Identification of a small molecule that modulates platelet glycoprotein Ib-von Willebrand factor interaction.
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 interfering with the VWF-GPIbα binding. After determination of putative small molecule binding pockets on the surface of VWF-A1 and GPIbα 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-GPIbα complex formation, by which we identified a compound that surprisingly stimulated the VWF-GPIbα 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 GPIbα could be confirmed by saturation transfer difference NMR spectroscopy. We thus clearly identified a small molecule that modulates VWF-GPIbα 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.
Laboratory for Thrombosis Research, Katholieke Universiteit Leuven, Kortrijk, Belgium.
Katleen
K
Broos
Mieke
M
Trekels
Rani Alphonsa
RA
Jose
Jonas
J
Demeulemeester
Aline
A
Vandenbulcke
Nele
N
Vandeputte
Tom
T
Venken
Brecht
B
Egle
Wim M
WM
De Borggraeve
Hans
H
Deckmyn
Marc
M
De Maeyer
D001665:Binding Sites; D001792:Blood Platelets / Q000187:drug effects / Q000378:metabolism; D004353:Drug Evaluation, Preclinical; D006801:Humans; D007700:Kinetics; D015394:Molecular Structure; D010973:Platelet Adhesiveness / Q000187:drug effects; D019038:Platelet Glycoprotein GPIb-IX Complex / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding / Q000187:drug effects*; D017434:Protein Structure, Tertiary; D054852:Small Molecule Libraries / Q000737:chemistry / Q000494:pharmacology*; D013329:Structure-Activity Relationship; D014841:von Willebrand Factor / Q000737:chemistry / Q000378:metabolism*
D019038:Platelet Glycoprotein GPIb-IX Complex; D054852:Small Molecule Libraries; D014841:von Willebrand Factor