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Open Access Highly Accessed Research article

Inactivation of nucleolin leads to nucleolar disruption, cell cycle arrest and defects in centrosome duplication

Iva Ugrinova12, Karine Monier2, Corinne Ivaldi12, Marc Thiry3, Sébastien Storck12, Fabien Mongelard12 and Philippe Bouvet12*

Author Affiliations

1 Laboratory Joliot-Curie, CNRS USR 3010, University of Lyon, Ecole Normale Supérieure de Lyon, 46 Allée d'Italie, Lyon, France

2 Laboratory of molecular biology of the cell, CNRS UMR 5239, IFR128 Biosciences, University of Lyon, Ecole Normale Supérieure de Lyon, 46 Allée d'Italie, Lyon, France

3 Laboratory of Cell Biology, Department of Life Sciences, Faculty of Sciences, University of Liege, Liege, Belgium

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BMC Molecular Biology 2007, 8:66  doi:10.1186/1471-2199-8-66

Published: 10 August 2007

Abstract

Background

Nucleolin is a major component of the nucleolus, but is also found in other cell compartments. This protein is involved in various aspects of ribosome biogenesis from transcription regulation to the assembly of pre-ribosomal particles; however, many reports suggest that it could also play an important role in non nucleolar functions. To explore nucleolin function in cell proliferation and cell cycle regulation we used siRNA to down regulate the expression of nucleolin.

Results

We found that, in addition to the expected effects on pre-ribosomal RNA accumulation and nucleolar structure, the absence of nucleolin results in a cell growth arrest, accumulation in G2, and an increase of apoptosis. Numerous nuclear alterations, including the presence of micronuclei, multiple nuclei or large nuclei are also observed. In addition, a large number of mitotic cells showed a defect in the control of centrosome duplication, as indicated by the presence of more than 2 centrosomes per cell associated with a multipolar spindle structure in the absence of nucleolin. This phenotype is very similar to that obtained with the inactivation of another nucleolar protein, B23.

Conclusion

Our findings uncovered a new role for nucleolin in cell division, and highlight the importance of nucleolar proteins for centrosome duplication.