The histone H4 Lys 20 methyltransferase PR-Set7 regulates replication origins in mammalian cells
The histone H4 Lys 20 methyltransferase PR-Set7 regulates replication origins in mammalian cells
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DOI：
10.1038/ncb2113
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发表时间：
2010-11-01
影响因子：
21.3
通讯作者：
Julien, Eric
中科院分区：
文献类型：
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作者：
Tardat, Mathieu;Brustel, Julien;Julien, Eric
DNA合成的起始是由复制起始点的许可控制的，这包括在M期晚期和g1期在起始点上组装一个复制前复合体（pre-RC）（1,2）。在后生动物中，功能性复制起点不显示确定的DNA一致序列，因此在这些起点的选择中引起染色质决定因素的参与(3)。在这里，我们发现在哺乳动物细胞中许可的开始与甲基转移酶PR-Set7（也称为Set8或KMT5A）在复制起点上组蛋白H4 Lys 20单甲基化（H4K20me1）的增加相一致。事实上，将PR-Set7甲基化酶活性拴在特定基因组位点上可促进pre-RC蛋白在染色质上的装载。此外，我们证明PR-Set7在S期经历PCNA-和cul4 - ddb1驱动的降解，这有助于H4K20me1在起源处的消失和复制许可的抑制。引人注目的是，对这种降解不敏感的PR-Set7突变体的表达导致H4K20me1的维持和起源处重复的DNA复制。这些结果阐明了PR-Set7和H4K20me1在调节复制起始的染色质事件中的关键作用。
The initiation of DNA synthesis is governed by the licensing of replication origins, which consists of assembling a pre-replication complex (pre-RC) on origins during late M- and G1-phases(1,2). In metazoans, functional replication origins do not show defined DNA consensus sequences, thus evoking the involvement of chromatin determinants in the selection of these origins(3). Here, we show that the onset of licensing in mammalian cells coincides with an increase in histone H4 Lys 20 monomethylation (H4K20me1) at replication origins by the methyltransferase PR-Set7 (also known as Set8 or KMT5A). Indeed, tethering PR-Set7 methylase activity to a specific genomic locus promotes the loading of pre-RC proteins on chromatin. In addition, we demonstrate that PR-Set7 undergoes a PCNA- and Cul4-Ddb1-driven degradation during S phase that contributes to the disappearance of H4K20me1 at origins and the inhibition of replication licensing. Strikingly, expression of a PR-Set7 mutant insensitive to this degradation causes the maintenance of H4K20me1 and repeated DNA replication at origins. These results elucidate a critical role for PR-Set7 and H4K20me1 in the chromatin events that regulate replication origins.