Autophagy control Salmonella infection in response to damage to the Salmonella-containing vacuole

Speaker: 賴曉菁                            Date: 15:10~16:00; May 10, 2006

Commentator: 林以行 老師                   Place: Room 601

Abstract:

Autophagy is a cellular process that mediates the degradation of long-lived proteins and unwanted organelles in the cell. The role of autophagy in bacterial infection is still unclear. Autophagy is an immediate response to Lengionella pneumophila infection and can restrict Streptococcus pyogenes replication in the cytosol. Salmonella Typhimurium is a gram-negative bacterium, which resides within a membrane-bound vacuolar structure termed Salmonella-containing vacuole (SCV). The bacterium infection induces the formation of filament structure called Sifts (Salmonella-induced filaments) in late stages of infection. To establish an intracellular niche, S. Typhimurium damaged SCV through its Salmonella pathogenecuty island(SPI)-1 encoded type three secretion systems (TTSS), which are known to damage host cell membranes. The authors demonstrate an intracellular population of  S. Typhimurium released from damaged SCV to the cytosol, which are then targeted by the autophagy system during in vitro infection. The authors known that autophagy system targets an intracellular S. Typhimirium population present within the damaged SCVs, and exposes the bacteria to the cytosol through gaps in the SCV membrane to

restrict the intracellular growth of this bacterium. All together, the authors demonstrate that S. Typhimurium induced autophagy is a rapid and localized response. The infected cells use autophagy to restrict the growth of S. Typhimurium in the cytosol and in SCVs damaged by the TTSS during infection. In summary, autophagy may play a role in innate immunity during S. Typhimurium infection. Salmonella infection is a powerful model to study the relationship between intrcellular bacteria infection and autophagy.

References:

1.          Birmingham C. L., Smith A. C., Bakowski M. A., Yoshimori T., and Brumell J. H. (2006) Autophagy controls Salmonella infection in response to damage the Salmonella-containing vacuole.J Biol Chem. 281: 11374-11383.

2.          Steel-Mortimer O., Brumell J. H., Knodler L. A., Méresse S., Lopez A., Finlay B. B. (2002) The invasion-associated type III secretion system of Salmonella enterica serovar typhimurium is necessary for intracellular proliferation and vacuole biogenesis in epithelial cells. Cell Microbiol. 4: 43-54.