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  • Review Article
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Targeting proteinase-activated receptors: therapeutic potential and challenges

Nature Reviews Drug Discovery volume 11, pages 69–86 (2012)Cite this article

Subjects

Key Points

  • Proteinase-activated receptors are seven-transmembrane G protein-coupled receptors with an unusual mechanism of activation involving the proteolytic unmasking of a tethered ligand.

  • Proteinase-activated receptors have been established as therapeutic targets in cardiovascular, musculoskeletal, gastrointestinal, respiratory and central nervous system pathologies.

  • Proteinase-activated receptors can be activated by multiple proteinases, and can exhibit so-called biased signalling, which is dependent on the agonist that is stimulating the receptor and on the membrane localization of the receptor.

  • Proteinase-activated receptors can be targeted for therapy using multiple strategies that include blocking the proteolytic cleavage of the receptor, interdicting the interaction between the tethered ligand and the receptor, or modulating intracellular interactions between the receptor and effectors.

Abstract

Proteinase-activated receptors (PARs), a family of four seven-transmembrane G protein-coupled receptors, act as targets for signalling by various proteolytic enzymes. PARs are characterized by a unique activation mechanism involving the proteolytic unmasking of a tethered ligand that stimulates the receptor. Given the emerging roles of these receptors in cancer as well as in disorders of the cardiovascular, musculoskeletal, gastrointestinal, respiratory and central nervous system, PARs have become attractive targets for the development of novel therapeutics. In this Review we summarize the mechanisms by which PARs modulate cell function and the roles they can have in physiology and diseases. Furthermore, we provide an overview of possible strategies for developing PAR antagonists.

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Figure 1: Mechanism of proteinase-activated receptor activation.
Figure 2: Intracellular trafficking of activated proteinase-activated receptors.
Figure 3: Proteinase-activated receptor modulators.
Figure 4: Important structural motifs regulating PAR function and strategies for modulating PARs.

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References

  1. Rieser, P. The insulin-like action of pepsin and pepsinogen. Acta Endocrinol. 54, 375–379 (1967).

    CAS  Google Scholar 

  2. Rieser, P. & Rieser, C. H. Anabolic responses of diaphragm muscle to insulin and to other pancreatic proteins. Proc. Soc. Exp. Biol. Med. 116, 669–671 (1964).

    CAS  PubMed  Google Scholar 

  3. Burger, M. M. Proteolytic enzymes initiating cell division and escape from contact inhibition of growth. Nature 227, 170–171 (1970).

    CAS  PubMed  Google Scholar 

  4. Sefton, B. M. & Rubin, H. Release from density dependent growth inhibition by proteolytic enzymes. Nature 227, 843–845 (1970).

    CAS  PubMed  Google Scholar 

  5. Chen, L. B. & Buchanan, J. M. Mitogenic activity of blood components. I. Thrombin and prothrombin. Proc. Natl Acad. Sci. USA 72, 131–135 (1975).

    CAS  PubMed  PubMed Central  Google Scholar 

  6. Carney, D. H. & Cunningham, D. D. Transmembrane action of thrombin initiates chick cell division. J. Supramol. Struct. 9, 337–350 (1978).

    CAS  PubMed  Google Scholar 

  7. Carney, D. H. & Cunningham, D. D. Initiation of chick cell division by trypsin action at the cell surface. Nature 268, 602–606 (1977).

    CAS  PubMed  Google Scholar 

  8. Coughlin, S. R. Protease-activated receptors in hemostasis, thrombosis and vascular biology. J. Thromb. Haemost. 3, 1800–1814 (2005).

    CAS  PubMed  Google Scholar 

  9. Ramachandran, R. & Hollenberg, M. D. Proteinases and signalling: pathophysiological and therapeutic implications via PARs and more. Br. J. Pharmacol. 153 (Suppl. 1), 263–282 (2008).

    Google Scholar 

  10. Adams, M. N. et al. Structure, function and pathophysiology of protease activated receptors. Pharmacol. Ther. 130, 248–282 (2011).

    CAS  PubMed  Google Scholar 

  11. Vu, T. K., Hung., D. T., Wheaton, V. I. & Coughlin, S. R. Molecular cloning of a functional thrombin receptor reveals a novel proteolytic mechanism of receptor activation. Cell 64, 1057–1068 (1991). This study described the cloning of the human thrombin receptor and identified the novel 'tethered ligand' mechanism of activation.

    CAS  PubMed  Google Scholar 

  12. Rasmussen, U. B. et al. cDNA cloning and expression of a hamster α-thrombin receptor coupled to Ca2+ mobilization. FEBS Lett. 288, 123–128 (1991). This was one of the first reports to describe the cloning and functional expression of the thrombin receptor in mammalian cells.

    CAS  PubMed  Google Scholar 

  13. Nystedt, S., Emilsson, K., Wahlestedt, C. & Sundelin, J. Molecular cloning of a potential proteinase activated receptor. Proc. Natl Acad. Sci. USA 91, 9208–9212 (1994).

    CAS  PubMed  PubMed Central  Google Scholar 

  14. Nystedt, S., Emilsson, K., Larsson, A. K., Strombeck, B. & Sundelin, J. Molecular cloning and functional expression of the gene encoding the human proteinase-activated receptor 2. Eur. J. Biochem. 232, 84–89 (1995).

    CAS  PubMed  Google Scholar 

  15. Ishihara, H. et al. Protease-activated receptor 3 is a second thrombin receptor in humans. Nature 386, 502–506 (1997).

    CAS  PubMed  Google Scholar 

  16. Kahn, M. L. et al. A dual thrombin receptor system for platelet activation. Nature 394, 690–694 (1998).

    CAS  PubMed  Google Scholar 

  17. Xu, W. F. et al. Cloning and characterization of human protease-activated receptor 4. Proc. Natl Acad. Sci. USA 95, 6642–6646 (1998).

    CAS  PubMed  PubMed Central  Google Scholar 

  18. Nakanishi-Matsui, M. et al. PAR3 is a cofactor for PAR4 activation by thrombin. Nature 404, 609–613 (2000).

    CAS  PubMed  Google Scholar 

  19. McLaughlin, J. N., Patterson, M. M. & Malik, A. B. Protease-activated receptor-3 (PAR3) regulates PAR1 signaling by receptor dimerization. Proc. Natl Acad. Sci. USA 104, 5662–5667 (2007).

    CAS  PubMed  PubMed Central  Google Scholar 

  20. Scarborough, R. M. et al. Tethered ligand agonist peptides. Structural requirements for thrombin receptor activation reveal mechanism of proteolytic unmasking of agonist function. J. Biol. Chem. 267, 13146–13149 (1992).

    CAS  PubMed  Google Scholar 

  21. Hollenberg, M. D., Saifeddine, M., Al-Ani, B. & Kawabata, A. Proteinase-activated receptors: structural requirements for activity, receptor cross-reactivity, and receptor selectivity of receptor-activating peptides. Can. J. Physiol. Pharmacol. 75, 832–841 (1997).

    CAS  PubMed  Google Scholar 

  22. McGuire, J. J., Dai, J., Andrade-Gordon, P., Triggle, C. R. & Hollenberg, M. D. Proteinase-activated receptor-2 (PAR2): vascular effects of a PAR2-derived activating peptide via a receptor different than PAR2. J. Pharmacol. Exp. Ther. 303, 985–992 (2002).

    CAS  PubMed  Google Scholar 

  23. Liu, Q. et al. The distinct roles of two GPCRs, MrgprC11 and PAR2, in itch and hyperalgesia. Sci. Signal. 4, ra45 (2011).

    CAS  PubMed  PubMed Central  Google Scholar 

  24. Defea, K. β-arrestins and heterotrimeric G-proteins: collaborators and competitors in signal transduction. Br. J. Pharmacol. 153 (Suppl. 1), 298–309 (2008).

    Google Scholar 

  25. Dulon, S. et al. Proteinase-activated receptor-2 and human lung epithelial cells: disarming by neutrophil serine proteinases. Am. J. Respir. Cell. Mol. Biol. 28, 339–346 (2003).

    CAS  PubMed  Google Scholar 

  26. Renesto, P. et al. Specific inhibition of thrombin-induced cell activation by the neutrophil proteinases elastase, cathepsin G, and proteinase 3: evidence for distinct cleavage sites within the aminoterminal domain of the thrombin receptor. Blood 89, 1944–1953 (1997).

    CAS  PubMed  Google Scholar 

  27. Ramachandran, R. et al. Neutrophil elastase acts as a biased agonist for proteinase activated receptor-2 (PAR2). J. Biol. Chem. 286, 24638–24648 (2011). This was one of the first studies to identify an endogenous proteolytic mechanism that can stimulate biased signalling through PAR2.

    CAS  PubMed  PubMed Central  Google Scholar 

  28. Rajagopal, S., Rajagopal, K. & Lefkowitz, R. J. Teaching old receptors new tricks: biasing seven-transmembrane receptors. Nature Rev. Drug Discov. 9, 373–386 (2011). This is an excellent overview of biased signalling involving GPCRs and β-arrestin.

    Google Scholar 

  29. Kenakin, T. & Miller, L. J. Seven transmembrane receptors as shapeshifting proteins: the impact of allosteric modulation and functional selectivity on new drug discovery. Pharmacol. Rev. 62, 265–304 (2010). This is a comprehensive overview of the concept of functional selectivity in GPCRs and its relevance to drug discovery.

    CAS  PubMed  PubMed Central  Google Scholar 

  30. Kenakin, T. Functional selectivity and biased receptor signaling. J. Pharmacol. Exp. Ther. 336, 296–302 (2011).

    CAS  PubMed  Google Scholar 

  31. Shapiro, M. J., Trejo, J., Zeng, D. & Coughlin, S. R. Role of the thrombin receptor's cytoplasmic tail in intracellular trafficking. Distinct determinants for agonist-triggered versus tonic internalization and intracellular localization. J. Biol. Chem. 271, 32874–32880 (1996).

    CAS  PubMed  Google Scholar 

  32. Shapiro, M. J. & Coughlin, S. R. Separate signals for agonist-independent and agonist-triggered trafficking of protease-activated receptor 1. J. Biol. Chem. 273, 29009–29014 (1998).

    CAS  PubMed  Google Scholar 

  33. Ishii, K. et al. Inhibition of thrombin receptor signaling by a G-protein coupled receptor kinase. Functional specificity among G-protein coupled receptor kinases. J. Biol. Chem. 269, 1125–1130 (1994).

    CAS  PubMed  Google Scholar 

  34. Tiruppathi, C. et al. G protein-coupled receptor kinase-5 regulates thrombin-activated signaling in endothelial cells. Proc. Natl Acad. Sci. USA 97, 7440–7445 (2000).

    CAS  PubMed  PubMed Central  Google Scholar 

  35. Wolfe, B. L., Marchese, A. & Trejo, J. Ubiquitination differentially regulates clathrin-dependent internalization of protease-activated receptor-1. J. Cell Biol. 177, 905–916 (2007).

    CAS  PubMed  PubMed Central  Google Scholar 

  36. Paing, M. M., Johnston, C. A., Siderovski, D. P. & Trejo, J. Clathrin adaptor AP2 regulates thrombin receptor constitutive internalization and endothelial cell resensitization. Mol. Cell Biol. 26, 3231–3242 (2006).

    CAS  PubMed  PubMed Central  Google Scholar 

  37. Paing, M. M., Stutts, A. B., Kohout, T. A., Lefkowitz, R. J. & Trejo, J. β-arrestins regulate protease-activated receptor-1 desensitization but not internalization or down-regulation. J. Biol. Chem. 277, 1292–1300 (2002).

    CAS  PubMed  Google Scholar 

  38. Chen, B. et al. Adaptor protein complex-2 (AP-2) and epsin-1 mediate protease-activated receptor-1 internalization via phosphorylation- and ubiquitination-dependent sorting signals. J. Biol. Chem. 286, 40760–40770 (2011).

    CAS  PubMed  PubMed Central  Google Scholar 

  39. Bohm, S. K. et al. Mechanisms of desensitization and resensitization of proteinase-activated receptor-2. J. Biol. Chem. 271, 22003–22016 (1996).

    CAS  PubMed  Google Scholar 

  40. Seatter, M. J. et al. The role of the C-terminal tail in protease-activated receptor-2-mediated Ca2+ signalling, proline-rich tyrosine kinase-2 activation, and mitogen-activated protein kinase activity. Cell Signal. 16, 21–29 (2004).

    CAS  PubMed  Google Scholar 

  41. Ricks, T. K. & Trejo, J. Phosphorylation of protease-activated receptor-2 differentially regulates desensitization and internalization. J. Biol. Chem. 284, 34444–34457 (2009).

    CAS  PubMed  PubMed Central  Google Scholar 

  42. Dery, O., Thoma, M. S., Wong, H., Grady, E. F. & Bunnett, N. W. Trafficking of proteinase-activated receptor-2 and β-arrestin-1 tagged with green fluorescent protein. β-arrestin-dependent endocytosis of a proteinase receptor. J. Biol. Chem. 274, 18524–18535 (1999).

    CAS  PubMed  Google Scholar 

  43. Hasdemir, B., Murphy, J. E., Cottrell, G. S. & Bunnett, N. W. Endosomal deubiquitinating enzymes control ubiquitination and down-regulation of protease-activated receptor 2. J. Biol. Chem. 284, 28453–28466 (2009).

    CAS  PubMed  PubMed Central  Google Scholar 

  44. Hasdemir, B., Bunnett, N. W. & Cottrell, G. S. Hepatocyte growth factor-regulated tyrosine kinase substrate (HRS) mediates post-endocytic trafficking of protease-activated receptor 2 and calcitonin receptor-like receptor. J. Biol. Chem. 282, 29646–29657 (2007).

    CAS  PubMed  Google Scholar 

  45. Shapiro, M. J., Weiss, E. J., Faruqi, T. R. & Coughlin, S. R. Protease-activated receptors 1 and 4 are shut off with distinct kinetics after activation by thrombin. J. Biol. Chem. 275, 25216–25221 (2000).

    CAS  PubMed  Google Scholar 

  46. Li, D., D'Angelo, L., Chavez, M. & Woulfe, D. S. Arrestin-2 differentially regulates PAR4 and ADP receptor signaling in platelets. J. Biol. Chem. 286, 3805–3814 (2011).

    CAS  PubMed  Google Scholar 

  47. Jacobs, S. & Cuatrecasas, P. The mobile receptor hypothesis and “cooperativity” of hormone binding. Application to insulin. Biochim. Biophys. Acta 433, 482–495 (1976).

    CAS  PubMed  Google Scholar 

  48. de Haen, C. The non-stoichiometric floating receptor model for hormone sensitive adenylyl cyclase. J. Theor. Biol. 58, 383–400 (1976).

    CAS  PubMed  Google Scholar 

  49. Urban, J. D. et al. Functional selectivity and classical concepts of quantitative pharmacology. J. Pharmacol. Exp. Ther. 320, 1–13 (2007).

    CAS  PubMed  Google Scholar 

  50. McLaughlin, J. N. et al. Functional selectivity of G protein signaling by agonist peptides and thrombin for the protease-activated receptor-1. J. Biol. Chem. 280, 25048–25059 (2005). This was one of the first studies to demonstrate clearly that different agonists could elicit distinct functional responses when acting at PAR1.

    CAS  PubMed  Google Scholar 

  51. Russo, A., Soh, U. J., Paing, M. M., Arora, P. & Trejo, J. Caveolae are required for protease-selective signaling by protease-activated receptor-1. Proc. Natl Acad. Sci. USA 106, 6393–6397 (2009).

    CAS  PubMed  PubMed Central  Google Scholar 

  52. Awasthi, V., Mandal, S. K., Papanna, V., Rao, L. V. & Pendurthi, U. R. Modulation of tissue factor–factor VIIa signaling by lipid rafts and caveolae. Arterioscler. Thromb. Vasc. Biol. 27, 1447–1455 (2007).

    CAS  PubMed  PubMed Central  Google Scholar 

  53. Hamilton, J. R., Nguyen, P. B. & Cocks, T. M. Atypical protease-activated receptor mediates endothelium-dependent relaxation of human coronary arteries. Circ. Res. 82, 1306–1311 (1998).

    CAS  PubMed  Google Scholar 

  54. Roy, S. S., Saifeddine, M., Loutzenhiser, R., Triggle, C. R. & Hollenberg, M. D. Dual endothelium-dependent vascular activities of proteinase-activated receptor-2-activating peptides: evidence for receptor heterogeneity. Br. J. Pharmacol. 123, 1434–1440 (1998).

    CAS  PubMed  PubMed Central  Google Scholar 

  55. Ballerio, R. et al. Distinct roles for PAR1- and PAR2-mediated vasomotor modulation in human arterial and venous conduits. J. Thromb. Haemost. 5, 174–180 (2007).

    CAS  PubMed  Google Scholar 

  56. Hamilton, J. R., Frauman, A. G. & Cocks, T. M. Increased expression of protease-activated receptor-2 (PAR2) and PAR4 in human coronary artery by inflammatory stimuli unveils endothelium-dependent relaxations to PAR2 and PAR4 agonists. Circ. Res. 89, 92–98 (2001).

    CAS  PubMed  Google Scholar 

  57. Moffatt, J. D. & Cocks, T. M. Endothelium-dependent and -independent responses to protease-activated receptor-2 (PAR-2) activation in mouse isolated renal arteries. Br. J. Pharmacol. 125, 591–594 (1998).

    CAS  PubMed  PubMed Central  Google Scholar 

  58. Laniyonu, A. A. & Hollenberg, M. D. Vascular actions of thrombin receptor-derived polypeptides: structure–activity profiles for contractile and relaxant effects in rat aorta. Br. J. Pharmacol. 114, 1680–1686 (1995).

    CAS  PubMed  PubMed Central  Google Scholar 

  59. Kagota, S., Chia, E. & McGuire, J. J. Preserved arterial vasodilation via endothelial protease-activated receptor-2 in obese type 2 diabetic mice. Br. J. Pharmacol. 164, 358–371 (2011).

    CAS  PubMed  PubMed Central  Google Scholar 

  60. McGuire, J. J., Van Vliet, B. N. & Halfyard, S. J. Blood pressures, heart rate and locomotor activity during salt loading and angiotensin II infusion in protease-activated receptor 2 (PAR2) knockout mice. BMC Physiol. 8, 20 (2008).

    PubMed  PubMed Central  Google Scholar 

  61. Hirano, K. & Hirano, M. Current perspective on the role of the thrombin receptor in cerebral vasospasm after subarachnoid hemorrhage. J. Pharmacol. Sci. 114, 127–133 (2010).

    CAS  PubMed  Google Scholar 

  62. Hollenberg, M. D. Novel insights into the delayed vasospasm following subarachnoid haemorrhage: importance of proteinase signalling. Br. J. Pharmacol. 30 Jun 2011 (doi:10.1111/j.1476-5381.2011.01564.x).

    Google Scholar 

  63. Kameda, K. et al. Combined argatroban and anti-oxidative agents prevents increased vascular contractility to thrombin and other ligands after subarachnoid hemorrhage. Br. J. Pharmacol. 13 May 2011 (doi:10.1111/j.1476-5381.2011.01485.x).

    Google Scholar 

  64. Hung., D. T., Vu, T. K., Wheaton, V. I., Ishii, K. & Coughlin, S. R. Cloned platelet thrombin receptor is necessary for thrombin-induced platelet activation. J. Clin. Invest. 89, 1350–1353 (1992).

    CAS  PubMed  PubMed Central  Google Scholar 

  65. Cook, J. J. et al. An antibody against the exosite of the cloned thrombin receptor inhibits experimental arterial thrombosis in the African green monkey. Circulation 91, 2961–2971 (1995).

    CAS  PubMed  Google Scholar 

  66. Kahn, M. L., Nakanishi-Matsui, M., Shapiro, M. J., Ishihara, H. & Coughlin, S. R. Protease-activated receptors 1 and 4 mediate activation of human platelets by thrombin. J. Clin. Invest. 103, 879–887 (1999).

    CAS  PubMed  PubMed Central  Google Scholar 

  67. Leger, A. J. et al. Blocking the protease-activated receptor 1–4 heterodimer in platelet-mediated thrombosis. Circulation 113, 1244–1254 (2006).

    CAS  PubMed  Google Scholar 

  68. Covic, L., Gresser, A. L. & Kuliopulos, A. Biphasic kinetics of activation and signaling for PAR1 and PAR4 thrombin receptors in platelets. Biochemistry 39, 5458–5467 (2000).

    CAS  PubMed  Google Scholar 

  69. Sevigny, L. M. et al. Protease-activated receptor-2 modulates protease-activated receptor-1-driven neointimal hyperplasia. Arterioscler. Thromb. Vasc. Biol. 31, e100–e106 (2011).

    CAS  PubMed  PubMed Central  Google Scholar 

  70. Sambrano, G. R. et al. Cathepsin G activates protease-activated receptor-4 in human platelets. J. Biol. Chem. 275, 6819–6823 (2000).

    CAS  PubMed  Google Scholar 

  71. Oikonomopoulou, K. et al. Kallikrein-mediated cell signalling: targeting proteinase-activated receptors (PARs). Biol. Chem. 387, 817–824 (2006).

    CAS  PubMed  Google Scholar 

  72. Santulli, R. J. et al. Evidence for the presence of a protease-activated receptor distinct from the thrombin receptor in human keratinocytes. Proc. Natl Acad. Sci. USA 92, 9151–9155 (1995).

    CAS  PubMed  PubMed Central  Google Scholar 

  73. Oikonomopoulou, K. et al. Proteinase-activated receptors, targets for kallikrein signaling. J. Biol. Chem. 281, 32095–32112 (2006).

    CAS  PubMed  Google Scholar 

  74. Cornelissen, I. et al. Roles and interactions among protease-activated receptors and P2ry12 in hemostasis and thrombosis. Proc. Natl Acad. Sci. USA 107, 18605–18610 (2011).

    Google Scholar 

  75. Vergnolle, N., Hollenberg, M. D., Sharkey, K. A. & Wallace, J. L. Characterization of the inflammatory response to proteinase-activated receptor-2 (PAR2)-activating peptides in the rat paw. Br. J. Pharmacol. 127, 1083–1090 (1999). This study first established a role for PAR2 in regulating peripheral inflammation.

    CAS  PubMed  PubMed Central  Google Scholar 

  76. Vergnolle, N., Hollenberg, M. D. & Wallace, J. L. Pro- and anti-inflammatory actions of thrombin: a distinct role for proteinase-activated receptor-1 (PAR1). Br. J. Pharmacol. 126, 1262–1268 (1999). This study first established a role for PAR1 in regulating peripheral inflammation.

    CAS  PubMed  PubMed Central  Google Scholar 

  77. Asfaha, S., Brussee, V., Chapman, K., Zochodne, D. W. & Vergnolle, N. Proteinase-activated receptor-1 agonists attenuate nociception in response to noxious stimuli. Br. J. Pharmacol. 135, 1101–1106 (2002).

    CAS  PubMed  PubMed Central  Google Scholar 

  78. Asfaha, S. et al. Protease-activated receptor-4: a novel mechanism of inflammatory pain modulation. Br. J. Pharmacol. 150, 176–185 (2007).

    CAS  PubMed  Google Scholar 

  79. Steinhoff, M. et al. Agonists of proteinase-activated receptor 2 induce inflammation by a neurogenic mechanism. Nature Med. 6, 151–158 (2000). This study first identified a role for neuronal PAR2 in regulating inflammatory responses.

    CAS  PubMed  Google Scholar 

  80. Vergnolle, N. et al. Proteinase-activated receptor-2 and hyperalgesia: A novel pain pathway. Nature Med. 7, 821–826 (2001).

    CAS  PubMed  Google Scholar 

  81. Russell, F. A. & McDougall, J. J. Proteinase activated receptor (PAR) involvement in mediating arthritis pain and inflammation. Inflamm. Res. 58, 119–126 (2009).

    CAS  PubMed  Google Scholar 

  82. Ferrell, W. R. et al. Essential role for proteinase-activated receptor-2 in arthritis. J. Clin. Invest. 111, 35–41 (2003). This study established PAR2 as a potential therapeutic target for joint inflammation.

    CAS  PubMed  PubMed Central  Google Scholar 

  83. Kelso, E. B. et al. Therapeutic promise of proteinase-activated receptor-2 antagonism in joint inflammation. J. Pharmacol. Exp. Ther. 316, 1017–1024 (2006). This study illustrated multiple strategies for targeting PAR2 to block the receptor-mediated inflammatory responses.

    CAS  PubMed  Google Scholar 

  84. Howell, D. C. et al. Absence of proteinase-activated receptor-1 signaling affords protection from bleomycin-induced lung inflammation and fibrosis. Am. J. Pathol. 166, 1353–1365 (2005).

    CAS  PubMed  PubMed Central  Google Scholar 

  85. Scotton, C. J. et al. Increased local expression of coagulation factor X contributes to the fibrotic response in human and murine lung injury. J. Clin. Invest. 119, 2550–2563 (2009).

    CAS  PubMed  PubMed Central  Google Scholar 

  86. Chambers, R. C., Leoni, P., Blanc-Brude, O. P., Wembridge, D. E. & Laurent, G. J. Thrombin is a potent inducer of connective tissue growth factor production via proteolytic activation of protease-activated receptor-1. J. Biol. Chem. 275, 35584–35591 (2000).

    CAS  PubMed  Google Scholar 

  87. Chambers, R. C. et al. Thrombin stimulates fibroblast procollagen production via proteolytic activation of protease-activated receptor 1. Biochem. J. 333 (Pt 1), 121–127 (1998).

    CAS  PubMed  PubMed Central  Google Scholar 

  88. Bogatkevich, G. S., Tourkina, E., Silver, R. M. & Ludwicka-Bradley, A. Thrombin differentiates normal lung fibroblasts to a myofibroblast phenotype via the proteolytically activated receptor-1 and a protein kinase C-dependent pathway. J. Biol. Chem. 276, 45184–45192 (2001).

    CAS  PubMed  Google Scholar 

  89. Riewald, M., Petrovan, R. J., Donner, A., Mueller, B. M. & Ruf, W. Activation of endothelial cell protease activated receptor 1 by the protein C pathway. Science 296, 1880–1882 (2002). This was the first study to demonstrate that biased PAR1 signalling by APC is distinct from thrombin-stimulated signalling, implying a role for APC–PAR1 signalling in sepsis.

    CAS  PubMed  Google Scholar 

  90. Riewald, M. & Ruf, W. Protease-activated receptor-1 signaling by activated protein C in cytokine-perturbed endothelial cells is distinct from thrombin signaling. J. Biol. Chem. 280, 19808–19814 (2005).

    CAS  PubMed  Google Scholar 

  91. Yasui, H. et al. Intratracheal administration of activated protein C inhibits bleomycin-induced lung fibrosis in the mouse. Am. J. Respir. Crit. Care Med. 163, 1660–1668 (2001).

    CAS  PubMed  Google Scholar 

  92. Deng, X., Mercer, P. F., Scotton, C. J., Gilchrist, A. & Chambers, R. C. Thrombin induces fibroblast CCL2/JE production and release via coupling of PAR1 to Gαq and cooperation between ERK1/2 and Rho kinase signaling pathways. Mol. Biol. Cell 19, 2520–2533 (2008).

    CAS  PubMed  PubMed Central  Google Scholar 

  93. Ando, S. et al. Proteinase-activated receptor 4 stimulation-induced epithelial-mesenchymal transition in alveolar epithelial cells. Respir. Res. 8, 31 (2007).

    PubMed  PubMed Central  Google Scholar 

  94. Ramachandran, R. et al. Inflammatory mediators modulate thrombin and cathepsin-G signaling in human bronchial fibroblasts by inducing expression of proteinase-activated receptor-4. Am. J. Physiol. Lung Cell. Mol. Physiol. 292, L788–L798 (2007).

    CAS  PubMed  Google Scholar 

  95. Ramachandran, R., Morice, A. H. & Compton, S. J. Proteinase-activated receptor 2 agonists upregulate granulocyte colony-stimulating factor, IL-8, and VCAM-1 expression in human bronchial fibroblasts. Am. J. Respir. Cell. Mol. Biol. 35, 133–141 (2006).

    CAS  PubMed  Google Scholar 

  96. Akers, I. A. et al. Mast cell tryptase stimulates human lung fibroblast proliferation via protease-activated receptor-2. Am. J. Physiol. Lung Cell. Mol. Physiol. 278, L193–L201 (2000).

    CAS  PubMed  Google Scholar 

  97. Schmidlin, F. et al. Protease-activated receptor 2 mediates eosinophil infiltration and hyperreactivity in allergic inflammation of the airway. J. Immunol. 169, 5315–5321 (2002).

    PubMed  Google Scholar 

  98. Ebeling, C. et al. Proteinase-activated receptor 2 activation in the airways enhances antigen-mediated airway inflammation and airway hyperresponsiveness through different pathways. J. Allergy Clin. Immunol. 115, 623–630 (2005).

    CAS  PubMed  Google Scholar 

  99. Ebeling, C., Lam, T., Gordon, J. R., Hollenberg, M. D. & Vliagoftis, H. Proteinase-activated receptor-2 promotes allergic sensitization to an inhaled antigen through a TNF-mediated pathway. J. Immunol. 179, 2910–2917 (2007).

    CAS  PubMed  Google Scholar 

  100. Arizmendi, N. G. et al. Mucosal allergic sensitization to cockroach allergens is dependent on proteinase activity and proteinase-activated receptor-2 activation. J. Immunol. 186, 3164–3172 (2011).

    CAS  PubMed  Google Scholar 

  101. Adam, E. et al. The house dust mite allergen Der p 1, unlike Der p 3, stimulates the expression of interleukin-8 in human airway epithelial cells via a proteinase-activated receptor-2-independent mechanism. J. Biol. Chem. 281, 6910–6923 (2006).

    CAS  PubMed  Google Scholar 

  102. Asokananthan, N. et al. Activation of protease-activated receptor (PAR)-1, PAR-2, and PAR-4 stimulates IL-6, IL-8, and prostaglandin E2 release from human respiratory epithelial cells. J. Immunol. 168, 3577–3585 (2002).

    CAS  PubMed  Google Scholar 

  103. Asokananthan, N. et al. House dust mite allergens induce proinflammatory cytokines from respiratory epithelial cells: the cysteine protease allergen, Der p 1, activates protease-activated receptor (PAR)-2 and inactivates PAR-1. J. Immunol. 169, 4572–4578 (2002).

    CAS  PubMed  Google Scholar 

  104. Page, K., Ledford, J. R., Zhou, P., Dienger, K. & Wills-Karp, M. Mucosal sensitization to German cockroach involves protease-activated receptor-2. Respir. Res. 11, 62 (2010).

    PubMed  PubMed Central  Google Scholar 

  105. Cocks, T. M. et al. A protective role for protease-activated receptors in the airways. Nature 398, 156–160 (1999). This study demonstrated that epithelial PAR2 activation can stimulate the release of tracheal relaxing prostaglandins, suggesting a protective role for PAR2 in airway inflammatory diseases.

    CAS  PubMed  Google Scholar 

  106. Moffatt, J. D., Jeffrey, K. L. & Cocks, T. M. Protease-activated receptor-2 activating peptide SLIGRL inhibits bacterial lipopolysaccharide-induced recruitment of polymorphonuclear leukocytes into the airways of mice. Am. J. Respir. Cell. Mol. Biol. 26, 680–684 (2002).

    CAS  PubMed  Google Scholar 

  107. Vergnolle, N. Clinical relevance of proteinase activated receptors (PARs) in the gut. Gut 54, 867–874 (2005).

    CAS  PubMed  PubMed Central  Google Scholar 

  108. Mule, F., Pizzuti, R., Capparelli, A. & Vergnolle, N. Evidence for the presence of functional protease activated receptor 4 (PAR4) in the rat colon. Gut 53, 229–234 (2004).

    CAS  PubMed  PubMed Central  Google Scholar 

  109. Hollenberg, M. D., Saifeddine, M., Al-Ani, B. & Gui, Y. Proteinase-activated receptor 4 (PAR4): action of PAR4-activating peptides in vascular and gastric tissue and lack of cross-reactivity with PAR1 and PAR2. Can. J. Physiol. Pharmacol. 77, 458–464 (1999).

    CAS  PubMed  Google Scholar 

  110. Buresi, M. C., Buret, A. G., Hollenberg, M. D. & MacNaughton, W. K. Activation of proteinase-activated receptor 1 stimulates epithelial chloride secretion through a unique MAP kinase- and cyclo-oxygenase-dependent pathway. FASEB J. 16, 1515–1525 (2002).

    CAS  PubMed  Google Scholar 

  111. Buresi, M. C. et al. Activation of proteinase-activated receptor-1 inhibits neurally evoked chloride secretion in the mouse colon in vitro. Am. J. Physiol. Gastrointest. Liver Physiol. 288, G337–G345 (2005).

    CAS  PubMed  Google Scholar 

  112. Kong, W. et al. Luminal trypsin may regulate enterocytes through proteinase-activated receptor 2. Proc. Natl Acad. Sci. USA 94, 8884–8889 (1997).

    CAS  PubMed  PubMed Central  Google Scholar 

  113. van der Merwe, J. Q., Hollenberg, M. D. & MacNaughton, W. K. EGF receptor transactivation and MAP kinase mediate proteinase-activated receptor-2-induced chloride secretion in intestinal epithelial cells. Am. J. Physiol. Gastrointest. Liver Physiol. 294, G441–G451 (2008).

    CAS  PubMed  Google Scholar 

  114. Lau, C., Lytle, C., Straus, D. S. & DeFea, K. A. Apical and basolateral pools of proteinase-activated receptor-2 direct distinct signaling events in the intestinal epithelium. Am. J. Physiol. Cell Physiol. 300, C113–C123 (2011).

    CAS  PubMed  Google Scholar 

  115. Chin, A. C. et al. Proteinase-activated receptor 1 activation induces epithelial apoptosis and increases intestinal permeability. Proc. Natl Acad. Sci. USA 100, 11104–11109 (2003).

    CAS  PubMed  PubMed Central  Google Scholar 

  116. Mule, F., Baffi, M. C. & Cerra, M. C. Dual effect mediated by protease-activated receptors on the mechanical activity of rat colon. Br. J. Pharmacol. 136, 367–374 (2002).

    CAS  PubMed  PubMed Central  Google Scholar 

  117. Saifeddine, M., Al-Ani, B., Sandhu, S., Wijesuriya, S. J. & Hollenberg, M. D. Contractile actions of proteinase-activated receptor-derived polypeptides in guinea-pig gastric and lung parenchymal strips: evidence for distinct receptor systems. Br. J. Pharmacol. 132, 556–566 (2001).

    CAS  PubMed  PubMed Central  Google Scholar 

  118. Mule, F., Baffi, M. C., Capparelli, A. & Pizzuti, R. Involvement of nitric oxide and tachykinins in the effects induced by protease-activated receptors in rat colon longitudinal muscle. Br. J. Pharmacol. 139, 598–604 (2003).

    CAS  PubMed  PubMed Central  Google Scholar 

  119. Zhao, A. & Shea-Donohue, T. PAR-2 agonists induce contraction of murine small intestine through neurokinin receptors. Am. J. Physiol. Gastrointest. Liver Physiol. 285, G696–G703 (2003).

    CAS  PubMed  Google Scholar 

  120. Kawabata, A. et al. In vivo evidence that protease-activated receptors 1 and 2 modulate gastrointestinal transit in the mouse. Br. J. Pharmacol. 133, 1213–1218 (2001).

    CAS  PubMed  PubMed Central  Google Scholar 

  121. Cenac, N. et al. Induction of intestinal inflammation in mouse by activation of proteinase-activated receptor-2. Am. J. Pathol. 161, 1903–1915 (2002).

    CAS  PubMed  PubMed Central  Google Scholar 

  122. Hyun, E., Andrade-Gordon, P., Steinhoff, M. & Vergnolle, N. Protease-activated receptor-2 activation: a major actor in intestinal inflammation. Gut 57, 1222–1229 (2008).

    CAS  PubMed  Google Scholar 

  123. Hyun, E., Andrade-Gordon, P., Steinhoff, M., Beck, P. L. & Vergnolle, N. Contribution of bone marrow-derived cells to the pro-inflammatory effects of protease-activated receptor-2 in colitis. Inflamm. Res. 59, 699–709 (2010).

    CAS  PubMed  PubMed Central  Google Scholar 

  124. Hansen, K. K. et al. A major role for proteolytic activity and proteinase-activated receptor-2 in the pathogenesis of infectious colitis. Proc. Natl Acad. Sci. USA 102, 8363–8368 (2005).

    CAS  PubMed  PubMed Central  Google Scholar 

  125. Cottrell, G. S. et al. Protease-activated receptor 2, dipeptidyl peptidase I, and proteases mediate Clostridium difficile toxin A enteritis. Gastroenterology 132, 2422–2437 (2007).

    CAS  PubMed  Google Scholar 

  126. Cenac, N. et al. Role for protease activity in visceral pain in irritable bowel syndrome. J. Clin. Invest. 117, 636–647 (2007).

    CAS  PubMed  PubMed Central  Google Scholar 

  127. Gecse, K. et al. Increased faecal serine protease activity in diarrhoeic IBS patients: a colonic lumenal factor impairing colonic permeability and sensitivity. Gut 57, 591–599 (2008).

    CAS  PubMed  Google Scholar 

  128. Cenac, N. et al. Proteinase-activated receptor-1 is an anti-inflammatory signal for colitis mediated by a type 2 immune response. Inflamm. Bowel Dis. 11, 792–798 (2005).

    PubMed  Google Scholar 

  129. Wee, J. L. et al. Protease-activated receptor-1 down-regulates the murine inflammatory and humoral response to Helicobacter pylori. Gastroenterology 138, 573–582 (2009).

    PubMed  Google Scholar 

  130. Fiorucci, S. et al. Proteinase-activated receptor 2 is an anti-inflammatory signal for colonic lamina propria lymphocytes in a mouse model of colitis. Proc. Natl Acad. Sci. USA 98, 13936–13941 (2001).

    CAS  PubMed  PubMed Central  Google Scholar 

  131. Cattaruzza, F. et al. Protective effect of proteinase-activated receptor 2 activation on motility impairment and tissue damage induced by intestinal ischemia/reperfusion in rodents. Am. J. Pathol. 169, 177–188 (2006).

    CAS  PubMed  PubMed Central  Google Scholar 

  132. Striggow, F. et al. Four different types of protease-activated receptors are widely expressed in the brain and are up-regulated in hippocampus by severe ischemia. Eur. J. Neurosci. 14, 595–608 (2001).

    CAS  PubMed  Google Scholar 

  133. Henrich-Noack, P., Riek-Burchardt, M., Baldauf, K., Reiser, G. & Reymann, K. G. Focal ischemia induces expression of protease-activated receptor1 (PAR1) and PAR3 on microglia and enhances PAR4 labeling in the penumbra. Brain Res. 1070, 232–241 (2006).

    CAS  PubMed  Google Scholar 

  134. Suo, Z., Wu, M., Citron, B. A., Gao, C. & Festoff, B. W. Persistent protease-activated receptor 4 signaling mediates thrombin-induced microglial activation. J. Biol. Chem. 278, 31177–31183 (2003).

    CAS  PubMed  Google Scholar 

  135. Wang, H., Ubl, J. J. & Reiser, G. Four subtypes of protease-activated receptors, co-expressed in rat astrocytes, evoke different physiological signaling. Glia 37, 53–63 (2002).

    CAS  PubMed  Google Scholar 

  136. Scarisbrick, I. A., Isackson, P. J., Ciric, B., Windebank, A. J. & Rodriguez, M. MSP, a trypsin-like serine protease, is abundantly expressed in the human nervous system. J. Comp. Neurol. 431, 347–361 (2001).

    CAS  PubMed  Google Scholar 

  137. Bernett, M. J. et al. Crystal structure and biochemical characterization of human kallikrein 6 reveals that a trypsin-like kallikrein is expressed in the central nervous system. J. Biol. Chem. 277, 24562–24570 (2002).

    CAS  PubMed  Google Scholar 

  138. Sokolova, E. & Reiser, G. Prothrombin/thrombin and the thrombin receptors PAR-1 and PAR-4 in the brain: localization, expression and participation in neurodegenerative diseases. Thromb. Haemost. 100, 576–581 (2008).

    CAS  PubMed  Google Scholar 

  139. Yoshida, S. & Shiosaka, S. Plasticity-related serine proteases in the brain. Int. J. Mol. Med. 3, 405–409 (1999).

    CAS  PubMed  Google Scholar 

  140. Turgeon, V. L. & Houenou, L. J. The role of thrombin-like (serine) proteases in the development, plasticity and pathology of the nervous system. Brain Res. Brain Res. Rev. 25, 85–95 (1997).

    CAS  PubMed  Google Scholar 

  141. Noorbakhsh, F., Vergnolle, N., Hollenberg, M. D. & Power, C. Proteinase-activated receptors in the nervous system. Nature Rev. Neurosci. 4, 981–990 (2003).

    CAS  Google Scholar 

  142. Luo, W., Wang, Y. & Reiser, G. Protease-activated receptors in the brain: receptor expression, activation, and functions in neurodegeneration and neuroprotection. Brain Res. Rev. 56, 331–345 (2007).

    CAS  PubMed  Google Scholar 

  143. Vaughan, P. J., Pike, C. J., Cotman, C. W. & Cunningham, D. D. Thrombin receptor activation protects neurons and astrocytes from cell death produced by environmental insults. J. Neurosci. 15, 5389–5401 (1995).

    CAS  PubMed  PubMed Central  Google Scholar 

  144. Donovan, F. M., Pike, C. J., Cotman, C. W. & Cunningham, D. D. Thrombin induces apoptosis in cultured neurons and astrocytes via a pathway requiring tyrosine kinase and RhoA activities. J. Neurosci. 17, 5316–5326 (1997).

    CAS  PubMed  PubMed Central  Google Scholar 

  145. Acharjee, S. et al. Proteinase-activated receptor-1 mediates dorsal root ganglion neuronal degeneration in HIV/AIDS. Brain 134, 3209–3221 (2011).

    PubMed  PubMed Central  Google Scholar 

  146. Gan, J., Greenwood, S. M., Cobb, S. R. & Bushell, T. J. Indirect modulation of neuronal excitability and synaptic transmission in the hippocampus by activation of proteinase-activated receptor-2. Br. J. Pharmacol. 163, 984–994 (2011).

    CAS  PubMed  PubMed Central  Google Scholar 

  147. Lohman, R. J., O'Brien, T. J. & Cocks, T. M. Protease-activated receptor-2 regulates trypsin expression in the brain and protects against seizures and epileptogenesis. Neurobiol. Dis. 30, 84–93 (2008).

    CAS  PubMed  Google Scholar 

  148. Lohman, R. J., Jones, N. C., O'Brien, T. J. & Cocks, T. M. A regulatory role for protease-activated receptor-2 in motivational learning in rats. Neurobiol. Learn. Mem. 92, 301–309 (2009).

    CAS  PubMed  Google Scholar 

  149. Junge, C. E. et al. The contribution of protease-activated receptor 1 to neuronal damage caused by transient focal cerebral ischemia. Proc. Natl Acad. Sci. USA 100, 13019–13024 (2003).

    CAS  PubMed  PubMed Central  Google Scholar 

  150. Hamill, C. E., Mannaioni, G., Lyuboslavsky, P., Sastre, A. A. & Traynelis, S. F. Protease-activated receptor 1-dependent neuronal damage involves NMDA receptor function. Exp. Neurol. 217, 136–146 (2009).

    CAS  PubMed  PubMed Central  Google Scholar 

  151. Xue, M., Hollenberg, M. D., Demchuk, A. & Yong, V. W. Relative importance of proteinase-activated receptor-1 versus matrix metalloproteinases in intracerebral hemorrhage-mediated neurotoxicity in mice. Stroke 40, 2199–2204 (2009).

    CAS  PubMed  Google Scholar 

  152. Boven, L. A. et al. Up-regulation of proteinase-activated receptor 1 expression in astrocytes during HIV encephalitis. J. Immunol. 170, 2638–2646 (2003). This was one of the first studies to show that PAR1 can be involved in CNS neurotoxicity.

    CAS  PubMed  Google Scholar 

  153. Hamill, C. E. et al. Exacerbation of dopaminergic terminal damage in a mouse model of Parkinson's disease by the G-protein-coupled receptor protease-activated receptor 1. Mol. Pharmacol. 72, 653–664 (2007).

    CAS  PubMed  Google Scholar 

  154. Lee, E. J. et al. α-synuclein activates microglia by inducing the expressions of matrix metalloproteinases and the subsequent activation of protease-activated receptor-1. J. Immunol. 185, 615–623 (2010).

    CAS  PubMed  Google Scholar 

  155. Nicole, O. et al. Activation of protease-activated receptor-1 triggers astrogliosis after brain injury. J. Neurosci. 25, 4319–4329 (2005).

    CAS  PubMed  PubMed Central  Google Scholar 

  156. Wang, Y., Luo, W., Stricker, R. & Reiser, G. Protease-activated receptor-1 protects rat astrocytes from apoptotic cell death via JNK-mediated release of the chemokine GRO/CINC-1. J. Neurochem. 98, 1046–1060 (2006).

    CAS  PubMed  Google Scholar 

  157. Thiyagarajan, M., Fernandez, J. A., Lane, S. M., Griffin, J. H. & Zlokovic, B. V. Activated protein C promotes neovascularization and neurogenesis in postischemic brain via protease-activated receptor 1. J. Neurosci. 28, 12788–12797 (2008).

    CAS  PubMed  PubMed Central  Google Scholar 

  158. Noorbakhsh, F. et al. Proteinase-activated receptor-2 induction by neuroinflammation prevents neuronal death during HIV infection. J. Immunol. 174, 7320–7329 (2005).

    CAS  PubMed  Google Scholar 

  159. Noorbakhsh, F. et al. Proteinase-activated receptor 2 modulates neuroinflammation in experimental autoimmune encephalomyelitis and multiple sclerosis. J. Exp. Med. 203, 425–435 (2006).

    PubMed  PubMed Central  Google Scholar 

  160. Afkhami-Goli, A. et al. Proteinase-activated receptor-2 exerts protective and pathogenic cell type-specific effects in Alzheimer's disease. J. Immunol. 179, 5493–5503 (2007).

    CAS  PubMed  Google Scholar 

  161. Jin, G. et al. Deficiency of PAR-2 gene increases acute focal ischemic brain injury. J. Cereb. Blood Flow Metab. 25, 302–313 (2005).

    CAS  PubMed  Google Scholar 

  162. Mao, Y., Zhang, M., Tuma, R. F. & Kunapuli, S. P. Deficiency of PAR4 attenuates cerebral ischemia/reperfusion injury in mice. J. Cereb. Blood Flow Metab. 30, 1044–1052 (2010).

    CAS  PubMed  PubMed Central  Google Scholar 

  163. Guo, H. et al. Activated protein C prevents neuronal apoptosis via protease activated receptors 1 and 3. Neuron 41, 563–572 (2004).

    CAS  PubMed  Google Scholar 

  164. Even-Ram, S. C. et al. Tumor cell invasion is promoted by activation of protease activated receptor-1 in cooperation with the αvβ5 integrin. J. Biol. Chem. 276, 10952–10962 (2001).

    CAS  PubMed  Google Scholar 

  165. Even-Ram, S. et al. Thrombin receptor overexpression in malignant and physiological invasion processes. Nature Med. 4, 909–914 (1998).

    CAS  PubMed  Google Scholar 

  166. Bar-Shavit, R. et al. PAR1 plays a role in epithelial malignancies: transcriptional regulation and novel signaling pathway. IUBMB Life 63, 397–402 (2011).

    CAS  PubMed  Google Scholar 

  167. Nyberg, P., Ylipalosaari, M., Sorsa, T. & Salo, T. Trypsins and their role in carcinoma growth. Exp. Cell Res. 312, 1219–1228 (2006).

    CAS  PubMed  Google Scholar 

  168. Soreide, K., Janssen, E. A., Korner, H. & Baak, J. P. Trypsin in colorectal cancer: molecular biological mechanisms of proliferation, invasion, and metastasis. J. Pathol. 209, 147–156 (2006).

    CAS  PubMed  Google Scholar 

  169. Zwicker, J. I., Furie, B. C. & Furie, B. Cancer-associated thrombosis. Crit. Rev. Oncol. Hematol. 62, 126–136 (2007).

    PubMed  Google Scholar 

  170. Rickles, F. R. Mechanisms of cancer-induced thrombosis in cancer. Pathophysiol. Haemost. Thromb. 35, 103–110 (2006).

    PubMed  Google Scholar 

  171. Trivedi, V. et al. Platelet matrix metalloprotease-1 mediates thrombogenesis by activating PAR1 at a cryptic ligand site. Cell 137, 332–343 (2009). This study showed that enzymes other than serine proteinases can activate PAR1 signalling by unmasking a non-canonical tethered ligand.

    CAS  PubMed  PubMed Central  Google Scholar 

  172. Boire, A. et al. PAR1 is a matrix metalloprotease-1 receptor that promotes invasion and tumorigenesis of breast cancer cells. Cell 120, 303–313 (2005).

    CAS  PubMed  Google Scholar 

  173. Salah, Z. et al. Identification of a novel functional androgen response element within hPar1 promoter: implications to prostate cancer progression. FASEB J. 19, 62–72 (2005).

    CAS  PubMed  Google Scholar 

  174. Ramsay, A. J. et al. Kallikrein-related peptidase 4 (KLK4) initiates intracellular signaling via protease-activated receptors (PARs). KLK4 and PAR-2 are co-expressed during prostate cancer progression. J. Biol. Chem. 283, 12293–12304 (2008).

    CAS  PubMed  Google Scholar 

  175. Gratio, V. et al. Kallikrein-related peptidase 14 acts on proteinase-activated receptor 2 to induce signaling pathway in colon cancer cells. Am. J. Pathol. 179, 2625–2636 (2011).

    CAS  PubMed  PubMed Central  Google Scholar 

  176. Gratio, V. et al. Kallikrein-related peptidase 4: a new activator of the aberrantly expressed protease-activated receptor 1 in colon cancer cells. Am. J. Pathol. 176, 1452–1461 (2010).

    CAS  PubMed  PubMed Central  Google Scholar 

  177. Krenzer, S. et al. Expression and function of the kallikrein-related peptidase 6 in the human melanoma microenvironment. J. Invest. Dermatol. 131, 2281–2288 (2011).

    CAS  PubMed  PubMed Central  Google Scholar 

  178. Wang, J., Boerma, M., Kulkarni, A., Hollenberg, M. D. & Hauer-Jensen, M. Activation of protease activated receptor 2 by exogenous agonist exacerbates early radiation injury in rat intestine. Int. J. Radiat. Oncol. Biol. Phys. 77, 1206–1212 (2010).

    CAS  PubMed  PubMed Central  Google Scholar 

  179. Vergnolle, N. Protease-activated receptors as drug targets in inflammation and pain. Pharmacol. Ther. 123, 292–309 (2009).

    CAS  PubMed  Google Scholar 

  180. Sevigny, L. M. et al. Interdicting protease-activated receptor-2-driven inflammation with cell-penetrating pepducins. Proc. Natl Acad. Sci. USA 108, 8491–8496 (2011). This was one of the first studies to provide proof of concept that PAR2 pepducin antagonists are able to inhibit inflammatory responses in vivo.

    CAS  PubMed  PubMed Central  Google Scholar 

  181. Dowal, L. et al. Identification of an antithrombotic allosteric modulator that acts through helix 8 of PAR1. Proc. Natl Acad. Sci. USA 108, 2951–2956 (2011).

    CAS  PubMed  PubMed Central  Google Scholar 

  182. Ruda, E. M., Scrutton, M. C., Manley, P. W. & Tuffin, D. P. Thrombin receptor antagonists: structure-activity relationships for the platelet thrombin receptor and effects on prostacyclin synthesis by human umbilical vein endothelial cells. Biochem. Pharmacol. 39, 373–381 (1990).

    CAS  PubMed  Google Scholar 

  183. Ruda, E. M., Petty, A., Scrutton, M. C., Tuffin, D. P. & Manley, P. W. Identification of small peptide analogues having agonist and antagonist activity at the platelet thrombin receptor. Biochem. Pharmacol. 37, 2417–2426 (1988).

    CAS  PubMed  Google Scholar 

  184. Andrade-Gordon, P. et al. Design, synthesis, and biological characterization of a peptide-mimetic antagonist for a tethered-ligand receptor. Proc. Natl Acad. Sci. USA 96, 12257–12262 (1999). This study reported the first successful synthesis and use of a PAR1-targeted peptidomimetic antagonist.

    CAS  PubMed  PubMed Central  Google Scholar 

  185. Maryanoff, B. E., Zhang, H. C., Andrade-Gordon, P. & Derian, C. K. Discovery of potent peptide-mimetic antagonists for the human thrombin receptor, protease-activated receptor-1 (PAR-1). Curr. Med. Chem. Cardiovasc. Hematol. Agents 1, 13–36 (2003).

    CAS  PubMed  Google Scholar 

  186. Andrade-Gordon, P. et al. Administration of a potent antagonist of protease-activated receptor-1 (PAR-1) attenuates vascular restenosis following balloon angioplasty in rats. J. Pharmacol. Exp. Ther. 298, 34–42 (2001).

    CAS  PubMed  Google Scholar 

  187. Derian, C. K. et al. Blockade of the thrombin receptor protease-activated receptor-1 with a small-molecule antagonist prevents thrombus formation and vascular occlusion in nonhuman primates. J. Pharmacol. Exp. Ther. 304, 855–861 (2003).

    CAS  PubMed  Google Scholar 

  188. Chackalamannil, S. et al. Discovery of potent orally active thrombin receptor (protease activated receptor 1) antagonists as novel antithrombotic agents. J. Med. Chem. 48, 5884–5887 (2005).

    CAS  PubMed  Google Scholar 

  189. Chackalamannil, S. et al. Discovery of a novel, orally active himbacine-based thrombin receptor antagonist (SCH 530348) with potent antiplatelet activity. J. Med. Chem. 51, 3061–3064 (2008).

    CAS  PubMed  Google Scholar 

  190. Becker, R. C. et al. Safety and tolerability of SCH 530348 in patients undergoing non-urgent percutaneous coronary intervention: a randomised, double-blind, placebo-controlled Phase II study. Lancet 373, 919–928 (2009).

    CAS  PubMed  Google Scholar 

  191. TRA*CER, Executive and Steering Committees. The thrombin receptor antagonist for clinical event reduction in acute coronary syndrome (TRA*CER) trial: study design and rationale. Am. Heart J. 158, 327–334 (2009).

  192. Morrow, D. A. et al. Evaluation of a novel antiplatelet agent for secondary prevention in patients with a history of atherosclerotic disease: design and rationale for the thrombin-receptor antagonist in secondary prevention of atherothrombotic ischemic events (TRA 2 ˚P)-TIMI 50 trial. Am. Heart J. 158, 335–341 (2009).

    CAS  PubMed  Google Scholar 

  193. Tricoci, P. et al. Thrombin-receptor antagonist vorapaxar in acute coronary syndromes. 13 Nov 2011 (doi:10.1056/NEJMoa1109719).

    CAS  Google Scholar 

  194. Feistritzer, C. & Riewald, M. Endothelial barrier protection by activated protein C through PAR1-dependent sphingosine 1-phosphate receptor-1 crossactivation. Blood 105, 3178–3184 (2005).

    CAS  PubMed  Google Scholar 

  195. Schuepbach, R. A., Feistritzer, C., Fernandez, J. A., Griffin, J. H. & Riewald, M. Protection of vascular barrier integrity by activated protein C in murine models depends on protease-activated receptor-1. Thromb. Haemost. 101, 724–733 (2009).

    CAS  PubMed  PubMed Central  Google Scholar 

  196. Kaneider, N. C. et al. 'Role reversal' for the receptor PAR1 in sepsis-induced vascular damage. Nature Immunol. 8, 1303–1312 (2007).

    CAS  Google Scholar 

  197. Serebruany, V. L., Kogushi, M., Dastros-Pitei, D., Flather, M. & Bhatt, D. L. The in-vitro effects of E5555, a protease-activated receptor (PAR)-1 antagonist, on platelet biomarkers in healthy volunteers and patients with coronary artery disease. Thromb. Haemost. 102, 111–119 (2009).

    CAS  PubMed  Google Scholar 

  198. O'Donoghue, M. L. et al. Safety and tolerability of atopaxar in the treatment of patients with acute coronary syndromes: the lessons from antagonizing the cellular effects of thrombin–acute coronary syndromes trial. Circulation 123, 1843–1853 (2011).

    CAS  PubMed  Google Scholar 

  199. Wiviott, S. D. et al. Randomized trial of atopaxar in the treatment of patients with coronary artery disease: the lessons from antagonizing the cellular effect of thrombin–coronary artery disease trial. Circulation 123, 1854–1863 (2011).

    CAS  PubMed  Google Scholar 

  200. Goto, S., Ogawa, H., Takeuchi, M., Flather, M. D. & Bhatt, D. L. Double-blind, placebo-controlled Phase II studies of the protease-activated receptor 1 antagonist E5555 (atopaxar) in Japanese patients with acute coronary syndrome or high-risk coronary artery disease. Eur. Heart J. 31, 2601–2613 (2010).

    CAS  PubMed  PubMed Central  Google Scholar 

  201. Chieng-Yane, P. et al. Protease-activated receptor-1 antagonist F 16618 reduces arterial restenosis by down-regulation of tumor necrosis factor α and matrix metalloproteinase 7 expression, migration, and proliferation of vascular smooth muscle cells. J. Pharmacol. Exp. Ther. 336, 643–651 (2011).

    CAS  PubMed  Google Scholar 

  202. Perez, M. et al. Discovery of novel protease activated receptors 1 antagonists with potent antithrombotic activity in vivo. J. Med. Chem. 52, 5826–5836 (2009).

    CAS  PubMed  Google Scholar 

  203. Planty, B. et al. Exploration of a new series of PAR1 antagonists. Bioorg. Med. Chem. Lett. 20, 1735–1739 (2010).

    CAS  PubMed  Google Scholar 

  204. Al-Ani, B., Saifeddine, M., Wijesuriya, S. J. & Hollenberg, M. D. Modified proteinase-activated receptor-1 and -2 derived peptides inhibit proteinase-activated receptor-2 activation by trypsin. J. Pharmacol. Exp. Ther. 300, 702–708 (2002).

    CAS  PubMed  Google Scholar 

  205. Goh, F. G., Ng, P. Y., Nilsson, M., Kanke, T. & Plevin, R. Dual effect of the novel peptide antagonist K-14585 on proteinase-activated receptor-2-mediated signalling. Br. J. Pharmacol. 158, 1695–1704 (2009).

    CAS  PubMed  PubMed Central  Google Scholar 

  206. Lohman, R. J. et al. Antagonism of protease activated receptor 2 protects against experimental colitis. J. Pharmacol. Exp. Ther. 25 Oct 2011 (doi:10.1124/jpet.111.187062). This was one of the first studies to show that in vivo pharmacological targeting of PAR2 with a small-molecule peptidomimetic antagonist attenuates experimental colitis.

    Google Scholar 

  207. Barry, G. D. et al. Novel agonists and antagonists for human protease activated receptor 2. J. Med. Chem. 53, 7428–7440 (2010).

    CAS  PubMed  Google Scholar 

  208. Suen, J. Y., Gardiner, B., Grimmond, S. & Fairlie, D. P. Profiling gene expression induced by protease-activated receptor 2 (PAR2) activation in human kidney cells. PLoS ONE 5, e13809 (2010).

    PubMed  PubMed Central  Google Scholar 

  209. Suen, J. Y. Regulating Protease Activated Receptor 2. Thesis, Univ. Queensland, Brisbane, Australia (2009).

    Google Scholar 

  210. Hollenberg, M. D. & Saifeddine, M. Proteinase-activated receptor 4 (PAR4): activation and inhibition of rat platelet aggregation by PAR4-derived peptides. Can. J. Physiol. Pharmacol. 79, 439–442 (2001).

    CAS  PubMed  Google Scholar 

  211. Wu, C. C. et al. Selective inhibition of protease-activated receptor 4-dependent platelet activation by YD-3. Thromb. Haemost. 87, 1026–1033 (2002).

    CAS  PubMed  Google Scholar 

  212. Wu, C. C. et al. The role of PAR4 in thrombin-induced thromboxane production in human platelets. Thromb. Haemost. 90, 299–308 (2003).

    CAS  PubMed  Google Scholar 

  213. Al-Ani, B. et al. Proteinase-activated receptor 2 (PAR(2)): development of a ligand-binding assay correlating with activation of PAR(2) by PAR(1)- and PAR(2)-derived peptide ligands. J. Pharmacol. Exp. Ther. 290, 753–760 (1999).

    CAS  PubMed  Google Scholar 

  214. O'Brien, P. J. et al. Thrombin responses in human endothelial cells. Contributions from receptors other than PAR1 include the transactivation of PAR2 by thrombin-cleaved PAR1. J. Biol. Chem. 275, 13502–13509 (2000).

    CAS  PubMed  Google Scholar 

  215. Tressel, S. L. et al. Pharmacology, biodistribution, and efficacy of GPCR-based pepducins in disease models. Methods Mol. Biol. 683, 259–275 (2010).

    Google Scholar 

  216. Covic, L., Misra, M., Badar, J., Singh, C. & Kuliopulos, A. Pepducin-based intervention of thrombin-receptor signaling and systemic platelet activation. Nature Med. 8, 1161–1165 (2002). This was one of the first studies to demonstrate the utility of intracellular targeting of PARs as a strategy for modulating signalling and cellular responses through these receptors.

    CAS  PubMed  Google Scholar 

  217. Covic, L., Gresser, A. L., Talavera, J., Swift, S. & Kuliopulos, A. Activation and inhibition of G protein-coupled receptors by cell-penetrating membrane-tethered peptides. Proc. Natl Acad. Sci. USA 99, 643–648 (2002).

    CAS  PubMed  PubMed Central  Google Scholar 

  218. Yang, E. et al. Blockade of PAR1 signaling with cell-penetrating pepducins inhibits Akt survival pathways in breast cancer cells and suppresses tumor survival and metastasis. Cancer Res. 69, 6223–6231 (2009).

    CAS  PubMed  PubMed Central  Google Scholar 

  219. Kenakin, T. P. Cellular assays as portals to seven-transmembrane receptor-based drug discovery. Nature Rev. Drug Discov. 8, 617–626 (2009). This is an excellent review discussing novel screening methods for targeting the functional selectivity of GPCRs in drug discovery.

    CAS  Google Scholar 

  220. Hanyaloglu, A. C. & von Zastrow, M. Regulation of GPCRs by endocytic membrane trafficking and its potential implications. Annu. Rev. Pharmacol. Toxicol. 48, 537–568 (2008).

    CAS  PubMed  Google Scholar 

  221. Marchese, A., Paing, M. M., Temple, B. R. & Trejo, J. G protein-coupled receptor sorting to endosomes and lysosomes. Annu. Rev. Pharmacol. Toxicol. 48, 601–629 (2008).

    CAS  PubMed  PubMed Central  Google Scholar 

  222. Chen, C. H., Paing, M. M. & Trejo, J. Termination of protease-activated receptor-1 signaling by β-arrestins is independent of receptor phosphorylation. J. Biol. Chem. 279, 10020–10031 (2004).

    CAS  PubMed  Google Scholar 

  223. Paing, M. M., Temple, B. R. & Trejo, J. A tyrosine-based sorting signal regulates intracellular trafficking of protease-activated receptor-1: multiple regulatory mechanisms for agonist-induced G protein-coupled receptor internalization. J. Biol. Chem. 279, 21938–21947 (2004).

    CAS  PubMed  Google Scholar 

  224. Wang, Y., Zhou, Y., Szabo, K., Haft, C. R. & Trejo, J. Down-regulation of protease-activated receptor-1 is regulated by sorting nexin 1. Mol. Biol. Cell 13, 1965–1976 (2002).

    CAS  PubMed  PubMed Central  Google Scholar 

  225. Swift, S. et al. A novel protease-activated receptor-1 interactor, bicaudal D1, regulates G protein signaling and internalization. J. Biol. Chem. 285, 11402–11410 (2010).

    CAS  PubMed  PubMed Central  Google Scholar 

  226. Defea, K., Schmidlin, F., Dery, O., Grady, E. F. & Bunnett, N. W. Mechanisms of initiation and termination of signalling by neuropeptide receptors: a comparison with the proteinase-activated receptors. Biochem. Soc. Trans. 28, 419–426 (2000).

    CAS  PubMed  Google Scholar 

  227. Roosterman, D., Schmidlin, F. & Bunnett, N. W. Rab5a and rab11a mediate agonist-induced trafficking of protease-activated receptor 2. Am. J. Physiol. Cell Physiol. 284, C1319–C1329 (2003).

    CAS  PubMed  Google Scholar 

  228. Bernatowicz, M. S. et al. Development of potent thrombin receptor antagonist peptides. J. Med. Chem. 39, 4879–4887 (1996).

    CAS  PubMed  Google Scholar 

  229. Damiano, B. P., Derian, C. K., Maryanoff, B. E., Zhang, H. C. & Gordon, P. A. RWJ-58259: a selective antagonist of protease activated receptor-1. Cardiovasc. Drug Rev. 21, 313–326 (2003).

    CAS  PubMed  Google Scholar 

  230. Kato, Y. et al. Inhibition of arterial thrombosis by a protease-activated receptor 1 antagonist, FR171113, in the guinea pig. Eur. J. Pharmacol. 473, 163–169 (2003).

    CAS  PubMed  Google Scholar 

  231. Suen, J. Y. et al. Modulating human proteinase activated receptor 2 with a novel antagonist (GB88) and agonist (GB110). Br. J. Pharmacol. 1 Aug 2011 (doi:10.1111/j.1476-5381.2011.01610.x).

    CAS  PubMed  PubMed Central  Google Scholar 

  232. Gardell, L. R. et al. Identification and characterization of novel small-molecule protease-activated receptor 2 agonists. J. Pharmacol. Exp. Ther. 327, 799–808 (2008).

    CAS  PubMed  Google Scholar 

  233. Kanke, T. et al. Novel antagonists for proteinase-activated receptor 2: inhibition of cellular and vascular responses in vitro and in vivo. Br. J. Pharmacol. 158, 361–371 (2009).

    CAS  PubMed  PubMed Central  Google Scholar 

  234. Chen, H. S. et al. Synthesis and antiplatelet activity of ethyl 4-(1-benzyl-1H-indazol-3-yl)benzoate (YD-3) derivatives. Bioorg. Med. Chem. 16, 1262–1278 (2008).

    CAS  PubMed  Google Scholar 

  235. Wu, C. C. et al. YD-3, a novel inhibitor of protease-induced platelet activation. Br. J. Pharmacol. 130, 1289–1296 (2000).

    CAS  PubMed  PubMed Central  Google Scholar 

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Acknowledgements

We acknowledge support from the Canadian Institutes of Health Research (M.D.H.), The Alberta Heritage Foundation for Medical Research (now known as Alberta Innovates Health Solutions; postdoctoral fellowship for R.R.) and the US National Institutes of Health (K.D.). We are indebted to the three reviewers for their insightful suggestions that have helped to clarify the text of this Review.

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Authors and Affiliations

  1. Department of Physiology and Pharmacology, Faculty of Medicine, University of Calgary, Alberta, T2N 4N1, Canada

    Rithwik Ramachandran, Farshid Noorbakhsh & Morley D. Hollenberg

  2. Department of Immunology, Faculty of Medicine, Tehran University of Medical Sciences, Tehran, 14176, Iran

    Farshid Noorbakhsh

  3. University of California Riverside, 900 University Ave., Riverside, 92521, California, USA

    Kathryn DeFea

  4. Department of Medicine, Faculty of Medicine, University of Calgary, Alberta, T2N 4N1, Canada

    Morley D. Hollenberg

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  1. Rithwik Ramachandran
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Glossary

Proteinases

Also known as proteases. Enzymes that catalyse the hydrolysis of peptide bonds. For peptide bond hydrolysis by serine proteinases, the amino acid serine forms a key transition-state intermediate within the catalytic triad, along with histidine and aspartic acid.

G protein-coupled receptors

Putative seven-transmembrane-spanning receptors that act as a GDP–GTP exchange factors for a class of guanine nucleotide-binding signal-transducing G protein heterotrimers (α, β or γ).

Antagonists

Compounds that bind to receptors to inhibit signalling caused by the binding of an endogenous ligand to the receptor. The term can be subcategorized to describe neutral antagonists, partial agonists and inverse agonists.

Agonists

Ligands that activate cell signalling following receptor binding to stimulate either complete or restricted cell responses that are dependent on their ability to drive receptor interactions with multiple signal effectors.

Tethered ligand

A proteolytically revealed extracellular amino-terminal proteinase-activated receptor sequence that, while remaining attached to the receptor carboxy-terminal sequence, can bind to other receptor extracellular domains to initiate cell signalling.

G protein

A heterotrimeric protein, consisting of α-, β- and γ-subunits, that has GTPase activity. Exchange of GDP for GTP triggers the activity of membrane-localized signal effectors such as adenylyl cyclase, and the G protein is recycled to its ground state as GTP is hydrolysed to GDP.

β-arrestin

A multifunctional adaptor protein that is important in regulating desensitization and signalling by seven-transmembrane G protein-coupled receptors and other transmembrane receptors.

Floating or 'mobile' receptor hypothesis

A model of receptor function proposing that a receptor's mobility along with the agonist-mediated changes in its conformation can promote receptor interactions with multiple effectors to trigger a complex array of effector-driven cell responses.

Tissue factor

A cell surface glycoprotein (also termed coagulation factor III) that forms a high-affinity complex with factor VIIa. In turn, the tissue factor–factor VIIa–factor Xa serine proteinase complex comprises the 'extrinsic coagulation pathway' generating thrombin and also activating the proteinase-activated receptors.

Factor VIIa

This activated form of the vitamin K-dependent serine proteinase coagulation factor VII, bound to tissue factor, activates coagulation factor X (to factor Xa) that in turn converts prothrombin to thrombin.

Thrombus

A blood clot of platelets, fibrin and entrapped erythrocytes, generated by the coagulation cascade in a blood vessel or a cardiac cavity. The thrombus can cause blood vessel occlusion, thereby hindering blood flow.

Ussing chamber

Invented by Hans Ussing in the 1950s. A two-chamber apparatus that measures current flow across an epithelial tissue or cultured cell monolayer, supported in the middle on a semi-permeable membrane. The short-circuit current required to cancel the voltage difference between the two chambers represents the net ion transport across the sample.

Pepducin

An N-palmitoylated cell-permeable peptide derived from sequences of the intracellular domain of G protein-coupled receptors (GPCRs) that is able to mimic the intracellular domains of a receptor to interdict the binding of a GPCR with its signal-transducing effectors.

Caveolae

Caveolin-rich 'cave-like' subdomains within lipid rafts of the plasma membrane that serve as locales for subsets of membrane-associated signalling effectors.

Biased agonists

Ligands that result in the activation of a selected subset of known available signalling pathways that are activated by the receptor.

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Ramachandran, R., Noorbakhsh, F., DeFea, K. et al. Targeting proteinase-activated receptors: therapeutic potential and challenges. Nat Rev Drug Discov 11, 69–86 (2012). https://doi.org/10.1038/nrd3615

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