Revealing how the mitotic spindle controls asymmetric cell division in vivo

揭示有丝分裂纺锤体如何控制体内不对称细胞分裂

• 批准号: 10100123
• 负责人: Nicolas Daniel Plachta
• 金额: $ 44.03万
• 依托单位: UNIVERSITY OF PENNSYLVANIA
• 依托单位国家: 美国
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-09-18 至 2024-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10100123
• 关键词: Actomyosin; Adopted; Affect; Apical; Biophysical Process; Biophysics; Cell Differentiation process; Cell Nucleus; Cell Polarity; Cell Separation; Cell Volumes; Cell division; Cells; Centrioles; Centrosome; Chromosomes; Complex; Cultured Cells; Cytoskeletal Modeling; Data; Development; Elements; Embryo; Environment; Event; Exposure to; Fertility; Fetus; Generations; Germ Cells; Goals; Homeostasis; Image; Image Analysis; Imaging Techniques; In Vitro; Invertebrates; Lead; Mammalian Cell; Mechanics; Metaphase; Microtubule-Organizing Center; Microtubules; Mitosis; Mitotic; Mitotic Spindle Apparatus; Mitotic spindle; Molecular; Movement; Mus; Organism; Pattern; Physiological; Placenta; Play; Positioning Attribute; Prokaryotic Cells; Proteins; Regulation; Role; Shapes; Source; Testing; Tissues; Work; base; biophysical techniques; cell behavior; cell cortex; cell type; daughter cell; imaging approach; in vivo; insight; quantitative imaging; segregation; tumorigenesis

Summary The goal of this proposal is to discover how new forms of microtubule organization drive the first asymmetric cell divisions of a mammalian organism in vivo. One of the most salient features of multicellular organisms is their vast number of cell types. Many of these are produced by asymmetric cell division, in which a parental cell asymmetrically distributes cell fate determinants, or generates daughter cells with different shape, volume or cell polarity features. In most cell types, the mitotic spindle apparatus plays a fundamental role in asymmetric cell division. It comprises two key parts, the central spindle that interacts with chromosomes and promotes cytokinetic furrow formation, and an array of astral microtubules. These astral microtubules originate from centrosomes at the spindle poles and allow polarized cortical elements and force regulators to differentially control the spindle to drive asymmetric cell division. The mechanisms of asymmetric cell division have been studied in detail in cultured cells and non- mammalian organisms. Yet, the mouse embryo does not inherit centrioles form its parental cells and has been proposed to lack functional centrosomes and astral microtubule arrays. Therefore, it remains unclear how mitotic spindles are organized during the earliest stages of development, and how they may contribute to asymmetric cell division to drive the differentiation of the first mammalian cell types. Here, we combine live-imaging approaches with molecular and biophysical methods to test the function of a new form of mitotic spindle organization, which we found to drive asymmetric cell division in vivo. Unlike previous assumptions of lack of centrosomes and astral microtubule arrays, we found that some cells establish a highly asymmetric spindle with only one astral-like microtubule array. Manipulations of this asymmetric spindle disrupt the segregation of the first cell types. Thus, the central hypothesis of this proposal is that the establishment of this new form of asymmetric spindle organization drives the first asymmetric cell divisions in vivo. To test this, our aims will investigate the mechanisms by which the asymmetric spindle is assembled (Aim 1) and can drive asymmetric cell division (Aim 2). Aim 1 will specifically focus on dissecting the source and function of the molecular regulators required to assemble the asymmetric spindle, the role of cell polarity components, and the physical forces required to bring together the astral array and the central spindle to assemble a complete mitotic spindle apparatus. Aim 2 will investigate the mechanisms by which the asymmetric spindle drives asymmetric cell division. We will specifically test three fundamental mechanisms based on the differential regulation of cell cleavage orientation, daughter cell volume and cell cortex tension.

概括 该提案的目的是发现新形式的微管组织如何驱动第一个不对称单元 体内哺乳动物生物的分裂。多细胞生物最显着的特征之一是它们 大量的细胞类型。其中许多是由非对称细胞分裂产生的，其中一个亲本细胞 非对称分布细胞命运决定因素，或产生不同形状，体积或细胞的子细胞 极性特征。 在大多数细胞类型中，有丝分裂纺锤体在不对称细胞分裂中起着基本作用。它包括 两个关键部分，与染色体相互作用并促进细胞力学沟的形成的中心主轴， 以及一系列星体微管。这些星体微管起源于纺锤体的中心体 并允许极化的皮质元件，并迫使调节器差异地控制主轴以驱动不对称 细胞分裂。在培养细胞和非 - 非对称细胞分裂的机制已详细研究 哺乳动物生物。然而，小鼠胚胎不会遗传中心元素形成其亲本细胞，并且已经存在 建议缺乏功能性的中心体和星体微管阵列。因此，尚不清楚如何有丝分裂 纺锤体是在最早的开发阶段组织的，以及它们如何有助于不对称 细胞分裂驱动第一个哺乳动物细胞类型的分化。 在这里，我们将现场模仿方法与分子和生物物理方法结合在一起，以测试新的功能 有丝分裂纺锤体组织的形式，我们发现在体内驱动不对称的细胞分裂。与以前不同 缺乏中心体和星体微管阵列的假设，我们发现某些细胞建立了高度 不对称主轴仅具有一个星体样微管阵列。操纵这种不对称的主轴破坏 第一批细胞类型的分离。因此，该提议的核心假设是建立 这种新形式的不对称纺锤体组织在体内驱动了第一个不对称的细胞分裂。为了测试这一点， 我们的目标将调查组装不对称纺锤体的机制（AIM 1）并可以驱动 非对称细胞分裂（AIM 2）。 AIM 1将专门针对剖析所需分子调节剂的源和功能 组装不对称的主轴，细胞极性成分的作用以及带来的物理力 星形阵列和中央主轴一起组装一个完整的有丝分裂纺锤体。 AIM 2将研究不对称纺锤体驱动不对称细胞分裂的机制。我们将 根据细胞裂解方向的差异调节，特异性测试了三种基本机制， 子细胞体积和细胞皮层张力。