Author:
Vilimek Dino,Duronio Vincent
Abstract
The regulation of glycogen synthase kinase-3 (GSK-3) by phosphorylation at inhibitory sites has been well documented. In many, but not all, cases, the phosphatidylinositol 3-kinase pathway, and particularly the downstream kinase protein kinase B (PKB) / akt, have been shown to be responsible for GSK-3 phosphorylation. Given that no studies have ever reported cytokine-mediated phosphorylation of GSK-3, we investigated the phosphorylation of this kinase in several hemopoietic cell types in response to either interleukin (IL)-3, IL-4 or granulocyte-macrophage colony stimulating factor (GM-CSF). Each of the cytokines was able to stimulate phosphorylation of the isoforms GSK-3α and GSK-3β. However, only in the case of IL-4 stimulation was there any dependence on PKB for this phosphorylation. We were clearly able to show that PKB was capable of phosphorylating GSK-3 in these cells, but studies using inhibitors of the protein kinase C (PKC) family of kinases have shown that these enzymes are more likely to play a key role in GSK-3 phosphorylation. Cytokine-mediated generation of diacylglycerol was demonstrated, supporting the possible activation of PKC family members. Thus, cytokine-dependent GSK-3 phosphorylation in hemopoietic cells proceeds primarily through PKB independent pathways.Key words: kinase, regulation, signal transduction, cytokine, apoptosis.
Publisher
Canadian Science Publishing
Subject
Cell Biology,Molecular Biology,Biochemistry
Cited by
36 articles.
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