, Volume 123, Issue 1–2, pp 117–128

Reactivation of Х chromosome upon reprogramming leads to changes in the replication pattern and 5hmC accumulation

  • Alexandra N. Bogomazova
  • Maria A. Lagarkova
  • Alexandra V. Panova
  • Evgueny D. Nekrasov
  • Sergey L. Kiselev
Research Article


Once set, the inactive status of the X chromosome in female somatic cells is preserved throughout subsequent cell divisions. The inactive status of the X chromosome is characterized by many features, including late replication. In contrast to induced pluripotent stem cells (iPSCs) in mice, the X chromosome in human female iPSCs usually remains inactive after reprogramming of somatic cells to the pluripotent state, although recent studies point to the possibility of reactivation of the X chromosome. Here, we demonstrated that, during reprogramming, the inactive X chromosome switches from late to synchronous replication, with restoration of the transcription of previously silenced genes. This process is accompanied by accumulation of a new epigenetic mark or intermediate of the DNA demethylation pathway, 5-hydroxymethylcytosine (5hmC), on the activated X chromosome. Our results indicate that the active status of the X chromosome is better confirmed by early replication and the reappearance of 5hmC, rather than by appearance of histone marks of active chromatin, removal of histone marks of inactive chromatin, or an absence of XIST coating.









Embryonic stem cells


Induced pluripotent stem cells


Fluorescence in situ hybridization


Active X chromosome


Inactive X chromosome

Supplementary material

412_2013_433_MOESM1_ESM.pdf (848 kb)
ESM 1(PDF 848 kb)


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Copyright information

© Springer-Verlag Berlin Heidelberg 2013

Authors and Affiliations

  • Alexandra N. Bogomazova
    • 1
  • Maria A. Lagarkova
    • 1
  • Alexandra V. Panova
    • 1
  • Evgueny D. Nekrasov
    • 1
  • Sergey L. Kiselev
    • 1
  1. 1.Vavilov Institute of General GeneticsRussian Academy of SciencesMoscowRussia

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