Role of CBP/p300 and SRC-1 in transcriptional regulation of the pulmonary surfactant protein-A (SP-A) gene by thyroid transcription factor-1 (TTF-1).
Surfactant protein-A (SP-A) gene expression is developmentally regulated in fetal lung type II cells and is enhanced by cAMP. cAMP stimulation of SP-A gene expression is mediated by protein kinase A (PKA) phosphorylation of thyroid transcription factor 1 (TTF-1), expressed selectively in developing lung epithelium. In this study, we analyzed roles of CREB-binding protein (CBP) and steroid receptor coactivator-1 (SRC-1) in TTF-1 regulation of SP-A expression. Upon differentiation of human fetal lung in culture, nuclear localization of CBP, SRC-1, and TTF-1 increased in ductular epithelium in association with type II cell differentiation and induction of SP-A expression. In transient transfections, CBP and SRC-1 acted synergistically with TTF-1 to increase SP-A promoter activity. Overexpression of PKA catalytic subunit enhanced hSP-A promoter activation by SRC-1 plus TTF-1. Adenoviral E1A overexpression reduced TTF-1 +/- SRC-1 induction of SP-A promoter activity, suggesting a role of endogenous CBP/p300. TTF-1 interacted with SRC-1 and CBP in vitro. SRC-1 immunodepletion from type II cell nuclear extracts reduced binding to the TTF-1 binding element upstream of SP-A gene. In cultured type II cells, cAMP increased TTF-1 acetylation. This suggests that cAMP-mediated TTF-1 phosphorylation facilitates interaction with CBP and SRC-1, resulting in its hyperacetylation, further enhancing TTF-1 DNA-binding and transcriptional activity.
Pubmed ID: 11713256 RIS Download
Adenoviridae | CREB-Binding Protein | Catalytic Domain | Cell Differentiation | Cell Line | Cells, Cultured | Cyclic AMP | Cyclic AMP-Dependent Protein Kinase Type II | Cyclic AMP-Dependent Protein Kinases | DNA | Electrophoresis, Polyacrylamide Gel | Glutathione Transferase | Histone Acetyltransferases | Humans | Immunoblotting | Immunohistochemistry | Lung | Models, Biological | Nuclear Proteins | Nuclear Receptor Coactivator 1 | Phosphorylation | Plasmids | Promoter Regions, Genetic | Protein Binding | Proteolipids | Pulmonary Alveoli | Pulmonary Surfactant-Associated Protein A | Pulmonary Surfactant-Associated Proteins | Pulmonary Surfactants | Time Factors | Trans-Activators | Transcription Factors | Transcription, Genetic | Transfection