Phagocytosis and the actin cytoskeleton

The process of engulfing a foreign particle - phagocytosis - is of fundamen tal importance for a wide diversity of organisms. From simple unicellular o rganisms that use phagocytosis to obtain their next meal, to complex metazo ans in which phagocytic cells represent an essential branch of the immune s ystem, evolution has armed cells with a fantastic repertoire of molecules t hat serve to bring about this complex event. Regardless of the organism or specific molecules concerned, however, all phagocytic processes are driven by a finely controlled rearrangement of the actin cytoskeleton, A variety o f signals can converge to locally reorganise the actin cytoskeleton at a ph agosome, and there are significant similarities and differences between dif ferent organisms and between different engulfment processes within the same organism. Recent advances have demonstrated the complexity of phagocytic s ignalling, such as the involvement of phosphoinostide lipids and multicompo nent signalling complexes in transducing signals from phagocytic receptors to the cytoskeleton. Similarly, a wide diversity of 'effector molecules' ar e now implicated in actin-remodelling downstream of these receptors.