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

Maarten L.J. Doornbos, Laura Pérez-Benito, Gary Tresadern, Thea Mulder-Krieger, Ilse Biesmans, Andrés A. Trabanco, Jose María Cid, Hilde Lavreysen, Adriaan P. Ijzerman, Laura H. Heitman

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32 Citations (Scopus)


© 2015 The British Pharmacological Society. 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.
Original languageEnglish
Pages (from-to)588-600
JournalBritish Journal of Pharmacology
Issue number3
Publication statusPublished - 1 Feb 2016


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