Kinetochore life-histories: understanding the mechanical events that ensure error-free chromosome segregation

着丝粒生命史：了解确保无差错染色体分离的机械事件

基本信息

批准号：
BB/R009503/1
负责人：
Andrew McAinsh
金额：
$ 140.84万
依托单位：
University of Warwick
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2018
资助国家：
英国
起止时间：
2018 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=BB%2FR009503%2F1
关键词：
Kinetochore life histories understanding mechanical

项目摘要

A fundamental challenge in modern cell biology is to understand how complex behaviours emerge from populations of molecular machines, machines that work close to the thermal energy level, thereby giving their behaviour a significant random component, whilst working independently within the context of a global communication network. Working with such systems poses significant challenges given their small size; however recent advances in light microscopy has enabled these systems to be observed and quantified with unprecedented spatial and time resolution. The biological system we are interested in is how chromosomes are separated during cell division. Human beings are built from a single fertilised cell, the zygote. Each cell contains 46 chromosomes - the packages of genetic material (DNA), which provide the instructions for how a cell should work and how to build a human. Cells divide generating two near identical daughter cells. The chromosomes are copied prior to division and a key part of cell division is the accurate separation of these replicated chromosomes such that each daughter receives 1 and only 1 copy. Failure of a cell to receive a complete set of 46 chromosomes is a cause of multiple human diseases, including cancers and Down's syndrome. During the mechanical process of cell division, most of the time is taken up with relocating the paired chromosomes (original and copy) into a holding pattern at the equatorial plane, prior to pulling the pairs apart to either end of the cell. Clearly it is vital that we work out how chromosome separation works.Chromosome separation is a mechanical spatial process. To move a chromosome the cell makes use of molecular cables called microtubules that can grow and shrink. Each chromosome has a "hook" called the kinetochore, which attach to these cables, both on their sides (lateral attachment) and to the ends of these cables. The kinetochore is an extremely versatile and 'intelligent' machine, comprising sensors and motors that allow it to determine how it is attached to microtubules and how its paired sister is attached, making a sequence of informed decisions so that the paired chromosomes are relocated to the equatorial plane. The kinetochore is thus the "control centre" that decides when and where a chromosome moves. But, how does the kinetochore do this? Why and how do kinetochores make decisions, and using what information as input? The experiments that we propose to carry out will help answer these exciting and intriguing question and therefore advance our understanding of how chromosomes are faithfully separated into daughter cells during cell division.We will use state-of-the-art imaging technology (microscopes) to observe how chromosomes move in living human cells. We will then use mathematical modelling and sophisticated statistical techniques (called reverse engineering) to determine the parameters of that model from the data (one engineers what the system must be from the observations). This will allow us to infer what cues the kinetochore is using to regulate the attached microtubules. This will include forces acting on the kinetochores and internal stretch and rotation of the kinetochore, our previous study showing that the kinetochore has a structure similar to a hip joint which potentially prevents breakage of the attachment under impulse forces. Our model will only be as good as our data; thus we will use a variety of techniques to perturb the system (remove or knock-down certain components, thereby changing behaviour), and thus 'road-test' our model through a range of different situations. Through such techniques we will achieve greater biological understanding.

现代细胞生物学的一个基本挑战是了解分子机器群体如何产生复杂的行为，这些机器在接近热能水平的情况下工作，从而赋予它们的行为显着的随机成分，同时在全球通信网络的背景下独立工作。鉴于此类系统体积小，使用此类系统会带来重大挑战；然而，光学显微镜的最新进展使得能够以前所未有的空间和时间分辨率观察和量化这些系统。我们感兴趣的生物系统是细胞分裂过程中染色体如何分离。人类是由单个受精细胞（受精卵）构成的。每个细胞包含 46 条染色体——遗传物质 (DNA) 的包裹，为细胞如何工作以及如何构建人类提供指导。细胞分裂产生两个几乎相同的子细胞。染色体在分裂前进行复制，细胞分裂的关键部分是准确分离这些复制的染色体，以便每个子代收到 1 个且仅 1 个副本。细胞无法接受完整的 46 条染色体是导致多种人类疾病的原因，包括癌症和唐氏综合症。在细胞分裂的机械过程中，大部分时间都花在将成对的染色体（原始和副本）重新定位到赤道平面上的固定模式中，然后将成对的染色体拉到细胞的任一端。显然，弄清楚染色体分离的工作原理至关重要。染色体分离是一个机械空间过程。为了移动染色体，细胞利用了一种称为微管的分子电缆，这种分子电缆可以生长和收缩。每条染色体都有一个称为动粒的“钩子”，它附着在这些电缆的两侧（横向附着）和这些电缆的末端。着丝粒是一种极其通用和“智能”的机器，由传感器和电机组成，使其能够确定自己如何附着在微管上，以及它的配对姐妹如何附着，做出一系列明智的决定，以便将配对染色体重新定位到微管上。赤道平面。因此，动粒是决定染色体移动的时间和地点的“控制中心”。但是，着丝粒是如何做到这一点的呢？动粒为什么以及如何做出决定，以及使用什么信息作为输入？我们打算进行的实验将有助于回答这些令人兴奋和有趣的问题，从而增进我们对细胞分裂过程中染色体如何忠实地分离成子细胞的理解。我们将使用最先进的成像技术（显微镜）来观察染色体如何在活的人类细胞中移动。然后，我们将使用数学建模和复杂的统计技术（称为逆向工程）从数据中确定该模型的参数（从观察中设计系统必须是什么样子）。这将使我们能够推断着丝粒使用什么线索来调节附着的微管。这将包括作用在动粒上的力以及动粒的内部拉伸和旋转，我们之前的研究表明动粒具有类似于髋关节的结构，可以防止附件在冲击力下断裂。我们的模型的好坏取决于我们的数据；因此，我们将使用各种技术来扰乱系统（删除或敲除某些组件，从而改变行为），从而通过一系列不同的情况对我们的模型进行“道路测试”。通过这些技术，我们将获得更深入的生物学理解。