Investigate the multifunctional adhesins in Cryptococcus

描述（由申请人提供）：除了普通人群的浅表和皮肤感染外，真菌还可以引起免疫受损个体的致命全身感染。例如，新型隐球菌对公众健康构成严重威胁，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，确定和表征影响真菌和宿主之间相互作用的隐球菌因子是势在必行的。隐球菌可以有两种形态：酵母和细丝。先前的研究表明形态与隐球菌毒力之间存在关联。申请人小组最近发现转录因子Znf2是形态发生和毒力之间的分子联系。Znf2决定细胞粘附、成丝和产孢。在小鼠模型中，Znf2过表达的隐球菌细胞刺激保护性宿主免疫反应，并失去引起致命疾病的能力。Znf2的主要靶点之一是粘附蛋白（adhesion protein） Cfl1。Cfl1在酵母向丝的转变过程中被上调，它覆盖在菌丝和由菌丝产生的感染性孢子的表面。重要的是，酵母细胞中Cfl1的过表达显著改变隐球菌的毒力。因此，天然包裹在隐球菌感染性繁殖体表面的Cfl1很可能参与了宿主与病原体之间的相互作用。令人惊讶的是，Cfl1不仅作为一种粘附蛋白对复杂群落（生物膜）的形成很重要，而且释放的Cfl1还作为一种信号分子诱导邻近细胞形成复杂的菌落并进行细胞分化。这些初步数据导致了分泌黏附素通过其多功能调节真菌群落行为的假设。这一假设将得到验证

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.