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.