Department of Genetics & Genomics, Boston University School of Medicine, Boston, MA, USA.
Cell Cycle. 2010 Jun 15;9(12):2375-88. doi: 10.4161/cc.9.12.11900.
Fanconi Anemia (FA) is a cancer-susceptibility syndrome characterized by cellular sensitivity to DNA inter-strand cross-link (ICL)-inducing agents. The Fanconia Anemia D2 (FANCD2) protein is implicated in repair of various forms of DNA damage including ICLs. Studies with replicating extracts from Xenopus eggs indicate a role for FANCD2 in processing and repair of DNA replication-associated double stranded breaks (DSB). We have investigated the role of FANCD2 in cell cycle progression of cultured human cells. Similar to Xenopus cell-free extracts, we show that chromatin association of FANCD2 in human cells is coupled to ongoing DNA replication. siRNA depletion experiments demonstrate that FANCD2 is necessary for efficient DNA synthesis. However, in contrast with Xenopus extracts, FANCD2-deficiency does not elicit a DNA damage response, and does not affect the elongation phase of DNA synthesis, suggesting that FANCD2 is dispensable for repair of replication-associated DNA damage. Using synchronized cultures of primary untransformed human dermal fibroblasts we demonstrate that FANCD2 is necessary for efficient initiation of DNA synthesis. Taken together, our results suggest a novel role for the FA pathway in regulation of DNA synthesis and cell cycle progression. Inefficient DNA replication may contribute to the genome instability and cancer-propensity of FA patients.
范可尼贫血症（FA）是一种易患癌症的综合征，其特征是细胞对 DNA 链间交联（ICL）诱导剂敏感。范可尼贫血症 D2（FANCD2）蛋白参与多种形式的 DNA 损伤修复，包括 ICL。来自非洲爪蟾卵提取物的研究表明，FANCD2 在处理和修复与 DNA 复制相关的双链断裂（DSB）方面发挥作用。我们研究了 FANCD2 在培养的人细胞细胞周期进程中的作用。与非洲爪蟾无细胞提取物类似，我们表明人细胞中 FANCD2 的染色质关联与正在进行的 DNA 复制偶联。siRNA 耗尽实验表明 FANCD2 对于有效的 DNA 合成是必需的。然而，与非洲爪蟾提取物不同，FANCD2 缺陷不会引发 DNA 损伤反应，也不会影响 DNA 合成的延伸阶段，这表明 FANCD2 对于修复与复制相关的 DNA 损伤是可有可无的。使用原代未转化的人真皮成纤维细胞的同步培养物，我们证明 FANCD2 对于有效启动 DNA 合成是必需的。总之，我们的结果表明 FA 途径在调节 DNA 合成和细胞周期进程中具有新的作用。低效的 DNA 复制可能导致 FA 患者的基因组不稳定性和癌症易感性。
