Dynamic Regulation of Epithelial Cell Survival by Enteropathogenic E. coli

性状（由申请方提供）：肠致病性大肠杆菌。大肠埃希氏菌（EPEC）是一种引起腹泻的肠道病原体，是导致显著发病率和死亡率的原因，特别是在发展中国家5岁以下儿童中。目前尚不清楚EPEC引起腹泻的确切机制。这种细菌精心设计了一种类似于病毒的III型分泌系统，将关键的毒力因子直接传递到宿主肠上皮细胞中。在感染的初始阶段，EPEC似乎特别限制了下面的上皮细胞的死亡。该提案的重点是通过EPEC和相关病原体特有的III型分泌蛋白EspZ抑制宿主细胞死亡。缺乏EspZ的菌株在动物感染模型中的定殖和疾病高度受损。我们假设EspZ与宿主蛋白相互作用以抑制受感染肠上皮细胞的过早死亡，从而在A/E病原体的肠道定植中发挥关键作用。我们建议（1）验证EspZ与宿主细胞伴侣的相互作用，定义EspZ相互作用结构域，并产生缺乏相互作用的特定EspZ突变体，（2）表征EspZ及其相互作用伴侣在激活有助于宿主细胞存活的信号传导途径中的作用，以及（3）使用动物感染模型定义EspZ及其相互作用伴侣在发病机制中的作用。了解EspZ的关键作用，以及宿主存活对发病机制的影响，可能会导致未来抑制EspZ功能的努力，从而控制EPEC相关性腹泻。

DESCRIPTION (provided by applicant): Enteropathogenic E. coli (EPEC), an intestinal pathogen that causes diarrhea, is responsible for significant morbidity and mortality, especially among children below 5 years of age in developing countries. The precise mechanism(s) by which EPEC causes diarrhea is currently not known. The bacteria elaborate a syringe-like type III secretion system that delivers key virulence factors directly into host intestinal epithelial cells. During the initial phase of infection, EPEC appears to specifically limit the death of the underlying epithelial cells. The focus of this proposal is the suppression of host cell death by the type III-secreted protein EspZ, which is unique to EPEC and related pathogens. Strains lacking EspZ are highly impaired for colonization and disease in animal models of infection. We hypothesize that EspZ interacts with host proteins to suppress premature death of infected enterocytes and, thereby, plays a key role in intestinal colonization by A/E pathogens. We propose to (1) validate the interaction of EspZ with host cell partners, define EspZ interaction domains, and generate specific EspZ mutants deficient for interaction(s), (2) characterize the role of EspZ and its interaction partners in activating signaling pathways that contribute to the survival of host cells, and (3) define the role of EspZ and its interaction partners in pathogenesis using animal models of infection. Understanding the key role of EspZ, and of host survival to pathogenesis, could lead to future efforts to inhibit EspZ function, and thereby control EPEC-associated diarrhea.