A novel ERβ high throughput microscopy platform for testing endocrine disrupting chemicals

Area of Science:

• Endocrinology
• Molecular Biology
• Environmental Toxicology

Background:

• Estrogen Receptor Beta (ERβ) plays a crucial role in various physiological processes.
• Identifying ERβ-selective compounds and endocrine disruptors (EDCs) is vital for environmental and human health.
• Existing screening tools may not fully capture ERβ-specific activities.

Purpose of the Study:

• To develop and validate an inducible, single-cell biosensor assay for ERβ.
• To screen a panel of reference chemicals for ERβ activity.
• To cross-validate findings using an orthogonal zebrafish model.

Main Methods:

• Developed the GFP-ERβ:PRL-HeLa biosensor assay for high-throughput screening.
• Utilized fluorescence microscopy and mRNA in situ hybridization to measure ERβ binding and transcriptional activity.
• Employed a transgenic zebrafish model for *in vivo* validation of compound activity.

Main Results:

• The GFP-ERβ:PRL-HeLa assay accurately differentiated ERβ-selective ligands from ERα ligands.
• Identified novel ERβ-activating compounds from an EPA reference chemical set.
• Cross-validation in zebrafish confirmed ERβ activity for several compounds, validating the biosensor's utility.

Conclusions:

• The GFP-ERβ:PRL-HeLa assay is a sensitive and effective tool for identifying ERβ EDCs.
• Combining this *in vitro* assay with *in vivo* zebrafish models provides a robust strategy for EDC screening.
• This approach enhances the identification of environmentally relevant ERβ EDCs for understudied nuclear receptors.