Neutrophil elastase acts as a biased agonist for proteinase-activated receptor-2 (PAR ₂)

Authors

Rithwik Ramachandran, University of Calgary
Koichiro Mihara, University of Calgary
Hyunjae Chung, University of Calgary
Bernard Renaux, University of Calgary
Chang S. Lau, University of California, Riverside
Daniel A. Muruve, University of Calgary
Kathryn A. DeFea, University of California, Riverside
Michel Bouvier, University of Montreal
Morley D. Hollenberg, University of Calgary

Document Type

Article

Publication Date

7-15-2011

Journal

Journal of Biological Chemistry

Volume

286

Issue

28

First Page

24638

Last Page

24648

URL with Digital Object Identifier

10.1074/jbc.M110.201988

Abstract

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 (PAR 2). 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. Wefound that none of neutrophil elastase, cathepsin-G, and proteinase-3 can activate G q-coupled PAR 2 calcium signaling; but all of these proteinases can disarm PAR 2, releasing the N-terminal TL sequence, thereby preventing G q-coupled PAR 2 signaling by trypsin. Interestingly, elastase (but neither cathepsin-G nor proteinase-3) causes a TL-independent PAR 2-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 extracellularNterminus of PAR 2, downstream of the TL sequence, demonstrated distinct proteolytic sites for all three neutrophil-derived enzymes. We conclude that in inflammation, neutrophil proteinases can modulate PAR 2 signaling by preventing/disarming the G q/calcium signal pathway and, via elastase, can selectively activate the p44/42MAPKpathway. Our data illustrate a new mode of PAR regulation that involves biased PAR 2 signaling by neutrophil elastase and a disarming/ silencing effect of cathepsin-G and proteinase-3. © 2011 by The American Society for Biochemistry and Molecular Biology, Inc.