Kinetics of Smac/DIABLO release from mitochondria during apoptosis of MCF-7 breast cancer cells

Magdalena Gorka, Michal Marek Godlewski, Barbara Gajkowska, Urszula Wojewodzka, Tomasz Motyl

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    22 Citations (Scopus)


    Smac/DIABLO, a pro-apoptotic protein released from mitochondrial intermembrane space during apoptosis, promotes caspase activation by IAPs neutralization. The kinetics and molecular mechanism of Smac/DIABLO release from mitochondria has remained obscure. Homeostatic confocal microscopy, for the first time, showed the precise kinetics of Smac/DIABLO release from mitochondria during CPT-induced apoptosis in living MCF-7 cells. The time pattern of Smac/DIABLO escape from mitochondria comprised two phases: the initial phase of gradual protein release, followed by the second phase of plateau, appearing after 24 min of cell exposure to the drug. A similar pattern was observed during oxidative stress. The dynamics of Smac/DIABLO redistribution was confirmed by different methods: traditional confocal microscopy, immunoelectron microscopy and laser scanning cytometry. The inhibition of m-calpain prevented Smac/DIABLO release from mitochondria, which confirmed the involvement of Bax in the process. Acquired results indicate that CPT treatment triggers Bax-dependent release of Smac/DIABLO from mitochondria simultaneously with the efflux of cytochrome c.

    Original languageEnglish
    Pages (from-to)741-754
    Number of pages14
    JournalCell Biology International
    Issue number11
    Publication statusPublished - Nov 2004


    • Apoptosis
    • Bax
    • Homeostatic confocal microscopy
    • Smac/DIABLO


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