title: Role of p120 Ras-GAP in directed cell movement.
abstract: We have used cell lines deficient in p120 Ras GTPase activating protein (Ras-GAP) to investigate the roles of Ras-GAP and the associated p190 Rho-GAP (p190) in cell polarity and cell migration. Cell wounding assays showed that Ras-GAP-deficient cells were incapable of establishing complete cell polarity and migration into the wound. Stimulation of mutant cells with growth factor rescued defects in cell spreading, Golgi apparatus fragmentation, and polarized vesicular transport and partially rescued migration in a Ras-dependent manner. However, for directional movement, the turnover of stress fibers and focal adhesions to produce an elongate morphology was dependent on the constitutive association between Ras-GAP and p190, independent of Ras regulation. Disruption of the phosphotyrosine-mediated Ras-GAP/p190 complex by microinjecting synthetic peptides derived from p190 sequences in wild-type cells caused a suppression of actin filament reorientation and migration. From these observations we suggest that although Ras-GAP is not directly required for motility per se, it is important for cell polarization by regulating actin stress fiber and focal adhesion reorientation when complexed with 190. This observation suggests a specific function for Ras-GAP separate from Ras regulation in cell motility.
authors.affiliation: Programme in Molecular Biology and Cancer, Samuel Lunenfeld Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada, M5G 1X5.
authors.forename: S V
authors.initials: SV
authors.lastname: Kulkarni
authors.forename: G
authors.initials: G
authors.lastname: Gish
authors.forename: P
authors.initials: P
authors.lastname: van der Geer
authors.forename: M
authors.initials: M
authors.lastname: Henkemeyer
authors.forename: T
authors.initials: T
authors.lastname: Pawson
mesh_terms: D000818:Animals; D002465:Cell Movement / Q000502:physiology*; D016764:Cell Polarity / Q000502:physiology; D002478:Cells, Cultured; D003599:Cytoskeleton / Q000502:physiology / Q000648:ultrastructure; D004268:DNA-Binding Proteins; D004622:Embryo, Mammalian / Q000166:cytology; D020690:GTPase-Activating Proteins; D006056:Golgi Apparatus / Q000502:physiology* / Q000648:ultrastructure; D020662:Guanine Nucleotide Exchange Factors; D051379:Mice; D018345:Mice, Knockout; D008870:Microtubules / Q000502:physiology / Q000648:ultrastructure; D009687:Nuclear Proteins / Q000737:chemistry / Q000378:metabolism*; D010446:Peptide Fragments / Q000737:chemistry / Q000494:pharmacology; D010750:Phosphoproteins / Q000737:chemistry / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D012097:Repressor Proteins; D014162:Transfection; D015017:Yolk Sac / Q000166:cytology; D020729:p120 GTPase Activating Protein / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D020666:ras-GRF1
chemical_list: C513041:Arhgap35 protein, mouse; C513042:Arhgap5 protein, mouse; D004268:DNA-Binding Proteins; D020690:GTPase-Activating Proteins; D020662:Guanine Nucleotide Exchange Factors; D009687:Nuclear Proteins; D010446:Peptide Fragments; D010750:Phosphoproteins; C513037:Rasgrf1 protein, mouse; D011994:Recombinant Proteins; D012097:Repressor Proteins; D020729:p120 GTPase Activating Protein; D020666:ras-GRF1