STAT3-dependent manipulation of host transcription and immune responses by Salmonella

项目摘要/摘要 背景：在全球范围内，细胞内细菌病原体的非伤寒血清 2010年，肠道沙门氏菌导致1.53亿例胃肠炎和5.7万人死亡。S. 肠系膜，肠系膜鼠伤寒杆菌是最流行的非伤寒沙门氏菌(NTS)血清型， 通过注入颠覆宿主的效应蛋白，在宿主细胞空泡内创建持久的利基 信号转导通路。最近，鼠伤寒沙门氏菌被证明可以促进其 通过激活宿主转录因子STAT3在细胞内存活和复制。而当 已知STAT3可促进细胞分化、存活和增殖，以响应细胞因子 和生长因子，目前还不清楚沙门氏菌是如何推动STAT3磷酸化的，或者STAT3是如何 使宿主细胞对鼠伤寒沙门氏菌更加宽容。 目标/初步数据：我的目标是了解STAT3的机制和功能 沙门氏菌感染过程中的磷酸化。最近，我们实验室发现一株鼠伤寒沙门氏菌 效应子SARA与STAT3物理结合并诱导STAT3磷酸化。然而， Sara缺乏与任何已知的激酶结构域的可识别的结构同源性，所以我假设 SARA启动一条信号通路，使STAT3磷酸化。进一步，鼠伤寒沙门氏菌∆Sara 在人类细胞和受感染的小鼠中显示出减少的细胞内复制。这种对Sara的依赖 在野生型感染期间，通过击倒或抑制宿主STAT3来概括还原， 这表明SARA通过激活STAT3来提高毒力。因此，我假设STAT3- 靶标促进含有沙门氏菌的空泡(SCV)中的细菌复制。 方法：我将确定蛋白质组学确定的SARA相互作用伙伴如何与 磷酸化的SARA基序驱动STAT3酪氨酸磷酸化。同时，我会核实 潜在的SARA到STAT3信号组件或调节器，通过共同的 与STAT3靶激活水平相关的人类遗传变异。最后，我会 确定激活的STAT3如何通过以下方式促进鼠伤寒沙门氏菌的细胞内复制 通过转录组学分析确定SARA依赖的转录变化， 促进细胞内细菌复制。 意义：揭示鼠伤寒沙门氏菌如何激活STAT3来操纵宿主转录 而改善其胞内生态位将增强我们对细菌-宿主相互作用的理解 STAT3途径的功能，在自身免疫和肿瘤发生中起关键作用。

Project Summary/Abstract Background: Across the globe, non-typhoidal serovars of the intracellular bacterial pathogen Salmonella enterica caused 153 million cases of gastroenteritis and 57,000 deaths in 2010. S. enterica enterica ser. Typhimurium, the most prevalent non-typhoidal Salmonella (NTS) serovar, creates a durable niche inside host cell vacuoles by injecting effector proteins that subvert host signal transduction pathways. Recently, S. Typhimurium has been shown to promote its intracellular survival and replication by activating the host transcription factor STAT3. While STAT3 is known to promote cell differentiation, survival, and proliferation in response to cytokines and growth factors, it is unknown how Salmonella drives STAT3 phosphorylation or how STAT3 renders host cells more permissive to S. Typhimurium. Goal/Preliminary Data: I aim to understand the mechanism and function of STAT3 phosphorylation during Salmonella infection. Recently, our lab discovered that an S. Typhimurium effector, SarA, physically associates with STAT3 and induces STAT3 phosphorylation. However, SarA lacks identifiable structural homology to any known kinase domain, so I hypothesize that SarA initiates a signaling pathway to phosphorylate STAT3. Further, S. Typhimurium ∆sarA exhibits reduced intracellular replication in human cells and infected mice. This SarA-dependent reduction is recapitulated by knockdown or inhibition of host STAT3 during wild-type infection, indicating that SarA promotes virulence by activating STAT3. Hence, I hypothesize that STAT3- targets promote bacterial replication in the Salmonella-containing vacuole (SCV). Approach: I will determine how SarA-interacting partners, identified by proteomics, interact with phosphorylated SarA motifs to drive STAT3 tyrosine phosphorylation. In parallel, I will verify potential SarA to STAT3 signaling components or regulators that were identified through common human genetic variants associated with the level of STAT3-target activation. Finally, I will determine how activated STAT3 promotes S. Typhimurium intracellular replication, by ascertaining how SarA-dependent transcriptional changes, identified by transcriptomics analysis, promote intracellular bacterial replication. Significance: Uncovering how S. Typhimurium activates STAT3 to manipulate host transcription and improve its intracellular niche will enhance our understanding of bacteria-host interaction and the function of the STAT3 pathway, a crucial player in autoimmunity and oncogenesis.