Regulatory crosstalk between human Caspases & Guanylate Binding Proteins in antimicrobial host-defence

背景：对感染原迅速和适当的反应对于清除感染是重要的。免疫系统依赖于先天防御的早期机制，这些机制适当地指导感染几天后部署的晚期机制。这两个系统协同工作，不正确的早期反应可能导致器官中微生物传播增加，炎症和组织损伤。早期反应的一个关键作用是快速识别感染的类型，例如是否是细菌，病毒或寄生虫，并以有效对抗特定类型病原体的方式作出反应。两个酶家族在早期免疫防御中起重要作用，鸟苷酸结合蛋白（GBP）和半胱天冬酶。GBP是将GTP分子转化为GDP的酶，并充当分子开关。半胱天冬酶是一种酶，它充当分子剪刀，切割一系列参与免疫的重要蛋白质。半胱天冬酶的分子切割对于细胞中许多蛋白质的正常功能是重要的。GBP和半胱天冬酶共同作用于不同的感染因子并保护我们。我们以前表明，家族成员GBP 1有助于早期免疫应答，以对抗致病性细菌病原体沙门氏菌以及引起各种脑部疾病的寄生虫病原体弓形虫。其他人已经表明，GBP和半胱天冬酶一起帮助防御疾病，例如细菌性腹泻、兔热病、军团病、HIV等。这反映了这些蛋白质的广泛保护作用及其在人类感染中的重要性。有趣的是，这些病原体侵入并驻留在我们自己的细胞中，如免疫细胞，脑细胞，肠细胞，它们在那里生长和繁殖。GBP和半胱天冬酶清除受感染的细胞，防止病原体的生长和传播。因此，这些酶在人类免疫反应中至关重要，需要更好地了解它们的作用。GBP和半胱天冬酶如何确切地合作仍然不清楚。目的和方法：我们的总体目标是了解GBP和半胱天冬酶如何保护我们免受感染的分子和细胞机制。它们的联合作用检测不同微生物的感染，并启动一系列事件，导致受感染的宿主细胞丧失，从而减少病原体繁殖并限制感染。我们希望了解GBP和半胱天冬酶如何相互合作以及其他分子，以及是否可以避免宿主细胞损失造成的附带损害。我们新发现，在沙门氏菌感染期间，胱天蛋白酶和GBP之间存在分子相互作用，自然抑制炎症。在拟议的工作中，我们将把这一发现扩大到其他GBP酶和其他炎症环境。GBP通过脂质锚定在细胞内的膜中以执行其功能。我们的团队包括化学家，他们设计了新的敏感化学探针，这将有助于回答重要的问题，例如脂质何时/何地/如何锚定GBP并控制它们的行为。我们将部署先进的基于人工智能的工作流程，用于病原体的显微成像，以快速分析大量数据并提高效率。我们是一支在免疫学、发病机制、炎症和化学生物学方面拥有多年经验的科学家团队。因此，我们的建议有很高的成功机会。潜在的好处：GBP和半胱天冬酶保护免受人类病原体的主要群体。可以利用它们的有益作用来改善我们对感染的自然防御。了解是什么使它们失调将使我们能够预防有害的炎症。我们关于其调节的新发现将有可能用于旨在减少不必要的炎症和更好地应对耐药病原体的治疗。

Background: A prompt and proportionate response to an infectious agent is important for clearing infection. The immune system relies on early mechanisms of innate defence which appropriately guide late mechanisms deployed after a few days of infection. Both systems work in tandem and incorrect early responses can result in increased microbial spread in organs, inflammation, and tissue damage. A key role of the early response is to quickly identify the type of infection, for example whether bacterial, viral, or parasitic, and respond in a manner that is effective against the specific type of pathogen. Two families of enzymes play important roles during early immune defence, the Guanylate Binding Proteins (GBPs) and Caspases. GBPs are enzymes that convert the molecule GTP into GDP, and act as molecular on-off switches. Caspases are enzymes that act as molecular scissors and cut a range of important proteins that are involved in immunity. Molecular cutting by caspases is important for the normal functions of many proteins in cells. Together, GBPs and caspases act against diverse infectious agents and protect us. We previously showed that the family member GBP1 assists in early immune responses against the diarrhoeagenic bacterial pathogen Salmonella as well as the parasitic pathogen Toxoplasma gondii which causes types of brain disease. Others have showed that GBPs and caspases together assist in defending against diseases such as forms of bacterial diarrhoeas, tularemia, Legionnaire's disease, HIV, among others. This reflects the broad protective roles of these proteins and their importance in human infection. Interestingly, these pathogens invade and reside within our own cells, such as immune cells, brain cells, intestinal cells, where they grow and multiply. GBPs and caspases remove infected cells and prevent the growth and spread of pathogens. These enzymes are therefore crucial in human immune responses and their actions need to be better understood. How exactly GBPs and caspases cooperate remains poorly defined.Aims & approaches: Our overall goal is to understand the molecular and cellular mechanisms of how GBPs and caspases defend us against infection. Their combined actions detect infections by different microbes and set in motion a series of events that result in the loss of the infected host cell, which reduces pathogen multiplication and limits infection. We want to understand how GBPs and caspases cooperate with each other and other molecules and whether collateral damage through loss of host cells can be avoided. We newly discovered that there is a molecular interplay between caspases and GBPs that naturally suppresses inflammation during Salmonella infection. In the proposed work we will broaden this finding to other GBP enzymes and other inflammatory settings. GBPs are anchored by lipids into membranes inside cells to execute their function. Our team includes chemists who have designed new sensitive chemical probes that will help answer important questions such as when/where/how lipids anchors GBPs and control their actions. We will deploy our advanced artificial intelligence-based workflow for microscopic imaging of pathogens for fast analyses of a large amount of data and increased efficiency. We are a team of scientists with many years of experience in immunology, pathogenesis, inflammation, and chemical biology. Our proposal therefore has a high chance of being successful.Potential benefits: GBPs and caspases protect against major groups of human pathogens. Their beneficial actions could be harnessed to improve our natural defence against infections. Understand what deregulates them will enable us to prevent detrimental inflammation. Our new discoveries on their regulation will have the potential to be exploited in therapies aimed at reducing unwanted inflammation and for a better response against drug-resistant pathogens.