Molecular pathways affected by drugs that disrupt Na+ and lipid homeostasis in malaria parasites

破坏疟原虫中钠和脂质稳态的药物影响的分子途径

• 批准号: 10659924
• 负责人: AKHIL B VAIDYA
• 金额: $ 71.2万
• 依托单位: DREXEL UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-05-05 至 2027-12-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10659924
• 关键词: ATP phosphohydrolase; Active Biological Transport; Affect; Antimalarials; Biochemical; Biological; Biology; Carbon; Cell Cycle; Cell membrane; Cells; Chemicals; Cholesterol; Cholesterol Homeostasis; Chromosome Segregation; Clinical Trials; Collection; Complex; Cytolysis; Cytoplasm; DNA metabolism; Development; Drug Targeting; Drug resistance; Enzymes; Event; Exposure to; Fatty Acids; Funding; Genetic; Goals; Homeostasis; Homo; Knowledge; Lipids; Malaria; Membrane; Metabolic; Metabolism; Molecular; Morphology; Parasites; Pathway interactions; Patients; Pediatric Hospitals; Pharmaceutical Preparations; Phase; Phenotype; Philadelphia; Physiology; Plasmodium; Plasmodium falciparum; Play; Process; Protein Dephosphorylation; Protein phosphatase; Proteins; Research Personnel; Role; Signal Transduction; Sodium; Structure; Universities; Work; drug discovery; fatty acid transport; genetic manipulation; inhibitor; insight; interdisciplinary approach; lipid transport; nuclear division; premature; prevent; recruit; response; rhoptry; smoothened signaling pathway

Project Summary In recent years, several chemically diverse compounds have been identified that target PfATP4, a P-type ATPase involved in maintaining Na+ homeostasis in malaria parasites. Some of these compounds have advanced to clinical trials. Thus, PfATP4-active compounds are among the most attractive new antimalarials being developed to counter the continuing threat of drug resistance. Over the previous funding period, we have discovered some dramatic alterations in parasite physiology that accompany a short 2 h exposure to PfATP4 inhibitors. These include: i) Rapid alterations in lipid homeostasis within the parasites with reversible accumulation of cholesterol in the parasite plasma membrane (PPM); ii) Morphological changes resembling premature schizogony; and iii) Massive dephosphorylation of parasite proteins that may underlie the metabolic slowdown that follows PfATP4 inhibition. These observations reveal a collection of hitherto unknown interrelated molecular pathways, disruptions of which result in parasite demise. We found that PfATP4 inhibition appears to result in inhibition of PfNCR1, another druggable transporter, that is involved in maintaining lipid/cholesterol homeostasis within the PPM. Reduction of cholesterol content of the RBC plasma membrane results in dramatic expulsion of trophozoites from the host cell without the lysis of the RBC membrane. Remarkably, treatment with either PfATP4 or PfNCR1 inhibitors prevents this expulsion. These studies suggest an active transport of cholesterol between the RBC plasma membrane and the parasite. We found that trophozoite stage parasites exposed to PfATP4 inhibitors for just 2 h undergo massive morphological changes that resemble premature onset of schizogony events including the formation of inner membrane complexes, rhoptry-like structures and karyokinesis. In addition, trophozoites undergo massive reduction of a large number of metabolites suggestive of metabolic shutdown. We hypothesize that underlying all these events is a signaling cascade unleashed by the influx of Na+ into parasite cytoplasm following PfATP4 inhibition. In support of this proposition, we found dephosphorylation of a large number of proteins, prominent among which were molecules involved in DNA metabolism, chromosome segregation and cell cycle processes. The complexity of events triggered by PfATP4 inhibition requires a multidisciplinary approach. For this purpose, we have recruited outstanding co-investigators in consortium arrangements for the next funding period. Together, we propose to carry out the following specific aims: i) Investigate the relationship between cholesterol dynamics and its role in fatty acid and lipid transport in P. falciparum; ii) Explore the significance of dephosphorylation of proteins that follows PfATP4 inhibition; iii) Examine the causes of metabolic slowdown following PfATP4 inhibition; iv) Derive structural information for PfATP4 and PfNCR1 to understand molecular details about these validated antimalarial drug targets.

项目摘要 近年来，几种化学上不同的化合物被鉴定为靶向PfATP4，一种P-型 ATPase参与维持疟疾寄生虫的Na+动态平衡。其中一些化合物具有 进入临床试验阶段。因此，PfATP4活性化合物是最具吸引力的新抗疟疾药物之一。 正在开发以对抗持续存在的抗药性威胁。在上一个资助期内，我们有 发现伴随着短暂接触PfATP4 2小时的寄生虫生理发生了一些戏剧性的变化 抑制剂。这些变化包括：i)可逆转的寄生虫体内脂质平衡的快速变化 胆固醇在寄生虫质膜(PPM)中的积累；II)类似于 过早的分裂；以及iii)可能作为代谢基础的寄生虫蛋白的大量去磷酸化 PfATP4抑制后的减慢。这些观察揭示了迄今为止未知的相互关联的集合 分子途径，破坏这些途径会导致寄生虫死亡。我们发现，抑制PfATP4似乎对 导致PfNCR1的抑制，PfNCR1是另一种参与维持脂质/胆固醇的药物转运蛋白 PPM内的动态平衡。红细胞膜胆固醇含量的降低导致显著的 从宿主细胞中排出滋养体而不裂解红细胞膜。值得注意的是，治疗 PfATP4或PfNCR1抑制剂可阻止这种排泄。这些研究表明， 红细胞质膜和寄生虫之间的胆固醇。我们发现滋养体阶段的寄生虫 暴露在PfATP4抑制剂下仅2小时，就会出现类似早产的巨大形态变化 分裂相事件的发生，包括内膜复合体的形成，棒状结构和 核分裂。此外，滋养体经历了大量代谢产物的大量减少，这表明 新陈代谢停滞。我们假设，所有这些事件背后都是一个信号级联，由 PfATP4抑制后Na+进入寄生虫细胞质。为了支持这一主张，我们发现 大量蛋白质的去磷酸化，其中最突出的是与DNA有关的分子 代谢、染色体分离和细胞周期过程。PfATP4触发事件的复杂性 抑制需要多学科的方法。为此，我们招募了优秀的合作调查员。 在下一个资金期的财团安排中。我们建议共同开展以下具体工作 目的：i)研究胆固醇动态及其在脂肪酸和脂质转运中的作用。 恶性疟原虫；ii)探索PfATP4抑制后蛋白质去磷酸化的意义；iii) 检查PfATP4抑制后代谢减慢的原因；iv)获得以下结构信息 PfATP4和PfNCR1，以了解这些有效的抗疟疾药物靶点的分子细节。