Transiently gene-modulated cell reporter for ultrasensitive detection of estrogen-like compounds in tap water.

Abnormal elevation of indispensable steroid hormone estrogens and exposure to exogenous estrogen-like compounds pose adverse health effects to aquatic animals and human alike. These compounds generally display functionally important estrogenic activity even at extremely low picomolar concentrations. In this study we identified one critical but lethal gene (TAF1) that remarkably represses estrogenic activity. This gene is selected as a candidate for genetically modulating an estrogen-responding cell line. To overcome its lethality, instead of adopting a gene knockout strategy, we developed a transient TAF1 depletion strategy using a designed small interfering RNA. By the transient knockdown of TAF1 in the estrogen-responding reporter cell line, the maximum induction signals for endogenous estrogen 17β-estradiol (E2) and environmental estrogens 17α-ethynyl estradiol (EE2) and bisphenol compounds were enhanced by 4.8–13.3 folds. The limit of detection for EE2 is about 8 × 10−15 mol/L. Moreover, by the established method, trace estrogenic activity (14.7–24.2 pg E2 equivalents (E2Eq)/L) can be detected in a portion of Tap water samples. [Display omitted] • By siRNA knockdown of TAF1, the established reporter displays enhanced response to estrogenic compounds by 4.8–13.3 folds. • The TAF1-knockdown enhanced reporter assay can be used to measure estrogenic activity down at the picomolar concentrations. • This improved assay can be applied for analysis of drinking water in a small detection volume (1 mL) with simple pretrement. [ABSTRACT FROM AUTHOR]