Redefining the role of autophagy in bacterial disease

项目总结 除了传统的抗菌药外，靶向宿主防御途径是一种有吸引力的策略，以限制 细菌感染的不良反应。其中一种受到相当大关注的途径是自噬， 一种将细胞成分隔离在双层膜小泡中的过程，随后 以溶酶体为目标进行降解和回收。自噬被认为是细胞的关键 自主防御，因为在双膜小泡中检测到许多细菌病原体 内部化。因此，以自噬为靶点的药物有可能在广泛的 细菌感染下游的疾病。然而，除了直接的杀菌机制外， 自噬具有许多底物和细胞类型特定的功能，这些功能可能有助于 感染。因此，我们选择使用两种模型病原体-沙门氏菌来重新研究体内自噬的作用 鼠伤寒沙门氏菌和金黄色葡萄球菌。我们选择调查鼠伤寒沙门氏菌是因为之前 体外研究广泛表明，这种细菌是通过自噬进行降解的。在……里面 相比之下，体外实验表明，金黄色葡萄球菌使用自噬机制进行细胞内生存。在……里面 初步数据显示，在体内抑制自噬会导致相反的结果，即 这是文献所预言的。具体地说，自噬突变体受到保护，不受鼠伤寒沙门氏菌和 对金黄色葡萄球菌敏感。这一建议的目的是阐明 自噬功能在感染这两种重要的细菌病原体时起作用。在目标1中，我们将测试一个模型 其中，鼠伤寒沙门氏菌利用自噬机制修复含有沙门氏菌的空泡(SCV)。 并躲避先天免疫传感器。在目标2中，我们将定义自噬在调节细胞中的新角色 宿主细胞的表面蛋白质组，这是限制由致孔毒素造成的损害的关键功能 由金黄色葡萄球菌生产。拟议中的实验结果将挑战现有的 自噬在抗菌防御中的作用，并指导针对自噬的药物的正确使用。

PROJECT SUMMARY In addition to traditional antimicrobials, targeting host defense pathways is an attractive strategy to limit the adverse effect of bacterial infection. One such pathway that has received considerable attention is autophagy, a process by which cellular constituents are sequestered in a double-membrane vesicle that is subsequently targeted to the lysosome for degradation and recycling. Autophagy is suggested to be critical for cell autonomous defense because many bacterial pathogens are detected within double-membrane vesicles upon internalization. Therefore, it is possible that drugs that target autophagy will be useful in a wide range of diseases downstream of bacterial infections. However, in addition to a direct microbicidal mechanism, autophagy has many substrates and cell type-specific functions that may contribute to the outcome of an infection. Thus, we chose to re-examine the role of autophagy in vivo using two model pathogens – Salmonella enterica Typhimurium and Staphylococcus aureus. We chose to investigate S. Typhimurium because previous in vitro studies extensively demonstrated that this bacterium is targeted for degradation through autophagy. In contrast, in vitro experiments indicate that S. aureus uses the autophagy machinery for intracellular survival. In preliminary data, we demonstrate that inhibiting autophagy in vivo leads to the opposite outcome that is predicted by the literature. Specifically, autophagy mutants were protected from S. Typhimurium and susceptible to S. aureus. The goal of this proposal is to elucidate the physiological mechanism by which autophagy functions during infection by these two important bacterial pathogens. In Aim 1, we will test a model in which S. Typhimurium recruits the autophagy machinery to repair the Salmonella-containing vacuole (SCV) and evade innate immune sensors. In Aim 2, we will define a novel role for autophagy in regulating the cell surface proteome of the host cells, a function that is critical in limiting damage caused by a pore-forming toxin produced by S. aureus. The results from the proposed experiments will challenge the existing paradigm on the role of autophagy in antimicrobial defense and guide the proper use of drugs that target autophagy.