GIT1 is a scaffold for ERK1/2 activation in focal adhesions

J Biol Chem. 2005 Jul 29;280(30):27705-12. doi: 10.1074/jbc.M502271200. Epub 2005 May 27.

Abstract

GIT1 (G protein-coupled receptor kinase-interacting protein 1) has been shown to regulate focal adhesion disassembly. We previously reported that GIT1 associates with MEK1 and acts as a scaffold to enhance ERK1/2 activation. Here, we show that GIT1 co-localizes with ERK1/2 in focal adhesions and regulates cell migration in vascular smooth muscle cells, HEK293 cells, and HeLa cells. Immunofluorescence showed that GIT1 co-localized with phospho-ERK1/2 in focal adhesions after epidermal growth factor stimulation. Because Src is required for both GIT1 tyrosine phosphorylation and focal adhesion disassembly, we studied the effects of Src on GIT1-ERK1/2 interactions. PP2 (4-amino-5-(4-chlorophenyl)-7-(t-butyl)pyrazolo[3,4-d]pyrimidine) inhibited association of GIT1 with ERK1/2, and their co-localization in focal adhesions was dramatically decreased in SYF-/- cells. GIT1 small interfering RNA significantly inhibited ERK1/2 recruitment to and activation in focal adhesions. GIT1 small interfering RNA and mutated GIT1 lacking the MEK1 binding domain significantly decreased epidermal growth factor-stimulated cell spreading and migration, suggesting that GIT1-mediated events such as ERK1/2 activation are required for spreading and migration. In summary, the present study further supports a key role for GIT1 (a MEK1-binding protein) as a scaffold for signal transduction in focal adhesions.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adaptor Proteins, Signal Transducing
  • Animals
  • Cell Cycle Proteins / metabolism
  • Cell Cycle Proteins / physiology*
  • Cell Line
  • Cell Movement
  • Chemotaxis
  • Cytoskeleton / metabolism
  • Enzyme Activation
  • Epidermal Growth Factor / metabolism
  • Focal Adhesions / metabolism
  • GTPase-Activating Proteins
  • HeLa Cells
  • Humans
  • Immunoblotting
  • Immunoprecipitation
  • Mice
  • Microscopy, Fluorescence
  • Mitogen-Activated Protein Kinase 1 / metabolism*
  • Mitogen-Activated Protein Kinase 3 / metabolism*
  • Mutation
  • Phosphoproteins / metabolism
  • Phosphoproteins / physiology*
  • Phosphorylation
  • Plasmids / metabolism
  • Protein Binding
  • Protein Structure, Tertiary
  • RNA Interference
  • RNA, Small Interfering / metabolism
  • Signal Transduction
  • Subcellular Fractions / metabolism
  • Time Factors
  • Transfection
  • Tyrosine / metabolism
  • src-Family Kinases / metabolism

Substances

  • Adaptor Proteins, Signal Transducing
  • Cell Cycle Proteins
  • GIT1 protein, human
  • GTPase-Activating Proteins
  • Git1 protein, mouse
  • Phosphoproteins
  • RNA, Small Interfering
  • Tyrosine
  • Epidermal Growth Factor
  • src-Family Kinases
  • Mitogen-Activated Protein Kinase 1
  • Mitogen-Activated Protein Kinase 3