Role of DNA polymerase θ in tolerance of endogenous and exogenous DNA damage in mouse B cells
Role of DNA polymerase θ in tolerance of endogenous and exogenous DNA damage in mouse B cells
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DOI：
10.1111/j.1365-2443.2006.00922.x
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发表时间：
2006-02-01
期刊：
影响因子：
2.1
通讯作者：
O-Wang, J
中科院分区：
文献类型：
--
作者：
Ukai, A;Maruyama, T;O-Wang, J
DNA聚合酶theta(Pol Theta)是一种含有固有解旋酶结构域的A家族聚合酶。为了研究Pol theta在哺乳动物细胞中的功能，我们通过靶向删除包含催化天冬氨酸残基的聚合酶核心域，使其在CH12小鼠B淋巴瘤细胞中的聚合酶活性失活。与亲本CH12细胞相比，缺乏Pol theta聚合酶活性的突变细胞表现出轻微的生长速度减慢，伴随着细胞自发死亡的增加。此外，突变细胞对丝裂霉素C、顺铂、依托泊苷、伽玛射线和紫外线的敏感性也有所提高。有趣的是，突变细胞对烷化剂甲烷磺酸甲酯(MMS)比亲本细胞更敏感。这种相对于WT细胞的MMS敏感性在甲氧胺的存在下持续存在，甲氧胺是主要碱基切除修复(BER)途径的抑制剂，这表明Pol theta通过似乎不同于BER的机制参与了MMS的耐受。这些结果揭示了Pol theta在防止自发性细胞死亡中的重要作用，以及对哺乳动物淋巴细胞中DNA链间交联和双链断裂以及UV加合物和烷基化损伤的耐受。
DNA polymerase theta (Pol theta) is a family A polymerase that contains an intrinsic helicase domain. To investigate the function of Pol theta 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 Pol theta 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 Pol theta is involved in tolerance of MMS through a mechanism that appears to be different from BER. These results reveal an important role for Pol theta 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.