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Meijers JCM, van der Harst J, Marx PF, Sahbaie P, Clark DJ, Morser J. Brain Expression of CPB2 and Effects of Cpb2 Deficiency in Mouse Models of Behavior. Thromb Haemost 2024; 124:4-19. [PMID: 37532120 DOI: 10.1055/s-0043-1771304] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/04/2023]
Abstract
BACKGROUND Procarboxypeptidase B2 (proCPB2 or TAFI) is a zymogen that after activation cleaves C-terminal basic residues from peptides or proteins with many identified targets. A splice variant of CPB2 has been found in the brain lacking essential residues for its carboxypeptidase function. The aim was to determine CPB2 expression in the brain and effects of CPB2 deficiency (Cpb2 -/-) on behavior. MATERIALS AND METHODS Behavioral effects were tested by comparing Cpb2 -/- mice in short-term (open field and elevated zero maze tests) and long-term (Phenotyper) observations with wild-type (WT) controls. RESULTS Long-term observation compared day 1 (acclimatizing to novel environment) to day 4 (fully acclimatized) with the inactive (day) and active (night) periods analyzed separately. Brain expression of CPB2 mRNA and protein was interrogated in publicly available databases. Long-term observation demonstrated differences between WT and Cpb2 -/- mice in several parameters. For example, Cpb2 -/- mice moved more frequently on both days 1 and 4, especially in the normally inactive periods. Cpb2 -/- mice spent more time on the shelter and less time in it. Differences were more pronounced on day 4 after the mice had fully acclimatized. In short-term observations, no differences were observed between Cpb2 -/- mice and WT mice. Brain expression of CBP2 was not detectable in the human protein atlas. Databases of single-cell RNAseq did not show expression of CPB2 mRNA in either human or mouse brain. CONCLUSION Continuous observation of home-cage behavior suggests that Cpb2 -/- mice are more active than WT mice, show different day-night activity levels, and might have a different way of processing information.
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Affiliation(s)
- Joost C M Meijers
- Department of Experimental Vascular Medicine, Amsterdam UMC, Amsterdam, The Netherlands
- Amsterdam Cardiovascular Sciences, Pulmonary Hypertension and Thrombosis, Amsterdam, The Netherlands
- Department of Molecular Hematology, Sanquin Research, Amsterdam, The Netherlands
| | | | - Pauline F Marx
- Department of Experimental Vascular Medicine, Amsterdam UMC, Amsterdam, The Netherlands
| | - Peyman Sahbaie
- Department of Anesthesiology, Perioperative and Pain Medicine, Stanford University School of Medicine, Stanford, California, United States
- Anesthesiology Service, Veterans Affairs Palo Alto Health Care System, Palo Alto, California, United States
| | - David J Clark
- Department of Anesthesiology, Perioperative and Pain Medicine, Stanford University School of Medicine, Stanford, California, United States
- Anesthesiology Service, Veterans Affairs Palo Alto Health Care System, Palo Alto, California, United States
| | - John Morser
- Division of Hematology, Stanford University School of Medicine, Stanford, California, United States
- Palo Alto Institute of Research and Education, Veterans Affairs Palo Alto Health Care System, Palo Alto, California, United States
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2
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Mutch NJ, Medcalf RL. The fibrinolysis renaissance. J Thromb Haemost 2023; 21:3304-3316. [PMID: 38000850 DOI: 10.1016/j.jtha.2023.09.012] [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: 09/06/2023] [Revised: 09/13/2023] [Accepted: 09/13/2023] [Indexed: 11/26/2023]
Abstract
Fibrinolysis is the system primarily responsible for removal of fibrin deposits and blood clots in the vasculature. The terminal enzyme in the pathway, plasmin, is formed from its circulating precursor, plasminogen. Fibrin is by far the most legendary substrate, but plasmin is notoriously prolific and is known to cleave many other proteins and participate in the activation of other proteolytic systems. Fibrinolysis is often overshadowed by the coagulation system and viewed as a simplistic poorer relation. However, the primordial plasminogen activators evolved alongside the complement system, approximately 70 million years before coagulation saw the light of day. It is highly likely that the plasminogen activation system evolved with its roots in primordial immunity. Almost all immune cells harbor at least one of a dozen plasminogen receptors that allow plasmin formation on the cell surface that in turn modulates immune cell behavior. Similarly, numerous pathogens express their own plasminogen activators or contain surface proteins that provide binding sites for host plasminogen. The fibrinolytic system has been harnessed for clinical medicine for many decades with the development of thrombolytic drugs and antifibrinolytic agents. Our refined understanding and appreciation of the fibrinolytic system and its alliance with infection and immunity and beyond are paving the way for new developments and interest in novel therapeutics and applications. One must ponder as to whether the nomenclature of the system hampered our understanding, by focusing on fibrin, rather than the complex myriad of interactions and substrates of the plasminogen activation system.
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Affiliation(s)
- Nicola J Mutch
- Aberdeen Cardiovascular & Diabetes Centre, Institute of Medical Sciences, School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Foresterhill, Aberdeen, UK.
| | - Robert L Medcalf
- Australian Centre for Blood Diseases, Central Clinical School, Monash University, Melbourne, Victoria, Australia
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3
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Chen R, Huang M, Xu P. Polyphosphate as an antithrombotic target and hemostatic agent. J Mater Chem B 2023; 11:7855-7872. [PMID: 37534776 DOI: 10.1039/d3tb01152f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/04/2023]
Abstract
Polyphosphate (PolyP) is a polymer comprised of linear phosphate units connected by phosphate anhydride bonds. PolyP exists in a diverse range of eukaryotes and prokaryotes with varied chain lengths ranging from six to thousands of phosphate units. Upon activation, human platelets and neutrophils release short-chain PolyP, along with other components, to initiate the coagulation pathway. Long-chain PolyP derived from cellular or bacterial organelles exhibits higher proinflammatory and procoagulant effects compared to short-chain PolyP. Notably, PolyP has been identified as a low-hemorrhagic antithrombotic target since neutralizing plasma PolyP suppresses the thrombotic process without impairing the hemostatic functions. As an inorganic polymer without uniform steric configuration, PolyP is typically targeted by cationic polymers or recombinant polyphosphatases rather than conventional antibodies, small-molecule compounds, or peptides. Additionally, because of its procoagulant property, PolyP has been incorporated in wound-dressing materials to facilitate blood hemostasis. This review summarizes current studies on PolyP as a low-hemorrhagic antithrombotic target and the development of hemostatic materials based on PolyP.
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Affiliation(s)
- Ruoyu Chen
- College of Biological Science and Engineering, Fuzhou University, Fuzhou, Fujian, 350108, P. R. China.
| | - Mingdong Huang
- College of Biological Science and Engineering, Fuzhou University, Fuzhou, Fujian, 350108, P. R. China.
- College of Chemistry, Fuzhou University, Fuzhou, Fujian, 350108, P. R. China
| | - Peng Xu
- College of Biological Science and Engineering, Fuzhou University, Fuzhou, Fujian, 350108, P. R. China.
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Elías-Sáenz I, Rodríguez-Otero N, Fernández-Lozano C, Bartolomé-Zavala B, González-de-Olano D. Zymogen granule protein 16-like and carboxypeptidase B, new allergens in hedgehog hypersensitivity. Ann Allergy Asthma Immunol 2023; 131:273-274. [PMID: 37253408 DOI: 10.1016/j.anai.2023.05.026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Revised: 05/22/2023] [Accepted: 05/23/2023] [Indexed: 06/01/2023]
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Garabon JJW, Boffa MB. Profibrinolytic effects of rivaroxaban are mediated by thrombin-activatable fibrinolysis inhibitor and are attenuated by a naturally occurring stabilizing mutation in enzyme. J Thromb Thrombolysis 2023:10.1007/s11239-023-02837-3. [PMID: 37310666 DOI: 10.1007/s11239-023-02837-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 05/22/2023] [Indexed: 06/14/2023]
Abstract
Rivaroxaban is a direct factor Xa inhibitor, recently implemented as a favorable alternative to warfarin in anticoagulation therapy. Rivaroxaban effectively reduces thrombin generation, which plays a major role in the activation of thrombin activatable fibrinolysis inhibitor (TAFI) to TAFIa. Based on the antifibrinolytic role of TAFIa, we hypothesized that rivaroxaban would consequently induce more rapid clot lysis. In vitro clot lysis assays were used to explore this hypothesis and additionally determine the effects of varying TAFI levels and a stabilizing Thr325Ile polymorphism (rs1926447) in the TAFI protein on the effects of rivaroxaban. Rivaroxaban was shown to decrease thrombin generation, resulting in less TAFI activation, thus enhancing lysis. These effects were also shown to be less substantial in the presence of greater TAFI levels or the more stable Ile325 enzyme. These findings suggest a role for TAFI levels and the Thr325Ile polymorphism in the pharmacodynamics and pharmacogenomics of rivaroxaban.
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Affiliation(s)
- Justin J W Garabon
- Department of Chemistry & Biochemistry, University of Windsor, Windsor, ON, Canada
| | - Michael B Boffa
- Department of Biochemistry, Room 4245A Robarts Research Institute, The University of Western Ontario, 1151 Richmond Street North, London, ON, N6A 5B7, Canada.
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van Moorsel MVA, Poolen GC, Koekman CA, Verhoef S, de Maat S, Barendrecht A, van Kleef ND, Meijers JCM, Schiffelers RM, Maas C, Urbanus RT. VhH anti-thrombomodulin clone 1 inhibits TAFI activation and enhances fibrinolysis in human whole blood under flow. J Thromb Haemost 2022; 20:1213-1222. [PMID: 35170225 PMCID: PMC9311061 DOI: 10.1111/jth.15674] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2021] [Revised: 02/09/2022] [Accepted: 02/10/2022] [Indexed: 11/28/2022]
Abstract
BACKGROUND Thrombomodulin on endothelial cells can form a complex with thrombin. This complex has both anticoagulant properties, by activating protein C, and clot-protective properties, by activating thrombin-activatable fibrinolysis inhibitor (TAFI). Activated TAFI (TAFIa) inhibits plasmin-mediated fibrinolysis. OBJECTIVES TAFIa inhibition is considered a potential antithrombotic strategy. So far, this goal has been pursued by developing compounds that directly inhibit TAFIa. In contrast, we here describe variable domain of heavy-chain-only antibody (VhH) clone 1 that inhibits TAFI activation by targeting human thrombomodulin. METHODS Two llamas (Lama Glama) were immunized, and phage display was used to select VhH anti-thrombomodulin (TM) clone 1. Affinity was determined with surface plasmon resonance and binding to native TM was confirmed with flow cytometry. Clone 1 was functionally assessed by competition, clot lysis, and thrombin generation assays. Last, the effect of clone 1 on tPA-mediated fibrinolysis in human whole blood was investigated in a microfluidic fibrinolysis model. RESULTS VhH anti-TM clone 1 bound recombinant TM with a binding affinity of 1.7 ± 0.4 nM and showed binding to native TM. Clone 1 competed with thrombin for binding to TM and attenuated TAFI activation in clot lysis assays and protein C activation in thrombin generation experiments. In a microfluidic fibrinolysis model, inhibition of TM with clone 1 fully prevented TAFI activation. DISCUSSION We have developed VhH anti-TM clone 1, which inhibits TAFI activation and enhances tPA-mediated fibrinolysis under flow. Different from agents that directly target TAFIa, our strategy should preserve direct TAFI activation via thrombin.
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Affiliation(s)
- Marc V. A. van Moorsel
- Central Diagnostic LaboratoryUniversity Medical Center UtrechtUtrecht UniversityUtrechtThe Netherlands
| | - Geke C. Poolen
- Central Diagnostic LaboratoryUniversity Medical Center UtrechtUtrecht UniversityUtrechtThe Netherlands
- Center for Benign HaematologyThrombosis and HaemostasisVan Creveldkliniek, University Medical Center UtrechtUtrecht UniversityUtrechtThe Netherlands
| | - Cornelis A. Koekman
- Central Diagnostic LaboratoryUniversity Medical Center UtrechtUtrecht UniversityUtrechtThe Netherlands
| | - Sandra Verhoef
- Central Diagnostic LaboratoryUniversity Medical Center UtrechtUtrecht UniversityUtrechtThe Netherlands
| | - Steven de Maat
- Central Diagnostic LaboratoryUniversity Medical Center UtrechtUtrecht UniversityUtrechtThe Netherlands
| | - Arjan Barendrecht
- Central Diagnostic LaboratoryUniversity Medical Center UtrechtUtrecht UniversityUtrechtThe Netherlands
| | - Nadine D. van Kleef
- Central Diagnostic LaboratoryUniversity Medical Center UtrechtUtrecht UniversityUtrechtThe Netherlands
| | - Joost C. M. Meijers
- Department of Experimental Vascular MedicineAmsterdam Cardiovascular Sciences, Amsterdam UMCUniversity of AmsterdamAmsterdamThe Netherlands
- Department of Molecular HematologySanquin ResearchAmsterdamThe Netherlands
| | - Raymond M. Schiffelers
- Central Diagnostic LaboratoryUniversity Medical Center UtrechtUtrecht UniversityUtrechtThe Netherlands
| | - Coen Maas
- Central Diagnostic LaboratoryUniversity Medical Center UtrechtUtrecht UniversityUtrechtThe Netherlands
| | - Rolf T. Urbanus
- Central Diagnostic LaboratoryUniversity Medical Center UtrechtUtrecht UniversityUtrechtThe Netherlands
- Center for Benign HaematologyThrombosis and HaemostasisVan Creveldkliniek, University Medical Center UtrechtUtrecht UniversityUtrechtThe Netherlands
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Akula S, Hellman L, Avilés FX, Wernersson S. Analysis of the mast cell expressed carboxypeptidase A3 and its structural and evolutionary relationship to other vertebrate carboxypeptidases. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2022; 127:104273. [PMID: 34619175 DOI: 10.1016/j.dci.2021.104273] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Revised: 09/28/2021] [Accepted: 09/28/2021] [Indexed: 06/13/2023]
Abstract
Metallo-carboxypeptidases are exopeptidases with diverse expression and function, found in all kingdoms of life from bacteria to mammals. One of them, the carboxypeptidase A3 (CPA3), has become an important component of the mammalian immune system by its expression in mast cells. Mast cells (MCs) are highly specialized sentinel cells, which store large amounts of bioactive mediators, including CPA3, in very abundant cytoplasmic granules. Clinical studies have found an increased CPA3 expression in asthma but the physiological role as well as the evolutionary origin of CPA3 remains largely unexplored. CPA3 belongs to the M14A subfamily of metallo-carboxypeptidases, which among others also includes the digestive enzymes CPA1, CPA2, CPB1 and CPO. To study the appearance of CPA3 during vertebrate evolution, we here performed bioinformatic analyses of homologous genes and gene loci from a broad panel of metazoan animals from invertebrates to mammals. The phylogenetic analysis indicated that CPA3 appeared at the base of tetrapod evolution in a branch closer to CPB1 than to other CPAs. Indeed, CPA3 and CPB1 are also located in the same locus, on chromosome 3 in humans. The presence of CPA3 only in tetrapods and not in fishes, suggested that CPA3 could have appeared by a gene duplication from CPB1 during early tetrapod evolution. However, the apparent loss of CPA3 in several tetrapod lineages, e.g. in birds and monotremes, indicates a complex evolution of the CPA3 gene. Interestingly, in the lack of CPA3 in fishes, zebrafish MCs express instead CPA5 for which the most closely related human carboxypeptidase is CPA1, which has a similar cleavage specificity as CPA3. Collectively, these findings clarify and add to our understanding of the evolution of hematopoietic proteases expressed by mast cells.
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Affiliation(s)
- Srinivas Akula
- Department of Anatomy, Physiology and Biochemistry, Swedish University of Agricultural Sciences, BOX 7011, SE-75007, Uppsala, Sweden; Department of Cell and Molecular Biology, Uppsala University, Uppsala, The Biomedical Center, Box 596, SE-751 24, Uppsala, Sweden.
| | - Lars Hellman
- Department of Cell and Molecular Biology, Uppsala University, Uppsala, The Biomedical Center, Box 596, SE-751 24, Uppsala, Sweden
| | - Francesc Xavier Avilés
- Institut de Biotecnologia i de Biomedicina (IBB) and Departament de Bioquímica i de Biologia Molecular, Universitat Autònoma de Barcelona, Bellaterra, Barcelona, Spain
| | - Sara Wernersson
- Department of Anatomy, Physiology and Biochemistry, Swedish University of Agricultural Sciences, BOX 7011, SE-75007, Uppsala, Sweden
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8
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Mathews NS, Suzuki Y, Honkura N, Sano H, Iwashita T, Urano T. Pre-administration of a carboxypeptidase inhibitor enhances tPA-induced thrombolysis in mouse microthrombi: Evidence from intravital imaging analysis. Thromb Res 2022; 210:78-86. [PMID: 35030422 DOI: 10.1016/j.thromres.2021.12.031] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Revised: 12/21/2021] [Accepted: 12/30/2021] [Indexed: 11/28/2022]
Abstract
INTRODUCTION Thrombolysis using recombinant tissue-type plasminogen activator (rt-PA) is the pharmacological treatment of choice in acute thrombotic events. However, a narrow therapeutic window and bleeding complications limit its use. We describe the role of carboxypeptidase inhibitor from potato tuber (PTCI), an inhibitor of activated thrombin-activatable fibrinolysis inhibitor (TAFIa), on Glu-plasminogen accumulation and microthrombus dynamics in vivo and demonstrate its influence on rt-PA-mediated thrombolysis. MATERIALS AND METHODS In conjunction with real-time intravital two-photon excitation fluorescence microscopy, we produced and imaged laser-induced microthrombi in the mesenteric venules of Green Fluorescent Protein (GFP)-expressing mice. We examined microthrombus dynamics and thrombolysis patterns in vivo by measuring the changes in the fluorescence intensity of labeled Glu-plasminogen following administration of epsilon aminocaproic acid (EACA), PTCI, and rt-PA. RESULTS PTCI enhanced Glu-plasminogen accumulation at the core of the thrombus by inhibiting TAFIa, while EACA inhibited this process. Exogenous rt-PA effectively triggered Glu-plasminogen activation within the thrombus and promoted thrombolysis. Administration of PTCI and rt-PA together showed no significant benefit on thrombolysis compared to rt-PA administration alone. However, early-phase systemic administration of PTCI before thrombolytic therapy by rt-PA expedited clot lysis as evidenced by significantly faster time to reach peak Glu-plasminogen fluorescence intensity and shorter time to achieve near-complete clot lysis (P = 0.014 and P = 0.003, respectively). CONCLUSIONS PTCI potentiates rt-PA-mediated thrombolysis when administered early in acute thrombotic events. Further studies are warranted to explore the potential of TAFI inhibitors as adjunct agents in thrombolysis or thromboprophylaxis.
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Affiliation(s)
- Nitty Skariah Mathews
- Department of Medical Physiology, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu city, Shizuoka 431-3192, Japan.
| | - Yuko Suzuki
- Department of Medical Physiology, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu city, Shizuoka 431-3192, Japan.
| | - Naoki Honkura
- Department of Medical Physiology, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu city, Shizuoka 431-3192, Japan.
| | - Hideto Sano
- Department of Medical Physiology, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu city, Shizuoka 431-3192, Japan.
| | - Toshihide Iwashita
- Department of Regenerative & Infectious Pathology, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu city, Shizuoka 431-3192, Japan.
| | - Tetsumei Urano
- Department of Medical Physiology, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu city, Shizuoka 431-3192, Japan; Shizuoka Graduate University of Public Health, 4-17-2, Kita-Ando, Aoi-ku Shizuoka 420-0882, Japan.
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Zhou Q, Zhao L, Shao Z, Declerck P, Leung LLK, Morser J. Both plasma basic carboxypeptidases, carboxypeptidase B2 and carboxypeptidase N, regulate vascular leakage activity in mice. J Thromb Haemost 2022; 20:238-244. [PMID: 34626062 DOI: 10.1111/jth.15551] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Accepted: 10/07/2021] [Indexed: 12/12/2022]
Abstract
BACKGROUND Kallikrein is generated when the contact system is activated, subsequently cleaving high molecular weight kininogen to bradykinin (BK). BK binds to bradykinin receptor 2, causing vascular leakage. BK is inactivated by proteolysis by the plasma carboxypeptidase B2 and N (CPB2 and CPN). CPN is constitutively active but CPB2 is generated from its zymogen, proCPB2. OBJECTIVES Determine the role of CPB2 and CPN in the regulation of vascular leakage. METHODS Mice deficient in CPB2, CPN, or both (Cpb2-/- , Cpn-/- , and Cpb2-/- /Cpn-/- ) were compared with wild-type mice (WT) in a model of vascular leakage caused by skin irritation. In some experiments, mice were pretreated with antibodies that prevent activation of proCPB2. RESULTS Skin irritation increased vascular leakage most in Cpb2-/- /Cpn-/- , less in Cpb2-/- and Cpn-/- , and least in WT mice. There was no difference in vascular leakage without the challenge. Antibodies inhibiting activation of proCPB2 by plasmin, but not by the thrombin/thrombomodulin complex, increased vascular leakage to the level seen in Cpb2-/- mice. There was no change in levels of markers of coagulation and fibrinolysis. CONCLUSIONS Bradykinin is inactivated by both CPB2 and CPN independently. Plasmin is the activator of proCPB2 in this model. Mice lacking both plasma carboxypeptidases have more vascular leak than those lacking either alone. Although BK levels were not determined, BK is the likely substrate for CPB2 and CPN in this model.
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Affiliation(s)
- Qin Zhou
- Division of Hematology, Stanford University School of Medicine, Stanford, California, USA
- Veterans Affairs Palo Alto Health Care System, Palo Alto, California, USA
| | - Lei Zhao
- Division of Hematology, Stanford University School of Medicine, Stanford, California, USA
- Veterans Affairs Palo Alto Health Care System, Palo Alto, California, USA
| | - Zhifei Shao
- Division of Hematology, Stanford University School of Medicine, Stanford, California, USA
- Veterans Affairs Palo Alto Health Care System, Palo Alto, California, USA
| | - Paul Declerck
- Laboratory for Therapeutic and Diagnostic Antibodies, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, Leuven, Belgium
| | - Lawrence L K Leung
- Division of Hematology, Stanford University School of Medicine, Stanford, California, USA
- Veterans Affairs Palo Alto Health Care System, Palo Alto, California, USA
| | - John Morser
- Division of Hematology, Stanford University School of Medicine, Stanford, California, USA
- Veterans Affairs Palo Alto Health Care System, Palo Alto, California, USA
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Fibrinogen and Antifibrinolytic Proteins: Interactions and Future Therapeutics. Int J Mol Sci 2021; 22:ijms222212537. [PMID: 34830419 PMCID: PMC8625824 DOI: 10.3390/ijms222212537] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2021] [Revised: 11/17/2021] [Accepted: 11/18/2021] [Indexed: 12/13/2022] Open
Abstract
Thrombus formation remains a major cause of morbidity and mortality worldwide. Current antiplatelet and anticoagulant therapies have been effective at reducing vascular events, but at the expense of increased bleeding risk. Targeting proteins that interact with fibrinogen and which are involved in hypofibrinolysis represents a more specific approach for the development of effective and safe therapeutic agents. The antifibrinolytic proteins alpha-2 antiplasmin (α2AP), thrombin activatable fibrinolysis inhibitor (TAFI), complement C3 and plasminogen activator inhibitor-2 (PAI-2), can be incorporated into the fibrin clot by FXIIIa and affect fibrinolysis by different mechanisms. Therefore, these antifibrinolytic proteins are attractive targets for the development of novel therapeutics, both for the modulation of thrombosis risk, but also for potentially improving clot instability in bleeding disorders. This review summarises the main properties of fibrinogen-bound antifibrinolytic proteins, their effect on clot lysis and association with thrombotic or bleeding conditions. The role of these proteins in therapeutic strategies targeting the fibrinolytic system for thrombotic diseases or bleeding disorders is also discussed.
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Activated platelet-based inhibition of fibrinolysis via thrombin-activatable fibrinolysis inhibitor activation system. Blood Adv 2021; 4:5501-5511. [PMID: 33166409 DOI: 10.1182/bloodadvances.2020002923] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2020] [Accepted: 10/12/2020] [Indexed: 12/20/2022] Open
Abstract
Our previous real-time imaging studies directly demonstrated the spatiotemporal regulation of clot formation and lysis by activated platelets. In addition to their procoagulant functions, platelets enhanced profibrinolytic potential by augmenting the accumulation of tissue-type plasminogen activator (tPA) and plasminogen, in vivo in a murine microthrombus model, and in vitro in a platelet-containing plasma clot model. To clarify the role of thrombin-activatable fibrinolysis inhibitor (TAFI), which regulates coagulation-dependent anti-fibrinolytic potential, we analyzed tPA-induced clot lysis times in platelet-containing plasma. Platelets prolonged clot lysis times in a concentration-dependent manner, which were successfully abolished by a thrombomodulin-neutralizing antibody or an activated TAFI inhibitor (TAFIaI). The results obtained using TAFI- or factor XIII-deficient plasma suggested that TAFI in plasma, but not in platelets, was essential for this prolongation, though its cross-linkage with fibrin was not necessary. Confocal laser scanning microscopy revealed that fluorescence-labeled plasminogen accumulated on activated platelet surfaces and propagated to the periphery, similar to the propagation of fibrinolysis. Plasminogen accumulation and propagation were both enhanced by TAFIaI, but only accumulation was enhanced by thrombomodulin-neutralizing antibody. Labeled TAFI also accumulated on both fibrin fibers and activated platelet surfaces, which were Lys-binding-site-dependent and Lys-binding-site-independent, respectively. Finally, TAFIaI significantly prolonged the occlusion times of tPA-containing whole blood in a microchip-based flow chamber system, suggesting that TAFI attenuated the tPA-dependent prolongation of clot formation under flow. Thus, activated platelet surfaces are targeted by plasma TAFI, to attenuate plasminogen accumulation and fibrinolysis, which may contribute to thrombogenicity under flow.
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Sillen M, Declerck PJ. Thrombin Activatable Fibrinolysis Inhibitor (TAFI): An Updated Narrative Review. Int J Mol Sci 2021; 22:ijms22073670. [PMID: 33916027 PMCID: PMC8036986 DOI: 10.3390/ijms22073670] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Revised: 03/26/2021] [Accepted: 03/29/2021] [Indexed: 01/02/2023] Open
Abstract
Thrombin activatable fibrinolysis inhibitor (TAFI), a proenzyme, is converted to a potent attenuator of the fibrinolytic system upon activation by thrombin, plasmin, or the thrombin/thrombomodulin complex. Since TAFI forms a molecular link between coagulation and fibrinolysis and plays a potential role in venous and arterial thrombotic diseases, much interest has been tied to the development of molecules that antagonize its function. This review aims at providing a general overview on the biochemical properties of TAFI, its (patho)physiologic function, and various strategies to stimulate the fibrinolytic system by interfering with (activated) TAFI functionality.
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Claesen K, Mertens JC, Leenaerts D, Hendriks D. Carboxypeptidase U (CPU, TAFIa, CPB2) in Thromboembolic Disease: What Do We Know Three Decades after Its Discovery? Int J Mol Sci 2021; 22:ijms22020883. [PMID: 33477318 PMCID: PMC7830380 DOI: 10.3390/ijms22020883] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2020] [Revised: 01/12/2021] [Accepted: 01/13/2021] [Indexed: 02/01/2023] Open
Abstract
Procarboxypeptidase U (proCPU, TAFI, proCPB2) is a basic carboxypeptidase zymogen that is converted by thrombin(-thrombomodulin) or plasmin into the active carboxypeptidase U (CPU, TAFIa, CPB2), a potent attenuator of fibrinolysis. As CPU forms a molecular link between coagulation and fibrinolysis, the development of CPU inhibitors as profibrinolytic agents constitutes an attractive new concept to improve endogenous fibrinolysis or to increase the efficacy of thrombolytic therapy in thromboembolic diseases. Furthermore, extensive research has been conducted on the in vivo role of CPU in (the acute phase of) thromboembolic disease, as well as on the hypothesis that high proCPU levels and the Thr/Ile325 polymorphism may cause a thrombotic predisposition. In this paper, an overview is given of the methods available for measuring proCPU, CPU, and inactivated CPU (CPUi), together with a summary of the clinical data generated so far, ranging from the current knowledge on proCPU concentrations and polymorphisms as potential thromboembolic risk factors to the positioning of different CPU forms (proCPU, CPU, and CPUi) as diagnostic markers for thromboembolic disease, and the potential benefit of pharmacological inhibition of the CPU pathway.
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14
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Mutch NJ. Regulation of Fibrinolysis by Platelets. Platelets 2019. [DOI: 10.1016/b978-0-12-813456-6.00023-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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15
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Pryzdial ELG, Lee FMH, Lin BH, Carter RLR, Tegegn TZ, Belletrutti MJ. Blood coagulation dissected. Transfus Apher Sci 2018; 57:449-457. [PMID: 30049564 DOI: 10.1016/j.transci.2018.07.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Hemostasis is the physiological control of bleeding and is initiated by subendothelial exposure. Platelets form the primary vascular seal in three stages (localization, stimulation and aggregation), which are triggered by specific interactions between platelet surface receptors and constituents of the subendothelial matrix. As a secondary hemostatic plug, fibrin clot formation is initiated and feedback-amplified to advance the seal and stabilize platelet aggregates comprising the primary plug. Once blood leakage has been halted, the fibrinolytic pathway is initiated to dissolve the clot and restore normal blood flow. Constitutive and induced anticoagulant and antifibrinolytic pathways create a physiological balance between too much and too little clot production. Hemostatic imbalance is a major burden to global healthcare, resulting in thrombosis or hemorrhage.
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Affiliation(s)
- Edward L G Pryzdial
- Centre for Innovation, Canadian Blood Services, Ottawa, ON, Canada; Centre for Blood Research, University of British Columbia, Vancouver, BC, Canada; Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC, Canada.
| | - Frank M H Lee
- Centre for Blood Research, University of British Columbia, Vancouver, BC, Canada; Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC, Canada
| | - Bryan H Lin
- Centre for Blood Research, University of British Columbia, Vancouver, BC, Canada; Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC, Canada
| | - Rolinda L R Carter
- Centre for Blood Research, University of British Columbia, Vancouver, BC, Canada; Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC, Canada
| | - Tseday Z Tegegn
- Centre for Innovation, Canadian Blood Services, Ottawa, ON, Canada; Centre for Blood Research, University of British Columbia, Vancouver, BC, Canada; Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC, Canada
| | - Mark J Belletrutti
- Pediatric Hematology, Department of Pediatrics, University of Alberta, Edmonton, AB, Canada
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16
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Leung LLK, Morser J. Carboxypeptidase B2 and carboxypeptidase N in the crosstalk between coagulation, thrombosis, inflammation, and innate immunity. J Thromb Haemost 2018; 16:S1538-7836(22)02219-X. [PMID: 29883024 DOI: 10.1111/jth.14199] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Indexed: 02/06/2023]
Abstract
Two basic carboxypeptidases, carboxypeptidase B2 (CPB2) and carboxypeptidase N (CPN) are present in plasma. CPN is constitutively active, whereas CPB2 circulates as a precursor, procarboxypeptidase B2 (proCPB2), that needs to be activated by the thrombin-thrombomodulin complex or plasmin bound to glycosaminoglycans. The substrate specificities of CPB2 and CPN are similar; they both remove C-terminal basic amino acids from bioactive peptides and proteins, thereby inactivating them. The complement cascade is a cascade of proteases and cofactors activated by pathogens or dead cells, divided into two phases, with the second phase only being triggered if sufficient C3b is present. Complement activation generates anaphylatoxins: C3a, which stimulates macrophages; and C5a, which is an activator and attractant for neutrophils. Pharmacological intervention with inhibitors has shown that CPB2 delays fibrinolysis, whereas CPN is responsible for systemic inactivation of C3a and C5a. Among mice genetically deficient in either CPB2 or CPN, in a model of hemolytic-uremic syndrome, Cpb2-/- mice had the worst disease, followed by Cpn-/- mice, with wild-type (WT) mice being the most protected. This model is driven by C5a, and shows that CPB2 is important in inactivating C5a. In contrast, when mice were challenged acutely with cobra venom factor, the reverse phenotype was observed; Cpn-/- mice had markedly worse disease than Cpb2-/- mice, and WT mice were resistant. These observations need to be confirmed in humans. Therefore, CPB2 and CPN have different roles. CPN inactivates C3a and C5a generated spontaneously, whereas proCPB2 is activated at specific sites, where it inactivates bioactive peptides that would overwhelm CPN.
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Affiliation(s)
- L L K Leung
- Division of Hematology, Department of Medicine, Stanford University School of Medicine, Stanford, CA, USA
- Veterans Affairs Palo Alto Health Care System, Palo Alto, CA, USA
| | - J Morser
- Division of Hematology, Department of Medicine, Stanford University School of Medicine, Stanford, CA, USA
- Veterans Affairs Palo Alto Health Care System, Palo Alto, CA, USA
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17
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Morser J, Shao Z, Nishimura T, Zhou Q, Zhao L, Higgins J, Leung LLK. Carboxypeptidase B2 and N play different roles in regulation of activated complements C3a and C5a in mice. J Thromb Haemost 2018; 16:991-1002. [PMID: 29383821 PMCID: PMC8491566 DOI: 10.1111/jth.13964] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2017] [Indexed: 12/24/2022]
Abstract
Essentials Two basic carboxypeptidases are present in plasma, B2 (CPB2) and N (CPN). Cpb2-/- and Cpn-/- mice were challenged in a hemolytic uremic syndrome (HUS) model vs. wild type. Cpb2-/- exacerbates HUS while Cpn-/- exacerbates cobra venom factor challenge vs. wild type mice. CPB2 and CPN have overlapping but non-redundant roles. SUMMARY Background There are two basic carboxypeptidases in plasma. Carboxypeptidase B2 (CPB2) is activated from a circulating zymogen, proCPB2, and carboxypeptidase N (CPN) is constitutively active with both inactivating complement C3a and C5a. Aims To test the roles of CPB2 and CPN in complement-driven mouse models of cobra venom factor (CVF) challenge and hemolytic-uremic syndrome (HUS). Methods Cpb2-/- , Cpn-/- and wild-type (WT) mice were compared in an HUS model induced by Shiga toxin and lipopolysaccharide administration and following CVF administration. Results HUS was exacerbated in Cpb2-/- mice more than in Cpn-/- mice, compared with WT mice. Cpb2-/- mice developed the HUS clinical triad of microangiopathic hemolytic anemia, uremia and thrombocytopenia. Treatment with anti-C5 antibody improved survival of both Cpb2-/- and Cpn-/- mice. In contrast, when challenged acutely with CVF, the reverse phenotype was observed. Cpn-/- mice had markedly worse disease than Cpb2-/- mice, whereas the WT mice were resistant. Conclusions CPN and CPB2 play overlapping but non-redundant roles in regulating complement activation in vivo. The constitutively active CPN is key for inactivation of systemic C5a, whereas CPB2 functions as an on-demand supplementary anaphylatoxin inhibitor in inactivating excessive C5a formed locally.
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Affiliation(s)
- J Morser
- Division of Hematology, Stanford University School of Medicine, Stanford, CA, USA
- Veterans Affairs Palo Alto Health Care System, Palo Alto, CA, USA
| | - Z Shao
- Division of Hematology, Stanford University School of Medicine, Stanford, CA, USA
- Veterans Affairs Palo Alto Health Care System, Palo Alto, CA, USA
| | - T Nishimura
- Division of Hematology, Stanford University School of Medicine, Stanford, CA, USA
- Veterans Affairs Palo Alto Health Care System, Palo Alto, CA, USA
| | - Q Zhou
- Division of Hematology, Stanford University School of Medicine, Stanford, CA, USA
- Veterans Affairs Palo Alto Health Care System, Palo Alto, CA, USA
| | - L Zhao
- Division of Hematology, Stanford University School of Medicine, Stanford, CA, USA
- Veterans Affairs Palo Alto Health Care System, Palo Alto, CA, USA
| | - J Higgins
- Department of Pathology, Stanford University School of Medicine, Stanford, CA, USA
| | - L L K Leung
- Division of Hematology, Stanford University School of Medicine, Stanford, CA, USA
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18
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Koch M, Umek W, Hanzal E, Mohr T, Seyfert S, Koelbl H, Mitulović G. Serum proteomic pattern in female stress urinary incontinence. Electrophoresis 2018; 39:1071-1078. [DOI: 10.1002/elps.201700423] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2017] [Revised: 12/27/2017] [Accepted: 01/16/2018] [Indexed: 12/14/2022]
Affiliation(s)
- Marianne Koch
- Clinical Division of General Gynecology and Gynecological Oncology; Department of Obstetrics and Gynecology; Medical University of Vienna; Vienna Austria
- Karl Landsteiner Society; St. Poelten Austria
| | - Wolfgang Umek
- Clinical Division of General Gynecology and Gynecological Oncology; Department of Obstetrics and Gynecology; Medical University of Vienna; Vienna Austria
- Karl Landsteiner Society; St. Poelten Austria
| | - Engelbert Hanzal
- Clinical Division of General Gynecology and Gynecological Oncology; Department of Obstetrics and Gynecology; Medical University of Vienna; Vienna Austria
| | - Thomas Mohr
- ScienceConsult- DI Thomas Mohr KG; Guntramsdorf Austria
| | - Sonja Seyfert
- Core Facility Proteomics; Clinical Institute of Laboratory Medicine; Medical University of Vienna; Vienna Austria
| | - Heinz Koelbl
- Clinical Division of General Gynecology and Gynecological Oncology; Department of Obstetrics and Gynecology; Medical University of Vienna; Vienna Austria
| | - Goran Mitulović
- Core Facility Proteomics; Clinical Institute of Laboratory Medicine; Medical University of Vienna; Vienna Austria
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Stanne TM, Olsson M, Lorentzen E, Pedersen A, Gummesson A, Gils A, Jood K, Engström G, Melander O, Declerck PJ, Jern C. A Genome-wide Study of Common and Rare Genetic Variants Associated with Circulating Thrombin Activatable Fibrinolysis Inhibitor. Thromb Haemost 2018; 118:298-308. [PMID: 29378355 PMCID: PMC6260132 DOI: 10.1160/th17-04-0249] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
Thrombin-activatable fibrinolysis inhibitor (TAFI) plays a central role in haemostasis, and plasma TAFI concentrations are heritable. Candidate gene studies have identified several variants within the gene encoding TAFI,
CPB2
, that explain part of the estimated heritability. Here, we describe an exploratory genome-wide association study to identify novel variants within and outside of the
CPB2
locus that influence plasma concentrations of intact TAFI and/or the extent of TAFI activation (measured by released TAFI activation peptide, TAFI-AP) amongst 3,260 subjects from Southern Sweden. We also explored the role of rare variants on the HumanExome BeadChip. We confirmed the association with previously reported common variants in
CPB2
for both intact TAFI and TAFI-AP, and discovered novel associations with variants in putative
CPB2
enhancers. We identified a gene-based association with intact TAFI at
CPB2
(
PSKAT-O
= 2.8 × 10
−8
), driven by two novel rare nonsynonymous single nucleotide polymorphisms (SNPs; I420N and D177G). Carriers of the rare variant of D177G (rs140446990; MAF 0.2%) had lower intact TAFI and TAFI-AP concentrations compared with non-carriers (intact TAFI, geometric mean 53 vs. 78%,
PT-test
=
5 × 10
−7
; TAFI-AP 63 vs. 99%,
PT-test
= 7.2 × 10
−4
). For TAFI-AP, we identified a genome-wide significant association at an intergenic region of chromosome 3p14.1 and five gene-based associations (all
PSKAT-O
< 5 × 10
−6
). Using well-characterized assays together with a genome-wide association study and a rare-variant approach, we verified
CPB2
to be the primary determinant of TAFI concentrations and identified putative secondary loci (candidate variants and genes) associated with intact TAFI and TAFI-AP that require independent validation.
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Affiliation(s)
- Tara M Stanne
- Department of Pathology and Genetics, Institute of Biomedicine, Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden
| | - Maja Olsson
- Department of Pathology and Genetics, Institute of Biomedicine, Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden
| | - Erik Lorentzen
- Bioinformatics Core Facility, University of Gothenburg, Gothenburg, Sweden
| | - Annie Pedersen
- Department of Pathology and Genetics, Institute of Biomedicine, Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden
| | - Anders Gummesson
- Department of Pathology and Genetics, Institute of Biomedicine, Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden
| | - Ann Gils
- Laboratory for Therapeutic and Diagnostic Antibodies, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, Brussels, Belgium
| | - Katarina Jood
- Department of Clinical Neuroscience, Institute of Neuroscience and Physiology, Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden
| | - Gunnar Engström
- Department of Clinical Sciences, Lund University, Lund, Sweden
| | - Olle Melander
- Department of Clinical Sciences, Lund University, Lund, Sweden
| | - Paul J Declerck
- Laboratory for Therapeutic and Diagnostic Antibodies, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, Brussels, Belgium
| | - Christina Jern
- Department of Pathology and Genetics, Institute of Biomedicine, Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden
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Nielsen SD, Beverly RL, Dallas DC. Milk Proteins Are Predigested Within the Human Mammary Gland. J Mammary Gland Biol Neoplasia 2017; 22:251-261. [PMID: 29464498 PMCID: PMC5856648 DOI: 10.1007/s10911-018-9388-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Accepted: 02/02/2018] [Indexed: 10/18/2022] Open
Abstract
Previous work demonstrates that proteases present in human milk release hundreds of peptides derived from milk proteins. However, the question of whether human milk protein digestion begins within the mammary gland remains incompletely answered. The primary objective of this study was to determine whether proteolytic degradation of human milk proteins into peptides begins within the mammary gland. The secondary objectives were to determine which milk proteases participate in the proteolysis and to predict which released peptides have bioactivity. Lactating mothers (n = 4) expressed their milk directly into a mixture of antiproteases on ice followed by immediate freezing of the milk to limit post-expression protease activity. Samples were analyzed for their peptide profiles via mass spectrometry and database searching. Peptidomics-based protease prediction and bioactivity prediction were each performed with several different approaches. The findings demonstrate that human milk contains more than 1,100 unique peptides derived from milk protein hydrolysis within the mammary gland. These peptides derived from 42 milk proteins and included 306 potential bioactive peptides. Based on the peptidomics data, plasmin was predicted to be the milk protease most active in the hydrolysis of human milk proteins within the mammary gland. Milk proteases actively cleave milk proteins within the mammary gland, initiating the release of functional peptides. Thus, the directly breastfed infant receives partially pre-digested proteins and numerous bioactive peptides.
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Affiliation(s)
- Søren D Nielsen
- Nutrition Program, School of Biological and Population Health Sciences, College of Public Health and Human Sciences, Oregon State University, 118G Milam Hall, Corvallis, OR, 97331, USA
| | - Robert L Beverly
- Nutrition Program, School of Biological and Population Health Sciences, College of Public Health and Human Sciences, Oregon State University, 118G Milam Hall, Corvallis, OR, 97331, USA
| | - David C Dallas
- Nutrition Program, School of Biological and Population Health Sciences, College of Public Health and Human Sciences, Oregon State University, 118G Milam Hall, Corvallis, OR, 97331, USA.
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Komnenov D, Scipione C, Bazzi Z, Garabon J, Koschinsky M, Boffa M. Pro-inflammatory cytokines reduce human TAFI expression via tristetraprolin-mediated mRNA destabilisation and decreased binding of HuR. Thromb Haemost 2017; 114:337-49. [DOI: 10.1160/th14-08-0653] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2014] [Accepted: 03/12/2015] [Indexed: 01/26/2023]
Abstract
SummaryThrombin activatable fibrinolysis inhibitor (TAFI) is the zymogen form of a basic carboxypeptidase (TAFIa) with both anti-fibrinolytic and anti-inflammatory properties. The role of TAFI in inflammatory disease is multifaceted and involves modulation both of specific inflammatory mediators as well as of the behaviour of inflammatory cells. Moreover, as suggested by in vitro studies, inflammatory mediators are capable of regulating the expression of CPB2, the gene encoding TAFI. In this study we addressed the hypothesis that decreased TAFI levels observed in inflammation are due to post-transcriptional mechanisms. Treatment of human HepG2 cells with pro-inflammatory cytokines TNFα, IL-6 in combination with IL-1β, or with bacterial lipopolysaccharide (LPS) decreased TAFI protein levels by approximately two-fold over 24 to 48 hours of treatment. Conversely, treatment of HepG2 cells with the anti-inflammatory cytokine IL-10 increased TAFI protein levels by two-fold at both time points. We found that the mechanistic basis for this modulation of TAFI levels involves binding of tristetraprolin (TTP) to the CPB2 3′-UTR, which mediates CPB2 mRNA destabilisation. In this report we also identified that HuR, another ARE-binding protein but one that stabilises transcripts, is capable of binding the CBP2 3’UTR. We found that pro-inflammatory mediators reduce the occupancy of HuR on the CPB2 3’-UTR and that the mutation of the TTP binding site in this context abolishes this effect, although TTP and HuR appear to contact discrete binding sites. Interestingly, all of the mediators tested appear to increase TAFI protein expression in THP-1 macrophages, likewise through effects on CPB2 mRNA stability.
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22
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Lin JHH, Novakovic D, Rizzo CM, Zagorac B, Garand M, Filipieva A, Koschinsky ML, Boffa MB. The mRNA encoding TAFI is alternatively spliced in different cell types and produces intracellular forms of the protein lacking TAFIa activity. Thromb Haemost 2017; 109:1033-44. [DOI: 10.1160/th12-09-0668] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2012] [Accepted: 02/27/2013] [Indexed: 11/05/2022]
Abstract
SummaryTAFI (thrombin-activatable fibrinolysis inhibitor) is a pro-carboxypeptidase, encoded by the CPB2 gene in humans that links the coagulation cascade to fibrinolysis and inflammation. The liver is the main source for plasma TAFI, and TAFI expression has been documented in platelets and monocyte-derived macrophages. A recent study reported an alternatively spliced CPB2 mRNA variant lacking exon 7 (Δ7) in HepG2 cells and liver. Another study identified a CPB2 mRNA variant lacking exon 7 and a 52 bp deletion in exon 11 (Δ7+11) in human hippocampus. We have examined alternative splicing of CPB2 mRNA in various cell types by RT-PCR and have assessed the functional properties of TAFI variants encoded by these transcripts by recombinant expression in mammalian cells. We identified the Δ7 exon skipping event in liver, Dami megakaryoblasts, THP-1-derived macrophages, peripheral blood mononuclear cells, platelets, testis, cerebellum, and SH-SY5Y neuroblastoma cells. The Δ11 alternative splicing event was notably absent in liver cells. We also detected a novel exon Δ7+8 skipping event in liver and megakaryocytes. Of note, we detected non-alternatively spliced CPB2 transcripts in brain tissues, suggesting the expression of full-length TAFI in brain. Experiments using cultured mammalian cells transfected with wild-type CPB2-, Δ7-, Δ7+11 -, and_Δ11 -cDNA revealed that alternatively spliced TAFI is stored inside the cells, cannot be activated by thrombin-thrombomodulin, and does not have TAFIa activity. The alternative splicing events clearly do not give rise to a secreted protein with basic carboxy-peptidase activity, but the intracellular forms may possess novel functions related to intracellular proteolysis.
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Leenaerts D, Aernouts J, Van Der Veken P, Sim Y, Lambeir AM, Hendriks D. Plasma carboxypeptidase U (CPU, CPB2, TAFIa) generation during in vitro clot lysis and its interplay between coagulation and fibrinolysis. Thromb Haemost 2017; 117:1498-1508. [PMID: 28692110 DOI: 10.1160/th17-02-0097] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2017] [Accepted: 05/02/2017] [Indexed: 11/05/2022]
Abstract
Carboxypeptidase U (CPU, CPB2, TAFIa) is a basic carboxypeptidase that is able to attenuate fibrinolysis. The inactive precursor procarboxypeptidase U is converted to its active form by thrombin, the thrombin-thrombomodulin complex or plasmin. The aim of this study was to investigate and characterise the time course of CPU generation in healthy individuals. In plasma of 29 healthy volunteers, CPU generation was monitored during in vitro clot lysis. CPU activity was measured by means of an enzymatic assay that uses the specific substrate Bz-o-cyano-Phe-Arg. An algorithm was written to plot the CPU generation curve and calculate the parameters that define it. In all individuals, CPU generation was biphasic. Marked inter-individual differences were present and a reference range was determined. The endogenous CPU generation potential is the composite effect of multiple factors. With respect to the first CPU activity peak characteristics, we found correlations with baseline proCPU concentration, proCPU Thr325Ile polymorphism, time to clot initiation and the clot lysis time. The second CPU peak related with baseline proCPU levels and with the maximum turbidity of the clot lysis profile. In conclusion, our method offers a technique to determine the endogenous CPU generation potential of an individual. The parameters obtained by the method quantitatively describe the different mechanisms that influence CPU generation during the complex interplay between coagulation and fibrinolysis, which are in line with the threshold hypothesis.
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Affiliation(s)
| | | | | | | | | | - Dirk Hendriks
- Prof. D. Hendriks, Laboratory of Medical Biochemistry, University of Antwerp, Universiteitsplein 1, B-2610 Wilrijk, Belgium, Tel.: +32 3 265 27 27, E-mail:
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24
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Wu C, Stafford AR, Fredenburgh JC, Weitz JI, Gils A, Declerck PJ, Kim PY. Lys 42/43/44 and Arg 12 of thrombin-activable fibrinolysis inhibitor comprise a thrombomodulin exosite essential for its antifibrinolytic potential. Thromb Haemost 2017. [PMID: 28640323 DOI: 10.1160/th17-01-0054] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The thrombin-thrombomodulin (TM) complex activates thrombin-activable fibrinolysis inhibitor (TAFI) more efficiently than thrombin alone. The exosite on TAFI required for its TM-dependent activation by thrombin has not been identified. Based on previous work by us and others, we generated TAFI variants with one or more of residues Lys 42, Lys 43, Lys 44 and Arg 12 within the activation peptide mutated to alanine. Mutation of one, two, or three Lys residues or the Arg residue alone decreased the catalytic efficiency of TAFI activation by thrombin-TM by 2.4-, 3.2-, 4.7-, and 15.0-fold, respectively, and increased the TAFI concentrations required for half-maximal prolongation of clot lysis times (K1/2) by 3-, 4,- 15-, and 24-fold, respectively. Mutation of all four residues decreased the catalytic efficiency of TAFI activation by 45.0-fold, increased the K1/2 by 130-fold, and abolished antifibrinolytic activity in a clot lysis assay at physiologic levels of TAFI. Similar trends in the antifibrinolytic activity of the TAFI variants were observed when plasma clots were formed using HUVECs as the source of TM. When thrombin was used as the activator, mutation of all four residues reduced the rate of activation by 1.1-fold compared with wild-type TAFI, suggesting that these mutations only impacted activation kinetics in the presence of TM. Surface plasmon resonance data suggest that mutation of the four residues abrogates TM binding with or without thrombin. Therefore, Lys 42, Lys 43, Lys 44 and Arg 12 are critical for the interaction of TAFI with the thrombin-TM complex, which modulates its antifibrinolytic potential.
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Affiliation(s)
| | | | | | | | | | | | - Paul Y Kim
- Paul Y. Kim, Thrombosis and Atherosclerosis Research Institute, 237 Barton St. East, Hamilton, Ontario, L8L 2X2, Canada, Tel.: +1 905 521 2100, Fax: +1 905 575 2646, E-mail:
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25
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Brzoska T, Suzuki Y, Sano H, Suzuki S, Tomczyk M, Tanaka H, Urano T. Imaging analyses of coagulation-dependent initiation of fibrinolysis on activated platelets and its modification by thrombin-activatable fibrinolysis inhibitor. Thromb Haemost 2017; 117:682-690. [PMID: 28150854 DOI: 10.1160/th16-09-0722] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2016] [Accepted: 12/26/2016] [Indexed: 11/05/2022]
Abstract
Using intravital confocal microscopy, we observed previously that the process of platelet phosphatidylserine (PS) exposure, fibrin formation and lysine binding site-dependent plasminogen (plg) accumulation took place only in the centre of thrombi, not at their periphery. These findings prompted us to analyse the spatiotemporal regulatory mechanisms underlying coagulation and fibrinolysis. We analysed the fibrin network formation and the subsequent lysis in an in vitro experiment using diluted platelet-rich plasma supplemented with fluorescently labelled coagulation and fibrinolytic factors, using confocal laser scanning microscopy. The structure of the fibrin network formed by supplemented tissue factor was uneven and denser at the sites of coagulation initiation regions (CIRs) on PS-exposed platelets. When tissue-type plasminogen activator (tPA; 7.5 nM) was supplemented, labelled plg (50 nM) as well as tPA accumulated at CIRs, from where fibrinolysis started and gradually expanded to the peripheries. The lysis time at CIRs and their peripheries (50 µm from the CIR) were 27.9 ± 6.6 and 44.4 ± 9.7 minutes (mean ± SD, n=50 from five independent experiments) after the addition of tissue factor, respectively. Recombinant human soluble thrombomodulin (TMα; 2.0 nM) attenuated the CIR-dependent plg accumulation and strongly delayed fibrinolysis at CIRs. A carboxypeptidase inhibitor dose-dependently enhanced the CIR-dependent fibrinolysis initiation, and at 20 µM it completely abrogated the TMα-induced delay of fibrinolysis. Our findings are the first to directly present crosstalk between coagulation and fibrinolysis, which takes place on activated platelets' surface and is further controlled by thrombin-activatable fibrinolysis inhibitor (TAFI).
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Affiliation(s)
| | | | | | | | | | | | - Tetsumei Urano
- Dr. Tetsumei Urano, Department of Physiology, Hamamatsu University School of Medicine, 1-20-1 Handa-yama Higashi-ku Hamamatsu, Shizuoka 431-3192, Japan, Tel.: +81 53 435 2248, Fax: +81 53 435 7020, E-mail:
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26
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Abstract
Platelets are small anuclear cells that play a central role in haemostasis. Platelets become activated in response to various stimuli triggering release of their granular contents into the surrounding milieu. One of these types of granules, termed dense granules, have been found to contain polyphosphate (polyP) in addition to other inorganic biomolecules, such as serotonin, ADP, ATP, PPi. Individuals deficient in dense granules exhibit bleeding tendencies, emphasizing their importance in haemostasis. Platelet polyP is of a relatively defined size, approximately 60-100 phosphate monomers in length. These linear polymers act at various points in the coagulation and fibrinolytic systems thereby modulating the haemostatic response. Due to its highly anionic nature, polyP lends itself to being a natural activator of the contact system. The contact system functions in multiple pathways including coagulation, fibrinolysis, inflammation and complement. Activation of the contact system accelerates thrombin generation, the terminal enzyme in the coagulation cascade. PolyP also modulates factors further downstream in the coagulation cascade to augment thrombin generation. The net effect is increased fibrin formation and platelet activation resulting in faster clot formation. PolyP is incorporated into the forming clot thereby modifying the structure of the resulting fibrin network and its susceptibility to degradation by certain plasminogen activators. In conclusion, release of platelet polyP at the site of injury may facilitate clot formation and augment clot stability thereby promoting wound healing.
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Plug T, Meijers JC. Stimulation of thrombin- and plasmin-mediated activation of thrombin-activatable fibrinolysis inhibitor by anionic molecules. Thromb Res 2016; 146:7-14. [DOI: 10.1016/j.thromres.2016.08.015] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2016] [Revised: 06/29/2016] [Accepted: 08/14/2016] [Indexed: 11/25/2022]
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Timofeev АV. [Basic carboxypeptidases of blood: significance for coagulology]. BIOMEDIT︠S︡INSKAI︠A︡ KHIMII︠A︡ 2016; 62:141-9. [PMID: 27143370 DOI: 10.18097/pbmc20166202141] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
This review considers the basic metallocarboxypeptidases of human blood and their role in coagulologic disorders. In includes information on the history of the discovery and biological characteristics of potential enzymes-regulators of the fibrinolytic process: carboxypeptidase U and carboxypeptidase N. Certain attention is paid to the biochemical mechanisms and the main modern concepts of the antifibrinolytic effects of these enzymes.
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Affiliation(s)
- А V Timofeev
- Russian Research Institute of Haematology and Transfusiology, Saint Petersburg, Russia
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Seheult JN, Chibisov I. A Case of Unexplained Cerebral Sinus Thrombosis in a 22-Year-Old Obese Caucasian Woman. Lab Med 2016; 47:233-40. [PMID: 27287941 DOI: 10.1093/labmed/lmw023] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Herein, we present the case of a 22-year old obese Caucasian woman female with no acquired thrombophilic risk factors who was diagnosed with extensive cerebral sinus thrombosis. A detailed thrombophilia workup demonstrated persistently elevated plasminogen activator inhibitor 1 (PAI-1) activity levels, with an elevated PAI-1 antigen concentration and homozygosity for the PAI-1 4G allele (4G/4G genotype). The patient was treated with indefinite warfarin anticoagulation medication due to the unprovoked nature of her thrombotic event. Disturbances in the fibrinolytic system, in particular PAI-1, have been related to an increased risk of arterial and venous thrombosis. In this article, we discuss the pathophysiology of hypofibrinolysis associated with elevated PAI-1 levels and the PAI-1 4G/5G polymorphism.
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Affiliation(s)
- Jansen N Seheult
- Department of Pathology, University of Pittsburgh School of Medicine, Pittsburgh, PA,
| | - Irina Chibisov
- Department of Pathology, University of Pittsburgh School of Medicine, Pittsburgh, PA, Institute for Transfusion Medicine, University of Pittsburgh Medical Center Health System, Pittsburgh, PA
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Marar TT, Boffa MB. Identification of a thrombomodulin interaction site on thrombin-activatable fibrinolysis inhibitor that mediates accelerated activation by thrombin. J Thromb Haemost 2016; 14:772-83. [PMID: 26816270 DOI: 10.1111/jth.13275] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2015] [Indexed: 11/26/2022]
Abstract
BACKGROUND Thrombin-activatable fibrinolysis inhibitor (TAFI) is a human plasma zymogen that provides a molecular connection between coagulation and fibrinolysis. TAFI is activated through proteolytic cleavage by thrombin, thrombin in complex with the endothelial cell cofactor thrombomodulin (TM) or plasmin. Evidence from several studies suggests that TM and TAFI make direct contact at sites remote from the activating cleavage site to facilitate acceleration of thrombin-mediated TAFI activation. The elements of TAFI structure that allow accelerated activation of thrombin by TM are incompletely defined. OBJECTIVES To identify TM interaction regions on TAFI that mediate acceleration of activation by thrombin and therefore indicate TM binding sites on TAFI. METHODS We mutated selected surface-exposed charged residues on TAFI to alanine in order to identify sites that mediate acceleration of activation by TM. The kinetics of activation of the mutants by thrombin in the presence or absence of TM, as well as their thermal stabilities and antifibrinolytic potentials, were determined. RESULTS TAFI variants R15A, E28A, K59A, D75A/E77A/D78A, E99A and E106A all exhibited moderately reduced catalytic efficiencies of activation by thrombin-TM. TAFI variants R377A and, particularly, R12A and R12A/R15A exhibited severely reduced activation by thrombin-TM that was not explained by differences in activation by thrombin alone. CONCLUSIONS We have identified R12 as a critical residue for the activation of TAFI by thrombin-TM, extending a previous report that identified a role for this residue. R12 is likely to directly bind to TM while another key residue, R377, may affect the thrombin-TAFI interaction specifically in the presence of TM.
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Affiliation(s)
- T T Marar
- Department of Chemistry and Biochemistry, University of Windsor, Windsor, ON, Canada
| | - M B Boffa
- Department of Chemistry and Biochemistry, University of Windsor, Windsor, ON, Canada
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Plug T, Meijers JCM. Structure-function relationships in thrombin-activatable fibrinolysis inhibitor. J Thromb Haemost 2016; 14:633-44. [PMID: 26786060 DOI: 10.1111/jth.13261] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2015] [Indexed: 11/30/2022]
Abstract
Thrombin-activatable fibrinolysis inhibitor (TAFI) is an important regulator in the balance of coagulation and fibrinolysis. TAFI is a metallocarboxypeptidase that circulates in plasma as zymogen. Activated TAFI (TAFIa) cleaves C-terminal lysine or arginine residues from peptide substrates. The removal of C-terminal lysine residues from partially degraded fibrin leads to reduced plasmin formation and thus attenuation of fibrinolysis. TAFI also plays a role in inflammatory processes via the removal of C-terminal arginine or lysine residues from bradykinin, thrombin-cleaved osteopontin, C3a, C5a and chemerin. TAFI has been studied extensively over the past three decades and recent publications provide a wealth of information, including crystal structures, mutants and structural data obtained with antibodies and peptides. In this review, we combined and compared available data on structure/function relationships of TAFI.
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Affiliation(s)
- T Plug
- Department of Experimental Vascular Medicine, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands
| | - J C M Meijers
- Department of Experimental Vascular Medicine, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands
- Department of Plasma Proteins, Sanquin Research, Amsterdam, the Netherlands
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Abstract
D-dimer is the smallest fibrinolysis-specific degradation product found in the circulation. The origins, assays, and clinical use of D-dimer will be addressed. Hemostasis (platelet and vascular function, coagulation, fibrinolysis, hemostasis) is briefly reviewed. D-dimer assays are reviewed. The D-dimer is very sensitive to intravascular thrombus and may be markedly elevated in disseminated intravascular coagulation, acute aortic dissection, and pulmonary embolus. Because of its exquisite sensitivity, negative tests are useful in the exclusion venous thromboembolism. Elevations occur in normal pregnancy, rising two- to fourfold by delivery. D-dimer also rises with age, limiting its use in those >80 years old. There is a variable rise in D-dimer in active malignancy and indicates increased thrombosis risk in active disease. Elevated D-dimer following anticoagulation for a thrombotic event indicates increased risk of recurrent thrombosis. These and other issues are addressed.
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Santos IR, Fernandes AP, Carvalho MG, Sousa MO, Ferreira CN, Gomes KB. Thrombin-activatable fibrinolysis inhibitor (TAFI) levels and its polymorphism rs3742264 are associated with dyslipidemia in a cohort of Brazilian subjects. Clin Chim Acta 2014; 433:76-83. [PMID: 24631134 DOI: 10.1016/j.cca.2014.02.030] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2013] [Revised: 02/20/2014] [Accepted: 02/28/2014] [Indexed: 11/19/2022]
Abstract
BACKGROUND Dyslipidemia, a metabolic alteration that affects lipoprotein levels, is considered a major risk factor for atherosclerosis and its complications. Dyslipidemia also affects the hemostatic system, especially impairing fibrinolysis, and increased levels of thrombin-activatable fibrinolysis inhibitor (TAFI) have been associated with cardiovascular events. OBJECTIVES AND METHODS This study evaluated the association of acquired risk factors (hypertension, body mass index - BMI, smoking, sedentary lifestyle, use or not of oral contraceptives and hormone replacement therapy, and post-menopause status), the polymorphisms Thr325Ile (rs1926447), Ala147Thr (rs3742264) and +1542C/G (rs940) in the TAFI gene, and TAFI plasma levels in 109 dyslipidemic and 105 normolipemic individuals. Biochemical analyses and TAFI levels were evaluated by colorimetric/turbidimetric assays and ELISA, respectively. Genotypic and allelic frequencies were determined by polymerase chain reaction (PCR). RESULTS Hypertension, increased BMI, and menopause were more common in dyslipidemic individuals, who had higher TAFI levels. The alleles 325Ile, Ala147, and C showed association with lower TAFI levels. The rs3742264 polymorphism was associated with dyslipidemia in males. CONCLUSIONS The results suggest that TAFI levels are independently associated to dyslipidemia and that the polymorphism rs3742264 may be related to cardiovascular risk in male subjects.
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Affiliation(s)
- Izabela R Santos
- Departamento de Biologia Geral, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Ana P Fernandes
- Departamento de Análises Clínicas e Toxicológicas, Faculdade de Farmácia, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Maria G Carvalho
- Departamento de Análises Clínicas e Toxicológicas, Faculdade de Farmácia, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Marinez O Sousa
- Departamento de Análises Clínicas e Toxicológicas, Faculdade de Farmácia, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Cláudia N Ferreira
- Colégio Técnico, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Karina B Gomes
- Departamento de Biologia Geral, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil; Departamento de Análises Clínicas e Toxicológicas, Faculdade de Farmácia, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil.
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Semeraro F, Ammollo CT, Gils A, Declerck PJ, Colucci M. Monoclonal antibodies targeting the antifibrinolytic activity of activated thrombin-activatable fibrinolysis inhibitor but not the anti-inflammatory activity on osteopontin and C5a. J Thromb Haemost 2013; 11:2137-47. [PMID: 24134522 DOI: 10.1111/jth.12431] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2013] [Indexed: 11/29/2022]
Abstract
BACKGROUND Recently, anti-thrombin-activatable fibrinolysis inhibitor (TAFI) mAbs selectively inhibiting plasmin-mediated TAFI activation were shown to stimulate fibrinolysis in vitro and in vivo, suggesting, in contrast to other findings, that plasmin-mediated TAFI activation plays an important role in fibrinolysis regulation. OBJECTIVE To further characterize the effects of two plasmin-specific anti-TAFI mAbs (MA-TCK11A9 and MA-TCK26D6) on TAFI-dependent inhibition of fibrinolysis. METHODS AND RESULTS Both mAbs inhibited plasmin-mediated but not thrombin/thrombomodulin-mediated TAFI activation, whereas neither inhibited the cleavage of hippuryl-arginine by activated TAFI (TAFIa). They stimulated tissue-type plasminogen activator-induced fibrinolysis in different clot lysis models through a TAFI-dependent mechanism, especially in the presence of thrombomodulin (TM), a condition in which TAFI is largely activated by the thrombin-TM complex. In a fibrinolysis-based TAFIa activity assay, both mAbs inhibited TAFIa, whereas other mAbs targeting thrombin-TM-mediated TAFI activation did not. The inhibition of TAFIa activity, however, was substrate-specific, because neither mAb inhibited the cleavage of thrombin-activated osteopontin and C5a by TAFIa, thus sparing the anti-inflammatory activity of TAFIa. CONCLUSIONS Our anti-TAFI mAbs, by selectively inhibiting TAFIa activity on fibrin, may represent the prototype of a new class of TAFI inhibitors with improved pharmacologic activity.
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Affiliation(s)
- F Semeraro
- Department of Biomedical Sciences and Human Oncology, Section of General and Experimental Pathology, Aldo Moro University, Bari, Italy
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35
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A methodological and functional proteomic approach of human follicular fluid en route for oocyte quality evaluation. J Proteomics 2013; 90:61-76. [DOI: 10.1016/j.jprot.2013.02.025] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2012] [Revised: 02/15/2013] [Accepted: 02/27/2013] [Indexed: 11/23/2022]
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Foley JH, Kim PY, Mutch NJ, Gils A. Insights into thrombin activatable fibrinolysis inhibitor function and regulation. J Thromb Haemost 2013; 11 Suppl 1:306-15. [PMID: 23809134 DOI: 10.1111/jth.12216] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Fibrinolysis is initiated when the zymogen plasminogen is converted to plasmin via the action of plasminogen activators. Proteolytic cleavage of fibrin by plasmin generates C-terminal lysine residues capable of binding both plasminogen and the plasminogen activator, thereby stimulating plasminogen activator-mediated plasminogen activation and propagating fibrinolysis. This positive feedback mechanism is regulated by activated thrombin activatable fibrinolysis inhibitor (TAFIa), which cleaves C-terminal lysine residues from the fibrin surface, thereby decreasing its cofactor activity. TAFI can be activated by thrombin alone, but the rate of activation is accelerated when in complex with thrombomodulin. Plasmin is also known to activate TAFI. TAFIa has no known physiologic inhibitors and consequently, its primary regulatory mechanism involves its intrinsic thermal instability. The rate of TAFI activation and stability of the active form, TAFIa, function in maintaining its concentration above the threshold value required to down-regulate fibrinolysis. Although all methods to quantify TAFI or TAFIa have their limitations, epidemiologic studies have indicated that elevated TAFI levels are correlated with an increased risk of venous thrombosis. Major efforts have been made to develop TAFI inhibitors that can either directly interfere with TAFIa activity or impair its activation. However, the anti-inflammatory properties of TAFIa might complicate the development and application of a TAFIa inhibitor that aims to increase the efficiency of thrombolytic therapy.
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Affiliation(s)
- J H Foley
- Centre for Blood Research, University of British Columbia, Vancouver, BC, Canada
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37
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Regulation of the gene encoding human thrombin-activatable fibrinolysis inhibitor by estrogen and progesterone. Blood Coagul Fibrinolysis 2013; 24:393-404. [DOI: 10.1097/mbc.0b013e32835d543a] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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38
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Vercauteren E, Mutch NJ, Declerck PJ, Gils A. Plasmin and the thrombin-thrombomodulin complex both contribute to thrombin-activatable fibrinolysis inhibitor activation in whole blood model thrombi. J Thromb Haemost 2013; 11:190-2. [PMID: 23140098 DOI: 10.1111/jth.12062] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- E Vercauteren
- Laboratory for Pharmaceutical Biology, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, Leuven, Belgium
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39
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Novakovic D, Kuo ACY, Lin JH, Koschinsky ML, Boffa MB. Identification of tristetraprolin as a factor that modulates the stability of the TAFI transcript through binding to the 3'-untranslated region. J Thromb Haemost 2012; 10:887-94. [PMID: 22452791 DOI: 10.1111/j.1538-7836.2012.04689.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
BACKGROUND Thrombin-activatable fibrinolysis inhibitor (TAFI) is a basic carboxypeptidase zymogen encoded by the human gene CPB2. TAFI constitutes a molecular link between coagulation and fibrinolysis, and between coagulation and inflammation. The 3'-untranslated region (UTR) of the human CPB2 mRNA plays a key role in regulating CPB2 mRNA abundance, but the exact mechanisms that mediate this regulation are largely unexplored. OBJECTIVES To pinpoint cis-acting elements in the CPB2 3'-UTR that act as stability determinants and to identify protein factors binding to these sites. METHODS We constructed a series of plasmids encoding mRNAs containing rabbit β-globin sequences (as a reporter) fused to sequences of the CPB2 3'-UTR (encompassing 5' and internal deletions). These plasmids were transfected into HepG2 (human hepatoma) cells and the stability of the fusion transcripts measured. We performed a series of gel mobility shift analyses using RNA probes encompassing putative (in)stability elements. RESULTS We identified one element conferring stability and three elements conferring instability. Supershift assays identified the protein bound to the site between the second and third polyadenylation sites as tristetraprolin (TTP). Mutation of the TTP site abolished TTP binding in gel mobility shift assays and also stabilized β-globin/CPB2 fusion transcripts. TTP knockdown stabilized the fusion transcript containing the TTP site, but not a fusion transcript in which this site was mutated. CONCLUSIONS Our findings are indicative of a role for TTP in constitutive, and perhaps regulated, control of CPB2 mRNA stability and hence abundance.
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Affiliation(s)
- D Novakovic
- Department of Chemistry and Biochemistry, University of Windsor, Windsor, ON, Canada
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40
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Regulation of the mouse gene encoding TAFI by TNFα: Role of NFκB binding site. Cytokine 2012; 57:389-97. [DOI: 10.1016/j.cyto.2011.11.023] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2011] [Revised: 11/29/2011] [Accepted: 11/30/2011] [Indexed: 11/18/2022]
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41
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Declerck PJ. Thrombin activatable fibrinolysis inhibitor. Hamostaseologie 2011; 31:165-6, 168-73. [PMID: 21629966 DOI: 10.5482/ha-1155] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2011] [Accepted: 05/26/2011] [Indexed: 12/14/2022] Open
Abstract
Thrombin activatable fibrinolysis inhibitor (TAFI) was discovered two decades ago as a consequence of the identification of an unstable carboxypeptidase (CPU), which was formed upon thrombin activation of the respective pro-enzyme (proCPU). The antifibrinolytic function of the activated form (TAFIa, CPU) is directly linked to its capacity to remove C-terminal lysines from the surface of the fibrin clot. No endogenous inhibitors have been identified, but TAFIa activity is regulated by its intrinsic temperature-dependent instability with a half-life of 8 to 15 min at 37 °C. A variety of studies have demonstrated a role for TAFI/TAFIa in venous and arterial diseases. In addition, a role in inflammation and cell migration has been shown. Since an elevated level of TAFIa it is a potential risk factor for thrombotic disorders, many inhibitors, both at the level of activation or at the level of activity, have been developed and were proven to exhibit a profibrinolytic effect in animal models. Pharmacologically active inhibitors of the TAFI/TAFIa system may open new ways for the prevention of thrombotic diseases or for the establishment of adjunctive treatments during thrombolytic therapy.
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Affiliation(s)
- P J Declerck
- Katholieke Universiteit Leuven, Campus Gasthuisberg, Herestraat 49, Leuven, Belgium.
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42
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Lin JHH, Garand M, Zagorac B, Schadinger SL, Scipione C, Koschinsky ML, Boffa MB. Identification of human thrombin-activatable fibrinolysis inhibitor in vascular and inflammatory cells. Thromb Haemost 2011; 105:999-1009. [PMID: 21505719 DOI: 10.1160/th10-06-0413] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2010] [Accepted: 03/10/2011] [Indexed: 11/05/2022]
Abstract
TAFI (thrombin-activatable fibrinolysis inhibitor) is a carboxypeptidase zymogen originally identified in plasma. The TAFI pathway helps to regulate the balance between the coagulation and fibrinolytic cascades. Activated TAFI (TAFIa) can also inactivate certain pro-inflammatory mediators, suggesting that the TAFI pathway may also regulate communication between coagulation and inflammation. Expression in the liver is considered to be the source of plasma TAFI. TAFI has also been identified in platelets and CPB2 (the gene encoding TAFI) mRNA has been detected in megakaryocytic cell lines as well as in endothelial cells. We have undertaken a quantitative analysis of CPB2 mRNA and TAFI protein in extrahepatic cell types relevant to vascular disease. Using RT-PCR and quantitative RT-PCR, we detected CPB2 mRNA in the human megakaryoblastic cell lines MEG-01 and Dami, the human monocytoid cell line THP-1 as well as THP-1 cells differentiated into a macrophage-like phenotype, and in primary human umbilical vein and coronary artery endothelial cells. CPB2 mRNA abundance in MEG-01, Dami, and THP-1 cells was modulated by the state of differentiation of these cells. Using a recently developed TAFIa assay, we detected TAFI protein in the lysates of the human hepatocellular carcinoma cell line HepG2 as well as in MEG-01 and Dami cells and in the conditioned medium of HepG2 cells, differentiated Dami cells, and THP-1 macrophages. We have obtained clear evidence for extrahepatic expression of TAFI, which has clear implications for the physiological and pathophysiological functions of the TAFI pathway.
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Affiliation(s)
- J H H Lin
- Department of Chemistry & Biochemistry, University of Windsor, Windsor, Ontario, Canada
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43
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Foley JH, Cook PF, Nesheim ME. Kinetics of activated thrombin-activatable fibrinolysis inhibitor (TAFIa)-catalyzed cleavage of C-terminal lysine residues of fibrin degradation products and removal of plasminogen-binding sites. J Biol Chem 2011; 286:19280-6. [PMID: 21467042 DOI: 10.1074/jbc.m110.215061] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Partial digestion of fibrin by plasmin exposes C-terminal lysine residues, which comprise new binding sites for both plasminogen and tissue-type plasminogen activator (tPA). This binding increases the catalytic efficiency of plasminogen activation by 3000-fold compared with tPA alone. The activated thrombin-activatable fibrinolysis inhibitor (TAFIa) attenuates fibrinolysis by removing these residues, which causes a 97% reduction in tPA catalytic efficiency. The aim of this study was to determine the kinetics of TAFIa-catalyzed lysine cleavage from fibrin degradation products and the kinetics of loss of plasminogen-binding sites. We show that the k(cat) and K(m) of Glu(1)-plasminogen (Glu-Pg)-binding site removal are 2.34 s(-1) and 142.6 nm, respectively, implying a catalytic efficiency of 16.21 μm(-1) s(-1). The corresponding values of Lys(77)/Lys(78)-plasminogen (Lys-Pg)-binding site removal are 0.89 s(-1) and 96 nm implying a catalytic efficiency of 9.23 μm(-1) s(-1). These catalytic efficiencies of plasminogen-binding site removal by TAFIa are the highest of any TAFIa-catalyzed reaction with a biological substrate reported to date and suggest that plasmin-modified fibrin is a primary physiological substrate for TAFIa. We also show that the catalytic efficiency of cleavage of all C-terminal lysine residues, whether they are involved in plasminogen binding or not, is 1.10 μm(-1) s(-1). Interestingly, this value increases to 3.85 μm(-1) s(-1) in the presence of Glu-Pg. These changes are due to a decrease in K(m). This suggests that an interaction between TAFIa and plasminogen comprises a component of the reaction mechanism, the plausibility of which was established by showing that TAFIa binds both Glu-Pg and Lys-Pg.
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Affiliation(s)
- Jonathan H Foley
- Department of Biochemistry, Queen's University, Kingston, Ontario, Canada
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Evaluation of the profibrinolytic properties of an anti-TAFI monoclonal antibody in a mouse thromboembolism model. Blood 2011; 117:4615-22. [PMID: 21343611 DOI: 10.1182/blood-2010-08-303677] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The enhancement of fibrinolysis constitutes a promising approach to treat thrombotic diseases. Activated thrombin activatable fibrinolysis inhibitor (TAFIa) attenuates fibrinolysis and is an attractive target to develop profibrinolytic drugs. TAFI can be activated by thrombin, thrombin/thrombomodulin, or plasmin, but the in vivo physiologic TAFI activator(s) are unknown. Here, we generated and characterized MA-TCK26D6, a monoclonal antibody raised against human TAFI, and examined its profibrinolytic properties in vitro and in vivo. In vitro, MA-TCK26D6 showed a strong profibrinolytic effect caused by inhibition of the plasmin-mediated TAFI activation. In vivo, MA-TCK26D6 significantly decreased fibrin deposition in the lungs of thromboembolism-induced mice. Moreover, in the presence of MA-TCK26D6, plasmin-α(2)-antiplasmin complexes in plasma of thromboembolism-induced mice were significantly increased compared with a control antibody, indicative of an acceleration of fibrinolysis through MA-TCK26D6. In this study, we show that plasmin is an important TAFI activator that hampers in vitro clot lysis. Furthermore, this is the first report on an anti-TAFI monoclonal antibody that demonstrates a strong profibrinolytic effect in a mouse thromboembolism model.
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Dusse LM, Rios DR, Pinheiro MB, Cooper AJ, Lwaleed BA. Pre-eclampsia: Relationship between coagulation, fibrinolysis and inflammation. Clin Chim Acta 2011; 412:17-21. [DOI: 10.1016/j.cca.2010.09.030] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2010] [Accepted: 09/25/2010] [Indexed: 01/18/2023]
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46
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Valnickova Z, Sanglas L, Arolas JL, Petersen SV, Schar C, Otzen D, Aviles FX, Gomis-Rüth FX, Enghild JJ. Flexibility of the thrombin-activatable fibrinolysis inhibitor pro-domain enables productive binding of protein substrates. J Biol Chem 2010; 285:38243-50. [PMID: 20880845 DOI: 10.1074/jbc.m110.150342] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We have previously reported that thrombin-activatable fibrinolysis inhibitor (TAFI) exhibits intrinsic proteolytic activity toward large peptides. The structural basis for this observation was clarified by the crystal structures of human and bovine TAFI. These structures evinced a significant rotation of the pro-domain away from the catalytic moiety when compared with other pro-carboxypeptidases, thus enabling access of large peptide substrates to the active site cleft. Here, we further investigated the flexible nature of the pro-domain and demonstrated that TAFI forms productive complexes with protein carboxypeptidase inhibitors from potato, leech, and tick (PCI, LCI, and TCI, respectively). We determined the crystal structure of the bovine TAFI-TCI complex, revealing that the pro-domain was completely displaced from the position observed in the TAFI structure. It protruded into the bulk solvent and was disordered, whereas TCI occupied the position previously held by the pro-domain. The authentic nature of the presently studied TAFI-inhibitor complexes was supported by the trimming of the C-terminal residues from the three inhibitors upon complex formation. This finding suggests that the inhibitors interact with the active site of TAFI in a substrate-like manner. Taken together, these data show for the first time that TAFI is able to form a bona fide complex with protein carboxypeptidase inhibitors. This underlines the unusually flexible nature of the pro-domain and implies a possible mechanism for regulation of TAFI intrinsic proteolytic activity in vivo.
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Affiliation(s)
- Zuzana Valnickova
- Center for Insoluble Protein Structure (inSPIN), Department of Molecular Biology, Science Park, Aarhus University, Gustav Wieds Vej 10C, DK-8000 Aarhus C, Denmark
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Sanglas L, Arolas JL, Valnickova Z, Aviles FX, Enghild JJ, Gomis-Rüth FX. Insights into the molecular inactivation mechanism of human activated thrombin-activatable fibrinolysis inhibitor. J Thromb Haemost 2010; 8:1056-65. [PMID: 20088943 DOI: 10.1111/j.1538-7836.2010.03740.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
SUMMARY BACKGROUND Thrombin-activatable fibrinolysis inhibitor (TAFI) is a validated target for thrombotic diseases. TAFI is converted in vivo to activated TAFI (TAFIa) by removal of its pro-domain. Whereas TAFI is stable and persists in the circulation, possibly in complex with plasminogen, TAFIa is unstable and poorly soluble, with a half-life of minutes. OBJECTIVES In order to study the molecular determinants of this instability, we studied the influence of protein inhibitors on human TAFIa. RESULTS We found that protein inhibitors significantly reduced the instability and insolubility of TAFIa. In addition, we solved the 2.5-A resolution crystal structure of human TAFIa in complex with a potent protein inhibitor, tick-derived carboxypeptidase inhibitor, which gives rise to a stable and soluble TAFIa species. The structure revealed a significant reduction in the flexibility of dynamic segments when compared with the structures of bovine and human TAFI. We also identified two latent hotspots, loop Lbeta2beta3 and segment alpha5-Lalpha5beta7-beta7, where conformational destabilization may begin. These hotspots are also present in TAFI, but the pro-domain may provide sufficient stabilization and solubility to guarantee protein persistence in vivo. When the pro-domain is removed, the free TAFIa moiety becomes unstable, its activity is suppressed, and the molecule becomes insoluble. CONCLUSIONS The present study corroborates the function of protein inhibitors in stabilizing human TAFIa and it provides a rigid and high-resolution mold for the design of small molecule inhibitors of this enzyme, thus paving the way for novel therapy for thrombotic disorders.
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Affiliation(s)
- L Sanglas
- Departament de Bioquímica i Biologia Molecular, Facultat de Ciències, Institut de Biotecnologia i de Biomedicina, Universitat Autònoma de Barcelona, Bellaterra, Spain
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Valnickova Z, Thaysen-Andersen M, Højrup P, Christensen T, Sanggaard KW, Kristensen T, Enghild JJ. Biochemical characterization of bovine plasma thrombin-activatable fibrinolysis inhibitor (TAFI). BMC BIOCHEMISTRY 2009; 10:13. [PMID: 19416536 PMCID: PMC2684115 DOI: 10.1186/1471-2091-10-13] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/05/2008] [Accepted: 05/05/2009] [Indexed: 11/18/2022]
Abstract
Background TAFI is a plasma protein assumed to be an important link between coagulation and fibrinolysis. The three-dimensional crystal structures of authentic mature bovine TAFI (TAFIa) in complex with tick carboxypeptidase inhibitor, authentic full lenght bovine plasma thrombin-activatable fibrinolysis inhibitor (TAFI), and recombinant human TAFI have recently been solved. In light of these recent advances, we have characterized authentic bovine TAFI biochemically and compared it to human TAFI. Results The four N-linked glycosylation sequons within the activation peptide were all occupied in bovine TAFI, similar to human TAFI, while the sequon located within the enzyme moiety of the bovine protein was non-glycosylated. The enzymatic stability and the kinetic constants of TAFIa differed somewhat between the two proteins, as did the isoelectric point of TAFI, but not TAFIa. Equivalent to human TAFI, bovine TAFI was a substrate for transglutaminases and could be proteolytically cleaved by trypsin or thrombin/solulin complex, although small differences in the fragmentation patterns were observed. Furthermore, bovine TAFI exhibited intrinsic activity and TAFIa attenuated tPA-mediated fibrinolysis similar to the human protein. Conclusion The findings presented here suggest that the properties of these two orthologous proteins are similar and that conclusions reached using the bovine TAFI may be extrapolated to the human protein.
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Affiliation(s)
- Zuzana Valnickova
- Center for Insoluble Protein Structures and Interdisciplinary Nanoscience Center, Department of Molecular Biology, Science Park, University of Aarhus, Gustav Wieds Vej 10c, 8000 Aarhus C, Denmark.
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Okumura N, Koh T, Hasebe Y, Seki T, Ariga T. A novel function of thrombin-activatable fibrinolysis inhibitor during rat liver regeneration and in growth-promoted hepatocytes in primary culture. J Biol Chem 2009; 284:16553-16561. [PMID: 19386599 DOI: 10.1074/jbc.m109.011452] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Thrombin-activatable fibrinolysis inhibitor (TAFI) exhibits anti-fibrinolytic activity by removing C-terminal lysine residues from fibrin or plasminogen receptor proteins on the cellular surface, and plays an important role in the regulation of fibrinolysis. In this study, we examined the regulation of TAFI in hepatocytes during liver regeneration, and revealed its pivotal role in hepatocyte proliferation. In rat models, partial hepatectomy or carbon tetrachloride (CCl4)-induced acute liver injury suppressed the levels of plasma TAFI activity and hepatic TAFI mRNA, whereas this operation markedly increased both the hepatic plasmin activity and the level of proliferating cell nuclear antigen. In primary cultures of rat hepatocytes, the TAFI mRNA level was decreased under growth-promoting culture conditions. Treatment of the hepatocytes with TAFI siRNA increased the amount of plasmin on the hepatocytes and promoted hepatocyte proliferation. We concluded that TAFI regulates plasmin activity through its enzymatic activity whereby it reduces the plasminogen-binding capacity of the hepatocytes. The TAFI gene expression is down-regulated in hepatocyte proliferation for producing a fibrinolytic microenvironment suitable for cell growth. This is the first report on the role of TAFI in the pericellular fibrinolysis necessary for cellular proliferation.
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Affiliation(s)
- Nobuaki Okumura
- From the Department of Applied Life Sciences, Nihon University Graduate School of Bioresource Sciences, and the Department of Chemistry and Life Science, Nihon University College of Bioresource Sciences, Kanagawa 252-8510, Japan
| | - Tomohiko Koh
- From the Department of Applied Life Sciences, Nihon University Graduate School of Bioresource Sciences, and the Department of Chemistry and Life Science, Nihon University College of Bioresource Sciences, Kanagawa 252-8510, Japan
| | - Yuichi Hasebe
- From the Department of Applied Life Sciences, Nihon University Graduate School of Bioresource Sciences, and the Department of Chemistry and Life Science, Nihon University College of Bioresource Sciences, Kanagawa 252-8510, Japan
| | - Taiichiro Seki
- From the Department of Applied Life Sciences, Nihon University Graduate School of Bioresource Sciences, and the Department of Chemistry and Life Science, Nihon University College of Bioresource Sciences, Kanagawa 252-8510, Japan.
| | - Toyohiko Ariga
- From the Department of Applied Life Sciences, Nihon University Graduate School of Bioresource Sciences, and the Department of Chemistry and Life Science, Nihon University College of Bioresource Sciences, Kanagawa 252-8510, Japan
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Miah MF, Boffa MB. Functional analysis of mutant variants of thrombin-activatable fibrinolysis inhibitor resistant to activation by thrombin or plasmin. J Thromb Haemost 2009; 7:665-72. [PMID: 19335449 DOI: 10.1111/j.1538-7836.2009.03311.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
BACKGROUND Thrombin-activatable fibrinolysis inhibitor (TAFI) defines a pathway that functionally links the coagulation and fibrinolytic cascades. TAFI is activated by proteolytic cleavage, a reaction that can be performed by thrombin and plasmin, but most efficiently by thrombin in complex with the endothelial cofactor thrombomodulin (TM). The respective roles of these activators in regulating the TAFI pathway are largely unknown. OBJECTIVE AND METHODS In the present study, we constructed and expressed mutant variants of TAFI that have key substitutions in the amino acids surrounding the scissile Arg92-Ala93 bond. RESULTS AND CONCLUSIONS We identified variants that showed patterns of resistance to specific activators. For example, the P91S, R92K and S90P variants exhibited specific impairment of activation by thrombin or thrombin-TM, thrombin alone, and thrombin alone or plasmin, respectively. The variants that we tested also showed antifibrinolytic potentials that can be rationalized in terms of which enzymes are capable of activating them. On the other hand, certain predictions from peptide studies of mutations that would be expected to interfere with plasmin cleavage were not satisfied by our data, indicating that protein context, as well as the identity of amino acids at protease cleavage sites, dictates protease specificity.
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Affiliation(s)
- M F Miah
- Department of Biochemistry, Queen's University, Kingston, ON, Canada
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