Bradykinin stimulates the ERK-->Elk-1-->Fos/AP-1 pathway in mesangial cells

Am J Physiol. 1998 Sep;275(3):F343-52. doi: 10.1152/ajprenal.1998.275.3.F343.


Among its diverse biological actions, the vasoactive peptide bradykinin (BK) induces the transcription factor AP-1 and proliferation of mesangial cells (S. S. El-Dahr, S. Dipp, I. V. Yosipiv, and W. H. Baricos. Kidney Int. 50: 1850-1855, 1996). In the present study, we examined the role of protein tyrosine phosphorylation and the mitogen-activated protein kinases, ERK1/2,in mediating BK-induced AP-1 and DNA replication in cultured rat mesangial cells. BK (10(-9) to 10(-7) M) stimulated a rapid increase in tyrosine phosphorylation of multiple proteins with an estimated molecular mass of 120-130, 90-95, and 44-42 kDa. Immunoblots using antibodies specific for ERK or tyrosine-phosphorylated ERK revealed a shifting of p42 ERK2 to a higher molecular weight that correlated temporally with an increase in tyrosine-phosphorylated ERK2. Genistein, a specific tyrosine kinase inhibitor, prevented the phosphorylation of ERK2 by BK. In-gel kinase assays indicated that BK-induced tyrosine phosphorylation of ERK2 is accompanied by fourfold activation of its phosphotransferase activity toward the substrate PHAS-I (P < 0.05). Furthermore, BK stimulated a 2.5-fold increase (P < 0.05) in phosphorylation of Elk-1, a transcription factor required for growth factor-induced c-fos transcription. In accord with the stimulation of Elk-1 phosphorylation, BK induced c-fos gene expression and the production of Fos/AP-1 complexes. In addition, thymidine incorporation into DNA increased twofold (P < 0. 05) following BK stimulation. Each of these effects was blocked by tyrosine kinase inhibition with genistein or herbimycin A. Similarly, antisense oligodeoxynucleotide targeting of ERK1/2 mRNA inhibited BK-stimulated DNA synthesis. In contrast, protein kinase C inhibition or depletion had no effect on BK-induced c-fos mRNA, AP-1-DNA binding activity, or DNA synthesis. Collectively, these data demonstrate that BK activates the ERK-->Elk-1-->AP-1 pathway and that BK mitogenic signaling is critically dependent on protein tyrosine phosphorylation.

Publication types

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

MeSH terms

  • Animals
  • Bradykinin / pharmacology*
  • Calcium-Calmodulin-Dependent Protein Kinases / metabolism
  • Cells, Cultured
  • DNA / biosynthesis
  • DNA-Binding Proteins*
  • Enzyme Activation
  • Glomerular Mesangium / drug effects
  • Glomerular Mesangium / metabolism*
  • Male
  • Mitogen-Activated Protein Kinases / metabolism*
  • Phosphorylation
  • Phosphotyrosine / metabolism
  • Proto-Oncogene Proteins / metabolism*
  • Proto-Oncogene Proteins c-fos / metabolism*
  • Rats
  • Rats, Sprague-Dawley
  • Signal Transduction
  • Tetradecanoylphorbol Acetate / pharmacology
  • Transcription Factor AP-1 / metabolism*
  • Transcription Factors*
  • ets-Domain Protein Elk-1


  • DNA-Binding Proteins
  • Elk1 protein, rat
  • Proto-Oncogene Proteins
  • Proto-Oncogene Proteins c-fos
  • Transcription Factor AP-1
  • Transcription Factors
  • ets-Domain Protein Elk-1
  • Phosphotyrosine
  • DNA
  • Calcium-Calmodulin-Dependent Protein Kinases
  • Mitogen-Activated Protein Kinases
  • Tetradecanoylphorbol Acetate
  • Bradykinin