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Strategies for Tracking Anastasis, A Cell Survival Phenomenon that Reverses Apoptosis
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Mitochondrial pathway of apoptosis is ancestral in metazoans

Cheryl E Bender1, Patrick Fitzgerald, Stephen W G Tait

  • 1Apoptosis and Cell Death Program, Burnham Institute for Medical Research, La Jolla, CA 92037, USA.

Proceedings of the National Academy of Sciences of the United States of America
|March 15, 2012
PubMed

Insights

The study reveals that the mitochondrial apoptosis pathway, involving mitochondrial outer membrane permeabilization (MOMP), is present in planaria, an invertebrate. This finding suggests this cell death mechanism predates vertebrates but was lost in some lineages.

Area of Science:

  • Cell Biology
  • Evolutionary Biology
  • Developmental Biology

Background:

  • The mitochondrial pathway of apoptosis is crucial for cell death in vertebrates.
  • This pathway involves mitochondrial outer membrane permeabilization (MOMP), cytochrome c release, and caspase activation.
  • The presence of this pathway in invertebrates has been debated due to conserved but uncharacterized components.

Purpose of the Study:

  • To investigate the existence and function of the mitochondrial apoptosis pathway in invertebrates.
  • To determine if planaria utilize MOMP and cytochrome c for apoptosis.
  • To explore the evolutionary origins of the mitochondrial apoptosis pathway.

Main Methods:

  • Apoptosis assays in planaria.
  • Analysis of cytochrome c's role in caspase activation using cytosolic extracts.
  • Functional studies of planarian Bcl-2 proteins in yeast and mammalian cells.
  • Survey of cytochrome c's effect on caspase activation across diverse organisms.

Main Results:

  • Apoptosis in planaria is associated with MOMP and cytochrome c-triggered caspase activation.
  • Planarian Bcl-2 proteins can regulate MOMP in heterologous systems.
  • Cytochrome c triggers caspase activation in cytosolic extracts from invertebrate deuterostomes.

Conclusions:

  • The mitochondrial apoptosis pathway likely predates the emergence of vertebrates.
  • This pathway may have been lost in certain invertebrate lineages, such as nematodes.
  • The findings provide evidence for the ancient evolutionary history of programmed cell death mechanisms.

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