CHLAMYDIAL INVASION OF NON-PHAGOCYTIC CELLS

描述(申请人提供)：沙眼衣原体是一种革兰氏阴性的细胞内专性病原体，是包括沙眼和性传播疾病衣原体在内的一系列人类疾病的病原体。衣原体对细胞的成功感染包括附着、入侵、建立称为包涵体的保护性空泡，以及抑制溶酶体融合。随着沙眼衣原体基因组序列和新的细胞生物学和蛋白质组学工具的出现，这些过程中涉及的机制才刚刚开始被揭示，从而促进了我们对衣原体与宿主细胞相互作用的了解。长期目标是确定对成功建立衣原体感染至关重要的分子和生化机制。这项提案将具体处理入侵过程。据推测，衣原体通过多种途径侵袭非吞噬细胞。最近发现的一种被称为Tarp的分子被证明从感染的基本体穿过宿主质膜进入胞浆，在胞浆中被未知的宿主激酶磷酸化的酪氨酸，并招募肌动蛋白。作为一种磷化蛋白，Tarp可以作为一个信号平台招募许多介导肌动蛋白细胞骨架重塑的适配器和效应器分子。具体目标1将解决RAC GTPase依赖的途径，并重点关注肌动蛋白招募的潜在下游中介。具体目标2将集中在Tarp蛋白，负责其磷酸化的酪氨酸激酶(S)，结合伙伴，它们在衣原体侵袭中的作用，以及Tarp与Rac GTP酶的潜在关系。具体目标3将探讨沙眼衣原体TARP同源物招募肌动蛋白的潜在机制，该同系物不包含沙眼衣原体L2和D血清型中存在的多个重复序列。这些研究不仅将揭示衣原体生物学的重要见解，而且还将揭示衣原体颠覆促进其感染的肌动蛋白细胞骨架的细胞过程。

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.