Stop-and-Go: Dynamics of Nucleolar Transcription During the Cell Cycle

Aishwarya Iyer-Bierhoff, Ingrid Grummt

Research output: Contribution to journalComment/debate

Abstract

Entry into mitosis correlates with nucleolar disassembly and shutdown of ribosomal RNA (rRNA) gene (rDNA) transcription. In telophase, nucleoli reform and transcription is reactivated. The molecular mechanisms underlying the dynamics of nucleolar transcription during the cell cycle are manifold. Although mitotic inactivation of the RNA polymerase I (Pol I) transcription machinery by posttranslational modifications has been extensively studied, little is known about the structure of rDNA chromatin during progression through mitosis. Methylation of histone H2A at glutamine 104 (H2AQ104me), a dedicated nucleolar histone modification, is lost in prometaphase, leading to chromatin compaction, which enforces mitotic repression of rRNA genes. At telophase, restoration of H2AQ104me is required for the activation of transcription. H2AQ104 methylation and chromatin dynamics are regulated by fibrillarin (FBL) and the NAD+-dependent nucleolar deacetylase sirtuin 7 (SIRT7). Deacetylation of FBL is required for the methylation of H2AQ104 and high levels of rDNA transcription during interphase. At the entry into mitosis, nucleoli disassemble and FBL is hyperacetylated, leading to loss of H2AQ104me, chromatin compaction, and shutdown of Pol I transcription. These results reveal that reversible acetylation of FBL regulates methylation of nucleolar H2AQ104, thereby reinforcing oscillation of Pol I transcription during the cell cycle.

Original languageEnglish (US)
JournalEpigenetics Insights
Volume12
DOIs
StatePublished - May 1 2019

Fingerprint

Transcription
Methylation
Chromatin
Cell Cycle
Ribosomal DNA
Cells
Mitosis
Telophase
Histone Code
Prometaphase
Interphase
Post Translational Protein Processing
Acetylation
Glutamine
rRNA Genes
NAD
Histones
Transcriptional Activation
Compaction
Genes

Keywords

  • H2AQ104 methylation
  • RNA polymerase I
  • SIRT7
  • acetylation
  • cell cycle
  • fibrillarin
  • rDNA
  • transcription

ASJC Scopus subject areas

  • Biochemistry
  • Genetics

Cite this

Stop-and-Go : Dynamics of Nucleolar Transcription During the Cell Cycle. / Iyer-Bierhoff, Aishwarya; Grummt, Ingrid.

In: Epigenetics Insights, Vol. 12, 01.05.2019.

Research output: Contribution to journalComment/debate

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