The link between dimorphism and virulence in Cryptococcus

描述（由申请方提供）：本提案旨在鉴定和表征真菌新型隐球菌中可用作靶点以损害其致病性的因子。隐球菌是一种二型真菌：当它处于酵母形式时，它通常引起疾病，而当它处于丝状形式（假菌丝或菌丝）时，它的毒性较小。由于响应宿主线索调节生长形式的能力是许多真核微生物引起疾病的基本要求，激活适当的发育调节回路可能对隐球菌在宿主条件下的生存和繁殖至关重要。不幸的是，隐球菌的二型性和毒力之间联系的分子基础仍然是一个谜。 隐球菌的丝状化历来被认为与交配有关，而交配在宿主条件下受到抑制。在申请人的实验室中进行的初步研究表明，遗传操作可以在与宿主生理相关的条件下赋予隐球菌丝状生长。Znf2是一种锌指转录因子，它是一种主要的细胞粘附调节因子，也决定了细胞的粘附（絮凝）。重要的是，Znf2对隐球菌的致病性有负面影响。因此，Znf2提供了一个链接，以了解隐球菌的二型性和毒力的分子基础。该提议的中心假设是Znf2通过控制细胞形态型和通常与形态发生相关的其他特征来介导隐球菌引起疾病的能力。在强有力的初步数据的指导下，该假设将通过追求以下具体目标进行测试：1）。建立ZNF2表达、表达能力、细胞粘附和隐球菌毒力之间的关系。2）。表征额外的决定因素的抑制和Znf2目标，并确定其在毒力中的作用。为了了解隐球菌的二型性和毒力，对调节进行交配的固有能力的因素的关注代表了与当前以导致交配的信号传导途径为中心的方法的实质性偏离。基于这一新视角的研究有望产生对隐球菌中新型毒力决定因素的机制性见解。考虑到隐球菌与其他环境获得的二型病原体（不同的门）的分歧，这些病原体也显示出类似的致病性和毒力之间的逆相关性，这项研究很可能会确定真菌二型性所需的保守决定因素。由于隐球菌是一种临床上重要的病原体，并适合遗传和分子研究，这项研究将有助于更广泛地了解细胞形状的决定和形态对微生物病原体生存的影响。长期目标是了解真菌病原体常见的形态发生和致病性的基本要求，并利用这些知识来制定针对侵袭性真菌病的预防和治疗措施。

DESCRIPTION (provided by applicant): This proposal is to identify and characterize factors in the fungus Cryptococcus neoformans that can be used as targets to compromise its pathogenicity. Cryptococcus is a dimorphic fungus: it generally causes diseases when it is in the yeast form and it is less virulent when it is in the filamentous form (pseudohyphae or hyphae). As the ability to regulate growth form in response to host cues is an essential requirement for many eukaryotic microbes to cause diseases, activating appropriate regulatory circuits for development is likely to be critical for the survival and propagation of Cryptococcus under host conditions. Unfortunately, the molecular bases underlying the link between dimorphism and virulence in Cryptococcus remain an enigma. Filamentation in Cryptococcus has historically been considered to be coupled with mating, which is suppressed under host conditions. Preliminary studies performed in the applicant's lab indicate that genetic manipulation can confer Cryptococcus filamentous growth under conditions that are host physiologically relevant. Znf2, a zinc finger transcription factor, is a master regulator of filamentation and it also dictates cell adhesion (flocculation). Importantly, Znf2 negatively impact Cryptococcus pathogenicity. Thus, Znf2 provides a link to understand the molecular bases of dimorphism and virulence in Cryptococcus. The central hypothesis of this proposal is that Znf2 mediates the ability of Cryptococcus to cause disease by controlling cell morphotype and other features normally associated with morphogenesis. Guided by strong preliminary data, the hypothesis will be tested by pursuing the following specific aims: 1). Establish the relationship between ZNF2 expression, the ability to undergo filamentation, cell adhesion, and Cryptococcus virulence. 2). Characterize additional determinants of filamentation and Znf2 targets, and determine their roles in virulence. The focus on factors that regulate the inherent ability to undergo filamentation in order to understand dimorphism and virulence in Cryptococcus represents a substantial departure from current approaches that are centered on the signaling pathways that lead to mating. Research based on this new vision is expected to generate mechanistic insights into novel virulence determinants in Cryptococcus. Given the divergence of Cryptococcus from other environmentally-acquired dimorphic pathogens (different phyla) that also show a similar inverse association between filamentation and virulence, it is highly likely that this research will identify conserved determinants necessary for fungal dimorphism. As Cryptococcus is both a clinically important pathogen and is amenable to genetic and molecular studies, this research will contribute to a broader understanding of cell-shape determination and the impact of morphotype on the survival of microbial pathogens. The long-term goals are to understand the fundamental requirements for morphogenesis and pathogenicity that are common to fungal pathogens, and to harness such knowledge to develop preventative and therapeutic measures against invasive mycoses.