title: Regulation of insulin-like growth factor-binding protein-1 by nitric oxide under hypoxic conditions.
abstract: Nitric oxide (NO) is believed to play an important, but as yet undefined, role in regulating hypoxia inducible gene expression. Recently, we have reported evidence suggesting that the human insulin-like growth factor-binding protein-1 (IGFBP-1) gene is directly regulated by hypoxia through the hypoxia-inducible factor-1 pathway. The goal of the current study was to investigate NO regulation of hypoxic induction of IGFBP-1 gene expression using HepG2 cells, a model system of hepatic gene expression. We report that a NO generator, sodium nitroprusside, significantly diminishes hypoxic activation of IGFBP-1 protein and messenger ribonucleic acid expression. Furthermore, these effects are independent of guanylate cyclase/ cGMP signaling, as two different inhibitors, LY 83583, a specific inhibitor of guanylate cyclase, and KT 5823, a protein kinase G inhibitor, had no effect on IGFBP-1 induction by hypoxia. Hypoxic induction of a reporter gene containing four tandemly ligated hypoxia response elements was completely blocked by sodium nitroprusside, but not by 8-bromo-cGMP, an analog ofcGMP. These results suggest that NO blocks hypoxic induction of IGFBP-1 by a guanylate cyclase/ cGMP-independent pathway, possibly at the level of oxygen sensing. The impaired hypoxia regulation of IGFBP-1 by nitric oxide may play a key role in the hyperinduction of IGFBP-1 observed in pathophysiological conditions such as fetal hypoxia and preeclampsia where dysregulation of NO has been observed.
authors.affiliation: Department of Gynecology and Obstetrics, Stanford University Medical School, California 94305-5317, USA.
authors.forename: J
authors.initials: J
authors.lastname: Sugawara
authors.forename: D S
authors.initials: DS
authors.lastname: Suh
authors.forename: G H
authors.initials: GH
authors.lastname: Faessen
authors.forename: L F
authors.initials: LF
authors.lastname: Suen
authors.forename: T
authors.initials: T
authors.lastname: Shibata
authors.forename: F
authors.initials: F
authors.lastname: Kaper
authors.forename: A J
authors.initials: AJ
authors.lastname: Giaccia
authors.forename: L C
authors.initials: LC
authors.lastname: Giudice
mesh_terms: D000470:Alkaloids / Q000494:pharmacology; D000634:Aminoquinolines / Q000494:pharmacology; D001483:Base Sequence; D001665:Binding Sites; D002227:Carbazoles; D006528:Carcinoma, Hepatocellular; D015687:Cell Hypoxia; D017124:Conserved Sequence; D006152:Cyclic GMP / Q000031:analogs & derivatives / Q000494:pharmacology / Q000502:physiology; D004268:DNA-Binding Proteins / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects; D006162:Guanylate Cyclase / Q000378:metabolism; D006801:Humans; D051793:Hypoxia-Inducible Factor 1; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D007211:Indoles; D018970:Insulin-Like Growth Factor Binding Protein 1 / Q000235:genetics*; D007700:Kinetics; D008099:Liver / Q000378:metabolism; D008113:Liver Neoplasms; D008156:Luciferases / Q000235:genetics; D008969:Molecular Sequence Data; D009569:Nitric Oxide / Q000502:physiology*; D009599:Nitroprusside / Q000494:pharmacology*; D009687:Nuclear Proteins / Q000378:metabolism; D014176:Protein Biosynthesis; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D015398:Signal Transduction / Q000187:drug effects; D014157:Transcription Factors / Q000378:metabolism; D014158:Transcription, Genetic; D014162:Transfection; D014407:Tumor Cells, Cultured
chemical_list: D000470:Alkaloids; D000634:Aminoquinolines; D002227:Carbazoles; D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors; C497442:HIF1A protein, human; D051793:Hypoxia-Inducible Factor 1; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D007211:Indoles; D018970:Insulin-Like Growth Factor Binding Protein 1; D009687:Nuclear Proteins; D011993:Recombinant Fusion Proteins; D014157:Transcription Factors; C073601:KT 5823; D009599:Nitroprusside; C016276:8-bromocyclic GMP; D009569:Nitric Oxide; C041715:6-anilino-5,8-quinolinedione; D008156:Luciferases; D006162:Guanylate Cyclase; D006152:Cyclic GMP