THE PITUITARY-SPECIFIC REGULATORY GENE GHF1 CONTAINS A MINIMAL CELL TYPE-SPECIFIC PROMOTER CENTERED AROUND ITS TATA BOX

GHF-1 is a pituitary-specific transcription factor responsible for activation of the growth hormone (GH) gene. The GHF1 gene is expressed exclusively in cells of the somatotrophic lineage, and its transcription is extinguished in somatic cell hybrids. The minimal sequences required for differential transcription of GHF1 in GH-expressing and -nonexpressing cell lines and somatic cell hybrids were localized to a 15-bp region surrounding and including its TATA box. This 15-bp fragment acts as a cell type-specific promoter element and is recognized by a transcription factor present in GH-expressing cell lines. Hence, in addition to enhancers and upstream promoter elements, the TATA element (TATA box plus surrounding sequences) can be, in certain cases, an important determinant of cell-type-specific transcription.