Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
10816432 | Cellular Signalling | 2005 | 12 Pages |
Abstract
G protein-coupled receptors (GPCRs) transmit diverse cellular signals in response to a large number of stimuli such as chemoattractants, lipids, neurotransmitters, odorants and light. The classical signaling pathway is through heterotrimeric G proteins, but GPCRs can also transmit signals through mechanisms that are not dependent on G proteins. In mammalian cells, the key component for this type of signaling is the family of scaffolding molecules called β-arrestins. They can function as scaffolds for activation of mitogen-activated protein kinases, including extracellular signal-regulated kinases 1 and 2 (ERK1/2). In this study we examined the role of G protein and β-arrestin in formyl peptide receptor (FPR)-mediated activation of chemotaxis, receptor endocytosis and ERK1/2 activation using wild type and mutant receptors. Our findings suggest that, unlike certain other GPCRs that can activate ERK1/2 without the involvement of G protein, FPR requires signaling through a G protein-mediated pathway. Previous observations have shown that ERK1/2, activated through G protein, translocates to the nucleus where it stimulates transcription factors. In contrast, the scaffolding protein β-arrestin retains the activated ERK1/2 in the cytoplasm to allow phosphorylation of cytoplasmic targets. Our experimental data show that both wild-type FPR and a mutant FPR, defective in β-arrestin binding, induce nuclear translocation of activated ERK1/2 with similar ligand concentration dependence as seen for activation of cytosolic ERK1/2. We propose that FPR-mediated activation of ERK1/2 takes place primarily through G protein and is physiologically important to ensure transcriptional activation of myeloid immunomodulators, such as cytokines.
Keywords
FPRFura 2-AMN-formyl peptide receptorfMLFextracellular signal regulated kinases 1 and 2β-arrestinN-formyl-methionyl-leucyl-phenylalanineGRKGPCRERK1/2G protein-coupled receptor kinaseMAPKChoChinese Hamster OvaryG proteinCell signalingTranscriptional activationmitogen-activated protein kinaseChemotaxisextracellular signal-regulated kinaseformyl peptide receptorG protein-coupled receptor
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Authors
Jeannie M. Gripentrog, Heini M. Miettinen,