Direct interaction between DNMT1 and G9a coordinates DNA and histone methylation during replication
Direct interaction between DNMT1 and G9a coordinates DNA and histone methylation during replication
复制标题
DOI：
10.1101/gad.1463706
复制
发表时间：
2006-11-15
影响因子：
10.5
通讯作者：
Pradhan, Sriharsa
中科院分区：
文献类型：
--
作者：
Esteve, Pierre-Olivier;Chin, Hang Gyeong;Pradhan, Sriharsa
在哺乳动物发育过程中，染色质甲基化是稳定抑制基因表达所必需的。在细胞分裂过程中，DNMT1维持新合成子链的DNA甲基化模式，而G9a甲基化H3K9。在这里，DNMT1被证明在体内和体外都直接结合G9a，并在DNA复制过程中在细胞核中共定位。DNMT1和G9a复合体与二甲基化的H3K9 （H3K9me2）在复制位点共定位。同样，另一种H3K9组蛋白甲基转移酶SUV39H1在细胞分裂前仅与DNMT1在核仁的异染色质区域共定位。在染色质复制过程中，DNMT1和G9a在与装载因子PCNA的三元复合体中同时装载到染色质上。DNMT1的小干扰RNA （Small interfering RNA, siRNA）敲低会损害染色质和rDNA重复序列上的DNA甲基化、G9a装载和H3K9甲基化，从而证实DNMT1是主要装载因子。此外，DNMT1和G9a复合物导致体外组装的染色质底物的DNA和组蛋白甲基化增强。因此，DNMT1和G9a之间的直接合作提供了细胞分裂过程中DNA和H3K9甲基化协调的机制。
Chromatin methylation is necessary for stable repression of gene expression during mammalian development. During cell division, DNMT1 maintains the DNA methylation pattern of the newly synthesized daughter strand, while G9a methylates H3K9. Here, DNMT1 is shown to directly bind G9a both in vivo and in vitro and to colocalize in the nucleus during DNA replication. The complex of DNMT1 and G9a colocalizes with dimethylated H3K9 (H3K9me2) at replication foci. Similarly, another H3K9 histone methyltransferase, SUV39H1, colocalizes with DNMT1 on heterochromatic regions of the nucleoli exclusively before cell division. Both DNMT1 and G9a are loaded onto the chromatin simultaneously in a ternary complex with loading factor PCNA during chromatin replication. Small interfering RNA ( siRNA) knockdown of DNMT1 impairs DNA methylation, G9a loading, and H3K9 methylation on chromatin and rDNA repeats, confirming DNMT1 as the primary loading factor. Additionally, the complex of DNMT1 and G9a led to enhanced DNA and histone methylation of in vitro assembled chromatin substrates. Thus, direct cooperation between DNMT1 and G9a provides a mechanism of coordinated DNA and H3K9 methylation during cell division.