title: Inhibitory PAS domain protein is a negative regulator of hypoxia-inducible gene expression.
abstract: Alteration of gene expression is a crucial component of adaptive responses to hypoxia. These responses are mediated by hypoxia-inducible transcription factors (HIFs). Here we describe an inhibitory PAS (Per/Arnt/Sim) domain protein, IPAS, which is a basic helix-loop-helix (bHLH)/PAS protein structurally related to HIFs. IPAS contains no endogenous transactivation function but demonstrates dominant negative regulation of HIF-mediated control of gene expression. Ectopic expression of IPAS in hepatoma cells selectively impairs induction of genes involved in adaptation to a hypoxic environment, notably the vascular endothelial growth factor (VEGF) gene, and results in retarded tumour growth and tumour vascular density in vivo. In mice, IPAS was predominantly expressed in Purkinje cells of the cerebellum and in corneal epithelium of the eye. Expression of IPAS in the cornea correlates with low levels of expression of the VEGF gene under hypoxic conditions. Application of an IPAS antisense oligonucleotide to the mouse cornea induced angiogenesis under normal oxygen conditions, and demonstrated hypoxia-dependent induction of VEGF gene expression in hypoxic corneal cells. These results indicate a previously unknown mechanism for negative regulation of angiogenesis and maintenance of an avascular phenotype.
authors.affiliation: Department of Cell and Molecular Biology, Medical Nobel Institute, Karolinska Institutet, S-171 77 Stockholm, Sweden.
authors.forename: Y
authors.initials: Y
authors.lastname: Makino
authors.forename: R
authors.initials: R
authors.lastname: Cao
authors.forename: K
authors.initials: K
authors.lastname: Svensson
authors.forename: G
authors.initials: G
authors.lastname: Bertilsson
authors.forename: M
authors.initials: M
authors.lastname: Asman
authors.forename: H
authors.initials: H
authors.lastname: Tanaka
authors.forename: Y
authors.initials: Y
authors.lastname: Cao
authors.forename: A
authors.initials: A
authors.lastname: Berkenstam
authors.forename: L
authors.initials: L
authors.lastname: Poellinger
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D051017:Apoptosis Regulatory Proteins; D051784:Aryl Hydrocarbon Receptor Nuclear Translocator; D019556:COS Cells; D015687:Cell Hypoxia; D002531:Cerebellum / Q000378:metabolism; D003315:Cornea / Q000378:metabolism; D004268:DNA-Binding Proteins; D016228:Endothelial Growth Factors / Q000096:biosynthesis / Q000235:genetics*; D005786:Gene Expression Regulation; D006367:HeLa Cells; D018257:Helix-Loop-Helix Motifs; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D008222:Lymphokines / Q000096:biosynthesis / Q000235:genetics*; D051379:Mice; D008969:Molecular Sequence Data; D018919:Neovascularization, Physiologic / Q000235:genetics / Q000502:physiology; D010100:Oxygen / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D018336:Receptors, Aryl Hydrocarbon; D011993:Recombinant Fusion Proteins / Q000235:genetics; D012097:Repressor Proteins; D017386:Sequence Homology, Amino Acid; D014157:Transcription Factors / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D014407:Tumor Cells, Cultured; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors
chemical_list: C497396:ARNT protein, human; D051017:Apoptosis Regulatory Proteins; C497397:Arnt protein, mouse; D004268:DNA-Binding Proteins; D016228:Endothelial Growth Factors; C497442:HIF1A protein, human; C444643:Hif3a protein, mouse; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D008222:Lymphokines; D018336:Receptors, Aryl Hydrocarbon; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins; D014157:Transcription Factors; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors; D051784:Aryl Hydrocarbon Receptor Nuclear Translocator; D010100:Oxygen