Phagocytosis of apoptotic cells in mammals, caenorhabditis elegans and Drosophila melanogaster: molecular mechanisms and physiological consequences.

Phagocytosis is the necessary corollary of apoptosis. It leads to the clearance of apoptotic cells by phagocytes, which can be 'professional' or 'amateur'. I review the known molecular aspects of phagocytosis of apoptotic corpses in mammals, Caenorhabditis elegans and Drosophila melanogaster from the point of view of the phagocyte and the apoptotic corpse. I highlight recent advances made in the field and discuss the physiological outcomes and consequences of this process. Indeed, phagocytosis of apoptotic cells is important in shaping or remodeling tissues to maintain their integrity and specialized functions during development and wound healing. It also contributes to the development of inflammation and/or its resolution after an injury or infection. This perhaps explains why the molecular mechanisms of phagocytosis of apoptotic cells are redundant and complex in mammals and suggests why they appear to have been mostly conserved through evolution. Caenorhabditis elegans has already proven to be useful in genetically dissecting the molecular mechanisms underlying phagocytosis of apoptotic corpses by 'amateur' neighboring cells. Drosophila melanogaster will become the model of choice in genetically dissecting the molecular mechanisms underlying phagocytosis of apoptotic cells by 'professional' phagocytes such as macrophages.