title: Role of nitric oxide in the regulation of HIF-1alpha expression during hypoxia.
abstract: Hypoxia-inducible factor-1 (HIF-1), a heterodimeric transcription factor consisting of HIF-1alpha and HIF-1beta subunits, controls the expression of a large number of genes involved in the regulation of cellular responses to reduced oxygen availability. The oxygen-regulated subunit, HIF-1alpha, is stabilized in cells exposed to hypoxia. The regulation of hypoxic responses by nitric oxide (NO) is believed to have wide pathophysiological relevance, thus we investigated whether NO affects HIF-1 activation in hypoxic cells. Here we show that NO generated from NO donors prevented HIF-1alpha hypoxic accumulation in Hep 3B and PC-12 cells. Addition of a glutathione analog or peroxynitrite scavengers prevented the NO-induced inhibition of HIF-1alpha accumulation in both cell lines. Exposure to NO was associated with inhibition of mitochondrial electron transport and compensatory glycolysis, which maintained normal cellular ATP content. Succinate, a Krebs cycle intermediate and respiratory chain substrate, restored HIF-1alpha hypoxic induction in the cells, suggesting involvement of mitochondria in regulation of HIF-1alpha accumulation during hypoxia. Regulation of HIF-1alpha by NO is an additional important mechanism by which NO might modulate cellular responses to hypoxia in mammalian cells.
authors.affiliation: Department of Anatomy, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106-4938, USA. fxa5@po.cwru.edu
authors.forename: Faton H
authors.initials: FH
authors.lastname: Agani
authors.forename: Michelle
authors.initials: M
authors.lastname: Puchowicz
authors.forename: Juan Carlos
authors.initials: JC
authors.lastname: Chavez
authors.forename: Paola
authors.initials: P
authors.lastname: Pichiule
authors.forename: Joseph
authors.initials: J
authors.lastname: LaManna
mesh_terms: D000818:Animals; D015687:Cell Hypoxia / Q000502:physiology*; D042967:Electron Transport Complex I; D005978:Glutathione / Q000031:analogs & derivatives* / Q000494:pharmacology; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D008928:Mitochondria / Q000378:metabolism; D009247:NADH, NADPH Oxidoreductases / Q000378:metabolism; D009569:Nitric Oxide / Q000494:pharmacology / Q000502:physiology*; D020030:Nitric Oxide Donors / Q000494:pharmacology; D016716:PC12 Cells; D051381:Rats; D026423:S-Nitroso-N-Acetylpenicillamine / Q000494:pharmacology; D019802:Succinic Acid / Q000494:pharmacology; D014157:Transcription Factors / Q000037:antagonists & inhibitors / Q000378:metabolism*; D014226:Triazenes / Q000494:pharmacology; D014407:Tumor Cells, Cultured; D014527:Uric Acid / Q000494:pharmacology
chemical_list: C105351:1-hydroxy-2-oxo-3,3-bis(2-aminoethyl)-1-triazene; C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D020030:Nitric Oxide Donors; D014157:Transcription Factors; D014226:Triazenes; D014527:Uric Acid; D009569:Nitric Oxide; D026423:S-Nitroso-N-Acetylpenicillamine; C042431:S-ethyl glutathione; D019802:Succinic Acid; D009247:NADH, NADPH Oxidoreductases; D042967:Electron Transport Complex I; D005978:Glutathione