Angiotensin II cyclic analogs as tools to investigate AT(1)R biased signaling mechanisms

作者：St Pierre David; Cabana Jerome; Holleran Brian J; Besserer Offroy Elie; Escher Emanuel; Guillemette Gaetan; Lavigne Pierre; Leduc Richard^*

来源：Biochemical Pharmacology, 2018, 154: 104-117.

DOI：10.1016/j.bcp.2018.04.021

• Angiotensin II
• Angiotensin II receptor
• GPCR
• Biased signaling
• Cyclic analogs

G protein coupled receptors (GPCRs) produce pleiotropic effects by their capacity to engage numerous signaling pathways once activated. Functional selectivity (also called biased signaling), where specific compounds can bring GPCRs to adopt conformations that enable selective receptor coupling to distinct signaling pathways, continues to be significantly investigated. However, an important but often overlooked aspect of functional selectivity is the capability of ligands such as angiotensin II (AngII) to adopt specific conformations that may preferentially bind to selective GPCRs structures. Understanding both receptor and ligand conformation is of the utmost importance for the design of new drugs targeting GPCRs. In this study, we examined the properties of AngII cyclic analogs to impart biased agonism on the angiotensin type 1 receptor (AT(1)R). Positions 3 and 5 of AngII were substituted for cysteine and homocysteine residues ([Sar(1)Hcy(3,5)]AngII, [Sar(1)Cys(3)Hcy(5)]AngII and [Sar(1)Cys(3,5)]AngII) and the resulting analogs were evaluated for their capacity to activate the Gq/11, G12, Gi2, Gi3, Gz, ERK and beta-arrestin (beta arr) signaling pathways via AT(1)R. Interestingly, [Sar(1)Hcy(3.5)]AngII exhibited potency and full efficacy on all pathways tested with the exception of the Gq pathway. Molecular dynamic simulations showed that the energy barrier associated with the insertion of residue Phe(8) of AngII within the hydrophobic core of AT(1)R, associated with Gq/11 activation, is increased with [Sar(1)Hcy(3,5)]AngII. These results suggest that constraining the movements of molecular determinants within a given ligand by introducing cyclic structures may lead to the generation of novel ligands providing more efficient biased agonism.

• 出版日期2018-8