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Wang Y, Li R. Specific O-glycans in the mechanosensory domain of glycoprotein Ibα are important for its stability and function. Haematologica 2023; 108:2526-2530. [PMID: 36779596 PMCID: PMC10483358 DOI: 10.3324/haematol.2022.281979] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Accepted: 01/30/2023] [Indexed: 02/11/2023] Open
Abstract
Not available.
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Affiliation(s)
- Yingchun Wang
- Aflac Cancer and Blood Disorders Center, Children's Healthcare of Atlanta, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA 30322
| | - Renhao Li
- Aflac Cancer and Blood Disorders Center, Children's Healthcare of Atlanta, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA 30322.
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2
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Arce NA, Liu Y, Chen W, Zhang XF, Li R. Autoinhibitory module underlies species difference in shear activation of von Willebrand factor. J Thromb Haemost 2022; 20:2686-2696. [PMID: 36031939 PMCID: PMC9588639 DOI: 10.1111/jth.15837] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2022] [Revised: 07/05/2022] [Accepted: 07/22/2022] [Indexed: 11/30/2022]
Abstract
BACKGROUND Von Willebrand factor (VWF) is a multimeric plasma protein that bridges the gap between vessel injury and platelet capture at high shear rates. Under high shear or tension, VWF can become activated upon the unfolding of its autoinhibitory module (AIM). AIM unfolding exposes the A1 domain, allowing for binding to platelet glycoprotein (GP)Ibα to initiate primary hemostasis. The characteristics of the AIM and its inhibitory properties within mouse VWF are unknown. OBJECTIVES To determine and characterize the autoinhibitory properties of mouse VWF. METHODS Recombinant mouse VWF A1 fragments containing or lacking the flanking regions around the A1 domain were generated. We tested the ability of these fragments to bind to human or mouse GPIbα and platelets. We compared the unfolding of mouse AIM-A1 to human AIM-A1 by single-molecule force spectroscopy. RESULTS Recombinant mouse AIM-A1 binds with higher affinity to GPIbα than its human counterpart. Recombinant mouse proteins lacking part of the AIM show increased binding to GPIbα. Activated A1 fragments lacking the AIM can effectively agglutinate platelets across the species barrier. Using single-molecule force spectroscopy, we determined that the mouse AIM unfolds under forces similar to the human AIM. Additionally, the human AIM paired with mouse A1 largely recapitulates the behavior of human AIM-A1. CONCLUSIONS Our results suggest that the regulation of VWF-GPIbα binding has been specifically tuned to work optimally in different rheological architectures. Differences in the AIM sequence may contribute to the difference in VWF shear response between human and mice.
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Affiliation(s)
- Nicholas A. Arce
- Aflac Cancer and Blood Disorders Center, Children’s Healthcare of Atlanta, Department of Pediatrics, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Yi Liu
- Department of Bioengineering, Lehigh University, Bethlehem, Pennsylvania, USA
| | - Wenchun Chen
- Aflac Cancer and Blood Disorders Center, Children’s Healthcare of Atlanta, Department of Pediatrics, Emory University School of Medicine, Atlanta, Georgia, USA
| | - X. Frank Zhang
- Department of Bioengineering, Lehigh University, Bethlehem, Pennsylvania, USA
| | - Renhao Li
- Aflac Cancer and Blood Disorders Center, Children’s Healthcare of Atlanta, Department of Pediatrics, Emory University School of Medicine, Atlanta, Georgia, USA
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3
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Chen W, Wilson MS, Wang Y, Bergmeier W, Lanza F, Li R. Fast clearance of platelets in a commonly used mouse model for GPIbα is impeded by an anti-GPIbβ antibody derivative. J Thromb Haemost 2022; 20:1451-1463. [PMID: 35305057 PMCID: PMC9133214 DOI: 10.1111/jth.15702] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Revised: 02/21/2022] [Accepted: 03/14/2022] [Indexed: 01/26/2023]
Abstract
BACKGROUND Glycoprotein (GP)Ibα plays a critical role in regulating platelet clearance. Recently, we identified the mechanosensory domain (MSD) in GPIbα and reported evidence to suggest that unfolding of the GPIbα MSD induces exposure of the Trigger sequence therein and subsequent GPIb-IX signaling that accelerates platelet clearance. In a commonly used transgenic mouse model, IL4R-IbαTg, where the Trigger sequence is constitutively exposed, constitutive GPIb-IX-mediated cellular signals are present. Clearance of their platelets is also significantly faster than that of wild-type mice. Previously, an anti-GPIbβ antibody RAM.1 was developed. RAM.1 inhibits GPIbα-dependent platelet signaling and activation. Further, RAM.1 also inhibits anti-GPIbα antibody-mediated filopodia formation. OBJECTIVE To investigate whether RAM.1 can ameliorate trigger sequence exposure-mediated platelet clearance. METHODS Spontaneous filopodia were measured by confocal microscopy. Other platelet signaling events were measured by flow cytometry. Endogenous platelet life span was tracked by Alexa 488-labeled anti-mouse GPIX antibody. RESULT Transfected Chinese hamster ovary cells stably expressing the same chimeric IL4R-Ibα protein complex as in IL4R-IbαTg mice also constitutively exhibit filopodia, and that such filopodia could be abolished by treatment of RAM.1. Further, transfusion of a recombinant RAM.1 derivative that is devoid of its Fc portion significantly extends the endogenous life span of IL4R-IbαTg platelets. CONCLUSION These results provide the key evidence supporting the causative link of Trigger sequence exposure to accelerated platelet clearance, and suggest that a RAM.1 derivative may be therapeutically developed to treat GPIb-IX-mediated thrombocytopenia.
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Affiliation(s)
- Wenchun Chen
- Aflac Cancer and Blood Disorders Center, Children’s Healthcare of Atlanta, Departments of Pediatrics, Emory University School of Medicine Atlanta, GA
| | - Moriah S. Wilson
- Aflac Cancer and Blood Disorders Center, Children’s Healthcare of Atlanta, Departments of Pediatrics, Emory University School of Medicine Atlanta, GA
| | - Yingchun Wang
- Aflac Cancer and Blood Disorders Center, Children’s Healthcare of Atlanta, Departments of Pediatrics, Emory University School of Medicine Atlanta, GA
| | - Wolfgang Bergmeier
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC
| | - Francois Lanza
- Université de Strasbourg, INSERM, BPPS UMR-S1255, Strasbourg, France
| | - Renhao Li
- Aflac Cancer and Blood Disorders Center, Children’s Healthcare of Atlanta, Departments of Pediatrics, Emory University School of Medicine Atlanta, GA
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4
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Overlapping and unique substrate specificities of ST3GAL1 and 2 during hematopoietic and megakaryocytic differentiation. Blood Adv 2022; 6:3945-3955. [PMID: 35507766 PMCID: PMC9278294 DOI: 10.1182/bloodadvances.2022007001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2022] [Accepted: 04/21/2022] [Indexed: 11/26/2022] Open
Abstract
ST3GAL1 and ST3GAL2 have both overlapping and unique substrate specificities in O-glycan sialylation during megakaryopoiesis. O-glycan sialylation is dispensable for MK production but indispensable for MK proplatelet formation.
Although the sialyltransferases ST3GAL1 and ST3GAL2 are known to transfer sialic acid to the galactose residue of type III disaccharides (Galβ1,3GalNAc) in vitro, sialylation of O-linked glycosylated proteins in living cells has been largely attributed to ST3GAL1. To examine the role of ST3GAL2 in O-sialylation, we examined its expression during differentiation of human-induced pluripotent stem cells (iPSCs) into hematopoietic progenitor cells (HPCs) and megakaryocytes (MKs). ST3GAL1 and ST3GAL2 each became highly expressed during the differentiation of iPSCs to HPCs but decreased markedly in their expression upon differentiation into MKs, suggesting coordination of expression during megakaryopoiesis. To further delineate their role in these processes, we generated ST3GAL1-, ST3GAL2-, and doubly deficient human iPSC lines. Binding of the peanut agglutinin lectin, which reports the presence of unsialylated Galβ1,3GalNAc glycan chains, was strongly increased in HPCs and MKs derived from double-knockout iPSCs and remained moderately increased in cells lacking either one of these sialyltransferases, demonstrating that both can serve as functional cellular O-glycan sialyltransferases. Interestingly, the HPC markers CD34 and CD43, as well as MK membrane glycoprotein (GP) GPIbα, were identified as major GP substrates for ST3GAL1 and ST3GAL2. In contrast, O-sialylation of GPIIb relied predominantly on the expression of ST3GAL2. Finally, although disruption of ST3GAL1 and ST3GAL2 had little impact on MK production, their absence resulted in dramatically impaired MK proplatelet formation. Taken together, these data establish heretofore unknown physiological roles for ST3GAL1 and ST3GAL2 in O-linked glycan sialylation in hemato- and megakaryocytopoiesis.
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Voos KM, Cao W, Arce NA, Legan ER, Wang Y, Shajahan A, Azadi P, Lollar P, Zhang XF, Li R. Desialylation of O-glycans activates von Willebrand factor by destabilizing its autoinhibitory module. J Thromb Haemost 2022; 20:196-207. [PMID: 34529349 PMCID: PMC9134874 DOI: 10.1111/jth.15528] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2021] [Revised: 08/15/2021] [Accepted: 09/10/2021] [Indexed: 01/03/2023]
Abstract
BACKGROUND The binding of the A1 domain of von Willebrand factor (VWF) to platelet receptor glycoprotein (GP)Ibα defines the VWF activity in hemostasis. Recent studies suggest that sequences flanking A1 form cooperatively an autoinhibitory module (AIM) that reduces the accessibility of the GPIbα binding site on A1. Application of a tensile force induces unfolding of the AIM. Desialylation induces spontaneous binding of plasma VWF to platelets. Most O-glycans in VWF are located around the A1 domain. Removing certain O-glycans in the flanking sequences by site-directed mutagenesis enhances A1 binding to GPIbα and produces an effect similar to type 2B von Willebrand disease in animals. OBJECTIVES To understand if and how desialylation of O-glycans in the flanking sequences increases A1 activity. METHODS A recombinant AIM-A1 fragment encompassing VWF residues 1238-1493 and only O-glycans was treated with neuraminidase to produce desialylated protein. The glycan structure, dynamics, stability, and function of the desialylated protein was characterized by biochemical and biophysical methods and compared to the sialylated fragment. RESULTS Asialo-AIM-A1 exhibited increased binding activity and induced more apparent platelet aggregation than its sialylated counterpart. It exhibited a lower melting temperature, and increased hydrogen-deuterium exchange rates at residues near the secondary GPIbα binding site and the N-terminal flanking sequence. Asialo-AIM-A1 is less mechanically stable than sialo-AIM-A1, with its unstressed unfolding rate approximately 3-fold greater than the latter. CONCLUSIONS Desialylation of O-glycans around A1 increases its activity by destabilizing the AIM.
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Affiliation(s)
- Kayleigh M. Voos
- Aflac Cancer and Blood Disorders Center, Children’s Healthcare of Atlanta, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA
| | - Wenpeng Cao
- Department of Bioengineering, Lehigh University, Bethlehem, PA
| | - Nicholas A. Arce
- Aflac Cancer and Blood Disorders Center, Children’s Healthcare of Atlanta, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA
| | - Emily R. Legan
- Aflac Cancer and Blood Disorders Center, Children’s Healthcare of Atlanta, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA
| | - Yingchun Wang
- Aflac Cancer and Blood Disorders Center, Children’s Healthcare of Atlanta, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA
| | - Asif Shajahan
- Complex Carbohydrate Research Center, University of Georgia, Athens, Georgia, USA
| | - Parastoo Azadi
- Complex Carbohydrate Research Center, University of Georgia, Athens, Georgia, USA
| | - Pete Lollar
- Aflac Cancer and Blood Disorders Center, Children’s Healthcare of Atlanta, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA
| | - X. Frank Zhang
- Department of Bioengineering, Lehigh University, Bethlehem, PA
| | - Renhao Li
- Aflac Cancer and Blood Disorders Center, Children’s Healthcare of Atlanta, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA
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Quach ME, Chen W, Wang Y, Deckmyn H, Lanza F, Nieswandt B, Li R. Differential regulation of the platelet GPIb-IX complex by anti-GPIbβ antibodies. J Thromb Haemost 2021; 19:2044-2055. [PMID: 33915031 PMCID: PMC8324530 DOI: 10.1111/jth.15359] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2020] [Revised: 04/14/2021] [Accepted: 04/26/2021] [Indexed: 11/30/2022]
Abstract
BACKGROUND Platelets' initial recognition of endothelial damage proceeds through the interaction between collagen, plasma von Willebrand factor (VWF), and the platelet glycoprotein (GP)Ib-IX complex (CD42). The GPIb-IX complex consists of one GPIbα, one GPIX, and two GPIbβ subunits. Once platelets are immobilized to the subendothelial matrix, shear generated by blood flow unfolds a membrane-proximal mechanosensory domain (MSD) in GPIbα, exposing a conserved trigger sequence and activating the receptor. Currently, GPIbα appears to solely facilitate ligand-induced activation because it contains both the MSD and the binding sites for all known ligands to GPIb-IX. Despite being positioned directly adjacent to the MSD, the roles of GPIbβ and GPIX in signal transduction remain murky. OBJECTIVES To characterize a novel rat monoclonal antibody 3G6 that binds GPIbβ. METHODS Effects of 3G6 on activation of GPIb-IX are characterized in platelets and Chinese hamster ovary cells expressing GPIb-IX (CHO-Ib-IX) and compared with those of an inhibitory anti-GPIbβ antibody, RAM.1. RESULTS Both RAM.1 and 3G6 bind to purified GPIbβ and GPIb-IX with high affinity. 3G6 potentiates GPIb-IX-associated filopodia formation in platelets or CHO-Ib-IX when they adhere VWF or antibodies against the ligand-binding domain (LBD) of GPIbα. Pretreatment with 3G6 also increased anti-LBD antibody-induced GPIb-IX activation. Conversely, RAM.1 inhibits nearly all GPIb-IX-related signaling in platelets and CHO-Ib-IX cells. CONCLUSIONS These data represent the first report of a positive modulator of GPIb-IX activation. The divergent modulatory effects of 3G6 and RAM.1, both targeting GPIbβ, strongly suggest that changes in the conformation of GPIbβ underlie outside-in activation via GPIb-IX.
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Affiliation(s)
- M. Edward Quach
- Aflac Cancer and Blood Disorders Center, Children’s Healthcare of Atlanta, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA 30322
| | - Wenchun Chen
- Aflac Cancer and Blood Disorders Center, Children’s Healthcare of Atlanta, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA 30322
| | - Yingchun Wang
- Aflac Cancer and Blood Disorders Center, Children’s Healthcare of Atlanta, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA 30322
| | - Hans Deckmyn
- Laboratory for Thrombosis Research, KU Leuven Campus Kulak Kortrijk, Kortrijk, Belgium
| | - Francois Lanza
- Université de Strasbourg, INSERM, BPPS UMR-S1255, Strasbourg, France
| | - Bernhard Nieswandt
- Rudolf Virchow Center, Julius Maximilian University of Wurzburg, Würzburg, Germany
| | - Renhao Li
- Aflac Cancer and Blood Disorders Center, Children’s Healthcare of Atlanta, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA 30322
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7
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Abstract
Platelet adhesion to the site of vascular damage is a critical early step in hemostasis. The platelet glycoprotein (GP) Ib-IX-V plays a key role in this step via its interaction with immobilized von Willebrand Factor (VWF). In addition to its well-known role in adhesion, GPIb-IX-V is critical for platelets' survival in circulation and plays an important role in the regulation of platelet clearance. Several mechanisms of platelet clearance work in concert to maintain a normal platelet count and ensure that circulating platelets are functionally viable via removal of senescent or activated platelets. Furthermore, dysregulation of platelet clearance underlies several bleeding disorders. GPIb-IX-V is central to many physiological mechanisms of platelet clearance including clearance via glycan receptors, clearance of VWF-platelet complexes, and fast clearance of transfused platelets. GPIb-IX-V dependent clearance also underlies thrombocytopenia in several bleeding disorders, including von Willebrand disease (VWD) and immune thrombocytopenia. This review will cover physiological and pathological mechanisms of platelet clearance, focusing on the role of GPIb-IX-V.
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Affiliation(s)
- M Edward Quach
- Stem Cell Program, Boston Children's Hospital, Boston, MA, USA.,Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, MA, USA
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8
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Zhou K, Xia Y, Yang M, Xiao W, Zhao L, Hu R, Shoaib KM, Yan R, Dai K. Actin polymerization regulates glycoprotein Ibα shedding. Platelets 2021; 33:381-389. [PMID: 33979555 DOI: 10.1080/09537104.2021.1922882] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Glycoprotein (GP) Ibα shedding mediated by ADAM17 (a disintegrin and metalloproteinase 17) plays an important role in negatively regulating platelet function and thrombus formation. However, the mechanism of GPIbα shedding remains elusive. Here, we show that jasplakinolide (an actin-polymerizing peptide)-induced actin polymerization results in GPIbα shedding and impairs platelet function. Thrombin and A23187-induced GPIbα shedding is increased by jasplakinolide; in contrast, GPIbα shedding is reduced by a depolymerization regent (cytochalasin B). We find that actin polymerization activates calpain leading to filamin A hydrolyzation. We further demonstrate that the interaction of filamin A with the cytoplasmic domain of GPIbα plays a critical role in regulating actin polymerization-induced GPIbα shedding. Taken together, these data demonstrate that actin polymerization regulates ADAM17-mediated GPIbα shedding, suggesting a novel strategy to negatively regulate platelet function.
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Affiliation(s)
- Kangxi Zhou
- Medical College, Jiangsu Institute of Hematology, the First Affiliated Hospital and Collaborative Innovation Center of Hematology, State Key Laboratory of Radiation Medicine and Protection, Soochow University, Key Laboratory of Thrombosis and Hemostasis, Ministry of Health, Suzhou, Jiangsu, China
| | - Yue Xia
- Medical College, Jiangsu Institute of Hematology, the First Affiliated Hospital and Collaborative Innovation Center of Hematology, State Key Laboratory of Radiation Medicine and Protection, Soochow University, Key Laboratory of Thrombosis and Hemostasis, Ministry of Health, Suzhou, Jiangsu, China
| | - Mengnan Yang
- Medical College, Jiangsu Institute of Hematology, the First Affiliated Hospital and Collaborative Innovation Center of Hematology, State Key Laboratory of Radiation Medicine and Protection, Soochow University, Key Laboratory of Thrombosis and Hemostasis, Ministry of Health, Suzhou, Jiangsu, China
| | - Weiling Xiao
- Medical College, Jiangsu Institute of Hematology, the First Affiliated Hospital and Collaborative Innovation Center of Hematology, State Key Laboratory of Radiation Medicine and Protection, Soochow University, Key Laboratory of Thrombosis and Hemostasis, Ministry of Health, Suzhou, Jiangsu, China
| | - Lili Zhao
- Medical College, Jiangsu Institute of Hematology, the First Affiliated Hospital and Collaborative Innovation Center of Hematology, State Key Laboratory of Radiation Medicine and Protection, Soochow University, Key Laboratory of Thrombosis and Hemostasis, Ministry of Health, Suzhou, Jiangsu, China
| | - Renping Hu
- Medical College, Jiangsu Institute of Hematology, the First Affiliated Hospital and Collaborative Innovation Center of Hematology, State Key Laboratory of Radiation Medicine and Protection, Soochow University, Key Laboratory of Thrombosis and Hemostasis, Ministry of Health, Suzhou, Jiangsu, China
| | - Khan Muhammad Shoaib
- Medical College, Jiangsu Institute of Hematology, the First Affiliated Hospital and Collaborative Innovation Center of Hematology, State Key Laboratory of Radiation Medicine and Protection, Soochow University, Key Laboratory of Thrombosis and Hemostasis, Ministry of Health, Suzhou, Jiangsu, China
| | - Rong Yan
- Medical College, Jiangsu Institute of Hematology, the First Affiliated Hospital and Collaborative Innovation Center of Hematology, State Key Laboratory of Radiation Medicine and Protection, Soochow University, Key Laboratory of Thrombosis and Hemostasis, Ministry of Health, Suzhou, Jiangsu, China
| | - Kesheng Dai
- Medical College, Jiangsu Institute of Hematology, the First Affiliated Hospital and Collaborative Innovation Center of Hematology, State Key Laboratory of Radiation Medicine and Protection, Soochow University, Key Laboratory of Thrombosis and Hemostasis, Ministry of Health, Suzhou, Jiangsu, China
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9
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Arce NA, Cao W, Brown AK, Legan ER, Wilson MS, Xu ER, Berndt MC, Emsley J, Zhang XF, Li R. Activation of von Willebrand factor via mechanical unfolding of its discontinuous autoinhibitory module. Nat Commun 2021; 12:2360. [PMID: 33883551 PMCID: PMC8060278 DOI: 10.1038/s41467-021-22634-x] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Accepted: 03/16/2021] [Indexed: 01/05/2023] Open
Abstract
Von Willebrand factor (VWF) activates in response to shear flow to initiate hemostasis, while aberrant activation could lead to thrombosis. Above a critical shear force, the A1 domain of VWF becomes activated and captures platelets via the GPIb-IX complex. Here we show that the shear-responsive element controlling VWF activation resides in the discontinuous autoinhibitory module (AIM) flanking A1. Application of tensile force in a single-molecule setting induces cooperative unfolding of the AIM to expose A1. The AIM-unfolding force is lowered by truncating either N- or C-terminal AIM region, type 2B VWD mutations, or binding of a ristocetin-mimicking monoclonal antibody, all of which could activate A1. Furthermore, the AIM is mechanically stabilized by the nanobody that comprises caplacizumab, the only FDA-approved anti-thrombotic drug to-date that targets VWF. Thus, the AIM is a mechano-regulator of VWF activity. Its conformational dynamics may define the extent of VWF autoinhibition and subsequent activation under force. Von Willebrand factor (VWF) is a large glycoprotein in the blood secreted from endothelial cells lining the blood vessel and activation of VWF leads to formation of VWF-platelet complexes or thrombi. Here authors use single-molecule force measurement, X-ray crystallography and functional measurements to monitor the activation of VWF via mechanical unfolding of the autoinhibitory module (AIM).
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Affiliation(s)
- Nicholas A Arce
- Aflac Cancer and Blood Disorders Center, Children's Healthcare of Atlanta, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA, USA
| | - Wenpeng Cao
- Department of Bioengineering, Department of Mechanical Engineering & Mechanics, Lehigh University, Bethlehem, PA, USA
| | - Alexander K Brown
- Biodiscovery Institute, School of Pharmacy, University of Nottingham, Nottingham, UK
| | - Emily R Legan
- Aflac Cancer and Blood Disorders Center, Children's Healthcare of Atlanta, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA, USA
| | - Moriah S Wilson
- Aflac Cancer and Blood Disorders Center, Children's Healthcare of Atlanta, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA, USA
| | - Emma-Ruoqi Xu
- Biodiscovery Institute, School of Pharmacy, University of Nottingham, Nottingham, UK
| | - Michael C Berndt
- Faculty of Health Sciences, Curtin University, Perth, WA, Australia
| | - Jonas Emsley
- Biodiscovery Institute, School of Pharmacy, University of Nottingham, Nottingham, UK
| | - X Frank Zhang
- Department of Bioengineering, Department of Mechanical Engineering & Mechanics, Lehigh University, Bethlehem, PA, USA.
| | - Renhao Li
- Aflac Cancer and Blood Disorders Center, Children's Healthcare of Atlanta, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA, USA.
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10
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Wang Y, Chen W, Zhang W, Lee-Sundlov MM, Casari C, Berndt MC, Lanza F, Bergmeier W, Hoffmeister KM, Zhang XF, Li R. Desialylation of O-glycans on glycoprotein Ibα drives receptor signaling and platelet clearance. Haematologica 2021; 106:220-229. [PMID: 31974202 PMCID: PMC7776245 DOI: 10.3324/haematol.2019.240440] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2019] [Accepted: 01/22/2020] [Indexed: 11/16/2022] Open
Abstract
During infection neuraminidase desialylates platelets and induces their rapid clearance from circulation. The underlying molecular basis, particularly the role of platelet glycoprotein (GP)Ibα therein, is not clear. Utilizing genetically altered mice, we report that the extracellular domain of GPIbα, but neither von Willebrand factor nor ADAM17 (a disintegrin and metalloprotease 17), is required for platelet clearance induced by intravenous injection of neuraminidase. Lectin binding to platelet following neuraminidase injection over time revealed that the extent of desialylation of O-glycans correlates with the decrease of platelet count in mice. Injection of α2,3-neuraminidase reduces platelet counts in wild-type but not in transgenic mice expressing only a chimeric GPIbα that misses most of its extracellular domain. Neuraminidase treatment induces unfolding of the O-glycosylated mechanosensory domain in GPIbα as monitored by single-molecule force spectroscopy, increases the exposure of the ADAM17 shedding cleavage site in the mechanosensory domain on the platelet surface, and induces ligand-independent GPIb-IX signaling in human and murine platelets. These results suggest that desialylation of O-glycans of GPIbα induces unfolding of the mechanosensory domain, subsequent GPIb-IX signaling including amplified desialylation of N-glycans, and eventually rapid platelet clearance. This new molecular mechanism of GPIbα-facilitated clearance could potentially resolve many puzzling and seemingly contradicting observations associated with clearance of desialylated or hyposialylated platelet.
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Affiliation(s)
- Yingchun Wang
- Department of Pediatrics, Emory University School of Medicine, Atlanta, GA
| | - Wenchun Chen
- Department of Pediatrics, Emory University School of Medicine, Atlanta, GA
| | - Wei Zhang
- Department of Bioengineering, Lehigh University, Bethlehem, PA
| | | | - Caterina Casari
- McAllister Heart Institute, University of North Carolina, School of Medicine, Chapel Hill, NC
| | | | - Francois Lanza
- Université de Strasbourg, EFS-Alsace, Strasbourg, France
| | | | | | - X Frank Zhang
- Department of Bioengineering, Lehigh University, Bethlehem, PA
| | - Renhao Li
- Department of Pediatrics, Emory University School of Medicine, Atlanta, GA
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11
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Platelet heterogeneity in activation-induced glycoprotein shedding: functional effects. Blood Adv 2019; 2:2320-2331. [PMID: 30232085 DOI: 10.1182/bloodadvances.2017011544] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Accepted: 08/15/2018] [Indexed: 12/20/2022] Open
Abstract
The platelet receptors glycoprotein Ibα (GPIbα) and GPVI are known to be cleaved by members of a disintegrin and metalloprotease (ADAM) family (ADAM10 and ADAM17), but the mechanisms and consequences of this shedding are not well understood. Our results revealed that (1) glycoprotein shedding is confined to distinct platelet populations showing near-complete shedding, (2) the heterogeneity between (non)shed platelets is independent of agonist type but coincides with exposure of phosphatidylserine (PS), and (3) distinct pathways of shedding are induced by elevated Ca2+, low Ca2+ protein kinase C (PKC), or apoptotic activation. Furthermore, we found that receptor shedding reduces binding of von Willebrand factor, enhances binding of coagulation factors, and augments fibrin formation. In response to Ca2+-increasing agents, shedding of GPIbα was abolished by ADAM10/17 inhibition but not by blockage of calpain. Stimulation of PKC induced shedding of only GPIbα, which was annulled by kinase inhibition. The proapoptotic agent ABT-737 induced shedding, which was caspase dependent. In Scott syndrome platelets that are deficient in Ca2+-dependent PS exposure, shedding occurred normally, indicating that PS exposure is not a prerequisite for ADAM activity. In whole-blood thrombus formation, ADAM-dependent glycoprotein shedding enhanced thrombin generation and fibrin formation. Together, these findings indicate that 2 major activation pathways can evoke ADAM-mediated glycoprotein shedding in distinct platelet populations and that shedding modulates platelet function from less adhesive to more procoagulant.
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12
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Chen 陈温纯 W, Voos KM, Josephson CD, Li R. Short-Acting Anti-VWF (von Willebrand Factor) Aptamer Improves the Recovery, Survival, and Hemostatic Functions of Refrigerated Platelets. Arterioscler Thromb Vasc Biol 2019; 39:2028-2037. [PMID: 31315441 DOI: 10.1161/atvbaha.119.312439] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
OBJECTIVE Refrigeration-induced binding of VWF (von Willebrand factor) to platelets contributes to the rapid clearance of refrigerated platelets. In this study, we investigate whether inhibiting VWF binding by a DNA-based aptamer ameliorates the clearance of refrigerated platelets without significantly impeding hemostatic functions. Approach and Results: Platelets were refrigerated with or without aptamer ARC1779 for 48 hours. VWF binding, the effective lifetime of ARC1779, platelet post-transfusion recovery and survival, and the hemostatic function were measured. ARC1779 treatment during refrigeration inhibited the platelet-VWF interaction. ARC1779-treated refrigerated murine platelets exhibited increased post-transfusion recovery and survival than untreated ones (recovery of ARC1779-treated platelets: 76.7±5.5%; untreated: 63.7±0.8%; P<0.01. Half-life: 31.4±2.36 hours versus 28.1±0.86 hours; P<0.05). A similar increase was observed for refrigerated human platelets (recovery: 49.4±4.4% versus 36.8±2.1%, P<0.01; half-life: 9.2±1.5 hours versus 8.7±0.9 hours, ns). The effective lifetime of ARC1779 in mice was 2 hours. Additionally, ARC1779 improved the long-term (2 hours after transfusion) hemostatic function of refrigerated platelets (tail bleeding time of mice transfused with ARC1779-treated refrigerated platelets: 160±65 seconds; untreated: 373±96 seconds; P<0.01). The addition of an ARC1779 antidote before transfusion improved the immediate (15 minutes after transfusion) hemostatic function (bleeding time of treated platelets: 149±21 seconds; untreated: 320±36 seconds; P<0.01). CONCLUSIONS ARC1779 improves the post-transfusion recovery of refrigerated platelets and preserves the long-term hemostatic function of refrigerated platelets. These results suggest that a short-acting inhibitor of the platelet-VWF interaction may be a potential therapeutic option to improve refrigeration of platelets for transfusion treatment.
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Affiliation(s)
- Wenchun Chen 陈温纯
- From the Aflac Cancer and Blood Disorders Center, Children's Healthcare of Atlanta, Department of Pediatrics (W.C., K.M.V., C.D.J., R.L.), Emory University School of Medicine, Atlanta, GA
| | - Kayleigh M Voos
- From the Aflac Cancer and Blood Disorders Center, Children's Healthcare of Atlanta, Department of Pediatrics (W.C., K.M.V., C.D.J., R.L.), Emory University School of Medicine, Atlanta, GA
| | - Cassandra D Josephson
- From the Aflac Cancer and Blood Disorders Center, Children's Healthcare of Atlanta, Department of Pediatrics (W.C., K.M.V., C.D.J., R.L.), Emory University School of Medicine, Atlanta, GA.,Department of Pathology (C.D.J), Emory University School of Medicine, Atlanta, GA
| | - Renhao Li
- From the Aflac Cancer and Blood Disorders Center, Children's Healthcare of Atlanta, Department of Pediatrics (W.C., K.M.V., C.D.J., R.L.), Emory University School of Medicine, Atlanta, GA
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13
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Quach ME, Syed AK, Li R. A Uniform Shear Assay for Human Platelet and Cell Surface Receptors via Cone-plate Viscometry. J Vis Exp 2019. [PMID: 31233025 DOI: 10.3791/59704] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Many biological cells/tissues sense the mechanical properties of their local environments via mechanoreceptors, proteins that can respond to forces like pressure or mechanical perturbations. Mechanoreceptors detect their stimuli and transmit signals via a great diversity of mechanisms. Some of the most common roles for mechanoreceptors are in neuronal responses, like touch and pain, or hair cells which function in balance and hearing. Mechanosensation is also important for cell types which are regularly exposed to shear stress such as endothelial cells, which line blood vessels, or blood cells which experience shear in normal circulation. Viscometers are devices that detect the viscosity of fluids. Rotational viscometers may also be used to apply a known shear force to fluids. The ability of these instruments to introduce uniform shear to fluids has been exploited to study many biological fluids including blood and plasma. Viscometry may also be used to apply shear to the cells in a solution, and to test the effects of shear on specific ligand-receptor pairs. Here, we utilize cone-plate viscometry to test the effects of endogenous levels of shear stress on platelets treated with antibodies against the platelet mechanosensory receptor complex GPIb-IX.
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Affiliation(s)
- M Edward Quach
- Aflac Cancer and Blood Disorders Center, Children's Healthcare of Atlanta; Department of Pediatrics, Emory University School of Medicine
| | - Anum K Syed
- Aflac Cancer and Blood Disorders Center, Children's Healthcare of Atlanta; Department of Pediatrics, Emory University School of Medicine
| | - Renhao Li
- Aflac Cancer and Blood Disorders Center, Children's Healthcare of Atlanta; Department of Pediatrics, Emory University School of Medicine;
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14
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Zhang XF, Zhang W, Quach ME, Deng W, Li R. Force-Regulated Refolding of the Mechanosensory Domain in the Platelet Glycoprotein Ib-IX Complex. Biophys J 2019; 116:1960-1969. [PMID: 31030883 DOI: 10.1016/j.bpj.2019.03.037] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2018] [Revised: 03/25/2019] [Accepted: 03/29/2019] [Indexed: 12/18/2022] Open
Abstract
In platelets, the glycoprotein (GP) Ib-IX receptor complex senses blood shear flow and transmits the mechanical signals into platelets. Recently, we have discovered a juxtamembrane mechanosensory domain (MSD) within the GPIbα subunit of GPIb-IX. Mechanical unfolding of the MSD activates GPIb-IX signaling into platelets, leading to their activation and clearance. Using optical tweezer-based single-molecule force measurement, we herein report a systematic biomechanical characterization of the MSD in its native, full-length receptor complex and a recombinant, unglycosylated MSD in isolation. The native MSD unfolds at a resting rate of 9 × 10-3 s-1. Upon exposure to pulling forces, MSD unfolding accelerates exponentially over a force scale of 2.0 pN. Importantly, the unfolded MSD can refold with or without applied forces. The unstressed refolding rate of MSD is ∼17 s-1 and slows exponentially over a force scale of 3.7 pN. Our measurements confirm that the MSD is relatively unstable, with a folding free energy of 7.5 kBT. Because MSD refolding may turn off GPIb-IX's mechanosensory signals, our results provide a mechanism for the requirement of a continuous pulling force of >15 pN to fully activate GPIb-IX.
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Affiliation(s)
- X Frank Zhang
- Department of Bioengineering, Department of Mechanical Engineering & Mechanics, Lehigh University, Bethlehem, Pennsylvania.
| | - Wei Zhang
- Department of Bioengineering, Department of Mechanical Engineering & Mechanics, Lehigh University, Bethlehem, Pennsylvania
| | - M Edward Quach
- Aflac Cancer and Blood Disorders Center, Department of Pediatrics, Emory University School of Medicine, Atlanta, Georgia
| | - Wei Deng
- Aflac Cancer and Blood Disorders Center, Department of Pediatrics, Emory University School of Medicine, Atlanta, Georgia
| | - Renhao Li
- Aflac Cancer and Blood Disorders Center, Department of Pediatrics, Emory University School of Medicine, Atlanta, Georgia.
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15
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The Glycoprotein Ib-IX-V Complex. Platelets 2019. [DOI: 10.1016/b978-0-12-813456-6.00010-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2023]
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16
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Wei G, Luo Q, Wang X, Wu X, Xu M, Ding N, Zhao Y, Zhong L, Wang J, Wu Y, Li X, Liu Y, Ju W, Li Z, Zeng L, Xu K, Qiao J. Increased GPIbα shedding from platelets treated with immune thrombocytopenia plasma. Int Immunopharmacol 2018; 66:91-98. [PMID: 30445311 DOI: 10.1016/j.intimp.2018.11.011] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2018] [Revised: 11/08/2018] [Accepted: 11/08/2018] [Indexed: 12/19/2022]
Abstract
Immune thrombocytopenia (ITP) is a heterogeneous autoimmune disease, characterized by accelerated platelet destruction/clearance or decreased platelet production. ADAM17-mediated platelet receptor GPIbα extracellular domain shedding has been shown to be involved in platelet clearance. Whether GPIbα shedding participates in the pathogenesis of ITP remains poorly understood. This study aims to investigate the role of GPIbα shedding in the development of ITP via incubating normal platelets with ITP plasma to mimic ITP in vivo environment. Plasma was isolated from ITP patients or healthy control and incubated with platelets in vitro followed by measuring GPIbα expression by flow cytometry and western blot, ADAM17 expression by western blot, ROS generation and platelet activation by flow cytometry. Compared with control plasma, ITP plasma-treated platelet displayed significantly reduced GPIbα surface expression, increased ADAM17 expression and ROS generation. However, metalloproteinase inhibitor GM6001 blocked the ITP-plasma-induced decrease in GPIbα surface expression, increase in ADAM17 expression and platelet activation. In addition, inhibitors of NADPH oxidase or mitochondria respiration significantly inhibited ROS generation from ITP plasma-treated platelets. Moreover, ROS inhibition or blocking FcγRIIa attenuated the decrease in GPIbα surface expression, platelet activation and ROS generation (for blocking FcγRIIa) in ITP plasma-treated platelets. In conclusion, ITP plasma induces platelet receptor GPIbα extracellular domain shedding, suggesting that it might participate in the pathogenesis of ITP and targeting it might be a novel approach for treating ITP.
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Affiliation(s)
- Guangyu Wei
- Blood Diseases Institute, Xuzhou Medical University, Xuzhou, China; Department of Hematology, the Affiliated Hospital of Xuzhou Medical University, Xuzhou, China; Key Laboratory of Bone Marrow Stem Cell, Jiangsu Province, Xuzhou, China
| | - Qi Luo
- Blood Diseases Institute, Xuzhou Medical University, Xuzhou, China; Department of Hematology, the Affiliated Hospital of Xuzhou Medical University, Xuzhou, China; Key Laboratory of Bone Marrow Stem Cell, Jiangsu Province, Xuzhou, China
| | - Xiamin Wang
- Blood Diseases Institute, Xuzhou Medical University, Xuzhou, China; Department of Hematology, the Affiliated Hospital of Xuzhou Medical University, Xuzhou, China; Key Laboratory of Bone Marrow Stem Cell, Jiangsu Province, Xuzhou, China
| | - Xiaoqing Wu
- Blood Diseases Institute, Xuzhou Medical University, Xuzhou, China; Department of Hematology, Xinyi City Hospital, Xuzhou, China
| | - Mengdi Xu
- Blood Diseases Institute, Xuzhou Medical University, Xuzhou, China; Department of Hematology, the Affiliated Hospital of Xuzhou Medical University, Xuzhou, China; Key Laboratory of Bone Marrow Stem Cell, Jiangsu Province, Xuzhou, China
| | - Ning Ding
- Blood Diseases Institute, Xuzhou Medical University, Xuzhou, China
| | - Yan Zhao
- Blood Diseases Institute, Xuzhou Medical University, Xuzhou, China
| | - Lamei Zhong
- Blood Diseases Institute, Xuzhou Medical University, Xuzhou, China
| | - Jurui Wang
- Blood Diseases Institute, Xuzhou Medical University, Xuzhou, China
| | - Yulu Wu
- Blood Diseases Institute, Xuzhou Medical University, Xuzhou, China
| | - Xiaoqian Li
- Department of Hematology, the Affiliated Hospital of Xuzhou Medical University, Xuzhou, China
| | - Yun Liu
- Department of Clinical Laboratory, The Affiliated Hospital of Xuzhou Medical University, Xuzhou, China
| | - Wen Ju
- Blood Diseases Institute, Xuzhou Medical University, Xuzhou, China; Department of Hematology, the Affiliated Hospital of Xuzhou Medical University, Xuzhou, China; Key Laboratory of Bone Marrow Stem Cell, Jiangsu Province, Xuzhou, China
| | - Zhenyu Li
- Blood Diseases Institute, Xuzhou Medical University, Xuzhou, China; Department of Hematology, the Affiliated Hospital of Xuzhou Medical University, Xuzhou, China; Key Laboratory of Bone Marrow Stem Cell, Jiangsu Province, Xuzhou, China
| | - Lingyu Zeng
- Blood Diseases Institute, Xuzhou Medical University, Xuzhou, China; Key Laboratory of Bone Marrow Stem Cell, Jiangsu Province, Xuzhou, China
| | - Kailin Xu
- Blood Diseases Institute, Xuzhou Medical University, Xuzhou, China; Department of Hematology, the Affiliated Hospital of Xuzhou Medical University, Xuzhou, China; Key Laboratory of Bone Marrow Stem Cell, Jiangsu Province, Xuzhou, China.
| | - Jianlin Qiao
- Blood Diseases Institute, Xuzhou Medical University, Xuzhou, China; Department of Hematology, the Affiliated Hospital of Xuzhou Medical University, Xuzhou, China; Key Laboratory of Bone Marrow Stem Cell, Jiangsu Province, Xuzhou, China.
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17
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Qi Y, Chen W, Liang X, Xu K, Gu X, Wu F, Fan X, Ren S, Liu J, Zhang J, Li R, Liu J, Liang X. Novel antibodies against GPIbα inhibit pulmonary metastasis by affecting vWF-GPIbα interaction. J Hematol Oncol 2018; 11:117. [PMID: 30223883 PMCID: PMC6142402 DOI: 10.1186/s13045-018-0659-4] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2018] [Accepted: 08/31/2018] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND Platelet glycoprotein Ibα (GPIbα) extracellular domain, which is part of the receptor complex GPIb-IX-V, plays an important role in tumor metastasis. However, the mechanism through which GPIbα participates in the metastatic process remains unclear. In addition, potential bleeding complication remains an obstacle for the clinical use of anti-platelet agents in cancer therapy. METHODS We established a series of screening models and obtained rat anti-mouse GPIbα monoclonal antibodies (mAb) 1D12 and 2B4 that demonstrated potential value in suppressing cancer metastasis. To validate our findings, we further obtained mouse anti-human GPIbα monoclonal antibody YQ3 through the same approach. RESULTS 1D12 and 2B4 affected the von Willebrand factor (vWF)-GPIbα interaction via binding to GPIbα aa 41-50 and aa 277-290 respectively, which markedly inhibited the interaction among platelets, tumor cells, and endothelial cells in vitro, and reduced the mean number of surface nodules in the experimental and spontaneous metastasis models in vivo. As expected, YQ3 inhibited lung cancer adhesion and demonstrated similar value in metastasis. More importantly, for all three mAbs in our study, none of their Fabs induced thrombocytopenia. CONCLUSION Our results therefore supported the hypothesis that GPIbα contributes to tumor metastasis and suggested potential value of using anti-GPIbα mAb to suppress cancer metastasis.
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Affiliation(s)
- Yingxue Qi
- State Key Laboratory of Bioreactor Engineering & Shanghai Key Laboratory of New Drug Design, School of Pharmacy, East China University of Science and Technology, 130 Meilong Rd, Shanghai, 200237, People's Republic of China
| | - Wenchun Chen
- Aflac Cancer and Blood Disorders Center, Children's Healthcare of Atlanta, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA, 30322, USA
| | - Xinyu Liang
- State Key Laboratory of Bioreactor Engineering & Shanghai Key Laboratory of New Drug Design, School of Pharmacy, East China University of Science and Technology, 130 Meilong Rd, Shanghai, 200237, People's Republic of China
| | - Ke Xu
- Central laboratory, General Surgery, Putuo Hospital, and Interventional Cancer Institute of Chinese Integrative Medicine, Shanghai University of Traditional Chinese Medicine, 164 Lanxi Rd, Shanghai, 200062, People's Republic of China.
| | - Xiangyu Gu
- State Key Laboratory of Bioreactor Engineering & Shanghai Key Laboratory of New Drug Design, School of Pharmacy, East China University of Science and Technology, 130 Meilong Rd, Shanghai, 200237, People's Republic of China
| | - Fengying Wu
- Department of Medical Oncology, Shanghai Pulmonary Hospital, Thoracic Cancer Institute, Tongji University School of Medicine, Shanghai, People's Republic of China
| | - Xuemei Fan
- Department of Biochemistry and Molecular Cell Biology, Shanghai Key Laboratory of Tumor Microenvironment and Inflammation, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, People's Republic of China
| | - Shengxiang Ren
- Department of Medical Oncology, Shanghai Pulmonary Hospital, Thoracic Cancer Institute, Tongji University School of Medicine, Shanghai, People's Republic of China
| | - Junling Liu
- Department of Biochemistry and Molecular Cell Biology, Shanghai Key Laboratory of Tumor Microenvironment and Inflammation, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, People's Republic of China
| | - Jun Zhang
- Division of Hematology, Oncology and Blood & Marrow Transplantation, Department of Internal Medicine, Holden Comprehensive Cancer Center, University of Iowa Carver College of Medicine, Iowa City, IA, 52242, USA
| | - Renhao Li
- Aflac Cancer and Blood Disorders Center, Children's Healthcare of Atlanta, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA, 30322, USA
| | - Jianwen Liu
- State Key Laboratory of Bioreactor Engineering & Shanghai Key Laboratory of New Drug Design, School of Pharmacy, East China University of Science and Technology, 130 Meilong Rd, Shanghai, 200237, People's Republic of China.
| | - Xin Liang
- State Key Laboratory of Bioreactor Engineering & Shanghai Key Laboratory of New Drug Design, School of Pharmacy, East China University of Science and Technology, 130 Meilong Rd, Shanghai, 200237, People's Republic of China.
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18
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Zilberman-Rudenko J, Zhao FZ, Reitsma SE, Mitrugno A, Pang J, Shatzel JJ, Rick B, Tyrrell C, Hasan W, McCarty OJT, Schreiber MA. Effect of Pneumatic Tubing System Transport on Platelet Apheresis Units. Cardiovasc Eng Technol 2018; 9:515-527. [PMID: 29785664 PMCID: PMC6168073 DOI: 10.1007/s13239-018-0361-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/21/2018] [Accepted: 05/08/2018] [Indexed: 01/23/2023]
Abstract
Platelet apheresis units are transfused into patients to mitigate or prevent bleeding. In a hospital, platelet apheresis units are transported from the transfusion service to the healthcare teams via two methods: a pneumatic tubing system (PTS) or ambulatory transport. Whether PTS transport affects the activity and utility of platelet apheresis units is unclear. We quantified the gravitational forces and transport time associated with PTS and ambulatory transport within our hospital. Washed platelets and supernatants were prepared from platelet apheresis units prior to transport as well as following ambulatory or PTS transport. For each group, we compared resting and agonist-induced platelet activity and platelet aggregate formation on collagen or von Willebrand factor (VWF) under shear, platelet VWF-receptor expression and VWF multimer levels. Subjection of platelet apheresis units to rapid acceleration/deceleration forces during PTS transport did not pre-activate platelets or their ability to activate in response to platelet agonists as compared to ambulatory transport. Platelets within platelet apheresis units transported via PTS retained their ability to adhere to surfaces of VWF and collagen under shear, although platelet aggregation on collagen and VWF was diminished as compared to ambulatory transport. VWF multimer levels and platelet GPIb receptor expression was unaffected by PTS transport as compared to ambulatory transport. Subjection of platelet apheresis units to PTS transport did not significantly affect the baseline or agonist-induced levels of platelet activation as compared to ambulatory transport. Our case study suggests that PTS transport may not significantly affect the hemostatic potential of platelets within platelet apheresis units.
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Affiliation(s)
- Jevgenia Zilberman-Rudenko
- Division of Trauma, Critical Care and Acute Care Surgery, Department of Surgery, Oregon Health & Science University, Portland, OR, USA.
- Department of Biomedical Engineering, School of Medicine, Oregon Health & Science University, 3303 SW Bond Ave., Portland, OR, USA.
| | - Frank Z Zhao
- Division of Trauma, Critical Care and Acute Care Surgery, Department of Surgery, Oregon Health & Science University, Portland, OR, USA
| | - Stephanie E Reitsma
- Department of Biomedical Engineering, School of Medicine, Oregon Health & Science University, 3303 SW Bond Ave., Portland, OR, USA
| | - Annachiara Mitrugno
- Department of Biomedical Engineering, School of Medicine, Oregon Health & Science University, 3303 SW Bond Ave., Portland, OR, USA
| | - Jiaqing Pang
- Department of Biomedical Engineering, School of Medicine, Oregon Health & Science University, 3303 SW Bond Ave., Portland, OR, USA
| | - Joseph J Shatzel
- Division of Hematology & Medical Oncology, Department of Medicine, Oregon Health & Science University, Portland, OR, USA
| | - Beth Rick
- Division of Trauma, Critical Care and Acute Care Surgery, Department of Surgery, Oregon Health & Science University, Portland, OR, USA
| | - Christina Tyrrell
- Knight Cardiovascular Institute, Oregon Health & Science University, Portland, OR, USA
| | - Wohaib Hasan
- Knight Cardiovascular Institute, Oregon Health & Science University, Portland, OR, USA
| | - Owen J T McCarty
- Department of Biomedical Engineering, School of Medicine, Oregon Health & Science University, 3303 SW Bond Ave., Portland, OR, USA
| | - Martin A Schreiber
- Division of Trauma, Critical Care and Acute Care Surgery, Department of Surgery, Oregon Health & Science University, Portland, OR, USA
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19
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Affiliation(s)
- Joel S Bennett
- From the Hematology-Oncology Division, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia.
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20
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Mechanisms of platelet clearance and translation to improve platelet storage. Blood 2018; 131:1512-1521. [PMID: 29475962 DOI: 10.1182/blood-2017-08-743229] [Citation(s) in RCA: 150] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Accepted: 01/28/2018] [Indexed: 02/01/2023] Open
Abstract
Hundreds of billions of platelets are cleared daily from circulation via efficient and highly regulated mechanisms. These mechanisms may be stimulated by exogenous reagents or environmental changes to accelerate platelet clearance, leading to thrombocytopenia. The interplay between antiapoptotic Bcl-xL and proapoptotic molecules Bax and Bak sets an internal clock for the platelet lifespan, and BH3-only proteins, mitochondrial permeabilization, and phosphatidylserine (PS) exposure may also contribute to apoptosis-induced platelet clearance. Binding of plasma von Willebrand factor or antibodies to the ligand-binding domain of glycoprotein Ibα (GPIbα) on platelets can activate GPIb-IX in a shear-dependent manner by inducing unfolding of the mechanosensory domain therein, and trigger downstream signaling in the platelet including desialylation and PS exposure. Deglycosylated platelets are recognized by the Ashwell-Morell receptor and potentially other scavenger receptors, and are rapidly cleared by hepatocytes and/or macrophages. Inhibitors of platelet clearance pathways, including inhibitors of GPIbα shedding, neuraminidases, and platelet signaling, are efficacious at preserving the viability of platelets during storage and improving their recovery and survival in vivo. Overall, common mechanisms of platelet clearance have begun to emerge, suggesting potential strategies to extend the shelf-life of platelets stored at room temperature or to enable refrigerated storage.
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21
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Fc-independent immune thrombocytopenia via mechanomolecular signaling in platelets. Blood 2017; 131:787-796. [PMID: 29203584 DOI: 10.1182/blood-2017-05-784975] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2017] [Accepted: 11/27/2017] [Indexed: 01/13/2023] Open
Abstract
Immune thrombocytopenia (ITP) is a prevalent autoimmune disease characterized by autoantibody-induced platelet clearance. Some ITP patients are refractory to standard immunosuppressive treatments such as intravenous immunoglobulin (IVIg). These patients often have autoantibodies that target the ligand-binding domain (LBD) of glycoprotein Ibα (GPIbα), a major subunit of the platelet mechanoreceptor complex GPIb-IX. However, the molecular mechanism of this Fc-independent platelet clearance is not clear. Here, we report that many anti-LBD monoclonal antibodies such as 6B4, but not AK2, activated GPIb-IX in a shear-dependent manner and induced IVIg-resistant platelet clearance in mice. Single-molecule optical tweezer measurements of antibodies pulling on full-length GPIb-IX demonstrated that the unbinding force needed to dissociate 6B4 from the LBD far exceeds the force required to unfold the juxtamembrane mechanosensory domain (MSD) in GPIbα, unlike the AK2-LBD unbinding force. Binding of 6B4, not AK2, induced shear-dependent unfolding of the MSD on the platelet, as evidenced by increased exposure of a linear sequence therein. Imaging flow cytometry and aggregometry measurements of platelets and LBD-coated platelet-mimetic beads revealed that 6B4 can sustain crosslinking of platelets under shear, whereas 6B4 Fab and AK2 cannot. These results suggest a novel mechanism by which anti-LBD antibodies can exert a pulling force on GPIb-IX via platelet crosslinking, activating GPIb-IX by unfolding its MSD and inducing Fc-independent platelet clearance.
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22
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Chen W, Druzak SA, Wang Y, Josephson CD, Hoffmeister KM, Ware J, Li R. Refrigeration-Induced Binding of von Willebrand Factor Facilitates Fast Clearance of Refrigerated Platelets. Arterioscler Thromb Vasc Biol 2017; 37:2271-2279. [PMID: 29097365 DOI: 10.1161/atvbaha.117.310062] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2017] [Accepted: 10/23/2017] [Indexed: 11/16/2022]
Abstract
OBJECTIVE Apheresis platelets for transfusion treatment are currently stored at room temperature because after refrigeration platelets are rapidly cleared on transfusion. In this study, the role of von Willebrand factor (VWF) in the clearance of refrigerated platelets is addressed. APPROACH AND RESULTS Human and murine platelets were refrigerated in gas-permeable bags at 4°C for 24 hours. VWF binding, platelet signaling events, and platelet post-transfusion recovery and survival were measured. After refrigeration, the binding of plasma VWF to platelets was drastically increased, confirming earlier studies. The binding was blocked by peptide OS1 that bound specifically to platelet glycoprotein (GP)Ibα and was absent in VWF-/- plasma. Although surface expression of GPIbα was reduced after refrigeration, refrigeration-induced VWF binding under physiological shear induced unfolding of the GPIbα mechanosensory domain on the platelet, as evidenced by increased exposure of a linear epitope therein. Refrigeration and shear treatment also induced small elevation of intracellular Ca2+, phosphatidylserine exposure, and desialylation of platelets, which were absent in VWF-/- platelets or inhibited by OS1, which is a monomeric 11-residue peptide (CTERMALHNLC). Furthermore, refrigerated VWF-/- platelets displayed increased post-transfusion recovery and survival than wild-type ones. Similarly, adding OS1 to transgenic murine platelets expressing only human GPIbα during refrigeration improved their post-transfusion recovery and survival. CONCLUSIONS Refrigeration-induced binding of VWF to platelets facilitates their rapid clearance by inducing GPIbα-mediated signaling. Our results suggest that inhibition of the VWF-GPIbα interaction may be a potential strategy to enable refrigeration of platelets for transfusion treatment.
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Affiliation(s)
- Wenchun Chen
- From the Aflac Cancer and Blood Disorders Center, Children's Healthcare of Atlanta, GA (W.C., S.A.D., Y.W., C.D.J., R.L.); Department of Pediatrics (W.C., S.A.D., Y.W., C.D.J., R.L.) and Department of Pathology (C.D.J.), Emory University School of Medicine, Atlanta, GA; Blood Research Institute, BloodCenter of Wisconsin, Milwaukee (K.M.H.); and Department of Physiology and Biophysics, University of Arkansas for Medical Sciences, Little Rock (J.W.)
| | - Samuel A Druzak
- From the Aflac Cancer and Blood Disorders Center, Children's Healthcare of Atlanta, GA (W.C., S.A.D., Y.W., C.D.J., R.L.); Department of Pediatrics (W.C., S.A.D., Y.W., C.D.J., R.L.) and Department of Pathology (C.D.J.), Emory University School of Medicine, Atlanta, GA; Blood Research Institute, BloodCenter of Wisconsin, Milwaukee (K.M.H.); and Department of Physiology and Biophysics, University of Arkansas for Medical Sciences, Little Rock (J.W.)
| | - Yingchun Wang
- From the Aflac Cancer and Blood Disorders Center, Children's Healthcare of Atlanta, GA (W.C., S.A.D., Y.W., C.D.J., R.L.); Department of Pediatrics (W.C., S.A.D., Y.W., C.D.J., R.L.) and Department of Pathology (C.D.J.), Emory University School of Medicine, Atlanta, GA; Blood Research Institute, BloodCenter of Wisconsin, Milwaukee (K.M.H.); and Department of Physiology and Biophysics, University of Arkansas for Medical Sciences, Little Rock (J.W.)
| | - Cassandra D Josephson
- From the Aflac Cancer and Blood Disorders Center, Children's Healthcare of Atlanta, GA (W.C., S.A.D., Y.W., C.D.J., R.L.); Department of Pediatrics (W.C., S.A.D., Y.W., C.D.J., R.L.) and Department of Pathology (C.D.J.), Emory University School of Medicine, Atlanta, GA; Blood Research Institute, BloodCenter of Wisconsin, Milwaukee (K.M.H.); and Department of Physiology and Biophysics, University of Arkansas for Medical Sciences, Little Rock (J.W.)
| | - Karin M Hoffmeister
- From the Aflac Cancer and Blood Disorders Center, Children's Healthcare of Atlanta, GA (W.C., S.A.D., Y.W., C.D.J., R.L.); Department of Pediatrics (W.C., S.A.D., Y.W., C.D.J., R.L.) and Department of Pathology (C.D.J.), Emory University School of Medicine, Atlanta, GA; Blood Research Institute, BloodCenter of Wisconsin, Milwaukee (K.M.H.); and Department of Physiology and Biophysics, University of Arkansas for Medical Sciences, Little Rock (J.W.)
| | - Jerry Ware
- From the Aflac Cancer and Blood Disorders Center, Children's Healthcare of Atlanta, GA (W.C., S.A.D., Y.W., C.D.J., R.L.); Department of Pediatrics (W.C., S.A.D., Y.W., C.D.J., R.L.) and Department of Pathology (C.D.J.), Emory University School of Medicine, Atlanta, GA; Blood Research Institute, BloodCenter of Wisconsin, Milwaukee (K.M.H.); and Department of Physiology and Biophysics, University of Arkansas for Medical Sciences, Little Rock (J.W.)
| | - Renhao Li
- From the Aflac Cancer and Blood Disorders Center, Children's Healthcare of Atlanta, GA (W.C., S.A.D., Y.W., C.D.J., R.L.); Department of Pediatrics (W.C., S.A.D., Y.W., C.D.J., R.L.) and Department of Pathology (C.D.J.), Emory University School of Medicine, Atlanta, GA; Blood Research Institute, BloodCenter of Wisconsin, Milwaukee (K.M.H.); and Department of Physiology and Biophysics, University of Arkansas for Medical Sciences, Little Rock (J.W.).
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23
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Deng W, Wang Y, Druzak SA, Healey JF, Syed AK, Lollar P, Li R. A discontinuous autoinhibitory module masks the A1 domain of von Willebrand factor. J Thromb Haemost 2017; 15:1867-1877. [PMID: 28692141 PMCID: PMC5585049 DOI: 10.1111/jth.13775] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Indexed: 12/18/2022]
Abstract
Essentials The mechanism for the auto-inhibition of von Willebrand factor (VWF) remains unclear. Hydrogen exchange of two VWF A1 fragments with disparate activities was measured and compared. Discontinuous residues flanking A1 form a structural module that blocks A1 binding to the platelet. Our results suggest a potentially unified model of VWF activation. Click to hear an ISTH Academy presentation on the domain architecture of VWF and activation by elongational flow by Dr Springer SUMMARY: Background How von Willebrand factor (VWF) senses and responds to shear flow remains unclear. In the absence of shear flow, VWF or its fragments can be induced to bind spontaneously to platelet GPIbα. Objectives To elucidate the auto-inhibition mechanism of VWF. Methods Hydrogen-deuterium exchange (HDX) of two recombinant VWF fragments expressed from baby hamster kidney cells were measured and compared. Results The shortA1 protein contains VWF residues 1261-1472 and binds GPIbα with a significantly higher affinity than the longA1 protein that contains VWF residues 1238-1472. Both proteins contain the VWF A1 domain (residues 1272-1458). Many residues in longA1, particularly those in the N- and C-terminal sequences flanking the A1 domain, and in helix α1, loops α1β2 and β3α2, demonstrated markedly reduced HDX compared with their counterparts in shortA1. The HDX-protected region in longA1 overlaps with the GPIbα-binding interface and is clustered with type 2B von Willebrand disease (VWD) mutations. Additional comparison with the HDX of denatured longA1 and ristocetin-bound longA1 indicates the N- and C-terminal sequences flanking the A1 domain form cooperatively an integrated autoinhibitory module (AIM) that interacts with the HDX-protected region. Binding of ristocetin to the C-terminal part of the AIM desorbs the AIM from A1 and enables longA1 binding to GPIbα. Conclusion The discontinuous AIM binds the A1 domain and prevents it from binding to GPIbα, which has significant implications for the pathogenesis of type 2B VWD and the shear-induced activation of VWF activity.
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Affiliation(s)
- W Deng
- Aflac Cancer and Blood Disorders Center, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA, USA
| | - Y Wang
- Aflac Cancer and Blood Disorders Center, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA, USA
| | - S A Druzak
- Aflac Cancer and Blood Disorders Center, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA, USA
| | - J F Healey
- Aflac Cancer and Blood Disorders Center, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA, USA
| | - A K Syed
- Aflac Cancer and Blood Disorders Center, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA, USA
| | - P Lollar
- Aflac Cancer and Blood Disorders Center, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA, USA
| | - R Li
- Aflac Cancer and Blood Disorders Center, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA, USA
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24
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Tien WS, Chen JH, Wu KP. SheddomeDB: the ectodomain shedding database for membrane-bound shed markers. BMC Bioinformatics 2017; 18:42. [PMID: 28361715 PMCID: PMC5374707 DOI: 10.1186/s12859-017-1465-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND A number of membrane-anchored proteins are known to be released from cell surface via ectodomain shedding. The cleavage and release of membrane proteins has been shown to modulate various cellular processes and disease pathologies. Numerous studies revealed that cell membrane molecules of diverse functional groups are subjected to proteolytic cleavage, and the released soluble form of proteins may modulate various signaling processes. Therefore, in addition to the secreted protein markers that undergo secretion through the secretory pathway, the shed membrane proteins may comprise an additional resource of noninvasive and accessible biomarkers. In this context, identifying the membrane-bound proteins that will be shed has become important in the discovery of clinically noninvasive biomarkers. Nevertheless, a data repository for biological and clinical researchers to review the shedding information, which is experimentally validated, for membrane-bound protein shed markers is still lacking. RESULTS In this study, the database SheddomeDB was developed to integrate publicly available data of the shed membrane proteins. A comprehensive literature survey was performed to collect the membrane proteins that were verified to be cleaved or released in the supernatant by immunological-based validation experiments. From 436 studies on shedding, 401 validated shed membrane proteins were included, among which 199 shed membrane proteins have not been annotated or validated yet by existing cleavage databases. SheddomeDB attempted to provide a comprehensive shedding report, including the regulation of shedding machinery and the related function or diseases involved in the shedding events. In addition, our published tool ShedP was embedded into SheddomeDB to support researchers for predicting the shedding event on unknown or unrecorded membrane proteins. CONCLUSIONS To the best of our knowledge, SheddomeDB is the first database for the identification of experimentally validated shed membrane proteins and currently may provide the most number of membrane proteins for reviewing the shedding information. The database included membrane-bound shed markers associated with numerous cellular processes and diseases, and some of these markers are potential novel markers because they are not annotated or validated yet in other databases. SheddomeDB may provide a useful resource for discovering membrane-bound shed markers. The interactive web of SheddomeDB is publicly available at http://bal.ym.edu.tw/SheddomeDB/ .
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Affiliation(s)
- Wei-Sheng Tien
- Institute of Biomedical Informatics, National Yang Ming University, Taipei, 112, Taiwan.,Bioinformatics Program, Taiwan International Graduate Program, Academia Sinica, Taipei, 115, Taiwan
| | - Jun-Hong Chen
- Department of Computer Science, National Taipei University of Education, Taipei, 106, Taiwan
| | - Kun-Pin Wu
- Institute of Biomedical Informatics, National Yang Ming University, Taipei, 112, Taiwan.
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25
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Abstract
Proteolytic shedding of the extracellular ectodomain of platelet receptors provides a key mechanism for irreversible loss of ligand-binding capacity, and for regulating platelet function in health and disease. Platelets derived from megakaryocytes are small anucleate cells in peripheral blood, with the ability to rapidly adhere, become activated, and secrete an array of procoagulant and proinflammatory factors at sites of vascular injury or disease, and to form a platelet aggregate (thrombus) which is not only critical in normal hemostasis and wound healing, but in atherothrombotic diseases including myocardial infarction and ischemic stroke. Basic mechanisms of receptor shedding on platelets have important distinctions from how receptors on other cell types might be shed, in that shedding is rapidly initiated (within seconds to minutes) and occurs under altered shear conditions encountered in flowing blood or experimentally ex vivo. This review will consider the key components of platelet receptor shedding, that is, the receptor with relevant cleavage site, the (metallo)proteinase or sheddase and how its activity is regulated, and the range of known regulatory factors that control platelet receptor shedding including receptor-associated molecules such as calmodulin, factors controlling sheddase surface expression and activity, and other elements such as shear stress, plasma membrane properties, cellular activation status or age. Understanding these basic mechanisms of platelet receptor shedding is significant in terms of utilizing receptor surface expression or soluble proteolytic fragments as platelet-specific biomarkers and/or ultimately therapeutic targeting of these mechanisms to control platelet reactivity and function.
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Affiliation(s)
- Robert K Andrews
- a Australian Centre for Blood Diseases , Monash University , Melbourne , Australia 3004.,b Department of Cancer Biology and Therapeutics, the John Curtin School of Medical Research , Australian National University , Canberra , Australia 2600
| | - Elizabeth E Gardiner
- a Australian Centre for Blood Diseases , Monash University , Melbourne , Australia 3004.,b Department of Cancer Biology and Therapeutics, the John Curtin School of Medical Research , Australian National University , Canberra , Australia 2600
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26
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Platelet clearance via shear-induced unfolding of a membrane mechanoreceptor. Nat Commun 2016; 7:12863. [PMID: 27670775 PMCID: PMC5052631 DOI: 10.1038/ncomms12863] [Citation(s) in RCA: 82] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2016] [Accepted: 08/10/2016] [Indexed: 12/26/2022] Open
Abstract
Mechanisms by which blood cells sense shear stress are poorly characterized. In platelets, glycoprotein (GP)Ib–IX receptor complex has been long suggested to be a shear sensor and receptor. Recently, a relatively unstable and mechanosensitive domain in the GPIbα subunit of GPIb–IX was identified. Here we show that binding of its ligand, von Willebrand factor, under physiological shear stress induces unfolding of this mechanosensory domain (MSD) on the platelet surface. The unfolded MSD, particularly the juxtamembrane ‘Trigger' sequence therein, leads to intracellular signalling and rapid platelet clearance. These results illustrate the initial molecular event underlying platelet shear sensing and provide a mechanism linking GPIb–IX to platelet clearance. Our results have implications on the mechanism of platelet activation, and on the pathophysiology of von Willebrand disease and related thrombocytopenic disorders. The mechanosensation via receptor unfolding may be applicable for many other cell adhesion receptors. The platelets detect and respond to shear stress generated by blood flow. Here the authors show that the binding of the soluble von Willebrand factor to its receptor GPIba under physiological shear stress induces receptor's domain unfolding on the platelet and signalling into the platelet, leading to platelets clearance.
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27
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Ju L, Chen Y, Xue L, Du X, Zhu C. Cooperative unfolding of distinctive mechanoreceptor domains transduces force into signals. eLife 2016; 5. [PMID: 27434669 PMCID: PMC5021522 DOI: 10.7554/elife.15447] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2016] [Accepted: 07/18/2016] [Indexed: 12/30/2022] Open
Abstract
How cells sense their mechanical environment and transduce forces into biochemical signals is a crucial yet unresolved question in mechanobiology. Platelets use receptor glycoprotein Ib (GPIb), specifically its α subunit (GPIbα), to signal as they tether and translocate on von Willebrand factor (VWF) of injured arterial surfaces against blood flow. Force elicits catch bonds to slow VWF-GPIbα dissociation and unfolds the GPIbα leucine-rich repeat domain (LRRD) and juxtamembrane mechanosensitive domain (MSD). How these mechanical processes trigger biochemical signals remains unknown. Here we analyze these extracellular events and the resulting intracellular Ca(2+) on a single platelet in real time, revealing that LRRD unfolding intensifies Ca(2+) signal whereas MSD unfolding affects the type of Ca(2+) signal. Therefore, LRRD and MSD are analog and digital force transducers, respectively. The >30 nm macroglycopeptide separating the two domains transmits force on the VWF-GPIbα bond (whose lifetime is prolonged by LRRD unfolding) to the MSD to enhance its unfolding, resulting in unfolding cooperativity at an optimal force. These elements may provide design principles for a generic mechanosensory protein machine.
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Affiliation(s)
- Lining Ju
- Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, United States.,Petit Institute for Bioengineering and Biosciences, Georgia Institute of Technology, Atlanta, United States.,Heart Research Institute, Camperdown, Australia.,Charles Perkins Centre, The University of Sydney, Camperdown, Australia
| | - Yunfeng Chen
- Petit Institute for Bioengineering and Biosciences, Georgia Institute of Technology, Atlanta, United States.,Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, United States
| | - Lingzhou Xue
- Department of Statistics, The Pennsylvania State University, University Park, United States
| | - Xiaoping Du
- Department of Pharmacology, College of Medicine, University of Illinois at Chicago, Chicago, United States
| | - Cheng Zhu
- Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, United States.,Petit Institute for Bioengineering and Biosciences, Georgia Institute of Technology, Atlanta, United States.,Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, United States
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28
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Chen W, Liang X, Syed AK, Jessup P, Church WR, Ware J, Josephson CD, Li R. Inhibiting GPIbα Shedding Preserves Post-Transfusion Recovery and Hemostatic Function of Platelets After Prolonged Storage. Arterioscler Thromb Vasc Biol 2016; 36:1821-8. [PMID: 27417583 DOI: 10.1161/atvbaha.116.307639] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2016] [Accepted: 06/23/2016] [Indexed: 11/16/2022]
Abstract
OBJECTIVE The platelet storage lesion accelerates platelet clearance after transfusion, but the underlying molecular mechanism remains elusive. Although inhibiting sheddase activity hampers clearance of platelets with storage lesion, the target platelet protein responsible for ectodomain shedding-induced clearance is not definitively identified. Monoclonal antibody 5G6 was developed recently to bind specifically human platelet receptor glycoprotein (GP)Ibα and inhibit its shedding but not shedding of other receptors. Here, the role of GPIbα shedding in platelet clearance after transfusion was addressed. APPROACH AND RESULTS Both human leukoreduced apheresis-derived platelets and transgenic mouse platelets expressing human GPIbα were stored at room temperature in the presence and absence of 5G6 Fab fragment. At various time points, aliquots of stored platelets were analyzed and compared. 5G6 Fab inhibited GPIbα shedding in both platelets during storage and preserved higher level of GPIbα on the platelet surface. Compared with age-matched control platelets, 5G6 Fab-stored platelets exhibited similar levels of platelet activation, degranulation, and agonist-induced aggregation. 5G6 Fab-stored human GPIbα platelets exhibited significantly higher post-transfusion recovery and in vivo hemostatic function in recipient mice than control platelets. Consistently, 5G6 Fab-stored, 8-day-old human platelets produced similar improvement in post-transfusion recovery in immunodeficient mice and in ex vivo thrombus formation over collagen under shear flow. CONCLUSIONS Specific inhibition of GPIbα shedding in the stored platelets improves post-transfusion platelet recovery and hemostatic function, providing clear evidence for GPIbα shedding as a cause of platelet clearance. These results suggest that specific inhibition of GPIbα shedding may be used to optimize platelet storage conditions.
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Affiliation(s)
- Wenchun Chen
- From the Aflac Cancer and Blood Disorders Center, Children's Healthcare of Atlanta, Department of Pediatrics (W.C., X.L., A.K.S., C.D.J., R.L.) and Department of Pathology (P.J., C.D.J.), Emory University School of Medicine, GA; Green Mountain Antibodies, Burlington, VT (W.R.C.); and Department of Physiology and Biophysics, University of Arkansas for Medical Sciences, Little Rock, AR (J.W.)
| | - Xin Liang
- From the Aflac Cancer and Blood Disorders Center, Children's Healthcare of Atlanta, Department of Pediatrics (W.C., X.L., A.K.S., C.D.J., R.L.) and Department of Pathology (P.J., C.D.J.), Emory University School of Medicine, GA; Green Mountain Antibodies, Burlington, VT (W.R.C.); and Department of Physiology and Biophysics, University of Arkansas for Medical Sciences, Little Rock, AR (J.W.)
| | - Anum K Syed
- From the Aflac Cancer and Blood Disorders Center, Children's Healthcare of Atlanta, Department of Pediatrics (W.C., X.L., A.K.S., C.D.J., R.L.) and Department of Pathology (P.J., C.D.J.), Emory University School of Medicine, GA; Green Mountain Antibodies, Burlington, VT (W.R.C.); and Department of Physiology and Biophysics, University of Arkansas for Medical Sciences, Little Rock, AR (J.W.)
| | - Paula Jessup
- From the Aflac Cancer and Blood Disorders Center, Children's Healthcare of Atlanta, Department of Pediatrics (W.C., X.L., A.K.S., C.D.J., R.L.) and Department of Pathology (P.J., C.D.J.), Emory University School of Medicine, GA; Green Mountain Antibodies, Burlington, VT (W.R.C.); and Department of Physiology and Biophysics, University of Arkansas for Medical Sciences, Little Rock, AR (J.W.)
| | - William R Church
- From the Aflac Cancer and Blood Disorders Center, Children's Healthcare of Atlanta, Department of Pediatrics (W.C., X.L., A.K.S., C.D.J., R.L.) and Department of Pathology (P.J., C.D.J.), Emory University School of Medicine, GA; Green Mountain Antibodies, Burlington, VT (W.R.C.); and Department of Physiology and Biophysics, University of Arkansas for Medical Sciences, Little Rock, AR (J.W.)
| | - Jerry Ware
- From the Aflac Cancer and Blood Disorders Center, Children's Healthcare of Atlanta, Department of Pediatrics (W.C., X.L., A.K.S., C.D.J., R.L.) and Department of Pathology (P.J., C.D.J.), Emory University School of Medicine, GA; Green Mountain Antibodies, Burlington, VT (W.R.C.); and Department of Physiology and Biophysics, University of Arkansas for Medical Sciences, Little Rock, AR (J.W.)
| | - Cassandra D Josephson
- From the Aflac Cancer and Blood Disorders Center, Children's Healthcare of Atlanta, Department of Pediatrics (W.C., X.L., A.K.S., C.D.J., R.L.) and Department of Pathology (P.J., C.D.J.), Emory University School of Medicine, GA; Green Mountain Antibodies, Burlington, VT (W.R.C.); and Department of Physiology and Biophysics, University of Arkansas for Medical Sciences, Little Rock, AR (J.W.)
| | - Renhao Li
- From the Aflac Cancer and Blood Disorders Center, Children's Healthcare of Atlanta, Department of Pediatrics (W.C., X.L., A.K.S., C.D.J., R.L.) and Department of Pathology (P.J., C.D.J.), Emory University School of Medicine, GA; Green Mountain Antibodies, Burlington, VT (W.R.C.); and Department of Physiology and Biophysics, University of Arkansas for Medical Sciences, Little Rock, AR (J.W.).
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29
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Affiliation(s)
- Markus Bender
- Department of Experimental Biomedicine, University of Würzburg, University Hospital and Rudolf Virchow Center, Würzburg, Germany
| | - David Stegner
- Department of Experimental Biomedicine, University of Würzburg, University Hospital and Rudolf Virchow Center, Würzburg, Germany
| | - Bernhard Nieswandt
- Department of Experimental Biomedicine, University of Würzburg, University Hospital and Rudolf Virchow Center, Würzburg, Germany
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30
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Tao Y, Zhang X, Liang X, Zang J, Mo X, Li R. Structural basis for the specific inhibition of glycoprotein Ibα shedding by an inhibitory antibody. Sci Rep 2016; 6:24789. [PMID: 27102061 PMCID: PMC4840364 DOI: 10.1038/srep24789] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2015] [Accepted: 04/04/2016] [Indexed: 01/14/2023] Open
Abstract
Ectodomain shedding of glycoprotein (GP) Ibα is thought to mediate the clearance of activated, aged or damaged platelets. A monoclonal antibody, 5G6, has been developed recently to specifically bind to the GPIbα shedding cleavage site and to inhibit its shedding. However, the molecular mechanism underlying antigen recognition and inhibitory specificity is not clear. To elucidate the structural basis for 5G6 binding to GPIbα, we determined the crystal structure of 5G6 Fab fragment in complex with its epitope peptide KL10 (GPIbα residues 461–470, KLRGVLQGHL), to 2.4-Å resolution. Key residues in both 5G6 and KL10 were mutated to validate their effects in antibody binding by using isothermal titration calorimetry. The 5G6 Fab-KL10 peptide complex structure confirmed the direct association of 5G6 with its target GPIbα residues and elucidated the molecular basis underlying its binding specificity and high affinity. The similar binding properties of 5G6 Fab fragment to GPIbα on human platelets as those to KL10 suggests that such an interaction may not be affected by the plasma membrane or nearby GPIbβ. This structural information may facilitate further antibody optimization and humanization.
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Affiliation(s)
- Yue Tao
- Key Laboratory of Pediatric Hematology &Oncology Ministry of Health, Pediatric Translational Medicine Institute, Shanghai Children's Medical Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Xiaoqin Zhang
- Key Laboratory of Pediatric Hematology &Oncology Ministry of Health, Pediatric Translational Medicine Institute, Shanghai Children's Medical Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Xin Liang
- Aflac Cancer and Blood Disorders Center, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA, USA
| | - Jianye Zang
- Hefei National Laboratory for Physical Sciences at Microscale and School of Life Sciences; University of Science and Technology of China, Hefei, China.,Key Laboratory of Structural Biology; Chinese Academy of Sciences, Hefei, China
| | - Xi Mo
- Key Laboratory of Pediatric Hematology &Oncology Ministry of Health, Pediatric Translational Medicine Institute, Shanghai Children's Medical Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Renhao Li
- Aflac Cancer and Blood Disorders Center, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA, USA
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Liang X, Syed AK, Russell SR, Ware J, Li R. Dimerization of glycoprotein Ibα is not sufficient to induce platelet clearance. J Thromb Haemost 2016; 14:381-6. [PMID: 26662889 PMCID: PMC4755834 DOI: 10.1111/jth.13221] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2015] [Accepted: 11/22/2015] [Indexed: 01/10/2023]
Abstract
UNLABELLED ESSENTIALS: Many anti-glycoprotein (GP)Ibα antibodies induce platelet clearance in a dimer-dependent manner. Characterization of monoclonal antibodies that bind the mechanosensitive domain (MSD) of GPIbα. An anti-MSD antibody binds two copies of GPIbα in platelets but does not induce platelet clearance. The prevailing clustering model of GPIbα signaling is incorrect or needs revision. BACKGROUND The mechanism of platelet clearance is not clear. Many antibodies binding the membrane-distal ligand-binding domain of glycoprotein (GP)Ibα induce rapid clearance of platelets and acute thrombocytopenia, which requires the bifurcated antibody structure. It was thought that binding of these antibodies induced lateral dimerization or clustering of GPIbα in the plasma membrane, which leads to downstream signaling and platelet clearance. However, many antibodies targeting GPIbβ and GPIX, which are associated with GPIbα in the GPIb-IX complex, do not induce platelet clearance, which is in contradiction to the clustering model. OBJECTIVES To test whether dimerization or clustering of GPIbα is sufficient to transmit the signal that leads to platelet clearance. METHODS We have recently raised several mAbs targeting the mechanosensitive domain (MSD) of GPIbα. Binding of these anti-MSD antibodies was characterized with biochemical methods. Their ability to stimulate platelets and induce platelet clearance in mice was assessed. RESULTS AND CONCLUSION Infusion of anti-MSD antibodies does not cause thrombocytopenia in mice. These antibodies show no detectable effects on platelet activation and aggregation in vitro. Further biochemical investigation showed that the anti-MSD antibody 3D1 binds two copies of GPIbα on the platelet surface. Therefore, lateral dimerization of GPIbα induced by antibody binding is not sufficient to initiate GPIb-IX signaling and induce platelet clearance. Our results suggest that a factor other than or in addition to clustering of GPIbα is required to induce platelet clearance.
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Affiliation(s)
- Xin Liang
- Aflac Cancer and Blood Disorders Center, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA
| | - Anum K. Syed
- Aflac Cancer and Blood Disorders Center, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA
| | - Susan R. Russell
- Department of Physiology and Biophysics, University of Arkansas for Medical Sciences, Little Rock, AR
| | - Jerry Ware
- Department of Physiology and Biophysics, University of Arkansas for Medical Sciences, Little Rock, AR
| | - Renhao Li
- Aflac Cancer and Blood Disorders Center, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA
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33
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Platelets and physics: How platelets “feel” and respond to their mechanical microenvironment. Blood Rev 2015; 29:377-86. [DOI: 10.1016/j.blre.2015.05.002] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2015] [Revised: 05/04/2015] [Accepted: 05/04/2015] [Indexed: 01/08/2023]
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34
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Lancellotti S, Dragani A, Ranalli P, Petrucci G, Basso M, Tartaglione R, Rocca B, De Cristofaro R. Qualitative and quantitative modifications of von Willebrand factor in patients with essential thrombocythemia and controlled platelet count. J Thromb Haemost 2015; 13:1226-37. [PMID: 25876231 DOI: 10.1111/jth.12967] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2014] [Indexed: 12/23/2022]
Abstract
BACKGROUND Essential thrombocythemia (ET) is characterized by increased platelets and prevalent thrombosis. An acquired von Willebrand factor (VWF) disease has been hypothesized and inconsistently associated with extreme thrombocytosis or rare bleeding in ET. Whether VWF is modified in ET patients with controlled platelet count remains unclear. OBJECTIVES We studied different VWF- and platelet-associated parameters in ET patients treated according to current recommendations. PATIENTS/METHODS Sixty-nine ET patients (M = 29; median age, 62 [48-70] years; platelets, 432 [337-620] × 10(3) μL(-1) ), 69 matched controls and 10 subjects with reactive thrombocytosis (RT) were studied. VWF:antigen (Ag), activity (act), electrophoretic patterns, VWF:propeptide, plasma glycocalycin (GC), glycoproteinV (GpV), ADAMTS-13, elastase, C-reactive protein and serum thromboxane (TX)B2 were measured. RESULTS In ET patients, VWF:Ag was increased by 31 ± 13% vs. controls (P < 0.01), without dependence of blood groups, while VWF:act was reduced by 21 ± 12% vs. controls and by 50 ± 24% vs. RT (P < 0.01). The VWF:act/VWF:Ag ratios in ET were reduced by 35 ± 17% vs. controls and RT patients (P < 0.001) and significantly associated with: immature or total platelet counts, GC, GpV and TXB2 . In multivariable analysis, only GC inversely predicted ET patients' VWF:act/VWF:Ag ratios (β = -0.42, P = 0.01). By electrophoresis analyses, high-molecular-weight VWF multimers were variably reduced with atypical cleavage bands in ET only. VWF:propeptide, ADAMTS-13 and elastase levels were normal in ET patients. Platelet-associated ADAM-10 and ADAM-17 hydrolyzed VWFm in vitro, showing patterns similar to those in ET samples. CONCLUSIONS In ET patients with controlled platelet counts, the VWF:act/VWF:Ag ratio is decreased and predicted by GC, a product of platelet activation. ADAM-10 and/or ADAM-17 might be involved. In vivo platelet activation, which characterizes ET, might contribute to disease-specific VWF alterations.
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Affiliation(s)
- S Lancellotti
- Center for Haemorrhagic and Thrombotic Diseases, Department of Medical Sciences, Catholic University School of Medicine, 'A. Gemelli' Hospital, Rome, Italy
| | - A Dragani
- Center for Haemorrhagic, Thrombotic and Rare Hematologic Diseases, Spirito Santo Hospital, Pescara, Italy
| | - P Ranalli
- Center for Haemorrhagic, Thrombotic and Rare Hematologic Diseases, Spirito Santo Hospital, Pescara, Italy
| | - G Petrucci
- Institute of Pharmacology, Catholic University School of Medicine, Rome, Italy
| | - M Basso
- Center for Haemorrhagic and Thrombotic Diseases, Department of Medical Sciences, Catholic University School of Medicine, 'A. Gemelli' Hospital, Rome, Italy
| | - R Tartaglione
- Institute of Haematology, Complesso Integrato Columbus, Catholic University School of Medicine, Rome, Italy
| | - B Rocca
- Institute of Pharmacology, Catholic University School of Medicine, Rome, Italy
| | - R De Cristofaro
- Center for Haemorrhagic and Thrombotic Diseases, Department of Medical Sciences, Catholic University School of Medicine, 'A. Gemelli' Hospital, Rome, Italy
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