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Immunodetection of Outer Membrane Proteins by Flow Cytometry of Isolated Mitochondria
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Immunodetection of Outer Membrane Proteins by Flow Cytometry of Isolated Mitochondria

Published on: September 18, 2014

Confocal microscopy of the mitochondrial permeability transition in necrotic cell killing, apoptosis and autophagy

J J Lemasters1, T Qian, S P Elmore

  • 1Department of Cell Biology and Anatomy, University of North Carolina, Chapel Hill 27599-7090, USA.

Biofactors (Oxford, England)
|January 23, 1999
PubMed

Insights

The mitochondrial permeability transition (MPT) in living cells is visualized, revealing its role in cell death pathways like apoptosis. This process, triggered by various stressors, precedes mitochondrial autophagy.

Area of Science:

  • Cell Biology
  • Mitochondrial Dynamics
  • Cell Death Mechanisms

Background:

  • The mitochondrial permeability transition (MPT) is a critical event implicated in various cell death pathways, including apoptosis and necrosis.
  • Understanding the MPT's role is crucial for comprehending conditions like oxidative stress, ischemia/reperfusion injury, and drug toxicity.

Purpose of the Study:

  • To visualize the onset of cyclosporin-A-sensitive MPT in individual mitochondria within living cells.
  • To investigate the triggers and consequences of MPT in cellular death processes.

Main Methods:

  • Utilized laser scanning confocal microscopy to observe MPT in individual mitochondria in real-time within living cells.
  • Examined MPT during tumor necrosis factor alpha (TNF alpha)-induced apoptosis in hepatocytes.

Main Results:

  • Demonstrated that MPT can be visualized in individual mitochondria using confocal microscopy.
  • Identified pyridine nucleotide oxidation, reactive oxygen species generation, and altered mitochondrial Ca2+ and pH as promoters of MPT.
  • Observed spontaneous mitochondrial depolarization preceding lysosomal entry after nutrient deprivation, suggesting MPT precedes autophagy.

Conclusions:

  • The MPT is a key event initiating diverse cell death pathways, including apoptosis and necrosis.
  • MPT can be directly visualized in situ, providing insights into its dynamic role in cell fate.
  • A model is proposed where progressive MPT onset in multiple mitochondria drives cells towards autophagy, apoptosis, and necrosis.

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