Intermolecular Interactions Identify Ligand-selective Activity Of Estrogen Receptor α /β Dimers

摘要

Estrogen receptor (ER) dimerization is prerequisite for its activation of target gene transcription. Because the two forms of ER, ERα and ERβ , exhibit opposing functions in cell proliferation, the ability of ligands to induce ERα/ β heterodimers vs. their respective ho-modimers is expected to have profound impacts on transcriptional outcomes and cellular growth. However, there is a lack of direct methods to monitor the formation of ERα /β heterodimers in vivo and to distinguish the ability of estrogenic ligands to promote ER homo- vs. heterodimerization. Here, we describe bioluminescence resonance energy transfer (BRET) assays for monitoring the formation of ERα /β heterodimers and their respective homodimers in live cells. We demonstrate that although both partners contribute to heterodimerization, ligand-bound ERα plays a dominant role. Furthermore, a bioactive component was found to induce ERβ/β homodimers, and ERα/ β heterodimers but had minimal activity on ERα/α homodimers, posing a model that compounds promoting ERα /β heterodimer formation might have therapeutic value. Thus, ER homodimer and heterodimer BRET assays are applicable to drug screening for dimer-selective selective ER modulators. Furthermore, this strategy can be used to study other nuclear receptor dimers.