A complex between FAK, RACK1, and PDE4D5 controls spreading initiation and cancer cell polarity

Curr Biol. 2010 Jun 22;20(12):1086-92. doi: 10.1016/j.cub.2010.04.042. Epub 2010 May 20.


A fundamental question in cell biology concerns how cells respond to their environment by polarizing after sensing directional cues. This requires the differential localization of protein complexes in cells, and it is important to identify and understand how these complexes function. Here we describe a novel "direction-sensing" pathway that links the integrin effector focal adhesion kinase (FAK), the molecular scaffold protein RACK1, and activity of one of its client proteins, PDE4D5, a cAMP-degrading phosphodiesterase. The complex is recruited to nascent adhesions and promotes cell polarity. We identify FAK FERM domain residues whose mutation impairs RACK1 binding. When re-expressed in cancer cells in which endogenous fak is deleted by Cre-lox-mediated recombination, the RACK1-binding-impaired FAK mutant protein does not support formation of nascent actin adhesion structures as cells spread. These cancer cells, like FAK-deficient cells, cannot undergo directional responses, including wound-induced polarization or chemotactic invasion into three-dimensional matrix gels. We show that RACK1 serves as the molecular bridge linking FAK to the recruitment of PDE4D5. FAK/RACK1/PDE4D5 is a novel 'direction-sensing' complex that acts to recruit specific components of the cAMP second-messenger system to nascent integrin adhesions and to the leading edge of polarizing cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Polarity*
  • Chemotaxis
  • Cyclic Nucleotide Phosphodiesterases, Type 3 / metabolism*
  • Cyclic Nucleotide Phosphodiesterases, Type 4
  • Focal Adhesion Protein-Tyrosine Kinases / metabolism*
  • GTP-Binding Proteins / genetics
  • GTP-Binding Proteins / metabolism*
  • Humans
  • Mutation
  • Neoplasm Invasiveness
  • Neoplasm Proteins / genetics
  • Neoplasm Proteins / metabolism*
  • Neoplasms / pathology*
  • Receptors for Activated C Kinase
  • Receptors, Cell Surface / genetics
  • Receptors, Cell Surface / metabolism*


  • Neoplasm Proteins
  • RACK1 protein, human
  • Receptors for Activated C Kinase
  • Receptors, Cell Surface
  • Focal Adhesion Protein-Tyrosine Kinases
  • Cyclic Nucleotide Phosphodiesterases, Type 3
  • Cyclic Nucleotide Phosphodiesterases, Type 4
  • PDE4D protein, human
  • GTP-Binding Proteins