Proximal promoter of the surfactant protein D gene: regulatory roles of AP-1, forkhead box, and GT box binding proteins.
Surfactant protein D (SP-D) plays roles in pulmonary host defense and surfactant homeostasis and is increased following lung injury. Because AP-1 proteins regulate cellular responses to diverse environmental stimuli, we hypothesized that the conserved AP-1 motif (at -109) and flanking sequences in the human SP-D promoter contribute to the regulation of SP-D expression. The AP-1 sequence specifically bound to fra-1, junD, and junB in H441 lung adenocarcinoma nuclear extracts. Mutagenesis of the AP-1 motif in a chloramphenicol acetyltransferase reporter construct containing 285 base pairs of upstream sequence nearly abolished promoter activity, and co-transfection of junD significantly increased wild type but not mutant promoter activity. The sequence immediately downstream of the AP-1 element contained a binding site for HNF-3 (FOXA), and simultaneous mutation of this site (fox-d) and an upstream FoxA binding site (-277, fox-u) caused a 4-fold reduction in chloramphenicol acetyltransferase activity. Immediately upstream of the AP-1-binding site, we identified a GT box-containing positive regulatory element. Despite finding regions of limited homology to the thyroid transcription factor 1-binding site, SP-D promoter activity did not require thyroid transcription factor 1. Thus, transcriptional regulation of SP-D gene expression involves complex interactions with ubiquitous and lineage-dependent factors consistent with more generalized roles in innate immunity.
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Departments of Pathology and Immunology and Internal Medicine, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
Crouch
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Rust
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Spaite
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Brody
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D020816:Amino Acid Motifs; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D001665:Binding Sites; D002467:Cell Nucleus / Q000378:metabolism; D015500:Chloramphenicol O-Acetyltransferase / Q000378:metabolism; D018076:DNA, Complementary / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D005809:Genes, Regulator; D006023:Glycoproteins / Q000235:genetics*; D051541:Hepatocyte Nuclear Factor 3-alpha; D006801:Humans; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D009687:Nuclear Proteins / Q000378:metabolism; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D016760:Proto-Oncogene Proteins c-fos / Q000235:genetics / Q000378:metabolism; D037663:Pulmonary Surfactant-Associated Protein D; D011663:Pulmonary Surfactants / Q000235:genetics*; D012689:Sequence Homology, Nucleic Acid; D000074482:Thyroid Nuclear Factor 1; D018808:Transcription Factor AP-1 / Q000235:genetics*; D014157:Transcription Factors / Q000378:metabolism; D014158:Transcription, Genetic; D014162:Transfection; D014407:Tumor Cells, Cultured; D000099169:Fos-Related Antigen 1
D001425:Bacterial Outer Membrane Proteins; D015500:Chloramphenicol O-Acetyltransferase; D018076:DNA, Complementary; D004268:DNA-Binding Proteins; D006023:Glycoproteins; D051541:Hepatocyte Nuclear Factor 3-alpha; D009687:Nuclear Proteins; D016760:Proto-Oncogene Proteins c-fos; D037663:Pulmonary Surfactant-Associated Protein D; D011663:Pulmonary Surfactants; D000074482:Thyroid Nuclear Factor 1; D018808:Transcription Factor AP-1; D014157:Transcription Factors; D000099169:Fos-Related Antigen 1; C496499:FOXA1 protein, human; C000614412:NKX2-1 protein, human