Department of Pathology, University of Cambridge, Cambridge CB2 1QP, United Kingdom.
Proc Natl Acad Sci U S A. 2013 Oct 15;110(42):16880-5. doi: 10.1073/pnas.1311680110. Epub 2013 Oct 1.
ADP ribosylation factor (Arf) 6 anchors to the plasma membrane, where it coordinates membrane trafficking and cytoskeleton remodelling, but how it assembles actin filaments is unknown. By reconstituting membrane-associated actin assembly mediated by the WASP family veroprolin homolog (WAVE) regulatory complex (WRC), we recapitulated an Arf6-driven actin polymerization pathway. We show that Arf6 is divergent from other Arf members, as it was incapable of directly recruiting WRC. We demonstrate that Arf6 triggers actin assembly at the membrane indirectly by recruiting the Arf guanine nucleotide exchange factor (GEF) ARNO that activates Arf1 to enable WRC-dependent actin assembly. The pathogen Salmonella usurped Arf6 for host cell invasion by recruiting its canonical GEFs EFA6 and BRAG2. Arf6 and its GEFs facilitated membrane ruffling and pathogen invasion via ARNO, and triggered actin assembly by generating an Arf1-WRC signaling hub at the membrane in vitro and in cells. This study reconstitutes Arf6-dependent actin assembly to reveal a mechanism by which related Arf GTPases orchestrate distinct steps in the WRC cytoskeleton remodelling pathway.
ADP 核糖基化因子 (Arf) 6 锚定在质膜上，在那里它协调膜运输和细胞骨架重塑，但它如何组装肌动蛋白丝尚不清楚。通过重新组装由 W iskott–Aldrich 综合征蛋白家族 veroprolin 同源物 (WAVE) 调节复合物 (WRC) 介导的膜相关肌动蛋白组装，我们再现了 Arf6 驱动的肌动蛋白聚合途径。我们表明，Arf6 与其他 Arf 成员不同，因为它无法直接招募 WRC。我们证明 Arf6 通过招募 Arf 鸟嘌呤核苷酸交换因子 (GEF) ARNO 间接触发膜上的肌动蛋白组装，从而激活 Arf1 以实现 WRC 依赖的肌动蛋白组装。病原体沙门氏菌通过招募其规范的 GEFs EFA6 和 BRAG2 来入侵宿主细胞，从而利用 Arf6。Arf6 及其 GEFs 通过 ARNO 促进膜皱襞和病原体入侵，并通过在体外和细胞中在膜上生成 Arf1-WRC 信号枢纽来触发肌动蛋白组装。本研究重建了 Arf6 依赖性肌动蛋白组装，揭示了相关 Arf GTPases 协调 WRC 细胞骨架重塑途径中不同步骤的机制。
