Post-replicative base excision repair in replication foci

Area of Science:

• Molecular Biology
• DNA Repair Mechanisms
• Cellular Biochemistry

Background:

• Base excision repair (BER) is a critical pathway for maintaining genomic stability.
• BER can be completed via alternative routes, some involving DNA replication proteins.
• Uracil incorporation into DNA can arise from deamination of cytosine or misincorporation of dUTP.

Purpose of the Study:

• To investigate the role of uracil-DNA glycosylase (UNG2) in DNA replication and repair.
• To determine the interaction of UNG2 with key replication factors like PCNA and RPA.
• To elucidate the formation of a base excision repair complex at the replication fork.

Main Methods:

• Monitoring UNG2 expression and localization during S phase using BrdUrd incorporation.
• Assessing uracil removal in isolated nuclei using neutralizing antibodies against UNG2.
• Investigating molecular interactions between UNG2, PCNA, and RPA via two-hybrid assays, peptide SPOT assays, and ELISAs.

Main Results:

• UNG2 levels increase during S phase and co-localize with replication foci.
• UNG2 is responsible for the rapid removal of uracil from newly synthesized DNA.
• Direct molecular interactions were confirmed between UNG2, PCNA, and RPA.

Conclusions:

• UNG2 plays a significant role in the rapid post-replicative removal of incorporated uracil.
• A functional base excision repair complex comprising UNG2, RPA, and PCNA forms near the replication fork.
• This BER complex likely contributes to maintaining genome integrity during DNA replication.