R1205H (Vicenza) causes conformational changes in the von Willebrand factor D′D3 domains and enhances von Willebrand factor binding to clearance receptors LRP1 and SR-AI
Ferdows Atiq 1), Orla Rawley 2), Jamie M. O’Sullivan 1), Mehmet Özbil 3), Dearbhla Doherty 1), Niamh Cooke 4), Virginie Terraube 4), Alain Chion 1), Aamir Amin 1), Anne-Marije Hulshof 1), Bogdan Baci 1), Ciara Byrne 1), Hanan E. Aburawi 1), David Lillicrap 2), James S. O’Donnell 1) 5) 1)
1-Irish Centre for Vascular Biology, School of Pharmacy and Biomolecular Sciences, Royal College of Surgeons in Ireland, Dublin, Ireland
2-Department of Pathology and Molecular Medicine, Queen’s University, Kingston, Ontario, Canada
3-Computational Biochemistry Group, Gebze Technical University, Institute of Biotechnology, Gebze, Kocaeli, Turkey
4-BioMedicine Design, Pfizer, Grange Castle, Dublin, Ireland
5-National Coagulation Centre, St James’s Hospital, Dublin, Ireland
Abstract
Background
von Willebrand factor (VWF)-R1205H variant (Vicenza) results in markedly enhanced VWF clearance in humans that has been shown to be largely macrophage-mediated. However, the biological mechanisms underlying this enhanced clearance remain poorly understood.
Objectives
This study aimed to investigate the roles of (i) specific VWF domains and (ii) different macrophage receptors in regulating enhanced VWF-R1205H clearance.
Methods
In vivo clearance of full-length and truncated wild-type (WT)-VWF and VWF with R1205 substitutions was investigated in VWF−/− mice. Plate-binding assays were employed to characterize VWF binding to purified scavenger receptor class A member 1 (SR-AI), low-density lipoprotein receptor–related protein-1 (LRP1) cluster II or cluster IV receptors, and macrophage galactose-type lectin.
Results
In full-length VWF missing the A1 domain, introduction of R1205H led to significantly enhanced clearance in VWF−/− mice compared with WT-VWF missing the A1 domain. Importantly, R1205H in a truncated VWF-D′D3 fragment also triggered increased clearance compared with WT-VWF-D′D3. Additional in vivo studies demonstrated that VWF-R1205K (which preserves the positive charge at 1205) exhibited normal clearance, whereas VWF-R1205E (which results in loss of the positive charge) caused significantly enhanced clearance, pinpointing the importance of the positive charge at VWF-R1205. In vitro plate-binding studies confirmed increased VWF-R1205H interaction with SR-AI compared with WT-VWF. Furthermore, significantly enhanced VWF-R1205H binding to LRP1 cluster IV (P < .001) and less marked enhanced binding to LRP1 cluster II (P = .034) was observed. In contrast, VWF-R1205H and WT-VWF demonstrated no difference in binding affinity to macrophage galactose-type lectin.
Conclusion
Disruption of the positive charge at amino acid R1205 causes conformational changes in the VWF-D′D3 domains and triggers enhanced LRP1-mediated and SR-AI–mediated clearance.