Mak Winifred, Nesterova Tatyana B, de Napoles Mariana, Appanah Ruth, Yamanaka Shinya, Otte Arie P, Brockdorff Neil
X inactivation group, MRC Clinical Sciences Centre, ICSM, Hammersmith Hospital, London, W12 0NN, UK.
Science. 2004 Jan 30;303(5658):666-9. doi: 10.1126/science.1092674.
It is generally accepted that paternally imprinted X inactivation occurs exclusively in extraembryonic lineages of mouse embryos, whereas cells of the embryo proper, derived from the inner cell mass (ICM), undergo only random X inactivation. Here we show that imprinted X inactivation, in fact, occurs in all cells of early embryos and that the paternal X is then selectively reactivated in cells allocated to the ICM. This contrasts with more differentiated cell types where X inactivation is highly stable and generally irreversible. Our observations illustrate that an important component of genome plasticity in early development is the capacity to reverse heritable gene silencing decisions.
一般认为，父源印记X染色体失活仅发生在小鼠胚胎的胚外谱系中，而源自内细胞团（ICM）的胚胎自身细胞仅经历随机X染色体失活。在此我们表明，事实上印记X染色体失活发生在早期胚胎的所有细胞中，并且父源X染色体随后在分配到内细胞团的细胞中被选择性重新激活。这与更分化的细胞类型形成对比，在这些细胞类型中X染色体失活高度稳定且通常不可逆。我们的观察结果表明，早期发育中基因组可塑性的一个重要组成部分是逆转可遗传基因沉默决定的能力。
