伴随X染色体失活的甲基化修饰

The methylation modification accompanying X chromosome inactivation

X染色体失活(XCI)是哺乳动物X染色体基因剂量补偿作用的实现方式,是由失活的关键调节因子Xist RNA结合到X染色体上引发的。失活的X染色体(Xi)伴随有一系列的表观遗传修饰,包括组蛋白H3的甲基化、组蛋白H3和H4的去乙酰化、macroH2A的积聚和DNA甲基化。其中,组蛋白H3 Lys-9和27位点的甲基化修饰是两个独特的抑制型标记,在失活的起始和维持中起着相当重要的作用。DNA甲基化在失活状态的维持中也起到必不可少的作用。本文详细描述了X染色体失活过程中所伴随的甲基化修饰。

X chromosome inactivation （XCI） is the manner to achieve dosage compensation of genes on X chromosomes in mammals. XCI is controlled by the key regulation factor Xist RNA that coats the X chromosome in eis and triggers its silencing. The inactivated X chromosome （Xi） is characterized by a series of epigenetic modifications, including histone H3 methylation, histone H3 and H4 hypoaeetylation, enrichment of variant histone maeroH2A and DNA methylation, which play a key role during X chromosome inactivation. Histone H3 Lys-9 methylation and H3 Lys-27 methylation are two unique repressive marks, and required in the establishment and maintenance of XCI. DNA methylation also plays an essential role in the maintenance of XCI. Here we describe the modification of methylation in XCI in detail.