Mechanism of centrosome maturation in vertebrates

项目总结/摘要 在有丝分裂过程中，染色体的正确分离依赖于正确组装的纺锤体， 中心体在其两侧锚定有丝分裂微管。中心体是一个主要的微管- 组织中心（MTOC）。它由一对中心粒和一对围绕中心粒的 材料（PCM）。PCM使微管成核并锚定，从而决定微管的MTOC活性。 中心体中心体在有丝分裂开始时迅速扩大其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 在理解PCM如何在有丝分裂开始时组装和调节方面存在差距。此外，虽然 中心体成熟的框架已经在分子水平上阐明， PCM组装在细胞器水平上仍然难以捉摸-没有封闭的膜，是什么保持了PCM的功能？ 拥挤的PCM蛋白质分散吗是什么胶水把这个无膜的整体粘合在一起，就像微米一样- 在有丝分裂过程中的中心体大小？在脊椎动物中，中心体成熟部分由中心周蛋白驱动， （PCNT），一种与人类发育障碍有关的大型PCM蛋白，包括原始侏儒症， 小头畸形和唐氏综合症PCNT作为一个支架在其他PCM蛋白的招聘过程中， 中心体成熟我们最近的工作表明，PCNT是协同传递到有丝分裂， PCNT的这种共翻译靶向促进中心体成熟。我们的长期目标 就是了解中心体是如何组装和发挥作用的。总体目标是阐明 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- 驱动冷凝，一个过程，有利于适当的PCM组装，PLK 1调节共- 除了在有丝分裂中心体的作用外，它还参与翻译靶向过程。我们将测试我们的假设， 三个具体目标：（1）确定PCNT凝聚在中心体成熟中的贡献，（2） 确定PCNT的共翻译靶向和相分离之间的关系，以及（3） 确定动力蛋白和PLK 1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仍有待进一步研究。 阐明。理解这些过程是完全理解中心体功能的关键 在人类疾病中正常调节和破坏。

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.