Estrogen Receptor Inducibility of the Human Na⁺/H⁺Exchanger Regulatory Factor/Ezrin-Radixin-Moesin Binding Protein 50 (NHE-RF/EBP50) Gene Involving Multiple Half-Estrogen Response Elements

Abstract

The Na+/H+ exchanger regulatory factor (NHE-RF; also known as ezrin-radixin-moesin binding protein 50) is a primary response gene under estrogen receptor (ER) control that may provide a link between estrogen action and the regulation of cytoskeletal and cell-signaling pathways. These studies were undertaken to define the human NHE-RF genomic regions and regulatory sequences mediating its robust estrogen responsiveness. Screening of a human genomic library yielded NHE-RF clones comprising the full gene, including the 5'-regulatory region and first exon, which were found to contain a large number (13) of consensus half-estrogen response elements (EREs), but to lack palindromic full EREs. Transfection-transactivation assays with wild-type and mutant ERs and reporter gene constructs linked to progressive deletions, or containing mutations, of the 5'-flanking region including a portion of exon I, and electrophoretic mobility and competitive gel shift assays were performed. These demonstrated direct ER interaction with the multiple half-ERE sites and the importance of the one proximal half-ERE and the multiple upstream half-EREs for eliciting the robust transcription activation of the NHE-RF gene by the estrogen-ER complex. Our findings highlight a paradigm for gene regulation via numerous half-ERE sites that expands the range of modes by which DNA recognition sites mediate the actions of this nuclear receptor.

Regulation of G Protein-Coupled Receptor Function by Na+/H+ Exchange Regulatory Factors

“…As noted earlier, NHERF1 possesses an estrogen response element (Ediger et al, 1999(Ediger et al, , 2002. Thus, high correlation between NHERF1 and estrogen receptor expression comes as no surprise (Stemmer-Rachamimov et al, 2001;Cardone et al, 2007;Song et al, 2007;Wheeler et al, 2011).…”

“…Other steroid hormones were without effect, and antiestrogens blocked the stimulatory action of estradiol. Further analysis revealed that although NHERF1 does not possess a canonical estrogen response element, it contains numerous ERE half-sites (TGACC and GGTCA) (Ediger et al, 2002). Subcloning of the 3.5 kilobases of the 5Ј-flanking region, which contains all 13 ERE half-sites, in a CAT reporter and cotransfection with the estrogen receptor ␣ in MDA-MB-231 breast cancer cells displayed a 29-fold stimulation in response to estradiol.…”

Gene expression profiling of breast cell lines identifies potential new basal markers

“…It also contained the ER-responsive gene coding for NHE-RF/EBP50/SLC9A3R1 protein, which inhibits cell migration by scaffolding ERM proteins and regulating their link with the actin cytoskeleton (Ediger et al, 2002). In perfect agreement, this gene is overexpressed in non-invasive vs invasive BCL (Schindelmann et al, 2002).…”

Ezrin-Radixin-Moesin-Binding Phosphoprotein (EBP50), an Estrogen-Inducible Scaffold Protein, Contributes to Biliary Epithelial Cell Proliferation

“…Whereas in vitro experiments have suggested anti-proliferative functions of EBP50, 14 -16 a positive correlation between EBP50 expression, estrogen receptor status, and tumor progression has been found in human breast cancer. 9,10 Of particular interest with respect to biliary pathophysiology, the major regulators of EBP50 expression are estrogens, 4,17 which are known to target the biliary tree, where they modulate the proliferative activities of cholangiocytes. 18 -20 In the present study, we examined the expression of EBP50 and binding partners in the human liver, under normal conditions and in the setting of biliary disorders, ie, in different types of human cholangiopathies and after bile duct ligation (BDL) in rats.…”