Coevolution of non-homologous end joining efficiency and encephalization

Area of Science:

• Genetics
• Evolutionary Biology
• Molecular Biology

Background:

• DNA double-strand breaks (DSB) represent a severe form of DNA damage.
• Non-homologous end-joining (NHEJ) and homologous recombination (HR) are the primary repair pathways for DSBs.
• Primates, notably humans, exhibit enhanced NHEJ efficiency and significant encephalization.

Purpose of the Study:

• To investigate the correlation between gene expression of DNA repair pathways (NHEJ and HR) and species-specific traits.
• To explore relationships between NHEJ/HR gene expression and encephalization, body mass, and longevity across mammals.
• To understand the evolutionary interplay between DNA repair mechanisms and primate-specific characteristics.

Main Methods:

• Utilized existing transcriptome data from 34 mammalian species.
• Analyzed gene expression patterns for NHEJ and HR pathways.
• Correlated gene expression levels with data on encephalization, body mass, and longevity.

Main Results:

• Homologous recombination (HR) gene expression showed a stronger correlation with longevity.
• Non-homologous end-joining (NHEJ) gene expression demonstrated a robust correlation with encephalization.
• NHEJ gene expression was more strongly associated with encephalization than with body mass or longevity.

Conclusions:

• NHEJ efficiency appears to be linked with the evolutionary expansion of the brain (encephalization).
• The brain, composed of postmitotic cells, relies heavily on NHEJ for DSB repair.
• These findings suggest that NHEJ efficiency and encephalization coevolved in the primate lineage.