IDENTIFICATION OF ERF-1 AS A MEMBER OF THE AP2 TRANSCRIPTION FACTOR FAMILY

The ERF-1 transcription factor was previously shown to be involved in the regulation of estrogen receptor (ER) gene transcription in hormona lly responsive breast and endometrial carcinomas, In this study we sou ght to identify the gene for ERF-1, ERF-1 activates ER gene transcript ion by binding to the imperfect palindrome CCCT-GCGGGG within the prom oter of the ER gene, ERF-1 protein was purified from the ER-positive b reast carcinoma cell line, MCF7, utilizing ion exchange and DNA affini ty chromatography, Peptide sequence analysis was used to isolate a 2,7 kb cDNA clone from an MCF7 cDNA library, This cDNA encodes a protein of 48 kDa previously identified as the AP2 gamma transcription factor, By gel-shift analysis, in vitro synthesized ERF-1 comigrates with MCF 7 native ERF-1 complex and demonstrates identical sequence binding spe cificity as native ERF-1, In addition, AP2 polyclonal antisera supersh ifts both ill vitro synthesized and native ERF-1 complexes, These resu lts show that ERF-1 is a member of the AP2 family of developmentally r egulated transcription factors, Given the central role of ER expressio n in breast carcinoma biology, ERF-1 is likely to regulate expression of a set of genes characteristic of the hormonally-responsive breast c ancer phenotype.