Open AccessRas-GAP Controls Rho-Mediated Cytoskeletal Reorganization through Its SH3 Domain
Author(s) -
Véronique G. LeBlanc,
Bruno Tocqué,
Isabelle Delumeau
Publication year - 1998
Publication title -
molecular and cellular biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.14
H-Index - 327
eISSN - 1067-8824
pISSN - 0270-7306
DOI - 10.1128/mcb.18.9.5567
Subject(s) - sh3 domain , microbiology and biotechnology , biology , cytoskeleton , gtpase activating protein , actin cytoskeleton , microinjection , rac gtp binding proteins , cdc42 , actin , stress fiber , lysophosphatidic acid , xenopus , signal transduction , rac1 , proto oncogene tyrosine protein kinase src , receptor , focal adhesion , g protein , genetics , cell , gene
Proteins of the Ras superfamily, Ras, Rac, Rho, and Cdc42, control the remodelling of the cortical actin cytoskeleton following growth factor stimulation. A major regulator of Ras, Ras-GAP, contains several structural motifs, including an SH3 domain and two SH2 domains, and there is evidence that they harbor a signalling function. We have previously described a monoclonal antibody to the SH3 domain of Ras-GAP which blocks Ras signalling inXenopus oocytes. We now show that microinjection of this antibody into Swiss 3T3 cells prevents the formation of actin stress fibers stimulated by growth factors or activated Ras, but not membrane ruffling. This inhibition is bypassed by coinjection of activated Rho, suggesting that the Ras-GAP SH3 domain is necessary for endogenous Rho activation. In agreement, the antibody blocks lysophosphatidic acid-induced neurite retraction in differentiated PC12 cells. Furthermore, we demonstrate that microinjection of full-length Ras-GAP triggers stress fiber polymerization in fibroblasts in an SH3-dependent manner, strongly suggesting an effector function besides its role as a Ras downregulator. These results support the idea that Ras-GAP connects the Ras and Rho pathways and, therefore, regulates the actin cytoskeleton through a mechanism which probably does not involve p190 Rho-GAP.