The Dynamics of Postmitotic Reassembly of the Nucleolus

• Published in: The Journal of cell biology Vol. 150; no. 3; pp. 433 - 446
• Main Authors: Dundr, Miroslav, Misteli, Tom, Mark O. J. Olson
• Format: Journal Article
• Language: English
• Published: United States Rockefeller University Press 07-08-2000; The Rockefeller University Press
• Subjects: Anaphase; Animals; Antibodies; Cell division; Cell nucleolus; Cell Nucleolus - physiology; Cell Nucleolus - ultrastructure; Cell Nucleus - ultrastructure; Cells; Cells, Cultured; Cellular biology; Chromosomal Proteins, Non-Histone - genetics; Chromosomal Proteins, Non-Histone - isolation & purification; Daughter cells; Deoxyribonucleic acid; DNA; Fluorescence; Green Fluorescent Proteins; Luminescent Proteins - genetics; Mitosis; Mitosis - physiology; Nuclear proteins; Nuclear Proteins - genetics; Nuclear Proteins - isolation & purification; Nucleophosmin; Original; Proteins; Recombinant Fusion Proteins; Ribonucleic acid; RNA; RNA Precursors - metabolism; RNA Processing, Post-Transcriptional; RNA, Ribosomal - metabolism; Telophase; Telophase - physiology
• ISSN: 0021-9525; 1540-8140
• DOI: 10.1083/jcb.150.3.433

Mammalian cell nucleoli disassemble at the onset of M-phase and reassemble during telophase. Recent studies showed that partially processed preribosomal RNA (pre-rRNA) is preserved in association with processing components in the perichromosomal regions (PRs) and in particles called nucleolus-derived foci (NDF) during mitosis. Here, the dynamics of nucleolar reassembly were examined for the first time in living cells expressing fusions of the processing-related proteins fibrillarin, nucleolin, or B23 with green fluorescent protein (GFP). During telophase the NDF disappeared with a concomitant appearance of material in the reforming nuclei. Prenucleolar bodies (PNBs) appeared in nuclei in early telophase and gradually disappeared as nucleoli formed, strongly suggesting the transfer of PNB components to newly forming nucleoli. Fluorescence recovery after photobleaching (FRAP) showed that fibrillarin-GFP reassociates with the NDF and PNBs at rapid and similar rates. The reentry of processing complexes into telophase nuclei is suggested by the presence of pre-rRNA sequences in PNBs. Entry of specific proteins into the nucleolus approximately correlated with the timing of processing events. The mitotically preserved processing complexes may be essential for regulating the distribution of components to reassembling daughter cell nucleoli.