Sensitive image-based chromatin binding assays using inducible ERα to rapidly characterize estrogenic chemicals and mixtures

Adam T Szafran; Maureen G Mancini; Fabio Stossi; Michael A Mancini

doi:10.1016/j.isci.2022.105200

Sensitive image-based chromatin binding assays using inducible ERα to rapidly characterize estrogenic chemicals and mixtures

iScience. 2022 Sep 23;25(10):105200. doi: 10.1016/j.isci.2022.105200. eCollection 2022 Oct 21.

Authors

Adam T Szafran¹, Maureen G Mancini¹, Fabio Stossi^{1

2}, Michael A Mancini^{1

2}

Affiliations

¹ Molecular and Cellular Biology, Baylor College of Medicine, One Baylor Plaza, MS: BCM 130, Houston, TX 77030, USA.
² GCC Center for Advanced Microscopy and Image Informatics, Texas A&M University, Houston, TX, USA.

Abstract

The United States Environmental Protection Agency (EPA) has been pursuing new high throughput in vitro assays to characterize endocrine disrupting chemicals (EDCs) that interact with estrogen receptor signaling. We characterize two new PRL-HeLa cell models expressing either inducible C-terminal (iGFP-ER) or N-terminal (iER-GFP) tagged estrogen receptor-α (ERα) that allows direct visualization of chromatin binding. These models are an order of magnitude more sensitive, detecting 87 - 93% of very weak estrogens tested compared to only 27% by a previous PRL-HeLa variant and compares favorably to the 73% detected by an EPA-developed computational model using in vitro data. Importantly, the chromatin binding assays distinguished agonist- and antagonist-like phenotypes without activity specific assays. Finally, analysis of complex environmentally relevant chemical mixtures demonstrated how chromatin binding data can be used in risk assessment models to predict activity. These new assays should be a useful in vitro tool to screen for estrogenic activity.

Keywords: Biological sciences research methodologies; Endocrinology.

Grants and funding

P30 ES030285/ES/NIEHS NIH HHS/United States