cAMP signaling pathways within Mycobacterium tuberculosis

描述(申请人提供)：结核分枝杆菌(结核分枝杆菌)是结核病(TB)的病原体，在全球范围内继续对人类健康造成负面影响。该项目的长期目标是了解结核分枝杆菌在感染期间感知宿主环境并对其做出反应的方式，以便开发改进的结核病生物标记物和治疗方法。环磷酸腺苷(CAMP)是一种普遍存在的第二信使，由腺苷环化酶在三磷酸腺苷(ATP)作用下产生，被微生物及其宿主用来感知和响应环境提示。CAMP通过与cAMP受体蛋白(CAMP)样转录因子的变构相互作用，在结核分枝杆菌和其他细菌病原体的毒力基因调控中发挥核心作用。MTB编码两种这样的转录因子：CrpMt，它有助于小鼠模型的毒力；Cmr，它调节Mtb基因在巨噬细胞中的表达。先前的工作表明，当细菌进入巨噬细胞时，结核分枝杆菌内cAMP水平急剧增加，这表明cAMP在感知和响应巨噬细胞内环境方面发挥了作用。目前的项目解决了这样的假设，即cAMP信号通过调节细菌内的基因表达来响应环境条件，从而促进结核分枝杆菌与宿主的相互作用。这一假设将在三个具体目标中得到解决。目标1将重新定义CrpMt调节子及其在结核分枝杆菌中的作用 在全球、细胞和分子水平上的感染过程中的生物学。目的2阐述Cmr在结核分枝杆菌生物学中的作用，重点是它在巨噬细胞感染期间和肉芽肿内调节丙酸代谢的作用。目的3利用分子、遗传和细胞相结合的方法研究CrpMt和CmR作为EspA毒力操纵子的共同调节因子与其他转录因子的作用。这些研究的完成将大大促进对cAMP在结核分枝杆菌生物学中作用的理解，特别是在细菌感应和对宿主相关条件的反应方面。这些信息将有助于确定感染的阶段特异性生物标记物和新的药物靶点。CAMP在调节一系列重要细菌病原体的毒力方面的既定作用，以及结核分枝杆菌中cAMP相关信号蛋白的异常庞大和不寻常的网络，进一步加强了该项目的意义。

DESCRIPTION (provided by applicant): Mycobacterium tuberculosis (Mtb), the causative agent of tuberculosis (TB), continues to negatively impact human health on a global scale. The long term goal of this project is to understand the means by which Mtb senses and responds to its host environment during infection, so that improved biomarkers and treatments for TB disease can be developed. Cyclic AMP (cAMP), which is generated from ATP by adenylyl cyclases, is a universal second messenger used by both microbial pathogens and their mammalian hosts to sense and respond to environmental cues. cAMP plays a central role in virulence gene regulation in Mtb and other bacterial pathogens through its allosteric interactions with cAMP receptor protein (CRP)-like transcription factors. Mtb encodes two such transcription factors: CrpMt, which contributes to virulence in a murine model; and Cmr, which regulates Mtb gene expression within macrophages. Previous work has shown that levels of cAMP within Mtb bacteria increase dramatically upon bacterial entry into macrophages, suggesting a role for cAMP in sensing and responding to the intra-macrophage environment. The current project addresses the hypothesis that cAMP signaling contributes to Mtb-host interactions by regulating gene expression within the bacterium in response to environmental conditions. This hypothesis will be addressed in three specific aims. Aim 1 will redefine the CrpMt regulon and its role in Mtb biology during infection at the global, cellular and molecular levels. Aim 2 addresses the role of Cmr in Mtb biology with a focus on its role in regulating propionate metabolism during macrophage infection and within granulomas. Aim 3 addresses the roles of CrpMt and Cmr as co-regulators with other transcription factors, of the espA virulence operon using a combination of molecular, genetic and cellular approaches. Completion of these studies will significantly advance understanding of cAMP's role in Mtb biology, particularly in the context of bacterial sensing and response to host-associated conditions. This information will contribute to the identification of stage-specific biomarkers of infection and new drug targets. The significance of this project is further enhanced by cAMP's established role in regulating virulence in a wide range of important bacterial pathogens, as well as the exceptionally large and unusual network of cAMP-associated signaling proteins in Mtb.