title: Protease-activated receptor-2 simultaneously directs beta-arrestin-1-dependent inhibition and Galphaq-dependent activation of phosphatidylinositol 3-kinase.
abstract: Protease-activated receptor-2 (PAR-2) is a G-protein-coupled receptor (GPCR) activated upon proteolytic cleavage of its N-terminus by a number of serine proteases. We have previously reported that formation of a beta-arrestin-dependent signaling scaffold is required for PAR-2-stimulated activation of extracellular signal regulated kinases 1 and 2 and chemotaxis. beta-Arrestin-dependent pathways downstream of some GPCRs have been shown to function independently and sometimes in opposition to classic signaling through heterotrimeric G-proteins; however, this possibility has not been addressed with respect to PAR-2. Here we demonstrate that PAR-2 can increase PI3K activity through a Galphaq/Ca(2+)-dependent pathway involving PYK2 and a Src-family kinase, while inhibiting PI3K activity through a beta-arrestin-dependent mechanism, and that beta-arrestin-1 can directly associate with and inhibit the catalytic activity of p110alpha. Using size exclusion chromatography and co-immunoprecipitation, we demonstrate that the PI3K is recruited into a scaffolding complex containing PAR-2 and beta-arrestins. Inhibition of PI3K activity blocks PAR-2-stimulated chemotaxis, and beta-arrestin-1 colocalizes with p85 within the pseudopodia, suggesting that beta-arrestin-1 association with PI3K may spatially restrict its enzymatic activity and that this localized inhibition may be crucial for PAR-2-stimulated chemotaxis.
authors.affiliation: Division of Biomedical Sciences, University of California, Riverside, California 92521, USA.
authors.forename: Ping
authors.initials: P
authors.lastname: Wang
authors.forename: Kathryn A
authors.initials: KA
authors.lastname: DeFea
mesh_terms: D000818:Animals; D019390:Arrestins / Q000235:genetics / Q000378:metabolism*; D002633:Chemotaxis; D058534:Class I Phosphatidylinositol 3-Kinases; D004789:Enzyme Activation; D051418:Focal Adhesion Kinase 2 / Q000378:metabolism; D043802:GTP-Binding Protein alpha Subunits, Gq-G11 / Q000235:genetics / Q000378:metabolism*; D047468:Immunoprecipitation; D046911:Macromolecular Substances / Q000378:metabolism; D051379:Mice; D041681:NIH 3T3 Cells; D019869:Phosphatidylinositol 3-Kinases / Q000032:analysis / Q000378:metabolism*; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011554:Pseudopodia / Q000201:enzymology; D044464:Receptor, PAR-2 / Q000378:metabolism*; D000071559:beta-Arrestin 1; D000071557:beta-Arrestins; D019061:src-Family Kinases / Q000032:analysis / Q000378:metabolism
chemical_list: D019390:Arrestins; D058534:Class I Phosphatidylinositol 3-Kinases; D051418:Focal Adhesion Kinase 2; D043802:GTP-Binding Protein alpha Subunits, Gq-G11; D046911:Macromolecular Substances; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D044464:Receptor, PAR-2; D000071559:beta-Arrestin 1; D000071557:beta-Arrestins; D019061:src-Family Kinases; C000605255:Arrb1 protein, mouse; C509622:1-phosphatidylinositol 3-kinase p110 subunit, mouse