title: Hepatocyte nuclear factor 3 activates transcription of thyroid transcription factor 1 in respiratory epithelial cells.
abstract: Thyroid transcription factor 1 (TTF-1), hepatocyte nuclear factor 3alpha (HNF-3alpha), and HNF-3beta regulate the transcription of genes expressed in the respiratory epithelium. To test whether members of the HNF-3/forkhead family influence TTF-1 gene expression, deletion constructs containing the 5' region of the human TTF-1 gene were transfected into immortalized mouse lung epithelial (MLE) cells. DNase I protection and electrophoretic mobility shift assays identified elements in the 5' region of the TTF-1 gene that bound MLE cell nuclear proteins consistent with the binding of HNF-3 to sites at positions -135 to -124 and -14 to -3. In MLE cells, TTF-1-luciferase reporter constructs were activated by cotransfection with HNF-3beta, activated to a lesser extent by HNF-3alpha, but not activated by HFH-8. HNF-3alpha. and HFH-8 inhibited the activation of TTF-1-luciferase by HNF-3beta. Site-specific mutagenesis of each of the HNF-3 binding sites in the human TTF-1 gene inhibited the binding of MLE cell nuclear proteins and inhibited transactivation of the TTF-1-luciferase constructs after cotransfection with HNF-3beta. Immunohistochemical staining demonstrated that both HNF-3beta and TTF-1 were detected in bronchiolar and alveolar type II cells in the human lung. Modulation of TTF-1 gene expression by members of the HNF-3/forkhead family members may provide a mechanism by which distinct HNF-3/forkhead family members influence respiratory epithelial cell gene expression and cell differentiation.
authors.affiliation: Division of Pulmonary Biology, Children's Hospital Medical Center, Cincinnati, Ohio 45229-3039, USA.
authors.forename: K
authors.initials: K
authors.lastname: Ikeda
authors.forename: J R
authors.initials: JR
authors.lastname: Shaw-White
authors.forename: S E
authors.initials: SE
authors.lastname: Wert
authors.forename: J A
authors.initials: JA
authors.lastname: Whitsett
mesh_terms: D016475:3T3 Cells; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D002460:Cell Line; D016384:Consensus Sequence; D004247:DNA / Q000737:chemistry / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000096:biosynthesis / Q000378:metabolism*; D004847:Epithelial Cells; D004848:Epithelium / Q000378:metabolism; D051541:Hepatocyte Nuclear Factor 3-alpha; D006801:Humans; D007150:Immunohistochemistry; D007231:Infant, Newborn; D008156:Luciferases / Q000096:biosynthesis; D008168:Lung / Q000166:cytology / Q000378:metabolism*; D051379:Mice; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009687:Nuclear Proteins / Q000096:biosynthesis* / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000378:metabolism; D015183:Restriction Mapping; D017384:Sequence Deletion; D000074482:Thyroid Nuclear Factor 1; D014157:Transcription Factors / Q000096:biosynthesis* / Q000378:metabolism*; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D014162:Transfection
chemical_list: D004268:DNA-Binding Proteins; C496499:FOXA1 protein, human; C496500:Foxa1 protein, mouse; D051541:Hepatocyte Nuclear Factor 3-alpha; C000614412:NKX2-1 protein, human; C000614414:Nkx2-1 protein, mouse; D009687:Nuclear Proteins; D011993:Recombinant Fusion Proteins; D000074482:Thyroid Nuclear Factor 1; D014157:Transcription Factors; D004247:DNA; D008156:Luciferases