title: Characterization of rabbit SP-B promoter region responsive to downregulation by tumor necrosis factor-alpha.
abstract: Surfactant protein B (SP-B) is essential for the maintenance of biophysical properties and physiological function of pulmonary surfactant. Tumor necrosis factor-alpha (TNF-alpha), an important mediator of lung inflammation, inhibits surfactant phospholipid and surfactant protein synthesis in the lung. In the present study, we investigated the TNF-alpha inhibition of rabbit SP-B promoter activity in a human lung adenocarcinoma cell line (NCI-H441). Deletion experiments indicated that the TNF-alpha response elements are located within -236 bp of SP-B 5'-flanking DNA. The TNF-alpha response region contained binding sites for nuclear factor-kappa B (NF-kappa B), Sp1/Sp3, thyroid transcription factor (TTF)-1, and hepatocyte nuclear factor (HNF)-3 transcription factors. Inhibitors of NF-kappa B activation such as dexamethasone and N-tosyl-L-phenylalanine chloromethyl ketone and mutation of the NF-kappa B element did not reverse TNF-alpha inhibition of SP-B promoter, indicating that TNF-alpha inhibition of SP-B promoter activity occurs independently of NF-kappa B activation. TNF-alpha treatment decreased the binding activities of TTF-1 and HNF-3 elements without altering the nuclear levels of TTF-1 and HNF-3 alpha proteins. Pretreatment of cells with okadaic acid reversed TNF-alpha inhibition of SP-B promoter activity. Taken together these data indicated that in NCI-H441 cells 1) TNF-alpha inhibition of SP-B promoter activity may be caused by decreased binding activities of TTF-1 and HNF-3 elements, 2) the decreased binding activities of TTF-1 and HNF-3 alpha are not due to decreased nuclear levels of the proteins, and 3) okadaic acid-sensitive phosphatases may be involved in mediating TNF-alpha inhibition of SP-B promoter activity.
authors.affiliation: Department of Molecular Biology, University of Texas Health Science Center at Tyler, Tyler, Texas 75708-3154, USA.
authors.forename: K
authors.initials: K
authors.lastname: Berhane
authors.forename: R K
authors.initials: RK
authors.lastname: Margana
authors.forename: V
authors.initials: V
authors.lastname: Boggaram
mesh_terms: D000230:Adenocarcinoma; D000818:Animals; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects*; D051541:Hepatocyte Nuclear Factor 3-alpha; D006801:Humans; D008175:Lung Neoplasms; D016297:Mutagenesis, Site-Directed; D016328:NF-kappa B / Q000378:metabolism; D009687:Nuclear Proteins / Q000378:metabolism; D011033:Podophyllin / Q000031:analogs & derivatives* / Q000378:metabolism; D011034:Podophyllotoxin / Q000031:analogs & derivatives; D011401:Promoter Regions, Genetic; D011510:Proteolipids / Q000235:genetics*; D011663:Pulmonary Surfactants / Q000235:genetics*; D011817:Rabbits; D000074482:Thyroid Nuclear Factor 1; D014157:Transcription Factors / Q000378:metabolism; D014162:Transfection; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
chemical_list: D004268:DNA-Binding Proteins; C496499:FOXA1 protein, human; D051541:Hepatocyte Nuclear Factor 3-alpha; D016328:NF-kappa B; C000614412:NKX2-1 protein, human; D009687:Nuclear Proteins; D011510:Proteolipids; D011663:Pulmonary Surfactants; D000074482:Thyroid Nuclear Factor 1; D014157:Transcription Factors; D014409:Tumor Necrosis Factor-alpha; C003170:mitopodozide; D011033:Podophyllin; D011034:Podophyllotoxin