Redundant and differential regulation of multiple licensing factors ensures prevention of re-replication in normal human cells
Redundant and differential regulation of multiple licensing factors ensures prevention of re-replication in normal human cells
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DOI：
10.1242/jcs.041889
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发表时间：
2009-04-15
影响因子：
4
通讯作者：
Fujita, Masatoshi
中科院分区：
文献类型：
--
作者：
Sugimoto, Nozomi;Yoshida, Kazumasa;Fujita, Masatoshi
当人类细胞进入S期时，重叠的差异抑制机制下调了复制许可因子ORC1，CDC6和Cdt1。这种调节防止再复制，因此预期任何单个因子的失调都不会诱导明显的再复制。然而，Cdt1或Cdt1+CDC6的过表达在一些癌细胞系中引起再复制的事实已经挑战了这一点。我们认为，重要的是要分析许可条例在人类非癌细胞Cdt1诱导的再复制和检查是否同时解除管制，这些许可因素诱导再复制在两个这样的细胞系，包括人成纤维细胞永生化的端粒酶。Cdt1、ORC1或CDC6的单独过表达均未诱导可检测到的再复制。然而，与Cdt1+ ORC 1或Cdt1+CDC6，一些再复制是可检测的和Cdt1+ ORC 1 +CDC6的共表达协同作用，以提供强大的再复制与增加的微型染色体维持（MCM）加载。ORC 1 +CDC6的共表达没有影响。这些结果表明，虽然Cdt1调节是关键步骤，但多种许可因子的差异调节确保了正常人类细胞中再复制的预防。我们的研究结果还首次显示了ORC1调控对预防再复制的重要性。
When human cells enter S-phase, overlapping differential inhibitory mechanisms downregulate the replication licensing factors ORC1, CDC6 and Cdt1. Such regulation prevents re-replication so that deregulation of any individual factor alone would not be expected to induce overt re-replication. However, this has been challenged by the fact that overexpression of Cdt1 or Cdt1+CDC6 causes re-replication in some cancer cell lines. We thought it important to analyze licensing regulations in human non-cancerous cells that are resistant to Cdt1-induced re-replication and examined whether simultaneous deregulation of these licensing factors induces re-replication in two such cell lines, including human fibroblasts immortalized by telomerase. Individual overexpression of either Cdt1, ORC1 or CDC6 induced no detectable re-replication. However, with Cdt1+ORC1 or Cdt1+CDC6, some re-replication was detectable and coexpression of Cdt1+ORC1+CDC6 synergistically acted to give strong re-replication with increased mini-chromosome maintenance (MCM) loading. Coexpression of ORC1+CDC6 was without effect. These results suggest that, although Cdt1 regulation is the key step, differential regulation of multiple licensing factors ensures prevention of re-replication in normal human cells. Our findings also show for the first time the importance of ORC1 regulation for prevention of re-replication.