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Sundaram P, Rao K, Yajima M. Vasa, a regulator of localized mRNA translation on the spindle. Bioessays 2023; 45:e2300004. [PMID: 36825672 PMCID: PMC10023503 DOI: 10.1002/bies.202300004] [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] [Received: 01/08/2023] [Revised: 02/06/2023] [Accepted: 02/07/2023] [Indexed: 02/25/2023]
Abstract
Localized mRNA translation is a biological process that allows mRNA to be translated on-site, which is proposed to provide fine control in protein regulation, both spatially and temporally within a cell. We recently reported that Vasa, an RNA-helicase, is a promising factor that appears to regulate this process on the spindle during the embryonic development of the sea urchin, yet the detailed roles and functional mechanisms of Vasa in this process are still largely unknown. In this review article, to elucidate these remaining questions, we first summarize the prior knowledge and our recent findings in the area of Vasa research and further discuss how Vasa may function in localized mRNA translation, contributing to efficient protein regulation during rapid embryogenesis and cancer cell regulation.
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Affiliation(s)
- Paola Sundaram
- Department of Molecular Biology Cell Biology Biochemistry, Brown University, 185 Meeting Street, BOX-GL277, Providence, RI 02912, USA
| | - Kavya Rao
- Department of Molecular Biology Cell Biology Biochemistry, Brown University, 185 Meeting Street, BOX-GL277, Providence, RI 02912, USA
| | - Mamiko Yajima
- Department of Molecular Biology Cell Biology Biochemistry, Brown University, 185 Meeting Street, BOX-GL277, Providence, RI 02912, USA
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2
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Razin SV, Gavrilov AA. Non-coding RNAs in chromatin folding and nuclear organization. Cell Mol Life Sci 2021; 78:5489-5504. [PMID: 34117518 PMCID: PMC11072467 DOI: 10.1007/s00018-021-03876-w] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Revised: 04/24/2021] [Accepted: 06/05/2021] [Indexed: 12/19/2022]
Abstract
One of the most intriguing questions facing modern biology concerns how the genome directs the construction of cells, tissues, and whole organisms. It is tempting to suggest that the part of the genome that does not encode proteins contains architectural plans. We are still far from understanding how these plans work at the level of building tissues and the body as a whole. However, the results of recent studies demonstrate that at the cellular level, special non-coding RNAs serve as scaffolds for the construction of various intracellular structures. The term "architectural RNAs" was proposed to designate this subset of non-coding RNAs. In this review, we discuss the role of architectural RNAs in the construction of the cell nucleus and maintenance of the three-dimensional organization of the genome.
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Affiliation(s)
- Sergey V Razin
- Institute of Gene Biology, Russian Academy of Sciences, 119334, Moscow, Russia.
- Faculty of Biology, M. V. Lomonosov Moscow State University, 119234, Moscow, Russia.
| | - Alexey A Gavrilov
- Institute of Gene Biology, Russian Academy of Sciences, 119334, Moscow, Russia
- Center for Precision Genome Editing and Genetic Technologies for Biomedicine, Institute of Gene Biology, Russian Academy of Sciences, 119334, Moscow, Russia
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3
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Barutcu AR, Blencowe BJ, Rinn JL. Differential contribution of steady-state RNA and active transcription in chromatin organization. EMBO Rep 2019; 20:e48068. [PMID: 31448565 PMCID: PMC6776903 DOI: 10.15252/embr.201948068] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Revised: 08/05/2019] [Accepted: 08/06/2019] [Indexed: 12/29/2022] Open
Abstract
Nuclear RNA and the act of transcription have been implicated in nuclear organization. However, their global contribution to shaping fundamental features of higher-order chromatin organization such as topologically associated domains (TADs) and genomic compartments remains unclear. To investigate these questions, we perform genome-wide chromatin conformation capture (Hi-C) analysis in the presence and absence of RNase before and after crosslinking, or a transcriptional inhibitor. TAD boundaries are largely unaffected by RNase treatment, although a subtle disruption of compartmental interactions is observed. In contrast, transcriptional inhibition leads to weaker TAD boundary scores. Collectively, our findings demonstrate differences in the relative contribution of RNA and transcription to the formation of TAD boundaries detected by the widely used Hi-C methodology.
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Affiliation(s)
- A Rasim Barutcu
- Department of Stem Cell and Regenerative BiologyHarvard UniversityCambridgeMAUSA
- Donnelly CentreUniversity of TorontoTorontoONCanada
| | - Benjamin J Blencowe
- Donnelly CentreUniversity of TorontoTorontoONCanada
- Department of Molecular GeneticsUniversity of TorontoTorontoONCanada
| | - John L Rinn
- Department of Stem Cell and Regenerative BiologyHarvard UniversityCambridgeMAUSA
- Present address:
Department of BiochemistryBioFrontiersUniversity of ColoradoBoulderCOUSA
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4
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Booth DG, Earnshaw WC. Ki-67 and the Chromosome Periphery Compartment in Mitosis. Trends Cell Biol 2017; 27:906-916. [PMID: 28838621 DOI: 10.1016/j.tcb.2017.08.001] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2017] [Revised: 08/01/2017] [Accepted: 08/02/2017] [Indexed: 12/12/2022]
Abstract
The chromosome periphery is a complex network of proteins and RNA molecules (many derived from nucleoli) that covers the outer surface of chromosomes and whose function remains mysterious. Although it was first described over 130 years ago, technological advances and the recent discovery that Ki-67 acts as an organiser of this region have allowed the chromosome periphery to be dissected in previously unattainable detail, leading to a revival of interest in this obscure chromosomal compartment. Here, we review the most recent advances into the composition, structure and function of the chromosome periphery, discuss possible roles of Ki-67 during mitosis and consider why this structure is likely to remain the focus of ongoing attention in the future.
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Affiliation(s)
- Daniel G Booth
- Centre For Neuroregeneration, Chancellor's Building, University of Edinburgh, Edinburgh, EH16 4SB, UK.
| | - William C Earnshaw
- Wellcome Trust Centre for Cell Biology, King's Buildings, University of Edinburgh, Edinburgh, EH9 3BF, UK.
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5
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Mazur AJ, Radaszkiewicz T, Makowiecka A, Malicka-Błaszkiewicz M, Mannherz HG, Nowak D. Gelsolin interacts with LamR, hnRNP U, nestin, Arp3 and β-tubulin in human melanoma cells as revealed by immunoprecipitation and mass spectrometry. Eur J Cell Biol 2016; 95:26-41. [DOI: 10.1016/j.ejcb.2015.11.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2015] [Revised: 10/08/2015] [Accepted: 11/04/2015] [Indexed: 01/25/2023] Open
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6
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Dynamics of hnRNPs and omega speckles in normal and heat shocked live cell nuclei of Drosophila melanogaster. Chromosoma 2015; 124:367-83. [PMID: 25663367 DOI: 10.1007/s00412-015-0506-0] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2014] [Revised: 12/27/2014] [Accepted: 01/20/2015] [Indexed: 01/14/2023]
Abstract
The nucleus limited long-noncoding hsrω-n transcripts, hnRNPs, and some other RNA processing proteins organize nucleoplasmic omega speckles in Drosophila. Unlike other nuclear speckles, omega speckles rapidly disappear following cell stress, while hnRNPs and other associated proteins move away from chromosome sites, nucleoplasm, and the disappearing speckles to get uniquely sequestered at hsrω locus. Omega speckles reappear and hnRNPs get redistributed to normal locations during recovery from stress. With a view to understand the dynamics of omega speckles and their associated proteins, we used live imaging of GFP tagged hnRNPs (Hrb87F, Hrb98DE, or Squid) in unstressed and stressed Drosophila cells. Omega speckles display size-dependent mobility in nucleoplasmic domains with significant colocalization with nuclear matrix Tpr/Megator and SAFB proteins, which also accumulate at hsrω gene site after stress. Instead of moving towards the nuclear periphery located hsrω locus following heat shock or colchicine treatment, omega speckles rapidly disappear within nucleoplasm while chromosomal and nucleoplasmic hnRNPs move, stochastically or, more likely, by nuclear matrix-mediated transport to hsrω locus in non-particulate form. Continuing transcription of hsrω during cell stress is essential for sequestering incoming hnRNPs at the site. While recovering from stress, the sequestered hnRNPs are released as omega speckles in ISWI-dependent manner. Photobleaching studies reveal hnRNPs to freely move between nucleoplasm, omega speckles, chromosome regions, and hsrω gene site although their residence periods at chromosomes and hsrω locus are longer. A model for regulation of exchange of hnRNPs between nuclear compartments by hsrω-n transcripts is presented.
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7
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Tai PWL, Zaidi SK, Wu H, Grandy RA, Montecino MM, van Wijnen AJ, Lian JB, Stein GS, Stein JL. The dynamic architectural and epigenetic nuclear landscape: developing the genomic almanac of biology and disease. J Cell Physiol 2014; 229:711-27. [PMID: 24242872 PMCID: PMC3996806 DOI: 10.1002/jcp.24508] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2013] [Accepted: 11/11/2013] [Indexed: 12/31/2022]
Abstract
Compaction of the eukaryotic genome into the confined space of the cell nucleus must occur faithfully throughout each cell cycle to retain gene expression fidelity. For decades, experimental limitations to study the structural organization of the interphase nucleus restricted our understanding of its contributions towards gene regulation and disease. However, within the past few years, our capability to visualize chromosomes in vivo with sophisticated fluorescence microscopy, and to characterize chromosomal regulatory environments via massively parallel sequencing methodologies have drastically changed how we currently understand epigenetic gene control within the context of three-dimensional nuclear structure. The rapid rate at which information on nuclear structure is unfolding brings challenges to compare and contrast recent observations with historic findings. In this review, we discuss experimental breakthroughs that have influenced how we understand and explore the dynamic structure and function of the nucleus, and how we can incorporate historical perspectives with insights acquired from the ever-evolving advances in molecular biology and pathology.
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Affiliation(s)
- Phillip W. L. Tai
- Department of Biochemistry and Vermont Cancer Center, University of Vermont College of Medicine, Burlington, VT
| | - Sayyed K. Zaidi
- Department of Biochemistry and Vermont Cancer Center, University of Vermont College of Medicine, Burlington, VT
| | - Hai Wu
- Department of Biochemistry and Vermont Cancer Center, University of Vermont College of Medicine, Burlington, VT
| | - Rodrigo A. Grandy
- Department of Biochemistry and Vermont Cancer Center, University of Vermont College of Medicine, Burlington, VT
| | - Martin M. Montecino
- Center for Biomedical Research and FONDAP Center for Genome Regulation, Universidad Andres Bello, Santiago, Chile
| | - André J. van Wijnen
- Departments of Orthopedic Surgery and Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN
| | - Jane B. Lian
- Department of Biochemistry and Vermont Cancer Center, University of Vermont College of Medicine, Burlington, VT
| | - Gary S. Stein
- Department of Biochemistry and Vermont Cancer Center, University of Vermont College of Medicine, Burlington, VT
| | - Janet L. Stein
- Department of Biochemistry and Vermont Cancer Center, University of Vermont College of Medicine, Burlington, VT
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8
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Razin SV, Iarovaia OV, Vassetzky YS. A requiem to the nuclear matrix: from a controversial concept to 3D organization of the nucleus. Chromosoma 2014; 123:217-24. [PMID: 24664318 DOI: 10.1007/s00412-014-0459-8] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2014] [Revised: 03/10/2014] [Accepted: 03/14/2014] [Indexed: 12/13/2022]
Abstract
The first papers coining the term "nuclear matrix" were published 40 years ago. Here, we review the data obtained during the nuclear matrix studies and discuss the contribution of this controversial concept to our current understanding of nuclear architecture and three-dimensional organization of genome.
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Affiliation(s)
- S V Razin
- Institute of Gene Biology of the Russian Academy of Sciences, 119334, Moscow, Russia
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9
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The hnRNP A1 homolog Hrp36 is essential for normal development, female fecundity, omega speckle formation and stress tolerance in Drosophila melanogaster. J Biosci 2013; 37:659-78. [PMID: 22922191 DOI: 10.1007/s12038-012-9239-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
Hrp36/Hrb87F is one of the most abundant and well-characterized hnRNP A homolog in Drosophila and is shown to have roles in regulation of alternative splicing, heterochromatin formation, neurodegeneration, etc. Yet, hrp36 null individuals were reported to be viable and without any apparent phenotype, presumably because of overlapping functions provided by Hrp38 and related proteins. Here we show that loss of both copies of hrp36 gene slows down development with significant reduction in adult life span, decreased female fecundity and high sensitivity to starvation and thermal stresses. In the absence of Hrp36, the nucleoplasmic omega speckles are nearly completely disrupted. The levels of nuclear matrix protein Megator and the chromatin remodeller ISWI are significantly elevated in principal cells of larval Malpighian tubules, which also display additional endoreplication cycles and good polytene chromosomes. We suggest that besides the non-coding hsr omega-n transcripts, the Hrp36 protein is also a core constituent of omega speckles. The heat-shock-induced association of other hnRNPs at the hsr omega locus is affected in hrp36 null cells, which may be one of the reasons for their high sensitivity to cell stress. Therefore, in spite of the functional redundancy provided by Hrp38, Hrp36 is essential for normal development and for survival under conditions of stress.
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10
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Papadopoulou C, Ganou V, Patrinou-Georgoula M, Guialis A. HuR-hnRNP interactions and the effect of cellular stress. Mol Cell Biochem 2012; 372:137-47. [PMID: 22983828 DOI: 10.1007/s11010-012-1454-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2012] [Accepted: 09/05/2012] [Indexed: 12/11/2022]
Abstract
The heterogeneous nuclear ribonucleoproteins (hnRNPs) constitute an important group of RNA-binding proteins (RBPs) that play an active role in post-transcriptional gene regulation. Here, we focus on representative members of the hnRNP group of RBPs, namely hnRNP A1 and hnRNP C1/C2, which participate mainly in RNA splicing, as well as on HuR, a prototype of the AU-rich element-binding proteins (ARE-BP), which has an established role in regulating the stability and translation of target mRNAs. HuR and most hnRNPs are primarily localized in the nucleoplasm, and they can shuttle between the nucleus and the cytoplasm. Herein, we have extended our recently reported findings on the ability of HuR to associate with the immunopurified from mammalian cell extracts hnRNP and mRNP complexes by the application of an anti-HuR antibody that selects HuR-RNP complexes. We find that the protein components precipitated by the anti-HuR antibody are very similar to the hnRNP-HuR complexes reported previously. The in vivo association of HuR and hnRNP proteins is examined in the presence and the absence of thermal stress by confocal microscopy of intact cells and by in situ nuclear matrix preparation. We find notable heat-induced changes of HuR and of hnRNP A1, which exit the nucleus and co-localize to large cytoplasmic foci that represent heat-induced stress granules. The functional implications of HuR-hnRNP interactions in stressed and unstressed cells are discussed.
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Affiliation(s)
- Christina Papadopoulou
- RNA Processing Program, Institute of Biological Research and Biotechnology, National Hellenic Research Foundation, 48 Vas. Constantinou Avenue, 11635 Athens, Greece
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11
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Kallappagoudar S, Varma P, Pathak RU, Senthilkumar R, Mishra RK. Nuclear matrix proteome analysis of Drosophila melanogaster. Mol Cell Proteomics 2010; 9:2005-18. [PMID: 20530634 DOI: 10.1074/mcp.m110.001362] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The nucleus is a highly structured organelle and contains many functional compartments. Although the structural basis for this complex spatial organization of compartments is unknown, a major component of this organization is likely to be the non-chromatin scaffolding called nuclear matrix (NuMat). Experimental evidence over the past decades indicates that most of the nuclear functions are at least transiently associated with the NuMat, although the components of NuMat itself are poorly known. Here, we report NuMat proteome analysis from Drosophila melanogaster embryos and discuss its links with nuclear architecture and functions. In the NuMat proteome, we found structural proteins, chaperones, DNA/RNA-binding proteins, chromatin remodeling and transcription factors. This complexity of NuMat proteome is an indicator of its structural and functional significance. Comparison of the two-dimensional profile of NuMat proteome from different developmental stages of Drosophila embryos showed that less than half of the NuMat proteome is constant, and the rest of the proteins are stage-specific dynamic components. These NuMat dynamics suggest a possible functional link between NuMat and embryonic development. Finally, we also showed that a subset of NuMat proteins remains associated with the mitotic chromosomes, implicating their role in mitosis and possibly the epigenetic cellular memory. NuMat proteome analysis provides tools and opens up ways to understand nuclear organization and function.
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Affiliation(s)
- Satish Kallappagoudar
- Centre for Cellular and Molecular Biology, Council of Scientific and Industrial Research, Hyderabad, India
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12
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Papadopoulou C, Patrinou-Georgoula M, Guialis A. Extensive association of HuR with hnRNP proteins within immunoselected hnRNP and mRNP complexes. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2010; 1804:692-703. [DOI: 10.1016/j.bbapap.2009.11.007] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2009] [Revised: 10/08/2009] [Accepted: 11/09/2009] [Indexed: 10/20/2022]
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13
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Marko M, Leichter M, Patrinou-Georgoula M, Guialis A. hnRNP M interacts with PSF and p54nrb and co-localizes within defined nuclear structures. Exp Cell Res 2010; 316:390-400. [DOI: 10.1016/j.yexcr.2009.10.021] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2009] [Revised: 09/21/2009] [Accepted: 10/21/2009] [Indexed: 01/28/2023]
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14
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Shen Q, Zheng X, McNutt MA, Guang L, Sun Y, Wang J, Gong Y, Hou L, Zhang B. NAT10, a nucleolar protein, localizes to the midbody and regulates cytokinesis and acetylation of microtubules. Exp Cell Res 2009; 315:1653-67. [PMID: 19303003 DOI: 10.1016/j.yexcr.2009.03.007] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2008] [Revised: 03/03/2009] [Accepted: 03/05/2009] [Indexed: 01/02/2023]
Abstract
The midbody is a structural organelle formed in late phase mitosis which is responsible for completion of cytokinesis. Although various kinds of proteins have been found to distribute or immigrate to this organelle, their functions have still not been completely worked out. In this study, we demonstrated that NAT10 (N-acetyltransferase 10, NAT10) is not only predominantly distributed in the nucleolus in interphase, but is also concentrated in the mitotic midbody during telophase. The domain in N-terminal residues 549-834 of NAT10 specifically mediated its subcellular localization. Treatment with genotoxic agents or irradiation increased concentration of NAT10 in both the nucleolus and midbody. Moreover, DNA damage induced increase of NAT10 in the midbody apparently accompanied by in situ elevation of the level of acetylated alpha-tubulin, suggesting that it plays a role in maintaining or enhancing stability of alpha-tubulin. The depletion of NAT10 induced defects in nucleolar assembly, cytokinesis and decreased acetylated alpha-tubulin, leading to G2/M cell cycle arrest or delay of mitotic exit. In addition, over-expression of NAT10 was found in a variety of soft tissue sarcomas, and correlated with tumor histological grading. These results indicate that NAT10 may play an important role in cell division through facilitating reformation of the nucleolus and midbody in the late phase of cell mitosis, and stabilization of microtubules.
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Affiliation(s)
- Qi Shen
- Department of Pathology, Health Science Center of Peking University, Haidian District, Beijing, China
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15
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Denisenko O, Bomsztyk K. Epistatic interaction between the K-homology domain protein HEK2 and SIR1 at HMR and telomeres in yeast. J Mol Biol 2007; 375:1178-87. [PMID: 18067921 DOI: 10.1016/j.jmb.2007.11.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2007] [Revised: 10/30/2007] [Accepted: 11/01/2007] [Indexed: 10/22/2022]
Abstract
In budding yeast, telomeres, the ribosomal DNA array, and HM loci are transcriptionally silenced by chromatin complexes containing Sir proteins. Hek2, a protein containing three evolutionary conserved RNA-binding K-homology domains, was identified as a suppressor of telomeric silencing [telomeric position effect (TPE)]. To explore the mechanisms of Hek2p action in gene silencing, we examined its relationship with Sir proteins. This search revealed an epistatic interaction between HEK2 and SIR1 at telomeres. Both single mutations, sir1Delta and hek2Delta, enhanced TPE, whereas the effect of double mutation, sir1Delta hek2Delta, did not exceed that of the single mutations. The results of chromatin immunoprecipitation analysis demonstrate that the TPE enhancement observed in these mutants is associated with increased binding of Sir2 protein to telomeres. At the HMR locus, hek2Delta rescues the silencing defect caused by sir1Delta mutation and reverses the loss of Sir2p and Sir3p. These data suggest that the epistatic interaction of HEK2 and SIR1 reflects competition between telomeres and HMR for Sir2/3 factors where HEK2 acts to suppress silencing. Because chromatin immunoprecipitation analysis reveals the presence of Hek2p at a subtelomeric region and HMR, its silencing effects at these loci are likely direct. These observations suggest that HEK2 regulates the composition of Sir complexes at HMR and telomeres.
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Affiliation(s)
- Oleg Denisenko
- Department of Medicine, Room 242, University of Washington, 815 Mercer Street, Seattle, WA 98109, USA.
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16
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Foster HA, Bridger JM. The genome and the nucleus: a marriage made by evolution. Genome organisation and nuclear architecture. Chromosoma 2005; 114:212-29. [PMID: 16133352 DOI: 10.1007/s00412-005-0016-6] [Citation(s) in RCA: 109] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2005] [Revised: 06/29/2005] [Accepted: 07/04/2005] [Indexed: 01/15/2023]
Abstract
Genomes are housed within cell nuclei as individual chromosome territories. Nuclei contain several architectural structures that interact and influence the genome. In this review, we discuss how the genome may be organised within its nuclear environment with the position of chromosomes inside nuclei being either influenced by gene density or by chromosomes size. We compare interphase genome organisation in diverse species and reveal similarities and differences between evolutionary divergent organisms. Genome organisation is also discussed with relevance to regulation of gene expression, development and differentiation and asks whether large movements of whole chromosomes are really observed during differentiation. Literature and data describing alterations to genome organisation in disease are also discussed. Further, the nuclear structures that are involved in genome function are described, with reference to what happens to the genome when these structures contain protein from mutant genes as in the laminopathies.
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Affiliation(s)
- Helen A Foster
- Laboratory of Nuclear and Genomic Health, Cell and Chromosome Biology Group, Division of Biosciences, School of Health Sciences and Social Care, Brunel University, Uxbridge UB8 3PH, UK
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17
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Gao S, Scott RE. P2P-R protein overexpression restricts mitotic progression at prometaphase and promotes mitotic apoptosis. J Cell Physiol 2002; 193:199-207. [PMID: 12384997 DOI: 10.1002/jcp.10163] [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: 11/11/2022]
Abstract
Mitotic cells show a tenfold increase in immunoreactive P2P-R protein. During mitosis, the distribution of P2P-R protein also changes from a primary nucleolar localization in interphase cells to the periphery of chromosome in mitotic cells. These findings suggest that P2P-R might serve a functional role in mitosis. To test this possibility, human Saos2 cells were stably transfected with P2P-R DNA constructs and the biological effects of P2P-R overexpression were evaluated. Overexpression of near full-length P2P-R was found to have paradoxical effects on the relationship between proliferation and mitosis in the nine Saos2 cell clones that were studied. A significant repression in the population doubling rates was observed in all nine clones even though a significant increase in the frequency of easily detached cells with a mitotic morphology was apparent. Flow cytometric analysis confirmed that greater than two thirds of the cells with a mitotic morphology had a 4n DNA content. Confocal microscopy further established that 85% of the mitotic cell population had prometaphase characteristics suggesting that P2P-R overexpression restricts mitotic progression at prometaphase. Many cells with a mitotic morphology also showed signs of apoptosis with prominent cell surface blebs. Confocal microscopy confirmed that 25-40% of such mitotic cells were apoptotic with chromosomal abnormalities and cell surface blebbing. In association with mitotic apoptosis, P2P-R protein appears to dissociate from the periphery of chromosomes and localize in the cytoplasm and in cell surface blebs. The presence of P2P-R in cell surface blebs was confirmed by analysis of highly enriched populations of apoptotic cell surface blebs wherein Western blotting documented the presence of 250 kDa P2P-R. These results therefore suggest that P2P-R overexpression promotes both prometaphase arrest in mitosis and mitotic apoptosis.
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Affiliation(s)
- Sizhi Gao
- Department of Pathology, University of Tennessee Health Science Center, Memphis TN 38163, Tennessee, USA
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18
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Gao S, Witte MM, Scott RE. P2P-R protein localizes to the nucleolus of interphase cells and the periphery of chromosomes in mitotic cells which show maximum P2P-R immunoreactivity. J Cell Physiol 2002; 191:145-54. [PMID: 12064457 DOI: 10.1002/jcp.10084] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
P2P-R is a nuclear protein that can bind both p53 and Rb1. Its functions include roles in the control of RNA metabolism, apoptosis, and p53-dependent transcription. The expression of P2P-R also is repressed in G1 arrested terminally differentiated cells. The current studies therefore evaluated if P2P-R undergoes cell cycle-associated changes in its abundance and/or localization. Western blots show that relative to G0 quiescent cells, P2P-R protein levels are higher in populations of G2/M cells prepared by the physiological parasynchronization technique of serum deprivation followed by serum stimulation. More striking is the > 10-fold enrichment of P2P-R protein in specimens of highly purified mitotic cells prepared by the mitotic shake-select technique, or by synchrony with the mitotic spindle disruption agents nocodazole or vinblastine. These changes in P2P-R protein occur without a concomitant change in P2P-R mRNA expression suggesting that P2P-R immunoreactivity increases during mitosis. Confocal microscopy next established the localization of P2P-R to nucleoli in interphase cells and at the periphery of chromosomes in mitotic cells that lack nucleoli. The high levels of P2P-R localized to the periphery of chromosomes in mitotic cells suggest that P2P-R shares characteristics with other nucleolar proteins that associate with the periphery of chromosomes during mitosis. These include: nucleolin, B23, Ki67, and fibrillarin.
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Affiliation(s)
- Sizhi Gao
- Department of Pathology, University of Tennessee Health Science Center, Memphis 38163, USA
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19
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Yamaguchi A, Nagahama Y. Somatic lamins in germinal vesicles of goldfish (Carassius auratus) vitellogenic oocytes. Cell Struct Funct 2001; 26:693-703. [PMID: 11942628 DOI: 10.1247/csf.26.693] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
In fish and amphibians, B-type lamins are divided into somatic (B1, B2) and oocyte-type (B3) lamins. In this study, we purified nuclear lamins from rainbow trout erythrocytes, raised an anti-lamin monoclonal antibody (L-200) that recognizes goldfish somatic-lamins, and isolated cDNAs encoding goldfish B-type lamins (B1 and B2) from a goldfish cell culture cDNA library. Goldfish B-type lamins are structurally similar to lamins found in other vertebrates with minor amino acid substitutions in the conserved region. Western blot analysis showed that goldfish oocytes contained mainly GV-lamin B3 as well as some somatic lamins. Laser-confocal microscope observations revealed that lamin B3 was present only in GV nuclear lamina, whereas somatic lamins were present in dense fibrillar structures throughout nuclear gels of isolated GVs. Similar nuclear filamentous structures were also observed in GVs of paraffin embedded oocytes. Epitope mapping indicated that L-200 recognized a conserved region containing a short stretch of the alpha-helix coiled-coil rod domain (Y(E/Q)(Q/E)LL). A similar motif is also present in other cytoplasmic intermediate filaments (i.e., vimentin, desmin, peripherin and GFAP). Taken together, these findings suggest that lamins or lamin-related intermediate filaments are an important component of the interior architecture of goldfish vitellogenic oocyte nuclei (GVs).
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Affiliation(s)
- A Yamaguchi
- Department of Developmental Biology, National Institute for Basic Biology, Okazaki, Japan
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20
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Abstract
Nuclei are intricately structured, and nuclear metabolism has an elaborate spatial organization. The architecture of the nucleus includes two overlapping and nucleic-acid-containing structures - chromatin and a nuclear matrix. The nuclear matrix is observed by microscopy in live, fixed and extracted cells. Its ultrastructure and composition show it to be, in large part, the ribonucleoprotein (RNP) network first seen in unfractionated cells more than 30 years ago. At that time, the discovery of this RNP structure explained surprising observations that RNA, packaged in proteins, is attached to an intranuclear, non-chromatin structure. Periodic and specific attachments of chromatin fibers to the nuclear matrix create the chromatin loop domains that can be directly observed by microscopy or inferred from biochemical experiments. The ultrastructure of the nuclear matrix is well characterized and consists of a nuclear lamina and an internal nuclear network of subassemblies linked together by highly structured fibers. These complex fibers are built on an underlying scaffolding of branched 10-nm filaments that connect to the nuclear lamina. The structural proteins of the nuclear lamina have been well characterized, but the structural biochemistry of the internal nuclear matrix has received less attention. Many internal matrix proteins have been identified, but far less is known about how these proteins assemble to make the fibers, filaments and other assemblies of the internal nuclear matrix. Correcting this imbalance will require the combined application of biochemistry and electron microscopy. The central problem in trying to define nuclear matrix structure is to identify the proteins that assemble into the 10-nm filaments upon which the interior architecture of the nucleus is constructed. Only by achieving a biochemical characterization of the nuclear matrix will we advance beyond simple microscopic observations of structure to a better understanding of nuclear matrix function, regulation and post-mitotic assembly.
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Affiliation(s)
- J Nickerson
- Department of Cell Biology and Cancer Center, University of Massachusetts Medical School, Worcester, MA 01655, USA.
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21
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Abstract
Nuclear mitotic apparatus protein, NuMA, is an abundant 240 kDa protein with microtubule (MT) binding capacity via its carboxyl terminal region. Structurally, it has been shown to be a double-strand coiled-coil that has a high potential to form filamentous polymers. During interphase, NuMA locates within the nucleus but rapidly redistributes to the separating centrosomes during early mitosis. Xenopus NuMA associates with MT minus end-directed motor cytoplasmic dynein and its motility-activating complex dynactin at mitotic centrosomal regions. This NuMA-motor complex binds the free ends of MTs, converging and tethering spindle MT ends to the poles. A similar scenario appears to be true in higher vertebrates as well. As a mitotic centrosomal component, NuMA is essential for the organization and stabilization of spindle poles from early mitosis until at least the onset of anaphase. The cell cycle-dependent distribution and function of NuMA is regulated by phosphorylation and dephosphorylation, and p34/CDC2 activity is important to the mitotic role of NuMA. This review summarizes data about the structural features and mitotic function of NuMA with particular emphasis on the newly discovered NuMA-motor complex in spindle organization. Furthermore, NuMA may represent a large group of proteins whose mitotic function is sequestered in the nucleus during interphase.
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Affiliation(s)
- C Zeng
- Verna and Marrs McLean Department of Biochemistry, Baylor College of Medicine, Houston, TX 77030, USA.
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22
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Tan JH, Wooley JC, LeStourgeon WM. Nuclear matrix-like filaments and fibrogranular complexes form through the rearrangement of specific nuclear ribonucleoproteins. Mol Biol Cell 2000; 11:1547-54. [PMID: 10793134 PMCID: PMC14866 DOI: 10.1091/mbc.11.5.1547] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
The behavior of nuclear pre-mRNA-binding proteins after their nuclease and/or salt-induced release from RNA was investigated. After RNase digestion or salt extraction, two proteins that initially exist as tetramers (A2)(3)B1 in isolated heterogeneous nuclear ribonucleoprotein (hnRNP) complexes quantitatively reassociated to form regular helical filaments ranging in length from 100 nm to >10 microm. In highly magnified preparations prepared for scanning transmission electron microscopy, single filaments have diameters near 18 nm. In conventional negatively stained preparations viewed at low magnification, the diameters of the thinnest filaments range from 7 to 10 nm. At protein concentrations of >0.1 mg/ml, the filaments rapidly aggregated to form thicker filamentous networks that look like the fibrogranular structures termed the "nuclear matrix." Like the residual material seen in nuclear matrix preparations, the hnRNP filaments were insoluble in 2 M NaCl. Filament formation is associated with, and may be dependent on, disulfide bridge formation between the hnRNP proteins. The reducing agent 2-mercaptoethanol significantly attenuates filament assembly, and the residual material that forms is ultrastructurally distinct from the 7- to 10-nm fibers. In addition to the protein rearrangement leading to filament formation, nearly one-third of the protein present in chromatin-clarified nuclear extracts was converted to salt-insoluble material within 1 min of digestion with RNase. These observations are consistent with the possibility that the residual material termed the nuclear matrix may be enriched in, if not formed by, denatured proteins that function in pre-mRNA packaging, processing, and transport.
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Affiliation(s)
- J H Tan
- Department of Molecular Biology, Vanderbilt University, Nashville, Tennessee 37235, USA
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23
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MacCallum DE, Hall PA. Biochemical characterization of pKi67 with the identification of a mitotic-specific form associated with hyperphosphorylation and altered DNA binding. Exp Cell Res 1999; 252:186-98. [PMID: 10502411 DOI: 10.1006/excr.1999.4600] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Although widely used as an operational marker of proliferation, the cell cycle-regulated Ki67 protein is of unknown function. pKi67 is found predominantly in the nucleolus in cycling interphase cells and moves to become perichromosomal during mitosis. We have performed a detailed immunochemical analysis of pKi67 in HeLa cells and report the existence of a novel hyperphosphorylated form in mitosis. Two isoforms can be identified on immunoblots as a consequence of the previously described alternative splicing. In extracts from mitotic cells both these isoforms have considerably reduced mobility. Treatment with phosphatase converts the mitotic form to the interphase form. Immunoprecipitated pKi67 can be phosphorylated in vitro both by cdc2/cyclin B and by protein kinase C, and treatment by PKC leads to the full mobility shift. Treatment of nocodazole-arrested mitotic HeLa cells with staurosporine causes a dephosphorylation of pKi67 to the interphase state and a concomitant change in the localization of pKi67 with movement away from the perichromosomal layer to cytoplasmic dots that colocalize with nucleolin. These data indicate that pKi67 localization is regulated by the action of cell cycle-specific kinase(s) and phosphatase(s). The data presented here provide a starting point for the analysis of pKi67 function and regulation.
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Affiliation(s)
- D E MacCallum
- Ninewells Hospital and Medical School, University of Dundee, Dundee, DD1 9SY, United Kingdom
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24
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Ma H, Siegel AJ, Berezney R. Association of chromosome territories with the nuclear matrix. Disruption of human chromosome territories correlates with the release of a subset of nuclear matrix proteins. J Cell Biol 1999; 146:531-42. [PMID: 10444063 PMCID: PMC2150557 DOI: 10.1083/jcb.146.3.531] [Citation(s) in RCA: 124] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/1998] [Accepted: 07/02/1999] [Indexed: 11/27/2022] Open
Abstract
To study the possible role of the nuclear matrix in chromosome territory organization, normal human fibroblast cells are treated in situ via classic isolation procedures for nuclear matrix in the absence of nuclease (e.g., DNase I) digestion, followed by chromosome painting. We report for the first time that chromosome territories are maintained intact on the nuclear matrix. In contrast, complete extraction of the internal nuclear matrix components with RNase treatment followed by 2 M NaCl results in the disruption of higher order chromosome territory architecture. Correlative with territorial disruption is the formation of a faint DNA halo surrounding the nuclear lamina and a dispersive effect on the characteristically discrete DNA replication sites in the nuclear interior. Identical results were obtained using eight different human chromosome paints. Based on these findings, we developed a fractionation strategy to release the bulk of nuclear matrix proteins under conditions where the chromosome territories are maintained intact. A second treatment results in disruption of the chromosome territories in conjunction with the release of a small subset of acidic proteins. These proteins are distinct from the major nuclear matrix proteins and may be involved in mediating chromosome territory organization.
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Affiliation(s)
- Hong Ma
- Department of Biological Sciences, State University of New York at Buffalo, Buffalo, New York 14260
| | - Alan J. Siegel
- Department of Biological Sciences, State University of New York at Buffalo, Buffalo, New York 14260
| | - Ronald Berezney
- Department of Biological Sciences, State University of New York at Buffalo, Buffalo, New York 14260
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25
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Zatsepina OV, Rousselet A, Chan PK, Olson MO, Jordan EG, Bornens M. The nucleolar phosphoprotein B23 redistributes in part to the spindle poles during mitosis. J Cell Sci 1999; 112 ( Pt 4):455-66. [PMID: 9914158 DOI: 10.1242/jcs.112.4.455] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
B23 is a major phosphoprotein in the interphasic nucleolus where it is involved in the assembly of pre-ribosomes. Using several cultured animal cells, we report that, in addition to the known redistribution of the protein during mitosis, B23 also becomes associated with mitotic spindle poles starting from early prometaphase onwards. Colocalization of B23 with the protein NuMA (Nuclear Mitotic Apparatus protein) was studied in mitotic cells and taxol-arrested cells. During the onset of mitosis, we observed that a fraction of B23 associates with, and dissociates from, the poles later than NuMA. At metaphase, both proteins are colocalized at the poles. The polar redistribution of both B23 and NuMA is mediated by microtubules. In taxol-treated cells, B23 is associated with the microtubule minus ends in the center of mitotic asters together with NuMA. Association of B23 with microtubule minus ends of mitotic asters was further confirmed with an in vitro assay, where B23 was found by western blotting to co-sediment with taxol-induced microtubule asters formed in a mitotic cell extract. Immunolabeling demonstrated that B23 and NuMA were both present at the center of the asters. Furthermore, an additional hyperphosphorylated form of B23 appeared when microtubule asters formed and associated with the asters. Immunodepletion of B23 from the mitotic extract revealed that taxol-induced microtubule asters were still observed in B23-immunodepleted mitotic extract, indicating that the presence of B23 at the poles is unlikely to be essential for spindle formation or stabilisation.
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Affiliation(s)
- O V Zatsepina
- Randall Institute, King's College London, London WC2B 5RL, UK.
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26
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Patturajan M, Wei X, Berezney R, Corden JL. A nuclear matrix protein interacts with the phosphorylated C-terminal domain of RNA polymerase II. Mol Cell Biol 1998; 18:2406-15. [PMID: 9528809 PMCID: PMC121500 DOI: 10.1128/mcb.18.4.2406] [Citation(s) in RCA: 84] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/1997] [Accepted: 01/23/1998] [Indexed: 02/07/2023] Open
Abstract
Yeast two-hybrid screening has led to the identification of a family of proteins that interact with the repetitive C-terminal repeat domain (CTD) of RNA polymerase II (A. Yuryev et al., Proc. Natl. Acad. Sci. USA 93:6975-6980, 1996). In addition to serine/arginine-rich SR motifs, the SCAFs (SR-like CTD-associated factors) contain discrete CTD-interacting domains. In this paper, we show that the CTD-interacting domain of SCAF8 specifically binds CTD molecules phosphorylated on serines 2 and 5 of the consensus sequence Tyr1Ser2Pro3Thr4Ser5Pro6Ser7. In addition, we demonstrate that SCAF8 associates with hyperphosphorylated but not with hypophosphorylated RNA polymerase II in vitro and in vivo. This result suggests that SCAF8 is not present in preinitiation complexes but rather associates with elongating RNA polymerase II. Immunolocalization studies show that SCAF8 is present in granular nuclear foci which correspond to sites of active transcription. We also provide evidence that SCAF8 foci are associated with the nuclear matrix. A fraction of these sites overlap with a subset of larger nuclear speckles containing phosphorylated polymerase II. Taken together, our results indicate a possible role for SCAF8 in linking transcription and pre-mRNA processing.
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Affiliation(s)
- M Patturajan
- Department of Molecular Biology and Genetics, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205-2185, USA
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27
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Lampel S, Bridger JM, Zirbel RM, Mathieu UR, Lichter P. Nuclear RNA accumulations contain released transcripts and exhibit specific distributions with respect to Sm antigen foci. DNA Cell Biol 1997; 16:1133-42. [PMID: 9364924 DOI: 10.1089/dna.1997.16.1133] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
RNA polymerase II transcripts accumulate within mammalian nuclei at distinct sites and exhibit varying morphology. Certain RNA species are organized in elongated structures, whereas others appear as dot-like concentrations. To analyze the status of the RNA within these accumulations, we investigated the composition of accumulations derived from Epstein-Barr virus (EBV) genes, human papilloma virus 18 (HPV18) open reading frames E6 and E7, as well as heat shock protein 89a (hsp89alpha) and 89beta (hsp89beta) genes. No differential distribution of exon and intron sequences within concentrations of EBV RNA could be observed. Whereas accumulations of hsp89alpha and hsp89beta always coincided with Sm antigen foci, the RNA of EBV and HPV18 never co-localized with these foci. This excludes Sm antigen foci as the only sites of splicing and suggests gene-specific variation in the nuclear localization of transcripts. Two sets of experiments were performed to assess whether transcripts in the RNA accumulations are in statu nascendi or products released from a discrete gene locus. Because RNA transcripts derived from EBV genes, which are located on both ends of the genome, were all distributed along the entire length of the RNA signals, they cannot be derived from a highly decondensed genomic DNA extending throughout elongated RNA accumulations. Furthermore, removal of labeled RNA sequences and subsequent visualization of DNA confirmed the confinement of the genomic sequences to a small subregion of the area occupied by accumulated RNA. Therefore, this study supports the view of RNA accumulations as a stream of molecules that delineate a path from a dot-like gene locus toward the nuclear envelope for export into the cytoplasm.
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MESH Headings
- Autoantigens/analysis
- Burkitt Lymphoma
- Cell Fractionation
- Cell Nucleus/chemistry
- Cytoplasm/chemistry
- DNA, Viral/analysis
- DNA-Binding Proteins
- Exons/genetics
- Genes, Viral/genetics
- HeLa Cells
- Heat-Shock Proteins/genetics
- Herpesvirus 4, Human/genetics
- Humans
- Introns/genetics
- Nuclear Envelope/chemistry
- Oncogene Proteins, Viral/genetics
- Papillomaviridae/genetics
- RNA Precursors/analysis
- RNA Splicing
- RNA, Messenger/analysis
- RNA, Nuclear/analysis
- RNA, Viral/analysis
- Ribonucleoproteins, Small Nuclear
- Transcription, Genetic
- Tumor Cells, Cultured
- snRNP Core Proteins
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Affiliation(s)
- S Lampel
- Abteilung Organisation komplexer Genome, Deutsches Krebsforschungszentrum, Heidelberg, Germany
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28
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Valkov NI, Gump JL, Sullivan DM. Quantitative immunofluorescence and immunoelectron microscopy of the topoisomerase II alpha associated with nuclear matrices from wild-type and drug-resistant chinese hamster ovary cell lines. J Cell Biochem 1997; 67:112-30. [PMID: 9328845 DOI: 10.1002/(sici)1097-4644(19971001)67:1<112::aid-jcb12>3.0.co;2-j] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Topo II alpha is considered an important constituent of the nuclear matrix, serving as a fastener of DNA loops to the underlying filamentous scaffolding network. To further define a mechanism of drug resistance to topo II poisons, we studied the quantity of topo II alpha associated with the nuclear matrix in drug-resistant SMR16 and parental cells in the presence and absence of VP-16. Nuclear matrices were prepared from nuclei isolated in EDTA buffer, followed by nuclease digestion with DNase II in the absence of RNase treatment and extraction with 2 M NaCl. Whole-mount spreading of residual structures permits, by means of isoform-specific antibody and colloidal-gold secondary antibodies, an estimate of the amount of topo II alpha in individual nuclear matrices. There are significant variations in topo II alpha amounts between individual nuclear matrices due to the cell cycle distribution. The parental cell line contained eight to ten times more nuclear matrix-associated topo II alpha than the resistant cell line matrices. Nuclear matrix-associated topo II alpha from wild-type and resistant cell lines correlated well with the immunofluorescent staining of the enzyme in nuclei of intact cells. The amount of DNA associated with residual nuclear structures was five times greater in the resistant cell line. This quantity of DNA was not proportional to the quantity of topo II alpha in the same matrix; in fact they were inversely related. In situ whole-mount nuclear matrix preparations were obtained from cells grown on grids and confirmed the results from labeling of isolated residual structures.
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Affiliation(s)
- N I Valkov
- H. Lee Moffitt Cancer Center & Research Institute, Department of Internal Medicine and Biochemistry, University of South Florida, Tampa 33612, USA
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29
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Krauss SW, Larabell CA, Lockett S, Gascard P, Penman S, Mohandas N, Chasis JA. Structural protein 4.1 in the nucleus of human cells: dynamic rearrangements during cell division. J Cell Biol 1997; 137:275-89. [PMID: 9128242 PMCID: PMC2139783 DOI: 10.1083/jcb.137.2.275] [Citation(s) in RCA: 95] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/1996] [Revised: 01/20/1997] [Indexed: 02/04/2023] Open
Abstract
Structural protein 4.1, first identified as a crucial 80-kD protein in the mature red cell membrane skeleton, is now known to be a diverse family of protein isoforms generated by complex alternative mRNA splicing, variable usage of translation initiation sites, and posttranslational modification. Protein 4.1 epitopes are detected at multiple intracellular sites in nucleated mammalian cells. We report here investigations of protein 4.1 in the nucleus. Reconstructions of optical sections of human diploid fibroblast nuclei using antibodies specific for 80-kD red cell 4.1 and for 4.1 peptides showed 4.1 immunofluorescent signals were intranuclear and distributed throughout the volume of the nucleus. After sequential extractions of cells in situ, 4.1 epitopes were detected in nuclear matrix both by immunofluorescence light microscopy and resinless section immunoelectron microscopy. Western blot analysis of fibroblast nuclear matrix protein fractions, isolated under identical extraction conditions as those for microscopy, revealed several polypeptide bands reactive to multiple 4.1 antibodies against different domains. Epitope-tagged protein 4.1 was detected in fibroblast nuclei after transient transfections using a construct encoding red cell 80-kD 4.1 fused to an epitope tag. Endogenous protein 4.1 epitopes were detected throughout the cell cycle but underwent dynamic spatial rearrangements during cell division. Protein 4.1 was observed in nucleoplasm and centrosomes at interphase, in the mitotic spindle during mitosis, in perichromatin during telophase, as well as in the midbody during cytokinesis. These results suggest that multiple protein 4.1 isoforms may contribute significantly to nuclear architecture and ultimately to nuclear function.
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Affiliation(s)
- S W Krauss
- Life Sciences Division, University of California, Lawrence Berkeley National Laboratory, 94720, USA
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30
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Witte MM, Scott RE. The proliferation potential protein-related (P2P-R) gene with domains encoding heterogeneous nuclear ribonucleoprotein association and Rb1 binding shows repressed expression during terminal differentiation. Proc Natl Acad Sci U S A 1997; 94:1212-7. [PMID: 9037032 PMCID: PMC19770 DOI: 10.1073/pnas.94.4.1212] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Terminal differentiation is associated with repression in the expression of the proliferation potential proteins (P2P) subset of heterogeneous nuclear ribonucleoprotein (hnRNP) proteins. We report here the cloning and characterization of a 5173-bp P2P-related (P2P-R) cDNA that contains a 4214-bp open reading frame. Probes to this cDNA detect a single 8-kb mRNA in multiple murine tissues and in proliferating 3T3T cells, but not in terminally differentiated 3T3T adipocytes. Evidence that this cDNA can encode peptides with domains for hnRNP association was established by showing that such peptides are recognized by two monoclonal antibodies known to detect core hnRNP proteins, and by showing that the C130 monoclonal antibody, produced against a cDNA-derived fusion protein, also selectively detects native P2P hnRNP proteins. In addition, P2P-R cDNA-derived fusion proteins bind single-stranded nucleic acids, and a P2P-R cDNA-derived antisense oligonucleotide selectively represses P2P expression. Because terminal differentiation is associated with modulation in Rb1 function, we assayed if products of this cDNA might interact with Rb1. Evidence that the P2P-R cDNA encodes a protein domain that binds Rb1 was established using a glutathione S-transferase fusion protein to selectively precipitate Rb1 from cellular extracts. Data also show that this binding is reduced by competition with the adenovirus E1a protein, indicating that binding occurs through the "pocket" domain of Rb1. These results establish that the P2P-R cDNA encodes protein domains involved in both hnRNP association and Rb1 binding and complement recent reports that localize Rb1 to sites of RNA processing in the nucleus.
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Affiliation(s)
- M M Witte
- Department of Pathology, University of Tennessee Medical Center, Memphis 38163, USA
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31
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Mattern KA, Humbel BM, Muijsers AO, de Jong L, van Driel R. hnRNP proteins and B23 are the major proteins of the internal nuclear matrix of HeLa S3 cells. J Cell Biochem 1996; 62:275-89. [PMID: 8844407 DOI: 10.1002/(sici)1097-4644(199608)62:2<275::aid-jcb15>3.0.co;2-k] [Citation(s) in RCA: 93] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The nuclear matrix is the structure that persists after removal of chromatin and loosely bound components from the nucleus. It consists of a peripheral lamina-pore complex and an intricate internal fibrogranular structure. Little is known about the molecular structure of this proteinaceous internal network. Our aim is to identify the major proteins of the internal nuclear matrix of HeLa 53 cells. To this end, a cell fraction containing the internal fibrogranular structure was compared with one from which this structure had been selectively dissociated. Protein compositions were quantitatively analyzed after high-resolution two-dimensional gel electrophoresis. We have identified the 21 most abundant polypeptides that are present exclusively in the internal nuclear matrix. Sixteen of these proteins are heterogeneous nuclear ribonucleoprotein (hnRNP) proteins. B23 (numatrin) is another abundant protein of the internal nuclear matrix. Our results show that most of the quantitatively major polypeptides of the internal nuclear matrix are proteins involved in RNA metabolism, including packaging and transport of RNA.
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Affiliation(s)
- K A Mattern
- E.C. Slater Instituut, University of Amsterdam, The Netherlands
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32
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Hempel K, Strätling WH. The chicken lysozyme gene 5′ MAR and the Drosophila histone SAR are electroelutable from encapsulated and digested nuclei. J Cell Sci 1996; 109 ( Pt 6):1459-69. [PMID: 8799833 DOI: 10.1242/jcs.109.6.1459] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Cultured chicken cells were encapsulated in agarose microbeads, lysed in a near-physiological buffer and resulting encapsulated nuclei were digested with a restriction enzyme and electroeluted. After removal of approximately 97% of the chromatin, the nuclear lamina, residual nucleoli and an internal nuclear network remained. The majority of nascent RNA was also recovered in digested and electroeluted nuclei. Surprisingly, however, the chicken lysozyme gene 5′ MAR was quantitatively electroeluted from digested nuclei of expressing and non-expressing cells, as well as the promoter region and the coding sequence. When encapsulated nuclei were digested partially, the proportion of elutable 5′ MAR chromatin was comparable to that of elutable bulk chromatin. Furthermore, after digestion of encapsulated nuclei from Drosophila Kc cells, the histone SAR was electroeluted to the same extent as bulk chromatin. We conclude that the lysozyme gene 5′ MAR and the histone SAR are not permanently attached to a nuclear matrix or scaffold.
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Affiliation(s)
- K Hempel
- Institut für Physiologische Chemie, Universitäts-Krankenhaus Eppendorf, Hamburg, FR Germany
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33
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He D, Zeng C, Brinkley BR. Nuclear matrix proteins as structural and functional components of the mitotic apparatus. INTERNATIONAL REVIEW OF CYTOLOGY 1996; 162B:1-74. [PMID: 8557485 DOI: 10.1016/s0074-7696(08)62614-5] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The eukaryotic nucleus is a membrane-enclosed compartment containing the genome and associated organelles supported by a complex matrix of nonhistone proteins. Identified as the nuclear matrix, this component maintains spatial order and provides the structural framework needed for DNA replication, RNA synthesis and processing, nuclear transport, and steroid hormone action. During mitosis, the nucleoskeleton and associated chromatin is efficiently dismantled, packaged, partitioned, and subsequently reassembled into daughter nuclei. The dramatic dissolution of the nucleus is accompanied by the assembly of a mitotic apparatus required to facilitate the complex events associated with nuclear division. Until recently, little was known about the fate or disposition of nuclear matrix proteins during mitosis. The availability of specific molecular probes and imaging techniques, including confocal microscopy and improved immunoelectron microscopy using resinless sections and related procedures, has enabled investigators to identify and map the distribution of nuclear matrix proteins throughout the cell cycle. This chapter will review the structure, function, and distribution of the protein NuMA (nuclear matrix mitotic apparatus) and other nuclear matrix proteins that depart the nucleus during the interphase/mitosis transition to become structural and functional components within specific domains of the mitotic apparatus.
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Affiliation(s)
- D He
- Department of Cell Biology, Baylor College of Medicine, Houston, Texas 77030, USA
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34
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Bagchi M, Van Wijnen A, Katar M, Merriman H, Lian J, Stein J, Stein G, Maisel H. Sequence-specific DNA binding activities of nuclear matrix proteins of mammalian lens epithelial cells. J Cell Biochem 1995; 58:1-5. [PMID: 7642716 DOI: 10.1002/jcb.240580102] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
This study examines matrix and nonmatrix nuclear proteins of the rabbit lens epithelial cells. The nuclear matrix proteins were isolated by modified Penman technique, which requires presence of detergents and nucleases, whereas nonmatrix nuclear proteins were obtained by high salt extraction. The data from these experiments revealed presence of DNA binding activities for SP-1 and OCT-1 proteins in both matrix and non-matrix compartments of rabbit lens epithelial cells. Comparison of the relative abundance of SP-1 and OCT-1 binding activities in nuclear matrix and nonmatrix fractions suggest the distribution between these two compartments is cell type specific and possibly related to the control of cell growth.
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Affiliation(s)
- M Bagchi
- Department of Anatomy and Cell Biology, School of Medicine, Wayne State University, Detroit, Michigan 48201, USA
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35
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Fackelmayer FO, Richter A. Purification of two isoforms of hnRNP-U and characterization of their nucleic acid binding activity. Biochemistry 1994; 33:10416-22. [PMID: 8068679 DOI: 10.1021/bi00200a024] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The scaffold attachment factor A (SAF-A; Romig et al., 1992), a human nuclear protein which specifically binds vertebrate SAR (scaffold attached region) DNA, is identical with hnRNP-U (Kiledjian & Dreyfuss, 1992). In this paper, we report on the purification of two forms of this protein that can be chromatographically separated. We show that the purified proteins represent two isoforms, form 1 and form 2 hnRNP-U, which differ in their primary structure. Both isoforms bind to double- and single-stranded DNA and RNA. In addition, they form higher ordered nucleic acid/protein complexes and specifically bind and aggregate the human SAR element MII at physiological ionic strengths. Electron microscopic analysis shows that the isoforms differ from each other, as form 1 hnRNP-U aggregates into long unbranched filamentous protein/DNA complexes whereas form 2 hnRNP-U aggregates as spheres with an average diameter of 35 nm.
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36
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Wachsberger PR, Coss RA. Recovery of nuclear matrix ultrastructure of interphase CHO cells after heat shock. J Cell Physiol 1994; 160:97-106. [PMID: 7517408 DOI: 10.1002/jcp.1041600112] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Heat shock induces changes in G1 CHO cell nuclear matrix (NM) ultrastructure that may be related to heat-induced nuclear protein accumulation (Wachsberger and Coss, 1993, J. Cell. Physiol., 155:615-634). The present study quantitates recovery of alterations in NM fine structure in CHO cells heated in G1 and compares structural recovery with recovery of bulk RNA synthesis and surviving fraction (SF). Morphology of NM preparations was quantified 30 min and 20 hr following heat shock by 1) measurement of the number of fiber anastomosing points per unit area per NM, and 2) measurement of the length of fibers between points of anastomoses within individual NMs. Architectural recovery was nearly complete within 20 hr in cells heated at 43 degrees C or 45 degrees C with SFs of 0.27 or greater. No recovery of architecture was observed in heated cells with SFs of approximately 0.01 or less. The residual damage to NMs was associated with RNA-containing fiber networks as determined by means of RNase gold labeling. Recovery from inhibition of RNA synthesis following heat shock was related to recovery of NM architecture. It is suggested that 1) repair of NM architecture does not require full recovery of bulk RNA synthesis, and 2) partial or complete irreversible collapse of the NM may be responsible, in part, for heat-induced, interphase cell death.
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Affiliation(s)
- P R Wachsberger
- Department of Radiation Oncology and Nuclear Medicine, Laboratory of Experimental Radiation Oncology
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37
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Abstract
Tissue specific regulation of gene expression by a single transcription factor or group of transcription factors cannot be explained simply by DNA sequence alone. For example, in the same animal a particular transcription factor is capable of interacting with DNA in the nucleus of many different cell types, resulting in unique gene expressions despite the presence of a similar genome in all cells. Historically, these differences in response to a single type of factor within target tissues in the same animal have been suggested to occur through different alterations in chromatin structure. Recent, data has demonstrated that combinations of hormones and transcription factors working together may cooperatively play a role in the regulation of gene expression [Pearce and Yamamoto (1993): Science 259:1161-1165]. However, the molecular mechanisms of this tissue specific regulation of gene expression still remains largely unexplained. Current evidence suggests that in different cell types the interplay between the specific three-dimensional organization of the genome and the structural components of the nucleus, the nuclear matrix, may accomplish the regulation of specific gene expression.
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Affiliation(s)
- R H Getzenberg
- Pittsburgh Cancer Institute, University of Pittsburgh Medical Center, Pennsylvania 15213-2582
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38
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Fackelmayer FO, Dahm K, Renz A, Ramsperger U, Richter A. Nucleic-acid-binding properties of hnRNP-U/SAF-A, a nuclear-matrix protein which binds DNA and RNA in vivo and in vitro. EUROPEAN JOURNAL OF BIOCHEMISTRY 1994; 221:749-57. [PMID: 8174554 DOI: 10.1111/j.1432-1033.1994.tb18788.x] [Citation(s) in RCA: 132] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
We show that SAF-A, a nuclear protein which specifically binds vertebrate scaffold-attachment-region (SAR) elements with high affinity is identical with hnRNP-U, assumed to be involved in packaging of hnRNA in ribonucleoprotein particles. Ultraviolet cross-linking experiments show that the protein, referred to as hnRNP-U/SAF-A, is bound to chromosomal DNA in vivo. In vitro, the isolated protein binds to double-stranded and single-stranded DNA and forms higher ordered nucleic-acid-protein complexes. Filter-binding experiments performed with different types of natural and synthetic nucleic acids as substrates show that the protein binds DNA and RNA with different affinities and most likely at different binding sites. We conclude that hnRNP-U/SAF-A thus may have functions in the organisation of chromosomal DNA in addition to its suggested role in hnRNA metabolism.
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39
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Abstract
A complex structure, visible by electron microscopy, surrounds each chromosome during mitosis. The organization of this structure is distinct from that of the chromosomes and the cytoplasm. It forms a perichromosomal layer that can be isolated together with the chromosomes. This layer covers the chromosomes except in centromeric regions. The perichromosomal layer includes nuclear and nucleolar proteins as well as ribonucleoproteins (RNPs). The list of proteins and RNAs identified includes nuclear matrix proteins (perichromin, peripherin), nucleolar proteins (perichro-monucleolin, Ki-67 antigen, B23 protein, fibrillarin, p103, p52), ribosomal proteins (S1) and snRNAs (U3 RNAs). Only limited information is available about how and when the perichromosomal layer is formed. During early prophase, the proteins extend from the nucleoli towards the periphery of the nucleus. Thin cordon-like structures reach the nuclear envelope delimiting areas in which chromosomes condense. At telophase, the proteins are associated with the part of the chromosomes remaining condensed and accumulate in newly formed nucleoli in regions where chromatin is already decondensed. The perichromosomal layer contains several different classes of proteins and RNPs and it has been attributed various roles: (1) in chromosome organization, (2) as a barrier around the chromosomes, (3) involvement in compartmentation of the cells in prophase and telophase and (4) a binding site for chromosomal passenger proteins necessary to the early process of nuclear assembly.
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40
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Wan KM, Nickerson JA, Krockmalnic G, Penman S. The B1C8 protein is in the dense assemblies of the nuclear matrix and relocates to the spindle and pericentriolar filaments at mitosis. Proc Natl Acad Sci U S A 1994; 91:594-8. [PMID: 8290569 PMCID: PMC42995 DOI: 10.1073/pnas.91.2.594] [Citation(s) in RCA: 55] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
The B1C8 monoclonal antibody detects a 180-kDa nuclear matrix-specific protein. The protein is a component of the dense, metabolically active bodies or assemblies revealed by resinless section electron microscopy of the nuclear matrix. These assemblies are scattered through the nuclear interior, enmeshed in a complex network of 11-nm filaments. Resinless section electron microscopy of immunogold-stained nuclear matrix preparations shows B1C8 located in many but apparently not all the assemblies. In this regard, the B1C8 antigen resembles previously studied nuclear matrix proteins such as the H1B2 protein. The speckled pattern of nuclear immunofluorescence by B1C8 reflects this labeling of the dense assemblies in the nuclear matrix. Somewhat unusual is the faint staining of cytoplasmic microtubules by B1C8, which appears to be due to a weakly cross-reacting protein. During cell division, the B1C8 antigen redistributed drastically, showing the dispersion of nuclear matrix assemblies at mitosis. Speckles of B1C8 fluorescence first coalesced at prophase within the nuclear interior and then scattered into numerous cytoplasmic speckles by prometaphase. At metaphase, the B1C8 speckled cytoplasmic staining had become even more widely distributed and finely grained. Also, intense labeling appeared at the mitotic pole and on the spindle fibers themselves. The reassembly of B1C8 antigens into larger cytoplasmic speckles began at anaphase and finally, at telophase, most B1C8 labeling redistributed into speckles in the re-forming nuclei.
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Affiliation(s)
- K M Wan
- Department of Biology, Massachusetts Institute of Technology, Cambridge 02139
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41
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Zeng C, He D, Brinkley BR. Localization of NuMA protein isoforms in the nuclear matrix of mammalian cells. CELL MOTILITY AND THE CYTOSKELETON 1994; 29:167-76. [PMID: 7820866 DOI: 10.1002/cm.970290208] [Citation(s) in RCA: 81] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Using a monoclonal antibody 2D3 generated against a kinetochore-enriched human chromosome preparation, we identified a high molecular mass protein with nuclear staining in interphase and polar staining of the pericentriolar region in the mitotic spindle. Initially termed centrophilin, this protein associates with the minus-ends of spindle microtubules (MT) and appears to be important in spindle organization [Tousson et al., 1991: J. Cell Biol. 112:427-440]. Comparison of a partial cDNA sequence obtained for centrophilin with the full length cDNA sequence of nuclear mitotic apparatus protein (NuMA) [Compton et al., 1992: J. Cell Biol. 116:1395-1408; Yang et al., 1992: J. Cell Biol. 116:1303-1317] has indicated that NuMA and centrophilin are the same protein. Using a polyclonal NuMA antibody, we have provided further evidence that NuMA exists as isoforms as shown by peptide mapping and immunoblots. Sequential fractionation experiments along with immunofluorescence, immunoblotting, and EM immunogold labeling have demonstrated that NuMA isoforms are novel components of nuclear core filaments. Thus, NuMA, a long coiled-coil protein, appears to have dual functions in interphase and mitosis during the cell cycle. In interphase, NuMA likely plays a structural role in the nucleoskeleton that may be important in nuclear organization and functions, whereas in mitosis, NuMA appears to be associated with spindle MT organization and chromosome positioning.
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Affiliation(s)
- C Zeng
- Department of Cell Biology, Baylor College of Medicine, Houston, Texas
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42
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Traub P, Shoeman RL. Intermediate filament proteins: cytoskeletal elements with gene-regulatory function? INTERNATIONAL REVIEW OF CYTOLOGY 1994; 154:1-103. [PMID: 8083030 DOI: 10.1016/s0074-7696(08)62198-1] [Citation(s) in RCA: 58] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- P Traub
- Max-Planck-Institut für Zellbiologie, Ladenburg/Heidelberg, Germany
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43
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Julian M, Tollon Y, Lajoie-Mazenc I, Moisand A, Mazarguil H, Puget A, Wright M. gamma-Tubulin participates in the formation of the midbody during cytokinesis in mammalian cells. J Cell Sci 1993; 105 ( Pt 1):145-56. [PMID: 8360269 DOI: 10.1242/jcs.105.1.145] [Citation(s) in RCA: 118] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Animal cells undergoing cytokinesis form an inter-cellular bridge containing two bundles of microtubules interdigitated at their plus ends, which constitute the midbody. Polyclonal antibodies raised against three specific amino acid sequences of gamma-tubulin (EEFATEGGDRKDV, NIIQGEADPTDVHKSL and EYHAATRPDYISWGTQEQ) specifically stained the centrosome in interphase, the spindle poles in all stages of mitosis, and the extremities of the midbody in mammalian cells (Potorous, human, Chinese hamster, mouse). This staining was prevented by the corresponding peptides, by Xenopus gamma-tubulin, but was not modified by purified alpha beta-tubulin heterodimer. An identical staining was obtained with affinity-purified antibodies against the carboxyl-terminal amino acid sequence of human gamma-tubulin. No gamma-tubulin could be detected in the interzone during anaphase and early telophase. Material containing gamma-tubulin first appeared in the two daughter cells on each side of the division plane in late telophase, and accumulated transiently at the minus ends of the two microtubule bundles constituting the midbody for one hour after metaphase. Micro-injection of gamma-tubulin antibodies into anaphase cells prevented the subsequent formation of the microtubule bundles between the two daughter cells. In contrast with previous views, these observations suggest that the microtubules constituting the midbody may be nucleated on special microtubule organizing centres, active during late telophase only, and assembled on each side of the dividing plane between the daughter cells.
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Affiliation(s)
- M Julian
- Laboratoire de Pharmacologie et de Toxicologie fondamentales, CNRS, Toulouse, France
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44
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Basu HS, Wright WD, Deen DF, Roti-Roti J, Marton LJ. Treatment with a polyamine analog alters DNA-matrix association in HeLa cell nuclei: a nucleoid halo assay. Biochemistry 1993; 32:4073-6. [PMID: 8471614 DOI: 10.1021/bi00066a031] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The polyamine analog 1,14-bis(ethylamino)-5,10-diazatetradecane (BE-4-4-4) depletes polyamines and inhibits the growth of tumor cells in tissue culture. We treated HeLa cells in culture with BE-4-4-4 for different time periods to produce different degrees of polyamine depletion. The cells were lysed and dehistonized to obtain nucleoids containing DNA attached to the nuclear matrix. Titration of the nucleoids with propidium iodide caused an uncoiling of negatively supercoiled DNA, resulting in the formation of a halo surrounding the nucleoid periphery. The halo diameters in both the BE-4-4-4-treated cells and the untreated control cells were measured using a fluorescence image analysis system. As compared to the control cells, the BE-4-4-4-treated cells showed a 20-25% decrease in halo diameter, indicating that there was less relaxation of the negative supercoils in the nuclear DNA of the BE-4-4-4-treated cells than in the controls.
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Affiliation(s)
- H S Basu
- Department of Neurological Surgery, University of California, San Francisco 94143
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