title: JUN-CCAAT/enhancer-binding protein complexes inhibit surfactant-associated protein B promoter activity.
abstract: The murine surfactant-associated protein B (Sftpb) gene promoter, spanning nucleotides -653 to +42, is composed of functionally distinct proximal and distal regions. Although both regions contain consensus/putative activator protein 1 (AP-1) sites, the distal, but not the proximal, region mediates the inhibition by jun proto-oncogene (JUN) of Sftpb promoter activity. In transient cotransfection assays, JUN inhibited the luciferase reporter activity of plasmid constructs containing Sftpb promoter fragments that lacked the distal putative AP-1 site, indicating that another regulatory motif mediates JUN-dependent inhibition. Electrophoretic mobility shift assays and in silico analyses identified a DNA target sequence (Sftpb nucleotides -339 to -316) and transcription factors that regulate Sftpb promoter activity. The identified sequence contains a CCAAT/enhancer-binding protein (C/EBP) consensus recognition element. Mutation of the site reduced Sftpb promoter activity and sensitivity to inhibition by JUN. Purified recombinant JUN, which did not recognize the -339 to -316 target sequence when added alone, supershifted the mobility of in vitro translated C/EBP-α and C/EBP-β proteins complexed with the identified cis-regulatory element. These findings support the idea that heterodimerization between JUN and C/EBP-α and/or C/EBP-β targets JUN to the Sftpb promoter, thereby mediating its inhibitory regulatory role.
authors.affiliation: Department of Environmental and Occupational Health, Graduate School of Public Health, University of Pittsburgh, PA 15219-3130, USA. Kbein@pitt.edu
authors.forename: Kiflai
authors.initials: K
authors.lastname: Bein
authors.forename: Hayley
authors.initials: H
authors.lastname: Leight
authors.forename: George D
authors.initials: GD
authors.lastname: Leikauf
mesh_terms: D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D022782:CCAAT-Enhancer-Binding Protein-beta / Q000235:genetics / Q000378:metabolism*; D022762:CCAAT-Enhancer-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008969:Molecular Sequence Data; D009154:Mutation; D011401:Promoter Regions, Genetic / Q000235:genetics*; D011485:Protein Binding; D016755:Proto-Oncogene Proteins c-jun / Q000235:genetics / Q000378:metabolism*; D037701:Pulmonary Surfactant-Associated Protein B / Q000235:genetics* / Q000378:metabolism; D012045:Regulatory Sequences, Nucleic Acid; D012689:Sequence Homology, Nucleic Acid; D018808:Transcription Factor AP-1; D014158:Transcription, Genetic; D015533:Transcriptional Activation
chemical_list: D022782:CCAAT-Enhancer-Binding Protein-beta; D022762:CCAAT-Enhancer-Binding Proteins; C530718:CEBPA protein, mouse; C545013:Cebpb protein, mouse; D016755:Proto-Oncogene Proteins c-jun; D037701:Pulmonary Surfactant-Associated Protein B; D018808:Transcription Factor AP-1