Mechanism of centrosome maturation in vertebrates

项目摘要/摘要 在有丝分裂过程中，染色体的准确分离依赖于正确组装的纺锤体装置， 中心体在其两侧锚定有丝分裂的微管。中心体是一个主要的微管- 动物细胞的组织中心(MTOC)。它由一对中心粒组成，中心粒周围环绕着中心粒。 材料(PCM)。PCM成核和锚定微管，从而决定MTOC的活性。 中心体。中心体在有丝分裂开始时迅速扩张其PCM。这个过程被称为中心体 成熟是纺锤体组织和染色体分离的关键。然而，有一个基本的 在了解PCM在有丝分裂开始时如何组装和调节方面存在差距。此外，虽然 中心体成熟的框架已在分子水平上阐明，其基本原理是 PCM组装在细胞器水平上仍然难以捉摸--没有封闭的膜，是什么使PCM保持 拥挤的PCM蛋白不能分散？是什么胶水把这个无膜的整体粘在一起，就像一个微米- 有丝分裂期间中心体的大小？在脊椎动物中，中心体成熟部分是由中心周围蛋白驱动的 (PCNT)，一种与人类发育障碍有关的大型PCM蛋白，包括原始dwarfism， 小头畸形症和唐氏综合症。PCNT作为一种支架在其他PCM蛋白的招募过程中 中心体成熟。我们最近的工作表明，PCNT是通过共翻译的方式传递给有丝分裂的 中心体和PCNT的这种共翻译靶向促进了中心体的成熟。我们的长期目标 就是了解中心体是如何组装和运作的。总体目标是阐明这一角色 PCNT在调节中心体成熟和PCM组装中的作用。根据我们最近的工作和初步的 研究中，我们假设共翻译蛋白靶向通过邻近促进PCNT相分离- 驱动缩合，一种促进适当的PCM组装的过程，并且PLK1调节co- 翻译靶向过程以及它在有丝分裂中心体中的作用。我们将在下面测试我们的假设 fic的三个目标：(1)确定PCNT缩合在中心体成熟中的贡献，(2) 确定共翻译靶向与PCNT相分离的关系，以及(3) 确定Dynein和PLK1调节共翻译靶向的分子机制 PCNT。脊椎动物细胞中心体组装的分子机制尚不清楚 已澄清。了解这些过程是充分理解中心体功能的关键 在人类疾病中通常受到调节和干扰。

Project Summary/Abstract Faithfully segregating chromosomes during mitosis relies on a properly assembled spindle apparatus with centrosomes anchoring mitotic microtubules on both sides of it. The centrosome is a major microtubule- organizing center (MTOC) in animal cells. It consists of a pair of centrioles surrounded by the pericentriolar material (PCM). The PCM nucleates and anchors microtubules and thus dictates the MTOC activity of the centrosome. Centrosomes rapidly expand their PCM at the onset of mitosis. This process, termed centrosome maturation, is critical for spindle organization and chromosome segregation. However, there is a fundamental gap in understanding how the PCM is assembled and regulated at the onset of mitosis. In addition, while the framework of centrosome maturation has been elucidated at the molecular level, the fundamental principle of PCM assembly remains elusive at the organellar level—without an enclosing membrane, what keeps the crowded PCM proteins from dispersing? What glue holds this membraneless ensemble together as a micron- sized centrosome during mitosis? In vertebrates, centrosome maturation is driven in part by pericentrin (PCNT), a large PCM protein linked to human developmental disorders, including primordial dwarfism, microcephaly, and Down syndrome. PCNT acts as a scaffold in the recruitment of other PCM proteins during centrosome maturation. Our recent work reveals that PCNT is delivered co-translationally to mitotic centrosomes and this co-translational targeting of PCNT facilitates centrosome maturation. Our long-term goal is to understand how the centrosome is assembled and functions. The overall objective is to elucidate the role of PCNT in regulating centrosome maturation and PCM assembly. Based on our recent work and preliminary studies, we hypothesize that co-translational protein targeting promotes PCNT phase separation via proximity- driven condensation, a process that facilitates proper PCM assembly, and that PLK1 regulates the co- translational targeting process in addition to its role at the mitotic centrosome. We will test our hypothesis in three specific aims: (1) determine the contribution of PCNT condensation in centrosome maturation, (2) determine the relationship between co-translational targeting and phase separation of PCNT, and (3) determine the molecular mechanisms through which dynein and PLK1 regulate co-translational targeting of PCNT. The molecular mechanisms underlying centrosome assembly in vertebrate cells remain to be elucidated. Understanding these processes is the key to fully understanding how centrosome function is normally regulated and disrupted in human disease.