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Confocal Imaging of Single Mitochondrial Superoxide Flashes in Intact Heart or In Vivo
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Confocal Imaging of Single Mitochondrial Superoxide Flashes in Intact Heart or In Vivo

Published on: November 5, 2013

Superoxide flashes: early mitochondrial signals for oxidative stress-induced apoptosis

Qi Ma1, Huaqiang Fang, Wei Shang

  • 1Joint Laboratory of Apoptosis and Cancer Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China.

The Journal of Biological Chemistry
|June 11, 2011
PubMed

Insights

Transient mitochondrial permeability transition (tMPT) and superoxide flashes act as early signals in oxidative stress-induced apoptosis. Targeting these mitochondrial events impacts cell death progression, revealing a novel signaling pathway.

Area of Science:

  • Cell Biology
  • Biochemistry
  • Apoptosis Research

Background:

  • Irreversible mitochondrial permeability transition (MPT) and cytochrome c release are established hallmarks of apoptotic cell death.
  • The functional significance of transient MPT (tMPT), characterized by flickering pore opening, remains largely unexplored in apoptosis.
  • Understanding early mitochondrial events is crucial for deciphering cell fate decisions during stress.

Purpose of the Study:

  • To investigate the role of transient mitochondrial permeability transition (tMPT) and associated superoxide flashes in oxidative stress-induced apoptosis.
  • To elucidate the signaling mechanisms by which tMPT/superoxide flashes influence apoptotic progression.
  • To determine if tMPT/superoxide flashes represent early, localized mitochondrial events preceding global cellular damage.

Main Methods:

  • Induction of apoptosis using selenite (ROS-dependent) and staurosporine (ROS-independent) in cell models.
  • Monitoring of tMPT/superoxide flash activity using specialized imaging techniques.
  • Manipulation of cyclophilin D expression and mitochondrial reactive oxygen species (ROS) levels.
  • Assessment of Bax translocation and cytochrome c release as markers of apoptosis.

Main Results:

  • Selenite, but not staurosporine, induced early and persistent tMPT/superoxide flash activity preceding mitochondrial fragmentation and global ROS increase.
  • These early flashes were independent of Bax translocation and cytochrome c release.
  • Targeting tMPT/superoxide flash activity (via cyclophilin D or ROS scavenging) significantly altered selenite-induced apoptosis.
  • tMPT/superoxide flashes were identified as a convergence point for pro- and anti-apoptotic protein regulation (cyclophilin D, Bcl-2).

Conclusions:

  • Transient mitochondrial permeability transition (tMPT) and associated superoxide flashes serve as critical early mitochondrial signals in oxidative stress-induced apoptosis.
  • These localized ROS signaling events play a decisive role in cell fate determination.
  • The findings highlight a novel mechanism of mitochondrial ROS signaling in regulating apoptosis.

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