TY - JOUR
T1 - Creation of Fluorescent RXR Antagonists Based on CBTF-EE and Application to a Fluorescence Polarization Binding Assay
AU - Takioku, Maho
AU - Takamura, Yuta
AU - Fujihara, Michiko
AU - Watanabe, Masaki
AU - Yamada, Shoya
AU - Kawasaki, Mayu
AU - Ito, Sohei
AU - Nakano, Shogo
AU - Kakuta, Hiroki
N1 - Funding Information:
This work was partially supported by a Grant-in-Aid from the Japan Society for the Promotion of Science (JSPS) 12J06716 (to S.Y.), grants from the Okayama Foundation for Science and Technology (to H.K.), The Tokyo Biochemical Research Foundation (TBRF) (to H.K.), the Kobayashi Foundation (to H.K.), and scholarship support from the Shoshisha Foundation (to Y.T.)
Publisher Copyright:
© 2021 American Chemical Society.
PY - 2021/6/10
Y1 - 2021/6/10
N2 - 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.
AB - 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.
KW - BODIPY
KW - NBD
KW - RXR
KW - binding assay
KW - fluorescence
KW - fluorescence polarization
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U2 - 10.1021/acsmedchemlett.1c00201
DO - 10.1021/acsmedchemlett.1c00201
M3 - Article
AN - SCOPUS:85106387344
VL - 12
SP - 1024
EP - 1029
JO - ACS Medicinal Chemistry Letters
JF - ACS Medicinal Chemistry Letters
SN - 1948-5875
IS - 6
ER -