Developmental Regulation of the Cell Cycle in Drosophila

果蝇细胞周期的发育调控

基本信息

批准号：
7887404
负责人：
LAURA ANNE LEE
金额：
$ 29.79万
依托单位：
VANDERBILT UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2005
资助国家：
美国
起止时间：
2005-04-01 至 2014-03-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/7887404
关键词：
Acetylation Acetyltransferase Animal Model Appearance Binding Biological Process Brain Cell Cycle Cell Cycle Regulation Cell Nucleus Cell division Cells Centrioles Centrosome Chimeric Proteins Chromosome Segregation Complex Coupling Cytokinesis Cytology Cytoplasm DNA Data Defect Development Differentiation and Growth Drosophila genus Drosophila melanogaster Dynein ATPase Employee Strikes Event Exhibits Funding Gametogenesis Genetic Germ Cells Haploidy Homologous Gene Human Image Analysis Intracellular Transport Knowledge LIS1 protein Life Malignant Neoplasms Mediating Meiosis Microtubules Mitosis Mitotic Modeling Motor Movement Mus Nuclear Nuclear Pore Complex Organism Pattern Phenotype Phosphorylation Site Process Prophase Proteins Proteolysis Recruitment Activity Regulation Relative (related person)Reporting Role Site Somatic Cell Spermatids Spermatocytes Spermatogenesis Surface System Tertiary Protein Structure Testing Testis Time Tubulin Yeasts cell motility dynactin gene conservation human disease insight kinetosome male mutant programs public health relevance research study sperm cell yeast two hybrid system

项目摘要

DESCRIPTION (provided by applicant): The high degree of functional conservation of genes involved in the cell cycle combined with the superb genetics and cytology of Drosophila melanogaster make it an ideal model organism for studying cell-cycle regulation in a developmental context. Spermatogenesis utilizes mitotic and meiotic cell cycles coordinated with growth and differentiation programs to generate functional sperm. By mutational analysis, we have identified asunder (asun), which encodes an evolutionarily conserved protein, as an essential regulator of Drosophila spermatogenesis. asun spermatocytes arrest during prophase of meiosis I. Strikingly, arrested spermatocytes contain free centrosomes that fail to stably associate with the nucleus. Spermatocytes that overcome arrest exhibit severe defects in meiotic spindle assembly, chromosome segregation, and cytokinesis. Furthermore, the centriole-derived basal body is detached from the nucleus in asun postmeiotic spermatids, resulting in abnormalities later in spermatogenesis. We find that asun spermatocytes and spermatids exhibit drastic reduction of perinuclear dynein. Dynein is a minus end-directed microtubule motor complex that is required for diverse biological processes, from transport of intracellular cargo to cell migration. Dynein is controlled at multiple levels, including regulation of its subcellular localization; the mechanisms underlying the targeting of dynein to various sites within cells, however, are not well understood. Our current model is that asun coordinates spermatogenesis by promoting dynein recruitment to the nuclear surface, a critical step that is required for nucleus-centrosome coupling at M-phase entry and fidelity of meiotic divisions. ASUN exhibits a dynamic localization pattern during Drosophila male meiosis, and the timing of its release from the nucleus to the cytoplasm correlates with the appearance of dynein on the nuclear surface in G2 spermatocytes. We will assess whether this regulated movement of ASUN within spermatocytes is critical for controlling the activity of dynein. We propose experiments that will allow us to gain a more detailed understanding of the mechanism by which dynein is recruited to the nuclear surface with a focus on elucidating the role of ASUN in this process. Our preliminary data suggest that dynein anchored on the nuclear surface of spermatocytes may preferentially bind to microtubules that are post-translationally modified by acetylation. We will test our hypothesis that this pool of acetylated microtubules mediates key events of Drosophila male meiosis, including nucleus-centrosome coupling. The proposed experiments have the potential to illuminate the mechanism of action of ASUN, to identify additional factors required for recruitment of the dynein motor complex to the nuclear surface, and to define the role of microtubule acetylation during spermatogenesis. PUBLIC HEALTH RELEVANCE: The mechanisms controlling localization of dynein motors within cells are not well understood. We have shown that ASUN is required for recruitment of dynein to the nuclear surface of Drosophila spermatocytes, a critical event for fidelity of meiotic divisions. Because the vertebrate homolog of ASUN also controls dynein localization in cultured human cells during mitosis, elucidation of the mechanism of action of ASUN may have important implications for human diseases such as cancer.

描述（由申请人提供）：细胞周期相关基因的高度功能保守性，加上黑腹果蝇卓越的遗传学和细胞学特性，使其成为研究发育背景下细胞周期调控的理想模型生物。精子发生利用有丝分裂和减数分裂细胞周期与生长和分化程序协调来产生功能性精子。通过突变分析，我们发现 asunder (asun) 编码一种进化上保守的蛋白质，是果蝇精子发生的重要调节因子。精母细胞在减数分裂 I 前期停滞。引人注目的是，停滞的精母细胞含有游离中心体，无法与细胞核稳定结合。克服停滞的精母细胞在减数分裂纺锤体组装、染色体分离和胞质分裂方面表现出严重缺陷。此外，在减数分裂后的精子细胞中，中心粒衍生的基体与细胞核分离，导致精子发生后期出现异常。我们发现asun精母细胞和精子细胞的核周动力蛋白急剧减少。动力蛋白是一种负端定向的微管运动复合物，是从细胞内货物运输到细胞迁移等多种生物过程所必需的。动力蛋白在多个层面上受到控制，包括其亚细胞定位的调节；然而，动力蛋白靶向细胞内不同位点的机制尚不清楚。我们目前的模型是，asun 通过促进动力蛋白募集到核表面来协调精子发生，这是 M 期进入时核-中心体耦合和减数分裂保真度所需的关键步骤。 ASUN 在果蝇雄性减数分裂过程中表现出动态定位模式，其从细胞核释放到细胞质的时间与 G2 精母细胞核表面动力蛋白的出现相关。我们将评估精母细胞内 ASUN 的这种受调节运动对于控制动力蛋白的活性是否至关重要。我们提出的实验将使我们能够更详细地了解动力蛋白被招募到核表面的机制，重点是阐明 ASUN 在此过程中的作用。我们的初步数据表明，锚定在精母细胞核表面的动力蛋白可能优先与通过乙酰化进行翻译后修饰的微管结合。我们将检验我们的假设，即乙酰化微管池介导果蝇雄性减数分裂的关键事件，包括核-中心体偶联。所提出的实验有可能阐明 ASUN 的作用机制，确定将动力蛋白运动复合体募集到核表面所需的其他因素，并确定微管乙酰化在精子发生过程中的作用。公共健康相关性：控制细胞内动力蛋白马达定位的机制尚不清楚。我们已经证明，ASUN 是果蝇精母细胞核表面募集动力蛋白所必需的，这是减数分裂保真度的关键事件。由于 ASUN 的脊椎动物同源物也控制有丝分裂期间培养的人类细胞中的动力蛋白定位，因此阐明 ASUN 的作用机制可能对癌症等人类疾病具有重要意义。