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.
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.
Repici
M
M
Département de Biologie Cellulaire et de Morphologie, Université de Lausanne, Rue du Bugnon 9, CH-1005 Lausanne, Switzerland.
Mare
L
L
Colombo
A
A
Ploia
C
C
Sclip
A
A
Bonny
C
C
Nicod
P
P
Salmona
M
M
Borsello
T
T
D051698:Activating Transcription Factor 2 / Q000378:metabolism; D000595:Amino Acid Sequence; D000704:Analysis of Variance; D000818:Animals; D000831:Animals, Newborn; D002540:Cerebral Cortex / Q000166:cytology*; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation / Q000187:drug effects; D048049:Extracellular Signal-Regulated MAP Kinases; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism*; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D048670:MAP Kinase Kinase 4 / Q000378:metabolism*; D048688:MAP Kinase Kinase 7 / Q000378:metabolism*; D009474:Neurons / Q000378:metabolism*; D010455:Peptides / Q000494:pharmacology; D010766:Phosphorylation; D011485:Protein Binding / Q000502:physiology; D054730:Protein Interaction Domains and Motifs; D051381:Rats; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D050807:ets-Domain Protein Elk-1 / Q000378:metabolism
D051698:Activating Transcription Factor 2; D010455:Peptides; D050807:ets-Domain Protein Elk-1; D007770:L-Lactate Dehydrogenase; D048049:Extracellular Signal-Regulated MAP Kinases; D048031:JNK Mitogen-Activated Protein Kinases; D048670:MAP Kinase Kinase 4; D048688:MAP Kinase Kinase 7; C478085:D-JNKI-1