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Osorio DS, Gomes ER. The contemporary nucleus: A trip down memory lane. Biol Cell 2013; 105:430-41. [DOI: 10.1111/boc.201300009] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2013] [Accepted: 06/21/2013] [Indexed: 01/12/2023]
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2
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Kalive M, Zhang W, Chen Y, Capco DG. Human intestinal epithelial cells exhibit a cellular response indicating a potential toxicity upon exposure to hematite nanoparticles. Cell Biol Toxicol 2012; 28:343-68. [PMID: 22903759 DOI: 10.1007/s10565-012-9229-7] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2012] [Accepted: 07/30/2012] [Indexed: 02/06/2023]
Abstract
This study examined the effects of different-sized nanoparticles on potential cytotoxicity in intestinal epithelia. Three sizes of hematite nanoparticles were used for the study at a 10 ppm concentration: 17, 53, and, 100 nm. Results indicate that, of the hematite nanoparticles tested, 17 nm was more toxic to the epithelial integrity than 53 or 100 nm. In addition, the epithelial integrity was affected by disruption of epithelial structures such as apical microvilli, and by disruption of the cell-cell junctions leading to reduction in transepithelial electrical resistance measurements (TEER). The drop in TEER was caused by disruption of the adhering junctions not by cell death, as determined by immunocytochemistry, and by using a cell viability assay. Epithelial integrity was also affected at the molecular level as shown by differential expression of genes related to cell junction maintenance, which was assessed by microarray analysis. In conclusion, the 17- and 100-nm hematite nanoparticles caused significant structural changes in the epithelium but not the 53 nm nanoparticles. Also, different-sized hematite nanoparticles each had different effects both at the cellular level and genetic level.
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Affiliation(s)
- Madhavi Kalive
- School of Life Sciences, Cell and Molecular Biosciences, Arizona State University, Tempe, AZ 85287-4501, USA
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3
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Dialynas G, Flannery KM, Zirbel LN, Nagy PL, Mathews KD, Moore SA, Wallrath LL. LMNA variants cause cytoplasmic distribution of nuclear pore proteins in Drosophila and human muscle. Hum Mol Genet 2011; 21:1544-56. [PMID: 22186027 PMCID: PMC3298278 DOI: 10.1093/hmg/ddr592] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Mutations in the human LMNA gene, encoding A-type lamins, give rise to laminopathies, which include several types of muscular dystrophy. Here, heterozygous sequence variants in LMNA, which result in single amino-acid substitutions, were identified in patients exhibiting muscle weakness. To assess whether the substitutions altered lamin function, we performed in vivo analyses using a Drosophila model. Stocks were generated that expressed mutant forms of the Drosophila A-type lamin modeled after each variant. Larvae were used for motility assays and histochemical staining of the body-wall muscle. In parallel, immunohistochemical analyses were performed on human muscle biopsy samples from the patients. In control flies, muscle-specific expression of the wild-type A-type lamin had no apparent affect. In contrast, expression of the mutant A-type lamins caused dominant larval muscle defects and semi-lethality at the pupal stage. Histochemical staining of larval body wall muscle revealed that the mutant A-type lamin, B-type lamins, the Sad1p, UNC-84 domain protein Klaroid and nuclear pore complex proteins were mislocalized to the cytoplasm. In addition, cytoplasmic actin filaments were disorganized, suggesting links between the nuclear lamina and the cytoskeleton were disrupted. Muscle biopsies from the patients showed dystrophic histopathology and architectural abnormalities similar to the Drosophila larvae, including cytoplasmic distribution of nuclear envelope proteins. These data provide evidence that the Drosophila model can be used to assess the function of novel LMNA mutations and support the idea that loss of cellular compartmentalization of nuclear proteins contributes to muscle disease pathogenesis.
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Affiliation(s)
- George Dialynas
- Department of Biochemistry, University of Iowa, Iowa City, IA 52242, USA
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4
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Dialynas G, Speese S, Budnik V, Geyer PK, Wallrath LL. The role of Drosophila Lamin C in muscle function and gene expression. Development 2010; 137:3067-77. [PMID: 20702563 DOI: 10.1242/dev.048231] [Citation(s) in RCA: 91] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The inner side of the nuclear envelope (NE) is lined with lamins, a meshwork of intermediate filaments that provides structural support for the nucleus and plays roles in many nuclear processes. Lamins, classified as A- or B-types on the basis of biochemical properties, have a conserved globular head, central rod and C-terminal domain that includes an Ig-fold structural motif. In humans, mutations in A-type lamins give rise to diseases that exhibit tissue-specific defects, such as Emery-Dreifuss muscular dystrophy. Drosophila is being used as a model to determine tissue-specific functions of A-type lamins in development, with implications for understanding human disease mechanisms. The GAL4-UAS system was used to express wild-type and mutant forms of Lamin C (the presumed Drosophila A-type lamin), in an otherwise wild-type background. Larval muscle-specific expression of wild type Drosophila Lamin C caused no overt phenotype. By contrast, larval muscle-specific expression of a truncated form of Lamin C lacking the N-terminal head (Lamin C DeltaN) caused muscle defects and semi-lethality, with adult 'escapers' possessing malformed legs. The leg defects were due to a lack of larval muscle function and alterations in hormone-regulated gene expression. The consequences of Lamin C association at a gene were tested directly by targeting a Lamin C DNA-binding domain fusion protein upstream of a reporter gene. Association of Lamin C correlated with localization of the reporter gene at the nuclear periphery and gene repression. These data demonstrate connections among the Drosophila A-type lamin, hormone-induced gene expression and muscle function.
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Affiliation(s)
- George Dialynas
- Department of Biochemistry, University of Iowa, Iowa City, IA 52241, USA
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5
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Demasi MAA, Montor WR, Ferreira GB, Pimenta DC, Labriola L, Sogayar MC. Differential proteomic analysis of the anti-proliferative effect of glucocorticoid hormones in ST1 rat glioma cells. J Steroid Biochem Mol Biol 2007; 103:137-48. [PMID: 17127050 DOI: 10.1016/j.jsbmb.2006.08.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/30/2005] [Accepted: 08/17/2006] [Indexed: 02/02/2023]
Abstract
Glucocorticoid hormones (GCs) exert a potent anti-proliferative activity on several cell types. The classic molecular mechanism of GCs involves modulation of the activity of the glucocorticoids receptor, a transcriptional regulator. However, the anti-proliferative effect of GCs may also involve modulation of processes such as translation, subcellular localization and post-translational modifications, which are not reflected at the mRNA level. To investigate these potential effects of GCs, we employed the proteomic approach (two-dimensional electrophoresis and mass spectrometry) and the ST1 cells, obtained from the C6 rat glioma cell line, as a model. GC treatment leads ST1 cells to a complete transformed-to-normal phenotypic reversion and loss of their tumorigenic potential. By comparing sets of 2D nuclear protein profiles of ST1 cells treated (or not) with hydrocortisone (Hy), 13 polypeptides displaying >or=two-fold difference in abundance upon Hy treatment were found. Five of these polypeptides were identified by peptide mass fingerprinting, including Annexin 2 (ANX2), hnRNP A3 and Ubiquitin. Evidence obtained by Western blot analysis indicates that ANX2 is present in the nucleus and has its subcellular localization modulated by GC-treatment of ST1 cells. Our findings indicate complementary mechanisms contributing to the regulation of gene expression associated with ST1 cells' response to GCs.
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Affiliation(s)
- Marcos A A Demasi
- Instituto de Química, Universidade de São Paulo, 05508-900 SP, São Paulo, Brazil
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6
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Javed A, Barnes GL, Pratap J, Antkowiak T, Gerstenfeld LC, van Wijnen AJ, Stein JL, Lian JB, Stein GS. Impaired intranuclear trafficking of Runx2 (AML3/CBFA1) transcription factors in breast cancer cells inhibits osteolysis in vivo. Proc Natl Acad Sci U S A 2005; 102:1454-9. [PMID: 15665096 PMCID: PMC547873 DOI: 10.1073/pnas.0409121102] [Citation(s) in RCA: 156] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2004] [Indexed: 12/24/2022] Open
Abstract
Runx transcription factors comprise a family of proteins that are essential for organogenesis. A unique nuclear matrix-targeting signal in the C terminus directs these factors to their appropriate subnuclear domains. At these sites, they interact with coregulatory proteins and target genes. We have previously shown that aberrant expression of the Runx2 DNA binding domain in metastatic breast cancer cells can prevent production of osteolytic lesions in bone. Here, we show that proper Runx2 subnuclear targeting is required for osteolysis. We have identified point mutations of the Runx2 nuclear matrix-targeting signal sequence that impair its targeting to nuclear matrix sites. These mutations block the invasive and osteolytic properties of MDA-MB-231 breast cancer cells in vivo. Cell lines expressing this Runx2 mutant protein inhibit the osteogenic properties of bone marrow stromal cells in coculture assays. The mutant breast cancer cells also exhibit reduced invasiveness in vitro and do not express genes involved in invasion and angiogenesis (VEGF and MMP13). Our findings suggest that fidelity of Runx2 intranuclear organization is necessary for expression of target genes that mediate the osteolytic activity of metastatic breast cancer cells.
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Affiliation(s)
- Amjad Javed
- Department of Cell Biology and Cancer Center, University of Massachusetts Medical School, 55 Lake Avenue North, Worcester, MA 01655, USA
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7
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Zaidi SK, Young DW, Pockwinse SM, Javed A, Lian JB, Stein JL, van Wijnen AJ, Stein GS. Mitotic partitioning and selective reorganization of tissue-specific transcription factors in progeny cells. Proc Natl Acad Sci U S A 2003; 100:14852-7. [PMID: 14657346 PMCID: PMC299826 DOI: 10.1073/pnas.2533076100] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2003] [Indexed: 11/18/2022] Open
Abstract
Postmitotic gene expression requires restoration of nuclear organization and assembly of regulatory complexes. The hematopoietic and osteogenic Runx (Cbfa/AML) transcription factors are punctately organized in the interphase nucleus and provide a model for understanding the subnuclear organization of tissue-specific regulatory proteins after mitosis. Here we have used quantitative in situ immunofluorescence microscopy and quantitative image analysis to show that Runx factors undergo progressive changes in cellular localization during mitosis while retaining a punctate distribution. In comparison, the acetyl transferase p300 and acetylated histone H4 remain localized with DNA throughout mitosis while the RNA processing factor SC35 is excluded from mitotic chromatin. Subnuclear organization of Runx foci is completely restored in telophase, and Runx proteins are equally partitioned into progeny nuclei. In contrast, subnuclear organization of SC35 is restored subsequent to telophase. Our results show a sequential reorganization of Runx and its coregulatory proteins that precedes restoration of RNA processing speckles. Thus, mitotic partitioning and spatiotemporal reorganization of regulatory proteins together render progeny cells equivalently competent to support phenotypic gene expression.
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Affiliation(s)
- Sayyed K Zaidi
- Department of Cell Biology and Cancer Center, University of Massachusetts Medical School, Worcester, MA 01655-0105, USA
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8
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Doornaert B, Leblond V, Galiacy S, Gras G, Planus E, Laurent V, Isabey D, Lafuma C. Negative impact of DEP exposure on human airway epithelial cell adhesion, stiffness, and repair. Am J Physiol Lung Cell Mol Physiol 2003; 284:L119-32. [PMID: 12471014 DOI: 10.1152/ajplung.00039.2002] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Epidemiological and experimental studies suggest that diesel exhaust particles (DEPs) may be associated with increased respiratory mortality and morbidity. Several recent studies have also shown that DEPs increase the production of inflammatory cytokines by human bronchial epithelium (HBE) cells in vitro. The present study investigates the effects of DEPs on the interaction of l-HBE cells (16HBE14o-) with the cell and matrix microenvironment based on evaluation of integrin-type cell/matrix ligand expression, cytoskeleton (CSK) stiffness, and matrix remodeling via matrix metalloproteinase (MMP)-1, MMP-2, and MMP-9 expression. The results showed that DEP exposure induced: 1) a net dose-dependent decrease in CSK stiffness through actin fibers, 2) a concomitant specific reduction of both alpha(3)- and beta(1)-integrin subunits extensively expressed on the HBE cell surface, 3) a decrease in the level of CD44, which is a major HBE cell-cell and HBE cell-matrix adhesion molecule; and 4) an isolated decrease in MMP-1 expression without any change in tissue inhibitor of matrix metalloproteinase (TIMP)-1 or TIMP-2 tissue inhibitors. Restrictive modulation of cell-matrix interaction, cell-cell connection, CSK stiffness, and fibrillary collagen remodeling results in a decreased wound closure capacity and an increased deadhesion capacity. In conclusion, on the basis of these results, we can propose that, in addition to their ability to increase the production of inflammatory cytokines, DEPs could also alter the links between actin CSK and the extracellular matrix, suggesting that they might facilitate HBE cell detachment in vivo.
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Affiliation(s)
- Blandine Doornaert
- Faculté de Médecine, Faculté des Sciences Université Paris XII, Institut National de la Santé et de la Recherche Médicale, Unité 492 de Physiopathologie et Thérapeutique Respiratoire, 8 rue du Général Sarrail, 94010 Créteil Cedex, France
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9
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Goldman RD, Gruenbaum Y, Moir RD, Shumaker DK, Spann TP. Nuclear lamins: building blocks of nuclear architecture. Genes Dev 2002; 16:533-47. [PMID: 11877373 DOI: 10.1101/gad.960502] [Citation(s) in RCA: 442] [Impact Index Per Article: 20.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Affiliation(s)
- Robert D Goldman
- Northwestern University Medical School, Department of Cell and Molecular Biology, Chicago, Illinois 60611, USA.
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10
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Nievers MG, Schaapveld RQ, Oomen LC, Fontao L, Geerts D, Sonnenberg A. Ligand-independent role of the beta 4 integrin subunit in the formation of hemidesmosomes. J Cell Sci 1998; 111 ( Pt 12):1659-72. [PMID: 9601096 DOI: 10.1242/jcs.111.12.1659] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Recently, we have shown that a region within the beta4 cytoplasmic domain, encompassing the second fibronectin type III (FNIII) repeat and the first 27 amino acids of the connecting segment, is critical for the localization of alpha6 beta4 in hemidesmosomes. In addition, this region was shown to regulate the distribution of HD1/plectin in transfected cells. In order to investigate the function of the beta4 extracellular and cytoplasmic domains in the assembly and integrity of hemidesmosomes, we have constructed chimeric receptors consisting of the extracellular and transmembrane domains of the interleukin 2 receptor (IL2R), fused to different parts of the beta4 cytoplasmic domain. These chimeras are expressed as single subunits at the plasma membrane. The results show that the first and the second FNIII repeat, together with the first part of the connecting segment (in total a stretch of 241 amino acids spanning amino acids 1,115 to 1,356) are both essential and sufficient for the localization of beta4 in pre-existing hemidesmosomes. Moreover, expression of the IL2R/beta4 chimeric constructs in COS-7 and CHO cells, which do not express alpha6 beta4 or the bullous pemphigoid (BP) antigens but do express HD1/plectin, revealed that the stretch of 241 amino acids is sufficient for inducing the formation of type II hemidesmosomes. Expression of the IL2R/beta4 chimeras in a keratinocyte cell line derived from a patient lacking beta4 expression, showed that amino acids 1,115 to 1,356 can also induce the formation of type I hemidesmosomes. We further demonstrate that type I and II hemidesmosomes can also be formed upon adhesion of alpha6 beta4-expressing cells to fibronectin. These findings establish that the beta4 extracellular domain is not essential for the induction of hemidesmosome assembly. Moreover, they demonstrate that binding of alpha6 beta4 to ligand, and heterodimerization of alpha6 with beta4, are not required for hemidesmosome formation. This indicates that the assembly of hemidesmosomes can be regulated from within the cell.
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Affiliation(s)
- M G Nievers
- The Netherlands Cancer Institute, Division of Cell Biology, Plesmanlaan 121, The Netherlands
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11
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Nievers MG, Birge RB, Greulich H, Verkleij AJ, Hanafusa H, van Bergen en Henegouwen PM. v-Crk-induced cell transformation: changes in focal adhesion composition and signaling. J Cell Sci 1997; 110 ( Pt 3):389-99. [PMID: 9057091 DOI: 10.1242/jcs.110.3.389] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
v-Crk is an oncogene product in which a viral Gag sequence is fused to a cellular Crk sequence. It contains one SH2 and one SH3 domain. To gain insight into the molecular mechanisms underlying v-Crk-induced cell transformation, we studied the subcellular localization and molecular interactions of v-Crk in v-Crk-transformed NIH-3T3 cells. Our results show that v-Crk specifically localizes to focal adhesions where it induces protein tyrosine phosphorylation. Subcellular fractionation studies indicated that a significant amount of v-Crk is present in the cytoskeletal cell fraction, a fraction that includes focal adhesions. Tyrosine phosphorylated proteins, including p130CAS, were also predominantly found in the cytoskeletal fraction. We show that v-Crk induces a translocation of p130CAS to the cytoskeleton, which is accompanied by hyperphosphorylation of this protein. Mutational analyses showed that functional v-Crk SH2 domain is required for the localization of v-Crk in focal adhesions. Functional v-Crk SH2 and SH3 domains were both found to be required for the observed increase in tyrosine phosphorylation of focal adhesion proteins and for the translocation and hyperphosphorylation of p130CAS. v-Crk immunoprecipitation studies revealed that cytoskeleton-associated v-Crk interacts with both p130CAS and an unidentified tyrosine kinase. These findings suggest that formation of a focal adhesion-located complex consisting of v-Crk, a tyrosine kinase and p130CAS, which may lead to the hyperphosphorylation of p130CAS. These specific and localized signaling events may represent initial steps in the process of v-Crk-induced cell transformation.
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Affiliation(s)
- M G Nievers
- Department of Molecular Cell Biology, Institute of Biomembranes, Utrecht University, The Netherlands.
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12
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Watanabe H, MacKay CA, Kislauskis E, Mason-Savas A, Marks SC. Ultrastructural evidence of abnormally short and maldistributed actin stress fibers in osteopetrotic (toothless) rat osteoblasts in situ after detergent perfusion. Tissue Cell 1997; 29:89-98. [PMID: 9061979 DOI: 10.1016/s0040-8166(97)80075-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Osteopetrosis is a heterogenous group of metabolic bone diseases characterized by a generalized increase in skeletal mass, the product of reduced bone resorption and interceptions in the development and/or function of osteoclasts. In one such mutation in the rat, toothless (tl), osteoblasts are absent from older bone surfaces and there is evidence for aberrant osteoblast gene expression and function. Given the emerging appreciation of the role of osteoblasts in the differentiation and activation of osteoclasts, we have examined ultrastructural features of the cytoskeleton of normal and mutant osteoblasts after perfusion fixation with the non-ionic detergent Triton X-100. This procedure reduces the electron density of the cytoplasm, rendering visible the microfilamentous network in osteoblasts. In normal osteoblasts a prominent system of stress fibers (bundles of actin microfilaments) run parallel to the cell membrane adjacent to osteoid surfaces, stretching for 75% of that distance. However, only 50% of mutant (tl) osteoblasts had stress fibers and in these cells stress fibers were either significantly shorter (18% of normal) or distributed intracellularly rather than along the osteoid surface. In mutant osteoblasts without stress fibers, 20% showed ultrastructural signs of cell degeneration. Given the role of stress fibers in cellular attachment ot extracellular matrices, these observations suggest that the reduced number of osteoblasts in tl rats may be related to their inability to organize actin filaments and adhesion plaques for attachment to bone surfaces. We propose that a feature of osteopetrosis in the tl rat is a disruption of the mechanisms that regulate the synthesis, sorting, and/or assembly of actin.
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Affiliation(s)
- H Watanabe
- Department of Cell Biology, University of Massachusetts Medical Center, Worcester 01655, USA
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13
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14
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Abstract
The eukaryotic cell nucleus is a membrane-enclosed compartment containing the genome and associated molecules supported by a highly insoluble filamentous network known as the nucleoskeleton or nuclear matrix. The nuclear matrix is believed to play roles in maintaining nuclear architecture and organizing nuclear metabolism. Recently, advances in microscopic techniques and the availability of new molecular probes have made it possible to localize functional domains within the nuclear matrix and demonstrate dynamic interactions between both soluble and insoluble components involved in the control of multiple nuclear transactions. Like the cytoplasm and its skeleton, the nucleoplasm is highly structured and very crowded with an equally complex skeletal framework. In fact, there is growing evidence that the two skeletal systems are functionally contiguous, providing a dynamic cellular matrix connecting the cell surface with the genome. If we impose cell cycle dynamics upon this skeletal organization, it is obvious that the genome and associated nuclear matrix must undergo a major structural transition during mitosis, being disassembled and/or reorganized in late G2 and reassembled again in daughter nuclei. However, recent evidence from our laboratory and elsewhere suggests that much of the nuclear matrix is used to form the mitotic apparatus (MA). Indeed, both facultative and constitutive matrix-associated proteins such as NuMA, CENP-B, CENP-F, and the retinoblastoma protein (Rb) associate within and around the MA. During mitosis, the nuclear matrix proteins may either become inert "passengers" or assume critical functions in partitioning the genome into newly formed G1 nuclei. Therefore, we support the view that the nuclear matrix exists as a dynamic architectural continuum, embracing the genome and maintaining cellular regulation throughout the cell cycle.
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Affiliation(s)
- M A Mancini
- Department of Cell Biology, Baylor College of Medicine, Houston, Texas 77030, USA
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15
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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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16
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Pomorski P, Grçbecka L. Nuclear movements and nuclear actin in bilobed nuclei of Amoeba proteus. Eur J Protistol 1995. [DOI: 10.1016/s0932-4739(11)80089-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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17
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Nickerson JA, Krockmalnic G, Wan KM, Turner CD, Penman S. A normally masked nuclear matrix antigen that appears at mitosis on cytoskeleton filaments adjoining chromosomes, centrioles, and midbodies. J Cell Biol 1992; 116:977-87. [PMID: 1734026 PMCID: PMC2289346 DOI: 10.1083/jcb.116.4.977] [Citation(s) in RCA: 54] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
mAbs were generated against HeLa nuclear matrix proteins and one, HIB2, which selectively stained mitotic cells, was selected for further study. Western blot analysis showed H1B2 antibody detected a protein of 240 kD in the nuclear matrix fractions. The H1B2 antigen was completely masked in immunofluorescently stained interphase cells. However, removing chromatin with DNase I digestion and 0.25 M ammonium sulfate extraction exposed the protein epitope. The resulting fluorescence pattern was bright, highly punctate, and entirely nuclear. Further extraction of the nuclear matrix with 2 M NaCl uncovers an underlying, anastomosing network of 9-13 nm core filaments. Most of the H1B2 antigen was retained in the fibrogranular masses enmeshed in the core filament network and not in the filaments themselves. The H1B2 antigen showed remarkable behavior at mitosis. As cells approached prophase the antigen became unmasked to immunofluorescent staining without the removal of chromatin. First appearing as a bright spot, the antibody staining spread through the nucleus finally concentrating in the region around the condensed chromosomes. The antibody also brightly stained the spindle poles and, more weakly, in a punctate pattern in the cytoskeleton around the spindle. As the chromosomes separated at anaphase, H1B2 remained with the separating daughter sets of chromosomes. The H1B2 antigen returned to the reforming nucleus at telophase, but left a bright staining region in the midbody. Immunoelectron microscopy of resinless sections showed that, in the mitotic cell, the H1B2 antibody did not stain chromosomes and centrioles themselves, but decorated a fibrogranular network surrounding and connected to the chromosomes and a fibrogranular structure surrounding the centriole.
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Affiliation(s)
- J A Nickerson
- Department of Biology, Massachusetts Institute of Technology, Cambridge 02139
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18
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Kessel RG. Annulate lamellae: a last frontier in cellular organelles. INTERNATIONAL REVIEW OF CYTOLOGY 1992; 133:43-120. [PMID: 1374369 DOI: 10.1016/s0074-7696(08)61858-6] [Citation(s) in RCA: 128] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- R G Kessel
- Department of Biology, University of Iowa, Iowa City 52242
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19
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He DC, Martin T, Penman S. Localization of heterogeneous nuclear ribonucleoprotein in the interphase nuclear matrix core filaments and on perichromosomal filaments at mitosis. Proc Natl Acad Sci U S A 1991; 88:7469-73. [PMID: 1881885 PMCID: PMC52321 DOI: 10.1073/pnas.88.17.7469] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Although heterogeneous nuclear RNA (hnRNA) has been localized to the core filament substructure of the nuclear matrix, its precise location in the filament network has been unknown. The fA12 monoclonal antibody can localize, at high resolution, hn ribonucleoproteins (hnRNPs) and, presumably, hnRNA. Gold bead immunolabeling of resinless electron microscopy sections showed the fA12 antigens were in the fibrogranular material enmeshed in the filament network and not in the filaments themselves. At mitosis, hnRNP antigens became dispersed into a halo surrounding the chromosomes and spindle poles. Immunogold staining showed fA12 stained fibrogranular material associated with perichromosomal and pericentriolar filaments distinct from the mitotic spindle fibers. fA12 also labeled the midbody remaining after cytokinesis.
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Affiliation(s)
- D C He
- Department of Biology, Massachuseets Institute of Technology, Cambridge 02139
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20
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Capco DG, Bement WM. Analysis of cellular signaling events, the cytoskeleton, and spatial organization of macromolecules during early Xenopus development. Methods Cell Biol 1991; 36:249-70. [PMID: 1811137 DOI: 10.1016/s0091-679x(08)60281-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- D G Capco
- Department of Zoology, Arizona State University, Tempe 85287-1501
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21
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Hodge LD, Martinez JE, Allsbrook WC, Pantazis CG, Welter DA. Intermediate structures in nuclear morphogenesis following metaphase from HeLaS3 cells can be isolated and temporally grouped. Chromosoma 1990; 99:169-82. [PMID: 2204519 DOI: 10.1007/bf01731127] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Previously nuclear reformation following metaphase in HeLaS3 cells was conceptualized in terms of a stepwise process which was continuous throughout anaphase and telophase. This concept was based on a three-dimensional visualization by scanning electron microscopy (SEM) of individual, organically prepared chromatid structures (prenuclei) which could be sequentially arranged. Morphologic analysis revealed unique topographies and morphometric properties which suggested that it should be possible to isolate populations of prenuclei aqueously. Such an isolation using detergents and density centrifugation is presented which yields metaphase plates and two populations of prenuclei with distinctive morphology. Essentially, prenuclei are freed from late mitotic cells in suspension cultures of synchronized HeLaS3 cells by treatment with 0.1% Nonidet-P40 followed by treatment with a mixture of Tween 40-desoxycholate (0.5%). Critical for the isolation is the presence of a divalent cation (5 mM Mg(+)+) and an acid pH (approximately 5.8). After density centrifugation, 2N decondensing structures (late intermediates) are recovered from 42% Percoll, and a mixture of 2N predecondensing (early intermediates) and 4N metaphase plates are recovered from 52% Percoll. The latter intermediates can be further separated into highly enriched populations (greater than 94% pure) by fluorescence-activated sorting. Predecondensing structures are of the same overall morphology as prenuclei isolated previously by organic means, can also be ordered sequentially to demonstrate nuclear morphogenesis, and retain centromere/kinetochore loci. These chromosomal loci based on immunostaining of individual structures appear to be positioned centrally during chromatid reassociation and then appear to be dispersed prior to structural rearrangements leading to formation of a disc-like prenucleus.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- L D Hodge
- Department of Cell and Molecular Biology, Medical College of Georgia, Augusta 30912
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22
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Abstract
The nuclear matrix is concealed by a much larger mass of chromatin, which can be removed selectively by digesting nuclei with DNase I followed by elution of chromatin with 0.25 M ammonium sulfate. This mild procedure removes chromatin almost completely and preserves nuclear matrix morphology. The complete nuclear matrix consists of a nuclear lamina with an interior matrix composed of thick, polymorphic fibers and large masses that resemble remnant nucleoli. Further extraction of the nuclear matrices of HeLa or MCF-7 cells with 2 M sodium chloride uncovered a network of core filaments. A few dark masses remained enmeshed in the filament network and may be remnants of the nuclear matrix thick fibers and nucleoli. The highly branched core filaments had diameters of 9 and 13 nm measured relative to the intermediate filaments. They may serve as the core structure around which the matrix is constructed. The core filaments retained 70% of nuclear RNA. This RNA consisted both of ribosomal RNA precursors and of very high molecular weight hnRNA with a modal size of 20 kb. Treatment with RNase A removed the core filaments. When 2 M sodium chloride was used directly to remove chromatin after DNase I digestion without a preceding 0.25 M ammonium sulfate extraction, the core filaments were not revealed. Instead, the nuclear interior was filled with amorphous masses that may cover the filaments. This reflected a requirement for a stepwise increase in ionic strength because gradual addition of sodium chloride to a final concentration of 2 M without an 0.25 M ammonium sulfate extraction uncovered core filaments.
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Affiliation(s)
- D C He
- Department of Biology, Beijing Normal University, Peoples Republic of China
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23
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Carmo-Fonseca M, David-Ferreira JF. Interactions of intermediate filaments with cell structures. ELECTRON MICROSCOPY REVIEWS 1990; 3:115-41. [PMID: 2103336 DOI: 10.1016/0892-0354(90)90017-m] [Citation(s) in RCA: 57] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Intermediate filaments (IF) are unique components of the cytoskeleton of most eukaryotic cells. Also the nuclear lamins are now recognized to be IF-like proteins, providing the nucleus with a putative skeleton for chromatin attachment. Immunofluorescence and whole-mount electron microscopic studies reveal that IF form a cytoplasmic network that surrounds the nucleus and extends to cell surface, as 'mechanical integrators of cellular space'. It seems however unlikely that IF in the cell accomplish a merely structural role, considering the diversity of IF proteins and the complex regulation of their gene expression. In this work we primarily present electron microscopic data that points to the presence of interactions between IF and several cellular components, namely the nucleus, plasma membrane, other cytoskeletal elements, cytoplasmic organelles and ribonucleoproteins. Although the functional significance of such interactions remains to be demonstrated, assumptions like involvement of IF in information transfer or cytoskeleton-dependent control of gene expression represent attractive hypothesis for future research.
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Affiliation(s)
- M Carmo-Fonseca
- Instituto de Histologia e Embriologia, Faculdade de Medicina, Universidade de Lisboa, Portugal
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24
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25
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Lawrence JB, Singer RH, Marselle LM. Highly localized tracks of specific transcripts within interphase nuclei visualized by in situ hybridization. Cell 1989; 57:493-502. [PMID: 2541917 DOI: 10.1016/0092-8674(89)90924-0] [Citation(s) in RCA: 357] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Use of in situ hybridization optimized for fluorescent detection of nuclear RNA has revealed a striking localization of specific viral RNAs within nuclei of cells latently infected with EBV. Several hundred kb of specific transcripts is sharply restricted to a small region of the nucleus, frequently in a curvilinear "track". Detection of nuclear RNA was evidenced by hybridization without denaturation, sensitivity to RNAase, inhibition by actinomycin D, and specificity of transcribed sequences. Results indicate that RNA "tracks" extend from an internal genome into the nuclear periphery, and that RNA transport may be coupled to transcription. Localized nRNA is apparent for other viral sequences, different lymphoblastoid cell lines, nuclei prepared by two different methods, and an abundant, nonviral transfected sequence. Implications for understanding nuclear organization and the investigation of gene expression are discussed.
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Affiliation(s)
- J B Lawrence
- Department of Cell Biology, University of Massachusetts Medical School, Worcester 01655
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26
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Dufer J, Akeli MG, Jeannesson P, Desplaces A, Jardillier JC. Quantitative morphological analysis of adriamycin-resistant human K562 leukemic cells. CYTOMETRY 1989; 10:37-43. [PMID: 2917473 DOI: 10.1002/cyto.990100107] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The morphological changes associated with Adriamycin resistance in a human leukemic cell line have been investigated by image analysis. An Adriamycin-resistant subline of the human erythroleukemic K562 cell line has been established. Three sets of cells have been analysed: sensitive cells, resistant cells cultured in the continuous presence of Adriamycin, and resistant cells cultured without the drug. Image analysis shows that Adriamycin-resistant K562 cells display significant morphological changes as compared with sensitive cells, at both the nuclear and cytoplasmic levels. These changes make it possible to separate sensitive and resistant cells automatically and with a classification accuracy of 76% and only four cytological parameters. Image analysis may therefore offer an interesting tool for studying drug resistance in leukemic cells, from both an experimental and a clinical point of view.
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Affiliation(s)
- J Dufer
- Groupe d'Etude des Interactions Biologiques des Substances Anticancéreuses, Institut Jean Godinot, Reims, France
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27
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Affiliation(s)
- E M Merisko
- Drug Delivery Department, Sterling Research Group, Great Valley, Pa 19355
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28
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Nucleo-Cytoplasmic Transport of mRNA: Its Relationship to RNA Metabolism, Subcellular Structures and Other Nucleocytoplasmic Exchanges. PROGRESS IN MOLECULAR AND SUBCELLULAR BIOLOGY 1988. [DOI: 10.1007/978-3-642-73599-8_2] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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29
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Affiliation(s)
- J V Small
- Institute of Molecular Biology, Austrian Academy of Sciences, Salzburg
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30
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31
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Lachapelle M, Lafontaine JG. Observations on the ultrastructural preservation of the nucleus in the myxomycetePhysarum polycephalum as observed in resinless sections. ACTA ACUST UNITED AC 1987. [DOI: 10.1002/jemt.1060050303] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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32
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Abstract
Inorganic metals and minerals for which there is evidence of carcinogenicity are identified. The risk of cancer from contact with them in the work place, the general environment, and under conditions of clinical (medical) exposure is discussed. The evidence indicates that minerals and metals most often influence cancer development through their action as cocarcinogens. The relationship between the physical form of mineral fibers, smoking and carcinogenic risk is emphasized. Metals are categorized as established (As, Be, Cr, Ni), suspected (Cd, Pb) and possible carcinogens (Table 6), based on the existing in vitro, animal experimental and human epidemiological data. Cancer risk and possible modes of action of elements in each class are discussed. Views on mechanisms that may be responsible for the carcinogenicity of metals are updated and analysed. Some specific examples of cancer risks associated with the clinical use of potentially carcinogenic metals and from radioactive pharmaceuticals used in therapy and diagnosis are presented. Questions are raised as to the effectiveness of conventional dosimetry in accurately measuring risk from radiopharmaceuticals.
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33
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Wagner B, Krochmalnic G, Penman S. Resinless section electron microscopy of HeLa cell mitotic architecture. Proc Natl Acad Sci U S A 1986; 83:8996-9000. [PMID: 3466172 PMCID: PMC387061 DOI: 10.1073/pnas.83.23.8996] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
The use of resinless sections extends embedment-free electron microscopy to the cytoskeleton of thick specimens. Here we examine HeLa cells rounded at mitosis. Extraction of mitotic HeLa cells with Triton X-100 removes lipids and soluble proteins, leaving the cytoskeletal framework and spindle apparatus. After fixation, the samples are embedded and sectioned, and the temporary embedding resin is removed for direct visualization in the electron microscope. The micrographs show that the cytoskeletal framework, chromosomes, spindle, and centrioles form an interconnected entity. The pericentriolar region, indistinct in conventional micrographs, appears composed of distinct fibers interconnecting the spindle microtubules and centriole. The resinless sections also reveal characteristic lacunae at late anaphase/early telophase. These probably result from reformation of the interphase cytoskeleton lagging reassembly of the nucleus.
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34
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Onfelt A. Mechanistic aspects on chemical induction of spindle disturbances and abnormal chromosome numbers. Mutat Res 1986; 168:249-300. [PMID: 3540644 DOI: 10.1016/0165-1110(86)90023-0] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Work on the chemical induction of spindle disturbances and abnormal chromosome numbers, and work on the composition and biochemistry of the spindle are reviewed. Some early investigations have shown that there is an unspecific mechanism for chemical induction of spindle disturbances. This mechanism is based on the interaction of compounds with cellular hydrophobic compartments. Some compounds act differently and are more active than predicted from their lipophilic character. Selected compounds of that kind and their possible mechanisms of action are discussed. Changes in sulfhydryl and ATP levels, oxidative damage of membranes and impaired control of cytoplasmic Ca2+ levels are discussed in this context.
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35
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Capco DG, McGaughey RW. Cytoskeletal reorganization during early mammalian development: analysis using embedment-free sections. Dev Biol 1986; 115:446-58. [PMID: 3519319 DOI: 10.1016/0012-1606(86)90265-4] [Citation(s) in RCA: 59] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
We have examined cytoskeletal reorganization during early embryonic development in the hamster by employing detergent extraction to remove soluble components of the embryos and reveal the underlying structural network. This procedure allows examination of both the cortical cytoskeleton and the cytoskeleton of the egg interior. Sections of eggs and embryos were prepared for transmission electron microscopy with the removable embedding medium, diethylene glycol disterate which allows thicker sections than conventional embedment procedures thereby providing more spatial cues for studying organization. The cytoskeleton reorganizes after fertilization, at the time of compaction and again at the blastocyst stage. These cytoskeletal reorganizations are considered in terms of the blastomere polarity hypothesis and the involvement of the cytoskeleton with early embryonic development.
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36
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Steffen W, Fuge H, Dietz R, Bastmeyer M, Müller G. Aster-free spindle poles in insect spermatocytes: evidence for chromosome-induced spindle formation? J Cell Biol 1986; 102:1679-87. [PMID: 3700473 PMCID: PMC2114219 DOI: 10.1083/jcb.102.5.1679] [Citation(s) in RCA: 77] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Tipulid spermatocytes form normally functioning bipolar spindles after one of the centrosomes is experimentally dislocated from the nucleus in late diakinesis (Dietz, R., 1959, Z. Naturforsch., 14b:749-752; Dietz, R., 1963, Zool. Anz. Suppl., 23:131-138; Dietz, R., 1966, Heredity, 19:161-166). The possibility that dissociated pericentriolar material (PCM) is nevertheless responsible for the formation of the spindle in these cells cannot be ruled out based on live observation. In studying serial sections of complete cells and of lysed cells, it was found that centrosome-free spindle poles in the crane fly show neither pericentriolar-like material nor aster microtubules, whereas the displaced centrosomes appear complete, i.e., consist of a centriole pair, aster microtubules, and PCM. Exposure to a lysis buffer containing tubulin resulted in an increase of centrosomal asters due to aster microtubule polymerization. Aster-free spindle poles did not show any reaction, also indicating the absence of PCM at these poles. The results favor the hypothesis of chromosome-induced spindle pole formation at the onset of prometaphase and the dispensability of PCM in Pales.
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37
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Abstract
In this study we examined the distribution of U-snRNPs during mitosis using a monoclonal antibody which recognizes the 28 kD protein associated with U-snRNP particles. During interphase U-snRNPs are concentrated within discrete intranuclear protein clusters. The onset of mitosis is accompanied by a breakdown of these nuclear protein clusters and U-snRNPs are redistributed between the condensing chromosomes. During metaphase and anaphase, two populations of U-snRNPs can be identified: those associated with the chromosome surface and a 'free' form distributed throughout the cytoplasm. During telophase, the reformation of nuclear protein clusters appears to be associated with the chromosome surface and coincides with chromatin decondensation. These studies suggest that the interphase assembly of nuclear domains containing U-snRNPs is sensitive to the transcriptionally active or decondensed state of chromatin.
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38
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Wedrychowski A, Schmidt WN, Ward WS, Hnilica LS. Cross-linking of cytokeratins to DNA in vivo by chromium salt and cis-diamminedichloroplatinum(II). Biochemistry 1986; 25:1-9. [PMID: 2420355 DOI: 10.1021/bi00349a001] [Citation(s) in RCA: 33] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The in vivo cross-linking of cytokeratins to DNA in intact Novikoff ascites hepatoma cells exposed to the chromium salt K2CrO4 and cis-diamminedichloroplatinum(II) (cis-DDP) was studied. Cytokeratin-DNA complexes were obtained by high-speed centrifugation of cells solubilized in buffered 4% sodium dodecyl sulfate. The cytokeratins were identified electrophoretically and immunologically by use of polyclonal and monoclonal antibodies. Time dependence experiments showed that detectable cross-linking occurred after cells were exposed to K2CrO4 for at least 4 h, and the amount of keratin-DNA complexes increased with the incubation time. Each of the three Novikoff ascites hepatoma cytokeratins (p39, p49, and p56) showed a different apparent rate of cross-link formation with DNA. Cytokeratin-DNA complexes were detectable in our system only with K2CrO4 concentrations of 200 microM or greater, and saturation in cross-linking was effected at approximately 2 mM. Higher K2CrO4 concentrations (up to 5 mM) did not produce further significant increases in the amount of cross-linked cytokeratins. Chromium and cis-DDP cross-linked the same cytokeratins at approximately the same ratios; however, both agents cross-linked the major cytokeratins selectively, since not all cytokeratins present in Novikoff hepatoma cell lysates could be cross-linked to DNA. Further evidence of DNA-cytokeratin complexes was obtained by CsCl gradient centrifugation. Our results document the ability of chromate and cis-DDP to produce DNA-cytokeratin cross-links in vivo and show that in live Novikoff hepatoma cells some, but not all, of the components of intermediate filaments are within cross-linking distance of DNA.
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39
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Nakayasu H, Ueda K. Association of rapidly-labelled RNAs with actin in nuclear matrix from mouse L5178Y cells. Exp Cell Res 1985; 160:319-30. [PMID: 2412867 DOI: 10.1016/0014-4827(85)90179-x] [Citation(s) in RCA: 35] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
More than 90% of rapidly-labelled nuclear RNA was associated with a nuclear matrix prepared from mouse leukemia L5178Y cells. The binding was not affected with up to 4 M NaCl; however, these RNAs were released from the nuclear matrix by treatment with a low ionic strength buffer (5 mM Tris-HCl buffer, pH 7.5, containing 1 mM ATP, 1 mM dithiothreitol, 0.2 mM ethylenediaminetetraacetic acid (EDTA) and 0.4 mM calcium chloride), without destruction of the sphere of the nuclear matrix. Actin filaments in the nuclear matrix were depolymerized with this buffer accompanied with rapidly-labelled RNAs. When the depolymerization was inhibited by slight modifications of the low ionic strength buffer (replacement of ATP by the same concentration of GTP; replacement of calcium ion by the same concentration of magnesium ion; addition of 20 micrograms/ml of phalloidine, which is a specific inhibitor of actin depolymerization), the release of rapidly-labelled RNAs from the nuclear matrix was also inhibited. The complex containing rapidly-labelled RNAs and matrix proteins was solubilized by a sonication from the nuclear matrix, and subjected to cesium chloride equilibrium centrifugation. Rapidly-labelled RNAs were concentrated on the bottom of the gradient accompanied with a small number of proteins (68K, 60K, 43K and 40K). The 43K protein was identified as actin by immunoblotting. By RNase digestion before equilibrium centrifugation, actin in the bottom fractions disappeared. These results suggest that rapidly-labelled RNAs anchor on the actin filaments in the nuclear matrix.
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40
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Fey EG, Capco DG, Krochmalnic G, Penman S. Epithelial structure revealed by chemical dissection and unembedded electron microscopy. J Cell Biol 1984; 99:203s-208s. [PMID: 6540264 PMCID: PMC2275580 DOI: 10.1083/jcb.99.1.203s] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Cytoskeletal structures obtained after extraction of Madin-Darby canine
kidney epithelial cell monolayers with Triton X-100 were examined in
transmission electron micrographs of cell whole mounts and unembedded thick
sections. The cytoskeleton, an ordered structure consisting of a peripheral
plasma lamina, a complex network of filaments, and chromatin-containing
nuclei, was revealed after extraction of intact cells with a nearly
physiological buffer containing Triton X-100. The cytoskeleton was further
fractionated by extraction with (NH4)2SO4, which left a structure enriched
in intermediate filaments and desmosomes around the nuclei. A further
digestion with nuclease and elution with (NH4)2SO4 removed the chromatin.
The stable structure that remained after this procedure retained much of
the epithelial morphology and contained essentially all of the cytokeratin
filaments and desmosomes and the chromatin-depleted nuclear matrices. This
structural network may serve as a scaffold for epithelial organization. The
cytoskeleton and the underlying nuclear matrix intermediate filament
scaffold, when examined in both conventional embedded thin sections and in
unembedded whole mounts and thick sections, showed the retention of many of
the detailed morphological aspects of the intact cells, which suggests a
structural continuum linking the nuclear matrix, the intermediate filament
network, and the intercellular desmosomal junctions. Most importantly, the
protein composition of each of the four fractions obtained by this
sequential procedure was essentially unique. Thus, the proteins
constituting the soluble fraction, the cytoskeleton, the chromatin
fraction, and the underlying nuclear matrix-intermediate filament scaffold
are biochemically distinct.
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41
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Chaly N, Bladon T, Setterfield G, Little JE, Kaplan JG, Brown DL. Changes in distribution of nuclear matrix antigens during the mitotic cell cycle. J Biophys Biochem Cytol 1984; 99:661-71. [PMID: 6378926 PMCID: PMC2113259 DOI: 10.1083/jcb.99.2.661] [Citation(s) in RCA: 116] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
We examined the distribution of nonlamin nuclear matrix antigens during the mitotic cell cycle in mouse 3T3 fibroblasts. Four monoclonal antibodies produced against isolated nuclear matrices were used to characterize antigens by the immunoblotting of isolated nuclear matrix preparations, and were used to localize the antigens by indirect immunofluorescence. For comparison, lamins and histones were localized using human autoimmune antibodies. At interphase, the monoclonal antibodies recognized non-nucleolar and nonheterochromatin nuclear components. Antibody P1 stained the nuclear periphery homogeneously, with some small invaginations toward the interior of the nucleus. Antibody I1 detected an antigen distributed as fine granules throughout the nuclear interior. Monoclonals PI1 and PI2 stained both the nuclear periphery and interior, with some characteristic differences. During mitosis, P1 and I1 were chromosome-associated, whereas PI1 and PI2 dispersed in the cytoplasm. Antibody P1 heavily stained the periphery of the chromosome mass, and we suggest that the antigen may play a role in maintaining interphase and mitotic chromosome order. With antibody I1, bright granules were distributed along the chromosomes and there was also some diffuse internal staining. The antigen to I1 may be involved in chromatin/chromosome higher-order organization throughout the cell cycle. Antibodies PI1 and PI2 were redistributed independently during prophase, and dispersed into the cytoplasm during prometaphase. Antibody PI2 also detected antigen associated with the spindle poles.
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42
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Capco DG, Krochmalnic G, Penman S. A new method of preparing embeddment-free sections for transmission electron microscopy: applications to the cytoskeletal framework and other three-dimensional networks. J Biophys Biochem Cytol 1984; 98:1878-85. [PMID: 6539336 PMCID: PMC2113197 DOI: 10.1083/jcb.98.5.1878] [Citation(s) in RCA: 89] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Diethylene glycol distearate is used as a removable embedding medium to produce embeddment -free sections for transmission electron microscopy. The easily cut sections of this material float and form ribbons in a water-filled knife trough and exhibit interference colors that aid in the selection of sections of equal thickness. The images obtained with embeddment -free sections are compared with those from the more conventional epoxy-embedded sections, and illustrate that embedding medium can obscure important biological structures, especially protein filament networks. The embeddment -free section methodology is well suited for morphological studies of cytoskeletal preparations obtained by extraction of cells with nonionic detergent in cytoskeletal stabilizing medium. The embeddment -free section also serves to bridge the very different images afforded by embedded sections and unembedded whole mounts.
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43
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Ward WS, Schmidt WN, Schmidt CA, Hnilica LS. Association of cytokeratin p39 with DNA in intact Novikoff hepatoma cells. Proc Natl Acad Sci U S A 1984; 81:419-23. [PMID: 6198648 PMCID: PMC344688 DOI: 10.1073/pnas.81.2.419] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
The relationship between the rat tumor-associated cytokeratin p39 (Mr 39,000) and cellular DNA has been studied in intact cells. Using a DNA-protein crosslinking technique, incubation with cis-dichlorodiammineplatinum, we present evidence for the association of p39 with DNA in intact Novikoff ascites hepatoma cells. The cells were treated with cis-dichlorodiammineplatinum and solubilized in NaDodSO4-containing buffer, and the DNA was pelleted by high-speed centrifugation. By immunotransfer analysis, the cytokeratin was found in the DNA pellet of the crosslinked samples while absent from the controls. This result was further substantiated by CsCl density-gradient centrifugation. Collectively, these results suggest a cytokeratin-DNA association at the filament binding sites on or near the nuclear lamina.
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44
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Tew KD, Moy BC, Hartley-Asp B. Acquired drug resistance is accompanied by modification in the karyotype and nuclear matrix of a rat carcinoma cell line. Exp Cell Res 1983; 149:443-50. [PMID: 6641811 DOI: 10.1016/0014-4827(83)90356-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
A Walker 256 breast carcinoma cell line (WR) exhibiting a greater than 20-fold resistance to alkylating agents has been selected from a parent cell line (WS). Karyotypic heterogeneity was apparent, with a number of differences evident between WR and WS cells. The modal chromosome number for WS is 62; for WR, 54; double minutes were found only in WR, whereas spontaneous chromosomal aberrations were present in approx. 40% of the WS cells. No similar aberrations were observed in WR. Using SDS-gel electrophoresis and subsequent silver staining, differences in the profile of nuclear matrix proteins in WR and WS were observed. A diffuse band at approx. 70 kD in the WS was absent in WR cells. This protein was phosphorylated, together with a number of the other major matrix polypeptides. Levels of phosphorylated matrix proteins were approximately equivalent in both WR and WS cell lines, but matrix protein phosphorylation levels were approx. 2-fold higher than corresponding values for bulk nuclear proteins. Selective pressure of drug exposure has resulted in enhanced genetic stability in WR cells and observed karyotype differences are accompanied by modifications in the structural proteins of the nuclear matrix. Whether the observed differences are the cause or result of drug resistance remains to be established.
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