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Evaluation of an In Vitro Multi-Receptor and Multi-Species Assay for Potential Endocrine Disruptor Targets (SOT)
Citation:
Houck, K., C. LaLone, R. Judson, M. Martin, Dan Villeneuve, G. Ankley, A. Medvedev, AND S. Markarorav. Evaluation of an In Vitro Multi-Receptor and Multi-Species Assay for Potential Endocrine Disruptor Targets (SOT). Presented at SOT National Meeting, Baltimore, MD, March 12 - 16, 2017.
Impact/Purpose:
abstract for SOT national meeting
Description:
Receptor sequence conservation across species may be a key factor determining susceptibility to potential endocrine disrupting chemicals. Computational approaches that compare receptor sequence similarities (e.g. SeqAPASS; https://seqapass.epa.gov/seqapass/) have been proposed to identify the likelihood of species sensitivities to chemical exposures. Here, we evaluated 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 estrogen receptor (ER), androgen receptor (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 results in the form of potency values demonstrated strong coherence of each receptor family. Detailed comparisons between species of receptor responses within a receptor family showed moderate to high concordance. For example, 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 combination 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.