Upregulation of NAD(P)H oxidase 1 in hypoxia activates hypoxia-inducible factor 1 via increase in reactive oxygen species.
Hypoxia sensing and related signaling events, including activation of hypoxia-inducible factor 1 (HIF-1), represent key features in cell physiology and lung function. Using cultured A549 cells, we investigated the role of NAD(P)H oxidase 1 (Nox1), suggested to be a subunit of a low-output NAD(P)H oxidase complex, in hypoxia signaling. Nox1 expression was detected on both the mRNA and protein levels. Upregulation of Nox1 mRNA and protein occurred during hypoxia, accompanied by enhanced reactive oxygen species (ROS) generation. A549 cells, which were transfected with a Nox1 expression vector, revealed an increase in ROS generation accompanied by activation of HIF-1-dependent target gene expression (heme oxygenase 1 mRNA, hypoxia-responsive-element reporter gene activity). In A549 cells stably overexpressing Nox1, accumulation of HIF-1alpha in normoxia and an additional increase in hypoxia were noted. Interference with ROS metabolism by the flavoprotein inhibitor diphenylene iodonium (DPI) and catalase inhibited HIF-1 induction. This suggests that H2O2 links Nox1 and HIF-1 activation. We conclude that hypoxic upregulation of Nox1 and subsequently augmented ROS generation may activate HIF-1-dependent pathways.
Goyal
Parag
P
Department of Internal Medicine 2, Klinikstrasse 36, Giessen, Germany.
Weissmann
Norbert
N
Grimminger
Friedrich
F
Hegel
Cornelia
C
Bader
Lucius
L
Rose
Frank
F
Fink
Ludger
L
Ghofrani
Hossein A
HA
Schermuly
Ralph T
RT
Schmidt
Harald H H W
HH
Seeger
Werner
W
Hänze
Jörg
J
D002374:Catalase / Q000494:pharmacology; D015687:Cell Hypoxia; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004847:Epithelial Cells / Q000166:cytology / Q000187:drug effects / Q000201:enzymology*; D006419:Heme Oxygenase (Decyclizing) / Q000235:genetics / Q000378:metabolism; D051547:Heme Oxygenase-1; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D008156:Luciferases / Q000378:metabolism; D008168:Lung / Q000166:cytology / Q000187:drug effects / Q000201:enzymology*; D008565:Membrane Proteins; D009247:NADH, NADPH Oxidoreductases / Q000378:metabolism*; D000074624:NADPH Oxidase 1; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D009861:Onium Compounds / Q000494:pharmacology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D015854:Up-Regulation
D004791:Enzyme Inhibitors; C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D008565:Membrane Proteins; D009861:Onium Compounds; D012333:RNA, Messenger; D017382:Reactive Oxygen Species; D014157:Transcription Factors; C007517:diphenyleneiodonium; D002374:Catalase; D008156:Luciferases; D019001:Nitric Oxide Synthase; C496541:HMOX1 protein, human; D006419:Heme Oxygenase (Decyclizing); D051547:Heme Oxygenase-1; D009247:NADH, NADPH Oxidoreductases; D000074624:NADPH Oxidase 1