Gomez Timothy S, Billadeau Daniel D
Department of Immunology, Division of Oncology Research and Schulze Center for Novel Therapeutics, College of Medicine, Mayo Clinic, Rochester, MN 55905, USA.
Dev Cell. 2009 Nov;17(5):699-711. doi: 10.1016/j.devcel.2009.09.009.
The Arp2/3 complex regulates endocytosis, sorting, and trafficking, yet the Arp2/3-stimulating factors orchestrating these distinct events remain ill defined. WASH (Wiskott-Aldrich Syndrome Protein and SCAR Homolog) is an Arp2/3 activator with unknown function that was duplicated during primate evolution. We demonstrate that WASH associates with tubulin and localizes to early endosomal subdomains, which are enriched in Arp2/3, F-actin, and retromer components. Although WASH localized with activated receptors, it was not essential for endocytosis. However, WASH did regulate retromer-mediated retrograde CI-MPR trafficking, which required its association with endosomes, Arp2/3-directed F-actin regulation, and tubulin interaction. Moreover, WASH exists in a multiprotein complex containing FAM21, which links WASH to endosomes and is required for WASH-dependent retromer-mediated sorting. Significantly, without WASH, retromer tubulation was exaggerated, supporting a model wherein WASH links retromer-mediated cargo containing tubules to microtubules for Golgi-directed trafficking and generates F-actin-driven force for tubule scission.
Arp2/3复合物调控内吞作用、分选和运输，然而协调这些不同事件的Arp2/3刺激因子仍未明确界定。WASH（威斯科特-奥尔德里奇综合征蛋白和SCAR同源物）是一种功能未知的Arp2/3激活剂，在灵长类动物进化过程中发生了复制。我们证明WASH与微管蛋白结合并定位于富含Arp2/3、F-肌动蛋白和回收体成分的早期内体亚结构域。尽管WASH与激活的受体共定位，但它对于内吞作用并非必不可少。然而，WASH确实调节回收体介导的逆行CI-MPR运输，这需要它与内体结合、Arp2/3导向的F-肌动蛋白调节以及微管蛋白相互作用。此外，WASH存在于一个包含FAM21的多蛋白复合物中，FAM21将WASH连接到内体，是WASH依赖的回收体介导的分选所必需的。重要的是，没有WASH，回收体微管形成会过度，这支持了一种模型，即WASH将回收体介导的含货物微管连接到微管以进行高尔基体导向的运输，并产生F-肌动蛋白驱动的力用于微管断裂。
