Cellular Functions of the Tumor Suppressor APC

描述（由申请人提供）：结肠癌肿瘤抑制因子结肠腺瘤性息肉病（APC）是Wnt信号转导途径的重要负调节因子，在肌动蛋白和微管细胞骨架的调节中也具有重要作用。APC蛋白影响细胞骨架的确切机制尚未确定，可能有助于结肠癌的发展。我们已经开发了一个在体内系统中，研究果蝇APC 2的细胞骨架功能的果蝇合胞体胚胎作为模型的细胞骨架组织。在这里，在细胞周期中皮层肌动蛋白的动态重排是由一些已知的肌动蛋白调节蛋白和与中心体和微管的相互作用。我们以前已经表明，果蝇APC 2在组织的合胞体细胞骨架中起作用，包括果蝇B-连环蛋白同源物，犰狳，和α-连环蛋白。我们在该系统中对APC 2的继续研究表明，APC 2的功能是在合胞体胚胎中组织肌动蛋白结构，并且这种功能部分地与果蝇的同源结构域蛋白质Diaphanous一起进行。该项目的总体目标包括定义APC 2在Armadillo-a-catenin复合物和透明复合物中的分子相互作用，并详细了解这些复合物如何使用生物化学测定、实时成像技术、肌动蛋白和微管组织和行为的分析以及其他蛋白质伴侣和调节剂的鉴定来组织肌动蛋白细胞骨架。这些发现不仅有助于我们理解正常细胞过程，也有助于我们理解细胞功能障碍和癌症。

DESCRIPTION (provided by applicant): The colon cancer tumor suppressor Adenomatous polyposis coli (APC) acts as an essential negative regulator of the Wnt signal transduction pathway and also has fundamental roles in the regulation of the actin and microtubule cytoskeletons. The precise mechanisms by which APC proteins influence the cytoskeleton have not been defined and may contribute to the development of colon cancer. We have developed an in vivo system in which to study the cytoskeletal functions of Drosophila APC2 using the Drosophila syncytial embryo as a model for cytoskeletal organization. Here, dynamic rearrangements of cortical actin during the cell cycle are orchestrated by a number of known actin regulatory proteins and by interactions with centrosomes and microtubules. We have previously shown that Drosophila APC2 plays a role in organization of the syncytial cytoskeleton in a complex including the Drosophila B-catenin homolog, Armadillo, and a-catenin. Our continued study of APC2 in this system revealed that APC2 functions to organize actin structures in the syncytial embryo and that this function is carried out in part with a Drosophila formin homology domain protein Diaphanous. The overall goals of this project include defining the molecular interactions of APC2 within the Armadillo-a-catenin complex and the Diaphanous complex and to understand in detail how these complexes are functioning to organize the actin cytoskeleton using biochemical assays, live imaging techniques, analysis of actin and microtubule organization and behavior, and identification of other proteins partners and regulators. These findings will contribute not only to our appreciation of normal cell processes, but also to our understanding of cellular dysfunction and cancer.