Deficiency in the response to DNA double-strand breaks in mouse early preimplantation embryos.
Deficiency in the response to DNA double-strand breaks in mouse early preimplantation embryos.
复制标题
DOI：
10.1016/j.bbrc.2007.04.162
复制
发表时间：
2007-06
影响因子：
3.1
通讯作者：
M. Yukawa;S. Oda;H. Mitani;M. Nagata;F. Aoki
中科院分区：
文献类型：
--
作者：
M. Yukawa;S. Oda;H. Mitani;M. Nagata;F. Aoki
DNA双链断裂（DSB）是由各种环境应力引起的，如电离辐射和DNA损伤剂。当DSB发生时，细胞周期检查点机制的功能是停止细胞周期，直到所有DSB被修复; H2 AX的磷酸化在这个过程中起着重要作用。小鼠预受精阶段的胚胎对电离辐射高度敏感，X射线照射的小鼠受精卵被阻滞在第一个细胞周期的G2期。为了探讨小鼠植入前胚胎G2期DNA损伤的反应机制，我们研究了这些胚胎的G2/M检查点和DNA修复机制。大多数经γ射线诱导DSB的单细胞和双细胞胚胎在囊胚期前发生卵裂延迟并停止发育。在这些胚胎中，磷酸化的H2 AX（γ-H2 AX）在一个或两个细胞阶段的免疫细胞化学检测不到，虽然它被检测到后的两个细胞阶段在植入前发育。这些结果表明，G2/M检查点和DNA修复机制在单细胞和双细胞胚胎中的功能不足，导致对γ射线的超敏反应。此外，磷酸化共济失调毛细血管扩张症突变蛋白和DNA蛋白激酶催化亚基，磷酸化H2 AX，在胚胎中检测到在一个和两个细胞阶段，以及在其他植入前阶段，表明γ-H2 AX在一个和两个细胞胚胎中的缺乏取决于一些因素，而不是这些激酶。
DNA double-strand breaks (DSBs) are caused by various environmental stresses, such as ionizing radiation and DNA-damaging agents. When DSBs occur, cell cycle checkpoint mechanisms function to stop the cell cycle until all DSBs are repaired; the phosphorylation of H2AX plays an important role in this process. Mouse preimplantation-stage embryos are hypersensitive to ionizing radiation, and X-irradiated mouse zygotes are arrested at the G2 phase of the first cell cycle. To investigate the mechanisms responding to DNA damage at G2 in mouse preimplantation embryos, we examined G2/M checkpoint and DNA repair mechanisms in these embryos. Most of the one- and two-cell embryos in which DSBs had been induced by γ-irradiation underwent a delay in cleavage and ceased development before the blastocyst stage. In these embryos, phosphorylated H2AX (γ-H2AX) was not detected in the one- or two-cell stages by immunocytochemistry, although it was detected after the two-cell stage during preimplantation development. These results suggest that the G2/M checkpoint and DNA repair mechanisms have insufficient function in one- and two-cell embryos, causing hypersensitivity to γ-irradiation. In addition, phosphorylated ataxia telangiectasia mutated protein and DNA protein kinase catalytic subunits, which phosphorylate H2AX, were detected in the embryos at one- and two-cell stages, as well as at other preimplantation stages, suggesting that the absence of γ-H2AX in one- and two-cell embryos depends on some factor(s) other than these kinases.