title: SUMOylation of hypoxia-inducible factor-1alpha reduces its transcriptional activity.
abstract: The hypoxic response of mammalian cells is controlled through a transcriptional pathway that is mediated by the hypoxia-inducible factor (HIF). Here, we show that HIF-1alpha undergoes post-translational modification by the three isoforms of the small ubiquitin-related modifier (SUMO-1, -2 and -3) in vitro in proximity to and within the oxygen-dependent degradation domain (ODDD). SUMO conjugation is promoted in vitro by the E3 SUMO ligase RanBP2/Nup538 and SUMO modification in vivo does not change HIF-1alpha turnover rate. Using cotransfection of siRNA targeted to endogenous HIF-1alpha together with HIF-1alpha siRNA-resistant expression vectors carrying mutations for SUMO modification we demonstrate increased hypoxia-response element-dependent transcriptional activity for SUMO-deficient HIF-1alpha. These results indicate that when HIF-1alpha is conjugated to SUMO its transcriptional activity is decreased and that this is not mediated by a change in the protein's half-life.
authors.affiliation: Institute of Signalling, Developmental Biology and Cancer Research, University of Nice, CNRS UMR 6543, Centre A. Lacassagne, 33 Avenue Valombrose, 06189 Nice, France.
authors.forename: Mélanie A
authors.initials: MA
authors.lastname: Berta
authors.forename: Nathalie
authors.initials: N
authors.lastname: Mazure
authors.forename: Maurice
authors.initials: M
authors.lastname: Hattab
authors.forename: Jacques
authors.initials: J
authors.lastname: Pouysségur
authors.forename: M Christiane
authors.initials: MC
authors.lastname: Brahimi-Horn
mesh_terms: D015536:Down-Regulation / Q000187:drug effects; D005982:Glutathione Transferase / Q000235:genetics; D006367:HeLa Cells; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000235:genetics / Q000378:metabolism*; D016297:Mutagenesis, Site-Directed; D034741:RNA, Small Interfering / Q000494:pharmacology; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D025842:SUMO-1 Protein / Q000235:genetics / Q000378:metabolism*; D025841:Small Ubiquitin-Related Modifier Proteins / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic / Q000187:drug effects
chemical_list: C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D034741:RNA, Small Interfering; D011993:Recombinant Fusion Proteins; D025842:SUMO-1 Protein; C117909:SUMO2 protein, human; D025841:Small Ubiquitin-Related Modifier Proteins; D005982:Glutathione Transferase