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Rawley O, Swystun LL, Brown C, Nesbitt K, Rand M, Hossain T, Klaassen R, James PD, Carcao MD, Lillicrap D. Novel cysteine substitution p.(Cys1084Tyr) causes variable expressivity of qualitative and quantitative VWF defects. Blood Adv 2022; 6:2908-2919. [PMID: 35020809 PMCID: PMC9092401 DOI: 10.1182/bloodadvances.2021005928] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Accepted: 11/23/2021] [Indexed: 11/20/2022] Open
Abstract
von Willebrand factor (VWF) is an extremely cysteine-rich multimeric protein that is essential for maintaining normal hemostasis. The cysteine residues of VWF monomers form intra- and intermolecular disulfide bonds that regulate its structural conformation, multimer distribution, and ultimately its hemostatic activity. In this study, we investigated and characterized the molecular and pathogenic mechanisms through which a novel cysteine variant p.(Cys1084Tyr) causes an unusual, mixed phenotype form of von Willebrand disease (VWD). Phenotypic data including bleeding scores, laboratory values, VWF multimer distribution, and desmopressin response kinetics were investigated in 5 members (2 parents and 3 daughters) of a consanguineous family. VWF synthesis and secretion were also assessed in a heterologous expression system and in a transient transgenic mouse model. Heterozygosity for p.(Cys1084Tyr) was associated with variable expressivity of qualitative VWF defects. Heterozygous individuals had reduced VWF:GPIbM (<0.40 IU/mL) and VWF:CB (<0.35 IU/mL), as well as relative reductions in high-molecular-weight multimers, consistent with type 2A VWD. In addition to these qualitative defects, homozygous individuals also displayed reduced factor VIII (FVIII):C/VWF:Ag, leading to very low FVIII levels (0.03-0.1 IU/mL) and reduced VWF:Ag (<0.40 IU/mL) and VWF:GPIbM (<0.30 IU/mL). Accelerated VWF clearance and impaired VWF secretion contributed to the fully expressed homozygous phenotype with impaired secretion arising because of disordered disulfide connectivity.
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Affiliation(s)
- Orla Rawley
- Molecular Hemostasis Research Group, Department of Pathology and Molecular Medicine, Queen’s University, Kingston, ON, Canada
| | - Laura L. Swystun
- Molecular Hemostasis Research Group, Department of Pathology and Molecular Medicine, Queen’s University, Kingston, ON, Canada
| | - Christine Brown
- Molecular Hemostasis Research Group, Department of Pathology and Molecular Medicine, Queen’s University, Kingston, ON, Canada
| | - Kate Nesbitt
- Molecular Hemostasis Research Group, Department of Pathology and Molecular Medicine, Queen’s University, Kingston, ON, Canada
| | - Margaret Rand
- Division of Hematology/Oncology, Department of Pediatrics, Hospital for Sick Children and University of Toronto, Toronto, ON, Canada
| | - Taneya Hossain
- Division of Hematology/Oncology, Department of Pediatrics, Hospital for Sick Children and University of Toronto, Toronto, ON, Canada
| | - Robert Klaassen
- Department of Pediatrics, University of Ottawa, Ottawa, ON, Canada; and
| | - Paula D. James
- Department of Medicine, Queen’s University, Kingston, ON, Canada
| | - Manuel D. Carcao
- Division of Hematology/Oncology, Department of Pediatrics, Hospital for Sick Children and University of Toronto, Toronto, ON, Canada
| | - David Lillicrap
- Molecular Hemostasis Research Group, Department of Pathology and Molecular Medicine, Queen’s University, Kingston, ON, Canada
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Mojzisch A, Brehm MA. The Manifold Cellular Functions of von Willebrand Factor. Cells 2021; 10:2351. [PMID: 34572000 PMCID: PMC8466076 DOI: 10.3390/cells10092351] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2021] [Revised: 08/26/2021] [Accepted: 09/02/2021] [Indexed: 12/13/2022] Open
Abstract
The plasma glycoprotein von Willebrand factor (VWF) is exclusively synthesized in endothelial cells (ECs) and megakaryocytes, the precursor cells of platelets. Its primary function lies in hemostasis. However, VWF is much more than just a "fishing hook" for platelets and a transporter for coagulation factor VIII. VWF is a true multitasker when it comes to its many roles in cellular processes. In ECs, VWF coordinates the formation of Weibel-Palade bodies and guides several cargo proteins to these storage organelles, which control the release of hemostatic, inflammatory and angiogenic factors. Leukocytes employ VWF to assist their rolling on, adhesion to and passage through the endothelium. Vascular smooth muscle cell proliferation is supported by VWF, and it regulates angiogenesis. The life cycle of platelets is accompanied by VWF from their budding from megakaryocytes to adhesion, activation and aggregation until the end in apoptosis. Some tumor cells acquire the ability to produce VWF to promote metastasis and hide in a shell of VWF and platelets, and even the maturation of osteoclasts is regulated by VWF. This review summarizes the current knowledge on VWF's versatile cellular functions and the resulting pathophysiological consequences of their dysregulation.
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Affiliation(s)
- Angelika Mojzisch
- Dermatology and Venerology, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany;
| | - Maria A. Brehm
- School of Life Sciences, University of Siegen, 57076 Siegen, Germany
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3
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Yadegari H, Biswas A, Ahmed S, Naz A, Oldenburg J. von Willebrand factor propeptide missense variants affect anterograde transport to Golgi resulting in ER retention. Hum Mutat 2021; 42:731-744. [PMID: 33942438 DOI: 10.1002/humu.24204] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Revised: 02/22/2021] [Accepted: 04/01/2021] [Indexed: 11/07/2022]
Abstract
von Willebrand disease (VWD), the most prevalent congenital bleeding disorder, arises from a deficiency in von Willebrand factor (VWF), which has crucial roles in hemostasis. The present study investigated functional consequences and underlying pathomolecular mechanisms of several VWF propeptide (VWFpp) missense variants detected in our cohort of VWD patients for the first time. Transient expression experiments in HEK293T cells demonstrated that four out of the six investigated missense variants (p.Gly55Glu, p.Val86Glu, p.Trp191Arg, and p.Cys608Trp) severely impaired secretion. Their cotransfections with the wild-type partly corrected VWF secretion, displaying loss of large/intermediate multimers. Immunostaining of the transfected HEK293 cells illustrated the endoplasmic reticulum (ER) retention of the VWF variants. Docking of the COP I and COP II cargo recruitment proteins, ADP-ribosylation factor 1 and Sec24, onto the N-terminal VWF model (D1D2D'D3) revealed that these variants occur at VWFpp putative interfaces, which can hinder VWF loading at the ER exit quality control. Furthermore, quantitative and automated morphometric exploration of the three-dimensional immunofluorescence images showed changes in the number/size of the VWF storage organelles, Weibel-Palade body (WPB)-like vesicles. The result of this study highlighted the significance of the VWFpp variants on anterograde ER-Golgi trafficking of VWF as well as the biogenesis of WPB-like vesicles.
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Affiliation(s)
- Hamideh Yadegari
- Institute of Experimental Haematology and Transfusion Medicine, University Clinics Bonn, Bonn, Germany
| | - Arijit Biswas
- Institute of Experimental Haematology and Transfusion Medicine, University Clinics Bonn, Bonn, Germany
| | - Shariq Ahmed
- National Institute of Blood Disease & Bone Marrow Transplantation, Karachi, Pakistan
| | - Arshi Naz
- National Institute of Blood Disease & Bone Marrow Transplantation, Karachi, Pakistan
| | - Johannes Oldenburg
- Institute of Experimental Haematology and Transfusion Medicine, University Clinics Bonn, Bonn, Germany
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4
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Rawley O, Lillicrap D. Functional Roles of the von Willebrand Factor Propeptide. Hamostaseologie 2021; 41:63-68. [PMID: 33588457 DOI: 10.1055/a-1334-8002] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The primary polypeptide sequence of von Willebrand factor (VWF) includes an N-terminal 741-amino acid VWF propeptide (VWFpp). In cells expressing VWF, the VWFpp performs two critical functions. In the Golgi, VWFpp mediates the intermolecular disulfide linkages that generate high-molecular-weight VWF multimers. Subsequently, the VWFpp, which is proteolytically cleaved from mature VWF by furin, functions to generate the endothelial storage organelles (Weibel-Palade bodies) in which VWF and a distinct collection of proteins are stored, and from where they undergo regulated secretion from the endothelium. The VWFpp is secreted from endothelial cells as dimers and circulates in plasma with at least some of the dimers associating with a noncovalent manner with the D'D3 domain of mature VWF. The VWFpp has a half-life of 2 to 3 hours in plasma, but to date no extracellular function has been determined for the molecule. Nevertheless, its large size and several biologically interesting structural features (two sets of vicinal cysteines and an RGD sequence) suggest that there may be roles that the VWFpp plays in hemostasis or associated physiological processes such as angiogenesis or wound repair.
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Affiliation(s)
- Orla Rawley
- Department of Pathology and Molecular Medicine, Richardson Laboratory, Queen's University, Kingston, Ontario, Canada
| | - David Lillicrap
- Department of Pathology and Molecular Medicine, Richardson Laboratory, Queen's University, Kingston, Ontario, Canada
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Ahmad F, Kannan M, Obser T, Budde U, Schneppenheim S, Saxena R, Schneppenheim R. Characterization ofVWFgene conversions causing von Willebrand disease. Br J Haematol 2018; 184:817-825. [DOI: 10.1111/bjh.15709] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2018] [Accepted: 11/05/2018] [Indexed: 12/01/2022]
Affiliation(s)
- Firdos Ahmad
- Sharjah Institute for Medical Research and, College of Medicine; University of Sharjah; Sharjah UAE
| | - Meganathan Kannan
- Division of Blood and Vascular Biology; Department of Life Sciences; School of Basic and Applied Sciences; Central University of Tamilnadu; Thiruvarur India
| | - Tobias Obser
- Department of Pediatric Haematology and Oncology; University Medical Centre; Eppendorf Hamburg Germany
| | - Ulrich Budde
- Medilys Laboratory Coagulation; Asklepios Hospital Altona; Hamburg Germany
| | | | - Renu Saxena
- Department of Haematology; All India Institute of Medical Sciences; New Delhi India
| | - Reinhard Schneppenheim
- Department of Pediatric Haematology and Oncology; University Medical Centre; Eppendorf Hamburg Germany
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Shigekiyo T, Udaka K, Sekimoto E, Shibata H, Ozaki S, Higuchi Y, Matsumoto M. Identification of a homozygous missense mutation (p.Cys379Gly) in the D1 domain of von Willebrand factor propeptide in a family with type 2A (IIC) von Willebrand disease. Haemophilia 2018; 24:e422-e425. [PMID: 30175488 DOI: 10.1111/hae.13605] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2018] [Revised: 07/26/2018] [Accepted: 07/30/2018] [Indexed: 06/08/2023]
Affiliation(s)
- Toshio Shigekiyo
- Department of Hematology, Tokushima Prefectural Central Hospital, Tokushima, Japan
| | - Kengo Udaka
- Department of Hematology, Tokushima Prefectural Central Hospital, Tokushima, Japan
| | - Etsuko Sekimoto
- Department of Hematology, Tokushima Prefectural Central Hospital, Tokushima, Japan
| | - Hironobu Shibata
- Department of Hematology, Tokushima Prefectural Central Hospital, Tokushima, Japan
| | - Shuji Ozaki
- Department of Hematology, Tokushima Prefectural Central Hospital, Tokushima, Japan
| | - Yukio Higuchi
- Department of Orthopedics, Tokushima Prefectural Central Hospital, Tokushima, Japan
| | - Masanori Matsumoto
- Department of Blood Transfusion Medicine, Nara Medical University, Nara, Japan
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Aponte-Santamaría C, Obser T, Grässle S, Oyen F, Budde U, Schneppenheim S, Baldauf C, Gräter F, Schneider SW, Schneppenheim R, Brehm MA, Huck V. von Willebrand disease type 2A phenotypes IIC, IID and IIE: A day in the life of shear-stressed mutant von Willebrand factor. Thromb Haemost 2017; 112:96-108. [DOI: 10.1160/th13-11-0902] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2013] [Accepted: 02/11/2014] [Indexed: 11/05/2022]
Abstract
SummaryThe bleeding disorder von Willebrand disease (VWD) is caused by mutations of von Willebrand factor (VWF), a multimeric glycoprotein essential for platelet-dependent primary haemostasis. VWD type 2A–associated mutations each disrupt VWF biosynthesis and function at different stages, depending on the VWF domain altered by the mutation. These effects cause considerable heterogeneity in phenotypes and symptoms. To characterise the molecular mechanisms underlying the specific VWF deficiencies in VWD 2A/IIC, IID and IIE, we investigated VWF variants with patient-derived mutations either in the VWF pro-peptide or in domains D3 or CK. Additionally to static assays and molecular dynamics (MD) simulations we used microfluidic approaches to perform a detailed investigation of the shear-dependent function of VWD 2A mutants. For each group, we found distinct characteristics in their intracellular localisation visualising specific defects in biosynthesis which are correlated to respective multimer patterns. Using microfluidic assays we further determined shear flow-dependent characteristics in polymer-platelet-aggregate formation, platelet binding and string formation for all mutants. The phenotypes observed under flow conditions were not related to the mutated VWF domain. By MD simulations we further investigated how VWD 2A/IID mutations might alter the ability of VWF to form carboxy-terminal dimers. In conclusion, our study offers a comprehensive picture of shear-dependent and shear-independent dysfunction of VWD type 2A mutants. Furthermore, our microfluidic assay might open new possibilities for diagnosis of new VWD phenotypes and treatment choice for VWD patients with shear-dependent VWF dysfunctions that are currently not detectable by static tests.
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de Jong A, Eikenboom J. Von Willebrand disease mutation spectrum and associated mutation mechanisms. Thromb Res 2017; 159:65-75. [PMID: 28987708 DOI: 10.1016/j.thromres.2017.09.025] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2017] [Revised: 09/13/2017] [Accepted: 09/22/2017] [Indexed: 01/24/2023]
Abstract
Von Willebrand disease (VWD) is a bleeding disorder that is mainly caused by mutations in the multimeric protein von Willebrand factor (VWF). These mutations may lead to deficiencies in plasma VWF or dysfunctional VWF. VWF is a heterogeneous protein and over the past three decades, hundreds of VWF mutations have been identified. In this review we have organized all reported mutations, spanning a timeline from the late eighties until early 2017. This resulted in an overview of 750 unique mutations that are divided over the VWD types 1, 2A, 2B, 2M, 2N and 3. For many of these mutations the disease-causing effects have been characterized in vitro through expression studies, ex vivo by analysis of patient-derived endothelial cells, as well as in animal or (bio)physical models. Here we describe the mechanisms associated with the VWF mutations per VWD type.
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Affiliation(s)
- Annika de Jong
- Department of Internal Medicine, Division of Thrombosis and Hemostasis, Einthoven Laboratory for Vascular and Regenerative Medicine, Leiden University Medical Center, Leiden, The Netherlands
| | - Jeroen Eikenboom
- Department of Internal Medicine, Division of Thrombosis and Hemostasis, Einthoven Laboratory for Vascular and Regenerative Medicine, Leiden University Medical Center, Leiden, The Netherlands.
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Gashash EA, Aloor A, Li D, Zhu H, Xu XQ, Xiao C, Zhang J, Parameswaran A, Song J, Ma C, Xiao W, Wang PG. An Insight into Glyco-Microheterogeneity of Plasma von Willebrand Factor by Mass Spectrometry. J Proteome Res 2017; 16:3348-3362. [PMID: 28696719 PMCID: PMC6309539 DOI: 10.1021/acs.jproteome.7b00359] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Human plasma von Willebrand Factor (VWF) plays essential roles in primary hemostasis in cooperation with other coagulations factors. There is ample indication that glycosylation affects many biological phases during the protein life cycle. However, comprehensive characterization of all probable N-glycosites simultaneous with O-glycosites is still not fully revealed. Thus, the intention of this exploration was to estimate the occupancy of all canonical N-glycosites besides simultaneous characterization of N- and O-glycoforms. An RP-LC-MS/MS system functionalized with CID and HCD tandem mass was utilized to analyze VWF. N-Glycosite occupancy varied along the protein backbone chain. Out of 257 HCD spectra, 181 characterized glycoforms were specified as either N- or O-glycosites. Sequential cleavage of glycosidic bonds along with Human Database mass matching have confirmed the glycoform structures. A total of 173 glycoforms represented most commonly biantennary and infrequently tri- and tetra-antennary N-glycans beside high mannose, hybrid, ABH antigen-terminated, and sulfated N-glycans. Many glycoforms were common across all N-sites. Noteworthy, previously unreported N-glycosites within domain D'(TIL'-E') showed glycosylation. Moreover, sialylated core 1 and core 2 O-glycans were detected on 2298T. Given subtle characterization of site-specific glycoforms, we can attain a profound understanding of the biological roles of VWF as well as facilitate the production of VWF-based therapeutics.
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Affiliation(s)
- Ebtesam A. Gashash
- Center for Diagnostics & Therapeutics and Department of Chemistry, Georgia State University, Atlanta, Georgia 30302, United States
- Department of Chemistry, College of Science, Albaha University, Baljurashi, Albaha 65635, Saudi Arabia
| | - Arya Aloor
- Center for Diagnostics & Therapeutics and Department of Chemistry, Georgia State University, Atlanta, Georgia 30302, United States
| | - Dong Li
- Department of Clinical Laboratory, Shanghai Tongji Hospital, Tongji University School of Medicine, 200065 Shanghai, China
| | - He Zhu
- Center for Diagnostics & Therapeutics and Department of Chemistry, Georgia State University, Atlanta, Georgia 30302, United States
| | - Xiao-Qian Xu
- Department of Hematology, Changhai Hospital, Second Military Medical University, Shanghai, China
| | - Cong Xiao
- Center for Diagnostics & Therapeutics and Department of Chemistry, Georgia State University, Atlanta, Georgia 30302, United States
| | - Junping Zhang
- Sol Sherry Thrombosis Research Center, Temple University, Philadelphia, Pennsylvania 19140, United States
| | - Aishwarya Parameswaran
- Center for Diagnostics & Therapeutics and Department of Chemistry, Georgia State University, Atlanta, Georgia 30302, United States
| | - Jing Song
- Center for Diagnostics & Therapeutics and Department of Chemistry, Georgia State University, Atlanta, Georgia 30302, United States
| | - Cheng Ma
- Center for Diagnostics & Therapeutics and Department of Chemistry, Georgia State University, Atlanta, Georgia 30302, United States
| | - Weidong Xiao
- Sol Sherry Thrombosis Research Center, Temple University, Philadelphia, Pennsylvania 19140, United States
| | - Peng George Wang
- Center for Diagnostics & Therapeutics and Department of Chemistry, Georgia State University, Atlanta, Georgia 30302, United States
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Selvam S, James P. Angiodysplasia in von Willebrand Disease: Understanding the Clinical and Basic Science. Semin Thromb Hemost 2017; 43:572-580. [PMID: 28476066 DOI: 10.1055/s-0037-1599145] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Severe and intractable gastrointestinal bleeding caused by angiodysplasia is a debilitating problem for up to 20% of patients with von Willebrand disease (VWD). Currently, the lack of an optimal treatment for this recurrent problem presents an ongoing challenge for many physicians in their management of affected patients. Over the past few years, studies have pointed to a regulatory role for the hemostatic protein, von Willebrand factor (VWF), in angiogenesis, providing a novel target for the modulation of vessel development. This article will review the clinical implications and molecular pathology of angiodysplasia in VWD.
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Affiliation(s)
- Soundarya Selvam
- Department of Pathology and Molecular Medicine, Queen's University, Kingston, Canada
| | - Paula James
- Department of Pathology and Molecular Medicine, Queen's University, Kingston, Canada.,Department of Medicine, Queen's University, Kingston, Canada
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Swami A, Kaur V. von Willebrand Disease: A Concise Review and Update for the Practicing Physician. Clin Appl Thromb Hemost 2016; 23:900-910. [PMID: 27920237 DOI: 10.1177/1076029616675969] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
von Willebrand disease (vWD) is the most common inherited disorder of hemostasis and comprises a spectrum of heterogeneous subtypes. Significant advances have been made in understanding von Willebrand factor ( vWF) gene mutations, resultant physiologic deficits in the vWF peptide, and their correlation to clinical presentation. Diagnostic tests for this disorder are complex, and interpretation requires a thorough understanding of the underlying pathophysiology by the practicing physician. The objective of this review is to summarize our current understanding of pathophysiology, laboratory investigations, and evolving treatment paradigm of vWD with the availability of recombinant von Willebrand factor.
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Affiliation(s)
| | - Varinder Kaur
- 2 Division of hematology/oncology, Department of Internal Medicine, Vancouver Island Cancer Center, University of British Columbia, British Columbia Cancer Agency, Vancouver, British Columbia, Canada.,3 British Columbia Cancer Agency, Vancouver, British Columbia, Canada
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Obser T, Ledford-Kraemer M, Oyen F, Brehm MA, Denis CV, Marschalek R, Montgomery RR, Sadler JE, Schneppenheim S, Budde U, Schneppenheim R. Identification and characterization of the elusive mutation causing the historical von Willebrand Disease type IIC Miami. J Thromb Haemost 2016; 14:1725-35. [PMID: 27344059 PMCID: PMC5035592 DOI: 10.1111/jth.13398] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2016] [Accepted: 06/15/2016] [Indexed: 11/28/2022]
Abstract
UNLABELLED Essentials Von Willebrand disease IIC Miami features high von Willebrand factor (VWF) with reduced function. We aimed to identify and characterize the elusive underlying mutation in the original family. An inframe duplication of VWF exons 9-10 was identified and characterized. The mutation causes a defect in VWF multimerization and decreased VWF clearance from the circulation. SUMMARY Background A variant of von Willebrand disease (VWD) type 2A, phenotype IIC (VWD2AIIC), is characterized by recessive inheritance, low von Willebrand factor antigen (VWF:Ag), lack of VWF high-molecular-weight multimers, absence of VWF proteolytic fragments and mutations in the VWF propeptide. A family with dominantly inherited VWD2AIIC but markedly elevated VWF:Ag of > 2 U L(-1) was described as VWD type IIC Miami (VWD2AIIC-Miami) in 1993; however, the molecular defect remained elusive. Objectives To identify the molecular mechanism underlying the phenotype of the original VWD2AIIC-Miami. Patients and Methods We studied the original family with VWD2AIIC-Miami phenotypically and by genotyping. The identified mutation was recombinantly expressed and characterized by standard techniques, confocal imaging and in a mouse model, respectively. Results By Multiplex ligation-dependent probe amplification we identified an in-frame duplication of VWF exons 9-10 (c.998_1156dup; p.Glu333_385dup) in all patients. Recombinant mutant (rm)VWF only presented as a dimer. Co-expressed with wild-type VWF, the multimer pattern was indistinguishable from patients' plasma VWF. Immunofluorescence studies indicated retention of rmVWF in unusually large intracellular granules in the endoplasmic reticulum. ADAMTS-13 proteolysis of rmVWF under denaturing conditions was normal; however, an aberrant proteolytic fragment was apparent. A decreased ratio of VWF propeptide to VWF:Ag and a 1-desamino-8-d-arginine vasopressin (DDAVP) test in one patient indicated delayed VWF clearance, which was supported by clearance data after infusion of rmVWF into VWF(-/-) mice. Conclusion The unique phenotype of VWD2 type IIC-Miami results from dominant impairment of multimer assembly, an aberrant structure of mutant mature VWF and reduced clearance in vivo.
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Affiliation(s)
- T Obser
- Department of Pediatric Hematology and Oncology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | | | - F Oyen
- Department of Pediatric Hematology and Oncology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - M A Brehm
- Department of Pediatric Hematology and Oncology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - C V Denis
- INSERM UMR_S 1176, Université Paris-Sud, Université Paris-Saclay, Le Kremlin-Bicetre, France
| | - R Marschalek
- Institute of Pharmaceutical Biology/ZAFES/DCAL, Biocenter, Johann-Wolfgang-Goethe-University Frankfurt, Frankfurt/Main, Germany
| | - R R Montgomery
- Blood Research Institute of Blood Center of Wisconsin and Medical College of Wisconsin, Milwaukee, WI, USA
| | - J E Sadler
- Departments of Medicine and Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO, USA
| | - S Schneppenheim
- Medilys Central Laboratory Coagulation, Asklepios Clinic Altona, Hamburg, Germany
| | - U Budde
- Medilys Central Laboratory Coagulation, Asklepios Clinic Altona, Hamburg, Germany
| | - R Schneppenheim
- Department of Pediatric Hematology and Oncology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
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White-Adams TC, Ng CJ, Jacobi PM, Haberichter SL, Di Paola JA. Mutations in the D'D3 region of VWF traditionally associated with type 1 VWD lead to quantitative and qualitative deficiencies of VWF. Thromb Res 2016; 145:112-8. [PMID: 27533707 DOI: 10.1016/j.thromres.2016.08.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Revised: 07/12/2016] [Accepted: 08/09/2016] [Indexed: 10/21/2022]
Abstract
Type 1 von Willebrand disease (VWD) is characterized by low plasma levels of von Willebrand factor (VWF) and clinical bleeding. Several mechanisms have been described that cause a decrease in plasma VWF levels in VWD, and the goal of this study was to elucidate the pathogenic origins of VWD for a group of mutations in the VWF D'D3 region traditionally associated with type 1 VWD. Varying ratios of mutant-to-wild-type VWF were expressed in two cell lines in order to study the intracellular location, multimer assembly, secretion and function of VWF. We identified four mutants (M771I, Y1146C, T1156M, R782Q) that caused defective intracellular packaging and markedly reduced VWF secretion. Consistent with previous reports, Y1146C and T1156M VWF led to a loss of high molecular weight multimers. In a functional analysis, Y1146C demonstrated a novel FVIII binding defect. Mutations R924W and I1094T were processed normally and did not show abnormal FVIII binding suggesting that other mechanisms such as plasma clearance or platelet binding defects may contribute to the pathogenicity of these mutants.
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Affiliation(s)
- Tara C White-Adams
- Department of Pediatrics, University of Colorado and Children's Hospital Colorado, Aurora, CO, USA
| | - Christopher J Ng
- Department of Pediatrics, University of Colorado and Children's Hospital Colorado, Aurora, CO, USA
| | | | - Sandra L Haberichter
- BloodCenter of Wisconsin, Milwaukee, WI, USA; Department of Pediatrics, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Jorge A Di Paola
- Department of Pediatrics, University of Colorado and Children's Hospital Colorado, Aurora, CO, USA; Human Medical Genetics and Genomics, University of Colorado Denver, Aurora, CO, USA.
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Shameer K, Tripathi LP, Kalari KR, Dudley JT, Sowdhamini R. Interpreting functional effects of coding variants: challenges in proteome-scale prediction, annotation and assessment. Brief Bioinform 2015; 17:841-62. [PMID: 26494363 DOI: 10.1093/bib/bbv084] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2015] [Indexed: 12/20/2022] Open
Abstract
Accurate assessment of genetic variation in human DNA sequencing studies remains a nontrivial challenge in clinical genomics and genome informatics. Ascribing functional roles and/or clinical significances to single nucleotide variants identified from a next-generation sequencing study is an important step in genome interpretation. Experimental characterization of all the observed functional variants is yet impractical; thus, the prediction of functional and/or regulatory impacts of the various mutations using in silico approaches is an important step toward the identification of functionally significant or clinically actionable variants. The relationships between genotypes and the expressed phenotypes are multilayered and biologically complex; such relationships present numerous challenges and at the same time offer various opportunities for the design of in silico variant assessment strategies. Over the past decade, many bioinformatics algorithms have been developed to predict functional consequences of single nucleotide variants in the protein coding regions. In this review, we provide an overview of the bioinformatics resources for the prediction, annotation and visualization of coding single nucleotide variants. We discuss the currently available approaches and major challenges from the perspective of protein sequence, structure, function and interactions that require consideration when interpreting the impact of putatively functional variants. We also discuss the relevance of incorporating integrated workflows for predicting the biomedical impact of the functionally important variations encoded in a genome, exome or transcriptome. Finally, we propose a framework to classify variant assessment approaches and strategies for incorporation of variant assessment within electronic health records.
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[The function and clinical value of Von Willebrand factor propeptide]. ZHONGHUA XUE YE XUE ZA ZHI = ZHONGHUA XUEYEXUE ZAZHI 2015; 36:883-7. [PMID: 26477774 PMCID: PMC7364933 DOI: 10.3760/cma.j.issn.0253-2727.2015.10.019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Abstract
von Willebrand factor (VWF) is a large multimeric glycoprotein that mediates the attachment of platelets to damaged endothelium and also serves as the carrier protein for coagulation factor VIII (FVIII), protecting it from proteolytic degradation. Quantitative or qualitative defects in VWF result in von Willebrand disease (VWD), a common inherited bleeding disorder. VWF is synthesized with a very large propeptide (VWFpp) that is critical for intracellular processing of VWF. VWFpp actively participates in the process of VWF multimerization and is essential for trafficking of VWF to the regulated storage pathway. Mutations identified within VWFpp in VWD patients are associated with altered VWF structure and function. The assay of plasma VWFpp has clinical utility in assessing acute and chronic vascular perturbation associated with diseases such as thrombotic thrombocytopenic purpura, sepsis, and diabetes among others. VWFpp assay also has clear utility in the diagnosis of VWD subtypes, particularly in discriminating true type 3 subjects from type 1C (reduced plasma survival of VWF), which is clinically important and has implications for therapeutic treatment.
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Stockschlaeder M, Schneppenheim R, Budde U. Update on von Willebrand factor multimers: focus on high-molecular-weight multimers and their role in hemostasis. Blood Coagul Fibrinolysis 2014; 25:206-16. [PMID: 24448155 PMCID: PMC3969155 DOI: 10.1097/mbc.0000000000000065] [Citation(s) in RCA: 139] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2013] [Revised: 11/27/2013] [Accepted: 12/04/2013] [Indexed: 12/16/2022]
Abstract
Normal hemostasis requires von Willebrand factor (VWF) to support platelet adhesion and aggregation at sites of vascular injury. VWF is a multimeric glycoprotein built from identical subunits that contain binding sites for both platelet glycoprotein receptors and collagen. The adhesive activity of VWF depends on the size of its multimers, which range from 500 to over 10 000 kDa. There is good evidence that the high-molecular-weight multimers (HMWM), which are 5000-10 000 kDa, are the most effective in supporting interaction with collagen and platelet receptors and in facilitating wound healing under conditions of shear stress. Thus, these HMWM of VWF are of particular clinical interest. The unusually large multimers of VWF are, under normal conditions, cleaved by the plasma metalloproteinase ADAMTS13 to smaller, less adhesive multimers. A reduction or lack of HMWM, owing to a multimerization defect of VWF or to an increased susceptibility of VWF for ADAMTS13, leads to a functionally impaired VWF and the particular type 2A of von Willebrand disease. This review considers the biology and function of VWF multimers with a particular focus on the characterization of HMWM - their production, storage, release, degradation, and role in normal physiology. Evidence from basic research and the study of clinical diseases and their management highlight a pivotal role for the HMWM of VWF in hemostasis.
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Affiliation(s)
| | - Reinhard Schneppenheim
- Department of Pediatric Hematology and Oncology, University Medical Center Hamburg-Eppendorf
| | - Ulrich Budde
- Department of Hemostaseology, Medilys Laborgesellschaft, Hamburg, Germany
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Abstract
PURPOSE OF REVIEW Von Willebrand disease (VWD) is an autosomally inherited bleeding disorder caused by a deficiency or abnormality of von Willebrand factor (VWF). VWF is a multimeric adhesive protein produced mainly by the endothelial cells. VWF is crucial in primary hemostasis because it promotes platelet adhesion to the subendothelium at the sites of vascular injury and in coagulation because VWF is the carrier of factor VIII. VWD is highly heterogeneous because the molecular mechanisms underlying the different clinical and laboratory phenotypes may be complex. VWD is classified into quantitative deficiencies of VWF (type 1 and type 3 VWD) and qualitative variants (type 2 VWD), because of a dysfunctional VWF. Whereas inheritance is autosomal dominant and bleeding tendency is heterogeneous in type 1 and 2, type 3 patients present moderate-to-severe bleeding diathesis and display a recessive pattern of inheritance. RECENT FINDINGS Although the responsible genetic background has been extensively clarified over the recent years, providing insights on the structure-function relationship of the protein, the cellular basis of the disorder is being investigated for a few mutations only recently. In several cases, increased clearance of the mutant VWF may be responsible for the disease. Standardized criteria for the definition of bleeding history and appropriate history collection are now available, but estimates of bleeding risk are largely lacking. SUMMARY VWD, the most frequent inherited bleeding disorder, has been the subject of extensive pathophysiological and clinical studies. The novel evidences provide accurate insights on the mechanisms of the disease and the bleeding risk associated with VWF deficiency or abnormality.
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Hampshire DJ, Abuzenadah AM, Cartwright A, Al-Shammari NS, Coyle RE, Eckert M, Al-Buhairan AM, Messenger SL, Budde U, Gürsel T, Ingerslev J, Peake IR, Goodeve AC. Identification and characterisation of mutations associated with von Willebrand disease in a Turkish patient cohort. Thromb Haemost 2013; 110:264-74. [PMID: 23702511 DOI: 10.1160/th13-02-0135] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2013] [Accepted: 05/04/2013] [Indexed: 11/05/2022]
Abstract
Several cohort studies have investigated the molecular basis of von Willebrand disease (VWD); however, these have mostly focused on European and North American populations. This study aimed to investigate mutation spectrum in 26 index cases (IC) from Turkey diagnosed with all three VWD types, the majority (73%) with parents who were knowingly related. IC were screened for mutations using multiplex ligation-dependent probe amplification and analysis of all von Willebrand factor gene (VWF) exons and exon/intron boundaries. Selected missense mutations were expressed in vitro. Candidate VWF mutations were identified in 25 of 26 IC and included propeptide missense mutations in four IC (two resulting in type 1 and two in recessive 2A), all influencing VWF expression in vitro. Four missense mutations, a nonsense mutation and a small in-frame insertion resulting in type 2A were also identified. Of 15 type 3 VWD IC, 13 were homozygous and two compound heterozygous for 14 candidate mutations predicted to result in lack of expression and two propeptide missense changes. Identification of intronic breakpoints of an exon 17-18 deletion suggested that the mutation resulted from non-homologous end joining. This study provides further insight into the pathogenesis of VWD in a population with a high degree of consanguineous partnerships.
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Affiliation(s)
- Daniel J Hampshire
- Haemostasis Research Group, Department of Cardiovascular Science, Faculty of Medicine, Dentistry and Health, University of Sheffield, Beech Hill Road, Sheffield, UK.
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20
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Enayat MS, Ravanbod S, Rassoulzadegan M, Jazebi M, Ala F, Budde U, Schneppenheim S, Obser T, Schneppenheim R. Identification of a homozygous Cys410Ser mutation in the von Willebrand factor D2 domain causing type 2A(IIC) von Willebrand disease phenotype in an Iranian patient. Haemophilia 2013; 19:e261-4. [DOI: 10.1111/hae.12161] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/02/2013] [Indexed: 11/29/2022]
Affiliation(s)
- M. S. Enayat
- Iranian Comprehensive Haemophilia Care Centre; Tehran; (IR)Iran
| | - S. Ravanbod
- Iranian Comprehensive Haemophilia Care Centre; Tehran; (IR)Iran
| | | | - M. Jazebi
- Iranian Comprehensive Haemophilia Care Centre; Tehran; (IR)Iran
| | - F. Ala
- Iranian Comprehensive Haemophilia Care Centre; Tehran; (IR)Iran
| | - U. Budde
- Asklepios Clinic Altona; Medilys Central Laboratory Coagulation; Hamburg; Germany
| | - S. Schneppenheim
- Asklepios Clinic Altona; Medilys Central Laboratory Coagulation; Hamburg; Germany
| | - T. Obser
- Department of Paediatric Haematology and Oncology; University Medical Centre Hamburg-Eppendorf; Hamburg; Germany
| | - R. Schneppenheim
- Department of Paediatric Haematology and Oncology; University Medical Centre Hamburg-Eppendorf; Hamburg; Germany
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21
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Yadegari H, Driesen J, Pavlova A, Biswas A, Ivaskevicius V, Klamroth R, Oldenburg J. Insights into pathological mechanisms of missense mutations in C-terminal domains of von Willebrand factor causing qualitative or quantitative von Willebrand disease. Haematologica 2013; 98:1315-23. [PMID: 23539537 DOI: 10.3324/haematol.2013.084111] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
The carboxyl-terminal domains of von Willebrand factor, D4-CK, are cysteine-rich implying that they are structurally important. In this study we characterized the impact of five cysteine missense mutations residing in D4-CK domains on the conformation and biosynthesis of von Willebrand factor. These variants were identified as heterozygous in type 1 (p.Cys2619Tyr and p.Cys2676Phe), type 2A (p.Cys2085Tyr and p.Cys2327Trp) and as compound heterozygous in type 3 (p.Cys2283Arg) von Willebrand disease. Transient expression of human cell lines with wild-type or mutant von Willebrand factor constructs was performed. The mutated and wild-type recombinant von Willebrand factors were quantitatively and qualitatively assessed and compared. Storage of von Willebrand factor in pseudo-Weibel-Palade bodies was studied with confocal microscopy. The structural impact of the mutations was analyzed by homology modeling. Homozygous expressions showed that these mutations caused defects in multimerization, elongation of pseudo-Weibel-Palade bodies and secretion of von Willebrand factor. Co-expressions of wild-type von Willebrand factor and p.Cys2085Tyr, p.Cys2327Trp and p.Cys2283Arg demonstrated defective multimer assembly, suggesting a new pathological mechanism for dominant type 2A von Willebrand disease due to mutations in D4 and B domains. Structural analysis revealed that mutations p.Cys2283Arg, p.Cys2619Tyr and p.Cys2676Phe disrupted intra-domain disulfide bonds, whereas p.Cys2327Trp might affect an inter-domain disulfide bond. The p.Cys2327Trp variant is distinguished from the other mutants by an electrophoretic mobility shift of the multimer bands. The results highlight the importance of cysteine residues within the carboxyl-terminal of von Willebrand factor on structural conformation of the protein and consequently multimerization, storage, and secretion of von Willebrand factor.
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Affiliation(s)
- Hamideh Yadegari
- Institute of Experimental Haematology and Transfusion Medicine, University Clinics Bonn, Germany
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Analysis of the storage and secretion of von Willebrand factor in blood outgrowth endothelial cells derived from patients with von Willebrand disease. Blood 2013; 121:2762-72. [PMID: 23426949 DOI: 10.1182/blood-2012-06-434373] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Patients with von Willebrand disease (VWD) are often heterozygous for a missense mutation in the von Willebrand factor (VWF) gene. Investigating the pathogenic features of VWF mutations in cells directly derived from patients has been challenging. Here, we have used blood outgrowth endothelial cells (BOECs) isolated from human peripheral blood to analyze the storage and secretion of VWF. BOECs showed full endothelial characteristics and responded to Weibel-Palade body (WPB) secretagogues except desmopressin. We examined BOECs derived from a single subject heterozygous for a type 2N mutation (p.Arg854Gln) and from 4 patients with type 1 VWD who were, respectively, heterozygous for p.Ser1285Pro, p.Leu1307Pro, p.Tyr1584Cys, and p.Cys2693Tyr. Compared with normal BOECs, BOECs heterozygous for p.Ser1285Pro, p.Leu1307Pro, or p.Cys2693Tyr showed morphologically abnormal WPB and retention of VWF in the endoplasmic reticulum, whereas BOECs heterozygous for p.Arg854Gln or p.Tyr1584Cys showed normal WPB. The agonist-induced exocytosis of WPB from BOECs and formation of VWF strings on BOECs heterozygous for p.Ser1285Pro, p.Leu1307Pro, or p.Cys2693Tyr, but not for p.Arg854Gln or p.Tyr1584Cys, were reduced. In conclusion, VWD phenotype can be recapitulated in BOECs, and thus BOECs provide a feasible bona fide cell model to study the pathogenic effects of VWF mutations.
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Berber E. The molecular genetics of von Willebrand disease. Turk J Haematol 2012; 29:313-24. [PMID: 24385719 PMCID: PMC3781629 DOI: 10.5505/tjh.2012.39205] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2011] [Accepted: 04/24/2012] [Indexed: 01/25/2023] Open
Abstract
Quantitative and/or qualitative deficiency of von Willebrand factor (vWF) is associated with the most common inherited bleeding disease von Willebrand disease (vWD). vWD is a complex disease with clinical and genetic heterogeneity. Incomplete penetrance and variable expression due to genetic and environmental factors contribute to its complexity. vWD also has a complex molecular pathogenesis. Some vWF gene mutations are associated with the affected vWF biosynthesis and multimerization, whereas others are associated with increased clearance and functional impairment. Moreover, in addition to a particular mutation, type O blood may result in the more severe phenotype. The present review aimed to provide a summary of the current literature on the molecular genetics of vWD. Conflict of interest:None declared.
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Affiliation(s)
- Ergül Berber
- İstanbul Arel University, Department of Molecular Biology and Genetics, İstanbul, Turkey
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Castaman G, Giacomelli SH, Jacobi PM, Obser T, Budde U, Rodeghiero F, Schneppenheim R, Haberichter SL. Reduced von Willebrand factor secretion is associated with loss of Weibel-Palade body formation. J Thromb Haemost 2012; 10:951-8. [PMID: 22429825 DOI: 10.1111/j.1538-7836.2012.04702.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
BACKGROUND von Willebrand disease (VWD) is caused by mutations in von Willebrand factor (VWF) that have different pathophysiologic effect in causing low plasma VWF levels. Type 1 VWD includes quantitative plasma VWF deficiency with normal VWF structure and function. OBJECTIVES We report three novel type 1 VWF mutations (A1716P, C2190Y and R2663C) located in different VWF domains that are associated with reduced secretion and reduced formation of elongated Weibel-Palade body (WPB)-like granules. METHODS Transient expression of recombinant mutant full-length VWF in 293 EBNA cells was performed and secretion, collagen binding and GpIb binding assessed in comparison with wild-type VWF. Expression was also examined in HEK293 cells that form WPB-like granules when transfected with wild-type VWF. RESULTS Laboratory results and multimer analysis of plasma VWF was compatible with type 1 VWD. Expression experiments demonstrated slightly reduced VWF synthesis and drastically impaired secretion upon homozygous expression. In HEK293 cells, homozygous expression of A1716P and C2190Y VWF variants failed to form elongated WPB-like granules, while R2663C was capable of WPB-like granules. Heterozygous expression of VWF variants had a negative impact on wild-type VWF with a reduction in elongated WPB-like granules in co-transfected cells. CONCLUSIONS Our results demonstrate that homozygous and heterozygous quantitative VWF deficiency caused by missense VWF mutations in different VWF domains can be associated with inability to form endothelial WPB-like granules.
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Affiliation(s)
- G Castaman
- Department of Cellular Therapy and Hematology, San Bortolo Hospital, Vicenza, Italy.
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Intersection of mechanisms of type 2A VWD through defects in VWF multimerization, secretion, ADAMTS-13 susceptibility, and regulated storage. Blood 2012; 119:4543-53. [PMID: 22431572 DOI: 10.1182/blood-2011-06-360875] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Type 2A VWD is characterized by the absence of large VWF multimers and decreased platelet-binding function. Historically, type 2A variants are subdivided into group 1, which have impaired assembly and secretion of VWF multimers, or group 2, which have normal secretion of VWF multimers and increased ADAMTS13 proteolysis. Type 2A VWD patients recruited through the T. S. Zimmerman Program for the Molecular and Clinical Biology of VWD study were characterized phenotypically and potential mutations identified in the VWF D2, D3, A1, and A2 domains. We examined type 2A variants and their interaction with WT-VWF through expression studies. We assessed secretion/intracellular retention, multimerization, regulated storage, and ADAMTS13 proteolysis. Whereas some variants fit into the traditional group 1 or 2 categories, others did not fall clearly into either category. We determined that loss of Weibel-Palade body formation is associated with markedly reduced secretion. Mutations involving cysteines were likely to cause abnormalities in multimer structure but not necessarily secretion. When coexpressed with wild-type VWF, type 2A variants negatively affected one or more mechanisms important for normal VWF processing. Type 2A VWD appears to result from a complex intersection of mechanisms that include: (1) intracellular retention or degradation of VWF, (2) defective multimerization, (3) loss of regulated storage, and (4) increased proteolysis by ADAMTS13.
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Schneppenheim R, Budde U. von Willebrand factor: the complex molecular genetics of a multidomain and multifunctional protein. J Thromb Haemost 2011; 9 Suppl 1:209-15. [PMID: 21781257 DOI: 10.1111/j.1538-7836.2011.04324.x] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
von Willebrand disease (VWD), the most common inherited bleeding disorder in humans, is characterised by a prolonged bleeding time due to quantitative and/or functional deficits of von Willebrand factor (VWF), a huge multimeric protein. Given the large size and complexity of the protein, the many functions of VWF, for example, binding to collagen, to platelet GPIb, and to FVIII, the localisation of these binding sites in different VWF domains, as well as the dependence on a high molecular weight multimer structure for proper function, VWF is prone to quantitative and very heterogeneous structural and functional defects. Comprehensive clinical and laboratory phenotypic description of patients with VWD in correlation to the genotype has considerably increased our knowledge on this disorder and the physiology and pathophysiology of VWF. This article focuses on the phenotype/genotype relationship in VWD and the context of VWD types and subtypes with particular VWF domains.
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Affiliation(s)
- R Schneppenheim
- Department of Paediatric Haematology and Oncology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
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Abstract
Weibel-Palade bodies (WPBs) are elongated secretory organelles specific to endothelial cells that contain von Willebrand factor (VWF) and a variety of other proteins that contribute to inflammation, angiogenesis, and tissue repair. The remarkable architecture of WPBs is because of the unique properties of their major constituent VWF. VWF is stored inside WPBs as tubules, but on its release, forms strikingly long strings that arrest bleeding by recruiting blood platelets to sites of vascular injury. In recent years considerable progress has been made regarding the molecular events that underlie the packaging of VWF multimers into tubules and the processes leading to the formation of elongated WPBs. Mechanisms directing the conversion of tightly packaged VWF tubules into VWF strings on the surface of endothelial cells are starting to be unraveled. Several modes of exocytosis have now been described for WPBs, emphasizing the plasticity of these organelles. WPB exocytosis plays a role in the pathophysiology and treatment of von Willebrand disease and may have impact on common hematologic and cardiovascular disorders. This review summarizes the major advances made on the biogenesis and exocytosis of WPBs and places these recent discoveries in the context of von Willebrand disease.
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Castaman G, Giacomelli SH, Jacobi P, Obser T, Budde U, Rodeghiero F, Haberichter SL, Schneppenheim R. Homozygous type 2N R854W von Willebrand factor is poorly secreted and causes a severe von Willebrand disease phenotype. J Thromb Haemost 2010; 8:2011-6. [PMID: 20586924 DOI: 10.1111/j.1538-7836.2010.03971.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
BACKGROUND von Willebrand disease (VWD) type Normandy (VWD 2N) is caused by mutations at the factor (F)VIII-binding site of von Willebrand factor (VWF), located in the D'and D3 domains on the N-terminus of mature VWF. The R854Q mutation is the most frequent cause of this phenotype. OBJECTIVES We report the characterization of a homozygous VWD 2N mutation, R854W, detected in a patient with a severe VWD phenotype. METHODS The plasma VWF phenotype was studied, transient expression of recombinant mutant full-length VWF in 293 EBNA cells was performed, and the results were compared with those obtained with wild-type (WT) VWF. Furthermore, expression was also examined in HEK293 cells, which form Weibel-Palade body-like granules when transfected with WT VWF. RESULTS The multimer analysis of plasma VWF showed the lack of the typical triplet structure, with the presence of the central band only, and a relative decrease in the high molecular mass multimers. Homozygous expression of recombinant R854W VWF resulted in normal amounts of cellular VWF, but with a severe reduction in secretion into the medium. Severe reductions in FVIII binding to R854W VWF, glycoprotein Ib binding activity and collagen binding of secreted W854 VWF was observed, and reproduced the phenotypic parameters of plasma VWF. In HEK293 cells, homozygous R854W VWF failed to form Weibel-Palade body-like granules. CONCLUSIONS Our results demonstrate that a homozygous R854W mutation in the D' domain of VWF induces impaired secretion and activity of the protein, thereby explaining the severe phenotype of the patient.
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Affiliation(s)
- G Castaman
- Department of Cellular Therapy and Haematology, San Bortolo Hospital, Vicenza, Italy.
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Specific N-linked glycosylation sites modulate synthesis and secretion of von Willebrand factor. Blood 2010; 116:640-8. [PMID: 20418283 DOI: 10.1182/blood-2010-02-267450] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We examined the role that N-linked glycans play in the synthesis and expression of von Willebrand Factor (VWF). Blocking the addition of N-linked glycans (NLGs) or inhibiting initial glycan processing prevented secretion of VWF. To determine whether specific glycosylation sites were important, the 16 VWF N-linked glycosylation sites were mutated followed by expression in HEK293T cells. Four NLG mutants affected VWF expression: N99Q (D1 domain), N857Q (D' domain), N2400Q (B1 domain), and N2790Q (CK domain) either abolished or reduced secretion of VWF and this was confirmed by metabolic labeling. Multimer analysis of mutant N2790Q cell lysate revealed an increase in VWF monomers, which was also observed when the isolated CK domain was expressed with N2790 mutated. Immunofluorescence microscopy showed that mutants N99Q, N857Q, and N2790Q were primarily retained within the ER, producing only few pseudo Weibel-Palade bodies over longer time periods compared with wtVWF. All the variants also showed an increase in free thiol reactivity. This was greatest with N857Q and D4-C2 NLG mutants, which had approximately 6-fold and 3- to 4-fold more free thiol reactivity than wtVWF. These data provide further evidence of the critical role that individual N-linked glycans play in determining VWF synthesis and expression.
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