title: [The mechanisms of the release of cytochrome C from mitochondria revealed by proteomics analysis].
abstract: Mitochondrial permeability transition (PT) is the phenomenon in which the mitochondrial inner membrane becomes permeable to various solutes and ions. When PT is induced by Ca(2+), cytochrome c is released from mitochondria into the cytosol where it then triggers subsequent steps of programmed cell death, apoptosis. Thus, the proteins that regulate PT and cytochrome c release could become druggable targets for various diseases. However, the mechanisms of PT and the release of cytochrome c have not yet been revealed. We previously showed that valinomycin, a potassium selective ionophore, also caused release of cytochrome c from mitochondria without inducing PT. This result indicates that cytochrome c could be released from mitochondria with or without induction of PT. In this study, to understand the difference of effects of valinomycin and Ca(2+) on mitochondria, we examined what protein species are released from valinomycin- and Ca(2+)-treated mitochondria by LC-MS/MS. As a result, only the proteins located in the intermembrane space were found to be released from valinomycin-treated mitochondria, while those in both the intermembrane space and in the matrix were released from Ca(2+)-treated mitochondria. Furthermore, the protein releases by each reagent occurred not selectively but in a concentration-dependent manner. Based on these results, the permeabilization effects of Ca(2+) and valinomycin on the inner and outer mitochondrial membranes are discussed.
authors.affiliation: Institute for Genome Research, University of Tokushima, Kuramoto-cho, Tokushima, Japan. tyamamo@genome.tokushima-u.ac.jp
authors.forename: Takenori
authors.initials: T
authors.lastname: Yamamoto
authors.forename: Akiko
authors.initials: A
authors.lastname: Yamada
authors.forename: Yuya
authors.initials: Y
authors.lastname: Yoshimura
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Terada
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Shinohara
mesh_terms: D000818:Animals; D002118:Calcium / Q000494:pharmacology; D045304:Cytochromes c / Q000378:metabolism*; D008928:Mitochondria / Q000378:metabolism*; D033681:Mitochondrial Membrane Transport Proteins / Q000502:physiology; D051336:Mitochondrial Membranes / Q000187:drug effects; D000083162:Mitochondrial Permeability Transition Pore; D040901:Proteomics; D051381:Rats; D014634:Valinomycin / Q000494:pharmacology
chemical_list: D033681:Mitochondrial Membrane Transport Proteins; D000083162:Mitochondrial Permeability Transition Pore; D014634:Valinomycin; D045304:Cytochromes c; D002118:Calcium