Role of septins in cytokinetic abscission

项目摘要 癌症仍然是全球主要的死亡原因。在美国，有超过150万例新诊断和 每年有50万人死亡。90%以上的实体肿瘤(如乳房、结直肠)的特征是 染色体异常，包括非整倍体，染色体的丢失或获得，这是导致 推动癌症发展的基因组不稳定性。非整倍体由染色体缺陷引起 有丝分裂期间的分离。在有丝分裂后期， 连接两个隔间的细胞间桥(ICB) 一个分裂的细胞被称为脱落的过程所切断。脱落提供了一种延迟细胞的机制 在ICB中存在错误分离的染色体(NoCut检查点)的情况下进行分裂。因此， 脱落和NoCut检查点的缺陷会导致非整倍体和染色体损伤。离位 包括由内吞分选复合体收缩和切断ICB膜，这是 运输-III(ESCRT-III)。这种多组分膜复合体的组装是在空间和时间上的 受调控，需要靶向携带ESCRT-III的内体并与ICB融合。到目前为止， 然而，关于ESCRT-III组装是如何时空协调的知之甚少。 内体融合以及它如何与NoCut检查点联系在一起。Septins是一种GTP结合蛋白，是 在许多癌症中异常表达。隔膜组装成控制空间的更高级别的结构 膜和胞质蛋白的组织。在酵母中，隔膜蛋白对于空间协调是必不可少的。 胞质分裂。在哺乳动物细胞中，间隔蛋白是完成脱落所必需的，但它们的功能是 人们对此知之甚少。根据初步数据，我们假设Septins调节细胞的组装 ESCRT-III复合体。在这里，我们将确定Septins在ESCRT的招募和组装中的作用- III亚基形成环状和螺旋状细丝。我们将测试Septin在ESCRT的空间组织中的作用- III复合体及其组份的内吞给药。重要的是，拟议的工作将审查如何 Septin表达异常在癌症中很常见，它会影响NoCut检查点。建议数 研究需要培训光学和电子显微镜(EM)的尖端方法，包括结构化的 照明超分辨率显微镜和相关的光和铂复制品EM。的首要目标是 这一博士前奖学金项目是为在细胞和更广泛的领域从事独立职业做准备。 癌症生物学。综上所述，拟议的项目将为细胞运动的机制提供新的见解 脱落和隔膜蛋白，它们在许多癌症中异常表达，但它们的作用仍然很差 明白了。

Project Summary Cancer remains a leading cause of death worldwide. In the US, there are over 1.5 million new diagnoses and half million deaths annually. Over 90% of solid tumors (e.g., breast, colorectal) are characterized by chromosomal abnormalities including aneuploidy, the loss or gain of chromosomes, which contributes to the genomic instability that drives cancer development. Aneuploidy arises from defects in chromosome segregation during mitosis. In late mitosis, the intercellular bridge (ICB) that connects the two compartments of a dividing cell is severed by a process termed abscission. Abscission provides a mechanism for delaying cell division in the presence of missegregated chromosomes (NoCut checkpoint) that are trapped in the ICB. Thus, defects in abscission and the NoCut checkpoint result in aneuploidy and chromosome damage. Abscission involves the constriction and severing of the ICB membrane by the endocytic sorting complex required for transport-III (ESCRT-III). Assembly of this multi-component membrane complex is spatially and temporally regulated, and requires the targeting and fusion of ESCRT-III-carrying endosomes with the ICB. To date, however, very little is known about of how ESCRT-III assembly is spatio-temporally coordinated with endosome fusion and how it is linked to the NoCut checkpoint. Septins are GTP-binding proteins that are abnormally expressed in many cancers. Septins assemble into higher order structures that control the spatial organization of membrane and cytosolic proteins. In yeast, septins are essential for the spatial coordination of cytokinesis. In mammalian cells, septins are required for the completion of abscission, but their functions are poorly understood. Based on preliminary data, we hypothesize that septins regulate the assembly of the ESCRT-III complex. Here, we will determine how septins function in the recruitment and assembly of ESCRT- III subunits into rings and spiral filaments. We will test for septin roles in the spatial organization of the ESCRT- III complex and the endosomal delivery of its components. Importantly, the proposed work will examine how abnormalities in septin expression, which are common in cancer, affect the NoCut checkpoint. The proposed studies require training in cutting edge methods of light and electron microscopy (EM) including structured illumination super-resolution microscopy and correlative light and platinum replica EM. The overarching goal of this pre-doctoral fellowship project is to prepare for an independent career in the broader areas of cell and cancer biology. In summary, the proposed project will shed new insights into the mechanisms of cytokinetic abscission and septins, which are abnormally expressed in many cancers, but their roles remain poorly understood.