein-serine kinases by insulin in skeletal muscle of fructose-hypertensive rats

1999 ◽  
Vol 277 (2) ◽  
pp. E299-E307 ◽  
Author(s):  
Sanjay Bhanot ◽  
Baljinder S. Salh ◽  
Subodh Verma ◽  
John H. McNeill ◽  
Steven L. Pelech
Keyword(s):  
Skeletal Muscle ◽  
Glycogen Synthase ◽  
Insulin Injection ◽  
Glycogen Synthase Kinase 3 ◽  
Phosphatidylinositol 3 Kinase ◽  
S6 Kinase ◽  
Serine Kinases ◽  
Gsk 3Β

The effects of tail-vein insulin injection (2 U/kg) on the regulation of protein-serine kinases in hindlimb skeletal muscle were investigated in hyperinsulinemic hypertensive fructose-fed (FF) animals that had been fasted overnight. Basal protein kinase B (PKB) activity was elevated about twofold in FF rats and was not further stimulated by insulin. Phosphatidylinositol 3-kinase (PI3K), which lies upstream of PKB, was increased ∼3.5-fold within 2–5 min by insulin in control rats. Basal and insulin-activated PI3K activities were further enhanced up to 2-fold and 1.3-fold, respectively, in FF rats. The 70-kDa S6 kinase (S6K) was stimulated about twofold by insulin in control rats. Both basal and insulin-stimulated S6K activity was further enhanced up to 1.5-fold and 3.5-fold, respectively, in FF rats. In control rats, insulin caused a 40–50% reduction of the phosphotransferase activity of the β-isoform of glycogen synthase kinase 3 (GSK-3β), which is a PKB target in vitro. Basal GSK-3β activity was decreased by ∼40% in FF rats and remained unchanged after insulin treatment. In summary, 1) the PI3K → PKB → S6K pathway was upregulated under basal conditions, and 2) insulin stimulation of PI3K and S6K activities was enhanced, but both PKB and GSK-3 were refractory to the effects of insulin in FF rats.

scholarly journals Selective Glycogen Synthase Kinase 3 Inhibitors Potentiate Insulin Activation of Glucose Transport and Utilization In Vitro and In Vivo

Diabetes ◽  
2003 ◽  
Vol 52 (3) ◽  
pp. 588-595 ◽  
Author(s):  
D. B. Ring ◽  
K. W. Johnson ◽  
E. J. Henriksen ◽  
J. M. Nuss ◽  
D. Goff ◽  
...  
Keyword(s):  
Glucose Transport ◽  
Glycogen Synthase ◽  
Glycogen Synthase Kinase ◽  
Glycogen Synthase Kinase 3

scholarly journals N-terminal phosphorylation regulates the activity of Glycogen Synthase Kinase 3 from Plasmodium falciparum

2021 ◽  
Author(s):  
Samuel Pazicky ◽  
Arne Alder ◽  
Haydyn Mertens ◽  
D. I. Svergun ◽  
Tim Gilberger ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Conformational Changes ◽  
Glycogen Synthase ◽  
New Drugs ◽  
Glycogen Synthase Kinase ◽  
Scattering Data ◽  
Glycogen Synthase Kinase 3 ◽  
X Ray ◽  
X Ray Scattering

As the decline of malaria cases stalled over the last five years, novel targets in Plasmodium falciparum are necessary for the development of new drugs. Glycogen Synthase Kinase (PfGSK3) has been identified as a potential target, since its selective inhibitors were shown to disrupt the parasite`s life cycle. Here, we show that PfGSK3 exhibits autophosphorylation, leading to an extensive phosphorylation both in vitro and in the parasite. In the uncanonical N-terminal region of the parasite enzyme, we identified several autophosphorylation sites that regulate the activity of PfGSK3. By combining molecular modeling with experimental small-angle X-ray scattering data, we show that increased PfGSK3 activity is promoted by conformational changes in the PfGSK3 N-terminus, triggered by N-terminal phosphorylation. Our work provides novel insights into the structure and regulation of the malarial PfGSK3.

scholarly journals Shared Roles of Yeast Glycogen Synthase Kinase 3 Family Members in Nitrogen-Responsive Phosphorylation of Meiotic Regulator Ume6p

2000 ◽  
Vol 20 (15) ◽  
pp. 5447-5453 ◽  
Author(s):  
Yang Xiao ◽  
Aaron P. Mitchell
Keyword(s):  
Gene Expression ◽  
Nitrogen Limitation ◽  
Glycogen Synthase ◽  
Gene Activation ◽  
Glycogen Synthase Kinase ◽  
Glycogen Synthase Kinase 3 ◽  
Meiotic Gene ◽  
Transduction Mechanisms

ABSTRACT Nitrogen limitation activates meiosis and meiotic gene expression in yeast, but nitrogen-responsive signal transduction mechanisms that govern meiotic gene expression are poorly understood. We show here that Ume6p, a subunit of the Ume6p-Ime1p meiotic transcriptional activator, undergoes increased phosphorylation in vivo in response to nitrogen limitation. Phosphorylation depends on an N-terminal glycogen synthase kinase 3 (GSK3) target site in which substitutions cause reduced Ume6p-Ime1p interaction and meiotic gene expression, thus arguing that phosphorylation promotes functional Ume6p-Ime1p interaction. Phosphorylation of this site depends on two GSK3 homologs, Rim11p and Mck1p. Prior studies indicate that Rim11p phosphorylates both Ume6p and Ime1p in vitro and is required for Ume6p-Ime1p interaction, but no evidence has linked Mck1p function to Ume6p activity. Here we find that Mck1p-Ume6p interaction is detectable by two-hybrid assays and that meiosis in a partially defective rim11-K68R mutant is completely dependent on Mck1p. These findings argue that nitrogen limitation governs Rim11p/Mck1p-dependent phosphorylation of Ume6p, which in turn is required for Ume6p-Ime1p interaction and meiotic gene activation.

Hierarchical phosphorylation at N-terminal transformation-sensitive sites in c-Myc protein is regulated by mitogens and in mitosis

1994 ◽  
Vol 14 (8) ◽  
pp. 5510-5522
Author(s):  
B Lutterbach ◽  
S R Hann
Keyword(s):  
Glycogen Synthase ◽  
Mitogen Activated Protein Kinase ◽  
Glycogen Synthase Kinase ◽  
Glycogen Synthase Kinase 3 ◽  
Terminal Domain ◽  
In Vivo Experiments ◽  
Phosphopeptide Mapping ◽  
Hierarchical Phosphorylation

The N-terminal domain of the c-Myc protein has been reported to be critical for both the transactivation and biological functions of the c-Myc proteins. Through detailed phosphopeptide mapping analyses, we demonstrate that there is a cluster of four regulated and complex phosphorylation events on the N-terminal domain of Myc proteins, including Thr-58, Ser-62, and Ser-71. An apparent enhancement of Ser-62 phosphorylation occurs on v-Myc proteins having a mutation at Thr-58 which has previously been correlated with increased transforming ability. In contrast, phosphorylation of Thr-58 in cells is dependent on a prior phosphorylation of Ser-62. Hierarchical phosphorylation of c-Myc is also observed in vitro with a specific glycogen synthase kinase 3 alpha, unlike the promiscuous phosphorylation observed with other glycogen synthase kinase 3 alpha and 3 beta preparations. Although both p42 mitogen-activated protein kinase and cdc2 kinase specifically phosphorylate Ser-62 in vitro and cellular phosphorylation of Thr-58/Ser-62 is stimulated by mitogens, other in vivo experiments do not support a role for these kinases in the phosphorylation of Myc proteins. Unexpectedly, both the Thr-58 and Ser-62 phosphorylation events, but not other N-terminal phosphorylation events, can occur in the cytoplasm, suggesting that translocation of the c-Myc proteins to the nucleus is not required for phosphorylation at these sites. In addition, there appears to be an unusual block to the phosphorylation of Ser-62 during mitosis. Finally, although the enhanced transforming properties of Myc proteins correlates with the loss of phosphorylation at Thr-58 and an enhancement of Ser-62 phosphorylation, these phosphorylation events do not alter the ability of c-Myc to transactivate through the CACGTG Myc/Max binding site.

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