Sialylation on O-linked glycans protects von Willebrand factor from macrophage galactose lectin mediated clearance
Author(s)
Type
Journal Article
Abstract
Terminal sialylation determines the plasma half-life of von Willebrand factor (VWF). A role for macrophage galactose lectin (MGL) in regulating hyposialylated VWF clearance has recently been proposed. In this study, we showed that MGL influences physiological plasma VWF clearance. MGL inhibition was associated with a significantly extended mean residence time and 3-fold increase in endogenous plasma VWF antigen levels (P<0.05). Using a series of VWF truncations, we further demonstrated that the A1 domain of VWF is predominantly responsible for enabling the MGL interaction. Binding of both full-length and VWF-A1-A2-A3 to MGL was significantly enhanced in the presence of ristocetin (P<0.05), suggesting that the MGL-binding site in A1 is not fully accessible in globular VWF. Additional studies using different VWF glycoforms demonstrated that VWF O-linked glycans, clustered at either end of the A1 domain, play a key role in protecting VWF against MGLmediated clearance. Reduced sialylation has been associated with pathological, increased clearance of VWF in patients with von Willebrand disease. Herein, we demonstrate that specific loss of α2-3 linked sialylation from O-glycans results in markedly increased MGL-binding in vitro, and markedly enhanced MGL-mediated clearance of VWF in vivo. Our data further show that the asialoglycoprotein receptor (ASGPR) does not have a significant role in mediating the increased clearance of VWF following loss of O-sialylation. Conversely however, we observed that loss of N-linked sialylation from VWF drives enhanced circulatory clearance predominantly via the ASGPR. Collectively, our data support the hypothesis that in addition to regulating physiological VWF clearance, the MGL receptor works in tandem with ASGPR to modulate enhanced clearance of aberrantly sialylated VWF in the pathogenesis of von Willebrand disease.
Date Issued
2021-03-25
Date Acceptance
2021-03-12
Citation
Haematologica, 2021, 107 (3), pp.668-679
ISSN
0390-6078
Publisher
Ferrata Storti Foundation (Haematologica)
Start Page
668
End Page
679
Journal / Book Title
Haematologica
Volume
107
Issue
3
Copyright Statement
©2022 Ferrata Storti Foundation
Material published in Haematologica is covered by copyright.
All rights are reserved to the Ferrata Storti Foundation. Use of
published material is allowed under the following terms and
conditions:
https://creativecommons.org/licenses/by-nc/4.0/legalcode.
Copies of published material are allowed for personal or internal use. Sharing published material for non-commercial purposes is subject to the following conditions:
https://creativecommons.org/licenses/by-nc/4.0/legalcode,
sect. 3. Reproducing and sharing published material for commercial purposes is not allowed without permission in writing
from the publisher.
Material published in Haematologica is covered by copyright.
All rights are reserved to the Ferrata Storti Foundation. Use of
published material is allowed under the following terms and
conditions:
https://creativecommons.org/licenses/by-nc/4.0/legalcode.
Copies of published material are allowed for personal or internal use. Sharing published material for non-commercial purposes is subject to the following conditions:
https://creativecommons.org/licenses/by-nc/4.0/legalcode,
sect. 3. Reproducing and sharing published material for commercial purposes is not allowed without permission in writing
from the publisher.
License URL
Identifier
https://haematologica.org/article/view/haematol.2020.274720
Subjects
Immunology
1102 Cardiorespiratory Medicine and Haematology
Publication Status
Published
Date Publish Online
2021-03-25