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A model system to study the tumor suppressor APC

研究肿瘤抑制因子APC的模型系统

基本信息

批准号：
8900295
负责人：
Mark A. Peifer
金额：
$ 25.59万
依托单位：
UNIV OF NORTH CAROLINA CHAPEL HILL
依托单位国家：
美国
项目类别：
财政年份：
2002
资助国家：
美国
起止时间：
2002-09-01 至 2018-07-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8900295
关键词：
APC gene APC2 gene Adenomatous Polyposis Coli Adult Animals Basic Science Biological Biological Models Buffers Cancer Etiology Cell Shape Cells Centrosome Cessation of life Chromosomal Instability Chromosome Segregation Colon Colon Carcinoma Communication Complex Cytoskeleton DNA Damage Data Development Drosophila genus Ensure Event Excision Funding Genetic Genome Stability Goals Health Homeostasis Human Malignant Neoplasms Mitosis Mitotic Mitotic Checkpoint Modeling Multiprotein Complexes Mutate Mutation Nuclear Organ Pathway interactions Phosphorylation Play Process Proteins Regulation Role Set protein Signal Pathway Signal Transduction Skeleton Stem cells Textbooks Tissues Translating Tumor Suppressor Proteins Ubiquitination Work base biochemical tools clinical application effective therapy in vivo innovation insight intercellular communication interdisciplinary approach migration novel receptor stem tumor tumor progression ubiquitin-protein ligase

项目摘要

DESCRIPTION (provided by applicant): Colon cancer is a major health challenge, ranking as the second leading cause of cancer deaths. Most cases are initiated by mutations in the tumor suppressor Adenomatous polyposis coli (APC). APC is best known as a key negative regulator of the Wnt cell-cell signaling pathway, which shapes cell fates in virtually every tissue and organ, regulates homeostasis of stem cells in several tissues, and is inappropriately activated in many cancers. APC also plays Wnt-independent roles in regulating the cytoskeleton, thus facilitating processes like high-fidelity chromosome segregation, which also are disrupted in cancer. Our lab's long term goal is to determine how APC and its protein partners regulate both Wnt signaling and the cytoskeleton during normal development and homeostasis, and how that process goes wrong in colon and other cancers. Our lab played important roles in defining how APC acts in the "destruction complex", which targets the Wnt effectors sscatenin for ubiquitination and destruction, and also identified APC as a regulator of cytoskeletal events. To do so, we established powerful dual model systems to study this in parallel in intact animals during Drosophila development and in cultured human cells, using a highly multidisciplinary approach combining state-of-the-art genetic, cell biological, and biochemical tools. Understanding mechanisms by which APC and its protein partners regulate both Wnt signaling and the cytoskeleton during normal development will thus advance both basic science and clinical applications. While we now possess textbook models for both Wnt regulation and APCs cytoskeletal function, it is becoming increasingly clear that these paradigms are oversimplified-in fact APC's mechanistic roles in the destruction complex and in cytoskeletal regulation remain largely mysterious. Our work in the past funding period challenged existing hypotheses for APC function in Wnt regulation, including our own, demonstrating that APC does not play essential nuclear roles in Wnt regulation nor does it play an essential role in localizing the destruction complex. Instead, work from our lab and others suggests the innovative hypothesis underlying Aim 1, in which APC regulates a dynamic catalytic cycle of the destruction complex, which is essential for sscatenin transfer to the E3 ubiquitin ligase. In Aim 1 we will define mechanisms by which APC and Axin act in a dynamic destruction complex, identify novel protein partners that regulate the cycle of conformational change, and determine how Wnt signaling alters destruction complex dynamics to turn it off. Our data also suggest textbook views of APC's roles as a cytoskeletal regulator must be significantly modified. We hypothesize APC is not an essential regulator of mitosis, but instead acts to ensure high fidelity chromosome segregation, working as part of a multiprotein complex, and with its action buffered by mitotic checkpoints that can partially compensate for its loss-this underlies Aim 2. In this Aim we will determine how APC and its partners act to regulate centrosome migration and thus ensure high fidelity chromosome segregation, and explore how Chk2 and other checkpoint regulators buffer the errors that occur in its absence.

描述（由申请人提供）：结肠癌是一个重大的健康挑战，是癌症死亡的第二大原因。大多数病例是由肿瘤抑制基因腺瘤性结肠息肉病（APC）突变引起的。APC最为人所知的是Wnt细胞-细胞信号通路的关键负调节因子，其在几乎每个组织和器官中塑造细胞命运，调节几种组织中干细胞的稳态，并且在许多癌症中被不适当地激活。APC还在调节细胞骨架中发挥Wnt独立作用，从而促进高保真染色体分离等过程，这些过程在癌症中也被破坏。我们实验室的长期目标是确定APC及其蛋白质伴侣如何在正常发育和稳态过程中调节Wnt信号传导和细胞骨架，以及该过程如何在结肠和其他癌症中出错。我们的实验室在定义APC如何在“破坏复合物”中起作用方面发挥了重要作用，该复合物靶向Wnt效应物sscatenin进行泛素化和破坏，并且还将APC鉴定为细胞骨架事件的调节剂。为此，我们建立了强大的双模型系统，在果蝇发育期间的完整动物和培养的人类细胞中平行研究这一点，使用高度多学科的方法，结合最先进的遗传学，细胞生物学和生物化学工具。因此，了解APC及其蛋白伴侣在正常发育过程中调节Wnt信号传导和细胞骨架的机制将推动基础科学和临床应用。虽然我们现在拥有Wnt调控和APC细胞骨架功能的教科书模型，但越来越明显的是，这些范式被过度简化了。事实上，APC在破坏复合体和细胞骨架调节中的机械作用在很大程度上仍然是神秘的。我们在过去的资助期间的工作挑战了现有的假设APC功能在Wnt调控，包括我们自己的，表明APC不发挥重要的核作用Wnt调控，也没有发挥重要的作用，在本地化的破坏复杂。相反，我们实验室和其他人的工作提出了Aim 1的创新假设，其中APC调节破坏复合物的动态催化循环，这对于sscatenin转移到E3泛素连接酶至关重要。在目标1中，我们将定义APC和Axin在动态破坏复合物中起作用的机制，确定调节构象变化周期的新蛋白质伴侣，并确定Wnt信号如何改变破坏复合物的动力学以关闭它。我们的数据还表明，教科书上关于APC作为细胞骨架调节因子的观点必须进行重大修改。我们假设APC不是有丝分裂的重要调节器，而是作为多蛋白复合物的一部分起作用以确保高保真的染色体分离，并且其作用由有丝分裂检查点缓冲，可以部分补偿其损失-这是目标2的基础。在这个目标中，我们将确定APC及其合作伙伴如何调节中心体迁移，从而确保高保真的染色体分离，并探索Chk 2和其他检查点调节器如何缓冲在其缺失时发生的错误。