The link between dimorphism and virulence in Cryptococcus

隐球菌二态性和毒力之间的联系

基本信息

批准号：
9529008
负责人：
Xiaorong Lin
金额：
$ 6.97万
依托单位：
UNIVERSITY OF GEORGIA
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：
2017-08-01 至 2018-11-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/9529008
关键词：
link between dimorphism virulence Cryptococcus

项目摘要

Cryptococcus neoformans causes cryptococcosis that claims hundreds of thousands of lives annually. The mortality rates of this fungal disease are unacceptably high (10-70%). Current antifungal treatments for cryptococcosis are extremely limited and no vaccine is available. Thus, there is a critical need to understand cryptococcal programs that could be selectively targeted by novel antifungals or vaccines. Cryptococcus can assume different morphotypes: the yeast form is considered pathogenic and the filamentous form is associated with attenuated virulence. Therefore, understanding the molecular bases for morphological changes and their impact on cryptococcal virulence could be exploited to combat this fatal disease. During the first phase of this research project, we established Znf2 as the regulator bridging morphotype and virulence potential in Cryptococcus. Deletion of ZNF2 locks cells in the yeast form and enhances cryptococcal virulence. Conversely, ZNF2 overexpression promotes hyphal growth. Cryptococcal cells overexpressing ZNF2 elicit protective defense responses in the mammalian host and are avirulent. More importantly, immunization with ZNF2 overexpression cells, either in live or heat-killed form, can offer 100% protection to the host against a subsequent challenge by an otherwise lethal wild-type H99 infection. Such protection is rarely observed against this deadly fungal pathogen. Therefore, activation of Znf2 represents a promising means to compromise cryptococcal pathogenicity and provides a vehicle to study host immunity. Given that Znf2 is the decision-maker for cryptococcal hyphal morphogenesis and its regulon is enriched with secretory proteins including adhesion proteins, we hypothesize that activation of ZNF2 alters cell surface composition and that certain cellular components present in ZNF2 overexpression cells are effective immunogens. Therefore, for the second phase of this research project, we will identify immunogens present in ZNF2 overexpression cells that can elicit protective host immune responses in aim 1. In aim 2, we will determine Znf2 regulatory circuits (activators, repressors, and/or receptors) and assess their roles in cryptococcal virulence. We hypothesize that turning on the activator and/or inhibiting the repressor of this potent anti-virulence factor could be exploited to compromise cryptococcal pathogenicity during infection. Our preliminary data suggest that Znf2 can be strongly activated artificially during infection, but its activation is subdued in wild-type cells. We expect that results obtained from the second phase of the research project will move us closer to our long term goals: to understand the fundamental requirements for morphogenesis and pathogenicity using Cryptococcus as a genetic model, and to harness such knowledge to develop preventative and therapeutic measures against invasive mycoses.

新型隐球菌引起的隐球菌病每年夺去数十万人的生命。这种真菌病的死亡率高得令人无法接受（10-70%）。目前的抗真菌治疗隐球菌病极为有限，并且没有疫苗可用。因此，迫切需要了解新型抗真菌药物或疫苗可以选择性地针对隐球菌项目。隐球菌可以呈现不同的形态类型：酵母形式被认为是致病性的，而丝状形式则与之相关具有减弱的毒力。因此，了解形态变化的分子基础及其可以利用对隐球菌毒力的影响来对抗这种致命疾病。在本次活动的第一阶段研究项目中，我们建立了 Znf2 作为桥接形态型和毒力潜力的调节剂隐球菌。 ZNF2 的缺失将细胞锁定在酵母形式并增强隐球菌毒力。反过来， ZNF2 过度表达促进菌丝生长。过度表达 ZNF2 的隐球菌细胞引发保护作用哺乳动物宿主的防御反应并且无毒。更重要的是，ZNF2免疫过表达细胞，无论是活的还是热灭活的形式，都可以为宿主提供 100% 的保护，使其免受随后受到致命的野生型 H99 感染的攻击。这种保护很少被遵守对抗这种致命的真菌病原体。因此，Znf2的激活是一种有希望的方法损害隐球菌致病性并提供研究宿主免疫的工具。鉴于 Znf2 是隐球菌菌丝形态发生的决策者及其调节子富含分泌蛋白包括粘附蛋白，我们假设 ZNF2 的激活改变了细胞表面组成，并且 ZNF2 过表达细胞中存在的某些细胞成分是有效的免疫原。因此，对于在这个研究项目的第二阶段，我们将鉴定 ZNF2 过表达细胞中存在的免疫原，可以在目标 1 中引发保护性宿主免疫反应。在目标 2 中，我们将确定 Znf2 调节电路（激活剂、阻遏物和/或受体）并评估它们在隐球菌毒力中的作用。我们假设打开激活剂和/或抑制这种有效的抗毒因子的阻遏物可用于在感染过程中损害隐球菌的致病性。我们的初步数据表明 Znf2 可以在感染过程中人工强烈激活，但其激活在野生型细胞中受到抑制。我们期望研究项目第二阶段取得的成果将使我们更接近我们的长期目标：了解使用隐球菌作为形态发生和致病性的基本要求遗传模型，并利用这些知识来制定预防和治疗措施侵袭性真菌病。