title: A two-hybrid yeast assay to quantify the effects of xenobiotics on retinoid X receptor-mediated gene expression.
abstract: The aim of this study is to investigate the chemical retinoic acid (RA) disruption at the level of retinoid X receptor (RXR) functioning. This assay makes use of recombined human RXR gene and reporter gene yeast, which specifically expresses beta-galactosidase when incubated with exogenous 9-cis retinoic acid (9-cis RA). Agonistic and antagonistic actions of chemicals including a series of phenols, phthalates, organochlorine pesticides (OCPs) were tested in the absence and presence of 5 x 10(-6)mol/L 9-cis RA, at which maximal beta-galactosidase activity could be induced. The results obtained reveal that some chemicals, e.g., 2-t-butylphenol, 2-isopropylphenol, 2,4-dichlorophenol (2,4-DCP), 3,4-dichlorophenol (3,4-DCP), 4-tert-octylphenol (4-t-OP) and hexachlorobenzene (HCB), are RXR agonists. Especially, bisphenol A (BPA) showed high induction activity to RXR when tested with metabolization. The 20% relative inhibitory concentration (RIC20) values of r-hexachlorocyclohexane (HCH), p,p'-dichlorodiphenyltrichloroethane (p,p'-DDT) and 2,4-DCP with metabolization were lower than 1 x 10(-6)mol/L. These results suggest that BPA, HCH, p,p'-DDT and 2,4-DCP are chemicals that pose a threat to hRXR functioning. Altogether the results of the present study show that the newly developed, yeast two-hybrid assay can be used as a valuable tool for identification and quantification of compounds active in disturbing retinoid homeostasis at the level of RXR.
authors.affiliation: Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, P.O. Box 2871, Beijing 100085, China.
authors.forename: Jian
authors.initials: J
authors.lastname: Li
authors.forename: Mei
authors.initials: M
authors.lastname: Ma
authors.forename: Zijian
authors.initials: Z
authors.lastname: Wang
mesh_terms: D000077556:Alitretinoin; D004305:Dose-Response Relationship, Drug; D052244:Endocrine Disruptors / Q000737:chemistry / Q000633:toxicity*; D015870:Gene Expression / Q000187:drug effects*; D010957:Plasmids; D011485:Protein Binding; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D047488:Retinoid X Receptors / Q000235:genetics* / Q000378:metabolism; D014212:Tretinoin / Q000494:pharmacology; D020798:Two-Hybrid System Techniques; D015262:Xenobiotics / Q000737:chemistry / Q000633:toxicity*; D015003:Yeasts / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D001616:beta-Galactosidase / Q000235:genetics
chemical_list: D052244:Endocrine Disruptors; D011994:Recombinant Proteins; D047488:Retinoid X Receptors; D015262:Xenobiotics; D000077556:Alitretinoin; D014212:Tretinoin; D001616:beta-Galactosidase