Pseudomonas aeruginosa-induced host cell pathogenesis

描述(申请人提供)：铜绿假单胞菌(PA)是一种机会性的革兰氏阴性病原体，导致大量的医院感染。Joanne Engel博士和她的团队已经证明，PA103通过III型分泌系统(TTSS)依赖的机制诱导上皮细胞和巨噬细胞凋亡样细胞死亡。与其他人的结果一致，他们发现这是一个依赖于Fas配体和Fas受体的过程。我们认为，PA诱导的细胞凋亡要么是通过TTSS将细菌效应物直接移位到宿主细胞内，导致Fas依赖的细胞凋亡激活，要么是通过III型转位装置本身的一个或多个组件直接诱导Fas依赖的细胞凋亡。我们将确定PAl03在真核细胞中诱导TTS依赖的类凋亡细胞死亡的机制。我们将首先使用遗传学和蛋白质组学的方法来鉴定一个假定的诱导凋亡的III型分泌效应分子。我们也可以检验另一种假设，即TTSS本身负责PA诱导的细胞凋亡。我们将在一株缺乏编码TTSS的耶尔森氏菌中表达PA TTSS，并检测其恢复诱导细胞凋亡的活性。

DESCRIPTION (provided by applicant): Pseudomonas aeruginosa (PA) is an opportunistic gram-negative pathogen responsible for a large number of nosocomial infections. Dr. Joanne Engel and her group have shown that PA103 induces apoptotic-like cell death in epithelial cells and macrophages by a Type III Secretion System (TTSS)-dependent mechanism. Consistent with the results of others, They have found this to be a Fas ligand- and Fas receptor-dependent process. We propose that PA-induced apoptosis occurs either by (A) direct translocation of a bacterial effector into the host cell (PAF, for Pseudomonas Apoptosis Factor) by the TTSS, resulting in activation of Fas-dependent apoptosis or by (B) direct induction of Fas-dependent apoptosis by one or more components of the type III translocation apparatus itself. We will identify the mechanism by which PAl03 induces TTS-dependent apoptotic-like cell death in eukaryotic cells. We will initially use genetic and proteomic approaches to identify a putative apoptosis-inducing type III secreted effector molecule. We may also test the alternative hypothesis that the TTSS itself is responsible for the induction of apoptosis by PA. We will express the PA TTSS in a Yersinia strain that lacks the plasmid encoded TTSS and test for restoration of apoptosis-inducing activity.