Higher concentrations of histone macroH2A in the Barr body are correlated with higher nucleosome density

Curr Biol. 2000 Nov 30;10(23):1531-4. doi: 10.1016/s0960-9822(00)00832-0.


Histone macroH2A, which is a subtype of histone H2A, possesses a histone H2A-like portion fused to a relatively long non-histone portion. MacroH2A has been shown to associate preferentially with the inactive X chromosome [1]. To investigate the specificity of this association, the nuclear distribution of macroH2A was compared with that of regular core histones. In normal human female fibroblasts, all anti-histone antibodies that were tested (including anti-macroH2A antibody) preferentially labeled the inactive X chromosome. Moreover, when expressed as green fluorescent protein (GFP) fusions, both histone H2A and macroH2A were concentrated in the Barr body. These data clearly show the presence of a higher density of nucleosomes in the inactive X chromosome. Accordingly, the specificity of the macroH2A association with the inactive X chromosome should be reconsidered. While investigating the role of macroH2A, we found that the proximity of the non-histone region of macroH2A to a promoter could lead to a specific repression of transcription, suggesting that the incorporation of macroH2A into chromatin might help to establish the stable pattern of gene expression in differentiated cells.

MeSH terms

  • Female
  • Fibroblasts
  • Histones / genetics
  • Histones / metabolism*
  • Humans
  • In Situ Hybridization, Fluorescence
  • Nucleosomes / metabolism*
  • RNA Probes
  • RNA, Long Noncoding
  • RNA, Untranslated / genetics
  • RNA, Untranslated / metabolism
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism
  • Sex Chromatin / genetics
  • Sex Chromatin / metabolism*
  • Transcription Factors / genetics
  • Transcription Factors / metabolism
  • X Chromosome / metabolism*


  • Histones
  • Nucleosomes
  • RNA Probes
  • RNA, Long Noncoding
  • RNA, Untranslated
  • Recombinant Fusion Proteins
  • Transcription Factors
  • XIST non-coding RNA
  • macroH2A histone