Protease-activated receptor-2 simultaneously directs beta-arrestin-1-dependent inhibition and Galphaq-dependent activation of phosphatidylinositol 3-kinase

Biochemistry. 2006 Aug 8;45(31):9374-85. doi: 10.1021/bi0602617.

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.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Arrestins / genetics
  • Arrestins / metabolism*
  • Chemotaxis
  • Class I Phosphatidylinositol 3-Kinases
  • Enzyme Activation
  • Focal Adhesion Kinase 2 / metabolism
  • GTP-Binding Protein alpha Subunits, Gq-G11 / genetics
  • GTP-Binding Protein alpha Subunits, Gq-G11 / metabolism*
  • Immunoprecipitation
  • Macromolecular Substances / metabolism
  • Mice
  • NIH 3T3 Cells
  • Phosphatidylinositol 3-Kinases / analysis
  • Phosphatidylinositol 3-Kinases / metabolism*
  • Phosphoinositide-3 Kinase Inhibitors*
  • Pseudopodia / enzymology
  • Receptor, PAR-2 / metabolism*
  • beta-Arrestin 1
  • beta-Arrestins
  • src-Family Kinases / analysis
  • src-Family Kinases / metabolism

Substances

  • Arrb1 protein, mouse
  • Arrestins
  • Macromolecular Substances
  • Phosphoinositide-3 Kinase Inhibitors
  • Receptor, PAR-2
  • beta-Arrestin 1
  • beta-Arrestins
  • 1-phosphatidylinositol 3-kinase p110 subunit, mouse
  • Class I Phosphatidylinositol 3-Kinases
  • Focal Adhesion Kinase 2
  • src-Family Kinases
  • GTP-Binding Protein alpha Subunits, Gq-G11