Chlamydia trachomatis is the etiologic agent of the most prevalent sexually transmitted infection (STI) in industrialized nations and the blinding condition, trachoma, in under-developed countries. There is an estimated 93 million new reported cases of Chlamydia STI annually worldwide. Trachoma affects approximately 150 million individuals, predominantly women and children. The pathologic hallmark of both diseases is the scarring the results from chronic inflammation; and inflammation at the very early stages of infection is initiated by infection of epithelial cells, and sustained by active bacterial replication and dissemination along the genital and ocular mucosae. Chlamydia is a Gram-negative obligate intracellular pathogen, which means that it requires an intracellular environment for its survival and replication. Hence, invasion of a permissive host cell is paramount to its survival and pathogenesis. In vivo, the primary target is the epithelial cells that line the ocular and genital mucosae. Our overarching hypothesis is that invasion is a Chlamydia-driven process. This pathogen has evolved mechanisms of manipulating the host cell actin cytoskeleton of to induce its uptake, leading to the formation of cell surface structures designed to engulf the bacteria. Invasion involves a number of signaling pathways that in normal cells play a role in regulating actin cytoskeleton dynamics. The bacteria turns on the machinery at its site of adherence, with the location of actin remodeling determined by the restricted translocation of a chlamydial virulence protein called TarP to the cytosolic side of the host cell plasma membrane. TarP recruits a number of signaling molecules to initiate the remodeling of the actin cytoskeleton, followed by the engulfment of the pathogen. Once inside the cell, the pathogen has the opportunity to hijack other cellular processes, including the initiation of inflammation, which when sustained leads to tissue damage and scarring of the ocular conjunctiva the genital tract resulting in infertility. Thus, the ability of Chlamydia to cause disease starts with invasion. While we have a better understanding of TarP function during invasion, mechanistic details on how it is regulated is sparse. This application will investigate the role of mechanotransduction in regulating TarP interactions with host signaling molecules. The following Specific Aims will be addressed. I) To identify the mechanism and significance of TarP mechanosensing in invasion; II) To define the myosin II-regulated components of the chlamydial invasome; and III) To determine the mechanism of uptake post-actin recruitment. The goal is to obtain a detailed understanding of TarP function and regulation in order to guide rational drug and vaccine designs to combat Chlamydia infections.

Public Health Relevance

One of the key challenges in Chlamydia research is the elucidation of essential virulence processes, such as invasion of non-phagocytic epithelial cells. A number of host cell receptors and signaling proteins have been implicated in facilitating Chlamydia invasion, which exhibited direct and indirect biochemical and functional interactions with the virulence factor TarP. This proposal will explore a novel means of regulating how TarP interacts with these host proteins using a combination of quantitative approaches, namely proteomics and live- cell imaging.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
7R01AI065545-09
Application #
10032822
Study Section
Host Interactions with Bacterial Pathogens Study Section (HIBP)
Program Officer
Vincent, Leah Rebecca
Project Start
2005-07-01
Project End
2021-12-31
Budget Start
2020-01-01
Budget End
2020-12-31
Support Year
9
Fiscal Year
2020
Total Cost
Indirect Cost
Name
University of Nebraska Medical Center
Department
Pathology
Type
Schools of Medicine
DUNS #
168559177
City
Omaha
State
NE
Country
United States
Zip Code
68198
Nogueira, Ana T; Pedrosa, Antonio T; Carabeo, Rey A (2018) Manipulation of the Host Cell Cytoskeleton by Chlamydia. Curr Top Microbiol Immunol 412:59-80
Brinkworth, Amanda J; Wildung, Mark R; Carabeo, Rey A (2018) Genomewide Transcriptional Responses of Iron-Starved Chlamydia trachomatis Reveal Prioritization of Metabolic Precursor Synthesis over Protein Translation. mSystems 3:
Nogueira, Ana T; Braun, Kristin M; Carabeo, Rey A (2017) Characterization of the Growth of Chlamydia trachomatis in In Vitro-Generated Stratified Epithelium. Front Cell Infect Microbiol 7:438
Pokorzynski, Nick D; Thompson, Christopher C; Carabeo, Rey A (2017) Ironing Out the Unconventional Mechanisms of Iron Acquisition and Gene Regulation in Chlamydia. Front Cell Infect Microbiol 7:394
Thwaites, Tristan R; Pedrosa, Antonio T; Peacock, Thomas P et al. (2015) Vinculin Interacts with the Chlamydia Effector TarP Via a Tripartite Vinculin Binding Domain to Mediate Actin Recruitment and Assembly at the Plasma Membrane. Front Cell Infect Microbiol 5:88
Thwaites, Tristan; Nogueira, Ana T; Campeotto, Ivan et al. (2014) The Chlamydia effector TarP mimics the mammalian leucine-aspartic acid motif of paxillin to subvert the focal adhesion kinase during invasion. J Biol Chem 289:30426-42
Thompson, Christopher C; Nicod, Sophie S; Malcolm, Denise S et al. (2012) Cleavage of a putative metal permease in Chlamydia trachomatis yields an iron-dependent transcriptional repressor. Proc Natl Acad Sci U S A 109:10546-51
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Brinkworth, Amanda J; Malcolm, Denise S; Pedrosa, António T et al. (2011) Chlamydia trachomatis Slc1 is a type III secretion chaperone that enhances the translocation of its invasion effector substrate TARP. Mol Microbiol 82:131-44
Carabeo, Rey (2011) Bacterial subversion of host actin dynamics at the plasma membrane. Cell Microbiol 13:1460-9

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