Absence of correlation between oxysterol accumulation in lipid raft microdomains, calcium increase, and apoptosis induction on 158N murine oligodendrocytes

作者：Ragot Kevin; Mackrill John J; Zarrouk Amira; Nury Thomas; Aires Virginie; Jacquin Agnes; Athias Anne; de Barros Jean Paul Pais; Vejux Anne; Riedinger Jean Marc; Delmas Dominique; Lizard Gerard^*

来源：Biochemical Pharmacology, 2013, 86(1): 67-79.

DOI：10.1016/j.bcp.2013.02.028

• Apoptosis
• Calcium
• Lipid rafts
• Oligodendrocytes
• 7-Ketocholesterol
• 7 beta-Hydroxycholesterol
• 27-Hydroxycholesterol
• alpha-Tocopherol

There is some evidence that oxidized derivatives of cholesterol, 7-ketocholesterol (71(C) and 7 beta-hydroxycholesterol (7 beta OHC), 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 7 beta OHC 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 Ca2+ 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 7 beta OHC accumulated in lipid rafts. Although not cytotoxic, 27OHC was mainly detected in lipid rafts. It is noteworthy that alpha-tocopherol (but not ellagic acid and resveratrol) was able to counteract 7KC- and 7 beta OHC-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 Ca2+ level and of their accumulation in lipid raft microdomains.

• 出版日期2013-7-1