BRCA1 binds TERRA RNA and suppresses R-Loop-based telomeric DNA damage

Area of Science:

• Molecular Biology
• Genetics
• Biochemistry

Background:

• R-loop structures are crucial for cellular processes but can induce genomic instability, especially at telomeres.
• Telomeres are susceptible to DNA secondary structures, and R-loops contribute to telomeric fragility.

Purpose of the Study:

• To investigate the role of BRCA1 in regulating R-loop structures at telomeres.
• To elucidate the mechanism by which BRCA1 interacts with TERRA RNA and telomere proteins.

Main Methods:

• Biochemical assays to confirm direct binding of BRCA1 to TERRA RNA and shelterin proteins.
• Cellular experiments to assess the impact of BRCA1 depletion and mutations on R-loop formation and telomere integrity.
• Analysis of R-loop-associated DNA damage and repair pathways.

Main Results:

• BRCA1 directly binds TERRA RNA via its N-terminal nuclear localization sequence and telomere-specific shelterin proteins.
• BRCA1 binding to TERRA promoters represses transcription, prevents R-loop associated damage, and promotes repair.
• BRCA1 depletion or mutations lead to increased TERRA R-loops, telomeric replication stress, and abnormalities.

Conclusions:

• BRCA1 plays a critical role in suppressing telomere-centered genome instability by regulating TERRA R-loops.
• Normal BRCA1-TERRA interaction is essential for maintaining telomere integrity and preventing DNA damage.
• Dysfunctional BRCA1 contributes to telomeric abnormalities through aberrant R-loop formation.