Symbiotic Origin of Apoptosis

Area of Science:

• Evolutionary Biology
• Cell Biology
• Biochemistry

Background:

• Symbiosis, especially mitochondrial domestication, is fundamental to eukaryotic evolution.
• Mitochondria, endosymbiotic bacteria, perform energy production via oxidative respiration and regulate programmed cell death (apoptosis).
• Apoptosis is essential for multicellularity and exists across diverse eukaryotic lineages.

Purpose of the Study:

• To investigate the evolutionary origins of apoptosis.
• To explore the relationship between apoptosis and mitochondrial function.
• To understand the role of apoptosis in the establishment of multicellularity.

Main Methods:

• Phylogenetic analysis of apoptotic factors.
• Comparative studies of cell death mechanisms in unicellular and multicellular eukaryotes.
• Investigating the co-evolution of aerobic respiration and apoptosis.

Main Results:

• Phylogenetic studies suggest apoptosis evolved from toxins produced during an evolutionary arms race between early eukaryotes and protomitochondria.
• Aerobic respiration and apoptosis appear to be co-evolved and functionally linked.
• Perturbations in apoptosis correlate with disruptions in oxidative respiration, as observed in yeast studies.

Conclusions:

• Mitochondrial domestication was a pivotal event in the evolution of apoptosis.
• Apoptosis likely arose as a defense mechanism, with its factors evolving from protomitochondrial toxins.
• The intricate link between respiration and apoptosis has implications for understanding diseases like cancer.