The CCC complex directs phagosomal maturation and bactericidal activity in macrophages through PI(3)P regulation

Area of Science:

• Immunology
• Cell Biology
• Molecular Biology

Background:

• Phagocytosis is vital for host defense, involving immune cells engulfing pathogens.
• Phagosome maturation requires protein recruitment and phosphoinositide regulation for pathogen degradation.
• The COMMD/CCDC22/CCDC93 (CCC) complex is known for endosomal recycling but its role in phagocytosis was unclear.

Purpose of the Study:

• To investigate the role of the CCC complex in phagosome maturation and innate immune defense.
• To determine how the CCC complex influences bacterial clearance by macrophages.

Main Methods:

• Utilized bone marrow-derived macrophages (BMDMs) to study phagocytosis.
• Assessed bacterial clearance and phagosomal protein composition.
• Analyzed phagosome-lysosome fusion and phosphoinositide dynamics.

Main Results:

• The CCC complex is essential for efficient bacterial clearance by BMDMs.
• The CCC complex regulates the temporal remodeling of phagosomal protein composition.
• Deficiency in the CCC complex leads to impaired phagosome-lysosome fusion and excessive phosphatidylinositol-3-phosphate (PI(3)P) accumulation.

Conclusions:

• The CCC complex plays a critical, previously unrecognized role in innate immune defense.
• The CCC complex is necessary for proper phagosome maturation and function.
• Dysregulation of the CCC complex impairs macrophage ability to clear pathogens.