Mechanistic Studies of Cytoplasmic dsDNA-Sensing Pathways

项目摘要 dsDNA在细胞质中的存在标志着真核细胞中的严重问题，范围从 线粒体功能失调导致病原体入侵。在哺乳动物中，先天免疫系统检测到这些流氓 dsDNA并引发炎症反应。胞质dsDNA传感途径是宿主细胞的组成部分， 它们的功能障碍也与各种人类疾病有关。 在这里，我们将定义细胞质dsDNA传感器启动宿主先天性 免疫系统以协调的方式反应。在目标1中，我们将解决有关 cGAS的激活机制，例如为什么dsDNA长度重要（或不重要），N结构域的作用是什么，以及 cGAS如何在dsDNA上二聚化。在目标2中，我们将解决一个基本的机械问题， 关于什么定义了cGAS、AIM 2和IFI16的dsDNA特异性，免疫学是一个重要的研究领域。然后我们将测试 细胞RNA可以充当缓冲剂，以使这些传感器的假激活最小化。在目标3中，我们 确定cGAS、AIM2、IFI16和TREX1核酸酶的差异动力学是否可以塑造整体的 宿主对胞质dsDNA反应。然后，我们将研究这些之间的激动和拮抗作用， 传感器在产生针对细胞质dsDNA的良好平衡的宿主应答中的作用。

Project summary The presence of dsDNA in the cytoplasm signals serious problems in eukaryotic cells, ranging from dysfunctional mitochondria to pathogen invasion. In mammals, the innate immune system detects these rogue dsDNA and initiate inflammatory responses. Cytoplasmic dsDNA sensing pathways are integral to host defense against numerous pathogens, and their malfunctions are also implicated in various human maladies. Here, we will define the molecular mechanisms by which cytoplasmic dsDNA sensors initiate host innate immune responses in a coordinated fashion. In Aim 1, we will resolve several controversies regarding the activation mechanism of cGAS such as why dsDNA length matters (or not), what the role of N-domain is, and how cGAS dimerizes on dsDNA. In Aim 2, we will resolve a fundamental mechanistic question in innate immunology as to what defines the dsDNA specificity of cGAS, AIM2, and IFI16. We will then test whether cellular RNA can act as a buffer to minimize the spurious activation of these sensors. In Aim 3, we will determine whether differential kinetics of cGAS, AIM2, IFI16, and the TREX1 nuclease can shape the overall host response against cytoplasmic dsDNA. We will then investigate agonism and antagonism among these sensors in generating well-balanced host responses against cytoplasmic dsDNA.