title: Cobalt inhibits the interaction between hypoxia-inducible factor-alpha and von Hippel-Lindau protein by direct binding to hypoxia-inducible factor-alpha.
abstract: The hypoxia-inducible factor (HIF) activates the expression of genes that contain a hypoxia response element. The alpha-subunits of the HIF transcription factors are degraded by proteasomal pathways during normoxia but are stabilized under hypoxic conditions. The von Hippel-Lindau protein (pVHL) mediates the ubiquitination and rapid degradation of HIF-alpha (including HIF-1alpha and HIF-2alpha). Post-translational hydroxylation of a proline residue in the oxygen-dependent degradation (ODD) domain of HIF-alpha is required for the interaction between HIF and VHL. It has previously been established that cobalt mimics hypoxia and causes accumulation of HIF-1alpha and HIF-2alpha. However, little is known about the mechanism by which this occurs. In an earlier study, we demonstrated that cobalt binds directly to the ODD domain of HIF-2alpha. Here we provide the first evidence that cobalt inhibits pVHL binding to HIF-alpha even when HIF-alpha is hydroxylated. Deletion of 17 amino acids within the ODD domain of HIF-2alpha that are required for pVHL binding prevented the binding of cobalt and stabilized HIF-2alpha during normoxia. These findings show that cobalt mimics hypoxia, at least in part, by occupying the VHL-binding domain of HIF-alpha and thereby preventing the degradation of HIF-alpha.
authors.affiliation: Genome Research Institute, University of Cincinnati, 231 Albert Sabin Way, Cincinnati, OH 45267-0505, USA.
authors.forename: Yong
authors.initials: Y
authors.lastname: Yuan
authors.forename: George
authors.initials: G
authors.lastname: Hilliard
authors.forename: Tsuneo
authors.initials: T
authors.lastname: Ferguson
authors.forename: David E
authors.initials: DE
authors.lastname: Millhorn
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins; D016466:CHO Cells; D003035:Cobalt / Q000494:pharmacology*; D006224:Cricetinae; D003676:Deferoxamine / Q000494:pharmacology; D005998:Glycine / Q000031:analogs & derivatives*; D006900:Hydroxylation; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D008025:Ligases / Q000378:metabolism*; D008969:Molecular Sequence Data; D051381:Rats; D015534:Trans-Activators / Q000737:chemistry / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism*; D025521:Tumor Suppressor Proteins; D044767:Ubiquitin-Protein Ligases; D051794:Von Hippel-Lindau Tumor Suppressor Protein; D000099162:Endothelial PAS Domain-Containing Protein 1
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D003035:Cobalt; D003676:Deferoxamine; D005998:Glycine; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D008025:Ligases; D015534:Trans-Activators; D014157:Transcription Factors; D025521:Tumor Suppressor Proteins; D044767:Ubiquitin-Protein Ligases; D051794:Von Hippel-Lindau Tumor Suppressor Protein; D000099162:Endothelial PAS Domain-Containing Protein 1; C084257:PC 12 ester