Mechanisms of mitosis and size control in Xenopus

非洲爪蟾有丝分裂和大小控制的机制

• 批准号: 10378687
• 负责人: Rebecca W Heald
• 金额: $ 87.01万
• 依托单位: UNIVERSITY OF CALIFORNIA BERKELEY
• 依托单位国家: 美国
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-04-12 至 2026-03-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10378687
• 关键词: Address; Affect; Architecture; Area; Automobile Driving; Biochemical; Biological; Biological Assay; Biology; Biophysical Process; Cell Nucleus; Cell Size; Cell division; Cell physiology; Cells; Centromere; Chromosome Condensation; Chromosome Segregation; Chromosomes; Ciona intestinalis; Collaborations; Computer Models; Conflict (Psychology); Cytoplasm; Cytoskeleton; DNA; Defect; Development; Embryo; Embryonic Development; Ensure; Event; Evolution; Gene Expression; Genome; Genomics; Hybrids; Interphase; Kinetochores; Laboratories; Lead; Life; Link; Malignant Neoplasms; Measures; Mediating; Meiosis; Microfluidics; Microscopy; Microtubules; Mitosis; Mitotic; Mitotic Chromosome; Mitotic spindle; Molecular; Morphology; Oocytes; Organelles; Organism; Phylogenetic Analysis; Physiology; Ploidies; Process; Proteomics; Rana; Research; Resolution; Role; Shapes; Structure; Surface; System; Techniques; Testing; Time; Urochordata; Xenopus; base; cell type; chromosome missegregation; daughter cell; egg; embryo cell; human disease; in vivo; innovation; insight; laser tweezer; novel; novel strategies; reproductive; segregation; sensor; single molecule; sperm cell; virtual; xenopus development

PROJECT SUMMARY Mechanisms of Mitosis and Size Control in Xenopus Research in my laboratory is focused on two major areas: Cell division is arguably the most dramatic event in the life of a cell. Chromosomes condense, organelles vesiculate, and the microtubule cytoskeleton rearranges into a bipolar spindle that attaches to chromosomes at their kinetochores and segregates a complete genome to each daughter cell. Although the morphological changes that occur during mitosis were first observed over a century ago, we still do not understand how these dynamic events are orchestrated. Many factors have been identified that contribute to spindle assembly and function, but the molecular and biophysical mechanisms and interactions that ensure mitotic fidelity remain unclear. Our current projects address outstanding questions including 1) What are the molecular underpinnings and functional consequences of different spindle architectures? Spindle size and organization vary dramatically across cell types and organisms, and factors known to affect these parameters are altered in many cancers, but how specific spindle features are established and their effects on chromosome segregation and cell division are poorly understood. We will leverage morphometric and phylogenetic comparisons together with biochemical and functional assays to investigate the dramatic changes in spindle architecture that occur between oocyte meiosis and the mitotic divisions of early development in Xenopus and the sea squirt Ciona intestinalis. We will elucidate the role of specific factors in this transition, and examine the consequences of altering spindle architecture on embryo cell division. 2) What defects in cell division mechanisms underlie speciation? We have observed chromosome mis-segregation in inviable hybrids generated by fertilizing Xenopus tropicalis eggs with X. laevis sperm, and identified incompatibility between a subset of paternal centromeres and maternal cytoplasm as one underlying cause. We will elucidate the molecular basis of inter-species conflicts that impact cell division and contribute to reproductive isolation. 3) What is the molecular basis of mitotic chromosome condensation? We have developed a novel approach using optical tweezers to measure the dynamics of single DNA molecules in real-time in Xenopus egg extracts with high spatial and temporal precision and will use this system to dissect the roles of key factors in driving mitotic chromosome assembly. Absolute and relative size of biological entities varies widely, both within and among species at all levels of organization above the atomic/molecular: the organism, the cells that make up the organism, and the cellular components. How does scaling occur so that everything fits and functions properly? Correct scaling inside cells is crucial for cell function, architecture, and division, but until recently the control systems that a cell uses to regulate the size of its internal structures were virtually unknown. We have established assays to elucidate mechanisms of intracellular scaling between different-sized frog species and during the rapid, reductive cell divisions of early embryogenesis. We are further developing these systems to ask: 1) What scales mitotic chromosome size to cell size? We are testing the hypothesis that a surface area to volume sensor acting on the interphase nucleus and the mitotic spindle also coordinately adjusts mitotic chromosomes to cell size during Xenopus development. 2) What are the connections between genome size, cell size, physiology, and development? Cell size correlates strongly with genome size across evolution, but underlying mechanisms are unknown. We will utilize different ploidy frog embryos to address how altering genome size affects gene expression, and a variety of species including the dodecaploid frog Xenopus longipes to investigate relationships between genome size, cell division mechanisms, development, and physiology. The means to address these fundamental cell biological questions is enabled by powerful experimental systems based on cytoplasmic extracts and functional in vivo assays in vertebrate (Xenopus) embryos. We have established productive collaborations and apply diverse techniques including high-resolution microscopy, single molecule assays, genomics, proteomics, microfluidics and computational modeling to fill important conceptual gaps in an innovative, rigorous, and interdisciplinary manner. Our research will continue to provide novel insight into cell division and size control, processes essential for viability and development, and defective in human diseases including cancer. Although introduced as distinct topics, cell division and size control are intimately linked. We are increasingly focused on how cross-species comparisons can elucidate molecular mechanisms underlying cell division and size control, as well as how biological constraints related to these processes have shaped evolution. Together, these projects uniquely advance our understanding of long-standing questions in biology.

项目摘要 有丝分裂的机制和爪蟾的尺寸控制 我的实验室的研究集中在两个主要领域： 细胞分裂可以说是细胞生命中最戏剧性的事件。染色体凝结，细胞器 囊泡，微管细胞骨架重排成双极主轴，该双极轴连接到染色体上 他们的动力学并将一个完整的基因组分离到每个子细胞。虽然是形态学 一个世纪前首次观察到有丝分裂过程中发生的变化，我们仍然不了解 这些动态事件如何精心策划。已经确定了许多有助于主轴的因素 组装和功能，但分子和生物物理机制和相互作用可确保有丝分裂 保真度仍然不清楚。我们目前的项目解决了未出色的问题，包括1）分子是什么 不同主轴架构的基础和功能后果？主轴尺寸和组织 在细胞类型和生物体之间发生巨大变化，并且已知影响这些参数的因素发生了变化 许多癌症，但是如何建立特定的主轴特征及其对染色体隔离的影响 和细胞分裂知之甚少。我们将共同利用形态计量和系统发育比较 使用生化和功能性测定来研究发生纺锤体体系结构的巨大变化 在Xenopus和Sea Squirt Ciona的早期发育的有丝分裂分裂之间 肠道。我们将阐明特定因素在此过渡中的作用，并检查 改变胚细胞部门的主轴结构。 2）细胞分裂机制的缺陷是什么 物种？我们已经观察到通过受精的Xenopus产生的不可或缺的混合体中的染色体错误分离 带有X. laevis精​​子的热带鸡蛋，并确定了父亲的centromeres和 母体细胞质是一个根本原因。我们将阐明种间间的分子基础冲突 撞击细胞分裂并有助于生殖隔离。 3）什么是有丝分裂染色体的分子基础 缩合？我们已经开发了一种使用光学镊子来测量单个动力学的​​新颖方法 DNA分子在具有高空间和时间精度的Xenopus卵提取物中实时实时，并将使用此 剖析关键因素在驱动有丝分裂染色体组装中的作用的系统。 生物实体的绝对和相对大小在各个层面的物种内部和物种之间都有很大差异 原子/分子上方的组织：有机体的生物体，构成生物的细胞和细胞 成分。如何进行缩放以使一切都适合和正常运行？在内部正确缩放 细胞对于细胞功能，体系结构和除法至关重要，但是直到最近，控制系统 细胞用于调节其内部结构大小的用途实际上未知。我们已经建立了测定 阐明不同大小的青蛙物种之间的细胞内尺度机制以及在快速的过程中 早期胚胎发生的还原细胞分裂。我们正在进一步开发这些系统以询问：1）什么尺度 有丝分裂染色体大小到细胞大小？我们正在测试一个假设，即表面积到体积传感器作用 在相间核和有丝分裂的纺锤体上还协调将有丝分裂染色体调整为细胞大小 在Xenopus开发过程中。 2）基因组大小，细胞大小，生理学和 发展？细胞大小与进化过程中的基因组大小密切相关，但潜在的机制是 未知。我们将利用不同的蛋白青蛙胚胎来解决改变基因组大小如何影响基因 表达和多种物种在内 在基因组大小，细胞分裂机制，发育和生理学之间。 强大的实验系统实现了解决这些基本细胞生物学问题的方法 基于脊椎动物（Xenopus）胚胎中的细胞质提取物和功能性在体内测定。我们有 建立的生产合作和应用多种技术，包括高分辨率显微镜，单一 分子测定，基因组学，蛋白质组学，微流体和计算建模，以填充重要的概念 以创新，严格和跨学科的方式差距。我们的研究将继续提供新颖的见解 进入细胞分裂和尺寸控制，对生存力和发育必不可少的过程，在人类中有缺陷 包括癌症在内的疾病。尽管引入了不同的主题，但细胞分裂和尺寸控制密切相关 链接。我们越来越关注跨物种比较如何阐明分子机制 潜在的细胞分裂和大小控制，以及与这些过程相关的生物学约束如何具有 形状进化。这些项目共同提出了我们对长期存在问题的理解 生物学。