National Institute for Public Health and the Environment, Bilthoven, The Netherlands; Department of Cell Biology and Genetics, Center for Biomedical Genetics, Erasmus MC, Rotterdam, The Netherlands.
National Institute for Public Health and the Environment, Bilthoven, The Netherlands.
PLoS One. 2014 Apr 16;9(4):e93568. doi: 10.1371/journal.pone.0093568. eCollection 2014.
Ku80 and DNA-PKCS are both involved in the repair of double strand DNA breaks via the nonhomologous end joining (NHEJ) pathway. While ku80-/- mice exhibit a severely reduced lifespan and size, this phenotype is less pronounced in dna-pkcs-/- mice. However, these observations are based on independent studies with varying genetic backgrounds. Here, we generated ku80-/-, dna-pkcs-/- and double knock out mice in a C57Bl6/J*FVB F1 hybrid background and compared their lifespan, end of life pathology and mutation frequency in liver and spleen using a lacZ reporter. Our data confirm that inactivation of Ku80 and DNA-PKCS causes reduced lifespan and bodyweights, which is most severe in ku80-/- mice. All mutant mice exhibited a strong increase in lymphoma incidence as well as other aging-related pathology (skin epidermal and adnexal atrophy, trabacular bone reduction, kidney tubular anisokaryosis, and cortical and medullar atrophy) and severe lymphoid depletion. LacZ mutation frequency analysis did not show strong differences in mutation frequencies between knock out and wild type mice. The ku80-/- mice had the most severe phenotype and the Ku80-mutation was dominant over the DNA-PKCS-mutation. Presumably, the more severe degenerative effect of Ku80 inactivation on lifespan compared to DNA-PKCS inactivation is caused by additional functions of Ku80 or activity of free Ku70 since both Ku80 and DNA-PKCS are essential for NHEJ.
Ku80 和 DNA-PKCS 均参与通过非同源末端连接（NHEJ）途径修复双链 DNA 断裂。虽然 Ku80-/- 小鼠的寿命和体型明显缩短，但 DNA-PKCS-/- 小鼠的表型则不太明显。然而，这些观察结果是基于具有不同遗传背景的独立研究。在这里，我们在 C57Bl6/J*FVB F1 杂种背景下生成了 Ku80-/-、DNA-PKCS-/- 和双敲除小鼠，并使用 lacZ 报告基因比较了它们的寿命、生命末期的病理学和肝脏和脾脏中的突变频率。我们的数据证实，Ku80 和 DNA-PKCS 的失活导致寿命和体重降低，在 Ku80-/- 小鼠中最为严重。所有突变小鼠的淋巴瘤发病率以及其他与衰老相关的病理学（皮肤表皮和附属物萎缩、小梁骨减少、肾小管不均匀核、皮质和髓质萎缩）均显著增加，并且淋巴细胞严重耗竭。LacZ 突变频率分析未显示敲除和野生型小鼠之间的突变频率有明显差异。Ku80-/- 小鼠的表型最为严重，Ku80 突变的作用超过了 DNA-PKCS 突变。推测 Ku80 失活对寿命的退行性影响比 DNA-PKCS 失活更为严重，这是由于 Ku80 或游离 Ku70 的额外功能或活性所致，因为 Ku80 和 DNA-PKCS 对 NHEJ 都是必需的。
