Berny Michelle A, White Tara C, Tucker Erik I, Bush-Pelc Leslie A, Di Cera Enrico, Gruber András, McCarty Owen J T
Department of Biomedical Engineering, Oregon Health & Science University, 3303 SW Bond Ave, Portland, OR 97239, USA.
Arterioscler Thromb Vasc Biol. 2008 Feb;28(2):329-34. doi: 10.1161/ATVBAHA.107.156273. Epub 2007 Oct 25.
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.
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.
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.
含有色氨酸215丙氨酸和谷氨酸217丙氨酸突变(WE)的凝血酶可选择性激活蛋白C,并在灵长类动物中具有强大的抗血栓作用。本研究的目的是阐明在静态和剪切条件下WE凝血酶与血小板直接相互作用的分子机制。
在静态条件下,纯化的血小板能结合并铺展在固定化的野生型凝血酶上,但不能结合在WE凝血酶上。在剪切流条件下的PPACK抗凝血液中,血小板能在野生型和WE凝血酶上拴系和滚动,并且这些相互作用可被糖蛋白Ib(GPIb)阻断抗体的存在所消除。在存在WE凝血酶的情况下,血小板在胶原蛋白上的沉积被阻断,但野生型凝血酶或凝血酶原则不会。WE凝血酶还可消除剪切流条件下全血中血小板在固定化血管性血友病因子上的拴系和滚动。
这些观察结果表明,凝血酶突变体WE虽然不激活血小板,但仍保留通过GPIb与血小板相互作用的能力,并在剪切力作用下抑制GPIb依赖性与血管性血友病因子-胶原蛋白的结合。