Department of Cell Biology and Physiology, University of Pittsburgh School of Medicine and University of Pittsburgh Cancer Institute, Pittsburgh, PA, USA.
EMBO J. 2010 May 19;29(10):1726-37. doi: 10.1038/emboj.2010.55. Epub 2010 Apr 27.
Recent studies have shown a critical function for the ubiquitin-proteasome system (UPS) in regulating the signalling network for DNA damage responses and DNA repair. To search for new UPS targets in the DNA damage signalling pathway, we have carried out a non-biased assay to identify fast-turnover proteins induced by various types of genotoxic stress. This endeavour led to the identification of Rad17 as a protein exhibiting a distinctive pattern of upregulation followed by subsequent degradation after exposure to UV radiation in human primary cells. Our characterization showed that UV-induced Rad17 oscillation is mediated by Cdh1/APC, a ubiquitin-protein ligase. Studies using a degradation-resistant Rad17 mutant demonstrated that Rad17 stabilization prevents the termination of checkpoint signalling, which in turn attenuates the cellular re-entry into cell-cycle progression. The findings provide an insight into how the proteolysis of Rad17 by Cdh1/APC regulates the termination of checkpoint signalling and the recovery from genotoxic stress.
最近的研究表明，泛素-蛋白酶体系统 (UPS) 在调节 DNA 损伤反应和 DNA 修复的信号网络方面具有关键功能。为了在 DNA 损伤信号通路中寻找新的 UPS 靶标，我们进行了一项无偏的测定，以鉴定各种类型的遗传毒性应激诱导的快速周转蛋白。这一努力导致了 Rad17 作为一种蛋白的鉴定，它在人类原代细胞暴露于 UV 辐射后表现出独特的上调模式，随后降解。我们的特性表明，UV 诱导的 Rad17 振荡是由 Cdh1/APC 介导的，Cdh1/APC 是一种泛素-蛋白连接酶。使用不易降解的 Rad17 突变体进行的研究表明，Rad17 的稳定化可防止检查点信号的终止，从而减弱细胞重新进入细胞周期进程。这些发现提供了一个深入了解 Rad17 被 Cdh1/APC 蛋白酶体降解如何调节检查点信号的终止以及从遗传毒性应激中恢复的机制。
