Participation of TDP1 in the repair of formaldehyde-induced DNA-protein cross-links in chicken DT40 cells.

Toshiaki Nakano,Minoru Takata,Mahmoud I Shoulkamy,Kouji Hirota,Tadayoshi Bessho,Shunichi Takeda,Shin-Ichiro Masunaga,Masataka Tsuda,Hiroshi Ide,Hiroyuki Sasanuma,Keizo Tano,Robert W Sobol

doi:10.1371/journal.pone.0234859

Abstract

Proteins are covalently trapped on DNA to form DNA-protein cross-links (DPCs) when cells are exposed to DNA-damaging agents. Aldehyde compounds produce common types of DPCs that contain proteins in an undisrupted DNA strand. Tyrosyl-DNA phosphodiesterase 1 (TDP1) repairs topoisomerase 1 (TOPO1) that is trapped at the 3’-end of DNA. In the present study, we examined the contribution of TDP1 to the repair of formaldehyde-induced DPCs using a reverse genetic strategy with chicken DT40 cells. The results obtained showed that cells deficient in TDP1 were sensitive to formaldehyde. The removal of formaldehyde-induced DPCs was slower in tdp1-deficient cells than in wild type cells. We also found that formaldehyde did not produce trapped TOPO1, indicating that trapped TOPO1 was not a primary cytotoxic DNA lesion that was generated by formaldehyde and repaired by TDP1. The formaldehyde treatment resulted in the accumulation of chromosomal breakages that were more prominent in tdp1-deficient cells than in wild type cells. Therefore, TDP1 plays a critical role in the repair of formaldehyde-induced DPCs that are distinct from trapped TOPO1.

Highlights

Proteins can be covalently cross-linked to DNA by endogenous and exogenous agents and form DNA-protein cross-links (DPCs) [1, 2]
When a DNA polymerase or replicative helicase is blocked by DPCs, DPCs can be repaired by SPRTN-mediated protein degradation followed by translesion DNA synthesis (TLS) and/or nucleotide excision repair (NER) [8,9,10,11,12]
Formaldehyde-induced DPCs resulted in chromosomal breakages that were more prominent in tdp1-deficient cells than in wild type cells

Summary

Introduction

Proteins can be covalently cross-linked to DNA by endogenous and exogenous agents and form DNA-protein cross-links (DPCs) [1, 2]. Recent studies reported that tdp1-deficient cells were sensitive to VP16 that trapped TOPO2-DNA reaction intermediates [38,39,40,41,42,43]. TDP1 removes trapped TOPO2 at 5’-end of DSBs. In the present study, we investigated the roles of TDP1 and TDP2 in the repair of formaldehyde-induced DNA damage in DT40 cell lines.

Results

Conclusion