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Mol Pharmacol. 2017 Apr;91(4):348-356. doi: 10.1124/mol.116.107276. Epub 2017 Feb 6.

A New Molecular Mechanism To Engineer Protean Agonism at a G Protein-Coupled Receptor.

Author information

1
Pharmacology and Toxicology Section, Institute of Pharmacy (A.D.M., J.H., C.T., K.M., R.S.), Research Training Group 1873 (A.D.M., E.K., K.M.), and Molecular-, Cellular-, and Pharmacobiology Section, Institute of Pharmaceutical Biology (E.K.), University of Bonn, Bonn, Germany; Dipartimento di Scienze Farmaceutiche, Sezione di Chimica Farmaceutica 'Pietro Pratesi,' Università degli Studi di Milano, Milano, Italy (C.M., M.D.A., C.D.); Institute of Pharmacology and Toxicology, University of Würzburg, Würzburg, Germany (A.B.); Department of Pharmaceutical and Medicinal Chemistry, Institute of Pharmacy, University of Würzburg, Würzburg, Germany (J.K., M.M., U.H.); and Department of Pharmacology, University of North Carolina School of Medicine, Chapel Hill, North Carolina (T.K.).
2
Pharmacology and Toxicology Section, Institute of Pharmacy (A.D.M., J.H., C.T., K.M., R.S.), Research Training Group 1873 (A.D.M., E.K., K.M.), and Molecular-, Cellular-, and Pharmacobiology Section, Institute of Pharmaceutical Biology (E.K.), University of Bonn, Bonn, Germany; Dipartimento di Scienze Farmaceutiche, Sezione di Chimica Farmaceutica 'Pietro Pratesi,' Università degli Studi di Milano, Milano, Italy (C.M., M.D.A., C.D.); Institute of Pharmacology and Toxicology, University of Würzburg, Würzburg, Germany (A.B.); Department of Pharmaceutical and Medicinal Chemistry, Institute of Pharmacy, University of Würzburg, Würzburg, Germany (J.K., M.M., U.H.); and Department of Pharmacology, University of North Carolina School of Medicine, Chapel Hill, North Carolina (T.K.) rschrage@uni-bonn.de.

Abstract

Protean agonists are of great pharmacological interest as their behavior may change in magnitude and direction depending on the constitutive activity of a receptor. Yet, this intriguing phenomenon has been poorly described and understood, due to the lack of stable experimental systems and design strategies. In this study, we overcome both limitations: First, we demonstrate that modulation of the ionic strength in a defined experimental set-up allows for analysis of G protein-coupled receptor activation in the absence and presence of a specific amount of spontaneous receptor activity using the muscarinic M2 acetylcholine receptor as a model. Second, we employ this assay system to show that a dualsteric design principle, that is, molecular probes, carrying two pharmacophores to simultaneously adopt orthosteric and allosteric topography within a G protein-coupled receptor, may represent a novel approach to achieve protean agonism. We pinpoint three molecular requirements within dualsteric compounds that elicit protean agonism at the muscarinic M2 acetylcholine receptor. Using radioligand-binding and functional assays, we posit that dynamic ligand binding may be the mechanism underlying protean agonism of dualsteric ligands. Our findings provide both new mechanistic insights into the still enigmatic phenomenon of protean agonism and a rationale for the design of such compounds for a G protein-coupled receptor.

PMID:
28167741
DOI:
10.1124/mol.116.107276
[Indexed for MEDLINE]

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