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Kearney KJ, Spronk HMH, Emsley J, Key NS, Philippou H. Plasma Kallikrein as a Forgotten Clotting Factor. Semin Thromb Hemost 2023. [PMID: 37072020 DOI: 10.1055/s-0043-57034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/20/2023]
Abstract
For decades, it was considered that plasma kallikrein's (PKa) sole function within the coagulation cascade is the activation of factor (F)XII. Until recently, the two key known activators of FIX within the coagulation cascade were activated FXI(a) and the tissue factor-FVII(a) complex. Simultaneously, and using independent experimental approaches, three groups identified a new branch of the coagulation cascade, whereby PKa can directly activate FIX. These key studies identified that (1) FIX or FIXa can bind with high affinity to either prekallikrein (PK) or PKa; (2) in human plasma, PKa can dose dependently trigger thrombin generation and clot formation independent of FXI; (3) in FXI knockout murine models treated with intrinsic pathway agonists, PKa activity results in increased formation of FIXa:AT complexes, indicating direct activation of FIX by PKa in vivo. These findings suggest that there is both a canonical (FXIa-dependent) and non-canonical (PKa-dependent) pathway of FIX activation. These three recent studies are described within this review, alongside historical data that hinted at the existence of this novel role of PKa as a coagulation clotting factor. The implications of direct PKa cleavage of FIX remain to be determined physiologically, pathophysiologically, and in the context of next-generation anticoagulants in development.
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Affiliation(s)
- Katherine J Kearney
- Department of Discovery and Translational Science, Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, United Kingdom
| | - Henri M H Spronk
- Laboratory for Clinical Thrombosis and Haemostasis, Departments of Biochemistry and Internal Medicine, Cardiovascular Research Institute Maastricht, Maastricht University, The Netherlands
| | - Jonas Emsley
- Biodiscovery Institute, School of Pharmacy, University of Nottingham, Nottingham, United Kingdom
| | - Nigel S Key
- Division of Hematology and UNC Blood Research Center, Department of Medicine, University of North Carolina, Chapel Hill, North Carolina
| | - Helen Philippou
- Department of Discovery and Translational Science, Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, United Kingdom
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Bar Barroeta A, Marquart JA, Bakhtiari K, Meijer AB, Urbanus RT, Meijers JCM. Nanobodies against factor XI apple 3 domain inhibit binding of factor IX and reveal a novel binding site for high molecular weight kininogen. J Thromb Haemost 2022; 20:2538-2549. [PMID: 35815349 PMCID: PMC9795894 DOI: 10.1111/jth.15815] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Revised: 06/21/2022] [Accepted: 07/05/2022] [Indexed: 12/30/2022]
Abstract
BACKGROUND Factor XI (FXI) is a promising target for novel anticoagulants because it shows a strong relation to thromboembolic diseases, while fulfilling a mostly supportive role in hemostasis. Anticoagulants targeting FXI could therefore reduce the risk for thrombosis, without increasing the chance of bleeding side effects. OBJECTIVES To generate nanobodies that can interfere with FXIa mediated activation of factor IX (FIX). METHODS Nanobodies were selected for binding to the apple 3 domain of FXI and their effects on FXI and coagulation were measured in purified protein systems as well as in plasma-based coagulation assays. Additionally, the binding epitope of selected nanobodies was assessed by hydrogen-deuterium exchange mass spectrometry. RESULTS We have identified five nanobodies that inhibit FIX activation by FXI by competing with the FIX binding site on FXI. Interestingly, a sixth nanobody was found to target a different binding epitope in the apple 3 domain, resulting in competition with the FXI-high molecular weight kininogen (HK) interaction. CONCLUSIONS We have characterized a nanobody targeting the FXI apple 3 domain that elucidates the binding orientation of HK on FXI. Moreover, we have produced five nanobodies that can inhibit the FXI-FIX interaction.
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Affiliation(s)
| | | | - Kamran Bakhtiari
- Department of Molecular HematologySanquinAmsterdamthe Netherlands
| | - Alexander B. Meijer
- Department of Molecular HematologySanquinAmsterdamthe Netherlands
- Department of PharmaceuticsUtrecht Institute for Pharmaceutical Sciences (UIPS), Utrecht UniversityUtrechtthe Netherlands
| | - Rolf T. Urbanus
- Center for Benign Haematology, Thrombosis and Haemostasis, Van CreveldkliniekUniversity Medical Center Utrecht, University UtrechtUtrechtthe Netherlands
| | - Joost C. M. Meijers
- Department of Molecular HematologySanquinAmsterdamthe Netherlands
- Department of Experimental Vascular MedicineAmsterdam UMC, University of AmsterdamAmsterdamthe Netherlands
- Amsterdam Cardiovascular Sciences, Pulmonary Hypertension and ThrombosisAmsterdamthe Netherlands
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Kuder H, Dickeson SK, Brooks MB, Kehl A, Müller E, Gailani D, Giger U. A Common Missense Variant Causing Factor XI Deficiency and Increased Bleeding Tendency in Maine Coon Cats. Genes (Basel) 2022; 13:792. [PMID: 35627175 PMCID: PMC9140718 DOI: 10.3390/genes13050792] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2022] [Revised: 04/22/2022] [Accepted: 04/26/2022] [Indexed: 02/05/2023] Open
Abstract
Hereditary factor XI (FXI) deficiency is characterized as an autosomal mild to moderate coagulopathy in humans and domestic animals. Coagulation testing revealed FXI deficiency in a core family of Maine Coon cats (MCCs) in the United States. Factor XI-deficient MCCs were homozygous for a guanine to adenine transition resulting in a methionine substitution for the highly conserved valine-516 in the FXI catalytic domain. Immunoblots detected FXI of normal size and quantity in plasmas of MCCs homozygous for V516M. Some FXI-deficient MCCs experienced excessive post-operative/traumatic bleeding. Screening of 263 MCCs in Europe revealed a mutant allele frequency of 0.232 (23.2%). However, V516M was not found among 100 cats of other breeds. Recombinant feline FXI-M516 (fFXI-M516) expressed ~4% of the activity of wild-type fFXI-V516 in plasma clotting assays. Furthermore, fFXIa-M516 cleaved the chromogenic substrate S-2366 with ~4.3-fold lower catalytic efficacy (kcat/Km) than fFXIa-V516, supporting a conformational alteration of the protease active site. The rate of FIX activation by fFXIa-M516 was reduced >3-fold compared with fFXIa-V516. The common missense variant FXI-V516M causes a cross-reactive material positive FXI deficiency in MCCs that is associated with mild-moderate bleeding tendencies. Given the prevalence of the variant in MCCs, genotyping is recommended prior to invasive procedures or breeding.
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Affiliation(s)
- Henrike Kuder
- Vetsuisse Faculty, University of Zürich, Winterthurerstrasse 260, CH-8057 Zurich, Switzerland;
- Laboklin GmbH & Co. KG (Labogen), Steubenstrasse 4, D-97688 Bad Kissingen, Germany; (A.K.); (E.M.)
| | - S. Kent Dickeson
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, 1301 Medical Center Dr, Nashville, TN 37232, USA; (S.K.D.); (D.G.)
| | - Marjory B. Brooks
- Comparative Coagulation Laboratory, Cornell University, 240 Farrier Road, Ithaca, NY 14853, USA;
| | - Alexandra Kehl
- Laboklin GmbH & Co. KG (Labogen), Steubenstrasse 4, D-97688 Bad Kissingen, Germany; (A.K.); (E.M.)
| | - Elisabeth Müller
- Laboklin GmbH & Co. KG (Labogen), Steubenstrasse 4, D-97688 Bad Kissingen, Germany; (A.K.); (E.M.)
| | - David Gailani
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, 1301 Medical Center Dr, Nashville, TN 37232, USA; (S.K.D.); (D.G.)
| | - Urs Giger
- Vetsuisse Faculty, University of Zürich, Winterthurerstrasse 260, CH-8057 Zurich, Switzerland;
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Branchini A, Morfini M, Lunghi B, Belvini D, Radossi P, Bury L, Serino ML, Giordano P, Cultrera D, Molinari AC, Napolitano M, Bigagli E, Castaman G, Pinotti M, Bernardi F. F9 missense mutations impairing factor IX activation are associated with pleiotropic plasma phenotypes. J Thromb Haemost 2022; 20:69-81. [PMID: 34626083 PMCID: PMC9298354 DOI: 10.1111/jth.15552] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Revised: 10/06/2021] [Accepted: 10/06/2021] [Indexed: 11/30/2022]
Abstract
BACKGROUND Circulating dysfunctional factor IX (FIX) might modulate distribution of infused FIX in hemophilia B (HB) patients. Recurrent substitutions at FIX activation sites (R191-R226, >300 patients) are associated with variable FIX activity and antigen (FIXag) levels. OBJECTIVES To investigate the (1) expression of a complete panel of missense mutations at FIX activation sites and (2) contribution of F9 genotypes on the FIX pharmacokinetics (PK). METHODS We checked FIX activity and antigen and activity assays in plasma and after recombinant expression of FIX variants and performed an analysis of infused FIX PK parameters in patients (n = 30), mostly enrolled in the F9 Genotype and PK HB Italian Study (GePKHIS; EudraCT ID2017-003902-42). RESULTS The variable FIXag amounts and good relation between biosynthesis and activity of multiple R191 variants results in graded moderate-to-mild severity of the R191C>L>P>H substitutions. Recombinant expression may predict the absence in the HB mutation database of the benign R191Q/W/K and R226K substitutions. Equivalent changes at R191/R226 produced higher FIXag levels for R226Q/W/P substitutions, as also observed in p.R226W female carrier plasma. Pharmacokinetics analysis in patients suggested that infused FIX Alpha distribution and Beta elimination phases positively correlated with endogenous FIXag levels. Mean residence time was particularly prolonged (79.4 h, 95% confidence interval 44.3-114.5) in patients (n = 7) with the R191/R226 substitutions, which in regression analysis were independent predictors (β coefficient 0.699, P = .004) of Beta half-life, potentially prolonged by the increasing over time ratio between endogenous and infused FIX. CONCLUSIONS FIX activity and antigen levels and specific features of the dysfunctional R191/R226 variants may exert pleiotropic effects both on HB patients' phenotypes and substitutive treatment.
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Affiliation(s)
- Alessio Branchini
- Department of Life Sciences and Biotechnology and LTTA CentreUniversity of FerraraFerraraItaly
| | | | - Barbara Lunghi
- Department of Life Sciences and Biotechnology and LTTA CentreUniversity of FerraraFerraraItaly
| | - Donata Belvini
- Transfusion ServiceHaemophilia Centre and HaematologyCastelfranco Veneto HospitalCastelfranco VenetoItaly
| | - Paolo Radossi
- Oncohematology‐Oncologic Institute of VenetoCastelfranco Veneto HospitalCastelfranco VenetoItaly
| | - Loredana Bury
- Department of Medicine and SurgeryUniversity of PerugiaPerugiaItaly
| | - Maria Luisa Serino
- Haemostasis and Thrombosis CentreUniversity Hospital of FerraraFerraraItaly
| | - Paola Giordano
- Paediatric SectionDepartment of Biomedicine and Human OncologyA. Moro” UniversityBariItaly
| | - Dorina Cultrera
- Haemophilia Regional Reference CenterVittorio Emanuele” University HospitalCataniaItaly
| | | | - Mariasanta Napolitano
- Haematology UnitThrombosis and Haemostasis Reference Regional Center and PROMISE DepartmentUniversity of PalermoPalermoItaly
| | - Elisabetta Bigagli
- Department of Neuroscience, PsychologyDrug Research and Child Health (NEUROFARBA)Section of Pharmacology and ToxicologyUniversity of FlorenceFlorenceItaly
| | - Giancarlo Castaman
- Department of Oncology, Center for Bleeding DisordersCareggi University HospitalFirenzeItaly
| | - Mirko Pinotti
- Department of Life Sciences and Biotechnology and LTTA CentreUniversity of FerraraFerraraItaly
| | - Francesco Bernardi
- Department of Life Sciences and Biotechnology and LTTA CentreUniversity of FerraraFerraraItaly
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Abstract
Haemophilia A and B are rare congenital, recessive X-linked disorders caused by lack or deficiency of clotting factor VIII (FVIII) or IX (FIX), respectively. The severity of the disease depends on the reduction of levels of FVIII or FIX, which are determined by the type of the causative mutation in the genes encoding the factors (F8 and F9, respectively). The hallmark clinical characteristic, especially in untreated severe forms, is bleeding (spontaneous or after trauma) into major joints such as ankles, knees and elbows, which can result in the development of arthropathy. Intracranial bleeds and bleeds into internal organs may be life-threatening. The median life expectancy was ~30 years until the 1960s, but improved understanding of the disorder and development of efficacious therapy based on prophylactic replacement of the missing factor has caused a paradigm shift, and today individuals with haemophilia can look forward to a virtually normal life expectancy and quality of life. Nevertheless, the potential development of inhibitory antibodies to infused factor is still a major hurdle to overcome in a substantial proportion of patients. Finally, gene therapy for both types of haemophilia has progressed remarkably and could soon become a reality.
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Hayakawa Y, Tamura S, Suzuki N, Odaira K, Tokoro M, Kawashima F, Hayakawa F, Takagi A, Katsumi A, Suzuki A, Okamoto S, Kanematsu T, Matsushita T, Kojima T. Essential role of a carboxyl-terminal α-helix motif in the secretion of coagulation factor XI. J Thromb Haemost 2021; 19:920-930. [PMID: 33421272 DOI: 10.1111/jth.15242] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Revised: 12/28/2020] [Accepted: 01/04/2021] [Indexed: 11/29/2022]
Abstract
BACKGROUND Coagulation factor XI (FXI) is a plasma serine protease zymogen that contributes to hemostasis. However, the mechanism of its secretion remains unclear. OBJECTIVE To determine the molecular mechanism of FXI secretion by characterizing a novel FXI mutant identified in a FXI-deficient Japanese patient. PATIENT/METHODS The FXI gene (F11) was analyzed by direct sequencing. Mutant recombinant FXI (rFXI) was overexpressed in HEK293 or COS-7 cells. Western blotting and enzyme-linked immunosorbent assay were performed to examine the FXI extracellular secretion profile. Immunofluorescence microscopy was used to investigate the subcellular localization of the rFXI mutant. RESULTS We identified a novel homozygous frameshift mutation in F11 [c.1788dupC (p.E597Rfs*65)], resulting in a unique and extended carboxyl-terminal (C-terminal) structure in FXI. Although rFXI-E597Rfs*65 was intracellularly synthesized, its extracellular secretion was markedly reduced. Subcellular localization analysis revealed that rFXI-E597Rfs*65 was abnormally retained in the endoplasmic reticulum (ER). We generated a series of C-terminal-truncated rFXI mutants to further investigate the role of the C-terminal region in FXI secretion. Serial rFXI experiments revealed that a threonine at position 622, the fourth residue from the C-terminus, was essential for secretion. Notably, Thr622 engages in the formation of an α-helix motif, indicating the importance of the C-terminal α-helix in FXI intracellular behavior and secretion. CONCLUSION FXI E597Rfs*65 results in the pathogenesis of a severe secretory defect resulting from aberrant ER-to-Golgi trafficking caused by the lack of a C-terminal α-helix motif. This study demonstrates the impact of the C-terminal structure, especially the α-helix motif, on FXI secretion.
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Affiliation(s)
- Yuri Hayakawa
- Division of Cellular and Genetic Sciences, Department of Integrated Health Sciences, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Shogo Tamura
- Division of Cellular and Genetic Sciences, Department of Integrated Health Sciences, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Nobuaki Suzuki
- Department of Transfusion Medicine, Nagoya University Hospital, Nagoya, Japan
| | - Koya Odaira
- Division of Cellular and Genetic Sciences, Department of Integrated Health Sciences, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Mahiru Tokoro
- Division of Cellular and Genetic Sciences, Department of Integrated Health Sciences, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Fumika Kawashima
- Division of Cellular and Genetic Sciences, Department of Integrated Health Sciences, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Fumihiko Hayakawa
- Division of Cellular and Genetic Sciences, Department of Integrated Health Sciences, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Akira Takagi
- Department of Medical Technology, Shubun University, Ichinomiya, Japan
| | - Akira Katsumi
- Department of Hematology, National Center for Geriatrics and Gerontology, Obu City, Japan
| | - Atsuo Suzuki
- Department of Clinical Laboratory, Nagoya University Hospital, Nagoya, Japan
| | - Shuichi Okamoto
- Department of Hematology and Oncology, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Takeshi Kanematsu
- Department of Clinical Laboratory, Nagoya University Hospital, Nagoya, Japan
| | - Tadashi Matsushita
- Department of Transfusion Medicine, Nagoya University Hospital, Nagoya, Japan
- Department of Clinical Laboratory, Nagoya University Hospital, Nagoya, Japan
| | - Tetsuhito Kojima
- Division of Cellular and Genetic Sciences, Department of Integrated Health Sciences, Nagoya University Graduate School of Medicine, Nagoya, Japan
- Aichi Health Promotion Foundation, Nagoya, Japan
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Ponczek MB, Shamanaev A, LaPlace A, Dickeson SK, Srivastava P, Sun MF, Gruber A, Kastrup C, Emsley J, Gailani D. The evolution of factor XI and the kallikrein-kinin system. Blood Adv 2020; 4:6135-6147. [PMID: 33351111 PMCID: PMC7757006 DOI: 10.1182/bloodadvances.2020002456] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Accepted: 10/19/2020] [Indexed: 12/16/2022] Open
Abstract
Factor XI (FXI) is the zymogen of a plasma protease (FXIa) that contributes to hemostasis by activating factor IX (FIX). In the original cascade model of coagulation, FXI is converted to FXIa by factor XIIa (FXIIa), a component, along with prekallikrein and high-molecular-weight kininogen (HK), of the plasma kallikrein-kinin system (KKS). More recent coagulation models emphasize thrombin as a FXI activator, bypassing the need for FXIIa and the KKS. We took an evolutionary approach to better understand the relationship of FXI to the KKS and thrombin generation. BLAST searches were conducted for FXI, FXII, prekallikrein, and HK using genomes for multiple vertebrate species. The analysis shows the KKS appeared in lobe-finned fish, the ancestors of all land vertebrates. FXI arose later from a duplication of the prekallikrein gene early in mammalian evolution. Features of FXI that facilitate efficient FIX activation are present in all living mammals, including primitive egg-laying monotremes, and may represent enhancement of FIX-activating activity inherent in prekallikrein. FXI activation by thrombin is a more recent acquisition, appearing in placental mammals. These findings suggest FXI activation by FXIIa may be more important to hemostasis in primitive mammals than in placental mammals. FXI activation by thrombin places FXI partially under control of the vitamin K-dependent coagulation mechanism, reducing the importance of the KKS in blood coagulation. This would explain why humans with FXI deficiency have a bleeding abnormality, whereas those lacking components of the KKS do not.
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Affiliation(s)
- Michał B Ponczek
- Department of General Biochemistry, Faculty of Biology and Environmental Protection, University of Lodz, Lodz, Poland
| | - Aleksandr Shamanaev
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN
| | - Alec LaPlace
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN
| | - S Kent Dickeson
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN
| | - Priyanka Srivastava
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN
| | - Mao-Fu Sun
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN
| | - Andras Gruber
- Department of Biomedical Engineering and
- Division of Hematology and Medical Oncology, School of Medicine, Oregon Health and Sciences University, Portland, OR
- Aronora, Inc., Portland, OR
| | - Christian Kastrup
- Michael Smith Laboratories and Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC, Canada; and
| | - Jonas Emsley
- Biodiscovery Institute, School of Pharmacy, University of Nottingham, Nottingham, United Kingdom
| | - David Gailani
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN
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Grover SP, Olson TM, Cooley BC, Mackman N. Model-dependent contributions of FXII and FXI to venous thrombosis in mice. J Thromb Haemost 2020; 18:2899-2909. [PMID: 33094904 PMCID: PMC7693194 DOI: 10.1111/jth.15037] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Revised: 07/07/2020] [Accepted: 07/17/2020] [Indexed: 12/17/2022]
Abstract
BACKGROUND The intrinsic pathway factors (F) XII and FXI have been shown to contribute to thrombosis in animal models. We assessed the role of FXII and FXI in venous thrombosis in three distinct mouse models. METHODS Venous thrombosis was assessed in mice genetically deficient for either FXII or FXI. Three models were used: the inferior vena cava (IVC) stasis, IVC stenosis, and femoral vein electrolytic injury models. RESULTS In the IVC stasis model, FXII and FXI deficiency did not affect the size of thrombi but their absence was associated with decreased levels of fibrin(ogen) and an increased level of the neutrophil extracellular trap marker citrullinated histone H3. In contrast, a deficiency of either FXII or FXI resulted in a significant and equivalent reduction in thrombus weight and incidence of thrombus formation in the IVC stenosis model. Thrombi formed in the IVC stenosis model contained significantly higher levels of citrullinated histone H3 compared with the thrombi formed in the IVC stasis model. Deletion of either FXII or FXI also resulted in a significant and equivalent reduction in both fibrin and platelet accumulation in the femoral vein electrolytic injury model. CONCLUSIONS Collectively, these data indicate that FXII and FXI contribute to the size of venous thrombosis in models with blood flow and thrombus composition in a stasis model. This study also demonstrates the importance of using multiple mouse models to assess the role of a given protein in venous thrombosis.
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Affiliation(s)
- Steven P. Grover
- Division of Hematology and OncologyDepartment of MedicineUNC Blood Research CenterUniversity of North Carolina at Chapel HillChapel HillNCUSA
| | - Tatianna M. Olson
- Division of Hematology and OncologyDepartment of MedicineUNC Blood Research CenterUniversity of North Carolina at Chapel HillChapel HillNCUSA
| | - Brian C. Cooley
- Department of Pathology and Laboratory MedicineMcAllister Heart InstituteUniversity of North Carolina at Chapel HillChapel HillNCUSA
| | - Nigel Mackman
- Division of Hematology and OncologyDepartment of MedicineUNC Blood Research CenterUniversity of North Carolina at Chapel HillChapel HillNCUSA
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Al-Horani RA. Factor XI(a) inhibitors for thrombosis: an updated patent review (2016-present). Expert Opin Ther Pat 2019; 30:39-55. [PMID: 31847619 DOI: 10.1080/13543776.2020.1705783] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Introduction: Anticoagulation without bleeding is an ideal goal in treating thrombosis, however, this goal has not been achieved. All current anticoagulants are associated with significant bleeding which limits their safe use. Genetic and pharmacological findings indicate that factor XIa is a key player in thrombosis, yet it is a relatively marginal one in hemostasis. Thus, factor XIa and its zymogen offer a unique opportunity to develop anticoagulants with low bleeding risk.Areas covered: A survey of patent literature has retrieved more than 50 patents on the discovery of novel therapeutics targeting factor XI(a) since 2016. Small molecules, monoclonal antibodies, oligonucleotides, and polypeptides have been developed to inhibit factor XI(a). Many inhibitors are in early development and few have been evaluated in clinical trials.Expert opinion: Factor XI(a) is being actively pursued as a drug target for the development of effective and safer anticoagulants. Although many patents claiming factor XI(a) inhibitors were filed prior to 2016, recent literature reveals a moderately declining trend. Nevertheless, more agents have entered different levels of clinical trials. These agents exploit diverse mechanistic strategies for inhibition. Although further development is warranted, reaching one or more of these agents to the clinic will transform the anticoagulation therapy.
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Affiliation(s)
- Rami A Al-Horani
- Division of Basic Pharmaceutical Sciences, College of Pharmacy, Xavier University of Louisiana, New Orleans, LA, USA
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Gailani D, Emsley J. Toward a better understanding of factor XI activation. J Thromb Haemost 2019; 17:2016-2018. [PMID: 31797540 PMCID: PMC8559519 DOI: 10.1111/jth.14631] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2019] [Accepted: 09/05/2019] [Indexed: 12/14/2022]
Affiliation(s)
- David Gailani
- The Department of Pathology, Microbiology and Immunology,
Vanderbilt University, Nashville, TN, USA
| | - Jonas Emsley
- The Center for Biomolecular Sciences, School of Pharmacy,
University of Nottingham, Nottingham, UK
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11
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Bar Barroeta A, van Galen J, Stroo I, Marquart JA, Meijer AB, Meijers JCM. Hydrogen-deuterium exchange mass spectrometry highlights conformational changes induced by factor XI activation and binding of factor IX to factor XIa. J Thromb Haemost 2019; 17:2047-2055. [PMID: 31519061 PMCID: PMC6916417 DOI: 10.1111/jth.14632] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Revised: 08/06/2019] [Accepted: 08/19/2019] [Indexed: 12/19/2022]
Abstract
BACKGROUND Factor XI (FXI) is a zymogen in the coagulation pathway that, once activated, promotes haemostasis by activating factor IX (FIX). Substitution studies using apple domains of the homologous protein prekallikrein have identified that FIX binds to the apple 3 domain of FXI. However, the molecular changes upon activation of FXI or binding of FIX to FXIa have remained largely unresolved. OBJECTIVES This study aimed to gain more insight in the FXI activation mechanism by identifying the molecular differences between FXI and FXIa, and in the conformational changes in FXIa induced by binding of FIX. METHODS Hydrogen-deuterium exchange mass spectrometry was performed on FXI, FXIa, and FXIa in complex with FIX. RESULTS Both activation and binding to FIX induced conformational changes at the interface between the catalytic domain and the apple domains of FXI(a)-more specifically at the loops connecting the apple domains. Moreover, introduction of FIX uniquely induced a reduction of deuterium uptake in the beginning of the apple 3 domain. CONCLUSIONS We propose that the conformational changes of the catalytic domain upon activation increase the accessibility to the apple 3 domain to enable FIX binding. Moreover, our HDX MS results support the location of the proposed FIX binding site at the beginning of the apple 3 domain and suggest a mediating role in FIX binding for both loops adjacent to the apple 3 domain.
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Affiliation(s)
- Awital Bar Barroeta
- Department of Molecular and Cellular HemostasisSanquin ResearchAmsterdamThe Netherlands
| | - Josse van Galen
- Department of Molecular and Cellular HemostasisSanquin ResearchAmsterdamThe Netherlands
| | - Ingrid Stroo
- Department of Molecular and Cellular HemostasisSanquin ResearchAmsterdamThe Netherlands
| | - J. Arnoud Marquart
- Department of Molecular and Cellular HemostasisSanquin ResearchAmsterdamThe Netherlands
| | - Alexander B. Meijer
- Department of Molecular and Cellular HemostasisSanquin ResearchAmsterdamThe Netherlands
- Department of PharmaceuticsUtrecht Institute for Pharmaceutical Sciences (UIPS)Utrecht UniversityUtrechtThe Netherlands
| | - Joost C. M. Meijers
- Department of Molecular and Cellular HemostasisSanquin ResearchAmsterdamThe Netherlands
- Department of Experimental Vascular MedicineAmsterdam UMCUniversity of AmsterdamAmsterdamThe Netherlands
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13
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Minami H, Nogami K, Yada K, Ogiwara K, Furukawa S, Soeda T, Kitazawa T, Shima M. Emicizumab, the bispecific antibody to factors IX/IXa and X/Xa, potentiates coagulation function in factor XI-deficient plasma in vitro. J Thromb Haemost 2019; 17:126-137. [PMID: 30444568 DOI: 10.1111/jth.14334] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2018] [Indexed: 08/31/2023]
Abstract
Essentials Emicizumab mimics factor (F)VIIIa cofactor function, augments the intrinsic tenase activity. We assessed the emicizumab-driven hemostatic function in FXI-deficient plasmas. Emicizumab improved the coagulation potentials in severe FXI-deficient plasma. Emicizumab may provide a possibility for clinical application in patients with FXI deficiency. SUMMARY: Background Patients with factor (F)XI deficiency commonly present with markedly prolonged activated partial thromboplastin times (APTT), although bleeding phenotypes are heterogeneous. Emicizumab, a bispecific monoclonal antibody to FIX/FIXa and FX/FXa, mimics FVIIIa cofactor function on phospholipid (PL) surfaces. Antibody reactions were designed, therefore, to augment mechanisms during the propagation phase of blood coagulation. Aim To assess emicizumab-driven hemostatic function in FXI-deficient plasmas. Methods and Results Standard ellagic acid (Elg)/PL-based APTTs of different FXI-deficient plasmas (n = 13; FXI activity, < 1 IU dl-1 ) were markedly shortened dose dependently by the presence of emicizumab. To further analyze the effects of emicizumab, clot waveform analysis (CWA) in FXI-deficient plasmas with emicizumab, triggered by tissue factor (TF)/Elg demonstrated improvements in both clot times, reflecting the initiation phase, and coagulation velocity, which represents the propagation phase. Emicizumab also enhanced the TF/Elg-triggered thrombin generation in FXI-deficient plasmas dose-dependently although the degree of enhancement varied in individual cases. Thrombin generation with either FVII-deficient plasma or FIX-deficient plasma treated with anti-FXI antibody showed little or no increase by the co-presence of emicizumab, suggesting that the accelerated thrombin generation in FXI-deficient plasmas by emicizumab should depend on the FIXa-involved coagulation propagation initially triggered by FVIIa/TF. The ex vivo addition of emicizumab to whole blood from three patients with severe FXI deficiency demonstrated modest, dose-dependent improvements in Ca2+ -triggered thromboelastograms (NATEM mode). Conclusion Emicizumab appeared to improve coagulation function in severe FXI-deficient plasma, and might provide possibilities for clinical application in patients with FXI deficiency.
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Affiliation(s)
- H Minami
- Department of Pediatrics, Nara Medical University, Kashihara, Nara, Japan
| | - K Nogami
- Department of Pediatrics, Nara Medical University, Kashihara, Nara, Japan
| | - K Yada
- Department of Pediatrics, Nara Medical University, Kashihara, Nara, Japan
| | - K Ogiwara
- Department of Pediatrics, Nara Medical University, Kashihara, Nara, Japan
| | - S Furukawa
- Department of Pediatrics, Nara Medical University, Kashihara, Nara, Japan
| | - T Soeda
- Research Division, Chugai Pharmaceutical Co., Ltd, Kamakura, Japan
| | - T Kitazawa
- Research Division, Chugai Pharmaceutical Co., Ltd, Kamakura, Japan
| | - M Shima
- Department of Pediatrics, Nara Medical University, Kashihara, Nara, Japan
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14
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Mohammed BM, Matafonov A, Ivanov I, Sun MF, Cheng Q, Dickeson SK, Li C, Sun D, Verhamme IM, Emsley J, Gailani D. An update on factor XI structure and function. Thromb Res 2018; 161:94-105. [PMID: 29223926 PMCID: PMC5776729 DOI: 10.1016/j.thromres.2017.10.008] [Citation(s) in RCA: 99] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2017] [Revised: 10/04/2017] [Accepted: 10/09/2017] [Indexed: 12/19/2022]
Abstract
Factor XI (FXI) is the zymogen of a plasma protease, factor XIa (FXIa), that contributes to thrombin generation during blood coagulation by proteolytic activation of several coagulation factors, most notably factor IX (FIX). FXI is a homolog of prekallikrein (PK), a component of the plasma kallikrein-kinin system. While sharing structural and functional features with PK, FXI has undergone adaptive changes that allow it to contribute to blood coagulation. Here we review current understanding of the biology and enzymology of FXI, with an emphasis on structural features of the protein as they relate to protease function.
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Affiliation(s)
- Bassem M Mohammed
- Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN, USA; School of Pharmacy, Department of Clinical Pharmacy, Cairo University, Cairo, Egypt
| | - Anton Matafonov
- Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Ivan Ivanov
- Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Mao-Fu Sun
- Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Qiufang Cheng
- Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - S Kent Dickeson
- Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Chan Li
- School of Pharmacy, Centre for Biomolecular Sciences, University of Nottingham, Nottingham, UK
| | - David Sun
- Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Ingrid M Verhamme
- Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Jonas Emsley
- School of Pharmacy, Centre for Biomolecular Sciences, University of Nottingham, Nottingham, UK
| | - David Gailani
- Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN, USA.
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15
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Woodruff RS, Ivanov I, Verhamme IM, Sun MF, Gailani D, Sullenger BA. Generation and characterization of aptamers targeting factor XIa. Thromb Res 2017. [PMID: 28644959 DOI: 10.1016/j.thromres.2017.06.015] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
BACKGROUND The plasma protease factor XIa (FXIa) has become a target of interest for therapeutics designed to prevent or treat thrombotic disorders. METHODS We used a solution-based, directed evolution approach called systematic evolution of ligands by exponential enrichment (SELEX) to isolate RNA aptamers that target the FXIa catalytic domain. RESULTS Two aptamers, designated 11.16 and 12.7, were identified that bound to previously identified anion binding and serpin bindings sites on the FXIa catalytic domain. The aptamers were non-competitive inhibitors of FXIa cleavage of a tripeptide chromogenic substrate and of FXIa activation of factor IX. In normal human plasma, aptamer 12.7 significantly prolonged the aPTT clotting time. CONCLUSIONS The results show that novel inhibitors of FXIa can be prepared using SELEX techniques. RNA aptamers can bind to distinct sites on the FXIa catalytic domain and noncompetitively inhibit FXIa activity toward its primary macromolecular substrate factor IX with different levels of potency. Such compounds can be developed for use as therapeutic inhibitors.
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Affiliation(s)
- R S Woodruff
- Department of Surgery, Duke University Medical Center, Durham, NC, United States; University Program in Genetics and Genomics, Duke University, Durham, NC, United States
| | - I Ivanov
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN, United States
| | - I M Verhamme
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN, United States
| | - M-F Sun
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN, United States
| | - D Gailani
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN, United States
| | - B A Sullenger
- Department of Surgery, Duke University Medical Center, Durham, NC, United States.
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16
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Ivanov I, Shakhawat R, Sun MF, Dickeson SK, Puy C, McCarty OJT, Gruber A, Matafonov A, Gailani D. Nucleic acids as cofactors for factor XI and prekallikrein activation: Different roles for high-molecular-weight kininogen. Thromb Haemost 2017; 117:671-681. [PMID: 28124063 DOI: 10.1160/th16-09-0691] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2016] [Accepted: 12/26/2016] [Indexed: 01/12/2023]
Abstract
The plasma zymogens factor XI (fXI) and prekallikrein (PK) are activated by factor XIIa (fXIIa) during contact activation. Polyanions such as DNA and RNA may contribute to thrombosis and inflammation partly by enhancing PK and fXI activation. We examined PK and fXI activation in the presence of nucleic acids, and determine the effects of the cofactor high molecular weight kininogen (HK) on the reactions. In the absence of HK, DNA and RNA induced fXI autoactivation. Proteases known to activate fXI (fXIIa and thrombin) did not enhance this process appreciably. Nucleic acids had little effect on PK activation by fXIIa in the absence of HK. HK had significant but opposite effects on PK and fXI activation. HK enhanced fXIIa activation of PK in the presence of nucleic acids, but blocked fXI autoactivation. Thrombin and fXIIa could overcome the HK inhibitory effect on autoactivation, indicating these proteases are necessary for nucleic acid-induced fXI activation in an HK-rich environment such as plasma. In contrast to PK, which requires HK for optimal activation, fXI activation in the presence of nucleic acids depends on anion binding sites on the fXI molecule. The corresponding sites on PK are not necessary for PK activation. Our results indicate that HK functions as a cofactor for PK activation in the presence of nucleic acids in a manner consistent with classic models of contact activation. However, HK has, on balance, an inhibitory effect on nucleic acid-supported fXI activation and may function as a negative regulator of fXI activation.
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Affiliation(s)
| | | | | | | | | | | | | | | | - David Gailani
- David Gailani, Hematology/Oncology Division, Vanderbilt University Medical Center, 777 Preston Research Building, 2220 Pierce Ave., Nashville, TN, USA, Tel.: +1 615 936 1505, E-mail:
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17
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Gailani D, Bane CE, Gruber A. Factor XI and contact activation as targets for antithrombotic therapy. J Thromb Haemost 2015; 13:1383-95. [PMID: 25976012 PMCID: PMC4516614 DOI: 10.1111/jth.13005] [Citation(s) in RCA: 96] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2015] [Accepted: 05/01/2015] [Indexed: 11/26/2022]
Abstract
The most commonly used anticoagulants produce therapeutic antithrombotic effects either by inhibiting thrombin or factor Xa (FXa) or by lowering the plasma levels of the precursors of these key enzymes, prothrombin and FX. These drugs do not distinguish between thrombin generation contributing to thrombosis from thrombin generation required for hemostasis. Thus, anticoagulants increase bleeding risk, and many patients who would benefit from therapy go untreated because of comorbidities that place them at unacceptable risk for hemorrhage. Studies in animals demonstrate that components of the plasma contact activation system contribute to experimentally induced thrombosis, despite playing little or no role in hemostasis. Attention has focused on FXII, the zymogen of a protease (FXIIa) that initiates contact activation when blood is exposed to foreign surfaces, and FXI, the zymogen of the protease FXIa, which links contact activation to the thrombin generation mechanism. In the case of FXI, epidemiologic data indicate this protein contributes to stroke and venous thromboembolism, and perhaps myocardial infarction, in humans. A phase 2 trial showing that reduction of FXI may be more effective than low molecular weight heparin at preventing venous thrombosis during knee replacement surgery provides proof of concept for the premise that an antithrombotic effect can be uncoupled from an anticoagulant effect in humans by targeting components of contact activation. Here, we review data on the role of FXI and FXII in thrombosis and results of preclinical and human trials for therapies targeting these proteins.
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Affiliation(s)
- David Gailani
- Department of Pathology, Microbiology and Immunology, Vanderbilt University, Nashville, Tennessee, USA
| | - Charles E. Bane
- Department of Pathology, Microbiology and Immunology, Vanderbilt University, Nashville, Tennessee, USA
| | - Andras Gruber
- Department of Biomedical Engineering, Oregon Health & Science University, Portland, OR
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18
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Gailani D, Geng Y, Verhamme I, Sun MF, Bajaj SP, Messer A, Emsley J. The mechanism underlying activation of factor IX by factor XIa. Thromb Res 2014; 133 Suppl 1:S48-51. [PMID: 24759143 DOI: 10.1016/j.thromres.2014.03.020] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Factor XI (fXI) is the zymogen of a plasma protease, factor XIa (fXIa), that contributes to thrombin generation during blood coagulation by proteolytic conversion of factor IX (fIX) to factor IXaβ (fIXaβ). There is considerable interest in fXIa as a therapeutic target because it contributes to thrombosis, while serving a relatively minor role in hemostasis. FXI/XIa has a distinctly different structure than other plasma coagulation proteases. Specifically, the protein lacks a phospholipid-binding Gla-domain, and is a homodimer. Each subunit of a fXIa dimer contains four apple domains (A1 to A4) and one trypsin-like catalytic domain. The A3 domain contains a binding site (exosite) that largely determines affinity and specificity for the substrate fIX. After binding to fXIa, fIX undergoes a single cleavage to form the intermediate fIXα. FIXα then rebinds to the A3 domain to undergo a second cleavage, generating fIXaβ. The catalytic efficiency for the second cleavage is ~7-fold greater than that of the first cleavage, limiting fIXα accumulation. Residues at the N-terminus and C-terminus of the fXIa A3 domain likely form the fIX binding site. The dimeric conformation of fXIa is not required for normal fIX activation in solution. However, monomeric forms of fXI do not reconstitute fXI-deficient mice in arterial thrombosis models, indicating the dimer is required for normal function in vivo. FXI must be a dimer to be activated normal by the protease fXIIa. It is also possible that the dimeric structure is an adaptation that allows fXI/XIa to bind to a surface through one subunit, while binding to its substrate fIX through the other.
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Affiliation(s)
- David Gailani
- Department of Pathology, Microbiology and Immunology, Vanderbilt University, Nashville, TN, United States.
| | - Yipeng Geng
- Department of Pathology, Microbiology and Immunology, Vanderbilt University, Nashville, TN, United States
| | - Ingrid Verhamme
- Department of Pathology, Microbiology and Immunology, Vanderbilt University, Nashville, TN, United States
| | - Mao-fu Sun
- Department of Pathology, Microbiology and Immunology, Vanderbilt University, Nashville, TN, United States
| | - S Paul Bajaj
- Department of Orthopaedic Surgery, David Geffen School of Medicine at UCLA, Los Angeles, CA, United States
| | - Amanda Messer
- Department of Orthopaedic Surgery, David Geffen School of Medicine at UCLA, Los Angeles, CA, United States
| | - Jonas Emsley
- School of Pharmacy, Centre for Biomolecular Sciences, University of Nottingham, Nottingham, UK
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19
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Bane CE, Gailani D. Factor XI as a target for antithrombotic therapy. Drug Discov Today 2014; 19:1454-8. [PMID: 24886766 DOI: 10.1016/j.drudis.2014.05.018] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2014] [Accepted: 05/20/2014] [Indexed: 11/19/2022]
Abstract
Anticoagulants currently used in clinical practice to treat thromboembolic disorders are effective but increase the risk of severe bleeding because they target proteins that are essential for normal coagulation (hemostasis). Drugs with better safety profiles are required for prevention and treatment of thromboembolic disease. Coagulation factor XIa has emerged as a novel target for safer anticoagulant therapy because of its role in thrombosis and its relatively small contribution to hemostasis.
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Affiliation(s)
- Charles E Bane
- Department of Pathology, Microbiology and Immunology, Vanderbilt University, Nashville, TN, USA
| | - David Gailani
- Department of Pathology, Microbiology and Immunology, Vanderbilt University, Nashville, TN, USA.
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20
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Argade MD, Mehta AY, Sarkar A, Desai UR. Allosteric inhibition of human factor XIa: discovery of monosulfated benzofurans as a class of promising inhibitors. J Med Chem 2014; 57:3559-69. [PMID: 24666186 PMCID: PMC4317055 DOI: 10.1021/jm5002698] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
![]()
Factor
XIa (fXIa) is being recognized as a prime target for developing
safer anticoagulants. To discover synthetic, small, allosteric inhibitors
of fXIa, we screened an in-house, unique library of 65 molecules displaying
many distinct scaffolds and varying levels of sulfation. Of these,
monosulfated benzofurans were the only group of molecules found to
inhibit fXIa (∼100% efficacy) and led to the identification
of monosulfated trimer 24 (IC50 0.82 μM)
as the most potent inhibitor. Michaelis–Menten kinetics studies
revealed a classic noncompetitive mechanism of action for 24. Although monosulfated, the inhibitors did not compete with unfractionated
heparin alluding to a novel site of interaction. Fluorescence quenching
studies indicated that trimer 24 induces major conformational
changes in the active site of fXIa. Docking studies identified a site
near Lys255 on the A3 domain of fXIa as the most probable site of
binding for 24. Factor XIa devoid of the A3 domain displayed
a major defect in the inhibition potency of 24 supporting
the docking prediction. Our work presents the sulfated benzofuran
scaffold as a promising framework to develop allosteric fXIa inhibitors
that likely function through the A3 domain.
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Affiliation(s)
- Malaika D Argade
- Department of Medicinal Chemistry and Institute for Structural Biology and Drug Discovery, Virginia Commonwealth University , Richmond, Virginia 23219, United States
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21
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Abstract
The plasma zymogens factor XII (fXII) and factor XI (fXI) contribute to thrombosis in a variety of mouse models. These proteins serve a limited role in hemostasis, suggesting that antithrombotic therapies targeting them may be associated with low bleeding risks. Although there is substantial epidemiologic evidence supporting a role for fXI in human thrombosis, the situation is not as clear for fXII. We generated monoclonal antibodies (9A2 and 15H8) against the human fXII heavy chain that interfere with fXII conversion to the protease factor XIIa (fXIIa). The anti-fXII antibodies were tested in models in which anti-fXI antibodies are known to have antithrombotic effects. Both anti-fXII antibodies reduced fibrin formation in human blood perfused through collagen-coated tubes. fXII-deficient mice are resistant to ferric chloride-induced arterial thrombosis, and this resistance can be reversed by infusion of human fXII. 9A2 partially blocks, and 15H8 completely blocks, the prothrombotic effect of fXII in this model. 15H8 prolonged the activated partial thromboplastin time of baboon and human plasmas. 15H8 reduced fibrin formation in collagen-coated vascular grafts inserted into arteriovenous shunts in baboons, and reduced fibrin and platelet accumulation downstream of the graft. These findings support a role for fXII in thrombus formation in primates.
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22
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Yu Y, Millar CM. Measurement of factor IX activity in plasma-derived and recombinant concentrates: insights from thrombin generation and activation-based assays. J Thromb Haemost 2014; 12:62-70. [PMID: 24215160 DOI: 10.1111/jth.12452] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2013] [Indexed: 11/30/2022]
Abstract
BACKGROUND Hemophilia B, resulting from a deficiency of coagulation factor IX, is treated effectively with either recombinant FIX (r-FIX) or plasma-derived FIX (pd-FIX) concentrates, although differences in pharmacokinetics are observed. FIX is activated in vivo by both activated FXI (FXIa) and tissue factor (TF)-activated FVII (FVIIa); however, conventional activated partial thromboplastin time (APTT)-based assays assess only activation by FXIa. OBJECTIVES To examine the differences between pd-FIX and r-FIX concentrates with respect to their thrombogenicity and activation. METHODS AND RESULTS FIX ELISA was used to quantify antigenic FIX. Calibrated automated thrombography was performed to evaluate the effect of FIX on thrombin generation. FIXa was quantified by the cleavage of FIXa-specific chromogenic substrate. FIX activation was studied in a purified system. RESULTS We found that r-FIX had ~ 1.6-fold greater specific activity than pd-FIX. r-FIX generated a markedly higher thrombin peak than pd-FIX at an equivalent antigen level when coagulation was initiated by TF, but this was not seen in contact activation-triggered thrombin generation (TG). Interestingly, the amount of FIXa in r-FIX concentrate was 10 times higher than that in pd-FIX concentrate. In a purified system, the amount of r-FIXa generated by FXIa in the first 10 min of activation was 1.37-fold that of pd-FIXa, whereas no difference between the concentrates was observed when triggered by TF-FVIIa. CONCLUSIONS Clear differences were observed between pd-FIX and r-FIX concentrates, including the proportion of FIXa and the activation by FXIa. These may explain some of the discrepancies observed clinically, and suggest that the APTT may not reflect their resultant in vivo properties.
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Affiliation(s)
- Y Yu
- Centre for Haematology, Department of Medicine, Imperial College London, London, UK
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23
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Matafonov A, Cheng Q, Geng Y, Verhamme IM, Umunakwe O, Tucker EI, Sun MF, Serebrov V, Gruber A, Gailani D. Evidence for factor IX-independent roles for factor XIa in blood coagulation. J Thromb Haemost 2013; 11:2118-27. [PMID: 24152424 PMCID: PMC3947433 DOI: 10.1111/jth.12435] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2013] [Accepted: 10/15/2013] [Indexed: 01/01/2023]
Abstract
BACKGROUND Factor XIa is traditionally assigned a role in FIX activation during coagulation. However, recent evidence suggests this protease may have additional plasma substrates. OBJECTIVE To determine whether FXIa promotes thrombin generation and coagulation in plasma in the absence of FIX, and to determine whether FXI-deficiency produces an antithrombotic effect in mice independently of FIX. METHODS FXIa, FXIa variants and anti-FXIa antibodies were tested for their effects on plasma coagulation and thrombin generation in the absence of FIX, and for their effects on the activation of purified coagulation factors. Mice with combined FIX and FXI deficiency were compared with mice lacking either FIX or FXI in an arterial thrombosis model. RESULTS In FIX-deficient plasma, FXIa induced thrombin generation, and anti-FXIa antibodies prolonged clotting times. This process involved FXIa-mediated conversion of FX and FV to their active forms. Activation of FV by FXIa required the A3 domain on the FXIa heavy chain, whereas activation of FX did not. FX activation by FXIa, unlike FIX activation, was not a calcium-dependent process. Mice lacking both FIX and FXI were more resistant to ferric chloride-induced carotid artery occlusion than FXI-deficient or FIX-deficient mice. CONCLUSION In addition to its predominant role as an activator of FIX, FXIa may contribute to coagulation by activating FX and FV. As the latter reactions do not require calcium, they may make important contributions to in vitro clotting triggered by contact activation. The reactions may be relevant to FXIa's roles in hemostasis and in promoting thrombosis.
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Affiliation(s)
- Anton Matafonov
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University, Nashville, TN
- Department of Bioengineering and Organic Chemistry, Tomsk Polytechnic University, Tomsk, Russia
| | - Qiufang Cheng
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University, Nashville, TN
| | - Yipeng Geng
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University, Nashville, TN
| | - Ingrid M. Verhamme
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University, Nashville, TN
| | - Obi Umunakwe
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University, Nashville, TN
| | - Erik I. Tucker
- Department of Biomedical Engineering, Oregon Health and Science University, Portland, OR
| | - Mao-fu Sun
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University, Nashville, TN
| | - Vladimir Serebrov
- Department of Biochemistry and Molecular Biology, Siberian State Medical University, Tomsk, Russia
| | - Andras Gruber
- Department of Biomedical Engineering, Oregon Health and Science University, Portland, OR
| | - David Gailani
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University, Nashville, TN
- Department of Medicine, Vanderbilt University, Nashville, TN
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24
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Geng Y, Verhamme IM, Smith SA, Cheng Q, Sun MF, Sheehan JP, Morrissey JH, Gailani D. Factor XI anion-binding sites are required for productive interactions with polyphosphate. J Thromb Haemost 2013; 11:2020-8. [PMID: 24118982 PMCID: PMC3865764 DOI: 10.1111/jth.12414] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2013] [Accepted: 09/16/2013] [Indexed: 10/26/2022]
Abstract
BACKGROUND Conversion of factor XI (FXI) to FXIa is enhanced by polymers of inorganic phosphate (polyP). This process requires FXI to bind to polyP. Each FXIa subunit contains anion-binding sites (ABSs) on the apple 3 (A3) and catalytic domains that are required for normal heparin-mediated enhancement of FXIa inhibition by antithrombin. AIMS To determine the importance of FXI ABSs to polyP enhancement of FXI activation. METHODS Recombinant FXI variants lacking one or both ABSs were tested in polyP-dependent purified protein systems, plasma clotting assays, and a murine thrombosis model. RESULTS In the presence of polyP, activation rates for FXI lacking either ABS were reduced compared with wild-type FXI, and FXI lacking both sites had an even greater defect. In contrast to heparin, polyP binding to FXIa did not enhance inhibition by antithrombin and did not interfere with FXIa activation of FIX. FXI lacking one or both ABSs does not reconstitute FXI-deficient plasma as well as wild-type FXI when polyP was used to initiate coagulation. In FXI-deficient mice, FXI lacking one or more ABSs was inferior to wild-type FXI in supporting arterial thrombus formation. CONCLUSIONS The ABSs on FXIa that are required for expression of heparin's cofactor activity during protease inhibition by antithrombin are also required for expression of polyP cofactor activity during FXI activation. These sites may contribute to FXI-dependent thrombotic processes.
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Affiliation(s)
- Yipeng Geng
- Department of Pathology, Microbiology and Immunology, Vanderbilt University, Nashville, TN
| | - Ingrid M. Verhamme
- Department of Pathology, Microbiology and Immunology, Vanderbilt University, Nashville, TN
| | | | - Qiufang Cheng
- Department of Pathology, Microbiology and Immunology, Vanderbilt University, Nashville, TN
| | - Mao-fu Sun
- Department of Pathology, Microbiology and Immunology, Vanderbilt University, Nashville, TN
| | - John P. Sheehan
- Department of Medicine, University of Wisconsin, Madison, WI
| | | | - David Gailani
- Department of Pathology, Microbiology and Immunology, Vanderbilt University, Nashville, TN
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25
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Geng Y, Verhamme IM, Sun MF, Bajaj SP, Emsley J, Gailani D. Analysis of the factor XI variant Arg184Gly suggests a structural basis for factor IX binding to factor XIa. J Thromb Haemost 2013; 11:1374-84. [PMID: 23617568 PMCID: PMC4158700 DOI: 10.1111/jth.12275] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2013] [Accepted: 04/03/2013] [Indexed: 12/01/2022]
Abstract
BACKGROUND A patient with factor XI (FXI) deficiency was reported with an Arg184Gly substitution in the FXI A3 domain. The A3 domain contains an exosite required for binding of FIX to activated FXI (FXIa). OBJECTIVE To test the effects of the Arg184Gly substitution on FIX activation, and to characterize the FIX-binding site on FXIa. METHODS Recombinant FXIa and FIX variants were used to identify residues involved in FIX activation by FXIa. Analysis of the FXI structure was used to identify potential FIX-binding sites. RESULTS The Km for FIX activation by FXIa-Gly184 was approximately three-fold higher than for FXIa, suggesting that Arg184 is part of the exosite. Arg184 and the adjacent residues, Ile183 and Asp185, contribute to charged and hydrophobic areas that are not present in the FXI homolog prekallikrein (PK). Replacing residues 183-185 with alanine abolished exosite activity, similarly to replacement of the entire A3 domain with the A3 domain from PK (FXIa/PKA3). Reintroducing FXI residues 183-185 into FXIa/PKA3 partially restored the exosite, and replacing residues 183-185 and 260-264 completely restored exosite function. FIX in which the Ω-loop (residues 4-11) was replaced with the FVII Ω-loop was activated poorly by FXIa, suggesting that the FIX Ω-loop binds to FXIa. CONCLUSIONS The results support a model in which the Ω-loop of FIX binds to an area on FXIa composed of residues from the N-terminus and C-terminus of the A3 domain. These residues are buried in zymogen FXI, and must be exposed upon conversion to FXIa to permit FIX binding.
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Affiliation(s)
- Y Geng
- Department of Pathology, Microbiology and Immunology, Vanderbilt University, Nashville, TN, USA
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