Related Experiment Video

Updated: Oct 13, 2026

Detecting the Ligand-binding Domain Dimerization Activity of Estrogen Receptor Alpha Using the Mammalian Two-Hybrid Assay
09:07

Detecting the Ligand-binding Domain Dimerization Activity of Estrogen Receptor Alpha Using the Mammalian Two-Hybrid Assay

Published on: December 19, 2018

Differential effects of xenoestrogens on coactivator recruitment by estrogen receptor (ER) alpha and ERbeta

E J Routledge1, R White, M G Parker

  • 1Department of Biological Sciences, Brunel University, Uxbridge, Middlesex UB8 3PH, UK. edwin.routledge@brunel.ac.uk

The Journal of Biological Chemistry
|August 31, 2000
PubMed

Insights

Xenoestrogens can alter estrogen receptor (ER) binding to coactivators, influencing gene expression. ERbeta shows a greater ability than ERalpha to recruit coactivators, explaining varied tissue responses to xenoestrogens.

Area of Science:

  • Endocrinology
  • Molecular Biology
  • Environmental Health

Background:

  • Xenoestrogens are environmental compounds mimicking natural estrogens.
  • Their tissue-specific effects may involve alterations in estrogen receptor (ER) structure and coactivator interactions.
  • The precise impact of xenoestrogens on ERalpha and ERbeta behavior post-ligand binding remains unclear.

Purpose of the Study:

  • To investigate how xenoestrogens affect the recruitment of coactivator proteins (TIF2 and SRC-1a) by ERalpha and ERbeta.
  • To compare the binding affinities and coactivator recruitment abilities of ERalpha and ERbeta in the presence of various ligands, including xenoestrogens.
  • To correlate in vitro coactivator recruitment with in vivo reporter gene activity.

Main Methods:

  • In vitro assessment of ERalpha and ERbeta coactivator binding using TIF2 and SRC-1a.
  • Testing a range of ligands: 17beta-estradiol, genistein, diethylstilbestrol, 4-tert-octylphenol, tetrachlorobiphenyl-ol, and bisphenol A.
  • Transient transfection assays in HeLa cells expressing coactivators (SRC-1e, TIF2) to measure reporter gene activity.

Main Results:

  • Ligand-dependent differences were observed in ERalpha and ERbeta coactivator binding, despite similar ligand affinities.
  • ERbeta demonstrated a superior ability to recruit coactivators compared to ERalpha when bound to xenoestrogens.
  • This enhanced coactivator recruitment by ERbeta correlated with increased reporter gene activity in transfected cells.

Conclusions:

  • Ligand-dependent variations in ERalpha and ERbeta coactivator recruitment contribute to the complex, tissue-specific agonistic/antagonistic actions of xenoestrogens.
  • ERbeta's greater propensity to bind coactivators in the presence of xenoestrogens may underlie its distinct cellular responses.
  • Understanding these receptor-coactivator dynamics is crucial for elucidating xenoestrogen mechanisms of action.

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