title: Absence of correlation between oxysterol accumulation in lipid raft microdomains, calcium increase, and apoptosis induction on 158N murine oligodendrocytes.
abstract: There is some evidence that oxidized derivatives of cholesterol, 7-ketocholesterol (7KC) and 7β-hydroxycholesterol (7βOHC), are increased in the plasma of patients with neurodegenerative diseases associated with demyelinization of the central nervous system (CNS). It was therefore of interest to investigate the effects of these oxysterols on oligodendrocytes, the myelin-forming cells in the CNS. To this end, 158N murine oligodendrocytes were treated with 7KC or 7βOHC inducing an apoptotic mode of cell death characterized by condensation/fragmentation of the nuclei, dephosphorylation of Akt and GSK3, mitochondrial depolarization involving Mcl-1, and caspase-3 activation. In contrast, under treatment with 27-hydroxycholesterol (27OHC), no cell death was observed. When the cells were stained with Fura-2, no significant Ca(2+) rise was found with the different oxysterols, whereas strong signals were detected with ionomycin used as positive control. At concentrations which induced apoptosis, 7KC but not 7βOHC accumulated in lipid rafts. Although not cytotoxic, 27OHC was mainly detected in lipid rafts. It is noteworthy that α-tocopherol (but not ellagic acid and resveratrol) was able to counteract 7KC- and 7βOHC-induced apoptosis and to decrease the accumulation of 7KC and 27OHC in lipid rafts. Thus, in 158N cells, the ability of oxysterols to trigger a mode of cell death by apoptosis involving GSK-3 and caspase-3 activation is independent of the increase in the Ca(2+) level and of their accumulation in lipid raft microdomains.
authors.affiliation: Université de Bourgogne, Equipe 'Biochimie du peroxysome, inflammation et métabolisme lipidique' EA 7270/INSERM, Dijon, France.
authors.forename: Kévin
authors.initials: K
authors.lastname: Ragot
authors.forename: John J
authors.initials: JJ
authors.lastname: Mackrill
authors.forename: Amira
authors.initials: A
authors.lastname: Zarrouk
authors.forename: Thomas
authors.initials: T
authors.lastname: Nury
authors.forename: Virginie
authors.initials: V
authors.lastname: Aires
authors.forename: Agnès
authors.initials: A
authors.lastname: Jacquin
authors.forename: Anne
authors.initials: A
authors.lastname: Athias
authors.forename: Jean-Paul
authors.initials: JP
authors.lastname: Pais de Barros
authors.forename: Anne
authors.initials: A
authors.lastname: Véjux
authors.forename: Jean-Marc
authors.initials: JM
authors.lastname: Riedinger
authors.forename: Dominique
authors.initials: D
authors.lastname: Delmas
authors.forename: Gérard
authors.initials: G
authors.lastname: Lizard
mesh_terms: D000818:Animals; D017209:Apoptosis; D002118:Calcium / Q000378:metabolism*; D002460:Cell Line; D049109:Cell Proliferation; D002470:Cell Survival; D038362:Glycogen Synthase Kinase 3 / Q000378:metabolism; D006888:Hydroxycholesterols / Q000378:metabolism / Q000494:pharmacology; D007653:Ketocholesterols / Q000378:metabolism / Q000494:pharmacology; D021962:Membrane Microdomains / Q000187:drug effects / Q000378:metabolism*; D051379:Mice; D064549:Myeloid Cell Leukemia Sequence 1 Protein; D009836:Oligodendroglia / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D013261:Sterols / Q000378:metabolism*; D024502:alpha-Tocopherol / Q000494:pharmacology
chemical_list: D006888:Hydroxycholesterols; D007653:Ketocholesterols; C579094:Mcl1 protein, mouse; D064549:Myeloid Cell Leukemia Sequence 1 Protein; D019253:Proto-Oncogene Proteins c-bcl-2; D013261:Sterols; C011724:cholest-5-en-3 beta,7 alpha-diol; C076996:27-hydroxycholesterol; D051057:Proto-Oncogene Proteins c-akt; D038362:Glycogen Synthase Kinase 3; D024502:alpha-Tocopherol; C003001:7-ketocholesterol; D002118:Calcium