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J Biol Chem. 2014 May 30;289(22):15856-66. doi: 10.1074/jbc.M113.536672. Epub 2014 Apr 21.

Allosteric modulation of M1 muscarinic acetylcholine receptor internalization and subcellular trafficking.

Author information

1
From the Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Faculty of Pharmacy and Pharmaceutical Sciences, Monash University, Parkville, Melbourne, Victoria 3052, Australia and.
2
Department of Pharmacology and Toxicology, Georgia Regents University, Augusta, Georgia 30912.
3
From the Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Faculty of Pharmacy and Pharmaceutical Sciences, Monash University, Parkville, Melbourne, Victoria 3052, Australia and arthur.christopoulos@monash.edu.
4
From the Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Faculty of Pharmacy and Pharmaceutical Sciences, Monash University, Parkville, Melbourne, Victoria 3052, Australia and meri.canals@monash.edu.

Abstract

Allosteric modulators are an attractive approach to achieve receptor subtype-selective targeting of G protein-coupled receptors. Benzyl quinolone carboxylic acid (BQCA) is an unprecedented example of a highly selective positive allosteric modulator of the M1 muscarinic acetylcholine receptor (mAChR). However, despite favorable pharmacological characteristics of BQCA in vitro and in vivo, there is limited evidence of the impact of allosteric modulation on receptor regulatory mechanisms such as β-arrestin recruitment or receptor internalization and endocytic trafficking. In the present study we investigated the impact of BQCA on M1 mAChR regulation. We show that BQCA potentiates agonist-induced β-arrestin recruitment to M1 mAChRs. Using a bioluminescence resonance energy transfer approach to monitor intracellular trafficking of M1 mAChRs, we show that once internalized, M1 mAChRs traffic to early endosomes, recycling endosomes and late endosomes. We also show that BQCA potentiates agonist-induced subcellular trafficking. M1 mAChR internalization is both β-arrestin and G protein-dependent, with the third intracellular loop playing an important role in the dynamics of β-arrestin recruitment. As the global effect of receptor activation ultimately depends on the levels of receptor expression at the cell surface, these results illustrate the need to extend the characterization of novel allosteric modulators of G protein-coupled receptors to encapsulate the consequences of chronic exposure to this family of ligands.

KEYWORDS:

Allosteric Modulator; Allosteric Regulation; Arrestin; G Protein-coupled Receptor (GPCR); GPCR Regulation; Receptor Endocytosis; Trafficking

PMID:
24753247
PMCID:
PMC4140939
DOI:
10.1074/jbc.M113.536672
[Indexed for MEDLINE]
Free PMC Article
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