Functional consequences of dynamic MAPK signalling on the host defence response of vertebrates to bacterial infections

在我们的世界中，生物体不断地相互作用。这些相互作用的结果是多种多样的，并表现为不同的模式，如捕食、共生、共居或寄生。我对了解决定宿主对病原体反应的分子机制特别感兴趣。宿主防御细菌和真菌感染的一个关键因素是将中性粒细胞募集到感染部位。因此，正确调节中性粒细胞炎症对于宿主至关重要。一旦感知到病原体，就会发出求救信号，导致中性粒细胞的募集。最近，我们发现了上皮细胞中的三个关键信号传导途径，这是抵御感染的第一道防线，导致中性粒细胞响应革兰氏阴性细菌而募集。这三个途径是：TAK1-MKK3-p38a、TAK1-IKKß-NF?B 和 TAK1-IKKß-TPL2-MKK1-ERK2。这些途径共同协调炎症介质的合成。 ***尽管我们在识别对细菌感染炎症调节至关重要的关键信号方面取得了良好进展，但我们仍然缺少许多有助于更好地理解这一重要生物反应的细节。目前的大多数方法（包括我们的方法）都使用准时探测来测量信号强度，从而在获取的信息中留下了重要的空白。该资助旨在开发工具来克服这一限制，以便更全面地了解人类上皮细胞感染引发的炎症调节。将实现两个目标：***目标 1：开发动态成像炎症的工具。为了动态评估 TLR-TAK1 介导的 MKK3-p38a、IKKß-NF?B 和 IKKß-TPL2-MKK1-ERK2 途径的激活，我们将使用以下技术：双分子荧光互补 (BiFC)、生物发光共振能量转移 (BRET)、福斯特共振能量转移 (FRET) 和荧光素酶转录报告基因。生成的工具将用于第二个目标，以探讨信号转导调节炎症的基本机制。***目标 2：揭示宿主与病原体相互作用期间的炎症反应。在第二个目标中，我们将对培养物中的人类上皮细胞感染期间发生的炎症进行实时成像。感染后，我们将动态测量细胞内信号通路和相关转录因子的激活。与此同时，我们将使用经典方法测量细胞因子的产生和中性粒细胞的募集，以评估炎症的严重程度。 ***总而言之，这些研究应该更清楚地描绘出炎症调节的基本分子机制。 ******

In our world, living organisms constantly interact with each other. The outcome of these interactions is diverse and represented by different modes like predation, symbiosis, co-habitation or parasitism. I am particularly interested in understanding the molecular mechanisms determining the host response to pathogens. A key element of host defense against bacterial and fungal infections is the recruitment of neutrophils to site of infections. Therefore it is vitally important for the host to properly regulate neutrophilic inflammation. Upon sensing of pathogens, distress signals are emitted leading to the recruitment of neutrophils. Recently we have identified three key signaling pathways in epithelial cells, the first line of defense against infections that lead to neutrophil recruitment in response to gram-negative bacteria. The three pathways are: TAK1-MKK3-p38a, TAK1-IKKß-NF?B and TAK1-IKKß-TPL2-MKK1-ERK2. Together, these pathways coordinate the synthesis of inflammatory mediators. ***Although we have made good progress in identifying key signals important for the regulation of inflammation in response to bacterial infection, we are still missing a lot of the details that would contribute to a much better understanding of this important biological response. The majority of current approaches, including ours, use punctual probing to measure signal intensities, leaving important gaps in the information acquired. This grant aims to develop tools to overcome this limitation in order to get a more complete understanding of the regulation of inflammation triggered by infection of human epithelial cells. Two objectives will be undertaken:***Objective 1: Developing tools to dynamically image inflammation. To dynamically assess TLR-TAK1-mediated activation of the MKK3-p38a, IKKß-NF?B and IKKß-TPL2-MKK1-ERK2 pathways, we will be using the following technologies: Bimolecular fluorescence complementation (BiFC), Bioluminescence Resonance Energy Transfer (BRET), Forster Resonance energy transfer (FRET) and luciferase transcriptional reporters. The tools generated will be used in the second objective to probe fundamental mechanisms of signal transduction regulating inflammation.***Objective 2: Shedding light on the inflammatory response during host-pathogen interactions. In this second objective, we will image inflammation in real-time occurring during infection of human epithelial cells in culture. Following infection, we will measure dynamically the activation of intracellular signaling pathways and associated transcription factors. In parallel, using classical approaches we will measure the production of cytokines and neutrophil recruitment to evaluate the magnitude of inflammation. ***Taken together, these studies should paint a much clearer picture of the fundamental molecular mechanisms underlying the regulation of inflammation. ********