Chlamydia trachomatis infection prevents front-rear polarity of migrating HeLa cells.

Chlamydiae are obligate intracellular bacterial pathogens that cause trachoma, sexually transmitted diseases and respiratory infections in humans. Fragmentation of the host cell Golgi apparatus (GA) is essential for chlamydial development, whereas the consequences for host cell functions, including cell migration are not well understood. We could show that Chlamydia trachomatis-infected cells display decelerated migration and fail to repopulate monolayer scratch wounds. Furthermore, infected cells lost the ability to reorient the fragmented GA or the microtubule organization centre (MTOC) after a migratory stimulus. Silencing of golgin-84 phenocopied this defect in the absence of the infection. Interestingly, GA stabilization via knockdown of Rab6A and Rab11A improved its reorientation in infected cells and it was fully rescued after inhibition of Golgi fragmentation with WEHD-fmk. These results show that C. trachomatis infection perturbs host cell migration on multiple levels, including the alignment of GA and MTOC.

Rab6 and Rab11 regulate Chlamydia trachomatis development and golgin-84-dependent Golgi fragmentation.

Many intracellular pathogens that replicate in special membrane bound compartments exploit cellular trafficking pathways by targeting small GTPases, including Rab proteins. Members of the Chlamydiaceae recruit a subset of Rab proteins to their inclusions, but the significance of these interactions is uncertain. Using RNA interference, we identified Rab6 and Rab11 as important regulators of Chlamydia infections. Depletion of either Rab6 or Rab11, but not the other Rab proteins tested, decreased the formation of infectious particles. We further examined the interplay between these Rab proteins and the Golgi matrix components golgin-84 and p115 with regard to Chlamydia-induced Golgi fragmentation. Silencing of the Rab proteins blocked Chlamydia-induced and golgin-84 knockdown-stimulated Golgi disruption, whereas Golgi fragmentation was unaffected in p115 depleted cells. Interestingly, p115-induced Golgi fragmentation could rescue Chlamydia propagation in Rab6 and Rab11 knockdown cells. Furthermore, transport of nutrients to Chlamydia, as monitored by BODIPY-Ceramide, was inhibited by Rab6 and Rab11 knockdown. Taken together, our results demonstrate that Rab6 and Rab11 are key regulators of Golgi stability and further support the notion that Chlamydia subverts Golgi structure to enhance its intracellular development.

Chlamydia causes fragmentation of the Golgi compartment to ensure reproduction.

The obligate intracellular bacterium Chlamydia trachomatis survives and replicates within a membrane-bound vacuole, termed the inclusion, which intercepts host exocytic pathways to obtain nutrients. Like many other intracellular pathogens, C. trachomatis has a marked requirement for host cell lipids, such as sphingolipids and cholesterol, produced in the endoplasmic reticulum and the Golgi apparatus. However, the mechanisms by which intracellular pathogens acquire host cell lipids are not well understood. In particular, no host cell protein responsible for transporting Golgi-derived lipids to the chlamydial inclusions has yet been identified. Here we show that Chlamydia infection in human epithelial cells induces Golgi fragmentation to generate Golgi ministacks surrounding the bacterial inclusion. Ministack formation is triggered by the proteolytic cleavage of the Golgi matrix protein golgin-84. Inhibition of golgin-84 truncation prevents Golgi fragmentation, causing a block in lipid acquisition and maturation of C. trachomatis. Golgi fragmentation by means of RNA-interference-mediated knockdown of distinct Golgi matrix proteins before infection enhances bacterial maturation. Our data functionally connect bacteria-induced golgin-84 cleavage, Golgi ministack formation, lipid acquisition and intracellular pathogen growth. We show that C. trachomatis subverts the structure and function of an entire host cell organelle for its own advantage.