The meiotic role of dtopors in male Drosophila

dtopors在雄性果蝇减数分裂中的作用

• 批准号: 7304661
• 负责人: JOHN E TOMKIEL DEAN
• 金额: $ 20.93万
• 依托单位: UNIVERSITY OF NORTH CAROLINA GREENSBORO
• 依托单位国家: 美国
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-07-01 至 2011-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7304661
• 关键词: Alleles; Aneuploidy; Binding; Biological Assay; Biological Markers; Bulla; Cancer cell line; Cell Cycle Progression; Cell Cycle Proteins; Cell Cycle Regulation; Cell division; Cells; Centrioles; Centrosome; Chromatin; Chromosomal Instability; Chromosome Condensation; Chromosome Segregation; Collection; Complex; Confocal Microscopy; DNA Repair; Defect; Disruption; Drosophila genus; Drosophila melanogaster; Embryo; Fingers; Gene Expression Regulation; Genes; Genetic; Genetic Screening; Genomic Instability; Germ Cells; Germ Lines; Homologous Gene; Human; Human Activities; Individual; Insulator Elements; Lamins; Lead; Ligase; Male Sterility; Malignant Neoplasms; Meiosis; Microscopy; Mitosis; Mitotic; Modeling; Molecular Genetics; Nuclear; Nuclear Lamina; Nuclear Structure; Numbers; Outcome; Pathway interactions; Pattern; Phenotype; Play; Production; Property; Prophase; Protein Overexpression; Proteins; Proteolysis; Regulation; Regulator Genes; Role; Series; System; TP53 gene; Tertiary Protein Structure; Testis; Transcriptional Regulation; Transgenes; Transgenic Organisms; Transmission Electron Microscopy; Tumor Suppression; Tumor Suppressor Genes; Tumor Suppressor Proteins; Type I DNA Topoisomerases; Ubiquitin; Ubiquitination; Viral; base; cancer type; chemotherapy; fly; human TOP1 protein; insight; leukemia; male; multicatalytic endopeptidase complex; mutant; protein function; transcription factor; tumorigenesis; ubiquitin ligase

DESCRIPTION (provided by applicant): The tumor suppressor Topors is an E3-type ubiquitin and SUMO ligase that binds to a number of important cell cycle regulatory proteins, including p53, topoisomerase I, and DJ-1. It regulates protein function by ubiquitin-conjugating targets for proteosome degradation, or by altering binding properties or cellular localizations of targets by sumoylation. Additionally, Topors associates with Promyeloleucytic Leukemia Bodies, nuclear structures implicated in oncogenesis that are involved in a diversity of functions including sumolyation, transcriptional regulation, cell cycle control and anti-viral defense. Topors is downregulated in cancer cell lines, suggesting its activities are important for suppressing oncogenesis. Drosophila has proven an informative model for characterizing functions of the conserved Topors homolog, Dtopors. The Dtopors protein acts as a ubiquitin ligase, and regulates early embryonic pattern by directing proteolysis of the Hairy transcription factor. Additionally, it plays a second role in gene regulation via assembly at insulator elements. Insulator elements are proposed to function by establishing chromatin domains that restrict the activities of cis-acting transcriptional regulatory elements. The Dtopors protein associates with insulator proteins and lamin and has been hypothesized to play an important functional role in tethering insulator complexes to the nuclear lamina. The Dtopors protein is also essential for proper chromosome segregation in the male germ line, where it is required for timely chromosome condensation, normal nuclear lamina formation, and the regulation of centrosome duplication. In meiotic prophase cells, Dtopors assembles into intranuclear foci reminiscent of PML bodies. Mutants in dtopors lead to disruption of these foci, germline genomic instability and the production of aneuploid gametes. These findings suggest that characterization of Dtopors function in the Drosophila male germ line may reveal important conserved mechanisms of tumor suppression. Such studies will be pursued using a combined cytological, molecular and genetic approach. Requirements for Dtopors in the male germ line will be defined by examining the outcome of temporally and spatially regulated expression of wild type and mutant forms of Dtopors. The ability to form foci and to rescue individual aspects of the germ line defects will be examined both cytologically and genetically. A potential interaction with Mod(mdg4), a known mitotic partner of Dtopors, will be investigated in meiosis. Modifier screens will be performed to identify new genes that interact with dtopors in meiosis, based on suppression of a dtopors allele-specific male sterility and on alteration of dtopors-induced cytological defects. These studies will characterize the involvement of dTopors in meiotic cell division, and importantly will lead to the identification of genes in the dtopors pathway that may have important implications for the activities of human Topors in tumor suppression. Topors is a multifunctional human tumor suppressor gene known to alter the activities of proteins involved in cell cycle progression and DNA damage repair. Studies of dtopors, the functional homolog in the fruit fly Drosophila melanogaster, have revealed important insights on its mechanism of action. This proposal aims to characterize dtopors functions in male meiosis, where it is particularly critical and is required for meiotic chromosome segregation, towards understanding of analogous roles of human Topors in tumor suppression.

描述（由申请人提供）：肿瘤抑制因子Topors是一种E3型泛素和SUMO连接酶，与许多重要的细胞周期调节蛋白结合，包括p53、拓扑异构酶I和DJ-1。它通过泛素结合蛋白体降解靶点，或通过类小泛素化改变靶点的结合特性或细胞定位来调节蛋白质功能。此外，Topors与早幼粒细胞白血病小体相关，早幼粒细胞白血病小体是与肿瘤发生有关的核结构，其参与多种功能，包括抑制、转录调节、细胞周期控制和抗病毒防御。Topors在癌细胞系中下调，表明其活性对抑制肿瘤发生很重要。果蝇已经证明了一个信息模型的保守Topors同源物，Dtopors的功能特征。Dtopors蛋白作为泛素连接酶，通过指导Hairy转录因子的蛋白水解来调节早期胚胎模式。此外，它还通过在绝缘子元件上的组装在基因调控中发挥第二个作用。绝缘子元件被认为是通过建立染色质结构域来限制顺式作用转录调控元件的活性。Dtopors蛋白与绝缘子蛋白和核纤层蛋白相关联，并被假设在将绝缘子复合物拴系到核纤层中发挥重要的功能作用。Dtopors蛋白对于雄性生殖系中的适当染色体分离也是必不可少的，在雄性生殖系中，它是及时染色体浓缩、正常核纤层形成和中心体复制调节所必需的。在减数分裂前期细胞中，Dtopors组装成核内病灶，使人联想到PML小体。dtopors中的突变体导致这些焦点的破坏、种系基因组的不稳定性和非整倍体配子的产生。这些发现表明，Dtopors功能的果蝇雄性生殖系的特征可能揭示重要的保守的肿瘤抑制机制。这些研究将采用细胞学、分子学和遗传学相结合的方法进行。将通过检查野生型和突变型Dtopors的时间和空间调节表达的结果来定义雄性生殖系中对Dtopors的要求。将从细胞学和遗传学两个方面检查形成病灶和挽救生殖系缺陷个体方面的能力。将在减数分裂中研究与Dtopors的已知有丝分裂伴侣Mod（mdg 4）的潜在相互作用。将进行修饰筛选，以确定与dtopors在减数分裂中相互作用的新基因，基于抑制dtopors等位基因特异性雄性不育和dtopors诱导的细胞学缺陷的改变。这些研究将表征dTopors参与减数分裂细胞分裂的特征，并且重要的是将导致鉴定dTopors途径中的基因，这些基因可能对人类Topors在肿瘤抑制中的活性具有重要意义。Topors是一种多功能的人类肿瘤抑制基因，已知其改变参与细胞周期进程和DNA损伤修复的蛋白质的活性。dtopors是果蝇Drosophila melanogaster中的功能同源物，对它的研究揭示了其作用机制的重要见解。该建议旨在表征dtopors在男性减数分裂中的功能，其中它是特别关键的，并且是减数分裂染色体分离所需的，以了解人类Topors在肿瘤抑制中的类似作用。