Reproduction of the FC/DFC units in nucleoli

Smirnov, Evgeny; Hornáček, Matúš; Kováčik, Ľubomír; Mazel, Tomáš; Schröfel, Adam; Svidenská, Silvie; Skalnı́ková, Magdalena; Bártová, Eva; Cmarko, Dušan; Raška, Ivan

doi:10.1080/19491034.2016.1157674

Cited by 22 publications

(23 citation statements)

References 56 publications

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“…In the control the incorporated FU is accumulated predominantly in the nucleolar beads which, according to our earlier study, [55] correspond to the FC/DFC units of the nucleoli (Fig 1). The transcription signal in the nucleoplasm appeared as multiple small foci of much lower intensity.…”

Section: Effects Of Low Temperature On the Nucleolar Transcriptionsupporting

confidence: 67%

“…BrUTP (Sigma) was introduced into cells by the scratch procedure. [55,56] Here we followed the same procedure as for the labelling of replication in the cited works. Briefly, the cells were grown on the coverslips; a drop of medium containing 20μg/ml BrUTP was applied upon each coverslip; then the latter was scratched by the tip of a syringe needle and incubated for 5 min at 37˚C.…”

Section: Labeling Of the Transcription Sitesmentioning

confidence: 99%

“…Since incorporation of FU is preceded by its penetration in the cell and phosphorylation, we performed an additional experiment with another RNA predecessor, BrUTP, which was introduced in the HeLa cells by the scratch procedure ( Fig 1B). [55,56] When cells were permeabilized by scratching in the presence of BrUTP for 5 min and then immediately fixed ( Fig 1B, left) or washed and incubated for further 10 min at +4˚C (Fig 1B, middle), there was no significant incorporation of the nucleotide. But when the permeabilization was followed by 10 min incubation in the normal conditions ( Fig 1B, right), the cells situated along the scratch track displayed the transcription signal in the nucleoli and nucleoplasm.…”

Section: Effects Of Low Temperature On the Nucleolar Transcriptionmentioning

confidence: 99%

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Discontinuous transcription of ribosomal DNA in human cells

et al. 2020

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Numerous studies show that various genes in all kinds of organisms are transcribed discontinuously, i.e. in short bursts or pulses with periods of inactivity between them. But it remains unclear whether ribosomal DNA (rDNA), represented by multiple copies in every cell, is also expressed in such manner. In this work, we synchronized the pol I activity in the populations of tumour derived as well as normal human cells by cold block and release. Our experiments with 5-fluorouridine (FU) and BrUTP confirmed that the nucleolar transcription can be efficiently and reversibly arrested at +4˚C. Then using special software for analysis of the microscopic images, we measured the intensity of transcription signal (incorporated FU) in the nucleoli at different time points after the release. We found that the ribosomal genes in the human cells are transcribed discontinuously with periods ranging from 45 min to 75 min. Our data indicate that the dynamics of rDNA transcription follows the undulating pattern, in which the bursts are alternated by periods of rare transcription events.

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Section: Effects Of Low Temperature On the Nucleolar Transcriptionsupporting

confidence: 67%

Section: Labeling Of the Transcription Sitesmentioning

confidence: 99%

Section: Effects Of Low Temperature On the Nucleolar Transcriptionmentioning

confidence: 99%

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Discontinuous transcription of ribosomal DNA in human cells

et al. 2020

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“…Recently, it was reported that correlation of replication timing and Pol I occupancy suggests that a considerable subset of ribosomal genes remain transcriptionally silent from mid S phase to mitosis, but become again active in the postmitotic daughter cells (Smirnov et al 2016). …”

Section: Human Rdna Nucleolar Morphology and Rrna Transcriptionmentioning

confidence: 99%

Nucleolus and chromatin

Schöfer

Weipoltshammer

2018

Histochem Cell Biol

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The nucleolus as site of ribosome biogenesis holds a pivotal role in cell metabolism. It is composed of ribosomal DNA (rDNA), which is present as tandem arrays located in nucleolus organizer regions (NORs). In interphase cells, rDNA can be found inside and adjacent to nucleoli and the location is indicative for transcriptional activity of ribosomal genes—inactive rDNA (outside) versus active one (inside). Moreover, the nucleolus itself acts as a spatial organizer of non-nucleolar chromatin. Microscopy-based approaches offer the possibility to explore the spatially distinct localization of the different DNA populations in relation to the nucleolar structure. Recent technical developments in microscopy and preparatory methods may further our understanding of the functional architecture of nucleoli. This review will attempt to summarize the current understanding of mammalian nucleolar chromatin organization as seen from a microscopist’s perspective.

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“…For instance, it is still debatable whether rRNA transcription takes place at FC, DFC, or the border between FC and DFC (Raska et al, 1989;Cheutin et al, 2002;Huang, 2002;Koberna et al, 2002;Raska, 2003;Thiry and Lafontaine, 2005). Observations based on EM have built the foundation of nucleolus structure (Tao et al, 2002;Olson and Dundr, 2005;Derenzini et al, 2006;Cmarko et al, 2008;Thiry et al, 2011;Smirnov et al, 2016). Given that nucleolus is a highly dynamic structure, systematic investigation of nucleolar structure during the cell cycle is still urgently needed.…”

Section: Structural Dynamics Of Nucleolus During the Cell Cyclementioning

confidence: 99%

Disruption and restoration of nucleolar FC and DFC during S phase in HeLa cells

Guan¹,

Jiao²,

Li³

et al. 2017

Cell Biology International

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In the higher eukaryotic nucleolus, fibrillar centers (FCs), the dense fibrillar components (DFCs), and the granular components (GCs) are functional domains structurally relatively well-defined by electron microscopy (EM). However, ultrastructural alterations in FC, DFC, and GC during the cell cycle and their associated cellular functions are still largely unclear. Based on synchronized HeLa cells, we followed the structural dynamics of nucleolus during cell cycle by EM. We found that nucleolus structure shifted from tripartite to bipartite organization and FC/DFCs were reorganized in S phase with three distinct stages: (1) In early-S phase, FC/DFC structures were disassembled. (2) In mid-S phase, a transition from FC/DFC disruption to restoration occurred. As FC/DFC structures were completely disassembled, nucleoli became structurally homogenous. (3) In late-S phase, the number of small FC/DFCs increased and subsequently large FC/DFCs were constructed. Our data demonstrated that nucleolar FC/DFCs in interphase are presented in two different forms or states due to disassembly and reassembly. FC/DFCs in G1 are nucleolar structures constructed concomitantly with the establishment of nucleoli derived from the nucleolar organizer region (NOR). FC/DFCs in G2 are nucleolar components reconstituted after the global reassembly in mid-S phase. Dynamic nucleolus structures revealed in this study may serve as ultrastructural characteristics to reflect distinct stages of the cell cycle. By providing evidence for the temporal and spatial regulation of nucleolus, our findings contribute to the coupling of nucleolus structures to cell cycle dependent functions.

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Reproduction of the FC/DFC units in nucleoli

Cited by 22 publications

References 56 publications

Discontinuous transcription of ribosomal DNA in human cells

Discontinuous transcription of ribosomal DNA in human cells

Nucleolus and chromatin

Disruption and restoration of nucleolar FC and DFC during S phase in HeLa cells

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