Peroxynitrite activates mitogen-activated protein kinase (MAPK) via a MEK-independent pathway: a role for protein kinase C

FEBS Lett. 2001 Jun 15;499(1-2):21-6. doi: 10.1016/s0014-5793(01)02511-x.


In this study we show that phosphorylation of extracellular signal-regulated kinase (ERK1/2; also known as p44/42MAPK) following peroxynitrite (ONOO(-)) exposure occurs via a MAPK kinase (MEK)-independent but PKC-dependent pathway in rat-1 fibroblasts. ONOO(-)-mediated ERK1/2 phosphorylation was not blocked by MEK inhibitors PD98059 and U0126. Furthermore, no increase in MEK phosphorylation was detected upon ONOO(-) treatment. Staurosporine was used to investigate whether protein kinase C (PKC) is involved. This was confirmed by down-regulation of PKC by phorbol-12,13-dibutyrate, which resulted in significant reduction of ERK1/2 phosphorylation by ONOO(-), implying that activation of ERK by ONOO(-) depends on activation of PKC. Indeed, PKCalpha and epsilon were activated upon ONOO(-) exposure. When cells were treated with ONOO(-) in a calcium-free buffer, no activation of PKCalpha was detected. Concomitantly, a reduction of ERK1/2 phosphorylation was observed suggesting that calcium was required for translocation of PKCalpha and ERK phosphorylation by ONOO(-). Indeed, ONOO(-) exposure resulted in increased cytosolic calcium, which depended on the presence of extracellular calcium. Finally, data using Gö6976, an inhibitor of calcium-dependent PKC activation, implied that ONOO(-)-mediated ERK1/2 phosphorylation depends on activation of a calcium-dependent PKC.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Calcium / metabolism
  • Calcium Signaling / drug effects
  • Cell Line
  • Cell Membrane / drug effects
  • Cell Membrane / enzymology
  • Cell Membrane / metabolism
  • Down-Regulation / drug effects
  • Enzyme Activation / drug effects
  • Fibroblasts
  • MAP Kinase Kinase 1
  • MAP Kinase Signaling System / drug effects*
  • Mitogen-Activated Protein Kinase Kinases / antagonists & inhibitors
  • Mitogen-Activated Protein Kinase Kinases / metabolism*
  • Mitogen-Activated Protein Kinases / metabolism*
  • Nitrates / pharmacology*
  • Phorbol 12,13-Dibutyrate / pharmacology
  • Phosphorylation / drug effects
  • Protein Kinase C / antagonists & inhibitors
  • Protein Kinase C / metabolism*
  • Protein Transport / drug effects
  • Protein-Serine-Threonine Kinases / antagonists & inhibitors
  • Protein-Serine-Threonine Kinases / metabolism*
  • Rats


  • Nitrates
  • peroxynitric acid
  • Phorbol 12,13-Dibutyrate
  • Protein-Serine-Threonine Kinases
  • Protein Kinase C
  • Mitogen-Activated Protein Kinases
  • MAP Kinase Kinase 1
  • Mitogen-Activated Protein Kinase Kinases
  • Calcium