The Platelet-Endothelial Cell – VIII Axis

1976 ◽  
Vol 35 (01) ◽  
pp. 120-123 ◽  
Author(s):  
R. L Nachman ◽  
E. A Jaffe
Keyword(s):  
Endothelial Cells ◽  
Factor Viii ◽  
Von Willebrand Factor ◽  
Protein S ◽  
Human Platelets ◽  
Factor Activity ◽  
Normal Platelet ◽  
Factor Viii Antigen ◽  
Von Willebrand ◽  
Willebrand Factor

SummaryCultured human endothelial cells synthesize and secrete a protein(s) which has factor VIII antigen and von Willebrand factor activity. Subcellular membrane and granule fractions derived from human platelets also contain the factor VIII antigen and von Willebrand factor activity. Circulating platelets constitute a significant reservoir of VIII antigen containing approximately 15 % of the amount present in platelet-poor plasma. Thus normal platelets contain surface bound as well as intracellularly stored von Willebrand factor, a protein synthesized by endothelial cells which is required for normal platelet function.

scholarly journals Subcellular platelet factor VIII antigen and von Willebrand factor.

1975 ◽  
Vol 141 (5) ◽  
pp. 1101-1113 ◽  
Author(s):  
R L Nachman ◽  
E A Jaffe
Keyword(s):  
Factor Viii ◽  
Von Willebrand Factor ◽  
Human Platelets ◽  
Factor Vii ◽  
Platelet Factor ◽  
Plasma Factor ◽  
Factor Viii Antigen ◽  
Von Willebrand ◽  
Willebrand Factor

Subcellular membrane and granule fractions derived from human platelets contain factor VIIII antigen and von Willebrand factor activity but not factor VII procoagulant activity. Circulating platelets constitute a significant reservoir of plasma factor VIII antigen, containing approximately 15% of the amount of factor VIII antigen present in platelet-poor plasma. The antibiotic ristocetin, which aggregates human platelets in the presence of von Willebrand factor, nonspecifically precipitates platelet membrane factor VIII antigen. Thus normal platelets contain surface-bound as well as internally stored von Willebrand factor, a protein synthesized by endothelial cells which is necessary for normal platelet function in vivo.

Interactions of Purified Rat Factor VIII/von Willebrand Factor with Rat and Human Platelets – Effect of Albumin and Ristocetin

1984 ◽  
Vol 52 (01) ◽  
pp. 057-059 ◽  
Author(s):  
E Dejana ◽  
M Furlan ◽  
B Barbieri ◽  
M B Donati ◽  
E A Beck
Keyword(s):  
Factor Viii ◽  
Von Willebrand Factor ◽  
Rat Plasma ◽  
Human Platelets ◽  
High Concentrations ◽  
Low Sensitivity ◽  
Von Willebrand ◽  
Induced Aggregation ◽  
Willebrand Factor ◽  
Rat Platelets

SummaryRat platelets do not respond to ristocetin in their own plasma nor do they aggregate in the presence of bovine or porcine factor VIII von Willebrand factor (F VIII R:WF) or human F VIII R:WF in presence of ristocetin. However, rat plasma supports ristocetin induced aggregation of washed human platelets. In this study we report on purification of rat F VIII R:WF from cryoprecipitate. Similarly to porcine or bovine material, purified rat F VIII R:WF induced aggregation of human washed fixed platelets. This effect was enhanced by addition of ristocetin and was not modified by addition of albumin. Rat washed platelets were aggregated by ristocetin in the presence of rat or human F VIII R:WF provided that high concentrations of ristocetin are added in a system essentially free of extraneous proteins. Increasing concentrations of albumin dramatically reduced the ability of ristocetin to aggregate rat platelets while human platelet aggregation by human or rat F VIII R:WF was only moderately affected.These studies show that rat F VIII R:WF can interact with rat and human platelets. The lack of response of rat platelets to ristocetin in their own plasma is most likely due to a low sensitivity of rat platelets to this drug and to an inhibitory activity of plasma proteins on this reaction.

The Importance of the Carbohydrate Moiety of the Factor VIII/Von Willebrand Factor Protein in Binding to and Causing Agglutination of Human Platelets

1979 ◽  
Author(s):  
H.R. Gralnick ◽  
D.K. Morisato
Keyword(s):  
Factor Viii ◽  
Von Willebrand Factor ◽  
Binding Sites ◽  
Human Platelets ◽  
Galactose Oxidase ◽  
Scatchard Analysis ◽  
Human Fibrinogen ◽  
Number Of Binding Sites ◽  
Von Willebrand ◽  
Willebrand Factor

We have investigated the binding of radiolabelled factor VIII/von Willebrand factor (f. VIII/vWf) protein to human platelets (P) in the presence of ristocetin (R). In these atudies we have delineated the importance of the carbohydrate (CHO) moiety(s) in both the binding to the P and in cauaing agglutination of P. Binding of the f.VIII/vWf protein to human P was time and temperature dependent and dependent on the concentration of R. Binding was specific in that it could not be blocked by human fibrinogen but was inhibited by unlabelled f.VIII/vWf protein. In studies utilizing varying amounts of the f.VIII/vWf protein or by varying the number of P in the assay, the number of binding sites for the f. VIII/vWf protein were estimated at 9,500-9,800 per platelet. Scatchard analysis revealed 11,000 binding sites with 3,600 of high affinity and 7,400 of low affinity. Removal of the sialic acid of the f.VIII/vWf protein resulted in no significa nt change in its ability to bind to the P surface or cause agglutination in the presence, IR. Removal of the galactose by 6-galactosijase resulted in a 75% reduction of binding of the f.VIII/vWf protein and a 91% decrease in the agglutination of human P. Similar studies with galactose oxidase showed that oxidation of the penultimate galactose residue s results in a decrease in agglutination comparable to that seen with 6-galactosidase treatment. These studies indicate that the CHO moiety of the f.VIII/vWf protein is important in both binding to the P surface as well as causing agglutination of human P.

scholarly journals von Willebrand Factor Activity in Plasmin Digests of Factor VIII

1977 ◽  
Author(s):  
J. A. Guisasola ◽  
C. Cockburn ◽  
R. M. Hardisty
Keyword(s):  
Factor Viii ◽  
Von Willebrand Factor ◽  
Human Factor ◽  
Factor Activity ◽  
Group Iii ◽  
Molecular Weights ◽  
Human Factor Viii ◽  
Group Ii ◽  
Von Willebrand ◽  
Willebrand Factor

Purified human factor VIII was incubated for up to 24 hours with plasmin, and the activity of the breakdown products studied at intervals. Factor VIII coagulant activity was lost within the first hour, but von Willebrand factor activity (FVIIIR:WF) was retained for two hours, and then declined slowly during the subsequent incubation. Analysis of the 24-hour breakdown products by immuno-electrophoresis, sepharose 4B chromatography and SDS Polyacrylamide electrophoresis revealed three main groups of fragments recognised by rabbit anti-human factor VIII anti-serum, and having molecular weights in the following ranges: Group 1 300,000=500,000; Group II, 150–200,000; Group III, 100,000. FVIIIR:WF activity, which was found only in Group II, appeared to be associated with glycopeptide(s) of up to 155,000 daltons.

A Novel Mutation in the D3 Domain of von Willebrand Factor Markedly Decreases Its Ability to Bind Factor VIII and Affects Its Multimerization

Blood ◽  
1998 ◽  
Vol 92 (12) ◽  
pp. 4663-4670 ◽  
Author(s):  
S. Jorieux ◽  
C. Gaucher ◽  
J. Goudemand ◽  
C. Mazurier
Keyword(s):  
Factor Viii ◽  
Von Willebrand Factor ◽  
Stop Codon ◽  
Novel Mutation ◽  
Von Willebrand Disease ◽  
Enzyme Linked Immunosorbent Assay ◽  
Sequencing Analysis ◽  
Normal Platelet ◽  
Von Willebrand ◽  
Willebrand Factor

Abstract In type 2N von Willebrand disease (vWD), von Willebrand factor (vWF) is characterized by normal multimeric pattern, normal platelet-dependent function, but a markedly decreased affinity for factor VIII (FVIII). In this report, we describe the case of a vWD patient who has an abnormal vWF multimers distribution associated with a markedly decreased vWF ability to bind FVIII. Sequencing analysis of patient’s vWF gene showed, at heterozygous state, a G→A transition resulting in the substitution of Asn for Asp at position 116 of the mature vWF subunit and a C→T transition, changing the codon for Arg 896 into a stop codon. His sister who has a subnormal vWF level, but a normal FVIII/vWF interaction, was found to be heterozygous for the Arg896ter mutation only. Recombinant vWF (rvWF) containing the candidate (Asn116) missense mutation was expressed in COS-7 cells. The expression level of Asn116rvWF was significantly decreased compared with wild-type rvWF. The multimeric pattern of Asn116rvWF was greatly impaired as shown by the decrease in high molecular weight forms. The FVIII binding ability of Asn116rvWF was dramatically decreased. These data show that the Asp116Asn substitution is the cause of both the defective FVIII/vWF interaction and the impaired multimeric pattern observed in the patient’s vWF. The monoclonal antibody 31H3 against D’ domain of vWF (epitope aa 66-76) that partially inhibits the FVIII binding and recognizes only nonreduced vWF, showed a decreased ability to bind Asn116rvWF when used as capture-antibody in enzyme-linked immunosorbent assay (ELISA). This result suggests that a potential conformation change in the D’ domain is induced by the Asp116Asn substitution, which is localized in the D3 domain.

scholarly journals Effect of multimeric structure of the factor VIII/von Willebrand factor protein on binding to platelets

Blood ◽  
1981 ◽  
Vol 58 (2) ◽  
pp. 387-397 ◽  
Author(s):  
HR Gralnick ◽  
SB Williams ◽  
DK Morisato
Keyword(s):  
Factor Viii ◽  
Von Willebrand Factor ◽  
Competitive Inhibition ◽  
Human Platelets ◽  
Factor Vii ◽  
Variant Form ◽  
Factor Binding ◽  
Plasma Factor ◽  
Von Willebrand ◽  
Willebrand Factor

The characteristics of the intact factor VIII/von Willebrand factor protein binding to human platelets was compared to 2-mercaptoethanol- treated factor VIII/von Willebrand factor protein and to fractions of plasma factor VIII/von Willebrand factor protein that elute after the void volume. These studies indicate that the factor VIII/von Willebrand factor protein larger size oligomers bind preferentially with high affinity to low capacity sites on human platelets. The intermediate and smaller size oligomers bind with intermediate or low affinity to sites with a much greater capacity. The results from binding analysis are also paralleled by the competitive inhibition of the intact factor VIII/von Willebrand factor protein by the various 2-mercaptoethanol- treated materials. These studies indicate that the two classes of binding sites seen in previous reports of factor VII/von Willebrand factor binding reflect heterogeneity in the oligomer size of the factor VIII/von Willebrand factor protein used in these assays. This study provides a model for understanding some of the normal structure- function relationships of the normal factor VIII/von Willebrand factor protein and the defect(s) in a variant form of von Willebrand's disease. In this form of the disease, decreased factor VIII/von Willebrand factor binding to platelets is reflected in decreased von Willebrand factor activity but coagulant and/or antigen levels are normal or only slightly decreased.

Effect Of The Multimeric Structure Of The Factor VIII/Von Willebrand Factor Protein On Binding To Human Platelets

1981 ◽  
Author(s):  
H Gralnick ◽  
S Williams ◽  
D J Morisato
Keyword(s):  
Factor Viii ◽  
Von Willebrand Factor ◽  
Competitive Inhibition ◽  
High Capacity ◽  
Molecular Size ◽  
Human Platelets ◽  
Affinity Binding ◽  
Platelet Receptor ◽  
Von Willebrand ◽  
Willebrand Factor

We have studied the characteristics of binding of intact factor VIII/von Willebrand factor (f. VIII/vWf) protein and 2-mercaptoethanol (2ME) treated f. VIII/vWf protein to human platelets. The purified f. VIII/vWf was radiolabelled with tritiated 3H potassium borohydride; 4.5 × 103 molecules of the intact radiolabelled material bound per platelet. Of these some molecules bound with a high affinity/low capacity (Kd 0.21 nM and 1.5 × 103 molecules) and another with a low affinity/high capacity (Kd 2.5 nM and 3 × 103 molecules). When the material was reduced with 2ME at 0.01%, it bound with an intermediate affinity of 1.6 nM with a capacity of 4.0 × 103 and a low affinity binding of 12.5 nM and a capacity of 4.0 × 103 . The 0.1% 2ME-treated material revealed only low affinity binding with a Kd of 15 nM and the number of molecules bound 13 × 103. Studies of competitive inhibition of the intact f. VIII/vWf binding to human platelets by the reduced materials revealed that the smallest f. VIII/vWf protein (i.e., 0.1% 2ME) was the least effective while the 0.01% 2ME material was intermediate between the 0.1% and the intact material. The differences noted in the ability to displace the intact material as well as in binding to the human platelet were paralleled by decreases in the vWf activity of these proteins.These studies aid in our understanding of the binding of the f. VIII/vWf to platelets in that the binding sites on platelets may be homogeneous while the ligand is heterogenous. These studies reinforce the structure/function relationships of f. VIII/vWf proteins which have been defined using ristocetin-induced platelet aggregation (i.e., the minimum molecular size of the f. VIII/vWf protein and the penultimate galactose residues on the carbohydrate side chain). We conclude that these defects of the f. VIII/vWf protein also interfere with the protein binding to its platelet receptor and that f. VIII/vWf binding to platelets is an important primary step in hemostasis.

Sign in / Sign up

Export Citation Format

Share Document