Biased Signaling by Agonists of Protease Activated Receptor 2.
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 (EC502 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 (EC5040 nM, Ca2+; EC502 μM, ERK1/2), while its analogue AY254 (Isox-Cha-Chg-A-R-NH2) was an ERK-biased agonist (EC502 nM, ERK1/2; EC5080 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.
Centre for Inflammation and Disease Research and Australian Research Council Centre of Excellence in Advanced Molecular Imaging, Institute for Molecular Bioscience, The University of Queensland , Brisbane, Queensland 4072, Australia.
Yuhong
Y
Jiang
Centre for Inflammation and Disease Research and Australian Research Council Centre of Excellence in Advanced Molecular Imaging, Institute for Molecular Bioscience, The University of Queensland , Brisbane, Queensland 4072, Australia.
Mei-Kwan
MK
Yau
Centre for Inflammation and Disease Research and Australian Research Council Centre of Excellence in Advanced Molecular Imaging, Institute for Molecular Bioscience, The University of Queensland , Brisbane, Queensland 4072, Australia.
W Mei
WM
Kok
Centre for Inflammation and Disease Research and Australian Research Council Centre of Excellence in Advanced Molecular Imaging, Institute for Molecular Bioscience, The University of Queensland , Brisbane, Queensland 4072, Australia.
Junxian
J
Lim
Centre for Inflammation and Disease Research and Australian Research Council Centre of Excellence in Advanced Molecular Imaging, Institute for Molecular Bioscience, The University of Queensland , Brisbane, Queensland 4072, Australia.
Kai-Chen
KC
Wu
Centre for Inflammation and Disease Research and Australian Research Council Centre of Excellence in Advanced Molecular Imaging, Institute for Molecular Bioscience, The University of Queensland , Brisbane, Queensland 4072, Australia.
Ligong
L
Liu
Centre for Inflammation and Disease Research and Australian Research Council Centre of Excellence in Advanced Molecular Imaging, Institute for Molecular Bioscience, The University of Queensland , Brisbane, Queensland 4072, Australia.
Timothy A
TA
Hill
Centre for Inflammation and Disease Research and Australian Research Council Centre of Excellence in Advanced Molecular Imaging, Institute for Molecular Bioscience, The University of Queensland , Brisbane, Queensland 4072, Australia.
Jacky Y
JY
Suen
Centre for Inflammation and Disease Research and Australian Research Council Centre of Excellence in Advanced Molecular Imaging, Institute for Molecular Bioscience, The University of Queensland , Brisbane, Queensland 4072, Australia.
David P
0000-0002-7856-8566
DP
Fairlie
D000818:Animals; D016466:CHO Cells; D002118:Calcium / Q000378:metabolism; D003412:Cricetulus; D019073:HT29 Cells; D006801:Humans; D008024:Ligands; D020935:MAP Kinase Signaling System / Q000187:drug effects; D044464:Receptor, PAR-2 / Q000819:agonists* / Q000502:physiology; D015398:Signal Transduction / Q000187:drug effects*; D013329:Structure-Activity Relationship; D014162:Transfection
D008024:Ligands; D044464:Receptor, PAR-2; D002118:Calcium