Spatial arrangement and three-dimensional structure of human centromeres

着丝粒出现在染色体的主要收缩处。它们允许复制的染色体分裂，控制细胞分裂，并参与控制基因表达。在许多类型的癌症和其他遗传疾病中都发现有缺陷的着丝粒。它们还与染色体外疾病如唐氏综合症有关。着丝粒的结构与染色体的其他部分不同，我们希望研究的正是这种结构。我们想看看着丝粒DNA是如何在着丝粒上紧密折叠的。我们还想找出为什么着丝粒位于细胞核的某些区域，因为这可能会影响着丝粒如何工作以及它们如何调节基因。人类着丝粒有多种大小和形式；通过观察广泛的人类着丝粒，将会发现共同的结构和空间特性。我们已经发现了非常小的着丝粒——新着丝粒——这比其他着丝粒更容易研究。我们已经用这些着丝粒构建了人类的小染色体，我们相信这代表了用基因疗法治疗人类的主要、全人类的方法。帮助我们实现目标的一种方法是以一种可控的方式拉伸着丝粒，使其结构更容易可视化。我们的工具将是抗体、荧光标记蛋白和高分辨率显微镜。这些设备包括电子显微镜，以及可以产生光学切片和3D图像的显微镜。其中之一是共聚焦激光扫描显微镜；另一种方法是使用反卷积软件去除图像中的失焦光，以达到相同的目的。我们将用荧光显微镜检测不同的着丝粒蛋白，用电子显微镜检测不同大小的金颗粒。使用这些显微镜，我们已经能够找到我们的一个新中心体在细胞核中的位置。我们也开始用电子显微镜观察着丝粒。

Centromeres occur at the main constriction of chromosomes. They allow duplicated chromosomes to divide, control cell division and are involved in the control of gene expression. Faulty centromeres are found in many types of cancer and in other genetic diseases. They are also implicated in extra-chromosome disorders such as Down syndrome. Centromeres have a different structure to the rest of the chromosome and it is this structure we wish to study. We want to see how centromere DNA folds up tightly at the centromere. We also want to find out why centromeres locate in certain regions of the nucleus, because this may influence how the centromere works and how they regulate genes. Human centromeres come in many sizes and forms; by looking at a wide range of human centromeres, common structural and spatial properties will emerge. We have discovered very small centromeres - neocentromeres - which are much easier to study than other centromeres. We have used these centromeres to construct human minichromosomes, which we believe represent the main, all-human way forward to treat people with gene therapy. One way to help us achieve our aims is to stretch out centromeres in a controlled way to make it easier to visualise their structure. Our tools will be antibodies, fluorescently-labelled proteins and high resolution microscopes. These include an electron microscope, and microscopes that can produce optical sections and in turn a 3D image. One of these is the confocal laser scanning microscope; the other involves removal of out-of-focus light from images using deconvolution software to achieve the same goal. We will detect different centromere proteins with different fluorochromes for fluorescence microscopes and different sizes of gold particles for the electron microscope. Using these microscopes we have already been able to find out where one of our neocentromeres is located within the nucleus. We have also started to look at centromeres with the electron microscope.