The hypoxia-inducible factor-2alpha is stabilized by oxidative stress involving NOX4.
The hypoxia-inducible factor-2alpha (HIF-2alpha) contributes to the vascular response to hypoxia. Hypoxia inhibits prolyl hydroxylation of the N-terminal transactivation domain (N-TAD), thus preventing binding of the von Hippel-Lindau protein (pVHL) and proteasomal degradation; additionally, hypoxia inhibits asparagyl hydroxylation of the C-TAD, thus diminishing cofactor recruitment. Reactive oxygen species (ROS) derived from NADPH oxidases (NOXs) have been shown to control vascular functions and to promote vascular remodeling. However, whether HIF-2alpha, ROS, and NOXs are linked under such nonhypoxic conditions is unclear. We found that activation of NOX4 by thrombin or H(2)O(2) increased HIF-2alpha protein because of decreased pVHL binding in pulmonary artery smooth muscle cells (PASMCs). Thrombin, H(2)O(2), and NOX4 overexpression increased HIF-2alpha N-TAD and C-TAD activity, which was prevented by ascorbate treatment or mutation of the hydroxylation sites in the TADs. HIF-2alpha also mediated induction of plasminogen activator inhibitor-1 and the proliferative response to thrombin, H(2)O(2), or NOX4 overexpression. Thus, ROS derived from NOX4 in response to thrombin stabilize HIF-2alpha by preventing hydroxylation of the N- and C-TAD, thus allowing formation of transcriptionally active HIF-2alpha, which promotes PASMC proliferation. Together, these findings present the first evidence that HIF-2alpha is critically involved in the ROS-regulated vascular remodeling processes.
Diebold
Isabel
I
Experimental Pediatric Cardiology, German Heart Center Munich, Munich, Germany.
Flügel
Daniela
D
Becht
Sabine
S
Belaiba
Rachida S
RS
Bonello
Steve
S
Hess
John
J
Kietzmann
Thomas
T
Görlach
Agnes
A
D000818:Animals; D001205:Ascorbic Acid / Q000378:metabolism / Q000494:pharmacology; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics / Q000378:metabolism*; D015153:Blotting, Western; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D007501:Iron / Q000378:metabolism; D000074663:NADPH Oxidase 4; D019255:NADPH Oxidases / Q000235:genetics / Q000378:metabolism*; D018384:Oxidative Stress / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D051381:Rats; D017382:Reactive Oxygen Species / Q000378:metabolism; D013917:Thrombin / Q000494:pharmacology; D051794:Von Hippel-Lindau Tumor Suppressor Protein / Q000235:genetics / Q000378:metabolism; D000099162:Endothelial PAS Domain-Containing Protein 1
D001205:Ascorbic Acid; D051792:Basic Helix-Loop-Helix Proteins; D006861:Hydrogen Peroxide; D007501:Iron; D000074663:NADPH Oxidase 4; D019255:NADPH Oxidases; D017382:Reactive Oxygen Species; D013917:Thrombin; D051794:Von Hippel-Lindau Tumor Suppressor Protein; D000099162:Endothelial PAS Domain-Containing Protein 1; C498910:NOX4 protein, human; C497446:VHL protein, human