Differential requirement of EGF receptor and its tyrosine kinase for AP-1 transactivation induced by EGF and TPA

Oncogene. 2003 Jan 16;22(2):211-9. doi: 10.1038/sj.onc.1206102.


The transcription factor activator protein-1 (AP-1) has been implicated in a large variety of biological processes including cell differentiation, proliferation, apoptosis and oncogenic transformation. It is thought that the 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced AP-1 activity is because of the activation of the PKC/MAPK/AP-1 pathway, although the detailed molecular mechanism has not been fully characterized. The tyrosine kinases of epidermal growth factor receptor (EGFR) lie at the head of a complex of signal transduction cascade that modulates cell proliferation, survival, adhesion, migration and differentiation. Currently, little is known about whether EGFR or its tyrosine kinase is necessary for TPA-induced AP-1 activation. In the present study, we investigated this issue using a well-characterized mouse fibroblast B82 cell line, which is devoid of the EGFR, and its stable transfectants with either wild-type EGFR (B82L) or tyrosine kinase-deficient EGFR (mutation at Lys-721) (B82M721). We demonstrated that the TPA or epidermal growth factor (EGF) induced AP-1 activation in the B82L cells that express wild-type EGFR, but not in the B82 cell, whereas autophosphorylation at tyrosine(1173) of EGFR in B82L cells was only induced by EGF, but not TPA. The expression of tyrosine kinase-deficient EGFR (mutation at Lys-721) (B82M721) resulted in deficiency of AP-1 induction in cellular response to EGF, while TPA treatment led to fully AP-1 activation. Furthermore, the mutation at Lys-721 of EGFR resulted in impairing of EGFR autophosphorylation at tyrosine(1173) induced by EGF. Based on these results, we conclude that TPA-induced AP-1 activation requires the basal level-EGFR protein, but not EGFR tyrosine kinase and EGFR autophosphorylation at tyrosine(1173), whereas both EGFR tyrosine kinase and EGFR autophosphorylation at Y(1173) play a critical role in EGF-induced AP-1 activation.

Publication types

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

MeSH terms

  • Animals
  • Cells, Cultured
  • Enzyme Activation / drug effects
  • Epidermal Growth Factor / metabolism
  • Epidermal Growth Factor / pharmacology*
  • ErbB Receptors / genetics
  • ErbB Receptors / metabolism*
  • Fibroblasts
  • Humans
  • Lysine / genetics
  • Mice
  • Mitogen-Activated Protein Kinases / drug effects
  • Mitogen-Activated Protein Kinases / metabolism
  • Phosphorylation
  • Point Mutation
  • Tetradecanoylphorbol Acetate / pharmacology*
  • Transcription Factor AP-1 / drug effects
  • Transcription Factor AP-1 / genetics*
  • Transcription Factor AP-1 / metabolism
  • Transcriptional Activation / drug effects*
  • Transfection
  • Tyrosine / metabolism


  • Transcription Factor AP-1
  • Tyrosine
  • Epidermal Growth Factor
  • ErbB Receptors
  • Mitogen-Activated Protein Kinases
  • Lysine
  • Tetradecanoylphorbol Acetate