Biased Signaling by Agonists of Protease Activated Receptor 2

ACS Chem Biol. 2017 May 19;12(5):1217-1226. doi: 10.1021/acschembio.6b01088. Epub 2017 Mar 14.

Abstract

Protease activated receptor 2 (PAR2) is associated with metabolism, obesity, inflammatory, respiratory and gastrointestinal disorders, pain, cancer, and other diseases. The extracellular N-terminus of PAR2 is a common target for multiple proteases, which cleave it at different sites to generate different N-termini that activate different PAR2-mediated intracellular signaling pathways. There are no synthetic PAR2 ligands that reproduce the same signaling profiles and potencies as proteases. Structure-activity relationships here for 26 compounds spanned a signaling bias over 3 log units, culminating in three small ligands as biased agonist tools for interrogating PAR2 functions. DF253 (2f-LAAAAI-NH2) triggered PAR2-mediated calcium release (EC50 2 μM) but not ERK1/2 phosphorylation (EC50 > 100 μM) in CHO cells transfected with hPAR2. AY77 (Isox-Cha-Chg-NH2) was a more potent calcium-biased agonist (EC50 40 nM, Ca2+; EC50 2 μM, ERK1/2), while its analogue AY254 (Isox-Cha-Chg-A-R-NH2) was an ERK-biased agonist (EC50 2 nM, ERK1/2; EC50 80 nM, Ca2+). Signaling bias led to different functional responses in human colorectal carcinoma cells (HT29). AY254, but not AY77 or DF253, attenuated cytokine-induced caspase 3/8 activation, promoted scratch-wound healing, and induced IL-8 secretion, all via PAR2-ERK1/2 signaling. Different ligand components were responsible for different PAR2 signaling and functions, clues that can potentially lead to drugs that modulate different pathway-selective cellular and physiological responses.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • CHO Cells
  • Calcium / metabolism
  • Cricetulus
  • HT29 Cells
  • Humans
  • Ligands
  • MAP Kinase Signaling System / drug effects
  • Receptor, PAR-2 / agonists*
  • Receptor, PAR-2 / physiology
  • Signal Transduction / drug effects*
  • Structure-Activity Relationship
  • Transfection

Substances

  • Ligands
  • Receptor, PAR-2
  • Calcium