Functional role of TTF-1 binding sites in bovine thyroglobulin promoter.
We have studied the binding of purified TTF-1 on the bovine thyroglobulin gene promoter. DNase I footprinting experiments revealed three binding sites which corresponded in location to the A, B and C sites found in the rat thyroglobulin promoter. Mutants in the A and C regions showing reduced binding of TTF-1, also exhibited largely decreased promoter activity in transient expression experiments in primary-cultured dog thyrocytes. Two mutants in the B site that exhibited a reduced capacity to bind TTF-1 also displayed a drastically affected transcriptional activity in transient assays. As in the rat, sites A and C only are critical for promoter activity, these results suggest that full occupancy of the B site is required for thyroglobulin promoter activity in the cow only.
Javaux
F
F
IRIBHN, Université Libre de Bruxelles, Brussels, Belgium.
Bertaux
F
F
Donda
A
A
Francis-Lang
H
H
Vassart
G
G
DiLauro
R
R
Christophe
D
D
D000227:Adenine Nucleotides / Q000235:genetics; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites / Q000502:physiology; D002417:Cattle; D002478:Cells, Cultured; D015500:Chloramphenicol O-Acetyltransferase / Q000235:genetics; D003597:Cytosine Nucleotides / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics*; D004285:Dogs; D008969:Molecular Sequence Data; D016296:Mutagenesis; D009687:Nuclear Proteins / Q000737:chemistry / Q000235:genetics*; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D051381:Rats; D013329:Structure-Activity Relationship; D013954:Thyroglobulin / Q000235:genetics*; D013961:Thyroid Gland / Q000166:cytology; D000074482:Thyroid Nuclear Factor 1; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics*
D000227:Adenine Nucleotides; D003597:Cytosine Nucleotides; D004268:DNA-Binding Proteins; C000614416:Nkx2-1 protein, rat; D009687:Nuclear Proteins; D000074482:Thyroid Nuclear Factor 1; D014157:Transcription Factors; D013954:Thyroglobulin; D015500:Chloramphenicol O-Acetyltransferase