The major fibronectin (FN)-binding α5β1 and αvβ3 integrins exhibit cooperativity during cell adhesion, migration and mechanosensing, through mechanisms that are not yet fully resolved. Exploiting mechanically tunable nano-patterned substrates, and peptidomimetic ligands designed to selectively bind corresponding integrins, we report that focal adhesions (FAs) of endothelial cells assembled on α5β1 integrin-selective substrates rapidly recruit αvβ3 integrins, but not vice versa. Blocking of αvβ3 integrin hindered FA maturation and cell spreading on α5β1 integrin-selective substrates, indicating a mechanism dependent on extracellular ligand binding and highlighting the requirement of αvβ3 integrin engagement for efficient adhesion. Recruitment of αvβ3 integrins additionally occurred on hydrogel substrates of varying mechanical properties, above a threshold stiffness that supports FA formation. Mechanistic studies revealed the need for soluble factors present in serum to allow recruitment, and excluded exogenous, or endogenous, FN as the ligand responsible for αvβ3 integrin accumulation to adhesion clusters. Our findings highlight a novel mechanism of integrin cooperation and a critical role for αvβ3 integrins in promoting cell adhesion on α5β1 integrin-selective substrates.

中文翻译：

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将ανβ3整联蛋白招募至α5β1整联蛋白诱导的簇能够实现粘着斑成熟和细胞扩散。

主要的纤连蛋白（FN）结合α5β1和αvβ3整联蛋白通过尚未完全解决的机制在细胞粘附，迁移和机械传感过程中表现出协同作用。利用机械可调的纳米图案底物和拟选择性结合相应整联蛋白的拟肽配体，我们报道了组装在α5β1整联蛋白选择性底物上的内皮细胞的粘着斑（FA）迅速募集了αvβ3整联蛋白，反之则不然。αvβ3整联蛋白的阻滞阻碍了FA的成熟和细胞在α5β1整联蛋白选择性底物上的扩散，这表明了依赖于细胞外配体结合的机制，并突出了αvβ3整联蛋白参与有效粘附的要求。另外，在具有不同机械性能的水凝胶基质上还需要募集αvβ3整合素，高于支持FA形成的阈值刚度。机理研究表明，需要血清中存在的可溶性因子来募集，并排除外源性或内源性FN作为负责αvβ3整联蛋白积累至粘附簇的配体。我们的发现突出了整合素协同作用的新机制，以及αvβ3整合素在促进α5β1整合素选择性底物上的细胞粘附中的关键作用。