Molecular Determinants of Intracellular Survival and Replication in Leishmania

利什曼原虫细胞内存活和复制的分子决定因素

• 批准号: 8733007
• 负责人: Norma Windsor Andrews
• 金额: $ 44.29万
• 依托单位: UNIV OF MARYLAND, COLLEGE PARK
• 依托单位国家: 美国
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-06-01 至 2019-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8733007
• 关键词: Affect; Autophagocytosis; Binding; Biological Process; Biology; Cell membrane; Cells; Development; Dominant-Negative Mutation; Environment; Erythrocytes; Erythrophagocytosis; Ferritin; Funding; Future; Grant; Growth; Heme; Heme Iron; Hemeproteins; Hemin; Homeostasis; Host resistance; Human; Infection; Infectious Agent; Integration Host Factors; Intercept; Investigation; Iron; Knowledge; Leishmania; Leishmaniasis; Life; Lysosomes; Maintenance; Mammals; Mediating; Membrane Proteins; Membrane Transport Proteins; Molecular; Mus; Nutrient; Nutrition Disorders; Parasites; Pathway interactions; Phagocytosis; Phagolysosome; Play; Porphyrins; Positioning Attribute; Predisposition; Process; Proteins; Public Health; Reaction; Recycling; Research; Resistance to infection; Risk; Role; Source; Testing; Therapeutic Intervention; Transferrin; Vacuole; Virulence; Work; acquired factor; cellular imaging; cofactor; drug development; hepcidin; in vivo; insight; iron (III) reductase; iron deficiency; iron metabolism; late endosome; macrophage; metal transporting protein 1; mutant; novel; overexpression; pathogen; public health relevance; senescence; tool; trafficking; uptake

DESCRIPTION (provided by applicant): Iron and iron-containing heme are essential cofactors in reactions that perform critical biological functions, but are toxic in excess. Hence, the availability of these nutrients is tightly controlled. Leishmania parasites replicate intracellulary and can't synthesize heme, so must acquire iron and heme from the host cell. Until recently, it was not known how this was achieved. Work from the previous grant cycle identified three membrane proteins involved in iron and heme uptake that are essential for the intracellular growth and virulence of L. amazonensis: The ferric iron reductase LFR1, the ferrous iron transporter LIT1, and the long- sought heme transporter, LHR1. The availability of parasite strains deficient in these molecules and powerful tools to interrogate host cell heme-iron metabolism will now allow us to take this work to the next level: An investigation of the functiona interrelationship between parasite and host cell pathways for heme-iron homeostasis. Understanding this process is critical because Leishmania parasitizes macrophages, cells that perform a key role in the maintenance of organismal heme-iron metabolism. Reticuloendothelial macrophages recycle iron from phagocytosed senescent red blood cells at a staggering rate. In mammals, about 5x106 red blood cells or 5x1015 heme molecules are degraded each second inside macrophage phagolysosomes, releasing iron for body redistribution through a tightly regulated membrane transporter, ferroportin. We will take advantage of exciting recent advances in the field of heme- iron traffic in macrophages to: (1) Elucidate how the iron export machinery of macrophages impacts the ability of Leishmania amazonensis to acquire iron and replicate intracellularly; (2) Determine how the dynamics of heme traffic in macrophages affects intracellular heme uptake by L. amazonensis; and (3) Elucidate the importance of heme as a source of iron for L. amazonensis. Our results will facilitate future drug development by defining where L. amazonensis intercepts the elaborate heme-iron traffic machinery of macrophages, and by revealing whether heme reaching parasitophorous vacuoles represents a major source of iron for the parasites. Importantly, this project will also propel forward our understanding of human susceptibility to leishmaniasis. Iron deficiency is the most prevalent nutritional disorder, and identification of novel host factors that counteract the parasite's machinery for heme-iron acquisition can have a significant impact in the assessment of infection risk.

描述（由申请人提供）：铁和含铁血红素是执行关键生物功能的反应中必不可少的辅助因子，但过量是有毒的。因此，这些营养物质的可用性受到严格控制。利什曼原虫在细胞内复制，不能合成血红素，必须从宿主细胞获取铁和血红素。直到最近，人们才知道这是如何实现的。上一个资助周期的工作确定了三种参与铁和血红素摄取的膜蛋白，它们对亚马逊河蛭的细胞内生长和毒力至关重要：铁还原酶LFR1、亚铁转运蛋白LIT1和长期寻找的血红素转运蛋白LHR1。缺乏这些分子的寄生虫菌株的可用性和询问宿主细胞血红素铁代谢的强大工具将使我们能够将这项工作提升到下一个水平：研究寄生虫和宿主细胞血红素铁稳态途径之间的功能相互关系。了解这一过程至关重要，因为利什曼原虫寄生于巨噬细胞，而巨噬细胞在维持机体血红素铁代谢中起着关键作用。网状内皮巨噬细胞以惊人的速度从被吞噬的衰老红细胞中回收铁。在哺乳动物中，巨噬细胞吞噬溶酶体内每秒约有5x106个红细胞或5x1015个血红素分子被降解，释放铁，通过一种受到严格调控的膜转运蛋白——铁转运蛋白，在体内重新分配。我们将利用巨噬细胞血红素-铁运输领域的最新进展：(1)阐明巨噬细胞的铁输出机制如何影响亚马逊利什曼原虫获得铁和细胞内复制的能力；(2)确定巨噬细胞血红素运输动态如何影响亚马逊河蛭胞内血红素摄取；(3)阐明血红素作为铁元素来源的重要性。我们的研究结果将有助于未来的药物开发，通过确定亚马逊乳杆菌拦截巨噬细胞复杂的血红素-铁运输机制，并揭示到达寄生虫液泡的血红素是否代表寄生虫铁的主要来源。重要的是，该项目还将推动我们对人类对利什曼病易感性的理解。缺铁是最普遍的营养失调，鉴定新的宿主因子可以抵消寄生虫的血红素铁获取机制，对感染风险的评估具有重要影响。