Role of E3 ubiquitin ligase in Salmonella-induced inflammation

描述（由申请人提供）：沙门氏菌病继续引起世界范围的医学关注，并且仍然是人类和动物食源性疾病的头号原因。SopA被确定为SPI-1的效应物，并已被证明可易位到宿主细胞中，并在PMN跨上皮迁移和诱导肠炎中发挥关键作用。沙门氏菌和SopA诱导肠道炎症和肠炎的分子和生化机制尚不清楚。我们最近发现SopA与人类RMA1 （HsRMA1）相互作用，这是一种E3泛素连接酶。令人惊讶的是，我们还发现SopA本身是E3泛素连接酶，这表明SopA必须泛素化细菌和/或宿主细胞底物才能在沙门氏菌诱导的肠炎中发挥作用。沙门氏菌E3泛素连接酶SopA的鉴定为我们研究SopA的功能提供了独特的工具，并有助于揭示沙门氏菌和SopA诱导肠道炎症和肠炎的分子和生化机制。我的工作假设是，沙门氏菌采用了一种协调的策略，将细菌蛋白质注入宿主细胞，并通过利用宿主的泛素化途径来规划它们的破坏，以促进细菌的生存，同时减少这些细菌效应物对宿主细胞施加的长期不利影响。因此，本项目的目标是利用遗传、生化和细胞生物学方法，表征SopA及其E3泛素连接酶在沙门氏菌诱导的肠道炎症和肠炎中的活性。我们建议：1)研究沙门氏菌SopA及其E3泛素连接酶活性在趋化因子诱导和中性粒细胞迁移中的作用；2)鉴定和表征作为宿主HsRMA1和沙门氏菌SopA底物的细菌和宿主蛋白。这些研究将有助于我们了解沙门氏菌诱导肠道炎症和肠炎的分子机制。本研究的结果将有助于细胞微生物学和细胞生物学的新兴领域，特别是宿主细胞泛素化的调控。获奖将大大减少我在系里的教学和服务义务。我的研究涉及细胞生物学和微生物学的广泛范围。它需要不断更新这些项目所需的背景知识和技术。获得K02奖可以让我有更多的时间在研究上，极大地提升我的研究生涯。我的部门致力于这一领域的强大研究计划，并提供了一个很好的环境来实现我的研究目标。

DESCRIPTION (provided by applicant): Salmonellosis continues to pose worldwide medical concerns and remains the number one cause of foodborne diseases in humans and animals. SopA was identified as an SPI-1 effector and has been shown to be translocated into the host cells and to play a key role in PMN trans-epithelial migration and the induction of enteritis. The molecular and biochemical mechanisms by which Salmonella and SopA induce intestinal inflammation and enteritis are not understood. We have recently found that SopA interacts with human RMA1 (HsRMA1), an E3 ubiquitin ligase. Surprisingly, we also discovered that SopA itself is an E3 ubiquitin ligase, suggesting SopA must ubiquitinate bacterial and/or host cellular substrates to exert its function in Salmonella-induced enteritis. The identification of the Salmonella E3 ubiquitin ligase, SopA, has provided us with a unique tool to study SopA function and to help unravel the molecular and biochemical mechanisms by which Salmonella and SopA induce intestinal inflammation and enteritis. My working hypothesis is that a coordinated strategy is employed by Salmonella to inject bacterial proteins into the host cells and to program their destruction by exploiting the host ubiquitination pathways in order to facilitate bacterial survival while reducing prolonged adverse effects on the host cells exerted by these bacterial effectors. Thus, the goal of this project is to characterize SopA and its E3 ubiquitin ligase activity in Salmonella-induced intestinal inflammation and enteritis, using genetic, biochemical and cell biological approaches. We propose to: 1) examine roles of Salmonella SopA and its E3 ubiquitin ligase activity in chemokine induction and neutrophile migration; 2) identify and characterize bacterial and host proteins that are substrates for the host HsRMA1 and Salmonella SopA. These studies will help us to understand the molecular mechanism by which Salmonella induces intestinal inflammation and enteritis. Results from this study will contribute to the emerging field of cellular microbiology and to the field of cell biology, especially the regulation of ubiquitination in host cells. An award would significantly reduce my teaching and service obligations within the Department. My research involves a broad scope of both cell biology and microbiology. It requires constant update of the background knowledge and techniques needed for these projects. A K02 award will allow me to spend more time on my research and greatly enhance my research career. My department is committed to a strong research program in this area and has provided an excellent environment to carry out my research goals.