Spindle orientation along the developmental axes in echinoderm embryos

棘皮动物胚胎沿发育轴的纺锤体方向

• 批准号: 8733008
• 负责人: Charles Bradley Shuster
• 金额: $ 42.65万
• 依托单位: NEW MEXICO STATE UNIVERSITY LAS CRUCES
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-08-15 至 2018-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8733008
• 关键词: Ablation; Animal Model; Animals; Apical; Asses; Biological Models; Caenorhabditis elegans; Cell Count; Cell Nucleus; Cell Polarity; Cell Size; Cell division; Cells; Centrosome; Complex; Cues; Cytoskeleton; Data; Development; Developmental Biology; Drosophila genus; Dynein ATPase; Embryo; Endomesoderm; Event; Exhibits; Exposure to; Fertilization; Genetic; Germ Layers; Grant; Image; Institution; Invertebrates; Lead; Life; Microtubules; Minority; Mitosis; Mitotic Spindle Apparatus; Mitotic spindle; Modeling; Molecular; Motor; Nuclear; Optics; Organism; Pattern; Phase; Play; Population; Positioning Attribute; Publishing; Radial; Relative (related person); Research; Role; Sea Urchins; Series; Signal Pathway; Solid; Specific qualifier value; Staging; Starfish; Stem cells; Students; System; Testing; base; cell type; cellular imaging; combinatorial; daughter cell; egg; embryo stage 2; insight; migration; neuroblast; novel; public health relevance; segregation; zygote

DESCRIPTION (provided by applicant): A common feature of animal development is that following fertilization, embryos undergo a species-specific, stereotypical pattern of cleavages that sequester developmental determinants into specific daughter cells. And while lineage tracing and cell ablation studies have firmly established the significance of these developmentally asymmetric cell divisions, study of the mechanisms that align the mitotic spindle relative to the developmental axes has been largely limited to a few model organisms. Sea urchins undergo radial cleavage, with each cleavage plane bisecting the plane of the previous division. By the end of the fourth division, factors associated with the vegetal cortex ar sequestered by asymmetric cell division into a population of cells that will in turn direct the formation of the endomesoderm. And despite the intense scrutiny placed on the developmental role of micromeres in sea urchins and asymmetric cell division in other systems, we understand little of the mechanisms that facilitate spindle positioning relative to the animal-vegetal axis during echinoderm development. In almost all cell types studied to date, the mitotic spindle obeys Hertwig's rule and aligns itself along the long axis of the cell, facilitated by cortical puling forces generated by the microtubule motor, dynein. This proposal seeks to understand how the mitotic spindle is positioned relative to developmental axes during the initial cleavages of the sea urchin embryo. We hypothesize that factors that define cell polarity in early blastomeres align the nucleus and its duplicated centrosomes prior to the onset of mitosis to influence spindle orientation during both symmetric and asymmetric cell division. To test this hypothesis, we will perform a series of live cell analyses in sea urchin and starfish embryos, whose complementary features will aid in defining what we believe is a highly conserved mechanism for spindle alignment in early embryos. The lines of experimentation that form the Specific Aims of this proposal will: 1) Define the role of the PAR complex in defining blastomere polarity and spindle orientation during early cleavage; and 2) Assess the role of polarity factors and Disheveled during micromere formation. Together, is anticipated that the these studies will lead to a mechanistic understanding of how polarity factors act to effect a highly stereotypical and precise pattern of cell divisions that will ultimately lead to axis determination and the specification of the germ layers on echinoderm embryos.

描述（由申请人提供）：动物发育的一个共同特征是受精后，胚胎经历物种特异性的、刻板的卵裂模式，将发育决定因素隔离到特定的子细胞中。虽然谱系追踪和细胞消融研究已经牢固地确立了这些发育不对称细胞分裂的意义，但有丝分裂纺锤体相对于发育轴对齐的机制的研究在很大程度上限于少数模式生物。海胆经历放射状卵裂，每个卵裂平面平分前一个分裂的平面。到第四次分裂结束时，与植物皮层相关的因子通过不对称的细胞分裂被隔离成一群细胞，这些细胞反过来将指导内中胚层的形成。尽管对海胆中微粒体的发育作用和其他系统中的不对称细胞分裂进行了严格的审查，但我们对棘皮动物发育过程中促进纺锤体相对于动物-植物轴定位的机制知之甚少。 在迄今为止研究的几乎所有细胞类型中，有丝分裂纺锤体遵循Hertwig规则，并在微管马达动力蛋白产生的皮质拉动力的促进下沿着细胞的长轴沿着。这项建议旨在了解如何有丝分裂纺锤体定位相对于发展轴在最初的卵裂的海胆胚胎。我们假设，在早期卵裂球中定义细胞极性的因素在有丝分裂开始之前使细胞核及其复制的中心体对齐，以影响对称和不对称细胞分裂期间的纺锤体取向。为了验证这一假设，我们将在海胆和海星胚胎中进行一系列活细胞分析，其互补特征将有助于定义我们认为是早期胚胎中纺锤体对齐的高度保守机制。形成本提案具体目标的实验路线将：1）确定PAR复合物在早期卵裂过程中定义卵裂球极性和纺锤体取向的作用; 2）评估极性因子和Disheveled在微球形成过程中的作用。 总之，预计这些研究将导致极性因子如何作用于影响高度定型和精确的细胞分裂模式的机制性理解，这将最终导致轴确定和棘皮动物胚胎上胚层的规格。