Abstract
The sphingomyelin-derived messenger ceramides provoke neuronal apoptosis through caspase-3 activation, while the neuropeptide pituitary adenylate cyclase-activating polypeptide (PACAP) promotes neuronal survival and inhibits caspase-3 activity. However, the mechanisms leading to the opposite regulation of caspase-3 by C2-ceramide and PACAP are currently unknown. Here, we show that PACAP prevents C2-ceramide-induced inhibition of mitochondrial potential and C2-ceramide-evoked cytochrome c release. C2-ceramide stimulated Bax expression, but had no effect on Bcl-2, while PACAP abrogated the action of C2-ceramide on Bax and stimulated Bcl-2 expression. The effects of C2-ceramide and PACAP on Bax and Bcl-2 were blocked, respectively, by the JNK inhibitor L-JNKI1 and the MEK inhibitor U0126. L-JNKI1 prevented the alteration of mitochondria induced by C2-ceramide while U0126 suppressed the protective effect of PACAP against the deleterious action of C2-ceramide on mitochondrial potential. Moreover, L-JNKI1 inhibited the stimulatory effect of C2-ceramide on caspase-9 and -3 and prevented C2-ceramide-induced cell death. U0126 blocked PACAP-induced Bcl-2 expression, abrogated the inhibitory effect of PACAP on ceramide-induced caspase-9 activity, and promoted granule cell death. The present study reveals that C2-ceramide and PACAP exert opposite effects on Bax and Bcl-2 through, respectively, JNK- and ERK-dependent mechanisms. These data indicate that the mitochondrial pathway plays a pivotal role in the pro- and anti-apoptotic effects of C2-ceramide and PACAP.
Publication types
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Comparative Study
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Research Support, Non-U.S. Gov't
MeSH terms
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Animals
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Animals, Newborn
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Benzimidazoles
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Blotting, Western / methods
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Carbocyanines
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Caspase 3
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Caspase 9
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Caspases / metabolism
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Cells, Cultured
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Cerebellum / cytology*
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Cytochromes c / metabolism
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Cytosol / drug effects
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Dose-Response Relationship, Drug
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Drug Interactions
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Enzyme Inhibitors / pharmacology
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Fluorescent Antibody Technique / methods
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Gene Expression Regulation / drug effects
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Intracellular Signaling Peptides and Proteins / metabolism
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Intracellular Signaling Peptides and Proteins / pharmacology
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JNK Mitogen-Activated Protein Kinases / metabolism
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MAP Kinase Kinase 4
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Membrane Potentials / drug effects
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Mice
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Mitochondria / drug effects*
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Mitochondria / physiology
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Mitogen-Activated Protein Kinase Kinases / metabolism
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Mitogen-Activated Protein Kinases / metabolism*
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Models, Neurological
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Nerve Growth Factors / pharmacology*
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Neurons / drug effects*
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Neuropeptides / pharmacology*
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Neurotransmitter Agents / pharmacology*
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Pituitary Adenylate Cyclase-Activating Polypeptide
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Proto-Oncogene Proteins c-bcl-2 / genetics
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Proto-Oncogene Proteins c-bcl-2 / metabolism
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RNA, Messenger / biosynthesis
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Rats
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Rats, Wistar
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Reverse Transcriptase Polymerase Chain Reaction / methods
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Signal Transduction / drug effects
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Sphingosine / analogs & derivatives*
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Sphingosine / pharmacology*
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Time Factors
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bcl-2-Associated X Protein
Substances
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2,3-N-octanoylsphingosine
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Adcyap1 protein, mouse
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Adcyap1 protein, rat
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Bax protein, mouse
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Bax protein, rat
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Benzimidazoles
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Carbocyanines
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Enzyme Inhibitors
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Intracellular Signaling Peptides and Proteins
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Mapkbp1 protein, mouse
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N-acetylsphingosine
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Nerve Growth Factors
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Neuropeptides
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Neurotransmitter Agents
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Pituitary Adenylate Cyclase-Activating Polypeptide
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Proto-Oncogene Proteins c-bcl-2
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RNA, Messenger
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bcl-2-Associated X Protein
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5,5',6,6'-tetrachloro-1,1',3,3'-tetraethylbenzimidazolocarbocyanine
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Cytochromes c
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JNK Mitogen-Activated Protein Kinases
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Mitogen-Activated Protein Kinases
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MAP Kinase Kinase 4
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Mitogen-Activated Protein Kinase Kinases
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Casp3 protein, mouse
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Casp3 protein, rat
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Casp9 protein, mouse
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Casp9 protein, rat
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Caspase 3
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Caspase 9
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Caspases
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Sphingosine