Creation of Fluorescent RXR Antagonists Based on CBTF-EE and Application to a Fluorescence Polarization Binding Assay

Maho Takioku, Yuta Takamura, Michiko Fujihara, Masaki Watanabe, Shoya Yamada, Mayu Kawasaki, Sohei Ito, Shogo Nakano, Hiroki Kakuta

Research output: Contribution to journalArticlepeer-review

Abstract

Retinoid X receptor (RXR) ligands often bind in modes in which the carboxy group forms a hydrogen bond inside the ligand-binding pocket (LBP). However, our previously reported RXR antagonist, CBTF-EE (4a), binds with its carboxy group directed outside the LBP and its alkoxy side chain located inside the LBP. Here, we examined the binding modes of 4b and 4c bearing a nitrobenzoxadiazole (NBD) or boron-dipyrromethene (BODIPY) fluorophore, respectively, at the end of the alkoxy chain of 4a. Both compounds function as RXR antagonists. 4c, but not 4b, was available for a fluorescence polarization binding assay, indicating that rotation of BODIPY, but not NBD, is restricted in the bound state. The fluorescence findings, supported by docking simulations, suggest the fluorophores are located outside the LBP, so that the binding mode of 4b and 4c is different from that of 4a. The assay results were highly correlated with those of a [3H]9-cis-retinoic acid assay.

Original languageEnglish
Pages (from-to)1024-1029
Number of pages6
JournalACS Medicinal Chemistry Letters
Volume12
Issue number6
DOIs
Publication statusPublished - Jun 10 2021

Keywords

  • BODIPY
  • NBD
  • RXR
  • binding assay
  • fluorescence
  • fluorescence polarization

ASJC Scopus subject areas

  • Biochemistry
  • Drug Discovery
  • Organic Chemistry

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