Different DNA repair pathways support intact or truncated insertions by R2 retrotransposon protein.

Area of Science:

• Molecular Biology
• Genetics
• Genomics

Background:

• Non-LTR retrotransposons replicate via reverse transcription, but the mechanisms for stable DNA insertion remain unclear.
• Understanding these processes is crucial for insights into genome stability and engineering.

Purpose of the Study:

• To identify cellular factors governing site-specific transgene insertion by an R2 retrotransposon protein in the human genome.
• To elucidate the DNA repair pathways involved in cDNA insertion and second-strand synthesis.

Main Methods:

• Screening for cellular factors influencing R2 retrotransposon transgene synthesis.
• Analyzing insertion lengths and junction signatures resulting from different repair pathways.

Main Results:

• Discovered alternative repair pathways affecting insertion: ATR-dependent Polymerase θ end-joining, 53BP1-directed Shieldin/CST-Polα-primase fill-in synthesis, and CtIP-MRN-dependent strand annealing.
• Insertion lengths and junction signatures vary based on the specific repair mechanism utilized.

Conclusions:

• Cellular DNA repair pathways dictate the outcome of non-LTR retrotransposon cDNA insertion.
• These findings provide critical insights into retrotransposon mobility and offer potential for genome engineering applications.