title: Protective role of mitochondrial unsaturated lipids on the preservation of the apoptotic ability of cytochrome C exposed to singlet oxygen.
abstract: Cytochrome c-mediated apoptosis in cells submitted to photodynamic therapy raises the question about the ability of photodynamically oxidized cytochrome c (cytc405) to trigger apoptosis as well as the effect of membranes on protein photo-oxidation. Cytochrome c was submitted to irradiation in the presence of MB+ in phosphate buffer and in the presence of four types of phosphatidylcholine/phosphatidylethanolamine/cardiolipin (PCPECL) liposomes (50/30/20%): totally saturated lipids (tsPCPECL), totally unsaturated lipids (tuPCPECL), partially unsaturated (80%) lipids, with unsaturation in the PC and PE content (puPCPECL80), and partially unsaturated (20%) lipids, with unsaturation in the CL content (puPCPECL20). Cytc405 was formed by irradiation in buffered water and in tsPCPECL and puPCPECL20 liposomes. In the presence of tuPCPECL and puPCPECL80, cytochrome c was protected from photodynamic damage (lipid-protected cytochrome c). In CL liposomes, 25% unsaturated lipids were enough to protect cytochrome c. The presence of unsaturated lipids, in amounts varying according to the liposome composition, are crucial to protect cytochrome c. Interesting findings corroborating the unsaturated lipids as cytochrome c protectors were obtained from the analysis of the lipid-oxidized derivatives of the samples. Native cytochrome c, lipid-protected cytochrome c, and cytc405 were microinjected in aortic smooth muscle cells. Apoptosis, characterized by nucleus blebbing and chromatin condensation, was detected in cells loaded with native and lipid protected cytochrome c but not in cells loaded with cytc405. These results suggest that photodynamic therapy-promoted apoptosis is feasible due to the protective effect of the mitochondrial lipids on the cytochrome c structure and function.
authors.affiliation: Centro Interdisciplinar de Investigação Bioquímica Universidade de Mogi das Cruzes, Prédio I, Sala 1S-15, Mogi das Cruzes 08780-911, São Paulo, Brazil.
authors.forename: Tiago
authors.initials: T
authors.lastname: Rodrigues
authors.forename: Lucimar P
authors.initials: LP
authors.lastname: de França
authors.forename: Cintia
authors.initials: C
authors.lastname: Kawai
authors.forename: Priscila A
authors.initials: PA
authors.lastname: de Faria
authors.forename: Katia C U
authors.initials: KC
authors.lastname: Mugnol
authors.forename: Fernanda M
authors.initials: FM
authors.lastname: Braga
authors.forename: Ivarne L S
authors.initials: IL
authors.lastname: Tersariol
authors.forename: Soraya S
authors.initials: SS
authors.lastname: Smaili
authors.forename: Iseli L
authors.initials: IL
authors.lastname: Nantes
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000528:radiation effects; D002478:Cells, Cultured; D002843:Chromatin / Q000737:chemistry / Q000378:metabolism; D003574:Cytochrome c Group / Q000737:chemistry* / Q000378:metabolism / Q000494:pharmacology; D005231:Fatty Acids, Unsaturated / Q000737:chemistry* / Q000378:metabolism / Q000494:pharmacology; D006736:Horses; D006801:Humans; D015227:Lipid Peroxidation / Q000528:radiation effects; D008081:Liposomes / Q000737:chemistry* / Q000378:metabolism / Q000494:pharmacology; D008929:Mitochondria, Heart / Q000737:chemistry* / Q000378:metabolism / Q000528:radiation effects; D032389:Myocytes, Smooth Muscle / Q000166:cytology / Q000378:metabolism*; D010084:Oxidation-Reduction / Q000528:radiation effects; D010778:Photochemotherapy; D011817:Rabbits; D026082:Singlet Oxygen / Q000737:chemistry* / Q000378:metabolism; D013329:Structure-Activity Relationship
chemical_list: D002843:Chromatin; D003574:Cytochrome c Group; D005231:Fatty Acids, Unsaturated; D008081:Liposomes; D026082:Singlet Oxygen; C017165:cytochrome c(3)