Protease-activated receptor 1 is the primary mediator of thrombin-stimulated platelet procoagulant activity
Protease-activated receptor 1 is the primary mediator of thrombin-stimulated platelet procoagulant activity
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DOI：
10.1073/pnas.96.20.11189
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发表时间：
1999-09-28
影响因子：
11.1
通讯作者：
Davie, EW
中科院分区：
文献类型：
--
作者：
Andersen, H;Greenberg, DL;Davie, EW
凝血酶对人血小板的激活主要由蛋白酶激活受体（PAR）介导。PAR 1和PAR 4存在于人血小板上，并分别被六肽SFLLRN和GYPGQV激活。为了进一步表征PAR 1和PAR 4参与血小板活化，已经检查了SFLLRN或GYPGQV产生膜联蛋白V结合血小板表面上新暴露的磷脂并产生促凝血活性的能力。磷脂酰丝氨酸和磷脂酰乙醇胺在血小板上的暴露，如通过膜联蛋白V结合的增加所确定的，被SFLLRN、凝血酶和胶原强烈刺激，但仅在较小程度上被GYPGQV刺激。在用因子VIIa、可溶性组织因子和钙启动的凝血测定中，在没有血小板的情况下的凝血时间>5分钟。在存在未刺激的血小板的情况下，凝固时间为200 +/-20秒。在存在用SFLLRN或胶原活化的血小板的情况下，凝血时间降低至100 +/-10秒。当将受刺激的血小板与未受刺激的血小板进行比较并且将活化的血小板用作参照时，凝血时间的这种缩短相当于凝血活性的约5倍增加。这些结果表明凝血酶通过PAR 1在血小板中引发非常强的应答，导致支持血液凝血的阴离子磷脂的暴露。然而，由PAR 4介导的反应仅限于血小板聚集，并且类似于由较弱的激动剂如ADP或肾上腺素在血小板中引发的反应。
The activation of human platelets by thrombin is mediated primarily by protease-activated receptors (PARs). PAR1 and PAR4 are present on human platelets and are activated by the hexapeptides SFLLRN and GYPGQV, respectively. To further characterize the involvement of PAR1 and PAR4 in platelet activation, the ability of SFLLRN or GYPGQV to generate annexin V binding to newly exposed phospholipids on the platelet surface and generate procoagulant activity has been examined. Exposure of phosphatidylserine and phosphatidylethanolamine on platelets, as determined by an increase in annexin V binding, was strongly stimulated by SFLLRN, thrombin, and collagen, but only to a minor extent by GYPGQV, In a clotting assay initiated with factor VIIa, soluble tissue factor, and calcium, the clotting time in the absence of platelets was >5 min. In the presence of unstimulated platelets, the clotting time was 200 +/- 20 sec. In the presence of platelets activated with SFLLRN or collagen, the clotting time decreased to 100 +/- 10 sec. This shortening of the clotting time is equivalent to about a 5-fold increase in coagulant activity when stimulated platelets are compared with unstimulated platelets and activated platelets are used as a reference, These results indicate that thrombin initiates a very strong response in platelets through PAR1, leading to exposure of anionic phospholipids that support blood clotting. The response mediated by PAR4, however, was limited to platelet aggregation and similar to that triggered in platelets by weaker agonists such as ADP or epinephrine.