The Effect of Structural Diversity on Ligand Specificity and Resulting Signaling Differences of Estrogen Receptor α

High mobility of the H9-H10 loop induced by DES is correlated with the significant up-regulation of specific gene expression

2019 Study Abstract

Numerous chemicals have been reported to exert estrogen-like endocrine disrupting effects via a receptor binding mechanism that directly interacts with the ligand binding domain (LBD) of estrogen receptor α (ERα). However, not only their binding affinities to ERα but also their interference in specific cell and tissue functions are clearly different. In this regard, significant regulation differences among three representative estrogenic chemicals (diethylstilbestrol (DES), bisphenol A (BPA) and diarylpropionitrile (DPN)), well-known ERα agonists with very similar structures, have been observed. Molecular dynamics (MD) simulation is used to explore the underlying mechanism of different regulation effect induced by the similar estrogen-like chemicals. DES induced 12 Å motion of the H9-H10 loop markedly expands the negative electrostatic potential surface of the AF-2 domain, which is consistent with the over-regulation effect of the agonist. In comparison, the 3 Å motion induced by BPA and DPN corresponds to the low-regulation effect of the chemicals. Cross-correlation analysis indicates that the different ERα motions and resulting surface feature of AF-2 domain is brought by the distinguished binding modes of the agonists. Moreover, only hydrophobic DES with estrogen-like size and flexibility has high binding affinity of -23.47 kcal/mol binding free energy. Both the hydrophilic group in DPN and the small molecular size of BPA dramatically decrease the agonist binding ability, and their binding free energies are only -12.43 kcal/mol and -11.82 kcal/mol, respectively. Our study demonstrates that similar chemicals interact differently with ERα and induce different allosteric effects, which explains the observed regulation diversity.

Reference

  • The Effect of Structural Diversity on Ligand Specificity and Resulting Signaling Differences of Estrogen Receptor α, Chemical Research in Toxicology, NCBI PubMed PMID: 30924335.
DES DIETHYLSTILBESTROL RESOURCES

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