MOUSE ANDROGEN RECEPTOR GENE CONTAINS A 2ND FUNCTIONAL PROMOTER WHICHIS REGULATED BY DIHYDROTESTOSTERONE

The androgen receptor (AR) is a developmental and tissue-specific tran scription factor which is activated by binding testosterone or dihydro testosterone. Several different methods of transcriptional regulation of the AR have been shown, including regulation by androgens, follicle -stimulating hormone, epidermal growth factor, and the cAMP pathway. i n order to further characterize the transcriptional regulation of the AR, portions of the mouse androgen receptor (mAR) promoter were cloned into the promoterless pBLCAT3 vector and assayed for chloramphenicol acetyltransferase activity. The results indicate that in addition to t he previously characterized promoter (+1) there is a second distinct p romoter located 3' to the first promoter. Amplification of the 5'-end of the AR gene indicates that RNA originating from the second promoter is initiated from 162 and 170 bases downstream from the 5'-most previ ously characterized site. Northern blot analysis indicated that RNA in itiated from the two promoters is differentially expressed in several cell lines and multiple tissues. Androgen ablation by castration showe d that both promoters are controlled by androgens in the kidney. Seque nce analysis revealed that the second promoter does not contain a TATA or CAAT box. Further characterization of this promoter may provide im portant insights into the transcriptional regulation of the androgen r eceptor since previous studies have often included only the first prom oter.