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Cytoplasmic bacteria can be targets for autophagy
Kathryn A Rich1, Chelsea Burkett, Paul Webster
1Ahmanson Advanced Electron Microscopy and Imaging Center, House Ear Institute, and Department of Pathology, Keck School of Medicine, USC, Los Angeles, CA, USA.
Cellular Microbiology
|June 20, 2003
Summary
Listeria monocytogenes, an intracellular pathogen, can be targeted by autophagy, a cellular degradation process. This study reveals autophagy
Area of Science:
- Cell Biology
- Immunology
- Microbiology
Background:
- Autophagy is a fundamental cellular process for degrading damaged components and maintaining homeostasis.
- Intracellular pathogens like Listeria monocytogenes can evade host defenses by residing within cells.
Purpose of the Study:
- To investigate whether autophagy can target and eliminate intracellular Listeria monocytogenes.
- To elucidate the mechanism by which Listeria monocytogenes is sequestered and degraded by autophagy.
Main Methods:
- Infection of macrophages with Listeria monocytogenes.
- Treatment with chloramphenicol to arrest bacterial metabolism.
- Immunofluorescence microscopy to identify autophagic vacuoles and their origin.
- Inhibition of autophagy using specific chemical inhibitors (3-methyladenine, wortmannin).
- Assessment of autophagosome-lysosome fusion.
Main Results:
- Metabolically arrested Listeria monocytogenes in the cytoplasm are internalized into double-membraned autophagic vacuoles.
- These autophagic vacuoles originate from the rough endoplasmic reticulum.
- The internalization process is inhibited by autophagy inhibitors and enhanced under starvation conditions.
- The autophagic vacuoles containing bacteria fuse with the endocytic pathway for degradation.
Conclusions:
- Autophagy serves as a host defense mechanism against intracellular Listeria monocytogenes.
- Targeting cytoplasmic bacteria with autophagy facilitates their removal and degradation.
- This pathway represents a novel host strategy for combating bacterial infections.