Actin retrograde flow actively aligns and orients ligand-engaged integrins in focal adhesions
Actin retrograde flow actively aligns and orients ligand-engaged integrins in focal adhesions
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DOI：
10.1073/pnas.1701136114
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发表时间：
2017-10-03
影响因子：
11.1
通讯作者：
Waterman, Clare M.
中科院分区：
文献类型：
--
作者：
Swaminathan, Vinay;Kalappurakkal, Joseph Mathew;Waterman, Clare M.
整合素是跨膜受体，激活后结合细胞外配体并将其连接到肌动蛋白丝 (F-肌动蛋白) 细胞骨架，以介导细胞粘附和迁移。假设迁移细胞中由聚合或收缩驱动的 F-肌动蛋白从细胞前缘的“逆行流”产生的细胞骨架力可介导配体结合的整合素激活。这预测这些力应该在前缘对齐和定向激活的、配体结合的整联蛋白。在这里，成纤维细胞中 GFP-α V beta 3 整合素的偏振敏感荧光显微镜显示，整合素在粘着斑 (FA) 内以特定方向共排列，其方式依赖于结合固定配体和踝蛋白介导的与 F-肌动蛋白细胞骨架的连接。这些发现与 Rosetta 模型一起表明 FA 中的整合素是相互排列的，并且可能因细胞骨架力而高度倾斜。因此，F-肌动蛋白细胞骨架在 FA 中塑造了一个各向异性的分子支架，这一特征可能是迁移细胞感知定向细胞外信号能力的基础。
Integrins are transmembrane receptors that, upon activation, bind extracellular ligands and link them to the actin filament (F-actin) cytoskeleton to mediate cell adhesion and migration. Cytoskeletal forces in migrating cells generated by polymerization-or contractility-driven "retrograde flow" of F-actin from the cell leading edge have been hypothesized to mediate integrin activation for ligand binding. This predicts that these forces should align and orient activated, ligand-bound integrins at the leading edge. Here, polarization-sensitive fluorescence microscopy of GFP-alpha V beta 3 integrins in fibroblasts shows that integrins are coaligned in a specific orientation within focal adhesions (FAs) in a manner dependent on binding immobilized ligand and a talin-mediated linkage to the F-actin cytoskeleton. These findings, together with Rosetta modeling, suggest that integrins in FA are coaligned and may be highly tilted by cytoskeletal forces. Thus, the F-actin cytoskeleton sculpts an anisotropic molecular scaffold in FAs, and this feature may underlie the ability of migrating cells to sense directional extracellular cues.