c-Jun N-terminal kinase binding domain-dependent phosphorylation of mitogen-activated protein kinase kinase 4 and mitogen-activated protein kinase kinase 7 and balancing cross-talk between c-Jun N-terminal kinase and extracellular signal-regulated kinase pathways in cortical neurons

M Repici, L Mare, A Colombo, C Ploia, A Sclip, C Bonny, P Nicod, M Salmona, T Borsello

Research output: Contribution to journalArticle


The c-Jun N-terminal kinase (JNK) is a mitogen-activated protein kinase (MAPK) activated by stress-signals and involved in many different diseases. Previous results proved the powerful effect of the cell permeable peptide inhibitor d-JNKI1 (d-retro-inverso form of c-Jun N-terminal kinase-inhibitor) against neuronal death in CNS diseases, but the precise features of this neuroprotection remain unclear. We here performed cell-free and in vitro experiments for a deeper characterization of d-JNKI1 features in physiological conditions. This peptide works by preventing JNK interaction with its c-Jun N-terminal kinase-binding domain (JBD) dependent targets. We here focused on the two JNK upstream MAPKKs, mitogen-activated protein kinase kinase 4 (MKK4) and mitogen-activated protein kinase kinase 7 (MKK7), because they contain a JBD homology domain. We proved that d-JNKI1 prevents MKK4 and MKK7 activity in cell-free and in vitro experiments: these MAPKK could be considered not only activators but also substrates of JNK. This means that d-JNKI1 can interrupt downstream but also upstream events along the JNK cascade, highlighting a new remarkable feature of this peptide. We also showed the lack of any direct effect of the peptide on p38, MEK1, and extracellular signal-regulated kinase (ERK) in cell free, while in rat primary cortical neurons JNK inhibition activates the MEK1-ERK-Ets1/c-Fos cascade. JNK inhibition induces a compensatory effect and leads to ERK activation via MEK1, resulting in an activation of the survival pathway-(MEK1/ERK) as a consequence of the death pathway-(JNK) inhibition. This study should hold as an important step to clarify the strong neuroprotective effect of d-JNKI1.

Original languageEnglish
Pages (from-to)94-103
Number of pages10
Issue number1
Publication statusPublished - 3 Mar 2009



  • Activating Transcription Factor 2/metabolism
  • Amino Acid Sequence
  • Analysis of Variance
  • Animals
  • Animals, Newborn
  • Cerebral Cortex/cytology
  • Dose-Response Relationship, Drug
  • Enzyme Activation/drug effects
  • Extracellular Signal-Regulated MAP Kinases
  • JNK Mitogen-Activated Protein Kinases/metabolism
  • L-Lactate Dehydrogenase/metabolism
  • MAP Kinase Kinase 4/metabolism
  • MAP Kinase Kinase 7/metabolism
  • Neurons/metabolism
  • Peptides/pharmacology
  • Phosphorylation
  • Protein Binding/physiology
  • Protein Interaction Domains and Motifs
  • Rats
  • Signal Transduction/drug effects
  • ets-Domain Protein Elk-1/metabolism

Cite this