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: 7759140
• 负责人: Kenneth H Moberg
• 金额: $ 26.51万
• 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 2012-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7759140
• 关键词: Binding; Biochemical Genetics; Biological; Biological Models; Blood Vessels; Cell Cycle; Cell Proliferation; Cells; Chemotactic Factors; 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member; mutant; novel; programs; transcription factor; tumorigenesis; ubiquitin ligase; ubiquitin-protein ligase; unpublished works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 In the current proposal, we present a substantial body of unpublished work that demonstrates a novel role for the ago ligase in post-mitotic morphogenesis of the fly embryonic tracheal system, a branched network of epithelial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(申请人提供)：我们的长期目标是以果蝇黑腹果蝇为模型系统，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，我们专注于群岛(AGO)基因的一种新功能，我们根据其在苍蝇眼中的抗增殖作用来鉴定该基因，其人类同源基因Fbw7随后被证明在各种组织类型中抑制肿瘤发生。AGO基因编码一种F-box蛋白(AGO)，通过直接与蛋白酶体降解的蛋白质结合，并将它们重新招募到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靶标，细胞周期调节因子Cyclin E和原癌基因转录因子dMyc，这两个靶标也是Fbw7的靶标。然而，我们对AGO/Fbw7靶基因全谱的缺乏限制了我们对该基因在发育中作用的理解，并阻碍了预测AGO/Fbw7缺失在人类中的生物学后果的尝试。在目前的提案中，我们提出了大量未发表的工作，证明了AGO连接酶在苍蝇胚胎气管系统有丝分裂后形态发生中的新作用，苍蝇胚胎气管系统是一个类似于人类血管系统的上皮管分支网络，通过发育中的胚胎输送氧气。我们推测，AGO通过一个新的靶点发挥作用：TracHealth Protein(TRH)，它是缺氧诱导因子(HIF)-1α转录因子家族的成员，激活成纤维细胞生长因子(FGF)途径，后者是苍蝇气管发育和哺乳动物血管和肺发育的已知调节因子。在特定的目标1中，我们试图测试我们的初步数据提出的假设，即AGO与气管细胞中的TRH结合，并将其作为降解的目标。我们已经发现，AGO可能与dVHL基因在这一过程中起冗余作用，dVHL基因编码一种已知参与气管发育的HIF-1α泛素连接酶，在特定的目的2，我们建议测试AGO和dVHL之间的遗传和功能相互作用。我们还发现，成熟组织中AGO的失活能够非细胞自主地诱导异位的气管末端分支，这一过程通常由氧气供应控制。因此，我们假设AGO在抑制气管分支的动态平衡机制中起着重要作用。我们在具体目标3中的目标是定义这一角色并阐明其分子基础。