FUNCTIONAL INTERACTIONS BETWEEN THE ESTROGEN-RECEPTOR AND THE TRANSCRIPTION ACTIVATOR SP1 REGULATE THE ESTROGEN-DEPENDENT TRANSCRIPTIONAL ACTIVITY OF THE VITELLOGENIN A1 IO PROMOTER
Srb. Demedeiros et al., FUNCTIONAL INTERACTIONS BETWEEN THE ESTROGEN-RECEPTOR AND THE TRANSCRIPTION ACTIVATOR SP1 REGULATE THE ESTROGEN-DEPENDENT TRANSCRIPTIONAL ACTIVITY OF THE VITELLOGENIN A1 IO PROMOTER, The Journal of biological chemistry, 272(29), 1997, pp. 18250-18260
Two distinct, TATA box-containing promoters regulate the transcription
al activity of the Xenopus vitellogenin Al gene. These two promoters a
re of different strength and are separated by 1.8 kilobase pairs of un
translated sequence. Estrogen receptor (ER) and its ligand, 17 beta-es
tradiol, induce the activity of both promoters. The estrogen response
elements (EREs) are located a proximal to the downstream i promoter wh
ile no ERE-like sequences have been identified in the vicinity of the
upstream io promoter. We show here, that transcriptional activity of t
he upstream io promoter is Sp1-dependent. Moreover, we demonstrate tha
t estrogen inducibility of the io promoter results from functional int
eractions between the io bound Sp1 and the ER bound at the proximity o
f i. Functional interactions between Sp1 and ER do not require the pre
sence of a TATA box for transcriptional activation, as is demonstrated
using the acyl-CoA oxidase promoter. The relative positions that ER a
nd Sp1 occupy with respect to the initiation site determines whether t
hese two transcription activators can synergize for transcription init
iation.