Development of highly potent protease-activated receptor 2 agonists via synthetic lipid tethering

FASEB J. 2013 Apr;27(4):1498-510. doi: 10.1096/fj.12-217323. Epub 2013 Jan 4.

Abstract

Protease-activated receptor-2 (PAR₂) is a G-protein coupled receptor (GPCR) associated with a variety of pathologies. However, the therapeutic potential of PAR₂ is limited by a lack of potent and specific ligands. Following proteolytic cleavage, PAR₂ is activated through a tethered ligand. Hence, we reasoned that lipidation of peptidomimetic ligands could promote membrane targeting and thus significantly improve potency and constructed a series of synthetic tethered ligands (STLs). STLs contained a peptidomimetic PAR₂ agonist (2-aminothiazol-4-yl-LIGRL-NH₂) bound to a palmitoyl group (Pam) via polyethylene glycol (PEG) linkers. In a high-throughput physiological assay, these STL agonists displayed EC₅₀ values as low as 1.47 nM, representing a ∼200 fold improvement over the untethered parent ligand. Similarly, these STL agonists were potent activators of signaling pathways associated with PAR₂: EC₅₀ for Ca(2+) response as low as 3.95 nM; EC₅₀ for MAPK response as low as 9.49 nM. Moreover, STLs demonstrated significant improvement in potency in vivo, evoking mechanical allodynia with an EC₅₀ of 14.4 pmol. STLs failed to elicit responses in PAR2(-/-) cells at agonist concentrations of >300-fold their EC₅₀ values. Our results demonstrate that the STL approach is a powerful tool for increasing ligand potency at PAR₂ and represent opportunities for drug development at other protease activated receptors and across GPCRs.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Calcium / metabolism
  • Calcium Signaling / drug effects*
  • Cell Line / drug effects
  • Humans
  • Hyperalgesia / drug therapy
  • Ligands
  • Lipid Metabolism / drug effects*
  • Ornithine / analogs & derivatives
  • Ornithine / pharmacology
  • Palmitates / pharmacology*
  • Peptidomimetics / pharmacology*
  • Receptor, PAR-2 / agonists*
  • Structure-Activity Relationship

Substances

  • 2at-LIGRLO(PEG3-Pam)-NH2
  • Ligands
  • Palmitates
  • Peptidomimetics
  • Receptor, PAR-2
  • Ornithine
  • Calcium