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Conformation of von Willebrand factor in shear flow revealed with stroboscopic single-molecule imaging
von Willebrand factor (VWF) is a multimeric blood protein that acts as a mechanical probe, responding to changes in flow to initiate platelet plug formation. Previously, our laboratory tests had shown that using single-molecule imaging that shear stress can extend surface-tethered VWF, but paradoxic...
Autores principales: | , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
The American Society of Hematology
2022
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9837445/ https://www.ncbi.nlm.nih.gov/pubmed/36040485 http://dx.doi.org/10.1182/blood.2022016969 |
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author | Bergal, Hans T. Jiang, Yan Yang, Darren Springer, Timothy A. Wong, Wesley P. |
author_facet | Bergal, Hans T. Jiang, Yan Yang, Darren Springer, Timothy A. Wong, Wesley P. |
author_sort | Bergal, Hans T. |
collection | PubMed |
description | von Willebrand factor (VWF) is a multimeric blood protein that acts as a mechanical probe, responding to changes in flow to initiate platelet plug formation. Previously, our laboratory tests had shown that using single-molecule imaging that shear stress can extend surface-tethered VWF, but paradoxically, we found that the required shear stress was higher than reported for free-in-flow VWF, an observation inconsistent with basic physical principles. To resolve this inconsistency critical to VWF’s molecular mechanism, we measured free-VWF extension in shear flow using pulsed laser stroboscopic imaging of single molecules. Here, laser pulses of different durations are used to capture multiple images of the same molecule within each frame, enabling accurate length measurements in the presence of motion blur. At high shear stresses, we observed a mean shift in VWF extension of <200 nm, much shorter than the multiple-micron extensions previously reported with no evidence for the predicted sharp globule-stretch conformational transition. Modeling VWF with a Brownian dynamics simulation, our results were consistent with VWF behaving as an uncollapsed polymer rather than the theorized compact ball. The muted response of free VWF to high shear rates implies that the tension experienced by free VWF in physiological shear flow is lower than indicated by previous reports and that tethering to platelets or the vessel wall is required to mechanically activate VWF adhesive function for primary hemostasis. |
format | Online Article Text |
id | pubmed-9837445 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2022 |
publisher | The American Society of Hematology |
record_format | MEDLINE/PubMed |
spelling | pubmed-98374452023-01-18 Conformation of von Willebrand factor in shear flow revealed with stroboscopic single-molecule imaging Bergal, Hans T. Jiang, Yan Yang, Darren Springer, Timothy A. Wong, Wesley P. Blood Regular Article von Willebrand factor (VWF) is a multimeric blood protein that acts as a mechanical probe, responding to changes in flow to initiate platelet plug formation. Previously, our laboratory tests had shown that using single-molecule imaging that shear stress can extend surface-tethered VWF, but paradoxically, we found that the required shear stress was higher than reported for free-in-flow VWF, an observation inconsistent with basic physical principles. To resolve this inconsistency critical to VWF’s molecular mechanism, we measured free-VWF extension in shear flow using pulsed laser stroboscopic imaging of single molecules. Here, laser pulses of different durations are used to capture multiple images of the same molecule within each frame, enabling accurate length measurements in the presence of motion blur. At high shear stresses, we observed a mean shift in VWF extension of <200 nm, much shorter than the multiple-micron extensions previously reported with no evidence for the predicted sharp globule-stretch conformational transition. Modeling VWF with a Brownian dynamics simulation, our results were consistent with VWF behaving as an uncollapsed polymer rather than the theorized compact ball. The muted response of free VWF to high shear rates implies that the tension experienced by free VWF in physiological shear flow is lower than indicated by previous reports and that tethering to platelets or the vessel wall is required to mechanically activate VWF adhesive function for primary hemostasis. The American Society of Hematology 2022-12-08 2022-09-02 /pmc/articles/PMC9837445/ /pubmed/36040485 http://dx.doi.org/10.1182/blood.2022016969 Text en © 2022 by The American Society of Hematology. Licensed under Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0), permitting only noncommercial, nonderivative use with attribution. All other rights reserved. https://creativecommons.org/licenses/by-nc-nd/4.0/This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). |
spellingShingle | Regular Article Bergal, Hans T. Jiang, Yan Yang, Darren Springer, Timothy A. Wong, Wesley P. Conformation of von Willebrand factor in shear flow revealed with stroboscopic single-molecule imaging |
title | Conformation of von Willebrand factor in shear flow revealed with stroboscopic single-molecule imaging |
title_full | Conformation of von Willebrand factor in shear flow revealed with stroboscopic single-molecule imaging |
title_fullStr | Conformation of von Willebrand factor in shear flow revealed with stroboscopic single-molecule imaging |
title_full_unstemmed | Conformation of von Willebrand factor in shear flow revealed with stroboscopic single-molecule imaging |
title_short | Conformation of von Willebrand factor in shear flow revealed with stroboscopic single-molecule imaging |
title_sort | conformation of von willebrand factor in shear flow revealed with stroboscopic single-molecule imaging |
topic | Regular Article |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9837445/ https://www.ncbi.nlm.nih.gov/pubmed/36040485 http://dx.doi.org/10.1182/blood.2022016969 |
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