Polκ protects mammalian cells against the lethal and mutagenic effects of benzo[a]pyrene
Polκ protects mammalian cells against the lethal and mutagenic effects of benzo[a]pyrene
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DOI：
10.1073/pnas.222377899
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发表时间：
2002-11-26
影响因子：
11.1
通讯作者：
Ohmori, H
中科院分区：
文献类型：
--
作者：
Ogi, T;Shinkai, Y;Ohmori, H
最近发现了几种低保真度DNA聚合酶，它们能够在体外DNA合成过程中绕过DNA损伤。然而，病变旁路的效率和准确性是聚合酶和病变特异性的。例如，体外研究表明，人类DNA聚合酶kappa（Polkappa）无法插入顺式-顺式胸腺嘧啶-胸腺嘧啶二聚体或顺铂加合物对面的碱基，但可以绕过一些DNA损伤，例如脱碱基位点和乙酰氨基芴加合的鸟嘌呤。容易出错的方式。更重要的是，Polkappa能够准确有效地绕过苯并[a]芘（B[a]P）加合的鸟嘌呤。为了研究Polkappa的生物学功能，我们已经产生了编码该酶的Polk基因缺陷的小鼠胚胎干（ES）细胞。Polk缺陷的ES细胞正常生长，它们对紫外线和X射线辐射的敏感性仅受到轻微影响。相反，突变细胞对B[a] P诱导的杀伤和诱变都高度敏感。此外，在Polk缺陷细胞中恢复的突变谱与野生型细胞中的突变谱不同。因此，我们的研究结果表明，Polkappa在抑制由B[a] P产生的DNA损伤处的突变中起重要作用。
Several low-fidelity DNA polymerases have recently been discovered that are able to bypass DNA lesions during DNA synthesis in vitro. The efficiency and accuracy of lesion bypass is, however, both polymerase and lesion specific. For example, in vitro studies revealed that human DNA polymerase kappa (Polkappa) is unable to insert a base opposite a cis-syn thymine-thymine dimer or cisplatin adduct, yet can bypass some DNA lesions such as abasic site and acetylaminofluorene-adducted guanine in an error-prone manner. More importantly, Polkappa is able to bypass benzo[a]pyrene (B[a]P)-adducted guanine accurately and efficiently. To investigate the biological function of Polkappa, we have generated mouse embryonic stem (ES) cells deficient in the Polk gene encoding the enzyme. Polk-deficient ES cells grow normally and their sensitivities to UV and x-ray radiation are only slightly affected. In contrast, the mutant cells are highly sensitive to both killing and mutagenesis induced by B[a]P. Furthermore, the spectrum of mutations recovered in the Polk-deficient cells is different from that in the wildtype cells. Thus, our results indicate that Polkappa plays an important role in suppressing mutations at DNA lesions generated by B[a]P.