Reticular adhesions (RAs) consist of integrin αvβ5 and harbor flat clathrin lattices (FCLs), long-lasting structures with similar molecular composition as clathrin-mediated endocytosis (CME) carriers. Why FCLs and RAs colocalize is not known. Here, we show that RAs are assembled at FCLs in a process controlled by fibronectin (FN) and its receptor, integrin α5β1. We observed that cells on FN-rich matrices displayed fewer FCLs and RAs. CME machinery inhibition abolished RAs and live-cell imaging showed that RA establishment requires FCL coassembly. The inhibitory activity of FN was mediated by the activation of integrin α5β1 at Tensin1-positive fibrillar adhesions. Conventionally, endocytosis disassembles cellular adhesions by internalizing their components. Our results present a novel paradigm in the relationship between these two processes by showing that endocytic proteins can actively function in the assembly of cell adhesions. Furthermore, we show this novel adhesion assembly mechanism is coupled to cell migration via unique crosstalk between cell-matrix adhesions.

中文翻译：

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网状粘连在扁平的网格蛋白晶格上组装，并受到活性整合素 α5β1 的对抗


网状粘连 (RA) 由整合素 αvβ5 和扁平网格蛋白网格 (FCL) 组成，这是一种持久结构，其分子组成与网格蛋白介导的内吞作用 (CME) 载体相似。为什么 FCL 和 RA 共定位尚不清楚。在这里，我们表明 RA 在 FCL 上组装的过程由纤连蛋白 (FN) 及其受体整合素 α5β1 控制。我们观察到富含 FN 的基质上的细胞显示出较少的 FCL 和 RA。 CME 机械抑制消除了 RA，活细胞成像表明 RA 的建立需要 FCL 共组装。 FN 的抑制活性是通过 Tensin1 阳性纤维粘连处整合素 α5β1 的激活介导的。传统上，内吞作用通过内化细胞粘附的成分来分解细胞粘附。我们的结果通过表明内吞蛋白可以在细胞粘附组装中积极发挥作用，为这两个过程之间的关系提供了一个新的范例。此外，我们表明这种新颖的粘附组装机制通过细胞基质粘附之间独特的串扰与细胞迁移耦合。