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Post-mitotic dynamics of pre-nucleolar bodies is driven by pre-rRNA processing
Coralie Carron1, Stéphanie Balor, Franck Delavoie
1Université de Toulouse, UPS, Laboratoire de Biologie Moléculaire Eucaryote, F-31000 Toulouse, France.
Journal of Cell Science
|July 7, 2012
Summary
Pre-nucleolar bodies (PNBs) are active ribosome factories, not just reservoirs. They resume pre-ribosomal RNA (pre-RNA) maturation after mitosis, driving their own disassembly once ribosome production is complete.
Area of Science:
- Cell Biology
- Molecular Biology
- Genetics
Background:
- Pre-nucleolar bodies (PNBs) are transient nuclear structures observed after mitosis.
- They are traditionally considered reservoirs for nucleolar factors.
- Their precise function in ribosome biogenesis remains unclear.
Purpose of the Study:
- To investigate the molecular function of PNBs during the cell cycle.
- To determine if PNBs are involved in ribosome biogenesis.
- To elucidate the role of PNBs in post-mitotic nucleolus reassembly.
Main Methods:
- Fluorescence in situ hybridization (FISH) in HeLa cells.
- Loss-of-function experiments to block pre-ribosomal RNA (pre-RNA) maturation.
- Correlative electron tomography to visualize PNB ultrastructure.
Main Results:
- PNBs actively process and mature pre-RNAs, resuming ribosome biogenesis after mitosis.
- Blocking pre-RNA maturation leads to stalled pre-ribosomes within PNBs.
- PNBs persist longer when pre-RNA maturation is inhibited, suggesting maturation drives their disassembly.
Conclusions:
- PNBs function as autonomous, extra-nucleolar sites for ribosome maturation.
- The disassembly of PNBs in G1 phase is linked to the completion of pre-ribosome maturation and release.
- This challenges the view of PNBs as simple reservoirs, highlighting their dynamic role in ribosome production.
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