The WAVE2/Abi 1 complex differentially regulates megakaryocyte development and spreading: implications for platelet biogenesis and spreading machinery
The WAVE2/Abi 1 complex differentially regulates megakaryocyte development and spreading: implications for platelet biogenesis and spreading machinery
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DOI：
10.1182/blood-2007-04-085860
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发表时间：
2007-11-15
期刊：
影响因子：
20.3
通讯作者：
Nakauchi, Hirornitsu
中科院分区：
文献类型：
--
作者：
Eto, Koji;Nishikii, Hidekazu;Nakauchi, Hirornitsu
肌动蛋白聚合对于血小板生成、血小板粘附以及巨核细胞 (MK) 和血小板扩散至关重要。 Wiskott-Aldrich 综合征蛋白 (WASp) 同源物 WAVE 在 Rac 下游发挥作用，在板状伪足形成中发挥关键作用。虽然 MK 和血小板主要表达与 Abi1 相关的 WAVE1 和 WAVE2，但 WAVE 同工型的生理意义仍不清楚。我们生成了 WAVE2(-/-) 胚胎干 (ES) 细胞，因为 WAVE2 缺失小鼠在胚胎日 (E) 12.5 时死亡。我们发现，虽然 WAVE2(-/-) ES 细胞在 0139 基质上分化为未成熟的 MK，但它们的终末分化和血小板生成严重受损。即使在佛波醇 12-肉豆蔻酸酯 13-乙酸酯 (PMA) 共刺激下，WAVE2(-/-) MK 在纤维蛋白原上的外周板状伪足中也表现出缺陷，表明整合素 α(IIb)β(3) 介导的完全扩散需要 WAVE2。 Abi1 表达被小干扰 RNA (siRNA) 降低的 MK 在成熟和扩散方面与 WAVE2(-/-) MK 表现出惊人的相似性。有趣的是，IRSp53（一种优先与 WAVE2 结合的 Rac 效应子）的敲低会损害板状伪足的发育，但不会影响前血小板的产生。相比之下，WAVE1缺失小鼠体内的血栓形成和体外血小板在纤维蛋白原上的扩散是完整的。这些观察结果阐明了 WAVE2/Abi1 复合物在 MK 和血小板通过 Rac 和 IRSp53 介导的 α(IIB)beta(3) 介导的板状伪足中的不可或缺的作用，以及在独立于 Rac 和 IRSp53 的血小板生成中的不可或缺的作用。
Actin polymerization is crucial in thrombopoiesis, platelet adhesion, and megakaryocyte (MK) and platelet spreading. The Wiskott-Aldrich syndrome protein (WASp) homolog WAVE functions downstream of Rac and plays a pivotal role in lamellipodia formation. While MKs and platelets principally express WAVE1 and WAVE2, which are associated with Abi1, the physiologic significance of WAVE iso-forms remains undefined. We generated WAVE2(-/-) embryonic stem (ES) cells because WAVE2-null mice die by embryonic day (E) 12.5. We found that while WAVE2(-/-) ES cells differentiated into immature MKs on 0139 stroma, they were severely impaired in terminal differentiation and in platelet production. WAVE2(-/-) MKs exhibited a defect in peripheral lamellipodia on fibrinogen even with phorbol 12-myristate 13-acetate (PMA) costimulation, indicating a requirement of WAVE2 for integrin alpha(IIb)beta(3)-mediated full spreading. MKs in which expression of Abi1 was reduced by small interfering RNA (siRNA) exhibited striking similarity to WAVE2(-/-) MKs in maturation and spreading. Interestingly, the knockdown of IRSp53, a Rac effector that preferentially, binds to WAVE2, impaired the development of lamellipodia without affecting proplatelet production. In contrast, thrombopolesis in vivo and platelet spreading on fibrinogen in vitro were intact in WAVE1-null mice. These observations clarify indispensable roles for the WAVE2/Abi1 complex in alpha(IIB)beta(3)-mediated lamellipodia by MKs and platelets through Rac and IRSp53, and additionally in thrombopoiesis independent of Rac and IRSp53.