早期胚胎发育合子基因组激活调控

动物早期胚胎发育始于分化成熟的雌雄配子经受精后重编程为全能性合子。在胚胎发育的初期,合子基因组的转录水平处于静默状态,母源物质调控占据主导地位。随着胚胎发育的进行,母源物质会经历分阶段的降解,合子基因组开始逐渐激活转录,标志着早期胚胎发育从母源性调控向合子基因组调控的转变,也称为母源-合子转换（maternal-zygotic transition,MZT）。其中一个关键的转折性事件就是合子基因组激活（zygotic genome activation,ZGA）,ZGA的正确发生对于早期胚胎发育和细胞命运决定至关重要。然而,目前对于ZGA的调控因子和具体的分子机制仍知之甚少。研究表明,ZGA在不同物种中存在较大差异,可能受到DNA甲基化、组蛋白修饰、非编码RNA、染色质重塑以及ZGA相关因子等多种调控因素的影响。本文探讨了上述几种调控因素影响合子基因组激活的研究进展,对进一步研究早期胚胎ZGA的相关机制具有借鉴意义。     

H1oo在哺乳动物胚胎发育及其基因组重编程中的作用

染色质结构可由转录抑制状态转变为转录激活状态,从而调节早期胚胎由母型基因控制转变为合子型基因控制。作为一种特殊类型的连接组蛋白——哺乳动物特异性连接组蛋白H1oo,其表达方式具有一定的时序性,但又与其他7种连接组蛋白亚型有所不同,H1oo不但能够在卵母细胞．胚胎发育转换过程中发挥功能,而且还可能在基因组重编程过程中起到关键性作用。分析研究卵母细胞特异性连接组蛋白,有助于认识染色质重构建、基因组重编程过程以及核移植的分子机制,而且可能对克隆效率的提高有所补益。     

Regulation of zygotic gene activation in the mouse

Zygotic gene activation (ZGA) is the critical event that governs the transition from maternal to embryonic control of development. In the mouse, ZGA occurs during the 2-cell stage and appears to be regulated by the time following fertilization, i.e. a zygotic clock, rather than by progression through the first cell cycle. The onset of ZGA must depend on maternally inherited proteins, and post-translational modification of these maternally derived proteins is likely to play a role in ZGA. Consistent with this prediction is that protein phosphorylation catalyzed by the cAMP-dependent protein kinase is involved in ZGA and that protein synthesis is not required for ZGA. Recent results suggest that ZGA may occur earlier than previously thought, i.e. not during the 2-cell stage, but rather in G₂ of the 1-cell embryo. Thus ZGA may comprise a period of minor gene activation in the 1-cell embryo that is followed by a period of major gene activation in the 2-cell embryo. Following ZGA, the expression of constitutively activated genes may require an enhancer.