Comparative and functional genomics of C. neoformans

新型隐球菌的比较和功能基因组学

• 批准号: 7758330
• 负责人: JAMES W KRONSTAD
• 金额: $ 26.66万
• 依托单位: UNIVERSITY OF BRITISH COLUMBIA
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-08-01 至 2014-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7758330
• 关键词: Acquired Immunodeficiency Syndrome; Binding; Biological Assay; Complex; Cryptococcus; Cryptococcus neoformans; DNA; DNA Binding; Data; Defect; Disease; Electrophoretic Mobility Shift Assay; Environment; Epitopes; Foundations; Funding; Fungal Genes; Gene Expression; Gene Expression Microarray Analysis; Gene Expression Regulation; Gene Targeting; Genes; Genetic Transcription; Goals; Growth; HIV; Heme; Heme Iron; Homeostasis; Human; Immune system; Immunocompetent; Incidence; Infection; Infection Control; Iron; Knowledge; Lead; Life; Link; Mass Spectrum Analysis; Melanins; Metabolism; Metals; Modeling; Molecular; Mycoses; Nutrient; Oxygenases; Pathogenesis; Patients; Phenotype; Play; Polysaccharides; Proliferating; Promoter Regions; Protein Binding; Proteins; Proteomics; Publishing; Regulation; Regulon; Research; Role; Source; Testing; Theft; Time; Transferrin; Virulence; Virulence Factors; Work; base; capsule; combat; comparative; functional genomics; fungus; genetic regulatory protein; interest; mutant; pathogen; promoter; public health relevance; research study; response; therapeutic target; transcription factor; uptake

DESCRIPTION (provided by applicant): The fungal pathogen Cryptococcus neoformans causes a high incidence of life-threatening infections in AIDS patients and this fungus therefore poses a major threat to the > 40 million people worldwide who are infected with HIV. In addition, the related species C. gattii has recently emerged as a primary pathogen of immunocompetent people. Our long-term goal is to acquire knowledge that will lead to new strategies to combat fungal infections. In particular, we want to develop a detailed understanding of the factors required for growth of pathogens in mammalian hosts in order to identify key targets to block infection. In this regard, iron availability is an important indicator of the host environment as well as an essential nutrient for pathogens. Therefore, we plan to investigate iron regulation and acquisition in C. neoformans, as a model for understanding the role of iron in fungal pathogenesis. Iron levels are particularly important for the pathogenesis of C. neoformans because availability influences the size of the polysaccharide capsule that is the major virulence factor of the fungus. Our hypothesis is that the influence of iron on virulence and growth occurs through a network controlled by the master iron-responsive regulator Cir1 (Cryptococcus iron regulator). We believe that the characterization of Cir1 and this network will identify mechanisms of iron acquisition that are essential for C. neoformans to cause disease. Our first specific aim is to characterize the key functions of Cir1. We will specifically determine whether Cir1 directly binds iron and whether the protein binds the promoter regions of target genes encoding iron uptake functions. This work will include proteomic approaches to identify regulatory factors that interact with Cir1. These factors may participate in the regulation of target genes for iron acquisition and other functions relevant to virulence. Our second specific aim will characterize the role of the Hap transcription factor complex in iron acquisition from heme. The expression of the HAP genes is regulated by Cir1 and we have preliminary data that these genes are required for heme use. Our third specific aim will employ transcriptional profiling to examine the role of Cir1 in the use of iron sources (heme and transferrin) that are abundant in the host. Finally, we will construct mutants that are defective in genes encoding candidate functions for the use of heme and transferrin during infection. Likely targets (e.g., heme oxygenase) have been identified and we anticipate that our microarray work in aim 3 will identify additional functions. At the conclusion of this work, we will have a deeper understanding of the regulatory network that links iron to virulence, and we will know the functions that C. neoformans uses to steal iron from the host during infection. This information will highlight the key iron-related functions that can be targeted to treat Cryptococcal disease. PUBLIC HEALTH RELEVANCE: The relevance of this project comes from the pressing need to control fungal infections in humans with impaired immune systems. In particular, the 40 million or more people infected with HIV have a high chance of succumbing to fungal disease. The research will specifically examine the potential to control infections by targeting the ability of fungal pathogens to acquire the nutrient iron during infection.

描述（由申请人提供）：真菌病原体新型隐球菌在艾滋病患者中引起危及生命的感染的高发生率，因此这种真菌对全世界超过 4000 万艾滋病毒感染者构成重大威胁。此外，相关物种格特隐球菌最近已成为免疫功能正常人群的主要病原体。我们的长期目标是获取知识，从而制定对抗真菌感染的新策略。特别是，我们希望详细了解病原体在哺乳动物宿主中生长所需的因素，以便确定阻止感染的关键目标。在这方面，铁的可用性是宿主环境的重要指标，也是病原体的必需营养素。因此，我们计划研究新型隐球菌中铁的调节和获取，作为了解铁在真菌发病机制中的作用的模型。铁水平对于新型隐球菌的发病机制尤其重要，因为铁的可用性会影响多糖荚膜的大小，而多糖荚膜是真菌的主要毒力因子。我们的假设是，铁对毒力和生长的影响是通过主要铁反应调节因子 Cir1（隐球菌铁调节因子）控制的网络发生的。我们相信，Cir1 和该网络的表征将确定新型隐球菌引起疾病所必需的铁获取机制。我们的第一个具体目标是描述 Cir1 的关键功能。我们将具体确定 Cir1 是否直接结合铁以及该蛋白是否结合编码铁摄取功能的靶基因的启动子区域。这项工作将包括蛋白质组学方法来识别与 Cir1 相互作用的调节因子。这些因素可能参与铁获取和其他与毒力相关功能的靶基因的调节。我们的第二个具体目标是表征 Hap 转录因子复合物在从血红素获取铁中的作用。 HAP 基因的表达受 Cir1 调节，我们有初步数据表明这些基因是血红素使用所必需的。我们的第三个具体目标是采用转录分析来检查 Cir1 在利用宿主丰富的铁源（血红素和转铁蛋白）中的作用。最后，我们将构建在编码感染期间使用血红素和转铁蛋白的候选功能的基因中有缺陷的突变体。可能的目标（例如血红素加氧酶）已经确定，我们预计目标 3 中的微阵列工作将确定其他功能。在这项工作结束时，我们将对将铁与毒力联系起来的调控网络有更深入的了解，并且我们将了解新型隐球菌在感染期间从宿主中窃取铁的功能。该信息将重点介绍可用于治疗隐球菌疾病的关键铁相关功能。公共卫生相关性：该项目的相关性来自于控制免疫系统受损的人类真菌感染的迫切需要。特别是，4000万或更多的艾滋病毒感染者有很高的机会死于真菌病。该研究将专门研究通过针对真菌病原体在感染期间获取营养铁的能力来控制感染的潜力。