Stalled RNAP-II molecules bound to non-coding rDNA spacers are required for normal nucleolus architecture

Authors

  • M. A. Freire-Picos,

    1. MRC Clinical Sciences Centre, Imperial College, London, UK
    2. Department of Molecular and Cellular Biology, University of A Coruña (UDC), Coruña, Spain
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  • V. Landeira-Ameijeiras,

    1. MRC Clinical Sciences Centre, Imperial College, London, UK
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    • Present address: Biomedical Research Centre (INIBIC), CH Universitario A Coruña, 15006 A Coruña, Spain
  • María D. Mayán

    Corresponding author
    • MRC Clinical Sciences Centre, Imperial College, London, UK
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    • Present address: Biomedical Research Centre (INIBIC), CH Universitario A Coruña, 15006 A Coruña, Spain

Correspondence to: M. D. Mayan, Division of Rheumatology, Cartilage Biology Research Group, Biomedical Research Centre (INIBIC), CHUAC. Xubias de Arriba, 84 15006, A Coruña, Spain.

E-mail: MA.Dolores.Mayan.Santos@sergas.es

Abstract

The correct distribution of nuclear domains is critical for the maintenance of normal cellular processes such as transcription and replication, which are regulated depending on their location and surroundings. The most well-characterized nuclear domain, the nucleolus, is essential for cell survival and metabolism. Alterations in nucleolar structure affect nuclear dynamics; however, how the nucleolus and the rest of the nuclear domains are interconnected is largely unknown. In this report, we demonstrate that RNAP-II is vital for the maintenance of the typical crescent-shaped structure of the nucleolar rDNA repeats and rRNA transcription. When stalled RNAP-II molecules are not bound to the chromatin, the nucleolus loses its typical crescent-shaped structure. However, the RNAP-II interaction with Seh1p, or cryptic transcription by RNAP-II, is not critical for morphological changes. Copyright © 2013 John Wiley & Sons, Ltd.

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