Molecular determinants of positive allosteric modulation of the human metabotropic glutamate receptor 2

Br J Pharmacol. 2015 May;172(9):2383-96. doi: 10.1111/bph.13065. Epub 2015 Feb 27.

Abstract

Background and purpose: The activation of the metabotropic glutamate receptor 2 (mGlu2 ) reduces glutamatergic transmission in brain regions where excess excitatory signalling is implicated in disorders such as anxiety and schizophrenia. Positive allosteric modulators (PAMs) can provide a fine-tuned potentiation of these receptors' function and are being investigated as a novel therapeutic approach. An extensive set of mutant human mGlu2 receptors were used to investigate the molecular determinants that are important for positive allosteric modulation at this receptor.

Experimental approach: Site-directed mutagenesis, binding and functional assays were employed to identify amino acids important for the activity of nine PAMs. The data from the radioligand binding and mutagenesis studies were used with computational docking to predict a binding mode at an mGlu2 receptor model based on the recent structure of the mGlu1 receptor.

Key results: New amino acids in TM3 (R635, L639, F643), TM5 (L732) and TM6 (W773, F776) were identified for the first time as playing an important role in the activity of mGlu2 PAMs.

Conclusions and implications: This extensive study furthers our understanding of positive allosteric modulation of the mGlu2 receptor and can contribute to improved future design of mGlu2 PAMs.

MeSH terms

  • Animals
  • Binding Sites
  • Binding, Competitive
  • CHO Cells
  • Cricetulus
  • Dose-Response Relationship, Drug
  • Drug Design*
  • Excitatory Amino Acid Agents / chemistry
  • Excitatory Amino Acid Agents / metabolism*
  • Excitatory Amino Acid Agents / pharmacology
  • Glutamic Acid / metabolism
  • Humans
  • Ligands
  • Molecular Docking Simulation*
  • Mutagenesis, Site-Directed
  • Mutation
  • Protein Binding
  • Protein Conformation
  • Receptors, Metabotropic Glutamate / drug effects
  • Receptors, Metabotropic Glutamate / genetics
  • Receptors, Metabotropic Glutamate / metabolism*
  • Structure-Activity Relationship
  • Transfection

Substances

  • Excitatory Amino Acid Agents
  • Ligands
  • Receptors, Metabotropic Glutamate
  • metabotropic glutamate receptor 2
  • Glutamic Acid