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，已经鉴定了几种化学上不同的化合物，其靶向PfATP 4，一种P型 ATP酶参与维持疟疾寄生虫的Na+稳态。这些化合物中的一些具有 进入临床试验阶段。因此，PfATP 4活性化合物是最有吸引力的新抗疟药之一 是为了对抗持续的抗药性威胁。在上一个资助期内，我们 发现了一些寄生虫生理学的戏剧性变化，伴随着短的2小时暴露于PfATP 4 抑制剂的这些包括：i）具有可逆性的寄生虫内脂质稳态的快速改变， 胆固醇在寄生虫质膜（PPM）中的积累; ii）类似于 过早的寄生虫生殖;和iii）寄生虫蛋白质的大量去磷酸化，这可能是代谢的基础。 PfATP 4抑制后的减缓。这些观察揭示了一系列迄今未知的相互关联的 分子途径，其破坏导致寄生虫死亡。我们发现，PfATP 4抑制似乎 导致PfNCR 1的抑制，PfNCR 1是另一种可药用转运蛋白，参与维持脂质/胆固醇 PPM内的稳态。降低红细胞质膜的胆固醇含量， 滋养体从宿主细胞中排出而不溶解RBC膜。值得注意的是， PfATP 4或PfNCR 1抑制剂均可阻止这种排出。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 暴露于PfATP 4抑制剂仅2小时，就会发生大量形态学变化， 包括内膜复合物、棒状结构和 核分裂此外，滋养体经历大量的代谢物的大量减少，这表明 新陈代谢停止的迹象我们假设，所有这些事件的背后是一个信号级联释放， PfATP 4抑制后Na+流入寄生虫细胞质。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。PfATP 4触发事件的复杂性 禁止需要采取多学科办法。为此，我们招募了杰出的合作调查员 在下一个融资期的联合安排中。我们共同建议开展以下具体工作： 目的：i）研究胆固醇动力学与其在脂肪酸和脂质转运中的作用之间的关系， P. ii）探索PfATP 4抑制后蛋白质去磷酸化的意义; iii） 检查PfATP 4抑制后代谢减慢的原因; iv）推导PfATP 4的结构信息。 PfATP 4和PfNCR 1，以了解这些经验证的抗疟药物靶点的分子细节。