U. 770 INSERM, Hôpital de Bicêtre, France.
Thromb Res. 2010 Apr;125 Suppl 1:S46-8. doi: 10.1016/j.thromres.2010.01.036. Epub 2010 Feb 12.
The platelet procoagulant response consists of providing a catalytic surface where vitamin K-dependent clotting factors can interact with cofactors to form the characteristic enzyme complexes of the cascade culminating in the generation of sufficient thrombin for effective hemostasis. The essential element allowing such a local concentration is the anionic aminophospholipid phosphatidylserine, sequestered in the inner leaflet of the plasma membrane of resting cells but swiftly translocated to the outer leaflet after stimulation. Phosphatidylserine egress is followed by the shedding of membrane fragments, the so-called microparticles or microvesicles, also endowed with procoagulant properties more particularly when they harbor tissue factor, the major initiator of blood coagulation reactions. Furthermore, because microparticles hijack a number of membrane and cytoplasmic components from the cells they derive, they can elicit various responses in proximal or remote cells they interact with and can therefore be viewed as intercellular "macromessengers". Although several regulatory mechanisms have been proposed, the main actors responsible for the whole process of phosphatidylserine transmembrane redistribution and subsequent microparticle release remain to be identified.
血小板促凝反应包括提供一个催化表面，使维生素 K 依赖性凝血因子能够与辅助因子相互作用，形成级联反应的特征酶复合物，最终产生足够的凝血酶以实现有效的止血。允许这种局部浓度的基本要素是阴离子氨基磷脂磷脂酰丝氨酸，它被隔离在静止细胞的质膜内层，但在刺激后迅速易位到质膜外层。磷脂酰丝氨酸外排后，会伴随着膜片段的脱落，即所谓的微粒体或微囊泡，当它们含有组织因子时，也具有促凝特性，特别是当它们含有组织因子时，组织因子是血液凝固反应的主要启动子。此外，由于微粒体从其来源的细胞中劫持了许多膜和细胞质成分，因此它们可以在与之相互作用的近端或远端细胞中引发各种反应，因此可以将其视为细胞间“大分子信使”。尽管已经提出了几种调节机制，但负责磷脂酰丝氨酸跨膜重新分布和随后微粒体释放的整个过程的主要参与者仍有待确定。
