Mechanisms for new microtubule nucleation in the mitotic spindle

在所有真核生物中，准确的细胞分裂是生命所必需的。在发育过程中，我们从单个细胞开始，变成由大约40万亿个细胞组成的大型组件，这个细胞分裂过程一直持续到成年生活，以补充死亡的细胞。这一过程中的错误可能会导致细胞死亡、癌症或出生缺陷。细胞分裂涉及两个子细胞之间遗传物质的准确分离。这是通过形成一个双极有丝分裂纺锤体实现的，该纺锤体由数千个微管及其相关蛋白组成，它们与不同的马达和非马达蛋白协同作用，促进姐妹染色单体的分离。每条染色体通过其动粒与有丝分裂纺锤体相连，动粒是一个蛋白质盘，上面附着着约20个微管，形成动粒纤维(K-纤维)。最近的研究发现，在人类细胞中，K-纤维是由相互连接的被称为网状结构的蛋白质连接在一起的。这些蛋白质似乎组织了K纤维内的微管，并提供了稳定性，以确保准确的细胞分裂。我攻读博士学位的目的是研究TACC3在有丝分裂纺锤体中的作用，TACC3是以前发现的“网状结构”的组成部分。特别是，我将使用各种显微镜技术研究这种蛋白质在基因编辑的人类细胞系中潜在的相分离结构。我还将测试TACC3是否是有丝分裂纺锤体内新的微管生长的场所，以及是否需要它来稳定纺锤体内特定位置的微管。

Accurate cell division is essential for life in all eukaryotes. During development, we start life as a single cell and become large assemblies made of ~40 trillion cells, and this process of cell division continues into adult life to replenish dead cells. Errors in this process can lead to cell death, cancer or birth defects. Cell division involves the accurate segregation of genetic material between the two resulting daughter cells. This is achieved by the formation of a bipolar mitotic spindle, composed of thousands of microtubules (MTs) and their associated proteins which, in concert with different motors and non-motor proteins facilitates sister chromatid separation. Each chromosome is connected to the mitotic spindle via its kinetochore, a protein disc with ~20 microtubules attached to it forming a kinetochore fibre (K-fibre). Recent research has found that in human cells K-fibres are held together by interconnecting proteins termed the 'mesh'. These proteins appear to organise the microtubules within the K-fibre and provide stability to ensure accurate cell division. The aim of my PhD is to investigate the role of TACC3, a previously identified component of the 'mesh', within the mitotic spindle. In particular, I will investigate the potential phase separated structure of this protein in gene edited human cells lines using a variety of microscopy techniques. I will also test whether TACC3 is a site for new microtubule growth within the mitotic spindle and if it is required to stabilise microtubules at specific sites within the spindle.