Tyrosine phosphorylation of Grb2 by Bcr/Abl and epidermal growth factor receptor: a novel regulatory mechanism for tyrosine kinase signaling

EMBO J. 2001 Dec 3;20(23):6793-804. doi: 10.1093/emboj/20.23.6793.

Abstract

Growth factor receptor-binding protein-2 (Grb2) plays a key role in signal transduction initiated by Bcr/Abl oncoproteins and growth factors, functioning as an adaptor protein through its Src homology 2 and 3 (SH2 and SH3) domains. We found that Grb2 was tyrosine-phosphorylated in cells expressing BCR/ABL and in A431 cells stimulated with epidermal growth factor (EGF). Phosphorylation of Grb2 by Bcr/Abl or EGF receptor reduced its SH3-dependent binding to Sos in vivo, but not its SH2-dependent binding to Bcr/Abl. Tyr209 within the C-terminal SH3 domain of Grb2 was identified as one of the tyrosine phosphorylation sites, and phosphorylation of Tyr209 abolished the binding of the SH3 domain to a proline-rich Sos peptide in vitro. In vivo expression of a Grb2 mutant where Tyr209 was changed to phenylalanine enhanced BCR/ABL-induced ERK activation and fibroblast transformation, and potentiated and prolonged Grb2-mediated activation of Ras, mitogen-activated protein kinase and c-Jun N-terminal kinase in response to EGF stimulation. These results suggest that tyrosine phosphorylation of Grb2 is a novel mechanism of down-regulation of tyrosine kinase signaling.

Publication types

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

MeSH terms

  • 3T3 Cells
  • Adaptor Proteins, Signal Transducing*
  • Animals
  • Binding Sites
  • Blotting, Western
  • Cell Line
  • Cell Line, Transformed
  • DNA Mutational Analysis
  • Dose-Response Relationship, Drug
  • Down-Regulation
  • Enzyme Activation
  • ErbB Receptors / metabolism*
  • Fibroblasts / metabolism
  • Fusion Proteins, bcr-abl / metabolism*
  • GRB2 Adaptor Protein
  • Humans
  • JNK Mitogen-Activated Protein Kinases
  • K562 Cells
  • MAP Kinase Signaling System
  • Mass Spectrometry
  • Mice
  • Mitogen-Activated Protein Kinases / metabolism
  • Mutation
  • Peptide Mapping
  • Phosphopeptides / chemistry
  • Phosphorylation
  • Precipitin Tests
  • Protein Binding
  • Protein Structure, Tertiary
  • Proteins / metabolism*
  • Signal Transduction
  • Son of Sevenless Protein, Drosophila / metabolism
  • Time Factors
  • Transfection
  • Transformation, Genetic
  • Tumor Cells, Cultured
  • Tyrosine / metabolism*
  • ras Proteins / metabolism
  • src Homology Domains

Substances

  • Adaptor Proteins, Signal Transducing
  • GRB2 Adaptor Protein
  • GRB2 protein, human
  • Grb2 protein, mouse
  • Phosphopeptides
  • Proteins
  • Son of Sevenless Protein, Drosophila
  • Tyrosine
  • ErbB Receptors
  • Fusion Proteins, bcr-abl
  • JNK Mitogen-Activated Protein Kinases
  • Mitogen-Activated Protein Kinases
  • ras Proteins

Associated data

  • PDB/4G10