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Leishmania donovani requires functional Cdc42 and Rac1 to prevent phagosomal maturation
1Division of Medical Microbiology, Department of Molecular and Clinical Medicine, Faculty of Health Sciences, Linköping University, SE-581 85 Linköping, Sweden. marle@imk.liu.se
Infection and Immunity
|April 20, 2006
Summary
Leishmania donovani uses lipophosphoglycan (LPG) to recruit Cdc42 and Rac1, forming an F-actin coat around phagosomes. This F-actin shell prevents phagosomal maturation, enabling parasite survival within macrophages.
Area of Science:
- Cell biology
- Parasitology
- Immunology
Background:
- Leishmania donovani survives in macrophages by blocking phagosome maturation.
- Lipophosphoglycan (LPG) is a key surface molecule mediating this survival mechanism.
- LPG induces F-actin accumulation around the phagosome, involving protein kinase C alpha.
Purpose of the Study:
- To investigate the role of Cdc42 and Rac1 in L. donovani phagosome F-actin coat formation.
- To elucidate the mechanism by which LPG-mediated F-actin accumulation prevents phagosomal maturation.
Main Methods:
- Macrophage cell culture.
- Analysis of F-actin accumulation around L. donovani phagosomes.
- Manipulation of Cdc42 and Rac1 activity using permanently active forms.
Main Results:
- Functional Cdc42 and Rac1 are essential for F-actin formation around L. donovani phagosomes.
- LPG-deficient L. donovani failed to induce F-actin accumulation.
- In macrophages with constitutively active Cdc42 and Rac1, LPG-defective parasites showed increased periphagosomal F-actin and impaired phagosome maturation.
Conclusions:
- L. donovani utilizes LPG to engage Cdc42 and Rac1.
- This engagement leads to the formation of a protective F-actin coat around the phagosome.
- The F-actin coat is critical for preventing phagosomal maturation and ensuring parasite survival.