Lysosomal Fusion and Immune Signaling

ARC syndrome is caused by mutations in the human Vps33B and VIPAS39/Vps16B proteins. Mutations in their Drosophila homologs compromise the fusion of phagosomes with lysosomes and result in reduced clearance of bacterial infections and elevated immune signaling.

ARC Syndrome Diagram
In Drosophila hemocytes, phagocytosed bacteria (green) are delivered to lysosomes and degraded, but in fob mutants, a model for ARC syndrome, the bacteria accumulate.