Pold4 subunit of replicative polymerase δ promotes fork slowing at broken templates.

Autor: Kojima K; Department of Chemistry, Graduate School of Science, Tokyo Metropolitan University, Minamiosawa 1-1, Hachioji-shi, Tokyo 192-0397, Japan., Ohkubo H; Department of Chemistry, Graduate School of Science, Tokyo Metropolitan University, Minamiosawa 1-1, Hachioji-shi, Tokyo 192-0397, Japan., Kawasumi R; Department of Chemistry, Graduate School of Science, Tokyo Metropolitan University, Minamiosawa 1-1, Hachioji-shi, Tokyo 192-0397, Japan., Hirota K; Department of Chemistry, Graduate School of Science, Tokyo Metropolitan University, Minamiosawa 1-1, Hachioji-shi, Tokyo 192-0397, Japan. Electronic address: khirota@tmu.ac.jp.
Jazyk: angličtina
Zdroj: DNA repair [DNA Repair (Amst)] 2024 Jul; Vol. 139, pp. 103688. Date of Electronic Publication: 2024 Apr 24.
DOI: 10.1016/j.dnarep.2024.103688
Abstrakt: Single-strand breaks (SSBs) are the most frequent type of lesion, and replication across such lesions leads to double-strand breaks (DSBs). DSBs that arise during replication are repaired by homologous recombination (HR) and are suppressed by fork reversal. Poly[ADP-ribose] polymerase I (PARP1) and the proofreading exonuclease activity of replicative polymerase ε (Polε) are required for fork reversal when leading strand replication encounters SSBs. However, the mechanism underlying fork reversal at the SSB during lagging-strand replication remains elusive. We here demonstrate that the Pold4 subunit of replicative polymerase δ (Polδ) plays a role in promoting fork reversal during lagging strand replication on a broken template. POLD4 -/- cells exhibited heightened sensitivity to camptothecin (CPT) but not to other DNA-damaging agents compared to wild-type cells. This selective CPT sensitivity in POLD4 -/- cells suggests that Pold4 suppresses DSBs during replication, as CPT induces significant SSBs during replication, which subsequently lead to DSBs. To explore the functional interactions among Pold4, Polε exonuclease, and PARP1 in DSB suppression, we generated PARP1 -/- , POLD4 -/- , Polε exonuclease-deficient POLE1 exo-/- , PARP1 -/- /POLD4 -/- , and POLD4 -/- /POLE1 exo-/- cells. These epistasis analyses showed that Pold4 is involved in the PARP1-Polε exonuclease-mediated fork reversal following CPT treatment. These results suggest that Pold4 aids in fork reversal when lagging strand replication stalls on a broken template. In conclusion, the Pold4 subunit of Polδ has roles in the PARP1-Polε exonuclease-mediated fork reversal, contributing to the suppression of DSBs.
Competing Interests: Declaration of Competing Interest We have no conflicts of interest to disclose.
(Copyright © 2024 Elsevier B.V. All rights reserved.)
Databáze: MEDLINE
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