Cloning and expression of a novel dominant-negative-acting estrogen response element-binding protein in the heterogeneous nuclear ribonucleoprotein family

Abstract

Most genera of New World primates exhibit a compensated form of resistance to steroid hormones produced by the adrenal gland, gonads, and kidney. Estrogen resistance in New World primate cells is associated with the relative overexpression of a nonreceptor-related estrogen response element-binding protein (ERE-BP) that competes with estrogen receptor for ERE binding. Using the concatamerized ERE half-site (AGGTCAcag) in DNA affinity chromatography, we purified to homogeneity a 40-42-kDa ERE-BP. The affinity-purified ERE-BP bound specifically to either single- or double-stranded DNA bearing the consensus ERE half-site motif AGGTCA. Four distinct internal tryptic peptides from this protein were generated and shown to exhibit sequence similarity to proteins in the heterogeneous nuclear ribonucleoprotein family. These tryptic peptide fragments were used to generate a series of degenerate oligonucleotides that were successfully employed in isolating a full-length ERE-BP cDNA by polymerase chain reaction. Although a member of a family of proteins generally recognized for their ability to bind single strand RNA, the estrogen resistance-associated protein ERE-BP can effectively bind double strand DNA and competitively squelch estrogen receptor-directed transactivation.