Rho GTPases have diverse effects on the organization of the actin filament system.
The Rho GTPases are related to the Ras proto-oncogenes and consist of 22 family members. These proteins have important roles in regulating the organization of the actin filament system, and thereby the morphogenesis of vertebrate cells as well as their ability to migrate. In an effort to compare the effects of all members of the Rho GTPase family, active Rho GTPases were transfected into porcine aortic endothelial cells and the effects on the actin filament system were monitored. Cdc42, TCL (TC10-like), Rac1-Rac3 and RhoG induced the formation of lamellipodia, whereas Cdc42, Rac1 and Rac2 also induced the formation of thick bundles of actin filaments. In contrast, transfection with TC10 or Chp resulted in the formation of focal adhesion-like structures, whereas Wrch-1 induced long and thin filopodia. Transfection with RhoA, RhoB or RhoC induced the assembly of stress fibres, whereas Rnd1-Rnd3 resulted in the loss of stress fibres, but this effect was associated with the formation of actin- and ezrin-containing dorsal microvilli. Cells expressing RhoD and Rif had extremely long and flexible filopodia. None of the RhoBTB or Miro GTPases had any major influence on the organization of the actin filament system; instead, RhoBTB1 and RhoBTB2 were present in vesicular structures, and Miro-1 and Miro-2 were present in mitochondria. Collectively, the data obtained in this study to some extent confirm earlier observations, but also allow the identification of previously undetected roles of the different members of the Rho GTPases.
Aspenström
Pontus
P
Ludwig Institute for Cancer Research, Biomedical Center, Box 595, S-751 24 Uppsala, Sweden. pontus.aspenstrom@LICR.uu.se
Fransson
Asa
A
Saras
Jan
J
D008841:Actin Cytoskeleton / Q000648:ultrastructure*; D000818:Animals; D001665:Binding Sites; D019556:COS Cells; D002478:Cells, Cultured; D017434:Protein Structure, Tertiary; D013552:Swine; D020764:cdc42 GTP-Binding Protein / Q000502:physiology; D020744:rac GTP-Binding Proteins / Q000502:physiology; D020741:rho GTP-Binding Proteins / Q000737:chemistry / Q000145:classification / Q000502:physiology*
D020764:cdc42 GTP-Binding Protein; D020744:rac GTP-Binding Proteins; D020741:rho GTP-Binding Proteins