Sierant Megan L, Davey Scott K
Division of Cancer Biology & Genetics, Cancer Research Institute, Queen's University, Kingston, ON K7L 3N6, Canada; Department of Biochemistry, Queen's University, Kingston, ON K7L 3N6, Canada.
Division of Cancer Biology & Genetics, Cancer Research Institute, Queen's University, Kingston, ON K7L 3N6, Canada; Department of Biochemistry, Queen's University, Kingston, ON K7L 3N6, Canada; Departments of Pathology and Molecular Medicine, and Oncology, Queen's University, Kingston, ON K7L 3N6, Canada.
Cancer Genet. 2018 Dec;228-229:98-109. doi: 10.1016/j.cancergen.2018.10.003. Epub 2018 Oct 18.
The human RAD9A protein is required for successful execution of the G2/M DNA damage checkpoint. Along with RAD1 and HUS1, RAD9A exists in a heterotrimeric ring-shaped complex which is necessary for activation of the CHK1 checkpoint kinase. RAD9A is also required for proper localization of both TopBP1 and the Claspin adaptor protein during the DNA damage response. We have shown large, RAD9A-dense nuclear foci containing several members of the homologous recombination pathway as well as BRCA1 and the DNA damage marker γH2AX. This RAD9A-dense body is closely associated with the inactive X in HeLa cells but not in other cell types analyzed including a Klinefelter's syndrome-derived line containing multiple Xi. We have also shown these foci disappear after cell synchronization but are enriched after treatment with the homologous recombination inhibitor pentoxifylline. We conclude these foci are the result of an active process, suspended in perturbed cells, that involves interaction between the cell cycle checkpoint and homologous recombination machinery.
人类RAD9A蛋白是成功执行G2/M期DNA损伤检查点所必需的。RAD9A与RAD1和HUS1一起存在于异源三聚体环状复合物中，该复合物是激活CHK1检查点激酶所必需的。在DNA损伤反应过程中，TopBP1和Claspin衔接蛋白的正确定位也需要RAD9A。我们已经发现了大的、富含RAD9A的核灶，其中包含同源重组途径的几个成员以及BRCA1和DNA损伤标志物γH2AX。这种富含RAD9A的物体在HeLa细胞中与失活的X染色体紧密相关，但在包括含有多个Xi的克兰费尔特综合征衍生系在内的其他分析细胞类型中则不然。我们还表明，这些病灶在细胞同步化后消失，但在用同源重组抑制剂己酮可可碱处理后会富集。我们得出结论，这些病灶是一个活跃过程的结果，在受干扰的细胞中暂停，该过程涉及细胞周期检查点和同源重组机制之间的相互作用。
