Department of Late Effects Studies, Laboratory of DNA Damage Signaling, Kyoto University, Kyoto 606-8501, Japan, Japan Society for the Promotion of Science (JSPS), Tokyo 102-0083, Japan.
Nucleic Acids Res. 2013 Aug;41(14):6930-41. doi: 10.1093/nar/gkt467. Epub 2013 May 30.
When DNA replication is stalled at sites of DNA damage, a cascade of responses is activated in the cell to halt cell cycle progression and promote DNA repair. A pathway initiated by the kinase Ataxia teleangiectasia and Rad3 related (ATR) and its partner ATR interacting protein (ATRIP) plays an important role in this response. The Fanconi anemia (FA) pathway is also activated following genomic stress, and defects in this pathway cause a cancer-prone hematologic disorder in humans. Little is known about how these two pathways are coordinated. We report here that following cellular exposure to DNA cross-linking damage, the FA core complex enhances binding and localization of ATRIP within damaged chromatin. In cells lacking the core complex, ATR-mediated phosphorylation of two functional response targets, ATRIP and FANCI, is defective. We also provide evidence that the canonical ATR activation pathway involving RAD17 and TOPBP1 is largely dispensable for the FA pathway activation. Indeed DT40 mutant cells lacking both RAD17 and FANCD2 were synergistically more sensitive to cisplatin compared with either single mutant. Collectively, these data reveal new aspects of the interplay between regulation of ATR-ATRIP kinase and activation of the FA pathway.
当 DNA 复制在 DNA 损伤部位停滞时，细胞中会激活一系列反应来阻止细胞周期进程并促进 DNA 修复。由激酶共济失调毛细血管扩张症和 Rad3 相关（ATR）及其伴侣 ATR 相互作用蛋白（ATRIP）启动的途径在该反应中起着重要作用。FA 途径也会在基因组应激后被激活，而该途径的缺陷会导致人类易患癌症的血液疾病。目前尚不清楚这两种途径如何协调。我们在这里报告，在细胞暴露于 DNA 交联损伤后，FA 核心复合物增强了ATRIP 在受损染色质中的结合和定位。在缺乏核心复合物的细胞中，ATR 介导的两个功能反应靶标ATRIP 和 FANCI 的磷酸化是有缺陷的。我们还提供了证据表明，涉及 RAD17 和 TOPBP1 的经典 ATR 激活途径对于 FA 途径的激活在很大程度上是可有可无的。事实上，与任一单突变体相比，同时缺乏 RAD17 和 FANCD2 的 DT40 突变细胞对顺铂的敏感性呈协同增强。总之，这些数据揭示了 ATR-ATRIP 激酶的调节与 FA 途径激活之间相互作用的新方面。
