Cell locomotion is characterized by a rearward flow of structures at the cell surface and in the cytoplasm. The objective of the proposal is to test two current models of the mechanism of metazoan cell locomotion that explain this rearward movement: Membrane flow, and Cortical actin flow. Fibroblasts will be surface labelled with antibodies to membrane proteins and microinjected with fluorescent actin. The redistribution of these probes during cell locomotion will be monitored using digital video fluorescence microscopy, photobleaching, and electron microscopy. The mobility of the membrane probes with respect to actin assemblies in lamellipodia, arcs and stress fibers will provide a critical test of the two models. By microinjecting cells with actin-binding proteins the existence of a forward flow of actin through the cytoplasm will be tested. The elucidation of the mechanism of cell movement will be of fundamental importance to our understanding of the role of cell migrations in embryonic morphogenesis, in the inflammatory response, in wound healing, and other physiological process.
