Bracken, C.Whitelaw, M.Peet, D.2007-05-102007-05-102005Journal of Biological Chemistry, 2005; 280(14):14240-142510021-92581083-351Xhttp://hdl.handle.net/2440/27499© 2004 by The American Society for Biochemistry and Molecular BiologyThe hypoxia-inducible factors 1α (HIF-1α) and 2α (HIF-2α) are key regulators of the transcriptional response to low oxygen and are closely related in domain architecture, DNA binding, and activation mechanisms. Despite these similarities, targeted disruption of the HIF- α genes in mice results in distinctly different phenotypes demonstrating nonredundancy of function, although the underlying mechanisms remain unclear. Here we report on the novel and specific interaction of HIF-2α, but not HIF-1α, with the NF- κB essential modulator (NEMO) using immunoprecipitation, mammalian two-hybrid, and in vitro protein interaction assays. Reporter gene assays demonstrate that this interaction specifically enhances normoxic HIF-2α transcriptional activity, independently of the HIF-2α transactivation domain, consistent with a model by which NEMO aids CBP/p300 recruitment to HIF-2α. In contrast, HIF-2α overexpression does not alter NF- κB signaling, suggesting that the functional consequence of the HIF-2α /NEMO interaction is limited to the HIF pathway. The specificity of NEMO for HIF-2α represents one of the few known differential protein-protein interactions between the HIF-α proteins, which has important implications for the activity of HIF-2α and is also the first postulated NF-κ B-independent role for NEMO.enCell LineAnimalsHumansMiceTrans-ActivatorsNuclear ProteinsRecombinant Fusion ProteinsTranscription FactorsOligonucleotides, AntisenseTwo-Hybrid System TechniquesSignal TransductionTranscription, GeneticGene Expression RegulationGenes, ReporterE1A-Associated p300 ProteinI-kappa B KinaseBasic Helix-Loop-Helix Transcription FactorsHypoxia-Inducible Factor 1, alpha SubunitProtein Serine-Threonine KinasesJournal article002005032310.1074/jbc.M4099872000002280955001272-s2.0-1714442046655130Peet, D. [0000-0002-6085-8936]