Protein kinase A activation of the surfactant protein B gene is mediated by phosphorylation of thyroid transcription factor 1.
Thyroid transcription factor 1 (TTF-1) is a homeodomain-containing nuclear transcription factor expressed in epithelial cells of the lung and thyroid. TTF-1 binds to and activates the transcription of genes expressed selectively in the respiratory epithelium including pulmonary surfactant A, B, C and Clara cell secretory protein. Transfection with a plasmid encoding the cyclic AMP-dependent protein kinase (protein kinase A; PKA) catalytic subunit, Cat-beta, stimulated the phosphorylation of a TTF-1-flag fusion protein 6-7-fold in H441 pulmonary adenocarcinoma cells. Recombinant TTF-1 was phosphorylated by purified PKA catalytic subunit in the presence of [gamma-32P]ATP. PKA catalytic subunit family members, Cat-alpha and Cat-beta, markedly enhanced the transcriptional activation of surfactant B gene promoters by TTF-1 in vitro. Peptide mapping was used to identify a PKA phosphorylation site at the NH2 terminus of TTF-1. A 17-amino acid synthetic peptide comprising this site completely inhibited the PKA-dependent phosphorylation of TTF-1 in vitro. A substitution mutation of TTF-1 (Thr9 two head right arrow Ala) abolished phosphorylation by PKA and reduced transactivation of the surfactant B gene promoter. Transfection with a plasmid encoding the cAMP regulatory element binding factor inhibited transcriptional activity of the surfactant protein B gene promoter. Phosphorylation of TTF-1 mediates PKA-dependent activation of surfactant protein B gene transcription.
Yan
C
C
Children's Hospital Medical Center, Divisions of Neonatology and Pulmonary Biology, The Children's Hospital Research Foundations, Cincinnati, Ohio 45229-3039, USA.
Whitsett
J A
JA
D000409:Alanine / Q000235:genetics; D002384:Catalysis; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism; D004848:Epithelium / Q000378:metabolism; D006367:HeLa Cells; D051541:Hepatocyte Nuclear Factor 3-alpha; D051542:Hepatocyte Nuclear Factor 3-beta; D018398:Homeodomain Proteins / Q000378:metabolism*; D006801:Humans; D008168:Lung / Q000166:cytology / Q000378:metabolism; D009154:Mutation; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D011401:Promoter Regions, Genetic; D011487:Protein Conformation; D011493:Protein Kinase C / Q000378:metabolism; D011510:Proteolipids / Q000235:genetics*; D011663:Pulmonary Surfactants / Q000235:genetics*; D013912:Threonine / Q000235:genetics; D000074482:Thyroid Nuclear Factor 1; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014162:Transfection; D014407:Tumor Cells, Cultured
D017362:Cyclic AMP Response Element-Binding Protein; D004268:DNA-Binding Proteins; C496499:FOXA1 protein, human; C496502:FOXA2 protein, human; D051541:Hepatocyte Nuclear Factor 3-alpha; D018398:Homeodomain Proteins; C000614412:NKX2-1 protein, human; D009687:Nuclear Proteins; D011510:Proteolipids; D011663:Pulmonary Surfactants; D000074482:Thyroid Nuclear Factor 1; D014157:Transcription Factors; D051542:Hepatocyte Nuclear Factor 3-beta; D013912:Threonine; D017868:Cyclic AMP-Dependent Protein Kinases; D011493:Protein Kinase C; D000409:Alanine