Regulation of heme oxygenase-1 expression in vivo and in vitro in hyperoxic lung injury.
Using hyperoxia as a model of oxidant-induced lung injury in the rat, we explored the regulation of heme oxygenase-1 (HO-1) expression in vivo and in vitro. We demonstrate marked increase of HO-1 messenger ribonucleic acid (mRNA) levels in rat lungs after hyperoxia. Increased HO-1 mRNA expression correlated with increased HO-1 protein and enzyme activity. Immunohistochemical studies of the rat lung after hyperoxia showed increased HO-1 expression in a variety of cell types, including the bronchoalveolar epithelium and interstitial and inflammatory cells. We then examined the regulation of HO-1 expression in vitro after hyperoxia and observed increased HO-1 gene expression in various cultured cells including epithelial cells, fibroblasts, macrophages, and smooth muscle cells. Increased HO-1 mRNA expression correlated with increased HO-1 protein in vitro, and resulted from increased gene transcription and not from increased mRNA stability. We show that transcriptional activation of the HO-1 gene by hyperoxia requires cooperation between the HO-1 promoter and an enhancer fragment located 4 kb upstream from its transcription site. Increased HO-1 gene transcription was associated with increased activator protein-1 (AP-1) binding activity and supershift of the AP-1 complex by antibodies to c-Fos and c-Jun after hyperoxia. Taken together, our data suggest that AP-1 activation may represent one mechanism mediating hyperoxia-induced HO-1 gene transcription.
Lee
P J
PJ
Division of Pulmonary and Critical Care, Johns Hopkins University, School of Medicine, Baltimore, Maryland 21205, USA.
Alam
J
J
Sylvester
S L
SL
Inamdar
N
N
Otterbein
L
L
Choi
A M
AM
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002478:Cells, Cultured / Q000737:chemistry / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D004847:Epithelial Cells; D004848:Epithelium / Q000737:chemistry / Q000502:physiology; D005347:Fibroblasts / Q000737:chemistry / Q000502:physiology; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology; D006419:Heme Oxygenase (Decyclizing) / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D018496:Hyperoxia / Q000503:physiopathology*; D007150:Immunohistochemistry; D007700:Kinetics; D008171:Lung Diseases / Q000139:chemically induced; D016676:Macrophages, Alveolar / Q000737:chemistry / Q000502:physiology; D017737:Macrophages, Peritoneal / Q000737:chemistry / Q000502:physiology; D051379:Mice; D008969:Molecular Sequence Data; D010100:Oxygen / Q000009:adverse effects; D011485:Protein Binding / Q000502:physiology; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D013047:Specific Pathogen-Free Organisms; D018808:Transcription Factor AP-1 / Q000378:metabolism; D014158:Transcription, Genetic / Q000502:physiology
D012333:RNA, Messenger; D018808:Transcription Factor AP-1; D006419:Heme Oxygenase (Decyclizing); D010100:Oxygen