title: Ceramide induces neuronal apoptosis through mitogen-activated protein kinases and causes release of multiple mitochondrial proteins.
abstract: Ceramide accumulates in neurons during various disorders associated with acute or chronic neurodegeneration. In these studies, we investigated the mechanisms of ceramide-induced apoptosis in primary cortical neurons using exogenous C(2) ceramide as well as inducing endogenous ceramide accumulation using inhibitors of glucosylceramide synthetase. Ceramide induced the translocation of certain, but not all, pro-apoptotic mitochondrial proteins: cytochrome c, Omi, SMAC, and AIF were released from the mitochondria, whereas Endonuclease G was not. Ceramide also selectively altered the phosphorylation state of members of the MAPK superfamily, causing dephosphorylation of ERK1/2 and hyperphosphorylation of p38 MAP kinases, but not affecting the phosphorylation of JNK or ERK5. Inhibitors of the p38 MAP kinase pathway (SB-202190 or SB-203580) and an inhibitor of the ERK1/2 pathway (U0126) reduced ceramide-induced neuronal death. These p38 and ERK1/2 inhibitors appear to block ceramide-activated apoptotic signaling upstream of the mitochondria, as they attenuated mitochondrial release of cytochrome c, Omi, AIF, and SMAC, as well as reducing ceramide-induced caspase-3 activation.
authors.affiliation: Department of Neuroscience, Georgetown University Medical Center, 3970 Reservoir Road, N.W., Research Building, Room EP-12, Washington, DC 20057, USA.
authors.forename: Bogdan A
authors.initials: BA
authors.lastname: Stoica
authors.forename: Vilen A
authors.initials: VA
authors.lastname: Movsesyan
authors.forename: Susan M
authors.initials: SM
authors.lastname: Knoblach
authors.forename: Alan I
authors.initials: AI
authors.lastname: Faden
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D051033:Apoptosis Inducing Factor; D051017:Apoptosis Regulatory Proteins; D002352:Carrier Proteins / Q000378:metabolism; D053148:Caspase 3; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism; D002478:Cells, Cultured; D002518:Ceramides / Q000378:metabolism* / Q000633:toxicity; D045304:Cytochromes c / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005420:Flavoproteins / Q000378:metabolism; D005964:Glucosyltransferases / Q000037:antagonists & inhibitors / Q000378:metabolism; D000074923:High-Temperature Requirement A Serine Peptidase 2; D020935:MAP Kinase Signaling System / Q000187:drug effects / Q000502:physiology*; D008565:Membrane Proteins / Q000378:metabolism; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D024101:Mitochondrial Proteins / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000037:antagonists & inhibitors / Q000378:metabolism; D009410:Nerve Degeneration / Q000139:chemically induced / Q000378:metabolism* / Q000503:physiopathology; D009419:Nerve Tissue Proteins / Q000378:metabolism; D019636:Neurodegenerative Diseases / Q000378:metabolism / Q000503:physiopathology; D009474:Neurons / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D051381:Rats; D012697:Serine Endopeptidases / Q000378:metabolism; D048051:p38 Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism
chemical_list: C494831:Aifm1 protein, rat; D051033:Apoptosis Inducing Factor; D051017:Apoptosis Regulatory Proteins; D002352:Carrier Proteins; D061945:Caspase Inhibitors; D002518:Ceramides; C489013:DIABLO protein, rat; D004791:Enzyme Inhibitors; D005420:Flavoproteins; D008565:Membrane Proteins; D024101:Mitochondrial Proteins; D009419:Nerve Tissue Proteins; D045304:Cytochromes c; D005964:Glucosyltransferases; C023246:ceramide glucosyltransferase; D048052:Mitogen-Activated Protein Kinase 3; D048051:p38 Mitogen-Activated Protein Kinases; D012697:Serine Endopeptidases; D000074923:High-Temperature Requirement A Serine Peptidase 2; C505410:Casp3 protein, rat; D053148:Caspase 3; D020169:Caspases