Nuclear deadenylation/polyadenylation factors regulate 3' processing in response to DNA damage

Area of Science:

• Molecular Biology
• RNA Processing
• DNA Repair

Background:

• DNA damage transiently inhibits mRNA 3' end cleavage.
• Cleavage stimulation factor-50 (CstF-50) links transcription-coupled RNA processing and DNA repair.

Purpose of the Study:

• Investigate the interaction between CstF-50 and nuclear poly(A)-specific ribonuclease (PARN) under DNA-damaging conditions.
• Elucidate the role of CstF-50/PARN complex formation in regulating mRNA processing and gene expression following DNA damage.
• Determine the involvement of tumor suppressor BARD1 in CstF-50/PARN mediated regulation.

Main Methods:

• In vitro binding assays to detect CstF-50/PARN interaction.
• Analysis of UV-exposed cell extracts to confirm complex formation in vivo.
• Assays to measure 3' cleavage and deadenylation activity.
• Investigation of BARD1 and cap-binding protein-80 (CBP80) effects on PARN activity.

Main Results:

• CstF-50 interacts with PARN in vitro and in UV-exposed cell extracts.
• CstF-50/PARN complex formation inhibits 3' cleavage and activates deadenylation upon DNA damage.
• Tumor suppressor BARD1 strongly activates PARN-mediated deadenylation in the presence of CstF-50.
• The CstF-50/BARD1 complex can overcome CBP80-mediated inhibition of PARN activity.
• PARN and the CstF/BARD1 complex regulate endogenous transcripts under DNA-damaging conditions.

Conclusions:

• CstF-50 and PARN form a complex that regulates mRNA 3' end processing and deadenylation in response to DNA damage.
• The interplay between polyadenylation, deadenylation, and tumor suppressors like BARD1 contributes to controlling gene expression under cellular stress.
• This regulatory mechanism may prevent the expression of prematurely terminated transcripts, aiding cellular homeostasis.