title: Phenazine methosulfate decreases HIF-1α accumulation during the exposure of cells to hypoxia.
abstract: In HEK293 cells, exposure to various NAD(P)H oxidants, including phenazine methosulfate (PMS), that non-enzymatically oxidize intracellular NAD(P)H to NAD(P), decreased hypoxia-induced hypoxia-inducible factor 1 (HIF-1α) accumulation. RT-PCR and cycloheximide inhibition experiments indicated that PMS-induced HIF-1α decrease is involved in post-translational degradation during hypoxia. The decrease in HIF-1α caused by PMS was not eliminated by proteasome inhibitor MG132. Moreover, the increase in HIF-1α induced by exposure to MG132 alone in normoxia was diminished by PMS. In contrast, calpastatin peptide, a calpain inhibitor, fully prevented PMS-induced reduction in HIF-1α in hypoxic cells. These data suggest that the decreased stability of HIF-1α induced by PMS is due to the activation by PMS of a protein degradation system that is independent of the ubiquitin-proteasome pathway.
authors.affiliation: Department of Biomedical Laboratory Science, Faculty of Health Sciences, Kyorin University, Miyashita, Hachioji, Tokyo 192-8508, Japan.
authors.forename: Akiko
authors.initials: A
authors.lastname: Yamaki
authors.forename: Haruhiro
authors.initials: H
authors.lastname: Muratsubaki
mesh_terms: D002135:Calcium-Binding Proteins / Q000494:pharmacology; D015687:Cell Hypoxia; D003513:Cycloheximide / Q000494:pharmacology; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D057809:HEK293 Cells; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000235:genetics / Q000378:metabolism*; D007976:Leupeptins / Q000494:pharmacology; D008773:Methylphenazonium Methosulfate / Q000494:pharmacology*; D016877:Oxidants / Q000494:pharmacology*; D010100:Oxygen / Q000494:pharmacology*; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D061988:Proteasome Inhibitors / Q000494:pharmacology; D011499:Protein Processing, Post-Translational / Q000187:drug effects*; D055550:Protein Stability / Q000187:drug effects; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D059748:Proteolysis / Q000187:drug effects; D015398:Signal Transduction / Q000187:drug effects* / Q000235:genetics
chemical_list: D002135:Calcium-Binding Proteins; D015853:Cysteine Proteinase Inhibitors; C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D007976:Leupeptins; D016877:Oxidants; D061988:Proteasome Inhibitors; D011500:Protein Synthesis Inhibitors; D008773:Methylphenazonium Methosulfate; C033668:calpastatin; D003513:Cycloheximide; D046988:Proteasome Endopeptidase Complex; C072553:benzyloxycarbonylleucyl-leucyl-leucine aldehyde; D010100:Oxygen