von Willebrand factor C1C2 domain is involved in platelet adhesion to polymerized fibrin at high shear rate.
Fibrin is actively involved in platelet reactions essential for thrombus growth, in which von Willebrand factor (VWF) might be an important mediator. The aim of this study was to localize VWF domains that bind to fibrin and to determine their relevance in platelet adhesion. VWF binds specifically to fibrin with an apparent Kd of 2.2 microg/mL. Competition in the presence of 2 complementary fragments, SpIII (residues 1-1365) and SpII (residues 1366-2050), indicated that the high affinity binding site for fibrin is located in the C-terminal part, thus distinct from the A domains. Comparison of 2 deleted rVWF (DeltaD4B-rVWF, DeltaC1C2-rVWF) suggested that the C1C2 domains contained a fibrin binding site. This site is distinct from RGD, as shown by binding of D1746G-rVWF to fibrin. Perfusion studies at high shear rate demonstrated that C1C2 domains were required for optimal platelet adhesion to fibrin. With the use of a VWF-deficient mouse model, it was found that plasma VWF is critical for platelet tethering and adhesion to fibrin. These results suggest a dual role of fibrin-bound VWF in thrombus formation: first, fibrin-bound VWF is critical in the recruitment of platelets by way of glycoprotein (GP) Ib, and, second, it contributes to stationary platelet adhesion by way of binding to activated alphaIIbbeta3.
Keuren
Jeffrey F W
JF
Department of Biochemistry, Cardiovascular Research Institute, Maastricht University, Maastricht, The Netherlands.
Baruch
Dominique
D
Legendre
Paulette
P
Denis
Cécile V
CV
Lenting
Peter J
PJ
Girma
Jean-Pierre
JP
Lindhout
Theo
T
D000818:Animals; D001665:Binding Sites; D001667:Binding, Competitive; D002448:Cell Adhesion; D004305:Dose-Response Relationship, Drug; D004591:Electrophoresis, Polyacrylamide Gel; D005337:Fibrin / Q000737:chemistry*; D006801:Humans; D007700:Kinetics; D051379:Mice; D008810:Mice, Inbred C57BL; D010973:Platelet Adhesiveness; D010974:Platelet Aggregation; D019039:Platelet Glycoprotein GPIIb-IIIa Complex / Q000378:metabolism; D019038:Platelet Glycoprotein GPIb-IX Complex / Q000737:chemistry; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D013314:Stress, Mechanical; D013997:Time Factors; D014841:von Willebrand Factor / Q000737:chemistry*
D019039:Platelet Glycoprotein GPIIb-IIIa Complex; D019038:Platelet Glycoprotein GPIb-IX Complex; D014841:von Willebrand Factor; D005337:Fibrin