Neutrophil elastase and proteinase-3 trigger G protein-biased signaling through proteinase-activated receptor-1 (PAR1).
Neutrophil proteinases released at sites of inflammation can affect tissue function by either activating or disarming signal transduction mediated by proteinase-activated receptors (PARs). Because PAR1 is expressed at sites where abundant neutrophil infiltration occurs, we hypothesized that neutrophil-derived enzymes might also regulate PAR1 signaling. We report here that both neutrophil elastase and proteinase-3 cleave the human PAR1 N terminus at sites distinct from the thrombin cleavage site. This cleavage results in a disarming of thrombin-activated calcium signaling through PAR1. However, the distinct non-canonical tethered ligands unmasked by neutrophil elastase and proteinase-3, as well as synthetic peptides with sequences derived from these novel exposed tethered ligands, selectively stimulated PAR1-mediated mitogen-activated protein kinase activation. This signaling was blocked by pertussis toxin, implicating a Gαi-triggered signal pathway. We conclude that neutrophil proteinases trigger biased PAR1 signaling and we describe a novel set of tethered ligands that are distinct from the classical tethered ligand revealed by thrombin. We further demonstrate the function of this biased signaling in regulating endothelial cell barrier integrity.
From the Inflammation Research Network, Snyder Institute for Chronic Diseases, and.
Koichiro
K
Mihara
Rithwik
R
Ramachandran
Bernard
B
Renaux
Mahmoud
M
Saifeddine
Morley D
MD
Hollenberg
D045744:Cell Line, Tumor; D004789:Enzyme Activation / Q000502:physiology; D048049:Extracellular Signal-Regulated MAP Kinases / Q000235:genetics / Q000378:metabolism; D044385:GTP-Binding Protein alpha Subunits / Q000235:genetics / Q000378:metabolism*; D057809:HEK293 Cells; D006801:Humans; D019272:Leukocyte Elastase / Q000235:genetics / Q000378:metabolism*; D020935:MAP Kinase Signaling System / Q000502:physiology*; D053146:Myeloblastin / Q000235:genetics / Q000378:metabolism*; D044463:Receptor, PAR-1 / Q000235:genetics / Q000378:metabolism*; D013917:Thrombin / Q000235:genetics / Q000378:metabolism
D044385:GTP-Binding Protein alpha Subunits; D044463:Receptor, PAR-1; D048049:Extracellular Signal-Regulated MAP Kinases; D019272:Leukocyte Elastase; D013917:Thrombin; D053146:Myeloblastin
Biased Signaling; Calcium Signaling; Endothelial Cell; G Protein-coupled Receptors (GPCR); Intracellular Trafficking; MAP Kinases (MAPKs); Neutrophil; Proteinase-activated Receptor; Thrombin