Orphan G protein-coupled receptors Mrga1 and Mrgc11 are distinctively activated by RF-amide-related peptides through the Gαq/11 pathway

Sang Kyou Han, Xinzhong Dong, Jong Ik Hwang, Mark J. Zylka, David J. Anderson, Melvin I. Simon

Research output: Contribution to journalArticle

122 Citations (Scopus)

Abstract

MrgA1 and MrgC11 belong to a recently identified family of orphan G-protein coupled receptors, called mrgs (mas-related genes). They are only expressed in a specific subset of sensory neurons that are known to detect painful stimuli. However, the precise physiological function of Mrg receptors and their underlying mechanisms of signal transduction are not known. We therefore have screened a series of neuropeptides against human embryonic kidney (HEK) 293 cells that stably express either MrgA1 or MrgC11 to identify ligands and/or agonists. MrgA1- or MrgC11-specific agonists stimulated dose-dependent increases in intracellular free Ca2+ in a pertussis toxin-insensitive manner, but failed to alter basal or forskolin-stimulated levels of intracellular cAMP. Furthermore, studies using embryonic fibroblasts derived from various Ga protein knockout mice demonstrated that both the MrgA1 and MrgC11 receptors are coupled to the Gαq/11, signaling pathway. Screening of neuropeptides identified surrogate agonists, most of these peptides included a common C-terminal -RF(Y)G or -RF(Y) amide motif. Structure-function studies suggest that endogenous ligands of Mrg receptors are likely to be RF(Y)G and/or RF(Y) amide-related peptides and that postprocessing of these peptides may serve to determine Mrg receptor-ligand specificity. The differences in ligand specificity also suggest functional diversity amongst the Mrg receptors.

Original languageEnglish
Pages (from-to)14740-14745
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume99
Issue number23
DOIs
Publication statusPublished - 2002 Nov 12

ASJC Scopus subject areas

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