Exploring an Essential and Dangerous Pathway in Leishmania Parasites

描述(申请人提供)：利什曼原虫属寄生虫是一组严重疾病(称为利什曼病)的病原体，感染全球1000-1200万人。目前治疗利什曼病的药物普遍存在疗效低、毒性大等问题。由于耐药性正在上升，而且没有安全的疫苗可用，迫切需要保持稳定的新药和潜在的药物靶点。PI的长期目标是破译利什曼原虫在沙蝇和哺乳动物身上繁衍的分子策略。在发病的基本机制方面的进展可以带来新的和改进的治疗方法。在哺乳动物细胞中，狮身人面像碱基(SBS)及其磷酸化衍生物是一种强大的信号分子，调节着过多的重要途径。最近的研究表明，利什曼原虫具有非常活跃的SB代谢，具有重要但尚未明确的功能。这个应用程序的目的是阐明 Sb代谢在利什曼原虫增殖和毒力中的作用建立在强有力的初步研究的基础上，中心假设是Sb代谢是利什曼原虫适应哺乳动物恶劣环境、清除有毒代谢物和合成必需磷脂所必需的。这项拟议研究的基本原理是，更好地了解这一极其重要且有些危险的途径将为寄生虫与宿主的相互作用提供新的见解，并发现控制利什曼病的新线索。两个特定的目标将被用来检验中心假说：目标1是阐明鞘氨醇激酶(SB代谢的关键酶)在利什曼原虫中的关键作用；目标2是确定为什么利什曼原虫需要乙醇胺磷酸(SB代谢的中间产物)才能生存。每个目标都将探索利什曼原虫中SB代谢途径的一个分支。基因敲除突变体及其互补对照将使用分子、细胞和生化方法产生和表征。这些研究的成功完成将大大提高我们对利什曼原虫中SB代谢的了解，以及总体上脂类代谢物的功能。这一项目意义重大，因为除了令人兴奋的新知识外，这些研究结束后可能会出现一些新的药物靶点。

DESCRIPTION (provided by applicant): Protozoan parasites of the genus Leishmania are the causative agents for a group of serious diseases (known as Leishmaniasis) infecting 10-12 million people worldwide. Current drugs for leishmaniasis are plagued with low efficacy and high toxicity. With resistance on the rise and no safe vaccine available, there is an urgent need to maintain a steady stream of new drugs and potential drug targets. The PI's long term goal is to decipher the molecular strategy utilized by Leishmania parasites to thrive in sandflies and mammals. Advancement in the fundamental mechanism of pathogenesis can lead to new and improved treatments. In mammalian cells, sphingoid bases (SBs) and their phosphorylated derivatives are powerful signaling molecules regulating a plethora of essential pathways. Recent studies demonstrate that Leishmania parasites possess a very active SB metabolism with important yet poorly defined functions. The objective of this application is to elucidate the vital roles of SB metabolism in Leishmania proliferation and virulence. Formulated on the basis of strong preliminary studies, the central hypothesis is that SB metabolism is required for the adaptation of Leishmania parasites to the harsh environment in mammals, the removal of toxic metabolites, and the synthesis of essential phospholipids. Rationale for the proposed research is that a better understanding of this critically important and somewhat dangerous pathway will provide novel insight into parasite-host interaction and uncover new clues to control leishmaniasis. Two specific aims will be undertaken to test the central hypothesis: aim 1 is to elucidate the crucial roles of sphingosine kinase (a key enzyme in SB metabolism) in Leishmania; and aim 2 is to determine why Leishmania needs ethanolamine phosphate (an intermediate in SB metabolism) to survive. Each aim will explore one branch of the SB metabolic pathway in Leishmania. Genetic knockout mutants and their complemented controls will be generated and characterized using molecular, cellular, and biochemical approaches. Successful completion of these studies will significantly improve our understanding of SB metabolism in Leishmania and the function of lipid metabolites in general. This project is highly significant because in addition to the exciting new knowledge, a number of novel drug targets may emerge at the conclusion of these studies.