小鼠孤雌胚、体外培养胚与体内胚H3K9乙酰化模式的比较

Comparative analysis of H3K9 acetylation level in parthenogenetic, and in vitro and in vivo developed mouse embryos

孤雌胚胎的发育率比体内体外生成胚胎的发育率要慢,为研究小鼠孤雌胚、体外培养胚H3K9乙酰化(H3K9ac)模式与体内自然胚之间的差异、曲古抑菌素A(Trichostatin,TSA)对孤雌胚H3K9乙酰化模式的影响及表观遗传模式对孤雌胚、体外培养胚发育的影响,文章采用间接免疫荧光法对小鼠植入前各时期孤雌胚、体外培养胚及体内自然胚基因组组蛋白的H3K9乙酰化水平进行检测。结果显示,植入前各时期孤雌胚H3K9乙酰化模式与体内组变化趋势基本一致,但平均荧光强度较体内组普遍偏高;经TSA处理后孤雌胚H3K9乙酰化水平有所提高,原核期至8-细胞期差异显著(P<0.05)。体外培养胚H3K9乙酰化荧光强度与体内组变化趋势也基本一致,但平均荧光强度较体内组普遍偏低。以上结果表明,小鼠孤雌胚H3K9乙酰化水平高于体内胚,使植入前胚胎发育过程中本应沉默的基因启动子发生超乙酰化,进而抑制胚胎发育,这可能是造成孤雌胚胎发育能力较差的重要原因之一;TSA处理可以部分弥补体外培养环境对胚胎发育带来的伤害,但TSA提高孤雌胚的发育能力可能并不完全是通过改变H3K9乙酰化水平来实现的。

The developmental rate of parthenogenetic embryos is slower than that of embryos generated in vitro and in vivo. To detect the effects of epigenetic modification on embryo development, we compared the H3K9 acetyla-tion level in these three types of embryos as well as parthenogenetic embryos treated with a histone deacetylase in-hibitor trichostatin （TSA） by indirect immunofluorescence. Our results showed that fluctuations in the level of acety-lated H3K9 detected during embryo development are similar among different types of mouse embryos. However, the level of H3K9 acetylation in parthenogenetic embryos is significantly higher while the level in embryos generated in＆amp;nbsp;vitro is lower when compared with that in embryos derived from in vivo. Treatment of parthenogenetic embryos with TSA increases the developmental rate but further elevates the level of H3K9 acetylation, especially from pronuclear to 8-cell stages. These results suggest that the promoters of genes that should be silenced during pre-implantation embryo development may be hyperacetylated in parthenogenetic embryos which inhibit normal embryo development. However, the positive effect of TSA on embryo development is not through altering the H3K9 acetylation level.