Close encounters: Moving along bumps, breaks, and bubbles on expanded trinucleotide tracts

Area of Science:

• Genetics
• Molecular Biology
• Genomic Instability

Background:

• Triplet repeat expansions (TNRs) are the root cause of over 30 severe degenerative diseases.
• While major pathways for TNR expansion and the polymerases involved in gap-filling synthesis are understood, repair mechanisms remain complex.

Purpose of the Study:

• To review the complex interplay between DNA lesions, structural features, and replication/repair complexes in directing TNR repair pathway choice.
• To explore how polymerase properties influence replication and repair success when encountering GC-rich or abnormal DNA structures.

Main Methods:

• Literature review focusing on recent insights (last 3 years) into DNA replication and repair mechanisms at TNR sequences.
• Analysis of polymerase properties and their interactions with specific DNA structures.

Main Results:

• The choice of repair pathway is dictated by a complex interplay of lesion type, DNA structure, and the specific polymerase involved.
• Polymerase properties significantly influence the success of replication and repair at challenging GC-rich or structurally abnormal sequences.

Conclusions:

• Recent advances offer new insights into mechanisms protecting genome stability at TNR loci.
• Further understanding of polymerase choice and function is crucial for developing therapeutic strategies for TNR-associated diseases.