Raf-1 regulates Rho signaling and cell migration

J Cell Biol. 2005 Mar 14;168(6):955-64. doi: 10.1083/jcb.200409162. Epub 2005 Mar 7.

Abstract

Raf kinases relay signals inducing proliferation, differentiation, and survival. The Raf-1 isoform has been extensively studied as the upstream kinase linking Ras activation to the MEK/ERK module. Recently, however, genetic experiments have shown that Raf-1 plays an essential role in counteracting apoptosis, and that it does so independently of its ability to activate MEK. By conditional gene ablation, we now show that Raf-1 is required for normal wound healing in vivo and for the migration of keratinocytes and fibroblasts in vitro. Raf-1-deficient cells show a symmetric, contracted appearance, characterized by cortical actin bundles and by a disordered vimentin cytoskeleton. These defects are due to the hyperactivity and incorrect localization of the Rho-effector Rok-alpha to the plasma membrane. Raf-1 physically associates with Rok-alpha in wild-type (WT) cells, and reintroduction of either WT or kinase-dead Raf-1 in knockout fibroblasts rescues their defects in shape and migration. Thus, Raf-1 plays an essential, kinase-independent function as a spatial regulator of Rho downstream signaling during migration.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Animals, Newborn
  • Apoptosis
  • Blotting, Western
  • COS Cells
  • Cell Adhesion
  • Cell Movement*
  • Cell Shape
  • Cells, Cultured
  • Chlorocebus aethiops
  • Fibroblasts / metabolism
  • Gene Expression Regulation
  • Keratin-15
  • Keratin-5
  • Keratinocytes / metabolism
  • Keratins / metabolism
  • Ki-67 Antigen / metabolism
  • Mice
  • Mice, Transgenic
  • Microscopy, Confocal
  • Precipitin Tests
  • Protein Precursors / metabolism
  • Proto-Oncogene Proteins c-raf / genetics
  • Proto-Oncogene Proteins c-raf / physiology*
  • Signal Transduction*
  • Time Factors
  • Wound Healing
  • rho GTP-Binding Proteins / metabolism*

Substances

  • Keratin-15
  • Keratin-5
  • Ki-67 Antigen
  • Krt15 protein, mouse
  • Protein Precursors
  • involucrin
  • Keratins
  • Proto-Oncogene Proteins c-raf
  • rho GTP-Binding Proteins