VDAC-dependent permeabilization of the outer mitochondrial membrane by superoxide induces rapid and massive cytochrome c release

Madesh Muniswamy, György Hajnóczky

Research output: Contribution to journalArticle

377 Citations (Scopus)

Abstract

Enhanced formation of reactive oxygen species (ROS), superoxide (O2·-), and hydrogen peroxide (H2O2) may result in either apoptosis or other forms of cell death. Here, we studied the mechanisms underlying activation of the apoptotic machinery by ROS. Exposure of permeabilized HepG2 cells to O2·- elicited rapid and massive cytochrome c release (CCR), whereas H2O2 failed to induce any release. Both O2·- and H2O2 promoted activation of the mitochondrial permeability transition pore by Ca2+, but Ca2+-dependent pore opening was not required for O2·--induced CCR. Furthermore, O2·- alone evoked CCR without damage of the inner mitochondrial membrane barrier, as mitochondrial membrane potential was sustained in the presence of extramitochondrial ATP. Strikingly, pretreatment of the cells with drugs or an antibody, which block the voltage-dependent anion channel (VDAC), prevented O2·--induced CCR. Furthermore, VDAC-reconstituted liposomes permeated cytochrome c after O2·- exposure, and this release was prevented by VDAC blocker. The proapoptotic protein, Bak, was not detected in HepG2 cells and O2·--induced CCR did not depend on Bax translocation to mitochondria. O2·--induced CCR was followed by caspase activation and execution of apoptosis. Thus, O2·- triggers apoptosis via VDAC-dependent permeabilization of the mitochondrial outer membrane without apparent contribution of proapoptotic Bcl-2 family proteins.

Original languageEnglish (US)
Pages (from-to)1003-1015
Number of pages13
JournalJournal of Cell Biology
Volume155
Issue number6
DOIs
StatePublished - Dec 10 2001
Externally publishedYes

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Voltage-Dependent Anion Channels
Mitochondrial Membranes
Cytochromes c
Superoxides
Hep G2 Cells
Apoptosis
Reactive Oxygen Species
bcl-2 Homologous Antagonist-Killer Protein
Mitochondrial Membrane Potential
Caspases
Liposomes
Hydrogen Peroxide
Mitochondria
Cell Death
Adenosine Triphosphate
Antibodies

Keywords

  • Cytochrome c, apoptosis
  • Mitochondria
  • Superoxide anion
  • VDAC

ASJC Scopus subject areas

  • Cell Biology

Cite this

VDAC-dependent permeabilization of the outer mitochondrial membrane by superoxide induces rapid and massive cytochrome c release. / Muniswamy, Madesh; Hajnóczky, György.

In: Journal of Cell Biology, Vol. 155, No. 6, 10.12.2001, p. 1003-1015.

Research output: Contribution to journalArticle

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