Meister Peter, Taddei Angela, Vernis Laurence, Poidevin Mickaël, Gasser Susan M, Baldacci Giuseppe
CNRS UMR2027, Institut Curie, Centre Universitaire, 91405 Orsay Cedex, France.
J Cell Biol. 2005 Feb 14;168(4):537-44. doi: 10.1083/jcb.200410006.
In response to DNA damage and replication pausing, eukaryotes activate checkpoint pathways that prevent genomic instability by coordinating cell cycle progression with DNA repair. The intra-S-phase checkpoint has been proposed to protect stalled replication forks from pathological rearrangements that could result from unscheduled recombination. On the other hand, recombination may be needed to cope with either stalled forks or double-strand breaks resulting from hydroxyurea treatment. We have exploited fission yeast to elucidate the relationship between replication fork stalling, loading of replication and recombination proteins onto DNA, and the intra-S checkpoint. Here, we show that a functional recombination machinery is not essential for recovery from replication fork arrest and instead can lead to nonfunctional fork structures. We find that Rad22-containing foci are rare in S-phase cells, but peak in G2 phase cells after a perturbed S phase. Importantly, we find that the intra-S checkpoint is necessary to avoid aberrant strand-exchange events during a hydroxyurea block.
为应对DNA损伤和复制暂停，真核生物激活检查点通路，通过协调细胞周期进程与DNA修复来防止基因组不稳定。有人提出S期内检查点可保护停滞的复制叉免受因异常重组而可能导致的病理性重排。另一方面，可能需要重组来应对由羟基脲处理导致的停滞叉或双链断裂。我们利用裂殖酵母来阐明复制叉停滞、复制和重组蛋白加载到DNA上以及S期内检查点之间的关系。在此，我们表明功能性重组机制对于从复制叉停滞中恢复并非必不可少，反而可能导致无功能的叉结构。我们发现含Rad22的病灶在S期细胞中很少见，但在受干扰的S期后的G2期细胞中达到峰值。重要的是，我们发现S期内检查点对于避免羟基脲阻断期间异常的链交换事件是必要的。
