Systematic investigation of GPI-anchored mannoproteins in Cryptococcus neoformans

新生隐球菌会导致致命的隐球菌性脑膜脑炎，并导致15%的 艾滋病患者的死亡人数。这种真菌也可以在没有明显症状的个体中引起脑膜脑炎。 免疫缺陷和这样的发生率正在增加。目前抗真菌治疗的结果 患有隐球菌性脑膜脑炎的患者远远不能接受，死亡率从10%到10%不等。 70%。治疗这种疾病的挑战促使我们理解隐球菌的发病机制，并 确定形成这种病原体和哺乳动物宿主之间相互作用的隐球菌因子。我们的 中心前提是调节宿主反应或嗜神经性的隐球菌因子可以提供靶标 用于抗真菌治疗、诊断或预防。 各种真核病原体中的糖基磷脂酰肌醇(GPI)修饰的糖蛋白是 在调节宿主反应方面扮演着重要角色。这些糖蛋白对宿主的作用可以是保护性的。 或者是有害的。在新生葡萄球菌中，甘露糖蛋白被认为是被 宿主抗隐球菌细胞介导的免疫反应。然而，只有几个GPI锚定的甘露糖蛋白 已研究过的致病因子包括几丁质脱乙酰酶Cda1-3和磷脂酶 Plb1.我们之前发现，过表达抗毒力转录因子Znf2的隐球菌细胞可以 赋予宿主罕见的杀菌免疫力，以抵御其他致命野生型的后续挑战 紧张。值得注意的是，在预测的49个GPI锚定的甘露糖蛋白基因中，有25个基因位于C. 新生杆菌H99受Znf2调控，其中10株上调，15株下调。这表明 Znf2在控制该真菌甘露糖蛋白递送中的重要性。最近的一项研究表明，13 甘露糖蛋白基因在隐球菌病小鼠和猴肺中的高度差异表达 感染。鉴于GPI锚定的甘露糖蛋白是细胞壁蛋白的主要类别，它们也是 ，我们推测，这些蛋白代表了最重要的 调节隐球菌与宿主相互作用的一组重要因子。 在这里，我们将系统地研究这49个GPI锚定的甘露糖蛋白在调节 隐球菌与宿主的相互作用。为了实现这一目标，我们建议完成一个基因缺失和基因 GPI锚定甘露糖蛋白超表达文库。我们将使用这些突变体来定义 这些甘露糖蛋白在隐球菌病的动物模型中与宿主相互作用。成功 拟议工作的完成将揭示我们未来可以利用的隐球菌因素或 其他用于研究宿主免疫、抗真菌靶标或诊断标记物。的探索性本质 拟议的工作及其对我们理解主持人和 这种致命的真菌非常适合R21机制。

Cryptococcus neoformans causes fatal cryptococcal meningoencephalitis and is responsible for 15% of deaths in AIDS patients. This fungus can also cause meningoencephalitis in individuals without apparent immuno-deficiency and such incidences are increasing. The outcome of the current antifungal therapy for patients with cryptococcal meningoencephalitis is far from acceptable, with mortality rates ranging from 10 to 70%. The challenges of treating this disease motivate us to understand cryptococcal pathogenesis and to identify cryptococcal factors that shape the interactions between this pathogen and a mammalian host. Our central premise is that cryptococcal factors that modulate host response or neurotropism could provide targets for antifungal therapy, diagnosis, or prevention. Glycosylphosphatidylinositol (GPI)-modified glycoproteins in various eukaryotic pathogens are prominent players in modulating host responses. The effect of these glycoproteins to the host can be protective or deleterious. In C. neoformans, mannoproteins are considered the primary components recognized by the host anti-cryptococcal cell-mediated immune response. However, only several GPI-anchored mannoproteins have been studied in this pathogen, including virulence factors chitin deacetylases Cda1-3 and phospholipase Plb1. We previously found that cryptococcal cells overexpressing an anti-virulence transcription factor Znf2 can confer rare sterilizing immunity to the host against a subsequent challenge by an otherwise lethal wild type strain. Remarkably, 25 out of the 49 predicted GPI-anchored mannoprotein genes in the genome of C. neoformans H99 are regulated by Znf2, with 10 being upregulated and 15 downregulated. This indicates the importance of Znf2 in controlling mannoprotein presentation in this fungus. A recent study indicates that 13 mannoprotein genes are highly differentially expressed in lungs of both mice and monkeys during cryptococcal infection. Given that GPI-anchored mannoproteins are the major class of cell wall proteins and they are also components of the capsule in C. neoformans, we hypothesize that these proteins represent one of the most important groups of factors modulating cryptococcal interactions with the host. Here we will systematically examine the role of these 49 GPI-anchored mannoproteins in modulating Cryptococcus-host interactions. To achieve this goal, we propose to complete a gene deletion and gene overexpression library for the GPI-anchored mannoproteins. We will use these mutants to define the roles of these mannoproteins in cryptococcal interaction with the host in an animal model of cryptococcosis. Successful completion of the proposed work will reveal cryptococcal factors that can be exploited in the future by us or others to investigate host immunity, antifungal targets, or diagnostic markers. The exploratory nature of the proposed work and the potential impact it has on our understanding of the interaction between the host and this deadly fungus fits perfectly for the R21 mechanism.