Nuclear phosphorylated Dicer processes double-stranded RNA in response to DNA damage

Area of Science:

• Molecular Biology
• Cell Biology
• Genetics

Background:

• Dicer is crucial for cytoplasmic microRNA production in the RNA interference pathway.
• Emerging evidence suggests noncanonical Dicer roles in the DNA damage response (DDR).

Purpose of the Study:

• To investigate the role and regulation of Dicer in the DNA damage response.
• To elucidate the mechanism by which Dicer participates in DNA repair.

Main Methods:

• Western blotting to detect phosphorylated Dicer (p-Dicer) at specific residues (S1016, S1728, S1852).
• Immunofluorescence and cell fractionation to track p-Dicer localization in the nucleus and at DNA double-strand breaks.
• Dicer depletion studies using siRNA to assess impact on DNA damage and repair factor recruitment.
• Analysis of nuclear double-stranded (ds) RNA turnover.

Main Results:

• DNA damage induces phosphorylation of human Dicer at S1016, leading to nuclear accumulation and recruitment to DNA breaks.
• Further C-terminal phosphorylation (S1728, S1852) is required for the turnover of damage-induced nuclear dsRNA.
• Dicer depletion results in endogenous DNA damage and impaired recruitment of repair factors MDC1 and 53BP1, delaying the DDR.
• Nuclear Dicer accumulation upon DNA damage is conserved across mammalian species.

Conclusions:

• Dicer functions as a DNA damage-inducible phosphoswitch, regulating nuclear dsRNA processing.
• Phosphorylated Dicer (p-Dicer) plays a critical role in promoting DNA repair by processing nuclear dsRNA at damage sites.
• Dicer's involvement in the DDR highlights a novel mechanism linking RNA processing to genome stability.