Importance of the Proximity and Orientation of Ligand-Linkage to the Design of Cinnamate-GW9662 Hybrid Compounds as Covalent PPARγ Agonists.

Yuki Utsugi,Masaya Nagao,Yukio Kawamura,Hiroko Isoda,Hirona Kobuchi,Yusaku Miyamae,Ahmed Salahelden Aboelhamd Atito

doi:10.3390/molecules24102019

Yuki Utsugi, Masaya Nagao + Show 5 more

Open Access

https://doi.org/10.3390/molecules24102019

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Abstract

Covalent agonists of PPARγ cause unique receptor conformational changes and behave as selective PPARγ modulators, whereas there are few covalent agonists other than endogenous unsaturated fatty acids metabolites. Previously, we established a cell-based strategy to identify new PPARγ ligands and synthesized a new-type of covalent agonist that possesses the hybrid structure of a plant-derived cinnamic acid derivative and GW9662, a covalent antagonist. Herein, we report six analogues that differ in how the two fragments are linked together. Compounds with a simplified linker showed potent agonistic activity with improved EC50 values (less than 5 nM), indicating that close proximity between the two fragments improves binding affinity. When the position of cinnamic acid moiety was placed at 4′ carbon of aniline ring, PPARγ agonist activity was completely abolished. Docking studies suggested that the activation profile likely depends on interaction with the cavity around helix 3, β-sheet, and Ω-loop region in the ligand-binding domain. Furthermore, a cell-based assay revealed that agonist-type compounds activate PPARγ transcription in a manner dependent on covalent linkage with the Cys285 residue leading to prolonged transactivation. This activation feature reflects pharmacological benefits of covalent drugs, suggesting that these hybrid compounds may serve as potential leads for a new-class of covalent PPARγ ligands.

Highlights

Peroxisome proliferator-activated receptor (PPAR) γ is a member of the nuclear receptor superfamily and is found in adipose tissue and macrophages [1]
We synthesized new derivatives of the covalent agonist 3 using an improved synthetic protocol, allowing us to access a variety of compounds with a simplified linker moiety and a different connection site between GW9662 and the cinnnamate unit
A cell-based assay revealed that the synthesized ligands showed distinct profiles of transactivation of the PPARγ

Summary

Introduction

Peroxisome proliferator-activated receptor (PPAR) γ is a member of the nuclear receptor superfamily and is found in adipose tissue and macrophages [1]. Molecules 2019, 24, 2019 of type 2 diabetes, its use has been limited because of adverse effects such as body weight gain and edema These side effects are closely related with the undesirable expression of a subset of genes as a result of the complete activation of PPARγ transcription by full agonists [8,9]. Partial PPARγ agonists can selectively modulate the transcription of the downstream gene set, resulting in fewer side effects while retaining beneficial pharmacological effects [10,11] This is related to the distinct conformational changes caused by the partial agonists, leading to different coactivator recruitment and activation of discrete sets of the downstream genes [12,13]

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