Identification of the Novel Player δEF1 in Estrogen Transcriptional Cascades

Abstract

Although many genes are regulated by estrogen, very few have been shown to directly bind the estrogen receptor complex. Therefore, transcriptional cascades probably occur in which the estrogen receptor directly binds to a target gene that encodes another transcription factor that subsequently regulates additional genes. Through the use of a differential display assay, a transcription factor has been identified that may be involved in estrogen transcriptional cascades. This report demonstrates that transcription factor ␦EF1 is induced eightfold by estrogen in the chick oviduct. Furthermore, the regulation by estrogen occurs at the transcriptional level and is likely to be a direct effect of the estrogen receptor complex, as it does not require concomitant protein synthesis. A putative binding site was identified in the 5-flanking region of the chick ovalbumin gene identifying it as a possible target gene for regulation by ␦EF1. Characterization of this binding site revealed that ␦EF1 binds to and regulates the chick ovalbumin gene. Thus, a novel regulatory cascade that is triggered by estrogen has been defined.

Interaction between Smad-interacting Protein-1 and the Corepressor C-terminal Binding Protein Is Dispensable for Transcriptional Repression of E-cadherin

“…Activator activity for SIP has not been proven yet but cannot be excluded because analysis of the amino acid sequence reveals proline-rich and acidic amino acid-rich domains. In addition, ␦EF1 can be a transcriptional activator of ovalbumin transcription via binding to a TACCT site and is potentiated by co(over)expression of upstream stimulatory factor 1 (50,51).…”

YY1 binds to regulatory element of chicken lysozyme and ovalbumin promoters

“…In fact, NRE may contain binding sites for both negative and positive regulatory proteins. Sanders et al postulated that dEF1 binds to NRE and SDRE and activates ovalbumin expression in a hormone-dependent manner (Chamberlain and Sanders 1999;Dillner and Sanders 2002). The binding site for YY1 is located just next to the dEF1 binding site in NRE.…”

Negative modulation of the chicken infectious anemia virus promoter by COUP-TF1 and an E box-like element at the transcription start site binding δEF1

“…Incubation of nuclear proteins from LMH cells with the TSP probe resulted in two specific bands, and addition of anti-dEF1 antibody, previously shown to block DNAprotein binding (Chamberlain & Sanders, 1999;Kraus et al, 2003), resulted in loss of band 1, a diminished band 2 and faster migration of band 3 (Fig. 3a, lanes 3 and 4).…”

“…The transcriptional regulator dEF1 is most commonly associated with repression of target genes as well as being part of an oestrogen signalling cascade that activates the chicken ovalbumin gene (Chamberlain & Sanders, 1999;Dillner & Sanders, 2002a, b). It is an important regulator of gene expression during embryonic development and is remarkably conserved between species, with homologues ZEB1 and Zfh-1a in humans and Drosophila, respectively (Akai & Storey, 2003;Comijn et al, 2001;Miyoshi et al, 2004;Postigo, 2003).…”

“…Protein (10 mg) was incubated with poly(dI-dC) (Sigma) in binding buffer (50 mM Tris/ HCl pH 7.6, 50 mM KCl, 10 %, v/v, glycerol, 20 nM ZnSO 4 , 0.5 mM DTT) for 15 min at room temperature, before addition of the labelled probe (100 000-200 000 c.p.m.). For supershift/blocking assays, 2 ml anti-chickendEF1 antibody (a kind gift from Michel Samuels, University of Minnesota) (Chamberlain & Sanders, 1999) or antibody to SIP1 (Santa Cruz Biotechnology), another transcription regulator, were added to the protein/blocking buffer mix and preincubated for 15 min at 37 u C then 15 min at room temperature before addition of the labelled probe. Protein-DNA complexes were resolved on 5 % polyacrylamide gels with 0.56 Tris/borate/EDTA running buffer at 150 V for 2 h, and visualized by autoradiography.…”