Analysis of Candida albicans NRG1-regulated gene expression in vivo.

描述（由申请人提供）：白色念珠菌是迄今为止最常从人类分离的真菌。它是人类的一种正常共生体，但也能够侵入人体的几乎每一个部位，并引起感染，特别是在艾滋病毒感染或免疫功能低下的宿主中。这种生物能够在单细胞酵母样形态（胚孢子）和丝状形态（根据丝状结构的细微变化称为菌丝或假菌丝）之间进行可逆的形态转变，以响应外部环境的变化，这种能力被认为是其致病潜力的关键。然而，这种信念主要是基于大量使用白色念珠菌突变株(即？cphl, ?efgl, ?tupl, ?Nrgl)无法经历这种形态发生转换：因为所有这些菌株都被锁定在一种或另一种形式，所以无法就这些形态发生变化在毒力中的作用得出明确的结论。为了解决这些问题，我们设计了一种条件突变株，其中灯丝的负调节因子（NRG1）置于四环素可调节启动子的控制下。对该菌株的分析表明，形态转变，也许更重要的是，在动物宿主感染期间，通过简单地改变真菌中NRG1的表达量，可以改变生物体的毒力。然而，NRG1 p已知是一种全局抑制蛋白，负责抑制许多白色念珠菌基因，并非所有这些基因都参与丝状过程。因此，本提案的目的是通过对直接从感染动物组织中分离的真菌细胞进行微阵列分析，研究NRG1过表达如何改变白色念珠菌的全局表达谱。与公共卫生的相关性：白色念珠菌是念珠菌病的主要病原体，念珠菌病是最常见的真菌感染，现在是美国医院感染的第四大原因，死亡率高，经济负担飙升。这项研究背后的主要思想是进一步研究由关键调控基因控制的丝状物与毒力之间的关系，这可能为开发治疗这些感染的新策略奠定基础。

DESCRIPTION (provided by applicant): Candida albicans is by far the most frequently isolated fungus from humans. It is a normal commensal of Man but is also capable of invading almost every site in the body and causing infections particularly in HIV infected or otherwise immunocompromised hosts. The organism is able to undergo reversible morphological transitions between unicellular yeast-like forms (blastospores) and filamentous forms (called hyphae or pseudohyphae depending on slight variations in the structure of the filament), in response to changes in the external environment, and this ability is considered pivotal to its pathogenic potential. However, this belief is based primarily upon the results obtained from a large number of virulence studies using C. albicans mutant strains (i.e. ?cphl, ?efgl, ?tupl, ?nrgl) unable to undergo this morphogenetic switch: because all of these strains are locked in one or other form, definitive conclusions on the role of these morphogenetic changes in virulence cannot be made. To address these concerns, we engineered a conditional mutant strain in which a negative regulator (NRG1) of filamentation was placed under the control of a tetracycline regulatable promoter. Analysis of this strain has revealed that morphological transitions and, perhaps more importantly, the virulence of the organism can be modified during an infection within an animal host by simply altering the amount of NRG1 being expressed in the fungus: Nrg1 p, however, is known to be a global repressor protein responsible for the suppression of numerous C. albicans genes not all of which are involved in the process of filamentation. The aim of this proposal therefore is to examine how the C. albicans global expression profile is altered by NRG1 overexpression by performing microarray analysis of fungal cells isolated directly from infected animal tissues. Relevance to public health: Candida albicans is the main causative agent of candidiasis, the most frequent fungal infection and now the fourth leading cause of infections in US hospitals, with high mortality rates and soaring economic burden. The main idea behind this study is to further investigate the relationship between filamentation and virulence, as controlled by key regulatory genes, which may serve as the basis for the development of novel strategies for the treatment of these infections.