title: 25-Hydroxycholesterol activates a cytochrome c release-mediated caspase cascade.
abstract: We have previously shown that 25-hydroxycholesterol (25-OHC) treated CHO-K1 cells could be used as a model to investigate the signaling pathway of apoptosis induced by oxidized LDL in vascular cells. In the present study, we examine the execution phase of the apoptotic pathway in CHO-K1 cell death induced by 25-OHC. Oxysterol-induced apoptosis in CHO-K1 was accompanied by caspase activation and was preceded by mitochondrial cytochrome c release. The addition of a competitive caspase-3 inhibitor, Ac-DEVD-CHO, prevented 25-OHC-induced apoptotic cell death. Furthermore, immunoblot analysis showed that 25-OHC treatment induced the degradation of poly(ADP-ribose) polymerase (PARP)-a substrate for caspase 3 and a key enzyme involved in genome surveillance and DNA repair. Thus, we could demonstrate in CHO-K1 cells that 25-OHC activates the apoptotic machinery through induction of the release of cytochrome c from mitochodria into the cytosol and activation of a typical caspase cascade.
authors.affiliation: Department of Biochemistry and Molecular Biology, James H. Quillen College of Medicine, Johnson City, Tennessee, 37614-0581, USA.
authors.forename: L
authors.initials: L
authors.lastname: Yang
authors.forename: M S
authors.initials: MS
authors.lastname: Sinensky
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D016466:CHO Cells; D053148:Caspase 3; D053181:Caspase 8; D053453:Caspase 9; D020169:Caspases / Q000378:metabolism*; D006224:Cricetinae; D003574:Cytochrome c Group / Q000032:analysis*; D004789:Enzyme Activation; D006888:Hydroxycholesterols / Q000494:pharmacology*; D007700:Kinetics; D008928:Mitochondria / Q000187:drug effects / Q000502:physiology; D009842:Oligopeptides / Q000494:pharmacology; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D015842:Serine Proteinase Inhibitors / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology
chemical_list: D003574:Cytochrome c Group; D006888:Hydroxycholesterols; D009842:Oligopeptides; D015842:Serine Proteinase Inhibitors; C099158:acetyl-aspartyl-glutamyl-valyl-aspartal; C007997:25-hydroxycholesterol; D011065:Poly(ADP-ribose) Polymerases; D053148:Caspase 3; D053181:Caspase 8; D053453:Caspase 9; D020169:Caspases