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，可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。它通过泛素缀合靶标进行蛋白酶体降解，或通过苏酰化改变靶标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体相关，这是与肿瘤发生有关的核结构，涉及多种功能，包括合成、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，表明其活性对于抑制肿瘤发生很重要。果蝇已被证明是一种表征保守 Topors 同源物 Dtopors 功能的信息丰富的模型。 Dtopors 蛋白充当泛素连接酶，通过指导毛转录因子的蛋白水解来调节早期胚胎模式。此外，它还通过在绝缘体元件上组装在基因调控中发挥第二个作用。绝缘子元件被认为通过建立限制顺式作用转录调控元件活性的染色质结构域来发挥作用。 Dtopors 蛋白与绝缘体蛋白和核纤层蛋白结合，并被假设在将绝缘体复合物束缚到核纤层中发挥重要的功能作用。 Dtopors 蛋白对于雄性种系中正确的染色体分离也至关重要，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 组装成核内灶，让人想起 PML 小体。 dtopor 突变体会​​导致这些病灶的破坏、种系基因组的不稳定性以及非整倍体配子的产生。这些发现表明，果蝇雄性种系中 Dtopors 功能的表征可能揭示肿瘤抑制的重要保守机制。此类研究将采用细胞学、分子和遗传学相结合的方法进行。雄性种系中对 Dtopors 的要求将通过检查 Dtopors 野生型和突变形式的时间和空间调节表达的结果来确定。形成病灶和挽救种系缺陷的各个方面的能力将从细胞学和遗传学上进行检查。将在减数分裂中研究与 Dtopors 的已知有丝分裂伴侣 Mod(mdg4) 的潜在相互作用。基于对 dtopors 等位基因特异性雄性不育的抑制和 dtopors 诱导的细胞学缺陷的改变，将进行修饰筛选，以鉴定在减数分裂中与 dtopors 相互作用的新基因。这些研究将表征 dTopors 在减数分裂细胞分裂中的参与，重要的是，将导致 dtopors 途径中基因的鉴定，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 是一种多功能人类肿瘤抑制基因，已知可以改变参与细胞周期进程和 DNA 损伤修复的蛋白质的活性。 dtopor（果蝇果蝇中的功能同源物）的研究揭示了对其作用机制的重要见解。该提案旨在表征雄性减数分裂中 dtopors 的功能，它对于减数分裂染色体分离尤为重要，也是必要的，以了解人类 Topors 在肿瘤抑制中的类似作用。