Defining the genetic network governing cryptococcal morphological transition

摘要 隐球菌性脑膜炎是一种定义艾滋病的疾病，它导致了#年15%的死亡 艾滋病患者。这种疾病的死亡率高达70%，每个人都夺去了数十万人的生命 年。现有的抗真菌药物并不总是有效的，也没有疫苗可用来对抗 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 致病机制，并确定可诱导保护性宿主反应的隐球菌途径。 新生隐球菌可以经历酵母到细丝的形态转变。我们和其他人有 表明形态类型对隐球菌与各种宿主的相互作用有深远的影响。在哺乳动物中 隐球菌病的模型，酵母形态是致病的，而丝状形态在 致命性。在此之前，我们发现了丝化的关键调控因子--锌锌。删除ZNF2会将单元锁定在 酵母菌形成并增强毒力。ZNF2的过表达促进了体外和体内的丝状化， 废除毒力，并能提供罕见的杀菌免疫力，以应对否则致命的挑战。基于 在这些研究中，我们假设激活隐球菌丝形成程序可以诱导保护性宿主 应对措施和缓解隐球菌病。这个应用程序的目标是描述成丝的特征 并识别那些诱导保护性宿主反应和减弱隐球菌的途径 致命性。 利用我们最近在新生隐孢子虫自然分离株中发现的自丝化现象 复杂(A型和D型)，我们进行了多个大的基因筛查，并确定了候选基因 在体外丝状化过程中发挥重要作用。在这些候选者中，渗透剂的多种成分 传感通路通过抑制核抑制A型参考菌株H99中的丝状化 转录因子Crz1的易位，它作用于Znf2的上游。在目标1中，我们将定义 Crz1通过区分不同的刺激来激活丝状化的机制。在目标2中，我们将 对已确定的候选基因进行表征，并建立其与锌氟化合物的亲缘关系 隐球菌体内毒力和形态。在目标3中，我们将测试无毒菌株的免疫效果。 2对寄主免疫的影响及其与锌粉的联合作用。这项工作将产生一组隐球菌 诱导保护性宿主反应的形态突变体。这些发现将揭示可以 在未来被我们和其他人利用来研究对抗这种致命真菌疾病的新措施。

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.