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Smetana K, Mikulenková D, Karban J, Trněný M. To the ring-shaped nucleolus seen by microscopy using human lymphocytes of blood donors and chronic lymphocytic leukemia patients. Eur J Histochem 2024; 68. [PMID: 39221853 PMCID: PMC11408907 DOI: 10.4081/ejh.2024.4075] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2024] [Accepted: 06/22/2024] [Indexed: 09/04/2024] Open
Abstract
The present study was undertaken to provide more information on the peripheral RNA containing ring of ringshaped nucleoli (RSNo). Human lymphocytes of blood donors and patients suffering from B chronic lymphocytic leukemia mostly characterized by RSNo represented very convenient cell models for such study. According to the light microscopy the peripheral RNA ring possessed several highly condensed foci. Such regions represented accumulated dense RNA fibrillar components (DFCs) seen by the electron microscopy. In contrary, the incidence of dense granular RNA-containing components (GCs) in surrounding portions of the RNA ring was small. Thus, the structural and morphological organization of the peripheral RNA ring of RSNo apparently reflects sites of micro-segregated foci of DFCs and a small incidence of GCs. That structural organization of the peripheral RNA ring of RSNo appeared to be a prerequisite for further regressive nucleolar changes resulting in the development of micronucleoli in terminal lymphocytes.
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Affiliation(s)
- Karel Smetana
- Institute of Haematology and Blood Transfusion, Prague.
| | | | - Josef Karban
- 1st Hematology and Oncology Clinic of the 1st Medical Faculty of the Charles University and General Medical Hospital, Prague.
| | - Marek Trněný
- 1st Hematology and Oncology Clinic of the 1st Medical Faculty of the Charles University and General Medical Hospital, Prague.
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2
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Smetana K, Mikulenková D, Klamová H, Karban J, Trněný M. Technical Note Cell Dysplasia - Cell Dysplastic Features (A Morphological Note). Folia Biol (Praha) 2023; 69:34-39. [PMID: 37962029 DOI: 10.14712/fb2023069010034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
Cell dysplasia is a currently used term describing various cellular developmental abnormalities visible by microscopy. However, detailed description of these developmental abnormalities might provide useful information not only on the cell state but also on the abnormal developmental steps of cell lineages, tissues and organs. The frequently noted visualized cell dysplastic features reflect nuclear- or nucleolar-cytoplasmic anarchy (asynchrony), premature heterochromatin condensation state, marked aneuploidy, abnormal nucleus-cytoplasm ratio, abnormality of cell organelles including mitochondria, abnormal presence or absence of cell lineage-specific granules, and formation of peripheral buds or blebbing on the cell surface. The description of these frequently occurring cell dysplastic features might also be helpful in recognizing and studying defined specific disorders of the "whole macro-body" expressed as a disease.
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Affiliation(s)
- Karel Smetana
- Institute of Haematology and Blood Transfusion, Prague, Czech Republic.
| | - Dana Mikulenková
- Institute of Haematology and Blood Transfusion, Prague, Czech Republic
| | - Hana Klamová
- Institute of Haematology and Blood Transfusion, Prague, Czech Republic
| | - Josef Karban
- 1st Department of Medicine - Department of Haematology, First Faculty of Medicine, Charles University and General University Hospital in Prague, Czech Republic
| | - Marek Trněný
- 1st Department of Medicine - Department of Haematology, First Faculty of Medicine, Charles University and General University Hospital in Prague, Czech Republic
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3
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Smetana K, Klamová H, Mikulenková D, Čermák J, Otevřelová P, Karban J, Trněný M. The cell body space occupied by the nucleus during the cell differentiation in human lymphocytic, granulocytic and erythroid cell lineages. Physiol Res 2021; 70:701-707. [PMID: 34505521 DOI: 10.33549/physiolres.934691] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
The present nuclear and cell body diameter measurements demonstrated size differences of the approximate cell space estimate occupied by the cell nucleus during the cell differentiation in lymphocytic, granulocytic and erythroid cell lineages. These lineages were used as convenient models because all differentiation steps were easily identified and accessible in diagnostic peripheral blood or bone marrow smears of blood donors (BDs), patients suffering from chronic lymphocytic leukemia (CLL), patients with chronic myeloid leukemia (CML) and refractory anemia (RA) of the myelodysplastic syndrome (MDS). The cell space occupied by the nucleus was constant and did not change during the cell differentiation in the lymphocytic cell lineages of BDs and CLL patients despite the decreased cell size. In contrary, the cell space occupied by the nucleus markedly decreased in differentiating cells of granulocytic and erythroid lineages of patients suffering from CML. In the erythroid cell lineage in patients with RA of MDS the small reduction of the cell space occupied by the nucleus during the differentiation was not significant. The measurements also indicated that in progenitor cells of all studied cell lineages nuclei occupied more than 70 % of the cell space. Thus, the nucleus-cytoplasmic morphological and functional equilibrium appeared to be characteristic for each differentiation step and each specific cell lineage.
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Affiliation(s)
- K Smetana
- Institute of Hematology and Blood Transfusion, Prague 2, Czech Republic.
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4
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Heissenberger C, Liendl L, Nagelreiter F, Gonskikh Y, Yang G, Stelzer EM, Krammer TL, Micutkova L, Vogt S, Kreil DP, Sekot G, Siena E, Poser I, Harreither E, Linder A, Ehret V, Helbich TH, Grillari-Voglauer R, Jansen-Dürr P, Koš M, Polacek N, Grillari J, Schosserer M. Loss of the ribosomal RNA methyltransferase NSUN5 impairs global protein synthesis and normal growth. Nucleic Acids Res 2019; 47:11807-11825. [PMID: 31722427 PMCID: PMC7145617 DOI: 10.1093/nar/gkz1043] [Citation(s) in RCA: 54] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2019] [Revised: 09/27/2019] [Accepted: 10/28/2019] [Indexed: 12/24/2022] Open
Abstract
Modifications of ribosomal RNA expand the nucleotide repertoire and thereby contribute to ribosome heterogeneity and translational regulation of gene expression. One particular m5C modification of 25S ribosomal RNA, which is introduced by Rcm1p, was previously shown to modulate stress responses and lifespan in yeast and other small organisms. Here, we report that NSUN5 is the functional orthologue of Rcm1p, introducing m5C3782 into human and m5C3438 into mouse 28S ribosomal RNA. Haploinsufficiency of the NSUN5 gene in fibroblasts from William Beuren syndrome patients causes partial loss of this modification. The N-terminal domain of NSUN5 is required for targeting to nucleoli, while two evolutionary highly conserved cysteines mediate catalysis. Phenotypic consequences of NSUN5 deficiency in mammalian cells include decreased proliferation and size, which can be attributed to a reduction in total protein synthesis by altered ribosomes. Strikingly, Nsun5 knockout in mice causes decreased body weight and lean mass without alterations in food intake, as well as a trend towards reduced protein synthesis in several tissues. Together, our findings emphasize the importance of single RNA modifications for ribosome function and normal cellular and organismal physiology.
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Affiliation(s)
- Clemens Heissenberger
- Department of Biotechnology, Institute of Molecular Biotechnology, University of Natural Resources and Life Sciences, Vienna, 1190 Vienna, Austria
| | - Lisa Liendl
- Department of Biotechnology, Institute of Molecular Biotechnology, University of Natural Resources and Life Sciences, Vienna, 1190 Vienna, Austria
| | - Fabian Nagelreiter
- Department of Biotechnology, Institute of Molecular Biotechnology, University of Natural Resources and Life Sciences, Vienna, 1190 Vienna, Austria
| | - Yulia Gonskikh
- Department of Chemistry and Biochemistry, University of Bern, 3012 Bern, Switzerland
| | - Guohuan Yang
- Biochemistry Center, University of Heidelberg, 69120 Heidelberg, Germany
| | - Elena M Stelzer
- Department of Biotechnology, Institute of Molecular Biotechnology, University of Natural Resources and Life Sciences, Vienna, 1190 Vienna, Austria
| | - Teresa L Krammer
- Department of Biotechnology, Institute of Molecular Biotechnology, University of Natural Resources and Life Sciences, Vienna, 1190 Vienna, Austria
| | - Lucia Micutkova
- Institute for Biomedical Aging Research, University of Innsbruck, 6020 Innsbruck, Austria
| | - Stefan Vogt
- Department of Biotechnology, Institute of Molecular Biotechnology, University of Natural Resources and Life Sciences, Vienna, 1190 Vienna, Austria
| | - David P Kreil
- Department of Biotechnology, Institute of Molecular Biotechnology, University of Natural Resources and Life Sciences, Vienna, 1190 Vienna, Austria
| | - Gerhard Sekot
- Department of Biotechnology, Institute of Molecular Biotechnology, University of Natural Resources and Life Sciences, Vienna, 1190 Vienna, Austria
| | - Emilio Siena
- Department of Biotechnology, Institute of Molecular Biotechnology, University of Natural Resources and Life Sciences, Vienna, 1190 Vienna, Austria
| | - Ina Poser
- Max Planck Institute for Molecular Cell Biology and Genetics, 01307 Dresden, Germany
| | - Eva Harreither
- Department of Biotechnology, Institute of Molecular Biotechnology, University of Natural Resources and Life Sciences, Vienna, 1190 Vienna, Austria
| | - Angela Linder
- Department of Biotechnology, Institute of Molecular Biotechnology, University of Natural Resources and Life Sciences, Vienna, 1190 Vienna, Austria
| | - Viktoria Ehret
- Department of Biomedical Imaging and Image-guided Therapy, Division of Molecular and Gender Imaging, Preclinical Imaging Laboratory, Medical University of Vienna, 1090 Vienna, Austria
| | - Thomas H Helbich
- Department of Biomedical Imaging and Image-guided Therapy, Division of Molecular and Gender Imaging, Preclinical Imaging Laboratory, Medical University of Vienna, 1090 Vienna, Austria
| | - Regina Grillari-Voglauer
- Department of Biotechnology, Institute of Molecular Biotechnology, University of Natural Resources and Life Sciences, Vienna, 1190 Vienna, Austria
| | - Pidder Jansen-Dürr
- Institute for Biomedical Aging Research, University of Innsbruck, 6020 Innsbruck, Austria
| | - Martin Koš
- Biochemistry Center, University of Heidelberg, 69120 Heidelberg, Germany
| | - Norbert Polacek
- Department of Chemistry and Biochemistry, University of Bern, 3012 Bern, Switzerland
| | - Johannes Grillari
- Department of Biotechnology, Institute of Molecular Biotechnology, University of Natural Resources and Life Sciences, Vienna, 1190 Vienna, Austria
- Christian Doppler Laboratory on Biotechnology of Skin Aging, 1190 Vienna, Austria
- Ludwig Boltzmann Institute for Experimental and Clinical Traumatology, 1200 Vienna, Austria
| | - Markus Schosserer
- Department of Biotechnology, Institute of Molecular Biotechnology, University of Natural Resources and Life Sciences, Vienna, 1190 Vienna, Austria
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5
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Long M, Sun X, Shi W, Yanru A, Leung STC, Ding D, Cheema MS, MacPherson N, Nelson CJ, Ausio J, Yan Y, Ishibashi T. A novel histone H4 variant H4G regulates rDNA transcription in breast cancer. Nucleic Acids Res 2019; 47:8399-8409. [PMID: 31219579 PMCID: PMC6895281 DOI: 10.1093/nar/gkz547] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2018] [Revised: 06/06/2019] [Accepted: 06/10/2019] [Indexed: 12/20/2022] Open
Abstract
Histone variants, present in various cell types and tissues, are known to exhibit different functions. For example, histone H3.3 and H2A.Z are both involved in gene expression regulation, whereas H2A.X is a specific variant that responds to DNA double-strand breaks. In this study, we characterized H4G, a novel hominidae-specific histone H4 variant. We found that H4G is expressed in a variety of human cell lines and exhibit tumor-stage dependent overexpression in tissues from breast cancer patients. We found that H4G localized primarily to the nucleoli of the cell nucleus. This localization was controlled by the interaction of the alpha-helix 3 of the histone fold motif with a histone chaperone, nucleophosmin 1. In addition, we found that modulating H4G expression affects rRNA expression levels, protein synthesis rates and cell-cycle progression. Our data suggest that H4G expression alters nucleolar chromatin in a way that enhances rDNA transcription in breast cancer tissues.
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Affiliation(s)
- Mengping Long
- Division of Life Science, Hong Kong University of Science and Technology, Clear Water Bay, NT, Hong Kong, HKSAR, China
| | - Xulun Sun
- Division of Life Science, Hong Kong University of Science and Technology, Clear Water Bay, NT, Hong Kong, HKSAR, China
| | - Wenjin Shi
- Division of Life Science, Hong Kong University of Science and Technology, Clear Water Bay, NT, Hong Kong, HKSAR, China
| | - An Yanru
- Division of Life Science, Hong Kong University of Science and Technology, Clear Water Bay, NT, Hong Kong, HKSAR, China
| | - Sophia T C Leung
- Division of Life Science, Hong Kong University of Science and Technology, Clear Water Bay, NT, Hong Kong, HKSAR, China
| | - Dongbo Ding
- Division of Life Science, Hong Kong University of Science and Technology, Clear Water Bay, NT, Hong Kong, HKSAR, China
| | - Manjinder S Cheema
- Department of Biochemistry and Microbiology, University of Victoria, Victoria BC V8W 3P6, Canada
| | - Nicol MacPherson
- Department of Medical Oncology, BC Cancer Vancouver Island Centre, Victoria, BC V8R 6V5, Canada
| | - Christopher J Nelson
- Department of Biochemistry and Microbiology, University of Victoria, Victoria BC V8W 3P6, Canada
| | - Juan Ausio
- Department of Biochemistry and Microbiology, University of Victoria, Victoria BC V8W 3P6, Canada
| | - Yan Yan
- Division of Life Science, Hong Kong University of Science and Technology, Clear Water Bay, NT, Hong Kong, HKSAR, China
| | - Toyotaka Ishibashi
- Division of Life Science, Hong Kong University of Science and Technology, Clear Water Bay, NT, Hong Kong, HKSAR, China
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6
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Smetana K, Klamová H, Mikulenková D. To the approximate size of the nuclear region occupied by nucleolar bodies during cell differentiation and maturation using the human leukemic granulocytic lineage as a convenient model. Physiol Res 2019; 68:633-638. [PMID: 31177792 DOI: 10.33549/physiolres.934045] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
The present study was undertaken to estimate the approximate size of nuclear regions occupied by nucleolar bodies during the cell differentiation and maturation. The differentiation and maturation of human leukemic granulocytic cells in patients suffering from the chronic phase of the chronic granulocytic leukemia (CML) represented a convenient model for such study because of the large number of cells for the diameter measurements at the single cell level. Early and advanced differentiation or maturation stages of these cells are well defined and nucleolar bodies and nuclear outlines are easily seen by simple cytochemical methods for the visualization of RNA and silver stained proteins in smear preparations. During the cell differentiation and maturation, the estimated size of the nuclear region occupied by nucleolar bodies decreased in both untreated and treated patients with the anti-leukemic therapy. However, the size reduction of nucleolar bodies in differentiated and mature cells was larger than that of the nucleus. In addition, the results also indicated that the nuclear region occupied by nucleolar bodies was characteristic for each differentiation and maturation stage of the granulocytic cell lineage and was not substantially influenced by the anti-leukemic therapy of CML patients.
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Affiliation(s)
- K Smetana
- Institute of Hematology and Blood Transfusion, Prague, Czech Republic.
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7
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Li Y, Hu Y, Che L, Jia J, Chen M. Nucleolar localization of Small G protein RhoA is associated with active RNA synthesis in human carcinoma HEp-2 cells. Oncol Lett 2016; 11:3605-3610. [PMID: 27313679 PMCID: PMC4888017 DOI: 10.3892/ol.2016.4450] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2015] [Accepted: 03/01/2016] [Indexed: 01/09/2023] Open
Abstract
Previous studies have demonstrated that the nuclear localization of ras homolog family member A (RhoA), with prominent concentration in the nucleolus, is a common feature in human cancer tissues and cancer cell lines. Although a previous study has demonstrated that the nuclear translocation of RhoA occurs via active transport, a process that occurs through importin α in a nuclear factor-κB-dependent manner, the mechanism, biological function and pathological meaning of the nucleolar residency of RhoA remain to be elucidated. As the cell nucleolus is the site of ribosome biosynthesis, the aim of the present study was to investigate the association between RNA synthesis and the nucleolar localization of RhoA, as well as the molecular mechanisms underlying the residency of RhoA in the nucleolus of HEp-2 (human larynx epithelial carcinoma) cells. Indirect immunofluorescence microscopy was used to evaluate the subcellular distribution of nuclear RhoA, and immunoblotting analysis was used to determine the total cellular protein level of RhoA. Consistent with the results of previous studies, untreated HEp-2 cells exhibited bright nucleolar staining, indicating an increased concentration of RhoA in the nucleoli. Treatment with actinomycin D for the inhibition of RNA synthesis caused a redistribution of RhoA from the nucleoli to the nucleoplasm with a speckled staining pattern. Immunoblotting revealed that neither the total cellular amount of RhoA nor the integrity of RhoA was affected by treatment with actinomycin D. In cells that were treated at a decreased concentration (0.05 mg/l) of actinomycin D, the redistribution of RhoA was reversible following the removal of the drug from the culture medium. However, this reversal was not observed at an increased drug concentration (1 mg/l). Overall, to the best of our knowledge, the results of the present study provide the first in situ evidence that the inhibition of RNA synthesis induces a redistribution of nucleolar RhoA to the nucleoplasm, and additionally suggest that the nucleolar residency of RhoA in HEp-2 cells may be associated with active RNA synthesis.
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Affiliation(s)
- Yueying Li
- Department of Physiology, School of Medicine, Jiangsu University, Zhenjiang, Jiangsu 212013, P.R. China
| | - Yong Hu
- Department of Neonatology, Shanghai Children's Hospital, Shanghai Jiao Tong University, Shanghai 200040, P.R. China
| | - Lilong Che
- Department of Physiology, School of Medicine, Jiangsu University, Zhenjiang, Jiangsu 212013, P.R. China
| | - Junhai Jia
- Department of Physiology, School of Medicine, Jiangsu University, Zhenjiang, Jiangsu 212013, P.R. China
| | - Min Chen
- Department of Physiology, School of Medicine, Jiangsu University, Zhenjiang, Jiangsu 212013, P.R. China
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P-TEFb Kinase Activity Is Essential for Global Transcription, Resumption of Meiosis and Embryonic Genome Activation in Pig. PLoS One 2016; 11:e0152254. [PMID: 27011207 PMCID: PMC4807088 DOI: 10.1371/journal.pone.0152254] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2015] [Accepted: 03/13/2016] [Indexed: 11/20/2022] Open
Abstract
Positive transcription elongation factor b (P-TEFb) is a RNA polymerase II carboxyl-terminal domain (Pol II CTD) kinase that phosphorylates Ser2 of the CTD and promotes the elongation phase of transcription. Despite the fact that P-TEFb has role in many cellular processes, the role of this kinase complex remains to be understood in mammalian early developmental events. In this study, using immunocytochemical analyses, we found that the P-TEFb components, CDK9, Cyclin T1 and Cyclin T2 were localized to nuclear speckles, as well as in nucleolar-like bodies in pig germinal vesicle oocytes. Using nascent RNA labeling and small molecule inhibitors, we showed that inhibition of CDK9 activity abolished the transcription of GV oocytes globally. Moreover, using fluorescence in situ hybridization, in absence of CDK9 kinase activity the production of ribosomal RNAs was impaired. We also presented the evidences indicating that P-TEFb kinase activity is essential for resumption of oocyte meiosis and embryo development. Treatment with CDK9 inhibitors resulted in germinal vesicle arrest in maturing oocytes in vitro. Inhibition of CDK9 kinase activity did not interfere with in vitro fertilization and pronuclear formation. However, when in vitro produced zygotes were treated with CDK9 inhibitors, their development beyond the 4-cell stage was impaired. In these embryos, inhibition of CDK9 abrogated global transcriptional activity and rRNA production. Collectively, our data suggested that P-TEFb kinase activity is crucial for oocyte maturation, embryo development and regulation of RNA transcription in pig.
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NPM1 histone chaperone is upregulated in glioblastoma to promote cell survival and maintain nucleolar shape. Sci Rep 2015; 5:16495. [PMID: 26559910 PMCID: PMC4642306 DOI: 10.1038/srep16495] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2015] [Accepted: 10/14/2015] [Indexed: 01/08/2023] Open
Abstract
Glioblastoma (grade IV glioma) is the most common and aggressive adult brain tumor. A better understanding of the biology of glioblastoma cells is crucial to identify molecular targets stimulating cell death. NPM1 (nucleophosmin) is a multifunctional chaperone that plays an important role in cancer development. Herein, NPM1 was analyzed by immunohistochemistry in human astrocytic gliomas. NPM1 was detected in all tumors but with a significantly higher staining intensity in grade IV than in low grade tumors. Depletion of NPM1 had only modest effects on the viability of U251MG, U1242MG, and U343MGa Cl2:6 glioma cells, despite alterations in nucleolar morphology. Glioma cell cultures depleted of NPM1 exposed to micromolar levels of actinomycin D were more prone to cell death (apoptosis) compared to cultures retaining NPM1. We had previously found that NPM1 binds to linker histone H1.5. Here we could show that silencing of H1.5 triggered glioma cell apoptosis as evidenced by a marked increase in both the numbers of cleaved caspase-3+ cells and in the amounts of cleaved PARP. Enforced expression of NPM1 suppressed apoptosis in H1.5 depleted glioma cells. Although our studies would suggest little effectiveness of targeting NPM1 alone there could be potential using it as a combination treatment.
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10
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Perinucleolar heterochromatin during the cell differentiation using human leukemic neutrophils as a convenient model. J Appl Biomed 2015. [DOI: 10.1016/j.jab.2015.03.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
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11
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Holmberg Olausson K, Nistér M, Lindström MS. Loss of nucleolar histone chaperone NPM1 triggers rearrangement of heterochromatin and synergizes with a deficiency in DNA methyltransferase DNMT3A to drive ribosomal DNA transcription. J Biol Chem 2014; 289:34601-19. [PMID: 25349213 DOI: 10.1074/jbc.m114.569244] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Nucleoli are prominent nuclear structures assembled and organized around actively transcribed ribosomal DNA (rDNA). The nucleolus has emerged as a platform for the organization of chromatin enriched for repressive histone modifications associated with repetitive DNA. NPM1 is a nucleolar protein required for the maintenance of genome stability. However, the role of NPM1 in nucleolar chromatin dynamics and ribosome biogenesis remains unclear. We found that normal fibroblasts and cancer cells depleted of NPM1 displayed deformed nucleoli and a striking rearrangement of perinucleolar heterochromatin, as identified by immunofluorescence staining of trimethylated H3K9, trimethylated H3K27, and heterochromatin protein 1γ (HP1γ/CBX3). By co-immunoprecipitation we found NPM1 associated with HP1γ and core and linker histones. Moreover, NPM1 was required for efficient tethering of HP1γ-enriched chromatin to the nucleolus. We next tested whether the alterations in perinucleolar heterochromatin architecture correlated with a difference in the regulation of rDNA. U1242MG glioma cells depleted of NPM1 presented with altered silver staining of nucleolar organizer regions, coupled to a modest decrease in H3K9 di- and trimethylation at the rDNA promoter. rDNA transcription and cell proliferation were sustained in these cells, indicating that altered organization of heterochromatin was not secondary to inhibition of rDNA transcription. Furthermore, knockdown of DNA methyltransferase DNMT3A markedly enhanced rDNA transcription in NPM1-depleted U1242MG cells. In summary, this study highlights a function of NPM1 in the spatial organization of nucleolus-associated heterochromatin.
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Affiliation(s)
- Karl Holmberg Olausson
- From the Department of Oncology-Pathology, Karolinska Institutet, Cancer Center Karolinska, Karolinska University Hospital, SE-17176 Stockholm, Sweden
| | - Monica Nistér
- From the Department of Oncology-Pathology, Karolinska Institutet, Cancer Center Karolinska, Karolinska University Hospital, SE-17176 Stockholm, Sweden
| | - Mikael S Lindström
- From the Department of Oncology-Pathology, Karolinska Institutet, Cancer Center Karolinska, Karolinska University Hospital, SE-17176 Stockholm, Sweden
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12
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Shaiken TE, Opekun AR. Dissecting the cell to nucleus, perinucleus and cytosol. Sci Rep 2014; 4:4923. [PMID: 24815916 PMCID: PMC4017230 DOI: 10.1038/srep04923] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2014] [Accepted: 04/22/2014] [Indexed: 12/25/2022] Open
Abstract
Cells have been described under the microscope as organelles containing cytoplasm and the nucleus. However, an unnoted structure exists between the cytoplasm and the nucleoplasm of eukaryotic cells. In addition to the nuclear envelope, there exists a perinuclear region (PNR or perinucleus) with unknown composition and function. Until now, an investigation of the role of the perinucleus has been restricted by the absence of a PNR isolation method. This manuscript describes a perinucleus isolation technique on the basis of its unique compact organization. The perinucleus was found to contain approximately 15 to 18% of the total proteins of the mammalian cell, almost half of the proteins of nuclei. Using four different normal and cancer cell lines, it was shown that the composition of PNR is highly dynamic. Application of the method showed that translocation of the p53 tumor-suppressor protein to the perinucleus in immortalized MEF cells is correlated with the translocation of p53-stabilizing protein, nucleophosmin (B23), to the PNR. Herein, the concept of the perinuclear region is advanced as a formal, identifiable structure. The roles of the perinucleus in maintaining genome integrity, regulation of gene expression and understanding of malignant transformation are discussed.
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Affiliation(s)
- Tattym E Shaiken
- Department of Molecular and Cellular Oncology, University of Texas M. D. Anderson Cancer Center, Houston, TX 77030, USA
| | - Antone R Opekun
- Departments of Medicine & Pediatrics G.I. & S.A.H.S. Baylor College of Medicine-McNair Faculty Center A10.019 One Baylor Plaza (GI Medicine MS901), Houston, Texas 77030, USA
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13
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Tworzydlo W, Kisiel E, Bilinski SM. Embryos of the viviparous dermapteran, Arixenia esau develop sequentially in two compartments: terminal ovarian follicles and the uterus. PLoS One 2013; 8:e64087. [PMID: 23667700 PMCID: PMC3648550 DOI: 10.1371/journal.pone.0064087] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2012] [Accepted: 04/08/2013] [Indexed: 11/27/2022] Open
Abstract
Three main reproductive strategies have been described among insects: most common oviparity, ovoviviparity and viviparity. In the latter strategy, the embryonic development takes place within the body of the mother which provides gas exchange and nutrients for embryos. Here we present the results of histological and EM analyses of the female reproductive system of the viviparous earwig, Arixenia esau, focusing on all the modifications related to the viviparity. We show that in the studied species the embryonic development consists of two “physiological phases” that take place in two clearly disparate compartments, i.e. the terminal ovarian follicle and the uterus. In both compartments the embryos are associated with synthetically active epithelial cells. We suggest that these cells are involved in the nourishment of the embryo. Our results indicate that viviparity in arixeniids is more complex than previously considered. We propose the new term “pseudoplacento-uterotrophic viviparity” for this unique two-phase reproductive strategy.
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Affiliation(s)
- Waclaw Tworzydlo
- Department of Developmental Biology and Morphology of Invertebrates, Institute of Zoology, Jagiellonian University, Krakow, Poland.
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14
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Lindström MS. Elucidation of motifs in ribosomal protein S9 that mediate its nucleolar localization and binding to NPM1/nucleophosmin. PLoS One 2012; 7:e52476. [PMID: 23285058 PMCID: PMC3527548 DOI: 10.1371/journal.pone.0052476] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2012] [Accepted: 11/19/2012] [Indexed: 11/19/2022] Open
Abstract
Biogenesis of eukaryotic ribosomes occurs mainly in a specific subnuclear compartment, the nucleolus, and involves the coordinated assembly of ribosomal RNA and ribosomal proteins. Identification of amino acid sequences mediating nucleolar localization of ribosomal proteins may provide important clues to understand the early steps in ribosome biogenesis. Human ribosomal protein S9 (RPS9), known in prokaryotes as RPS4, plays a critical role in ribosome biogenesis and directly binds to ribosomal RNA. RPS9 is targeted to the nucleolus but the regions in the protein that determine its localization remains unknown. Cellular expression of RPS9 deletion mutants revealed that it has three regions capable of driving nuclear localization of a fused enhanced green fluorescent protein (EGFP). The first region was mapped to the RPS9 N-terminus while the second one was located in the proteins C-terminus. The central and third region in RPS9 also behaved as a strong nucleolar localization signal and was hence sufficient to cause accumulation of EGFP in the nucleolus. RPS9 was previously shown to interact with the abundant nucleolar chaperone NPM1 (nucleophosmin). Evaluating different RPS9 fragments for their ability to bind NPM1 indicated that there are two binding sites for NPM1 on RPS9. Enforced expression of NPM1 resulted in nucleolar accumulation of a predominantly nucleoplasmic RPS9 mutant. Moreover, it was found that expression of a subset of RPS9 deletion mutants resulted in altered nucleolar morphology as evidenced by changes in the localization patterns of NPM1, fibrillarin and the silver stained nucleolar organizer regions. In conclusion, RPS9 has three regions that each are competent for nuclear localization, but only the central region acted as a potent nucleolar localization signal. Interestingly, the RPS9 nucleolar localization signal is residing in a highly conserved domain corresponding to a ribosomal RNA binding site.
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Affiliation(s)
- Mikael S Lindström
- Department of Oncology-Pathology, Karolinska Institutet, Stockholm, Sweden.
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15
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Holmberg Olausson K, Nistér M, Lindström MS. p53 -Dependent and -Independent Nucleolar Stress Responses. Cells 2012; 1:774-98. [PMID: 24710530 PMCID: PMC3901145 DOI: 10.3390/cells1040774] [Citation(s) in RCA: 77] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2012] [Revised: 09/28/2012] [Accepted: 10/01/2012] [Indexed: 12/27/2022] Open
Abstract
The nucleolus has emerged as a cellular stress sensor and key regulator of p53-dependent and -independent stress responses. A variety of abnormal metabolic conditions, cytotoxic compounds, and physical insults induce alterations in nucleolar structure and function, a situation known as nucleolar or ribosomal stress. Ribosomal proteins, including RPL11 and RPL5, become increasingly bound to the p53 regulatory protein MDM2 following nucleolar stress. Ribosomal protein binding to MDM2 blocks its E3 ligase function leading to stabilization and activation of p53. In this review we focus on a number of novel regulators of the RPL5/RPL11-MDM2-p53 complex including PICT1 (GLTSCR2), MYBBP1A, PML and NEDD8. p53-independent pathways mediating the nucleolar stress response are also emerging and in particular the negative control that RPL11 exerts on Myc oncoprotein is of importance, given the role of Myc as a master regulator of ribosome biogenesis. We also briefly discuss the potential of chemotherapeutic drugs that specifically target RNA polymerase I to induce nucleolar stress.
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Affiliation(s)
- Karl Holmberg Olausson
- Department of Oncology-Pathology, Karolinska Institutet, Cancer Center Karolinska R8:05, Karolinska University Hospital in Solna, SE-17176, Stockholm, Sweden.
| | - Monica Nistér
- Department of Oncology-Pathology, Karolinska Institutet, Cancer Center Karolinska R8:05, Karolinska University Hospital in Solna, SE-17176, Stockholm, Sweden.
| | - Mikael S Lindström
- Department of Oncology-Pathology, Karolinska Institutet, Cancer Center Karolinska R8:05, Karolinska University Hospital in Solna, SE-17176, Stockholm, Sweden.
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16
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Wang J, Beauchemin M, Bertrand R. Phospho-Bcl-x(L)(Ser62) plays a key role at DNA damage-induced G(2) checkpoint. Cell Cycle 2012; 11:2159-69. [PMID: 22617334 PMCID: PMC3368867 DOI: 10.4161/cc.20672] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Accumulating evidence suggests that Bcl-xL, an anti-apoptotic member of the Bcl-2 family, also functions in cell cycle progression and cell cycle checkpoints. Analysis of a series of phosphorylation site mutants reveals that cells expressing Bcl-xL(Ser62Ala) mutant are less stable at the G 2 checkpoint and enter mitosis more rapidly than cells expressing wild-type Bcl-xL or Bcl-xL phosphorylation site mutants, including Thr41Ala, Ser43Ala, Thr47Ala, Ser56Ala and Thr115Ala. Analysis of the dynamic phosphorylation and location of phospho-Bcl-xL(Ser62) in unperturbed, synchronized cells and during DNA damage-induced G 2 arrest discloses that a pool of phospho-Bcl-xL(Ser62) accumulates into nucleolar structures in etoposide-exposed cells during G 2 arrest. In a series of in vitro kinase assays, pharmacological inhibitors and specific siRNAs experiments, we found that Polo kinase 1 and MAPK9/JNK2 are major protein kinases involved in Bcl-xL(Ser62) phosphorylation and accumulation into nucleolar structures during the G 2 checkpoint. In nucleoli, phospho-Bcl-xL(Ser62) binds to and co-localizes with Cdk1(cdc2), the key cyclin-dependent kinase required for entry into mitosis. These data indicate that during G 2 checkpoint, phospho-Bcl-xL(Ser62) stabilizes G 2 arrest by timely trapping of Cdk1(cdc2) in nucleolar structures to slow mitotic entry. It also highlights that DNA damage affects the dynamic composition of the nucleolus, which now emerges as a piece of the DNA damage response.
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Affiliation(s)
- Jianfang Wang
- Centre de recherche; Centre hospitalier de l’Université of Montréal (CRCHUM) - Hôpital Notre-Dame and Institut du Cancer de Montréal; Montréal, Québec, Canada
| | - Myriam Beauchemin
- Centre de recherche; Centre hospitalier de l’Université of Montréal (CRCHUM) - Hôpital Notre-Dame and Institut du Cancer de Montréal; Montréal, Québec, Canada
| | - Richard Bertrand
- Centre de recherche; Centre hospitalier de l’Université of Montréal (CRCHUM) - Hôpital Notre-Dame and Institut du Cancer de Montréal; Montréal, Québec, Canada
- Département de médecine; Université de Montréal; Montréal, Québec, Canada
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Zapotocky M, Mejstrikova E, Smetana K, Stary J, Trka J, Starkova J. Valproic acid triggers differentiation and apoptosis in AML1/ETO-positive leukemic cells specifically. Cancer Lett 2012; 319:144-153. [PMID: 22261333 DOI: 10.1016/j.canlet.2011.12.041] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2011] [Revised: 12/04/2011] [Accepted: 12/25/2011] [Indexed: 01/07/2023]
Abstract
Valproic acid (VPA) has extensive effects on leukemic blasts through its inhibition of histone deacetylases. The main goal of this study was to identify the subgroup of patients who may benefit most from VPA treatment. We examined the significance of t(8;21) chromosomal aberration for VPA treatment response among acute myeloid leukemia (AML) patients by direct comparison of AML1/ETO-negative vs. positive leukemic cell-lines as well as bone marrow blasts from AML patients. In t(8;21) AML, leukemogenesis is supposed to be induced via aberrant recruitment of histone deacetylases. AML cell lines of different genotypes (Kasumi-1, Kasumi-6, MV4;11, K562) and diagnostic bone marrow samples from patients were treated with VPA. VPA induced apoptosis in AML1/ETO-positive and MLL-AF4-positive cells in a dose-dependent manner. Differentiation, as indicated by changes in immunophenotype, was observed only in AML1/ETO-positive cells. VPA increased the expression of AML1 target genes - PU.1, C/EBPa, BPI and IGFBP7 only in AML1/ETO-positive cells. This AML1/ETO-specific effect was confirmed also using patient blasts isolated at the time of diagnosis. AML1/ETO-positive leukemia shows specific mechanism of VPA residing from differentiation followed by apoptosis that is accompanied by an increase in the expression of repressed AML1 target genes. Our data suggest that AML1/ETO-positive patients might derive the greatest benefit from VPA treatment.
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Affiliation(s)
- Michal Zapotocky
- CLIP, Department of Pediatric Hematology and Oncology, Charles University, 2nd Medical School, Prague, Czech Republic
| | - Ester Mejstrikova
- CLIP, Department of Pediatric Hematology and Oncology, Charles University, 2nd Medical School, Prague, Czech Republic
| | - Karel Smetana
- Institute of Hematology and Blood Transfusion, Charles University, 1st Medical School, Prague, Czech Republic
| | - Jan Stary
- CLIP, Department of Pediatric Hematology and Oncology, Charles University, 2nd Medical School, Prague, Czech Republic
| | - Jan Trka
- CLIP, Department of Pediatric Hematology and Oncology, Charles University, 2nd Medical School, Prague, Czech Republic.
| | - Julia Starkova
- CLIP, Department of Pediatric Hematology and Oncology, Charles University, 2nd Medical School, Prague, Czech Republic
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18
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19
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Hernandez-Verdun D, Roussel P, Thiry M, Sirri V, Lafontaine DLJ. The nucleolus: structure/function relationship in RNA metabolism. WILEY INTERDISCIPLINARY REVIEWS-RNA 2010; 1:415-31. [PMID: 21956940 DOI: 10.1002/wrna.39] [Citation(s) in RCA: 179] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The nucleolus is the ribosome factory of the cells. This is the nuclear domain where ribosomal RNAs are synthesized, processed, and assembled with ribosomal proteins. Here we describe the classical tripartite organization of the nucleolus in mammals, reflecting ribosomal gene transcription and pre-ribosomal RNA (pre-rRNA) processing efficiency: fibrillar center, dense fibrillar component, and granular component. We review the nucleolar organization across evolution from the bipartite organization in yeast to the tripartite organization in humans. We discuss the basic principles of nucleolar assembly and nucleolar structure/function relationship in RNA metabolism. The control of nucleolar assembly is presented as well as the role of pre-existing machineries and pre-rRNAs inherited from the previous cell cycle. In addition, nucleoli carry many essential extra ribosomal functions and are closely linked to cellular homeostasis and human health. The last part of this review presents recent advances in nucleolar dysfunctions in human pathology such as cancer and virus infections that modify the nucleolar organization.
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Affiliation(s)
- Danièle Hernandez-Verdun
- Nuclei and cell cycle, Institut Jacques Monod-UMR 7592 CNRS, Université Paris Diderot, 75205 Paris cedex 13, France.
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20
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Hacot S, Coute Y, Belin S, Albaret MA, Mertani HC, Sanchez JC, Rosa-Calatrava M, Diaz JJ. Isolation of nucleoli. ACTA ACUST UNITED AC 2010; Chapter 3:Unit3.36. [PMID: 20521233 DOI: 10.1002/0471143030.cb0336s47] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Nucleoli are now recognized as multi-functional nuclear domains involved in several fundamental cell processes such as ribosome biogenesis, regulation of the assembly of non-ribosomal ribonucleoprotein complexes, tRNA maturation, sequestration of protein, viral infection, and cellular ageing. Extensive proteomic analyses of these nucleolar domains after their purification have contributed to the description of their multiple biological functions. Because nucleoli are the largest and densest nuclear structures, they are easily amenable to purification from nuclei of cultured animal cells using the protocol described in this unit.
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21
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Torres R, Ramirez JC. A chemokine targets the nucleus: Cxcl12-gamma isoform localizes to the nucleolus in adult mouse heart. PLoS One 2009; 4:e7570. [PMID: 19859557 PMCID: PMC2762742 DOI: 10.1371/journal.pone.0007570] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2009] [Accepted: 10/01/2009] [Indexed: 12/18/2022] Open
Abstract
Chemokines are extracellular mediators of complex regulatory circuits involved principally in cell-to-cell communication. Most studies to date of the essential chemokine Cxcl12 (Sdf-1) have focused on the ubiquitously expressed secreted isoforms α and β. Here we show that, unlike these isoforms and all other known chemokines, the alternatively transcribed γ isoform is an intracellular protein that localizes to the nucleolus in differentiated mouse Cardiac tissue. Our results demonstrate that nucleolar transportation is encoded by a nucleolar-localization signal in the unique carboxy-terminal region of Sdf-1γ, and is competent both in vivo and in vitro. The molecular mechanism underlying these unusual chemokine properties involves cardiac-specific transcription of an mRNA containing a unique short-leader sequence lacking the signal peptide and translation from a non-canonical CUG codon. Our results provide an example of genome economy even for essential and highly conserved genes such as Cxcl12, and suggest that chemokines can exert tissue specific functions unrelated to cell-to-cell communication.
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Affiliation(s)
- Raul Torres
- Viral Vector Facility, Technical Unit of Gene Targeting, Fundacion CNIC National Centre for Cardiovascular Research, Madrid, Spain
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22
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Smetana K, Jirásková I, Mikulenková D, Klamová H. The translocation of AgNORs in large nucleoli of early granulocyte progenitors in patients suffering from chronic phase of chronic myeloid leukaemia. J Appl Biomed 2009. [DOI: 10.32725/jab.2009.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
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23
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Kotoglou P, Kalaitzakis A, Vezyraki P, Tzavaras T, Michalis LK, Dantzer F, Jung JU, Angelidis C. Hsp70 translocates to the nuclei and nucleoli, binds to XRCC1 and PARP-1, and protects HeLa cells from single-strand DNA breaks. Cell Stress Chaperones 2009; 14:391-406. [PMID: 19089598 PMCID: PMC2728274 DOI: 10.1007/s12192-008-0093-6] [Citation(s) in RCA: 84] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2008] [Revised: 10/28/2008] [Accepted: 11/24/2008] [Indexed: 02/01/2023] Open
Abstract
For many years, there has been uncertainty concerning the reason for Hsp70 translocation to the nucleus and nucleolus. Herein, we propose that Hsp70 translocates to the nucleus and nucleoli in order to participate in pathways related to the protection of the nucleoplasmic DNA or ribosomal DNA from single-strand breaks. The absence of Hsp70 in HeLa cells, via Hsp70 gene silencing (knockdown), indicated the essential role of Hsp70 in DNA integrity. Therefore, HeLa Hsp70 depleted cells were very sensitive in heat treatment and their DNA breaks were multiple compared to that of control HeLa cells. The molecular mechanism with which Hsp70 performs its role at the level of nucleus and nucleolus during stress was examined. Hsp70 co-localizes with PARP1 in the nucleus/nucleoli as was observed in confocal studies and binds to the BCRT domain of PARP1 as was revealed with protein-protein interaction assays. It was also found that Hsp70 binds simultaneously to XRCC1 and PARP-1, indicating that Hsp70 function takes place at the level of DNA repair and possibly at the base excision repair system. Making a hypothetical model, we have suggested that Hsp70 is the molecule that binds and interrelates with PARP1 creating the repair proteins simultaneously, such as XRCC1, at the single-strand DNA breaks. Our data partially clarify a previously unrecognized cellular response to heat stress. Finally, we can speculate that Hsp70 plays a role in the quality and integrity of DNA.
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Affiliation(s)
- Polychronis Kotoglou
- Laboratory of General Biology, Medical School, University of Ioannina, Ioannina, 45110 Greece
| | - Alexandros Kalaitzakis
- Laboratory of General Biology, Medical School, University of Ioannina, Ioannina, 45110 Greece
| | - Patra Vezyraki
- Laboratory of Experimental Physiology, Medical School, University of Ioannina, Ioannina, 45110 Greece
| | - Theodore Tzavaras
- Laboratory of General Biology, Medical School, University of Ioannina, Ioannina, 45110 Greece
| | - Lampros K. Michalis
- Michaileidion Cardiac Center, Medical School, University of Ioannina, Ioannina, 45110 Greece
- Department of Cardiology, Medical School, University of Ioannina, Ioannina, 45110 Greece
| | - Francoise Dantzer
- Integrite du Genome, Ecole Superieure de Biotechnologie de Strasbourg, Unite Mixte de Recherche 7175, 67412 Illkirch, France
| | - Jae U. Jung
- Department of Microbiology and Molecular Genetics, Tumor Virology Division, New England Primate Research Center, Harvard Medical School, 1 Pine Hill Drive, Southborough, MA 01772-9102 USA
| | - Charalampos Angelidis
- Laboratory of General Biology, Medical School, University of Ioannina, Ioannina, 45110 Greece
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24
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Treacle recruits RNA polymerase I complex to the nucleolus that is independent of UBF. Biochem Biophys Res Commun 2009; 386:396-401. [PMID: 19527688 DOI: 10.1016/j.bbrc.2009.06.050] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2009] [Accepted: 06/09/2009] [Indexed: 11/22/2022]
Abstract
Mutations in treacle lead to Treacher Collins syndrome (TCS), an autosomal dominant disorder of craniofacial development. Treacle associates with upstream binding factor (UBF) to regulate rRNA gene (rDNA) transcription, but the precise mechanisms mediated by treacle remain elusive. Here we show that the central repeated domain of treacle binds with RNA polymerase I (Pol I), while that the treacle C-terminus is involved in rDNA promoter recognition and UBF recruitment. Knockdown of treacle resulted in dispersion of Pol I and UBF away from nucleolus, whereas interactions of treacle with Pol I and rDNA promoter were not disrupted by UBF depletion. These findings indicate that treacle, but not UBF, is essential for nucleolar recruitment of Pol I transcription complex. Furthermore, C-terminally truncated treacle, mimicking TCS-associated mutations, failed to target to the nucleolus, possibly causing loss-of-function in the mutant treacle. Our observations support that TCS results from haploinsufficiency of treacle.
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Abstract
The heavy metal mercury is ubiquitously distributed in the environment resulting in permanent low-level exposure in human populations. Mercury can be encountered in three main chemical forms (elemental, inorganic, and organic) which can affect the immune system in different ways. In this review, we describe the effects of these various forms of mercury exposure on immune cells in humans and animals. In genetically susceptible mice or rats, subtoxic doses of mercury induce the production of highly specific autoantibodies as well as a generalized activation of the immune system. We review studies performed in this model and discuss their implications for the role of environmental chemicals in human autoimmunity.
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Affiliation(s)
- Jaya Vas
- Department of Microbiology and Immunology, Temple University School of Medicine, Philadelphia, PA 19140, USA
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26
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On the nucleolar and cytoplasmic RNA density during "cell dedifferentiation" represented by blastic transformation of human mature T lymphocytes - a cytochemical study. Folia Histochem Cytobiol 2009; 46:429-32. [DOI: 10.2478/v10042-008-0074-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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27
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Silverman GJ, Srikrishnan R, Germar K, Goodyear CS, Andrews KA, Ginzler EM, Tsao BP. Genetic imprinting of autoantibody repertoires in systemic lupus erythematosus patients. Clin Exp Immunol 2008; 153:102-16. [PMID: 18510544 DOI: 10.1111/j.1365-2249.2008.03680.x] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Systemic lupus erythematosus (SLE) is an autoimmune disease distinguished by great heterogeneity in clinical manifestations and autoantibody expression. While only a handful of autoantibody specificities have proved useful for clinical diagnosis, to characterize complex lupus-associated autoantibody profiles more fully we have applied proteome microarray technology. Our multiplex microarrays included control ligands and 65-autoantigens, which represent diverse nuclear and cytoplasmic antigens recognized by disease-associated and natural autoantibodies. From longitudinal surveys of unrelated SLE patients, we found that autoantibody profile patterns can be patient-specific and highly stable overtime. From profiles of 38 SLE patients that included 14 sets of SLE twins, autoantibodies to the phospholipid neo-determinants, malondialdehyde (MDA) and phosphorylcholine (PC), which are exposed on apoptotic but not healthy cells, were among the most prevalent and highly expressed. We also found that immunoglobulin M (IgM) reactivity to MDA and PC ligands had significant direct correlations with DNA-containing antigens, while such a general relationship was not found with a panel of RNA-related antigens, or for IgG-autoantibodies. Significantly, hierarchical analysis revealed co-distribution/clustering of the IgM autoantibody repertoire patterns for six of 14 twin sets, and such patterns were even more common (10 of 14) for IgG autoantibody profiles. Our findings highlight the potentially distinct roles of IgM and IgG autoantibodies, as we postulate that the direct correlations for IgM autoantibodies to DNA antigens with apoptosis-related determinants may be due to co-expression arising from common pro-homeostatic protective roles. In contrast, the sharing of IgG autoantibody fingerprints by monozygotic twins suggests that lupus IgG autoantibodies can arise in predisposed individuals in genetically determined patterns.
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Affiliation(s)
- G J Silverman
- Rheumatic Diseases Core Center and the Laboratory of B-cell Immunobiology, University of California, San Diego, CA 92093-0663, USA
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28
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Callé A, Ugrinova I, Epstein AL, Bouvet P, Diaz JJ, Greco A. Nucleolin is required for an efficient herpes simplex virus type 1 infection. J Virol 2008; 82:4762-73. [PMID: 18321972 PMCID: PMC2346767 DOI: 10.1128/jvi.00077-08] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2008] [Accepted: 02/27/2008] [Indexed: 11/20/2022] Open
Abstract
Productive infection by herpes simplex virus type 1 (HSV-1), which occurs in the host cell nucleus, is accompanied by dramatic modifications of the nuclear architecture, including profound alterations of nucleolar morphology. Here, we show that the three most abundant nucleolar proteins--nucleolin, B23, and fibrillarin--are redistributed out of the nucleoli as a consequence of HSV-1 infection. We show that the amount of nucleolin increases progressively during the course of infection. We demonstrate for the first time that a nucleolar protein, i.e., nucleolin, colocalizes with ICP8 in the viral replication compartments, at the time when viral replication is effective, suggesting an involvement of nucleolin in the HSV-1 DNA replication process. At later times of infection, a granular form of nucleolin localizes to the cytoplasm, in structures that display the characteristic features of aggresomes, indicating that this form of nucleolin is very probably destined for degradation. The delocalization of nucleolin from the nucleoli requires the viral ICP4 protein or a factor(s) whose expression involves ICP4. Using small interfering RNA technology, we show that viral replication requires a high level of nucleolin expression, demonstrating for the first time a direct role for a nucleolar protein in herpes simplex virus biology.
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29
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Smetana K, Otevřelová P, Kalousek I. Heterochromatin density in the course of cell "dedifferentiation" represented by blastic transformation of human mature T lymphocytes. J Appl Biomed 2007. [DOI: 10.32725/jab.2007.025] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
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30
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Smetana K, Zápotocký M, Starková J, Trka J. Effect of histone deacetylase inhibitors on the cell nucleus and nucleolus of leukemic myeloblasts in vitro - a cytochemical study. Acta Histochem 2007; 109:413-9. [PMID: 17559910 DOI: 10.1016/j.acthis.2007.04.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2006] [Revised: 04/13/2007] [Accepted: 04/16/2007] [Indexed: 12/15/2022]
Abstract
The present study was designed to provide complementary information on the effects of histone deacetylase inhibitors (HDACi's) such as trichostatin A (TSA) and sodium valproate (VAP) on nuclei and nucleoli of leukemic myeloblasts represented by cultured Kasumi-1 cells. The number of apoptotic cells and bodies with characteristic chromatin condensation and fragmentation was greater after TSA treatment. However, in contrast to TSA, myeloblasts treated with VPA recovered and started to proliferate again. TSA-treated myeloblasts with a fine chromatin structure exhibited an intense phagocytosis of cell fragments. The decreased number and translocation of silver-stained proteins of nucleolus organiser regions (AgNORs) in large nucleoli of myeloblasts treated with HDACi's indicated that these cells entered apoptosis and/or ageing without preceding terminal maturation. The nucleolar asynchrony observed in an increased number of treated cells with both HDACi's studied here possibly represented myeloblasts resistant to such treatment. In conclusion, this study demonstrates that the chromatin structure and nucleoli visualised by simple cytochemical procedures provides useful information on the effects of HDACi's on myeloblasts and facilitated detection of these effects at the single cell level.
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Affiliation(s)
- K Smetana
- Institute of Haematology and Blood Transfusion, Prague, Czech Republic.
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31
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Smetana K, Jirásková I, Klamová H. Are microproerythroblasts in human bone marrow real or artefacts? A cytochemical note. Acta Histochem 2005; 107:313-7. [PMID: 16054197 DOI: 10.1016/j.acthis.2005.06.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2005] [Accepted: 06/06/2005] [Indexed: 11/18/2022]
Abstract
Early erythroid precursors were studied in human bone marrow smears to provide more information on small proerythroblasts--"microproerythroblasts"--using a silver reaction to demonstrate silver stained nucleolar organizer regions (AgNORs) and light microscopic densitometry of large irregularly shaped nucleoli and cytoplasm stained for RNA. No significant differences were found for the density of such nucleoli and basophilic cytoplasm between characteristic large proerythroblasts with a nuclear diameter larger that 9 microm (K2 and K1 erythroblasts) and small proerythroblasts--"microproerythroblasts" representing a subpopulation of K1/2 erythroblasts (early basophilic erythroblasts), which are characterized by a smaller nuclear diameter. In addition, large irregularly shaped nucleoli of "microproerythroblasts" possessed numerous silver stained particles representing AgNORs similar to those of large proerythroblasts. The number of AgNORs in "microproerythroblasts" was slightly, but significantly, smaller than that in large characteristic proerythroblasts.
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Affiliation(s)
- Karel Smetana
- Clinical Department, Institute of Haematology and Blood Transfusion, U nemocnice 1, Prague 2, 128 20 Czech Republic.
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32
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Smetana K, Klamová H, Pluskalová M, Stöckbauer P, Hrkal Z. To the intranucleolar translocation of AgNORs in leukemic early granulocytic and plasmacytic precursors. Histochem Cell Biol 2005; 125:165-70. [PMID: 16142449 DOI: 10.1007/s00418-005-0059-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/07/2005] [Indexed: 10/25/2022]
Abstract
Early leukemic granulocytic and plasmacytic precursors were studied in vitro and in vivo to provide an information on the intranucleolar distribution of AgNORs (silver stained nucleolus organizer regions). In most of these cells AgNORs appeared as clusters of silver stained particles distributed in the whole nucleolar body. On the other hand, in some leukemic early granulocytic precursors, i.e., in myeloblasts and promyelocytes enlarged AgNORs were translocated in the nucleolar peripheral part. In addition, the number of translocated AgNORs at the nucleolar periphery was significantly smaller. Such translocation of a reduced number of AgNORs was easily produced by experimental aging, i.e., starving of cultured leukemic early granulocytic precursors (HL-60 and K562 cells) in vitro and seems to be reversible. Similar translocation of a reduced number of AgNORs was also produced by aging of leukemic plasmacytic precursors. Thus, the translocation of the reduced number of AgNORs to the nucleolar periphery in some blastic leukemic hematopoietic cells might be an useful marker of their aging at the single cell level. However, more studies in this direction are required in the future.
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Affiliation(s)
- Karel Smetana
- Institute of Hematology and Blood Transfusion, U nemocnice 1, Prague 2, 128 20, Czech Republic.
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33
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Smetana K, Pluskalová M, Jirásková I, Hrkal Z. A morphological and cytochemical note to the reversible intranucleolar translocation of AgNORs (silver stained nucleolus organizer regions) in early leukemic granulocytic progenitors represented by cultured K 562 cells. J Appl Biomed 2005. [DOI: 10.32725/jab.2005.025] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
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34
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Rowley B, Monestier M. Mechanisms of heavy metal-induced autoimmunity. Mol Immunol 2005; 42:833-8. [PMID: 15829271 DOI: 10.1016/j.molimm.2004.07.050] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2004] [Accepted: 07/07/2004] [Indexed: 11/24/2022]
Abstract
Chemical exposure can trigger or accelerate the development of autoimmune manifestations. Although heavy metals are elementary chemical structures, they can have profound and complex effects on the immune system. In genetically susceptible mice or rats, administration of subtoxic doses of mercury induces both the production of highly specific autoantibodies and a polyclonal activation of the immune system. We review in this article some of the mechanisms by which heavy metal exposure can lead to autoimmunity.
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Affiliation(s)
- Benjamin Rowley
- Department of Microbiology and Immunology, Temple University School of Medicine, Philadelphia, PA 19140, USA
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35
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Morency E, Couté Y, Thomas J, Texier P, Lomonte P. The protein ICP0 of herpes simplex virus type 1 is targeted to nucleoli of infected cells. Arch Virol 2005; 150:2387-95. [PMID: 15883654 DOI: 10.1007/s00705-005-0546-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2005] [Accepted: 03/23/2005] [Indexed: 10/25/2022]
Abstract
This study describes the nucleolar localization of the viral protein ICP0 of herpes simplex virus type 1. We show that the RING finger domain of ICP0 is essential for ICP0 to localize in nucleoli of transfected and 4 hour-infected cells. ICP0 forms particular intranucleolar domains that do not correspond to any known nucleolar domains. This distribution was confirmed by immunoblots performed on fractionated infected cells. Quantitative RT-PCR experiments indicated that ICP0 did not increase the transcription from the RNA polymerase I (Pol I) promoter in transfected cells, an effect opposite to that observed on viral and cellular Pol II promoters. Nucleoli are thus, after PML bodies and centromeres, a novel nuclear structure targeted by ICP0.
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Affiliation(s)
- E Morency
- Centre de Génétique Moléculaire et Cellulaire, UMR5534-CNRS, Equipe Silencing Viral et Remodelage de la Chromatine Université Claude Bernard Lyon 1, Villeurbanne, France
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36
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Shav-Tal Y, Blechman J, Darzacq X, Montagna C, Dye BT, Patton JG, Singer RH, Zipori D. Dynamic sorting of nuclear components into distinct nucleolar caps during transcriptional inhibition. Mol Biol Cell 2005; 16:2395-413. [PMID: 15758027 PMCID: PMC1087244 DOI: 10.1091/mbc.e04-11-0992] [Citation(s) in RCA: 272] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Nucleolar segregation is observed under some physiological conditions of transcriptional arrest. This process can be mimicked by transcriptional arrest after actinomycin D treatment leading to the segregation of nucleolar components and the formation of unique structures termed nucleolar caps surrounding a central body. These nucleolar caps have been proposed to arise from the segregation of nucleolar components. We show that contrary to prevailing notion, a group of nucleoplasmic proteins, mostly RNA binding proteins, relocalized from the nucleoplasm to a specific nucleolar cap during transcriptional inhibition. For instance, an exclusively nucleoplasmic protein, the splicing factor PSF, localized to nucleolar caps under these conditions. This structure also contained pre-rRNA transcripts, but other caps contained either nucleolar proteins, PML, or Cajal body proteins and in addition nucleolar or Cajal body RNAs. In contrast to the capping of the nucleoplasmic components, nucleolar granular component proteins dispersed into the nucleoplasm, although at least two (p14/ARF and MRP RNA) were retained in the central body. The nucleolar caps are dynamic structures as determined using photobleaching and require energy for their formation. These findings demonstrate that the process of nucleolar segregation and capping involves energy-dependent repositioning of nuclear proteins and RNAs and emphasize the dynamic characteristics of nuclear domain formation in response to cellular stress.
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Affiliation(s)
- Yaron Shav-Tal
- Department of Molecular Cell Biology, The Weizmann Institute of Science, Rehovot, 76100 Israel.
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37
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Saville MK, Sparks A, Xirodimas DP, Wardrop J, Stevenson LF, Bourdon JC, Woods YL, Lane DP. Regulation of p53 by the ubiquitin-conjugating enzymes UbcH5B/C in vivo. J Biol Chem 2004; 279:42169-81. [PMID: 15280377 DOI: 10.1074/jbc.m403362200] [Citation(s) in RCA: 117] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
p53 levels are regulated by ubiquitination and 26 S proteasome-mediated degradation. p53 is a substrate for the E3 ligase Mdm2, however, the ubiquitin-conjugating enzymes (E2s) involved in p53 ubiquitination in intact cells have not been defined previously. To investigate the E2 specificity of Mdm2 we carried out an in vitro screen using a panel of ubiquitin E2s. Of the E2s tested only UbcH5A, -B, and -C and E2-25K support Mdm2-mediated ubiquitination of p53. The same E2s also support Mdm2 auto-ubiquitination. Small interfering RNA-mediated knockdown of UbcH5B/C causes accumulation of Mdm2 and p53 in unstressed cells. We show that suppression of UbcH5B/C inhibits p53 ubiquitination and degradation. Despite up-regulating the level of nuclear p53, UbcH5B/C knockdown does not on its own result in an increase in p53 transcriptional activity or sensitize p53 to activation by the therapeutic drugs doxorubicin and actinomycin D. We provide evidence that Mdm2 is responsible, at least in part, for repression of the transcriptional activity of the accumulated p53. In MCF7 cells levels of UbcH5B/C are reduced by doxorubicin and actinomycin D. This observation and the sensitivity of p53 expression to levels of UbcH5B/C raise the possibility that E2 regulation could be involved in signaling pathways that control the stability of p53. Our data indicate that UbcH5B/C are physiological E2s for Mdm2, which make a significant contribution to the maintenance of low levels of p53 and Mdm2 in unstressed cells and that inhibition of p53 ubiquitination and degradation by targeting UbcH5B/C is not sufficient to up-regulate p53 transcriptional activity.
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Affiliation(s)
- Mark K Saville
- Cancer Research UK, Cell Transformation Research Group, Department of Surgery and Molecular Oncology, Ninewells Hospital and Medical School, University of Dundee, Dundee DD1 9SY, Scotland, UK.
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38
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Hoffelder DR, Luo L, Burke NA, Watkins SC, Gollin SM, Saunders WS. Resolution of anaphase bridges in cancer cells. Chromosoma 2004; 112:389-97. [PMID: 15156327 DOI: 10.1007/s00412-004-0284-6] [Citation(s) in RCA: 194] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2004] [Revised: 04/02/2004] [Accepted: 04/05/2004] [Indexed: 11/28/2022]
Abstract
Chromosomal instability is a key step in the generation of the cancer cell karyotype. An indicator of unstable chromosomes is the presence of chromatin bridges during anaphase. We examined in detail the fate of anaphase bridges in cultured oral squamous cell carcinoma cells in real-time. Surprisingly, chromosomes in bridges typically resolve by breaking into multiple fragments. Often these fragments give rise to micronuclei (MN) at the end of mitosis. The formation of MN is shown to have important consequences for the cell. We found that MN have incomplete nuclear pore complex (NPC) formation and nuclear import defects and the chromatin within has greatly reduced transcriptional activity. Thus, a major consequence of the presence of anaphase bridges is the regular sequestration of chromatin into genetically inert MN. This represents another source of ongoing genetic instability in cancer cells.
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Affiliation(s)
- Diane R Hoffelder
- Department of Biological Sciences, University of Pittsburgh, 258 Crawford Hall, 15260, Pittsburgh, PA 15260, USA
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39
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Gonda K, Fowler J, Katoku-Kikyo N, Haroldson J, Wudel J, Kikyo N. Reversible disassembly of somatic nucleoli by the germ cell proteins FRGY2a and FRGY2b. Nat Cell Biol 2003; 5:205-10. [PMID: 12589397 DOI: 10.1038/ncb939] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2002] [Revised: 12/24/2002] [Accepted: 01/08/2003] [Indexed: 11/09/2022]
Abstract
Egg cytoplasm has the capability to reprogramme differentiated somatic nuclei, as shown by nuclear transplantation in animal cloning. The nucleoli of donor nuclei are rapidly disassembled on injection into interphase eggs and are correctly reassembled when donor transcription initiates in the early embryos of frogs and mammals, recapitulating the physiological nucleolar dynamics of early embryogenesis. This is one of the most remarkable structural reorganizations of somatic nuclei in nuclear cloning. Despite the long history of nuclear cloning, almost nothing is known about the molecular mechanism of nucleolar disassembly in egg cytoplasm. Here we show that the Xenopus germ cell proteins FRGY2a and FRGY2b reversibly disassemble somatic nucleoli in egg cytoplasm, independently of continuing ribosomal RNA transcription. The carboxy-terminal domain of FRGY2a, which localizes to the nucleoli, is sufficient for nucleolar disassembly in transfected cells. Our results show that a single protein fragment can trigger reversible disassembly of the complex nucleolar structure.
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Affiliation(s)
- Koichi Gonda
- Stem Cell Institute and Division of Hematology, Oncology and Transplantation, Department of Medicine, University of Minnesota, Mayo Mail Code 716, 420 Delaware Street, Minneapolis, Minnesota 55455, USA
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40
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Scherl A, Couté Y, Déon C, Callé A, Kindbeiter K, Sanchez JC, Greco A, Hochstrasser D, Diaz JJ. Functional proteomic analysis of human nucleolus. Mol Biol Cell 2002; 13:4100-9. [PMID: 12429849 PMCID: PMC133617 DOI: 10.1091/mbc.e02-05-0271] [Citation(s) in RCA: 365] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The notion of a "plurifunctional" nucleolus is now well established. However, molecular mechanisms underlying the biological processes occurring within this nuclear domain remain only partially understood. As a first step in elucidating these mechanisms we have carried out a proteomic analysis to draw up a list of proteins present within nucleoli of HeLa cells. This analysis allowed the identification of 213 different nucleolar proteins. This catalog complements that of the 271 proteins obtained recently by others, giving a total of approximately 350 different nucleolar proteins. Functional classification of these proteins allowed outlining several biological processes taking place within nucleoli. Bioinformatic analyses permitted the assignment of hypothetical functions for 43 proteins for which no functional information is available. Notably, a role in ribosome biogenesis was proposed for 31 proteins. More generally, this functional classification reinforces the plurifunctional nature of nucleoli and provides convincing evidence that nucleoli may play a central role in the control of gene expression. Finally, this analysis supports the recent demonstration of a coupling of transcription and translation in higher eukaryotes.
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Affiliation(s)
- Alexander Scherl
- Central Clinical Chemistry Laboratory, Geneva University Hospital, 1211 Geneva 14, Switzerland
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41
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Smetana K, Cajthamlová H, Grebenová D, Jirásková I, Hrkal Z. Nucleolar asynchrony observed in HL-60 leukemic granulocytic precursors resistant to 5-aminolaevulinic acid-based photodynamic treatment. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY. B, BIOLOGY 2002; 67:201-3. [PMID: 12167320 DOI: 10.1016/s1011-1344(02)00307-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
To provide more information on the 5-aminolaevulinic acid (ALA)-induced photodynamic effect on nucleoli, morphologically expressed nucleolar asynchrony (the presence of 'active' large nucleoli with an uniform distribution of RNA and 'resting' ring-shaped nucleoli in one and the same nucleus) was studied in cultured HL-60 leukemic granulocytic precursors using a simple cytochemical procedure for the demonstration of RNA. Nucleolar asynchrony was mainly expressed in cells which were apparently resistant to ALA-based photodynamic treatment (PDT) since most of them (about 75%) exhibited this phenomenon.
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Affiliation(s)
- Karel Smetana
- Institute of Hematology and Blood Transfusion, 128 20 U nemocnice, Prague 2, Czech Republic.
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42
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Utama B, Kennedy D, Ru K, Mattick JS. Isolation and characterization of a new nucleolar protein, Nrap, that is conserved from yeast to humans. Genes Cells 2002; 7:115-32. [PMID: 11895476 DOI: 10.1046/j.1356-9597.2001.00507.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND The nucleolus is the site of rRNA synthesis and processing in eukaryotic cells, but its composition remains poorly understood. RESULTS We have identified a novel nucleolar RNA-associated protein (Nrap) which is highly conserved from yeast (Saccharomyces cerevisiae) to human, with homologues in mouse, Drosophila melanogaster, Caenorhabditis elegans, Arabidopsis thaliana, Schizosaccharomyces pombe, and other species. In the mouse, we have found that Nrap is ubiquitously expressed and is specifically localized in the nucleolus. We have also identified splice variants in human and mouse, and defined the intron-exon structure of the human Nrap gene. Nrap is inherited into daughter nuclei by associating with the condensed chromosomes during mitosis. RNase treatment of permeabilized cells indicated that the nucleolar localization of Nrap is RNA dependent. The effects of actinomycin D, cycloheximide and 5,6-dichloro-beta-d-ribofuranosyl-benzimidazole on Nrap expression and distribution in cultured cells suggest that Nrap is associated with the pre-rRNA transcript. CONCLUSIONS Nrap is a large nucleolar protein (of more than 1000 amino acids), and is a new class of protein with new structural and functional motifs. Nrap appears to be associated with ribosome biogenesis by interacting with pre-rRNA primary transcript.
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Affiliation(s)
- Budi Utama
- Centre for Functional and Applied Genomics, Institute for Molecular Bioscience, University of Queensland, St. Lucia, QLD 4072, Australia
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43
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Smetana K, Busch R, Chan PK, Smetana K, Busch H. Immunocytochemical localization of nucleophosmin and RH-II/Gu protein in nucleoli of HeLa cells after treatment with actinomycin D. Acta Histochem 2001; 103:325-33. [PMID: 11482378 DOI: 10.1078/0065-1281-00598] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
HeLa cells were studied with the use of light microscopical immunocytochemistry to obtain more information on the nucleolar localization of nucleophosmin (B23 protein) and RH-II/Gu protein. In control cells these proteins are colocalized. After structural rearrangement of nucleoli induced by actinomycin D, nucleophosmin was present in the nucleolar periphery and nucleolar peripheral caps. In contrast, RH-II/Gu protein was observed mainly in central regions of nucleoli as a compact body. However, in some nucleoli the proteins colocalized in a small portion of the peripheral nucleolar cap. The proteins were also colocalized in micronucleoli but occasionally RH-II/Gu protein was absent or both proteins were not present.
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Affiliation(s)
- K Smetana
- Department of Pharmacology, Baylor College of Medicine, Houston, USA.
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44
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Llanos S, Clark PA, Rowe J, Peters G. Stabilization of p53 by p14ARF without relocation of MDM2 to the nucleolus. Nat Cell Biol 2001; 3:445-52. [PMID: 11331871 DOI: 10.1038/35074506] [Citation(s) in RCA: 186] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The alternative product of the human INK4a/ARF locus, p14ARF, has the potential to act as a tumour suppressor by binding to and inhibiting the p53 antagonist MDM2. Current models propose that ARF function depends on its ability to sequester MDM2 in the nucleolus. Here we describe situations in which stabilization of MDM2 and p53 occur without relocalization of endogenous MDM2 from the nucleoplasm. Conversely, forms of ARF that do not accumulate in the nucleolus retain the capacity to stabilize MDM2 and p53. We therefore propose that nucleolar localization is not essential for ARF function but may enhance the availability of ARF to inhibit MDM2.
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Affiliation(s)
- S Llanos
- Imperial Cancer Research Fund, 44 Lincoln's Inn Fields, London WC2A 3PX, UK
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45
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Chen M, von Mikecz A. Specific inhibition of rRNA transcription and dynamic relocation of fibrillarin induced by mercury. Exp Cell Res 2000; 259:225-38. [PMID: 10942594 DOI: 10.1006/excr.2000.4923] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Current evidence suggests that the nucleolus is composed of different substructures that are dynamic and form in response to the requirement for new ribosome synthesis. Thus, agents that disrupt nucleolar organization may deregulate basic cellular events and eventually contribute to human disease. Here we report that environmentally relevant concentrations (5 microM) of inorganic mercury induce a redistribution of nucleolar protein fibrillarin from the nucleolus to the nucleoplasm in epithelial cell lines. Since treatment with transcription inhibitors led to a similar relocation of fibrillarin, the effects of mercury on transcription were studied by run-on transcription assays: mercuric ions specifically blocked synthesis of ribosomal RNA, whereas activity of RNA polymerase II remained unchanged and occurred throughout the nucleoplasm. Moreover, we show by double-labeling that inhibition of nucleolar transcription and redistribution of fibrillarin occur simultaneously, underlining that fibrillarin relocation is a consequence of the blockade of ribosomal RNA synthesis by mercury. We also detected redistribution of fibrillarin in vivo, e.g., in splenic cells of mice chronically exposed to HgCl(2). Thus, implications of this alteration of nuclear structure and function for mercury-induced autoimmunity are discussed.
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Affiliation(s)
- M Chen
- Junior Research Group of Molecular Cell Biology, Heinrich-Heine-University, Düsseldorf, Germany
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46
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Martelli AM, Robuffo I, Bortul R, Ochs RL, Luchetti F, Cocco L, Zweyer M, Bareggi R, Falcieri E. Behavior of nucleolar proteins during the course of apoptosis in camptothecin-treated HL60 cells. J Cell Biochem 2000. [DOI: 10.1002/(sici)1097-4644(20000801)78:2<264::aid-jcb9>3.0.co;2-3] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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47
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Likovský Z, Smetana K. Nucleolar coefficient of granulocyte precursors and granulocytes after visualization of nucleoli by two different methods. Acta Histochem 2000; 102:95-102. [PMID: 10726168 DOI: 10.1078/0065-1281-00541] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
To clarify differences in the incidence and number of nucleoli in the granulopoietic lineage, these nuclear components were studied in human and rabbit granulocyte precursors and granulocytes after visualization by 2 widely employed cytochemical procedures, i.e. a procedure for the demonstration of RNA and the silver reaction for the demonstration of nucleolar silver stainable proteins (SSPs). In early stages of the granulocyte proliferating compartment, substantial differences were not found between specimens in which nucleoli were visualized by both procedures. However, in contrast to specimens stained with the silver reaction, the number of cells without nucleoli was substantially larger in advanced stages of granulocyte development in specimens stained for RNA. The number of nucleoli per cell as expressed by the nucleolar coefficient was generally larger in specimens stained with the silver reaction for nucleolar SSPs. These differences were significant starting with the stage of myelocytes. Moreover, in specimens stained with the silver reaction, most of human mature granulocytes did not contain nucleoli but nucleoli were present in all mature granulocytes of rabbits. Such differences were not observed in specimens stained for RNA in which most granulocytes were without RNA-containing nucleoli. Thus, the evaluation of the presence or absence of nucleoli in specimens depended on the visualization procedure. It is likely that in micronucleoli which are characteristic for terminal differentiation of the granulocytic lineage, RNA-containing structures may be lost or are below the detection limit of the light microscope. In addition, differences in the presence of nucleoli exist apparently between human and rabbit granulocytes in specimens stained for SSPs but not in those stained for RNA.
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Affiliation(s)
- Z Likovský
- Institute of Experimental Medicine, Prague, Czech Republic
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48
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Smetana K, Jirásková I, Cermák J. Incidence of nucleoli in erythroblasts in patients suffering from refractory anemia of myelodysplastic syndrome. Eur J Haematol 1999; 63:332-6. [PMID: 10580565 DOI: 10.1111/j.1600-0609.1999.tb01136.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Nucleoli of erythroblasts have been studied in patients suffering from refractory anemia (RA) of myelodysplastic syndrome (MDS) and in control patients without a disturbed erythropoiesis in order to provide information on the incidence of nucleoli and micronucleoli in these cells. Nucleoli in erythroblasts were visualized by a simple cytochemical procedure for the demonstration of RNA which facilitated the visualization not only large nucleoli but also micronucleoli in advanced stages of the erythroblastic maturation. In control patients nucleoli were detected in all stages of erythroblastic development. In patients suffering from RA of MDS, a relatively large population of polychromatic and orthochromatic erythroblasts was characterized by a loss of nucleoli accompanied by the decreased incidence of micronucleoli characteristic of these cells. In contrast to control patients, in patients suffering from RA of MDS the number of nucleoli expressed by the values of the nucleolar coefficient of erythroblasts was smaller, particularly in both the early and terminal stages of erythroblastic development. Thus in patients with RA of MDS both the abnormal loss of nucleoli and decreased number of nucleoli in erythroblasts apparently represent and reflect a further abnormality of disturbed erythropoiesis.
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Affiliation(s)
- K Smetana
- Clinical Section, Institute of Hematology and Blood Transfusion, Prague, Czech Republic.
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49
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Bagenstose LM, Salgame P, Monestier M. Murine mercury-induced autoimmunity: a model of chemically related autoimmunity in humans. Immunol Res 1999; 20:67-78. [PMID: 10467984 DOI: 10.1007/bf02786508] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Human exposure to certain compounds or therapeutic drugs can result in the development of an autoimmune syndrome. Mercury (Hg) induced autoimmunity is one of the few animal models in which administration of a chemical induces a specific loss of tolerance to self-antigens. After receiving subtoxic doses of Hg or other heavy metals, susceptible mouse strains rapidly develop highly specific antibodies to nucleolar antigens. In addition, these animals display a general activation of the immune system, especially pronounced for the Th2 subset and a transient glomerulonephritis with immunoglobulin deposits. Like many human autoimmune diseases, this syndrome is associated with the expression of susceptible major histocompatibility complex (MHC) class II genes. In this article, we review the essential features of this model, and we discuss the putative mechanisms by which Hg creates such a severe immune dysfunction.
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Affiliation(s)
- L M Bagenstose
- Department of Microbiology and Immunology, Temple University School of Medicine, Philadelphia, PA 19140, USA
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50
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Smetana K, Jirásková I, Perlaky L, Busch H. The silver reaction of nucleolar proteins in the main structural compartments of ring-shaped nucleoli in smear preparations. Acta Histochem 1999; 101:167-83. [PMID: 10335360 DOI: 10.1016/s0065-1281(99)80016-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
The present study was undertaken to provide more information on the conditions which result in preferential silver staining of the main nucleolar structural compartments using silver stainable proteins as their markers at the light microscopic level. For this study the mostly used method in cytology and pathology in which the nucleolar silver-positive structures are "developed" with the colloidal developer (Howell and Black, 1980; Ploton et al., 1986) was selected as silver reaction. Ring-shaped nucleoli of mature human lymphocytes represent a convenient model for such a study because they consist of one large fibrillar center, adjacent nucleolar regions with dense fibrillar components and the nucleolar peripheral shell with dense granular components. All these nucleolar compartments are known to possess characteristic silver stainable proteins. The results demonstrated that proteins of the fibrillar center and possibly adjacent nucleolar regions reacted preferentially with silver after a relatively long fixation with formaldehyde or methanol in unwashed specimens before the silver reaction. In contrast, the preferential staining of proteins in the nucleolar peripheral shell with silver was achieved after the fixation with acidified methanol or ethanol as well as after short fixation with formaldehyde vapors. In addition, the commonly used fixation before the silver reaction are not necessary and may be omitted for the visualization of all silver stainable proteins present in the fibrillar center as well as in the adjacent nucleolar regions and the nucleolar peripheral shell. In addition, similar results were achieved for the simultaneous visualization of proteins in the fibrillar center and nucleolar peripheral shell after fixation with ethanol.
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Affiliation(s)
- K Smetana
- Clinical Department, Institute of Hematology and Blood Transfusion, Prague, Czech Republic
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