title: Role of redox signaling in the autonomous proliferative response of endothelial cells to hypoxia.
abstract: 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.
authors.affiliation: Physiologisches Institut, Justus-Liebig-Universität, Aulweg 129, D-35392 Giessen, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Schäfer
authors.forename: C
authors.initials: C
authors.lastname: Schäfer
authors.forename: N
authors.initials: N
authors.lastname: Ewald
authors.forename: H M
authors.initials: HM
authors.lastname: Piper
authors.forename: Th
authors.initials: T
authors.lastname: Noll
mesh_terms: 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
chemical_list: 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