Importance of receptor expression in the classification of novel ligands at the M2 muscarinic acetylcholine receptor.
Br J Pharmacol
; 2022 Dec 22.
Article
em En
| MEDLINE
| ID: mdl-36550621
ABSTRACT
BACKGROUND AND PURPOSE:
Affinity-based, selective orthosteric ligands for the muscarinic acetylcholine receptors (mAChRs) are difficult to develop due to high sequence homology across the five subtypes. Selectivity can also be achieved via the selective activation of a particular subtype or signalling pathway. Promisingly, a prior study identified compounds 6A and 7A as functionally selective and Gi biased compounds at the M2 mAChR. Here, we have investigated the activation of individual G protein subfamilies and the downstream signalling profiles of 6A and 7A at the M2 mAChR. EXPERIMENTALAPPROACH:
G protein activation was measured with the TRUPATH assay in M2 mAChR FlpIn CHO cells. Activity in downstream signalling pathways was determined using the cAMP CAMYEL BRET sensor and assay of ERK 1/2 phosphorylation. KEYRESULTS:
M2 mAChRs coupled to GÉi1 , GÉoA and GÉs , but not GÉq , in response to canonical orthosteric agonists. Compounds 6A and 7A did not elicit any G protein activation, cAMP inhibition or stimulation, or ERK 1/2 phosphorylation. Instead, a Schild analysis indicates a competitive, antagonistic interaction of compounds 6A and 7A with ACh in the GÉi1 activation assay. Overexpression of the M2 mAChR may suggest an expression-dependent activation profile of compounds 6A and 7A. CONCLUSIONS AND IMPLICATIONS These data confirm that the M2 mAChR preferentially couples to GÉi/o and to a lesser extent to GÉs in response to canonical orthosteric ligands. However, this study was not able to detect GÉi bias of compounds 6A and 7A, highlighting the importance of cellular background when classifying new ligands.
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Base de dados:
MEDLINE
Idioma:
En
Revista:
Br J Pharmacol
Ano de publicação:
2022
Tipo de documento:
Article
País de afiliação:
Austrália