Mechanisms of Cytokinesis

细胞分裂的机制

• 批准号: 10675754
• 负责人: Karen F Oegema
• 金额: $ 46.78万
• 依托单位: UNIVERSITY OF CALIFORNIA, SAN DIEGO
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-08-02 至 2026-07-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10675754
• 关键词: Actomyosin; Address; Anaphase; Biological Assay; C-terminal; CDC2 gene; Caenorhabditis elegans; Cell Cycle; Cell division; Cell membrane; Cells; Centrosome; Chromosome Segregation; Chromosomes; Competence; Complement; Complex; Cyclin B; Cytokinesis; Cytoplasm; DNA biosynthesis; Data; Diffusion; Dimensions; Embryo; Failure; Family; GTPase-Activating Proteins; Genetic Code; Genomics; Goals; Guanine Nucleotide Exchange Factors; Guanosine Triphosphate; Guanosine Triphosphate Phosphohydrolases; Human; Investments; Kinesin; Life; Malignant Neoplasms; Measures; Mediating; Mediator; Microtubule Bundle; Microtubules; Mitosis; Mitotic; Mitotic spindle; Modeling; Molecular; Monitor; Mothers; Mutation; N-terminal; Nuclear; Organism; PLK1 gene; Pattern; Phase; Phosphorylation; Phosphotransferases; Population; Positioning Attribute; Process; Proteasome Inhibition; Proteins; Role; Signal Transduction; Specific qualifier value; System; TP53 gene; Tertiary Protein Structure; Testing; Time; Up-Regulation; Work; aurora kinase A; chemotherapeutic agent; constriction; daughter cell; dimer; genome integrity; inhibitor; interest; permissiveness; preservation; prevent; rho; screening

PROJECT SUMMARY After the chromosomes are segregated by the microtubule-based mitotic spindle, cytokinesis completes cell division, partitioning the contents of the mother cell to the two daughter cells. Cytokinesis is accomplished by constriction of an acto-myosin contractile ring that forms on the cortex in an equatorial band encircling the cell equator. Cytokinesis failure generates tetraploid cells that are a common intermediate in the genesis of cancers. Upregulation and mutation of cytokinesis regulators has also been implicated in different cancers, and inhibitors targeting cytokinesis are of interest as potential chemotherapeutic agents, motivating efforts to understand the mechanisms that pattern cortical contractility during cytokinesis. To ensure that each daughter cell receives an equivalent genomic complement, the position of the contractile ring is specified by the anaphase spindle. The spindle sends two superimposed signals to the cortex: (1) a positive signal promoting contractile ring assembly that is generated by set of bundled microtubules, called the central spindle, that forms between the separating chromosomes, and (2) a negative signal generated by the microtubule asters that suppresses the contractility of the non-equatorial cortex. The proposed work focuses on the molecular basis for these two signals that collectively direct contractile ring assembly. A central component of the positive signal promoting contractile ring assembly is centralspindlin, a tetrameric complex formed by a dimer of kinesin-6 and a dimer of CYK4. Centralspindlin is phosphorylated by the mitotic kinase PLK1, which concentrates on the central spindle; it subsequently diffuses to the adjacent plasma membrane where, through mechanisms that remain largely unclear, its CYK4 subunit engages with and activates the ECT2 guanine nucleotide exchange factor (GEF). Active ECT2 in turn generates an equatorial zone enriched for the master regulator of contractile ring assembly, RhoA-GTP. In Aim 1, we address the major open question with respect to positive cytokinesis signaling: the mechanism of ECT2 activation by centralspindlin. To understand how the microtubule asters suppress contractility on the non-equatorial cortex, which occurs at the same time as positive signaling from the central spindle, we developed an assay monitoring clearing of contractile ring proteins from the cell poles in the C. elegans embryo. Using this assay, we identified Aurora A kinase as an essential mediator of aster-based contractility suppression. In Aim 2, we build on this work to identify the Aurora A targets that mediate contractility suppression and extend analysis of this mechanism to human cells. Aim 3 addresses an important gap in understanding how the cell cycle state that supports contractile ring assembly is generated, and assesses whether the duration of cytokinesis, like that of mitosis, is monitored by a p53-based mitotic stopwatch mechanism that eliminates potentially problematic cells from the population.

项目摘要 基于微管的有丝分裂纺锤体隔离染色体后，细胞因子完成细胞 分裂，将母细胞的内容分配给两个子细胞。细胞因子是通过 在环绕细胞的赤道带上形成的赤道带上形成的肌动蛋白收缩环的收缩环的收缩环 赤道。细胞因子衰竭会产生四倍体细胞，这些细胞是癌症起源中常见中间体。 细胞因子调节剂的上调和突变也与不同的癌症有关 靶向细胞因子是潜在的化学治疗剂，激发了理解的努力 细胞因子过程中皮质收缩的机制。确保每个女儿细胞都会收到一个 等效基因组补体，收缩环的位置由后期纺锤体指定。这 主轴向皮层发送两个叠加信号：（1）促进收缩环组件的正信号 这是由一组捆绑的微管（称为中央主轴）生成的，在分离之间形成 染色体和（2）微管产生的负信号抑制了抑制的收缩力 非赤道皮层。拟议的工作重点是这两个信号的分子基础， 集体直接收缩环组件。正信号促进收缩环的一个核心部分 组装是Centralspindlin，这是一种由驱动蛋白6的二聚体和Cyk4二聚体形成的四聚体络合物。 Centralspindlin被丝分裂激酶PLK1磷酸化，该酶激酶PLK1集中在中央主轴上。它 随后扩散到相邻的质膜 尚不清楚，其CYK4亚基与ECT2鸟嘌呤核苷酸交换因子（GEF）接合并激活。 Active ECT2反过 Rhoa-GTP。在AIM 1中，我们解决了有关阳性细胞因子信号传导的主要开放问题： Centralspindlin激活ECT2激活的机理。了解微管如何抑制 非赤道皮质的收缩性，该皮质与中央的正信号同时发生 主轴，我们开发了一种从C中的细胞两极的收缩环蛋白的测定监测清除。 秀丽隐杆线胚。使用此测定，我们将Aurora A激酶确定为基于Aster的基本介体 抑制收缩力。在AIM 2中，我们以这项工作为基础，以确定介导收缩力的Aurora A目标 抑制并将这种机制分析扩展到人类细胞。 AIM 3解决了一个重要的差距 了解如何生成支持收缩环组件的细胞周期状态，并评估 是否像有丝分裂的细胞因子的持续时间都由基于p53的有丝分裂秒表监测 消除了人群中潜在有问题的细胞的机制。