Molecular mechanism of positive allosteric modulation of the metabotropic glutamate receptor 2 by JNJ‐46281222

• Published in: British journal of pharmacology 2016-02, Vol.173 (3), p.588-600
• Main Authors: Doornbos, Maarten L J, Pérez‐Benito, Laura, Tresadern, Gary, Mulder‐Krieger, Thea, Biesmans, Ilse, Trabanco, Andrés A, Cid, Jose María, Lavreysen, Hilde, IJzerman, Adriaan P, Heitman, Laura H
• Format: Article
• Language: English
• Subjects: Activation; Allosteric properties; Allosteric Regulation - drug effects; Amino acids; Animals; Binding sites; CHO Cells; Computational neuroscience; Computer applications; Computer simulation; Cricetulus; Glutamic acid receptors; Glutamic acid receptors (metabotropic); Guanosine triphosphate; Homology; Humans; Mental disorders; Models, Molecular; Molecular dynamics; Mutagenesis; Neurological diseases; Piperidines - pharmacology; Pyridines - pharmacology; Receptors, Metabotropic Glutamate - genetics; Receptors, Metabotropic Glutamate - metabolism; Research Paper; Research Papers; Site-directed mutagenesis; Triazoles - pharmacology
• ISSN: 0007-1188; 1476-5381
• DOI: 10.1111/bph.13390

Background and Purpose Allosteric modulation of the mGlu2 receptor is a potential strategy for treatment of various neurological and psychiatric disorders. Here, we describe the in vitro characterization of the mGlu2 positive allosteric modulator (PAM) JNJ‐46281222 and its radiolabelled counterpart [3H]‐JNJ‐46281222. Using this novel tool, we also describe the allosteric effect of orthosteric glutamate binding and the presence of a bound G protein on PAM binding and use computational approaches to further investigate the binding mode. Experimental Approach We have used radioligand binding studies, functional assays, site‐directed mutagenesis, homology modelling and molecular dynamics to study the binding of JNJ‐46281222. Key Results JNJ‐46281222 is an mGlu2‐selective, highly potent PAM with nanomolar affinity (KD = 1.7 nM). Binding of [3H]‐JNJ‐46281222 was increased by the presence of glutamate and greatly reduced by the presence of GTP, indicating the preference for a G protein bound state of the receptor for PAM binding. Its allosteric binding site was visualized and analysed by a computational docking and molecular dynamics study. The simulations revealed amino acid movements in regions expected to be important for activation. The binding mode was supported by [3H]‐JNJ‐46281222 binding experiments on mutant receptors. Conclusion and Implications Our results obtained with JNJ‐46281222 in unlabelled and tritiated form further contribute to our understanding of mGlu2 allosteric modulation. The computational simulations and mutagenesis provide a plausible binding mode with indications of how the ligand permits allosteric activation. This study is therefore of interest for mGlu2 and class C receptor drug discovery.