Identification of receptors for eight endocrine disrupting chemicals and their underlying mechanisms using zebrafish as a model organism.

ABSTRACT

Herein, eight common endocrine disrupting chemicals (EDCs) were exposed to zebrafish (Danio rerio) to investigate the relationship between different EDCs and their activated estrogen receptors. Under acute exposure, we identified five major malformation types whose incidence and deformity modes differed among EDCs. Luciferase analysis divided the EDC receptors into four categories (i) triclosan (TCS), 17ß-estradiol (E2) and estriol (E3) mainly activated GPER expression; (ii) bisphenol A (BPA), p-(tert-octyl) phenol (POP), 17α-ethynylestradiol (EE2), E2 and E3 activated ERß expression; (iii) E2 and E3 acted on both GPER and ERß; and (iv) estrone (E1) and 9,9-bis(4-hydroxyphenyl)fluorene (BHPF) had little effect on the two receptors. In vivo immunofluorescence experiments on 96-hpf larvae provided evidence that TCS and POP acted on GPER and ERß, respectively, while E2 acted on the two receptors simultaneously. Luciferase activities in the promoter regions of gper (-986 to -488) and erß (-1998 to -1496) were higher than those in other regions, identifying these key regions as targets for transcription activity. TCS promoted GPER expression by acting on the JUND transcription factor, while POP promoted ERß expression by activating the Foxl1 transcription factor. In contrast, E2 mainly regulated transcription of GPER and ERß by Arid3a. These findings provide compelling evidence that different EDCs possess varying estrogen receptors, leading to differential regulatory pathways and abnormality symptoms. These results offer an experimental strategy and fundamental information to assess the molecular mechanisms of EDC-induced estrogen effects.