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Terada R, Johnson PM, Butt AL, Mishima Y, Stewart KE, Levy JH, Tanaka KA. In vitro effects of Gla-domainless factor Xa analog on procoagulant and fibrinolytic pathways in apixaban-treated plasma and whole blood. Thromb Res 2023; 230:119-125. [PMID: 37713998 DOI: 10.1016/j.thromres.2023.08.018] [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: 07/12/2023] [Revised: 08/28/2023] [Accepted: 08/31/2023] [Indexed: 09/17/2023]
Abstract
BACKGROUND Andexanet alfa is a Gla-domainless FXa (GDXa) analog used as an antidote to FXa inhibitors. Despite its clinical use, laboratory monitoring for anti-Xa reversal and the effect of andexanet on fibrinolysis has not been explored. We used a GDXa with a serine-to-alanine mutation at position 195 (chymotrypsin numbering) to model the interaction between andexanet and apixaban. METHODS Six batches of pooled plasma, and whole blood from healthy volunteers were treated with increasing concentrations of apixaban with/without GDXa. Thrombin generation and plasmin generation (TG and PG) were tested in plasma, and whole blood thrombus formation was tested using thromboelastometry or a flow-chamber system. FXa was also tested in isolation for its ability to support plasmin activation with/without apixaban and GDXa. RESULTS Apixaban (250-800 nM) concentration-dependently decreased the velocity and peak of TG in plasma. Apixaban prolonged the onset of thrombus formation in thromboelastometry and flow-chamber tests. GDXa normalized apixaban-induced delays in TG and whole blood thrombus formation. However, GDXa minimally affected the low PG velocity and peak caused by apixaban at higher concentrations (500-800 nM). FXa promoted plasmin generation independent of fibrin that was inhibited by apixaban at supratherapeutic concentrations. CONCLUSIONS This study demonstrated the feasibility of assessing coagulation lag time recovery in plasma and whole blood following in vitro apixaban reversal using GDXa, a biosimilar to andexanet. In contrast, GDXa-induced changes in plasmin generation and fibrinolysis were limited in PG and tPA-added ROTEM assays, supporting the endogenous profibrinolytic activity of FXa and its inhibition at elevated apixaban concentrations.
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Affiliation(s)
- Rui Terada
- Department of Anesthesiology, University of Oklahoma Health Science Center, Oklahoma City, OK, United States of America
| | - Penny M Johnson
- Department of Anesthesiology, University of Oklahoma Health Science Center, Oklahoma City, OK, United States of America
| | - Amir L Butt
- Department of Anesthesiology, University of Oklahoma Health Science Center, Oklahoma City, OK, United States of America
| | - Yuko Mishima
- Department of Anesthesiology, University of Oklahoma Health Science Center, Oklahoma City, OK, United States of America
| | - Kenneth E Stewart
- Department of Anesthesiology, University of Oklahoma Health Science Center, Oklahoma City, OK, United States of America; Department of Surgery, University of Oklahoma Health Science Center, Oklahoma City, OK, United States of America
| | - Jerold H Levy
- Department of Anesthesiology, Critical Care, and Surgery (Cardiothoracic), Duke University Medical Center, Durham, NC, United States of America
| | - Kenichi A Tanaka
- Department of Anesthesiology, University of Oklahoma Health Science Center, Oklahoma City, OK, United States of America.
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Bonde AC, Lund J, Hansen JJ, Winther JR, Nielsen PF, Zahn S, Tiainen P, Olsen OH, Petersen HH, Bjelke JR. The functional role of the autolysis loop in the regulation of factor X upon hemostatic response. J Thromb Haemost 2022; 20:589-599. [PMID: 34927362 DOI: 10.1111/jth.15624] [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: 11/03/2021] [Accepted: 12/16/2021] [Indexed: 11/26/2022]
Abstract
BACKGROUND The regulation of factor X (FX) is critical to maintain the balance between blood coagulation and fluidity. OBJECTIVES To functionally characterize the role of the FX autolysis loop in the regulation of the zymogen and active form of FX. METHODS We introduced novel N-linked glycosylations on the surface-exposed loop spanning residues 143-150 (chymotrypsin numbering) of FX. The activity and inhibition of recombinant FX variants was quantified in pure component assays. The in vitro thrombin generation potential of the FX variants was evaluated in FX-depleted plasma. RESULTS The factor VIIa (FVIIa)-mediated activation and prothrombin activation was reduced, presumably through steric hinderance. Prothrombin activation was, however, recovered in presence of cofactor factor Va (FVa) despite a reduced prothrombinase assembly. The introduced N-glycans exhibited position-specific effects on the interaction with two FXa inhibitors: tissue factor pathway inhibitor (TFPI) and antithrombin (ATIII). Ki for the inhibition by full-length TFPI of these FXa variants was increased by 7- to 1150-fold, whereas ATIII inhibition in the presence of the heparin-analog Fondaparinux was modestly increased by 2- to 15-fold compared with wild-type. When supplemented in zymogen form, the FX variants exhibited reduced thrombin generation activity relative to wild-type FX, whereas enhanced procoagulant activity was measured for activated FXa variants. CONCLUSION The autolysis loop participates in all aspects of FX regulation. In plasma-based assays, a modest decrease in FX activation rate appeared to knock down the procoagulant response even when down regulation of FXa activity by inhibitors was reduced.
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Affiliation(s)
- Amalie Carnbring Bonde
- Global Research, Novo Nordisk A/S, Måløv, Denmark
- Section for Biomolecular Sciences, Department of Biology, University of Copenhagen, Copenhagen N, Denmark
| | - Jacob Lund
- Global Research, Novo Nordisk A/S, Måløv, Denmark
| | | | - Jakob Rahr Winther
- Section for Biomolecular Sciences, Department of Biology, University of Copenhagen, Copenhagen N, Denmark
| | | | - Stefan Zahn
- Global Research, Novo Nordisk A/S, Måløv, Denmark
| | | | - Ole Hvilsted Olsen
- Novo Nordisk Foundation Centre for Basic Metabolic Research, University of Copenhagen, Copenhagen N, Denmark
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Schmidt AE, Vadivel K, Whitelegge J, Bajaj SP. Plasmin-mediated proteolysis of human factor IXa in the presence of calcium/phospholipid: Conversion of procoagulant factor IXa to a fibrinolytic enhancer. J Thromb Haemost 2020; 18:1171-1182. [PMID: 32073726 PMCID: PMC7363452 DOI: 10.1111/jth.14773] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Revised: 01/28/2020] [Accepted: 02/18/2020] [Indexed: 11/30/2022]
Abstract
BACKGROUND Factor (F) IX/IXa inactivation by plasmin has been studied; however, whether plasmin converts FIXa to a fibrinolytic enhancer is not known. OBJECTIVE Investigate plasmin proteolysis site(s) in FIXa that inactivates and transforms it into a fibrinolytic enhancer. METHODS NH2 -terminal sequencing, mass spectrometry analysis, and functional assays. RESULTS Plasmin in the presence of Ca2+ /phospholipid (PL) rapidly cleaved FIXaβ at Lys316↓Gly317 to yield FIXaγ followed by a slow cleavage at Lys413↓Leu414 to yield FIXaδ. FIXaγ/FIXaδ migrated indistinguishably from FIXaβ in nondenaturing gel system indicating that C-terminal residues 317-415/317-413 of heavy chain remain noncovalently associated with FIXaγ/FIXaδ. However, as compared with FIXaβ, FIXaγ or FIXaγ/FIXaδ (25-75 mixture, 8-hour/24-hour incubation analysis by mass spectrometry) was impaired ~ 10-fold in hydrolyzing synthetic substrate CBS 31.39 (CH3-SO2-D-Leu-Gly-Arg-pNA), ~ 30-fold (~ 5-fold higher Km , ~ 6-fold lower kcat ) in activating FX in a system containing Ca2+ /PL, and ~ 650-fold in a system containing Ca2+ /PL and FVIIIa. Further, FIXaγ or FIXaγ/FIXaδ bound FVIIIa with ~ 60-fold reduced affinity compared with FIXaβ. Additionally, in ligand blots, plasminogen or diisopropylfluorophosphate-inhibited plasmin (DIP-plasmin) bound FIXaγ and FIXaδ but not FIXaβ. This interaction was prevented by ε-aminocaproic acid or carboxypeptidase B treatment suggesting that plasminogen/DIP-plasmin binds to FIXaγ/FIXaδ through newly generated C-terminal Lys316 and Lys413. Importantly, FIXaγ/FIXaδ mixture but not FIXaγ enhanced tissue plasminogen activator (tPA)-mediated plasminogen activation in a concentration dependent manner. Similarly, FIXaγ/FIXaδ mixture but not FIXaγ enhanced tPA-induced clot lysis in FIX-depleted plasma. CONCLUSION Plasmin cleavage at Lys316↓Gly317 abrogates FIXaβ coagulant activity, whereas additional cleavage at Lys413↓Leu414 converts it into a fibrinolytic enhancer.
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Affiliation(s)
- Amy E. Schmidt
- Department of Orthopedic Surgery, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA
| | - Kanagasabai Vadivel
- Department of Orthopedic Surgery, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA
| | - Julian Whitelegge
- The Pasarow Mass Spectrometry Laboratory, The Jane and Terry Semel Institute for Neuroscience and Human Behavior, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA
| | - S. Paul Bajaj
- Department of Orthopedic Surgery, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA
- Molecular Biology Institute, University of California, Los Angeles, CA 90095, USA
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Grinenko T, Yusova О, Revka O, Patalakh I, Yatsenko T. Fibrinolysis regulation by platelets retaining plasminogen and tissue-type plasminogen activator on their surface. UKRAINIAN BIOCHEMICAL JOURNAL 2019. [DOI: 10.15407/ubj91.06.038] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
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Goettig P, Brandstetter H, Magdolen V. Surface loops of trypsin-like serine proteases as determinants of function. Biochimie 2019; 166:52-76. [PMID: 31505212 PMCID: PMC7615277 DOI: 10.1016/j.biochi.2019.09.004] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Accepted: 09/06/2019] [Indexed: 02/07/2023]
Abstract
Trypsin and chymotrypsin-like serine proteases from family S1 (clan PA) constitute the largest protease group in humans and more generally in vertebrates. The prototypes chymotrypsin, trypsin and elastase represent simple digestive proteases in the gut, where they cleave nearly any protein. Multidomain trypsin-like proteases are key players in the tightly controlled blood coagulation and complement systems, as well as related proteases that are secreted from diverse immune cells. Some serine proteases are expressed in nearly all tissues and fluids of the human body, such as the human kallikreins and kallikrein-related peptidases with specialization for often unique substrates and accurate timing of activity. HtrA and membrane-anchored serine proteases fulfill important physiological tasks with emerging roles in cancer. The high diversity of all family members, which share the tandem β-barrel architecture of the chymotrypsin-fold in the catalytic domain, is conferred by the large differences of eight surface loops, surrounding the active site. The length of these loops alters with insertions and deletions, resulting in remarkably different three-dimensional arrangements. In addition, metal binding sites for Na+, Ca2+ and Zn2+ serve as regulatory elements, as do N-glycosylation sites. Depending on the individual tasks of the protease, the surface loops determine substrate specificity, control the turnover and allow regulation of activation, activity and degradation by other proteins, which are often serine proteases themselves. Most intriguingly, in some serine proteases, the surface loops interact as allosteric network, partially tuned by protein co-factors. Knowledge of these subtle and complicated molecular motions may allow nowadays for new and specific pharmaceutical or medical approaches.
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Affiliation(s)
- Peter Goettig
- Division of Structural Biology, Department of Biosciences, University of Salzburg, Billrothstrasse 11, 5020, Salzburg, Austria.
| | - Hans Brandstetter
- Division of Structural Biology, Department of Biosciences, University of Salzburg, Billrothstrasse 11, 5020, Salzburg, Austria
| | - Viktor Magdolen
- Clinical Research Unit, Department of Obstetrics and Gynecology, School of Medicine, Technical University of Munich, Ismaninger Strasse 22, 81675, München, Germany
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Carter RLR, Talbot K, Hur WS, Meixner SC, Van Der Gugten JG, Holmes DT, Côté HCF, Kastrup CJ, Smith TW, Lee AYY, Pryzdial ELG. Rivaroxaban and apixaban induce clotting factor Xa fibrinolytic activity. J Thromb Haemost 2018; 16:2276-2288. [PMID: 30176116 DOI: 10.1111/jth.14281] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Indexed: 12/26/2022]
Abstract
Essentials Activated clotting factor X (FXa) acquires fibrinolytic cofactor function after cleavage by plasmin. FXa-mediated plasma fibrinolysis is enabled by active site modification blocking a second cleavage. FXa-directed oral anticoagulants (DOACs) alter FXa cleavage by plasmin. DOACs enhance FX-dependent fibrinolysis and plasmin generation by tissue plasminogen activator. BACKGROUND When bound to an anionic phospholipid-containing membrane, activated clotting factor X (FXa) is sequentially cleaved by plasmin from the intact form, FXaα, to FXaβ and then to Xa33/13. Tissue-type plasminogen activator (t-PA) produces plasmin and is the initiator of fibrinolysis. Both FXaβ and Xa33/13 enhance t-PA-mediated plasminogen activation. Although stable in experiments using purified proteins, Xa33/13 rapidly loses t-PA cofactor function in plasma. Bypassing this inhibition, covalent modification of the FXaα active site prevents Xa33/13 formation by plasmin, and the persistent FXaβ enhances plasma fibrinolysis. As the direct oral anticoagulants (DOACs) rivaroxaban and apixaban bind to the FXa active site, we hypothesized that they similarly modulate FXa fibrinolytic function. METHODS DOAC effects on fibrinolysis and the t-PA cofactor function of FXa were studied in patient plasma, normal pooled plasma and purified protein experiments by the use of light scattering, chromogenic assays, and immunoblots. RESULTS The plasma of patients taking rivaroxaban showed enhanced fibrinolysis correlating with FXaβ. In normal pooled plasma, the addition of rivaroxaban or apixaban also shortened fibrinolysis times. This was related to the cleavage product, FXaβ, which increased plasmin production by t-PA. It was confirmed that these results were not caused by DOACs affecting activated FXIII-mediated fibrin crosslinking, clot ultrastructure and thrombin-activatable fibrinolysis inhibitor activation in plasma. CONCLUSION The current study suggests a previously unknown effect of DOACs on FXa in addition to their well-documented anticoagulant role. By enabling the t-PA cofactor function of FXaβ in plasma, DOACs also enhance fibrinolysis. This effect may broaden their therapeutic indications.
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Affiliation(s)
- R L R Carter
- Centre for Blood Research, University of British Columbia, Vancouver, British Columbia, Canada
- Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, British Columbia, Canada
| | - K Talbot
- Centre for Blood Research, University of British Columbia, Vancouver, British Columbia, Canada
- Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, British Columbia, Canada
- Centre for Innovation, Canadian Blood Services, Ottawa, Ontario, Canada
| | - W S Hur
- Centre for Blood Research, University of British Columbia, Vancouver, British Columbia, Canada
- Michael Smith Laboratories and Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia, Canada
| | - S C Meixner
- Centre for Blood Research, University of British Columbia, Vancouver, British Columbia, Canada
- Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, British Columbia, Canada
- Centre for Innovation, Canadian Blood Services, Ottawa, Ontario, Canada
| | - J G Van Der Gugten
- Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, British Columbia, Canada
- Department of Pathology and Laboratory Medicine, St Paul's Hospital, Vancouver, British Columbia
| | - D T Holmes
- Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, British Columbia, Canada
- Department of Pathology and Laboratory Medicine, St Paul's Hospital, Vancouver, British Columbia
| | - H C F Côté
- Centre for Blood Research, University of British Columbia, Vancouver, British Columbia, Canada
- Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, British Columbia, Canada
| | - C J Kastrup
- Centre for Blood Research, University of British Columbia, Vancouver, British Columbia, Canada
- Michael Smith Laboratories and Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia, Canada
| | - T W Smith
- Centre for Blood Research, University of British Columbia, Vancouver, British Columbia, Canada
- Division of Hematology, Department of Medicine, University of British Columbia, Vancouver, British Columbia, Canada
| | - A Y Y Lee
- Centre for Blood Research, University of British Columbia, Vancouver, British Columbia, Canada
- Division of Hematology, Department of Medicine, University of British Columbia, Vancouver, British Columbia, Canada
| | - E L G Pryzdial
- Centre for Blood Research, University of British Columbia, Vancouver, British Columbia, Canada
- Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, British Columbia, Canada
- Centre for Innovation, Canadian Blood Services, Ottawa, Ontario, Canada
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7
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Minsky BB, Abzalimov RR, Niu C, Zhao Y, Kirsch Z, Dubin PL, Savinov SN, Kaltashov IA. Mass Spectrometry Reveals a Multifaceted Role of Glycosaminoglycan Chains in Factor Xa Inactivation by Antithrombin. Biochemistry 2018; 57:4880-4890. [PMID: 29999301 DOI: 10.1021/acs.biochem.8b00199] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Factor Xa (fXa) inhibition by antithrombin (AT) enabled by heparin or heparan sulfate is critical for controlling blood coagulation. AT activation by heparin has been investigated extensively, while interaction of heparin with trapped AT/fXa intermediates has received relatively little attention. We use native electrospray ionization mass spectrometry to study the role of heparin chains of varying length [hexa-, octa-, deca-, and eicosasaccharides (dp6, dp8, dp10, and dp20, respectively)] in AT/fXa complex assembly. Despite being critical promoters of AT/Xa binding, shorter heparin chains are excluded from the final products (trapped intermediates). However, replacement of short heparin segments with dp20 gives rise to a prominent ionic signal of ternary complexes. These species are also observed when the trapped intermediate is initially prepared in the presence of a short oligoheparin (dp6), followed by addition of a longer heparin chain (dp20), indicating that binding of heparin to AT/fXa complexes takes place after the inhibition event. The importance of the heparin chain length for its ability to associate with the trapped intermediate suggests that the binding likely occurs in a bidentate fashion (where two distinct segments of oligoheparin make contacts with the protein components, while the part of the chain separating these two segments is extended into solution to minimize electrostatic repulsion). This model is corroborated by both molecular dynamics simulations with an explicit solvent and ion mobility measurements in the gas phase. The observed post-inhibition binding of heparin to the trapped AT/fXa intermediates hints at the likely role played by heparan sulfate in their catabolism.
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Schuliga M, Grainge C, Westall G, Knight D. The fibrogenic actions of the coagulant and plasminogen activation systems in pulmonary fibrosis. Int J Biochem Cell Biol 2018; 97:108-117. [PMID: 29474926 DOI: 10.1016/j.biocel.2018.02.016] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Revised: 02/16/2018] [Accepted: 02/19/2018] [Indexed: 12/27/2022]
Abstract
Fibrosis causes irreversible damage to lung structure and function in restrictive lung diseases such as idiopathic pulmonary fibrosis (IPF). Extravascular coagulation involving fibrin formation in the intra-alveolar compartment is postulated to have a pivotal role in the development of pulmonary fibrosis, serving as a provisional matrix for migrating fibroblasts. Furthermore, proteases of the coagulation and plasminogen activation (plasminergic) systems that form and breakdown fibrin respectively directly contribute to pulmonary fibrosis. The coagulants, thrombin and factor Xa (FXa) evoke fibrogenic effects via cleavage of the N-terminus of protease-activated receptors (PARs). Whilst the formation and activity of plasmin, the principle plasminergic mediator is suppressed in the airspaces of patients with IPF, localized increases are likely to occur in the lung interstitium. Plasmin-evoked proteolytic activation of factor XII (FXII), matrix metalloproteases (MMPs) and latent, matrix-bound growth factors such as epidermal growth factor (EGF) indirectly implicate plasmin in pulmonary fibrosis. Another plasminergic protease, urokinase plasminogen activator (uPA) is associated with regions of fibrosis in the remodelled lung of IPF patients and elicits fibrogenic activity via binding its receptor (uPAR). Plasminogen activator inhibitor-1 (PAI-1) formed in the injured alveolar epithelium also contributes to pulmonary fibrosis in a manner that involves vitronectin binding. This review describes the mechanisms by which components of the two systems primarily involved in fibrin homeostasis contribute to interstitial fibrosis, with a particular focus on IPF. Selectively targeting the receptor-mediated mechanisms of coagulant and plasminergic proteases may limit pulmonary fibrosis, without the bleeding complications associated with conventional anti-coagulant and thrombolytic therapies.
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Affiliation(s)
- Michael Schuliga
- School of Biomedical Sciences and Pharmacy, University of Newcastle, Callaghan, New South Wales, Australia; Priority Research Centre for Healthy Lungs, Hunter Medical Research Institute, New Lambton Heights, New South Wales, Australia.
| | - Christopher Grainge
- Priority Research Centre for Healthy Lungs, Hunter Medical Research Institute, New Lambton Heights, New South Wales, Australia; School of Medicine and Public Health, University of Newcastle, Callaghan, New South Wales, Australia
| | - Glen Westall
- Allergy, Immunology and Respiratory Medicine, Alfred Hospital, Prahran, Victoria, Australia
| | - Darryl Knight
- School of Biomedical Sciences and Pharmacy, University of Newcastle, Callaghan, New South Wales, Australia; Priority Research Centre for Healthy Lungs, Hunter Medical Research Institute, New Lambton Heights, New South Wales, Australia; Department of Anesthesiology, Pharmacology and Therapeutics, University of British Columbia, Canada
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Pryzdial ELG, Meixner SC, Talbot K, Eltringham-Smith LJ, Baylis JR, Lee FMH, Kastrup CJ, Sheffield WP. Thrombolysis by chemically modified coagulation factor Xa. J Thromb Haemost 2016; 14:1844-54. [PMID: 27359348 PMCID: PMC5576980 DOI: 10.1111/jth.13402] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2015] [Accepted: 06/15/2016] [Indexed: 12/22/2022]
Abstract
UNLABELLED Essentials Factor Xa (FXa) acquires cleavage-mediated tissue plasminogen activator (tPA) cofactor activity. Recombinant (r) tPA is the predominant thrombolytic drug, but it may cause systemic side effects. Chemically modified, non-enzymatic FXa was produced (Xai-K), which rapidly lysed thrombi in mice. Unlike rtPA, Xai-K had no systemic fibrinolysis activation markers, indicating improved safety. SUMMARY Background Enzymatic thrombolysis carries the risk of hemorrhage and re-occlusion must be evaded by co-administration with an anticoagulant. Toward further improving these shortcomings, we report a novel dual-functioning molecule, Xai-K, which is both a non-enzymatic thrombolytic agent and an anticoagulant. Xai-K is based on clotting factor Xa, whose sequential plasmin-mediated fragments, FXaβ and Xa33/13, accelerate the principal thrombolytic agent, tissue plasminogen activator (tPA), but only when localized to anionic phospholipid. Methods The effect of Xai-K on fibrinolysis was measured in vitro by turbidity, thromboelastography and chromogenic assays, and measured in a murine model of occlusive carotid thrombosis by Doppler ultrasound. The anticoagulant properties of Xai-K were evaluated by normal plasma clotting assays, and in murine liver laceration and tail amputation hemostatic models. Results Xa33/13, which participates in fibrinolysis of purified fibrin, was rapidly inhibited in plasma. Cleavage was blocked at FXaβ by modifying residues at the active site. The resultant Xai-K (1 nm) enhanced plasma clot dissolution by ~7-fold in vitro and was dependent on tPA. Xai-K alone (2.0 μg g(-1) body weight) achieved therapeutic patency in mice. The minimum primary dose of the tPA variant, Tenecteplase (TNK; 17 μg g(-1) ), could be reduced by > 30-fold to restore blood flow with adjunctive Xai-K (0.5 μg g(-1) ). TNK-induced systemic markers of fibrinolysis were not detected with Xai-K (2.0 μg g(-1) ). Xai-K had anticoagulant activity that was somewhat attenuated compared with a previously reported analogue. Conclusion These results suggest that Xai-K may ameliorate the safety profile of therapeutic thrombolysis, either as a primary or tPA/TNK-adjunctive agent.
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Affiliation(s)
- E L G Pryzdial
- Centre for Blood Research and Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC, Canada.
- Centre for Innovation, Canadian Blood Services, Ottawa, ON, Canada.
| | - S C Meixner
- Centre for Blood Research and Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC, Canada
- Centre for Innovation, Canadian Blood Services, Ottawa, ON, Canada
| | - K Talbot
- Centre for Blood Research and Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC, Canada
- Centre for Innovation, Canadian Blood Services, Ottawa, ON, Canada
| | - L J Eltringham-Smith
- Centre for Innovation, Canadian Blood Services, Ottawa, ON, Canada
- Department of Pathology and Molecular Medicine, McMaster University, Hamilton, ON, Canada
| | - J R Baylis
- Centre for Blood Research and Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC, Canada
- Michael Smith Laboratories and Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC, Canada
| | - F M H Lee
- Centre for Blood Research and Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC, Canada
- Centre for Innovation, Canadian Blood Services, Ottawa, ON, Canada
| | - C J Kastrup
- Centre for Blood Research and Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC, Canada
- Michael Smith Laboratories and Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC, Canada
| | - W P Sheffield
- Centre for Innovation, Canadian Blood Services, Ottawa, ON, Canada
- Department of Pathology and Molecular Medicine, McMaster University, Hamilton, ON, Canada
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10
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The inflammatory actions of coagulant and fibrinolytic proteases in disease. Mediators Inflamm 2015; 2015:437695. [PMID: 25878399 PMCID: PMC4387953 DOI: 10.1155/2015/437695] [Citation(s) in RCA: 68] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2014] [Revised: 03/02/2015] [Accepted: 03/16/2015] [Indexed: 12/30/2022] Open
Abstract
Aside from their role in hemostasis, coagulant and fibrinolytic proteases are important mediators of inflammation in diseases such as asthma, atherosclerosis, rheumatoid arthritis, and cancer. The blood circulating zymogens of these proteases enter damaged tissue as a consequence of vascular leak or rupture to become activated and contribute to extravascular coagulation or fibrinolysis. The coagulants, factor Xa (FXa), factor VIIa (FVIIa), tissue factor, and thrombin, also evoke cell-mediated actions on structural cells (e.g., fibroblasts and smooth muscle cells) or inflammatory cells (e.g., macrophages) via the proteolytic activation of protease-activated receptors (PARs). Plasmin, the principle enzymatic mediator of fibrinolysis, also forms toll-like receptor-4 (TLR-4) activating fibrin degradation products (FDPs) and can release latent-matrix bound growth factors such as transforming growth factor-β (TGF-β). Furthermore, the proteases that convert plasminogen into plasmin (e.g., urokinase plasminogen activator) evoke plasmin-independent proinflammatory actions involving coreceptor activation. Selectively targeting the receptor-mediated actions of hemostatic proteases is a strategy that may be used to treat inflammatory disease without the bleeding complications of conventional anticoagulant therapies. The mechanisms by which proteases of the coagulant and fibrinolytic systems contribute to extravascular inflammation in disease will be considered in this review.
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11
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Talbot K, Meixner SC, Pryzdial EL. Proteolytic modulation of factor Xa–antithrombin complex enhances fibrinolysis in plasma. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2013; 1834:989-95. [DOI: 10.1016/j.bbapap.2013.02.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2012] [Revised: 01/31/2013] [Accepted: 02/05/2013] [Indexed: 10/27/2022]
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12
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A specific antidote for reversal of anticoagulation by direct and indirect inhibitors of coagulation factor Xa. Nat Med 2013; 19:446-51. [PMID: 23455714 DOI: 10.1038/nm.3102] [Citation(s) in RCA: 520] [Impact Index Per Article: 47.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2012] [Accepted: 01/23/2013] [Indexed: 11/09/2022]
Abstract
Inhibitors of coagulation factor Xa (fXa) have emerged as a new class of antithrombotics but lack effective antidotes for patients experiencing serious bleeding. We designed and expressed a modified form of fXa as an antidote for fXa inhibitors. This recombinant protein (r-Antidote, PRT064445) is catalytically inactive and lacks the membrane-binding γ-carboxyglutamic acid domain of native fXa but retains the ability of native fXa to bind direct fXa inhibitors as well as low molecular weight heparin-activated antithrombin III (ATIII). r-Antidote dose-dependently reversed the inhibition of fXa by direct fXa inhibitors and corrected the prolongation of ex vivo clotting times by such inhibitors. In rabbits treated with the direct fXa inhibitor rivaroxaban, r-Antidote restored hemostasis in a liver laceration model. The effect of r-Antidote was mediated by reducing plasma anti-fXa activity and the non-protein bound fraction of the fXa inhibitor in plasma. In rats, r-Antidote administration dose-dependently and completely corrected increases in blood loss resulting from ATIII-dependent anticoagulation by enoxaparin or fondaparinux. r-Antidote has the potential to be used as a universal antidote for a broad range of fXa inhibitors.
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13
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Protamine sulfate stimulates degradation of factor Xa and the factor Xa–antithrombin complex. Blood Coagul Fibrinolysis 2011; 22:247-53. [DOI: 10.1097/mbc.0b013e328343f93f] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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14
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Abstract
The coagulation and fibrinolytic pathways regulate hemostasis and thrombosis, and an imbalance in these pathways may result in pathologic hemophilia or thrombosis. The plasminogen system is the primary proteolytic pathway for fibrinolysis, but also has important proteolytic functions in cell migration, extracellular matrix degradation, metalloproteinase activation, and hormone processing. Several studies have demonstrated plasmin cleavage and inactivation of several coagulation factors, suggesting plasmin may be not only be the primary fibrinolytic enzyme, but may have anticoagulant properties as well. The objective of this review is to examine both in vitro and in vivo evidence for plasmin inactivation of coagulation, and to consider whether plasmin may act as a physiological regulator of coagulation. While several studies have demonstrated strong evidence for plasmin cleavage and inactivation of coagulation factors FV, FVIII, FIX, and FX in vitro, in vivo evidence is lacking for a physiologic role for plasmin as an anticoagulant. However, inactivation of coagulation factors by plasmin may be useful as a localized anticoagulant therapy or as a combined thrombolytic and anticoagulant therapy.
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Affiliation(s)
- Jane Hoover-Plow
- Joseph J Jacobs Center for Thrombosis and Vascular Biology, Department of Cardiovascular Medicine, Lerner Research Institute Cleveland Clinic, Cleveland, Ohio 44195, USA.
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15
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Enhanced fibrinolysis by proteolysed coagulation factor Xa. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2009; 1804:723-30. [PMID: 19931652 DOI: 10.1016/j.bbapap.2009.11.011] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2009] [Revised: 10/23/2009] [Accepted: 11/12/2009] [Indexed: 11/24/2022]
Abstract
We previously showed that coagulation factor Xa (FXa) enhances activation of the fibrinolysis zymogen plasminogen to plasmin by tissue plasminogen activator (tPA). Implying that proteolytic modulation occurs in situ, intact FXa (FXaalpha) must be sequentially cleaved by plasmin or autoproteolysis, producing FXabeta and Xa33/13, which acquire necessary plasminogen binding sites. The implicit function of Xa33/13 in plasmin generation has not been demonstrated, nor has FXaalpha/beta or Xa33/13 been studied in clot lysis experiments. We now report that purified Xa33/13 increases tPA-dependent plasmin generation by at least 10-fold. Western blots confirmed that in situ conversion of FXaalpha/beta to Xa33/13 correlated to enhanced plasmin generation. Chemical modification of the FXaalpha active site resulted in the proteolytic generation of a product distinct from Xa33/13 and inhibited the enhancement of plasminogen activation. Identical modification of Xa33/13 had no effect on tPA cofactor function. Due to its overwhelming concentration in the clot, fibrin is the accepted tPA cofactor. Nevertheless, at the functional level of tPA that circulates in plasma, FXaalpha/beta or Xa33/13 greatly reduced purified fibrin lysis times by as much as 7-fold. This effect was attenuated at high levels of tPA, suggesting a role when intrinsic plasmin generation is relatively low. FXaalpha/beta or Xa33/13 did not alter the apparent size of fibrin degradation products, but accelerated the initial cleavage of fibrin to fragment X, which is known to optimize the tPA cofactor activity of fibrin. Thus, coagulation FXaalpha undergoes proteolytic modulation to enhance fibrinolysis, possibly by priming the tPA cofactor function of fibrin.
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16
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Comparative effects of atrial polypeptide and neurohormone C on the interaction of factor Xa with antithrombin III. Blood Coagul Fibrinolysis 2008; 19:645-51. [PMID: 18832904 DOI: 10.1097/mbc.0b013e328305094f] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The effects of atrial polypeptide and neurohormone C upon the interaction of human factor Xa (FXa) and human antithrombin III (ATIII) were followed by sodium dodecyl sulfate polyacrylamide gel electrophoresis. A pattern of bands consisting of a 1 degree duplex complex (FXaalpha-ATIII band of 109 kDa, FXabeta-ATIII band of 104 kDa), a 2 degree duplex complex (alpha band of 99 kDa, beta band of 95 kDa), a 3 degree duplex complex (alpha band of 66 kDa, beta band of 62 kDa), modified ATIII (ATIIIM, 58 kDa), native ATIII (55 kDa), FXaalpha (52 kDa), FXabeta (47 kDa), and a FXa degradation product (FXagamma, 35 kDa) was detected and quantitated. Preincubation of FXa, ATIII, or mixtures thereof with atrial polypeptide produced a shift from FXaalpha-ATIII to FXabeta-ATIII complexes and increases in both ATIIIM and FXagamma, reflecting degradation of the 1 degree and 2 degree complex to form the 3 degree complex. Atrial polypeptide appeared to promote FXa-ATIII complex formation when preincubated with ATIII, or when added within 1 min to FXa/ATIII mixtures. However, when atrial polypeptide was preincubated with FXa, inhibition of the 1 degree complex formation was suggested. Upon incubation of FXa, ATIII, or mixtures thereof with neurohormone C, there was an increase in total complex formation, a decrease in ATIIIM, a decrease in FXagamma, and little change in the ratio of free FXaalpha to FXabeta, or the ratio of FXaalpha-ATIII to FXabeta-ATIII complexes. Therefore, neurohormone C may act to suppress hydrolysis or proteolytic actions of excess FXa on FXa-ATIII complexes, or autolytic activity of FXa, to the level of FXagamma via an, as yet, unknown mechanism. Additionally, neurohormone C retards the hydrolysis of the FXa-ATIII complexes which form free FXa and ATIIIM. Hence, the role of atrial polypeptide in mixtures with ATIII and in mixtures with FXa is quite contrasting, and may reflect mechanistic effects of the atrial polypeptide molecule, as well as tissue-specific reactions.
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17
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Bhattacharjee G, Ahamed J, Pawlinski R, Liu C, Mackman N, Ruf W, Edgington TS. Factor Xa binding to annexin 2 mediates signal transduction via protease-activated receptor 1. Circ Res 2008; 102:457-64. [PMID: 18174463 DOI: 10.1161/circresaha.107.167759] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The serine protease zymogen factor X is converted to its catalytically active form factor Xa by the binary complex of factor VIIa bound to its cell surface receptor tissue factor (TF) or by the intrinsic Xase complex, which consists of active factors VIII (VIIIa), IX (IXa), factor X, and Ca2+. Factor Xa has procoagulant activity by conversion of prothrombin to thrombin and also induces signal transduction, either alone or in the ternary TF:VIIa:factor Xa coagulation initiation complex. Factor Xa cleaves and activates protease activated receptor (PAR)1 or -2, but factor Xa signaling efficiency varies among cell types. We show here that annexin 2 acts as a receptor for factor Xa on the surface of human umbilical vein endothelial cells and that annexin 2 facilitates factor Xa activation of PAR-1 but does not enhance coagulant function of factor Xa. Overexpression of TF abolishes annexin 2 dependence on factor Xa signaling and diminishes binding to cell surface annexin 2, whereas selectively abolishing TF promotes the annexin 2/factor Xa interaction. We propose that annexin 2 serves to regulate factor Xa signaling specifically in the absence of cell surface TF and may thus play physiological or pathological roles when factor Xa is generated in a TF-depleted environment.
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Affiliation(s)
- Gourab Bhattacharjee
- Scripps Research Institute, SP-258, 10550 N Torrey Pines Rd, La Jolla, CA 92037, USA.
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18
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Zeibdawi AR, Pryzdial EL. Mechanism of factor Va inactivation by plasmin. Loss of A2 and A3 domains from a Ca2+-dependent complex of fragments bound to phospholipid. J Biol Chem 2001; 276:19929-36. [PMID: 11278280 DOI: 10.1074/jbc.m004711200] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The coagulation cofactor Va (FVa) is a noncovalent heterodimer consisting of a heavy chain (FVaH) and a light chain (FVaL). Previously, the fibrinolytic effector plasmin (Pn) has been shown to inhibit FVa function. To understand this mechanism, the fragmentation profile of human FVa by Pn and the noncovalent association of the derived fragments were determined in the presence of Ca(2+) using anionic phospholipid (aPL)-coated microtiter wells and large (1 microm) aPL micelles as affinity matrices. Following Pn inactivation of aPL-bound FVa, a total of 16 fragments were observed and their NH(2) termini sequenced. These had apparent molecular weights and starting residues as follows (single letter abbreviation is used): 50(L1766), 48(L1766), 43(Q1828), 40(Q1828), 30(S1546), 12(T1657), and 7(S1546) kDa from FVaL; and 65(A1), 50(A1), 45(A1), 34(S349), 30(L94), 30(M110), and 3 small <5(W457, W457, and K365) kDa from FVaH. Of these, 50(L1766), 48(1766), 43(Q1828), and 40(Q1828) spanning the C1/C2 domains, and 30(L94), but not the similar 30(M110), positioned within the A1 domain remained associated with aPL. These were detected antigenically during Pn- or tissue plasminogen activator-mediated lysis of fibrin clot formed in plasma. Chelation by EDTA dissociated the 30(L94)-kDa fragment, which was observed to associate with intact FVaL upon recalcification, indicating that the Leu-94 to Lys-109 region of the A1 domain plays a critical role in the FVaL and FVaH Ca(2+)-dependent association. By using domain-specific monoclonal antibodies and an assay for thrombin generation, loss of FVa prothrombinase function was coincident with proteolysis at sites in the A2 and A3 domains resulting in their dissociation. Inactivation of FV or FVa by Pn was independent of the thrombophilic R506Q mutation. These results identify the molecular composition of Pn-cleaved FVa that remains bound to membrane as largely A1-C1/C2 in the presence of Ca(2+) and suggest that Pn inhibits FVa by a process involving A2 and A3 domain dissociation.
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Affiliation(s)
- A R Zeibdawi
- Research and Development Department, the Canadian Blood Services, Department of Biochemistry, University of Ottawa, Ottawa, Ontario K1G 4J5, Canada
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19
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Grundy JE, Lavigne N, Hirama T, MacKenzie CR, Pryzdial EL. Binding of Plasminogen and Tissue Plasminogen Activator to Plasmin-Modulated Factor X and Factor Xa. Biochemistry 2001; 40:6293-302. [PMID: 11371191 DOI: 10.1021/bi002209v] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Previous work in our laboratory has suggested that the fibrinolytic enzyme plasmin (Pn) inactivates coagulation factors X (FX) and Xa (FXa) in the presence of Ca(2+) and anionic phospholipid (aPL), producing fragments which bind plasminogen (Pg) and accelerate tissue plasminogen activator (t-PA). Our goals here were to determine if the Pn-mediated fragments of FX or FXa remain associated, whether they directly bind t-PA, and to quantify their interaction with Pg. Binding to aPL, benzamidine-Sepharose, or the active-site inhibitor dansyl-Glu-Gly-Arg-chloromethyl ketone demonstrated that Pn cleavage yielded noncovalent heterodimers of a fragment containing the aPL-binding domain (FXgamma(47) or FXagamma(33)) and a 13-kDa fragment (FXgamma(13) or FXagamma(13)). Both ligand blotting and surface plasmon resonance (SPR) showed that Pn-cleaved FX and FXa bound t-PA directly when Pn-treatment was effected in the presence of aPL and Ca(2+). Using SPR, apparent K(d) values of 1-3 microM and 0.3-0.4 microM were measured directly and by competition for the FXgamma(47/13)-Pg and FXagamma(33/13)-Pg interactions, respectively. For the first time, Pg-binding to a receptor was shown to be Ca(2+) enhanced, although primarily mediated by C-terminal lysine residues. Mathematical modeling of kinetic data suggesting two Pg per FXgamma(47/13) or FXagamma(33/13) was consistent with our conclusion that each subunit of FXgamma(47/13) or FXagamma(33/13) contains a C-terminal lysine. Earlier X-ray structures show that these Lys residues are distal from each other and the membrane, supporting the model where each interacts with a separate Pg. t-PA acceleration by FXgamma(47/13) or FXagamma(33/13) may therefore involve simultaneous presentation of two substrate molecules.
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Affiliation(s)
- J E Grundy
- R&D Department, Canadian Blood Services, 1800 Alta Vista Drive, Ottawa, Ontario, Canada K1G 4J5
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20
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Underwood MC, Zhong D, Mathur A, Heyduk T, Bajaj SP. Thermodynamic linkage between the S1 site, the Na+ site, and the Ca2+ site in the protease domain of human coagulation factor xa. Studies on catalytic efficiency and inhibitor binding. J Biol Chem 2000; 275:36876-84. [PMID: 10973949 DOI: 10.1074/jbc.m001386200] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The serine protease domain of factor Xa (FXa) contains a sodium as well as a calcium-binding site. Here, we investigated the functional significance of these two cation-binding sites and their thermodynamic links to the S1 site. Kinetic data reveal that Na(+) binds to the substrate bound FXa with K(d) approximately 39 mm in the absence and approximately 9.5 mm in the presence of Ca(2+). Sodium-bound FXa (sodium-Xa) has approximately 18-fold increased catalytic efficiency ( approximately 4.5-fold decrease in K(m) and approximately 4-fold increase in k(cat)) in hydrolyzing S-2222 (benzoyl-Ile-Glu-Gly-Arg-p-nitroanilide), and Ca(2+) further increases this k(cat) approximately 1.4-fold. Ca(2+) binds to the protease domain of substrate bound FXa with K(d) approximately 705 microm in the absence and approximately 175 microm in the presence of Na(+). Ca(2+) binding to the protease domain of FXa (Xa-calcium) has no effect on the K(m) but increases the k(cat) approximately 4-fold in hydrolyzing S-2222, and Na(+) further increases this k(cat) approximately 1.4-fold. In agreement with the K(m) data, sodium-Xa has approximately 5-fold increased affinity in its interaction with p-aminobenzamidine (S1 site probe) and approximately 4-fold increased rate in binding to the two-domain tissue factor pathway inhibitor; Ca(2+) (+/-Na(+)) has no effect on these interactions. Antithrombin binds to Xa-calcium with a approximately 4-fold faster rate, to sodium-Xa with a approximately 24-fold faster rate and to sodium-Xa-calcium with a approximately 28-fold faster rate. Thus, Ca(2+) and Na(+) together increase the catalytic efficiency of FXa approximately 28-fold. Na(+) enhances Ca(2+) binding, and Ca(2+) enhances Na(+) binding. Further, Na(+) enhances S1 site occupancy, and S1 site occupancy enhances Na(+) binding. Therefore, Na(+) site is thermodynamically linked to the S1 site as well as to the protease domain Ca(2+) site, whereas Ca(2+) site is only linked to the Na(+) site. The significance of these findings is that during physiologic coagulation, most of the FXa formed will exist as sodium-Xa-calcium, which has maximum biologic activity.
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Affiliation(s)
- M C Underwood
- Department of Biochemistry and Molecular Biology and the Departments of Medicine and Pathology, St. Louis University School of Medicine, St. Louis, Missouri 63104, USA
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21
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Brown MA, Stenberg LM, Persson U, Stenflo J. Identification and purification of vitamin K-dependent proteins and peptides with monoclonal antibodies specific for gamma -carboxyglutamyl (Gla) residues. J Biol Chem 2000; 275:19795-802. [PMID: 10779512 DOI: 10.1074/jbc.m002298200] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Novel monoclonal antibodies that specifically recognize gamma-carboxyglutamyl (Gla) residues in proteins and peptides have been produced. As demonstrated by Western blot and time-resolved immunofluorescence assays the antibodies are pan-specific for most or all of the Gla-containing proteins tested (factors VII, IX, and X, prothrombin, protein C, protein S, growth arrest-specific protein 6, bone Gla protein, conantokin G from a cone snail, and factor Xa-like proteins from snake venom). Only the Gla-containing light chain of the two-chain proteins was bound. Decarboxylation destroyed the epitope(s) on prothrombin fragment 1, and Ca(2+) strongly inhibited binding to prothrombin. In Western blot, immunofluorescence, and surface plasmon resonance assays the antibodies bound peptides conjugated to bovine serum albumin that contained either a single Gla or a tandem pair of Gla residues. Binding was maintained when the sequence surrounding the Gla residue(s) was altered. Replacement of Gla with glutamic acid resulted in a complete loss of the epitope. The utility of the antibodies was demonstrated in immunochemical methods for detecting Gla-containing proteins and in the immunopurification of a factor Xa-like protein from tiger snake venom. The amino acid sequences of the Gla domain and portions of the heavy chain of the snake protein were determined.
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Affiliation(s)
- M A Brown
- Department of Clinical Chemistry, Lund University, University Hospital, Malmö, S-205 02 Malmö, Sweden
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22
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Enyedy EJ, Kovach IM. Reversible modulation of human factor Xa activity with phosphonate esters: media effects. Bioorg Med Chem 2000; 8:549-56. [PMID: 10732971 DOI: 10.1016/s0968-0896(99)00321-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Enantiomers of 4-nitrophenyl 4-X-phenacyl methylphosphonate esters (X = H, PMN; CH3 and CH3O) inactivate human factor Xa with rate constants 8-86 M(-1)s(-1) at pH 6.75 in 0.025 M Hepes buffer, 0.15 M NaCl and 2 mM CaCl2 at 7.0+/-0.1 degrees C. The stereoselectivity of the inactivation of factor Xa is 2-10 and favors the levorotatory enantiomers. The pH-dependence of inactivation of factor Xa by (-)-PMN is sigmoidal and consistent with the participation of a catalytic residue with a pKa of 6.2+/-0.1. Factor Xa reactivates from its phosphonyl adducts through a self-catalyzed intramolecular reaction, which is much influenced by the presence of phospholipids. The rate of reactivation in the absence of phospholipids is not pH dependent at pH <9, but it increases very much at pH >9. In the presence of phospholipids, the pH dependence of the rate constant for reactivation is sigmoidal in the pH 6.5-10.3 range and levels off at pH >9 indicating that the enzyme catalyzes its reactivation. The kinetic pKa for the recovery of factor Xa from its adducts with the PMNs is in the range of 6.7-8.1 and is consistent with the participation of the catalytic His57 in the reactivation process.
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Affiliation(s)
- E J Enyedy
- Department of Chemistry, The Catholic University of America, Washington, DC 20064, USA
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23
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Himmelspach M, Pfleiderer M, Fischer BE, Plaimauer B, Antoine G, Falkner FG, Dorner F, Schlokat U. Recombinant human factor X: high yield expression and the role of furin in proteolytic maturation in vivo and in vitro. Thromb Res 2000; 97:51-67. [PMID: 10688334 DOI: 10.1016/s0049-3848(99)00145-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Factor X/Xa plays a pivotal role in the coagulation cascade and exhibits a therapeutic potential for the treatment of factor X-deficient as well as FVIII and FIX inhibitor patients. This report describes the establishment of Chinese hamster ovary cell clones expressing recombinant human factor X up to 120 microg/mL x day and 78 microg/10(6) cells x day, that is to 100-fold higher levels than reported previously. Although propeptide removal and single chain precursor to light and heavy chain processing as well as vitamin K-dependent gamma-carboxylation became impaired at these expression levels, up to 25% of the recombinant human factor X produced was active. This represents the highest functional activity ever reported for a vitamin K-dependent protein at such an expression level. Expression of recombinant human factor X in Chinese hamster ovary cells lacking the endoprotease Furin revealed that propeptide removal still occurred, whereas single chain precursor to light/heavy chain processing was abolished. This suggests that a protease different from Furin mediates propeptide removal, a unique finding compared with the other vitamin K-dependent coagulation factors. In contrast, exposure of incompletely processed rFX molecules to soluble recombinant Furin in vitro mediated both of these cleavage reactions despite the absence of a typical argP4-xP3-lys/argP2-argP1 Furin cleavage site in the propeptide, indicating relaxed specificity in vitro. Concomitantly with the degree of processing, the functional activity of recombinant human factor X increased. Interestingly, Furin was shown to even perform correct N-terminal proteolytic trimming of FX molecules truncated amino-terminal to the P3 residue in vitro. Depending on the absence or presence of warfarin in the culture media, as well as on the processing state, four distinct recombinant human factor X light chain isoforms were observed and their structure characterized. One of these light chain forms correlated with the functional activity. Finally, the distribution of the individual light chain isoforms suggests that gamma-carboxylation may be a prerequisite for propeptide removal.
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Affiliation(s)
- M Himmelspach
- Biomedical Research Center, Hyland-IMMUNO Division of Baxter Healthcare Corp., Orth/Donau, Austria
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24
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Pryzdial EL, Lavigne N, Dupuis N, Kessler GE. Plasmin converts factor X from coagulation zymogen to fibrinolysis cofactor. J Biol Chem 1999; 274:8500-5. [PMID: 10085082 DOI: 10.1074/jbc.274.13.8500] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Known anticoagulant pathways have been shown to exclusively inhibit blood coagulation cofactors and enzymes. In the current work, we first investigated the possibility of a novel anticoagulant mechanism that functions at the level of zymogen inactivation. Utilizing both clotting and chromogenic assays, the fibrinolysis protease plasmin was found to irreversibly inhibit the pivotal function of factor X (FX) in coagulation. This was due to cleavage at several sites, the location of which were altered by association of FX with procoagulant phospholipid (proPL). The final products were approximately 28 and approximately 47 kDa for proPL-bound and unbound FX, respectively, which did not have analogues when activated FX (FXa) was cleaved instead. We next investigated whether the FX derivatives could interact with the plasmin precursor plasminogen, and we found that plasmin exposed a binding site only on proPL-bound FX. The highest apparent affinity was for the 28-kDa fragment, which was identified as the light subunit disulfide linked to a small fragment of the heavy subunit (Met-296 to approximately Lys-330). After cleavage by plasmin, proPL-bound FX furthermore was observed to accelerate plasmin generation by tissue plasminogen activator. Thus, a feedback mechanism localized by proPL is suggested in which plasmin simultaneously inhibits FX clotting function and converts proPL-bound FX into a fibrinolysis cofactor. These data also provide the first evidence for an anticoagulant mechanism aimed directly at the zymogen FX.
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Affiliation(s)
- E L Pryzdial
- Research and Development Department, Canadian Blood Services and Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Ontario K1G 4J5, Canada.
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25
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Sabharwal AK, Padmanabhan K, Tulinsky A, Mathur A, Gorka J, Bajaj SP. Interaction of calcium with native and decarboxylated human factor X. Effect of proteolysis in the autolysis loop on catalytic efficiency and factor Va binding. J Biol Chem 1997; 272:22037-45. [PMID: 9268343 DOI: 10.1074/jbc.272.35.22037] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Human factor X is a two-chain, 58-kDa, vitamin K-dependent blood coagulation zymogen. The light chain of factor X consists of an NH2-terminal gamma-carboxyglutamic acid (Gla) domain, followed by a few helical hydrophobic residues and the two epidermal growth factor-like domains, whereas the heavy chain contains the serine protease domain. In this study, native factor X was found to contain three classes of Ca2+-binding sites: two high affinity (Kd 100 +/- 30 microM), four intermediate affinity (Kd 450 +/- 70 microM), and five to six low affinity (Kd 2 +/- 0.2 mM). Decarboxylated factor X in which the Gla residues were converted to Glu retained the two high affinity sites (Kd 140 +/- 20 microM). In contrast, factor X lacking the Gla domain as well as a part of the helical hydrophobic residues (des-44-X) retained only one high affinity Ca2+-binding site (Kd 130 +/- 20 microM). Moreover, a synthetic peptide composed of residues 238-277 (58-97 in chymotrypsinogen numbering) from the protease domain of factor X bound one Ca2+ with high affinity (Kd 150 +/- 20 microM). From competitive inhibition assays for binding of active site-blocked factor Xa to factor Va in the prothrombinase complex, the Kd for peptide-Va interaction was calculated to be approximately 10 microM as compared with 30 pM for factor Xa and approximately 1.5 microM for decarboxylated factor Xa. A peptide containing residues 238-262(58-82) bound Ca2+ with reduced affinity (Kd approximately 600 microM) and did not inhibit Xa:Va interaction. In contrast, a peptide containing residues 253-277(73-97) inhibited Xa:Va interaction (Kd approximately 10 microM) but did not bind Ca2+. In additional studies, Ca2+ increased the amidolytic activity of native and des-44-Xa toward a tetrapeptide substrate (benzoyl-Ile-Glu-Gly-Arg-p-nitroanilide) by approximately 1.6-fold. The half-maximal increase was observed at approximately 150 microM Ca2+ and the effect was primarily on the kcat. Ca2+ also significantly protected cleavage at Arg-332-Gln-333(150-151) in the protease domain autolysis loop. Des-44-Xa in which the autolysis loop was cleaved possessed </=5% of the amidolytic activity of the noncleaved form; however, the S1 binding site was not affected, as determined by the p-aminobenzamidine binding. Additionally, autolysis loop-cleaved, active site-blocked native factor Xa was calculated to have approximately 10-fold reduced affinity for factor Va as compared with that of the noncleaved form.
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Affiliation(s)
- A K Sabharwal
- Department of Medicine, Saint Louis University School of Medicine, St. Louis, Missouri 63104, USA
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