title: Development of yeast reporter assay for screening specific ligands of retinoic acid and retinoid X receptor subtypes.
abstract: BACKGROUND
  Retinoic acids are essential for embryonic development, tissue organization, and homeostasis and act via retinoic acid receptors (RARs) that form heterodimers with retinoid X receptors (RXRs). Human RARs and RXRs include the three subtypes α, β, and γ, which have varying distributions and physiological functions among human tissues. Recent reports show that subtype-specific binding of several chemicals to RARs or RXRs may lead to endocrine disruption. To evaluate these ligand-like chemicals, convenient assay systems for each receptor subtype are required.
  
  
  METHODS
  We developed reporter assay yeasts to screen ligands for RXR subtype receptor homodimers. To screen RAR ligands, yeasts were engineered to express RAR subtypes with defective RXRα, which fails to bind to coactivators because of its shortened c-terminus.
  
  
  RESULTS
  These assay yeasts were validated using known RXR- and RAR-specific ligands and subtype-specific responses were clearly shown. Subtype-specific ligand activities of the suspected chemical RAR or RXR ligands o-t-butylphenol, triphenyltin chloride, tributyltin chloride, and 4-nonylphenol were determined.
  
  
  CONCLUSIONS
  The present assay yeasts may be valuable tools for subtype-specific assessments of unidentified environmental ligand chemicals and receptor-specific pharmaceuticals.
authors: Department of Biology, Graduate School of Science, Osaka Prefecture University, Osaka, Japan.
authors: Kazuhiro
authors: K
authors: Shiizaki
authors: Department of Biology, Graduate School of Science, Osaka Prefecture University, Osaka, Japan.
authors: Tomoya
authors: T
authors: Yoshikawa
authors: Department of Biology, Graduate School of Science, Osaka Prefecture University, Osaka, Japan.
authors: Eiji
authors: E
authors: Takada
authors: Department of Biology, Graduate School of Science, Osaka Prefecture University, Osaka, Japan.
authors: Shizuma
authors: S
authors: Hirose
authors: Department of Biology, Graduate School of Science, Osaka Prefecture University, Osaka, Japan.
authors: Sayoko
authors: S
authors: Ito-Harashima
authors: Department of Biology, Graduate School of Science, Osaka Prefecture University, Osaka, Japan.
authors: Masanobu
authors: M
authors: Kawanishi
authors: Department of Biology, Graduate School of Science, Osaka Prefecture University, Osaka, Japan; Department of Life Science, Dongguk University, Seoul, Republic of Korea. Electronic address: yagi-t@riast.osakafu-u.ac.jp.
authors: Takashi
authors: T
authors: Yagi
mesh_terms: D017930:Genes, Reporter / Q000235:genetics; D006801:Humans; D008024:Ligands; D018168:Receptors, Retinoic Acid / Q000378:metabolism*; D047488:Retinoid X Receptors / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D014212:Tretinoin / Q000378:metabolism*
chemical_list: D008024:Ligands; D018168:Receptors, Retinoic Acid; D047488:Retinoid X Receptors; D014212:Tretinoin
keywords: Endocrine disruptors; Reporter assay; Retinoic acid receptor α, β, γ; Retinoid X receptor α, β, γ; Saccharomyces cerevisiae