Structural and therapeutic insights from the species specificity and in vivo antithrombotic activity of a novel alphaIIb-specific alphaIIbbeta3 antagonist

Blood. 2009 Jul 2;114(1):195-201. doi: 10.1182/blood-2008-08-169243. Epub 2009 May 4.


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.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Blood Platelets / drug effects*
  • Blood Platelets / metabolism
  • Carotid Artery Injuries / blood
  • Carotid Artery Injuries / drug therapy
  • Fibrinogen / metabolism
  • Fibrinolytic Agents / administration & dosage
  • Fibrinolytic Agents / chemistry
  • Fibrinolytic Agents / pharmacology*
  • Humans
  • In Vitro Techniques
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Mice, Transgenic
  • Molecular Sequence Data
  • Molecular Structure
  • Muscle, Skeletal / blood supply
  • Platelet Aggregation / drug effects
  • Platelet Glycoprotein GPIIb-IIIa Complex / antagonists & inhibitors*
  • Platelet Glycoprotein GPIIb-IIIa Complex / chemistry
  • Platelet Glycoprotein GPIIb-IIIa Complex / genetics
  • Platelet Glycoprotein GPIIb-IIIa Complex / metabolism
  • Platelet Membrane Glycoprotein IIb / blood*
  • Platelet Membrane Glycoprotein IIb / chemistry
  • Platelet Membrane Glycoprotein IIb / genetics
  • Rats
  • Recombinant Fusion Proteins / antagonists & inhibitors
  • Recombinant Fusion Proteins / genetics
  • Sequence Homology, Amino Acid
  • Species Specificity
  • Thrombosis / prevention & control


  • Fibrinolytic Agents
  • Platelet Glycoprotein GPIIb-IIIa Complex
  • Platelet Membrane Glycoprotein IIb
  • Recombinant Fusion Proteins
  • Fibrinogen