Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6018, USA.
Biol Reprod. 2010 Dec;83(6):1027-35. doi: 10.1095/biolreprod.110.086397. Epub 2010 Aug 18.
The epigenetic mechanisms involved in establishing and maintaining genomic imprinting are steadily being unmasked. The nucleosome remodeling and histone deacetylation (NuRD) complex is implicated in regulating DNA methylation and expression of the maternally expressed H19 gene in preimplantation mouse embryos. To dissect further the function of the NuRD complex in genomic imprinting, we employed an RNA interference (RNAi) strategy to deplete the NuRD complex component Metastasis Tumor Antigen 2 (MTA2). We found that Mta2 is the only zygotically expressed Mta gene prior to the blastocyst stage, and that RNAi-mediated knockdown of Mta2 transcript leads to biallelic H19 expression and loss of DNA methylation in the differentially methylated region in blastocysts. In addition, biallelic expression of the paternally expressed Peg3 gene, but not Snrpn, is also observed in blastocysts following Mta2 knockdown. Loss of MTA2 protein does not result in a decrease in abundance of other NuRD components, including methyl-binding-CpG-binding domain protein 3 (MBD3), histone deacetylases 1 and 2 (HDACs 1 and 2), and chromodomain helicase DNA-binding protein 4 (CHD4). Taken together, our results support a role for MTA2 within the NuRD complex in genomic imprinting.
涉及建立和维持基因组印记的表观遗传机制正在逐渐被揭示。核小体重塑和组蛋白去乙酰化（NuRD）复合物被认为在调节母系表达的 H19 基因的 DNA 甲基化和表达中起作用。为了进一步剖析 NuRD 复合物在基因组印记中的功能，我们采用 RNA 干扰（RNAi）策略来耗尽 NuRD 复合物成分转移肿瘤抗原 2（MTA2）。我们发现，Mta2 是合子表达的唯一 Mta 基因，在囊胚阶段之前，并且 RNAi 介导的 Mta2 转录本敲低导致囊胚中 H19 的双等位基因表达和差异甲基化区域的 DNA 甲基化丧失。此外，在 Mta2 敲低后，囊胚中也观察到父系表达的 Peg3 基因的双等位基因表达，但不是 Snrpn。MTA2 蛋白的丢失不会导致其他 NuRD 成分（包括甲基结合-CpG 结合域蛋白 3（MBD3）、组蛋白去乙酰化酶 1 和 2（HDACs 1 和 2）和染色质螺旋酶 DNA 结合蛋白 4（CHD4）的丰度降低。总之，我们的结果支持 MTA2 在 NuRD 复合物中的作用在基因组印记中。
