Regulation of Nucleolar Chromatin by B23/Nucleophosmin Jointly Depends upon Its RNA Binding Activity and Transcription Factor UBF

Miharu Hisaoka, Shuhei Ueshima, Kensaku Murano, Kyosuke Nagata, Mitsuru Okuwaki

Research output: Contribution to journalArticle

26 Citations (Scopus)

Abstract

Histone chaperones regulate the density of incorporated histone proteins around DNA transcription sites and therefore constitute an important site-specific regulatory mechanism for the control of gene expression. At present, the targeting mechanism conferring this site specificity is unknown. We previously reported that the histone chaperone B23/nucleophosmin associates with rRNA chromatin (r-chromatin) to stimulate rRNA transcription. Here, we report on the mechanism for site-specific targeting of B23 to the r-chromatin. We observed that, during mitosis, B23 was released from chromatin upon inactivation of its RNA binding activity by cdc2 kinase-mediated phosphorylation. The phosphorylation status of B23 was also shown to strongly affect its chromatin binding activity. We further found that r-chromatin binding of B23 was a necessary condition for B23 histone chaperone activity in vivo. In addition, we found that depletion of upstream binding factor (UBF; an rRNA transcription factor) decreased the chromatin binding affinity of B23, which in turn led to an increase in histone density at the r-chromatin. These two major strands of evidence suggest a novel cell cycle-dependent mechanism for the site-specific regulation of histone density via joint RNA- and transcription factor-mediated recruitment of histone chaperones to specific chromosome loci.

Original languageEnglish
Pages (from-to)4952-4964
Number of pages13
JournalMolecular and Cellular Biology
Volume30
Issue number20
DOIs
Publication statusPublished - 2010 Oct
Externally publishedYes

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Chromatin
Histone Chaperones
RNA
Histones
Phosphorylation
nucleophosmin
transcription factor UBF
Mitosis
Cell Cycle
Transcription Factors
Phosphotransferases
Chromosomes
Joints
Gene Expression
DNA
Proteins

ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology

Cite this

Regulation of Nucleolar Chromatin by B23/Nucleophosmin Jointly Depends upon Its RNA Binding Activity and Transcription Factor UBF. / Hisaoka, Miharu; Ueshima, Shuhei; Murano, Kensaku; Nagata, Kyosuke; Okuwaki, Mitsuru.

In: Molecular and Cellular Biology, Vol. 30, No. 20, 10.2010, p. 4952-4964.

Research output: Contribution to journalArticle

Hisaoka, Miharu ; Ueshima, Shuhei ; Murano, Kensaku ; Nagata, Kyosuke ; Okuwaki, Mitsuru. / Regulation of Nucleolar Chromatin by B23/Nucleophosmin Jointly Depends upon Its RNA Binding Activity and Transcription Factor UBF. In: Molecular and Cellular Biology. 2010 ; Vol. 30, No. 20. pp. 4952-4964.
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