Pronobis Mira I, Deuitch Natalie, Posham Vinya, Mimori-Kiyosue Yuko, Peifer Mark
Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599.
Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599.
Mol Biol Cell. 2017 Jan 1;28(1):41-53. doi: 10.1091/mbc.E16-07-0557. Epub 2016 Nov 16.
Negatively regulating key signaling pathways is critical to development and altered in cancer. Wnt signaling is kept off by the destruction complex, which is assembled around the tumor suppressors APC and Axin and targets β-catenin for destruction. Axin and APC are large proteins with many domains and motifs that bind other partners. We hypothesized that if we identified the essential regions required for APC:Axin cooperative function and used these data to design a minimal β-catenin-destruction machine, we would gain new insights into the core mechanisms of destruction complex function. We identified five key domains/motifs in APC or Axin that are essential for their function in reconstituting Wnt regulation. Strikingly, however, certain APC and Axin mutants that are nonfunctional on their own can complement one another in reducing β-catenin, revealing that the APC:Axin complex is a highly robust machine. We used these insights to design a minimal β-catenin-destruction machine, revealing that a minimized chimeric protein covalently linking the five essential regions of APC and Axin reconstitutes destruction complex internal structure, size, and dynamics, restoring efficient β-catenin destruction in colorectal tumor cells. On the basis of our data, we propose a new model of the mechanistic function of the destruction complex as an integrated machine.
对关键信号通路进行负调控对发育至关重要，且在癌症中会发生改变。Wnt信号通路通过破坏复合物被关闭，该复合物围绕肿瘤抑制因子APC和Axin组装，并将β-连环蛋白作为靶点进行破坏。Axin和APC是具有许多结构域和基序的大蛋白，这些结构域和基序可与其他伙伴结合。我们推测，如果我们确定了APC:Axin协同功能所需的关键区域，并利用这些数据设计一个最小化的β-连环蛋白破坏机器，我们将对破坏复合物功能的核心机制有新的认识。我们在APC或Axin中确定了五个关键结构域/基序，它们对于其在重建Wnt调控中的功能至关重要。然而，令人惊讶的是，某些自身无功能的APC和Axin突变体在降低β-连环蛋白方面可以相互补充，这表明APC:Axin复合物是一个高度稳健的机器。我们利用这些见解设计了一个最小化的β-连环蛋白破坏机器，结果表明，一种将APC和Axin的五个关键区域共价连接的最小化嵌合蛋白可重建破坏复合物的内部结构、大小和动力学，恢复结肠直肠肿瘤细胞中β-连环蛋白的有效破坏。基于我们的数据，我们提出了一个关于破坏复合物作为一个整合机器的机械功能的新模型。
