HIF-1-dependent transcriptional activity is required for oxygen-mediated HIF-1alpha degradation.
Hypoxia-inducible factor-1alpha (HIF-1alpha) plays a central role in oxygen homeostasis. In normoxia, HIF-1alpha is a short lived protein, whereas hypoxia rapidly increases HIF-1alpha protein levels by relaxing its ubiquitin-proteasome-dependent degradation. In this study, we show that the p42/p44 MAP kinase cascade, known to phosphorylate HIF-1alpha, does not modulate the degradation/stabilization profile of HIF-1alpha. However, we present evidence that the rate of HIF-1alpha degradation depends on the duration of hypoxic stress. We demonstrate that degradation of HIF-1alpha is suppressed by: (i) inhibiting general transcription with actinomycin D or (ii) specifically blocking HIF-1-dependent transcriptional activity. In keeping with these findings, we postulate that HIF-1alpha is targetted to the proteasome via a HIF-1alpha proteasome targetting factor (HPTF) which expression is directly under the control of HIF-1-mediated transcriptional activity. Although HPTF is not yet molecularly identified, it is clearly distinct from the von Hippel-Lindau protein (pVHL).
Berra
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Institute of Signaling, Developmental Biology and Cancer Research, CNRS-UMR 6543, Centre Antoine Lacassagne, 33 Avenue Valombrose, 06189 Nice, France. berra@unice.fr
Richard
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Gothié
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Pouysségur
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D015687:Cell Hypoxia; D003546:Cysteine Endopeptidases / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism*; D003609:Dactinomycin / Q000494:pharmacology; D006367:HeLa Cells; D006801:Humans; D051793:Hypoxia-Inducible Factor 1; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D015151:Immunoblotting; D008025:Ligases; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D009097:Multienzyme Complexes / Q000378:metabolism; D009687:Nuclear Proteins / Q000378:metabolism*; D019384:Nucleic Acid Synthesis Inhibitors / Q000494:pharmacology; D010100:Oxygen / Q000378:metabolism*; D010766:Phosphorylation; D011233:Precipitin Tests; D046988:Proteasome Endopeptidase Complex; D011506:Proteins / Q000378:metabolism; D012333:RNA, Messenger / Q000096:biosynthesis; D014157:Transcription Factors / Q000378:metabolism*; D025521:Tumor Suppressor Proteins; D044767:Ubiquitin-Protein Ligases; D051794:Von Hippel-Lindau Tumor Suppressor Protein
D004268:DNA-Binding Proteins; C497442:HIF1A protein, human; D051793:Hypoxia-Inducible Factor 1; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D009097:Multienzyme Complexes; D009687:Nuclear Proteins; D019384:Nucleic Acid Synthesis Inhibitors; D011506:Proteins; D012333:RNA, Messenger; D014157:Transcription Factors; D025521:Tumor Suppressor Proteins; D003609:Dactinomycin; D044767:Ubiquitin-Protein Ligases; D051794:Von Hippel-Lindau Tumor Suppressor Protein; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D003546:Cysteine Endopeptidases; D046988:Proteasome Endopeptidase Complex; D008025:Ligases; C497446:VHL protein, human; D010100:Oxygen