The activation of protein kinase B by H2O2 or heat shock is mediated by phosphoinositide 3-kinase and not by mitogen-activated protein kinase-activated protein kinase-2.
Protein kinase B (PKB) isoforms became activated [and glycogen synthase kinase-3 (GSK3) became inhibited] when mouse Swiss 3T3 fibroblasts were exposed to oxidative stress (H2O2) or heat shock, but not when they were exposed to osmotic shock (0.5 M sorbitol or 0. 7 M NaCl), chemical stress (sodium arsenite), the protein-synthesis inhibitor anisomycin, or UV radiation. In contrast, all seven stimuli activated mitogen-activated protein kinase-activated protein kinase-2 (MAPKAP-K2). The activation of MAPKAP-K2 was suppressed by the drug SB 203580, but not by inhibitors of phosphoinositide (phosphatidylinositide, PI) 3-kinase. In contrast, the activation of PKB isoforms and the inhibition of GSK3 by oxidative stress or heat shock were prevented by inhibitors of PI 3-kinase, but not by SB 203580. Thus the activation of PKB by oxidative stress or heat shock is mediated by PI 3-kinase and not by MAPKAP-K2. PKBalpha and PKBgamma were also activated by heat shock and oxidative stress in human embryonic kidney 293 cells and PKBgamma was activated by heat shock in NIH 3T3 cells; in each case activation was suppressed by inhibitors of PI 3-kinase. The activation of PKB isoforms by H2O2 may underlie some of the insulin-mimetic effects of this compound.
Shaw
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MRC Protein Phosphorylation Unit, Department of Biochemistry, University of Dundee, Dundee DD1 4HN, UK. MShaw@BAD.dundee.ac.uk
Cohen
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P
Alessi
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DR
D016475:3T3 Cells; D000595:Amino Acid Sequence; D000818:Animals; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000037:antagonists & inhibitors; D002460:Cell Line; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D038362:Glycogen Synthase Kinase 3; D038341:Glycogen Synthase Kinases; D018869:Heat-Shock Response; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D007093:Imidazoles / Q000494:pharmacology; D047908:Intracellular Signaling Peptides and Proteins; D051379:Mice; D008969:Molecular Sequence Data; D018384:Oxidative Stress; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D000081082:Phosphoinositide-3 Kinase Inhibitors; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt; D011725:Pyridines / Q000494:pharmacology; D000099190:MAP-Kinase-Activated Kinase 2
D017871:Calcium-Calmodulin-Dependent Protein Kinases; D004791:Enzyme Inhibitors; D038362:Glycogen Synthase Kinase 3; D038341:Glycogen Synthase Kinases; D006861:Hydrogen Peroxide; D007093:Imidazoles; D047908:Intracellular Signaling Peptides and Proteins; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D011725:Pyridines; D000099190:MAP-Kinase-Activated Kinase 2; C093642:SB 203580