title: Mitochondrial phospholipid hydroperoxide glutathione peroxidase inhibits the release of cytochrome c from mitochondria by suppressing the peroxidation of cardiolipin in hypoglycaemia-induced apoptosis.
abstract: Cytochrome c (cyt. c) is a proapoptotic factor that binds preferentially to cardiolipin (CL), a mitochondrial lipid, but not to cardiolipin hydroperoxide (CL-OOH). Cyt. c that had bound to CL liposomes was liberated on peroxidation of the liposomes by a radical. The generation of CL-OOH in mitochondria occurred before the release of cyt. c in rat basophile leukaemia (RBL)2H3 cells that had been induced to undergo apoptosis by exposure to hypoglycaemia with 2-deoxyglucose (2DG). The amount of cyt. c bound to CL prepared from the mitochondria of 2DG-treated cells was lower than that of untreated cells. The release of cyt. c was completely suppressed when the production of CL-OOH in mitochondria was inhibited by the overexpression of mitochondrial phospholipid hydroperoxide glutathione peroxidase (PHGPx). The fluorescence from CL-labelling dye (10-N-nonyl Acridine Orange) decreased on the induction of apoptosis by 2DG. However, no decrease in fluorescence was observed in PHGPx-overexpressing cells. Cyt. c was released from mitochondria that had been isolated from control cells on peroxidation by t-butylhydroperoxide, but no similar liberation of cyt. c from mitochondria isolated from mitochondrial PHGPx-overexpressing cells was observed. These findings suggest that the generation of CL-OOH in mitochondria might be a primary event that triggers the release of cyt. c from mitochondria in the apoptotic process in which mitochondrial PHGPx participates as an anti-apoptotic factor by preventing the formation of CL-OOH.
authors.affiliation: School of Pharmaceutical Sciences, Kitasato University, 5-9-1 Shirokane, Minato-ku, Tokyo 108-8641, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Nomura
authors.forename: H
authors.initials: H
authors.lastname: Imai
authors.forename: T
authors.initials: T
authors.lastname: Koumura
authors.forename: T
authors.initials: T
authors.lastname: Kobayashi
authors.forename: Y
authors.initials: Y
authors.lastname: Nakagawa
mesh_terms: D000165:Acridine Orange / Q000031:analogs & derivatives* / Q000378:metabolism; D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D002308:Cardiolipins / Q000378:metabolism*; D003574:Cytochrome c Group / Q000378:metabolism*; D003847:Deoxyglucose / Q000494:pharmacology; D005453:Fluorescence; D005979:Glutathione Peroxidase / Q000235:genetics / Q000378:metabolism*; D007003:Hypoglycemia / Q000139:chemically induced / Q000378:metabolism / Q000473:pathology*; D007425:Intracellular Membranes / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism; D015227:Lipid Peroxidation / Q000187:drug effects; D008081:Liposomes / Q000737:chemistry / Q000378:metabolism; D008293:Malates / Q000494:pharmacology; D008928:Mitochondria / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism* / Q000473:pathology; D010084:Oxidation-Reduction; D000080662:Phospholipid Hydroperoxide Glutathione Peroxidase; D010743:Phospholipids / Q000378:metabolism; D011485:Protein Binding / Q000187:drug effects; D051381:Rats; D014407:Tumor Cells, Cultured; D020122:tert-Butylhydroperoxide / Q000494:pharmacology
chemical_list: D002308:Cardiolipins; D003574:Cytochrome c Group; D008081:Liposomes; D008293:Malates; D010743:Phospholipids; C056258:N(10)-nonylacridine orange; C058705:diethyl malate; D020122:tert-Butylhydroperoxide; D003847:Deoxyglucose; D000080662:Phospholipid Hydroperoxide Glutathione Peroxidase; D005979:Glutathione Peroxidase; D000165:Acridine Orange