Identification of a novel, actin-rich structure, the actin nodule, in the early stages of platelet spreading
Identification of a novel, actin-rich structure, the actin nodule, in the early stages of platelet spreading
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DOI：
10.1111/j.1538-7836.2008.03141.x
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发表时间：
2008-11-01
影响因子：
10.4
通讯作者：
Watson, S. P.
中科院分区：
文献类型：
--
作者：
Calaminus, S. D. J.;Thomas, S.;Watson, S. P.
背景：在血小板铺展过程中，肌动蛋白细胞骨架发生显著变化，形成丝状足、片状脂膜和应力纤维。在目前的研究中，我们报告了一种新的富含肌动蛋白的结构，称为肌动蛋白结节，它出现在片状脂溢症和应力纤维形成之前。方法：用人血小板和小鼠GFP-肌动蛋白血小板，用实时和终点DIC、荧光显微镜和电子显微镜(EM)监测血小板扩散。结果：在粘连和扩散的早期阶段，我们发现了一种新的小的肌动蛋白结构，肌动蛋白结节，我们推测它是片状脂膜和应力纤维的先驱。结节形成与Rho激酶和肌球蛋白II活性呈负相关，不依赖于PI3-激酶，但依赖于Src激酶活性。肌动蛋白结节含有多种蛋白质，包括Arp2/3、Fyn、Rac、β1和β3整合素，但不含Src。EM分析表明，肌动蛋白细丝从结节向各个方向延伸。肌动蛋白结节存在于多种基质上，包括纤维蛋白原、层粘连蛋白和VWF+Botrocetin。结论：这项工作发现了一种新的血小板肌动蛋白结构，我们认为它是片状脂膜和应力纤维的前体，并起到推动血小板扩散的作用。
Background: During platelet spreading, the actin cytoskeleton undergoes marked changes, forming filopodia, lamellipodia and stress fibres. In the present study, we report the identification of a novel actin-rich structure, termed an actin nodule, which appears prior to lamellipodia and stress fibre formation. Methods: Platelet spreading was monitored using human platelets and mouse GFP-actin platelets using real-time and end-point DIC, and fluorescent and electron microscopy (EM). Results: We identified a small, novel actin structure, the actin nodule, in the early stages of adhesion and spreading, which we hypothesize to be a precursor of lamellipodia and stress fibres. Nodule formation shows an inverse correlation to Rho kinase and myosin-II activity, is independent of PI3-kinase, but dependent on Src kinase activity. Actin nodules contain multiple proteins, including Arp2/3, Fyn, Rac, and beta 1- and beta 3- integrins, but not Src. EM analysis revealed that actin filaments extend in all directions from the nodules. Actin nodules are present on multiple matrices, including fibrinogen, laminin and VWF + botrocetin. Conclusion: This work identifies a novel platelet actin structure, which we propose is a precursor to both lamellipodia and stress fibres and acts to drive platelet spreading.