The hierarchical structure of the perichromosomal layer comprises Ki67, ribosomal RNAs, and nucleolar proteins

Hayashi, Yoshihiko; Kato, Kazashi; Kimura, Kazuhiro

doi:10.1016/j.bbrc.2017.09.092

Cited by 26 publications

(30 citation statements)

References 18 publications

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“…Consistent with this notion, NOL11 signals in the PR were reduced by the treatment of low-dose actinomycin D, an inhibitor of RNA polymerase I, but hardly affected by the treatment of amanitin, an inhibitor of RNA polymerase II ( Supplementary Figure S5 ). In contrast, Ki67 signals in the PR were not affected by these inhibitors ( Supplementary Figure S5 ) as reported previously ( 20 ). To determine which components possess RNA-binding activity, GST fusion proteins of each component of the NWC complex were purified and tested for their ability to bind to pre-rRNA.…”

Section: Resultssupporting

confidence: 89%

“…A fractionation experiment conducted on mitotic cell extracts also showed that NOL11 was present in the chromosome-enriched fraction, whereas TIF-IA, another nucleolar protein and rRNA transcription factor, was barely detected (Figure 1D ). These results indicated that NOL11 localized at the PR, which consists of subsets of nucleolar proteins ( 1 , 3 , 15 , 20 , 33 ).…”

Section: Resultsmentioning

confidence: 82%

“…Recent studies have indicated that the newly synthesised pre-rRNA associates with the PR and acts as a binding scaffold for several pre-rRNA processing proteins ( 20 , 33 ). Consistent with this notion, treatment with RNase A reduced the NOL11 signals from the PR (Figure 3C ), unlike UBF that directly binds to the rDNA promoter region (Figure 3C ).…”

Section: Resultsmentioning

confidence: 99%

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Identification of a novel nucleolar protein complex required for mitotic chromosome segregation through centromeric accumulation of Aurora B

Fujimura

Hayashi

Kato

et al. 2020

Nucleic Acids Research

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Abstract The nucleolus is a membrane-less nuclear structure that disassembles when cells undergo mitosis. During mitosis, nucleolar factors are thus released from the nucleolus and dynamically change their subcellular localization; however, their functions remain largely uncharacterised. Here, we found that a nucleolar factor called nucleolar protein 11 (NOL11) forms a protein complex with two tryptophan-aspartic acid (WD) repeat proteins named WD-repeat protein 43 (WDR43) and Cirhin in mitotic cells. This complex, referred to here as the NWC (NOL11-WDR43-Cirhin) complex, exists in nucleoli during interphase and translocates to the periphery of mitotic chromosomes, i.e., perichromosomal regions. During mitotic progression, both the congression of chromosomes to the metaphase plate and sister chromatid cohesion are impaired in the absence of the NWC complex, as it is required for the centromeric enrichment of Aurora B and the associating phosphorylation of histone H3 at threonine 3. These results reveal the characteristics of a novel protein complex consisting of nucleolar proteins, which is required for regulating kinetochores and centromeres to ensure faithful chromosome segregation.

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Section: Resultssupporting

confidence: 89%

Section: Resultsmentioning

confidence: 82%

Section: Resultsmentioning

confidence: 99%

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Identification of a novel nucleolar protein complex required for mitotic chromosome segregation through centromeric accumulation of Aurora B

Fujimura

Hayashi

Kato

et al. 2020

Nucleic Acids Research

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“…S9B ). NIFK binds MKI67 and relocalizes to the perichromosome during the mitosis similarly to the rRNA to which NIFK associates during interphase [ 46 , 51 , 52 , 55 ]. Phosphorylation on S666 of HCFC1 has been abundantly identified over the years by mass spectrometry as reported in PSP database (62x on Jan 2020) and is considered downstream of various signaling including ionizing radiation or nocodazole arrest [ 56 – 58 ].…”

Section: Resultsmentioning

confidence: 99%

The Greatwall kinase safeguards the genome integrity by affecting the kinome activity in mitosis

et al. 2020

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Progression through mitosis is balanced by the timely regulation of phosphorylation and dephosphorylation events ensuring the correct segregation of chromosomes before cytokinesis. This balance is regulated by the opposing actions of CDK1 and PP2A, as well as the Greatwall kinase/MASTL. MASTL is commonly overexpressed in cancer, which makes it a potential therapeutic anticancer target. Loss of Mastl induces multiple chromosomal errors that lead to the accumulation of micronuclei and multilobulated cells in mitosis. Our analyses revealed that loss of Mastl leads to chromosome breaks and abnormalities impairing correct segregation. Phospho-proteomic data for Mastl knockout cells revealed alterations in proteins implicated in multiple processes during mitosis including double-strand DNA damage repair. In silico prediction of the kinases with affected activity unveiled NEK2 to be regulated in the absence of Mastl. We uncovered that, RAD51AP1, involved in regulation of homologous recombination, is phosphorylated by NEK2 and CDK1 but also efficiently dephosphorylated by PP2A/B55. Our results suggest that MastlKO disturbs the equilibrium of the mitotic phosphoproteome that leads to the disruption of DNA damage repair and triggers an accumulation of chromosome breaks even in noncancerous cells.

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“…It might be the case that the removal/addition of a large number of phosphate groups from/to IDRs of RNA-related proteins induces dynamic rearrangements of nucleolus and other RNA-containing nuclear speckles upon the entry of mitosis, which may disrupt these organelle and release a large amount of RNA molecules into the cellular plasm. This will drastically change an intracellular environment, and may affect the assembly/disassembly dynamics of other protein complexes, such as chromosome, which is known to contain preribosomal RNA and nucleolar proteins on the surface (70, 71). It might be the case that chromosome condensation could be induced by orchestrated effects of phosphorylation of chromosome-related proteins (Fig.…”

Section: Discussionmentioning

confidence: 99%

Quantitative proteomics indicate a strong correlation of mitotic phospho-/dephosphorylation with non-structured regions of substrates

Yamazaki

Kosako

Yoshimura

2019

Preprint

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16Protein phosphorylation plays inevitable roles in the regulation and the progression of mitosis. More than ten 17 thousands of phosphorylated residues and their responsible kinases have so far been identified by a number of 18 proteomic analyses. While some of those phosphosites have been demonstrated to affect either protein-protein 19 interaction or catalytic activity of the substrate protein, the effect of most mitotic phosphosites remain 20 unclarified. In this study, we tried to extract structural properties of mitotic phosphosites and neighboring 21 residues, and find a role of heavy phosphorylation at non-structured domain. A quantitative mass spectrometry 22 of mitosis-arrested and non-arrested HeLa cells identified more than 4,100 and 1,900 residues which are 23 significantly phosphorylated, and dephosphorylated at mitotic entry, respectively. Calculating the disorder score 24 of the neighboring amino acid sequence of individual phosphosites revealed that more than 70% of the 25 phosphosites which are dephosphorylated existed in disordered regions, whereas 50% of phosphorylated sites 26 existed in non-structured domain. There was a clear inversed co-relation between probability in non-structured 27 domain and increment of phosphorylation in mitosis. These results indicate that at the entry of mitosis, a 28 significant amount of phosphate group is removed from non-structured domains and attached to more structured 29 domains. GO term analysis revealed that mitosis-related proteins are heavily phosphorylated, whereas RNA-30 related proteins are both dephosphorylated and phosphorylated, implying that heavy 31 phosphorylation/dephosphorylation in non-structured domain of RNA-binding proteins may play a role in 32 dynamic rearrangement of RNA-containing organelle, as well as other intracellular environments. 33 34 65been identified (reviewed in (17-21)). Dephosphorylation also plays essential roles both at the entry and the 66 exit of mitosis (22, 23) (24, 25). More than 1,000 kinds of phosphosites are dephosphorylated during anaphase 67 (26), and more than five hundreds are dephosphorylated at the entry of mitosis (2). For example, CDK1 is 68 activated by dephosphorylation by Cdc25B/C (27, 28), and Cdc25C is partially activated by protein phosphatase 69 1 (27). These results indicate that a vast number of phosphate groups are transferred to and from the substrate 70 proteins during mitotic entry. 71One of the unclarified problems on mitotic phosphorylation could be why and how a vast number of 72 phosphate groups are transferred from a set of proteins to a different set of proteins, and whether these different 73 sets of mitotic phosphosites are structurally different or not. Especially, the distribution of phosphosites in 74 structured or non-structured regions of the substrate proteins is an important cue to understand the structural 75 effect of phosphorylation/dephosphorylation. In this study, we performed phosphoproteomic analysis of cellular 76 proteins to quantify and compare individual phosphosi...

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The hierarchical structure of the perichromosomal layer comprises Ki67, ribosomal RNAs, and nucleolar proteins

Cited by 26 publications

References 18 publications

Identification of a novel nucleolar protein complex required for mitotic chromosome segregation through centromeric accumulation of Aurora B

Identification of a novel nucleolar protein complex required for mitotic chromosome segregation through centromeric accumulation of Aurora B

The Greatwall kinase safeguards the genome integrity by affecting the kinome activity in mitosis

Quantitative proteomics indicate a strong correlation of mitotic phospho-/dephosphorylation with non-structured regions of substrates

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