Involvement of tryptophan W276 and of two surrounding amino acid residues in the high constitutive activity of the ghrelin receptor GHS-R1a - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue European Journal of Pharmacology Molecular Pharmacology Année : 2010

Involvement of tryptophan W276 and of two surrounding amino acid residues in the high constitutive activity of the ghrelin receptor GHS-R1a

Résumé

The human ghrelin receptor (GHS-R1a) is known to display a high level of signaling in the absence of ligand. The Trp276, located in the fully conserved CWXP motif of G protein-coupled receptors, is believed to function as a rotameric switch in these receptors. A comparative modelling of GHS-R1a with the motilin receptor, the most related G protein-coupled receptor to GHS-R1a known to date, but characterized by a very low ligand-independent signaling level, revealed that only two surrounding residues of Trp276, that are Val131 and Ile134, were different from these receptors. We mutated them at once in GHS-R1a to create a "motilin receptor-like" environment of Trp276 in order to study the consequences on GHS-R1a activation. We studied the pharmacological properties of the W276A, V131L-1134M GHS-R1a mutants. Basal as well as maximal ghrelin-induced signaling was assessed both by inositol-phosphate accumulation and SRE pathways. As compared to the wild type receptor, the SRE-luciferase assay displayed a markedly impaired basal activity for W276A whereas that of V131L-I134M was, strikingly, two fold increased. Nevertheless, the efficacy of ghrelin to bind or to stimulate mutant receptors remained unchanged. It is concluded that Trp276, Val131 and Ile134 have a significant impact on constitutive signaling of GHS-R1a, V131L-1134M being the first example of a GHS-R1a mutant with a higher basal activity than the wild type receptor. (C) 2010 Elsevier B.V. All rights reserved.

Dates et versions

hal-00583009 , version 1 (04-04-2011)

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Citer

C. Goze, Gilbert Berge, Celine M\'Kadmi, Nicolas Floquet, Didier Gagne, et al.. Involvement of tryptophan W276 and of two surrounding amino acid residues in the high constitutive activity of the ghrelin receptor GHS-R1a. European Journal of Pharmacology Molecular Pharmacology, 2010, 643 (2-3), pp.153-161. ⟨10.1016/j.ejphar.2010.06.018⟩. ⟨hal-00583009⟩
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