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[Mechanisms Of Signal Transduction] Critical Role of the Phosphatidylinositol 3-Kinase/Akt/Glycogen Synthase Kinase-3 Signaling Pathway in Recovery from Anthrax Lethal Toxin-induced Cell Cycle Arrest and MEK Cleavage in Macrophages

[Mechanisms Of Signal Transduction] Critical Role of the Phosphatidylinositol 3-Kinase/Akt/Glycogen Synthase Kinase-3 Signaling Pathway in Recovery from Anthrax Lethal Toxin-induced Cell Cycle Arrest and MEK Cleavage in Macrophages - Science News and Views

[Mechanisms Of Signal Transduction] Critical Role of the Phosphatidylinositol 3-Kinase/Akt/Glycogen Synthase Kinase-3 Signaling Pathway in Recovery from Anthrax Lethal Toxin-induced Cell Cycle Arrest and MEK Cleavage in Macrophages - The latest news and publications from Nature, Science, Cell and other journals. Post science topics and your thoughts here. Anything science related goes here.


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Old 12-14-2007, 11:04 AM
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Default [Mechanisms Of Signal Transduction] Critical Role of the Phosphatidylinositol 3-Kinase/Akt/Glycogen Synthase Kinase-3 Signaling Pathway in Recovery from Anthrax Lethal Toxin-induced Cell Cycle Arrest and MEK Cleavage in Macrophages



[Mechanisms Of Signal Transduction] Critical Role of the Phosphatidylinositol 3-Kinase/Akt/Glycogen Synthase Kinase-3 Signaling Pathway in Recovery from Anthrax Lethal Toxin-induced Cell Cycle Arrest and MEK Cleavage in Macrophages

Anthrax lethal toxin (LeTx) is a virulence factor causing immune suppression and toxic shock of Bacillus anthracis infected host. It inhibits cytokine production and cell proliferation/differentiation in various immune cells. This study showed that a brief exposure of LeTx caused a continual MEK1 cleavage and prevented tumor necrosis factor- (TNF) production in response to lipopolysaccharide (LPS) in non-proliferating cells such as human peripheral blood mononuclear cells or mouse primary peritoneal macrophages. In human monocytic cell lines U-937 and THP-1, LeTx induced cell cycle arrest in G0-G1 phase by rapid down-regulation of cyclin D1/D2 and checkpoint kinase 1 through MEK1 inhibition. However, THP-1 cells adaptively adjusted to LeTx and overrode cell cycle arrest by activating the phosphatidylinositol 3-kinase/Akt signaling pathway. Inhibitory Ser-9 phosphorylation of glycogen synthase kinase 3β (GSK3&beta by Akt prevented proteasome-mediated cyclin D1 degradation and induced cell cycle progress in LeTx-intoxicated THP-1 cells. Recovery from cell cycle arrest was required before recovering from on-going MEK1 cleavage and suppression of TNF production. Furthermore, pretreatment with LeTx or the GSK3-specific inhibitor SB-216763, or transfection with dominant active mutant Akt or degradation-defected mutant cyclin D1 protected cells from LeTx-induced cell cycle arrest, on-going MEK1 cleavage and suppression of TNF production. These results indicate that modulation of phosphatidylinositol 3-kinase/Akt/GSK3β signaling cascades can be beneficial for protecting or facilitating recovery from cellular LeTx intoxication in cells that depend on basal MEK1 activity for proliferation.
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anthrax , arrest , cell , cleavage , critical , cycle , kinase3 , lethal , macrophages , mechanisms , mek , pathway , phosphatidylinositol , recovery , role , signal , signaling , synthase , toxininduced , transduction


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