Rogers Stephen L, Wiedemann Ursula, Stuurman Nico, Vale Ronald D
Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA 94107, USA.
J Cell Biol. 2003 Sep 15;162(6):1079-88. doi: 10.1083/jcb.200303023.
Cell migration occurs through the protrusion of the actin-enriched lamella. Here, we investigated the effects of RNAi depletion of approximately 90 proteins implicated in actin function on lamella formation in Drosophila S2 cells. Similar to in vitro reconstitution studies of actin-based Listeria movement, we find that lamellae formation requires a relatively small set of proteins that participate in actin nucleation (Arp2/3 and SCAR), barbed end capping (capping protein), filament depolymerization (cofilin and Aip1), and actin monomer binding (profilin and cyclase-associated protein). Lamellae are initiated by parallel and partially redundant signaling pathways involving Rac GTPases and the adaptor protein Nck, which stimulate SCAR, an Arp2/3 activator. We also show that RNAi of three proteins (kette, Abi, and Sra-1) known to copurify with and inhibit SCAR in vitro leads to SCAR degradation, revealing a novel function of this protein complex in SCAR stability. Our results have identified an essential set of proteins involved in actin dynamics during lamella formation in Drosophila S2 cells.
细胞迁移通过富含肌动蛋白的片状伪足的突出而发生。在此，我们研究了约90种与肌动蛋白功能相关的蛋白质的RNA干扰缺失对果蝇S2细胞中片状伪足形成的影响。与基于肌动蛋白的李斯特菌运动的体外重组研究相似，我们发现片状伪足的形成需要一组相对较少的蛋白质参与肌动蛋白成核（Arp2/3和SCAR）、带刺末端封端（封端蛋白）、丝状体解聚（丝切蛋白和Aip1）以及肌动蛋白单体结合（肌动蛋白结合蛋白和环化酶相关蛋白）。片状伪足由涉及Rac GTP酶和衔接蛋白Nck的平行且部分冗余的信号通路启动，这些通路刺激Arp2/3激活剂SCAR。我们还表明，在体外已知与SCAR共纯化并抑制SCAR的三种蛋白质（kette、Abi和Sra-1）的RNA干扰会导致SCAR降解，揭示了这种蛋白质复合物在SCAR稳定性方面的新功能。我们的结果确定了果蝇S2细胞片状伪足形成过程中参与肌动蛋白动力学的一组必需蛋白质。
