Activation of Protein Kinase B Induced by H2O2 and Heat Shock through Distinct Mechanisms Dependent and Independent of Phosphatidylinositol 3-Kinase.

J-STAGE
  • Konishi Hiroaki
    Biosignal Research Center, Kobe University
  • Fujiyoshi Toshihide
    Department of Applied Biological Chemistry, Graduate School of Agriculture and Life Science, The University of Tokyo
  • Fukui Yasuhisa
    Department of Applied Biological Chemistry, Graduate School of Agriculture and Life Science, The University of Tokyo
  • Matsuzaki Hidenori
    Biosignal Research Center, Kobe University
  • Yamamoto Toshiyoshi
    Biosignal Research Center, Kobe University
  • Ono Yoshitaka
    Department of Applied Biological Chemistry, Graduate School of Agriculture and Life Science, The University of Tokyo
  • Andjelkovie Mirjana
    Department of Applied Biological Chemistry, Graduate School of Agriculture and Life Science, The University of Tokyo
  • Hemmings Brian A.
    Friedrich Iliescher Institute
  • Kikkawa Ushio
    Biosignal Research Center, Kobe University

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説明

Protein kinase B (PKB) is a downstream target of phosphatidylinositol (PI) 3-kinase in the signaling pathway of growth factors, and is activated by cellular stress such as H2O2 and heat shock. To study the mechanism of the stress-induced activation of PKB, PI 3-kinase products were measured in stress-stimulated cells. Both PI 3, 4-bisphosphate and PI 3, 4, 5-trisphosphate increased in H2O2-treated cells, and the elevation of these phospholipids and activation of PKB were concurrently blocked by wortmannin, a potent inhibitor of PI 3-kinase. In heat-shocked cells, the level of PI 3, 4-bisphosphate did not change while that of PI 3, 4, 5-trisphosphate increased slightly, and an association between PKB molecules was observed. Two active PKB fractions, presumably monomeric and oligomeric forms, were resolved from heat-shocked cells by gel filtration column chromatography. Activation of the former was suppressed by pretreatment with wortmannin, whereas the generation and activation of the latter were not blocked by the PI 3-kinase inhibitor. Only the monomeric form, but not the oligomeric form, was recovered from H2O2-treated cells, and its activation was prevented by wortmannin. These results indicate that PKB is activated by two distinct mechanisms that are dependent and independent of PI 3-kinase in stress-stimulated cells.

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