Inhibition of cytoskeletal assembly by cytochalasin B prevents signaling through tyrosine phosphorylation and secretion triggered by collagen but not by thrombin
Inhibition of cytoskeletal assembly by cytochalasin B prevents signaling through tyrosine phosphorylation and secretion triggered by collagen but not by thrombin
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DOI：
10.1016/s0002-9440(10)64376-3
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发表时间：
2002-01-01
影响因子：
6
通讯作者：
Ordinas, A
中科院分区：
文献类型：
--
作者：
Díaz-Ricart, M;Arderiu, G;Ordinas, A
血小板的激活导致细胞骨架的组装，而细胞骨架组装负责血小板的运动和内部收缩。我们已经评估了细胞骨架在两种强激动剂--胶原和凝血酶--激活血小板中的作用。在细胞松弛素B存在和不存在的情况下，通过测量细胞骨架组装、激活依赖标志物的外部化和促凝血活性的表达以及蛋白质酪氨酸磷酸化的变化来评估激活情况。胶原和凝血酶激活血小板后，细胞形态发生变化，CD62P、CD63、糖蛋白IV的表达增加，膜联蛋白V与血小板的结合增加。此外，两种激活剂都能诱导肌动蛋白聚合，增加与其他收缩蛋白的结合，并促进多种蛋白的酪氨酸磷酸化，其中一些蛋白与细胞骨架有关。当使用胶原作为激活剂时，细胞松弛素B的存在阻断了先前的事件，但仍发生了膜联蛋白V的结合。相反，细胞松弛素B的存在并不能完全阻止血小板对凝血酶的反应。因此，胶原蛋白的激活需要一个功能正常的细胞骨架，通过酪氨酸磷酸化和分泌来触发信号。凝血酶的情况并非如此，它能够在细胞骨架组装的强大抑制剂存在的情况下激活信号机制。此外，即使在血小板运动被抑制的情况下，血小板表面促凝血剂的表达仍然存在。
Activation of platelets leads to cytoskeletal assembly that is responsible for platelet motility and internal contraction. We have evaluated the involvement of the cytoskeleton in platelet activation by two strong agonists, collagen and thrombin. Activation was assessed by measuring changes in cytoskeletal assembly, externalization of activation-dependent markers and expression of procoagulant activity, and tyrosine phosphorylation of proteins, in both the absence and the presence of cytochalasin B. Activation of platelets with collagen and thrombin induced morphological changes and increased the expression of CD62P, CD63, glycoprotein IV, and binding of annexin V to platelets. Moreover, both activating agents induced actin polymerization, increased the association of other contractile proteins, and promoted tyrosine phosphorylation of multiple proteins, some of which were associated with the cytoskeleton. The presence of cytochalasin B blocked the previous events when collagen was used as the activating agent, although binding of annexin V still occurred. in contrast, platelet response to thrombin was not completely prevented by the presence of cytochalasin B. Thus, activation by collagen requires a functional cytoskeleton to trigger signaling through tyrosine phosphorylation and secretion. This is not the case for thrombin, which is capable of activating signaling mechanisms in the presence of strong inhibitors of cytoskeletal assembly. Moreover, the expression of a procoagulant surface in platelets still occurs even when platelet motility has been inhibited.