Department of Biology, Brandeis University, Waltham, MA
Centre de Recherche en Cancérologie de Marseille, Institut National de la Santé et de la Recherche Médicale, Institut Paoli-Calmettes, Aix-Marseille Université, Centre National de la Recherche Scientifique, Marseille, France.
J Cell Biol. 2019 Oct 7;218(10):3415-3435. doi: 10.1083/jcb.201904165. Epub 2019 Aug 30.
Focal adhesion (FA) turnover depends on microtubules and actin. Microtubule ends are captured at FAs, where they induce rapid FA disassembly. However, actin's roles are less clear. Here, we use polarization-resolved microscopy, FRAP, live cell imaging, and a mutant of Adenomatous polyposis coli (APC-m4) defective in actin nucleation to investigate the role of actin assembly in FA turnover. We show that APC-mediated actin assembly is critical for maintaining normal F-actin levels, organization, and dynamics at FAs, along with organization of FA components. In WT cells, microtubules are captured repeatedly at FAs as they mature, but once a FA reaches peak maturity, the next microtubule capture event leads to delivery of an autophagosome, triggering FA disassembly. In APC-m4 cells, microtubule capture frequency and duration are altered, and there are long delays between autophagosome delivery and FA disassembly. Thus, APC-mediated actin assembly is required for normal feedback between microtubules and FAs, and maintaining FAs in a state "primed" for microtubule-induced turnover.
焦点黏附（FA）周转率取决于微管和肌动蛋白。微管末端在 FA 处被捕获，在那里它们诱导快速 FA 解体。然而，肌动蛋白的作用不太清楚。在这里，我们使用极化分辨显微镜、FRAP、活细胞成像和一种突变的腺瘤性结肠息肉病（APC-m4），该突变在肌动蛋白成核中缺陷，以研究肌动蛋白组装在 FA 周转率中的作用。我们表明，APC 介导的肌动蛋白组装对于维持 FA 处的正常 F-肌动蛋白水平、组织和动态以及 FA 成分的组织至关重要。在 WT 细胞中，微管在成熟过程中反复在 FA 处被捕获，但一旦 FA 达到峰值成熟，下一个微管捕获事件会导致自噬体的传递，从而引发 FA 解体。在 APC-m4 细胞中，微管捕获的频率和持续时间发生改变，并且自噬体传递和 FA 解体之间存在很长的延迟。因此，APC 介导的肌动蛋白组装对于微管和 FA 之间的正常反馈以及将 FA 维持在“准备”微管诱导的周转率的状态是必需的。
