OBJECTIVE - Thrombin containing the mutations Trp215Ala and Glu217Ala (WE) selectively activates protein C and has potent antithrombotic effects in primates. The aim of this study was to delineate the molecular mechanism of direct WE-platelet interactions under static and shear conditions. METHODS AND RESULTS - Purified platelets under static conditions bound and spread on immobilized wild-type but not WE thrombin. In PPACK-anticoagulated blood under shear flow conditions, platelets tethered and rolled on both wild-type and WE thrombin, and these interactions were abrogated by the presence of a glycoprotein Ib (GPIb)-blocking antibody. Platelet deposition on collagen was blocked in the presence of WE, but not wild-type thrombin or prothrombin. WE also abrogated platelet tethering and rolling on immobilized von Willebrand factor in whole blood under shear flow. CONCLUSIONS - These observations demonstrate that the thrombin mutant WE, while not activating platelets, retains the ability to interact with platelets through GPIb, and inhibits GPIb-dependent binding to von Willebrand factor-collagen under shear.
|Original language||English (US)|
|Number of pages||6|
|Journal||Arteriosclerosis, thrombosis, and vascular biology|
|State||Published - Feb 2008|
- Von Willebrand factor
ASJC Scopus subject areas
- Cardiology and Cardiovascular Medicine