title: Prevention of 7-ketocholesterol-induced mitochondrial damage and cell death by calmodulin inhibition.
abstract: Oxysterols such as 7-ketocholesterol and 25-hydroxycholesterol formed under enhanced oxidative stress in the brain are suggested to induce neuronal cell death. The present study investigated the effect of calmodulin antagonists (trifluoperazine, W-7 and calmidazolium) against the cytotoxicity of 7-ketocholesterol in relation to the mitochondria-mediated cell death process and oxidative stress. PC12 cells exposed to 7-ketocholesterol revealed nuclear damage, decrease in the mitochondrial transmembrane potential, cytosolic accumulation of cytochrome c, activation of caspase-3, increase in the formation of reactive oxygen species and depletion of GSH. N-Acetylcysteine, trolox, carboxy-PTIO and Mn-TBAP reduced the cytotoxic effect of 7-ketocholesterol. Calmodulin antagonists attenuated the 7-ketocholesterol-induced nuclear damage, formation of the mitochondrial permeability transition and cell viability loss in PC12 cells. The results suggest that calmodulin antagonists may prevent the 7-ketocholesterol-induced viability loss in PC12 cells by suppressing formation of the mitochondrial permeability transition, leading to the release of cytochrome c and subsequent activation of caspase-3. The effects seem to be ascribed to their depressant action on the formation of reactive oxygen species and depletion of GSH. The findings suggest that calmodulin inhibition may exhibit a protective effect against the neurotoxicity of 7-ketocholesterol.
authors.affiliation: Department of Neurology, Seoul Veterans Hospital, Seoul 134-791, South Korea.
authors.forename: Jeong Ho
authors.initials: JH
authors.lastname: Han
authors.forename: Yun Jeong
authors.initials: YJ
authors.lastname: Kim
authors.forename: Eun Sook
authors.initials: ES
authors.lastname: Han
authors.forename: Chung Soo
authors.initials: CS
authors.lastname: Lee
mesh_terms: D000818:Animals; D002147:Calmodulin / Q000378:metabolism*; D053148:Caspase 3 / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D045304:Cytochromes c / Q000378:metabolism; D053938:DNA Fragmentation / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005434:Flow Cytometry; D005978:Glutathione / Q000378:metabolism; D007653:Ketocholesterols / Q000494:pharmacology*; D008928:Mitochondria / Q000187:drug effects*; D051336:Mitochondrial Membranes / Q000187:drug effects; D018384:Oxidative Stress / Q000187:drug effects; D016716:PC12 Cells / Q000187:drug effects; D010539:Permeability / Q000187:drug effects; D051381:Rats; D017382:Reactive Oxygen Species / Q000378:metabolism
chemical_list: D002147:Calmodulin; D004791:Enzyme Inhibitors; D007653:Ketocholesterols; D017382:Reactive Oxygen Species; D045304:Cytochromes c; D053148:Caspase 3; D005978:Glutathione; C003001:7-ketocholesterol