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

Research output: Contribution to journalArticlepeer-review

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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