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 当染色体被基于微管的有丝分裂纺锤体分离后，胞质分裂完成 分裂，将母细胞的内容物分配给两个子细胞。胞质分裂是通过 在皮层上形成的围绕细胞的赤道带中的肌动球蛋白收缩环的收缩 赤道胞质分裂失败产生四倍体细胞，其是癌症发生中的常见中间体。 胞质分裂调节因子的上调和突变也与不同的癌症有关， 靶向胞质分裂作为潜在的化疗剂是令人感兴趣的，激发了理解细胞分裂的努力。 在胞质分裂期间形成皮质收缩的机制。为了确保每个子细胞都能接收到 在等基因组互补中，收缩环的位置由后期纺锤体指定。的 纺锤体向皮层发送两个叠加信号：（1）促进收缩环组装的正信号 这是由一组成束的微管产生的，称为中心纺锤体，它形成于分离的 （2）由微管星状体产生的负信号，抑制染色体的收缩性， 非赤道皮层拟议的工作集中在这两个信号的分子基础上， 共同地直接收缩环组件。正性信号促进收缩环的中心成分 组装体是centralspindlin，由驱动蛋白-6的二聚体和CYK 4的二聚体形成的四聚体复合物。 Centralspindlin被有丝分裂激酶PLK 1磷酸化，其集中在中心纺锤体上; 随后扩散到邻近的质膜，在那里，通过大量保留的机制， 不清楚，其CYK 4亚基与ECT 2鸟嘌呤核苷酸交换因子（GEF）接合并激活。 活性ECT 2又产生富含收缩环组装的主调节器的赤道区， RhoA-GTP在目标1中，我们解决了关于阳性胞质分裂信号传导的主要开放问题： centralspindlin激活ECT 2的机制。为了了解紫菀微管是如何抑制 在非赤道皮质的收缩，这发生在同一时间，作为积极的信号，从中央 纺锤体，我们开发了一种检测收缩环蛋白从C. 线虫胚胎使用这种测定，我们确定极光A激酶作为一个重要的介导者， 收缩抑制在目标2中，我们在这项工作的基础上确定了调节收缩性的Aurora A靶点 并将该机制扩展分析到人类细胞。目标3解决了以下方面的一个重要差距： 了解支持收缩环组装的细胞周期状态是如何产生的，并评估 是否胞质分裂的持续时间，像有丝分裂一样，由基于p53的有丝分裂秒表监测 从群体中消除潜在问题细胞的机制。