Defining the genetic network governing cryptococcal morphological transition

定义控制隐球菌形态转变的遗传网络

基本信息

批准号：
10170231
负责人：
Xiaorong Lin
金额：
$ 47.18万
依托单位：
UNIVERSITY OF GEORGIA
依托单位国家：
美国
项目类别：
财政年份：
2018
资助国家：
美国
起止时间：
2018-06-11 至 2024-05-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/10170231
关键词：
Acquired Immunodeficiency Syndrome Antifungal Agents Attenuated Biological Assay Candida albicans Candidate Disease Gene Cell Nucleus Cells Central Nervous System Diseases Cessation of life Clinical Complex Cryptococcal Meningitis Cryptococcosis Cryptococcus Cryptococcus neoformans Development Disease Filament Future Gene Deletion Genetic Genetic Epistasis Genetic Screening Goals Immune Immune response Immunity Immunization In Vitro Induced Mutation Infection Insertional Mutagenesis Link Measures Modeling Molecular Morphogenesis Morphology Mutation Nuclear Nuclear Translocation Partner in relationship Pathogenesis Pathogenicity Pathway interactions Patients Pattern Phenotype Pheromone Phosphotransferases Play Proteins Public Health Refractory Regulation Research Role Serotyping Signal Pathway Stimulus Testing Virulence Virulent Work Yeasts Zinc Fingers attenuation base design fungus genetic linkage genome sequencing in vivo mortality mutant novel therapeutics opportunistic pathogen overexpression prevent programs protein expression response transcription factor vaccine access

项目摘要

Abstract Cryptococcal meningitis is an AIDS-defining condition and it is responsible for 15% of the deaths in AIDS patients. The disease has mortality rates up to 70% and it claims hundreds of thousands of lives each year. The existing antifungal drugs are not always effective and there is no vaccine available against cryptococcosis. The challenges of preventing and treating this disease motivate us to investigate cryptococcal pathogenesis and identify cryptococcal pathways that can induce a protective host response. Cryptococcus neoformans can undergo yeast-to-filament morphological transition. We and others have shown that morphotype has a profound effect on cryptococcal interaction with various hosts. In mammalian models of cryptococcosis, the yeast form is pathogenic while the filamentous form is attenuated/abolished in virulence. Previously, we identified a key regulator of filamentation, Znf2. Deletion of ZNF2 locks cells in the yeast form and enhances virulence. Overexpression of ZNF2 promotes filamentation in vitro and in vivo, abolishes virulence, and can offer rare sterilizing immunity against an otherwise lethal challenge. Based on these studies, we hypothesize that activating the cryptococcal filamentation program can elicit protective host responses and alleviate cryptococcosis. The goal of this application is to characterize filamentation pathways and identify those that induce protective host responses and attenuate cryptococcal virulence. Capitalizing on our recent discoveries of self-filamentation in natural isolates of C. neoformans species complex (serotype A and D), we performed multiple large genetic screens and identified candidate genes that play important roles in filamentation in vitro. Among these candidates, multiple components of the osmotic sensing pathway suppress filamentation in the serotype A reference strain H99 by inhibiting nuclear translocation of the transcription factor Crz1, which acts upstream of Znf2. In Aim 1, we will define the mechanism by which Crz1 distinguishes different stimuli to activate filamentation. In Aim 2, we will characterize the identified candidates and establish their genetic relationship with Znf2 in controlling cryptococcal virulence and morphology in vivo. In Aim 3, we will test the avirulent strains for their immunization effect and their combined effect with Znf2 on host immunity. The work will generate a set of Cryptococcus morphological mutants that induce protective host responses. These findings will reveal targets that can be exploited in the future by us and others to investigate new measures against this deadly fungal disease.

抽象的隐球菌性脑膜炎是一种艾滋病定义的疾病，它导致了 15% 的死亡艾滋病患者。这种疾病的死亡率高达 70%，每年夺去数十万人的生命年。现有的抗真菌药物并不总是有效，并且没有针对真菌的疫苗隐球菌病。预防和治疗这种疾病的挑战促使我们研究隐球菌发病机制并确定可以诱导保护性宿主反应的隐球菌途径。新型隐球菌可以经历酵母到丝状体的形态转变。我们和其他人有研究表明形态类型对隐球菌与各种宿主的相互作用具有深远的影响。在哺乳动物中在隐球菌病模型中，酵母形式具有致病性，而丝状形式在隐球菌病模型中被减弱/消除毒力。之前，我们确定了丝状形成的关键调节因子 Znf2。 ZNF2 的缺失将细胞锁定在酵母形成并增强毒力。 ZNF2 的过度表达可促进体外和体内的丝状形成，消除毒力，并可以针对其他致命的挑战提供罕见的灭菌免疫力。基于在这些研究中，我们假设激活隐球菌丝状程序可以引发保护性宿主反应并减轻隐球菌病。该应用的目标是表征丝化途径并确定那些诱导保护性宿主反应并减弱隐球菌的途径毒力。利用我们最近在新型隐球菌天然分离株中发现的自丝状结构复杂（血清型 A 和 D），我们进行了多次大型遗传筛选并鉴定了候选基因在体外丝状形成中发挥重要作用。在这些候选者中，渗透压的多种成分传感途径通过抑制核来抑制血清型 A 参考菌株 H99 中的丝状化转录因子 Crz1 的易位，作用于 Znf2 的上游。在目标 1 中，我们将定义 Crz1 区分不同刺激以激活丝状化的机制。在目标 2 中，我们将表征已识别的候选者并在控制中建立它们与 Znf2 的遗传关系隐球菌体内毒力和形态。在目标 3 中，我们将测试无毒株的免疫能力作用及其与 Znf2 的联合作用对宿主免疫的影响。该工作将生成一组隐球菌诱导保护性宿主反应的形态突变体。这些发现将揭示可以实现的目标我们和其他人将来会利用它来研究针对这种致命真菌疾病的新措施。