HIF-2alpha regulates glyceraldehyde-3-phosphate dehydrogenase expression in endothelial cells.
Endothelial cells (EC) express both hypoxia inducible factor-1alpha (HIF-1alpha) and -2alpha (HIF-2alpha), yet their roles in the EC hypoxic response are unclear. Hypoxia upregulates the glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase (GAPDH) in EC through a 5' hypoxic regulatory element (HRE). We compared the upregulation of GAPDH in human lung microvascular EC to that in hep3B cells, another cell type known to express both HIF-1alpha and HIF-2alpha. GAPDH mRNA increased to a lesser extent in hypoxic hep3B cells than in EC, yet upregulation occurred through the same HRE that was active in EC. HIF-1alpha protein induction in response to hypoxia was similar in both cell types. In contrast, HIF-2alpha protein levels were upregulated to a greater extent and for a longer period of time by hypoxia in EC than in hep3B cells. Correspondingly, electrophoretic mobility supershift assays showed that, in EC, there was preferential binding of HIF-2alpha to the GAPDH HRE while, in hep3B cells, there was binding of both HIF-1alpha and HIF-2alpha. The preferential binding of HIF-2alpha to the GAPDH HRE in EC may account for their higher level of induction of GAPDH. These findings suggest that cell-specific patterns of HIF-1alpha and HIF-2alpha expression lead to cell-specific gene upregulation during hypoxia.
Graven
Krista K
KK
Department of Medicine, Section of Pulmonary and Critical Care, University of Wisconsin Medical School, 2590 Medical Sciences Center, 1300 University Avenue, Madison, WI 53706, USA. kkg@medicine.wisc.edu <kkg@medicine.wisc.edu>
Bellur
Deepti
D
Klahn
Brian D
BD
Lowrey
Shawna L
SL
Amberger
Ed
E
D001483:Base Sequence; D015687:Cell Hypoxia; D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000032:analysis; D004730:Endothelium, Vascular / Q000201:enzymology*; D004790:Enzyme Induction; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases / Q000096:biosynthesis / Q000235:genetics*; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000096:biosynthesis; D020218:Response Elements; D014157:Transcription Factors / Q000378:metabolism / Q000502:physiology*; D015533:Transcriptional Activation; D014407:Tumor Cells, Cultured
D004268:DNA-Binding Proteins; C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D012333:RNA, Messenger; D014157:Transcription Factors; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases