Springer Cytoskeleton and Small G Proteins: 22 (Progress in Molecular and Subcellular Biology, 22)

Animal cells present an extreme variability in their shapes in relation to their physiological properties. For instance, fibroblastic cells are tightly attached to the extra-cellular matrix and display a flattened, spindle-shaped morphology. Neuronal cells self-organize as a network through a complex branching of dendrites and a long axonal extension. Resting peripheral blood lymphocytes are poorly adhesive and maintain a spherical, smooth shape, while macroph ages produce many pseudopodal extensions involved in the recognition of foreign molecules. In addition to the variability of the morphology of the cells that constitute different organs, many cell types also modify dynamically their morphology in response to environmental changes, leading to differential cell motility, migration, adhesion, polarity or intercellular contacts. This wide plasticity of cell morphology is promoted and maintained by the cytoskeleton, which is composed of the three interconnected actin micro filaments, tubulin microtubules and intermediate filaments networks, all capable of assembly and disassembly. Over the past few years, the Rho family of Ras-like GTPases emerged as key proteins that mediate extracellular signalling pathways leading to the forma tion of polymerized actin-containing structures such as ruffles, lamellipodia and filopodia. Since the discovery of the first member RhoA in 1985, 13 mem bers have so far been characterized in human cells. Most of Rho proteins are highly conserved between species as distant as yeast, slime mold, insects and mammals, which points to their fundamental role in cellular physiology. From the Back Cover The internal structure of a cell can be affected by signals in the form of small molecules outside the cell. These changes can then alter the shape or adhesiveness of the cell. This volume centers particularly on one family of cellular proteins which transmit these signals, the Rho Ras-like GTPases, and examines their role in normal cellular processes and development. Also discussed are their roles in cancer formation and microbial pathogenesis.