Induction of endothelial PAS domain protein-1 by hypoxia: characterization and comparison with hypoxia-inducible factor-1alpha.
Hypoxia results in adaptive changes in the transcription of a range of genes including erythropoietin. An important mediator is hypoxia-inducible factor-1 (HIF-1), a DNA binding complex shown to contain at least two basic helix-loop-helix PAS-domain (bHLH-PAS) proteins, HIF-1alpha and aryl hydrocarbon nuclear receptor translocator (ARNT). In response to hypoxia, HIF-1alpha is activated and accumulates rapidly in the cell. Endothelial PAS domain protein 1 (EPAS-1) is a recently identified bHLH-PAS protein with 48% identity to HIF-1alpha, raising the question of its role in responses to hypoxia. We developed specific antibodies and studied expression and regulation of EPAS-1 mRNA and protein across a range of human cell lines. EPAS-1 was widely expressed, and strongly induced by hypoxia at the level of protein but not mRNA. Comparison of the effect of a range of activating and inhibitory stimuli showed striking similarities in the EPAS-1 and HIF-1alpha responses. Although major differences were observed in the abundance of EPAS-1 and HIF-1alpha in different cell types, differences in the inducible response were subtle with EPAS-1 protein being slightly more evident in normoxic and mildly hypoxic cells. Functional studies in a mutant cell line (Ka13) expressing neither HIF-1alpha nor EPAS-1 confirmed that both proteins interact with hypoxically responsive targets, but suggest target specificity with greater EPAS-1 transactivation (relative to HIF-1alpha transactivation) of the VEGF promoter than the LDH-A promoter.
Wiesener
M S
MS
Institute of Molecular Medicine and the Department of Cellular Science, John Radcliffe Hospital, Oxford, UK.
Turley
H
H
Allen
W E
WE
Willam
C
C
Eckardt
K U
KU
Talks
K L
KL
Wood
S M
SM
Gatter
K C
KC
Harris
A L
AL
Pugh
C W
CW
Ratcliffe
P J
PJ
Maxwell
P H
PH
D000818:Animals; D051784:Aryl Hydrocarbon Receptor Nuclear Translocator; D051792:Basic Helix-Loop-Helix Proteins; D016466:CHO Cells; D019556:COS Cells; D015687:Cell Hypoxia / Q000502:physiology*; D002460:Cell Line; D003035:Cobalt / Q000494:pharmacology; D006224:Cricetinae; D003412:Cricetulus; D004268:DNA-Binding Proteins / Q000096:biosynthesis* / Q000235:genetics; D003676:Deferoxamine / Q000494:pharmacology; D016228:Endothelial Growth Factors / Q000235:genetics; D005786:Gene Expression Regulation; D006367:HeLa Cells / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D051793:Hypoxia-Inducible Factor 1; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D007502:Iron Chelating Agents / Q000494:pharmacology; D007770:L-Lactate Dehydrogenase / Q000235:genetics; D008222:Lymphokines / Q000235:genetics; D051379:Mice; D008807:Mice, Inbred BALB C; D009687:Nuclear Proteins / Q000096:biosynthesis* / Q000235:genetics; D009861:Onium Compounds / Q000494:pharmacology; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000096:biosynthesis; D018336:Receptors, Aryl Hydrocarbon; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D015534:Trans-Activators / Q000096:biosynthesis* / Q000235:genetics; D014157:Transcription Factors / Q000378:metabolism; D015533:Transcriptional Activation; D014162:Transfection; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors; D000099162:Endothelial PAS Domain-Containing Protein 1
D051784:Aryl Hydrocarbon Receptor Nuclear Translocator; D051792:Basic Helix-Loop-Helix Proteins; D003035:Cobalt; D004268:DNA-Binding Proteins; D003676:Deferoxamine; D016228:Endothelial Growth Factors; D051793:Hypoxia-Inducible Factor 1; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D007502:Iron Chelating Agents; D007770:L-Lactate Dehydrogenase; D008222:Lymphokines; D009687:Nuclear Proteins; D009861:Onium Compounds; D012333:RNA, Messenger; D018336:Receptors, Aryl Hydrocarbon; D011993:Recombinant Fusion Proteins; D015534:Trans-Activators; D014157:Transcription Factors; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors; D000099162:Endothelial PAS Domain-Containing Protein 1; C497396:ARNT protein, human; C497397:Arnt protein, mouse; C497442:HIF1A protein, human; C497443:Hif1a protein, mouse; C007517:diphenyleneiodonium; C018021:cobaltous chloride