Mutation of DNA Polymerase β R137Q Results in Retarded Embryo Development Due to Impaired DNA Base Excision Repair in Mice.
Mutation of DNA Polymerase β R137Q Results in Retarded Embryo Development Due to Impaired DNA Base Excision Repair in Mice.
复制标题
DNA 聚合酶β R137Q 突变导致小鼠 DNA 碱基切除修复受损导致胚胎发育迟缓
DOI：
10.1038/srep28614
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发表时间：
2016-06-30
影响因子：
4.6
通讯作者：
Guo Z
中科院分区：
文献类型：
--
作者：
Pan F;Zhao J;Zhou T;Kuang Z;Dai H;Wu H;Sun H;Zhou X;Wu X;Hu Z;He L;Shen B;Guo Z
DNA聚合酶β(POLβ)是DNA碱基切除修复途径中的关键酶，在维持基因组的完整性和稳定性方面起着关键作用。已在肿瘤中发现的一种POLDNA突变，R137Q(精氨酸到谷氨酰胺替代)，已被证明降低了聚合酶活性，并损害了其β修复能力。然而，在活着的生物体中，与这种多态相关的确切功能缺陷仍不清楚。在这里，我们构建了POLβR137Q敲入鼠，发现纯合子敲入鼠胚胎通常体积小，死亡率高(21%)。这些胚胎异常是由于细胞增殖缓慢和细胞凋亡增加所致。在R137Q敲入小鼠胚胎中，BER效率严重受损，从而导致双链断裂(DSB)和染色体异常。此外，R137Q小鼠胚胎成纤维细胞(MEF)对DNA损伤试剂，如甲烷磺酸甲酯(MMS)和过氧化氢更敏感。他们表现出更高比例的DSB，并且更有可能发生细胞凋亡。我们的结果表明，R137是一个关键的氨基酸位点，对于维持基因组稳定和胚胎发育的适当的POLβ功能是必不可少的。
DNA polymerase β (Pol β), a key enzyme in the DNA base excision repair (BER) pathway, is pivotal in maintaining the integrity and stability of genomes. One Pol β mutation that has been identified in tumors, R137Q (arginine to glutamine substitution), has been shown to lower polymerase activity, and impair its DNA repair capacity. However, the exact functional deficiency associated with this polymorphism in living organisms is still unknown. Here, we constructed Pol β R137Q knock-in mice, and found that homozygous knock-in mouse embryos were typically small in size and had a high mortality rate (21%). These embryonic abnormalities were caused by slow cell proliferation and increased apoptosis. In R137Q knock-in mouse embryos, the BER efficiency was severely impaired, which subsequently resulted in double-strand breaks (DSBs) and chromosomal aberrations. Furthermore, R137Q mouse embryo fibroblasts (MEFs) were more sensitive to DNA-damaging reagents, such as methyl methanesulfonate (MMS) and H2O2. They displayed a higher percentage of DSBs, and were more likely to undergo apoptosis. Our results indicate that R137 is a key amino acid site that is essential for proper Pol β functioning in maintaining genomic stability and embryo development.