Trpml controls actomyosin contractility and couples migration to phagocytosis in fly macrophages

Area of Science:

• Cell Biology
• Immunology
• Molecular Biology

Background:

• Phagocytes, like macrophages, utilize their actomyosin cytoskeleton for migration and engulfing materials (phagocytosis/macropinocytosis).
• The precise mechanisms coupling cell migration and extracellular material uptake in immune cells remain largely unelucidated.

Purpose of the Study:

• To identify key molecular players involved in coupling cell locomotion and phagocytosis in Drosophila hemocytes.
• To elucidate the distinct subcellular roles of identified molecules in migration and phagocytic processing.

Main Methods:

• Utilized time-lapse imaging to observe cellular dynamics.
• Employed genetic approaches to investigate gene function in Drosophila hemocytes.

Main Results:

• Identified the lysosomal calcium channel Trpml (Transient Receptor Potential Mucolipin) as essential for coupling hemocyte migration and phagocytosis.
• Trpml regulates hemocyte migration via actomyosin contractility at the cell rear.
• Trpml functions in a myosin-independent manner near the phagocytic cup for phagocytic processing.
• Vamp7 also influences phagocytic processing and locomotion through distinct pathways.

Conclusions:

• Trpml plays dual, spatially distinct roles in regulating immune cell migration and phagocytic efficiency.
• Multiple evolutionary mechanisms likely exist to coordinate phagocytic processing with cell migration for immune surveillance.
• This study provides novel insights into the molecular basis of immune cell motility and environmental interaction.