Coordinated Regulation of Virulence Genes in C. neoformans

描述（由申请人提供）：为了在被感染宿主的恶劣环境中生存，病原微生物必须能够感知和适应不断变化的环境条件。这种适应需要多种细胞因子的协调调节。与许多感染因子一样，人类真菌病原体新型隐球菌使用保守的信号分子环AMP （cAMP）来调节其对外部应激的反应。cAMP信号转导通路的核心成分在微生物中高度保守。然而，本研究的主要假设是cAMP的上游激活信号和下游效应物在功能上专一于微生物病原体。这种专门化允许致病生物使用cAMP信号来特异性地控制它们的毒力潜力。在过去的几年里，我们已经证明了C. neoformans的cAMP途径是适应宿主环境所必需的。这条通路调节了荚膜和黑色素的诱导，这两种细胞因子是发病所必需的。这种调控主要发生在转录水平上。因此，我们设计了本提案的实验，以确定控制胶囊相关基因转录的反式和顺式调控元件。Specific Aim 1提出了生物信息学和转录谱分析方法来鉴定控制新生荚膜基因表达的转录因子。特异性目标2概述了选定的转录调节因子的详细测试，以确定其在胶囊诱导中的作用。Specific Aim 3中的实验将定义前两个Aims中确定的转录因子的直接和间接靶基因。一旦完成，这些实验将为这种特定病原体感知和响应其宿主的方式提供新的见解。通过定义保守信号通路的新功能，这些实验还将探索环境感知、细胞应激和微生物毒力等更广泛的问题。

DESCRIPTION (provided by applicant): To survive within the hostile environment of the infected host, pathogenic microorganisms must be able to sense and adapt to changing environmental conditions. This adaptation requires the coordinated regulation of multiple cellular factors. Like many infectious agents, the human fungal pathogen Cryptococcus neoformans uses the conserved signaling molecule cyclic AMP (cAMP) to regulate its response to external stresses. The central components of cAMP signal transduction pathways are highly conserved among microorganisms. However, the main hypothesis of this proposal is that the upstream activating signals and the downstream effectors of cAMP are functionally specialized in microbial pathogens. This specialization allows pathogenic organisms to use cAMP signaling to specifically control their virulence potential. Over the past several years, we have demonstrated that the C. neoformans cAMP pathway is required for adaptation to the host environment. This pathway regulates the induction of capsule and melanin, two cellular factors required for pathogenesis. This regulation occurs primarily at the level of transcription. Therefore, we designed the experiments of this proposal to identify trans- and cis-acting regulatory elements that control the transcription of capsule-associated genes. Specific Aim 1 proposes bioinformatic and transcriptional profiling approaches to identify transcription factors that control C. neoformans capsule gene expression. Specific Aim 2 outlines detailed testing of selected transcriptional regulators to define their role in capsule induction. Experiments in Specific Aim 3 will define the direct and indirect target genes of the transcription factors identified in the first two Aims. Upon completion, these experiments will offer new insight into the ways in which this specific pathogen senses and responds to its host. By defining new functions for conserved signaling pathways, these experiments will also explore broader issues in environmental sensing, cellular stress, and microbial virulence.