The obligate intracellular bacterium Chlamydia trachomatis is the world's leading cause of preventable blindness and the most common sexually transmitted bacterial pathogen of humans. In the US, the incidence of new cases of chlamydial genital tract infection is approximately 4 million annually, causing severe illness such as pelvic inflammatory disease leading to tubal infertility. Chlamydia replication takes place in a unique membrane bound compartment within the host cell termed the inclusion. One of the earliest steps in inclusion maturation is centripetal migration to the perinuclear region, a process that is conserved among all chlamydial species suggesting an important role in pathogenesis. This migration is chlamydial driven, as chlamydial protein synthesis is required for the recruitment of the microtubule motor protein dynein. Dynein recruitment and activation is required for chlamydial inclusion trafficking to the microtubule organizing center (MTOC) of the cell, which ultimately leads to an intimate association between the inclusion and the host centrosome. The mature chlamydial inclusion remains associated with the centrosomes causing centrosome number defects, spindle defects, and chromosome instability. We hypothesize that the recruitment and activation of dynein is a central mechanism of pathogenesis during chlamydial infection. The focus of this proposal is to identify the chlamydial proteins involved in dynein activation, and investigate the role of dynein and centrosomes in cell to cell spread and cellular transformation.
Aim 1 will identify chlamydial proteins that bind to dynein using dynein immunoprecipitation, centrosome purification and microtubule isolation techniques. Centrosomes are dynamic organelles and are actively partitioned into daughter cells during cell division, therefore Aim 2 will investigate the role of dynein and the centrosome in cell-to-cell spread of Chlamydia under persistent and non-persistent growth conditions. Centrosome function is crucial in the maintenance of chromosome fidelity. The unique chlamydial driven interaction between dynein and the inclusion is likely an important factor in the link between chlamydial infection and cervical cancer.
Aim 3 will determine the mechanism of chlamydial induced centrosome defects and evaluate these defects in cellular transformation. Additionally, the link between cervical cancer and Chlamydia likely involves an interaction with human papilloma virus (HPV) infection. We will therefore assess the role of the interaction between chlamydial induced centrosome defects and expression of the high risk HPV16 E6 and E7 oncogenes on cellular transformation.
The bacteria Chlamydia infects an estimated 4 million people annually in the United States. Infection with this organism leads to pelvic inflammatory disease, infertility in women and raises the chance of cervical cancer development. Determining the mechanisms of chlamydial intracellular development and its impact on host cell replication machinery will lead to advances in understanding chlamydial disease and offer potential novel therapeutic targets.
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