1
|
Swan D, Mahlangu J, Thachil J. Non-factor therapies for bleeding disorders: A primer for the general haematologist. EJHAEM 2022; 3:584-595. [PMID: 36051064 PMCID: PMC9422036 DOI: 10.1002/jha2.442] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/17/2022] [Revised: 03/31/2022] [Accepted: 04/04/2022] [Indexed: 11/09/2022]
Abstract
Management of patients with severe bleeding disorders, particularly haemophilia A and B, and to a lesser extent, von Willebrand disease, has come on leaps and bounds over the past decade. Until recently, patients relied upon the administration of factor concentrates to prevent or treat bleeding episodes. Factor administration requires intravenous access and, in up to one-third of patients, leads to the development of neutralising antibodies, or inhibitors, which are associated with more frequent bleeding episodes and higher morbidity. Novel non-factor therapies may offer a solution to these unmet needs. In this review, we discuss the factor mimetics, particularly emicizumab, and the rebalancing agents, which inhibit antithrombin, tissue factor pathway inhibitor and activated protein C, and novel treatments to enhance von Willebrand factor levels. We review the available trial data, unanswered questions and challenges associated with these new treatment modalities. Finally, we provide practical management algorithms to aid the general haematologist when faced with a patient receiving emicizumab who requires surgery or may develop bleeding.
Collapse
Affiliation(s)
- Dawn Swan
- National University IrelandGalwayRepublic of Ireland
| | - Johnny Mahlangu
- Department of Molecular Medicine and HaematologySchool of PathologyFaculty of Health SciencesUniversity of the Witwatersrand and NHLSJohannesburgSouth Africa
| | - Jecko Thachil
- Department of HaematologyManchester University Hospitals NHS Foundation TrustManchesterUK
| |
Collapse
|
2
|
Grover SP, Mackman N. Anticoagulant SERPINs: Endogenous Regulators of Hemostasis and Thrombosis. Front Cardiovasc Med 2022; 9:878199. [PMID: 35592395 PMCID: PMC9110684 DOI: 10.3389/fcvm.2022.878199] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Accepted: 03/29/2022] [Indexed: 12/17/2022] Open
Abstract
Appropriate activation of coagulation requires a balance between procoagulant and anticoagulant proteins in blood. Loss in this balance leads to hemorrhage and thrombosis. A number of endogenous anticoagulant proteins, such as antithrombin and heparin cofactor II, are members of the serine protease inhibitor (SERPIN) family. These SERPIN anticoagulants function by forming irreversible inhibitory complexes with target coagulation proteases. Mutations in SERPIN family members, such as antithrombin, can cause hereditary thrombophilias. In addition, low plasma levels of SERPINs have been associated with an increased risk of thrombosis. Here, we review the biological activities of the different anticoagulant SERPINs. We further consider the clinical consequences of SERPIN deficiencies and insights gained from preclinical disease models. Finally, we discuss the potential utility of engineered SERPINs as novel therapies for the treatment of thrombotic pathologies.
Collapse
|
3
|
A Review of Alpha-1 Antitrypsin Binding Partners for Immune Regulation and Potential Therapeutic Application. Int J Mol Sci 2022; 23:ijms23052441. [PMID: 35269582 PMCID: PMC8910375 DOI: 10.3390/ijms23052441] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Revised: 02/17/2022] [Accepted: 02/18/2022] [Indexed: 02/06/2023] Open
Abstract
Alpha-1 antitrypsin (AAT) is the canonical serine protease inhibitor of neutrophil-derived proteases and can modulate innate immune mechanisms through its anti-inflammatory activities mediated by a broad spectrum of protein, cytokine, and cell surface interactions. AAT contains a reactive methionine residue that is critical for its protease-specific binding capacity, whereby AAT entraps the protease on cleavage of its reactive centre loop, neutralises its activity by key changes in its tertiary structure, and permits removal of the AAT-protease complex from the circulation. Recently, however, the immunomodulatory role of AAT has come increasingly to the fore with several prominent studies focused on lipid or protein-protein interactions that are predominantly mediated through electrostatic, glycan, or hydrophobic potential binding sites. The aim of this review was to investigate the spectrum of AAT molecular interactions, with newer studies supporting a potential therapeutic paradigm for AAT augmentation therapy in disorders in which a chronic immune response is strongly linked.
Collapse
|
4
|
Maas C, de Maat S. Therapeutic SERPINs: Improving on Nature. Front Cardiovasc Med 2021; 8:648349. [PMID: 33869308 PMCID: PMC8044344 DOI: 10.3389/fcvm.2021.648349] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Accepted: 03/10/2021] [Indexed: 01/22/2023] Open
Abstract
Serine proteases drive important physiological processes such as coagulation, fibrinolysis, inflammation and angiogenesis. These proteases are controlled by serine protease inhibitors (SERPINs) that neutralize their activity. Currently, over 1,500 SERPINs are known in nature, but only 37 SERPINs are found in humans. Thirty of these are functional protease inhibitors. The inhibitory potential of SERPINs is in perfect balance with the proteolytic activities of its targets to enable physiological protease activity. Hence, SERPIN deficiency (either qualitative or quantitative) can lead to disease. Several SERPIN resupplementation strategies have been developed to treat SERPIN deficiencies, including concentrates derived from plasma and recombinant SERPINs. SERPINs usually inhibit multiple proteases, but only in their active state. Over the past decades, considerable insights have been acquired in the identification of SERPIN biological functions, their inhibitory mechanisms and specificity determinants. This paves the way for the development of therapeutic SERPINs. Through rational design, the inhibitory properties (selectivity and inhibitory potential) of SERPINs can be reformed and optimized. This review explores the current state of SERPIN engineering with a focus on reactive center loop modifications and backbone stabilization. We will discuss the lessons learned from these recombinant SERPINs and explore novel techniques and strategies that will be essential for the creation and application of the future generation of therapeutic SERPINs.
Collapse
Affiliation(s)
- Coen Maas
- CDL Research, University Medical Center Utrecht, Utrecht, Netherlands
| | - Steven de Maat
- CDL Research, University Medical Center Utrecht, Utrecht, Netherlands
| |
Collapse
|
5
|
Hamada M, Bhakta V, Andres SN, Sheffield WP. Stepwise Reversion of Multiply Mutated Recombinant Antitrypsin Reveals a Selective Inhibitor of Coagulation Factor XIa as Active as the M358R Variant. Front Cardiovasc Med 2021; 8:647405. [PMID: 33816577 PMCID: PMC8017132 DOI: 10.3389/fcvm.2021.647405] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Accepted: 02/16/2021] [Indexed: 11/13/2022] Open
Abstract
Alpha-1 antitrypsin (AAT, also known as alpha-1 proteinase inhibitor or SERPINA1) is the most abundant member of the serpin superfamily found in human plasma. The naturally occurring variant AAT M358R, altered at the P1 position of the critical reactive center loop (RCL), is re-directed away from inhibition of AAT's chief natural target, neutrophil elastase, and toward accelerated inhibition of thrombin (FIIa), kallikrein (Kal), and other proteases such as factor XIa (FXIa). FXIa is an emerging target for the development of antithrombotic agents, since patients with FXI deficiency are protected from thromboembolic disease and do not exhibit a strong bleeding tendency. Previously, we used phage display, bacterial lysate screening, and combinatorial mutagenesis to identify AAT-RC, an engineered AAT M358R with additional changes between RCL positions P7-P3', CLEVEPR-STE [with changes bolded and the P1-P1' (R358-S359) reactive center shown as R-S]. AAT-RC was 279- and 16-fold more selective for FXIa/IIa or FXIa/Kal than AAT M358R; the increased selectivity came at a cost of a 2.3-fold decrease in the rate of FXIa inhibition and a 3.3-fold increase in the stoichiometry of inhibition (SI). Here, we asked which alterations in AAT-RC were most important for the observed increases in selectivity for FXIa inhibition. We back-mutated AAT-RC to AAT-RC-1 (P7-P3' FLEVEPRSTE), AAT-RC-2 (P7-P3' FLEAEPRSTE), and AAT RC-3 (P7-P3' FLEAIPR-STE). Proteins were expressed as cleavable, hexahistidine-tagged glutathione sulfotransferase fusion proteins in E. coli and purified by proteolytic elution from glutathione agarose, with polishing on nickel chelate agarose. Selectivity for FXIa over Kal of AAT-RC-1, −2, and −3 was 14, 21, and 2.3, respectively. AAT-RC-2 inhibited FXIa 31% more rapidly than AAT M358R, with the same SI, and enhanced selectivity for FXIa over Kal, FXa, FXIIa, activated protein C, and FIIa of 25-, 130-, 420-, 440-, and 470-fold, respectively. Structural modeling of the AAT-RC-2/FXIa encounter complex suggested that both E (Glu) substitutions at P3 and P3' may promote FXIa binding via hydrogen bonding to K192 in FXIa. AAT-RC-2 is the most selective and active AAT variant reported to date for FXIa inhibition and will be tested in animal models of thrombosis and bleeding.
Collapse
Affiliation(s)
- Mostafa Hamada
- Department of Pathology and Molecular Medicine, McMaster University, Hamilton, ON, Canada
| | - Varsha Bhakta
- Centre for Innovation, Canadian Blood Services, Hamilton, ON, Canada
| | - Sara N Andres
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON, Canada
| | - William P Sheffield
- Department of Pathology and Molecular Medicine, McMaster University, Hamilton, ON, Canada.,Centre for Innovation, Canadian Blood Services, Hamilton, ON, Canada
| |
Collapse
|
6
|
Identification of an alpha-1 antitrypsin variant with enhanced specificity for factor XIa by phage display, bacterial expression, and combinatorial mutagenesis. Sci Rep 2021; 11:5565. [PMID: 33692375 PMCID: PMC7946950 DOI: 10.1038/s41598-021-84618-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Accepted: 02/15/2021] [Indexed: 01/20/2023] Open
Abstract
Coagulation Factor XIa (FXIa) is an emerging target for antithrombotic agent development. The M358R variant of the serpin alpha-1 antitrypsin (AAT) inhibits both FXIa and other proteases. Our aim was to enhance the specificity of AAT M358R for FXIa. We randomized two AAT M358R phage display libraries at reactive centre loop positions P13-P8 and P7-P3 and biopanned them with FXIa. A bacterial expression library randomized at P2′-P3′ was also probed. Resulting novel variants were expressed as recombinant proteins in E. coli and their kinetics of FXIa inhibition determined. The most potent FXIa-inhibitory motifs were: P13-P8, HASTGQ; P7-P3, CLEVE; and P2-P3′, PRSTE (respectively, novel residues bolded). Selectivity for FXIa over thrombin was increased up to 34-fold versus AAT M358R for these single motif variants. Combining CLEVE and PRSTE motifs in AAT-RC increased FXIa selectivity for thrombin, factors XIIa, Xa, activated protein C, and kallikrein by 279-, 143-, 63-, 58-, and 36-fold, respectively, versus AAT M358R. AAT-RC lengthened human plasma clotting times less than AAT M358R. AAT-RC rapidly and selectively inhibits FXIa and is worthy of testing in vivo. AAT specificity can be focused on one target protease by selection in phage and bacterial systems coupled with combinatorial mutagenesis.
Collapse
|
7
|
Luo XH, Zhu Y, Shui LP, Xiao Q, Liu L. Repeated ruptures of corpus luteum in a female patient with alpha1-antitrypsin Pittsburgh. Ann Hematol 2020; 100:847-850. [PMID: 33156375 DOI: 10.1007/s00277-020-04327-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Accepted: 10/27/2020] [Indexed: 11/27/2022]
Affiliation(s)
- Xiao-Hua Luo
- Department of Hematology, The First Affiliated Hospital of Chongqing Medical University, Chongqing, 400016, China.
| | - Yan Zhu
- Department of Hematology, Southwest Hospital, Third Military Medical University (Army Medical University), Chongqing, 400038, China
| | - Li-Ping Shui
- Department of Hematology, The First Affiliated Hospital of Chongqing Medical University, Chongqing, 400016, China
| | - Qing Xiao
- Department of Hematology, The First Affiliated Hospital of Chongqing Medical University, Chongqing, 400016, China
| | - Lin Liu
- Department of Hematology, The First Affiliated Hospital of Chongqing Medical University, Chongqing, 400016, China
| |
Collapse
|
8
|
Design and characterization of α1-antitrypsin variants for treatment of contact system-driven thromboinflammation. Blood 2020; 134:1658-1669. [PMID: 31366623 DOI: 10.1182/blood.2019000481] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Accepted: 07/22/2019] [Indexed: 01/15/2023] Open
Abstract
The contact system produces the inflammatory peptide bradykinin and contributes to experimental thrombosis. C1 esterase-inhibitor (C1INH) deficiency or gain-of-function mutations in factor XII (FXII) cause hereditary angioedema, a life-threatening tissue swelling disease. C1INH is a relatively weak contact system enzyme inhibitor. Although α1-antitrypsin (α1AT) does not naturally inhibit contact system enzymes, a human mutation (M358R; α1AT-Pittsburgh) changes it into a powerful broad-spectrum enzyme inhibitor. It blocks the contact system, but also thrombin and activated protein C (APC), making it an unattractive candidate for therapeutic contact system blockade. We adapted the reactive center loop of α1AT-Pittsburgh (AIPR/S) to overcome these obstacles. Two α1AT variants (SMTR/S and SLLR/S) strongly inhibit plasma kallikrein, activated FXII, and plasmin. α1AT-SMTR/S no longer inhibits thrombin, but residually inhibits APC. In contrast, α1AT-SLLR/S residually inhibits thrombin, but no longer APC. Additional modification at the P1' position (S→V) eliminates residual inhibition of thrombin and APC for both variants, while retaining their properties as contact system inhibitors. Both α1AT-SMTR/V and -SLLR/V are superior to C1INH in reducing bradykinin production in plasma. Owing to their capacity to selectively block contact system-driven coagulation, both variants block vascular occlusion in an in vivo model for arterial thrombosis. Furthermore, both variants block acute carrageenan-induced tissue edema in mice. Finally, α1AT-SLLR/V, our most powerful candidate, suppresses epithelial leakage of the gut in a mouse model of colitis. Our findings confirm that redesign of α1AT strongly alters its inhibitory behavior and can be used for the treatment of contact system-mediated thrombosis and inflammation.
Collapse
|
9
|
Cheng S, Qi F, Jiang Z, Peng B, Hou W, Wang Y, Xiao J, Guo H, Wang Z. Knockdown of Clock gene induces thrombotic potential reduction by inhibiting α1-antitrypsin with promotion of fibronectin. BIOL RHYTHM RES 2020. [DOI: 10.1080/09291016.2020.1712782] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Affiliation(s)
- Shuting Cheng
- Health Ministry Key Laboratory of Chronobiology, West China School of Basic Medical Sciences & Forensic Medicine, Sichuan University, Chengdu, P.R. China
| | - Fang Qi
- Health Ministry Key Laboratory of Chronobiology, West China School of Basic Medical Sciences & Forensic Medicine, Sichuan University, Chengdu, P.R. China
| | - Zhou Jiang
- Health Ministry Key Laboratory of Chronobiology, West China School of Basic Medical Sciences & Forensic Medicine, Sichuan University, Chengdu, P.R. China
| | - Bo Peng
- Health Ministry Key Laboratory of Chronobiology, West China School of Basic Medical Sciences & Forensic Medicine, Sichuan University, Chengdu, P.R. China
| | - Wang Hou
- Health Ministry Key Laboratory of Chronobiology, West China School of Basic Medical Sciences & Forensic Medicine, Sichuan University, Chengdu, P.R. China
| | - Yuhui Wang
- Health Ministry Key Laboratory of Chronobiology, West China School of Basic Medical Sciences & Forensic Medicine, Sichuan University, Chengdu, P.R. China
| | - Jing Xiao
- Health Ministry Key Laboratory of Chronobiology, West China School of Basic Medical Sciences & Forensic Medicine, Sichuan University, Chengdu, P.R. China
| | - Huiling Guo
- Health Ministry Key Laboratory of Chronobiology, West China School of Basic Medical Sciences & Forensic Medicine, Sichuan University, Chengdu, P.R. China
| | - Zhengrong Wang
- Health Ministry Key Laboratory of Chronobiology, West China School of Basic Medical Sciences & Forensic Medicine, Sichuan University, Chengdu, P.R. China
| |
Collapse
|
10
|
Scott BM, Sheffield WP. Engineering the serpin α 1 -antitrypsin: A diversity of goals and techniques. Protein Sci 2019; 29:856-871. [PMID: 31774589 DOI: 10.1002/pro.3794] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Revised: 11/19/2019] [Accepted: 11/19/2019] [Indexed: 12/19/2022]
Abstract
α1 -Antitrypsin (α1 -AT) serves as an archetypal example for the serine proteinase inhibitor (serpin) protein family and has been used as a scaffold for protein engineering for >35 years. Techniques used to engineer α1 -AT include targeted mutagenesis, protein fusions, phage display, glycoengineering, and consensus protein design. The goals of engineering have also been diverse, ranging from understanding serpin structure-function relationships, to the design of more potent or more specific proteinase inhibitors with potential therapeutic relevance. Here we summarize the history of these protein engineering efforts, describing the techniques applied to engineer α1 -AT, specific mutants of interest, and providing an appended catalog of the >200 α1 -AT mutants published to date.
Collapse
Affiliation(s)
- Benjamin M Scott
- Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland.,Biosystems and Biomaterials Division, National Institute of Standards and Technology, Gaithersburg, Maryland
| | - William P Sheffield
- Canadian Blood Services, Centre for Innovation, Hamilton, Ontario, Canada.,Department of Pathology and Molecular Medicine, McMaster University, Hamilton, Ontario, Canada
| |
Collapse
|
11
|
Luo S, Ruan X, Wang Y, Li X, Xu Z, Min M, Li M, Zhang L, Li Y, Wang H, Cheng J, Zhang L, Wang Y, Mueck AO. The first family group of α1-AT-P in the world with repeated hematomas: 10-year follow-up. Climacteric 2019; 22:527-530. [PMID: 31079543 DOI: 10.1080/13697137.2019.1611762] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Affiliation(s)
- S. Luo
- Department of Gynecological Endocrinology, Beijing Obstetrics and Gynecology Hospital, Capital Medical University, Beijing, China
- Department of Gynecology, Henan Province People’s Hospital, Henan University, Zhengzhou, China
| | - X. Ruan
- Department of Gynecological Endocrinology, Beijing Obstetrics and Gynecology Hospital, Capital Medical University, Beijing, China
- Department of Women’s Health, University Women’s Hospital, University of Tübingen, Tübingen, Germany
| | - Y. Wang
- Department of Gynecology, Henan Province People’s Hospital, Henan University, Zhengzhou, China
| | - X. Li
- Department of Gynecological Endocrinology, Beijing Obstetrics and Gynecology Hospital, Capital Medical University, Beijing, China
| | - Z. Xu
- Department of Gynecological Endocrinology, Beijing Obstetrics and Gynecology Hospital, Capital Medical University, Beijing, China
| | - M. Min
- Department of Gynecological Endocrinology, Beijing Obstetrics and Gynecology Hospital, Capital Medical University, Beijing, China
| | - M. Li
- Department of Gynecological Endocrinology, Beijing Obstetrics and Gynecology Hospital, Capital Medical University, Beijing, China
| | - L. Zhang
- Department of Gynecological Endocrinology, Beijing Obstetrics and Gynecology Hospital, Capital Medical University, Beijing, China
| | - Y. Li
- Department of Gynecological Endocrinology, Beijing Obstetrics and Gynecology Hospital, Capital Medical University, Beijing, China
| | - H. Wang
- Department of Gynecological Endocrinology, Beijing Obstetrics and Gynecology Hospital, Capital Medical University, Beijing, China
| | - J. Cheng
- Department of Gynecological Endocrinology, Beijing Obstetrics and Gynecology Hospital, Capital Medical University, Beijing, China
| | - L. Zhang
- Department of Gynecological Endocrinology, Beijing Obstetrics and Gynecology Hospital, Capital Medical University, Beijing, China
| | - Y. Wang
- Department of Gynecological Endocrinology, Beijing Obstetrics and Gynecology Hospital, Capital Medical University, Beijing, China
| | - A. O. Mueck
- Department of Gynecological Endocrinology, Beijing Obstetrics and Gynecology Hospital, Capital Medical University, Beijing, China
- Department of Women’s Health, University Women’s Hospital, University of Tübingen, Tübingen, Germany
| |
Collapse
|
12
|
Sanrattana W, Maas C, de Maat S. SERPINs-From Trap to Treatment. Front Med (Lausanne) 2019; 6:25. [PMID: 30809526 PMCID: PMC6379291 DOI: 10.3389/fmed.2019.00025] [Citation(s) in RCA: 73] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Accepted: 01/25/2019] [Indexed: 01/04/2023] Open
Abstract
Excessive enzyme activity often has pathological consequences. This for example is the case in thrombosis and hereditary angioedema, where serine proteases of the coagulation system and kallikrein-kinin system are excessively active. Serine proteases are controlled by SERPINs (serine protease inhibitors). We here describe the basic biochemical mechanisms behind SERPIN activity and identify key determinants that influence their function. We explore the clinical phenotypes of several SERPIN deficiencies and review studies where SERPINs are being used beyond replacement therapy. Excitingly, rare human SERPIN mutations have led us and others to believe that it is possible to refine SERPINs toward desired behavior for the treatment of enzyme-driven pathology.
Collapse
Affiliation(s)
| | | | - Steven de Maat
- Department of Clinical Chemistry and Haematology, University Medical Center Utrecht, Utrecht University, Utrecht, Netherlands
| |
Collapse
|
13
|
Horn JD, Maitland DJ, Hartman J, Ortega JM. A computational thrombus formation model: application to an idealized two-dimensional aneurysm treated with bare metal coils. Biomech Model Mechanobiol 2018; 17:1821-1838. [DOI: 10.1007/s10237-018-1059-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2017] [Accepted: 07/21/2018] [Indexed: 10/28/2022]
|
14
|
Chung HS, Kim JS, Lee SM, Park SJ. Role of the P2 residue of human alpha 1-antitrypsin in determining target protease specificity. PLoS One 2017; 12:e0185074. [PMID: 28922398 PMCID: PMC5602671 DOI: 10.1371/journal.pone.0185074] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2017] [Accepted: 09/06/2017] [Indexed: 11/19/2022] Open
Abstract
Alpha 1-antitrypsin (A1AT) is a serine protease inhibitor that mainly inhibits neutrophil elastase in the lungs. A variant of A1AT at the P1 position with methionine 358 to arginine (A1AT-Pittsburgh) is a rapid inhibitor of thrombin with greatly diminished anti-elastase activity. The P2 residue (position 357) of A1AT-Pittsburgh has been shown to play an important role in interactions with thrombin and kallikrein, but the role of P2 residue in wild-type A1AT has largely been unraveled. Here, we investigated the effects of P2 proline substitutions in wild-type A1AT on interactions with porcine pancreatic elastase (PPE) and human neutrophil elastase (HNE). The mutant A1AT proteins (P357A, P357D, P357K, P357L, P357N, P357S, and P357W) were less efficient than the wild-type A1AT at inhibiting PPE and HNE. Among the mutants, P357D did not form a complex with PPE, whereas P357L, P357N, and P357W showed significantly reduced complex formation with PPE. Surprisingly, mass spectrometry analysis revealed that P357D had two cleavage sites after the P9 alanine and the P3 isoleucine residues. Our results indicate that the size and negative charge of the R group of the P2 residue influence the interaction with elastases. Specifically, the negative charge at the P2 residue is disfavored and the resulting conformational changes in the reactive center loop upon interaction with PPE lead to cleavage at new sites. Overall, the results of this study demonstrate a previously unknown role for P2 residue in determining inhibitory specificity of A1AT.
Collapse
Affiliation(s)
- Hye-Shin Chung
- Alteogen Inc., Yuseong-gu, Daejeon, South Korea
- Department of Biological Sciences and Biotechnology, Hannam University, Daejeon, South Korea
| | - Ji-Sun Kim
- Alteogen Inc., Yuseong-gu, Daejeon, South Korea
| | | | - Soon Jae Park
- Alteogen Inc., Yuseong-gu, Daejeon, South Korea
- * E-mail:
| |
Collapse
|
15
|
Cao L, Wang Z, Bai X, Yu Z, Su J, Ruan C. Clinical characteristics of two patients with α1-antitrypsin Pittsburgh in a Chinese family. Haemophilia 2016; 23:e33-e36. [PMID: 27891716 DOI: 10.1111/hae.13113] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/12/2016] [Indexed: 01/09/2023]
Affiliation(s)
- L. Cao
- Jiangsu Institute of Haematology; Key Laboratory of Thrombosis and Haemostasis of Ministry of Health; The First Affiliated Hospital of Soochow University; Suzhou China
- Collaborative Innovation Center of Haematology; Soochow University; Suzhou China
| | - Z. Wang
- Jiangsu Institute of Haematology; Key Laboratory of Thrombosis and Haemostasis of Ministry of Health; The First Affiliated Hospital of Soochow University; Suzhou China
- Collaborative Innovation Center of Haematology; Soochow University; Suzhou China
| | - X. Bai
- Jiangsu Institute of Haematology; Key Laboratory of Thrombosis and Haemostasis of Ministry of Health; The First Affiliated Hospital of Soochow University; Suzhou China
- Collaborative Innovation Center of Haematology; Soochow University; Suzhou China
| | - Z. Yu
- Jiangsu Institute of Haematology; Key Laboratory of Thrombosis and Haemostasis of Ministry of Health; The First Affiliated Hospital of Soochow University; Suzhou China
- Collaborative Innovation Center of Haematology; Soochow University; Suzhou China
| | - J. Su
- Jiangsu Institute of Haematology; Key Laboratory of Thrombosis and Haemostasis of Ministry of Health; The First Affiliated Hospital of Soochow University; Suzhou China
- Collaborative Innovation Center of Haematology; Soochow University; Suzhou China
| | - C. Ruan
- Jiangsu Institute of Haematology; Key Laboratory of Thrombosis and Haemostasis of Ministry of Health; The First Affiliated Hospital of Soochow University; Suzhou China
- Collaborative Innovation Center of Haematology; Soochow University; Suzhou China
| |
Collapse
|
16
|
Design and characterization of an APC-specific serpin for the treatment of hemophilia. Blood 2016; 129:105-113. [PMID: 27789479 DOI: 10.1182/blood-2016-05-718635] [Citation(s) in RCA: 108] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2016] [Accepted: 08/06/2016] [Indexed: 01/08/2023] Open
Abstract
Hemophilia is a bleeding disorder caused by deficiency in factors VIII or IX, the two components of the intrinsic Xase complex. Treatment with replacement factor can lead to the development of inhibitory antibodies, requiring the use of bypassing agents such as factor VIIa and factor concentrates. An alternative approach to bypass the Xase complex is to inhibit endogenous anticoagulant activities. Activated protein C (APC) breaks down the complex that produces thrombin by proteolytically inactivating factor Va. Defects in this mechanism (eg, factor V Leiden) are associated with thrombosis but result in less severe bleeding when co-inherited with hemophilia. Selective inhibition of APC might therefore be effective for the treatment of hemophilia. The endogenous inhibitors of APC are members of the serpin family: protein C inhibitor (PCI) and α1-antitrypsin (α1AT); however, both exhibit poor reactivity and selectivity for APC. We mutated residues in and around the scissile P1-P1' bond in PCI and α1AT, resulting in serpins with the desired specificity profile. The lead candidate was shown to promote thrombin generation in vitro and to restore fibrin and platelet deposition in an intravital laser injury model in hemophilia B mice. The power of targeting APC was further demonstrated by the complete normalization of bleeding after a severe tail clip injury in these mice. These results demonstrate that the protein C anticoagulant system can be successfully targeted by engineered serpins and that administration of such agents is effective at restoring hemostasis in vivo.
Collapse
|
17
|
Henneuse A, Suchon P, Chambost H, Morange PE, Frere C, Alessi MC. α 1 -antitrypsin Pittsburgh and plasmin-mediated proteolysis. J Thromb Haemost 2016; 14:2023-2026. [PMID: 27468101 DOI: 10.1111/jth.13426] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Accepted: 06/24/2016] [Indexed: 11/28/2022]
Abstract
Essentials Patients with α-1-antitrypsin (α1-AT) Pittsburgh exhibit a mild bleeding tendency. A new case of α1-AT Pittsburgh with suspected high antifibrinolytic potential was studied. We showed that α1-AT Pittsburgh inhibits tissue plasminogen activator and plasmin. The antifibrinolytic potential of the variant contributes to explaining the mild bleeding phenotype. SUMMARY α1 -Antitrypsin (α1 -AT) Pittsburgh has a Met358 to Arg substitution at the reactive Met-Ser site of α1 -AT, which enables the protein to act as a potent thrombin inhibitor. Four patients with α1 -AT Pittsburgh have been described to date. An additional young girl was recently diagnosed with α1 -AT Pittsburgh in our center after presenting with a large hematoma in the forearm. Interestingly, all of these patients showed a potent thrombin inhibitor in the plasma and a mild bleeding phenotype. This observation suggests that the in vivo consequences of the mutation may contribute to the maintenance of normal hemostatic balance. We assessed inhibition of the fibrinolytic system by the variant protein by evaluating the fibrinolysis inhibitory potential of the patient's plasma, purified wild-type α1 -AT and purified Pittsburgh α1 -AT with an electrophoretic zymography system, western blotting, and clot fibrinolysis. Our results indicate that the patient's plasma and purified α1 -AT Pittsburgh have strong potential to inhibit tissue-type plasminogen activator and plasmin.
Collapse
Affiliation(s)
- A Henneuse
- Laboratoire hématologie, CHU Timone, Inserm UMR_S 1062, Inra UMR_1260, Aix-Marseille Université, Marseille, France
| | - P Suchon
- Laboratoire hématologie, CHU Timone, Inserm UMR_S 1062, Inra UMR_1260, Aix-Marseille Université, Marseille, France
| | - H Chambost
- Laboratoire hématologie, CHU Timone, Inserm UMR_S 1062, Inra UMR_1260, Aix-Marseille Université, Marseille, France
- Service d'Hématologie Oncologie Pédiatrique, CHU Timone, Assistance Publique-Hôpitaux de Marseille, Marseille, France
| | - P E Morange
- Laboratoire hématologie, CHU Timone, Inserm UMR_S 1062, Inra UMR_1260, Aix-Marseille Université, Marseille, France
| | - C Frere
- Laboratoire hématologie, CHU Timone, Inserm UMR_S 1062, Inra UMR_1260, Aix-Marseille Université, Marseille, France
| | - M C Alessi
- Laboratoire hématologie, CHU Timone, Inserm UMR_S 1062, Inra UMR_1260, Aix-Marseille Université, Marseille, France.
| |
Collapse
|
18
|
Alsultan A, Gale AJ, Kurban K, Khalifah M, Albadr FB, Griffin JH. Activation-resistant homozygous protein C R229W mutation causing familial perinatal intracranial hemorrhage and delayed onset of thrombosis. Thromb Res 2016; 143:17-21. [PMID: 27172833 DOI: 10.1016/j.thromres.2016.04.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2016] [Revised: 04/08/2016] [Accepted: 04/22/2016] [Indexed: 11/18/2022]
Abstract
INTRODUCTION We describe a family with two first-degree cousins who presented with similar phenotypes characterized by neonatal intracranial hemorrhage and subsequent onset of thrombosis. PATIENTS/METHODS We enrolled the two affected patients, five unaffected family members and fifty-five normal controls. Clinical, laboratory, and radiological characteristics of patients were obtained. Exome sequencing was performed for the older affected child. PROC c.811 C>T was genotyped by PCR in patients, family members, and controls. Protein C amidolytic activity and antigen were measured using the STACHROM® protein C kit and ELISAs. To define functional abnormalities caused by the patients' mutation, recombinant wildtype protein C and its mutants R229W, R229Q and R229A were studied. RESULTS For the two cousins, protein C amidolytic activity was 61% and 59% and antigen was 57% and 73% (nl 70-140%), respectively. Exome sequencing revealed a homozygous variant in exon 9 of the protein C (PROC) gene c.811 C>T (R229W). The R229W mutation is located in the calcium binding loop of protein C's protease domain that mediates thrombomodulin interactions. Recombinant R229W-protein C mutant was strikingly defective in rate of activation by thrombin: thrombomodulin, suggesting an in vivo deficit in these children for generation of activated protein C. CONCLUSIONS These cases emphasize that protein C and activated protein C are important in maintaining the integrity of the brain vascular endothelium in humans. Moreover, routine protein C assays utilizing snake venom protease fail to detect protein C mutants that are resistant to thrombin:thrombomodulin activation.
Collapse
Affiliation(s)
- Abdulrahman Alsultan
- Department of Pediatrics, College of Medicine, King Saud University, Riyadh, Saudi Arabia.
| | - Andrew J Gale
- Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, CA, USA
| | - Kadijah Kurban
- Department of Pediatrics, College of Medicine, King Saud University, Riyadh, Saudi Arabia
| | - Mohammed Khalifah
- Department of Pediatrics, College of Medicine, King Saud University, Riyadh, Saudi Arabia
| | - Fahad B Albadr
- Department of Radiology, College of Medicine, King Saud University, Riyadh, Saudi Arabia
| | - John H Griffin
- Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, CA, USA
| |
Collapse
|
19
|
The M358R variant of α(1)-proteinase inhibitor inhibits coagulation factor VIIa. Biochem Biophys Res Commun 2016; 470:710-713. [PMID: 26797521 DOI: 10.1016/j.bbrc.2016.01.069] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Accepted: 01/11/2016] [Indexed: 12/11/2022]
Abstract
The naturally occurring M358R mutation of the plasma serpin α1-proteinase inhibitor (API) changes both its cleavable reactive centre bond to Arg-Ser and the efficacy with which it inhibits different proteases, reducing the rate of inhibition of neutrophil elastase, and enhancing that of thrombin, factor XIa, and kallikrein, by several orders of magnitude. Although another plasma serpin with an Arg-Ser reactive centre, antithrombin (AT), has been shown to inhibit factor VIIa (FVIIa), no published data are available with respect to FVIIa inhibition by API M358R. Recombinant bacterially-expressed API M358R and plasma-derived AT were therefore compared using gel-based and kinetic assays of FVIIa integrity and activity. Under pseudo-first order conditions of excess serpin over protease, both AT and API M358R formed denaturation-resistant inhibitory complexes with FVIIa in reactions accelerated by TF; AT, but not API M358R, also required heparin for maximal activity. The second order rate constant for heparin-independent API M358R-mediated FVIIa inhibition was determined to be 7.8 ± 0.8 × 10(2) M(-1)sec(-1). We conclude that API M358R inhibits FVIIa by forming inhibitory complexes of the serpin type more rapidly than AT in the absence of heparin. The likely 20-fold excess of API M358R over AT in patient plasma during inflammation raises the possibility that it could contribute to the hemorrhagic tendencies manifested by rare individuals expressing this mutant serpin.
Collapse
|
20
|
Gierczak RF, Pepler L, Bhagirath V, Liaw PC, Sheffield WP. Alpha-1 proteinase inhibitor M358R reduces thrombin generation when displayed on the surface of cells expressing tissue factor. Thromb Res 2014; 134:1142-9. [PMID: 25242242 DOI: 10.1016/j.thromres.2014.09.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2014] [Revised: 08/27/2014] [Accepted: 09/02/2014] [Indexed: 10/24/2022]
Abstract
The M358R variant of alpha-1-proteinase inhibitor (API) is a potent soluble inhibitor of thrombin. Previously we engineered AR-API M358R, a membrane-bound form of this protein and showed that it inhibited exogenous thrombin when expressed on transfected cells lacking tissue factor (TF). To determine the suitability of AR-API M358R for gene transfer to vascular cells to limit thrombogenicity, we tested the ability of AR-API M358R to inhibit endogenous thrombin generated in plasma via co-expression co-expressing it on the surface of cells expressing TF. Transfected AR-API M358R formed inhibitory complexes with thrombin following exposure of recalcified, defibrinated plasma to TF on T24/83 cells, but discontinuously monitored thrombin generation was unaffected. Similarly, AR-API M358R expression did not reduce continuously monitored thrombin generation by T24/83 cell suspensions exposed to recalcified normal plasma in a Thrombogram-Thrombinoscope-type thrombin generation assay (TGA); in contrast, 1 μM hirudin variant 3 or soluble API M358R abolished thrombin generation. Gene transfer of TF to HEK 293 conferred the ability to support TF-dependent thrombin generation on HEK 293 cells. Co-transfection of HEK 293 cells with a 9:1 excess of DNA encoding AR-API M358R to that encoding TF reduced peak thrombin generation approximately 3-fold compared to controls. These in vitro results suggest that surface display of API M358R inhibits thrombin generation when the tethered serpin is expressed in excess of TF, and suggest its potential to limit thrombosis in appropriate vascular beds in animal models.
Collapse
Affiliation(s)
- Richard F Gierczak
- Department of Pathology and Molecular Medicine, McMaster University, Hamilton, Ontario, Canada
| | - Laura Pepler
- Department of Medicine, McMaster University, Hamilton, Ontario, Canada
| | - Vinai Bhagirath
- Department of Medicine, McMaster University, Hamilton, Ontario, Canada
| | - Patricia C Liaw
- Department of Medicine, McMaster University, Hamilton, Ontario, Canada
| | - William P Sheffield
- Department of Pathology and Molecular Medicine, McMaster University, Hamilton, Ontario, Canada; Canadian Blood Services, Centre for Innovation, Hamilton, Ontario, Canada.
| |
Collapse
|
21
|
Bhakta V, Gierczak RF, Sheffield WP. Expression screening of bacterial libraries of recombinant alpha-1 proteinase inhibitor variants for candidates with thrombin inhibitory capacity. J Biotechnol 2013; 168:373-81. [DOI: 10.1016/j.jbiotec.2013.10.011] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2013] [Revised: 10/03/2013] [Accepted: 10/07/2013] [Indexed: 11/30/2022]
|
22
|
Roddick LA, Bhakta V, Sheffield WP. Fusion of the C-terminal triskaidecapeptide of hirudin variant 3 to alpha1-proteinase inhibitor M358R increases the serpin-mediated rate of thrombin inhibition. BMC BIOCHEMISTRY 2013; 14:31. [PMID: 24215622 PMCID: PMC3830444 DOI: 10.1186/1471-2091-14-31] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/05/2013] [Accepted: 11/05/2013] [Indexed: 11/10/2022]
Abstract
BACKGROUND Alpha-1 proteinase inhibitor (API) is a plasma serpin superfamily member that inhibits neutrophil elastase; variant API M358R inhibits thrombin and activated protein C (APC). Fusing residues 1-75 of another serpin, heparin cofactor II (HCII), to API M358R (in HAPI M358R) was previously shown to accelerate thrombin inhibition over API M358R by conferring thrombin exosite 1 binding properties. We hypothesized that replacing HCII 1-75 region with the 13 C-terminal residues (triskaidecapeptide) of hirudin variant 3 (HV354-66) would further enhance the inhibitory potency of API M358R fusion proteins. We therefore expressed HV3API M358R (HV354-66 fused to API M358R) and HV3API RCL5 (HV354-66 fused to API F352A/L353V/E354V/A355I/I356A/I460L/M358R) API M358R) as N-terminally hexahistidine-tagged polypeptides in E. coli. RESULTS HV3API M358R inhibited thrombin 3.3-fold more rapidly than API M358R; for HV3API RCL5 the rate enhancement was 1.9-fold versus API RCL5; neither protein inhibited thrombin as rapidly as HAPI M358R. While the thrombin/Activated Protein C rate constant ratio was 77-fold higher for HV3API RCL5 than for HV3API M358R, most of the increased specificity derived from the API F352A/L353V/E354V/A355I/I356A/I460L API RCL 5 mutations, since API RCL5 remained 3-fold more specific than HV3API RCL5. An HV3 54-66 peptide doubled the Thrombin Clotting Time (TCT) and halved the binding of thrombin to immobilized HCII 1-75 at lower concentrations than free HCII 1-75. HV3API RCL5 bound active site-inhibited FPR-chloromethyl ketone-thrombin more effectively than HAPI RCL5. Transferring the position of the fused HV3 triskaidecapeptide to the C-terminus of API M358R decreased the rate of thrombin inhibition relative to that mediated by HV3API M358R by 11-to 14-fold. CONCLUSIONS Fusing the C-terminal triskaidecapeptide of HV3 to API M358R-containing serpins significantly increased their effectiveness as thrombin inhibitors, but the enhancement was less than that seen in HCII 1-75-API M358R fusion proteins. HCII 1-75 was a superior fusion partner, in spite of the greater affinity of the HV3 triskaidecapeptide, manifested both in isolated and API-fused form, for thrombin exosite 1. Our results suggest that HCII 1-75 binds thrombin exosite 1 and orients the attached serpin scaffold for more efficient interaction with the active site of thrombin than the HV3 triskaidecapeptide.
Collapse
Affiliation(s)
| | | | - William P Sheffield
- Pathology and Molecular Medicine, McMaster University, 1280 Main Street West, Hamilton, ON L8S 4 K1, Canada.
| |
Collapse
|
23
|
Abstract
Injury-induced bleeding is stopped by a hemostatic plug formation that is controlled by a complex nonlinear and spatially heterogeneous biochemical network of proteolytic enzymes called blood coagulation. We studied spatial dynamics of thrombin, the central enzyme of this network, by developing a fluorogenic substrate-based method for time- and space-resolved imaging of thrombin enzymatic activity. Clotting stimulation by immobilized tissue factor induced localized thrombin activity impulse that propagated in space and possessed all characteristic traits of a traveling excitation wave: constant spatial velocity, constant amplitude, and insensitivity to the initial stimulation once it exceeded activation threshold. The parameters of this traveling wave were controlled by the availability of phospholipids or platelets, and the wave did not form in plasmas from hemophilia A or C patients who lack factors VIII and XI, which are mediators of the two principal positive feedbacks of coagulation. Stimulation of the negative feedback of the protein C pathway with thrombomodulin produced nonstationary patterns of wave formation followed by deceleration and annihilation. This indicates that blood can function as an excitable medium that conducts traveling waves of coagulation.
Collapse
|
24
|
Sutherland JS, Bhakta V, Sheffield WP. Investigating serpin-enzyme complex formation and stability via single and multiple residue reactive centre loop substitutions in heparin cofactor II. Thromb Res 2009; 117:447-61. [PMID: 15869786 DOI: 10.1016/j.thromres.2005.03.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2005] [Revised: 03/04/2005] [Accepted: 03/20/2005] [Indexed: 11/26/2022]
Abstract
INTRODUCTION Following thrombin cleavage of the reactive centre (P1-P1'; L444-S445) of the serpin heparin cofactor II (HCII), HCII traps thrombin (IIa) in a stable inhibitory complex. To compare HCII to other serpins we substituted: the P13-P5' residues of HCII with those of alpha(1)-proteinase inhibitor (alpha(1)-PI), alpha(1)-PI (M358R), or antithrombin (AT); the P4-P1, P3-P1, and P2-P1 residues of HCII with those of AT; and made L444A/H/K/M or R point mutations. We also combined L444R with changes in the glycosaminoglycan binding domain collectively termed MutD. MATERIALS AND METHODS Variants were made by site-directed mutagenesis, expressed in bacteria, purified and characterized electrophoretically and kinetically. RESULTS AND CONCLUSIONS Of the P13-P5' mutants, only the alpha(1)-PI-loop variant retained anti-IIa activity, but less than the corresponding L444M. Heparin-catalyzed rate constants for IIa inhibition were reduced vs. wild-type (WT) by at most three-fold for all P1 mutants save L444A (reduced 20-fold). L444R and L444K inhibited IIa>50- and >6-fold more rapidly than WT in heparin-free reactions, but stoichiometries of inhibition were increased for all variants. HCII-IIa complexes of all P1 variants were stable in the absence of heparin, but those of the L444K and L444R variants released active IIa over time with heparin. Limited proteolysis of these two groups of HCII-IIa complexes produced different fragmentation patterns consistent with conformational differences. The combination of either substituted AT residues at P2, P3, and P4, or the MutD mutations with L444R resulted in complex instability with or without heparin. This is the first description of HCII-IIa complexes of transient stability forming in the absence of heparin, and may explain the extent to which the reactive centre loop of HCII differs from that of AT.
Collapse
|
25
|
Anand M, Rajagopal K, Rajagopal KR. A model for the formation, growth, and lysis of clots in quiescent plasma. A comparison between the effects of antithrombin III deficiency and protein C deficiency. J Theor Biol 2008; 253:725-38. [PMID: 18539301 DOI: 10.1016/j.jtbi.2008.04.015] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2007] [Revised: 03/18/2008] [Accepted: 04/09/2008] [Indexed: 11/15/2022]
Abstract
A mathematical model comprised of 23 reaction-diffusion equations is used to simulate the biochemical changes and transport of various reactants involved in coagulation and fibrinolysis in quiescent plasma. The growth and lysis of a thrombus, as portrayed by the model equations, is governed by boundary conditions that include the surface concentration of TF-VIIa, the generation of XIa by contact activation (in vitro), and the secretion of tPA due to endothelial activation. We apply the model to two clinically relevant hypercoagulable states, caused by deficiency of either antithrombin III or protein C. These predictions are compared with published experimental data which validate the utility of the developed model under the special case of static conditions. The incorporation of varying hemodynamic conditions in to the current fluid static model remains to be performed.
Collapse
Affiliation(s)
- M Anand
- Department of Mechanical Engineering, Texas A&M University, College Station, TX 77843, USA
| | | | | |
Collapse
|
26
|
Redirection of the reaction between activated protein C and a serpin to the substrate pathway. Thromb Res 2008; 122:397-404. [DOI: 10.1016/j.thromres.2007.10.012] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2007] [Revised: 09/13/2007] [Accepted: 10/23/2007] [Indexed: 11/19/2022]
|
27
|
Abstract
Hemostasis and fibrinolysis, the biological processes that maintain proper blood flow, are the consequence of a complex series of cascading enzymatic reactions. Serine proteases involved in these processes are regulated by feedback loops, local cofactor molecules, and serine protease inhibitors (serpins). The delicate balance between proteolytic and inhibitory reactions in hemostasis and fibrinolysis, described by the coagulation, protein C and fibrinolytic pathways, can be disrupted, resulting in the pathological conditions of thrombosis or abnormal bleeding. Medicine capitalizes on the importance of serpins, using therapeutics to manipulate the serpin-protease reactions for the treatment and prevention of thrombosis and hemorrhage. Therefore, investigation of serpins, their cofactors, and their structure-function relationships is imperative for the development of state-of-the-art pharmaceuticals for the selective fine-tuning of hemostasis and fibrinolysis. This review describes key serpins important in the regulation of these pathways: antithrombin, heparin cofactor II, protein Z-dependent protease inhibitor, alpha(1)-protease inhibitor, protein C inhibitor, alpha(2)-antiplasmin and plasminogen activator inhibitor-1. We focus on the biological function, the important structural elements, their known non-hemostatic roles, the pathologies related to deficiencies or dysfunction, and the therapeutic roles of specific serpins.
Collapse
Affiliation(s)
- J C Rau
- Department of Pathology and Laboratory Medicine, Carolina Cardiovascular Biology Center, School of Medicine, University of North Carolina, Chapel Hill, NC 27599-7035, USA.
| | | | | | | |
Collapse
|
28
|
Tanaka KA, Szlam F, Levy JH. The effect of aprotinin on activated protein C-mediated downregulation of endogenous thrombin generation. Br J Haematol 2006; 134:77-82. [PMID: 16803571 DOI: 10.1111/j.1365-2141.2006.06099.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Thrombin plays a central role in coagulation and haemostasis. Binding of thrombin to thrombomodulin generates activated protein C (APC), which exerts a negative feedback on thrombin formation. Aprotinin, a natural proteinase inhibitor is used extensively during cardiac surgery because this procedure is often associated with profound activation of coagulation and inflammatory pathways. Some in vitro evidences suggest that aprotinin inhibits APC, but the clinical relevance is unclear. The recombinant human soluble thrombomodulin (rhsTM)-modified thrombin generation (TG) assay was used to investigate the effects of aprotinin on APC in plasma samples obtained from healthy volunteers, aprotinin-treated cardiac surgical patients and in protein C (PC)-depleted plasma. Based on the results of in vitro TG assay, addition of rhsTM (0.75-3.0 microg/ml) to volunteer or patient platelet-poor plasma significantly reduced (70.8 +/- 21.9 and 95.3% +/- 4.6%, respectively) thrombin formation when compared with PC-depleted plasma (8.3% +/- 5.2%). Aprotinin (100-200 KIU) caused a small, statistically insignificant decrease in the peak thrombin formation in normal and PC-deficient plasma (12.0 +/- 6.1%). In cardiac surgical patients, levels of functional PC, factor II, antithrombin and platelet significantly decreased after cardiopulmonary bypass (CPB). Soluble thrombomodulin concentrations were increased after CPB (3.5 +/- 2.2 to 5.0 +/- 2.2 ng/ml), but they were still within the normal range for human plasma. Our results showed that, even though endogenous PC level is decreased after CPB, it retains its activity in the presence of thrombomodulin, and aprotinin has limited inhibitory effect on APC generation.
Collapse
Affiliation(s)
- Kenichi A Tanaka
- Department of Anesthesiology, Emory University School of Medicine, Atlanta, GA, USA.
| | | | | |
Collapse
|
29
|
Abstract
Coagulation serine proteases signal through protease-activated receptors (PARs). Thrombin-dependent PAR signaling on platelets is essential for the hemostatic response and vascular thrombosis, but regulation of inflammation by PAR signaling is now recognized as an important aspect of the pro- and anti-coagulant pathways. In tissue factor (TF)-dependent initiation of coagulation, factor (F) Xa is the PAR-1 or PAR-2-activating protease when associated with the transient TF-FVIIa-FXa complex. In the anticoagulant protein C (PC) pathway, the thrombin-thrombomodulin complex activates PC bound to the endothelial cell PC receptor (EPCR), which functions as a required coreceptor for activated PC-mediated signaling through endothelial cell PAR-1. Thus, the pro- and anti-inflammatory receptor cascades are mechanistically coupled to immediate cell signaling, which precedes systemic coagulant or anticoagulant effects. In contrast to the substrate-like recognition of PARs by thrombin, TF- or EPCR-targeted activation of PARs generates cell-type specificity, PAR selectivity and protease receptor cosignaling with the G-protein-coupled PAR response. Protease receptors are thus major determinants of the biological outcome of coagulation factor signaling on vascular cells.
Collapse
Affiliation(s)
- W Ruf
- Department of Immunology, The Scripps Research Institute, La Jolla, CA 92037, USA.
| | | | | |
Collapse
|
30
|
Glasscock LN, Gerlitz B, Cooper ST, Grinnell BW, Church FC. Basic residues in the 37-loop of activated protein C modulate inhibition by protein C inhibitor but not by alpha(1)-antitrypsin. BIOCHIMICA ET BIOPHYSICA ACTA 2003; 1649:106-17. [PMID: 12818196 DOI: 10.1016/s1570-9639(03)00164-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The role of lysines 37-39 (chymotrypsin numbering) in the 37-loop of the serine protease activated protein C (APC) was studied by expressing acidic and neutral recombinant APC (rAPC) mutants. Activity of the APC mutants was assessed using human plasma and plasma-purified and recombinant derivatives of protein C inhibitor (PCI; also known as plasminogen activator inhibitor-3) and alpha(1)-antitrypsin, with and without heparin. The catalytic properties of the mutants to small peptidyl substrates were essentially the same as wild-type rAPC (wt-rAPC), yet their plasma anticoagulant activities were diminished. Analysis of the rAPC-protease inhibitor complexes formed after addition of wt-rAPC and mutants to plasma revealed no change in the inhibition pattern by alpha(1)-antitrypsin but a reduction in mutant complex formation by PCI in the presence of heparin. Using purified serpins, we found that inhibition rates of the mutants were the same as wt-rAPC with alpha(1)-antitrypsin; however, PCI (plasma-derived and recombinant forms) inhibition rates of the acidic mutants were slightly faster than that of wt-rAPC without heparin. By contrast, PCI-heparin inhibition rates of the mutants were not substantially accelerated compared to wt-rAPC. The mutants had reduced heparin-binding properties compared to wt-rAPC. Molecular modeling of the PCI-APC complex with heparin suggests that heparin may function not only to bridge PCI to APC, but also to alleviate putative non-optimal intermolecular interactions. Our results suggest that the basic residues of the 37-loop of APC are involved in macromolecular substrate interactions and in heparin binding, and they influence inhibition by PCI (with or without heparin) but not by alpha(1)-antitrypsin, two important blood plasma serpins.
Collapse
Affiliation(s)
- Laura N Glasscock
- Department of Pathology, Center for Thrombosis and Hemostasis, The University of North Carolina School of Medicine, Chapel Hill, NC 27599-7035, USA
| | | | | | | | | |
Collapse
|
31
|
Berg DT, Gerlitz B, Shang J, Smith T, Santa P, Richardson MA, Kurz KD, Grinnell BW, Mace K, Jones BE. Engineering the proteolytic specificity of activated protein C improves its pharmacological properties. Proc Natl Acad Sci U S A 2003; 100:4423-8. [PMID: 12671072 PMCID: PMC153571 DOI: 10.1073/pnas.0736918100] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Human activated protein C (APC) is an antithrombotic, antiinflammatory serine protease that plays a central role in vascular homeostasis, and activated recombinant protein C, drotrecogin alfa (activated), has been shown to reduce mortality in patients with severe sepsis. Similar to other serine proteases, functional APC levels are regulated by the serine protease inhibitor family of proteins including alpha(1)-antitrypsin and protein C inhibitor. Using APC-substrate modeling, we designed and produced a number of derivatives with the goal of altering the proteolytic specificity of APC such that the variants exhibited resistance to inactivation by protein C inhibitor and alpha(1)-antitrypsin yet maintained their primary anticoagulant activity. Substitutions at Leu-194 were of particular interest, because they exhibited 4- to 6-fold reductions in the rate of inactivation in human plasma and substantially increased pharmacokinetic profiles compared with wild-type APC. This was achieved with minimal impairment of the anticoagulant/antithrombotic activity of APC. These data demonstrate the ability to selectively modulate substrate specificity and subsequently affect in vivo performance and suggest therapeutic opportunities for the use of protein C derivatives in disease states with elevated serine protease inhibitor levels.
Collapse
Affiliation(s)
- David T Berg
- Division of BioResearch Technologies and Proteins, Lilly Research Laboratories, Lilly Corporate Center, Indianapolis, IN 46285, USA
| | | | | | | | | | | | | | | | | | | |
Collapse
|
32
|
Sulikowski T, Bauer BA, Patston PA. alpha(1)-Proteinase inhibitor mutants with specificity for plasma kallikrein and C1s but not C1. Protein Sci 2002; 11:2230-6. [PMID: 12192078 PMCID: PMC2373593 DOI: 10.1110/ps.0207302] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Coagulation and complement proteinases are activated in sepsis, and one approach to therapy is to develop proteinase inhibitors that will specifically inhibit these proteinases without inhibiting activated protein C, a proteinase that is beneficial to survival. In this study, we made mutants of the serpin alpha(1)-PI, designed to mimic the specificity of C1-inhibitor. The P3-P2-P1 residues of alpha1-PI were changed from IPM to LGR and PFR, sequences preferred by C1s and kallikrein, respectively. Inhibition of C1s, kallikrein, factor XIIa, and activated protein C was assessed by SDS-PAGE, and by determination of the k(app) and SI. alpha(1)-PI-LGR inhibited C1s with a rate of 7790 M(-1)s(-1), but only minimal inhibition of C1 in a hemolytic assay was observed. Kallikrein, factor XIIa, and activated protein C were inhibited with rates of 382,180 M(-1)s(-1), 10,400 M(-1)s(-1), and 3500 M(-1)s(-1), respectively. alpha(1)-PI-PFR was a poor inhibitor of C1s, factor XIIa, and activated protein C, but had enhanced reactivity with kallikrein. Changing the P4' residue of alpha(1)-PI-LGR Pro to Glu reduced the activity with C1s, consistent with the idea that C1s requires hydrophobic residues in this region of the serpin for optimal interaction. The data provide insight into the requirements for kallikrein and C1s inhibition necessary for designing inhibitors with appropriate properties for further investigation as therapeutic agents.
Collapse
Affiliation(s)
- Thomas Sulikowski
- Department of Oral Medicine and Diagnostic Sciences, University of Illinois at Chicago, Chicago, Illinois 60612, USA
| | | | | |
Collapse
|
33
|
Gale AJ, Tsavaler A, Griffin JH. Molecular characterization of an extended binding site for coagulation factor Va in the positive exosite of activated protein C. J Biol Chem 2002; 277:28836-40. [PMID: 12063259 DOI: 10.1074/jbc.m204363200] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The anticoagulant human plasma serine protease, activated protein C (APC), inhibits blood coagulation by specific inactivation of the coagulation cofactors factor Va (FVa) and factor VIIIa. Site-directed mutagenesis of residues in three surface loops of a positive exosite located on APC was used to identify residues that play a significant role in binding to FVa. Eighteen different residues were mutated to alanine singly, in pairs, or in triple mutation combinations. Mutant APC proteins were purified and characterized for their inactivation of FVa. Three APC residues were identified that provide major contributions to FVa interactions: Lys(193), Arg(229), and Arg(230). In addition, four residues made significant minor contributions to FVa interactions: Lys(191), Lys(192), Asp(214), and Glu(215). All of these residues primarily contribute to APC cleavage at Arg(506) in FVa and play a small role in the interaction of APC with the Arg(306) cleavage site. In conjunction with previously published work, these results define an extensive FVa binding site in the positive exosite of APC that is primarily involved in binding and cleaving at Arg(506) on FVa.
Collapse
Affiliation(s)
- Andrew J Gale
- Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, California 92037, USA.
| | | | | |
Collapse
|
34
|
Rezaie AR. Vitronectin functions as a cofactor for rapid inhibition of activated protein C by plasminogen activator inhibitor-1. Implications for the mechanism of profibrinolytic action of activated protein C. J Biol Chem 2001; 276:15567-70. [PMID: 11264280 DOI: 10.1074/jbc.c100123200] [Citation(s) in RCA: 104] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Activated protein C (APC) is a natural anticoagulant in plasma that down-regulates the coagulation cascade by degrading factors Va and VIIIa. In addition to its anticoagulant function, APC is also known to possess a profibrinolytic property. This property of APC has been attributed to its ability to neutralize PAI-1, thereby increasing the concentration of tissue plasminogen activator in plasma leading to up-regulation of the fibrinolytic cascade. This hypothesis, however, has not been well established, since the concentration of PAI-1 in plasma is low, and its reactivity with APC is very slow in a purified system. Here we demonstrate that vitronectin enhances the reactivity of PAI-1 with APC approximately 300-fold making PAI-1 the most efficient inhibitor of APC thus far reported (k(2) = 1.8 x 10(5) m(-)1 s(-)1). We further show that PAI-1 inhibition of the Glu(192) --> Gln mutant of APC is enhanced approximately 40-fold, independent of vitronectin, suggesting that vitronectin partially overcomes the inhibitory interaction of PAI-1 with Glu(192). Additionally, we show that PAI-1 inhibition of the Lys(37)-Lys(38)-Lys(39) --> Pro-Gln-Glu mutant of APC is severely impaired, suggesting that, similar to tissue plasminogen activator, the basic 39-loop of APC plays a critical role in the reaction. Together, these results suggest that vitronectin functions as a cofactor to promote the profibrinolytic activity of APC.
Collapse
Affiliation(s)
- A R Rezaie
- Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, Saint Louis, Missouri 63104, USA.
| |
Collapse
|
35
|
The autolysis loop of activated protein C interacts with factor Va and differentiates between the Arg506 and Arg306 cleavage sites. Blood 2000. [DOI: 10.1182/blood.v96.2.585.014k30_585_593] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The anticoagulant human plasma serine protease, activated protein C (APC), inactivates blood coagulation factors Va (FVa) and VIIIa. The so-called autolysis loop of APC (residues 301-316, equivalent to chymotrypsin [CHT] residues 142-153) has been hypothesized to bind FVa. In this study, site-directed mutagenesis was used to probe the role of the charged residues in this loop in interactions between APC and FVa. Residues Arg306 (147 CHT), Glu307, Lys308, Glu309, Lys311, Arg312, and Arg314 were each individually, or in selected combinations, mutated to Ala. The purified recombinant protein C mutants were characterized using activated partial thromboplastin time (APTT) clotting assays and FVa inactivation assays. Mutants 306A, 308A, 311A, 312A, and 314A had mildly reduced anticoagulant activity. Based on FVa inactivation assays and APTT assays using purified Gln506-FVa and plasma containing Gln506-FV, it appeared that these mutants were primarily impaired for cleavage of FVa at Arg506. Studies of the quadruple APC mutant (306A, 311A, 312A, and 314A) suggested that the autolysis loop provides for up to 15-fold discrimination of the Arg506 cleavage site relative to the Arg306 cleavage site. This study shows that the loop on APC of residues 306 to 314 defines an FVa binding site and accounts for much of the difference in cleavage rates at the 2 major cleavage sites in FVa.
Collapse
|
36
|
The autolysis loop of activated protein C interacts with factor Va and differentiates between the Arg506 and Arg306 cleavage sites. Blood 2000. [DOI: 10.1182/blood.v96.2.585] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
AbstractThe anticoagulant human plasma serine protease, activated protein C (APC), inactivates blood coagulation factors Va (FVa) and VIIIa. The so-called autolysis loop of APC (residues 301-316, equivalent to chymotrypsin [CHT] residues 142-153) has been hypothesized to bind FVa. In this study, site-directed mutagenesis was used to probe the role of the charged residues in this loop in interactions between APC and FVa. Residues Arg306 (147 CHT), Glu307, Lys308, Glu309, Lys311, Arg312, and Arg314 were each individually, or in selected combinations, mutated to Ala. The purified recombinant protein C mutants were characterized using activated partial thromboplastin time (APTT) clotting assays and FVa inactivation assays. Mutants 306A, 308A, 311A, 312A, and 314A had mildly reduced anticoagulant activity. Based on FVa inactivation assays and APTT assays using purified Gln506-FVa and plasma containing Gln506-FV, it appeared that these mutants were primarily impaired for cleavage of FVa at Arg506. Studies of the quadruple APC mutant (306A, 311A, 312A, and 314A) suggested that the autolysis loop provides for up to 15-fold discrimination of the Arg506 cleavage site relative to the Arg306 cleavage site. This study shows that the loop on APC of residues 306 to 314 defines an FVa binding site and accounts for much of the difference in cleavage rates at the 2 major cleavage sites in FVa.
Collapse
|
37
|
Petäjä J, Fernández JA, Fellman V, Griffin JH. Upregulation of the antithrombotic protein C pathway at birth. Pediatr Hematol Oncol 1998; 15:489-99. [PMID: 9842642 DOI: 10.3109/08880019809018310] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Serious thrombotic complications occur in sick neonates, while healthy infants have a very low risk of thrombosis. To better understand the regulation of physiological anticoagulation at birth, components of the protein C pathway were measured in cord plasma samples from 14 full-term healthy newborns and in samples from 10 adult controls. Although zymogen protein C was significantly reduced in cord plasma (mean +/- SEM in cord vs. adult sample 37 +/- 1.4% vs. 90 +/- 5.5%, p < 0.0001), levels of the active enzyme, activated protein C (APC), were not (119 +/- 20% vs. 75 +/- 12%, p = 0.0762). Relative to the protein C level, cord plasmas had a 5.2-fold higher APC level (p < 0.01). The APC increase was partially due to slower inactivation of APC in cord plasma (half-life for APC 50 min in cord plasma vs. 27 minutes in adult plasma). Increased sensitivity of factor V to inactivation by APC in cord plasma was observed since the activated partial thromboplastin time-based APC sensitivity ratio was significantly increased for cord vs. adult plasma samples (2.28 +/- 0.09 versus 1.97 +/- 0.03, p < 0.01). Thus, despite low zymogen protein C, the protein C pathway in newborns seems to be functionally well developed and at an activated stage at birth.
Collapse
Affiliation(s)
- J Petäjä
- Department of Molecular, Scripps Research Institute, La Jolla, California, USA.
| | | | | | | |
Collapse
|
38
|
Elisen M, Bouma B, Church F, Meijers J. Inhibition of serine proteases by reactive site mutants of protein C inhibitor (plasminogen activator inhibitor-3). ACTA ACUST UNITED AC 1998. [DOI: 10.1016/s0268-9499(98)80021-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
|
39
|
Gale AJ, Sun X, Heeb MJ, Griffin JH. Nonenzymatic anticoagulant activity of the mutant serine protease Ser360Ala-activated protein C mediated by factor Va. Protein Sci 1997; 6:132-40. [PMID: 9007985 PMCID: PMC2143509 DOI: 10.1002/pro.5560060115] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The human plasma serine protease, activated protein C (APC), primarily exerts its anticoagulant function by proteolytic inactivation of the blood coagulation cofactors Va and VIIIa. A recombinant active site Ser 360 to Ala mutation of protein C was prepared, and the mutant protein was expressed in human 293 kidney cells and purified. The activation peptide of the mutant protein C zymogen was cleaved by a snake venom activator, Protac C, but the "activated" S360A APC did not have amidolytic activity. However, it did exhibit significant anticoagulant activity both in clotting assays and in a purified protein assay system that measured prothrombinase activity. The S360A APC was compared to plasma-derived and wild-type recombinant APC. The anticoagulant activity of the mutant, but not native APC, was resistant to diisopropyl fluorophosphate, whereas all APCs were inhibited by monoclonal antibodies against APC. In contrast to native APC, S360A APC was not inactivated by serine protease inhibitors in plasma and did not bind to the highly reactive mutant protease inhibitor M358R alpha 1 antitrypsin. Since plasma serpins provide the major mechanism for inactivating APC in vivo, this suggests that S360A APC would have a long half-life in vivo, with potential therapeutic advantages. S360A APC rapidly inhibited factor Va in a nonenzymatic manner since it apparently did not proteolyze factor Va. These data suggest that native APC may exhibit rapid nonenzymatic anticoagulant activity followed by enzymatic irreversible proteolysis of factor Va. The results of clotting assays and prothrombinase assays showed that S360A APC could not inhibit the variant Gln 506-FVa compared with normal Arg 506-FVa, suggesting that the active site of S360A APC binds to FVa at or near Arg 506.
Collapse
Affiliation(s)
- A J Gale
- Department of Molecular and Experimental Medicine, Scripps Research Institute, La Jolla, California 92037, USA
| | | | | | | |
Collapse
|
40
|
Lomas DA, Stone SR, Llewellyn-Jones C, Keogan MT, Wang ZM, Rubin H, Carrell RW, Stockley RA. The control of neutrophil chemotaxis by inhibitors of cathepsin G and chymotrypsin. J Biol Chem 1995; 270:23437-43. [PMID: 7559504 DOI: 10.1074/jbc.270.40.23437] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Neutrophil chemotaxis plays an important role in the inflammatory response and when excessive or persistent may augment tissue damage. The effects of inhibitors indicated the involvement of one or more serine proteinases in human neutrophil migration and shape change in response to a chemoattractant. Monospecific antibodies, chloromethylketone inhibitors, and reactive-site mutants of alpha 1-antitrypsin and alpha 1-antichymotrypsin were used to probe the specificity of the proteinases involved in chemotaxis. Antibodies specific for cathepsin G inhibited chemotaxis. Moreover, rapid inhibitors of cathepsin G and alpha-chymotrypsin suppressed neutrophil chemotaxis to the chemoattractants N-formyl-L-methionyl-L-leucyl-L-phenylalanine (fMLP) and zymosan-activated serum in multiple blind well assays and to fMLP in migration assays under agarose. The concentrations of antichymotrypsin mutants that reduced chemotaxis by 50% would inactivate free cathepsin G with a half-life of 1.5-3 s, whereas the concentrations of chloromethylketones required to produce a similar inhibition of chemotaxis would inactivate cathepsin G with a half-life of 345 s. These data suggest different modes of action for these two classes of inhibitors. Indeed the chloromethylketone inhibitors of cathepsin G (Z-Gly-Leu-Phe-CMK) and to a lesser extent of chymotrypsin (Cbz-Gly-Gly-Phe-CMK) mediated their effect by preventing a shape change in the purified neutrophils exposed to fMLP. Antichymotrypsin did not affect shape change in response to fMLP even at concentrations that were able to reduce neutrophil chemotaxis by 50%. These results support the involvement of cell surface proteinases in the control of cell migration and show that antichymotrypsin and chloromethylketones have differing modes of action. This opens the possibility for the rational design of anti-inflammatory agents targeted at neutrophil membrane enzymes.
Collapse
Affiliation(s)
- D A Lomas
- Department of Medicine, University of Cambridge, United Kingdom
| | | | | | | | | | | | | | | |
Collapse
|
41
|
Hopkins PC, Crowther DC, Carrell RW, Stone SR. Development of a novel recombinant serpin with potential antithrombotic properties. J Biol Chem 1995; 270:11866-71. [PMID: 7744836 DOI: 10.1074/jbc.270.20.11866] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Recombinant alpha 1-antitrypsin with a P1 arginine residue (Arg-alpha 1-antitrypsin) is a rapid inhibitor of both thrombin and activated protein C (APC). A series of mutants were made in an attempt to increase the specificity of this serpin for thrombin over APC. Initially, P2 and P'1 residues of Arg-alpha 1-antitrypsin were replaced in single and double mutations by the corresponding residues in antithrombin and C1 inhibitor which are very poor inhibitors of APC. No improvement in selectivity was achieved by these mutations. In fact, all P2/P'1 substitutions led to a decrease in selectivity for thrombin over APC. For example, replacement of the P2 proline of Arg-alpha 1-antitrypsin by glycine decreased the association rate constant (kass) with thrombin by 37-fold while the kass value with APC was reduced by only 16-fold. Cooperative effects were observed with the double P2 and P'1 substitutions; the mutational effects were not additive. The decrease in the kass for thrombin caused by the mutation of the P2 proline to alanine or glycine was 3-fold greater when threonine was present in the P'1 position instead of the normal serine. In contrast to the disappointing results with the P2/P'1 mutations, replacement of the P7 to P'3 residues of alpha 1-antitrypsin by those of antithrombin led to a dramatic increase in selectivity. Although this substitution only affected the kass value with thrombin by 10-fold, a 12,500-fold decrease in this value with APC was observed. Substitution of proline for the P2 glycine of this chimeric serpin increased the kass values with thrombin and APC by 7- and 90-fold, respectively. The effect of the P2 substitution was again found to depend on the sequence surrounding the residue; the change in the kass for APC caused by the P2 Pro-->Gly replacement was 6-fold larger in the chimeric serpin. Evaluation of the kass values of the chimeric serpin with a P2 proline in light of the likely rates of inhibition of thrombin and APC during antithrombotic therapy with heparin suggested that this serpin may have kinetic parameters suitable for an antithrombotic agent.
Collapse
Affiliation(s)
- P C Hopkins
- Department of Haematology, University of Cambridge, United Kingdom
| | | | | | | |
Collapse
|
42
|
Cooper ST, Church FC. Reactive site mutants of recombinant protein C inhibitor. BIOCHIMICA ET BIOPHYSICA ACTA 1995; 1246:29-33. [PMID: 7811727 DOI: 10.1016/0167-4838(94)00185-j] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Protein C inhibitor (PCI) is a heparin-binding serine proteinase inhibitor (serpin) which is thought to be a physiological regulator of activated protein C (APC). The residues F353-R354-S355 (P2-P1-P1') constitute part of the reactive site loop of PCI with the R-S peptide bond being cleaved by the proteinase. Changing the reactive site P1 and P2 residues to those of either proteinase nexin-1, alpha 1-proteinase inhibitor or heparin cofactor II resulted in a decrease in inhibitory activity towards thrombin and APC. Changing the P2 residue F353-->P generated a rPCI which was a better thrombin inhibitor, but was 10-fold less active with APC. While these results support the concept that the P1 and P2 residues are important in the specificity of PCI, they suggest that the reactive site residues are not the only determinant of serpin specificity. Kinetic analysis of the rPCI variants was consistent with PCI operating by a mechanism similar to that proposed for other serpins. In this model an intermediary complex forms between inhibitor and proteinase that can proceed to either cleavage of the inhibitor as substrate or formation of an inactive complex.
Collapse
Affiliation(s)
- S T Cooper
- Department of Pathology, University of North Carolina School of Medicine, Chapel Hill 27599-7035
| | | |
Collapse
|
43
|
Phillips J, Cooper S, Potter E, Church F. Mutagenesis of recombinant protein C inhibitor reactive site residues alters target proteinase specificity. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(19)89446-2] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
|
44
|
Anderson ED, Thomas L, Hayflick JS, Thomas G. Inhibition of HIV-1 gp160-dependent membrane fusion by a furin-directed alpha 1-antitrypsin variant. J Biol Chem 1993. [DOI: 10.1016/s0021-9258(19)74548-7] [Citation(s) in RCA: 152] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
|
45
|
Mesters RM, Heeb MJ, Griffin JH. Interactions and inhibition of blood coagulation factor Va involving residues 311-325 of activated protein C. Protein Sci 1993; 2:1482-9. [PMID: 8401232 PMCID: PMC2142455 DOI: 10.1002/pro.5560020912] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Activated protein C (APC) exerts its physiologic anticoagulant role by proteolytic inactivation of the blood coagulation cofactors Va and VIIIa. The synthetic peptide-(311-325) (KRNRTFVLNFIKIPV), derived from the heavy chain sequence of APC, potently inhibited APC anticoagulant activity in activated partial thromboplastin time (APTT) and Xa-1-stage coagulation assays in normal and in protein S-depleted plasma with 50% inhibition at 13 microM peptide. In a system using purified clotting factors, peptide-(311-325) inhibited APC-catalyzed inactivation of factor Va in the presence or absence of phospholipids with 50% inhibition at 6 microM peptide. However, peptide-(311-325) had no effect on APC amidolytic activity or on the reaction of APC with the serpin, recombinant [Arg358]alpha 1-antitrypsin. Peptide-(311-325) surprisingly inhibited factor Xa clotting activity in normal plasma, and in a purified system it inhibited prothrombinase activity in the presence but not in the absence of factor Va with 50% inhibition at 8 microM peptide. The peptide had no significant effect on factor Xa or thrombin amidolytic activity and no effect on the clotting of purified fibrinogen by thrombin, suggesting it does not directly inhibit these enzymes. Factor Va bound in a dose-dependent manner to immobilized peptide-(311-325). Peptide-(311-315) inhibited the binding of factor Va to immobilized APC or factor Xa.(ABSTRACT TRUNCATED AT 250 WORDS)
Collapse
Affiliation(s)
- R M Mesters
- Department of Molecular and Experimental Medicine, Scripps Research Institute, La Jolla, California 92037
| | | | | |
Collapse
|
46
|
Richardson MA, Gerlitz B, Grinnell BW. Enhancing protein C interaction with thrombin results in a clot-activated anticoagulant. Nature 1992; 360:261-4. [PMID: 1436107 DOI: 10.1038/360261a0] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Human protein C is a vitamin K-dependent plasma glycoprotein that circulates as an inactive zymogen. At the endothelial cell surface, thrombin in complex with the integral membrane protein thrombomodulin converts protein C to its active form by specific cleavage of an activation peptide. The activated form of protein C has potent anticoagulant activity as a feedback regulator of thrombin generation (reviewed in refs 4-6), and also has profibrinolytic, anti-ischaemic and anti-inflammatory properties. Protein C is effective in the treatment of model and human thrombotic diseases but, except when it has been used to treat genetic or acquired deficiencies and microvascular thrombosis, it is administered as the activated enzyme, which has a short biological half-life. We have altered two putative inhibitory acidic residues near the thrombin cleavage site, which results in a 30-fold increase in substrate utilization by alpha-thrombin. We combined these changes with a genetically altered glycoform to generate a zymogen protein C with a 60-fold increased cleavage rate by free alpha-thrombin, independent of its cofactor thrombomodulin. We show that this 'proform' of protein C, unlike the natural circulating zymogen, can be activated by thrombin generated in clotting human plasma, resulting in an inhibition of further clot formation. Our data therefore show that we have engineered a site-activated agent, which only has anticoagulant activity when significant amounts of thrombin are being generated.
Collapse
Affiliation(s)
- M A Richardson
- Department of Cardiovascular Research, Lilly Research Laboratories, Indianapolis, Indiana 46285-0424
| | | | | |
Collapse
|
47
|
Mesters R, Houghten R, Griffin J. Identification of a sequence of human activated protein C (residues 390-404) essential for its anticoagulant activity. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(18)54259-9] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
|
48
|
Heeb M, Gruber A, Griffin J. Identification of divalent metal ion-dependent inhibition of activated protein C by alpha 2-macroglobulin and alpha 2-antiplasmin in blood and comparisons to inhibition of factor Xa, thrombin, and plasmin. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(19)47415-2] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
|
49
|
Glycosylation of human protein C affects its secretion, processing, functional activities, and activation by thrombin. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(18)92888-7] [Citation(s) in RCA: 110] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
|
50
|
Ragg H, Ulshöfer T, Gerewitz J. Glycosaminoglycan-mediated leuserpin-2/thrombin interaction. Structure-function relationships. J Biol Chem 1990. [DOI: 10.1016/s0021-9258(18)45717-1] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
|