title: Mechanism of retinoid X receptor partial agonistic action of 1-(3,5,5,8,8-pentamethyl-5,6,7,8-tetrahydro-2-naphthyl)-1H-benzotriazole-5-carboxylic acid and structural development to increase potency.
abstract: We have reported that retinoid X receptor (RXR) partial agonist 1-(3,5,5,8,8-pentamethyl-5,6,7,8-tetrahydro-2-naphthyl)-1H-benzotriazole-5-carboxylic acid (CBt-PMN, 4a) shows a significant antidiabetes effect in the KK-A(y) type 2 diabetes model mice, with reduced side effects compared to RXR full agonists. To elucidate the mechanism of the RXR partial agonist activity of 4a, we synthesized derivatives of 4a, evaluated their RXR agonist activity, and performed structure-activity relationship analysis. Reporter gene assay revealed that though 6b, which possesses an amino group at the 2-position of 5-carboxybenzimidazole, showed RXR full-agonist activity, compounds 6d and 6e, which possess an oxygen atom and a sulfur atom at the corresponding position, respectively, showed weak RXR agonist activity. On the other hand, 6c, which has a trifluoromethyl group at the corresponding position, acts as an RXR partial agonist, having similar Emax (67 ± 2%) and lower EC50 (15 ± 0 nM) compared to those of 4a (Emax = 75 ± 4%, EC50 = 143 ± 2 nM). A fluorescence polarization assay of cofactor recruitment confirmed that fluorescein-labeled D22 coactivator peptide was less efficiently recruited to RXR by 4a and 6c than by LGD1069 (1), a known RXR full agonist. Electrostatic potential field calculations and computational docking studies suggested that full agonists show an electrostatic attraction, which stabilizes the holo structure and favors coactivator recruitment, between the side chain at the benzimidazole 2-position and the α-carbonyl oxygen of asparagine-306 in helix 4 (H4) of the RXR receptor. However, RXR partial agonists 4a and 6c lack this interaction. Like 4a, 6c showed a significant antidiabetes effect in KK-A(y) type 2 diabetes model mice with reduced levels of the side effects associated with RXR full agonists. These findings should aid the design of new RXR partial agonists as antitype 2 diabetes drug candidates.
authors: 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.
authors: Fuminori
authors: F
authors: Ohsawa
authors: Shoya
authors: S
authors: Yamada
authors: Nobumasa
authors: N
authors: Yakushiji
authors: Ryosuke
authors: R
authors: Shinozaki
authors: Mariko
authors: M
authors: Nakayama
authors: Kohei
authors: K
authors: Kawata
authors: Manabu
authors: M
authors: Hagaya
authors: Toshiki
authors: T
authors: Kobayashi
authors: Kazutaka
authors: K
authors: Kohara
authors: Yuuki
authors: Y
authors: Furusawa
authors: Chisa
authors: C
authors: Fujiwara
authors: Yui
authors: Y
authors: Ohta
authors: Makoto
authors: M
authors: Makishima
authors: Hirotaka
authors: H
authors: Naitou
authors: Akihiro
authors: A
authors: Tai
authors: Yutaka
authors: Y
authors: Yoshikawa
authors: Hiroyuki
authors: H
authors: Yasui
authors: Hiroki
authors: H
authors: Kakuta
mesh_terms: D000818:Animals; D019556:COS Cells; D002522:Chlorocebus aethiops; D003924:Diabetes Mellitus, Type 2 / Q000188:drug therapy*; D007004:Hypoglycemic Agents / Q000737:chemistry / Q000494:pharmacology*; D051379:Mice; D008958:Models, Molecular; D062105:Molecular Docking Simulation; D047488:Retinoid X Receptors / Q000819:agonists* / Q000187:drug effects; D013764:Tetrahydronaphthalenes / Q000737:chemistry / Q000494:pharmacology*; D014230:Triazoles / Q000737:chemistry / Q000494:pharmacology*
chemical_list: C581001:1-(3,5,5,8,8-pentamethyl-5,6,7,8-tetrahydro-2-naphthyl)-1H-benzotriazole-5-carboxylic acid; D007004:Hypoglycemic Agents; D047488:Retinoid X Receptors; D013764:Tetrahydronaphthalenes; D014230:Triazoles; C062152:1H-benzotriazole-5-carboxylic acid