1. Thyroid receptor activator molecule, TRAM-1, is an androgen receptor coactivator
- Author
-
Jiann An Tan, Susan H. Hall, Peter Petrusz, and Frank S. French
- Subjects
Male ,medicine.medical_specialty ,Blotting, Western ,Biology ,Transfection ,Nuclear Receptor Coactivator 3 ,Transactivation ,Endocrinology ,Nuclear Receptor Coactivator 1 ,Acetyltransferases ,Complementary DNA ,Internal medicine ,Testis ,medicine ,Humans ,Receptor ,Spermatogenesis ,Cells, Cultured ,Glutathione Transferase ,Histone Acetyltransferases ,Oncogene Proteins ,Thyroid hormone receptor ,Activator (genetics) ,DNA-binding domain ,Seminiferous Tubules ,beta-Galactosidase ,Molecular biology ,Immunohistochemistry ,Androgen receptor ,Receptors, Androgen ,Dihydrotestosterone ,Androgens ,Trans-Activators ,medicine.drug ,Plasmids ,Transcription Factors - Abstract
An androgen receptor (AR) interacting protein was isolated from a HeLa cell complementary DNA library by two-hybrid screening in yeast using the AR DNA and ligand binding domains [amino acids (aa) 481-919] as bait. AR binding of the protein in yeast was dependent on the presence of testosterone or dihydrotestosterone (DHT). The isolated protein is identical to thyroid receptor activator molecule TRAM-1 but lacking aa 1-458. TRAM-1 is a steroid receptor coactivator-3 (SRC-3) subtype. In affinity matrix assays, 35S-labeled TRAM-1 bound the GST-AR ligand binding domain (aa 624-919) and GST-AR N-terminal and DNA binding domains (aa 1-660), but not the GST-AR DNA binding domain (aa 544-634) alone. Coexpression of TRAM-1 increased DHT-dependent AR transactivation 5-fold and constitutive activity of AR (aa 1-660) N-terminal and DNA-binding domains increased 9-fold. Full-length TRAM-1 (aa 1-1424) and the partial (aa 459-1424) were AR and GR coactivators as was SRC-1. In human testis, immunostaining of SRC-3 colocalized with AR in nuclei of Sertoli cells and peritubular myoid cells, indicating it could function as an AR coactivator in these cells. SRC-3 was also present in nuclei of spermatogenic cells where AR was not expressed, suggesting it might also be a coactivator with other nuclear receptors that regulate spermatogenesis.
- Published
- 2000