Investigate the multifunctional adhesins in Cryptococcus

描述（由申请人提供）：除了一般人群中的浅表和皮肤感染外，真菌还可在免疫受损个体中引起通常致命的全身感染。例如，新型隐球菌对公共卫生构成严重威胁，每年造成50多万人死亡。目前的抗真菌药物治疗远远不能令人满意，迫切需要替代或辅助治疗，包括疫苗接种和免疫治疗。因此，它是必要的，以确定和表征隐球菌的因素，塑造真菌和宿主之间的相互作用。隐球菌可呈现两种形态型：酵母和丝状。以往的研究表明隐球菌的形态和毒力之间的关联。申请人的小组最近发现转录因子Znf2充当形态发生和毒力之间的分子联系。Znf2决定细胞的粘附、定向和孢子形成。Znf2过表达的隐球菌细胞刺激保护性宿主免疫应答，并失去在小鼠模型中引起致命疾病的能力。Znf2的主要靶点之一是粘附蛋白（adhesin）Cfl1。cfl 1在酵母到丝状体的转变过程中上调，并且它覆盖菌丝和由菌丝产生的感染性孢子的表面。重要的是，Cfl1在酵母细胞中的过表达显著改变了隐球菌的毒力。因此，Cfl1，天然涂层表面的隐球菌感染性繁殖体，可能参与宿主和病原体之间的相互作用。令人惊讶的是，Cfl1不仅作为粘附蛋白对复杂群落（生物膜）的形成很重要，而且释放的Cfl1还作为信号分子刺激邻近细胞形成复杂集落并经历细胞分化。这些初步的数据导致的假设，分泌粘附素调节真菌群落行为，通过其多功能。这一假设将得到检验 通过追求以下具体目标。(Aim 1）阐述Cfl1发布后发起的信令网络。(Aim 2）表征潜在粘附素的概要并检查它们在酵母、菌丝和孢子中的表达模式。由于隐球菌孢子和宿主之间的初始相互作用对感染的结果至关重要，因此隐球菌孢子表面粘附素的表征对于促进我们对隐球菌生物学和发病机制的理解非常重要。这项拟议的研究是第一个证明粘附素介导的信号在非移动的真核微生物，并首次调查孢子粘附素在这种病原体。鉴于微生物粘附素在感染性疾病中的重要性，本研究将为进一步研究粘附素在隐球菌发病机制中的作用以及将来开发此类分子用于临床应用提供垫脚石。

DESCRIPTION (provided by applicant): Besides superficial and cutaneous infections in the general population, fungi can cause often fatal systemic infections in immune-impaired individuals. For instance, Cryptococcus neoformans poses a serious threat to public health and is responsible for the death of more than half a million people each year. The current antifungal drug therapies are far from satisfactory and there is a critical need for alternative or adjunct therapies, including vaccination and immunotherapy. Thus it is imperative to identify and characterize Cryptococcus factors that shape the interactions between the fungus and the host. Cryptococcus can assume two morphotypes: yeast and filament. Previous studies indicate the association between the morphotype and cryptococcal virulence. The applicant's group recently discovered that the transcription factor Znf2 serves as the molecular link between morphogenesis and virulence. Znf2 dictates cell adhesion, filamentation, and sporulation. Cryptococcus cells with Znf2 overexpression stimulate protective host immune responses and lose the ability to cause fatal diseases in mouse models. One of Znf2's prominent targets is the adhesion protein (adhesin) Cfl1. Cfl1 is up-regulated during the yeast-to-filament transition and it coats the surface of hyphae and infectious spores generated from hyphae. Importantly, overexpression of Cfl1 in the yeast cells significantly alters Cryptococcus virulence. Thus Cfl1, which naturally coats the surface of Cryptococcus infectious propagules, is likely involved in the interaction between the host and the pathogen. Surprisingly, Cfl1 not only is important for the formation of complex communities (biofilm) as an adhesion protein, but the released Cfl1 also elicits neighboring cells to form complex colonies and to undergo cellular differentiation as a signaling molecule. These preliminary data lead to the hypothesis that secreted adhesins regulate fungal community behaviors via their multi-functionalities. This hypothesis will be tested by pursuing the following specific aims. (Aim 1) Elucidate the signaling network initiated by released Cfl1. (Aim 2) Characterize a compendium of potential adhesins and examine their expression pattern in yeasts, hyphae and spores. Because the initial interaction between Cryptococcus spores and the host is critical for the outcome of the infection, characterization of adhesins on the surface of Cryptococcus spores is important for advancing our understanding of Cryptococcus biology and pathogenesis. This proposed research is the first to demonstrate adhesin-mediated signaling in a non-mobile eukaryotic microbe, and the first to investigate spore adhesins in this pathogen. Given the importance of microbial adhesins in infectious diseases, this research will provide a stepping stone for further investigation of adhesins' roles in Cryptococcus pathogenesis and for future exploitation of such molecules for clinical applications.