Induction of Akt phosphorylation in rat primary astrocytes by H2O2 occurs upstream of phosphatidylinositol 3-kinase: no evidence for oxidative inhibition of PTEN.
Phosphorylation of the serine/threonine kinase Akt has previously been shown to be increased by treatment of cells with H2O2; the target of H2O2 has not been clearly identified. Here we show that treatment of rat primary astrocytes with H2O2 resulted in increased Akt phosphorylation that was blocked by wortmannin. The thiol-reducing agent N-acetylcysteine had only a slight inhibitory effect. Treatment with rotenone or antimycin A also resulted in increased wortmannin-sensitive Akt phosphorylation, probably by increasing intracellular H2O2 generation by blocking mitochondrial electron transport. Addition of phosphatidylinositol 3,4-bisphosphate to cells also resulted in an increase in Akt phosphorylation. This increase was additive to that induced by H2O2 and was also blocked by wortmannin. These results suggest that activation of Akt by H2O2 occurs upstream of phosphatidylinositol 3-kinase (PI 3-K) activity in astrocytes. The data indicate that major oxidative effects do not occur at the level of the PI 3-K-antagonizing phosphatase PTEN.
Salsman
S
S
Department of Biochemistry and Molecular Biology, Oklahoma University Health Sciences Center, Oklahoma City 73104, USA.
Felts
N
N
Pye
Q N
QN
Floyd
R A
RA
Hensley
K
K
D000111:Acetylcysteine / Q000494:pharmacology; D000730:Androstadienes / Q000494:pharmacology; D000818:Animals; D000968:Antimycin A / Q000494:pharmacology; D001253:Astrocytes / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D015153:Blotting, Western; D002478:Cells, Cultured; D004815:Epidermal Growth Factor / Q000378:metabolism / Q000494:pharmacology; D066246:ErbB Receptors / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000494:pharmacology*; D051059:PTEN Phosphohydrolase; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D019269:Phosphatidylinositol 4,5-Diphosphate / Q000494:pharmacology; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010744:Phosphoric Monoester Hydrolases / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D010768:Phosphoserine / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt; D051381:Rats; D012402:Rotenone / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects*; D025521:Tumor Suppressor Proteins; D014475:Uncoupling Agents / Q000494:pharmacology; D000077191:Wortmannin
D000111:Acetylcysteine; D000730:Androstadienes; D000968:Antimycin A; D004815:Epidermal Growth Factor; D066246:ErbB Receptors; D006861:Hydrogen Peroxide; D051059:PTEN Phosphohydrolase; D019869:Phosphatidylinositol 3-Kinases; D019269:Phosphatidylinositol 4,5-Diphosphate; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010744:Phosphoric Monoester Hydrolases; D010768:Phosphoserine; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D012402:Rotenone; D025521:Tumor Suppressor Proteins; D014475:Uncoupling Agents; D000077191:Wortmannin; C494920:Akt1 protein, rat