Adenosine A2A receptor is a unique angiogenic target of HIF-2alpha in pulmonary endothelial cells.
Hypoxia, through the hypoxia-inducible transcription factors HIF-1alpha and HIF-2alpha (HIFs), induces angiogenesis by up-regulating a common set of angiogenic cytokines. Unlike HIF-1alpha, which regulates a unique set of genes, most genes regulated by HIF-2alpha overlap with those induced by HIF-1alpha. Thus, the unique contribution of HIF-2alpha remains largely obscure. By using adenoviral mutant HIF-1alpha and adenoviral mutant HIF-2alpha constructs, where the HIFs are transcriptionally active under normoxic conditions, we show that HIF-2alpha but not HIF-1alpha regulates adenosine A(2A) receptor in primary cultures of human lung endothelial cells. Further, siRNA knockdown of HIF-2alpha completely inhibits hypoxic induction of A(2A) receptor. Promoter studies show a 2.5-fold induction of luciferase activity with HIF-2alpha cotransfection. Analysis of the A(2A) receptor gene promoter revealed a hypoxia-responsive element in the region between -704 and -595 upstream of the transcription start site. By using a ChIP assay, we demonstrate that HIF-2alpha binding to this region is specific. In addition, we demonstrate that A(2A) receptor has angiogenic potential, as assessed by increases in cell proliferation, cell migration, and tube formation. Additional data show increased expression of A(2A) receptor in human lung tumor cancer samples relative to adjacent normal lung tissue. These data also demonstrate that A(2A) receptor is regulated by hypoxia and HIF-2alpha in human lung endothelial cells but not in mouse-derived endothelial cells.
Ahmad
Aftab
A
Department of Pediatrics, National Jewish Health, Denver, CO 80206, USA. ahmada@njhealth.org
Ahmad
Shama
S
Glover
Louise
L
Miller
Stacy M
SM
Shannon
John M
JM
Guo
Xiaoling
X
Franklin
Wilbur A
WA
Bridges
James P
JP
Schaack
Jerome B
JB
Colgan
Sean P
SP
White
Carl W
CW
D000600:Amino Acids, Dicarboxylic / Q000494:pharmacology; D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D015687:Cell Hypoxia; D002460:Cell Line; D002465:Cell Movement; D049109:Cell Proliferation; D002478:Cells, Cultured; D047369:Chromatin Immunoprecipitation; D042783:Endothelial Cells / Q000166:cytology / Q000378:metabolism / Q000502:physiology*; D015870:Gene Expression / Q000187:drug effects; D006801:Humans; D008156:Luciferases / Q000235:genetics / Q000378:metabolism; D008168:Lung / Q000166:cytology; D008175:Lung Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D051379:Mice; D018919:Neovascularization, Physiologic / Q000502:physiology*; D019408:Platelet Endothelial Cell Adhesion Molecule-1 / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000235:genetics; D034622:RNA Interference; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D043683:Receptors, Adenosine A2 / Q000235:genetics* / Q000378:metabolism; D020218:Response Elements / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics / Q000378:metabolism; D000099162:Endothelial PAS Domain-Containing Protein 1
D000600:Amino Acids, Dicarboxylic; D051792:Basic Helix-Loop-Helix Proteins; D008156:Luciferases; D019408:Platelet Endothelial Cell Adhesion Molecule-1; D012333:RNA, Messenger; D043683:Receptors, Adenosine A2; D042461:Vascular Endothelial Growth Factor A; D000099162:Endothelial PAS Domain-Containing Protein 1; C040947:oxalylglycine