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Characterization of large in-frame von Willebrand factor deletions highlights differing pathogenic mechanisms. Blood Adv 2021; 4:2979-2990. [PMID: 32609846 DOI: 10.1182/bloodadvances.2018027813] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2018] [Accepted: 05/02/2020] [Indexed: 11/20/2022] Open
Abstract
Copy number variation (CNV) is known to cause all von Willebrand disease (VWD) types, although the associated pathogenic mechanisms involved have not been extensively studied. Notably, in-frame CNV provides a unique opportunity to investigate how specific von Willebrand factor (VWF) domains influence the processing and packaging of the protein. Using multiplex ligation-dependent probe amplification, this study determined the extent to which CNV contributed to VWD in the Molecular and Clinical Markers for the Diagnosis and Management of Type 1 von Willebrand Disease cohort, highlighting in-frame deletions of exons 3, 4-5, 32-34, and 33-34. Heterozygous in vitro recombinant VWF expression demonstrated that, although deletion of exons 3, 32-34, and 33-34 all resulted in significant reductions in total VWF (P < .0001, P < .001, and P < .01, respectively), only deletion of exons 3 and 32-34 had a significant impact on VWF secretion (P < .0001). High-resolution microscopy of heterozygous and homozygous deletions confirmed these observations, indicating that deletion of exons 3 and 32-34 severely impaired pseudo-Weibel-Palade body (WPB) formation, whereas deletion of exons 33-34 did not, with this variant still exhibiting pseudo-WPB formation similar to wild-type VWF. In-frame deletions in VWD, therefore, contribute to pathogenesis via moderate or severe defects in VWF biosynthesis and secretion.
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Daidone V, Galletta E, De Marco L, Casonato A. Cryptic non-canonical splice site activation is part of the mechanism that abolishes multimer organization in the c.2269_2270del von Willebrand factor. Haematologica 2019; 105:1120-1128. [PMID: 31320553 PMCID: PMC7109749 DOI: 10.3324/haematol.2019.222679] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2019] [Accepted: 07/10/2019] [Indexed: 12/20/2022] Open
Abstract
We report a new pathogenic mechanism in von Willebrand disease involving the use of a non-canonical splicing site. The proband, carrying the homozygous c.2269_2270del mutation previously classified as a type 3 mutation, showed severely reduced plasma and platelet von Willebrand factor antigen levels and functions, and no factor VIII binding capacity. A particular von Willebrand factor multimer pattern emerged in plasma, characterized by the presence of only two oligomers: the dimer and an unusually large band, with no intermediate components. There were von Willebrand factor multimers in platelets, but each band ran more slowly than the normal counterpart. No anti-von Willebrand factor antibodies were detectable. The proband was classified as having severe type 1 von Willebrand disease. Seeking the relationship between phenotype and genotype, we found the c.2269_2270del mutation associated with three different RNA: r.2269_2270del (RNAI), giving a truncated von Willebrand factor protein; r.[2269_2270del;2282_2288del] (RNAII), resulting from activation of a cryptic “AG” splicing site; and r.[2269_2270del;2281_2282insAG] (RNAIII), where the wild-type “AG” acceptor of exon 18 was retained due to the non-canonical 2279-2280 “CG” acceptor splicing site being used. The aberrant RNAII and RNAIII caused the alteration of the furin cleavage and binding sites, respectively, both resulting in a von Willebrand factor protein characterized by the persistence of von Willebrand factor propeptide, as confirmed by western blot analysis of the recombinant mutated von Willebrand factor molecules produced in vitro. Taken together, these findings explain the residual von Willebrand factor synthesis, slower-running multimers, and absent factor VIII binding capacity. The apparently pure gene null mutation c.2269_2270del profoundly alters von Willebrand factor gene splicing, inducing a complex RNA expression pattern.
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Affiliation(s)
- Viviana Daidone
- University of Padua Medical School, Depar tment of Medicine, First Chair of Internal Medicine, Padua
| | - Eva Galletta
- University of Padua Medical School, Depar tment of Medicine, First Chair of Internal Medicine, Padua
| | - Luigi De Marco
- IRCCS, C.R.O. Aviano, Depar tment of Translational Research, Stem Cells Unit, Aviano, Italy
| | - Alessandra Casonato
- University of Padua Medical School, Depar tment of Medicine, First Chair of Internal Medicine, Padua
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Nolasco JG, Nolasco LH, Da Q, Cirlos S, Ruggeri ZM, Moake JL, Cruz MA. Complement Component C3 Binds to the A3 Domain of von Willebrand Factor. TH OPEN 2018; 2:e338-e345. [PMID: 31080944 PMCID: PMC6508891 DOI: 10.1055/s-0038-1672189] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
von Willebrand factor (VWF) is a multimeric protein composed of monomeric subunits (∼280 kD) linked by disulfide bonds. During hemostasis and thrombosis, ultralarge (UL) VWF (ULVWF) multimers initiate platelet adhesion. In vitro, human C3 binds to ULVWF multimeric strings secreted by and anchored to human endothelial cell to promote the assembly and activation of C3 convertase (C3bBb) and C5 convertase (C3bBbC3b) of the alternative complement pathway (AP). The purified and soluble C3 avidly binds to recombinant human VWF A1A2A3, as well as the recombinant isolated human VWF A3 domain. Notably, the binding of soluble human ULVWF multimers to purified human C3 was blocked by addition of a monovalent Fab fragment antibody to the VWF A3 domain. We conclude that the A3 domain in VWF/ULVWF contains a docking site for C3. In contrast, purified human C4, an essential component of the classical and lectin complement pathways, binds to soluble, isolated A1, but not to ULVWF strings secreted by and anchored to endothelial cells. Our findings should facilitate the design of new therapeutic agents to suppress the initiation of the AP on ULVWF multimeric strings during thrombotic and inflammatory disorders.
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Affiliation(s)
- Jennifer G Nolasco
- Section of Cardiovascular Research, Department of Medicine, Baylor College of Medicine, Houston, Texas, United States
| | - Leticia H Nolasco
- Department of Bioengineering, Rice University, Houston, Texas, United States
| | - Qi Da
- Section of Cardiovascular Research, Department of Medicine, Baylor College of Medicine, Houston, Texas, United States.,Center for Translational Research on Inflammatory Diseases (CTRID), Michael E. DeBakey VA Medical Center, Houston, Texas, United States
| | - Sonya Cirlos
- Section of Cardiovascular Research, Department of Medicine, Baylor College of Medicine, Houston, Texas, United States.,Center for Translational Research on Inflammatory Diseases (CTRID), Michael E. DeBakey VA Medical Center, Houston, Texas, United States
| | - Zaverio M Ruggeri
- Department of Molecular Medicine, MERU-Roon Research Center on Vascular Biology, The Scripps Research Institute, La Jolla, California, United States
| | - Joel L Moake
- Department of Bioengineering, Rice University, Houston, Texas, United States
| | - Miguel A Cruz
- Section of Cardiovascular Research, Department of Medicine, Baylor College of Medicine, Houston, Texas, United States.,Center for Translational Research on Inflammatory Diseases (CTRID), Michael E. DeBakey VA Medical Center, Houston, Texas, United States
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Abstract
Collagens mediate essential hemostasis by maintaining the integrity and stability of the vascular wall. Imbalanced turnover of collagens by uncontrolled formation and/or degradation may result in pathologic conditions such as fibrosis. Thickening of the vessel wall because of accumulation of collagens may lead to arterial occlusion or thrombosis. Thinning of the wall because of collagen degradation or deficiency may lead to rupture of the vessel wall or aneurysm. Preventing excessive hemorrhage or thrombosis relies on collagen-mediated actions. Von Willebrand factor, integrins and glycoprotein VI, as well as clotting factors, can bind collagen to restore normal hemostasis after trauma. This review outlines the essential roles of collagens in mediating hemostasis, with a focus on collagens types I, III, IV, VI, XV, and XVIII.
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Affiliation(s)
| | - N G Kjeld
- Nordic Bioscience A/S, Herlev, Denmark
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Casonato A, Pontara E, Morpurgo M, Sartorello F, De Groot PG, Cattini MG, Daidone V, De Marco L. Higher and lower active circulating VWF levels: different facets of von Willebrand disease. Br J Haematol 2015; 171:845-53. [DOI: 10.1111/bjh.13785] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2015] [Accepted: 08/03/2015] [Indexed: 11/30/2022]
Affiliation(s)
| | - Elena Pontara
- Department of Cardiologic, Thoracic and Vascular Sciences; University of Padua; Padua Italy
| | - Margherita Morpurgo
- Pharmaceutical Chemistry and Pharmacology Department; University of Padua; Padua Italy
| | | | - Philip G. De Groot
- Department of Clinical Chemistry and Haematology; University Medical Centre Utrecht; Utrecht the Netherlands
| | - Maria G. Cattini
- Department of Cardiologic, Thoracic and Vascular Sciences; University of Padua; Padua Italy
| | - Viviana Daidone
- Department of Cardiologic, Thoracic and Vascular Sciences; University of Padua; Padua Italy
| | - Luigi De Marco
- Department of Translational Research; Stem Cells Unit; IRCCS; C.R.O.; Aviano Italy
- Department of Molecular Medicine; The Scripps Research Institute; La Jolla CA USA
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