A Drosophila model to image phagosome maturation

Area of Science:

• Cell Biology
• Immunology
• Genetics

Background:

• Phagocytosis is crucial for pathogen degradation, involving phagosome maturation through fusion with endosomes and lysosomes.
• The in vivo study of phagosome maturation has been limited.
• Drosophila hemocytes offer a model system analogous to mammalian macrophages.

Purpose of the Study:

• To establish and validate a Drosophila model for studying phagosome maturation in vivo.
• To analyze the sequential fusion of endosomes and lysosomes with phagosomes during bacterial clearance.
• To utilize the model for genetic analysis of phagosome maturation defects.

Main Methods:

• Utilized transgenic Drosophila expressing Rab7-GFP (endosome) and Lamp1-GFP (lysosome) markers.
• Injected adult female Drosophila with E. coli DH5α and collected hemocytes at timed intervals.
• Employed two-photon imaging for in vivo observation of hemocyte phagosome dynamics.
• Analyzed phagosome maturation in wild-type and 14-3-3e mutant Drosophila.

Main Results:

• Observed E. coli within enlarged Rab7-GFP positive phagosomes (15-45 min) and Lamp1-GFP positive phagolysosomes (45 min) in wild-type flies.
• In vivo imaging confirmed vesicle enlargement and fusion dynamics consistent with phagosome maturation.
• Demonstrated altered phagosome maturation, including delayed bacterial uptake and trafficking, in 14-3-3e mutants.

Conclusions:

• Drosophila hemocytes provide a robust and genetically tractable model for studying phagosome maturation.
• The model accurately recapitulates key aspects of phagosome maturation observed in mammalian systems.
• This Drosophila model is suitable for both in vivo and ex vivo analyses of phagosome maturation and related genetic factors.