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

• Published in: Journal of neurochemistry 2006-11, Vol.99 (4), p.1237-1250
• Main Authors: Aubert, Nicolas, Falluel‐Morel, Anthony, Vaudry, David, Xifro, Xavier, Rodriguez‐Alvarez, José, Fisch, Cécile, De Jouffrey, Stéphane, Lebigot, Jean‐François, Fournier, Alain, Vaudry, Hubert, Gonzalez, Bruno J.
• Format: Article
• Language: English
• Subjects: activator protein‐1; Animals; Animals, Newborn; Apoptosis; Apoptosis - drug effects; Apoptosis - physiology; Biological and medical sciences; Cell physiology; Cell Survival; Cell Survival - drug effects; Cell Survival - physiology; Cells, Cultured; ceramide; Cerebellar Cortex; Cerebellar Cortex - drug effects; Cerebellar Cortex - metabolism; cerebellar granule cells; DNA-Binding Proteins; DNA-Binding Proteins - drug effects; DNA-Binding Proteins - metabolism; Dose-Response Relationship, Drug; Down-Regulation; Down-Regulation - genetics; Enzyme Inhibitors; Enzyme Inhibitors - pharmacology; Fundamental and applied biological sciences. Psychology; Gene expression; Gene Expression Regulation; Gene Expression Regulation - drug effects; Gene Expression Regulation - genetics; Kinases; Life Sciences; MAP Kinase Signaling System; MAP Kinase Signaling System - drug effects; MAP Kinase Signaling System - physiology; Molecular and cellular biology; Molecular genetics; Neurology; Neurons; Neurons - drug effects; Neurons - metabolism; Peptides; Phosphoprotein Phosphatases; Phosphoprotein Phosphatases - antagonists & inhibitors; Phosphoprotein Phosphatases - metabolism; Phosphorylation; Phosphorylation - drug effects; Pituitary Adenylate Cyclase-Activating Polypeptide; Pituitary Adenylate Cyclase-Activating Polypeptide - metabolism; Pituitary Adenylate Cyclase-Activating Polypeptide - pharmacology; Protein Phosphatase 2; Proteins; Proto-Oncogene Proteins c-bcl-2; Proto-Oncogene Proteins c-bcl-2 - drug effects; Proto-Oncogene Proteins c-bcl-2 - metabolism; Proto-Oncogene Proteins c-fos; Proto-Oncogene Proteins c-fos - drug effects; Proto-Oncogene Proteins c-fos - genetics; Proto-Oncogene Proteins c-fos - metabolism; Proto-Oncogene Proteins c-jun; Proto-Oncogene Proteins c-jun - drug effects; Proto-Oncogene Proteins c-jun - metabolism; Rats; Rats, Wistar; Rodents; Signal transduction; Sphingosine; Sphingosine - analogs & derivatives; Sphingosine - metabolism; Sphingosine - pharmacology; Toxicology; Transcription Factor AP-1; Transcription Factor AP-1 - metabolism; Transcription. Transcription factor. Splicing. Rna processing; Transcriptional Activation; Transcriptional Activation - drug effects; Transcriptional Activation - physiology
• ISSN: 0022-3042; 1471-4159
• DOI: 10.1111/j.1471-4159.2006.04148.x

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.