X-inactivation is stably maintained in mouse embryos deficient for histone methyl transferase G9a

Genesis. 2004 Nov;40(3):151-6. doi: 10.1002/gene.20077.


One of the two X chromosomes becomes inactivated during early development of female mammals. Recent studies demonstrate that the inactive X chromosome is rich in histone H3 methylated at Lys-9 and Lys-27, suggesting an important role for these modifications in X-inactivation. It has been shown that in the mouse Eed is required for maintenance of X-inactivation in the extraembryonic lineages. Interestingly, Eed associates with Ezh2 to form a complex possessing histone methyltransferase activity predominantly for H3 Lys-27. We previously showed that G9a is one of the histone methyltransferases specific for H3 Lys-9 and is essential for embryonic development. Here we examined X-inactivation in mouse embryos deficient for G9a. Expression of Xist, which is crucial for the initiation of X-inactivation, was properly regulated and the inactivated X chromosome was stably maintained even in the absence of G9a. These results demonstrate that G9a is not essential for X-inactivation.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Crosses, Genetic
  • Dosage Compensation, Genetic*
  • Embryo, Mammalian / enzymology*
  • Female
  • Gene Targeting
  • Green Fluorescent Proteins / genetics
  • Green Fluorescent Proteins / physiology
  • Histone Methyltransferases
  • Histone-Lysine N-Methyltransferase / deficiency*
  • Histone-Lysine N-Methyltransferase / genetics
  • Homozygote
  • Humans
  • Male
  • Methylation
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Mice, Transgenic
  • Protein Methyltransferases
  • RNA, Long Noncoding
  • RNA, Untranslated / metabolism
  • X Chromosome / metabolism*


  • RNA, Long Noncoding
  • RNA, Untranslated
  • XIST non-coding RNA
  • enhanced green fluorescent protein
  • Green Fluorescent Proteins
  • Histone Methyltransferases
  • Protein Methyltransferases
  • Histone-Lysine N-Methyltransferase