scholarly journals Hydrolysis of human platelet membrane glycoproteins with a Serratia marcescens metalloprotease: Effect on response to thrombin and von Willebrand factor

1982 ◽  
Vol 79 (5) ◽  
pp. 1433-1437 ◽  
Author(s):  
H. A. Cooper ◽  
W. P. Bennett ◽  
G. C. White ◽  
R. H. Wagner
Keyword(s):  
Serratia Marcescens ◽  
Von Willebrand Factor ◽  
Human Platelet ◽  
Platelet Membrane ◽  
Membrane Glycoproteins ◽  
Von Willebrand ◽  
Willebrand Factor ◽  
Hydrolysis Of

Role of Platelet Membrane Glycoproteins and Von Willebrand Factor in Adhesion of Platelets to Subendothelium and Collagen

1987 ◽  
Vol 516 (1 Blood in Cont) ◽  
pp. 52-65 ◽  
Author(s):  
KJELL S. SAKARIASSEN ◽  
EDITH FRESSINAUD ◽  
JEAN-PIERRE GIRMA ◽  
DOMINIQUE MEYER ◽  
HANS R. BAUMGARTNER
Keyword(s):  
Von Willebrand Factor ◽  
Platelet Membrane ◽  
Membrane Glycoproteins ◽  
Von Willebrand ◽  
Willebrand Factor ◽  
Adhesion Of Platelets

scholarly journals Phospholipase abolishes the effect of stimulated platelets on the thrombin activation of factor VIII

Blood ◽  
1988 ◽  
Vol 71 (1) ◽  
pp. 173-177
Author(s):  
ME Rick ◽  
DM Krizek
Keyword(s):  
Factor Viii ◽  
Von Willebrand Factor ◽  
Calcium Ionophore ◽  
Platelet Membrane ◽  
Activate Factor ◽  
Membrane Glycoproteins ◽  
Membrane Phospholipids ◽  
Thrombin Activation ◽  
Von Willebrand ◽  
Willebrand Factor

Factor VIII functions as a cofactor in the intrinsic coagulation pathway and must first be activated to function optimally in this capacity. Low concentrations of thrombin activate factor VIII, and the presence of stimulated platelets is known to enhance the activation of factor VIII complexed to von Willebrand factor. The current studies show that platelets stimulated by thrombin, collagen, or calcium ionophore will increase the activation of isolated factor VIII by thrombin. Ongoing platelet release is not necessary for the enhanced factor VIII activation, nor is platelet von Willebrand factor or platelet membrane glycoproteins Ib or IIb/IIIa. Platelet membrane phospholipids, on the other hand, are important for the enhanced activation of factor VIII by thrombin because the effect of stimulated platelets is abolished by incubation of the stimulated platelets with phospholipases. These results suggest that the enhanced activation of factor VIII by thrombin in the presence of stimulated platelets may be mediated by factor VIII binding to platelet phospholipid or to a receptor whose functional integrity is dependent on surrounding membrane phospholipid.

scholarly journals Platelet-collagen interaction: inhibition by ristocetin and enhancement by von Willebrand factor-platelet binding

Blood ◽  
1986 ◽  
Vol 68 (4) ◽  
pp. 927-937
Author(s):  
FM LaDuca ◽  
RE Bettigole ◽  
WR Bell ◽  
EB Robson
Keyword(s):  
Platelet Aggregation ◽  
Von Willebrand Factor ◽  
Platelet Rich Plasma ◽  
Platelet Membrane ◽  
Type I ◽  
Membrane Glycoproteins ◽  
Platelet Binding ◽  
Von Willebrand ◽  
Willebrand Factor

The contribution of von Willebrand factor (vWF)-platelet binding to platelet-collagen interaction was examined in vitro. The binding of vWF to platelets was mediated and regulated by ristocetin. Subthreshold concentrations of ristocetin (less than or equal to 1 mg/mL), insufficient to cause ristocetin-induced platelet aggregation (RIPA), were added to platelet-rich plasma (PRP) prior to the addition of collagen. The collagen-induced platelet aggregation (CIPA) was modified by ristocetin and the degree of alteration was dependent on the ristocetin concentration. Response as a function of ristocetin concentration was designated the Collagen-Platelet Aggregation Response (CoI-PAR). In normal PRP the CoI-PAR was a progressive inhibition followed by decreasing inhibition and then an enhanced response. The enhanced response occurred over a narrow range of ristocetin concentrations (0.8 to 1.0 mg/mL). In the absence of vWF (severe von Willebrand's disease, Type I, vWF less than 1%) the CoI-PAR was a progressive, eventually complete inhibition with no enhanced response (with ristocetin concentrations up to 3.0 mg/mL). With addition of vWF to this PRP an enhanced response was observed at a ristocetin concentration inversely proportional to the vWF level. PRP from a patient with severe Hemophilia A showed a response within the normal range. Subthreshold ristocetin did not cause plasma protein precipitation or platelet release of 3H-serotonin, nor induce micro platelet aggregate formation. Digestion of platelet membrane glycoproteins (GP(s] with chymotrypsin demonstrated that upon removal of GPI, RIPA was absent, CIPA retained and the CoI-PAR was progressive inhibition, with no enhancement. With removal of GPs I, II, and III, RIPA, CIPA, and the CoI-PAR were absent. A dose-response 125I-vWF- platelet binding occurred with increasing ristocetin concentrations which was unchanged by the addition of collagen. These results demonstrated that ristocetin-platelet association inhibited CIPA, and vWF-platelet binding enhanced platelet-collagen adhesion and platelet aggregation. The in vitro-enhanced CIPA represents a vWF-dependent aggregation of sufficient magnitude to overcome the inhibitory effect of ristocetin. These studies demonstrate an influential interaction of ristocetin, vWF, and collagen with the platelet membrane and imply an important hemostatic contribution of vWF-platelet binding in platelet- collagen interaction.

scholarly journals Phospholipase abolishes the effect of stimulated platelets on the thrombin activation of factor VIII

Blood ◽  
1988 ◽  
Vol 71 (1) ◽  
pp. 173-177 ◽  
Author(s):  
ME Rick ◽  
DM Krizek
Keyword(s):  
Factor Viii ◽  
Von Willebrand Factor ◽  
Calcium Ionophore ◽  
Platelet Membrane ◽  
Activate Factor ◽  
Membrane Glycoproteins ◽  
Membrane Phospholipids ◽  
Thrombin Activation ◽  
Von Willebrand ◽  
Willebrand Factor

Abstract Factor VIII functions as a cofactor in the intrinsic coagulation pathway and must first be activated to function optimally in this capacity. Low concentrations of thrombin activate factor VIII, and the presence of stimulated platelets is known to enhance the activation of factor VIII complexed to von Willebrand factor. The current studies show that platelets stimulated by thrombin, collagen, or calcium ionophore will increase the activation of isolated factor VIII by thrombin. Ongoing platelet release is not necessary for the enhanced factor VIII activation, nor is platelet von Willebrand factor or platelet membrane glycoproteins Ib or IIb/IIIa. Platelet membrane phospholipids, on the other hand, are important for the enhanced activation of factor VIII by thrombin because the effect of stimulated platelets is abolished by incubation of the stimulated platelets with phospholipases. These results suggest that the enhanced activation of factor VIII by thrombin in the presence of stimulated platelets may be mediated by factor VIII binding to platelet phospholipid or to a receptor whose functional integrity is dependent on surrounding membrane phospholipid.

scholarly journals Platelet-collagen interaction: inhibition by ristocetin and enhancement by von Willebrand factor-platelet binding

Blood ◽  
1986 ◽  
Vol 68 (4) ◽  
pp. 927-937 ◽  
Author(s):  
FM LaDuca ◽  
RE Bettigole ◽  
WR Bell ◽  
EB Robson
Keyword(s):  
Platelet Aggregation ◽  
Von Willebrand Factor ◽  
Platelet Rich Plasma ◽  
Platelet Membrane ◽  
Type I ◽  
Membrane Glycoproteins ◽  
Platelet Binding ◽  
Von Willebrand ◽  
Willebrand Factor

Abstract The contribution of von Willebrand factor (vWF)-platelet binding to platelet-collagen interaction was examined in vitro. The binding of vWF to platelets was mediated and regulated by ristocetin. Subthreshold concentrations of ristocetin (less than or equal to 1 mg/mL), insufficient to cause ristocetin-induced platelet aggregation (RIPA), were added to platelet-rich plasma (PRP) prior to the addition of collagen. The collagen-induced platelet aggregation (CIPA) was modified by ristocetin and the degree of alteration was dependent on the ristocetin concentration. Response as a function of ristocetin concentration was designated the Collagen-Platelet Aggregation Response (CoI-PAR). In normal PRP the CoI-PAR was a progressive inhibition followed by decreasing inhibition and then an enhanced response. The enhanced response occurred over a narrow range of ristocetin concentrations (0.8 to 1.0 mg/mL). In the absence of vWF (severe von Willebrand's disease, Type I, vWF less than 1%) the CoI-PAR was a progressive, eventually complete inhibition with no enhanced response (with ristocetin concentrations up to 3.0 mg/mL). With addition of vWF to this PRP an enhanced response was observed at a ristocetin concentration inversely proportional to the vWF level. PRP from a patient with severe Hemophilia A showed a response within the normal range. Subthreshold ristocetin did not cause plasma protein precipitation or platelet release of 3H-serotonin, nor induce micro platelet aggregate formation. Digestion of platelet membrane glycoproteins (GP(s] with chymotrypsin demonstrated that upon removal of GPI, RIPA was absent, CIPA retained and the CoI-PAR was progressive inhibition, with no enhancement. With removal of GPs I, II, and III, RIPA, CIPA, and the CoI-PAR were absent. A dose-response 125I-vWF- platelet binding occurred with increasing ristocetin concentrations which was unchanged by the addition of collagen. These results demonstrated that ristocetin-platelet association inhibited CIPA, and vWF-platelet binding enhanced platelet-collagen adhesion and platelet aggregation. The in vitro-enhanced CIPA represents a vWF-dependent aggregation of sufficient magnitude to overcome the inhibitory effect of ristocetin. These studies demonstrate an influential interaction of ristocetin, vWF, and collagen with the platelet membrane and imply an important hemostatic contribution of vWF-platelet binding in platelet- collagen interaction.

The Effect Of Serratia Marcescens Protease On The Aggregation Of Human Platelets By Von Willebrand Factor And Thrombin

1981 ◽  
Author(s):  
H Cooper ◽  
W Bennett ◽  
G White ◽  
R Wagner
Keyword(s):  
Serratia Marcescens ◽  
Von Willebrand Factor ◽  
Human Platelets ◽  
Serotonin Release ◽  
The Other ◽  
Minor Importance ◽  
Membrane Glycoproteins ◽  
Platelet Surface ◽  
Von Willebrand ◽  
Willebrand Factor

Serratia marcescens produces an extracellular metallo-protease (SP) that selectively attacks the surface of human fixed washed platelets and renders them unresponsive to human or bovine von Willebrand factor (vWF). SP treated fresh washed human platelets were studied for [14C]serotonin release, alterations in surface glycoproteins, and aggregation by bovine vWF and thrombin. Platelet membrane glycoproteins were identified by conventional discontinuous gel electrophoresis techniques using periodic acid Schiff reagent (PAS) to stain for carbohydrate. With SP concentrations above 0.6 μg/ml, there was loss of a single PAS band of ~180,000 MW, corresponding to GPlb. With an even more sensitive technique employing [3H]labelled platelets and autoradiography no significant loss of any of the other membrane glycoproteins was found, even at SP concentrations of 20 μg/ml. Supernatants from these treated platelets showed only a single glycoprotein of ~125,000 MW. The use of SP alone with fresh platelets did not cause aggregation or release. SP treatment did cause a complete loss of both serotonin release and aggregation by bovine vWF, but had only a minimal effect on the release and aggregation caused by thrombin. These studies show that SP selectively cleaves GPlb from the platelet surface. The cleaved fragment is smaller than glycocalicin (145,000 MW), suggesting that SP cleaves at a different site than the Ca2+ dependent protease(s) normally present on the platelet surface. These studies suggest that the 125,000 MW fragment cleaved from GPlb is essential for vWF to cause normal platelet release and aggregation. On the other hand, it appears that cleavage of the majority of GPlb is of only minor importance in the release and aggregation mechanism mediated by thrombin.

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