Molecular mechanisms of schizogony in malaria parasites

项目总结 疟疾是全世界疾病和死亡的一个重要原因，其中大多数死亡是由 恶性疟原虫感染。临床疟疾是寄生虫在人类体内无性复制的结果 红血球。在血液期，恶性疟原虫通过分裂生殖进行复制，其中子代寄生虫 是由一种特殊的胞质分裂形成的，这种分裂被称为分段。内膜复合体(IMC) 寄生虫体内独特的结构，由寄生虫蛋白和紧密结合的双脂双层组成 与质膜相关联，以及相关联的基础复合体被假设为协调 女儿寄生虫的集结和分裂。目前应用的焦点是分子 分裂与分割的机制。定向实验将确定生物发生， IMC和基础复合体的组成和功能。我们发现了两种新的寄生虫，它们是 对于分裂和分割来说是必不可少的。第一种是PfMOP，最初定位在中心体附近， 之后到达寄生虫的顶端，对IMC的生物发生至关重要。第二个，PfCINCH，本地化为 基本复合体，对寄生虫的胞质分裂至关重要。这两种蛋白质允许对IMC进行询问 和分别来自寄生虫顶端和基端的基复合体。 最近发现的恶性疟原虫裂殖子组织蛋白对无性繁殖和 配子体发育。在PfMOP缺乏的寄生虫中，IMC不能正确形成，导致 分割失败，未完全分割的裂殖子保持在具有 普通细胞质。PfMOP的分子功能及其与精神分裂和IMC进展的关系 生物发生仍不清楚。拟议的研究解决了这些关键的知识差距。第一个目标是 分成三个独立的子目标。在Aim 1.1中，PfMOP和IMC生物发生之间的联系 分裂遗传学将用细胞生物学方法和现场视频显微镜进行研究。在AIM 1.2中， PfMOP在早期精神分裂症患者中的功能将被调查，以检验PfMOP招募到 染色体凝聚的关键蛋白质复合体。在Aim 1.3中，PfMOP蛋白在晚期相互作用 裂殖体将通过反向遗传学进行确定、验证和功能评估。PfCINCH (新生细胞脱离的协调者)是基础复合体的一个新的和必要的组成部分。在……里面 缺乏PfCINCH的寄生虫，最后阶段的分割被打乱。在此的第二个目标中 建议，我们将重点研究PfCINCH的细胞功能及其蛋白质-蛋白质相互作用。长期的 这些研究的目标和对公共卫生的影响是确定关键的生物过程途径 未来疗法可能针对的疟疾寄生虫。

PROJECT SUMMARY Malaria is an important cause of illness and death worldwide, with most of these deaths resulting from Plasmodium falciparum infection. Clinical malaria results from the asexual replication of parasites in human red blood cells. During the blood stage, P. falciparum replicates via schizogony, wherein daughter parasites are formed by a specialized cytokinesis known as segmentation. The inner membrane complex (IMC), a unique structure within the parasite composed of parasite proteins and a double lipid bilayer that is closely associated with the plasma membrane, and associated basal complex are hypothesized to orchestrate daughter parasite assembly and division. The focus of the current application is on the molecular mechanisms of schizogony and segmentation. Directed experiments will determine the biogenesis, composition, and function of the IMC and basal complex. We have discovered two novel parasites that are essential for schizogony and segmentation. The first, PfMOP, localizes initially near the centrosome and later to the apical end of the parasite and is critical for IMC biogenesis. The second, PfCINCH, localizes to the basal complex and is critical for parasite cytokinesis. These two proteins allow interrogation of the IMC and basal complex from the apical and basal ends of the parasite, respectively. The recently discovered P. falciparum Merozoite Organizing Protein is essential for both asexual and gametocyte development. In PfMOP-deficient parasites, the IMC does not form properly, resulting in a failure of segmentation, and the incompletely segmented merozoites remain in an agglomerate with a common cytoplasm. The molecular function of PfMOP and its link to the progression of schizogony and IMC biogenesis remain unknown. The proposed studies address these critical knowledge gaps. The first aim is divided into three independent subaims. In Aim 1.1, the link between PfMOP and IMC biogenesis in late schizogony will be investigated using a cell biologic approach with live video microscopy. In Aim 1.2, the function of PfMOP in early schizonts will be investigated, testing the hypothesis that PfMOP recruits a critical protein complex for chromosome condensation. In Aim 1.3, the PfMOP protein interactions in late schizonts will be determined, validated, and functionally evaluated by reverse-genetics. PfCINCH (Coordinator of nascent cell detachment) is a novel and essential component of the basal complex. In PfCINCH-deficient parasites, the final stages of segmentation are disrupted. In the second aim of this proposal, we focus on the cellular function of PfCINCH and its protein-protein interactions. The long-term objectives and public health implications of these studies are to identify critical biologic process pathways in the malaria parasite that could be targeted by future therapeutics.