A novel mis-sense mutation in the platelet glycoprotein CD36 is associated with protection from malaria

SummaryThe interaction between GPIb and thrombin promotes platelet activation elicited via the hydrolysis of the thrombin receptor and involves structures located on the segment 238-290 within the N-terminal domain of GPIbα and the positively charged exosite 1 on thrombin. We have investigated the ability of peptides derived from the 269-287 sequence of GPIbα to interact with thrombin. Three peptides were synthesized, including Ibα 269-287 and two scrambled peptides R1 and R2 which are comparable to Ibα 269-287 with regards to their content and distribution of anionic residues. However, R2 differs from both Ibα 269-287 and R1 by the shifting of one proline from a central position to the N-terminus. By chemical cross-linking, we observed the formation of a complex between 125I-Ibα 269-287 and α-thrombin that was inhibited by hirudin, the C-terminal peptide of hirudin, sodium pyrophosphate but not by heparin. The complex did not form when γ-thrombin was substituted for α-thrombin. Ibα 269-287 produced only slight changes in thrombin amidolytic activity and inhibited thrombin binding to fibrin. R1 and R2 also formed complexes with α-thrombin, modified slightly its catalytic activity and inhibited its binding to fibrin. Peptides Ibα 269-287 and R1 inhibited platelet aggregation and secretion induced by low thrombin concentrations whereas R2 was without effect. Our results indicate that Ibα 269-287 interacts with thrombin exosite 1 via mainly electrostatic interactions, which explains why the scrambled peptides also interact with exosite 1. Nevertheless, the lack of effect of R2 on thrombin-induced platelet activation suggests that proline 280 is important for thrombin interaction with GPIb.

Download Full-text

Platelet Activation and Aggregation Induced by Recombinant von Willebrand Factors Reproducing Four Type 2B von Willebrand Disease Missense Mutations

Thrombosis and Haemostasis ◽

10.1055/s-0037-1614241 ◽

1998 ◽

Vol 79 (01) ◽

pp. 211-216 ◽

Cited By ~ 13

Author(s):

Lysiane Hilbert ◽

Claudine Mazurier ◽

Christophe de Romeuf

Keyword(s):

Platelet Aggregation ◽

Platelet Activation ◽

Von Willebrand Disease ◽

Platelet Glycoprotein ◽

Missense Mutations ◽

Inhibit Platelet Aggregation ◽

Wild Type ◽

A1 Domain ◽

Von Willebrand ◽

Willebrand Factor

SummaryType 2B of von Willebrand disease (vWD) refers to qualitative variants with increased affinity of von Willebrand factor (vWF) for platelet glycoprotein Ib (GPIb). All the mutations responsible for type 2B vWD have been located in the A1 domain of vWF. In this study, various recombinant von Willebrand factors (rvWF) reproducing four type 2B vWD missense mutations were compared to wild-type rvWF (WT-rvWF) for their spontaneous binding to platelets and their capacity to induce platelet activation and aggregation. Our data show that the multimeric pattern of each mutated rvWF is similar to that of WT-rvWF but the extent of spontaneous binding and the capacity to induce platelet activation and aggregation are more important for the R543Q and V553M mutations than for the L697V and A698V mutations. Both the binding of mutated rvWFs to platelets and platelet aggregation induced by type 2B rvWFs are inhibited by monoclonal anti-GPIb and anti-vWF antibodies, inhibitors of vWF binding to platelets in the presence of ristocetin, as well as by aurin tricarboxylic acid. On the other hand, EDTA and a monoclonal antibody directed against GPIIb/IIIa only inhibit platelet aggregation. Furthermore, the incubation of type 2B rvWFs with platelets, under stirring conditions, results in the decrease in high molecular weight vWF multimers in solution, the extent of which appears correlated with that of plasma vWF from type 2B vWD patients harboring the corresponding missense mutation. This study supports that the binding of different mutated type 2B vWFs onto platelet GPIb induces various degrees of platelet activation and aggregation and thus suggests that the phenotypic heterogeneity of type 2B vWD may be related to the nature and/or location of the causative point mutation.

Download Full-text

A Heparin-coated Circuit Maintains Platelet Aggregability in Response to Shear Stress in an In Vitro Model of Cardiopulmonary Bypass

Thrombosis and Haemostasis ◽

10.1055/s-0037-1615226 ◽

1998 ◽

Vol 80 (09) ◽

pp. 437-442 ◽

Cited By ~ 2

Author(s):

I. Hioki ◽

K. Onoda ◽

T. Shimono ◽

H. Shimpo ◽

K. Tanaka ◽

...

Keyword(s):

Shear Stress ◽

Cardiopulmonary Bypass ◽

Membrane Skeleton ◽

Platelet Glycoprotein ◽

Platelet Surface ◽

Platelet Aggregability ◽

Vitro Model ◽

Platelet Defects ◽

Set Up

SummaryAlterations in platelet aggregability may play a role in the pathogenesis of qualitative platelet defects associated with cardiopulmonary bypass (CPB). We circulated fresh heparinized whole blood through tubing sets coated with heparin (C group, n = 10) and through non-coated sets (N group, n = 10) as a simulated CPB circuit. Shear stress (108 dyne/cm2)-induced platelet aggregation (hSIPA), plasma von Willebrand factor (vWF) activity and platelet glycoprotein (GP) Ib expression were measured, before, during, and after this in vitro set up of circulation. In the two groups, the extent of hSIPA significantly decreased during circulation and was partially restored after circulation. Decreases in the extent of hSIPA were significantly less with use of heparin-coated circuits. There was an equivalent reduction in plasma vWF activity, in the two groups. Expression of platelet surface GP Ib decreased significantly during circulation and recovered after circulation. Reduction of surface GP Ib expression during circulation was significantly less in the C group than that in the N group. Decrease in surface GP Ib expression correlated (r = 0.88 in either group) with the magnitude of hSIPA, in the two groups. The progressive removal of surface GP Ib was mainly attributed to redistribution of GP Ib from the membrane skeleton into the cytoskeleton. Our observations suggest that use of heparin-coated circuits partly blocks the reduction of hSIPA, as a result of a lesser degree of redistribution of GP Ib.

Download Full-text

Immunoelectrophoretic Analysis of Membrane Glycoproteins in Cultured Human Endothelial Cells

Thrombosis and Haemostasis ◽

10.1055/s-0038-1645214 ◽

1990 ◽

Vol 63 (02) ◽

pp. 303-311

Author(s):

Tone Børsum

Keyword(s):

Endothelial Cells ◽

Endothelial Cell ◽

Rabbit Antiserum ◽

Platelet Glycoprotein ◽

Membrane Glycoproteins ◽

Human Endothelial Cells ◽

Immunoelectrophoretic Analysis ◽

Glycoprotein Complex ◽

Crossed Immunoelectrophoresis ◽

Triton X

SummaryHuman endothelial cells isolated from umbilical cordswere solubilized in Triton X-100 and examined by crossedimmunoelec-trophoresis using rabbit antiserum against endothelial cells. Endogenous labelling of the endothelialcell proteins with 14Cmannose followed by crossed immunoelectrophoresis and autoradiography revealed about 10 immunoprecipitates. Four of these endothelial cell glycoproteins were labelled by lactoperoxidase catalyzed iodination and thus were surface located. Three of the surface located glycoproteins showed reduced electrophoretic mobility after incubation of the endothelial cells with neuraminidase and were therefore sialoglycoproteins. Amphiphilicity of endothelial cell glycoproteins was studied by crossed hydrophobic interaction immunoelectrophoresis with phenyl-Sepharose in the intermediate gel. Amphiphilic proteins also show increasing electrophoretic migration velocity with decreasing concentration of Triton X-100 in the first dimension gels. Five of the endothelial cell glycoproteins were shown to be amphiphilic using these two techniques.Two monoclonal antibodies against the platelet glycoprotein complex Ilb-IIIa and glycoprotein IlIa, respectively, reacted with the same precipitate of endothelial cells. When a polyclonal antibody against the platelet glycoprotein complex Ilb-IIIa was incorporated into the intermediate gel the position of two endothelial cell precipitates were lowered. One of these was a sialoglycoprotein.

Download Full-text

Ristocetin and Botrocetin Involve Two Distinct Domains of von Willebrand Factor for Binding to Platelet Membrane Glycoprotein lb

Thrombosis and Haemostasis ◽

10.1055/s-0038-1647310 ◽

1990 ◽

Vol 64 (02) ◽

pp. 326-332 ◽

Cited By ~ 57

Author(s):

J P Girma ◽

Y Takahashi ◽

A Yoshioka ◽

J Diaz ◽

D Meyer

Keyword(s):

Von Willebrand Factor ◽

Synthetic Peptides ◽

Competitive Inhibition ◽

Final Concentration ◽

Binding Domain ◽

Platelet Membrane ◽

Platelet Glycoprotein ◽

Membrane Glycoprotein ◽

Von Willebrand ◽

Willebrand Factor

SummaryWe have evidence that ristocetin and botrocetin mediate binding of von Willebrand Factor (vWF) to platelet glycoprotein lb (GPIb) through two distinct domains on the vWF molecule. This was established by using monoclonal antibodies (MAbs) to vWF and synthetic peptides derived from the sequence of vWF. MAb 322 and MAb NMC/vW 4 both recognize native vWF as well as fragments containing the GPIb-binding domain of vWF, obtained with the following enzymes: trypsin (116 kDa), V-8 pro tease (Spill, 320 kDa) and V-8 protease plus subtilisin (33-28 kDa). Nevertheless, the lack of reciprocal displacement between the two MAbs in experiments of competitive inhibition for binding to vWF demonstrate that their respective epitopes are separate. Both MAbs inhibit 125I-vWF binding to platelet membrane GPIb and vWF-dependent platelet agglutination induced by ristocetin. However, only MAb NMC/vW4 inhibits these functions in the presence of botrocetin and when ristocetin-induced platelet agglutination is inhibited by MAb 322, botrocetin is still able to restore the agglutination. The involvement of two distinct domains of vWF for binding to GPIb in the presence of ristocetin or botrocetin was confirmed in experiments of binding of 125I-vWF to platelets using as competitor synthetic peptides corresponding to the GPIb binding domain of vWF (Cys 474 to Pro 488 and Ser 692 to Pro 708). At a final concentration of 2.5 mM both peptides inhibit more than 90% of the binding of vWF to ristocetin-treated platelets but are unable to modify this binding in the presence of botrocetin. In conclusion our data suggest that botrocetin and ristocetin involve distinct sites on vWF for binding to GPIb.

Download Full-text

The Interaction of Botrocetin with Normal or Variant von Willebrand Factor (Types IIA and IIB) and Its Inhibition by Monoclonal Antibodies that Block Receptor Binding

Thrombosis and Haemostasis ◽

10.1055/s-0038-1646298 ◽

1992 ◽

Vol 68 (04) ◽

pp. 464-469 ◽

Cited By ~ 9

Author(s):

Y Fujimura ◽

S Miyata ◽

S Nishida ◽

S Miura ◽

M Kaneda ◽

...

Keyword(s):

Monoclonal Antibodies ◽

Von Willebrand Factor ◽

Binding Activity ◽

Von Willebrand Disease ◽

Platelet Glycoprotein ◽

Normal Individuals ◽

Rag 1 ◽

The One ◽

Von Willebrand ◽

Willebrand Factor

SummaryWe have recently shown the existence of two distinct forms of botrocetin (one-chain and two-chain), and demonstrated that the two-chain species is approximately 30 times more active than the one-chain in promoting von Willebrand factor (vWF) binding to platelet glycoprotein (GP) Ib. The N-terminal sequence of two-chain botrocetin is highly homologous to sea-urchin Echinoidin and other Ca2+-dependent lectins (Fujimura et al., Biochemistry 1991; 30: 1957–64).Present data indicate that purified two-chain botrocetin binds to vWF from plasmas of patients with type IIA or IIB von Willebrand disease and its interaction is indistinguishable from that with vWF from normal individuals. However, an “activated complex” formed between botrocetin and IIB vWF expresses an enhanced biological activity for binding to GP Ib whereas the complex with IIA vWF has a decreased binding activity. Among several anti-vWF monoclonal antibodies (MoAbs) which inhibit ristocetin-induced platelet aggregation and/or vWF binding to GPIb, only two MoAbs (NMC-4 and RFF-VIII RAG:1) abolished direct binding between purified botrocetin and vWF. This suggests that they recognize an epitope(s) on the vWF molecule in close proximity to the botrocetin binding site.

Download Full-text

A Monoclonal Antibody to the Human Platelet Glycoprotein II b/III a Complex Induces Platelet Activation

Thrombosis and Haemostasis ◽

10.1055/s-0038-1647637 ◽

1988 ◽

Vol 60 (01) ◽

pp. 068-074 ◽

Cited By ~ 33

Author(s):

Piet W Modderman ◽

Han G Huisman ◽

Jan A van Mourik ◽

Albert E G Kr von dem Borne

Keyword(s):

Human Platelet ◽

Adenosine Diphosphate ◽

Dense Granule ◽

Platelet Glycoprotein ◽

Activated Platelets ◽

Complex Functions ◽

Slow Aggregation ◽

Irreversible Aggregation ◽

Platelet Release ◽

Aggregation Of Platelets

SummaryThe platelet glycoprotein (GP) IIb/IIIa complex functions as the receptor for fibrinogen on activated platelets. The effects of two anti-GPIIb/IIIa monoclonal antibodies on platelet function were studied. These antibodies, 6C9 and C17, recognized different epitopes, which were exclusively present on the undissociated GPIIb/IIIa complex. Whereas C17 inhibited the binding of fibrinogen to platelets and platelet aggregation induced by adenosine diphosphate (ADP) or collagen, 6C9 caused irreversible aggregation of platelets, both in the presence and absence of extracellular fibrinogen. When incubated with unstirred (nonaggregating) platelets, 6C9 induced release of alpha and dense granule-constituents as well as binding of 125I-fibrinogen to platelets. The latter was evidently mediated in part by platelet-derived ADP, since it was inhibited to a large extent by apyrase, the ADP-hydrolyzing enzyme. F(ab’)2 fragments of 6C9 did not induce platelet-release reactions but caused (slow) aggregation of platelets in the presence of extracellular fibrinogen.These results indicate that binding of an antibody to a specific site on the platelet GPIIb/IIIa complex may cause fibrinogen-mediated aggregation. The Fc part of the platelet-bound antibody appears to be involved in the induction of platelet release.

Download Full-text

Cloning of the cDNA Encoding Human Platelet CD36: Comparison to PCR Amplified Fragments of Monocyte, Endothelial and HEL Cells

Thrombosis and Haemostasis ◽

10.1055/s-0038-1649613 ◽

1993 ◽

Vol 70 (03) ◽

pp. 500-505 ◽

Cited By ~ 17

Author(s):

B Wyler ◽

L Daviet ◽

H Bortkiewicz ◽

J-C Bordet ◽

J L McGregor

Keyword(s):

Apparent Molecular Weight ◽

Platelet Glycoprotein ◽

Rt Pcr ◽

Post Translational Modifications ◽

Hel Cells ◽

Flanking Region ◽

Polymerase Chain ◽

A Minor ◽

Flanking Regions ◽

Cdna Fragments

SummaryGlycoprotein CD36, also known as GPIIIb or GPIV, is a major platelet glycoprotein that bears the newly identified Naka alloantigen. The aim of this study was to clone platelet CD36 and investigate other forms of CD36-cDNA present in monocytes, endothelial and HEL cells. RNA from above mentioned cells were reverse transcribed (RT), using specific primers for CD36, and amplified by the polymerase chain reaction (PCR) technique. Sequencing the different amplified platelet derived cDNA fragments, spanning the whole coding and flanking regions, showed the near identity between platelet and CD36-placenta cDNA. Platelet CD36-cDNA cross-hybridized, in Southern blots, with RT-PCR amplified cDNA originating from monocytes, endothelial and HEL cells. However, monocytes showed a RT-PCR amplified cDNA fragment (561 bp) that was present in platelets and placenta but not on endothelial on HEL-cells. Northern blot analysis of platelet RNA hybridized with placenta CD36 indicated the presence of a major (1.95 kb) and a minor (0.95 kb) transcript. The 1.95 kb transcript was the only one observed on Northern blots of monocytes, endothelial and HEL cells. These results indicate that the structure of CD36 expressed in platelets is similar, with the exception of the 3’ flanking region, to that of placenta. Differences in apparent molecular weight between CD36 and CD36-like glycoproteins may be due to post-translational modifications.

Download Full-text