Characterization of AtNUC-L1 Reveals a Central Role of Nucleolin in Nucleolus Organization and Silencing of AtNUC-L2 Gene in Arabidopsis

Pontvianne, Frédéric; Matı́a, Isabel; Douet, Julien; Tourmente, Sylvette; Medina, F. Javier; Echeverrı́a, Manuel; Sáez‐Vasquez, Julio

doi:10.1091/mbc.e06-08-0751

Cited by 125 publications

(230 citation statements)

References 49 publications

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“…2). In spite of the phenotypic similarity of apum23 mutant to the "loss of function" mutants of nucleolin 1 (AtNuc-L1) [46][47][48] and ribosomal protein (RP) [49][50][51][52] genes, our microarray data showed the transcriptional upregulation of a portion of the RP genes, although the expression level of the AtNuc-L1 transcript did not change. However, AtNuc-L2, which is not expressed under normal growth conditions in wild-type plants, was greatly upregulated.…”

Section: Apum23 Is Required For Normal Growth Patterning and Developmmentioning

confidence: 91%

“…AtNuc-L1 is also required in pre-rRNA processing, similar to APUM23. 46,48 Hence, AtNuc-L2 appears to be upregulated to compensate for the reduced supply rate of rRNA. Upregulation of RP gene expression in the apum23 mutant also may be a feed-back mechanism to compensate either the reduced rate of ribosome assembly or the imbalance of ribosome subunits due to a limited supply of integral rRNAs.…”

Section: Apum23 Is Required For Normal Growth Patterning and Developmmentioning

confidence: 99%

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Pumilio Puf domain RNA-binding proteins in Arabidopsis

Abbasi

Park

Choi

2011

Plant Signaling & Behavior

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Section: Apum23 Is Required For Normal Growth Patterning and Developmmentioning

confidence: 91%

Section: Apum23 Is Required For Normal Growth Patterning and Developmmentioning

confidence: 99%

Pumilio Puf domain RNA-binding proteins in Arabidopsis

Abbasi

Park

Choi

2011

Plant Signaling & Behavior

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“…Since Ki-67 is also dispersed in nucleoli after nucleolin depletion, we hypothesize that the apparent nucleolar dispersions of these three proteins in nucleolin-depleted cells probably arise as a consequence of disorganization of the nucleolar structure. It has been reported that mutations in genes encoding nucleolin homologues in fission yeast (GAR2) and Arabidopsis (AtNUC-L1) have severe effects on the organization of nucleoli (Léger-Silvestre et al, 1997;Pontvianne et al, 2007). However, the function of nucleolin in the organization of nucleoli has not been reported in animal cells.…”

Section: Nucleolin Is Required For Nucleolus Formationmentioning

confidence: 99%

Nucleolin functions in nucleolus formation and chromosome congression

Matsunaga

Takata

et al. 2007

Journal of Cell Science

121

124

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A complex structure, designated the chromosome periphery, surrounds each chromosome during mitosis. Although several proteins have been shown to localize to the chromosome periphery, their functions during mitosis remain unclear. Here, we used a combination of highresolution microscopy and RNA-interference-mediated depletion to study the functions of nucleolin, a nucleolar protein localized at the chromosome periphery, in interphase and mitosis. During mitosis, nucleolin was localized in the peripheral region including the vicinity of the outer kinetochore of chromosomes. Staining with an antibody specific for nucleolin phosphorylated by CDC2 revealed that nucleolin was also associated with the spindle poles from prometaphase to anaphase. Nucleolin depletion resulted in disorganization of the nucleoli at interphase. Furthermore, nucleolin-depleted cells showed a prolonged cell cycle with misaligned chromosomes and defects in spindle organization. The misaligned chromosomes showed syntelic kinetochore-microtubule attachments with reduced centromere stretching. Taken together, our results indicate that nucleolin is required for nucleolus formation, and is also involved in chromosome congression and spindle formation. Journal of Cell Science 2092Nucleolin is an abundant nucleolar protein localized in the DFCs and GCs of nucleoli (Biqqioqera et al., 1990). Nucleolin plays essential roles in rDNA transcription, rRNA maturation, ribosome assembly and nucleocytoplasmic transport (Ginisty et al., 1999;Srivastava and Pollard, 1999). As a multifunctional protein, nucleolin has also been proposed to be a nuclear matrix-binding protein (Gotzmann et al., 1997), to interact with telomerase (Khurts et al., 2004) and to be involved in the regulation of apoptosis (Mi et al., 2003), intestinal cell differentiation (Turck et al., 2006) and remodeling of nucleosomes (Angelov et al., 2006). Although many functions of nucleolin have been clarified, previous studies have fallen short of demonstrating its functions during mitosis.Nucleolin is highly phosphorylated (Olson et al., 1975;Rao et al., 1982) and its phosphorylation is highly regulated during the cell cycle (Peter et al., 1990;Morimoto et al., 2005). Extensive phosphorylation by casein kinase 2 (CK2) occurs at interphase and by CDC2 during mitosis (Peter et al., 1990), and this regulated phosphorylation of nucleolin probably regulates nucleolin functions during the cell cycle (Ginisty et al., 1999). It has been demonstrated that phosphorylation of nucleolin at interphase is correlated with active rRNA transcription (Suzuki et al., 1987). Despite a previous study describing the localization of nucleolin phosphorylated by CDC2 (Dranovsky et al., 2001), no information about its functions during mitosis has been obtained to date.Here, we demonstrate that nucleolin localizes to the nucleoli, which are located in the peripheral region including the vicinity of the outer kinetochore of chromosomes, in interphase nuclei and during mitosis. Staining with an antibody specific for nucle...

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“…A detailed analysis of the 3'ETS sequences revealed the presence of 3 (VAR2), 4 (VAR1 and VAR3) or 5 rDNA chromatin decondensation and affects expression of specific 45S rRNA gene variants. 1,16 Here we present additional characterization of these rDNA gene variants and discuss their possible impact on rDNA chromatin organization and gene expression.…”

Section: Variations On a Teammentioning

confidence: 99%

Variations in a team: Major and minor variants ofArabidopsisthaliana rDNA genes

Abou-Ellail¹,

Cooke²,

Sáez‐Vasquez³

2011

Nucleus

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While plant rRNA gene organization and expression have been studied for several decades, the repetitive nature and high sequence identity between the tandemly-repeated units has prevented precise studies to determine which units are active and elucidate mechanisms of spatial and temporal transcriptional control. We have detected four variants among rRNA genes of Arabidopsis thaliana by analysis of the 3' external spacer region. Surprisingly, the most abundant variant, representing ~50% of the genes, is not expressed in wild-type plants but is transcribed in lines mutated in one of the two nucleolin genes.1 Analysis of Arabidopsis ecotypes indicated considerable variability in numbers and presence/absence of variants, although more closely-related ecotypes show similar profiles. Sequence analysis showed that one of the variants is not only unexpectedly located within a 5S RNA gene cluster in the pericentromeric region of chromosome 3 but is also potentially highly expressed in wild-type plants. We present a model to explain how transcription of this this unusual variant, maintained in an active state by nucleolin binding, could be involved in control of expression of the major variant, while absence of nucleolin leads to silencing of the minor variant and consequent expression of the major variant.

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Characterization of AtNUC-L1 Reveals a Central Role of Nucleolin in Nucleolus Organization and Silencing of AtNUC-L2 Gene in Arabidopsis

Cited by 125 publications

References 49 publications

Pumilio Puf domain RNA-binding proteins in Arabidopsis

Pumilio Puf domain RNA-binding proteins in Arabidopsis

Nucleolin functions in nucleolus formation and chromosome congression

Variations in a team: Major and minor variants ofArabidopsisthaliana rDNA genes

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