Environmental Conditions Control Filamentation and Virulence in Candida albicans

描述（由申请人提供）：白色念珠菌是全球口腔念珠菌病的主要原因。从酵母（卵圆形，出芽细胞）到菌丝丝（端对端连接的细长细胞）的可逆转变能力是一个关键的毒力性状，它允许C。白色念珠菌是成功的机会致病菌。向丝状体的转变与其他毒力因子共调节，并且响应于几种宿主环境条件（包括37 ℃、血清、碳/氮饥饿和中性pH）而发生。暴露于这些生长条件激活促进毒力相关基因表达和菌丝生长的许多信号转导途径，但对控制细胞特异性转录因子表达和活性的机制知之甚少。虽然抗真菌疗法可用于治疗念珠菌病，但许多抗真菌药物具有不良副作用，并且是抑制真菌的，而不是杀真菌的。我们研究的长期目标是深入了解形态发生，以确定新的抗真菌药物靶点。我们的目标是了解C。白念珠菌表达的调节因子通过转录和翻译后机制对环境刺激作出反应。我们的研究将集中在Ume 6，Nrg 1和Rfg 1，这些关键转录因子调节菌丝特异性基因的表达和表达。我们假设，环境的不良诱导条件差异控制Ume 6，Nrg 1和Rfg 1的转录调控和活性。我们提出了以下具体目标来解决我们的假设：具体目标1：确定UME 6和NRG 1在环境诱导条件下转录调控的机制。具体目标2：确定Ume 6、Nrg 1和Rfg 1在几种环境条件下的转录活性。 为了解决目标1，我们将使用启动子缺失分析与lacZ报告分析，电泳迁移率变动分析和质谱法，以确定控制NRG 1和UME 6表达的转录调节因子，以响应特定的环境刺激。为了解决目标2，我们将使用具有lacZ报告基因的单杂交系统来研究响应于环境条件的Ume 6、Nrg 1和Rfg 1的转录活性。我们将在两个目标中使用RT-qPCR来定量lacZ表达。通过本课题的研究，我们希望能对C.白色念珠菌的形态发生，这将有助于新的抗真菌治疗的发展。 公共卫生相关性：白色念珠菌是全球口腔真菌感染的主要原因，部分原因是全球艾滋病毒大流行。我们的研究将深入了解一个关键的毒力因子，即在酵母和丝状形式之间转换的能力，这使得这种生物体成为成功的机会致病菌。这些知识将有助于开发新的抗真菌疗法。

DESCRIPTION (provided by applicant): Candida albicans is the leading cause of oral candidiasis worldwide. The ability to undergo a reversible transition from yeast (ovoid, budding cells) to hyphal filaments (elongated cells attached end-to-end) is a key virulence trait that allows C. albicans to be a successful opportunistic pathogen. The transition to filaments is co-regulated with other virulence factors and occurs in response to several host environmental conditions including 370C, serum, carbon/nitrogen starvation and neutral pH. Exposure to these growth conditions activates numerous signal transduction pathways that promote virulence-related gene expression and hyphal growth, but little is known about the mechanisms that control the expression and activity of filament-specific transcription factors. Although antifungal therapies are available to treat candidiasis, many antifungal drugs have adverse side effects and are fungistatic, not fungicidal. The long term goal of our studies is to gain insight into morphogenesis to identify novel antifungal drug targets. Our objective is to understand how C. albicans regulators of filamentation respond to environmental stimuli via transcriptional and posttranslational mechanisms. Our studies will focus on Ume6, Nrg1 and Rfg1, key transcription factors that regulate hyphal- specific gene expression and filamentation. We hypothesize that environmental filament-inducing conditions differentially control the transcriptional regulation and activity of Ume6, Nrg1 and Rfg1. We propose the following Specific Aims to address our hypothesis: Specific Aim 1: Determine the mechanism(s) by which UME6 and NRG1 are transcriptionally regulated in response to environmental filament-inducing conditions. Specific Aim 2: Determine the transcriptional activity of Ume6, Nrg1 and Rfg1 in response to several environmental conditions. In order to address Aim 1, we will use a promoter deletion analysis with a lacZ reporter assay, electrophoretic mobility shift assays and mass spectrometry to identify the transcriptional regulators that control NRG1 and UME6 expression in response to specific environmental stimuli. To address Aim 2, we will use a one-hybrid system with a lacZ reporter gene to investigate the transcriptional activity of Ume6, Nrg1 and Rfg1 in response to environmental conditions. We will use RT-qPCR in both Aims to quantify lacZ expression. At the completion of our studies, we expect to have a better understanding of the environmental regulation of C. albicans morphogenesis, which will aid in the development of new antifungal therapies. PUBLIC HEALTH RELEVANCE: Candida albicans is the leading cause of oral fungal infections worldwide due, in part, to the global HIV pandemic. Our studies will provide insight into a key virulence factor, the ability to switch between yeast and filamentous forms, which makes this organism a successful opportunistic pathogen. This knowledge will aid in the development of new antifungal therapies.