Induction of MnSOD gene by arachidonic acid is mediated by reactive oxygen species and p38 MAPK signaling pathway in human HepG2 hepatoma cells.
Metabolism of arachidonic acid (AA) is known to induce in different cell types an oxidative stress via the production of reactive oxygen species. As these latter may be scavenged by antioxidant enzymes as manganese and copper/zinc-dependent superoxide dismutase (MnSOD and Cu/ZnSOD, respectively), we investigated the effects of AA on their expression in human HepG2 hepatoma cells. RT-PCR and Western blot data revealed that AA induced an increase in the MnSOD, but not Cu/ZnSOD, expression at the mRNA and protein levels, respectively. This induction was also marked by an increase in MnSOD activity. The AA-induced MnSOD expression required de novo transcription as demonstrated by cotreatment of HepG2 cells with AA and actinomycin D. The fact that MnSOD expression was not induced when HepG2 cells were cultured with 5,8,11,14-eicosatetraynoic acid (ETYA), a nonmetabolizable analog of AA, or with different inhibitors of the AA metabolism pathways suggested that the metabolism of AA was required. Further investigations into the mechanisms by which AA induced MnSOD expression showed that superoxide anions released from AA metabolism act as second messengers via a signal-controlling pathway involving protein kinase C and p38 mitogen activated protein kinase (MAPK). These results define a novel role of p38 MAPK dependent-pathway in the regulation of MnSOD gene.
Bianchi
Arnaud
A
Laboratoire de Biologie Cellulaire du Développement, Université Henri Poincaré-Nancy I, Faculté des Sciences, Vandoeuvre-les-Nancy, France.
Bécuwe
Philippe
P
Franck
Patricia
P
Dauça
Michel
M
D015117:5,8,11,14-Eicosatetraynoic Acid / Q000494:pharmacology; D016718:Arachidonic Acid / Q000494:pharmacology*; D015153:Blotting, Western; D006528:Carcinoma, Hepatocellular / Q000201:enzymology* / Q000473:pathology; D002455:Cell Division / Q000187:drug effects; D017931:DNA Primers / Q000737:chemistry; D004790:Enzyme Induction; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005434:Flow Cytometry; D006801:Humans; D008113:Liver Neoplasms / Q000201:enzymology* / Q000473:pathology; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D009281:Naphthalenes / Q000494:pharmacology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism; D012333:RNA, Messenger / Q000096:biosynthesis*; D017382:Reactive Oxygen Species / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000187:drug effects*; D013482:Superoxide Dismutase / Q000096:biosynthesis / Q000235:genetics*; D013481:Superoxides / Q000378:metabolism*; D013778:Tetrazolium Salts; D013844:Thiazoles; D014407:Tumor Cells, Cultured / Q000187:drug effects* / Q000201:enzymology; D048051:p38 Mitogen-Activated Protein Kinases
D017931:DNA Primers; D004791:Enzyme Inhibitors; D009281:Naphthalenes; D012333:RNA, Messenger; D017382:Reactive Oxygen Species; D013778:Tetrazolium Salts; D013844:Thiazoles; D013481:Superoxides; D015117:5,8,11,14-Eicosatetraynoic Acid; D016718:Arachidonic Acid; D013482:Superoxide Dismutase; D011493:Protein Kinase C; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; C022616:thiazolyl blue; C058819:calphostin C