title: X-inactivation and X-reactivation: epigenetic hallmarks of mammalian reproduction and pluripotent stem cells.
abstract: X-chromosome inactivation is an epigenetic hallmark of mammalian development. Chromosome-wide regulation of the X-chromosome is essential in embryonic and germ cell development. In the male germline, the X-chromosome goes through meiotic sex chromosome inactivation, and the chromosome-wide silencing is maintained from meiosis into spermatids before the transmission to female embryos. In early female mouse embryos, X-inactivation is imprinted to occur on the paternal X-chromosome, representing the epigenetic programs acquired in both parental germlines. Recent advances revealed that the inactive X-chromosome in both females and males can be dissected into two elements: repeat elements versus unique coding genes. The inactive paternal X in female preimplantation embryos is reactivated in the inner cell mass of blastocysts in order to subsequently allow the random form of X-inactivation in the female embryo, by which both Xs have an equal chance of being inactivated. X-chromosome reactivation is regulated by pluripotency factors and also occurs in early female germ cells and in pluripotent stem cells, where X-reactivation is a stringent marker of naive ground state pluripotency. Here we summarize recent progress in the study of X-inactivation and X-reactivation during mammalian reproduction and development as well as in pluripotent stem cells.
authors.affiliation: Department of Genetics, Harvard Medical School, Boston, MA, USA. payer@molbio.mgh.harvard.edu
authors.forename: Bernhard
authors.initials: B
authors.lastname: Payer
authors.forename: Jeannie T
authors.initials: JT
authors.lastname: Lee
authors.forename: Satoshi H
authors.initials: SH
authors.lastname: Namekawa
mesh_terms: D000818:Animals; D044127:Epigenesis, Genetic / Q000235:genetics / Q000502:physiology*; D005260:Female; D018392:Genomic Imprinting / Q000502:physiology*; D005854:Germ Cells / Q000502:physiology*; D006801:Humans; D008297:Male; D008322:Mammals; D008954:Models, Biological; D039904:Pluripotent Stem Cells / Q000502:physiology*; D062085:RNA, Long Noncoding; D022661:RNA, Untranslated / Q000502:physiology; D013045:Species Specificity; D014960:X Chromosome / Q000235:genetics / Q000502:physiology*; D049951:X Chromosome Inactivation / Q000235:genetics / Q000502:physiology*
chemical_list: D062085:RNA, Long Noncoding; D022661:RNA, Untranslated; C077885:XIST non-coding RNA