Role of the Dnmt3 family in de novo methylation of imprinted and repetitive sequences during male germ cell development in the mouse
Role of the Dnmt3 family in de novo methylation of imprinted and repetitive sequences during male germ cell development in the mouse
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DOI：
10.1093/hmg/ddm179
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发表时间：
2007-10-01
影响因子：
3.5
通讯作者：
Sasaki, Hiroyuki
中科院分区：
文献类型：
--
作者：
Kato, Yuzuru;Kaneda, Masahiro;Sasaki, Hiroyuki
DNA甲基化是调节多种生物现象的重要表观遗传修饰，包括基因组印记和转座子沉默。众所周知，与父系印记基因相关的差异甲基化区域（DMR）和一些重复元件的甲基化发生在小鼠雄性生殖细胞发育过程中。我们对父系甲基化 DMR（H19、Dlk1/Gtl2 和 Rasgrf1）、散布重复序列 [SineB1、脑池内 A 颗粒 (IAP) 和 Line1] 和卫星重复序列（主要和次要）进行了详细的甲基化分析，以确定雄性生殖细胞中这种从头甲基化的时间。此外，我们还研究了从头甲基转移酶（Dnmt3a 和 Dnmt3b）和相关蛋白（Dnmt3L）在此过程中的作用。我们发现所有 DMR 和重复序列的甲基化在胎儿精原细胞中逐渐发生，并在新生儿阶段完成。对种系特异性 Dnmt3a 和 Dnmt3b 敲除小鼠的新生精原细胞的分析表明，Dnmt3a 主要甲基化 H19 和 Dlk1/Gtl2 DMR 以及短散布重复序列 SineB1。 Dnmt3a 和 Dnmt3b 均参与 Rasgrf1 DMR 以及长散布重复序列 IAP 和 Line1 的甲基化。卫星重复序列的甲基化仅需要 Dnmt3b。这些结果表明 Dnmt3a 和 Dnmt3b 在体内的共同和差异靶标特异性。最后，所有这些序列在 Dnmt3L 缺陷的精原细胞中均表现出中度至重度低甲基化，表明该因子在从头甲基化中的关键功能和广泛特异性。
DNA methylation is an important epigenetic modification regulating various biological phenomena, including genomic imprinting and transposon silencing. It is known that methylation of the differentially methylated regions (DMRs) associated with paternally imprinted genes and of some repetitive elements occurs during male germ cell development in the mouse. We have performed a detailed methylation analysis of the paternally methylated DMRs (H19, Dlk1/ Gtl2 and Rasgrf1), interspersed repeats [SineB1, intracisternal A particle (IAP) and Line1] and satellite repeats (major and minor) to determine the timing of this de novo methylation in male germ cells. Furthermore, we have examined the roles of the de novo methyltransferases (Dnmt3a and Dnmt3b) and related protein (Dnmt3L) in this process. We found that methylation of all DMRs and repeats occurred progressively in fetal prospermatogonia and was completed by the newborn stage. Analysis of newborn prospermatogonia from germline-specific Dnmt3a and Dnmt3b knockout mice revealed that Dnmt3a mainly methylates the H19 and Dlk1/Gtl2 DMRs and a short interspersed repeat SineB1. Both Dnmt3a and Dnmt3b were involved in the methylation of Rasgrf1 DMR and long interspersed repeats IAP and Line1. Only Dnmt3b was required for the methylation of the satellite repeats. These results indicate both common and differential target specificities of Dnmt3a and Dnmt3b in vivo. Finally, all these sequences showed moderate to severe hypomethylation in Dnmt3L-deficient prospermatogonia, indicating the critical function and broad specificity of this factor in de novo methylation.