title: RhoA inactivation by p190RhoGAP regulates cell spreading and migration by promoting membrane protrusion and polarity.
abstract: The binding of extracellular matrix proteins to integrins triggers rearrangements in the actin cytoskeleton by regulating the Rho family of small GTPases. The signaling events that mediate changes in the activity of Rho proteins in response to the extracellular matrix remain largely unknown. We have demonstrated in previous studies that integrin signaling transiently suppresses RhoA activity through stimulation of p190RhoGAP. Here, we investigated the biological significance of adhesion-dependent RhoA inactivation by manipulating p190RhoGAP signaling in Rat1 fibroblasts. The inhibition of RhoA activity that is induced transiently by adhesion was antagonized by expression of dominant negative p190RhoGAP. This resulted in impaired cell spreading on a fibronectin substrate, reduced cell protrusion, and premature assembly of stress fibers. Conversely, overexpression of p190RhoGAP augmented cell spreading. Dominant negative p190RhoGAP elevated RhoA activity in cells on fibronectin and inhibited migration, whereas overexpression of the wild-type GAP decreased RhoA activity, promoted the formation of membrane protrusions, and enhanced motility. Cells expressing dominant negative p190RhoGAP, but not control cells or cells overexpressing the wild-type GAP, were unable to establish polarity in the direction of migration. Taken together, these data demonstrate that integrin-triggered RhoA inhibition by p190RhoGAP enhances spreading and migration by regulating cell protrusion and polarity.
authors.affiliation: Department of Cell and Developmental Biology, Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599, USA. warthur@med.unc.edu
authors.forename: W T
authors.initials: WT
authors.lastname: Arthur
authors.forename: K
authors.initials: K
authors.lastname: Burridge
mesh_terms: D000199:Actins / Q000378:metabolism; D000818:Animals; D002448:Cell Adhesion; D002462:Cell Membrane / Q000378:metabolism*; D002465:Cell Movement; D016764:Cell Polarity; D048429:Cell Size; D022081:Cell Surface Extensions / Q000378:metabolism*; D003599:Cytoskeleton / Q000378:metabolism; D004268:DNA-Binding Proteins; D005347:Fibroblasts; D020662:Guanine Nucleotide Exchange Factors / Q000378:metabolism*; D008856:Microscopy, Fluorescence; D008954:Models, Biological; D009687:Nuclear Proteins / Q000378:metabolism*; D051381:Rats; D012097:Repressor Proteins; D020742:rhoA GTP-Binding Protein / Q000037:antagonists & inhibitors* / Q000378:metabolism
chemical_list: D000199:Actins; C513040:Arhgap35 protein, rat; D004268:DNA-Binding Proteins; D020662:Guanine Nucleotide Exchange Factors; D009687:Nuclear Proteins; D012097:Repressor Proteins; D020742:rhoA GTP-Binding Protein