title: Subcellular localization and regulation of hypoxia-inducible factor-2alpha in vascular endothelial cells.
abstract: The hypoxia-inducible factors 1alpha (HIF-1alpha) and 2alpha (HIF-2alpha) have extensive structural homology and have been identified as transcription factors that mediate hypoxia-inducible gene expression through hypoxia-responsive element (HRE). They play critical roles not only in normal development, but also in tumor progression. Endothelial cells (EC) express both HIF-1alpha and -2alpha. In this study, we examined the subcellular localization of HIF-1alpha and -2alpha in bovine arterial EC (BAEC) by immunoblotting and immunocytostaining analysis and found that even under normoxic conditions, as with its heterodimeric partner ARNT, HIF-2alpha was stable, and was localized in the nucleus of BAEC differently than HIF-1alpha. HIF-2alpha might be regulated by a different mechanism than HIF-1alpha and might mediate the expression of some EC-specific genes under normoxic conditions. We further found that cardiovascular helix-loop-helix factor (CHF) 2, which had been identified as an ARNT-interacting protein, was expressed in BAEC and suppressed HRE-dependent gene expression both under normoxia and hypoxia. CHF2 might be one of the key regulators of HIF-2alpha-mediated gene expression in normoxic EC.
authors.affiliation: Department of Public Health and Molecular Toxicology, School of Pharmaceutical Sciences, Kitasato University, Tokyo, Japan.
authors.forename: Ryo
authors.initials: R
authors.lastname: Takahashi
authors.forename: Chie
authors.initials: C
authors.lastname: Kobayashi
authors.forename: Yukihiro
authors.initials: Y
authors.lastname: Kondo
authors.forename: Yoshihito
authors.initials: Y
authors.lastname: Nakatani
authors.forename: Ichiro
authors.initials: I
authors.lastname: Kudo
authors.forename: Manabu
authors.initials: M
authors.lastname: Kunimoto
authors.forename: Nobumasa
authors.initials: N
authors.lastname: Imura
authors.forename: Shuntaro
authors.initials: S
authors.lastname: Hara
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001158:Arteries / Q000166:cytology / Q000378:metabolism; D051784:Aryl Hydrocarbon Receptor Nuclear Translocator; D051792:Basic Helix-Loop-Helix Proteins; D002417:Cattle; D015687:Cell Hypoxia / Q000235:genetics; D004268:DNA-Binding Proteins; D004730:Endothelium, Vascular / Q000166:cytology / Q000378:metabolism*; D005786:Gene Expression Regulation; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D008156:Luciferases / Q000378:metabolism; D008969:Molecular Sequence Data; D018336:Receptors, Aryl Hydrocarbon / Q000235:genetics / Q000378:metabolism; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism; D020218:Response Elements / Q000235:genetics; D013347:Subcellular Fractions / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic; D014162:Transfection; D015262:Xenobiotics
chemical_list: D051784:Aryl Hydrocarbon Receptor Nuclear Translocator; D051792:Basic Helix-Loop-Helix Proteins; D004268:DNA-Binding Proteins; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D008156:Luciferases; D018336:Receptors, Aryl Hydrocarbon; D012097:Repressor Proteins; D014157:Transcription Factors; D015262:Xenobiotics; C405694:Hairy, HRT1 protein