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: 10470177
• 负责人: Nicolas Daniel Plachta
• 金额: $ 44.14万
• 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/10470177
• 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 该提案的目标是发现新形式的微管组织如何驱动第一个不对称细胞 哺乳动物体内有机体的分裂。多细胞生物最显着的特征之一是它们 大量的细胞类型。其中许多是由不对称细胞分裂产生的，其中亲代细胞 不对称地分布细胞命运决定因素，或产生具有不同形状、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发挥着重要作用。它包括 两个关键部分，与染色体相互作用并促进细胞分裂沟形成的中央纺锤体， 和一系列星体微管。这些星体微管起源于纺锤体两极的中心体 并允许极化皮质元件和力调节器有差别地控制主轴以驱动不对称 细胞分裂。不对称细胞分裂的机制已在培养细胞和非细胞中进行了详细研究。 哺乳动物有机体。然而，小鼠胚胎并没有从其亲本细胞继承中心粒，并且已经被 提议缺乏功能性中心体和星体微管阵列。因此，目前尚不清楚有丝分裂是如何进行的 纺锤体在发育的最早阶段被组织起来，以及它们如何导致不对称 细胞分裂驱动第一种哺乳动物细胞类型的分化。 在这里，我们将实时成像方法与分子和生物物理方法相结合来测试新的功能 有丝分裂纺锤体组织的形式，我们发现它在体内驱动不对称细胞分裂。与之前不同 假设缺乏中心体和星体微管阵列，我们发现一些细胞建立了高度 不对称纺锤体，只有一个星体状微管阵列。这种不对称纺锤体的操纵会破坏 第一种细胞类型的分离。因此，该提案的中心假设是建立 这种新形式的不对称纺锤体组织驱动了体内第一次不对称细胞分裂。为了测试这一点， 我们的目标是研究非对称主轴的组装机制（目标 1）并驱动 不对称细胞分裂（目标 2）。 目标 1 将特别关注剖析所需分子调节剂的来源和功能 组装不对称纺锤体，细胞极性成分的作用，以及带来所需的物理力 星体阵列和中心纺锤体一起组装成完整的有丝分裂纺锤体装置。 目标 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 具体测试基于细胞分裂方向差异调节的三种基本机制， 子细胞体积和细胞皮层张力。