Dicer prevents genome instability in response to replication stress

Area of Science:

• Molecular Biology
• Genetics
• Cell Biology

Background:

• Dicer is known for its role in microRNA biogenesis and RNA interference.
• Dicer is also implicated in the DNA damage response and repair of double-stranded DNA breaks (DSBs).
• The role of Dicer in preserving genome integrity during replication stress is not well understood.

Purpose of the Study:

• To investigate the role of Dicer in maintaining genome integrity under replication stress conditions.
• To examine the effect of Dicer inhibition on common fragile sites (CFSs) and DNA damage signaling.

Main Methods:

• Studied the effect of Dicer pathway inhibition on CFS expression and 53BP1 nuclear body accumulation under replication stress.
• Assessed the assembly of Fanconi anemia (FA) protein FANCD2 and TopBP1 into nuclear foci in Dicer/Drosha-deficient cells.
• Evaluated the activation of the S-phase checkpoint in response to replication stress.

Main Results:

• Dicer pathway inhibition increased CFS expression and 53BP1 nuclear body accumulation, indicating replication-associated DNA damage.
• Absence of Dicer or Drosha impaired FANCD2 and TopBP1 recruitment to stalled replication forks.
• Dicer deficiency resulted in defective S-phase checkpoint activation.

Conclusions:

• Dicer plays a critical role in preventing genomic instability following replication stress.
• Dicer facilitates the recruitment of essential proteins for replication fork stability and S-phase checkpoint activation.
• Proper Dicer function prevents cells from entering mitosis with under-replicated DNA.