ccz-1 mediates the digestion of apoptotic corpses in C. elegans.

During development, the processes of cell division, differentiation and apoptosis must be precisely coordinated in order to maintain tissue homeostasis. The nematode C. elegans is a powerful model system in which to study cell death and its control. C. elegans apoptotic cells condense and form refractile corpses under differential interference contrast (DIC) microscopy. Activation of the GTPase CED-10 (Rac) in a neighbouring cell mediates the recognition and engulfment of the cell corpse. After inclusion of the engulfed corpse in a phagosome, different proteins are sequentially recruited onto this organelle to promote its acidification and fusion with lysosomes, leading to the enzymatic degradation of the cell corpse. We show that CCZ-1, a protein conserved from yeasts to humans, mediates the digestion of these apoptotic corpses. CCZ-1 seems to act in lysosome biogenesis and phagosome maturation by recruiting the GTPase RAB-7 over the phagosome.