PACAP and C2-ceramide generate different AP-1 complexes through a MAP-kinase-dependent pathway: involvement of c-Fos in PACAP-induced Bcl-2 expression.
The neuropeptide pituitary adenylate cyclase-activating polypeptide (PACAP) inhibits C2-ceramide-induced cell death through blockade of the mitochondrial apoptotic pathway in rat cerebellar granule neurones. However, the gene induction processes and transcription factors involved in the anti-apoptotic effect of PACAP remain unknown. Here, we show that PACAP and C2-ceramide activate activator protein-1 (AP-1) DNA binding in a dose- and time-dependent manner, but generate different AP-1 dimers. Thus, PACAP increased the proportion of c-Fos and Jun D while C2-ceramide increased c-Jun and reduced c-Fos in AP-1 complexes. In addition, PACAP strongly activated c-Fos gene expression while C2-ceramide markedly increased c-Jun phosphorylation. The effect of PACAP on c-Fos expression was blocked by the mitogen-activated protein kinase/extracellular signal-regulated kinase (MEK) inhibitor, U0126, while phosphorylation of c-Jun induced by C2-ceramide was abrogated by the protein phosphatase 2A (PP2A) inhibitor, okadaic acid. Transfection of immature granule cells with c-Fos siRNA, which strongly reduced basal and PACAP-stimulated levels of the protein, totally prevented the stimulatory effect of PACAP on Bcl-2 expression. The present study demonstrates that AP-1 complexes containing c-Fos mediate the effect of PACAP on Bcl-2 gene expression in cerebellar granule neurones. Our data also indicate that different AP-1 dimers are associated with the pro-apoptotic effect of C2-ceramide and the anti-apoptotic effect of PACAP.
Aubert
Nicolas
N
INSERM U413, Laboratory of Cellular and Molecular Neuroendocrinology, European Institute for Peptide Research, University of Rouen, Mont-Saint-Aignan, France.
Falluel-Morel
Anthony
A
Vaudry
David
D
Xifro
Xavier
X
Rodriguez-Alvarez
José
J
Fisch
Cécile
C
de Jouffrey
Stéphane
S
Lebigot
Jean-François
JF
Fournier
Alain
A
Vaudry
Hubert
H
Gonzalez
Bruno J
BJ
D000818:Animals; D000831:Animals, Newborn; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology; D002470:Cell Survival / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D002525:Cerebellar Cortex / Q000187:drug effects / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000187:drug effects / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation / Q000235:genetics; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects / Q000235:genetics; D020935:MAP Kinase Signaling System / Q000187:drug effects / Q000502:physiology*; D009474:Neurons / Q000187:drug effects / Q000378:metabolism; D010749:Phosphoprotein Phosphatases / Q000037:antagonists & inhibitors / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide / Q000378:metabolism* / Q000494:pharmacology; D054648:Protein Phosphatase 2; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000187:drug effects / Q000378:metabolism*; D016760:Proto-Oncogene Proteins c-fos / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D016755:Proto-Oncogene Proteins c-jun / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology; D018808:Transcription Factor AP-1 / Q000378:metabolism*; D015533:Transcriptional Activation / Q000187:drug effects / Q000502:physiology
D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors; C064769:N-acetylsphingosine; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D019253:Proto-Oncogene Proteins c-bcl-2; D016760:Proto-Oncogene Proteins c-fos; D016755:Proto-Oncogene Proteins c-jun; D018808:Transcription Factor AP-1; D010749:Phosphoprotein Phosphatases; D054648:Protein Phosphatase 2; D013110:Sphingosine