Reactivation of the Paternal X Chromosome in Early Mouse Embryos

• Published in: Science (American Association for the Advancement of Science) Vol. 303; no. 5658; pp. 666 - 669
• Main Authors: Mak, Winifred, Nesterova, Tatyana B., de Napoles, Mariana, Appanah, Ruth, Yamanaka, Shinya, Otte, Arie P., Brockdorff, Neil
• Format: Journal Article
• Language: English
• Published: Washington, DC American Association for the Advancement of Science 30.01.2004; The American Association for the Advancement of Science
• Subjects: Acetylation; Animals; Biological and medical sciences; Blastocyst; Blastocyst - physiology; Cell Cycle Proteins - genetics; Cell Cycle Proteins - metabolism; Chemical properties; Chromosomal Proteins, Non-Histone - genetics; Chromosomal Proteins, Non-Histone - metabolism; Chromosomes, Mammalian - physiology; Dosage Compensation, Genetic; Embryo, Mammalian - physiology; Embryology: invertebrates and vertebrates. Teratology; Embryonic and Fetal Development; Embryonic stem cells; Embryos; Female; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation, Developmental; Gene silencing; Genes; Genetics; Genomic Imprinting; Histones - metabolism; inner cell mass; Male; Methylation; Mice; Mice, Inbred C57BL; Mice, Inbred CBA; Molecular embryology; Morula; Morula - physiology; Optical focus; Physiological aspects; Pluripotent stem cells; Polycomb Repressive Complex 2; Proteins - genetics; Proteins - metabolism; Repressor Proteins - genetics; Repressor Proteins - metabolism; RNA; RNA, Long Noncoding; RNA, Untranslated - genetics; RNA, Untranslated - metabolism; Rodents; Scoring; Somatic cells; Stem cells; X chromosome; X Chromosome - physiology; X Chromosome inactivation; United Kingdom; Netherlands; Japan; Vertebrata; Embryo; Mammalia; Mouse; Rodentia; Plasticity; Development; Paternal effect; X-Chromosome; Genome; Inactivation; Inner cell mass
• ISSN: 0036-8075; 1095-9203
• 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.