RNA transcripts serve as a template for double-strand break repair in human cells

Area of Science:

• Molecular Biology
• Genetics
• Genomics

Background:

• Double-strand breaks (DSBs) are critical DNA lesions that threaten genome stability.
• Canonical DNA repair pathways are generally considered RNA-independent.
• Emerging evidence indicates RNA can influence DNA repair, but direct templating remains unproven.

Purpose of the Study:

• To investigate whether transcript RNA can serve as a direct template for DSB repair in human cells.
• To identify molecular factors and genomic signatures associated with RNA-templated DSB repair (RT-DSBR).

Main Methods:

• Development of fluorescence and sequencing-based assays to detect RT-DSBR.
• CRISPR/Cas9-based genetic screening to identify factors promoting RT-DSBR.
• Analysis of cancer genome sequencing data to find RT-DSBR signatures.

Main Results:

• Demonstrated that RNA oligonucleotides and messenger RNA can function as templates for DSB repair.
• Identified DNA polymerase zeta (Polζ) as a key factor potentially acting as a reverse transcriptase in RT-DSBR.
• Discovered whole intron deletions in cancer genomes as a distinct signature of RT-DSBR.

Conclusions:

• RNA-templated DSB repair (RT-DSBR) is an alternative pathway for repairing DSBs in transcribed genes.
• RT-DSBR, potentially involving Polζ, can lead to specific mutagenic consequences, including intron deletions.
• This pathway offers new insights into genome maintenance and potential sources of genetic variation.