State Key Laboratory of Agrobiotechnology and College of Biological Science, China Agricultural University, Beijing, China.
Theriogenology. 2012 Dec;78(9):1929-38. doi: 10.1016/j.theriogenology.2012.07.017. Epub 2012 Oct 8.
The objective was to investigate the relationship between histone H3 lysine 9 (H3K9) dimethylation (me2) and the histone methyltransferase EHMT2 (also known as G9A) in ovine embryos cloned by somatic cell nuclear transfer (SCNT). Levels of H3K9me2 or EHMT2 were detected (with immunostaining) and compared between SCNT and IVF-derived preimplantation embryos. In one-cell embryos, SCNT zygotes had significantly higher levels of H3K9me2 and EHMT2 than IVF zygotes. In cloned embryos, H3K9me2 remained hypermethylated relative to IVF embryos at two-cell and late developmental stages (morula and blastocyst), with no difference (P > 0.05) between IVF and SCNT embryos in EHMT2 levels from two-cell to blastocyst stages. The EHMT2-specific inhibitor, BIX01294, reduced global H3K9me2 levels in cultured ovine cells or SCNT embryos, but it was not appropriate for somatic cell nuclear transfer because of its high cellular toxicity. We inferred that abnormal H3K9me2 hypermethylation in SCNT embryos may not completely arise from EHMT2 expression error.
目的在于研究体细胞细胞核移植（SCNT）克隆羊胚胎中组蛋白 H3 赖氨酸 9（H3K9）二甲基化（me2）与组蛋白甲基转移酶 EHMT2（也称为 G9A）之间的关系。通过免疫染色检测和比较 SCNT 和体外受精（IVF）胚胎中 H3K9me2 或 EHMT2 的水平。在单细胞胚胎中，SCNT 受精卵的 H3K9me2 和 EHMT2 水平明显高于 IVF 受精卵。在克隆胚胎中，H3K9me2 相对于 IVF 胚胎在二细胞和晚期发育阶段（桑葚胚和囊胚）持续超甲基化，而从二细胞到囊胚阶段，EHMT2 水平在 IVF 和 SCNT 胚胎之间没有差异（P>0.05）。EHMT2 特异性抑制剂 BIX01294 降低了培养的绵羊细胞或 SCNT 胚胎中的全局 H3K9me2 水平，但由于其细胞毒性高，不适合用于体细胞细胞核移植。我们推断，SCNT 胚胎中异常的 H3K9me2 超甲基化可能不完全源于 EHMT2 表达错误。
