Pabón D, Jayo A, Xie J, Lastres P, González-Manchón C
Department of Molecular and Cellular Pathophysiology, Centro de Investigaciones Biológicas (CSIC), Madrid, Spain.
J Thromb Haemost. 2006 Oct;4(10):2238-47. doi: 10.1111/j.1538-7836.2006.02141.x.
The interaction of thrombin with platelet glycoprotein (GP) Ib-IX-V has been recently suggested to induce fibrin-dependent platelet aggregation associated with signaling events. The approaches used to avoid the protease-activated receptor (PAR) thrombin receptors in platelets have provided controversial conclusions regarding the precise mechanism and molecules involved in the response.
In the present study, we developed a cellular model to investigate the functional consequences following the binding of thrombin to GPIb-IX.
We used Chinese hamster ovary (CHO) cells stably expressing human alpha(IIb)beta(3) and/or GPIb-IX complexes (CHO-alpha(IIb)beta(3)-IbIX cells) to analyze the effect of thrombin on the binding of polymerizing fibrin by using fluorescein isothiocyanate-fibrinogen as precursor.
Thrombin induces, in a dose-dependent manner, the binding of polymerizing fibrin to CHO-alpha(IIb)beta(3)-IbIX cells. This response is not observed in cells expressing only one of the receptors, and it can be blocked by monoclonal antibodies against alpha(IIb)beta(3) and GPIbalpha. We show that the reaction is not due to simple cell trapping by the fibrin clot, and provide data supporting a role of a signaling pathway in which the 14-3-3zeta adaptor and calcium-calmodulin-dependent events are involved.
The present data support a significant role of GPIb-IX and alpha(IIb)beta(3) receptors in an alternative fibrin-mediated pathway of platelet activation induced by thrombin.
最近有研究表明，凝血酶与血小板糖蛋白（GP）Ib-IX-V的相互作用可诱导与信号事件相关的纤维蛋白依赖性血小板聚集。用于避免血小板中蛋白酶激活受体（PAR）凝血酶受体的方法，对于该反应所涉及的精确机制和分子得出了相互矛盾的结论。
在本研究中，我们建立了一个细胞模型，以研究凝血酶与糖蛋白Ib-IX结合后的功能后果。
我们使用稳定表达人α（IIb）β（3）和/或糖蛋白Ib-IX复合物的中国仓鼠卵巢（CHO）细胞（CHO-α（IIb）β（3）-IbIX细胞），以异硫氰酸荧光素 - 纤维蛋白原为前体，分析凝血酶对聚合纤维蛋白结合的影响。
凝血酶以剂量依赖性方式诱导聚合纤维蛋白与CHO-α（IIb）β（3）-IbIX细胞结合。在仅表达其中一种受体的细胞中未观察到这种反应，并且它可以被抗α（IIb）β（3）和糖蛋白Ibα的单克隆抗体阻断。我们表明该反应不是由于纤维蛋白凝块简单地捕获细胞，并提供数据支持涉及14-3-3ζ衔接蛋白和钙 - 钙调蛋白依赖性事件的信号通路的作用。
目前的数据支持糖蛋白Ib-IX和α（IIb）β（3）受体在凝血酶诱导的血小板激活的另一种纤维蛋白介导途径中起重要作用。
