# Mechanoregulatory mechanisms of von Willebrand disease and thrombosis

> **NIH NIH K25** · UNIVERSITY OF WASHINGTON · 2021 · $178,092

## Abstract

PROJECT SUMMARY
A critical initiating step in hemostasis and thrombosis is adhesion of platelet membrane receptor
glycoprotein Ibα (GPIbα) to von Willebrand factor (VWF), a large, multidomain, polymeric blood
glycoprotein. The precise mechanisms whereby VWF promotes platelet GPIbα adhesion to its A1 domain
only during hemostasis or thrombosis, but not in normal circulation, are not yet clear. Understanding these
mechanisms is essential for developing more effective diagnostics and therapeutics for vascular thrombosis
and the most common hereditary bleeding disorder, von Willebrand disease (VWD). The applicant, Dr.
Hongxia Fu, will develop innovative single-molecule approaches to study full-length VWF concatemers
hemostatic function in the laboratory of the mentor, Dr. Timothy Springer. This system can be utilized to
monitor both intramolecular VWF conformational transitions and GPIbα binding simultaneously by
combining rapid air pressure-actuated shear flow with total internal fluorescence microscopy (TIRF).
Utilizing this system, Dr. Fu will test the hypothesis that hydrodynamic flow directly induces a conformational
transition in VWF concatemers from a compact to an elongated form, thereby exposing high-affinity, force-
dependent binding sites to recruit both GPIbα (platelet adhesion) and additional VWF molecules (VWF self-
association). To expand this system to include complex features of physiological and pathophysiological
blood flow, she will furthermore develop a new fluorescence-based assay for VWF function in bulk solutions
and its expression in Weibel-Palade bodies inside endothelial cells with or without VWD-relevant mutations.
This work will provide direct insight into the regulatory mechanisms governing primary hemostasis,
thrombosis, and bleeding disorder, establishing a paradigm for mechanosensory control of receptor-ligand
binding affinity. It also will provide Dr. Fu with additional training in cell biology, genome editing, stem cells,
and biomedicine, complementing her expertise in quantitative sciences. Dr. Fu will devote 100 % of her time
to research under the direct mentorship of Dr. Springer. Dr. Fu's research program will establish new
quantitative assays for VWF function and VWF-related diseases, from the single molecule to the cellular
scale, providing a firm foundation for continued research in this area and career development to the
independent investigator stage in biomedicine.

## Key facts

- **NIH application ID:** 10164845
- **Project number:** 5K25HL135432-05
- **Recipient organization:** UNIVERSITY OF WASHINGTON
- **Principal Investigator:** Hongxia Fu
- **Activity code:** K25 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $178,092
- **Award type:** 5
- **Project period:** 2017-09-01 → 2023-05-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10164845

## Citation

> US National Institutes of Health, RePORTER application 10164845, Mechanoregulatory mechanisms of von Willebrand disease and thrombosis (5K25HL135432-05). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10164845. Licensed CC0.

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