Nitric oxide-inducible expression of heme oxygenase-1 in human cells. Translation-independent stabilization of the mRNA and evidence for direct action of nitric oxide.
Expression of heme oxygenase-1 (HO-1) in mammalian cells contributes to resistance to various types of free radical damage. Nitric oxide (NO) induces HO-1 in many cell types, but the specific contribution of transcriptional or post-transcriptional effects to this induction have remained unresolved. Here we show that the extent of HO-1 mRNA expression in IMR-90 and HeLa cells depends on the rate of NO delivery, and that the induction occurs more slowly in HeLa than in human fibroblast (IMR-90) cells. We used a specific NO scavenger (2-(4-carboxylphenyl)-4,4,5,5-tetramethylimidazolin-1-oxyl 3-oxide) that completely prevented the inducible expression of HO-1 by NO, pointing to direct signaling action of NO in this induction. By inhibiting transcription during the NO exposure, we have confirmed that NO treatment activates a mechanism that stabilizes HO-1 mRNA. The increase in the HO-1 mRNA half-life in IMR-90 cells was directly correlated with increasing rates of NO release. We also show here that the stabilization of the HO-1 message does not require de novo protein synthesis. Collectively, these results show that stabilization of HO-1 mRNA can be finely tuned to the NO exposure, and that the effect in human fibroblasts is mediated by a pre-existing protein.
Bouton
C
C
Department of Cancer Cell Biology, Harvard School of Public Health, Boston, Massachusetts 02115, USA.
Demple
B
B
D001565:Benzoates / Q000494:pharmacology; D002460:Cell Line; D003609:Dactinomycin / Q000494:pharmacology; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects / Q000502:physiology*; D006367:HeLa Cells; D006419:Heme Oxygenase (Decyclizing) / Q000235:genetics*; D051547:Heme Oxygenase-1; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology; D007700:Kinetics; D008565:Membrane Proteins; D009569:Nitric Oxide / Q000494:pharmacology / Q000502:physiology*; D020030:Nitric Oxide Donors / Q000494:pharmacology*; D009589:Nitrogen Oxides; D009603:Nitroso Compounds / Q000494:pharmacology; D014176:Protein Biosynthesis; D011691:Puromycin / Q000494:pharmacology; D012333:RNA, Messenger / Q000235:genetics; D013096:Spermine / Q000031:analogs & derivatives / Q000494:pharmacology; D014158:Transcription, Genetic / Q000187:drug effects*
D001565:Benzoates; D007093:Imidazoles; D008565:Membrane Proteins; D020030:Nitric Oxide Donors; D009589:Nitrogen Oxides; D009603:Nitroso Compounds; D012333:RNA, Messenger; C091861:spermine nitric oxide complex; C079393:1,3-dihydroxy-4,4,5,5-tetramethyl-2-(4-carboxyphenyl)tetrahydroimidazole; C094210:2,2'-(hydroxynitrosohydrazono)bis-ethanamine; D003609:Dactinomycin; D013096:Spermine; D009569:Nitric Oxide; D011691:Puromycin; C496541:HMOX1 protein, human; D006419:Heme Oxygenase (Decyclizing); D051547:Heme Oxygenase-1