Regulated binding of adenomatous polyposis coli protein to actin
Regulated binding of adenomatous polyposis coli protein to actin
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DOI：
10.1074/jbc.m610615200
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发表时间：
2007-04-27
影响因子：
4.8
通讯作者：
Goode, Bruce L.
中科院分区：
文献类型：
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作者：
Moseley, James B.;Bartolini, Francesca;Goode, Bruce L.
大肠腺瘤性息肉病（APC）蛋白是一种大的肿瘤抑制因子，在大多数结直肠癌中被截短。APC蛋白的羧基末端三分之一介导与微管和微管加末端跟踪蛋白EB 1的直接相互作用。此外，APC已定位于肌动蛋白丰富的细胞区域，但这种定位的机制和功能意义仍不清楚。在这里，我们表明，纯化的人APC蛋白（APC-基本）的羧基末端的基本结构域直接绑定和捆绑肌动蛋白丝和相关的肌动蛋白应力纤维在显微注射细胞。肌动蛋白丝和微管竞争结合APC-碱性，但APC-碱性也可以交联肌动蛋白丝和微管在特定的浓度，这表明在细胞骨架的串扰可能的作用。APC与肌动蛋白在体外的相互作用被其配体EB 1抑制，并且共显微注射EB 1防止APC与应力纤维的关联。在EB 1的点突变，破坏APC结合解除抑制在体外和恢复APC本地化的应力纤维在体内，表明EB 1-APC的调节是直接的。由于肿瘤的形成和转移涉及肌动蛋白和微管细胞骨架的协调变化，APC的这种新功能及其受EB 1的调节可能具有直接的意义。
Adenomatous polyposis coli ( APC) protein is a large tumor suppressor that is truncated in most colorectal cancers. The carboxyl-terminal third of APC protein mediates direct interactions with microtubules and the microtubule plus-end tracking protein EB1. In addition, APC has been localized to actin-rich regions of cells, but the mechanism and functional significance of this localization have remained unclear. Here we show that purified carboxyl-terminal basic domain of human APC protein ( APC-basic) bound directly to and bundled actin filaments and associated with actin stress fibers in microinjected cells. Actin filaments and microtubules competed for binding to APC-basic, but APC-basic also could cross-link actin filaments and microtubules at specific concentrations, suggesting a possible role in cytoskeletal cross-talk. APC interactions with actin in vitro were inhibited by its ligand EB1, and co-microinjection of EB1 prevented APC association with stress fibers. Point mutations in EB1 that disrupted APC binding relieved the inhibition in vitro and restored APC localization to stress fibers in vivo, demonstrating that EB1-APC regulation is direct. Because tumor formation and metastasis involve coordinated changes in the actin and microtubule cytoskeletons, this novel function for APC and its regulation by EB1 may have direct implications