Atypical protein kinase C mediates activation of NF-E2-related factor 2 in response to oxidative stress.
Transcription factor NF-E2-related factor 2 (Nrf2) regulates the induction of antioxidative proteins, including heme oxygenase-1 (HO-1). Nrf2 is sequestered in the cytoplasm by Keap1 under unstimulated conditions but translocates into the nucleus and transactivates the antioxidant responsive element (ARE) upon exposure to oxidative insults. It has recently been demonstrated that in vitro phosphorylation of Nrf2 on Ser40 by protein kinase C (PKC) facilitates the dissociation of Nrf2 from the Keap1 complex (Huang HC, Nguyen T, and Pickett CB. J Biol Chem 277: 42769-42774, 2002). The present study was designed to examine whether PKC is involved in oxidative stress-mediated nuclear translocation of Nrf2 in vivo and, if so, which PKC isoforms are involved. Induction of HO-1 gene expression by phorone, a glutathione depletor, and 4-hydroxy-2,3-nonenal (4-HNE), an end product of lipid peroxidation, was suppressed by a specific PKC inhibitor, Ro-31-8220, at concentrations that inhibit all isoforms in WI-38 cells. The induction of HO-1 was not affected by prolonged exposure of the cells to 12-O-tetradecanoylphorbol-13 acetate (TPA), suggesting that TPA-insensitive atypical PKC (aPKC) isoforms are involved. An immunocomplex kinase assay revealed that phorone and 4-HNE increased aPKCiota activity. In COS-7 cells, 4-HNE induced nuclear translocation of the Nrf2-green fluorescent protein (GFP) fusion protein, but not the Nrf2(S40A)-GFP mutant. In the absence of oxidative insults, the Nrf2(S40E)-GFP mutant was distributed in the nucleus. The Nrf2-GFP accumulation in the nucleus was induced by coexpression of aPKCiota, but not by a kinase inactive mutant aPKCiota(K274W). The activity of an ARE-driven reporter was increased by coexpression of aPKCiota, and this effect was eliminated by Ro-31-8220 in HepG2 cells. The reporter activity induced by 4-HNE was inhibited by coexpression of aPKCiota(K274W). These results suggest that phosphorylation of Nrf2 Ser40 by aPKC(s) is involved in the nuclear translocation and ARE transactivation of Nrf2 by oxidative stress.
Numazawa
Satoshi
S
Department of Biochemical Toxicology, School of Pharmaceutical Sciences, Showa University, 1-5-8 Hatanodai, Shinagawa, Tokyo 142, Japan. numazawa@pharm.showa-u.ac.jp
Ishikawa
Makie
M
Yoshida
Aya
A
Tanaka
Sachiko
S
Yoshida
Takemi
T
D021581:Active Transport, Cell Nucleus / Q000187:drug effects / Q000502:physiology; D000447:Aldehydes / Q000494:pharmacology; D000818:Animals; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005057:Eukaryotic Cells / Q000187:drug effects / Q000201:enzymology*; D017930:Genes, Reporter / Q000187:drug effects / Q000235:genetics; D006419:Heme Oxygenase (Decyclizing) / Q000096:biosynthesis / Q000187:drug effects; D051547:Heme Oxygenase-1; D006801:Humans; D007659:Ketones / Q000494:pharmacology; D008565:Membrane Proteins; D009154:Mutation / Q000187:drug effects / Q000235:genetics; D051267:NF-E2-Related Factor 2; D018384:Oxidative Stress / Q000187:drug effects / Q000502:physiology*; D010766:Phosphorylation / Q000187:drug effects; D011493:Protein Kinase C / Q000187:drug effects / Q000378:metabolism*; D011725:Pyridines / Q000494:pharmacology; D011993:Recombinant Fusion Proteins; D015534:Trans-Activators / Q000378:metabolism*; D015854:Up-Regulation / Q000187:drug effects / Q000502:physiology*
D000447:Aldehydes; D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors; D007659:Ketones; D008565:Membrane Proteins; D051267:NF-E2-Related Factor 2; C495635:NFE2L2 protein, human; D011725:Pyridines; D011993:Recombinant Fusion Proteins; D015534:Trans-Activators; C431843:tris(2-pyridylmethyl)amine; C018637:phorone; C496541:HMOX1 protein, human; D006419:Heme Oxygenase (Decyclizing); D051547:Heme Oxygenase-1; C115015:PKC-3 protein; D011493:Protein Kinase C; C027576:4-hydroxy-2-nonenal