| Literature DB >> 8276142 |
D F Gordon1, B R Haugen, V D Sarapura, A R Nelson, W M Wood, E C Ridgway.
Abstract
TSH beta gene expression is restricted to pituitary thyrotropes. Since Pit-1 is present in these cells, we characterized Pit-1 RNA and protein in thyrotropes, and tested its function in regulating TSH beta promoter activity. We demonstrate that both TtT-97 thyrotropic tumors and pituitaries contain four Pit-1 transcripts of 3.2, 2.6, 2.4, and 1.9 kb, respectively. Only two transcripts of 2.7 and 2.1 kb were detected in alpha TSH cells, a thyrotrope derived cell that no longer expresses TSH beta. Western analysis revealed Pit-1 protein in TtT-97 cells but not in alpha TSH cells. DNase I protection assays localized Pit-1 binding to three areas of the mouse TSH beta promoter. However, basal TSH beta promoter activity was minimally stimulated when alpha TSH cells or TtT-97 thyrotropes were co-transfected with mouse Pit-1 and a mTSH beta luciferase construct. These studies suggest that Pit-1 is not limiting for cell-specific expression of the TSH beta gene in thyrotrope-derived cells and implies that additional thyrotropic factors are likely required.Entities:
Mesh：
Substances：
Year: 1993 PMID： 8276142 DOI： 10.1016/0303-7207(93)90097-4
Source DB: PubMed Journal: Mol Cell Endocrinol ISSN： 0303-7207 Impact factor: 4.102