Imprinted X inactivation maintained by a mouse Polycomb group gene

Nat Genet. 2001 Aug;28(4):371-5. doi: 10.1038/ng574.


In mammals, dosage compensation of X-linked genes is achieved by the transcriptional silencing of one X chromosome in the female (reviewed in ref. 1). This process, called X inactivation, is usually random in the embryo proper. In marsupials and the extra-embryonic region of the mouse, however, X inactivation is imprinted: the paternal X chromosome is preferentially inactivated whereas the maternal X is always active. Having more than one active X chromosome is deleterious to extra-embryonic development in the mouse. Here we show that the gene eed (embryonic ectoderm development), a member of the mouse Polycomb group (Pc-G) of genes, is required for primary and secondary trophoblast giant cell development in female embryos. Results from mice carrying a paternally inherited X-linked green fluorescent protein (GFP) transgene implicate eed in the stable maintenance of imprinted X inactivation in extra-embryonic tissues. Based on the recent finding that the Eed protein interacts with histone deacetylases, we suggest that this maintenance activity involves hypoacetylation of the inactivated paternal X chromosome in the extra-embryonic tissues.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Acetylation
  • Animals
  • Cell Count
  • Crosses, Genetic
  • Dosage Compensation, Genetic*
  • Female
  • Genomic Imprinting / genetics*
  • Green Fluorescent Proteins
  • Histone Deacetylases / metabolism
  • Homozygote
  • Luminescent Proteins / biosynthesis
  • Luminescent Proteins / genetics
  • Male
  • Mice
  • Mice, Transgenic
  • Multigene Family
  • Placenta / cytology
  • Placenta / metabolism
  • Placental Lactogen / biosynthesis
  • Polycomb Repressive Complex 2
  • Polycomb-Group Proteins
  • Repressor Proteins / genetics*
  • Repressor Proteins / metabolism*
  • Sex Factors
  • Transgenes
  • Trophoblasts / cytology
  • Trophoblasts / metabolism*


  • Eed protein, mouse
  • Luminescent Proteins
  • Polycomb-Group Proteins
  • Repressor Proteins
  • Green Fluorescent Proteins
  • placental lactogen I, rat
  • Placental Lactogen
  • Polycomb Repressive Complex 2
  • Histone Deacetylases