Dynamics and three-dimensional localization of ribosomal RNA within the nucleolus

Thiry, Marc; Cheutin, Thierry; O’Donohue, Marie-Françoise; Kaplan, Hervé; Ploton, Dominique

doi:10.1017/s1355838200001564

Cited by 60 publications

(52 citation statements)

References 46 publications

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“…However, there was a gradual actinomycin D-dependent translocation of ADAR2 immunofluorescence from the nucleolus to the nucleoplasm and a nucleolar exclusion that appeared complete by 2 h (Fig. 2b Lower), a time course consistent with the processing and export of nascent rRNA from the nucleus (40). These results indicate that the localization of ADAR2 within nucleoli depends on the presence of rRNA.…”

Section: Adar2 Is Concentrated In the Nucleolusmentioning

confidence: 73%

Modulation of RNA editing by functional nucleolar sequestration of ADAR2

Sansam

Wells

Emeson

2003

Proc. Natl. Acad. Sci. U.S.A.

173

174

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The adenosine deaminases that act on RNA (ADARs) catalyze the site-specific conversion of adenosine to inosine (A to I) in primary mRNA transcripts, thereby affecting the splicing pattern or coding potential of mature mRNAs. Although the subnuclear localization of A-to-I editing has not been precisely defined, ADARs have been shown to act before splicing, suggesting that they function near nucleoplasmic sites of transcription. Here we demonstrate that ADAR2, a member of the vertebrate ADAR family, is concentrated in the nucleolus, a subnuclear domain disparate from the sites of mRNA transcription. Selective inhibition of ribosomal RNA synthesis or the introduction of mutations in the double-stranded RNAbinding domains within ADAR2 results in translocation of the protein to the nucleoplasm, suggesting that nucleolar association of ADAR2 depends on its ability to bind to ribosomal RNA. Fluorescence recovery after photobleaching reveals that ADAR2 can shuttle rapidly between subnuclear compartments. Enhanced translocation of endogenous ADAR2 from the nucleolus to the nucleoplasm results in increased editing of endogenous ADAR2 substrates. These observations indicate that the nucleolar localization of ADAR2 represents an important mechanism by which RNA editing can be modulated by the sequestration of enzymatic activity from potential RNA substrates in the nucleoplasm.T he conversion of adenosine to inosine (A to I) by RNA editing was first observed in yeast tRNAs (1) but has since been identified in numerous viral and cellular mRNA transcripts (2-4). A-to-I editing is most often identified as an adenosineto-guanosine (A-to-G) discrepancy between genomic and cDNA sequences due to the similar base-pairing properties of inosine and guanosine during cDNA synthesis. A-to-I conversion is catalyzed via hydrolytic deamination at the C6 position of the adenine ring (5) and requires an extended region of doublestranded RNA (dsRNA) in potential RNA substrates formed by intramolecular base-pairing interactions between exon and intron sequences (2-4). A family of adenosine deaminases that act on RNA (ADARs) have been extensively characterized and are responsible for catalyzing the site-specific A-to-I conversion observed in cellular mRNA transcripts (6-8). ADAR-mediated RNA editing events can change the amino acid coding potential of genomically encoded transcripts to produce protein products with altered functional properties (2, 3). For example, the editing of RNAs encoding mammalian ionotropic glutamate receptor (GluR) subunits can lead to the production of heteromeric glutamate-gated channels with altered ion permeation and agonist-induced desensitization kinetics (9-11), whereas the editing of transcripts encoding the 2C-subtype of serotonin receptor (5-HT 2C R) can generate receptor isoforms that couple to heterotrimeric G proteins with decreased efficiency (12-14). A-to-I editing events have also been described in nontranslated RNA species and noncoding regions of mRNA transcripts (15)(16)(17), suggesting that such modif...

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Section: Adar2 Is Concentrated In the Nucleolusmentioning

confidence: 73%

Modulation of RNA editing by functional nucleolar sequestration of ADAR2

Sansam

Wells

Emeson

2003

Proc. Natl. Acad. Sci. U.S.A.

173

174

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“…Notably, the distribution of Sl LHP1 at chromocenters was uneven, as it tends to occupy the pericentromeric region, leaving the center as a black hole ( Figure 2A, arrows in panels 3 and 4). Likewise, Sl LHP1 was localized at specific nucleolar compartments, excluding sphereshaped sites, which are reminiscent of fibrillar centers (Thiry et al, 2000). For comparison, we transiently expressed At LHP1 in Arabidopsis cells and found that its subnuclear localization generally resembled that of Sl LHP1 except for its absence from the nucleolus.…”

Section: Sl Lhp1-gfp Complemented the Lhp1 Mutantmentioning

confidence: 99%

Different Domains Control the Localization and Mobility of LIKE HETEROCHROMATIN PROTEIN1 inArabidopsisNuclei

Zemach

Ben-Meir

et al. 2005

The Plant Cell

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Plants possess a single gene for the structurally related HETEROCHROMATIN PROTEIN1 (HP1), termed LIKE-HP1 (LHP1). We investigated the subnuclear localization, binding properties, and dynamics of LHP1 proteins in Arabidopsis thaliana cells. Transient expression assays showed that tomato (Solanum lycopersicum) LHP1 fused to green fluorescent protein (GFP; Sl LHP1-GFP) and Arabidopsis LHP1 (At LHP1-GFP) localized to heterochromatic chromocenters and showed punctuated distribution within the nucleus; tomato but not Arabidopsis LHP1 was also localized within the nucleolus. Mutations of aromatic cage residues that recognize methyl K9 of histone H3 abolished their punctuated distribution and localization to chromocenters. Sl LHP1-GFP plants displayed cell type-dependent subnuclear localization. The diverse localization pattern of tomato LHP1 did not require the chromo shadow domain (CSD), whereas the chromodomain alone was insufficient for localization to chromocenters; a nucleolar localization signal was identified within the hinge region. Fluorescence recovery after photobleaching showed that Sl LHP1 is a highly mobile protein whose localization and retention are controlled by distinct domains; retention at the nucleolus and chromocenters is conferred by the CSD. Our results imply that LHP1 recruitment to chromatin is mediated, at least in part, through interaction with methyl K9 and that LHP1 controls different nuclear processes via transient binding to its nuclear sites.

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“…5) or FCs (Thiry et al, 2000;Cheutin et al, 2002) of somatic mammalian cells. Importantly, these diverging results have been obtained using basically the same techniques and also the same cell types.…”

Section: Rrna and Ribosome Biogenesis: Where In Nucleoli?mentioning

confidence: 99%

The nucleolus and transcription of ribosomal genes

Raška

Koberna

Malínský

et al. 2004

Biology of the Cell

125

111

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Ribosome biogenesis is a highly dynamic, steady-state nucleolar process that involves synthesis and maturation of rRNA, its transient interactions with non-ribosomal proteins and RNPs and assembly with ribosomal proteins. In the few years of the 21st century, an exciting progress in the molecular understanding of rRNA and ribosome biogenesis has taken place. In this review, we discuss the recent results on the regulation of rRNA synthesis in relation to the functional organization of the nucleolus, and put an emphasis on the situation encountered in mammalian somatic cells.

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Dynamics and three-dimensional localization of ribosomal RNA within the nucleolus

Cited by 60 publications

References 46 publications

Modulation of RNA editing by functional nucleolar sequestration of ADAR2

Modulation of RNA editing by functional nucleolar sequestration of ADAR2

Different Domains Control the Localization and Mobility of LIKE HETEROCHROMATIN PROTEIN1 inArabidopsisNuclei

The nucleolus and transcription of ribosomal genes

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