Phorbol ester-induced generation of reactive oxygen species is protein kinase cbeta -dependent and required for SAPK activation.
Treatment of human U-937 myeloid leukemia cells with 12-O-tetradecanoylphorbol-13-acetate (TPA) is associated with protein kinase C (PKC) betaII-mediated activation of the stress-activated protein kinase (SAPK) pathway. The present studies demonstrate that the TPA response of U-937 cells includes the generation of reactive oxygen species (ROS). By contrast, the TPA-resistant U-937 cell variant (TUR), which is deficient in PKCbetaII expression, failed to respond to TPA with the induction of ROS. Moreover, we show that TPA-induced ROS production is restored in TUR cells stably transfected to express PKCbetaII. The results also demonstrate that TPA-induced ROS production is required for activation of the MEK kinase-1 (MEKK-1)--> SAPK pathway. In concert with this observation, treatment of U-937 with H(2)O(2) as a source of ROS is associated with activation of the MEKK-1-->SAPK cascade. These findings indicate that PKCbetaII is required for TPA-induced ROS production and that the MEKK-1-->SAPK pathway is activated by a ROS-mediated mechanism.
Datta
R
R
Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts 02115, USA.
Yoshinaga
K
K
Kaneki
M
M
Pandey
P
P
Kufe
D
D
D004789:Enzyme Activation; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D007527:Isoenzymes / Q000502:physiology*; D048055:Mitogen-Activated Protein Kinase 8; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D011493:Protein Kinase C / Q000502:physiology*; D017382:Reactive Oxygen Species / Q000378:metabolism*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*; D020298:U937 Cells
D007527:Isoenzymes; D017382:Reactive Oxygen Species; D006861:Hydrogen Peroxide; D011493:Protein Kinase C; D048055:Mitogen-Activated Protein Kinase 8; D020928:Mitogen-Activated Protein Kinases; D013755:Tetradecanoylphorbol Acetate