Epigenetic Dynamics of Imprinted X Inactivation During Early Mouse Development

  title={Epigenetic Dynamics of Imprinted X Inactivation During Early Mouse Development},
  author={Ikuhiro Okamoto and Arie Pieter Otte and C. David Allis and Danny Reinberg and Edith Heard},
  pages={644 - 649}
The initiation of X-chromosome inactivation is thought to be tightly correlated with early differentiation events during mouse development. Here, we show that although initially active, the paternal X chromosome undergoes imprinted inactivation from the cleavage stages, well before cellular differentiation. A reversal of the inactive state, with a loss of epigenetic marks such as histone modifications and polycomb proteins, subsequently occurs in cells of the inner cell mass (ICM), which give… 
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As model systems for epigenetic regulation, genomic imprinting and X-chromosome inactivation have identified and elucidated the numerous regulatory mechanisms that function throughout the genome during development.
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A picture is emerging whereby initial epigenetic asymmetry between the two parental X chromosomes is reprogrammed in a lineage specific manner resulting in a switch from imprinted to random inactivation in embryonic derivatives.
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The recent discovery of the plasticity of the inactive state during early development, or during cloning, and induced pluripotency have contributed to the X chromosome becoming a gold standard in reprogramming studies.
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