title: A beta-arrestin-dependent scaffold is associated with prolonged MAPK activation in pseudopodia during protease-activated receptor-2-induced chemotaxis.
abstract: Cell motility during wound healing and inflammation is often dependent on the ability of the cell to sense a gradient of agonist. The first step in this process is the extension of a pseudopod in the direction of the agonist, and a diverse set of signals mediate pseudopod extension by different receptors. We have reported previously that protease-activated receptor-2 (PAR-2), a proinflammatory receptor that is highly expressed in motile cells such as neutrophils, macrophages, and tumor cells, is one of a growing family of receptors that utilizes a beta-arrestin-dependent mechanism for activation of the 42-44-kDa members of the MAPK family (extracellular signal-regulated kinases 1 and 2; ERK1/2). beta-Arrestin-bound PAR-2 serves as a scaffold to sequester a pool of activated ERK1/2 in the cytosol; however, a specific role for the sequestered kinase activity has not been established. We now show that PAR-2 activation promotes ERK1/2- and beta-arrestin-dependent reorganization of the actin cytoskeleton, polarized pseudopodia extension, and chemotaxis. Using subcellular fractionation, confocal microscopy, and physical isolation of pseudopodial proteins, we demonstrate that the previously identified PAR-2/beta-arrestin/ERK1/2 scaffolding complex is enriched in the pseudopodia, where it appears to prolong ERK1/2 activation. These studies suggest that the formation of a beta-arrestin/ERK1/2 signaling complex at the leading edge may be involved in localized actin assembly and chemotaxis and provide the first example of a distinct cellular consequence of beta-arrestin-sequestered ERK1/2 activity.
authors.affiliation: Biomedical Sciences Division, University of California, Riverside, California 92521, USA.
authors.forename: Lan
authors.initials: L
authors.lastname: Ge
authors.forename: Youly
authors.initials: Y
authors.lastname: Ly
authors.forename: Morley
authors.initials: M
authors.lastname: Hollenberg
authors.forename: Kathryn
authors.initials: K
authors.lastname: DeFea
mesh_terms: D016475:3T3 Cells; D000199:Actins / Q000378:metabolism; D000818:Animals; D019390:Arrestins / Q000378:metabolism*; D002465:Cell Movement; D002633:Chemotaxis; D003600:Cytosol / Q000378:metabolism; D011992:Endosomes / Q000378:metabolism; D004789:Enzyme Activation; D005434:Flow Cytometry; D005799:Genes, Dominant; D049452:Green Fluorescent Proteins; D006801:Humans; D008164:Luminescent Proteins / Q000378:metabolism; D020935:MAP Kinase Signaling System; D008264:Macrophages / Q000378:metabolism; D051379:Mice; D008856:Microscopy, Fluorescence; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D008954:Models, Biological; D009154:Mutation; D010455:Peptides / Q000737:chemistry; D011233:Precipitin Tests; D011485:Protein Binding; D011554:Pseudopodia / Q000201:enzymology*; D044464:Receptor, PAR-2; D018179:Receptors, Thrombin / Q000737:chemistry* / Q000378:metabolism; D015398:Signal Transduction; D013347:Subcellular Fractions / Q000378:metabolism; D014162:Transfection; D000071557:beta-Arrestins
chemical_list: D000199:Actins; D019390:Arrestins; D008164:Luminescent Proteins; D010455:Peptides; D044464:Receptor, PAR-2; D018179:Receptors, Thrombin; D000071557:beta-Arrestins; D049452:Green Fluorescent Proteins; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases