Molecular mechanisms of schizogony in malaria parasites

项目摘要 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于 恶性疟原虫感染。临床疟疾是寄生虫在人体内无性繁殖的结果 红细胞在血液阶段，恶性疟原虫通过雌体生殖进行复制，其中子代寄生虫 是由一种被称为细胞分裂的特殊细胞质分裂形成的。内膜复合物（IMC）， 寄生虫内的独特结构，由寄生虫蛋白质和紧密结合的双脂质双层组成。 与质膜和相关的基底复合体相关联， 子寄生物组装和分裂。当前应用的焦点是分子生物学。 无性生殖和分节的机制。定向实验将确定生物起源， IMC和基底复合物的组成和功能。我们发现了两种新的寄生虫， 对生殖和分裂至关重要。第一个，PfMOP，最初定位在中心体附近， 随后到达寄生虫的顶端，并且对于IMC生物发生至关重要。第二个，PfCINCH，本地化到 基础复合体，是寄生虫胞质分裂的关键。这两种蛋白质允许询问IMC 和基底复合体。 最近发现的恶性疟原虫裂殖子组织蛋白对于无性生殖和 配子体发育在PfMOP缺陷型寄生虫中，IMC不能正常形成，导致 分裂失败，并且不完全分裂的裂殖子保持在具有 普通细胞质PfMOP的分子功能及其与乳腺增生和IMC进展的关系 生物起源仍然未知。拟议的研究解决了这些关键的知识差距。第一个目标是 分为三个独立的子目标。在目标1.1中，PfMOP和晚期IMC生物成因之间的联系 将使用细胞生物学方法和实时视频显微镜研究胚胎发生。在目标1.2中， 将研究PfMOP在早期糖尿病患者中的功能，检验PfMOP招募 染色体凝聚的关键蛋白质复合物。在目的1.3中，PfMOP蛋白相互作用在晚期 将通过反向遗传学确定、验证和功能评价突变体。PfCINCH （新生细胞脱离协调器）是基底复合物的一种新的和必不可少的组分。在 PfCINCH缺陷型寄生虫，分裂的最后阶段被破坏。在第二个目标中， 因此，我们将重点关注PfCINCH的细胞功能及其蛋白质-蛋白质相互作用。长期 这些研究的目的和公共卫生意义是确定关键的生物过程途径， 这种疟疾寄生虫可能成为未来治疗的目标。

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.