Mouse DNA polymerase kappa has a functional role in the repair of DNA strand breaks

Area of Science:

• Molecular Biology
• Genetics
• Biochemistry

Background:

• Y-family DNA polymerases are crucial for translesion DNA synthesis (TLS) to overcome DNA damage during replication.
• Emerging evidence suggests specialized TLS polymerases have roles beyond TLS in DNA metabolism.
• Mouse polymerase kappa (Polκ) is a Y-family DNA polymerase with known roles in DNA repair.

Purpose of the Study:

• To investigate the role of mouse polymerase kappa (Polκ) in DNA damage response and repair.
• To determine the mechanisms of Polκ recruitment to sites of DNA damage.
• To assess the function of Polκ in cellular response to oxidative stress and DNA strand break repair.

Main Methods:

• Laser-induced DNA damage in mouse cells.
• Analysis of Polκ localization and recruitment dynamics.
• Assessment of Polκ recruitment in MSH2-deficient and Rad18-depleted cells.
• Sensitivity assays of Polκ-deficient mouse embryo fibroblasts to hydrogen peroxide (H2O2).
• Evaluation of DNA single- and double-strand break repair in Polκ-deficient cells.

Main Results:

• Mouse Polκ accumulates at laser-induced DNA damage sites in vivo, similar to other TLS polymerases.
• Polκ recruitment is mediated by its C-terminus, involving PCNA-interacting peptide, ubiquitin zinc finger motif 2, and nuclear localization signal.
• Recruitment of Polκ to damage sites is reduced in MSH2-deficient and Rad18-depleted cells.
• Polκ-deficient mouse embryo fibroblasts exhibit hypersensitivity to H2O2 and defects in single- and double-strand break repair.

Conclusions:

• Mouse Polκ plays a significant role in DNA repair pathways beyond its canonical TLS function.
• Polκ's recruitment to DNA damage sites is regulated by specific protein motifs and cellular factors.
• Polκ is implicated in the repair of DNA strand breaks, particularly following oxidative stress.