Regulation of p190 Rho-GAP by v-Src is linked to cytoskeletal disruption during transformation

V J Fincham, A Chudleigh, M C Frame

Research output: Contribution to journalArticlepeer-review

Abstract

The v-Src oncoprotein perturbs the dynamic regulation of the cellular cytoskeletal and adhesion network by a mechanism that is poorly understood. Here, we have examined in detail the effects of a temperature-dependent v-Src protein on the regulation of p190 RhoGAP, a GTPase activating protein (GAP) that has been implicated in disruption of the organised actin cytoskeleton, and addressed the dependence of v-Src-induced stress fibre loss on inhibition of Rho activity. We found that activation of v-Src induced association of tyrosine phosphorylated p190 with p120(RasGAP) and stimulation of p120(RasGAP)-associated RhoGAP activity, although p120(RasGAP) itself was not a target for phosphorylation by v-Src in chicken embryo cells. These events required the catalytic activity of v-Src and were linked to loss of actin stress fibres during morphological transformation and not mitogenic signalling. Furthermore, these effects were rapidly reversible since switching off v-Src led to dissociation of the p190/p120(RasGAP) complex, inactivation of p120(RasGAP)-associated RhoGAP activity and re-induction of actin stress fibres. In addition, transient transfection of Val14-RhoA, a constitutively active Rho protein that is insensitive to RhoGAPs, suppressed v-Src-induced stress fibre loss and cell transformation. Thus, we show here for the first time that an activated Src kinase requires the inactivation of Rho-mediated actin stress fibre assembly to induce its effects on actin disorganisation. Moreover, our work supports p190 as a strong candidate effector of v-Src-induced cytoskeletal disruption, most likely mediated by antagonism of the cellular function of Rho.
Original languageEnglish
Pages (from-to)947-56
Number of pages10
JournalJournal of Cell Science
Volume112 ( Pt 6)
Publication statusPublished - Mar 1999

Keywords

  • Actins
  • Animals
  • Cell Size
  • Cell Transformation, Neoplastic
  • Chick Embryo
  • Cytoskeleton
  • Fibroblasts
  • GTP-Binding Proteins
  • GTPase-Activating Proteins
  • Genes, src
  • Guanine Nucleotide Exchange Factors
  • Nuclear Proteins
  • Oncogene Protein pp60(v-src)
  • Phosphoproteins
  • Proteins
  • Recombinant Proteins
  • Transfection
  • rhoA GTP-Binding Protein

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