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Identification of a small molecule that modulates platelet glycoprotein Ib-von Willebrand factor interaction.

ABSTRACT: The von Willebrand factor (VWF) A1-glycoprotein (GP) Ib? interaction is of major importance during thrombosis mainly at sites of high shear stress. Inhibitors of this interaction prevent platelet-dependent thrombus formation in vivo, without major bleeding complications. However, the size and/or protein nature of the inhibitors currently in development limit oral bioavailability and clinical development. We therefore aimed to search for a small molecule protein-protein interaction inhibitor interfering with the VWF-GPIb? binding. After determination of putative small molecule binding pockets on the surface of VWF-A1 and GPIb? using site-finding algorithms and molecular dynamics, high throughput molecular docking was performed on both binding partners. A selection of compounds showing good in silico docking scores into the predicted pockets was retained for testing their in vitro effect on VWF-GPIb? complex formation, by which we identified a compound that surprisingly stimulated the VWF-GPIb? binding in a ristocetin cofactor ELISA and increased platelet adhesion in whole blood to collagen under arterial shear rate but in contrast inhibited ristocetin-induced platelet aggregation. The selected compound adhering to the predicted binding partner GPIb? could be confirmed by saturation transfer difference NMR spectroscopy. We thus clearly identified a small molecule that modulates VWF-GPIb? binding and that will now serve as a starting point for further studies and chemical modifications to fully characterize the interaction and to manipulate specific activity of the compound.

SUBMITTER: Broos K

PROVIDER: S-EPMC3308782 | biostudies-literature | 2012 Mar

REPOSITORIES: biostudies-literature

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Identification of a small molecule that modulates platelet glycoprotein Ib-von Willebrand factor interaction.

Broos Katleen K Trekels Mieke M Jose Rani Alphonsa RA Demeulemeester Jonas J Vandenbulcke Aline A Vandeputte Nele N Venken Tom T Egle Brecht B De Borggraeve Wim M WM Deckmyn Hans H De Maeyer Marc M

The Journal of biological chemistry 20120109 12

The von Willebrand factor (VWF) A1-glycoprotein (GP) Ibα interaction is of major importance during thrombosis mainly at sites of high shear stress. Inhibitors of this interaction prevent platelet-dependent thrombus formation in vivo, without major bleeding complications. However, the size and/or protein nature of the inhibitors currently in development limit oral bioavailability and clinical development. We therefore aimed to search for a small molecule protein-protein interaction inhibitor inte ...[more]

PMID: 22232560

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Project description:Essentials von Willebrand factor (VWF) is synthesized in endothelial cells and platelet precursors. Type 3 patients with Pro2808Leufs*24 have lower bleeding scores than other type 3s. The Pro2808Leufs*24 variant was examined in patient platelets and endothelial cells. Type 3s with this variant contain releaseable VWF, possibly reducing bleeding. SUMMARY:Background A novel variant, p.Pro2808Leufs*24, in the von Willebrand factor (VWF) gene was previously identified in the Canadian von Willebrand disease (VWD) patient population. Clinical observations of type 3 VWD patients with this variant indicate a milder bleeding phenotype compared with other type 3 patients. Objective To assess the effect of the Pro2808Leufs*24 variant on the molecular pathogenesis of VWD and correlate this with the phenotype observed in patients. Patients/Methods Phenotypic data from individuals in the Canadian type 3 VWD study were analyzed. VWF expression in platelets and plasma was assessed via immunoblotting. Cellular expression of VWF in platelets and blood outgrowth endothelial cells (BOEC) was examined via immunofluorescence microscopy and biochemical analysis in a type 3 index case and family member with Pro2808Leufs*24. Results Twenty-six individuals with the Pro2808Leufs*24 variant (16 type 3 VWD homozygous or compound heterozygous and 10 heterozygous family members) were studied. Bleeding scores were lower in type 3 patients with Pro2808Leufs*24 compared with type 3 patients with other variants, confirming a milder bleeding phenotype. Immunoblotting of platelet lysates detected VWF in the platelets of type 3 patients with Pro2808Leufs*24. Examination of an index case detected VWF within platelets via immunofluorescence microscopy, and in vitro experiments showed that this VWF was released upon platelet activation. Patient BOECs showed decreased VWF synthesis and secretion, although some VWF-containing granules were observed. Conclusion Type 3 VWD patients with the Pro2808Leufs*24 have bioavailable platelet-derived VWF that may produce a milder bleeding phenotype than other type 3s.

Dataset Information

Identification of a small molecule that modulates platelet glycoprotein Ib-von Willebrand factor interaction.

Publications

Identification of a small molecule that modulates platelet glycoprotein Ib-von Willebrand factor interaction.

Similar Datasets

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