title: The role of beta-arrestins in the formyl peptide receptor-like 1 internalization and signaling.
abstract: The N-formyl peptide receptor-like 1 (FPRL1) is a G protein-coupled receptor (GPCR) that transmits intracellular signals in response to a variety of agonists, many of them being clearly implicated in human pathology. beta-arrestins are adaptor proteins that uncouple GPCRs from G protein and regulate receptor internalization. They can also function as signal transducers through the scaffolding of signaling molecules, such as components of the extracellular signal-regulated kinase (ERK) cascade. We investigated the role of beta-arrestins in ligand-induced FPRL1 internalization and signaling. In HEK293 cells expressing FPRL1, fluorescence microscopy revealed that agonist-stimulated FPRL1 remained co-localized with beta-arrestins during endocytosis. Internalization of FPRL1, expressed in a mouse embryonic fibroblast (MEF) cell line lacking endogenous beta-arrestins, was highly compromised. This distinguishes FPRL1 from the prototypical formyl peptide receptor FPR that is efficiently internalized in the absence of beta-arrestins. In both HEK293 and MEF cells, FPRL1-mediated ERK1/2 activation was a rapid and transient event. The kinetics and extent of ERK1/2 activation were not significantly modified by beta-arrestin overexpression. The pattern of FPRL1-mediated ERK1/2 activation was similar whether cells express or not beta-arrestins. Furthermore, treatment of the FPRL1 expressing cells with pertussis toxin inhibited ERK1/2 activation in MEF and in HEK293 cells. These results led us to conclude that activation of ERK1/2 mediated by FPRL1 occurs primarily through G protein signaling. Since beta-arrestin-mediated signaling has been observed essentially for receptors coupled to G proteins other than G(i), this may be a characteristic of G(i) protein-coupled chemoattractant receptors.
authors.affiliation: Commissariat à l'Energie Atomique (CEA), DSV, iRSTV, Laboratoire de Biochimie et de Biophysique des Systèmes Intégrés (LBBSI), Grenoble, F-38054, France.
authors.forename: Emilie
authors.initials: E
authors.lastname: Huet
authors.forename: François
authors.initials: F
authors.lastname: Boulay
authors.forename: Sophie
authors.initials: S
authors.lastname: Barral
authors.forename: Marie-Josèphe
authors.initials: MJ
authors.lastname: Rabiet
mesh_terms: D000818:Animals; D019390:Arrestins / Q000172:deficiency / Q000378:metabolism*; D002460:Cell Line; D004705:Endocytosis; D004789:Enzyme Activation; D005347:Fibroblasts / Q000166:cytology / Q000201:enzymology; D019204:GTP-Binding Proteins / Q000378:metabolism; D015870:Gene Expression; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D051379:Mice; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D021381:Protein Transport; D044042:Receptors, Formyl Peptide / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D015398:Signal Transduction; D000071557:beta-Arrestins
chemical_list: D019390:Arrestins; D044042:Receptors, Formyl Peptide; D011993:Recombinant Fusion Proteins; D000071557:beta-Arrestins; C485184:enhanced green fluorescent protein; D049452:Green Fluorescent Proteins; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D019204:GTP-Binding Proteins