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A Multi-Receptor and Multi-Species Assay for Potential Endocrine Disruptor Targets (SLAS meeting)
Citation:
Houck, K., C. LaLone, A. Bone, R. Judson, M. Martin, Dan Villeneuve, G. Ankley, A. Medvedev, AND S. Markarov. A Multi-Receptor and Multi-Species Assay for Potential Endocrine Disruptor Targets (SLAS meeting). Presented at 2017 SLAS meeting, Washington, DC, February 04 - 08, 2017. https://doi.org/10.23645/epacomptox.5181265
Impact/Purpose:
Poster to be presented at SLAS meeting.
Description:
Screening methods for detecting potential endocrine disrupting chemicals rely chiefly on transactivation assays targeting nuclear receptors such as the estrogen (ER) and androgen receptors (AR). These assays are predominately human-based; yet environmental exposure can affect diverse ecological species. Testing against all species of concern is not feasible due to the required magnitude of effort. We describe here a combination of computational analysis and a multiplexed transactivation system to rationally address this problem. Receptor sequence conservation, specifically the ligand-binding domain, was computed across species using the SeqAPASS application (https://seqapass.epa.gov/seqapass/) to identify the likelihood of species susceptibility to chemical exposures. The computed similarities were evaluated in a high-throughput assay system that provides an efficient means of testing these predicted sensitivities using a multiplexed, in vitro assay that simultaneously monitors the modulation of multiple receptors from multiple species. The previously described Attagene Trans Factorial! assay system was modified to focus on a panel of nuclear receptors important for endocrine function and xenobiotic recognition; specifically, ER, AR, thyroid receptor (TR), peroxisome proliferator-activated receptor gamma (PPARg) and pregnane X receptors (PXR). In addition to human, ligand-binding domain sequences for each receptor from some or all of the following species were designed into the assay: mouse (Mus musculus), frog (Xenopus laevis), zebrafish (Danio rerio), chicken (Gallus gallus), and turtle (Chrysemys picta). A set of 189 chemicals enriched by known ligands to the human receptors was evaluated in a single, multiplexed assay in concentration-response for both agonist and antagonist activity. Hierarchical clustering of potency values demonstrated strong coherence of receptor families. Detailed comparisons between species of responses within a receptor family showed moderate to high concordance. ER agonists ranged from 62-84 % concordant for potencies under 50 uM while AR agonists ranged from 85-97%. PPARg showed high concordance between mammalian species, 88%, but was only 56% between mammalian and zebrafish. For chemicals with potencies less than 1 uM, concordances were 97-100% for all receptors except PXR. Concordance also showed a strong positive relationship to ligand-binding domain sequence similarity obtained by SeqAPASS analysis. In combinacombination with SeqAPASS analysis, this approach may provide efficient screening of important receptors in species that may not be conducive to ready extrapolation from other, tested species. This abstract does not reflect EPA policy.
URLs/Downloads:
DOI: A Multi-Receptor and Multi-Species Assay for Potential Endocrine Disruptor Targets (SLAS meeting)
SLAS_HOUCK_ABSTRACT_2017.PDF (PDF, NA pp, 63.329 KB, about PDF)
SLAS_2017_44X44_M.PDF (PDF, NA pp, 576.34 KB, about PDF)