Transcriptional regulation of the murine surfactant protein-A gene by B-Myb.
Surfactant protein A (SP-A) is selectively synthesized in subsets of cells lining the respiratory epithelium, where its expression is regulated by various transcription factors including thyroid transcription factor-1 (TTF-1). Cell-specific transcription of the mouse SP-A promoter is mediated by binding of TTF-1 at four distinct cis-active sites located in the 5'-flanking region of the gene. Mutation of TTF-1-binding sites (TBE) 1, 3, and 4 in combination markedly decreased transcriptional activity of SP-A promoter-chloramphenicol acetyltransferase constructs containing SP-A gene sequences from -256 to +45. In contrast, the same mutations enhanced transcriptional activity in constructs containing additional 5' SP-A sequences from -399 to +45 suggesting that cis-acting elements within the region -399 to -256 influence effects of TTF-1 on SP-A promoter activity. A consensus Myb-binding site was identified within the region, located at positions -380 to -371 in the mouse gene. Mutation of the Myb-binding site decreased activity of SP-A promoter constructs in MLE-15 cells. MLE-15 cells, a cell line expressing SP-A mRNA, also expressed B-Myb. B-Myb bound to the MBS in the SP-A gene as assessed by electrophoretic mobility shift assay. While co-transfection of HeLa cells with a B-Myb expression plasmid activated the transfected SP-A promoter about 3-fold, co-transfection of B-myb with cyclin A and cdk-2, to enhance phosphorylation of B-Myb, increased transcriptional activity of SP-A constructs approximately 20-fold. Taken together, the data support activation of SP-A gene promoter activity by B-Myb which acts at a cis-acting element in the SP-A gene.
Bruno
M D
MD
Division of Pulmonary Biology, Children's Hospital Research Foundation, Cincinnati, Ohio 45229-3039, USA.
Whitsett
J A
JA
Ross
G F
GF
Korfhagen
T R
TR
D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D018797:Cell Cycle Proteins; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D016384:Consensus Sequence; D004268:DNA-Binding Proteins / Q000378:metabolism*; D005786:Gene Expression Regulation; D006023:Glycoproteins / Q000235:genetics; D006367:HeLa Cells; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009687:Nuclear Proteins / Q000378:metabolism*; D015513:Oncogene Proteins / Q000378:metabolism; D011401:Promoter Regions, Genetic; D011510:Proteolipids / Q000096:biosynthesis / Q000235:genetics*; D037662:Pulmonary Surfactant-Associated Protein A; D037661:Pulmonary Surfactant-Associated Proteins; D011663:Pulmonary Surfactants / Q000096:biosynthesis / Q000235:genetics*; D051381:Rats; D011994:Recombinant Proteins / Q000096:biosynthesis; D012045:Regulatory Sequences, Nucleic Acid; D016415:Sequence Alignment; D012689:Sequence Homology, Nucleic Acid; D013961:Thyroid Gland / Q000378:metabolism; D000074482:Thyroid Nuclear Factor 1; D015534:Trans-Activators / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism*; D014158:Transcription, Genetic; D014162:Transfection
D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D006023:Glycoproteins; C064352:MYBL2 protein, human; C499306:Mybl2 protein, mouse; C000614412:NKX2-1 protein, human; C000614414:Nkx2-1 protein, mouse; C000614416:Nkx2-1 protein, rat; D009687:Nuclear Proteins; D015513:Oncogene Proteins; D011510:Proteolipids; D037662:Pulmonary Surfactant-Associated Protein A; D037661:Pulmonary Surfactant-Associated Proteins; D011663:Pulmonary Surfactants; D011994:Recombinant Proteins; D000074482:Thyroid Nuclear Factor 1; D015534:Trans-Activators; D014157:Transcription Factors