Related Experiment Video

Updated: Jun 14, 2025

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

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Resistance of estrogen receptor function to BET bromodomain inhibition is mediated by transcriptional coactivator

Sicong Zhang, Robert G Roeder

    Biorxiv : the Preprint Server for Biology
    |August 30, 2024
    PubMed

    Insights

    Bromodomain inhibition fails to repress estrogen receptor targets because BRD4 activates oncogenes independently of its bromodomains. BET proteins also regulate transcription elongation through bromodomain-independent interactions.

    Area of Science:

    • Molecular Biology
    • Epigenetics
    • Cancer Biology

    Background:

    • Bromodomain and Extra-Terminal Domain (BET) proteins are key epigenetic readers that regulate gene transcription.
    • BET proteins bind to acetylated histones via their bromodomains, typically activating gene expression.

    Purpose of the Study:

    • To investigate the mechanism by which BET proteins regulate oncogenic gene transcription, particularly in the context of estrogen receptor signaling.
    • To determine if BET protein function is solely dependent on its bromodomains or if other mechanisms are involved.

    Main Methods:

    • Analysis of gene expression in response to bromodomain inhibition.
    • Investigating the interaction of BRD4 with estrogen receptor binding sites and the Mediator complex.
    • Profiling of RNA polymerase II (Pol II)-associated factors and elongation factors.

    Main Results:

    • Bromodomain inhibition did not repress key oncogenic targets of the estrogen receptor.
    • BRD4 activates transcription of critical oncogenes independently of its bromodomains by binding to estrogen receptor sites.
    • BRD4 interacts with the Mediator complex, and its disruption reduces BRD4 occupancy at enhancers.
    • BET proteins regulate Pol II interactions with elongation factors (SPT5, SPT6, PAF1 complex) independently of bromodomains, impacting transcription elongation.

    Conclusions:

    • BET proteins possess critical bromodomain-independent functions in regulating oncogenic transcription.
    • BRD4's interaction with the Mediator complex and elongation factors is crucial for its transcriptional activity.
    • These findings suggest novel therapeutic strategies targeting bromodomain-independent BET protein functions.

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