Phosphatidylinositol 3-kinase, not extracellular signal-regulated kinase, regulates activation of the antioxidant-responsive element in IMR-32 human neuroblastoma cells.
The antioxidant-responsive element (ARE) plays an important role in the induction of phase II detoxifying enzymes including NADPH:quinone oxidoreductase (NQO1). We report herein that activation of the human NQO1-ARE (hNQO1-ARE) by tert-butylhydroquinone (tBHQ) is mediated by phosphatidylinositol 3-kinase (PI3-kinase), not extracellular signal-regulated kinase (Erk1/2), in IMR-32 human neuroblastoma cells. Treatment with tBHQ significantly increased NQO1 protein without activation of Erk1/2. In addition, PD 98059 (a selective mitogen-activated kinase/Erk kinase inhibitor) did not inhibit hNQO1-ARE-luciferase expression or NQO1 protein induction by tBHQ. Pretreatment with LY 294002 (a selective PI3-kinase inhibitor), however, inhibited both hNQO1-ARE-luciferase expression and endogenous NQO1 protein induction. In support of a role for PI3-kinase in ARE activation we show that: 1) transfection of IMR-32 cells with constitutively active PI3-kinase selectively activated the ARE in a dose-dependent manner that was completely inhibited by treatment with LY 294002; 2) pretreatment of cells with the PI3-kinase inhibitors, LY 294002 and wortmannin, significantly decreased NF-E2-related factor 2 (Nrf2) nuclear translocation induced by tBHQ; and 3) ARE activation by constitutively active PI3-kinase was blocked completely by dominant negative Nrf2. Taken together, these data clearly show that ARE activation by tBHQ depends on PI3-kinase, which lies upstream of Nrf2.
Lee
J M
JM
School of Pharmacy, the Environmental Toxicology Center, the Waisman Center, and the Center for Neuroscience, University of Wisconsin, Madison, Wisconsin 53706, USA.
Hanson
J M
JM
Chu
W A
WA
Johnson
J A
JA
D000975:Antioxidants / Q000378:metabolism*; D001483:Base Sequence; D002867:Chromones / Q000494:pharmacology; D017931:DNA Primers; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D006873:Hydroquinones / Q000494:pharmacology; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D009025:Morpholines / Q000494:pharmacology; D009447:Neuroblastoma / Q000378:metabolism* / Q000473:pathology; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D010766:Phosphorylation; D014407:Tumor Cells, Cultured
D000975:Antioxidants; D002867:Chromones; D017931:DNA Primers; D004791:Enzyme Inhibitors; D006873:Hydroquinones; D009025:Morpholines; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; C018855:2-tert-butylhydroquinone; D019869:Phosphatidylinositol 3-Kinases; D020928:Mitogen-Activated Protein Kinases