CHLAMYDIAL INVASION OF NON-PHAGOCYTIC CELLS

描述（由申请人提供）：沙眼衣原体是一种革兰氏阴性专性细胞内病原体，是多种人类疾病的病原体，包括沙眼和性传播疾病衣原体。衣原体成功感染细胞包括附着、侵入、建立一个被称为包涵体的保护液泡，以及抑制溶酶体融合。随着沙眼衣原体基因组序列的出现以及新的细胞生物学和蛋白质组学工具的出现，这些过程所涉及的机制才刚刚开始揭示，提高了我们对衣原体-宿主细胞相互作用的认识。长期目标是确定衣原体感染成功建立的重要分子和生化机制。这项建议将具体处理入侵的过程。据推测，衣原体通过多种途径侵入非吞噬细胞。最近发现的一种称为Tarp的分子已被证明从感染的初级体转移到宿主质膜，进入细胞质，在那里酪氨酸被未知的宿主激酶磷酸化，并招募肌动蛋白。作为一种磷蛋白，Tarp可能作为一个信号平台，招募一些介导肌动蛋白细胞骨架重塑的适配器和效应分子。特异性目标1将解决Rac GTPase依赖途径，并专注于肌动蛋白募集的潜在下游介质。特异性目标2将重点关注Tarp蛋白，负责其磷酸化的酪氨酸激酶，结合伙伴，它们在衣原体入侵中的作用，以及Tarp与Rac GTPase的潜在关系。特异性Aim 3将探讨通过洞穴衣原体Tarp同源物募集肌动蛋白的潜在机制，该同源物不包含沙眼衣原体血清L2和d中存在的多重重复序列。这些研究不仅将揭示衣原体生物学的重要见解，还将揭示衣原体破坏肌动蛋白细胞骨架以促进其感染的细胞信号过程。

DESCRIPTION (provided by applicant): Chlamydia trachomatis is a Gram-negative obligate intracellular pathogen that is the causative agent of a wide spectrum of human diseases including trachoma and the sexually transmitted disease chlamydia. Successful infection of cells by chlamydia involves attachment, invasion, establishment of a protective vacuole called an inclusion, and inhibition of lysosomal fusion. With the advent of the C. trachomatis genome sequence and new cell biological and proteomic tools, the mechanisms involved in these processes are just beginning to be revealed, advancing our knowledge of chlamydia-host cell interactions. The long term goal is to define the molecular and biochemical mechanisms important for the successful establishment of infection by chlamydia. This proposal will specifically address the process of invasion. It is hypothesized that chlamydia uses multiple pathways of invading non-phagocytic cells. A recently identified molecule termed Tarp has been demonstrated to be translocated from the infecting elementary body across the host plasma membrane and into the cytosol where it is tyrosine phosphorylated by unknown host kinases, and recruit actin. As a phosphoprotein, Tarp may act as a signaling platform to recruit a number of adapter and effector molecules that mediate actin cytoskeletal remodeling. Specific Aim 1 will address the Rac GTPase dependent pathway and focus on the potential downstream mediators of actin recruitment. Specific Aim 2 will focus on the Tarp protein, the tyrosine kinase(s) responsible for its phosphorylation, the binding partners, their roles in chlamydial invasion, and the potential relationship of Tarp with the Rac GTPase. Specific Aim 3 will address the potential mechanism of actin recruitment by the Chlamydophila caviae Tarp homolog, which does not contain the multiple repeat sequences present in C. trachomatis serovars L2 and D. These studies would not only reveal important insights into the biology of chlamydia, but also the cellular process of signaling to the actin cytoskeleton that chlamydia subverts to facilitate its infection.