Oxygen tension regulates heme oxygenase-1 gene expression in mammalian cell lines.
The gene expression of heme oxygenase-1 (HO-1) was studied in mammalian cell lines exposed to hyperoxia. Northern blot analysis demonstrated that hyperoxic exposure increased the HO-1 mRNA levels in various types of cells, including human hepatoma (HepG2) cells. This increase was time- and dose-dependent, and reversible. The HO-1 mRNA levels in HepG2 cells were increased to 2.3- and 4.2-fold of the control by hyperoxic exposure of 6 and 23 h, respectively. Cycloheximide and actinomycin D inhibited the increases in the HO-1 mRNA level produced by hyperoxia, indicating that response to hyperoxia is dependent on de novo protein synthesis and mRNA transcription. Antioxidants, desferrioxamine (DES) and o-phenanthroline (OP) partially inhibited the HO-1 mRNA elevation by hyperoxia. In addition to hyperoxia, sodium arsenite (NaAsO2), cadmium chloride (CdCl(2)) and hydrogen peroxide (H2O2), which are reactive oxygen intermediates (ROI) generators, increased the HO-1 mRNA level by 11-, 22- and 2.5-fold, respectively. OP, an antioxidant and a bivalent metal chelator, blocked the HO-1 mRNA elevation induced either by hyperoxia or by the three ROI generators. In contrast to OP, N-acetylcysteine (NAC), an antioxidant and membrane-permeable reducing reagent, enhanced the HO-1 mRNA elevation induced by hyperoxia, although NAC inhibited the mRNA elevation induced by NaAsO2, CdCl2 and H2O2. These results indicate that oxygen tension regulates HO-1 gene expression and suggest that hyperoxia-specific and redox-sensitive regulators may be involved in hyperoxia-mediated HO-1 gene expression.
Takahashi
S
S
School of Life Science, Tokyo University of Pharmacy and Life Science, Japan.
Takahashi
Y
Y
Yoshimi
T
T
Miura
T
T
D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D002460:Cell Line; D002470:Cell Survival; D003513:Cycloheximide / Q000494:pharmacology; D003609:Dactinomycin / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D015971:Gene Expression Regulation, Enzymologic; D006419:Heme Oxygenase (Decyclizing) / Q000096:biosynthesis* / Q000235:genetics; D051547:Heme Oxygenase-1; D006801:Humans; D008565:Membrane Proteins; D051379:Mice; D019384:Nucleic Acid Synthesis Inhibitors / Q000494:pharmacology; D016877:Oxidants / Q000494:pharmacology; D010100:Oxygen / Q000494:pharmacology*; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats
D000975:Antioxidants; D008565:Membrane Proteins; D019384:Nucleic Acid Synthesis Inhibitors; D016877:Oxidants; D011500:Protein Synthesis Inhibitors; D012333:RNA, Messenger; D003609:Dactinomycin; D003513:Cycloheximide; C496541:HMOX1 protein, human; D006419:Heme Oxygenase (Decyclizing); D051547:Heme Oxygenase-1; C496542:Hmox1 protein, mouse; D010100:Oxygen