Regulation of anchorage-dependent signal transduction by protein kinase A and p21-activated kinase

Nat Cell Biol. 2000 Sep;2(9):593-600. doi: 10.1038/35023536.

Abstract

Activation of the canonical mitogen-activated protein kinase (MAPK) cascade by soluble mitogens is blocked in non-adherent cells. It is also blocked in cells in which the cAMP-dependent protein kinase (PKA) is activated. Here we show that inhibition of PKA allows anchorage-independent stimulation of the MAPK cascade by growth factors. This effect is transient, and its duration correlates with sustained tyrosine phosphorylation of paxillin and focal-adhesion kinase (FAK) in non-adherent cells. The effect is sensitive to cytochalasin D, implicating the actin cytoskeleton as an important factor in mediating this anchorage-independent signalling. Interestingly, constitutively active p21-activated kinase (PAK) also allows anchorage-independent MAPK signalling. Furthermore, PKA negatively regulates PAK in vivo, and whereas the induction of anchorage-independent signaling resulting from PKA suppression is blocked by dominant negative PAK, it is markedly prolonged by constitutively active PAK. These observations indicate that PKA and PAK are important regulators of anchorage-dependent signal transduction.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • 3T3 Cells
  • Animals
  • Cell Adhesion*
  • Cyclic AMP-Dependent Protein Kinases / genetics
  • Cyclic AMP-Dependent Protein Kinases / metabolism*
  • Cytochalasin D / pharmacology
  • Cytoskeletal Proteins / metabolism
  • Enzyme Activation
  • Focal Adhesion Kinase 1
  • Focal Adhesion Protein-Tyrosine Kinases
  • MAP Kinase Signaling System*
  • Mice
  • Mitogen-Activated Protein Kinases / metabolism
  • Nucleic Acid Synthesis Inhibitors / pharmacology
  • Paxillin
  • Phosphoproteins / metabolism
  • Phosphorylation
  • Protein-Serine-Threonine Kinases / genetics
  • Protein-Serine-Threonine Kinases / metabolism*
  • Protein-Tyrosine Kinases / metabolism
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism
  • Signal Transduction / physiology*
  • Tyrosine / metabolism
  • p21-Activated Kinases

Substances

  • Cytoskeletal Proteins
  • Nucleic Acid Synthesis Inhibitors
  • Paxillin
  • Phosphoproteins
  • Pxn protein, mouse
  • Recombinant Fusion Proteins
  • Cytochalasin D
  • Tyrosine
  • Protein-Tyrosine Kinases
  • Focal Adhesion Kinase 1
  • Focal Adhesion Protein-Tyrosine Kinases
  • Ptk2 protein, mouse
  • Protein-Serine-Threonine Kinases
  • p21-Activated Kinases
  • Cyclic AMP-Dependent Protein Kinases
  • Mitogen-Activated Protein Kinases