Role of the Archipelago gene in Drosophila tracheal morphogenesis

群岛基因在果蝇气管形态发生中的作用

• 批准号: 7337614
• 负责人: Kenneth H Moberg
• 金额: $ 26.78万
• 依托单位: EMORY UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-02-01 至 2011-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7337614
• 关键词: Binding; Biochemical Genetics; Biological; Biological Models; Blood Vessels; Cell Cycle; Cell Proliferation; Cells; Chemotactic Factors; Condition; Cyclin E; Data; Defect; Development; Dominant-Negative Mutation; Drosophila genus; Drosophila melanogaster; Duct (organ) structure; Embryo; Epithelial; Eye; F-Box Proteins; Family; Fibroblast Growth Factor; Genes; Genetic Techniques; Genetic screening method; Goals; Histocompatibility Testing; Human; Hypoxia Inducible Factor; Knowledge; Ligase; Mammals; Mitotic; Modeling; Molecular; Morphogenesis; Morphology; Oncogenic; Orthologous Gene; Oxygen; Pathway interactions; Play; Process; Proteins; Recruitment Activity; Research Personnel; Role; Specificity; System; Testing; Tissues; Transgenes; Tube; Ubiquitination; Work; activating transcription factor; base; expectation; fly; gene function; hypoxia inducible factor 1; knock-down; lung development; member; mutant; novel; programs; transcription factor; tumorigenesis; ubiquitin ligase; ubiquitin-protein ligase; unpublished works

DESCRIPTION (provided by applicant): It is our long-term goal to use the fruit fly Drosophila melanogaster as a model system to identify genes that restrict cell proliferation, and to study the functions of these genes in developing tissues. Here we focus on a novel function of the archipelago (ago) gene, which we identified based on its anti-proliferative role in the fly eye, and whose human ortholog Fbw7 was subsequently shown to suppress tumorigenesis in a variety of tissue types. The ago gene encodes an F-box protein (Ago) that targets proteins for proteasomal degradation by binding directly to them, and recruiting them into an SCF E3-ubiquitin ligase for poly- ubiquitination. We have previously identified two Ago targets, the cell cycle regulator Cyclin E, and the proto- oncogenic transcription factor dMyc, both of which are also targeted by Fbw7. However, our lack of knowledge of the full repertoire of ago/Fbw7 targets limits our understanding of the role of the gene in development, and hinders attempts to predict the biological consequences of ago/Fbw7 loss in humans. In the current proposal, we present a substantial body of unpublished work that demonstrates a novel role for the ago ligase in post-mitotic morphogenesis of the fly embryonic tracheal system, a branched network of epithelial tubes similar to the human vasculature which duct oxygen through the developing embryo. We hypothesize that ago acts in this pathway via a novel target: the Trachealess protein (Trh), a member of the Hypoxia Inducible Factor (HIF)-1 alpha family of transcription factors that activates the Fibroblast Growth Factor (FGF) pathway, a known regulator of tracheal development in flies and vascular & lung development in mammals. In Specific Aim 1, we seek to test a hypothesis suggested by our preliminary data that Ago binds Trh in tracheal cells, and targets it for degradation. We have found that ago may act redundantly in this process with the dVHL gene, which encodes a HIF-1 alpha ubiquitin-ligase known to be involved in tracheal development, and in Specific Aim 2, we propose to test genetic and functional interactions between ago and dVHL. We also find that inactivation of ago in mature tissues is able to non-cell autonomously induce ectopic terminal tracheal branching, a process that is normally controlled by oxygen availability. Thus, we hypothesize that ago plays an important role in the homeostatic mechanisms that restrain tracheal branching. Our goal in Specific Aim 3 is to define this role and elucidate its molecular basis.

描述（由申请人提供）：我们的长期目标是使用果蝇 Drosophila melanogaster 作为模型系统来识别限制细胞增殖的基因，并研究这些基因在发育组织中的功能。在这里，我们重点关注群岛 (ago) 基因的一个新功能，我们根据其在果蝇眼中的抗增殖作用来识别该功能，并且其人类直系同源物 Fbw7 随后被证明可以抑制多种组织类型中的肿瘤发生。 ago 基因编码 F-box 蛋白 (Ago)，该蛋白通过直接与蛋白质结合来靶向蛋白质进行蛋白酶体降解，并将它们招募到 SCF E3 泛素连接酶中进行多泛素化。我们之前已经确定了两个 Ago 靶点，即细胞周期调节因子 Cyclin E 和原癌转录因子 dMyc，这两个靶点也是 Fbw7 的靶点。然而，我们对 ago/Fbw7 靶标的全部知识缺乏了解，限制了我们对该基因在发育中的作用的理解，并阻碍了预测人类中 ago/Fbw7 缺失的生物学后果的尝试。在当前的提案中，我们提出了大量未发表的工作，证明了前连接酶在果蝇胚胎气管系统有丝分裂后形态发生中的新作用，该系统是一个类似于人类脉管系统的上皮管分支网络，通过气管系统输送氧气。发育中的胚胎。我们假设 ago 通过一个新靶标在该通路中发挥作用：气管蛋白 (Trh)，它是缺氧诱导因子 (HIF)-1 α 转录因子家族的成员，可激活成纤维细胞生长因子 (FGF) 通路，这是一种已知的通路。果蝇气管发育以及哺乳动物血管和肺发育的调节器。在具体目标 1 中，我们试图测试我们的初步数据所提出的假设，即 Ago 与气管细胞中的 Trh 结合，并以它为目标进行降解。我们发现，ago 可能在此过程中与 dVHL 基因发挥冗余作用，dVHL 基因编码已知参与气管发育的 HIF-1 α 泛素连接酶，在具体目标 2 中，我们建议测试 ago 之间的遗传和功能相互作用和 dVHL。我们还发现，成熟组织中 ago 的失活能够非细胞自主诱导异位末端气管分支，这一过程通常由氧气可用性控制。因此，我们假设 ago 在抑制气管分支的稳态机制中发挥重要作用。我们在具体目标 3 中的目标是定义这一作用并阐明其分子基础。