Regulation of Glycogen Synthesis by Amino Acids in Cultured Human Muscle Cells

Armstrong, Jane L.; Bonavaud, Sylvie; Toole, Barry; Yeaman, Stephen J.

doi:10.1074/jbc.m004812200

Cited by 104 publications

(78 citation statements)

References 44 publications

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“…Hence, we examined the effect of combined inhibition of GSK-3b and p70S6K, and induction of DNAdamage. We used lithium chloride to inhibit GSK-3b, nonessential amino-acid (NEAA) restriction to inhibit p70S6K 16 and cisplatin, a key chemotherapeutic drug for bladder cancer and a known inducer of DNA-damage and p70S6K cleavage, to induce DNA-damage. 17 Blebbishield-mediated sphere formation after apoptosis and its dependence on amino acid-p70S6K signaling.…”

Section: Resultsmentioning

confidence: 99%

Blebbishields, the emergency program for cancer stem cells: sphere formation and tumorigenesis after apoptosis

et al. 2012

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Caspases mediate apoptosis and have also been implicated in stem-cell biology. How caspases are linked to stem-cell biology is not known. Here, we show that the apoptotic blebs of cancer cells fuse together to form novel structures called 'blebbishields'. Blebbishields form spheres by fusion. Both blebbishield formation and sphere formation involve active caspases and N-linked glycosylation. Sphere formation is enhanced by acidic pH and is counteracted by inhibitors of proton pump, caspases, and cholesterol. The blebbishields from VEGFR2 High cells are capable of enhanced sphere formation. Blebbishields express transiently downregulated stem-cell markers and the sphere-forming blebbishield-derived cells are tumorigenic. Our study demonstrates that the cancer stem cells can survive after apoptosis by blebbishield formation and subsequent sphere formation.

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Section: Resultsmentioning

confidence: 99%

Blebbishields, the emergency program for cancer stem cells: sphere formation and tumorigenesis after apoptosis

et al. 2012

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“…Numerous other stimuli also lead to inactivation of GSK-3 through S9/S21 phosphorylation, including growth factors such as EGF and PDGF that stimulate the GSK-3-inactivating kinase p90 RSK (also known as MAPKAP-K1) through MAP kinases (Brady et al, 1998;Saito et al, 1994), activators of p70 ribosomal S6 kinase (p70S6K) such as amino acids, (Armstrong et al, 2001;Krause et al, 2002;Terruzzi et al, 2002), activators of cAMP-activated protein kinase (PKA) (Fang et al, 2000;Li et al, 2000;Tanji et al, 2002) and PKC activators (Ballou et al, 2001;Fang et al, 2002).…”

Section: Gsk-3 Phosphorylation: Insights From Crystal Structures 1) Tmentioning

confidence: 99%

GSK-3: tricks of the trade for a multi-tasking kinase

Doble

Woodgett

2003

Journal of Cell Science

1,897

1,883

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Glycogen synthase kinase 3 (GSK-3) is a multifunctional serine/threonine kinase found in all eukaryotes. The enzyme is a key regulator of numerous signalling pathways, including cellular responses to Wnt, receptor tyrosine kinases and G-protein-coupled receptors and is involved in a wide range of cellular processes, ranging from glycogen metabolism to cell cycle regulation and proliferation. GSK-3 is unusual in that it is normally active in cells and is primarily regulated through inhibition of its activity. Another peculiarity compared with other protein kinases is its preference for primed substrates,that is, substrates previously phosphorylated by another kinase. Several recent advances have improved our understanding of GSK-3 regulation in multiple pathways. These include the solution of the crystal structure of GSK-3, which has provided insight into GSK-3's penchant for primed substrates and the regulation of GSK-3 by serine phosphorylation, and findings related to the involvement of GSK-3 in the Wnt/β-catenin and Hedgehog pathways. Finally, since increased GSK-3 activity may be linked to pathology in diseases such as Alzheimer's disease and non-insulin-dependent diabetes mellitus,several new GSK-3 inhibitors, such as the aloisines, the paullones and the maleimides, have been developed. Although they are just starting to be characterized in cell culture experiments, these new inhibitors hold promise as therapeutic agents.

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“…The inhibition of GSK3 could alter the balance between this enzyme and PP-1, leading to dephosphorylation of glycogen synthase and its subsequent activation. But, together with an implication of PKB in the stimulation of glucose uptake and glycogen synthesis by insulin (Ueki et al 1998), it has been shown that direct inhibition of GSK3 in liver cells increases glycogenesis (Armstrong et al 2001); thus, a combined mechanism of both might exist. In addition, some authors have provided evidence for a contribution of a rapamycin-sensitive signalling pathway, involving p70s6k, to the control of glycogen synthesis (Shepherd et al 1995, Hurel et al 1996.…”

Section: Introductionmentioning

confidence: 99%

Cell signalling of glucagon-like peptide-1 action in rat skeletal muscle

Acitores

González²,

Sancho³

et al. 2004

Journal of Endocrinology

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Glucagon-like peptide-1 (GLP-1), an incretin with glucose-dependent insulinotropic and insulinindependent antidiabetic properties, has insulin-like effects on glucose metabolism in extrapancreatic tissues participating in overall glucose homeostasis. These effects are exerted through specific receptors not associated with cAMP, an inositol phosphoglycan being a possible second messenger. In rat hepatocytes, activation of phosphatidylinositol 3-kinase (PI3K)/protein kinase B (PKB), protein kinase C (PKC) and protein phosphatase 1 (PP-1) has been shown to be involved in the GLP-1-induced stimulation of glycogen synthase. We have investigated the role of enzymes known or suggested to mediate the actions of insulin in the GLP-1-induced increase in glycogen synthase a activity in rat skeletal muscle strips.We first explored the effect of GLP-1, compared with that of insulin, on the activation of PI3K, PKB, p70s6 kinase (p70s6k) and p44/42 mitogen-activated protein kinases (MAPKs) and the action of specific inhibitors of these kinases on the insulin-and GLP-1-induced increment in glycogen synthase a activity.The study showed that GLP-1, like insulin, activated PI3K/PKB, p70s6k and p44/42. Wortmannin (a PI3K inhibitor) reduced the stimulatory action of insulin on glycogen synthase a activity and blocked that of GLP-1, rapamycin (a 70s6k inhibitor) did not affect the action of GLP-1 but abolished that of insulin, PD98059 (MAPK inhibitor) was ineffective on insulin but blocked the action of GLP-1, okadaic acid (a PP-2A inhibitor) and tumour necrosis factor-(a PP-1 inhibitor) were both ineffective on GLP-1 but abolished the action of insulin, and Ro 31-8220 (an inhibitor of some PKC isoforms) reduced the effect of GLP-1 while completely preventing that of insulin.It was concluded that activation of PI3K/PKB and MAPKs is required for the GLP-1-induced increment in glycogen synthase a activity, while PKC, although apparently participating, does not seem to play an essential role; unlike in insulin signaling, p70s6k, PP-1 and PP-2A do not seem to be needed in the action of GLP-1 upon glycogen synthase a activity in rat muscle.

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Regulation of Glycogen Synthesis by Amino Acids in Cultured Human Muscle Cells

Cited by 104 publications

References 44 publications

Blebbishields, the emergency program for cancer stem cells: sphere formation and tumorigenesis after apoptosis

Blebbishields, the emergency program for cancer stem cells: sphere formation and tumorigenesis after apoptosis

GSK-3: tricks of the trade for a multi-tasking kinase

Cell signalling of glucagon-like peptide-1 action in rat skeletal muscle

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