High Affinity Fluorescent Probe for Proteinase-Activated Receptor 2 (PAR2)

Area of Science:

• Biochemistry
• Molecular Biology
• Pharmacology

Background:

• Protease-Activated Receptor 2 (PAR2) is a G protein-coupled receptor implicated in cancer and inflammatory diseases.
• Development of PAR2-targeting imaging probes is limited despite the availability of low nanomolar affinity ligands.

Purpose of the Study:

• To develop novel PAR2-targeting compounds for potential use as imaging probes.
• To identify highly potent and selective PAR2-targeting peptides with suitable conjugation handles.

Main Methods:

• Synthesis and characterization of seven novel PAR2-targeting compounds.
• Evaluation of compound potency and selectivity using biochemical assays.
• Development and characterization of a fluorescently labeled peptide probe.

Main Results:

• Four highly potent and selective PAR2-targeting peptides were identified (EC50 = 10-23 nM).
• A lead peptide probe, Isox-Cha-Chg-ARK(Sulfo-Cy5)-NH2, exhibited the highest reported potency (EC50 = 16 nM) and affinity (KD = 38 nM) for PAR2.
• The lead probe demonstrated over a 10-fold improvement in potency and binding affinity compared to previous probes.

Conclusions:

• Novel PAR2-targeting peptides with high potency and selectivity have been developed.
• The lead fluorescent peptide probe is a valuable tool for in vitro and in vivo PAR2 imaging.
• This research advances the potential for diagnostic and therapeutic applications targeting PAR2.