title: C2-ceramide and reactive oxygen species inhibit pituitary adenylate cyclase activating polypeptide (PACAP)-induced cyclic-AMP-dependent signalling pathway.
abstract: The pituitary adenylate cyclase activating polypeptide (PACAP) type I receptor, a seven-domain transmembrane receptor, is positively coupled to both adenylate cyclase and phospholipase C. PACAP exerts neurotrophic effects which are mainly mediated through the cAMP/protein kinase A pathway. Here we show that the cell-permeable C2-ceramide selectively blocks PACAP-activated cAMP production, without affecting phosphoinositide breakdown. Thus by blocking the neuroprotective cAMP signalling pathway, C2-ceramide will reinforce its direct death-inducing signalling. We found that a reactive oxygen species scavenger reversed the C2-ceramide effect and that H2O2 mimicked it. Together these data indicate that reactive oxygen species (ROS) mediates C2-ceramide-induced cAMP pathway uncoupling. This uncoupling did not involve ATP supply or Galphas protein function but rather adenylate cyclase function per se. Further, the tyrosine phosphatase inhibitors, but not the serine/threonine phosphatase inhibitors, prevent inhibition of cAMP production by ROS. This suggests that H2O2 requires a functional tyrosine phosphatase(s) to block PACAP-dependent cAMP production.
authors.affiliation: Université Louis Pasteur, UMR 7519 CNRS, Strasbourg Cedex, France.
authors.forename: V
authors.initials: V
authors.lastname: Sée
authors.forename: B
authors.initials: B
authors.lastname: Koch
authors.forename: J P
authors.initials: JP
authors.lastname: Loeffler
mesh_terms: D000262:Adenylyl Cyclases / Q000502:physiology; D002460:Cell Line; D000242:Cyclic AMP / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000502:physiology*; D019204:GTP-Binding Proteins / Q000502:physiology; D009479:Neuropeptides / Q000494:pharmacology*; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D017027:Protein Tyrosine Phosphatases / Q000502:physiology; D017382:Reactive Oxygen Species / Q000502:physiology*; D051236:Receptors, Pituitary Adenylate Cyclase-Activating Polypeptide; D051237:Receptors, Pituitary Adenylate Cyclase-Activating Polypeptide, Type I; D011979:Receptors, Pituitary Hormone / Q000502:physiology; D015398:Signal Transduction / Q000187:drug effects* / Q000502:physiology*; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000494:pharmacology / Q000502:physiology*
chemical_list: C064769:N-acetylsphingosine; D009479:Neuropeptides; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D017382:Reactive Oxygen Species; D051236:Receptors, Pituitary Adenylate Cyclase-Activating Polypeptide; D051237:Receptors, Pituitary Adenylate Cyclase-Activating Polypeptide, Type I; D011979:Receptors, Pituitary Hormone; D000242:Cyclic AMP; D017027:Protein Tyrosine Phosphatases; D019204:GTP-Binding Proteins; D000262:Adenylyl Cyclases; D013110:Sphingosine