Ceramide-induced apoptosis in cortical neurons is mediated by an increase in p38 phosphorylation and not by the decrease in ERK phosphorylation.
Ceramide, the central molecule of the sphingomyelin pathway, serves as a second messenger for cellular functions ranging from proliferation and differentiation to growth arrest and apoptosis. In this study we show that c2-ceramide induces apoptosis in primary cortical neuron cultures and that this effect correlates with differential modulation of mitogen-activated protein kinase (MAPK) cascades. Phosphorylation of extracellular signal-regulated kinases (ERKs) and their upstream activators MAPK kinases (MEKs), as measured by immunoblotting is rapidly decreased by c2-ceramide. However, the MEK inhibitor PD98059 alone does not induce apoptosis and in combination with c2-ceramide it does not modify c2-ceramide-induced apoptosis. Treatment with c2-ceramide increases p38 and c-Jun N-terminal kinase (JNK) phosphorylation before and during caspase-3 activation. The p38 inhibitor SB203580 partially protects cortical neurons against c2-ceramide-induced apoptosis, implicating the p38 pathway in this process. The c2-ceramide treatment also increases levels of c-jun, c-fos and p53 mRNA in primary cortical neuron cultures, but this is independent of p38 activation. Our study further elucidates the time-courses of MAPK cascade modulation, and of c-jun, c-fos and p53 activation during c2-ceramide-induced neuronal apoptosis. It reveals that one of the activated kinases, p38, is necessary for this apoptosis.
Willaime
S
S
Laboratoire Signalisation Neuronale et Régulation Génique (FRE 2371), boîte 14, 9 quai Saint Bernard, 75005 Paris, France. sandrine.willaime@snv.jussieu.fr
Vanhoutte
P
P
Caboche
J
J
Lemaigre-Dubreuil
Y
Y
Mariani
J
J
Brugg
B
B
D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D002470:Cell Survival / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured / Q000166:cytology / Q000187:drug effects / Q000201:enzymology; D002518:Ceramides / Q000378:metabolism* / Q000494:pharmacology; D002540:Cerebral Cortex / Q000166:cytology / Q000187:drug effects / Q000201:enzymology*; D015536:Down-Regulation / Q000187:drug effects / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005333:Fetus; D007093:Imidazoles / Q000494:pharmacology; D020935:MAP Kinase Signaling System / Q000187:drug effects / Q000502:physiology*; D051379:Mice; D048055:Mitogen-Activated Protein Kinase 8; D020928:Mitogen-Activated Protein Kinases / Q000187:drug effects / Q000378:metabolism*; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000201:enzymology*; D010766:Phosphorylation / Q000187:drug effects; D016760:Proto-Oncogene Proteins c-fos / Q000235:genetics; D016755:Proto-Oncogene Proteins c-jun / Q000235:genetics; D011725:Pyridines / Q000494:pharmacology; D012313:RNA / Q000187:drug effects / Q000378:metabolism; D013109:Sphingomyelins / Q000378:metabolism; D013110:Sphingosine / Q000031:analogs & derivatives / Q000494:pharmacology; D016159:Tumor Suppressor Protein p53 / Q000235:genetics; D015854:Up-Regulation / Q000187:drug effects / Q000502:physiology; D048051:p38 Mitogen-Activated Protein Kinases
D002518:Ceramides; D004791:Enzyme Inhibitors; D007093:Imidazoles; C064769:N-acetylsphingosine; D016760:Proto-Oncogene Proteins c-fos; D016755:Proto-Oncogene Proteins c-jun; D011725:Pyridines; D013109:Sphingomyelins; D016159:Tumor Suppressor Protein p53; D012313:RNA; D048055:Mitogen-Activated Protein Kinase 8; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D013110:Sphingosine; C093642:SB 203580