A two-hybrid yeast assay to quantify the effects of xenobiotics on retinoid X receptor-mediated gene expression

Toxicol Lett. 2008 Feb 15;176(3):198-206. doi: 10.1016/j.toxlet.2007.11.006. Epub 2007 Dec 3.

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alitretinoin
  • Dose-Response Relationship, Drug
  • Endocrine Disruptors / chemistry
  • Endocrine Disruptors / toxicity*
  • Gene Expression / drug effects*
  • Plasmids
  • Protein Binding
  • Recombinant Proteins / genetics
  • Recombinant Proteins / metabolism
  • Retinoid X Receptors / genetics*
  • Retinoid X Receptors / metabolism
  • Tretinoin / pharmacology
  • Two-Hybrid System Techniques
  • Xenobiotics / chemistry
  • Xenobiotics / toxicity*
  • Yeasts / drug effects*
  • Yeasts / genetics
  • Yeasts / metabolism
  • beta-Galactosidase / genetics

Substances

  • Endocrine Disruptors
  • Recombinant Proteins
  • Retinoid X Receptors
  • Xenobiotics
  • Alitretinoin
  • Tretinoin
  • beta-Galactosidase