Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
2603297 | Toxicology in Vitro | 2007 | 9 Pages |
Abstract
Xenoestrogens can interfere with normal estrogen signaling by competitively binding to the estrogen receptor (ER) and activating transcription of target genes. In this study, we cloned the estrogen receptor alpha (vbERα) and beta 2 (vbERβ2) genes from liver of the indigenous Taiwanese cyprinid fish Varicorhinus barbatulus and tested the direct impact of several xenoestrogens on these ERs. Transcriptional activity of xenoestrogens was measured by the enzymatic activity of estrogen responsive element (ERE)-containing β-galactosidase in a yeast reporter system. The xenoestrogens tested were phenol derivatives, DDT-related substances, phthalic acid esters, and polychlorinated biphenyls, with 17β-estradiol (E2) as a subjective standard. The phenol derivatives [4-nonylphenol (4-NP), 4-t-octylphenol (4-t-OP) and bisphenol A (BPA)] exhibited significant dose-dependent responses in both ligand potency and ligand efficiency. Consistent with yeast assays using human or rainbow trout ERs, we observed a general subtype preference in that vbERα displayed higher relative potencies and efficiencies than vbERβ2, although our assays induced a stronger response for xenoestrogens than did human or trout ERs. Whereas 4-NP and 4-t-OP have similar EC50 values relative to E2 for both ER subtypes, the strong estrogenic response of BPA markedly differentiates vbERα from vbERβ2, suggesting possible species-specific BPA sensitivity. We report that the ameliorative yeast tool is readily applicable for indigenous wildlife studies of the bio-toxic influence of xenoestrogens with wildlife-specific estrogen receptors.
Keywords
BPADDEdi-n-butyl phthalate4-NonylphenolEREPCBsNCBIXenoestrogenONPG1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene5′-Rapid amplification of cDNA ends17β-estradiol4-t-Octylphenol5′-RACEDMSOE1, EstroneEDCs4-NPYESBenzyl butyl phthalateBisphenol APolychlorinated biphenylssynthetic dropoutBBPDDTDimethyl sulfoxideYeast Estrogen Screenestrogen response elementTranscriptional activationThe National Center for Biotechnology InformationEndocrine Disrupting Chemicalspolymerase chain reactionPCRoptical densityLigand efficiencyEstrogen receptor
Related Topics
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Environmental Science
Health, Toxicology and Mutagenesis
Authors
Keng-Yen Fu, Chung-Yuan Chen, Whei-meih Chang,