Role of DNA polymerase theta in tolerance of endogenous and exogenous DNA damage in mouse B cells.
DNA polymerase theta (Poltheta) is a family A polymerase that contains an intrinsic helicase domain. To investigate the function of Poltheta in mammalian cells, we have inactivated its polymerase activity in CH12 mouse B lymphoma cells by targeted deletion of the polymerase core domain that contains the catalytic aspartic acid residue. Compared to parental CH12 cells, mutant cells devoid of Poltheta polymerase activity exhibited a slightly reduced growth rate, accompanied by increased spontaneous cell death. In addition, mutant cells showed elevated sensitivity to mitomycin C, cisplatin, etoposide, gamma-irradiation and ultraviolet (UV) radiation. Interestingly, mutant cells were more sensitive to the alkylating agent methyl methanesulfonate (MMS) than parental cells. This elevated MMS sensitivity relative to WT cells persisted in the presence of methoxyamine, an inhibitor of the major base excision repair (BER) pathway, suggesting that Poltheta is involved in tolerance of MMS through a mechanism that appears to be different from BER. These results reveal an important role for Poltheta in preventing spontaneous cell death and in tolerance of not only DNA interstrand cross-links and double strand breaks but also UV adducts and alkylation damage in mammalian lymphocytes.
Ukai
Akiko
A
Laboratory for Antigen Receptor Diversity, Research Center for Allergy and Immunology, RIKEN Yokohama Institute, Yokohama 230-0045, Japan.
Maruyama
Takako
T
Mochizuki
Shigenobu
S
Ouchida
Rika
R
Masuda
Keiji
K
Kawamura
Kiyoko
K
Tagawa
Masatoshi
M
Kinoshita
Kazuo
K
Sakamoto
Akemi
A
Tokuhisa
Takeshi
T
O-Wang
Jiyang
J
D000818:Animals; D001402:B-Lymphocytes / Q000201:enzymology* / Q000378:metabolism* / Q000473:pathology; D016923:Cell Death; D004249:DNA Damage / Q000187:drug effects; D004260:DNA Repair / Q000187:drug effects; D004259:DNA-Directed DNA Polymerase / Q000737:chemistry / Q000172:deficiency / Q000378:metabolism*; D005091:Exons / Q000235:genetics; D016678:Genome / Q000235:genetics; D008741:Methyl Methanesulfonate / Q000494:pharmacology; D051379:Mice; D009154:Mutation / Q000235:genetics; D014407:Tumor Cells, Cultured; D000097462:DNA Polymerase theta
D004259:DNA-Directed DNA Polymerase; D008741:Methyl Methanesulfonate; D000097462:DNA Polymerase theta