scholarly journals Fibrin monomer induces binding of endogenous platelet von Willebrand factor to the glycocalicin portion of platelet glycoprotein IB

Blood ◽  
1987 ◽  
Vol 70 (5) ◽  
pp. 1589-1594
Author(s):  
RI Parker ◽  
HR Gralnick
Keyword(s):  
Von Willebrand Factor ◽  
Polyclonal Antibodies ◽  
Platelet Glycoprotein ◽  
Glycoprotein Ib ◽  
Human Fibrinogen ◽  
Activated Platelets ◽  
Fibrin Monomer ◽  
Low Concentrations ◽  
Von Willebrand ◽  
Willebrand Factor

This study demonstrates that when platelets are stimulated by thrombin in the presence of low concentrations of purified human fibrinogen (10 to 20 micrograms/mL, final concentration) binding of released platelet von Willebrand factor (plt-vWF) to the platelet membrane is enhanced. This effect appears to be mediated by fibrin monomer produced by the action of thrombin on the fibrinogen in the incubation suspension. When fibrin polymerization is inhibited, the binding of released plt-vWF to the platelets is markedly increased. This enhanced binding is dependent on platelet glycoprotein Ib (GPIb) as shown by a decreased response with Bernard-Soulier platelets and inhibition by both monoclonal and polyclonal antibodies against glycocalicin. The binding of fibrin to thrombin-activated platelets preincubated with monoclonal antibody against GPIIb/IIIa is increased when the predominant form of fibrin is fibrin monomer. The fibrin binding is also decreased in the presence of antibody against glycocalicin. Our data demonstrate that fibrin monomer facilitates plt-vWF binding to the glycocalicin portion of platelet GPIb on thrombin-stimulated platelets and that binding of fibrin monomer to glycocalicin is necessary for this response to occur.

scholarly journals Fibrin monomer induces binding of endogenous platelet von Willebrand factor to the glycocalicin portion of platelet glycoprotein IB

Blood ◽  
1987 ◽  
Vol 70 (5) ◽  
pp. 1589-1594 ◽  
Author(s):  
RI Parker ◽  
HR Gralnick
Keyword(s):  
Von Willebrand Factor ◽  
Polyclonal Antibodies ◽  
Platelet Glycoprotein ◽  
Glycoprotein Ib ◽  
Human Fibrinogen ◽  
Activated Platelets ◽  
Fibrin Monomer ◽  
Low Concentrations ◽  
Von Willebrand ◽  
Willebrand Factor

Abstract This study demonstrates that when platelets are stimulated by thrombin in the presence of low concentrations of purified human fibrinogen (10 to 20 micrograms/mL, final concentration) binding of released platelet von Willebrand factor (plt-vWF) to the platelet membrane is enhanced. This effect appears to be mediated by fibrin monomer produced by the action of thrombin on the fibrinogen in the incubation suspension. When fibrin polymerization is inhibited, the binding of released plt-vWF to the platelets is markedly increased. This enhanced binding is dependent on platelet glycoprotein Ib (GPIb) as shown by a decreased response with Bernard-Soulier platelets and inhibition by both monoclonal and polyclonal antibodies against glycocalicin. The binding of fibrin to thrombin-activated platelets preincubated with monoclonal antibody against GPIIb/IIIa is increased when the predominant form of fibrin is fibrin monomer. The fibrin binding is also decreased in the presence of antibody against glycocalicin. Our data demonstrate that fibrin monomer facilitates plt-vWF binding to the glycocalicin portion of platelet GPIb on thrombin-stimulated platelets and that binding of fibrin monomer to glycocalicin is necessary for this response to occur.

Glycoprotein Ib Can Mediate Endothelial Cell Attachment to a von Willebrand Factor Substratum

1995 ◽  
Vol 73 (02) ◽  
pp. 309-317 ◽  
Author(s):  
Dorothy A Beacham ◽  
Miguel A Cruz ◽  
Robert I Handin
Keyword(s):  
Endothelial Cell ◽  
Von Willebrand Factor ◽  
Cell Attachment ◽  
Umbilical Vein ◽  
Single Amino Acid ◽  
Cell Surface Expression ◽  
Platelet Glycoprotein ◽  
Glycoprotein Ib ◽  
Von Willebrand ◽  
Willebrand Factor

SummaryIntroduction of single amino acid substitutions into the C-terminal Arg-Gly-Asp-Ser (RGDS) site of von Willebrand Factor, referred to as RGD mutant vWF, selectively abrogated vWF binding to platelet glycoprotein IIb/IIIa (GpIIb/IIIa, αIIbβ3 and abolished human umbilical vein endothelial cell (HUVEC) spreading, but not attachment, to RGD mutant vWF (Beacham, D. A., Wise, R. J., Turci, S. M. and Handin, R. I. 1992. J. Biol. Chem. 167, 3409-3415). These results suggested that in addition to the vitronectin receptor (VNR, αvβ3), a second endothelial membrane glycoprotein can mediate HUVEC adhesion to vWF. HUVEC attachment to wild-type (WT) and RGD-mutant vWF was reduced by two proteins known to block the vWF-platelet glycoprotein Ib/IX (GpIb/IX) interaction, the monoclonal antibody AS-7 and the recombinant polypeptide, vWF-A1. The addition of cytochalasin B or DNase I to disrupt potential GPIbα-cytoskeletal interactions enhanced the immunoprecipitation of endothelial GPIbα, caused HUVEC to round up, and increased HUVEC adhesion to RGD mutant vWF. These results indicate that while the VNR is the primary adhesion receptor for vWF, endothelial GPIbα can mediate HUVEC attachment to vWF. GpIb-dependent attachment could contribute to HUVEC adhesion under conditions when cell surface expression of the VNR is downregulated, and VNR-dependent adhesion is reduced.

scholarly journals Fibrinogen competes with von Willebrand factor for binding to the glycoprotein IIb/IIIa complex when platelets are stimulated with thrombin

Blood ◽  
1984 ◽  
Vol 64 (4) ◽  
pp. 797-800 ◽  
Author(s):  
HR Gralnick ◽  
SB Williams ◽  
BS Coller
Keyword(s):  
Monoclonal Antibodies ◽  
Von Willebrand Factor ◽  
Adenosine Diphosphate ◽  
Glycoprotein Ib ◽  
Human Fibrinogen ◽  
Factor Binding ◽  
Normal Plasma ◽  
Platelet Binding ◽  
Von Willebrand ◽  
Willebrand Factor

Two monoclonal antibodies--one that blocks ristocetin-induced platelet binding of von Willebrand factor to glycoprotein Ib and one that blocks adenosine diphosphate-induced binding of fibrinogen to the glycoprotein IIb/IIIa complex--were used to assess the binding site(s) for von Willebrand factor when platelets are stimulated with thrombin or adenosine diphosphate (ADP). Neither agonist induced binding of von Willebrand factor to glycoprotein Ib. ADP and thrombin induced von Willebrand factor binding exclusively to the glycoprotein IIb/IIIa complex. The results of the site of binding of von Willebrand factor with thrombasthenic platelets were consistent with the data obtained with the monoclonal antibodies and normal platelets. Human fibrinogen caused complete inhibition of thrombin-induced von Willebrand factor binding to normal platelets at concentrations considerably below that found in normal plasma. We conclude that thrombin induces very little binding of exogenous von Willebrand factor to platelets at normal plasma fibrinogen levels.

scholarly journals The binding domain of von Willebrand factor to sulfatides is distinct from those interacting with glycoprotein Ib, heparin, and collagen and resides between amino acid residues Leu 512 and Lys 673

Blood ◽  
1991 ◽  
Vol 78 (9) ◽  
pp. 2310-2317 ◽  
Author(s):  
O Christophe ◽  
B Obert ◽  
D Meyer ◽  
JP Girma
Keyword(s):  
Von Willebrand Factor ◽  
Competitive Inhibition ◽  
Binding Domain ◽  
Functional Site ◽  
Platelet Glycoprotein ◽  
Functional Domain ◽  
Amino Acid Residues ◽  
Glycoprotein Ib ◽  
Von Willebrand ◽  
Willebrand Factor

A series of proteolytic fragments of human von Willebrand Factor (vWF) was purified to characterize the functional site that supports its interaction with sulfatides. SpIII, an N-terminal homodimer generated by V-8 protease (amino acids [AA] 1 to 1365), bound to sulfatides in a dose-dependent and saturable way. SpIII also totally inhibited the binding of vWF to sulfatides and SpIII binding was completely abolished by vWF. In contrast, SpII, the complementary C-terminal homodimer (AA 1366 to 2050), did not exhibit any binding affinity for sulfatides. Four purified fragments overlapping the sequence of SpIII were also tested for their ability to interact with sulfatides. An N-terminal monomeric 34-Kd fragment (P34, AA 1 to 272) generated by plasmin, a central monomer (SpI, AA 911 to 1365) produced by digestion with V-8 protease, and a tetrameric fragment III-T2 (comprising a pair of the two sequences AA 273 to 511 and AA 674 to 728) produced by secondary digestion of SpIII with trypsin did not interact with sulfatides. In contrast, a monomeric 39/34-Kd fragment produced by dispase (AA 480 to 718) bound specifically and with a high affinity to sulfatides and totally displaced vWF or SpIII binding. Conversely, binding of the 39/34-Kd species was totally abolished by vWF or SpIII. Thus, a functional site responsible for sulfatide binding was localized between AA 480 and 718 and comparison of the binding properties of the 39/34-Kd and III-T2 fragments indicated that the sequence 512 to 673 is necessary for the binding to sulfatides. Further mapping of this new functional domain of vWF, based on experiments of competitive inhibition of binding by either heparin or monoclonal antibodies directed toward vWF, showed that the site interacting with sulfatides is distinct from those involved in binding to platelet glycoprotein Ib, collagen, or heparin. This finding was confirmed by experiments using synthetic peptides which also indicated that the sequence comprising AA 569 to 584 is part of the sulfatide-binding domain or influences its activity.

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