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Han X, Knauss EA, Fuente MDL, Li W, Conlon RA, LePage DF, Jiang W, Renna SA, McKenzie SE, Nieman MT. A mouse model of the protease-activated receptor 4 Pro310Leu variant has reduced platelet reactivity. J Thromb Haemost 2024; 22:1715-1726. [PMID: 38508397 DOI: 10.1016/j.jtha.2024.03.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2023] [Revised: 02/26/2024] [Accepted: 03/11/2024] [Indexed: 03/22/2024]
Abstract
BACKGROUND Protease-activated receptor 4 (PAR4) mediates thrombin signaling on platelets and other cells. Our recent structural studies demonstrated that a single nucleotide polymorphism in extracellular loop 3 and PAR4-P310L (rs2227376) leads to a hyporeactive receptor. OBJECTIVES The goal of this study was to determine how the hyporeactive PAR4 variant in extracellular loop 3 impacts platelet function in vivo using a novel knock-in mouse model (PAR4-322L). METHODS A point mutation was introduced into the PAR4 gene F2rl3 via CRISPR/Cas9 to create PAR4-P322L, the mouse homolog to human PAR4-P310L. Platelet response to PAR4 activation peptide (AYPGKF), thrombin, ADP, and convulxin was monitored by αIIbβ3 integrin activation and P-selectin translocation using flow cytometry or platelet aggregation. In vivo responses were determined by the tail bleeding assay and the ferric chloride-induced carotid artery injury model. RESULTS PAR4-P/L and PAR4-L/L platelets had a reduced response to AYPGKF and thrombin measured by P-selectin translocation or αIIbβ3 activation. The response to ADP and convulxin was unchanged among genotypes. In addition, both PAR4-P/L and PAR4-L/L platelets showed a reduced response to thrombin in aggregation studies. There was an increase in the tail bleeding time for PAR4-L/L mice. The PAR4-P/L and PAR4-L/L mice both showed an extended time to arterial thrombosis. CONCLUSION PAR4-322L significantly reduced platelet responsiveness to AYPGKF and thrombin, which is in agreement with our previous structural and cell signaling studies. In addition, PAR4-322L had prolonged arterial thrombosis time. Our mouse model provides a foundation to further evaluate the role of PAR4 in other pathophysiological contexts.
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Affiliation(s)
- Xu Han
- Case Western Reserve University School of Medicine, Department of Pharmacology, Cleveland, Ohio, USA
| | - Elizabeth A Knauss
- Case Western Reserve University School of Medicine, Department of Pharmacology, Cleveland, Ohio, USA
| | - Maria de la Fuente
- Case Western Reserve University School of Medicine, Department of Pharmacology, Cleveland, Ohio, USA
| | - Wei Li
- Department of Biomedical Sciences, Joan C. Edwards School of Medicine at Marshall University, Huntington, West Virginia, USA
| | - Ronald A Conlon
- Case Transgenic and Targeting Facility, Case Western Reserve University, Cleveland, Ohio, USA
| | - David F LePage
- Case Transgenic and Targeting Facility, Case Western Reserve University, Cleveland, Ohio, USA
| | - Weihong Jiang
- Case Transgenic and Targeting Facility, Case Western Reserve University, Cleveland, Ohio, USA
| | - Stephanie A Renna
- Department of Medicine, The Cardeza Foundation for Hematologic Research, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Steven E McKenzie
- Department of Medicine, The Cardeza Foundation for Hematologic Research, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Marvin T Nieman
- Case Western Reserve University School of Medicine, Department of Pharmacology, Cleveland, Ohio, USA.
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O'Donnell JS, Fleming H, Noone D, Preston RJS. Unraveling coagulation factor-mediated cellular signaling. J Thromb Haemost 2023; 21:3342-3353. [PMID: 37391097 DOI: 10.1016/j.jtha.2023.06.019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Revised: 05/15/2023] [Accepted: 06/12/2023] [Indexed: 07/02/2023]
Abstract
Blood coagulation is initiated in response to blood vessel injury or proinflammatory stimuli, which activate coagulation factors to coordinate complex biochemical and cellular responses necessary for clot formation. In addition to these critical physiologic functions, plasma protein factors activated during coagulation mediate a spectrum of signaling responses via receptor-binding interactions on different cell types. In this review, we describe examples and mechanisms of coagulation factor signaling. We detail the molecular basis for cell signaling mediated by coagulation factor proteases via the protease-activated receptor family, considering new insights into the role of protease-specific cleavage sites, cofactor and coreceptor interactions, and distinct signaling intermediate interactions in shaping protease-activated receptor signaling diversity. Moreover, we discuss examples of how injury-dependent conformational activation of other coagulation proteins, such as fibrin(ogen) and von Willebrand factor, decrypts their signaling potential, unlocking their capacity to contribute to aberrant proinflammatory signaling. Finally, we consider the role of coagulation factor signaling in disease development and the status of pharmacologic approaches to either attenuate or enhance coagulation factor signaling for therapeutic benefit, emphasizing new approaches to inhibit deleterious coagulation factor signaling without impacting hemostatic activity.
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Affiliation(s)
- James S O'Donnell
- Irish Centre for Vascular Biology, School of Pharmacy and Biomolecular Sciences, RCSI University of Medicine and Health Sciences, Dublin, Ireland; National Children's Research Centre, Children's Health Ireland, Crumlin, Dublin, Ireland. https://twitter.com/profJSOdonnell
| | - Harry Fleming
- Irish Centre for Vascular Biology, School of Pharmacy and Biomolecular Sciences, RCSI University of Medicine and Health Sciences, Dublin, Ireland. https://www.twitter.com/PrestonLab_RCSI
| | - David Noone
- Irish Centre for Vascular Biology, School of Pharmacy and Biomolecular Sciences, RCSI University of Medicine and Health Sciences, Dublin, Ireland. https://www.twitter.com/PrestonLab_RCSI
| | - Roger J S Preston
- Irish Centre for Vascular Biology, School of Pharmacy and Biomolecular Sciences, RCSI University of Medicine and Health Sciences, Dublin, Ireland; National Children's Research Centre, Children's Health Ireland, Crumlin, Dublin, Ireland.
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3
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Han X, Knauss EA, de la Fuente M, Li W, Conlon RA, LePage DF, Jiang W, Renna SA, McKenzie SE, Nieman MT. A Mouse Model of the Protease Activated Receptor 4 (PAR4) Pro310Leu Variant has Reduced Platelet Reactivity. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.01.569075. [PMID: 38077081 PMCID: PMC10705540 DOI: 10.1101/2023.12.01.569075] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/17/2023]
Abstract
Background Protease activated receptor 4 (PAR4) mediates thrombin signaling on platelets and other cells. Our recent structural studies demonstrated a single nucleotide polymorphism in extracellular loop 3 (ECL3), PAR4-P310L (rs2227376) leads to a hypo-reactive receptor. Objectives The goal of this study was to determine how the hypo-reactive PAR4 variant in ECL3 impacts platelet function in vivo using a novel knock-in mouse model (PAR4-322L). Methods A point mutation was introduced into the PAR4 gene, F2rl3, via CRISPR/Cas9 to create PAR4-P322L, the mouse homolog to human PAR4-P310L. Platelet response to PAR4 activation peptide (AYPGKF), thrombin, ADP, and convulxin was monitored by αIIbβ3 integrin activation and P-selectin translocation using flow cytometry or platelet aggregation. In vivo responses were determined by the tail bleeding assay and the ferric chloride-induced carotid artery injury model. Results PAR4-P/L and PAR4-L/L platelets had a reduced response to AYPGKF and thrombin measured by P-selectin translocation or αIIbβ3 activation. The response to ADP and convulxin was unchanged among genotypes. In addition, both PAR4-P/L and PAR4-L/L platelets showed a reduced response to thrombin in aggregation studies. There was an increase in the tail bleeding time for PAR4-L/L mice. The PAR4-P/L and PAR4-L/L mice both showed an extended time to arterial thrombosis. Conclusions PAR4-322L significantly reduced platelet responsiveness to AYPGKF and thrombin, which is in agreement with our previous structural and cell signaling studies. In addition, PAR4-322L had prolonged arterial thrombosis time. Our mouse model provides a foundation to further evaluate the role of PAR4 in other pathophysiological contexts.
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Affiliation(s)
- Xu Han
- Department of Pharmacology, Case Western Reserve University, Cleveland, OH United States
| | - Elizabeth A. Knauss
- Department of Pharmacology, Case Western Reserve University, Cleveland, OH United States
| | - Maria de la Fuente
- Department of Pharmacology, Case Western Reserve University, Cleveland, OH United States
| | - Wei Li
- Department of Biomedical Sciences, Joan C. Edwards School of Medicine at Marshall University, Huntington, WV United States
| | - Ronald A Conlon
- Case Transgenic and Targeting Facility, Case Western Reserve University, Cleveland, OH United States
| | - David F. LePage
- Case Transgenic and Targeting Facility, Case Western Reserve University, Cleveland, OH United States
| | - Weihong Jiang
- Case Transgenic and Targeting Facility, Case Western Reserve University, Cleveland, OH United States
| | - Stephanie A. Renna
- Department of Medicine, The Cardeza Foundation for Hematologic Research, Thomas Jefferson University, Philadelphia, PA United States
| | - Steven E. McKenzie
- Department of Medicine, The Cardeza Foundation for Hematologic Research, Thomas Jefferson University, Philadelphia, PA United States
| | - Marvin T. Nieman
- Department of Pharmacology, Case Western Reserve University, Cleveland, OH United States
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Ramadas N, Sparkenbaugh EM. The APC-EPCR-PAR1 axis in sickle cell disease. Front Med (Lausanne) 2023; 10:1141020. [PMID: 37497271 PMCID: PMC10366386 DOI: 10.3389/fmed.2023.1141020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2023] [Accepted: 06/26/2023] [Indexed: 07/28/2023] Open
Abstract
Sickle Cell Disease (SCD) is a group of inherited hemoglobinopathies. Sickle cell anemia (SCA) is caused by a homozygous mutation in the β-globin generating sickle hemoglobin (HbS). Deoxygenation leads to pathologic polymerization of HbS and sickling of erythrocytes. The two predominant pathologies of SCD are hemolytic anemia and vaso-occlusive episodes (VOE), along with sequelae of complications including acute chest syndrome, hepatopathy, nephropathy, pulmonary hypertension, venous thromboembolism, and stroke. SCD is associated with endothelial activation due to the release of danger-associated molecular patterns (DAMPs) such as heme, recurrent ischemia-reperfusion injury, and chronic thrombin generation and inflammation. Endothelial cell activation is mediated, in part, by thrombin-dependent activation of protease-activated receptor 1 (PAR1), a G protein coupled receptor that plays a role in platelet activation, endothelial permeability, inflammation, and cytotoxicity. PAR1 can also be activated by activated protein C (APC), which promotes endothelial barrier protection and cytoprotective signaling. Notably, the APC system is dysregulated in SCD. This mini-review will discuss activation of PAR1 by APC and thrombin, the APC-EPCR-PAR1 axis, and their potential roles in SCD.
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Affiliation(s)
- Nirupama Ramadas
- Department of Medicine, Blood Research Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
| | - Erica M. Sparkenbaugh
- Department of Medicine, Blood Research Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
- Department of Pathology and Laboratory Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
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5
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Zhang X, Lee MD, Buckley C, Hollenberg MD, Wilson C, McCarron JG. Endothelial PAR2 activation evokes resistance artery relaxation. J Cell Physiol 2023; 238:776-789. [PMID: 36791026 PMCID: PMC10952239 DOI: 10.1002/jcp.30973] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2022] [Revised: 01/20/2023] [Accepted: 01/30/2023] [Indexed: 02/16/2023]
Abstract
Protease-activated receptor-1 & -2 (PAR1 and PAR2) are expressed widely in cardiovascular tissues including endothelial and smooth muscle cells. PAR1 and PAR2 may regulate blood pressure via changes in vascular contraction or relaxation mediated by endothelial Ca2+ signaling, but the mechanisms are incompletely understood. By using single-cell Ca2+ imaging across hundreds of endothelial cells in intact blood vessels, we explored PAR-mediated regulation of blood vessel function using PAR1 and PAR2 activators. We show that PAR2 activation evoked multicellular Ca2+ waves that propagated across the endothelium. The PAR2-evoked Ca2+ waves were temporally distinct from those generated by muscarinic receptor activation. PAR2 activated distinct clusters of endothelial cells, and these cells were different from those activated by muscarinic receptor stimulation. These results indicate that distinct cell clusters facilitate spatial segregation of endothelial signal processing. We also demonstrate that PAR2 is a phospholipase C-coupled receptor that evokes Ca2+ release from the IP3 -sensitive store in endothelial cells. A physiological consequence of this PAR2 signaling system is endothelium-dependent relaxation. Conversely, PAR1 activation did not trigger endothelial cell Ca2+ signaling nor relax or contract mesenteric arteries. Neither did PAR1 activators alter the response to PAR2 or muscarinic receptor activation. Collectively, these results suggest that endothelial PAR2 but not PAR1 evokes mesenteric artery relaxation by evoking IP3 -mediated Ca2+ release from the internal store. Sensing mediated by PAR2 receptors is distributed to spatially separated clusters of endothelial cells.
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Affiliation(s)
- Xun Zhang
- Strathclyde Institute of Pharmacy and Biomedical SciencesUniversity of StrathclydeGlasgowUK
| | - Matthew D. Lee
- Strathclyde Institute of Pharmacy and Biomedical SciencesUniversity of StrathclydeGlasgowUK
| | - Charlotte Buckley
- Strathclyde Institute of Pharmacy and Biomedical SciencesUniversity of StrathclydeGlasgowUK
| | - Morley D. Hollenberg
- Department of Physiology and Pharmacology and Department of MedicineUniversity of Calgary Cumming School of MedicineCalgaryAlbertaCanada
| | - Calum Wilson
- Strathclyde Institute of Pharmacy and Biomedical SciencesUniversity of StrathclydeGlasgowUK
| | - John G. McCarron
- Strathclyde Institute of Pharmacy and Biomedical SciencesUniversity of StrathclydeGlasgowUK
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Peach CJ, Edgington-Mitchell LE, Bunnett NW, Schmidt BL. Protease-activated receptors in health and disease. Physiol Rev 2023; 103:717-785. [PMID: 35901239 PMCID: PMC9662810 DOI: 10.1152/physrev.00044.2021] [Citation(s) in RCA: 21] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Revised: 07/08/2022] [Accepted: 07/10/2022] [Indexed: 11/22/2022] Open
Abstract
Proteases are signaling molecules that specifically control cellular functions by cleaving protease-activated receptors (PARs). The four known PARs are members of the large family of G protein-coupled receptors. These transmembrane receptors control most physiological and pathological processes and are the target of a large proportion of therapeutic drugs. Signaling proteases include enzymes from the circulation; from immune, inflammatory epithelial, and cancer cells; as well as from commensal and pathogenic bacteria. Advances in our understanding of the structure and function of PARs provide insights into how diverse proteases activate these receptors to regulate physiological and pathological processes in most tissues and organ systems. The realization that proteases and PARs are key mediators of disease, coupled with advances in understanding the atomic level structure of PARs and their mechanisms of signaling in subcellular microdomains, has spurred the development of antagonists, some of which have advanced to the clinic. Herein we review the discovery, structure, and function of this receptor system, highlight the contribution of PARs to homeostatic control, and discuss the potential of PAR antagonists for the treatment of major diseases.
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Affiliation(s)
- Chloe J Peach
- Department of Molecular Pathobiology, College of Dentistry, New York University, New York, New York
- Department of Neuroscience and Physiology and Neuroscience Institute, Grossman School of Medicine, New York University, New York, New York
| | - Laura E Edgington-Mitchell
- Department of Biochemistry and Pharmacology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, Victoria, Australia
- Bluestone Center for Clinical Research, Department of Oral and Maxillofacial Surgery, New York University College of Dentistry, New York, New York
| | - Nigel W Bunnett
- Department of Molecular Pathobiology, College of Dentistry, New York University, New York, New York
- Department of Neuroscience and Physiology and Neuroscience Institute, Grossman School of Medicine, New York University, New York, New York
| | - Brian L Schmidt
- Department of Molecular Pathobiology, College of Dentistry, New York University, New York, New York
- Bluestone Center for Clinical Research, Department of Oral and Maxillofacial Surgery, New York University College of Dentistry, New York, New York
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Abstract
PURPOSE OF REVIEW To provide an overview of the state-of-the-art in protein C (PC) pathway research. RECENT FINDINGS The PC pathway is crucial for maintaining hemostasis to prevent venous thromboembolism. This is evident from genetic mutations that result in impaired PC pathway activity and contribute to increased venous thromboembolism risk in affected individuals. In addition to its anticoagulant role, activated PC (APC) also mediates a complex, pleiotropic role in the maintenance of vascular cell health, which it achieves via anti-inflammatory and antiapoptotic cell signaling on endothelial cells. Emerging data have demonstrated that cell signaling by APC, mediated by multiple receptor interactions on different cell types, also confers cytoprotective and anti-inflammatory benefits. Defects in both arms of the PC pathway are associated with increased susceptibility to thrombo-inflammatory disease in various preclinical thrombotic, proinflammatory and neurological disease models. Moreover, recent studies have identified attenuation of anticoagulant PC pathway activity as an exciting therapeutic opportunity to promote hemostasis in patients with inherited or acquired bleeding disorders. SUMMARY In this review, we provide an overview of some recent developments in our understanding of the PC pathways.
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Affiliation(s)
- Gemma Leon
- Irish Centre for Vascular Biology, School of Pharmacy and Biomolecular Sciences, Royal College of Surgeons in Ireland
- National Children's Research Centre, Our Lady's Children's Hospital Crumlin, Crumlin, Dublin 12, Ireland
| | - Aisling M Rehill
- Irish Centre for Vascular Biology, School of Pharmacy and Biomolecular Sciences, Royal College of Surgeons in Ireland
| | - Roger J S Preston
- Irish Centre for Vascular Biology, School of Pharmacy and Biomolecular Sciences, Royal College of Surgeons in Ireland
- National Children's Research Centre, Our Lady's Children's Hospital Crumlin, Crumlin, Dublin 12, Ireland
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Chandrabalan A, Ramachandran R. Molecular mechanisms regulating Proteinase‐Activated Receptors (PARs). FEBS J 2021; 288:2697-2726. [DOI: 10.1111/febs.15829] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Revised: 03/10/2021] [Accepted: 03/18/2021] [Indexed: 12/13/2022]
Affiliation(s)
- Arundhasa Chandrabalan
- Department of Physiology and Pharmacology Schulich School of Medicine and Dentistry University of Western Ontario London Canada
| | - Rithwik Ramachandran
- Department of Physiology and Pharmacology Schulich School of Medicine and Dentistry University of Western Ontario London Canada
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Han X, Hofmann L, de la Fuente M, Alexander N, Palczewski K, Nieman MT. PAR4 activation involves extracellular loop 3 and transmembrane residue Thr153. Blood 2020; 136:2217-2228. [PMID: 32575122 PMCID: PMC7645988 DOI: 10.1182/blood.2019004634] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2019] [Accepted: 05/24/2020] [Indexed: 12/17/2022] Open
Abstract
Protease-activated receptor 4 (PAR4) mediates sustained thrombin signaling in platelets and is required for a stable thrombus. PAR4 is activated by proteolysis of the N terminus to expose a tethered ligand. The structural basis for PAR4 activation and the location of its ligand binding site (LBS) are unknown. Using hydrogen/deuterium exchange (H/D exchange), computational modeling, and signaling studies, we determined the molecular mechanism for tethered ligand-mediated PAR4 activation. H/D exchange identified that the LBS is composed of transmembrane 3 (TM3) domain and TM7. Unbiased computational modeling further predicted an interaction between Gly48 from the tethered ligand and Thr153 from the LBS. Mutating Thr153 significantly decreased PAR4 signaling. H/D exchange and modeling also showed that extracellular loop 3 (ECL3) serves as a gatekeeper for the interaction between the tethered ligand and LBS. A naturally occurring sequence variant (P310L, rs2227376) and 2 experimental mutations (S311A and P312L) determined that the rigidity conferred by prolines in ECL3 are essential for PAR4 activation. Finally, we examined the role of the polymorphism at position 310 in venous thromboembolism (VTE) using the International Network Against Venous Thrombosis (INVENT) consortium multi-ancestry genome-wide association study (GWAS) meta-analysis. Individuals with the PAR4 Leu310 allele had a 15% reduction in relative risk for VTE (odds ratio, 0.85; 95% confidence interval, 0.77-0.94) compared with the Pro310 allele. These data are consistent with our H/D exchange, molecular modeling, and signaling studies. In conclusion, we have uncovered the structural basis for PAR4 activation and identified a previously unrecognized role for PAR4 in VTE.
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Affiliation(s)
- Xu Han
- Case Western Reserve University, School of Medicine, Cleveland, OH; and
| | - Lukas Hofmann
- Case Western Reserve University, School of Medicine, Cleveland, OH; and
| | | | - Nathan Alexander
- Case Western Reserve University, School of Medicine, Cleveland, OH; and
| | | | - Marvin T Nieman
- Case Western Reserve University, School of Medicine, Cleveland, OH; and
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Han X, Nieman MT. The domino effect triggered by the tethered ligand of the protease activated receptors. Thromb Res 2020; 196:87-98. [PMID: 32853981 DOI: 10.1016/j.thromres.2020.08.004] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Revised: 07/23/2020] [Accepted: 08/03/2020] [Indexed: 12/20/2022]
Abstract
Protease activated receptors (PARs) are G-protein coupled receptors (GPCRs) that have a unique activation mechanism. Unlike other GPCRs that can be activated by free ligands, under physiological conditions, PARs are activated by the tethered ligand, which is a part of their N-terminus that is unmasked by proteolysis. It has been 30 years since the first member of the family, PAR1, was identified. In this review, we will discuss this unique tethered ligand mediate receptor activation of PARs in detail: how they interact with the proteases, the complex structural rearrangement of the receptors upon activation, and the termination of the signaling. We also summarize the structural studies of the PARs and how single nucleotide polymorphisms impact the receptor reactivity. Finally, we review the current strategies for inhibiting PAR function with therapeutic targets for anti-thrombosis. The focus of this review is PAR1 and PAR4 as they are the thrombin signal mediators on human platelets and therapeutics targets. We also include the structural studies of PAR2 as it informs the mechanism of action for PARs in general.
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Affiliation(s)
- Xu Han
- Department of Pharmacology, Case Western Reserve University, Cleveland, OH, USA
| | - Marvin T Nieman
- Department of Pharmacology, Case Western Reserve University, Cleveland, OH, USA.
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11
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Thibeault PE, LeSarge JC, Arends D, Fernandes M, Chidiac P, Stathopulos PB, Luyt LG, Ramachandran R. Molecular basis for activation and biased signaling at the thrombin-activated GPCR proteinase activated receptor-4 (PAR4). J Biol Chem 2020; 295:2520-2540. [PMID: 31892516 PMCID: PMC7039573 DOI: 10.1074/jbc.ra119.011461] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2019] [Revised: 12/28/2019] [Indexed: 01/09/2023] Open
Abstract
Proteinase-activated receptor (PAR)-4 is a member of the proteolytically-activated PAR family of G-protein-coupled receptors (GPCR) that represents an important target in the development of anti-platelet therapeutics. PARs are activated by proteolytic cleavage of their receptor N terminus by enzymes such as thrombin, trypsin, and cathepsin-G. This reveals the receptor-activating motif, termed the tethered ligand that binds intramolecularly to the receptor and triggers signaling. However, PARs are also activated by exogenous application of synthetic peptides derived from the tethered-ligand sequence. To better understand the molecular basis for PAR4-dependent signaling, we examined PAR4-signaling responses to a peptide library derived from the canonical PAR4-agonist peptide, AYPGKF-NH2, and we monitored activation of the Gαq/11-coupled calcium-signaling pathway, β-arrestin recruitment, and mitogen-activated protein kinase (MAPK) pathway activation. We identified peptides that are poor activators of PAR4-dependent calcium signaling but were fully competent in recruiting β-arrestin-1 and -2. Peptides that were unable to stimulate PAR4-dependent calcium signaling could not trigger MAPK activation. Using in silico docking and site-directed mutagenesis, we identified Asp230 in the extracellular loop-2 as being critical for PAR4 activation by both agonist peptide and the tethered ligand. Probing the consequence of biased signaling on platelet activation, we found that a peptide that cannot activate calcium signaling fails to cause platelet aggregation, whereas a peptide that is able to stimulate calcium signaling and is more potent for β-arrestin recruitment triggered greater levels of platelet aggregation compared with the canonical PAR4 agonist peptide. These findings uncover molecular determinants critical for agonist binding and biased signaling through PAR4.
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Affiliation(s)
- Pierre E Thibeault
- Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario N6A5C1, Canada
| | - Jordan C LeSarge
- Department of Chemistry, University of Western Ontario, London, Ontario N6A5C1, Canada
| | - D'Arcy Arends
- Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario N6A5C1, Canada
| | - Michaela Fernandes
- Department of Chemistry, University of Western Ontario, London, Ontario N6A5C1, Canada
| | - Peter Chidiac
- Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario N6A5C1, Canada
| | - Peter B Stathopulos
- Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario N6A5C1, Canada
| | - Leonard G Luyt
- Department of Chemistry, University of Western Ontario, London, Ontario N6A5C1, Canada; Department of Oncology, University of Western Ontario, London, Ontario N6A5C1, Canada; London Regional Cancer Program, Lawson Health Research Institute, London, Ontario N6C2R5, Canada
| | - Rithwik Ramachandran
- Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario N6A5C1, Canada.
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12
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de la Fuente M, Han X, Miyagi M, Nieman MT. Expression and Purification of Protease-Activated Receptor 4 (PAR4) and Analysis with Histidine Hydrogen-Deuterium Exchange. Biochemistry 2020; 59:671-681. [PMID: 31957446 DOI: 10.1021/acs.biochem.9b00987] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Protease-activated receptors (PARs) are G-protein-coupled receptors that are activated by proteolysis of the N-terminus, which exposes a tethered ligand that interacts with the receptor. Numerous studies have focused on the signaling pathways mediated by PARs. However, the structural basis for initiation of these pathways is unknown. Here, we describe a strategy for the expression and purification of PAR4. This is the first PAR family member to be isolated without stabilizing modifications for biophysical studies. We monitored PAR4 activation with histidine hydrogen-deuterium exchange. PAR4 has nine histidines that are spaced throughout the protein, allowing a global view of solvent accessible and nonaccessible regions. Peptides containing each of the nine His residues were used to determine the t1/2 for each His residue in apo or thrombin-activated PAR4. The thrombin-cleaved PAR4 exhibited a 2-fold increase (p > 0.01) in t1/2 values observed for four histidine residues (His180, His229, His240, and His380), demonstrating that these regions have decreased solvent accessibility upon thrombin treatment. In agreement, thrombin-cleaved PAR4 also was resistant to thermolysin digestion. In contrast, the rate of thermolysin proteolysis following stimulation with the PAR4 activation peptide was the same as that of unstimulated PAR4. Further analysis showed the C-terminus is protected in thrombin-activated PAR4 compared to uncleaved or agonist peptide-treated PAR4. The studies described here are the first to examine the tethered ligand activation mechanism for a PAR family member biophysically and shed light on the overall conformational changes that follow activation of PARs by a protease.
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Affiliation(s)
- Maria de la Fuente
- Department of Pharmacology , Case Western Reserve University , Cleveland , Ohio 44106-4965 , United States
| | - Xu Han
- Department of Pharmacology , Case Western Reserve University , Cleveland , Ohio 44106-4965 , United States
| | - Masaru Miyagi
- Department of Pharmacology , Case Western Reserve University , Cleveland , Ohio 44106-4965 , United States
| | - Marvin T Nieman
- Department of Pharmacology , Case Western Reserve University , Cleveland , Ohio 44106-4965 , United States
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Willis Fox O, Preston RJS. Molecular basis of protease-activated receptor 1 signaling diversity. J Thromb Haemost 2020; 18:6-16. [PMID: 31549766 DOI: 10.1111/jth.14643] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Revised: 09/13/2019] [Accepted: 09/17/2019] [Indexed: 12/13/2022]
Abstract
Protease-activated receptors (PARs) are a family of highly conserved G protein-coupled receptors (GPCRs) that respond to extracellular proteases via a unique proteolysis-dependent activation mechanism. Protease-activated receptor 1 (PAR1) was the first identified member of the receptor family and plays important roles in hemostasis, inflammation and malignancy. The biology underlying PAR1 signaling by its canonical agonist thrombin is well characterized; however, definition of the mechanistic basis of PAR1 signaling by other proteases, including matrix metalloproteases, activated protein C, plasmin, and activated factors VII and X, remains incompletely understood. In this review, we discuss emerging insights into the molecular bases for "biased" PAR1 signaling, including atypical PAR1 proteolysis, PAR1 heterodimer and coreceptor interactions, PAR1 translocation on the membrane surface, and interactions with different G-proteins and β-arrestins upon receptor activation. Moreover, we consider how these new insights into PAR1 signaling have acted to spur development of novel PAR1-targeted therapeutics that act to inhibit, redirect, or fine-tune PAR1 signaling output to treat cardiovascular and inflammatory disease. Finally, we discuss some of the key unanswered questions relating to PAR1 biology, in particular how differences in PAR1 proteolysis, signaling intermediate coupling, and engagement with coreceptors and GPCRs combine to mediate the diversity of identified PAR1 signaling outputs.
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Affiliation(s)
- Orla Willis Fox
- Irish Centre for Vascular Biology, Royal College of Surgeons in Ireland, Dublin, Ireland
- Department of Molecular and Cellular Therapeutics, Royal College of Surgeons in Ireland, Dublin, Ireland
| | - Roger J S Preston
- Irish Centre for Vascular Biology, Royal College of Surgeons in Ireland, Dublin, Ireland
- Department of Molecular and Cellular Therapeutics, Royal College of Surgeons in Ireland, Dublin, Ireland
- National Children's Research Centre, Our Lady's Children's Hospital Crumlin, Dublin, Ireland
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Kennedy AJ, Ballante F, Johansson JR, Milligan G, Sundström L, Nordqvist A, Carlsson J. Structural Characterization of Agonist Binding to Protease-Activated Receptor 2 through Mutagenesis and Computational Modeling. ACS Pharmacol Transl Sci 2018; 1:119-133. [PMID: 32219208 DOI: 10.1021/acsptsci.8b00019] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2018] [Indexed: 12/26/2022]
Abstract
Protease-activated receptor 2 (PAR2) is a G-protein-coupled receptor that is activated by proteolytic cleavage of its N-terminus. The unmasked N-terminal peptide then binds to the transmembrane bundle, leading to activation of intracellular signaling pathways associated with inflammation and cancer. Recently determined crystal structures have revealed binding sites of PAR2 antagonists, but the binding mode of the peptide agonist remains unknown. In order to generate a model of PAR2 in complex with peptide SLIGKV, corresponding to the trypsin-exposed tethered ligand, the orthosteric binding site was probed by iterative combinations of receptor mutagenesis, agonist ligand modifications, and data-driven structural modeling. Flexible-receptor docking identified a conserved binding mode for agonists related to the endogenous ligand that was consistent with the experimental data and allowed synthesis of a novel peptide (1-benzyl-1H[1,2,3]triazole-4-yl-LIGKV) with functional potency higher than that of SLIGKV. The final model may be used to understand the structural basis of PAR2 activation and in virtual screens to identify novel agonists and competitive antagonists. The combined experimental and computational approach to characterize agonist binding to PAR2 can be extended to study the many other G protein-coupled receptors that recognize peptides or proteins.
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Affiliation(s)
- Amanda J Kennedy
- Discovery Sciences and Cardiovascular Renal and Metabolism, IMED Biotech Unit, AstraZeneca, Gothenburg, SE-431 83 Mölndal, Sweden
| | - Flavio Ballante
- Science for Life Laboratory, Department of Cell and Molecular Biology, Uppsala University, BMC Box 596, SE-751 24 Uppsala, Sweden
| | - Johan R Johansson
- Discovery Sciences and Cardiovascular Renal and Metabolism, IMED Biotech Unit, AstraZeneca, Gothenburg, SE-431 83 Mölndal, Sweden
| | - Graeme Milligan
- Centre for Translational Pharmacology, Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - Linda Sundström
- Discovery Sciences and Cardiovascular Renal and Metabolism, IMED Biotech Unit, AstraZeneca, Gothenburg, SE-431 83 Mölndal, Sweden
| | - Anneli Nordqvist
- Discovery Sciences and Cardiovascular Renal and Metabolism, IMED Biotech Unit, AstraZeneca, Gothenburg, SE-431 83 Mölndal, Sweden
| | - Jens Carlsson
- Science for Life Laboratory, Department of Cell and Molecular Biology, Uppsala University, BMC Box 596, SE-751 24 Uppsala, Sweden
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Morikawa Y, Kato H, Kashiwagi H, Nishiura N, Akuta K, Honda S, Kanakura Y, Tomiyama Y. Protease-activated receptor-4 (PAR4) variant influences on platelet reactivity induced by PAR4-activating peptide through altered Ca 2+ mobilization and ERK phosphorylation in healthy Japanese subjects. Thromb Res 2018; 162:44-52. [DOI: 10.1016/j.thromres.2017.12.014] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2017] [Revised: 12/09/2017] [Accepted: 12/22/2017] [Indexed: 11/29/2022]
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Analysis of Large-Scale Mutagenesis Data To Assess the Impact of Single Amino Acid Substitutions. Genetics 2017; 207:53-61. [PMID: 28751422 PMCID: PMC5586385 DOI: 10.1534/genetics.117.300064] [Citation(s) in RCA: 76] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2017] [Accepted: 07/24/2017] [Indexed: 11/18/2022] Open
Abstract
Mutagenesis is a widely used method for identifying protein positions that are important for function or ligand binding. Advances in high-throughput DNA sequencing and mutagenesis techniques have enabled measurement of the effects of nearly all possible amino acid substitutions in many proteins. The resulting large-scale mutagenesis data sets offer a unique opportunity to draw general conclusions about the effects of different amino acid substitutions. Thus, we analyzed 34,373 mutations in 14 proteins whose effects were measured using large-scale mutagenesis approaches. Methionine was the most tolerated substitution, while proline was the least tolerated. We found that several substitutions, including histidine and asparagine, best recapitulated the effects of other substitutions, even when the identity of the wild-type amino acid was considered. The effects of histidine and asparagine substitutions also correlated best with the effects of other substitutions in different structural contexts. Furthermore, highly disruptive substitutions like aspartic and glutamic acid had the most discriminatory power for detecting ligand interface positions. Our work highlights the utility of large-scale mutagenesis data, and our conclusions can help guide future single substitution mutational scans.
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Natural Hirudin Increases Rat Flap Viability by Anti-Inflammation via PARs/p38/NF-κB Pathway. BIOMED RESEARCH INTERNATIONAL 2015; 2015:597264. [PMID: 26770977 PMCID: PMC4685076 DOI: 10.1155/2015/597264] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/08/2015] [Accepted: 11/24/2015] [Indexed: 12/30/2022]
Abstract
The present study aimed to evaluate the effect of natural hirudin on rat random skin flap viability and to determine the mechanism. Forty-eight rats were randomly divided into 2 groups. After the dorsal skin flap operation (3 cm × 10 cm in size), subcutaneous injections of 6 ATU hirudin were administered to group H (n = 24) every 12 h, while group C (n = 24) received an equal volume of 0.9% normal saline. Six rats from each group were euthanized 1, 2, 4, and 7 days after the operation. A full skin sample was collected from these rats to measure the p38-mitogen-activated protein kinase (p38-MAPK), phospho-p38- (Pp38-) MAPK, nuclear factor-κB (NF-κB) p65, phosphor-NF-κB (pNF-κB) p65, tumour necrosis factor- (TNF-) α, interleukin- (IL-) 6, and intercellular adhesion molecule- (ICAM-) 1 levels via western blot (WB) assays. The results showed that flap viability was significantly higher in the hirudin-treated group, which showed a reduced inflammatory response compared with the control group. The Pp38/p38, pNF-κB p65/NF-κB p65, TNF-α, IL-6, and ICAM-1 levels in the hirudin-treated group were lower than those in the control group. The results demonstrated that hirudin could improve random skin flap viability and suggested that this effect maybe occurs by blocking the thrombin/proteinase-activated receptors (PARs)/p38/NF-κB signalling pathway, thus decreasing the inflammatory response.
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Imaging G protein-coupled receptors while quantifying their ligand-binding free-energy landscape. Nat Methods 2015; 12:845-851. [PMID: 26167642 DOI: 10.1038/nmeth.3479] [Citation(s) in RCA: 90] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2014] [Accepted: 05/29/2015] [Indexed: 11/08/2022]
Abstract
Imaging native membrane receptors and testing how they interact with ligands is of fundamental interest in the life sciences but has proven remarkably difficult to accomplish. Here, we introduce an approach that uses force-distance curve-based atomic force microscopy to simultaneously image single native G protein-coupled receptors in membranes and quantify their dynamic binding strength to native and synthetic ligands. We measured kinetic and thermodynamic parameters for individual protease-activated receptor-1 (PAR1) molecules in the absence and presence of antagonists, and these measurements enabled us to describe PAR1's ligand-binding free-energy landscape with high accuracy. Our nanoscopic method opens an avenue to directly image and characterize ligand binding of native membrane receptors.
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N-linked glycosylation of protease-activated receptor-1 at extracellular loop 2 regulates G-protein signaling bias. Proc Natl Acad Sci U S A 2015; 112:E3600-8. [PMID: 26100877 DOI: 10.1073/pnas.1508838112] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Protease-activated receptor-1 (PAR1) is a G-protein-coupled receptor (GPCR) for the coagulant protease thrombin. Similar to other GPCRs, PAR1 is promiscuous and couples to multiple heterotrimeric G-protein subtypes in the same cell and promotes diverse cellular responses. The molecular mechanism by which activation of a given GPCR with the same ligand permits coupling to multiple G-protein subtypes is unclear. Here, we report that N-linked glycosylation of PAR1 at extracellular loop 2 (ECL2) controls G12/13 versus Gq coupling specificity in response to thrombin stimulation. A PAR1 mutant deficient in glycosylation at ECL2 was more effective at stimulating Gq-mediated phosphoinositide signaling compared with glycosylated wildtype receptor. In contrast, wildtype PAR1 displayed a greater efficacy at G12/13-dependent RhoA activation compared with mutant receptor lacking glycosylation at ECL2. Endogenous PAR1 rendered deficient in glycosylation using tunicamycin, a glycoprotein synthesis inhibitor, also exhibited increased PI signaling and diminished RhoA activation opposite to native receptor. Remarkably, PAR1 wildtype and glycosylation-deficient mutant were equally effective at coupling to Gi and β-arrestin-1. Consistent with preferential G12/13 coupling, thrombin-stimulated PAR1 wildtype strongly induced RhoA-mediated stress fiber formation compared with mutant receptor. In striking contrast, glycosylation-deficient PAR1 was more effective at increasing cellular proliferation, associated with Gq signaling, than wildtype receptor. These studies suggest that N-linked glycosylation at ECL2 contributes to the stabilization of an active PAR1 state that preferentially couples to G12/13 versus Gq and defines a previously unidentified function for N-linked glycosylation of GPCRs in regulating G-protein signaling bias.
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Mumaw MM, de la Fuente M, Arachiche A, Wahl JK, Nieman MT. Development and characterization of monoclonal antibodies against Protease Activated Receptor 4 (PAR4). Thromb Res 2015; 135:1165-71. [PMID: 25890453 DOI: 10.1016/j.thromres.2015.03.027] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Revised: 03/02/2015] [Accepted: 03/30/2015] [Indexed: 01/23/2023]
Abstract
BACKGROUND Protease activated receptor 4 (PAR4) is a G protein coupled receptor (GPCR) which is activated by proteolytic cleavage of its N-terminal exodomain. This generates a tethered ligand that activates the receptor and triggers downstream signaling events. With the current focus in the development of anti-platelet therapies shifted towards PARs, new reagents are needed for expanding the field's knowledge on PAR4. Currently, there are no PAR4 reagents which are able to detect activation of the receptor. METHODS Monoclonal PAR4 antibodies were purified from hybridomas producing antibody that were generated by fusing splenocytes with NS-1 cells. Immunoblotting, immunofluorescence, and flow cytometry were utilized to detect the epitope for each antibody and to evaluate the interaction of the antibodies with cells. RESULTS Here, we report the successful generation of three monoclonal antibodies to the N-terminal extracellular domain of PAR4: 14H6, 5F10, and 2D6. We mapped the epitope on PAR4 of 14H6, 5F10, and 2D6 antibodies to residues (48-53), (41-47), and (73-78), respectively. Two of the antibodies (14H6 and 5F10) interacted close to the thrombin cleavage and were sensitive to α-thrombin cleavage of PAR4. In addition, 5F10 was able to partially inhibit the cleavage of PAR4 expressed in HEK293 cells by α-thrombin. CONCLUSIONS These new antibodies provide a means to monitor endogenous PAR4 expression and activation by proteases on cells.
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Affiliation(s)
- Michele M Mumaw
- Department of Pharmacology, Case Western Reserve University, Cleveland, OH, USA
| | - Maria de la Fuente
- Department of Pharmacology, Case Western Reserve University, Cleveland, OH, USA
| | - Amal Arachiche
- Department of Pharmacology, Case Western Reserve University, Cleveland, OH, USA
| | - James K Wahl
- Department of Oral Biology, College of Dentistry, University of Nebraska Medical Center, Lincoln, NE, USA
| | - Marvin T Nieman
- Department of Pharmacology, Case Western Reserve University, Cleveland, OH, USA.
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Moschonas I, Goudevenos J, Tselepis A. Protease-activated receptor-1 antagonists in long-term antiplatelet therapy. Current state of evidence and future perspectives. Int J Cardiol 2015; 185:9-18. [DOI: 10.1016/j.ijcard.2015.03.049] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/25/2014] [Revised: 01/23/2015] [Accepted: 03/03/2015] [Indexed: 11/29/2022]
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Hollenberg MD, Mihara K, Polley D, Suen JY, Han A, Fairlie DP, Ramachandran R. Biased signalling and proteinase-activated receptors (PARs): targeting inflammatory disease. Br J Pharmacol 2014; 171:1180-94. [PMID: 24354792 DOI: 10.1111/bph.12544] [Citation(s) in RCA: 130] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2013] [Revised: 11/13/2013] [Accepted: 11/26/2013] [Indexed: 12/13/2022] Open
Abstract
Although it has been known since the 1960s that trypsin and chymotrypsin can mimic hormone action in tissues, it took until the 1990s to discover that serine proteinases can regulate cells by cleaving and activating a unique four-member family of GPCRs known as proteinase-activated receptors (PARs). PAR activation involves the proteolytic exposure of its N-terminal receptor sequence that folds back to function as a 'tethered' receptor-activating ligand (TL). A key N-terminal arginine in each of PARs 1 to 4 has been singled out as a target for cleavage by thrombin (PARs 1, 3 and 4), trypsin (PARs 2 and 4) or other proteases to unmask the TL that activates signalling via Gq , Gi or G12 /13 . Similarly, synthetic receptor-activating peptides, corresponding to the exposed 'TL sequences' (e.g. SFLLRN-, for PAR1 or SLIGRL- for PAR2) can, like proteinase activation, also drive signalling via Gq , Gi and G12 /13 , without requiring receptor cleavage. Recent data show, however, that distinct proteinase-revealed 'non-canonical' PAR tethered-ligand sequences and PAR-activating agonist and antagonist peptide analogues can induce 'biased' PAR signalling, for example, via G12 /13 -MAPKinase instead of Gq -calcium. This overview summarizes implications of this 'biased' signalling by PAR agonists and antagonists for the recognized roles the PARs play in inflammatory settings.
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Affiliation(s)
- M D Hollenberg
- Inflammation Research Network-Snyder Institute for Chronic Disease, Department of Physiology and Pharmacology, University of Calgary, Calgary, AB, Canada; Faculty of Medicine, Department of Medicine, University of Calgary, Calgary, AB, Canada
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Mumaw MM, de la Fuente M, Noble DN, Nieman MT. Targeting the anionic region of human protease-activated receptor 4 inhibits platelet aggregation and thrombosis without interfering with hemostasis. J Thromb Haemost 2014; 12:1331-41. [PMID: 24888424 PMCID: PMC4127092 DOI: 10.1111/jth.12619] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2014] [Accepted: 05/25/2014] [Indexed: 12/23/2022]
Abstract
BACKGROUND Human platelet activation and aggregation is a complex process. To date, many therapies have been developed targeting proteins that mediate this process to prevent unwanted activation. However, the current standard of care for acute coronary syndromes still has limitations, including bleeding risk. OBJECTIVE To evaluate the protease-activated receptor 4 (PAR4) anionic cluster as a viable antiplatelet target by using a polyclonal antibody (CAN12). METHODS We used western blotting, aggregation and secretion ex vivo to evaluate the ability of CAN12 to interact with PAR4 and inhibit platelet activation. The effects of CAN12 in vivo were evaluated with the Rose Bengal arterial thrombosis model and two models of hemostasis. RESULTS CAN12 was able to interact with human PAR4 and delay PAR4 cleavage. In addition, CAN12 inhibited thrombin-induced human platelet aggregation and secretion in a dose-dependent manner. The specificity of CAN12 was agonist-dependent. In vivo, we determined that CAN12 was able to inhibit arterial thrombosis, and, using two independent methods, we found that CAN12 did not influence hemostasis. CONCLUSION Targeting the extracellular anionic cluster on PAR4 is a viable novel strategy as an antiplatelet therapy.
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Affiliation(s)
- M M Mumaw
- Department of Pharmacology, Case Western Reserve University, Cleveland, OH, USA
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Valdivielso ÁM, Ventosa-Andrés P, Tato F, Fernández-Ibañez MÁ, Pappos I, Tsopanoglou NE, García-López MT, Gutiérrez-Rodríguez M, Herranz R. Highly functionalized 2-oxopiperazine-based peptidomimetics: An approach to PAR1 antagonists. Eur J Med Chem 2013; 70:199-224. [DOI: 10.1016/j.ejmech.2013.09.058] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2013] [Revised: 08/26/2013] [Accepted: 09/24/2013] [Indexed: 02/01/2023]
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Yau MK, Liu L, Fairlie DP. Toward drugs for protease-activated receptor 2 (PAR2). J Med Chem 2013; 56:7477-97. [PMID: 23895492 DOI: 10.1021/jm400638v] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
PAR2 has a distinctive functional phenotype among an unusual group of GPCRs called protease activated receptors, which self-activate after cleavage of their N-termini by mainly serine proteases. PAR2 is the most highly expressed PAR on certain immune cells, and it is activated by multiple proteases (but not thrombin) in inflammation. PAR2 is expressed on many types of primary human cells and cancer cells. PAR2 knockout mice and PAR2 agonists and antagonists have implicated PAR2 as a promising target in inflammatory conditions; respiratory, gastrointestinal, metabolic, cardiovascular, and neurological dysfunction; and cancers. This article summarizes salient features of PAR2 structure, activation, and function; opportunities for disease intervention via PAR2; pharmacological properties of published or patented PAR2 modulators (small molecule agonists and antagonists, pepducins, antibodies); and some personal perspectives on limitations of assessing their properties and on promising new directions for PAR2 modulation.
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Affiliation(s)
- Mei-Kwan Yau
- Division of Chemistry and Structural Biology, Institute for Molecular Bioscience, The University of Queensland , Brisbane, Queensland 4072, Australia
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27
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Larsen AK, Kristiansen K, Sylte I, Seternes OM, Bang BE. Differences in PAR-2 activating potential by king crab (Paralithodes camtschaticus), salmon (Salmo salar), and bovine (Bos taurus) trypsin. BMC Res Notes 2013; 6:281. [PMID: 23870109 PMCID: PMC3733831 DOI: 10.1186/1756-0500-6-281] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2013] [Accepted: 07/03/2013] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Salmon trypsin is shown to increase secretion of the pro-inflammatory cytokine interleukin (IL)-8 from human airway epithelial cells through activation of PAR-2. Secretion of IL-8 induced by king crab trypsin is observed in a different concentration range compared to salmon trypsin, and seems to be only partially related to PAR-2 activation. This report aim to identify differences in the molecular structure of king crab trypsin (Paralithodes camtschaticus) compared to salmon (Salmo salar) and bovine trypsin (Bos taurus) that might influence the ability to activate protease-activated receptor-2 (PAR-2). RESULTS During purification king crab trypsin displayed stronger binding capacity to the anionic column used in fast protein liquid chromatography compared to fish trypsins, and was identified as a slightly bigger molecule. Measurements of enzymatic activity yielded no obvious differences between the trypsins tested. Molecular modelling showed that king crab trypsin has a large area with strong negative electrostatic potential compared to the smaller negative areas in bovine and salmon trypsins. Bovine and salmon trypsins also displayed areas with strong positive electrostatic potential, a feature lacking in the king crab trypsin. Furthermore we have identified 3 divergent positions (Asp196, Arg244, and Tyr247) located near the substrate binding pocket of king crab trypsin that might affect the binding and cleavage of PAR-2. CONCLUSION These preliminary results indicate that electrostatic interactions could be of importance in binding, cleavage and subsequent activation of PAR-2.
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Affiliation(s)
- Anett K Larsen
- Department of Occupational- and Environmental Medicine, University Hospital North Norway, Tromsø, Norway
- Medical Pharmacology and Toxicology, Department of Medical Biology, Faculty of Health Sciences, University of Tromsø, Tromsø, Norway
| | - Kurt Kristiansen
- Medical Pharmacology and Toxicology, Department of Medical Biology, Faculty of Health Sciences, University of Tromsø, Tromsø, Norway
| | - Ingebrigt Sylte
- Medical Pharmacology and Toxicology, Department of Medical Biology, Faculty of Health Sciences, University of Tromsø, Tromsø, Norway
| | - Ole-Morten Seternes
- Department of Pharmacy, Faculty of Health Sciences, University of Tromsø, Tromsø, Norway
| | - Berit E Bang
- Department of Occupational- and Environmental Medicine, University Hospital North Norway, Tromsø, Norway
- Medical Pharmacology and Toxicology, Department of Medical Biology, Faculty of Health Sciences, University of Tromsø, Tromsø, Norway
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Arachiche A, de la Fuente M, Nieman MT. Calcium mobilization and protein kinase C activation downstream of protease activated receptor 4 (PAR4) is negatively regulated by PAR3 in mouse platelets. PLoS One 2013; 8:e55740. [PMID: 23405206 PMCID: PMC3566007 DOI: 10.1371/journal.pone.0055740] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2012] [Accepted: 12/29/2012] [Indexed: 12/17/2022] Open
Abstract
Thrombin activates platelets through protease activated receptors (PARs). Mouse platelets express PAR3 and PAR4. PAR3 does not signal in platelets. However, PAR4 is a relatively poor thrombin substrate and requires PAR3 as a cofactor at low thrombin concentrations. In this study we show that PAR3 also regulates PAR4 signaling. In response to thrombin (30–100 nM) or PAR4 activating peptide (AYPGKF), platelets from PAR3−/− mice had increased Gq signaling compared to wild type mice as demonstrated by a 1.6-fold increase in the maximum intracellular calcium (Ca2+) mobilization, an increase in phosphorylation level of protein kinase C (PKC) substrates, and a 2-fold increase of Ca2+ release from intracellular stores. Moreover, platelets from heterozygous mice (PAR3+/−) had an intermediate increase in maximum Ca2+ mobilization. Treatment of PAR3−/− mice platelets with P2Y12 antagonist (2MeSAMP) did not affect Ca2+ mobilization from PAR4 in response to thrombin or AYPGKF. The activation of RhoA-GTP downstream G12/13 signaling in response to thrombin was not significantly different between wild type and PAR3−/− mice. Since PAR3 influenced PAR4 signaling independent of agonist, we examined the direct interaction between PAR3 and PAR4 with bioluminescence resonance energy transfer (BRET). PAR3 and PAR4 form constitutive homodimers and heterodimers. In summary, our results demonstrate that in addition to enhancing PAR4 activation at low thrombin concentrations, PAR3 negatively regulates PAR4-mediated maximum Ca2+ mobilization and PKC activation in mouse platelets by physical interaction.
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Affiliation(s)
- Amal Arachiche
- Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio, United States of America
| | - María de la Fuente
- Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio, United States of America
| | - Marvin T. Nieman
- Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio, United States of America
- * E-mail:
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29
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Protease-Activated Receptors. Platelets 2013. [DOI: 10.1016/b978-0-12-387837-3.00013-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
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Zhang C, Srinivasan Y, Arlow DH, Fung JJ, Palmer D, Zheng Y, Green HF, Pandey A, Dror RO, Shaw DE, Weis WI, Coughlin SR, Kobilka BK. High-resolution crystal structure of human protease-activated receptor 1. Nature 2012; 492:387-92. [PMID: 23222541 PMCID: PMC3531875 DOI: 10.1038/nature11701] [Citation(s) in RCA: 347] [Impact Index Per Article: 28.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2012] [Accepted: 10/22/2012] [Indexed: 01/22/2023]
Abstract
Protease-Activated Receptor-1 (PAR1) is the prototypical member of a family of G protein-coupled receptors that mediate cellular responses to thrombin and related proteases. Thrombin irreversibly activates PAR1 by cleaving the N-terminal exodomain of the receptor, which exposes a tethered peptide ligand that binds the receptor’s heptahelical bundle to effect G protein-activation. Here we report a 2.2Å resolution crystal structure of human PAR1 bound to vorapaxar, a PAR1 antagonist. The structure reveals an unusual mode of drug binding that explains how a small molecule binds virtually irreversibly to inhibit receptor activation by PAR1’s tethered ligand. In contrast to deep, solvent-exposed binding pockets observed in other peptide-activated GPCRs, the vorapaxar-binding pocket is superficial but has little surface exposed to the aqueous solvent. PARs are important targets for drug development. The structure reported here will aid development of improved PAR1 antagonists and discovery of antagonists to other members of this receptor family.
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Affiliation(s)
- Cheng Zhang
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, California 94305, USA
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Yang AL, Zhou HJ, Lin Y, Luo JK, Cui HJ, Tang T, Yang QD. Thrombin promotes the expression of thrombospondin-1 and ‐2 in a rat model of intracerebral hemorrhage. J Neurol Sci 2012; 323:141-6. [DOI: 10.1016/j.jns.2012.09.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2012] [Revised: 09/05/2012] [Accepted: 09/07/2012] [Indexed: 10/27/2022]
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Ventosa-Andrés P, Valdivielso AM, Pappos I, García-López MT, Tsopanoglou NE, Herranz R. Design, synthesis and biological evaluation of new peptide-based ureas and thioureas as potential antagonists of the thrombin receptor PAR1. Eur J Med Chem 2012; 58:98-111. [PMID: 23123726 DOI: 10.1016/j.ejmech.2012.10.015] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2012] [Revised: 10/02/2012] [Accepted: 10/09/2012] [Indexed: 12/22/2022]
Abstract
By applying a diversity oriented synthesis strategy for the search of new antagonists of the thrombin receptor PAR1, a series of peptide-based ureas and thioureas, including analogues of the PAR1 reference antagonist RWJ-58259, has been designed and synthesized. The general synthetic scheme involves reduction of basic amino acid-derived amino nitriles by hydrogen transfer from hydrazine monohydrate in the presence of Raney Ni, followed by reaction with diverse isocyanates and isothiocyanates, and protecting group removal. All new compounds have been evaluated as inhibitors of human platelet aggregation induced by the PAR1 agonist SFLLRN. Some protected peptide-based ureas displayed significant antagonist activity.
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33
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Lee H, Hamilton JR. Physiology, pharmacology, and therapeutic potential of protease-activated receptors in vascular disease. Pharmacol Ther 2012; 134:246-59. [DOI: 10.1016/j.pharmthera.2012.01.007] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2012] [Accepted: 01/17/2012] [Indexed: 01/09/2023]
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34
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Lim AC, Ketchem RR, Borges L, Carabeo T, Carter J, Hoover JE, Hu Z, Wittekind M, Zhou H, Mehlin C. A diversity of antibody epitopes can induce signaling through the erythropoietin receptor. Biochemistry 2010; 49:3797-804. [PMID: 20337434 DOI: 10.1021/bi1001147] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Stimulation of red cell production through agonism of the erythropoietin receptor (EpoR) has historically been accomplished through administration of erythropoietin (EPO), the native ligand. The short half-life of EPO has led to the development of a variety of other agonists, including antibodies. It is of considerable interest to understand how these agents might activate the EpoR and whether or not it is important to bind in a manner similar to the native ligand. The binding epitopes of a panel of eight agonistic, single-chain antibody (scFv-Fc) constructs were determined through scanning alanine mutagenesis as well as more limited arginine mutagenesis of the receptor. It was found that while some of these constructs bound to receptor epitopes shared by the ligand, others bound in completely unique ways. The use of a panel of agonists and scanning mutagenesis can define the critical binding regions for signaling; in the case of the EpoR, these regions were remarkably broad.
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Affiliation(s)
- Ai Ching Lim
- Amgen, Inc., 1201 Amgen Court West AW2/3152, Seattle, Washington 98119-3105, USA
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35
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Long M, Yang L, Huang G, Liu L, Dong Y, Du Z, Tang A, Hu C, Gu R, Gao X, Tang L. Thrombin and its receptor enhance ST-segment elevation in acute myocardial infarction by activating the KATP channel. Mol Med 2010; 16:322-32. [PMID: 20386871 DOI: 10.2119/molmed.2010.00006] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2010] [Accepted: 04/08/2010] [Indexed: 11/06/2022] Open
Abstract
ST-segment elevation is the major clinical criterion for committing patients with chest pain to have emergent coronary revascularizations; however, the mechanism responsible for ST-segment elevation is unknown. In a guinea pig model of ST-segment elevation acute myocardial infarction (AMI), local application of hirudin, a thrombin antagonist, significantly decreased AMI-induced ST-segment elevation in a dose-dependent manner. Hirudin-induced (5 antithrombin units [ATU]) decrease in ST elevation was reversed by 250 nmol/L thrombin receptor activator peptide (TRAP). TRAP (250 nmol/L [100 microL]) significantly induced ST-segment elevation in hearts without AMI. The TRAP effect was blocked by 4 mg/kg glibenclamide and 4 mg/kg HMR1098 and partially blocked by 3 mg/kg 5HD. Pinacidil (0.45 mg/kg) simulated the effect of TRAP (250 nmol/L [100 microL]) on hearts without AMI. Moreover, single-channel recordings showed that TRAP induced ATP-sensitive K+ channel (KATP channel) activity, and this effect was blocked by HMR1098 but not 5HD. Finally, TRAP significantly shortened the monophasic action potential (MAP) at 90% repolarization (MAP90) and epicardial MAP (EpiMAP) duration. These effects of TRAP were completely reversed by HMR1098 and partially reversed by 5HD. Thrombin and its receptor activation enhanced ST-segment elevation in an AMI model by activating the sarcolemmal KATP channel.
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Affiliation(s)
- Ming Long
- Division of Cardiology, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
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36
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Martin K, Weiss S, Metharom P, Schmeckpeper J, Hynes B, O'Sullivan J, Caplice N. Thrombin Stimulates Smooth Muscle Cell Differentiation From Peripheral Blood Mononuclear Cells via Protease-Activated Receptor-1, RhoA, and Myocardin. Circ Res 2009; 105:214-8. [DOI: 10.1161/circresaha.109.199984] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Rationale:
Smooth muscle precursor cells have previously been reported to reside in bone marrow and in the circulation, but little is currently known regarding the proximate stimuli for smooth muscle cell differentiation of these putative progenitors.
Objective:
Because local thrombin generation occurs as an initial response to vascular injury, we hypothesized that thrombin may influence the differentiation of circulating smooth muscle progenitor cells.
Methods and Results:
Peripheral blood mononuclear cells were cultured on type I collagen using a protocol optimized to stimulate smooth muscle cell outgrowth. Thrombin-stimulated upregulation of the transcription factor myocardin and smooth muscle myosin heavy chain, and both were inhibited by hirudin or the RhoA inhibitor Y27632. After 10 days of culture, smooth muscle outgrowth colonies formed, which stained positive for α-smooth muscle actin, smooth muscle myosin heavy chain, and calponin, in addition to having a contractile response to 100 nmol/L angiotensin II. Coincubation of peripheral blood mononuclear cells with thrombin, 10 μmol/L protease-activated receptor-1, but not protease-activated receptor-4 activating peptide significantly increased the number of smooth muscle outgrowth colonies formed. Thrombin-induced enhancement of smooth muscle outgrowth colony formation was inhibited by hirudin, Y27632, and an antibody against protease-activated receptor-1.
Conclusions:
These data illustrate a novel thrombin-induced pathway for smooth muscle differentiation from putative smooth muscle progenitors in peripheral blood.
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Affiliation(s)
- Kenneth Martin
- From the Centre for Research in Vascular Biology, Biosciences Institute, University College Cork, Ireland
| | - Sharon Weiss
- From the Centre for Research in Vascular Biology, Biosciences Institute, University College Cork, Ireland
| | - Pat Metharom
- From the Centre for Research in Vascular Biology, Biosciences Institute, University College Cork, Ireland
| | - Jeffrey Schmeckpeper
- From the Centre for Research in Vascular Biology, Biosciences Institute, University College Cork, Ireland
| | - Brian Hynes
- From the Centre for Research in Vascular Biology, Biosciences Institute, University College Cork, Ireland
| | - John O'Sullivan
- From the Centre for Research in Vascular Biology, Biosciences Institute, University College Cork, Ireland
| | - Noel Caplice
- From the Centre for Research in Vascular Biology, Biosciences Institute, University College Cork, Ireland
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37
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Bahou WF, Schmidt VA. Molecular characterization of proteolytically activated receptors: insights from the thrombin receptor and proteinase activated receptor-2 (PAR-2) genes. Platelets 2009; 7:253-60. [DOI: 10.3109/09537109609023586] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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38
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Luo W, Wang Y, Reiser G. Protease-activated receptors in the brain: receptor expression, activation, and functions in neurodegeneration and neuroprotection. ACTA ACUST UNITED AC 2007; 56:331-45. [PMID: 17915333 DOI: 10.1016/j.brainresrev.2007.08.002] [Citation(s) in RCA: 134] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2007] [Revised: 08/15/2007] [Accepted: 08/18/2007] [Indexed: 11/15/2022]
Abstract
Protease-activated receptors (PARs) are G protein-coupled receptors that regulate the cellular response to extracellular serine proteases, like thrombin, trypsin, and tryptase. The PAR family consists of four members: PAR-1, -3, and -4 as thrombin receptors and PAR-2 as the trypsin/tryptase receptor, which are abundantly expressed in the brain throughout development. Recent evidence has supported the direct involvement of PARs in brain development and function. The expression of PARs in the brain is differentially upregulated or downregulated under pathological conditions in neurodegenerative disorders, like Parkinson's disease, Alzheimer's disease, multiple sclerosis, stroke, and human immunodeficiency virus-associated dementia. Activation of PARs mediates cell death or cell survival in the brain, depending on the amplitude and the duration of agonist stimulation. Interference or potentiation of PAR activation is beneficial in animal models of neurodegenerative diseases. Therefore, PARs mediate either neurodegeneration or neuroprotection in neurodegenerative diseases and represent attractive therapeutic targets for treatment of brain injuries. Here, we review the abnormal expression of PARs in the brain under pathological conditions, the functions of PARs in neurodegenerative disorders, and the molecular mechanisms involved.
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Affiliation(s)
- Weibo Luo
- Institut für Neurobiochemie, Medizinische Fakultät, Otto-von-Guericke-Universität Magdeburg, Leipziger Strasse 44, 39120 Magdeburg, Germany
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39
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Clasby MC, Chackalamannil S, Czarniecki M, Doller D, Eagen K, Greenlee W, Kao G, Lin Y, Tsai H, Xia Y, Ahn HS, Agans-Fantuzzi J, Boykow G, Chintala M, Foster C, Smith-Torhan A, Alton K, Bryant M, Hsieh Y, Lau J, Palamanda J. Metabolism-Based Identification of a Potent Thrombin Receptor Antagonist. J Med Chem 2006; 50:129-38. [PMID: 17201416 DOI: 10.1021/jm061043e] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The metabolism of our prototypical thrombin receptor antagonist 1, Ki = 2.7 nM, was studied and three major metabolites (2, 4, and 5) were found. The structures of the metabolites were verified independently by synthesis. Compound 4 was shown to be a potent antagonist of the thrombin receptor with a Ki = 11 nM. Additionally, compound 4 showed a 3-fold improvement in potency with respect to 1 in an agonist-induced ex-vivo platelet aggregation assay in cynomolgus monkeys after oral administration; this activity was sustained with 60% inhibition observed at 24 h post-dose. Compound 4 was highly active in functional assays and showed excellent oral bioavailability in rats and monkeys. Compound 4 showed a superior rat enzyme induction profile relative to compound 1, allowing it to replace compound 1 as a development candidate.
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Affiliation(s)
- Martin C Clasby
- Central Nervous System and Cardiovascular Chemical Research, Schering-Plough Research Institute, Kenilworth, New Jersey 07033, USA
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40
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Kuo FT, Lu TL, Fu HW. Opposing effects of β-arrestin1 and β-arrestin2 on activation and degradation of Src induced by protease-activated receptor 1. Cell Signal 2006; 18:1914-23. [PMID: 16580177 DOI: 10.1016/j.cellsig.2006.02.009] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2006] [Revised: 02/15/2006] [Accepted: 02/15/2006] [Indexed: 10/25/2022]
Abstract
Protease-activated receptor 1 (PAR1), a G protein-coupled receptor for thrombin, is irreversibly proteolytically activated. beta-Arrestin1 and beta-arrestin2 have been reported to have different effects on signal desensitization and transduction of PAR1. In this study, we investigated whether beta-arrestin1 and beta-arrestin2 regulate Src-dependent activation of extracellular signal-regulated kinases 1 and 2 (ERK1/2) induced by PAR1 in HEK 293 cells. Our results show that PAR1-mediated activation of Src and ERK1/2 in HEK 293 cells was increased with overexpression of beta-arrestin1 or depletion of beta-arrestin2. PAR1-mediated activation of Src and ERK1/2 in HEK 293 cells was decreased or eliminated with depletion of beta-arrestin1 or overexpression of beta-arrestin2. Furthermore, depletion of beta-arrestin2 blocked PAR1-induced degradation of Src. Thus, beta-arrestin1 and beta-arrestin2 have opposing roles in regulating the activation of Src induced by PAR1. beta-Arrestin2 also appears to promote PAR1-induced degradation of Src. This degradation of Src provides a possible mechanism for terminating PAR1 signaling.
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Affiliation(s)
- Fang-Ting Kuo
- Institute of Molecular and Cellular Biology, Hsinchu 30013, Taiwan ROC
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41
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Abstract
Thrombosis associated with the pathophysiological activation of platelets and vascular cells has brought thrombin and its receptors to the forefront of cardiovascular medicine. Thrombin signaling through the protease-activated receptors (PARs) has been shown to influence a wide range of physiological responses including platelet activation, intimal hyperplasia, inflammation, and maintenance of vascular tone and barrier function. The thrombin receptors PAR1 and PAR4 can be effectively targeted in animals in which acute or prolonged exposure to thrombin leads to thrombosis and/or restenosis. In the present study, we describe the molecular and pharmacological basis of small-molecule inhibitors that target PAR1. In addition, we discuss a new class of cell-penetrating inhibitors, termed pepducins, that provide insight into previously unidentified roles of PAR1 and PAR4 in protease signaling.
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Affiliation(s)
- Andrew J Leger
- Hemostasis and Thrombosis Laboratory, Division of Hematology/Oncology, Molecular Oncology Research Institute, Tufts-New England Medical Center, Boston, MA 02111, USA
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42
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Chackalamannil S. Thrombin receptor (protease activated receptor-1) antagonists as potent antithrombotic agents with strong antiplatelet effects. J Med Chem 2006; 49:5389-403. [PMID: 16942011 DOI: 10.1021/jm0603670] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Samuel Chackalamannil
- Schering-Plough Research Institute, 2015 Galloping Hill Road, Kenilworth, New Jersey 07033, USA. samuel.
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43
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Grishina Z, Ostrowska E, Halangk W, Sahin-Tóth M, Reiser G. Activity of recombinant trypsin isoforms on human proteinase-activated receptors (PAR): mesotrypsin cannot activate epithelial PAR-1, -2, but weakly activates brain PAR-1. Br J Pharmacol 2006; 146:990-9. [PMID: 16231009 PMCID: PMC1751236 DOI: 10.1038/sj.bjp.0706410] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
Abstract
Trypsin-like serine proteinases trigger signal transduction pathways through proteolytic cleavage of proteinase-activated receptors (PARs) in many tissues. Three members, PAR-1, PAR-2 and PAR-4, are trypsin substrates, as trypsinolytic cleavage of the extracellular N terminus produces receptor activation. Here, the ability of the three human pancreatic trypsin isoforms (cationic trypsin, anionic trypsin and mesotrypsin (trypsin IV)) as recombinant proteins was tested on PARs. Using fura 2 [Ca(2+)](i) measurements, we analyzed three human epithelial cell lines, HBE (human bronchial epithelial), A549 (human pulmonary epithelial) and HEK (human embryonic kidney)-293 cells, which express functional PAR-1 and PAR-2. Human mesotrypsin failed to induce a PAR-mediated Ca(2+) response in human epithelial cells even at high concentrations. In addition, mesotrypsin did not affect the magnitude of PAR activation by subsequently added bovine trypsin. In HBE cells, which like A549 cells express high PAR-2 levels with negligible PAR-1 levels (<11%), half-maximal responses were seen for both cationic and anionic trypsins at about 5 nM. In the epithelial cells, mesotrypsin did not activate PAR-2 or PAR-1, whereas both anionic and cationic trypsins were comparable activators. We also investigated human astrocytoma 1321N1cells, which express PAR-1 and some PAR-3, but no PAR-2. High concentrations (>100 nM) of mesotrypsin produced a relatively weak Ca(2+) signal, apparently through PAR-1 activation. Half-maximal responses were observed at 60 nM mesotrypsin, and at 10-20 nM cationic and anionic trypsins. Using a desensitization assay with PAR-2-AP, we confirmed that both cationic and anionic trypsin isoforms cause [Ca(2+)](i) elevation in HBE cells mainly through PAR-2 activation. Desensitization of PAR-1 with thrombin receptor agonist peptide in 1321N1 cells demonstrated that all three recombinant trypsin isoforms act through PAR-1.Thus, the activity of human cationic and anionic trypsins on PARs was comparable to that of bovine pancreatic trypsin. Mesotrypsin (trypsin IV), in contrast to cationic and anionic trypsin, cannot activate or disable PARs in human epithelial cells, demonstrating that the receptors are no substrates for this isoenzyme. On the other hand, mesotrypsin activates PAR-1 in human astrocytoma cells. This might play a role in protection/degeneration or plasticity processes in the human brain.
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Affiliation(s)
- Zoryana Grishina
- Institut für Neurobiochemie, Medizinische Fakultät der Otto-von-Guericke-Universität Magdeburg, Leipziger Straße 44, D-39120 Magdeburg, Germany
- AN Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow, Russia
| | - Ewa Ostrowska
- Institut für Neurobiochemie, Medizinische Fakultät der Otto-von-Guericke-Universität Magdeburg, Leipziger Straße 44, D-39120 Magdeburg, Germany
| | - Walter Halangk
- Department für Experimentelle Chirurgie, Otto von Guericke-Universität, D-39120 Magdeburg, Germany
| | - Miklós Sahin-Tóth
- Boston University Goldman School of Dental Medicine, Boston, Massachusetts 02118, U.S.A
| | - Georg Reiser
- Institut für Neurobiochemie, Medizinische Fakultät der Otto-von-Guericke-Universität Magdeburg, Leipziger Straße 44, D-39120 Magdeburg, Germany
- Author for correspondence:
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44
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Sarker KP, Biswas KK, Yamaji K, Yamakuchi M, Hashiguchi T, Lee KY, Maruyama I. Inhibition of thrombin-induced vascular endothelial growth factor production in human neuroblastoma (NB-1) cells by argatroban. PATHOPHYSIOLOGY OF HAEMOSTASIS AND THROMBOSIS 2006; 34:41-7. [PMID: 16293985 DOI: 10.1159/000088547] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2004] [Accepted: 06/18/2005] [Indexed: 01/27/2023]
Abstract
Thrombin, a serine protease that plays a pivotal role in blood coagulation, wound healing, and angiogenesis, has also been implicated in the mitogenesis of various cell types. Previously, we showed that thrombin and the thrombin receptor agonist peptide (TRAP-14; SFLLRNPNDKYEPF) for protease-activated receptor 1 (PAR1) induce vascular endothelial growth factor (VEGF) secretion in PC-12 cells. In this study, we show that thrombin and TRAP-14 also stimulate VEGF secretion in the human NB-1 neuroblastoma cells. In these cells, we further show that thrombin-induced VEGF secretion was blocked by cycloheximide and actinomycin D, indicating that de novo protein synthesis is essential for this process. Reduced thrombin-induced VEGF secretion upon treatment with LY294002, calphostin C, or BAPTA, further suggests that the process is dependent on phosphatidyl-inositol-3-kinase, protein kinase C, and calcium. However, the complete loss of thrombin-induced VEGF production upon treatment with argatroban, a derivative of arginine and a potent anticoagulant/antithrombin agent, supports the notion that argatroban serves as a useful therapeutic tool for thrombin-associated pathologic conditions. Here, it appears that argatroban may be effective in controlling disorders linked to thrombin-induced VEGF production in neuronal cells.
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Affiliation(s)
- Krishna Pada Sarker
- Department of Laboratory and Vascular Medicine, Cardiovascular and Respiratory Disorders, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan.
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45
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Clasby MC, Chackalamannil S, Czarniecki M, Doller D, Eagen K, Greenlee WJ, Lin Y, Tsai H, Xia Y, Ahn HS, Agans-Fantuzzi J, Boykow G, Chintala M, Foster C, Bryant M, Lau J. Discovery and synthesis of a novel series of quinoline-based thrombin receptor (PAR-1) antagonists. Bioorg Med Chem Lett 2005; 16:1544-8. [PMID: 16380251 DOI: 10.1016/j.bmcl.2005.12.042] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2005] [Revised: 12/05/2005] [Accepted: 12/09/2005] [Indexed: 11/26/2022]
Abstract
The design, synthesis, and SAR studies of a structurally novel series of highly potent thrombin receptor (PAR-1) antagonists are described. Compound 30 is a highly potent thrombin receptor antagonist (IC(50)=6.3 nM), a related compound 36 showing efficacy in a monkey ex vivo study.
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Affiliation(s)
- Martin C Clasby
- Central Nervous System and Cardiovascular Chemical Research, Schering-Plough Research Institute, 2015 Galloping Hill Road, Kenilworth, NJ 07033, USA.
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46
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Affiliation(s)
- D S Woulfe
- Center for Translational Medicine, Thomas Jefferson University, Philadelphia, PA 19107, USA.
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47
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Abstract
The coagulation cascade and protease-activated receptors (PARs) together provide an elegant mechanism that links mechanical information in the form of tissue injury to cellular responses. These receptors appear to largely account for the cellular effects of thrombin and can mediate signaling to other trypsin-like proteases. An important role for PARs in hemostasis and thrombosis is established in animal models, and studies in knockout mice and nonhuman primates raise the question of whether PAR inhibition might offer an appealing new approach to the prevention and treatment of thrombosis. PARs may also trigger inflammatory responses to tissue injury. For example, PAR activation on endothelial cells and perhaps sensory afferents can trigger local accumulation of leukocytes and platelets and transudation of plasma. However, panoply of signaling systems and cell types orchestrates inflammatory responses, and efforts to define the relative importance and roles of PARs in various inflammatory processes are just beginning. Lastly, roles for PARs in blood vessel formation and other processes during embryonic development are emerging, and whether these reflect new roles for the coagulation cascade and/or PAR signaling to other proteases remains to be explored.
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Affiliation(s)
- S R Coughlin
- Cardiovascular Research Institute, Department of Medicine, University of California, San Francisco, CA 94143-0130, USA.
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48
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Srivastava S, Goswami LN, Dikshit DK. Progress in the design of low molecular weight thrombin inhibitors. Med Res Rev 2005; 25:66-92. [PMID: 15389730 DOI: 10.1002/med.20016] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Intravascular thrombosis and its complication, embolism, is a leading cause of morbidity and mortality throughout the world. Past few decades have seen a great deal of progress in the development of antithrombotic agents, though the current treatment options are limited to heparin, LMW heparins, and warfarin. Detailed understanding of the biochemical and biophysical mechanisms of activation and regulation of blood coagulation have helped in developing specific inhibitors of enzymes, especially thrombin, within the coagulation cascade. Thrombin plays a central role in the coagulation cascade and so has become the primary target for the development of antithrombotic drugs. The review covers the main pharmacological aspects of haemostasis and thrombosis and provides an update on low molecular weight thrombin inhibitors along with the limitations of the prevalent antithrombotic agents. Recent developments in small molecule inhibitors of Protease Activated Receptor-1 (PAR-1) which can be helpful for the treatment of thrombotic and vascular proliferative disorders, have also been discussed.
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Affiliation(s)
- Stuti Srivastava
- Medicinal Chemistry Division, Central Drug Research Institute, Lucknow, India
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49
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Kristiansen K. Molecular mechanisms of ligand binding, signaling, and regulation within the superfamily of G-protein-coupled receptors: molecular modeling and mutagenesis approaches to receptor structure and function. Pharmacol Ther 2004; 103:21-80. [PMID: 15251227 DOI: 10.1016/j.pharmthera.2004.05.002] [Citation(s) in RCA: 392] [Impact Index Per Article: 19.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The superfamily of G-protein-coupled receptors (GPCRs) could be subclassified into 7 families (A, B, large N-terminal family B-7 transmembrane helix, C, Frizzled/Smoothened, taste 2, and vomeronasal 1 receptors) among mammalian species. Cloning and functional studies of GPCRs have revealed that the superfamily of GPCRs comprises receptors for chemically diverse native ligands including (1) endogenous compounds like amines, peptides, and Wnt proteins (i.e., secreted proteins activating Frizzled receptors); (2) endogenous cell surface adhesion molecules; and (3) photons and exogenous compounds like odorants. The combined use of site-directed mutagenesis and molecular modeling approaches have provided detailed insight into molecular mechanisms of ligand binding, receptor folding, receptor activation, G-protein coupling, and regulation of GPCRs. The vast majority of family A, B, C, vomeronasal 1, and taste 2 receptors are able to transduce signals into cells through G-protein coupling. However, G-protein-independent signaling mechanisms have also been reported for many GPCRs. Specific interaction motifs in the intracellular parts of these receptors allow them to interact with scaffold proteins. Protein engineering techniques have provided information on molecular mechanisms of GPCR-accessory protein, GPCR-GPCR, and GPCR-scaffold protein interactions. Site-directed mutagenesis and molecular dynamics simulations have revealed that the inactive state conformations are stabilized by specific interhelical and intrahelical salt bridge interactions and hydrophobic-type interactions. Constitutively activating mutations or agonist binding disrupts such constraining interactions leading to receptor conformations that associates with and activate G-proteins.
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Affiliation(s)
- Kurt Kristiansen
- Department of Pharmacology, Institute of Medical Biology, University of Tromsø, N-9037 Tromsø, Norway.
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50
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Abstract
Proteases acting at the surface of cells generate and destroy receptor agonists and activate and inactivate receptors, thereby making a vitally important contribution to signal transduction. Certain serine proteases that derive from the circulation (e.g., coagulation factors), inflammatory cells (e.g., mast cell and neutrophil proteases), and from multiple other sources (e.g., epithelial cells, neurons, bacteria, fungi) can cleave protease-activated receptors (PARs), a family of four G protein-coupled receptors. Cleavage within the extracellular amino terminus exposes a tethered ligand domain, which binds to and activates the receptors to initiate multiple signaling cascades. Despite this irreversible mechanism of activation, signaling by PARs is efficiently terminated by receptor desensitization (receptor phosphorylation and uncoupling from G proteins) and downregulation (receptor degradation by cell-surface and lysosomal proteases). Protease signaling in tissues depends on the generation and release of proteases, availability of cofactors, presence of protease inhibitors, and activation and inactivation of PARs. Many proteases that activate PARs are produced during tissue damage, and PARs make important contributions to tissue responses to injury, including hemostasis, repair, cell survival, inflammation, and pain. Drugs that mimic or interfere with these processes are attractive therapies: selective agonists of PARs may facilitate healing, repair, and protection, whereas protease inhibitors and PAR antagonists can impede exacerbated inflammation and pain. Major future challenges will be to understand the role of proteases and PARs in physiological control mechanisms and human diseases and to develop selective agonists and antagonists that can be used to probe function and treat disease.
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