Molecular and cellular dissection of kinesin motors in Apicomplexa to reveal roles in parasite proliferation

这项研究的目的是发现细胞内寄生虫的复制是如何在分子和细胞水平上驱动的。我们将重点研究Apicomplexan寄生虫，因为它们是导致具有重要医学和经济意义的疾病的病原体。其中包括巴贝斯虫、艾美耳球虫和新孢子虫--它们会影响家畜，造成巨大的经济损失--以及疟原虫，它会在包括人类在内的各种脊椎动物中引起疟疾，并导致全球58.4万人死亡。这些寄生虫的生活周期是复杂的，在不同的宿主中在有性和无性复制阶段之间交替。人们才刚刚开始了解它们的复制和扩散机制。通过了解这些寄生虫是如何复制的，我们希望首先对细胞复制的机制和进化提供一般性的见解。其次，我们希望揭示寄生虫特异性复制的独特特征，因为这一知识有望帮助开发新的抗寄生虫药物。就像我们的身体有一个骨架为我们提供支持和力量一样，寄生虫的细胞有一个骨架--称为细胞骨架--它也提供支撑和结构。细胞骨架参与寄生虫生命周期的许多重要方面，包括细胞运输、结构和复制。研究细胞骨架很重要，这样我们就可以了解正常细胞是如何工作的，以及寄生虫的细胞骨架与它们感染的宿主细胞是如何不同的。这些知识可以用来专门针对病原体的细胞骨架，用药物杀死这些生物体并预防疾病。特别是，这个项目将专注于细胞骨架的一部分，称为微管。这些是长长的圆柱形结构，就像分子运输马达携带细胞货物的轨道一样。我们将研究的马达被称为运动蛋白，有许多不同的类型，所有这些都沿着微管移动。在这个项目中，我们将研究被认为对细胞复制很重要的动蛋白。我们想知道寄生虫运动蛋白在复制过程中如何使用细胞燃料沿微管移动，以及它们在什么细胞环境中发挥这些作用。Birkbeck研究小组的工作将涉及研究细胞骨架的三维结构，因为了解细胞骨架是什么样子将有助于我们理解它在寄生虫本身中是如何工作的。我们将使用一种非常强大的显微镜-电子显微镜-来拍摄单个细胞骨架分子的照片，然后使用计算分析将这些图像组合在一起，计算出它们的三维形状。拟议项目的一个非常重要的方面是，我们还将与诺丁汉大学的寄生虫细胞生物学专家合作，研究驱动蛋白在疟疾寄生虫本身中的功能。与许多其他此类致病寄生虫不同，我们在诺丁汉的合作者研究了一种疟疾寄生虫(称为伯氏疟原虫)，这种寄生虫可以在其复杂生命周期的所有阶段进行研究，这些阶段涉及感染的发病和传播。除了这种寄生虫可以很容易地在基因上操纵之外，这意味着可以系统地测试不同驱动蛋白对寄生虫细胞复制的贡献。初步分析表明，疟疾等寄生虫的驱动蛋白与包括牲畜和人类在内的其他生物的驱动蛋白不同。这意味着我们或许能够找到可以阻止寄生虫运动蛋白的药物--从而阻止寄生虫复制--而不是人类运动蛋白。这类药物在作为抗寄生虫疗法的发展方面可能非常有前途。研究寄生虫运动蛋白的结构和功能将使我们能够研究这一想法。

The purpose of this research is to discover how replication of intracellular parasites is driven at a molecular and cellular level. We will focus our studies on Apicomplexan parasites because they are pathogens that cause diseases that are medically and economically important. These include Babesia, Eimeria and Neospora - which affect domesticated livestock causing huge economic losses - and Plasmodia, which causes malaria in a variety of vertebrates including man and kills 584,000 humans worldwide. The life cycles of these parasites are complex and alternate between sexual and asexual replicative stages in distinct hosts. Their replicative and proliferative mechanisms are just beginning to be understood. By understanding how these parasites replicate, we hope to first, provide general insight into the mechanisms and evolution of cell replication. Secondly, we hope to uncover unique features of parasite specific replication because this knowledge promises to help in the development of novel anti-parasite drugs.In the same way as our bodies have a skeleton that provides us with support and strength, the cells of parasites have a skeleton - called the cytoskeleton - which also provides support and structure. The cytoskeleton is involved in many important aspects of the parasite life cycle, including cellular transport, architecture and replication. Studying the cytoskeleton is important both so we can understand how normal cells work and how the parasite cytoskeleton differs from the host cells that they infect. This knowledge can be used to specifically target the cytoskeleton of pathogenic organisms with drugs that kill these organisms and prevent disease.In particular, this project will focus on a part of the cytoskeleton called microtubules. These are long cylindrical structures that act like tracks along which molecular transport motors carry cellular cargo. The motors that we will study are called kinesins and there are many different types, all of which move along microtubules. In this project, we will be investigating kinesins thought to be important for cell replication. We want to know both how parasite kinesins use cellular fuel to move along microtubules during replication and in what cellular context they perform these roles.The work by the Birkbeck research team will involve studying the three-dimensional structure of the cytoskeleton, because knowing what the cytoskeleton looks like will contribute to our understanding of how it works in the parasites themselves. We will use a very powerful microscope - an electron microscope - to take pictures of individual cytoskeleton molecules and then use computational analysis to combine these pictures and calculate their three-dimensional shape. A very important aspect of the proposed project is that we will also study the function of kinesins in malaria parasites themselves, in collaboration with experts in parasite cell biology at the University of Nottingham. Unlike many other such disease-causing parasites, our collaborators at Nottingham work on a species of malaria parasite (called P. berghei) that can be studied at all stages of its complex life cycle that are involved in the pathogenesis and transmission of the infection. Along with the ease with which this parasite can be genetically manipulated, this means that the contributions of different kinesins to parasite cell replication can be tested systematically.Initial analysis suggests that the kinesins from parasites such as malaria are different compared to kinesins from other organisms, including livestock and humans. This means that we might be able to find drugs that can block parasite kinesins - and thereby parasite replication - and not human kinesins. Such drugs could be very promising for development as anti-parasite treatments. Studying the structure and function of the parasite kinesins will allow us to investigate this idea.