Regulation of calcium signaling in the human malaria parasite

项目摘要 人类最致命的疟疾是由真核寄生虫恶性疟原虫引起的， 每年造成近45万人死亡。世界上近一半的人口生活在 疟疾流行的地区，每年造成近2.5亿人感染。到目前为止，还有 没有有效的疟疾疫苗和抗疟疾药物是治疗的主要手段。 不幸的是，这种寄生虫已经对临床上使用的所有抗疟疾药物和这些药物产生了抗药性。 耐药菌株正在世界各地传播。因此，至关重要的是，我们必须不断地识别 潜在的新药物靶点，以保持领先于这种致命的疾病。了解信号转导途径 驱动寄生虫生物学的药物将提供新的抗疟疾药物靶点，这些药物是 寄生的，在宿主中不存在的。钙离子(Ca~(2+))信号已成为主要驱动因素之一 恶性疟原虫生活史。这项建议的目标是研究钙信号和途径。 来调节疟疾寄生虫中的离子波动。在恶性疟原虫中，与其他真核生物相似 在生物体中，胞质中的钙离子水平很低，而胞质中的钙离子浓度却在上升 对特定信号的反应。这种胞质内钙离子的增加导致了一个信号级联反应，即 对寄生虫的生命周期来说是必不可少的。一旦信号减弱，细胞内的钙离子水平就会下降 通过摄取细胞内的钙离子储存库，如内质网。恶性疟原虫 基因组缺乏几个已知对其他井中的Ca~(2+)信号转导至关重要的规范基因 研究真核生物。因此，我们将以唯一与钙离子结合的可溶性蛋白质为目标 定位于细胞内主要的钙库--内质网的区域。我们假设 这种蛋白质调节这个细胞器对钙的释放和吸收。我们的初步数据显示 这种基因对寄生虫的无性生命周期是必不可少的，也是寄生虫入侵所必需的 寄生虫进入它的宿主红细胞。我们将利用遗传、细胞和生化方法来 明确该基因在调节Ca~(2+)信号和恶性疟原虫侵入宿主中的作用 手机。其中包括使用遗传编码的钙指示剂来揭示钙的波动 恶性疟原虫红细胞内生活史及基因干预对其的影响 钙离子动态平衡。将采用第二种独立的基于邻近的标记方法来 分离和发现靶基因的新伙伴，以定义所需的基因网络 调节恶性疟原虫感染人红细胞内钙离子的流动。实现…的目标 这项研究将揭示调节Ca~(2+)信号的寄生虫特有的基本通路，这可能是 以抗疟疾药物开发为目标。

Project Summary The deadliest form of human malaria is caused by the eukaryotic parasite Plasmodium falciparum, which is responsible for nearly 450,000 deaths every year. Nearly half of the world’s population lives in areas where malaria is endemic, resulting in almost ~250 million infections each year. As yet, there are no effective vaccines against malaria and antimalarial drugs are the mainstay of treatment. Unfortunately, the parasite has gained resistance to all antimalarial drugs used in the clinic and these drug-resistant strains are spreading throughout the world. Thus, it is crucial that we constantly identify potential novel drug targets to stay ahead of this deadly disease. Understanding the signaling pathways that drive the biology of the parasite will provide new antimalarial drug targets that are unique to the parasite and absent in the host. Calcium ion (Ca2+) signaling has emerged as one of the major drivers of the life cycle of P. falciparum. The goal of this proposal is to study Ca2+ signaling and the pathways that regulate ion fluctuations in malaria parasites. In P. falciparum, similar to other eukaryotic organisms, the cytoplasmic levels of Ca2+ is very low and its concentration rises in the cytoplasm in response to specific signals. This increased cytosolic Ca2+ results in a signaling cascade that that is essential for the life cycle of the parasite. Once the signal subsides, the levels of cytosolic Ca2+ falls back via uptake into intracellular Ca2+ stores, such as the endoplasmic reticulum. The P. falciparum genome lacks several canonical genes that are known to be essential for Ca2+ signaling in other well- studied eukaryotic organisms. Therefore, we will target the only soluble protein with Ca2+ binding domains that localizes to the major intracellular Ca2+ store, the endoplasmic reticulum. We hypothesize that this protein regulates the release and uptake of Ca2+ from this organelle. Our preliminary data show that this gene is essential for the asexual life cycle of the parasite and is required for the invasion of the parasite into its host red blood cell. We will utilize genetic, cellular, and biochemical approaches to define the role of this gene in regulating Ca2+ signaling and the invasion of P. falciparum into the host cell. These include the use of genetically encoded Ca2+ indicators to reveal the fluctuations of Ca2+ during the intraerythrocytic life cycle of P. falciparum as well as the effect of genetic interventions on the homeostasis of Ca2+. A second independent proximity-based labeling approach will be undertaken to isolate and discover novel partners of the targeted gene to define the network of genes required to regulate the flow of Ca2+ within the P. falciparum infected human red blood cells. Achieving the aims of this study will reveal the essential parasite-specific pathways that regulate Ca2+ signaling, which can be targeted for antimalarial drug development.