A model system to study the tumor suppressor APC

研究肿瘤抑制因子APC的模型系统

• 批准号: 8504082
• 负责人: Mark A. Peifer
• 金额: $ 27.85万
• 依托单位: UNIV OF NORTH CAROLINA CHAPEL HILL
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-09-01 至 2017-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8504082
• 关键词: APC gene; Adenomatous Polyposis Coli; Adult; Animals; Basic Science; Biochemical; 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; clinical application; effective therapy; in vivo; innovation; insight; intercellular communication; interdisciplinary approach; migration; novel; public health relevance; receptor; stem; tool; tumor; tumor progression; ubiquitin-protein ligase

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）：结肠癌是主要的健康挑战，是癌症死亡的第二大原因。大多数病例是由肿瘤抑制腺瘤性息肉病（APC）突变引发的。 APC最著名的是Wnt细胞 - 细胞信号通路的关键负调节剂，该途径几乎塑造了细胞的命运，几乎每个组织和器官都调节了几种组织中干细胞的稳态，并且在许多癌症中都受到了不当的激活。 APC还在调节细胞骨架中扮演了无关的角色，从而促进了诸如高保真染色体隔离之类的过程，这些过程在癌症中也受到破坏。我们实验室的长期目标是确定APC及其蛋白质伙伴如何在正常发育和稳态期间调节Wnt信号传导和细胞骨架，以及在结肠和其他癌症中该过程如何出错。我们的实验室在定义APC如何在“破坏复合物”中起作用，该作用是针对Wnt效应子Sscatenin用于泛素化和破坏的，并将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，以使用高度多学科的方法结合了最先进的遗传学，细胞生物学和生化工具，在果蝇发育和培养的人类细胞中与完整动物的完整动物进行研究。了解APC及其蛋白质伙伴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进基础科学和临床应用。虽然我们现在拥有用于Wnt调节和APC的细胞骨架功能的教科书模型，但越来越清楚这些范式被过度简化 事实，APC在破坏复合物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。过去的资金期间，我们在包括我们自己的WNT调节中对APC功能的现有假设提出了质疑，这表明APC在WNT监管中不发挥基本的核作用，也不在定位破坏综合体中起重要作用。取而代之的是，我们实验室和其他人的工作提出了目标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转移至E3泛素连接酶至关重要。在AIM 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，确定调节构象变化循环的新型蛋白质伴侣，并确定Wnt信号如何改变破坏性复杂动力学以将其关闭。我们的数据还表明，必须对APC角色作为细胞骨架调节剂的角色进行特征看法。我们假设APC不是有丝分裂的重要调节剂，而是采取行动，以确保高保真性染色体隔离，作为多蛋白复合物的一部分工作，并由有丝分裂检查点进行缓冲，可以部分补偿其损失的损失，从而确保APC和其偏移范围。隔离，并探索CHK2和其他检查点调节器如何缓冲其不存在的错误。