Role of the N-terminal region in G protein-coupled receptor functions : negative modulation revealed by 5-HT2B receptor polymorphisms

Belmer, Arnauld, Doly, Stephane, Setola, Vincent, Banas, Sophie M., Moutkine, Imane, Boutourlinsky, Katia, Kenakin, Terry, & Maroteaux, Luc (2013) Role of the N-terminal region in G protein-coupled receptor functions : negative modulation revealed by 5-HT2B receptor polymorphisms. Molecular Pharmacology, 85(1 ), pp. 127-138.

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Abstract

The putative role of the N-terminal region of rhodopsin-like 7 transmembrane biogenic amine receptors in agonist-induced signaling has not yet been clarified despite recent advances in 7 transmembrane receptor structural biology. Given the existence of N-terminal nonsynonymous polymorphisms (R6G;E42G) within the HTR2B gene in a drug-abusing population, we assessed whether these polymorphisms affect 5-hydroxytryptamine 2B (5-HT2B) receptor in vitro pharmacologic and coupling properties in transfected COS-7 cells. Modification of the 5-HT2B receptor N terminus by the R6G;E42G polymorphisms increases such agonist signaling pathways as inositol phosphate accumulation as assessed by either classic or operational models. The N-terminal R6G;E42G mutations of the 5-HT2B receptor also increase cell proliferation and slow its desensitization kinetics compared with the wild-type receptor, further supporting a role for the N terminus in transduction efficacy. Furthermore, by coexpressing a tethered wild-type 5-HT2B receptor N terminus with a 5-HT2B receptor bearing a N-terminal deletion, we were able to restore original coupling. This reversion to normal activity of a truncated 5-HT2B receptor by coexpression of the membrane-tethered wild-type 5-HT2B receptor N terminus was not observed using a membrane-tethered 5-HT2B receptor R6G;E42G N terminus. These data suggest that the N terminus exerts a negative control over basal as well as agonist-stimulated receptor activity that is lost in the R6G;E42G mutant. Our findings reveal a new and unanticipated role of the 5-HT2B receptor N terminus as a negative modulator, affecting both constitutive and agonist-stimulated activity. Moreover, our data caution against excluding the N terminus and extracellular loops in structural studies of this 7 transmembrane receptor family

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ID Code: 75293
Item Type: Journal Article
Refereed: Yes
Additional URLs:
Keywords: 5-HT2B, N-terminal, G-protein coupled receptors, SNP polymorphism
DOI: 10.1124/mol.113.089086
ISSN: 1521-0111
Subjects: Australian and New Zealand Standard Research Classification > MEDICAL AND HEALTH SCIENCES (110000) > PHARMACOLOGY AND PHARMACEUTICAL SCIENCES (111500) > Basic Pharmacology (111501)
Divisions: Current > QUT Faculties and Divisions > Faculty of Health
Copyright Owner: Copyright 2014 American Society for Pharmacology and Experimental Therapeutics
Deposited On: 19 Aug 2014 23:06
Last Modified: 21 Aug 2014 00:59

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