The Nucleolus: Structure and Function

Dubois, Marie-Line; Boisvert, François‐Michel

doi:10.1007/978-3-319-38882-3_2

Cited by 37 publications

(31 citation statements)

References 149 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The cell nucleus contains a collection of nonmembrane-bound nuclear bodies (NBs) that participate in the regulation of essential functions, such as gene expression [ 1 , 2 ]. The nucleolus is the most conspicuous NB that is present throughout the Eukarya domain [ 3 , 4 ]. The fundamental role of the nucleolus is to coordinate ribosome biogenesis, an intricate multistep process that includes the transcription of ribosomal cistrons (rDNA) by RNA polymerase (RNA Pol) I and accessory factors, cleavage and chemical modification of precursor ribosomal RNA (rRNA), and assembly of mature rRNA species 18S, 5.8S, and 25/28S with numerous proteins and the 5S rRNA, product of RNA Pol III activity [ 5 , 6 ].…”

Section: Introductionmentioning

confidence: 99%

Nucleolar Division in the Promastigote Stage ofLeishmania majorParasite: A Nop56 Point of View

Nepomuceno‐Mejía

Florencio-Martínez

Martínez‐Calvillo

2018

BioMed Research International

View full text Add to dashboard Cite

Nucleogenesis is the cellular event responsible for the formation of the new nucleoli at the end of mitosis. This process depends on the synthesis and processing of ribosomal RNA (rRNA) and, in some eukaryotes, the transfer of nucleolar material contained in prenucleolar bodies (PNBs) to active transcription sites. The lack of a comprehensive description of the nucleolus throughout the cell cycle of the human pathogen Leishmania major prompted us to analyze the distribution of nucleolar protein 56 (Nop56) during interphase and mitosis in the promastigote stage of the parasite. By in silico analysis we show that the orthologue of Nop56 in L. major (LmNop56) contains the three characteristic Nop56 domains and that its predicted three-dimensional structure is also conserved. Fluorescence microscopy observations indicate that the nucleolar localization of LmNop56 is similar, but not identical, to that of the nucleolar protein Elp3b. Notably, unlike other nucleolar proteins, LmNop56 remains associated with the nucleolus in nonproliferative cells. Moreover, epifluorescent images indicate the preservation of the nucleolar structure throughout the closed nuclear division. Experiments performed with the related parasite Trypanosoma brucei show that nucleolar division is carried out by an analogous mechanism.

show abstract

Section: Introductionmentioning

confidence: 99%

Nucleolar Division in the Promastigote Stage ofLeishmania majorParasite: A Nop56 Point of View

Nepomuceno‐Mejía

Florencio-Martínez

Martínez‐Calvillo

2018

BioMed Research International

View full text Add to dashboard Cite

show abstract

“…The nucleus is a membrane-enclosed organelle containing the nucleolus, Cajal bodies, promyelocytic leukaemia bodies, splicing speckles, paraspeckles and other subnuclear bodies (Dundr & Misteli, 2001;Matera et al, 2009). The nucleolus is the most prominent subnuclear compartment in which rRNA transcription, processing and ribosomal subunit assembly occur (Boisvert et al, 2007;Dubois & Boisvert, 2016). Fibrillarin (Fib2), nucleolin and B23 are the most abundant and well-studied nucleolar proteins (Dubois & Boisvert, 2016).…”

Section: Introductionmentioning

confidence: 99%

“…The nucleolus is the most prominent subnuclear compartment in which rRNA transcription, processing and ribosomal subunit assembly occur (Boisvert et al, 2007;Dubois & Boisvert, 2016). Fibrillarin (Fib2), nucleolin and B23 are the most abundant and well-studied nucleolar proteins (Dubois & Boisvert, 2016).…”

Section: Introductionmentioning

confidence: 99%

Hijacking of the nucleolar protein fibrillarin by TGB1 is required for cell‐to‐cell movement of Barley stripe mosaic virus

Zhang

Jiang

et al. 2017

Molecular Plant Pathology

View full text Add to dashboard Cite

Barley stripe mosaic virus (BSMV) Triple Gene Block1 (TGB1) is a multifunctional movement protein with RNA-binding, ATPase and helicase activities which mainly localizes to the plasmodesmata (PD) in infected cells. Here, we show that TGB1 localizes to the nucleus and the nucleolus, as well as the cytoplasm, and that TGB1 nuclear-cytoplasmic trafficking is required for BSMV cell-to-cell movement. Prediction analyses and laser scanning confocal microscopy (LSCM) experiments verified that TGB1 possesses a nucleolar localization signal (NoLS) (amino acids 95-104) and a nuclear localization signal (NLS) (amino acids 227-238). NoLS mutations reduced BSMV cell-to-cell movement significantly, whereas NLS mutations almost completely abolished movement. Furthermore, neither the NoLS nor NLS mutant viruses could infect Nicotiana benthamiana systemically, although the NoLS mutant virus was able to establish systemic infections of barley. Protein interaction experiments demonstrated that TGB1 interacts directly with the glycine-arginine-rich (GAR) domain of the nucleolar protein fibrillarin (Fib2). Moreover, in BSMV-infected cells, Fib2 accumulation increased by about 60%-70% and co-localized with TGB1 in the plasmodesmata. In addition, BSMV cell-to-cell movement in fib2 knockdown transgenic plants was reduced to less than one-third of that of non-transgenic plants. Fib2 also co-localized with both TGB1 and BSMV RNA, which are the main components of the ribonucleoprotein (RNP) movement complex. Collectively, these results show that TGB1-Fib2 interactions play a direct role in cell-to-cell movement, and we propose that Fib2 is hijacked by BSMV TGB1 to form a BSMV RNP which functions in cell-to-cell movement.

show abstract

“…With regards to the nucleolar structure, when a cell is stained with DAPI to highlight the cell’s DNA, the nucleolus appears as a large sparse area in the cell’s nucleus since the nucleolus has little DNA in it. However, the nucleolus does contain some DNA, primarily the ribosomal genes in nucleolar organizing regions (NORs), found in chromosomes 13, 14, 15, 21, and 22, and the nucleolus is associated with chromosomes when centromeres are assembled [ 35 ]. After assembling centromeres, the nucleoli disappear during mitosis as the cell divides, but the nucleoli reappear in the daughter cells by forming around NORs.…”

Section: Components Of the “X Chromosome-nucleolus Nexus” Hypothesismentioning

confidence: 99%

An Epigenetics-Based Hypothesis of Autoantigen Development in Systemic Lupus Erythematosus

Brooks

2020

Epigenomes

View full text Add to dashboard Cite

Currently, we have a limited understanding of mechanisms leading to systemic lupus erythematosus, but we know that genetics, environmental factors, and epigenetics contribute to the disease. One common aspect of the various environmental triggers is that they can cause cellular stress. When extraordinary stress occurs, such as viral activation, a cell’s response can include increased nucleolar volume and activity to produce more machinery (e.g., ribosomes) to help the cell recover. However, nucleolar expansion can disrupt the epigenetic control in neighboring heterochromatin that comprises the nucleolar shell. This disruption can open underlying vulnerabilities that provoke an autoimmune reaction. Here, we review the “X chromosome-nucleolus nexus” hypothesis, which explains how nucleolar stress can disrupt epigenetically silenced chromatin, especially the neighboring inactive X chromosome (aka the nucleolar satellite). Chromatin disruption can lead to the expression of sequestered DNA, such as Alu elements and fully functional LINE-1 reverse transcriptase genes. In addition, Alu transcripts can disrupt the nucleolar structural integrity, leading to nucleolar disintegration. Such disintegration can leave nucleolar components and products in autoantigenic forms, such as abnormal conformations or incomplete macromolecular assemblies. Recent research on DNA sensing pathways can now be incorporated into the hypothesis to provide further details explaining how autoantibodies to endogenous nucleic acids arise.

show abstract

The Nucleolus: Structure and Function

Cited by 37 publications

References 149 publications

Nucleolar Division in the Promastigote Stage ofLeishmania majorParasite: A Nop56 Point of View

Nucleolar Division in the Promastigote Stage ofLeishmania majorParasite: A Nop56 Point of View

Hijacking of the nucleolar protein fibrillarin by TGB1 is required for cell‐to‐cell movement of Barley stripe mosaic virus

An Epigenetics-Based Hypothesis of Autoantigen Development in Systemic Lupus Erythematosus

Contact Info

Product

Resources

About