Regulation of mitotic spindles by IP3 receptors

IP3 受体对有丝分裂纺锤体的调节

• 批准号: BB/S013776/1
• 负责人: Colin Taylor
• 金额: $ 72.34万
• 依托单位: University of Cambridge
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2019
• 资助国家: 英国
• 起止时间: 2019 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=BB%2FS013776%2F1
• 关键词: Regulation; mitotic; spindles; IP3; receptors

Every animal begins life as a single fertilized egg, which then divides repeatedly by mitosis to produce an animal with, in humans, some 30,000,000,000,000 cells. Mitosis continues throughout life to replenish lost and damaged cells. During mitosis, a diamond-shaped web forms (the spindle) and the replicated chromosomes align at its centre. The chromosomes are then drawn apart towards the spindle poles so that genetic material is evenly distributed between the two daughter cells. The orientation of the spindle - aligned with the surface to which the cell adheres or perpendicular to it - is important because it determines where the cell divides, and that influences how each cell will subsequently develop. Mitosis is tightly regulated, in large part by families of kinases that attach phosphate groups to other proteins, to ensure that each step proceeds only when preceding steps have been properly completed. Many cellular activities, including some steps in mitosis, are regulated by increases in intracellular calcium concentration. These calcium signals are generated when channels open and allow calcium to flow into the cell down a steep concentration gradient. One of the most important of these channels is the IP3 receptor, which allows controlled release of calcium from an intracellular store, the ER. In addition to distributing chromosomes to daughter cells, mitosis must also ensure that each cell gets its share of intracellular organelles, including the ER. There is, therefore, a massive rearrangement of intracellular structures, including the ER, during mitosis. Our recent work, using microscopes to report the movement of cellular components made visible by attachment of coloured proteins, has shown that during mitosis IP3 receptors accumulate around the spindle poles and that in cells without IP3 receptors the spindle does not align properly. We suggest that local calcium signals generated by these repositioned IP3 receptors control spindle orientation by regulating the tethers (astral microtubules) that hold the spindle poles to the plasma membrane that surrounds the cell. Immediately beneath the plasma membrane and at the spindle poles, there is an accumulation of actin, which, amongst many other functions, will later contribute to dividing the cell. We recently showed that IP3 receptors are 'licensed' to respond only when they associate with actin, and published work suggests that IP3 receptors may be stimulated after phosphorylation by one of the mitotic kinases (plk1) that accumulates at spindle poles. We suggest that accumulation of IP3 receptors at the spindle poles exposes them to signals (actin and plk1) that increase their activity, and that IP3 receptors then generate local calcium signals that control spindle orientation by regulating astral microtubules. In the proposed work, we will use advanced optical microscopy methods and newly developed tools that allow rapid repositioning of IP3 receptors to establish the mechanisms that move IP3 receptors to the spindle poles and to unravel how their activities at the poles control spindle orientation.

每一种动物的生命都是从一个受精卵开始的，受精卵通过有丝分裂反复分裂，产生一个具有大约300,000,000,000,000个细胞的动物。有丝分裂持续一生，以补充丢失和受损的细胞。在有丝分裂过程中，形成一个菱形的网（纺锤体），复制的染色体在其中心排列。然后染色体向纺锤体两极分开，这样遗传物质就均匀地分布在两个子细胞之间。纺锤体的方向——与细胞附着的表面对齐或垂直——很重要，因为它决定细胞分裂的位置，并影响每个细胞随后的发育方式。有丝分裂受到严格的调控，这在很大程度上是由将磷酸基团连接到其他蛋白质上的激酶家族控制的，以确保每一步只有在前一步正确完成后才能进行。许多细胞活动，包括有丝分裂的一些步骤，是由细胞内钙浓度的增加所调节的。当通道打开并允许钙以陡峭的浓度梯度流入细胞时，这些钙信号就会产生。这些通道中最重要的一个是IP3受体，它允许钙从细胞内储存的内质网中有控制地释放。除了将染色体分配给子细胞外，有丝分裂还必须确保每个细胞获得包括内质网在内的胞内细胞器。因此，在有丝分裂期间，包括内质网在内的细胞内结构发生了大量的重排。我们最近的工作，使用显微镜报告了通过附着有色蛋白可见的细胞成分的运动，表明在有丝分裂期间，IP3受体聚集在纺锤体极点周围，而在没有IP3受体的细胞中，纺锤体不能正确排列。我们认为，这些重新定位的IP3受体产生的局部钙信号通过调节将纺锤极固定在细胞周围的质膜上的系索（星状微管）来控制纺锤体的方向。在质膜的正下方和纺锤体的极点处，有肌动蛋白的积累，在许多其他功能中，肌动蛋白后来将有助于细胞分裂。我们最近发现IP3受体只有在与肌动蛋白结合时才有反应，并且发表的研究表明IP3受体可能在被纺锤体极点积累的一种有丝分裂激酶（plk1）磷酸化后受到刺激。我们认为，IP3受体在纺锤体极点的积累使其暴露于信号（肌动蛋白和plk1），从而增加其活性，IP3受体随后产生局部钙信号，通过调节星状微管来控制纺锤体取向。在这项工作中，我们将使用先进的光学显微镜方法和新开发的工具，允许IP3受体快速重新定位，以建立将IP3受体移动到纺锤体极点的机制，并揭示它们在极点的活动如何控制纺锤体方向。

项目成果

IP

知识产权

• DOI: 10.17863/cam.54049
• 发表时间: 2020
• 作者: Atakpa-Adaji P