PDF(Pubmed)
Abstract：
Cell adhesion requires linkage of transmembrane receptors to the cytoskeleton through intermediary linker proteins. Integrin-based adhesion to the extracellular matrix (ECM) involves large adhesion complexes that contain multiple cytoskeletal adapters that connect to the actin cytoskeleton. Many of these adapters, including the essential cytoskeletal linker Talin, have been shown to contain multiple actin-binding sites (ABSs) within a single protein. To investigate the possible role of having such a variety of ways of linking integrins to the cytoskeleton, we generated mutations in multiple actin binding sites in Drosophila talin. Using this approach, we have been able to show that different actin-binding sites in talin have both unique and complementary roles in integrin-mediated adhesion. Specifically, mutations in either the C-terminal ABS3 or the centrally located ABS2 result in lethality showing that they have unique and non-redundant function in some contexts. On the other hand, flies simultaneously expressing both the ABS2 and ABS3 mutants exhibit a milder phenotype than either mutant by itself, suggesting overlap in function in other contexts. Detailed phenotypic analysis of ABS mutants elucidated the unique roles of the talin ABSs during embryonic development as well as provided support for the hypothesis that talin acts as a dimer in in vivo contexts. Overall, our work highlights how the ability of adhesion complexes to link to the cytoskeleton in multiple ways provides redundancy, and consequently robustness, but also allows a capacity for functional specialization.
摘要：
细胞粘附需要跨膜受体通过中间接头蛋白与细胞骨架连接。基于整合素的对细胞外基质(ECM)的粘附涉及大的粘附复合物,其包含连接到肌动蛋白细胞骨架的多个细胞骨架衔接子。这些适配器中的许多，包括必需的细胞骨架接头Talin,已显示在单个蛋白质内含有多个肌动蛋白结合位点(ABSs)。为了研究将整合素与细胞骨架连接的各种方式的可能作用，我们在果蝇talin的多个肌动蛋白结合位点产生突变。使用这种方法，我们已经能够证明，talin中不同的肌动蛋白结合位点在整合素介导的粘附中具有独特和互补的作用。具体来说,C端ABS3或位于中央的ABS2中的突变导致致死性,表明它们在某些情况下具有独特且非冗余的功能.另一方面,同时表达ABS2和ABS3突变体的果蝇表现出比任一突变体本身更温和的表型，建议在其他情况下的功能重叠。ABS突变体的详细表型分析阐明了talinABS在胚胎发育过程中的独特作用，并为talin在体内环境中充当二聚体的假设提供了支持。总的来说,我们的工作强调了粘附复合物以多种方式连接到细胞骨架的能力如何提供冗余，因此，鲁棒性，而且还允许功能专业化的能力。
