Regulation of actin cytoskeleton by Rho-family GTPases and their associated proteins

Abstract

Cdc42, Rac and Rho GTPase each regulates distinct morphological changes in response to specific growth factors. These changes which involve actin-containing cytoskeletal structures may underlie aspects of growth and development. Proteins binding to the active GTP-bound form of the GTPase including the Cdc42/ Rac activated PAK, and the Rho associated kinase ROK can act as morphological effectors as can the RacGAP chimaerin. In fibroblasts and neuronal-type cells, the growth factors evoke morphological changes by activating individual GTPase pathways or Rac-Rho and Cdc42-Rac hierarchical pathways. There is also evidence for Cdc42-Rho antagonism. The morphological outcome will depend on the level of activation of the different GT Pases by their stimulatory growth factor.