An incomplete program of cellular tyrosine phosphorylations induced by kinase-defective epidermal growth factor receptors

J Biol Chem. 1995 May 19;270(20):12085-93. doi: 10.1074/jbc.270.20.12085.

Abstract

Although signaling by the epidermal growth factor (EGF) receptor is thought to be dependent on receptor tyrosine kinase activity, it is clear that mitogen-activated protein (MAP) kinase can be activated by receptors lacking kinase activity. Since analysis of the signaling pathways used by kinase-defective receptors could reveal otherwise masked capabilities, we examined in detail the tyrosine phosphorylations and enzymes of the MAP kinase pathway induced by kinase-defective EGF receptors. Following EGF stimulation of B82L cells expressing a kinase-defective EGF receptor mutant (K721M), we found that ERK2 and ERK1 MAP kinases, as well as MEK1 and MEK2 were all activated, and SHC became prominently tyrosine-phosphorylated. By contrast, kinase-defective receptors failed to induce detectable phosphorylations of GAP (GTPase-activating protein), p62, JAK1, or p91STAT1, all of which were robustly phosphorylated by wild-type receptors. These data demonstrate that kinase-defective receptors induce several protein tyrosine phosphorylations, but that these represent only a subset of those seen with wild-type receptors. This suggests that kinase-defective receptors activate a heterologous tyrosine kinase with a specificity different from the EGF receptor. We found that kinase-defective receptors induced ErbB2/c-Neu enzymatic activation and ErbB2/c-Neu binding to SHC at a level even greater than that induced by wild-type receptors. Thus, heterodimerization with and activation of endogenous ErbB2/c-Neu is a possible mechanism by which kinase-defective receptors stimulate the MAP kinase pathway.

Publication types

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

MeSH terms

  • Adaptor Proteins, Signal Transducing*
  • Animals
  • Calcium-Calmodulin-Dependent Protein Kinases / metabolism*
  • Cell Line
  • DNA-Binding Proteins / metabolism
  • Enzyme Activation
  • ErbB Receptors / genetics
  • ErbB Receptors / metabolism*
  • GRB2 Adaptor Protein
  • GTPase-Activating Proteins
  • Humans
  • Janus Kinase 2
  • MAP Kinase Kinase 1
  • MAP Kinase Kinase 2
  • Mice
  • Mitogen-Activated Protein Kinase 1
  • Mitogen-Activated Protein Kinase 3
  • Mitogen-Activated Protein Kinase Kinases*
  • Mitogen-Activated Protein Kinases*
  • Phosphorylation
  • Phosphotyrosine
  • Protein Processing, Post-Translational*
  • Protein Serine-Threonine Kinases / metabolism
  • Protein-Tyrosine Kinases / metabolism
  • Proteins / metabolism
  • Proto-Oncogene Proteins*
  • Receptor Protein-Tyrosine Kinases / deficiency*
  • Receptor Protein-Tyrosine Kinases / genetics
  • Receptor, ErbB-2 / metabolism
  • Recombinant Fusion Proteins / metabolism
  • STAT1 Transcription Factor
  • Signal Transduction*
  • Trans-Activators / metabolism
  • Tyrosine / analogs & derivatives
  • Tyrosine / metabolism

Substances

  • Adaptor Proteins, Signal Transducing
  • DNA-Binding Proteins
  • GRB2 Adaptor Protein
  • GRB2 protein, human
  • GTPase-Activating Proteins
  • Grb2 protein, mouse
  • Proteins
  • Proto-Oncogene Proteins
  • Recombinant Fusion Proteins
  • STAT1 Transcription Factor
  • STAT1 protein, human
  • Stat1 protein, mouse
  • Trans-Activators
  • Phosphotyrosine
  • Tyrosine
  • MAP2K2 protein, human
  • ErbB Receptors
  • Protein-Tyrosine Kinases
  • Receptor Protein-Tyrosine Kinases
  • Receptor, ErbB-2
  • JAK2 protein, human
  • Jak2 protein, mouse
  • Janus Kinase 2
  • Protein Serine-Threonine Kinases
  • Calcium-Calmodulin-Dependent Protein Kinases
  • Mitogen-Activated Protein Kinase 1
  • Mitogen-Activated Protein Kinase 3
  • Mitogen-Activated Protein Kinases
  • MAP Kinase Kinase 1
  • MAP Kinase Kinase 2
  • MAP2K1 protein, human
  • Map2k1 protein, mouse
  • Mitogen-Activated Protein Kinase Kinases