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Detection of Mitochondria Membrane Potential to Study CLIC4 Knockdown-induced HN4 Cell Apoptosis In Vitro
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Mitochondrial apoptosis is amplified through gap junctions

Pablo M Peixoto1, Shin-Young Ryu, Dawn Pietkiewicz Pruzansky

  • 1Dept Basic Sciences, New York University College of Dentistry, New York, NY 10010, USA.

Biochemical and Biophysical Research Communications
|September 22, 2009
PubMed

Insights

Cell death can spread to nearby cells via the bystander effect. This study shows mitochondrial apoptosis triggers this effect through gap junctions, amplifying cell death signals.

Area of Science:

  • Cell Biology
  • Apoptosis Research
  • Molecular Mechanisms of Cell Death

Background:

  • The bystander effect describes how the death of one cell can induce death in neighboring cells.
  • Mitochondrial outer membrane permeabilization (MOMP) is a key event in apoptosis.
  • The role of mitochondrial apoptosis in mediating the bystander effect is not fully understood.

Purpose of the Study:

  • To investigate if mitochondrial apoptosis can induce a bystander effect.
  • To elucidate the pathway through which mitochondrial apoptosis mediates the bystander effect.
  • To explore the role of gap junctions in transmitting apoptosis signals.

Main Methods:

  • Microinjection of cytochrome c into osteoblasts to mimic mitochondrial apoptosis.
  • Exogenous expression of tBid to induce MOMP and cytochrome c release.
  • Inhibition of gap junction intercellular communication (GJIC).
  • Experiments using connexin-43 deficient osteoblasts.

Main Results:

  • Microinjection of cytochrome c induced apoptosis in both target and neighboring osteoblasts.
  • Inhibition of GJIC significantly suppressed the bystander effect.
  • Exogenous expression of tBid also triggered a bystander effect.
  • Cytochrome c microinjection in connexin-43 deficient cells only caused target cell apoptosis, confirming the role of gap junctions.

Conclusions:

  • Mitochondrial apoptosis, initiated by factors like cytochrome c release, generates a death signal.
  • This death signal is transmitted to neighboring cells via gap junctions, amplifying apoptosis.
  • The findings highlight the crucial role of gap junctions in the bystander effect mediated by mitochondrial apoptosis.
  • This mechanism has potential implications for developing novel therapeutic strategies targeting cell death.

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