Centre for Chromosome Biology, School of Natural Sciences, National University of Ireland Galway, Ireland.
FEBS J. 2013 Oct;280(19):4888-902. doi: 10.1111/febs.12465. Epub 2013 Aug 27.
The replication factor Cdc45 has essential functions in the initiation and elongation steps of eukaryotic DNA replication and plays an important role in the intra-S-phase checkpoint. Its interactions with other replication proteins during the cell cycle and after intra-S-phase checkpoint activation are only partially characterized. In the present study, we show that the C terminal part of Cdc45 may mediate its interactions with Claspin. The interactions of human Cdc45 with the three replication factors Claspin, replication protein A and DNA polymerase δ are maximal during the S phase. Following UVC-induced DNA damage, Cdc45-Claspin complex formation is reduced, whereas the binding of Cdc45 to replication protein A is not affected. We also show that treatment of cells with UCN-01 and phosphatidylinositol 3-kinase-like kinase inhibitors does not rescue the UV-induced destabilization of Cdc45-Claspin interactions, suggesting that the loss of the interaction between Cdc45 and Claspin occurs upstream of ataxia telangiectasia and Rad 3-related activation in the intra-S-phase checkpoint.
复制因子 Cdc45 在真核生物 DNA 复制的起始和延伸步骤中具有重要功能，在细胞周期内 S 期检查点中发挥重要作用。其在细胞周期内和 S 期检查点激活后的与其他复制蛋白的相互作用仅部分被阐明。在本研究中，我们表明 Cdc45 的 C 端部分可能介导其与 Claspin 的相互作用。在 S 期，人 Cdc45 与三种复制因子 Claspin、复制蛋白 A 和 DNA 聚合酶 δ 的相互作用最大。在 UVC 诱导的 DNA 损伤后，Cdc45-Claspin 复合物的形成减少，而 Cdc45 与复制蛋白 A 的结合不受影响。我们还表明，用 UCN-01 和磷脂酰肌醇 3-激酶样激酶抑制剂处理细胞不能挽救 UV 诱导的 Cdc45-Claspin 相互作用的不稳定性，表明在细胞周期内 S 期检查点中，Cdc45 和 Claspin 之间的相互作用的丧失发生在共济失调毛细血管扩张症和 Rad 3 相关蛋白激活的上游。
