Figure 7

Proposed model for regulation of BRCA1 promoter activity. Results suggest that specificity proteins (Sps) contribute to basal and estrogen (E2)-dependent transactivation of the BRCA1 promoter. The Sp-binding region is a target site for multiple Sps, including Sp1, Sp3, and Sp4. However, our data document increased recruitment of Sp1 and Sp4, but not Sp3, in response to E2. We also document the constitutive presence of cAMP response element (CRE)-binding protein (CREB) at the CRE site. Arrows indicate potential interactions of Sp and CREB factors with a p300/estrogen receptor (ER)-α transcription complex bound to an activator protein (AP)-1 (Jun/Fos) domain [33] harbored in the BRCA1 promoter. The TRANSFAC/Match transcription factor database [56] was used to map the Sp, AP-1, and CRE sites.