Chromosome Segregation Laboratory, Cancer Research UK London Research Institute, 44 Lincoln's Inn Fields, London WC2A 3LY, UK.
Curr Biol. 2013 Jan 7;23(1):64-9. doi: 10.1016/j.cub.2012.11.030. Epub 2012 Dec 6.
The establishment of stable sister chromatid cohesion during DNA replication requires acetylation of the chromosomal cohesin complex by the replication fork-associated acetyltransferase Eco1. Cohesin acetylation is thought to facilitate replication fork progression by counteracting an as yet ill-defined cohesion "antiestablishment" activity imposed by the Wapl protein. Here, using budding yeast, we find no evidence that cohesin acetylation must overcome Wapl during replication fork progression. Instead, Wapl emerges as a negative regulator of cohesion maintenance in G2, a function that it likely exerts through its role as destabilizer of unacetylated, chromosome-bound cohesin. Our results suggest that acetylation renders cohesin Wapl-resistant from S phase onward until mitosis. In the absence of Wapl, sister chromatid cohesion functions well, suggesting that Wapl partakes in a cohesin function outside of sister chromatid cohesion. We find that Wapl is not required for cohesin's known role in transcriptional regulation. Rather, cells lacking Wapl display increased chromosome condensation in both interphase and mitosis. Thus, as a conserved regulator of cohesin dynamics on chromosomes, Wapl controls cohesion maintenance after its establishment in S phase and adjusts the chromosome condensation status.
在 DNA 复制过程中建立稳定的姐妹染色单体黏合需要复制叉相关的乙酰转移酶 Eco1 对染色体黏合复合物进行乙酰化。黏合蛋白的乙酰化被认为可以通过抵消 Wapl 蛋白施加的尚未明确的黏合“抗建立”活性来促进复制叉的进展。在这里，我们使用芽殖酵母发现，在复制叉进展过程中，黏合蛋白的乙酰化不必克服 Wapl。相反，Wapl 作为 G2 中黏合维持的负调控因子出现，它可能通过其作为未乙酰化、染色体结合的黏合蛋白的稳定剂来发挥作用。我们的结果表明，乙酰化使黏合蛋白从 S 期开始对 Wapl 具有抗性，直到有丝分裂。在没有 Wapl 的情况下，姐妹染色单体黏合功能良好，这表明 Wapl 参与了姐妹染色单体黏合之外的黏合功能。我们发现 Wapl 对于黏合蛋白在转录调控中的已知作用不是必需的。相反，缺乏 Wapl 的细胞在有丝分裂和间期都显示出染色体凝聚增加。因此，作为染色体上黏合动力学的保守调节剂，Wapl 在 S 期建立后控制黏合的维持，并调整染色体凝聚状态。
