Cloning and characterization of the 5'-flanking region of the rat estrogen receptor beta gene.

In the rat, estrogen receptor (ER) beta is preferentially expressed in the ovary and the prostate gland where it is transcriptionally regulated by testosterone. A single 5'-end of rERbeta cDNA was identified in these tissues by the 5'-RACE analysis in the present study. The transcription starting site was predicted at -335 from the translation starting signal (ATG), and a 640bp section of the 5'-flanking region of the gene was cloned. Luciferase reporter assays revealed this region to be responsible for cell-specific promoter activity and successive deletion analyses indicated that only 98bp were sufficient for basic promoter activity as well as for testosterone-dependent transcription. The sequence of the determined region found to demonstrate high homology with the mouse ERbeta promoter with more than 80% identity between positions -1 and -550. The rat region of -30/-110 also showed good homology with 69% identity to corresponding section of the human promoter. Putative cis-acting elements, USF/Arnt and AML1a, were found in common in the promoter regions of three species. The present study thus demonstrated the 5'-flanking region of the rERbeta gene to be a functional promoter.