Role of redox signaling in the autonomous proliferative response of endothelial cells to hypoxia.
Endothelial cells exhibit an autonomous proliferative response to hypoxia, independent of paracrine effectors. In cultured endothelial cells of porcine aorta, we analyzed the signaling of this response, with a focus on the roles of redox signaling and the MEK/ERK pathway. Transient hypoxia (1 hour) stimulated proliferation by 61+/-4% (n=16; P<0.05 versus control), quantified after 24 hours normoxic postincubation. Hypoxia induced an activation of ERK2 and of NAD(P)H oxidase and a burst of reactive oxygen species (ROS), determined by DCF fluorescence. To inhibit the MEK/ERK pathway, we used PD 98059 (PD, 20 micromol/L); to downregulate NAD(P)H oxidase, we applied p22phox antisense oligonucleotides; and to inhibit mitochondrial ROS generation, we used the ubiquinone derivate mitoQ (MQ, 10 micromol/L). All three inhibitions suppressed the proliferative response: PD inhibited NAD(P)H oxidase activation; p22phox antisense transfection did not inhibit ERK2 activation, but suppressed ROS production; and MQ inhibited ERK2 activation and ROS production. The autonomous proliferative response depends on the MEK/ERK pathway and redox signaling steps upstream and downstream of ERK. Located upstream is ROS generation by mitochondria, downstream is NAD(P)H oxidase.
Schäfer
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M
Physiologisches Institut, Justus-Liebig-Universität, Aulweg 129, D-35392 Giessen, Germany.
Schäfer
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Ewald
N
N
Piper
H M
HM
Noll
Th
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D000818:Animals; D002455:Cell Division; D015687:Cell Hypoxia; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D005419:Flavonoids / Q000494:pharmacology; D016166:Free Radical Scavengers / Q000494:pharmacology; D020935:MAP Kinase Signaling System / Q000187:drug effects; D026901:Membrane Transport Proteins; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D019950:Mitogen-Activated Protein Kinase 1 / Q000037:antagonists & inhibitors / Q000378:metabolism; D009243:NAD / Q000378:metabolism; D009252:NADPH Dehydrogenase / Q000235:genetics; D019255:NADPH Oxidases / Q000502:physiology; D016376:Oligonucleotides, Antisense / Q000235:genetics; D009943:Organophosphorus Compounds / Q000494:pharmacology; D010084:Oxidation-Reduction; D010750:Phosphoproteins / Q000235:genetics; D017382:Reactive Oxygen Species / Q000378:metabolism*; D013552:Swine; D014451:Ubiquinone / Q000494:pharmacology / Q000031:analogs & derivatives
D005419:Flavonoids; D016166:Free Radical Scavengers; D026901:Membrane Transport Proteins; D016376:Oligonucleotides, Antisense; D009943:Organophosphorus Compounds; D010750:Phosphoproteins; D017382:Reactive Oxygen Species; D009243:NAD; D014451:Ubiquinone; C429014:mitoquinone; D019255:NADPH Oxidases; C086986:CYBA protein, human; D009252:NADPH Dehydrogenase; D019950:Mitogen-Activated Protein Kinase 1; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one