NRG1 Regulated Genes in Candida albicans Pathogenicity

描述(申请人提供)：白色念珠菌是最常见的念珠菌病病原体，现在是医院感染的第四大原因。即使接受积极的药物治疗，患者的预后也不好，死亡率从30%到50%不等，更不用说与治疗相关的重大经济负担了。白念珠菌能够在单细胞、酵母样形态和丝状形态之间经历可逆的形态转变，正是这一属性被认为是其致病潜力的关键。然而，目前对形态发生在白念珠菌毒力中所起作用的理解主要是基于使用无法进行这一发育计划的基因定义的突变菌株的研究获得的数据。为了克服这些担忧，我们构建了一株TET-NRG1可调控菌株(SSY50-B)，在该菌株中，形态发生转化可以在体外和体内进行操纵。使用该菌株进行的毒力研究提供了迄今为止最令人信服的证据，将这种机会性病原体的形态发生和毒力联系起来。本应用旨在进一步探索NRG1调控白念珠菌丝状化和毒力的机制，为此我们提出了三个具体目标：i)使用遗传筛选来鉴定NRG1调控的基因，这些基因在白念珠菌丝状化和致病过程中发挥关键作用；ii)通过构建“敲除”突变株并在播散性白念珠菌病小鼠模型中测试它们，来评估NRG1调控基因在毒力中的单独作用；iii)筛选小分子文库，通过模拟白念珠菌Nrglp功能来鉴定抑制丝状化和毒力的化合物。 与公共卫生相关：白色念珠菌是念珠菌病的主要病原体，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。这项研究的主要思想是进一步研究丝状化和毒力之间的关系，这是由关键调控基因控制的，这可能成为开发治疗这些感染的新策略的基础。

DESCRIPTION (provided by applicant): Candida albicans is the most common etiological agent of candidiasis, now the fourth leading cause of nosocomial infections. Even with aggressive drug therapy the prognosis for the patient is not good with mortality rates ranging from 30-50%, not to mention the significant economic burden associated with treatment. C. albicans is able to undergo reversible morphological transitions between unicellular yeast-like and filamentous forms and it is this attribute that is considered pivotal to its pathogenic potential. However, the current understanding of the role played by morphogenesis in C. albicans virulence is based primarily on data obtained from studies using genetically defined mutant strains unable to undergo this developmental programme. To overcome these concerns, we have constructed a tet-NRG1 regulatable strain (SSY50-B) in which morphogenetic conversions can be externally manipulated both in vitro and in vivo. Virulence studies performed using this strain have provided the most compelling evidence to date linking morphogenesis and virulence in this opportunistic pathogen. This application aims to further explore the mechanisms by which NRG1 regulates C. albicans filamentation and virulence for which we propose three specific aims: i) to use a genetic screen to identify NRG1-regulated genes that play key roles in C. albicans filamentation and pathogenesis, ii) to assess the individual roles of the NRG1-regulated genes in virulence by constructing "knock out" mutant strains and testing them in a murine model of disseminated candidiasis and iii) to screen small molecule libraries to identify compounds that inhibit filamentation and virulence by mimicking C. albicans Nrglp function. 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.