Mechanisms for new microtubule nucleation in the mitotic spindle

精确的细胞分裂对于所有真核生物的生命都是必不可少的。在发育过程中，我们从一个单细胞开始生命，变成由约40万亿个细胞组成的大型集合体，这种细胞分裂过程持续到成年，以补充死亡的细胞。这个过程中的错误可能导致细胞死亡，癌症或出生缺陷。细胞分裂涉及遗传物质在两个子细胞之间的精确分离。这是通过形成双极有丝分裂纺锤体来实现的，该纺锤体由数千个微管（MT）及其相关蛋白组成，这些微管及其相关蛋白与不同的马达和非马达蛋白一起促进姐妹染色单体分离。每个染色体通过其动粒连接到有丝分裂纺锤体，动粒是一个蛋白质盘，约20个微管附着在其上，形成动粒纤维（K纤维）。最近的研究发现，在人类细胞中，K纤维是通过称为“网格”的相互连接的蛋白质保持在一起的。这些蛋白质似乎在K纤维内组织微管，并提供稳定性以确保准确的细胞分裂。我的博士学位的目的是研究TACC3的作用，TACC3是先前确定的“网格”的组成部分，在有丝分裂纺锤体中。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的潜在相分离结构。我还将测试TACC3是否是有丝分裂纺锤体内新微管生长的位点，以及是否需要它来稳定纺锤体内特定位点的微管。

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.