The mechanics of vascular cell motility.

Alterations in vascular cell shape and motility occur during developmental processes and in response to injury. Similarly, during tumor vascularization and atherogenesis, endothelial and smooth muscle cells undergo motile and proliferative responses to extracellular cues. Recent inroads into our understanding of signal transduction have identified several candidate pathways by which the extracellular matrix- and growth factor-mediated stimulation of vascular cell motility may be mediated. The multiple and divergent extracellular stimuli that stimulate vascular motile responses may converge on the cytoskeleton via a family of ras-related GTPases. Biochemical analyses as well as examination of cytoskeletal dynamics in vivo indicate that actin polymerization at the forward aspects of spreading cytoplasm is capable of driving forward protrusion formation in the absence of a conventional actin motor. Actin polymerization at the plasma membrane of leading lamellae may be mediated both by de novo nucleation of actin filaments and the generation of free filament ends by uncapping the barbed ends of existing actin filaments. This review summarizes the most recent findings in extracellular-cytoskeletal-signal transduction, therein, providing a framework to explain the remarkable remodeling seen in the vasculature during developmental and disease-related processes.