title: Vitamin C inhibits NO-induced stabilization of HIF-1alpha in HUVECs.
abstract: HIF-1alpha represents the oxygen-regulated sub-unit of the transcription factor HIF-1, which regulates the transcription of numerous genes involved in cellular response to hypoxia and oxidative stress. It is shown here that nitric oxide (NO) induces HIF-1alpha stabilization in human endothelial cells from umbilical cords (HUVECs) under normoxic conditions. HIF-1alpha protein was increased approximately 36-fold after incubation with 500 microM DETA-NO, which releases a steady state NO concentration of roughly one thousandth of the initial concentration of the donor. Loading of the cells with vitamin C counteracted NO-induced HIF-1alpha accumulation. Based on the observations that oxidative and nitrosative stress can influence the activity of the proteasomal system, which is responsible for the non-lysosomal degradation of proteins, among them HIF-1alpha, it was investigated whether NO-induced stabilization of HIF-1alpha might be due to reduced 20S proteasomal activity. This hypothesis could not be proved, because NO concentrations to inhibit 20S proteasomal activity were about one order of magnitude higher than that to inhibit HIF-1alpha degradation.
authors.affiliation: Center of Pathobiochemistry and Genetics, Department of Medical Chemistry, Medical University of Vienna, Austria.
authors.forename: Markus K
authors.initials: MK
authors.lastname: Muellner
authors.forename: Sabine M
authors.initials: SM
authors.lastname: Schreier
authors.forename: Barbara
authors.initials: B
authors.lastname: Schmidbauer
authors.forename: Magdalena
authors.initials: M
authors.lastname: Moser
authors.forename: Peter
authors.initials: P
authors.lastname: Quehenberger
authors.forename: Stylianos
authors.initials: S
authors.lastname: Kapiotis
authors.forename: Hans
authors.initials: H
authors.lastname: Goldenberg
authors.forename: Hilde
authors.initials: H
authors.lastname: Laggner
mesh_terms: D000975:Antioxidants / Q000494:pharmacology*; D001205:Ascorbic Acid / Q000494:pharmacology*; D015687:Cell Hypoxia; D002478:Cells, Cultured / Q000187:drug effects / Q000378:metabolism; D003683:Dehydroascorbic Acid / Q000378:metabolism; D042783:Endothelial Cells / Q000187:drug effects* / Q000378:metabolism; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000378:metabolism*; D007231:Infant, Newborn; D009569:Nitric Oxide / Q000037:antagonists & inhibitors / Q000502:physiology*; D018384:Oxidative Stress; D010100:Oxygen / Q000378:metabolism; D046988:Proteasome Endopeptidase Complex / Q000187:drug effects / Q000378:metabolism; D055550:Protein Stability; D014226:Triazenes / Q000494:pharmacology; D014471:Umbilical Veins
chemical_list: C105351:1-hydroxy-2-oxo-3,3-bis(2-aminoethyl)-1-triazene; D000975:Antioxidants; C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D014226:Triazenes; D009569:Nitric Oxide; D046988:Proteasome Endopeptidase Complex; D001205:Ascorbic Acid; D010100:Oxygen; D003683:Dehydroascorbic Acid