Neutrophil Elastase Acts as a Biased Agonist for Proteinase-activated Receptor-2 (PAR2)

• Published in: The Journal of biological chemistry Vol. 286; no. 28; pp. 24638 - 24648
• Main Authors: Ramachandran, Rithwik, Mihara, Koichiro, Chung, Hyunjae, Renaux, Bernard, Lau, Chang S., Muruve, Daniel A., DeFea, Kathryn A., Bouvier, Michel, Hollenberg, Morley D.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 15-07-2011; American Society for Biochemistry and Molecular Biology
• Subjects: Animals; Arrestins - genetics; Arrestins - metabolism; beta-Arrestins; Biased Agonist; Biased Signaling; Calcium; Calcium Signaling - drug effects; Calcium Signaling - physiology; Cathepsin G - genetics; Cathepsin G - metabolism; Elastase; G Protein-coupled Receptors (GPCRs); GTP-Binding Protein alpha Subunits, Gq-G11 - genetics; GTP-Binding Protein alpha Subunits, Gq-G11 - metabolism; HEK293 Cells; Humans; Inflammation - genetics; Inflammation - metabolism; Leukocyte Elastase; MAP Kinase Signaling System - drug effects; MAP Kinase Signaling System - physiology; MAP Kinases (MAPKs); Mitogen-Activated Protein Kinase 1 - genetics; Mitogen-Activated Protein Kinase 1 - metabolism; Mitogen-Activated Protein Kinase 3 - genetics; Mitogen-Activated Protein Kinase 3 - metabolism; Myeloblastin - genetics; Myeloblastin - metabolism; Neutrophil; Peptides - pharmacology; Protease; Protease-activated Receptors; Protein Structure, Tertiary; Proteinase-activated Receptors; Rats; Receptor, PAR-2 - agonists; Receptor, PAR-2 - genetics; Receptor, PAR-2 - metabolism; Signal Transduction; MAP Kinases (MAPKs); Protease-activated Receptors; Proteinase-activated Receptors; Calcium; Protease; Biased Agonist; Biased Signaling; Elastase; Neutrophil; G Protein-coupled Receptors (GPCRs)
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M110.201988

Human neutrophil proteinases (elastase, proteinase-3, and cathepsin-G) are released at sites of acute inflammation. We hypothesized that these inflammation-associated proteinases can affect cell signaling by targeting proteinase-activated receptor-2 (PAR2). The PAR family of G protein-coupled receptors is triggered by a unique mechanism involving the proteolytic unmasking of an N-terminal self-activating tethered ligand (TL). Proteinases can either activate PAR signaling by unmasking the TL sequence or disarm the receptor for subsequent enzyme activation by cleaving downstream from the TL sequence. We found that none of neutrophil elastase, cathepsin-G, and proteinase-3 can activate Gq-coupled PAR2 calcium signaling; but all of these proteinases can disarm PAR2, releasing the N-terminal TL sequence, thereby preventing Gq-coupled PAR2 signaling by trypsin. Interestingly, elastase (but neither cathepsin-G nor proteinase-3) causes a TL-independent PAR2-mediated activation of MAPK that, unlike the canonical trypsin activation, does not involve either receptor internalization or recruitment of β-arrestin. Cleavage of synthetic peptides derived from the extracellular N terminus of PAR2, downstream of the TL sequence, demonstrated distinct proteolytic sites for all three neutrophil-derived enzymes. We conclude that in inflammation, neutrophil proteinases can modulate PAR2 signaling by preventing/disarming the Gq/calcium signal pathway and, via elastase, can selectively activate the p44/42 MAPK pathway. Our data illustrate a new mode of PAR regulation that involves biased PAR2 signaling by neutrophil elastase and a disarming/silencing effect of cathepsin-G and proteinase-3.