scholarly journals Internal Tensile Force and A2 Domain Unfolding of von Willebrand Factor Multimers in Shear Flow

2018 ◽  
Author(s):  
Michael Morabito ◽  
Chuqiao Dong ◽  
Wei Wei ◽  
Xuanhong Cheng ◽  
Xiaohui F. Zhang ◽  
...  
Keyword(s):  
Shear Rate ◽  
Shear Flow ◽  
Von Willebrand Factor ◽  
Mechanical Response ◽  
Tensile Force ◽  
Convincing Evidence ◽  
Force Extension ◽  
Von Willebrand ◽  
A2 Domain ◽  
Willebrand Factor

ABSTRACTUsing Brownian molecular dynamics simulations, we examine the internal dynamics and biomechanical response of von Willebrand Factor (vWF) multimers subject to shear flow. The coarse grain multimer description employed here is based on a monomer model in which the A2 domain of vWF is explicitly represented by a non-linear elastic spring whose mechanical response was fit to experimental force/extension data from vWF monomers. This permits examination of the dynamic behavior of hydrodynamic forces acting on A2 domains as a function of shear rate and multimer length, as well as position of an A2 domain along the multimer contour. Force/position data reveal that collapsed multimers exhibit a force distribution with two peaks, one near each end of the chain; unraveled multimers, however, show a single peak in A2 domain force near the center of multimers. Guided further by experimental data, significant excursions of force acting on a domain are associated with an increasing probability for A2 domain unfolding. Our results suggest that the threshold shear rate required to induce A2 domain unfolding is inversely proportional to multimer length. By examining data for the duration and location of significant force excursions, convincing evidence is advanced that unfolding of A2 domains, and therefore scission of vWF multimers by the size-regulating blood enzyme ADAMTS13, happen preferentially near the center of unraveled multimers.

scholarly journals Internal Tensile Force and A2 Domain Unfolding of von Willebrand Factor Multimers in Shear Flow

2018 ◽  
Vol 115 (10) ◽  
pp. 1860-1871 ◽  
Author(s):  
Michael Morabito ◽  
Chuqiao Dong ◽  
Wei Wei ◽  
Xuanhong Cheng ◽  
Xiaohui F. Zhang ◽  
...  
Keyword(s):  
Shear Flow ◽  
Von Willebrand Factor ◽  
Tensile Force ◽  
Von Willebrand ◽  
A2 Domain ◽  
Willebrand Factor

Platelet-VWF complexes get the chop

Blood ◽  
2008 ◽  
Vol 111 (2) ◽  
pp. 475-475
Author(s):  
Michael C. Berndt ◽  
Robert K. Andrews
Keyword(s):  
Ligand Binding ◽  
Von Willebrand Factor ◽  
Tensile Force ◽  
Inhibitory Effect ◽  
Platelet Glycoprotein ◽  
A1 Domain ◽  
Von Willebrand ◽  
A2 Domain ◽  
Willebrand Factor ◽  
Binding Subunit

In this issue of Blood, Shim and colleagues define a dual role for platelet glycoprotein (GP)Ibα (the major ligand-binding subunit of the GPIb-IX-V complex) in regulating ADAMTS13-mediated cleavage of von Willebrand factor (VWF) under shear: it alleviates an inhibitory effect of the VWF A1 domain on cleavage of the A2 domain,1 and it allows tensile force to be exerted on the A2 domain through at least 2 platelets binding per VWF multimer via the A1 domain (see figure).

scholarly journals Exposure of Von Willebrand Factor Cleavage Site in A1A2A3-Fragment under Extreme Hydrodynamic Shear

Polymers ◽  
2021 ◽  
Vol 13 (22) ◽  
pp. 3912
Author(s):  
Olivier Languin-Cattöen ◽  
Emeline Laborie ◽  
Daria O. Yurkova ◽  
Simone Melchionna ◽  
Philippe Derreumaux ◽  
...  
Keyword(s):  
Shear Flow ◽  
Von Willebrand Factor ◽  
Cleavage Site ◽  
Coarse Grained ◽  
Complex Behaviour ◽  
Multi Scale ◽  
Rotational Components ◽  
Von Willebrand ◽  
A2 Domain ◽  
Willebrand Factor

Von Willebrand Factor (vWf) is a giant multimeric extracellular blood plasma involved in hemostasis. In this work we present multi-scale simulations of its three-domains fragment A1A2A3. These three domains are essential for the functional regulation of vWf. Namely the A2 domain hosts the site where the protease ADAMTS13 cleavages the multimeric vWf allowing for its length control that prevents thrombotic conditions. The exposure of the cleavage site follows the elongation/unfolding of the domain that is caused by an increased shear stress in blood. By deploying Lattice Boltzmann molecular dynamics simulations based on the OPEP coarse-grained model for proteins, we investigated at molecular level the unfolding of the A2 domain under the action of a perturbing shear flow. We described the structural steps of this unfolding that mainly concerns the β-strand structures of the domain, and we compared the process occurring under shear with that produced by the action of a directional pulling force, a typical condition of single molecule experiments. We observe, that under the action of shear flow, the competition among the elongational and rotational components of the fluid field leads to a complex behaviour of the domain, where elongated structures can be followed by partially collapsed melted globule structures with a very different degree of exposure of the cleavage site. Our simulations pose the base for the development of a multi-scale in-silico description of vWf dynamics and functionality in physiological conditions, including high resolution details for molecular relevant events, e.g., the binding to platelets and collagen during coagulation or thrombosis.

scholarly journals Unfolding, refolding and proteolysis of the von Willebrand Factor A2 domain under tensile force

2009 ◽  
Vol 96 (3) ◽  
pp. 37a
Author(s):  
Xiaohui Zhang ◽  
Kenneth Halvorsen ◽  
Wesley P. Wong ◽  
Timothy A. Springer
Keyword(s):  
Von Willebrand Factor ◽  
Tensile Force ◽  
Von Willebrand ◽  
A2 Domain ◽  
Willebrand Factor

Factor VIII Inhibitor Antibodies with C2 Domain Specificity Are Less inhibitory to Factor VIII Complexed with von Willebrand Factor

1996 ◽  
Vol 76 (05) ◽  
pp. 749-754 ◽  
Author(s):  
Suzuki Suzuki ◽  
Morio Arai ◽  
Kagehiro Amano ◽  
Kazuhiko Kagawa ◽  
Katsuyuki Fukutake
Keyword(s):  
Complex Formation ◽  
Factor Viii ◽  
Von Willebrand Factor ◽  
Domain Specificity ◽  
Factor Viii Inhibitor ◽  
C2 Domain ◽  
Recombinant Fviii ◽  
Von Willebrand ◽  
A2 Domain ◽  
Willebrand Factor

SummaryIn order to clarify the potential role of von Willebrand factor (vWf) in attenuating the inactivation of factor VIII (fVIII) by those antibodies with C2 domain specificity, we investigated a panel of 14 human antibodies to fVIII. Immunoblotting analysis localized light chain (C2 domain) epitopes for four cases, heavy chain (A2 domain) epitopes in five cases, while the remaining five cases were both light and heavy chains. The inhibitor titer was considerably higher for Kogenate, a recombinant fVIII concentrate, than for Haemate P, a fVIII/vWf complex concentrate, in all inhibitor plasmas that had C2 domain specificity. In five inhibitor plasmas with A2 domain specificity and in five with both A2 and C2 domain specificities, Kogenate gave titers similar to or lower than those with Haemate P. The inhibitory effect of IgG of each inhibitor plasma was then compared with recombinant fVIII and its complex with vWf. When compared to the other 10 inhibitor IgGs, IgG concentration, which inhibited 50% of fVIII activity (IC50), was remarkably higher for the fVIII/vWf complex than for fVIII in all the inhibitor IgGs that had C2 domain reactivity. Competition of inhibitor IgG and vWf for fVIII binding was observed in an ELISA system. In 10 inhibitors that had C2 domain reactivity, the dose dependent inhibition of fVIII-vWf complex formation was observed, while, in the group of inhibitors with A2 domain specificity, there was no inhibition of the complex formation except one case. We conclude that a subset of fVIII inhibitors, those that bind to C2 domain determinants, are less inhibitory to fVIII when it is complexed with vWf that binds to overlapping region in the C2 domain.

scholarly journals Long-ranged Protein-glycan Interactions Stabilize von Willebrand Factor A2 Domain from Mechanical Unfolding

2018 ◽  
Vol 8 (1) ◽  
Author(s):  
Chuqiao Dong ◽  
Jumin Lee ◽  
Seonghoon Kim ◽  
Whitney Lai ◽  
Edmund B. Webb ◽  
...  
Keyword(s):  
Von Willebrand Factor ◽  
Von Willebrand ◽  
A2 Domain ◽  
Willebrand Factor

scholarly journals Platelet von Willebrand factor: evidence for its involvement in platelet adhesion to collagen

Blood ◽  
1987 ◽  
Vol 70 (4) ◽  
pp. 1214-1217
Author(s):  
E Fressinaud ◽  
D Baruch ◽  
C Rothschild ◽  
HR Baumgartner ◽  
D Meyer
Keyword(s):  
Shear Rate ◽  
Von Willebrand Factor ◽  
Platelet Adhesion ◽  
Von Willebrand Disease ◽  
High Shear ◽  
Shear Rates ◽  
High Shear Rates ◽  
Von Willebrand ◽  
Willebrand Factor

Although it is well established that plasma von Willebrand Factor (vWF) is essential to platelet adhesion to subendothelium at high shear rates, the role of platelet vWF is less clear. We studied the respective role of both plasma and platelet vWF in mediating platelet adhesion to fibrillar collagen in a parallel-plate perfusion chamber. Reconstituted blood containing RBCs, various mixtures of labeled washed platelets and plasma from controls or five patients with severe von Willebrand disease (vWD), was perfused through the chamber for five minutes at a shear rate of 1,600 s-1. Platelet-collagen interactions were estimated by counting the radioactivity in deposited platelets and by quantitative morphometry. When the perfusate consisted of normal platelets suspended in normal plasma, platelet deposition on the collagen was 24.7 +/- 3.6 X 10(6)/cm2 (mean +/- SEM, n = 6). Significantly less deposition (16 +/- 2.3) was observed when vWD platelets were substituted for normal platelets. In mixtures containing vWD plasma, significantly greater deposition (9 +/- 2.2) was obtained with normal than with vWD platelets (1 +/- 0.4) demonstrating a role for platelet vWF in mediating the deposition of platelets on collagen. Morphometric analysis confirmed these data. Our findings indicate that platelet, as well as plasma, vWF mediates platelet-collagen interactions at a high shear rate.

Single-molecule imaging of von Willebrand factor reveals tension-dependent self-association

Blood ◽  
2021 ◽  
Vol 138 (23) ◽  
pp. 2425-2434
Author(s):  
Hongxia Fu ◽  
Yan Jiang ◽  
Wesley P. Wong ◽  
Timothy A. Springer
Keyword(s):  
Von Willebrand Factor ◽  
Single Molecule ◽  
Molecular Mechanisms ◽  
Tensile Force ◽  
Sharp Decrease ◽  
Hydrodynamic Drag ◽  
High Tension ◽  
Self Association ◽  
Von Willebrand ◽  
Willebrand Factor

Abstract von Willebrand factor (VWF) is an ultralong concatemeric protein important in hemostasis and thrombosis. VWF molecules can associate with other VWF molecules, but little is known about the mechanism. Hydrodynamic drag exerts tensile force on surface-tethered VWF that extends it and is maximal at the tether point and declines linearly to 0 at the downstream free end. Using single-molecule fluorescence microscopy, we directly visualized the kinetics of binding of free VWF in flow to surface-tethered single VWF molecules. We showed that self-association requires elongation of tethered VWF and that association increases with tension in tethered VWF, reaches half maximum at a characteristic tension of ∼10 pN, and plateaus above ∼25 pN. Association is reversible and hence noncovalent; a sharp decrease in shear flow results in rapid dissociation of bound VWF. Tethered primary VWF molecules can recruit more than their own mass of secondary VWF molecules from the flow stream. Kinetics show that instead of accelerating, the rate of accumulation decreases with time, revealing an inherently self-limiting self-association mechanism. We propose that this may occur because multiple tether points between secondary and primary VWF result in lower tension on the secondary VWF, which shields more highly tensioned primary VWF from further association. Glycoprotein Ibα (GPIbα) binding and VWF self-association occur in the same region of high tension in tethered VWF concatemers; however, the half-maximal tension required for activation of GPIbα is higher, suggesting differences in molecular mechanisms. These results have important implications for the mechanism of platelet plug formation in hemostasis and thrombosis.

scholarly journals Role of plasma viscosity in platelet adhesion

Blood ◽  
1992 ◽  
Vol 80 (4) ◽  
pp. 953-959 ◽  
Author(s):  
HF van Breugel ◽  
PG de Groot ◽  
RM Heethaar ◽  
JJ Sixma
Keyword(s):  
Endothelial Cell ◽  
Shear Rate ◽  
Von Willebrand Factor ◽  
Platelet Adhesion ◽  
Human Albumin ◽  
Plasma Viscosity ◽  
Cell Matrix ◽  
Von Willebrand ◽  
Willebrand Factor ◽  
Medium Viscosity

Abstract Platelet adhesion to the vessel wall is initiated by transport of blood platelets from the bulk flow to the wall. The process of diffusion and convection of the platelets is affected by rheological conditions such as well shear rate, red blood cell (RBC) deformability, and viscosity of the medium. To study the effect of plasma viscosity on platelet adhesion, perfusion experiments with a rectangular perfusion chamber were performed. Reconstituted blood, consisting of washed platelets and washed RBCs, was circulated through this chamber for 5 minutes at a wall shear rate of 300 s-1. Different albumin concentrations were made, to obtain different medium viscosities (0.89 to 1.85 mPa.s). Platelet adhesion decreased with increasing medium viscosity up to viscosities of 0.95 mPa.s, but increased with medium viscosity above this value. Instead of human albumin solution, different plasma viscosities were obtained by dilution of Waldenstrom plasma with buffer. Plasma was depleted of fibronectin, which gave a final plasma viscosity of 2.0 mPa.s, and was dialyzed against HEPES buffer and subsequently diluted with the dialysis buffer in different fractions (0.89 to 2.00 mPa.s). Perfusions were performed over a purified von Willebrand factor coating on glass, or over an endothelial cell matrix, preincubated with von Willebrand factor. With both surfaces, platelet adhesion was dependent on the plasma viscosity in a similar way: at low plasma viscosities, adhesion was decreased with increasing plasma viscosity, while at higher plasma viscosities, adhesion increased with plasma viscosity. Adhesion values at higher plasma viscosity or at higher human albumin concentrations could be explained by effects of the medium on the rigidity of the RBCs, since platelet adhesion is known to be increased by enhanced RBC rigidity. Effects of the medium on the deformability of the RBCs were measured separately with the laser diffraction method. These experiments confirmed that presence of human albumin or plasma in the measuring suspension increased the rigidity of RBCs. To prevent influence of the medium on the RBCs in perfusion experiments, the RBCs were fixated with glutaraldehyde. Perfusion experiments with fixated RBCs in plasma over a von Willebrand factor preincubated endothelial cell matrix, showed a consequent decrease in adhesion with increasing plasma viscosity, according to the diffusion theories, whereas the increase of adhesion at high plasma viscosities was lacking. This suggests that the latter effect was entirely due to increased transport of platelets by more rigid RBCs.

scholarly journals von Willebrand factor self-association is regulated by the shear-dependent unfolding of the A2 domain

2019 ◽  
Vol 3 (7) ◽  
pp. 957-968 ◽  
Author(s):  
Changjie Zhang ◽  
Anju Kelkar ◽  
Sriram Neelamegham
Keyword(s):  
Von Willebrand Factor ◽  
Ex Vivo ◽  
Association Studies ◽  
Apolipoprotein A1 ◽  
Platelet Glycoprotein ◽  
Functional Domain ◽  
Self Association ◽  
Von Willebrand ◽  
A2 Domain ◽  
Willebrand Factor

Abstract von Willebrand factor (VWF) self-association results in the homotypic binding of VWF upon exposure to fluid shear. The molecular mechanism of this process is not established. In this study, we demonstrate that the shear-dependent unfolding of the VWF A2 domain in the multimeric protein is a major regulator of protein self-association. This mechanism controls self-association on the platelet glycoprotein Ibα receptor, on collagen substrates, and during thrombus growth ex vivo. In support of this, A2-domain mutations that prevent domain unfolding due to disulfide bridging of N- and C-terminal residues (“Lock-VWF”) reduce self-association and platelet activation under various experimental conditions. In contrast, reducing assay calcium concentrations, and 2 mutations that destabilize VWF-A2 conformation by preventing coordination with calcium (D1498A and R1597W VWD type 2A mutation), enhance self-association. Studies using a panel of recombinant proteins that lack the A1 domain (“ΔA1 proteins”) suggest that besides pure homotypic A2 interactions, VWF-A2 may also engage other protein domains to control self-association. Addition of purified high-density lipoprotein and apolipoprotein-A1 partially blocked VWF self-association. Overall, similar conditions facilitate VWF self-association and ADAMTS13-mediated proteolysis, with low calcium and A2 disease mutations enhancing both processes, and locking-A2 blocking them simultaneously. Thus, VWF appears to have evolved 2 balancing molecular functions in a single A2 functional domain to dynamically regulate protein size in circulation: ADAMTS13-mediated proteolysis and VWF self-association. Modulating self-association rates by targeting VWF-A2 may provide novel methods to regulate the rates of thrombosis and hemostasis.

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