title: Pathway-selective antagonism of proteinase activated receptor 2.
abstract: OBJECTIVE
  Proteinase activated receptor 2 (PAR2) is a GPCR associated with inflammation, metabolism and disease. Clues to understanding how to block PAR2 signalling associated with disease without inhibiting PAR2 activation in normal physiology could be provided by studies of biased signalling.
  
  
  METHODS
  PAR2 ligand GB88 was profiled for PAR2 agonist and antagonist properties by several functional assays associated with intracellular G-protein-coupled signalling in vitro in three cell types and with PAR2-induced rat paw oedema in vivo.
  
  
  RESULTS
  In HT29 cells, GB88 was a PAR2 antagonist in terms of Ca(2+) mobilization and PKC phosphorylation, but a PAR2 agonist in attenuating forskolin-induced cAMP accumulation, increasing ERK1/2 phosphorylation, RhoA activation, myosin phosphatase phosphorylation and actin filament rearrangement. In CHO-hPAR2 cells, GB88 inhibited Ca(2+) release, but activated G(i/o) and increased ERK1/2 phosphorylation. In human kidney tubule cells, GB88 inhibited cytokine secretion (IL6, IL8, GM-CSF, TNF-α) mediated by PAR2. A rat paw oedema induced by PAR2 agonists was also inhibited by orally administered GB88 and compared with effects of locally administered inhibitors of G-protein coupled pathways.
  
  
  CONCLUSIONS
  GB88 is a biased antagonist of PAR2 that selectively inhibits PAR2/G(q/11)/Ca(2+)/PKC signalling, leading to anti-inflammatory activity in vivo, while being an agonist in activating three other PAR2-activated pathways (cAMP, ERK, Rho) in human cells. These findings highlight opportunities to design drugs to block specific PAR2-linked signalling pathways in disease, without blocking beneficial PAR2 signalling in normal physiology, and to dissect PAR2-associated mechanisms of disease in vivo.
authors.affiliation: Institute for Molecular Bioscience, The University of Queensland, Brisbane, Qld, Australia.
authors.forename: J Y
authors.initials: JY
authors.lastname: Suen
authors.forename: A
authors.initials: A
authors.lastname: Cotterell
authors.forename: R J
authors.initials: RJ
authors.lastname: Lohman
authors.forename: J
authors.initials: J
authors.lastname: Lim
authors.forename: A
authors.initials: A
authors.lastname: Han
authors.forename: M K
authors.initials: MK
authors.lastname: Yau
authors.forename: L
authors.initials: L
authors.lastname: Liu
authors.forename: M A
authors.initials: MA
authors.lastname: Cooper
authors.forename: D A
authors.initials: DA
authors.lastname: Vesey
authors.forename: D P
authors.initials: DP
authors.lastname: Fairlie
mesh_terms: D000818:Animals; D016466:CHO Cells; D002478:Cells, Cultured; D003412:Cricetulus; D016207:Cytokines / Q000037:antagonists & inhibitors / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D019073:HT29 Cells; D006801:Humans; D008024:Ligands; D009842:Oligopeptides / Q000008:administration & dosage / Q000494:pharmacology*; D051381:Rats; D044464:Receptor, PAR-2 / Q000037:antagonists & inhibitors* / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D013329:Structure-Activity Relationship
chemical_list: D016207:Cytokines; C581100:GB88 compound; D008024:Ligands; D009842:Oligopeptides; D044464:Receptor, PAR-2
keywords: GPCR; agonist; antagonist; biased signalling; cell signalling; inflammation; peptide; protease; protease inhibitor; proteinase activated receptor 2