Pituitary adenylate cyclase-activating polypeptide prevents the effects of ceramides on migration, neurite outgrowth, and cytoskeleton remodeling.
During neuronal migration, cells that do not reach their normal destination or fail to establish proper connections are eliminated through an apoptotic process. Recent studies have shown that the proinflammatory cytokine tumor necrosis factor alpha (and its second messengers ceramides) and the neuropeptide pituitary adenylate cyclase-activating polypeptide (PACAP) play a pivotal role in the histogenesis of the cerebellar cortex. However, the effects of ceramides and PACAP on migration of cerebellar granule cells have never been investigated. Time-lapse videomicroscopy recording showed that C2-ceramide, a cell-permeable ceramide analog, and PACAP induced opposite effects on cell motility and neurite outgrowth. C2-ceramide markedly stimulated cell movements during the first hours of treatment and inhibited neuritogenesis, whereas PACAP reduced cell migration and promoted neurite outgrowth. These actions of C2-ceramide on cell motility and neurite outgrowth were accompanied by a disorganization of the actin filament network, depolarization of tubulin, and alteration of the microtubule-associated protein Tau. In contrast, PACAP strengthened the polarization of actin at the emergence cone, increased Tau phosphorylation, and abolished C2-ceramide-evoked alterations of the cytoskeletal architecture. The caspase-inhibitor Z-VAD-FMK, like PACAP, suppressed the "dance of the death" provoked by C2-ceramide. Finally, Z-VAD-FMK and the PP2A inhibitor okadaic acid both prevented the impairment of Tau phosphorylation induced by C2-ceramide. Taken together, these data indicate that the reverse actions of C2-ceramide and PACAP on cerebellar granule cell motility and neurite outgrowth are attributable to their opposite effects on actin distribution, tubulin polymerization, and Tau phosphorylation.
Falluel-Morel
Anthony
A
European Institute for Peptide Research (Institut Fédératif de Recherches Multidisciplinares sur les Peptides 23), Institut National de la Santé et de la Recherche Médicale U413, University of Rouen, 76821 Mont-Saint-Aignan, France.
Vaudry
David
D
Aubert
Nicolas
N
Galas
Ludovic
L
Benard
Magalie
M
Basille
Magali
M
Fontaine
Marc
M
Fournier
Alain
A
Vaudry
Hubert
H
Gonzalez
Bruno J
BJ
D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D000818:Animals; D002465:Cell Movement / Q000187:drug effects; D002478:Cells, Cultured; D002531:Cerebellum / Q000166:cytology; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D003599:Cytoskeleton / Q000187:drug effects; D018715:Microscopy, Video; D009414:Nerve Growth Factors / Q000494:pharmacology* / Q000502:physiology; D009419:Nerve Tissue Proteins / Q000737:chemistry / Q000378:metabolism; D016501:Neurites / Q000187:drug effects / Q000648:ultrastructure; D009474:Neurons / Q000187:drug effects* / Q000502:physiology / Q000648:ultrastructure; D009479:Neuropeptides / Q000494:pharmacology* / Q000502:physiology; D018377:Neurotransmitter Agents / Q000494:pharmacology* / Q000502:physiology; D010750:Phosphoproteins / Q000737:chemistry / Q000378:metabolism; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D051381:Rats; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000494:pharmacology* / Q000502:physiology; D016875:tau Proteins
C495403:Adcyap1 protein, rat; D000590:Amino Acid Chloromethyl Ketones; D015853:Cysteine Proteinase Inhibitors; C489131:Mapt protein, rat; C064769:N-acetylsphingosine; D009414:Nerve Growth Factors; D009419:Nerve Tissue Proteins; D009479:Neuropeptides; D018377:Neurotransmitter Agents; D010750:Phosphoproteins; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; D016875:tau Proteins; D013110:Sphingosine