Work

Cathepsin S Causes Inflammatory Pain via Biased Agonism of PAR2 and TRPV4

Year: 2014

Type: article

Abstract: Background: Proteases trigger inflammation and pain by cleaving protease-activated receptors (PARs) at defined sites.Results: Cathepsin S (Cat-S) cleaved PAR 2 at a unique site E 56 2T 57 , leading to G␣s-mediated cAMP accumulation and TRPV4-dependent inflammation and pain.Conclusion: Cat-S is a biased agonist of PAR 2 -and TRPV4-dependent inflammation and pain.Significance: PARs integrate responses to diverse proteases.Serine proteases such as trypsin and mast cell tryptase cleave protease-activated receptor-2 (PAR 2 ) at R 36 2S 37 and reveal a tethered ligand that excites nociceptors, causing neurogenic inflammation and pain.Whether proteases that cleave PAR 2 at distinct sites are biased agonists that also induce inflammation and pain is unexplored.Cathepsin S (Cat-S) is a lysosomal cysteine protease of antigen-presenting cells that is secreted during inflammation and which retains activity at extracellular pH.We observed that Cat-S cleaved PAR 2 at E 56 2T 57 , which removed the canonical tethered ligand and prevented trypsin activation.In HEK and KNRK cell lines and in nociceptive neurons of mouse dorsal root ganglia, Cat-S and a decapeptide mimicking the Cat-S-revealed tethered ligand-stimulated PAR 2 coupling to G␣s and formation of cAMP.In contrast to trypsin, Cat-S did not mobilize intracellular Ca 2؉ , activate ERK1/2, recruit ␤-arrestins, or induce PAR 2 endocytosis.Cat-S caused PAR 2 -dependent activation of transient receptor potential vanilloid 4 (TRPV4) in Xenopus laevis oocytes, HEK cells and nociceptive neurons, and stimulated neuronal hyperexcitability by adenylyl cyclase and protein kinase A-dependent mechanisms.Intraplantar injection of Cat-S caused inflammation and hyperalgesia in mice that was attenuated by PAR 2 or TRPV4 deletion and adenylyl cyclase inhibition.Cat-S and PAR 2 antagonists suppressed formalin-induced inflammation and pain, which implicates endogenous Cat-S and PAR 2 in inflammatory pain.Our results identify Cat-S as a biased agonist of PAR 2 that causes PAR 2 -and TRPV4-dependent inflammation and pain.They expand the role of PAR 2 as a mediator of protease-driven inflammatory pain.

Source: Journal of Biological Chemistry

DOI: 10.1074/jbc.a114.599712