C-Jun N-terminal kinases/c-Jun and p38 pathways cooperate in ceramide-induced neuronal apoptosis.
Understanding the regulation of the apoptotic program in neurons by intracellular pathways is currently a subject of great interest. Recent results suggest that c-Jun N-terminal kinases (JNK), mitogen-activated protein kinases and the transcription factor c-Jun are important regulators of this cell death program in post-mitotic neurons following survival-factor withdrawal. Our study demonstrates that ceramide levels increase upon survival-factor withdrawal in primary cultured cortical neurons. Furthermore, survival-factor withdrawal or addition of exogenous c(2)-ceramide induces JNK pathway activation in these cells. Western blot analyses of JNK and c-Jun using phospho-specific antibodies reveal that JNK and subsequent c-Jun phosphorylation occur hours before the initiation of apoptosis, reflected morphologically by neurite retraction and fragmentation, cell-body shrinkage and chromatin fragmentation. Immunocytochemistry using the same antibodies shows that phospho-JNK are localized in the neurites of control neurons and translocate to the nucleus where phospho-c-Jun concurrently appears upon ceramide-induced apoptosis. To determine if ceramide-induced c-Jun activation is responsible for the induction of the apoptotic program, we performed transient transfections of a dominant negative form of c-Jun, truncated in its transactivation region. Our results show that DNc-Jun partially protects cortical neurons from ceramide-induced apoptosis. Treatment of dominant negative c-Jun-expressing neurons with the pharmacological inhibitor of p38 kinase, SB203580, completely blocked neuronal death. Thus our data show that p38 and JNK/c-Jun pathways cooperate to induce neuronal apoptosis.
Willaime-Morawek
S
S
Laboratoire Signalisation Neuronale et Régulation Génique (UMR 7102), Case 12, 9 quai Saint Bernard, 75005 Paris, France.
Brami-Cherrier
K
K
Mariani
J
J
Caboche
J
J
Brugg
B
B
D000818:Animals; D017209:Apoptosis; D015153:Blotting, Western; D002470:Cell Survival / Q000187:drug effects; D002518:Ceramides / Q000494:pharmacology*; D002540:Cerebral Cortex / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D016895:Culture Media, Serum-Free / Q000494:pharmacology; D046508:Culture Techniques; D004268:DNA-Binding Proteins / Q000378:metabolism; D051766:Early Growth Response Protein 1; D004622:Embryo, Mammalian; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D005786:Gene Expression Regulation / Q000187:drug effects; D049452:Green Fluorescent Proteins; D007093:Imidazoles / Q000494:pharmacology; D017874:Immediate-Early Proteins; D007150:Immunohistochemistry; D048031:JNK Mitogen-Activated Protein Kinases; D008164:Luminescent Proteins / Q000378:metabolism; D048670:MAP Kinase Kinase 4; D051379:Mice; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D009474:Neurons / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D010766:Phosphorylation / Q000187:drug effects; D011247:Pregnancy; D011506:Proteins / Q000378:metabolism; D016755:Proto-Oncogene Proteins c-jun / Q000378:metabolism*; D011725:Pyridines / Q000494:pharmacology; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000494:pharmacology; D013347:Subcellular Fractions / Q000187:drug effects / Q000378:metabolism; D013997:Time Factors; D014157:Transcription Factors / Q000378:metabolism; D014162:Transfection / Q000379:methods; D048051:p38 Mitogen-Activated Protein Kinases
D002518:Ceramides; D016895:Culture Media, Serum-Free; D004268:DNA-Binding Proteins; D051766:Early Growth Response Protein 1; C486109:Egr1 protein, mouse; D004791:Enzyme Inhibitors; D007093:Imidazoles; D017874:Immediate-Early Proteins; D008164:Luminescent Proteins; C064769:N-acetylsphingosine; D011506:Proteins; D016755:Proto-Oncogene Proteins c-jun; D011725:Pyridines; D014157:Transcription Factors; D049452:Green Fluorescent Proteins; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D048670:MAP Kinase Kinase 4; D020929:Mitogen-Activated Protein Kinase Kinases; D013110:Sphingosine; C093642:SB 203580