Analysis of the role of von Willebrand factor, platelet glycoprotein VI-, and α2β1-mediated collagen binding in thrombus formation.

Abstract

Rare missense mutations in the von Willebrand factor (VWF) A3 domain that disrupt collagen binding have been found in patients with a mild bleeding phenotype. However, the analysis of these aberrant VWF-collagen interactions has been limited. Here, we have developed mouse models of collagen-binding mutants and analyzed the function of the A3 domain using comprehensive in vitro and in vivo approaches. Five loss-of-function (p.S1731T, p.W1745C, p.S1783A, p.H1786D, A3 deletion) and 1 gain-of-function (p.L1757A) variants were generated in the mouse VWF complementary DNA. The results of these various assays were consistent, although the magnitude of the effects were different: the gain-of-function (p.L1757A) variant showed consistent enhanced collagen binding whereas the loss-of-function mutants showed variable degrees of functional deficit. We further analyzed the impact of direct platelet-collagen binding by blocking glycoprotein VI (GPVI) and integrin α2β1 in our ferric chloride murine thrombosis model. The inhibition of GPVI demonstrated a comparable functional defect in thrombosis formation to the VWF(-/-) mice whereas α2β1 inhibition demonstrated a milder bleeding phenotype. Furthermore, a delayed and markedly reduced thrombogenic response was still evident in VWF(-/-), GPVI, and α2β1 blocked animals, suggesting that alternative primary hemostatic mechanisms can partially rescue the bleeding phenotype associated with these defects.

• Authors: Yasuaki Shida, Natalia Rydz, David Stegner, Christine Brown, Jeffrey Mewburn, Kate Sponagle, Ozge Danisment, Bredon Crawford, Barbara Vidal, Carol A Hegadorn, Cynthia M Pruss, Bernhard Nieswandt, David Lillicrap
• Journal: Blood (Blood) Vol. 124 Issue 11 Pg. 1799-807 (Sep 11 2014) ISSN: 1528-0020 [Electronic] United States
• PMID: 25051961 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't)
• Copyright: © 2014 by The American Society of Hematology.

Chemical References

• Chlorides
• Ferric Compounds
• Integrin alpha2beta1
• Noxae
• Platelet Membrane Glycoproteins
• platelet membrane glycoprotein VI
• von Willebrand Factor
• Collagen
• ferric chloride

Topics

• Amino Acid Substitution
• Animals
• Chlorides (adverse effects, pharmacology)
• Collagen (genetics, metabolism)
• Disease Models, Animal
• Ferric Compounds (adverse effects, pharmacology)
• HEK293 Cells
• Humans
• Integrin alpha2beta1 (genetics, metabolism)
• Mice
• Mice, Knockout
• Mutation, Missense
• Noxae (adverse effects, pharmacology)
• Platelet Membrane Glycoproteins (genetics, metabolism)
• Protein Structure, Tertiary
• Thrombosis (chemically induced, genetics, metabolism, pathology)
• von Willebrand Factor (genetics, metabolism)