title: Hypoxia-inducible factor 2alpha binds to cobalt in vitro.
abstract: The hypoxia-inducible factor (HIF) activates the expression of genes that contain a hypoxia response element (HRE). The alpha subunit of the HIF transcription factors is degraded by proteasome pathways during normoxia, but stabilized under hypoxic conditions. It has previously been established that cobalt causes accumulation of HIF-2alpha and HIF-1alpha. However, little is known about the mechanism by which cobalt mimics hypoxia and stabilizes these transcription factors. We show here that cobalt binds directly to HIF-2alpha in vitro with a high affinity and in an oxygen-dependent manner. We found that HIF-2alpha, which had been stabilized with a proteasome inhibitor, could bind to cobalt, whereas hypoxia-stabilized HIF-2alpha could not. Mutations within the oxygen-dependent degradation domain of HIF-2alpha prevented cobalt binding and led to accumulation of HIF-2alpha during normoxia. This suggests that transition metal such as iron may play a role in regulation of HIF-2alpha in vivo.
authors.affiliation: Department of Molecular Physiology, Genome Research Institute, University of Cincinnati, 45267-0576, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Yuan
authors.forename: D
authors.initials: D
authors.lastname: Beitner-Johnson
authors.forename: D E
authors.initials: DE
authors.lastname: Millhorn
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins; D001665:Binding Sites; D016466:CHO Cells; D002614:Chelating Agents / Q000378:metabolism; D003035:Cobalt / Q000378:metabolism*; D017124:Conserved Sequence / Q000235:genetics; D006224:Cricetinae; D003546:Cysteine Endopeptidases / Q000378:metabolism; D006207:Half-Life; D006801:Humans; D008969:Molecular Sequence Data; D009097:Multienzyme Complexes / Q000037:antagonists & inhibitors / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D010100:Oxygen / Q000378:metabolism / Q000494:pharmacology; D016716:PC12 Cells; D046988:Proteasome Endopeptidase Complex; D011485:Protein Binding / Q000187:drug effects; D017434:Protein Structure, Tertiary; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000378:metabolism; D016415:Sequence Alignment; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D000099162:Endothelial PAS Domain-Containing Protein 1
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D002614:Chelating Agents; D003035:Cobalt; D003546:Cysteine Endopeptidases; D009097:Multienzyme Complexes; D010100:Oxygen; D046988:Proteasome Endopeptidase Complex; D011993:Recombinant Fusion Proteins; D014157:Transcription Factors; D000099162:Endothelial PAS Domain-Containing Protein 1