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Miura K, Fujihara M, Watanabe M, Takamura Y, Kawasaki M, Nakano S, Kakuta H. Direct evaluation of polarity of the ligand binding pocket in retinoid X receptor using a fluorescent solvatochromic agonist. Bioorg Med Chem Lett 2023; 96:129536. [PMID: 37913851 DOI: 10.1016/j.bmcl.2023.129536] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2023] [Revised: 10/03/2023] [Accepted: 10/22/2023] [Indexed: 11/03/2023]
Abstract
High selectivity of small-molecule drug candidates for their target molecule is important to minimize potential side effects. One factor that contributes to the selectivity is the internal polarity of the ligand-binding pocket (LBP) in the target molecule, but this is difficult to measure. Here, we first confirmed that the retinoid X receptor (RXR) agonist 6-(ethyl(1-isobutyl-2-oxo-4-(trifluoromethyl)-1,2-dihydroquinolin-7-yl)amino)nicotinic acid (NEt-iFQ, 1) exhibits fluorescence solvatochromism, i.e., its Stokes shift depends on the polarity of the solvent, and then we utilized this property to directly measure the internal polarity of the RXRα-LBP. The Stokes shift of 1 when bound to the RXRα-LBP corresponded to that of 1 in chloroform solution. This finding is expected to be helpful for designing RXR-selective ligands. A similar approach should be appliable to evaluate the internal polarity of the LBPs of other receptors.
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Affiliation(s)
- Kizuku Miura
- Faculty of Pharmaceutical Sciences, Okayama University, 1-1-1, Tsushima-naka, Kita-ku Okayama 700-8530, Japan
| | - Michiko Fujihara
- Division of Pharmaceutical Sciences, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 1-1-1, Tsushima-naka, Kita-ku Okayama 700-8530, Japan; Department of Liberal Arts, The Open University of Japan, 2-11 Wakaba, Mihama-ku, Chiba 261- 8586, Japan
| | - Masaki Watanabe
- Division of Pharmaceutical Sciences, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 1-1-1, Tsushima-naka, Kita-ku Okayama 700-8530, Japan
| | - Yuta Takamura
- Division of Pharmaceutical Sciences, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 1-1-1, Tsushima-naka, Kita-ku Okayama 700-8530, Japan
| | - Mayu Kawasaki
- Graduate School of Integrated Pharmaceutical and Nutritional Sciences, University of Shizuoka, 52- 1 Yada, Suruga-ku, Shizuoka 422-8526, Japan
| | - Shogo Nakano
- Graduate School of Integrated Pharmaceutical and Nutritional Sciences, University of Shizuoka, 52- 1 Yada, Suruga-ku, Shizuoka 422-8526, Japan
| | - Hiroki Kakuta
- Division of Pharmaceutical Sciences, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 1-1-1, Tsushima-naka, Kita-ku Okayama 700-8530, Japan.
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2
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Kawasaki M, Motoyama T, Yamada S, Watanabe M, Fujihara M, Kambe A, Nakano S, Kakuta H, Ito S. Ligand Screening System for the RXRα Heterodimer Using the Fluorescence RXR Agonist CU-6PMN. ACS Med Chem Lett 2023; 14:291-296. [PMID: 36923911 PMCID: PMC10009790 DOI: 10.1021/acsmedchemlett.2c00509] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2022] [Accepted: 02/15/2023] [Indexed: 02/22/2023] Open
Abstract
Retinoid X receptor (RXR), a nuclear receptor (NR) that regulates transcription of target genes in a ligand binding-dependent manner, is of interest as a drug target. RXR agonists have been developed as therapeutic agents for cutaneous invasive T-cell lymphoma (e.g., bexarotene (1)) and investigated as potential anti-inflammatory agents. Screening systems for the binding of RXR alone have been reported. However, although RXRs function as RXR heterodimers, information on systems to evaluate the differential binding of RXR agonists as RXR heterodimers has not been available until recently. Here we show that the fluorescent RXR agonist CU-6PMN (3), designed by our group, can be useful for assessing RXR binding to PPARγ/RXRα, and that the binding data differ from those of RXRα alone. This screening method opens a new avenue for binding assays for RXR heterodimers.
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Affiliation(s)
- Mayu Kawasaki
- Graduate
School of Integrated Pharmaceutical and Nutritional Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka 422-8526, Japan
| | - Tomoharu Motoyama
- Graduate
School of Integrated Pharmaceutical and Nutritional Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka 422-8526, Japan
| | - Shoya Yamada
- Division
of Pharmaceutical Sciences, Okayama University
Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 1-1-1, Tsushima-naka, Kita-ku, Okayama 700-8530, Japan
| | - Masaki Watanabe
- Division
of Pharmaceutical Sciences, Okayama University
Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 1-1-1, Tsushima-naka, Kita-ku, Okayama 700-8530, Japan
| | - Michiko Fujihara
- Division
of Pharmaceutical Sciences, Okayama University
Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 1-1-1, Tsushima-naka, Kita-ku, Okayama 700-8530, Japan
| | - Akira Kambe
- Graduate
School of Integrated Pharmaceutical and Nutritional Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka 422-8526, Japan
| | - Shogo Nakano
- Graduate
School of Integrated Pharmaceutical and Nutritional Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka 422-8526, Japan
- PREST,
Japan Science and Technology Agency, Saitama 332-0012, Japan
| | - Hiroki Kakuta
- Division
of Pharmaceutical Sciences, Okayama University
Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 1-1-1, Tsushima-naka, Kita-ku, Okayama 700-8530, Japan
| | - Sohei Ito
- Graduate
School of Integrated Pharmaceutical and Nutritional Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka 422-8526, Japan
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3
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Kodama S, Matsumoto S, Takamura Y, Fujihara M, Watanabe M, Ono A, Kakuta H. Structural characterization of 1,3-bis-tert-butyl monocyclic benzene derivatives with agonistic activity towards retinoid X receptor alpha. Toxicol Lett 2022; 373:76-83. [PMID: 36368620 DOI: 10.1016/j.toxlet.2022.11.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Revised: 10/11/2022] [Accepted: 11/07/2022] [Indexed: 11/11/2022]
Abstract
Retinoid X receptor alpha (RXRα) plays pivotal roles in multiple biological processes, but limited information is available on the structural features of chemicals that show low affinity for RXRα, but nevertheless cause significant activation, though these may represent a human health hazard. We recently discovered that several industrial chemicals having 1,3-bis-tert-butylbenzene as a common chemical structure exhibit agonistic activity towards rat RXRα. In this study, we explored the structure-activity relationship of 1,3-bis-tert-butyl monocyclic benzene derivatives for RXRα activation by means of in vitro and in silico analyses. The results indicate that a bulky substituent at the 5-position is favorable for agonistic activity towards human RXRα. Since 1,3-bis-tert-butyl monocyclic benzene derivatives with bulky hydrophobic moieties differ structurally from known RXRα ligands such as 9-cis-retinoic acid and bexarotene, our findings may be helpful for the development of structural alerts in the safety evaluation of industrial chemicals for RXRα-based toxicity to living organisms.
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Affiliation(s)
- Susumu Kodama
- Division of Pharmaceutical Sciences, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, 1-1-1, Tsushimanaka, Kita-ku, Okayama 700-8530, Japan.
| | - Shuzo Matsumoto
- Division of Pharmaceutical Sciences, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, 1-1-1, Tsushimanaka, Kita-ku, Okayama 700-8530, Japan
| | - Yuta Takamura
- Division of Pharmaceutical Sciences, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, 1-1-1, Tsushimanaka, Kita-ku, Okayama 700-8530, Japan
| | - Michiko Fujihara
- Division of Pharmaceutical Sciences, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, 1-1-1, Tsushimanaka, Kita-ku, Okayama 700-8530, Japan
| | - Masaki Watanabe
- Division of Pharmaceutical Sciences, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, 1-1-1, Tsushimanaka, Kita-ku, Okayama 700-8530, Japan
| | - Atsushi Ono
- Division of Pharmaceutical Sciences, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, 1-1-1, Tsushimanaka, Kita-ku, Okayama 700-8530, Japan
| | - Hiroki Kakuta
- Division of Pharmaceutical Sciences, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, 1-1-1, Tsushimanaka, Kita-ku, Okayama 700-8530, Japan
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4
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Watanabe M, Nakamura-Nakayama M, Fujihara M, Kawasaki M, Nakano S, Kakuta H. Increased Molecular Flexibility Widens the Gap between K i and K d values in Screening for Retinoid X Receptor Modulators. ACS Med Chem Lett 2022; 13:211-217. [PMID: 35178177 PMCID: PMC8842113 DOI: 10.1021/acsmedchemlett.1c00575] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Accepted: 01/19/2022] [Indexed: 11/29/2022] Open
Abstract
Screening for small-molecule modulators targeting a particular receptor is frequently based on measurement of K d, i.e., the binding constant between the receptor and the compound of interest. However, K d values also reflect binding at receptor protein sites other than the modulatory site. We designed derivatives of retinoid X receptor (RXR) antagonist CBTF-EE (1) with modifications that altered their conformational flexibility. Compounds 6a,b and 7a,b showed quite similar K d values, but 7a,b exhibited 10-fold higher K i values than those of 6a,b. Further, 6a,b showed potent RXR-antagonistic activity, while 7a,b were inactive. These results suggest that increased conformational flexibility promotes binding at nontarget receptor sites. In this situation, conventional determination of K d is less effective for screening purposes than the determination of K i using a ligand that binds specifically to the site regulating transcriptional activity. Thus, the use of K i values for orthosteric ligands may increase the hit rate in screening active regulatory molecules.
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Affiliation(s)
- Masaki Watanabe
- Division
of Pharmaceutical Sciences, Okayama University
Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 1-1-1, Tsushima-naka, Kita-ku, Okayama 700-8530, Japan
| | - Mariko Nakamura-Nakayama
- Division
of Pharmaceutical Sciences, Okayama University
Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 1-1-1, Tsushima-naka, Kita-ku, Okayama 700-8530, Japan
| | - Michiko Fujihara
- Division
of Pharmaceutical Sciences, Okayama University
Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 1-1-1, Tsushima-naka, Kita-ku, Okayama 700-8530, Japan,AIBIOS
K.K., Tri-Seven Roppongi
8F, 7-7-7 Roppongi, Minato-ku, Tokyo 106-0032, Japan
| | - Mayu Kawasaki
- Graduate
School of Integrated Pharmaceutical and Nutritional Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka 422-8526, Japan
| | - Shogo Nakano
- Graduate
School of Integrated Pharmaceutical and Nutritional Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka 422-8526, Japan
| | - Hiroki Kakuta
- Division
of Pharmaceutical Sciences, Okayama University
Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 1-1-1, Tsushima-naka, Kita-ku, Okayama 700-8530, Japan,. Phone: +81-(0)86-251-7963
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5
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Takioku M, Takamura Y, Fujihara M, Watanabe M, Yamada S, Kawasaki M, Ito S, Nakano S, Kakuta H. Creation of Fluorescent RXR Antagonists Based on CBTF-EE and Application to a Fluorescence Polarization Binding Assay. ACS Med Chem Lett 2021; 12:1024-1029. [PMID: 34141088 DOI: 10.1021/acsmedchemlett.1c00201] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Accepted: 05/05/2021] [Indexed: 01/08/2023] Open
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.
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Affiliation(s)
- Maho Takioku
- Division of Pharmaceutical Sciences, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 1-1-1, Tsushima-Naka, Kita-ku, Okayama 700-8530, Japan
| | - Yuta Takamura
- Division of Pharmaceutical Sciences, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 1-1-1, Tsushima-Naka, Kita-ku, Okayama 700-8530, Japan
| | - Michiko Fujihara
- Division of Pharmaceutical Sciences, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 1-1-1, Tsushima-Naka, Kita-ku, Okayama 700-8530, Japan
- AIBIOS Co. Ltd., Tri-Seven Roppongi 8F 7-7-7 Roppongi, Minato-ku, Tokyo 106-0032, Japan
| | - Masaki Watanabe
- Division of Pharmaceutical Sciences, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 1-1-1, Tsushima-Naka, Kita-ku, Okayama 700-8530, Japan
| | - Shoya Yamada
- Division of Pharmaceutical Sciences, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 1-1-1, Tsushima-Naka, Kita-ku, Okayama 700-8530, Japan
- Research Fellowship Division, Japan Society for the Promotion of Science, Sumitomo-Ichibancho FS Bldg., 8 Ichibancho, Chiyoda-ku, Tokyo 102-8472, Japan
| | - Mayu Kawasaki
- Graduate School of Integrated Pharmaceutical and Nutritional Sciences, University of Shizuoka, 52- 1 Yada, Suruga-ku, Shizuoka 422-8526, Japan
| | - Sohei Ito
- Graduate School of Integrated Pharmaceutical and Nutritional Sciences, University of Shizuoka, 52- 1 Yada, Suruga-ku, Shizuoka 422-8526, Japan
| | - Shogo Nakano
- Graduate School of Integrated Pharmaceutical and Nutritional Sciences, University of Shizuoka, 52- 1 Yada, Suruga-ku, Shizuoka 422-8526, Japan
| | - Hiroki Kakuta
- Division of Pharmaceutical Sciences, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 1-1-1, Tsushima-Naka, Kita-ku, Okayama 700-8530, Japan
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6
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Schierle S, Chaikuad A, Lillich FF, Ni X, Woltersdorf S, Schallmayer E, Renelt B, Ronchetti R, Knapp S, Proschak E, Merk D. Oxaprozin Analogues as Selective RXR Agonists with Superior Properties and Pharmacokinetics. J Med Chem 2021; 64:5123-5136. [PMID: 33793232 DOI: 10.1021/acs.jmedchem.1c00235] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The retinoid X receptors (RXR) are ligand-activated transcription factors involved in multiple regulatory networks as universal heterodimer partners for nuclear receptors. Despite their high therapeutic potential in many pathologies, targeting of RXR has only been exploited in cancer treatment as the currently available RXR agonists suffer from exceptional lipophilicity, poor pharmacokinetics (PK), and adverse effects. Aiming to overcome the limitations and to provide improved RXR ligands, we developed a new potent RXR ligand chemotype based on the nonsteroidal anti-inflammatory drug oxaprozin. Systematic structure-activity relationship analysis enabled structural optimization toward low nanomolar potency similar to the well-established rexinoids. Cocrystal structures of the most active derivatives demonstrated orthosteric binding, and in vivo profiling revealed superior PK properties compared to current RXR agonists. The optimized compounds were highly selective for RXR activation and induced RXR-regulated gene expression in native cellular and in vivo settings suggesting them as excellent chemical tools to further explore the therapeutic potential of RXR.
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Affiliation(s)
- Simone Schierle
- Institute of Pharmaceutical Chemistry, Goethe University Frankfurt, Max-von-Laue-Str. 9, D-60438 Frankfurt, Germany
| | - Apirat Chaikuad
- Institute of Pharmaceutical Chemistry, Goethe University Frankfurt, Max-von-Laue-Str. 9, D-60438 Frankfurt, Germany.,Structural Genomics Consortium, BMLS, Goethe University Frankfurt, Max-von-Laue-Str. 15, 60438 Frankfurt, Germany
| | - Felix F Lillich
- Institute of Pharmaceutical Chemistry, Goethe University Frankfurt, Max-von-Laue-Str. 9, D-60438 Frankfurt, Germany
| | - Xiaomin Ni
- Institute of Pharmaceutical Chemistry, Goethe University Frankfurt, Max-von-Laue-Str. 9, D-60438 Frankfurt, Germany.,Structural Genomics Consortium, BMLS, Goethe University Frankfurt, Max-von-Laue-Str. 15, 60438 Frankfurt, Germany
| | - Stefano Woltersdorf
- Institute of Pharmaceutical Chemistry, Goethe University Frankfurt, Max-von-Laue-Str. 9, D-60438 Frankfurt, Germany
| | - Espen Schallmayer
- Institute of Pharmaceutical Chemistry, Goethe University Frankfurt, Max-von-Laue-Str. 9, D-60438 Frankfurt, Germany
| | - Beatrice Renelt
- Institute of Pharmaceutical Chemistry, Goethe University Frankfurt, Max-von-Laue-Str. 9, D-60438 Frankfurt, Germany
| | - Riccardo Ronchetti
- Institute of Pharmaceutical Chemistry, Goethe University Frankfurt, Max-von-Laue-Str. 9, D-60438 Frankfurt, Germany
| | - Stefan Knapp
- Institute of Pharmaceutical Chemistry, Goethe University Frankfurt, Max-von-Laue-Str. 9, D-60438 Frankfurt, Germany.,Structural Genomics Consortium, BMLS, Goethe University Frankfurt, Max-von-Laue-Str. 15, 60438 Frankfurt, Germany
| | - Ewgenij Proschak
- Institute of Pharmaceutical Chemistry, Goethe University Frankfurt, Max-von-Laue-Str. 9, D-60438 Frankfurt, Germany
| | - Daniel Merk
- Institute of Pharmaceutical Chemistry, Goethe University Frankfurt, Max-von-Laue-Str. 9, D-60438 Frankfurt, Germany
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