Structural and therapeutic insights from the species specificity and in vivo antithrombotic activity of a novel alphaIIb-specific alphaIIbbeta3 antagonist.
We previously reported on a novel compound (Compound 1; RUC-1) identified by high-throughput screening that inhibits human alphaIIbbeta3. RUC-1 did not inhibit alphaVbeta3, suggesting that it interacts with alphaIIb, and flexible ligand/rigid protein molecular docking studies supported this speculation. We have now studied RUC-1's effects on murine and rat platelets, which are less sensitive than human to inhibition by Arg-Gly-Asp (RGD) peptides due to differences in the alphaIIb sequences contributing to the binding pocket. We found that RUC-1 was much less potent in inhibiting aggregation of murine and rat platelets. Moreover, RUC-1 potently inhibited fibrinogen binding to murine platelets expressing a hybrid alphaIIbbeta3 receptor composed of human alphaIIb and murine beta3, but not a hybrid receptor composed of murine alphaIIb and human beta3. Molecular docking studies of RUC-1 were consistent with the functional data. In vivo studies of RUC-1 administered intraperitoneally at a dose of 26.5 mg/kg demonstrated antithrombotic effects in both ferric chloride carotid artery and laser-induced microvascular injury models in mice with hybrid halphaIIb/mbeta3 receptors. Collectively, these data support RUC-1's specificity for alphaIIb, provide new insights into the alphaIIb binding pocket, and establish RUC-1's antithrombotic effects in vivo.
Laboratory of Blood and Vascular Biology, Rockefeller University, New York, NY 10065, USA.
Robert
R
Blue
M Anna
MA
Kowalska
Jessica
J
Hirsch
Marta
M
Murcia
Christin A
CA
Janczak
Amanda
A
Harrington
Marketa
M
Jirouskova
Jihong
J
Li
Rudy
R
Fuentes
Michael A
MA
Thornton
Marta
M
Filizola
Mortimer
M
Poncz
Barry S
BS
Coller
D000595:Amino Acid Sequence; D000818:Animals; D001792:Blood Platelets / Q000187:drug effects* / Q000378:metabolism; D020212:Carotid Artery Injuries / Q000097:blood / Q000188:drug therapy; D005340:Fibrinogen / Q000378:metabolism; D005343:Fibrinolytic Agents / Q000008:administration & dosage / Q000737:chemistry / Q000494:pharmacology*; D006801:Humans; D066298:In Vitro Techniques; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008822:Mice, Transgenic; D008969:Molecular Sequence Data; D015394:Molecular Structure; D018482:Muscle, Skeletal / Q000098:blood supply; D010974:Platelet Aggregation / Q000187:drug effects; D019039:Platelet Glycoprotein GPIIb-IIIa Complex / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D040201:Platelet Membrane Glycoprotein IIb / Q000097:blood* / Q000737:chemistry / Q000235:genetics; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000037:antagonists & inhibitors / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity; D013927:Thrombosis / Q000517:prevention & control
D005343:Fibrinolytic Agents; D019039:Platelet Glycoprotein GPIIb-IIIa Complex; D040201:Platelet Membrane Glycoprotein IIb; D011993:Recombinant Fusion Proteins; D005340:Fibrinogen