Recruitment of adenomatous polyposis coli and β-catenin to axin-puncta
Recruitment of adenomatous polyposis coli and β-catenin to axin-puncta
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DOI：
10.1038/onc.2008.205
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发表时间：
2008-10-02
期刊：
影响因子：
8
通讯作者：
Burgess, A. W.
中科院分区：
文献类型：
--
作者：
Faux, M. C.;Coates, J. L.;Burgess, A. W.
腺瘤性结肠息肉病（APC）肿瘤抑制因子是一种多功能蛋白，参与Wnt信号传导和细胞骨架动力学的调节。关于APC如何控制这些不同的功能知之甚少。在这项研究中，我们已经使用APC和轴荧光融合蛋白来研究这些蛋白质之间的相互作用，并表明APC的功能不同的人口也是空间上分开的。Axin-RFP形成细胞质点状结构，类似于内源性轴点。Axin-RFP募集β-连环蛋白破坏复合物蛋白，包括APC、β-连环蛋白、糖原合成酶激酶-3-β（GSK 3-β）和酪蛋白激酶-1-α（CK 1-α）。招募到轴-RFP点隔离APC从集群在细胞延伸，这阻止了其微管相关的功能。APC-GFP和轴蛋白-RFP之间的相互作用是直接的，并显着改变APC-GFP的动态特性。然而，APC向轴斑的募集不是β-连环蛋白降解所绝对需要的。相反，由DIX结构域介导的轴点的形成是β-连环蛋白降解所必需的。轴蛋白Delta DIX突变体不形成斑点，但仍介导破坏复合物蛋白的募集和β-连环蛋白的磷酸化。我们的结论是，有不同的池APC和轴斑的形成，而不是轴/APC复合物，是必不可少的β-连环蛋白破坏。
The adenomatous polyposis coli (APC) tumour suppressor is a multifunctional protein involved in the regulation of Wnt signalling and cytoskeletal dynamics. Little is known about how APC controls these disparate functions. In this study, we have used APC- and axin-fluorescent fusion proteins to examine the interactions between these proteins and show that the functionally distinct populations of APC are also spatially separate. Axin-RFP forms cytoplasmic punctate structures, similar to endogenous axin puncta. Axin-RFP recruits beta-catenin destruction complex proteins, including APC, b-catenin, glycogen synthase kinase-3-beta (GSK3-beta) and casein kinase-1-alpha (CK1-alpha). Recruitment into axin-RFP puncta sequesters APC from clusters at cell extensions and this prevents its microtubule-associated functions. The interaction between APC-GFP and axin-RFP within the cytoplasmic puncta is direct and dramatically alters the dynamic properties of APC-GFP. However, recruitment of APC to axin puncta is not absolutely required for beta-catenin degradation. Instead, formation of axin puncta, mediated by the DIX domain, is required for beta-catenin degradation. An axin Delta DIX mutant did not form puncta, but still mediated recruitment of destruction complex proteins and phosphorylation of beta-catenin. We conclude that there are distinct pools of APC and that the formation of axin puncta, rather than the axin/APC complex, is essential for beta-catenin destruction.