title: Involvement of p38 MAP kinase-mediated cytochrome c release on sphingosine-1-phosphate (S1P)- and N-monomethyl-S1P-induced cell death of PC12 cells.
abstract: d-erythro-Sphingosine-1-phosphate (S1P), a sphingolipid metabolite, affects various neuronal functions including cell fate. S1P appears to have contradictory effects in PC12 cells, a neuronal model cell line; neurite retraction and cell survival/differentiation. In the present study, we examined whether S1P induces cell death in undifferentiated PC12 cells. Culture with S1P at 20 microM for 4 h caused lactate dehydrogenase leakage 24 h later. The response was reduced by an inhibitor of caspases and accompanied by the release of cytochrome c and DNA fragmentation. S1P caused the phosphorylation of p38 mitogen-activated protein kinase (p38 MAPK) within 10 min. An inhibitor of p38 MAPK (10 microM SB203580) inhibited both the release of cytochrome c and DNA fragmentation induced by S1P. Treatment with nerve growth factor or pertussis toxin (PTX) decreased S1P-induced phosphorylation of p38 MAPK and cell death. These findings suggest that S1P-activated p38 MAPK acts as a death signal upstream of the release of cytochrome c. N-Monomethyl-S1P (MM-S1P), a weak agonist in cells expressing S1P1 receptors, had marked effects (phosphorylation of p38 MAPK, release of cytochrome c and DNA fragmentation) at lower concentrations than S1P and in a PTX-sensitive manner. These findings show that the activation of S1P receptors by S1P and MM-S1P causes cell death accompanied by DNA fragmentation via the p38 MAPK pathway-mediated release of cytochrome c in PC12 cells. The potential of S1P and MM-S1P to act as agonists of S1P receptors and as intracellular messengers is discussed.
authors.affiliation: Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, Chiba University, Chiba 260-8675, Japan.
authors.forename: Yuko
authors.initials: Y
authors.lastname: Takashiro
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Nakamura
authors.forename: Yuuki
authors.initials: Y
authors.lastname: Koide
authors.forename: Atsushi
authors.initials: A
authors.lastname: Nishida
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Murayama
mesh_terms: D000818:Animals; D016923:Cell Death / Q000187:drug effects / Q000502:physiology; D045304:Cytochromes c / Q000378:metabolism* / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D007093:Imidazoles / Q000494:pharmacology; D008246:Lysophospholipids / Q000502:physiology*; D016716:PC12 Cells; D011725:Pyridines / Q000494:pharmacology; D051381:Rats; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000502:physiology*; D048051:p38 Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000502:physiology*
chemical_list: D007093:Imidazoles; D008246:Lysophospholipids; D011725:Pyridines; C060506:sphingosine 1-phosphate; D045304:Cytochromes c; D048051:p38 Mitogen-Activated Protein Kinases; D013110:Sphingosine; C093642:SB 203580