XRad17 is required for the activation of XChk1 but not XCds1 during checkpoint signaling in Xenopus
XRad17 is required for the activation of XChk1 but not XCds1 during checkpoint signaling in Xenopus
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DOI：
10.1091/mbc.e03-03-0138
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发表时间：
2003-09-01
影响因子：
3.3
通讯作者：
Lindsay, HD
中科院分区：
文献类型：
--
作者：
Jones, RE;Chapman, JR;Lindsay, HD
DNA 损伤/复制检查点通过感知受损 DNA 或停滞的复制叉的存在来发挥作用，并启动阻止细胞周期进程的信号通路。在这里，我们报告了 RFC 和 PCNA 相关检查点蛋白的爪蟾直系同源物的克隆和表征。 XRad17 与复制因子 C 的五个亚基共享同源区域。XRad9、XRad1 和 XHus1（9-1-1 复合物的组成部分）均显示与 DNA 聚合酶持续合成因子 PCNA 同源。我们证明这些蛋白质与染色质结合，并且当复制被阿非迪霉素抑制时被磷酸化。 X9-1-1 的磷酸化对咖啡因敏感，但复制阻断后 XRad17 和 X9-1-1 复合体的染色质关联不受咖啡因影响。这表明 X9-1-1 复合物可以独立于 XAtm/XAtr 活性与染色质结合。我们进一步证明，XRad17 对于 X9-1-1 的染色质结合和检查点依赖性磷酸化以及当阿菲迪霉素诱导复制检查点时激活 XChk1 至关重要。然而，XRad17 并不是响应 dsDNA 末端而激活 XCds1 所必需的。
The DNA damage/replication checkpoints act by sensing the presence of damaged DNA or stalled replication forks and initiate signaling pathways that arrest cell cycle progression. Here we report the cloning and characterization of Xenopus orthologues of the RFC- and PCNA-related checkpoint proteins. XRad17 shares regions of homology with the five subunits of Replication factor C. XRad9, XRad1, and XHus1 (components of the 9-1-1 complex) all show homology to the DNA polymerase processivity factor PCNA. We demonstrate that these proteins associate with chromatin and are phosphorylated when replication is inhibited by aphidicolin. Phosphorylation of X9-1-1 is caffeine sensitive, but the chromatin association of XRad17 and the X9-1-1 complex after replication block is unaffected by caffeine. This suggests that the X9-1-1 complex can associate with chromatin independently of XAtm/XAtr activity. We further demonstrate that XRad17 is essential for the chromatin binding and checkpoint-dependent phosphorylation of X9-1-1 and for the activation of XChk1 when the replication checkpoint is induced by aphidicolin. XRad17 is not, however, required for the activation of XCds1 in response to dsDNA ends.