title: Transcriptional activity of the 5'-flanking region of the thyroid transcription factor-1 gene in human thyroid cell lines.
abstract: Thyroid transcription factor-1 (TTF-1, NKX2-1) is a homeodomain-containing transcriptional factor that binds to and activates the promoters of thyroid and lung-specific genes, such as thyroglobulin, thyroid peroxidase, and thyroid stimulating hormone receptor. TTF-1 is known to play a key role in the development of the thyroid. However, the precise mechanism of TTF-1 gene transcription in human thyroid cells has not been studied. The expression of transcriptional activity in various lengths of the 5'-flanking region of the human TTF -1 gene was studied in TTF-1 positive and negative human thyroid cell lines. Increased transcriptional activity was observed in thyroid cell lines containing plasmids that coded for a sequence proximal to the transcription start site of exon 1 of the TTF-1 gene. However, we did not observe any difference in promoter activity in the region up to -2.6 kb from the proximal transcription start site of the TTF-1 gene between TTF-1 positive and negative cells. These results suggest that the proximal 5'-flanking region of the human TTF -1 gene does not contain sufficient cis-active regulatory information to direct gene expression in thyroid cells, and that other cis- or trans-acting factors participate in the thyroid specific gene expression of TTF-1.
authors.affiliation: Department of Laboratory Medicine, Osaka University Graduate School of Medicine, Suita, Osaka, Japan.
authors.forename: Hiroya
authors.initials: H
authors.lastname: Yamada
authors.forename: Toru
authors.initials: T
authors.lastname: Takano
authors.forename: Fumio
authors.initials: F
authors.lastname: Matsuzuka
authors.forename: Mikio
authors.initials: M
authors.lastname: Watanabe
authors.forename: Akira
authors.initials: A
authors.lastname: Miyauchi
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Iwatani