STAT3 and its Acetylation in Acute Lung Injury

描述(由申请人提供)：急性肺损伤(ALI)及其发展为成人呼吸窘迫综合征(ARDS)仍然是危重患者发病率和死亡率的主要因素。尽管涉及细胞因子-转录因子网络的不断扩大的知识为急性肺炎性反应提供了新的见解，但阐明这些炎症相关转录因子在肺中的功能仍然是一个艰巨的挑战。作为一种转录因子，STAT3参与了许多细胞因子的信号通路，这些细胞因子受细胞因子信号转导抑制物(SOCS)家族的调节，包括SOCS3。虽然STAT3在肺组织中表达于不同类型的细胞，但对STAT3的功能作用及其调节急性肺炎性反应的分子机制知之甚少。此外，对于STAT3在肺中的激活是如何调节的，目前还没有明确的了解。我们的初步数据表明，STAT3可以参与肺部炎症结果，并且似乎在免疫复合物和脂多糖肺损伤模型和肺泡巨噬细胞中发挥双重作用。本研究的假说是STAT3可能通过激活多个靶基因在体内发挥其在ALI中的调节作用，从而对Fc3R和TLR4介导的肺部炎症反应进行差异性调节。因此，本研究旨在阐明STAT3和SOCS3信号在肺内免疫复合物或内毒素沉积后ALI中的作用及其分子机制。在第一个目标中，我们将寻求体内siRNA介导的STAT3抑制增强ALI免疫复合物模型中的损伤和减轻ALI模型中的内毒素损伤的初步信息，并确定促炎和抗炎介质的测量是否与ALI的结果相关。在第二个目标中，我们将定义STAT3乙酰化以及乙酰化调节肺泡巨噬细胞中STAT3活性和肺损伤的分子机制。在第三个目标中，我们将确定SOCS3调节免疫复合物诱导和内毒素诱导的肺泡巨噬细胞中STAT3激活和炎症反应的机制。将进行蛋白质组学分析以确定SOCS3相互作用的蛋白质。我们的研究结果有望提供有关肺部炎症级联反应的重要信息，以及STAT3和SOCS3在肺部炎症反应中的调节作用。这一知识将代表一种新的范式，用于开发治疗ALI的新治疗靶点。项目简介：这个拟议的项目将调查STAT3是否与免疫复合体和脓毒症相关的急性肺损伤有关。该项目还将确定翻译后机制，如蛋白质乙酰化和蛋白质-蛋白质相互作用是否有助于急性肺损伤中STAT3的活性。这些研究将是确定治疗急性肺损伤的新治疗靶点的关键。

DESCRIPTION (provided by applicant): Acute lung injury (ALI) and its progression to adult respiratory distress syndrome (ARDS) remain leading factors of morbidity and mortality in critically ill patients. Although the expanding knowledge involving the cytokine-transcription factor network has provided new insights into the acute lung inflammatory responses, elucidation of the function of these inflammation-related transcription factors in the lung is still a daunting challenge. Functioning as a transcription factor, STAT3 participates in the signaling pathways for many cytokines that are regulated by the suppressor of cytokine signaling (SOCS) family, including SOCS3. While STAT3 is expressed in various cell types in lung, little is known about the function role of STAT3 and the molecular mechanism exerted by STAT3 to regulate acute lung inflammatory responses. Furthermore, there is no clear understanding of exactly how STAT3 activation is regulated in the lung. Our preliminary data indicate that STAT3 can participate in lung inflammatory outcomes and seems to play a dual role in both IgG immune complex and LPS lung injury models and alveolar macrophages. The hypothesis of this study is that STAT3 may exert its regulatory function in vivo during ALI by activating multiple target genes, which then differentially regulate Fc3R-mediated and TLR4-mediated inflammatory responses in the lung. Therefore, this study is designed to elucidate the roles of STAT3 and SOCS3 signaling in ALI occurring after intrapulmonary deposition of IgG immune complex or LPS, and the underlying molecular mechanisms. In the first aim, we will pursue preliminary information that siRNA-mediated suppression of STAT3 in vivo intensifies injury in IgG immune complex model of ALI and attenuates injury in the LPS model of ALI and determine if measurements of the pro- and anti-inflammatory mediators correlate with ALI outcomes. In the second aim, we will define STAT3 acetylation and molecular mechanisms by which acetylation regulates STAT3 activity in alveolar macrophages and lung injury. In the third aim, we will determine the mechanisms by which SOCS3 regulates IgG immune complex-induced and LPS-induced STAT3 activation and inflammatory response in alveolar macrophage. Proteomic analysis will be performed to identify SOCS3 interacting proteins. The results of our studies are expected to provide important information on inflammatory cascades in the lung and the regulatory roles of STAT3 and SOCS3 in the lung inflammatory response. This knowledge will represent a new paradigm for approaching the development of new therapeutic targets for treatment of ALI. PROJECT NARRATIVE: This proposed project will investigate whether STAT3 contributes to immune complex and sepsis-related acute lung injury. This project will also define if post-translational mechanisms such as protein acetylation and protein-protein interaction contribute to STAT3 activity in acute lung injury. These studies will be essential to identify novel therapeutic targets for treatment of acute lung injury.