C/EBP-beta mediates iNOS induction by hypoxia in rat pulmonary microvascular smooth muscle cells.
Exposure of rats to 10% O(2) for 4 days caused pulmonary hypertension and induced expression of both inducible nitric oxide synthase (iNOS) and CCAAT box enhancer binding protein-beta (C/EBP-beta) in rat lung. Electrophoretic mobility shift assays (EMSAs) showed that exposure to 1% O(2) increased the C/EBP-beta binding in rat pulmonary microvascular smooth muscle cells (rPSMs). To test the hypothesis that C/EBP-beta participates in hypoxia-induced iNOS expression in rPSMs, a C/EBP motif at -910 bp of rat iNOS promoter was mutated. rPSMs transfected with the rat iNOS promoter and exposed to 1% O(2) for 24 hours had significantly increased wild-type iNOS promoter activity. The hypoxia-induced promoter activity was abolished by the C/EBP motif mutation. Thus, C/EBP-beta mediates, at least in part, hypoxia-induced iNOS expression in rPSMs.
Teng
Xingwu
X
Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA.
Li
Dechun
D
Catravas
John D
JD
Johns
Roger A
RA
D000818:Animals; D022782:CCAAT-Enhancer-Binding Protein-beta / Q000378:metabolism*; D015687:Cell Hypoxia / Q000502:physiology*; D002478:Cells, Cultured; D004790:Enzyme Induction / Q000187:drug effects / Q000502:physiology; D000860:Hypoxia / Q000378:metabolism* / Q000473:pathology; D008168:Lung / Q000098:blood supply / Q000378:metabolism / Q000473:pathology; D008297:Male; D008833:Microcirculation / Q000378:metabolism; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000378:metabolism*; D016297:Mutagenesis, Site-Directed; D019001:Nitric Oxide Synthase / Q000096:biosynthesis* / Q000235:genetics; D052247:Nitric Oxide Synthase Type II; D011401:Promoter Regions, Genetic; D011652:Pulmonary Circulation / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D012045:Regulatory Sequences, Nucleic Acid / Q000502:physiology; D015854:Up-Regulation
D022782:CCAAT-Enhancer-Binding Protein-beta; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496318:Nos2 protein, rat