Von Willebrand factor (VWF) synthesized in endothelial cells and megkaryocytes is a multimeric glycoprotein that mediates initial platelet tethering to subendothelium exposed at the sites of vessel injury. Upon stimulation, endothelial cells release ultra-large (UL) forms of VWF multimers that are hyperactive and prothrombotic. Upon secretion, ULVWF is rapidly cleaved by ADAMTS-13 to smaller multimers that are hemostatically active, but no longer prothrombotic. The circulating plasma VWF (pVWF) multimers, therefore, bind platelets only after activation by high shear stress or modulators. However, whether ULVWF structurally differs from pVWF remains debatable. It is also unclear as how shear stress activates pVWF. We hypothesize that 1) ULVWF differs from pVWF in their thiol-disulfide states with regards to specific cysteine residues in the C-domain;2) shear stress activates pVWF by inducing a thiol-disulfide exchange to facilitate covalent lateral association and to form fibrillar structures;and 3) ADAMTS-13 acts as a reductase to prevent this thiol-disulfide exchange, thus VWF activation. These hypotheses are supported by our preliminary data. We will test the hypotheses through two specific aims.
Aim 1 is to define the mechanism of VWF activation by thiol-disulfide exchange by several technical means. We will identify specific cysteine residues critical for the shear-induced activation of pVWF, determine whether shear stress induces the covalent lateral association of pVWF multimers as a means of activation, and detect the unfolding of VWF domains by physical forces and strength of pVWF bonds with GP Ib? before and after shear exposure.
Aim 2 is to define the reductase activity of ADAMTS-13 observed in our preliminary study by studying the key aspects of this activity. We will map the region(s) and specific cysteine residues involved in this reductase activity, directly measure the reduction of (UL)VWF by ADAMTS-13 under static and flow conditions, and identify cysteine residues in the pVWF C domain that are the substrate for the reductase activity. Finally, we will investigate how this reductase activity regulates the rate of VWF domain unfolding. Information generated through these experiments is critical to dissect the mechanisms of shear-induced VWF activation and to characterize this new ADAMTS-13 activity. Knowledge gained through the studies will help us to identify new strategies to regulate VWF's roles in hemostasis and thrombosis.

Public Health Relevance

This project is to test the hypotheses that ULVWF differs from plasma VWF in its thiol- disulfide states that can be changed by fluid shear stress and ADAMTS-13 functions as a reductase to inhibit the thiol-disulfide exchange and prevent shear-induced VWF activation. Results will help us to dissect this novel mechanism of shear-induced VWF activation. New information will be critical for development new strategies to regulate the role of VWF in hemostasis and thrombosis.

National Institute of Health (NIH)
National Heart, Lung, and Blood Institute (NHLBI)
Research Project (R01)
Project #
Application #
Study Section
Special Emphasis Panel (ZRG1-HEME-C (02))
Program Officer
Kindzelski, Andrei L
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
Puget Sound Blood Center
United States
Zip Code
Nascimbene, Angelo; Neelamegham, Sriram; Frazier, O H et al. (2016) Acquired von Willebrand syndrome associated with left ventricular assist device. Blood 127:3133-41
Zhao, Zilong; Wang, Min; Tian, Ye et al. (2016) Cardiolipin-mediated procoagulant activity of mitochondria contributes to traumatic brain injury-associated coagulopathy in mice. Blood 127:2763-72
Song, Jaewoo; Xue, Cheng; Preisser, John S et al. (2016) Association of Single Nucleotide Polymorphisms in the ST3GAL4 Gene with VWF Antigen and Factor VIII Activity. PLoS One 11:e0160757
Zhang, Li-han; Yang, Ai-jun; Wang, Min et al. (2016) Enhanced autophagy reveals vulnerability of P-gp mediated epirubicin resistance in triple negative breast cancer cells. Apoptosis 21:473-88
Liu, Xiao; Li, Ying; Zhu, Hui et al. (2015) Use of non-contact hopping probe ion conductance microscopy to investigate dynamic morphology of live platelets. Platelets 26:480-5
Tian, Ye; Salsbery, Breia; Wang, Min et al. (2015) Brain-derived microparticles induce systemic coagulation in a murine model of traumatic brain injury. Blood 125:2151-9
Yuan, Hengjie; Houck, Katie L; Tian, Ye et al. (2015) Piperlongumine Blocks JAK2-STAT3 to Inhibit Collagen-Induced Platelet Reactivity Independent of Reactive Oxygen Species. PLoS One 10:e0143964
Wang, Rui; Stone, Rebecca L; Kaelber, Jason T et al. (2015) Electron cryotomography reveals ultrastructure alterations in platelets from patients with ovarian cancer. Proc Natl Acad Sci U S A 112:14266-71
Song, Jaewoo; Chen, Fengju; Campos, Marco et al. (2015) Quantitative Influence of ABO Blood Groups on Factor VIII and Its Ratio to von Willebrand Factor, Novel Observations from an ARIC Study of 11,673 Subjects. PLoS One 10:e0132626
Nascimbene, Angelo; Hernandez, Ruben; George, Joggy K et al. (2014) Association between cell-derived microparticles and adverse events in patients with nonpulsatile left ventricular assist devices. J Heart Lung Transplant 33:470-7

Showing the most recent 10 out of 52 publications