title: Stabilization of wild-type p53 by hypoxia-inducible factor 1alpha.
abstract: Although hypoxia (lack of oxygen in body tissues) is perhaps the most physiological inducer of the wild-type p53 gene, the mechanism of this induction is unknown. Cells may detect low oxygen levels through a haem-containing sensor protein. The hypoxic state can be mimicked by using cobalt chloride and the iron chelator desferrioxamine: like hypoxia, cobalt chloride and desferrioxamine activate hypoxia-inducible factor 1alpha (HIF-1alpha), which stimulates the transcription of several genes that are associated with hypoxia. Here we show that these treatments induce accumulation of wild-type p53 through HIF-1alpha-dependent stabilization of p53 protein. Induction of p53 does not occur in either a mutant hepatoma cell line that is unable to induce HIF-1alpha or embryonic stem cells derived from mice lacking HIF-1beta. HIF-1alpha is found in p53 immunoprecipitates from MCF7 cells that express wild-type p53 and are either hypoxic or have been exposed to desferrioxamine. Similarly, anti-haemagglutinin immunoprecipitates from lysates of normoxic PC3M cells that had been co-transfected with haemagglutinin-tagged HIF-1alpha and wild-type p53 also contain p53. Transfection of normoxic MCF7 cells with HIF-1alpha stimulates a co-transfected p53-dependent reporter plasmid and increases the amount of endogenous p53. Our results suggest that hypoxic induction of transcriptionally active wild-type p53 is achieved as a result of the stabilization of p53 by its association with HIF-1alpha.
authors.affiliation: Department of Cell and Cancer Biology, Medicine Branch, NCI, NIH, Bethesda, Maryland 20892, USA.
authors.forename: W G
authors.initials: WG
authors.lastname: An
authors.forename: M
authors.initials: M
authors.lastname: Kanekal
authors.forename: M C
authors.initials: MC
authors.lastname: Simon
authors.forename: E
authors.initials: E
authors.lastname: Maltepe
authors.forename: M V
authors.initials: MV
authors.lastname: Blagosklonny
authors.forename: L M
authors.initials: LM
authors.lastname: Neckers
mesh_terms: D000818:Animals; D015687:Cell Hypoxia; D003035:Cobalt / Q000494:pharmacology; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D003676:Deferoxamine / Q000494:pharmacology; D051793:Hypoxia-Inducible Factor 1; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D051379:Mice; D009154:Mutation; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors; D014158:Transcription, Genetic; D014162:Transfection; D014407:Tumor Cells, Cultured; D016159:Tumor Suppressor Protein p53 / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*
chemical_list: D004268:DNA-Binding Proteins; C497443:Hif1a protein, mouse; D051793:Hypoxia-Inducible Factor 1; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D009687:Nuclear Proteins; D014157:Transcription Factors; D016159:Tumor Suppressor Protein p53; D003035:Cobalt; C018021:cobaltous chloride; D003676:Deferoxamine