Specificity of mutations induced by incorporation of oxidized dNTPs into DNA by human DNA polymerase η
Specificity of mutations induced by incorporation of oxidized dNTPs into DNA by human DNA polymerase η
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DOI：
10.1016/j.dnarep.2007.12.005
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发表时间：
2008-03-01
期刊：
影响因子：
3.8
通讯作者：
Nohmi, Takehiko
中科院分区：
文献类型：
--
作者：
Hidaka, Katsuhiko;Yamada, Masami;Nohmi, Takehiko
异常氧化是许多肿瘤细胞的一个特性。 DNA 前体（即脱氧核苷酸三磷酸 (dNTP)）以及 DNA 的氧化是基因组不稳定的主要原因。在这里，我们报道人类DNA聚合酶eta（h Pol eta）以错误且有效的方式将氧化dNTP，即2-羟基-2'-脱氧腺苷5'-三磷酸（2-OH-dATP）和8-羟基-2'-脱氧鸟苷5'-三磷酸（8-OH-dGTP）整合到DNA中，从而 在体外缺口填充 DNA 合成过程中诱导各种类型的突变。当反应混合物中 2-OH-dATP 的浓度等于四种正常 dNTP 的浓度时，h Pol eta 的 DNA 合成使 G 到 T 颠换的频率比仅存在正常 dNTP 的对照中的颠换频率高八倍。当 8-OH-dGTP 与正常 dNTP 等摩尔浓度存在时，它使 A 到 C 颠换的频率比对照高 17 倍。它还使 C 到 A 颠换的频率增加了大约两倍。这些结果表明，在 DNA 合成过程中，h Pol eta 掺入了与模板 G 相反的 2-OH-dATP，并掺入了与模板 A 相对的 8-OH-dGTP 和稍微相反的模板 C。除了碱基取代外，当反应混合物中存在 8-OH-dGTP 时，h Pol eta 还提高了单碱基移码和大小超过 100 个碱基对的缺失的频率。由于即使没有外源 DNA 损伤，h Pol eta 也存在于复制灶中，因此我们认为 h Pol eta 可能通过将氧化的 dNTP 错误且有效地掺入人类细胞中的 DNA 来参与诱导各种类型的突变。 (c) 2007 Elsevier B.V. 保留所有权利。
Aberrant oxidation is a property of many tumor cells. Oxidation of DNA precursors, i.e., deoxynucleotide triphosphates (dNTPs), as well as DNA is a major cause of genome instability. Here, we report that human DNA polymerase eta (h Pol eta) incorporates oxidized dNTPs, i.e., 2-hydroxy-2'-deoxyadenosine 5'-triphosphate (2-OH-dATP) and 8-hydroxy-2'-deoxyguanosine 5'-triphosphate (8-OH-dGTP), into DNA in an erroneous and efficient manner, thereby inducing various types of mutations during in vitro gap-filling DNA synthesis. When 2-OH-dATP was present at a concentration equal to those of the four normal dNTPs in the reaction mixture, DNA synthesis by h Pol eta enhanced the frequency of G-to-T transversions eight-fold higher than that of the transversions in control where only the normal dNTPs were present. When 8-OH-dGTP was present at an equimolar concentration to the normal dNTPs, it enhanced the frequency of A-to-C transversions 17-fold higher than the control. It also increased the frequency of C-to-A transversions about two-fold. These results suggest that h Pol eta incorporates 2-OH-dATP opposite template G and incorporates 8-OH-dGTP opposite template A and slightly opposite template C during DNA synthesis. Besides base substitutions, h Pol eta enhanced the frequency of single-base frameshifts and deletions with the size of more than 100 base pairs when 8-OH-dGTP was present in the reaction mixture. Since h Pol eta is present in replication foci even without exogenous DNA damage, we suggest that h Pol eta may be involved in induction of various types of mutations through the erroneous and efficient incorporation of oxidized dNTPs into DNA in human cells. (c) 2007 Elsevier B.V. All rights reserved.