在干细胞分化及X-染色体失活（使一个雌性X-染色体沉默、以确保两性之间基因剂量对等的过程）期间，染色质发生表观遗传重新编程而锁定在一个新状态。 将分化的细胞重新编程为“iPS细胞”还会使失活的X-染色体被重新激活，而且曾有人提出，多能因子Oct4联系着这两个过程。
在这项研究中，Donohue等人发现，Oct4通过触发X染色体配对和计数来调控X-染色体失活。Oct4与非编码RNA（Tsix 和 Xite）和蛋白（Ctcf 和Yy1）都发生相互作用。这项工作表明，干细胞中的X-染色体的表观遗传重新编程涉及一个复杂的网络。（生物谷Bioon.com）
生物谷推荐原始出处：
Nature 460, 128-132 (2 July 2009) | doi:10.1038/nature08098
The pluripotency factor Oct4 interacts with Ctcf and also controls X-chromosome pairing and counting
Mary E. Donohoe1,2,3,5,6, Susana S. Silva1,2,3,5, Stefan F. Pinter1,2,3, Na Xu1,2,3 & Jeannie T. Lee1,2,3,4
1 Howard Hughes Medical Institute,
2 Department of Molecular Biology, Massachusetts General Hospital,
3 Department of Genetics, Harvard Medical School,
4 Department of Pathology, Massachusetts General Hospital, Boston, Massachusetts 02114, USA
5 These authors contributed equally to this work.
6 Present address: Burke Medical Research Institute, Weill Cornell Medical College, White Plains, New York 10605, USA.
Pluripotency of embryonic stem (ES) cells is controlled by defined transcription factors1, 2. During differentiation, mouse ES cells undergo global epigenetic reprogramming, as exemplified by X-chromosome inactivation (XCI) in which one female X chromosome is silenced to achieve gene dosage parity between the sexes3, 4, 5. Somatic XCI is regulated by homologous X-chromosome pairing6, 7 and counting8, 9, 10, and by the random choice of future active and inactive X chromosomes. XCI and cell differentiation are tightly coupled11, as blocking one process compromises the other8, 12 and dedifferentiation of somatic cells to induced pluripotent stem cells is accompanied by X chromosome reactivation2. Recent evidence suggests coupling of Xist expression to pluripotency factors occurs13, but how the two are interconnected remains unknown. Here we show that Oct4 (also known as Pou5f1)14 lies at the top of the XCI hierarchy, and regulates XCI by triggering X-chromosome pairing and counting. Oct4 directly binds Tsix and Xite, two regulatory noncoding RNA genes of the X-inactivation centre15, 16, and also complexes with XCI trans-factors, Ctcf and Yy1 (ref. 17), through protein–protein interactions. Depletion of Oct4 blocks homologous X-chromosome pairing and results in the inactivation of both X chromosomes in female cells. Thus, we have identified the first trans-factor that regulates counting, and ascribed new functions to Oct4 during X-chromosome reprogramming.
