title: Accumulation of HIF-1alpha under the influence of nitric oxide.
abstract: The key player for adaptation to reduced oxygen availability is the transcription factor hypoxia-inducible factor 1 (HIF-1), composed of the redox-sensitive HIF-1alpha and the constitutively expressed HIF-1beta subunits. Under normoxic conditions, HIF-1alpha is rapidly degraded, whereas hypoxia, CoCl(2), or desferroxamine promote protein stabilization, thus evoking its transcriptional activity. Because HIF-1 is regulated by reactive oxygen species, investigation of the impact of reactive nitrogen species was intended. By using different nitric oxide (NO) donors, dose- and time-dependent HIF-1alpha accumulation in close correlation with the release of NO from chemically distinct NO donors was established. Intriguingly, small NO concentrations induced a faster but transient HIF-1alpha accumulation than higher doses of the same NO donor. In contrast, NO attenuated up-regulation of HIF-1alpha evoked by CoCl(2) in a concentration- and time-dependent manner, whereas the desferroxamine-elicited HIF-1alpha signal remained unaltered. To demonstrate an autocrine or paracrine signaling function of NO, we overexpressed the inducible NO synthase and used a coculture system of activated macrophages and tubular cells. Expression of the NO synthase induced HIF-1alpha accumulation, which underscored the role of NO as an intracellular activator for HIF-1. In addition, macrophage-derived NO triggered HIF-1alpha up-regulation in LLC-PK(1) target cells, which points to intercellular signaling properties of NO in achieving HIF-1 accumulation. Our results show that NO does not only modulate the HIF-1 response under hypoxic conditions, but it also functions as a HIF-1 inducer. We conclude that accumulation of HIF-1 occurs during hypoxia but also under inflammatory conditions that are characterized by sustained NO formation.
authors.affiliation: University of Erlangen-Nürnberg, Faculty of Medicine, Department of Medicine IV-Experimental Division, and Nikolaus-Fiebiger Center, Clinical Project Group I, Erlangen, Germany.
authors.forename: K B
authors.initials: KB
authors.lastname: Sandau
authors.forename: J
authors.initials: J
authors.lastname: Fandrey
authors.forename: B
authors.initials: B
authors.lastname: Brüne
mesh_terms: D000818:Animals; D001565:Benzoates / Q000494:pharmacology; D015687:Cell Hypoxia; D002460:Cell Line; D003035:Cobalt / Q000494:pharmacology; D018920:Coculture Techniques; D004268:DNA-Binding Proteins / Q000096:biosynthesis* / Q000235:genetics; D003676:Deferoxamine / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects*; D005978:Glutathione / Q000031:analogs & derivatives* / Q000494:pharmacology; D006162:Guanylate Cyclase / Q000037:antagonists & inhibitors; D006834:Hydrazines / Q000494:pharmacology; D051793:Hypoxia-Inducible Factor 1; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D007093:Imidazoles / Q000494:pharmacology; D007249:Inflammation; D007687:Kidney Tubules, Proximal / Q000166:cytology / Q000378:metabolism; D008262:Macrophage Activation; D008264:Macrophages / Q000378:metabolism; D051379:Mice; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000502:physiology*; D020030:Nitric Oxide Donors / Q000494:pharmacology*; D019001:Nitric Oxide Synthase / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II; D009589:Nitrogen Oxides; D009603:Nitroso Compounds / Q000494:pharmacology; D009687:Nuclear Proteins / Q000096:biosynthesis* / Q000235:genetics; D010069:Oxadiazoles / Q000494:pharmacology; D010078:Oxazines / Q000494:pharmacology; D026422:S-Nitrosoglutathione; D013096:Spermine / Q000031:analogs & derivatives / Q000494:pharmacology; D013552:Swine; D014157:Transcription Factors
chemical_list: D001565:Benzoates; D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors; C497443:Hif1a protein, mouse; D006834:Hydrazines; D051793:Hypoxia-Inducible Factor 1; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D007093:Imidazoles; C111257:NS 2028; D020030:Nitric Oxide Donors; D009589:Nitrogen Oxides; D009603:Nitroso Compounds; D009687:Nuclear Proteins; D010069:Oxadiazoles; D010078:Oxazines; D014157:Transcription Factors; C091861:spermine nitric oxide complex; C079393:1,3-dihydroxy-4,4,5,5-tetramethyl-2-(4-carboxyphenyl)tetrahydroimidazole; D013096:Spermine; D009569:Nitric Oxide; D003035:Cobalt; D026422:S-Nitrosoglutathione; C084012:1,1-diethyl-2-hydroxy-2-nitrosohydrazine; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse; D006162:Guanylate Cyclase; C018021:cobaltous chloride; D005978:Glutathione; D003676:Deferoxamine; D019331:NG-Nitroarginine Methyl Ester