Electronic sculpting of ligand-GPCR subtype selectivity: the case of angiotensin II.

Francesca Magnani,Masaaki Tamura,Paul Cordopatis,Charalampos G Pappas,Emma S Jones,Naomi Ohta,Tim Crook,Andreas G Tzakos,Susumu Ishiguro,Ioannis P Gerothanassis,Vassiliki Magafa,Sanja Bosnyak,Jana Selent,Robert E Widdop

doi:10.1021/cb500063y

Abstract

GPCR subtypes possess distinct functional and pharmacological profiles, and thus development of subtype-selective ligands has immense therapeutic potential. This is especially the case for the angiotensin receptor subtypes AT1R and AT2R, where a functional negative control has been described and AT2R activation highlighted as an important cancer drug target. We describe a strategy to fine-tune ligand selectivity for the AT2R/AT1R subtypes through electronic control of ligand aromatic-prolyl interactions. Through this strategy an AT2R high affinity (Ki = 3 nM) agonist analogue that exerted 18,000-fold higher selectivity for AT2R versus AT1R was obtained. We show that this compound is a negative regulator of AT1R signaling since it is able to inhibit MCF-7 breast carcinoma cellular proliferation in the low nanomolar range.

Highlights

G-protein-coupled receptors (GPCRs) subtypes within a subfamily usually possess distinct functional and pharmacological profiles,[3] and development of subtype-selective ligands has immense untapped therapeutic potential
Figure 1. 3D model of the Angiotensin II (AII)−AT1R complex and the electronic tuning strategy used in this work for AII. (a) Key interactions between the hormone AII and AT1R, comprising hydrogen bonds and hydrophobic contacts. (b) Conserved regions between AT1R and AT2R depicted in gray stick and surface; unconserved regions are highlighted in a red stick representation
ECL1, extracellular loop 2 (ECL2) correspond to the extracellular loops 1 and 2 and TM2, 4, 5, and 6 correspond to transmembrane regions 2, 4, 5, and 6, respectively. (c) The sequence of the hormone AII with its C-terminus highlighted. (d,e) The H6 of AII was altered in this work with 4-X substituted phenylalanine on the frame of an electronic strategy to regulate the compactness of the AII C-terminus

Summary

■ METHODS

This material is available free of charge via the Internet at http://pubs.acs.org. Present Address ○Biological Crystallography Lab, Department of Biology and Biotechnology, University of Pavia, Italy

■ ACKNOWLEDGMENTS

Findings

■ REFERENCES