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

基本信息

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
项目类别：
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

项目摘要

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.

项目概要近年来，已经鉴定出几种化学性质不同的化合物，它们以 PfATP4（一种 P 型）为目标。 ATP 酶参与维持疟疾寄生虫的 Na+ 稳态。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型抗疟药之一正在开发以对抗耐药性的持续威胁。在上一个资助期间，我们有发现短暂接触 PfATP4 2 小时后，寄生虫生理学会发生一些巨大的变化抑制剂。这些包括： i) 寄生虫内脂质稳态的快速改变，具有可逆性寄生虫质膜中胆固醇的积累（PPM）； ii) 形态变化类似过早的分裂； iii) 寄生虫蛋白的大规模去磷酸化可能是代谢的基础 PfATP4 抑制后的减慢。这些观察结果揭示了一系列迄今为止未知的相互关联的现象分子途径，其破坏导致寄生虫死亡。我们发现 PfATP4 抑制似乎导致 PfNCR1 的抑制，PfNCR1 是另一种药物转运蛋白，参与维持脂质/胆固醇 PPM 内的稳态。红细胞质膜胆固醇含量的降低导致显着将滋养体从宿主细胞中排出，而不裂解红细胞膜。值得注意的是，治疗 PfATP4 或 PfNCR1 抑制剂可防止这种排出。这些研究表明主动运输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 PfATP4 抑制剂仅 2 小时就会发生类似于早产的巨大形态变化分裂事件的发生，包括形成内膜复合物、菱状结构和核分裂。此外，滋养体经历大量代谢物的大量减少，提示代谢关闭。我们假设所有这些事件的背后是由以下因素释放的信号级联： PfATP4 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，其中最重要的是涉及 DNA 的分子新陈代谢、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，我们招募了优秀的联合研究员下一个资助期的财团安排。我们建议共同开展以下具体工作目标： i) 研究胆固醇动态及其在脂肪酸和脂质转运中的作用之间的关系恶性疟原虫； ii) 探索 PfATP4 抑制后蛋白质去磷酸化的意义；三）检查 PfATP4 抑制后代谢减慢的原因； iv) 导出结构信息 PfATP4 和 PfNCR1 了解这些经过验证的抗疟药物靶点的分子细节。