Pituitary adenylate cyclase-activating polypeptide prevents C2-ceramide-induced apoptosis of cerebellar granule cells.
The sphingolipid metabolites, ceramides, are critical mediators of the cellular stress response and play an important role in the control of programmed cell death. In particular, ceramides have been shown to induce apoptosis of cerebellar granule cells. We show that pituitary adenylate cyclase-activating polypeptide (PACAP) prevents C2-ceramide-induced apoptosis. The neuroprotective effect of PACAP was dose-dependent and blocked by its antagonist, PACAP6-38, whereas the PACAP-related peptide VIP was inactive. The effect of PACAP on cell survival was mimicked by dibutyryl-cAMP (dbcAMP) and forskolin and prevented by the MEK inhibitor U0126, indicating that both the adenylyl-cyclase and MAP-kinase pathways contribute to the neuroprotective action of the peptide. C2-ceramide and PACAP induced opposite effects on phosphorylated forms of ERK and JNK without affecting the total amounts of ERK and JNK, suggesting that a balance between these two MAP-kinases is critical for the cell survival/death decision. The effect of PACAP on ERK phosphorylation was blocked by U0126, but was not affected by H89 or chelerythrine indicating that PACAP activates ERK through a PKA- and PKC-independent mechanism. C2-ceramide induced a time-dependent activation of caspase-3, enhanced the amount of cleaved caspase-3 and stimulated the DNA fragmentation process, while PACAP strongly inhibited the C2-ceramide-induced activation of caspase-3, reduced the expression of cleaved caspase-3 and blocked DNA fragmentation. Taken together, the present results show that C2-ceramide induces apoptosis of cerebellar granule cells through a mechanism involving activation of caspase-3. Our data also demonstrate that PACAP is a potent inhibitor of C2-ceramide-induced apoptosis.
Vaudry
David
D
European Institute for Peptide Research (IFRMP 23), Laboratory of Cellular and Molecular Neuroendocrinology, INSERM U413, UA CNRS, University of Rouen, France. hubert.vaudry@univ-rouen.fr
Falluel-Morel
Anthony
A
Basille
Magali
M
Pamantung
Tommy F
TF
Fontaine
Marc
M
Fournier
Alain
A
Vaudry
Hubert
H
Gonzalez
Bruno J
BJ
D000262:Adenylyl Cyclases / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D015153:Blotting, Western; D020169:Caspases / Q000187:drug effects / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D002518:Ceramides / Q000633:toxicity*; D002531:Cerebellum / Q000187:drug effects / Q000201:enzymology; D053938:DNA Fragmentation / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D005786:Gene Expression Regulation / Q000187:drug effects; D020929:Mitogen-Activated Protein Kinase Kinases / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D009479:Neuropeptides / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D018696:Neuroprotective Agents / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D010766:Phosphorylation; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D051381:Rats; D017208:Rats, Wistar; D015398:Signal Transduction / Q000187:drug effects
C495403:Adcyap1 protein, rat; D002518:Ceramides; D009479:Neuropeptides; D018696:Neuroprotective Agents; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D020929:Mitogen-Activated Protein Kinase Kinases; D020169:Caspases; D000262:Adenylyl Cyclases