Activation of steroid hormone receptors by metabolism-disrupting chemicals

Abstract

Exposure to metabolism-disrupting chemicals (MDCs), compounds largely belonging to the group of endocrine-disrupting chemicals (EDCs), is associated with metabolic dysfunctions such as dyslipidemia, insulin resistance and hepatic steatosis. Steroid hormone receptors (SHRs) are known targets for MDCs but their regulatory environment in the presence of environmental chemicals remains elusive. Here, we studied the activation and molecular interactions of SHRs exposed to 17 suspected MDCs including pesticides, plasticizers, pharmaceuticals, flame retardants, industrial chemicals and their metabolites by combining in vitro and in silico approaches. We first established and pre-validated reporter gene assays in HepG2 hepatoma cells to assess the activation of estrogen (ER), androgen (AR), glucocorticoid (GR) and progesterone (PR) receptors. Next, using RNA-seq and publicly available protein interaction data, we identified relevant SHR-interacting coregulators expressed in hepatic cells and measured their MDC-dependent interactions with SHRs using the Microarray Assay for Real-time Coregulator-Nuclear receptor Interaction (MARCoNI) technology. Finally, we examined MDC binding to ER and GR using molecular dynamics simulations. These combined approaches lead to identification of MDCs capable of SHR activation at picomolar-to-low micromolar concentrations and paralleled with their ability to induce recruitment of multiple coregulators. MDCs induced distinct SHR-coregulator binding patterns involving multiple coactivators, corepressors and other modulatory proteins. Our results have broadened the test battery to detect MDCs and indicate that the activation of SHRs by MDCs is driven by diverse molecular interactions.