Regulation of immunity by the cGAS-STING pathway

项目摘要 这项建议的目的是剖析环状GMP-AMP酶检测自身DNA的机制 合酶(CGAS)，并确定其不同的信号活动在炎症反应中的相对贡献。 可移植小鼠肿瘤的微环境。CGAS几乎在所有类型的细胞中作为DNA感受器工作 蛋白质，与DNA结合时合成第二信使环状GMP-AMP(CGAMP)。这一秒 信使通过下游的蛋白刺痛刺激干扰素和炎症活动。因为 CGAS检测DNA的糖-磷酸骨架，一个主要的问题涉及到这个酶是如何调节的 以确保自我非自我歧视。这个问题与许多基础生物学有关，答案将是 影响越来越多的针对cGAS-STING途径的临床努力。CGAS-刺痛 在抗肿瘤免疫的背景下，经常讨论这一途径，但这一途径的活动是有益的 (或不)豁免权仍不清楚。例如，cGAS-STING在肿瘤中诱导的炎症活动 微环境(TME)可诱导保护性炎症和细胞溶解的CD8+T细胞。但 CGAS-STING信号事件也被报道促进肿瘤生长和疾病进展。一个 推动我们工作的中心思想是，cGAS-STING通路在大多数细胞类型中普遍存在， 再加上其不同的信号效应因子(cGAMP、IFN、细胞因子)，可以形成复杂的TME 不可预测的结果(例如，疾病的解决或进展)。为了理解这个过程中的每一项活动 途径，需要新的实验工具来解开它的效应器功能。在这里，我们描述了新的 基于合成生物学的遗传电路，可以在癌症中剖析cGAS-STING的效应功能 特别是细胞。值得注意的是，这些系统导致了发现特定特定的能力的差异 灵长类和小鼠cGAS蛋白检测自身DNA。这一发现提出了老鼠是否适合的问题。 和某些灵长类动物作为cGAS刺痛功能的准确临床前模型，并提供了定义 CGAS介导的自身DNA活性的机制和后果。本提案中的工作基于 关于cGAS-STING途径诱导的cGAMP、IFN和细胞因子存在差异的假说 在组织炎症和免疫中的作用，以及了解这些活动中的每一项在 特定的细胞类型，需要对自我(和非自我)DNA检测的机制进行详细的描述。 为了解决这一假设，我们建议确定不同的肿瘤内cGAS活动如何影响 保护性T细胞免疫(目标1)。在目标2中，我们建议通过以下方式确定自身DNA反应性的机制 通过对人、小鼠、黑猩猩和猩猩蛋白质的比较分析，人类cGAS 它们显示了不同的自我DNA反应性。

Project Summary The goal of this proposal is to dissect the mechanisms of self-DNA detection by the enzyme cyclic GMP-AMP synthase (cGAS), and to determine the relative contribution of its diverse signaling activities to inflammation in the microenvironment of implantable murine tumors. cGAS operates in virtually all cell types as a DNA sensory protein, which synthesizes the second messenger cyclic GMP-AMP (cGAMP) upon binding DNA. This second messenger stimulates interferon (IFN) and inflammatory activities via the downstream protein STING. Because cGAS detects the sugar-phosphate backbone of DNA, a major question relates to how this enzyme is regulated to ensure self-nonself discrimination. This question relates to much fundamental biology and the answer will impact the increasing number of clinical endeavors that target the cGAS-STING pathway. The cGAS-STING pathway is oft-discussed in the context of antitumor immunity, but the activities of this pathway that are beneficial (or not) to immunity remain unclear. For example, inflammatory activities induced by cGAS-STING in the tumor microenvironment (TME) have been reported to induce protective inflammatory and cytolytic CD8+ T cells. But cGAS-STING signaling events have also been reported to promote tumor growth and disease progression. A central idea that drives our work is that the ubiquitous presence of the cGAS-STING pathway in most cell types, along with its diverse signaling effectors (cGAMP, IFNs, cytokines), can create a complex TME prone to unpredictable outcomes (e.g. disease resolution or progression). In order to understand each activity of this pathway, new experimental tools are needed to disentangle its effector functions. Herein, we describe new synthetic biology-based genetic circuits that can dissect the effector functions of cGAS-STING, within cancer cells specifically. Notably, these systems led to the discovery of specifies-specific differences in the ability of primate and murine cGAS proteins to detect self-DNA. This finding raises questions of the suitability of mice and certain primates as accurate preclinical models for cGAS-STING function, and provide a mandate to define the mechanisms and consequences of cGAS-mediated self-DNA activities. The work in this proposal is based on the hypothesis that the cGAMP, IFNs and cytokines induced by the cGAS-STING pathway play differential roles in tissue inflammation and immunity, and that understanding the role of each of these activities, within specific cell types, requires a detailed characterization of the mechanisms of self (and nonself) DNA detection. To address this hypothesis, we propose to determine how distinct intra-tumoral cGAS activities influence protective T cell immunity (Aim 1). In Aim 2, we propose to determine mechanisms of self-DNA reactivity by human cGAS through comparative analysis of the human, mouse, chimpanzee and orangutan proteins, each of which display distinct means of self-DNA reactivity.