The role of DNA polymerase ζ in translesion synthesis across bulky DNA adducts and cross-links in human cells

Publication date: Available online 25 August 2016 Source:Mutation Research/Fundamental and Molecular Mechanisms of Mutagenesis Author(s): Tetsuya Suzuki, Petr Grúz, Masamitsu Honma, Noritaka Adachi, Takehiko Nohmi Translesion DNA synthesis (TLS) is a cellular defense mechanisms against genotoxins. Defects or mutations in specialized DNA polymerases (Pols) involved in TLS are believed to result in hypersensitivity to various genotoxic stresses. Here, DNA polymerase ζ (Pol ζ)-deficient (KO: knockout) and Pol ζ catalytically dead (CD) human cells were established and their sensitivity towards cytotoxic activities of various genotoxins was examined. The CD cells were engineered by altering the DNA sequence encoding two amino acids essential for the catalytic activity of Pol ζ, i.e., D2781 and D2783, to alanines. Both Pol ζ KO and CD cells displayed a prolonged cell cycle and higher incidence of micronuclei formation than the wild-type (WT) cells in the absence of exogenous genotoxic treatments, and the order of abnormality was CD>KO>WT cells. Both KO and CD cells exhibited higher sensitivity towards the killing effects of benzo[a]pyrene diol epoxide, mitomycin C, potassium bromate, N-methyl-N′-nitro-N-nitrosoguanidine, and ultraviolet C irradiation than WT cells, and there were no differences between the sensitivities of KO and CD cells. Interestingly, neither KO nor CD cells were sensitive to the cytotoxic effects of hydrogen peroxide. Since KO and C...

Source: Mutation Research Fundamental and Molecular Mechanisms of Mutagenesis - August 24, 2016 Category: Cytology Source Type: research