Higher concentrations of histone macroH2A in the Barr body are correlated with higher nucleosome density.
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.
Perche
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PY
Equipe, DyOGen, Institut Albert Bonniot, Faculté de Médecine, et Laboratoire de Biologie Moléculaire et Cellulaire de la Différenciation, INSERM U309, Domaine de la Merci, 38706,., La Tronche Cedex, France.
Vourc'h
C
C
Konecny
L
L
Souchier
C
C
Robert-Nicoud
M
M
Dimitrov
S
S
Khochbin
S
S
D005260:Female; D005347:Fibroblasts; D006657:Histones / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D009707:Nucleosomes / Q000378:metabolism*; D015347:RNA Probes; D062085:RNA, Long Noncoding; D022661:RNA, Untranslated / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012728:Sex Chromatin / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D014960:X Chromosome / Q000378:metabolism*
D006657:Histones; D009707:Nucleosomes; D015347:RNA Probes; D062085:RNA, Long Noncoding; D022661:RNA, Untranslated; D011993:Recombinant Fusion Proteins; D014157:Transcription Factors; C077885:XIST non-coding RNA; C120756:macroH2A histone