Akt/AS160 Signaling Pathway Inhibition Impairs Infection by Decreasing Rab14-Controlled Sphingolipids Delivery to Chlamydial Inclusions

Abstract

Chlamydia trachomatis , an obligate intracellular bacterium, intercepts different trafficking pathways of the host cell to acquire essential lipids for its survival and replication, particularly from the Golgi apparatus via a Rab14-mediated transport. Molecular mechanisms underlying how these bacteria manipulate intracellular transport are a matter of intense study. Here, we show that C. trachomatis utilizes Akt/AS160 signaling pathway to promote sphingolipids delivery to the chlamydial inclusion through Rab14-controlled vesicular transport. C. trachomatis provokes Akt phosphorylation along its entire developmental life cycle and recruits phosphorylated Akt (pAkt) to the inclusion membrane. As a consequence, Akt Substrate of 160 kDa (AS160), also known as TBC1D4, a GTPase Activating Protein (GAP) for Rab14, is phosphorylated and therefore inactivated. Phosphorylated AS160 (pAS160) loses its ability to promote GTP hydrolysis, favoring Rab14 binding to GTP. Akt inhibition by an allosteric isoform-specific Akt inhibitor (iAkt) prevents AS160 phosphorylation and reduces Rab14 recruitment to chlamydial inclusions. iAkt further impairs sphingolipids acquisition by C. trachomatis- inclusion and provokes lipid retention at the Golgi apparatus. Consequently, treatment with iAkt decreases chlamydial inclusion size, bacterial multiplication, and infectivity in a dose-dependent manner. Similar results were found in AS160-depleted cells. By electron microscopy, we observed that iAkt generates abnormal bacterial forms as those reported after sphingolipids deprivation or Rab14 silencing. Taken together, our findings indicate that targeting the Akt/AS160/Rab14 axis could constitute a novel strategy to limit chlamydial infections, mainly for those caused by antibiotic-resistant bacteria.

c-Myc plays a key role in IFN-γ induced persistence ofChlamydia trachomatis

“…4c). Both the MAPK and PI3K pathways activated during infection are critical for chlamydial development 59–62 . Therefore, the phosphorylation status of AKT and GSK3ß was examined in HeLa 229 and human Fimb cells, which were treated with IFN-γ and/or Trp and infected with Chlamydia .…”

Hijacking and Use of Host Kinases by Chlamydiae

“…SFKs at microdomains regulate inclusion trafficking along microtubules to the microtubule organization center (MTOC) and hence may hijack the vesicular transport along microtubules. A recent study found C. trachomatis utilizes the Akt/AS160 signaling pathway to acquire sphingolipids via Rab14 mediated vesicular transport [ 41 ]. Akt remains phosphorylated and recruited to the inclusion membrane for the duration of infection and is essential for chlamydial replication, inclusion size, and infectivity [ 41 ].…”

Diverse Facets of Sphingolipid Involvement in Bacterial Infections

“…Chlamydia directly obtain ceramide from the host cell Golgi and incorporate it into the inclusion membrane (Hackstadt et al, 1995; Figure 2). This is a process essential for the pathogen survival, in which chlamydial inclusion fuses with trans- Golgi network-derived secretory vesicles (van Ooij et al, 2000) in an Akt and Rab14-mediated way (Capmany and Damiani, 2010; Capmany et al, 2019). C. trachomatis has also been reported to cause the fragmentation of Golgi and to induce formation of mini stacks in the vicinity of the inclusion membrane, which supports lipid acquisition from the host (Heuer et al, 2009).…”