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Vinaiphat A, Charngkaew K, Thongboonkerd V. More complete polarization of renal tubular epithelial cells by artificial urine. Cell Death Discov 2018; 4:47. [PMID: 30323952 PMCID: PMC6180081 DOI: 10.1038/s41420-018-0112-z] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2018] [Revised: 08/30/2018] [Accepted: 09/26/2018] [Indexed: 02/06/2023] Open
Abstract
Cell polarization using Transwell is a common method employed to study renal tubular epithelial cells. However, this conventional protocol does not precisely recapitulate renal tubular epithelial cell phenotypes. In this study, we simulated renal physiological microenvironment by replacing serum-containing culture medium in upper chamber of the Transwell with physiologic artificial urine (AU) (to mimic renal tubular fluid), whereas the lower chamber still contained serum-containing medium (to mimic plasma-enriched renal interstitium). Comparing to the conventional protocol (control), the AU-assisted protocol offered more complete polarization of MDCK renal tubular cells as indicated by higher transepithelial electrical resistance (TER) and greater levels of tight junction (TJ) proteins (ZO-1 and occludin). Transmission electron microscopy (TEM) showed greater densities of TJ and desmosome, narrower intercellular spaces, greater cell height, and longer microvilli in the AU-treated cells. Secretome analysis revealed that the AU-treated cells secreted greater proportion of the proteins matched to normal human urinary proteome via both classical and non-classical secretory pathways. Finally, modifying/omitting each component of AU (one at a time) followed by validation revealed that urea was responsible for such property of AU to improve cell polarization. These data indicate that replacing AU on the upper chamber of Transwell can improve or optimize renal cell polarization for more precise investigations of renal physiology and cell biology in vitro.
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Affiliation(s)
- Arada Vinaiphat
- 1Medical Proteomics Unit, Office for Research and Development, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand.,2Graduate Program in Immunology, Department of Immunology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - Komgrid Charngkaew
- 3Department of Pathology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - Visith Thongboonkerd
- 1Medical Proteomics Unit, Office for Research and Development, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand.,4Center for Research in Complex Systems Science, Mahidol University, Bangkok, Thailand
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2
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Huen AC, Marathi A, Nam PK, Wells A. CXCL11 Expression by Keratinocytes Occurs Transiently Between Reaching Confluence and Cellular Compaction. Adv Wound Care (New Rochelle) 2016; 5:517-526. [PMID: 28078185 DOI: 10.1089/wound.2015.0680] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2015] [Accepted: 02/01/2016] [Indexed: 12/31/2022] Open
Abstract
Objective: To investigate whether differentiation or cellular confluence is responsible for CXCL11 expression patterns in re-epithelialization. Approach:In vitro model systems of re-epithelialization using the HaCaT keratinocyte cell line were utilized in monitoring expression of differentiation markers, including desmoplakin and various cytokeratins while evaluating for an association with chemokine CXCL11 expression. Results: CXCL11 expression was elevated in sparse culture with peak expression near the time of confluence. This somewhat followed the accumulation of desmoplakin in detergent-insoluble pool of proteins. However, in postconfluent, despite continued accumulation of desmoplakin within cells, CXCL11 expression decreased to baseline levels. This biphasic pattern was also seen in low calcium culture, an environment that inhibits keratinocyte differentiation and accumulation of desmosomal proteins. Highest CXCL11-expressing areas best correlated with newly confluent areas within culture expressing basal keratin 14, but also activated keratin 6. Innovation: Achievement of a threshold cellular density induces cell signaling cascade through CXCR3 that, in addition to other undiscovered pathways, can progress cutaneous wounds from the proliferative into the remodeling phases of cutaneous wound healing. Conclusion: These results suggest that the achievement of confluence with increased cellular density by migrating keratinocytes at the wound edge triggers expression of CXCL11. Since CXCR3 stimulation in endothelial cells results in apoptosis and causes neovascular pruning, whereas stimulation of CXCR3 in fibroblasts results decreased motility and cellular contraction, we speculate that CXCL11 expression by epidermal cells upon achieving cellular confluence could be the source of CXCR3 stimulation in the dermis ushering a transition from proliferative to remodeling phases of wound healing.
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Affiliation(s)
- Arthur C. Huen
- Department of Dermatology, McGowan Institute for Regenerative Medicine, VA Pittsburgh Health System, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Archana Marathi
- Department of Dermatology, McGowan Institute for Regenerative Medicine, VA Pittsburgh Health System, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Peter K. Nam
- Department of Dermatology, McGowan Institute for Regenerative Medicine, VA Pittsburgh Health System, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Alan Wells
- Department of Pathology, McGowan Institute for Regenerative Medicine, VA Pittsburgh Health System, University of Pittsburgh, Pittsburgh, Pennsylvania
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3
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Imbalzano KM, Cohet N, Wu Q, Underwood JM, Imbalzano AN, Nickerson JA. Nuclear shape changes are induced by knockdown of the SWI/SNF ATPase BRG1 and are independent of cytoskeletal connections. PLoS One 2013; 8:e55628. [PMID: 23405182 PMCID: PMC3566038 DOI: 10.1371/journal.pone.0055628] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2012] [Accepted: 01/02/2013] [Indexed: 11/24/2022] Open
Abstract
Changes in nuclear morphology occur during normal development and have been observed during the progression of several diseases. The shape of a nucleus is governed by the balance of forces exerted by nuclear-cytoskeletal contacts and internal forces created by the structure of the chromatin and nuclear envelope. However, factors that regulate the balance of these forces and determine nuclear shape are poorly understood. The SWI/SNF chromatin remodeling enzyme ATPase, BRG1, has been shown to contribute to the regulation of overall cell size and shape. Here we document that immortalized mammary epithelial cells show BRG1-dependent nuclear shape changes. Specifically, knockdown of BRG1 induced grooves in the nuclear periphery that could be documented by cytological and ultrastructural methods. To test the hypothesis that the observed changes in nuclear morphology resulted from altered tension exerted by the cytoskeleton, we disrupted the major cytoskeletal networks and quantified the frequency of BRG1-dependent changes in nuclear morphology. The results demonstrated that disruption of cytoskeletal networks did not change the frequency of BRG1-induced nuclear shape changes. These findings suggest that BRG1 mediates control of nuclear shape by internal nuclear mechanisms that likely control chromatin dynamics.
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Affiliation(s)
- Karen M Imbalzano
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
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4
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Fukasawa H, Obayashi H, Schmieder S, Lee J, Ghosh P, Farquhar MG. Phosphorylation of podocalyxin (Ser415) Prevents RhoA and ezrin activation and disrupts its interaction with the actin cytoskeleton. THE AMERICAN JOURNAL OF PATHOLOGY 2011; 179:2254-65. [PMID: 21945805 DOI: 10.1016/j.ajpath.2011.07.046] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2011] [Accepted: 07/12/2011] [Indexed: 01/01/2023]
Abstract
Podocalyxin (PC) is a polysialylated, anti-adhesin that is essential for maintaining foot process architecture and the integrity of the glomerular filtration barrier. We showed previously that PC is firmly attached to the actin cytoskeleton through ezrin, that in puromycin aminonucleoside (PAN)-mediated nephrosis the PC-ezrin-actin complex is disrupted, and that PC is uncoupled from actin. However, the precise mechanisms involved remained unknown. Here we show that detachment of PC from actin is regulated by phosphorylation of PC. PC is hyperphosphorylated at serines in PAN- and protamine sulfate (PS)-treated rat glomeruli. We determined that PC is a substrate of PKC and that the site of phosphorylation is Ser415, located within the juxtamembrane, ezrin-binding domain of the cytoplasmic tail of PC. Mutation of Ser415 to the phosphomimetic residues Glu (S415E) or Asp (S415D) interfered with direct binding of the PC cytoplasmic tail to ezrin in vitro. Moreover, stable expression of a phosphomimetic (S415E) PC mutant but not the WT or the phosphorylation-deficient (S415A) PC mutant, disrupted PC-ezrin-actin interaction, failed to activate RhoA, and the cytoskeletal linker, ezrin, remained inactive. Our data indicate that phosphorylation of PC at Ser415 prevents attachment of PC and ezrin to actin and highlights the strategic position of Ser415 and direct binding of PC to ezrin in regulating podocyte foot process architecture.
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Affiliation(s)
- Hirotaka Fukasawa
- Department of Medicine, Hamamatsu University School of Medicine, Japan
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5
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Wang Y, Azuma Y, Friedman DB, Coffey RJ, Neufeld KL. Novel association of APC with intermediate filaments identified using a new versatile APC antibody. BMC Cell Biol 2009; 10:75. [PMID: 19845967 PMCID: PMC2774295 DOI: 10.1186/1471-2121-10-75] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2009] [Accepted: 10/21/2009] [Indexed: 12/28/2022] Open
Abstract
BACKGROUND As a key player in suppression of colon tumorigenesis, Adenomatous Polyposis Coli (APC) has been widely studied to determine its cellular functions. However, inconsistencies of commercially available APC antibodies have limited the exploration of APC function. APC is implicated in spindle formation by direct interactions with tubulin and microtubule-binding protein EB1. APC also interacts with the actin cytoskeleton to regulate cell polarity. Until now, interaction of APC with the third cytoskeletal element, intermediate filaments, has remained unexamined. RESULTS We generated an APC antibody (APC-M2 pAb) raised against the 15 amino acid repeat region, and verified its reliability in applications including immunoprecipitation, immunoblotting, and immunofluorescence in cultured cells and tissue. Utilizing this APC-M2 pAb, we immunoprecipitated endogenous APC and its binding proteins from colon epithelial cells expressing wild-type APC. Using Liquid Chromatography Tandem Mass Spectrometry (LC-MS/MS), we identified 42 proteins in complex with APC, including beta-catenin and intermediate filament (IF) proteins lamin B1 and keratin 81. Association of lamin B1 with APC in cultured cells and human colonic tissue was verified by co-immunoprecipitation and colocalization. APC also colocalized with keratins and remained associated with IF proteins throughout a sequential extraction procedure. CONCLUSION We introduce a versatile APC antibody that is useful for cell/tissue immunostaining, immunoblotting and immunoprecipitation. We also present evidence for interactions between APC and IFs, independent of actin filaments and microtubules. Our results suggest that APC associates with all three major components of the cytoskeleton, thus expanding potential roles for APC in the regulation of cytoskeletal integrity.
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Affiliation(s)
- Yang Wang
- Department of Molecular Biosciences, University of Kansas, Lawrence, KS, USA
| | - Yoshiaki Azuma
- Department of Molecular Biosciences, University of Kansas, Lawrence, KS, USA
| | - David B Friedman
- Mass Spectrometry Research Center, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Robert J Coffey
- Departments of Cell and Developmental Biology and Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Kristi L Neufeld
- Department of Molecular Biosciences, University of Kansas, Lawrence, KS, USA
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6
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Spencer VA, Xu R, Bissell MJ. Extracellular matrix, nuclear and chromatin structure, and gene expression in normal tissues and malignant tumors: a work in progress. Adv Cancer Res 2009; 97:275-94. [PMID: 17419950 PMCID: PMC2912285 DOI: 10.1016/s0065-230x(06)97012-2] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Almost three decades ago, we presented a model where the extracellular matrix (ECM) was postulated to influence gene expression and tissue-specificity through the action of ECM receptors and the cytoskeleton. This hypothesis implied that ECM molecules could signal to the nucleus and that the unit of function in higher organisms was not the cell alone, but the cell plus its microenvironment. We now know that ECM invokes changes in tissue and organ architecture and that tissue, cell, nuclear, and chromatin structure are changed profoundly as a result of and during malignant progression. Whereas some evidence has been generated for a link between ECM-induced alterations in tissue architecture and changes in both nuclear and chromatin organization, the manner by which these changes actively induce or repress gene expression in normal and malignant cells is a topic in need of further attention. Here, we will discuss some key findings that may provide insights into mechanisms through which ECM could influence gene transcription and how tumor cells acquire the ability to overcome these levels of control.
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Affiliation(s)
- Virginia A Spencer
- Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
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7
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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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8
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Zhao CH, Li QF. Altered profiles of nuclear matrix proteins during the differentiation of human gastric mucous adenocarcinoma MGc80-3 cells. World J Gastroenterol 2005; 11:4628-33. [PMID: 16094700 PMCID: PMC4615401 DOI: 10.3748/wjg.v11.i30.4628] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
AIM: To find and identify specific nuclear matrix proteins associated with proliferation and differentiation of carcinoma cells, which will be potential markers for cancer diagnosis and targets in cancer therapy.
METHODS: Nuclear matrix proteins were selectively extracted from MGc80-3 cells treated with or without hexamethylamine bisacetamide (HMBA), and subjected to 2-D gel electrophoresis. The resulted protein patterns were analyzed by Melanie software. Spots of nuclear matrix proteins differentially expressed were excised and subjected to in situ digestion with trypsin. Peptide masses were obtained by matrix-assisted laser-desorption/ ionization time of flight mass spectrometry (MALDI-TOF-MS) analysis and submitted for database searching using Mascot tool.
RESULTS: The MGc80-3 cells were induced into differentiation by HMBA. There were 22 protein spots which changed remarkably in the nuclear matrix, from differentiation of MGc80-3 cells compared to control. Eleven of which were identified. Seven proteins - actin, prohibitin, porin 31HL, heterogeneous nuclear ribonucleoprotein A2/B1, vimentin, ATP synthase, and heat shock protein 60 were downregulated, whereas three proteins - heat shock protein gp96, heat shock protein 90-beta, and valosin-containing protein were upregulated, and the oxygen-regulated protein was only found in the differentiated MGc80-3 cells.
CONCLUSION: The induced differentiation of carcinoma cells is accompanied by the changes of nuclear matrix proteins. Further characterization of those proteins will show the mechanism of cellular proliferation and differentiation, as well as cancer differentiation.
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Affiliation(s)
- Chun-Hong Zhao
- Laboratory of Cell Biology, School of Life Sciences, Xiamen University, Fujian Province, China
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9
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Markova MD. Electron microscopic observations of human sperm whole-mounts after extraction for nuclear matrix and intermediate filaments (NM-IF). ACTA ACUST UNITED AC 2004; 27:291-5. [PMID: 15379969 DOI: 10.1111/j.1365-2605.2004.00479.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The extraction for nuclear matrix and intermediate filaments (NM-IF) is used to reveal, isolate and study these highly resistant structures in different cell types. We applied for the first time this chemical dissection to human spermatozoa and observed them as whole-mounts by unembedded electron microscopy. The general appearance of NM-IF extracted sperm cells was preserved, showing the intermediate filament-like properties of their cytoskeletal components. In most heads, a network was observed in subacrosomal position, consisting of hubs interconnected by filaments. It seemed to be overlaid on another, finer network. The neck retained its integrity, allowing observations of the three-dimensional structure of the segmented columns. More distally, axoneme and outer dense fibres were covered by submitochondrial cytoskeleton in the middle piece and fibrous sheath in the principal piece, with the annulus usually detached from the fibrous sheath. End piece microtubules were retained in most cells and showed a tendency of cohesion, remaining in a parallel bundle or forming flat sheets. In conclusion, our results provided additional structural details of human sperm cytoskeleton and demonstrated the advantages of combining different methodological approaches in ultrastructural research.
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Affiliation(s)
- Maya Dyankova Markova
- Department of Biology, Medical Faculty, Medical University of Sofia, Sofia, Bulgaria.
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10
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Michishita E, Kurahashi T, Suzuki T, Fukuda M, Fujii M, Hirano H, Ayusawa D. Changes in nuclear matrix proteins during the senescence-like phenomenon induced by 5-chlorodeoxyuridine in HeLa cells. Exp Gerontol 2002; 37:885-90. [PMID: 12086696 DOI: 10.1016/s0531-5565(02)00033-5] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
5-Chlorodeoxyuridine (CldU) immediately induces a senescence-like phenomenon in any type of mammalian cells probably due to a change in nuclear matrix structure. We thus examined nuclear matrix proteins in HeLa cells cultured with CldU by high-resolution two-dimensional gel electrophoresis and peptide mass spectrometry. Three proteins were found to be down-regulated and one protein up-regulated by addition of CldU. In addition, one acidic protein accumulated in the nuclear matrix, although not quantitatively changed in the nuclei. Since these alterations were observed within 24h after addition of CldU, these proteins may be involved in an early step of the senescence-like phenomenon.
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Affiliation(s)
- Eriko Michishita
- Division of Biochemistry, Kihara Institute for Biological Research and Graduate School of Integrated Science, Yokohama City University, Maioka-cho 641-12, Japan
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Takeda T, McQuistan T, Orlando RA, Farquhar MG. Loss of glomerular foot processes is associated with uncoupling of podocalyxin from the actin cytoskeleton. J Clin Invest 2001; 108:289-301. [PMID: 11457882 PMCID: PMC203027 DOI: 10.1172/jci12539] [Citation(s) in RCA: 187] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Podocalyxin (PC), the major sialoprotein of glomerular epithelial cells (GECs), helps maintain the characteristic architecture of the foot processes and the patency of the filtration slits. PC associates with actin via ezrin, a member of the ERM family of cytoskeletal linker proteins. Here we show that PC is linked to ezrin and the actin cytoskeleton via Na(+)/H(+)-exchanger regulatory factor 2 (NHERF2), a scaffold protein containing two PDZ (PSD-95/Dlg/ZO-1) domains and an ERM-binding region. The cytoplasmic tail of PC contains a C-terminal PDZ-binding motif (DTHL) that binds to the second PDZ domain of NHERF2 in yeast two-hybrid and in vitro pull-down assays. By immunocytochemistry NHERF2 colocalizes with PC and ezrin along the apical domain of the GEC plasma membrane. NHERF2 and ezrin form a multimeric complex with PC, as they coimmunoprecipitate with PC. The PC/NHERF2/ezrin complex interacts with the actin cytoskeleton, and this interaction is disrupted in GECs from puromycin aminonucleoside-, protamine sulfate-, or sialidase-treated rats, which show a dramatic loss of foot processes, comparable to that seen in the nephrotic syndrome. Thus NHERF2 appears to function as a scaffold protein linking PC to ezrin and the actin cytoskeleton. PC/NHERF2/ezrin/actin interactions are disrupted in pathologic conditions associated with changes in GEC foot processes, indicating their importance for maintaining the unique organization of this epithelium.
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Affiliation(s)
- T Takeda
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, California, USA
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12
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Ingber DE. Opposing views on tensegrity as a structural framework for understanding cell mechanics. J Appl Physiol (1985) 2000; 89:1663-70. [PMID: 11007610 DOI: 10.1152/jappl.2000.89.4.1663] [Citation(s) in RCA: 112] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Affiliation(s)
- D E Ingber
- Departments of Pathology and Surgery, Children's Hospital and Harvard Medical School, Boston, Massachusetts 02115, USA
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13
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Abstract
The three-dimensional intracellular network formed by the filamentous polymers comprising the cytoskeletal affects the way cells sense their extracellular environment and respond to stimuli. Because the cytoskeleton is viscoelastic, it provides a continuous mechanical coupling throughout the cell that changes as the cytoskeleton remodels. Such mechanical effects, based on network formation, can influence ion channel activity at the plasma membrane of cells and may conduct mechanical stresses from the cell membrane to internal organelles. As a result, both rapid responses such as changes in intracellular Ca2+ and slower responses such as gene transcription or the onset of apoptosis can be elicited or modulated by mechanical perturbations. In addition to mechanical features, the cytoskeleton also provides a large negatively charged surface on which many signaling molecules including protein and lipid kinases, phospholipases, and GTPases localize in response to activation of specific transmembrane receptors. The resulting spatial localization and concomitant change in enzymatic activity can alter the magnitude and limit the range of intracellular signaling events.
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Affiliation(s)
- P A Janmey
- Experimental Medicine Division, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
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14
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Hamakawa H, Bao Y, Takarada M, Fukuzumi M, Tanioka H. Cytokeratin expression in squamous cell carcinoma of the lung and oral cavity: an immunohistochemical study with possible clinical relevance. ORAL SURGERY, ORAL MEDICINE, ORAL PATHOLOGY, ORAL RADIOLOGY, AND ENDODONTICS 1998; 85:438-43. [PMID: 9574953 DOI: 10.1016/s1079-2104(98)90070-1] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
OBJECTIVE Serologic identification of the fragment of cytokeratin 19 known as CYFRA 21-1 has been used for early detection of squamous cell carcinoma of the lung. The sensitivity of the CYFRA 21-1 assay in detecting oral cancers is lower than that in detecting lung cancers. To clarify the reason for this, we compared the cytokeratin expression in these cancers, with special reference to cytokeratin 19. STUDY DESIGN Oral squamous cell carcinomas and lung squamous cell carcinomas were immunostained with cytokeratin 19, cytokeratin 10, and cytokeratin 13 antibodies. Staining intensity was scored on a graduated scale from 0 to 4. RESULTS With respect to cytokeratin 19, the stainings of all lung cancers were scored as 4, which indicates a greater expression of cytokeratin 19 than is seen in oral cancers (p < 0.01). With an average cytokeratin 19 staining score of 1.67, oral cancers ranked lowest among the antibodies. Squamous cell carcinomas of the maxillary sinus arising from pseudostratified ciliated epithelium were highly expressive of cytokeratin 19. A marker for keratinizing cells (cytokeratin 10) and a marker for squamous cells (cytokeratin 13) were expressed more frequently and intensely in oral cancers (p < 0.01) than in lung cancers (p = 0.019). CONCLUSIONS From the viewpoint of immunohistochemistry, cytokeratin 19 was found to be a tumor marker with low specificity and sensitivity in oral cancers. The staining results suggested that poor expression of cytokeratin 19 by oral squamous cell carcinoma may result in a low serum value of CYFRA 21-1 in patients with this condition.
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Affiliation(s)
- H Hamakawa
- Department of Oral and Maxillofacial Surgery, Ehime University School of Medicine, Japan
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15
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16
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Satir P. Cilia and Related Microtubular Arrays in the Eukaryotic Cell. Compr Physiol 1997. [DOI: 10.1002/cphy.cp140120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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17
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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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18
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Stein GS, Stein JL, Lian JB, van Wijnen AJ, Montecino M. Functional interrelationships between nuclear structure and transcriptional control: Contributions to regulation of cell cycle-and tissue-specific gene expression. J Cell Biochem 1996. [DOI: 10.1002/(sici)1097-4644(199608)62:2<198::aid-jcb8>3.0.co;2-n] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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19
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Stein GS, Stein JL, Lian JB, van Wijnen AJ, Montecino M. Functional interrelationships between nuclear structure and transcriptional control: contributions to regulation of cell cycle- and tissue-specific gene expression. J Cell Biochem 1996; 62:198-209. [PMID: 8844400 DOI: 10.1002/(sici)1097-4644(199608)62:2%3c198::aid-jcb8%3e3.0.co;2-n] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Multiple levels of nuclear structure contribute to functional interrelationships with transcriptional control in vivo. The linear organization of gene regulatory sequences is necessary but insufficient to accommodate the requirements for physiological responsiveness to homeostatic, developmental, and tissue-related signals. Chromatin structure, nucleosome organization, and gene-nuclear matrix interactions provide a basis for rendering sequences accessible to transcription factors supporting integration of activities at independent promoter elements of cell cycle- and tissue-specific genes. A model is presented for remodeling of nuclear organization to accommodate developmental transcriptional control.
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Affiliation(s)
- G S Stein
- Department of Cell Biology, University of Massachusetts Medical Center, Worcester 01655, USA
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20
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Odgren PR, Harvie LW, Fey EG. Phylogenetic occurrence of coiled coil proteins: implications for tissue structure in metazoa via a coiled coil tissue matrix. Proteins 1996; 24:467-84. [PMID: 9162947 DOI: 10.1002/(sici)1097-0134(199604)24:4<467::aid-prot6>3.0.co;2-b] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
We examined GenBank sequence files with a heptad repeat analysis program to assess the phylogenetic occurrence of coiled coil proteins, how heptad repeat domains are organized within them, and what structural/functional categories they comprise. Of 102,007 proteins analyzed, 5.95% (6,074) contained coiled coil domains; 1.26% (1,289) contained "extended" (> 75 amino acid) domains. While the frequency of proteins containing coiled coils was surprisingly constant among all biota, extended coiled coil proteins were fourfold more frequent in the animal kingdom and may reflect early events in the divergence of plants and animals. Structure/function categories of extended coils also revealed phylogenetic differences. In pathogens and parasites, many extended coiled coil proteins are external and bind host proteins. In animals, the majority of extended coiled coil proteins were identified as constituents of two protein categories: 1) myosins and motors; or 2) components of the nuclear matrix-intermediate filament scaffold. This scaffold, produced by sequential extraction of epithelial monolayers in situ, contains only 1-2% of the cell mass while accurately retaining morphological features of living epithelium and is greatly enriched in proteins with extensive, interrupted coiled coil forming domains. The increased occurrence of this type of protein in metazoa compared with plants or protists leads us to hypothesize a tissue-wide matrix of coiled coil interactions underlying metazoan differentiated cell and tissue structure.
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Affiliation(s)
- P R Odgren
- Department of Cell Biology, University of Massachusetts Medical Center, Worcester 01655, USA
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Pöhler D, Butt E, Meissner J, Müller S, Lohse M, Walter U, Lohmann SM, Jarchau T. Expression, purification, and characterization of the cGMP-dependent protein kinases I beta and II using the baculovirus system. FEBS Lett 1995; 374:419-25. [PMID: 7589584 DOI: 10.1016/0014-5793(95)01168-e] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Detailed studies of differences in distinct cGMP kinase isoforms are highly dependent on expression of large amounts of these enzyme isoforms that are not easily purified by conventional methods. Here cGMP-dependent protein kinases, the type I beta soluble form from human placenta, and the type II membrane-associated form from rat intestine, were each expressed in a baculovirus/Sf9 cell system and purified in milligram amounts by affinity chromatography. The expressed recombinant proteins displayed characteristics like those of their native counterparts. cGK I beta was expressed as a 76 kDa protein predominantly found in the cytosol fraction, whereas cGK II was expressed as an 86 kDa protein predominantly associated with the membrane fraction. The apparent Ka and Vmax of cGMP for activation of cGK I beta were 0.5 microM and 3.4 mumol/min/mg, and for cGK II were 0.04 microM and 1.8 mumol/min/mg.
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Affiliation(s)
- D Pöhler
- Medizinische Universitätsklinik, Labor für Klinische Biochemie, Würzburg, Germany
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22
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Stein GS, van Wijnen AJ, Stein JL, Lian JB, Bidwell JP, Montecino M. Nuclear architecture supports integration of physiological regulatory signals for transcription of cell growth and tissue-specific genes during osteoblast differentiation. J Cell Biochem 1994; 55:4-15. [PMID: 8083299 DOI: 10.1002/jcb.240550103] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
During the past several years it has become increasingly evident that the three-dimensional organization of the nucleus plays a critical role in transcriptional control. The principal theme of this prospect will be the contribution of nuclear structure to the regulation of gene expression as functionally related to development and maintenance of the osteoblast phenotype during establishment of bone tissue-like organization. The contributions of nuclear structure as it regulates and is regulated by the progressive developmental expression of cell growth and bone cell related genes will be examined. We will consider signalling mechanisms that integrate the complex and interdependent responsiveness to physiological mediators of osteoblast proliferation and differentiation. The focus will be on the involvement of the nuclear matrix, chromatin structure, and nucleosome organization in transcriptional control of cell growth and bone cell related genes. Findings are presented which are consistent with involvement of nuclear structure in gene regulatory mechanisms which support osteoblast differentiation by addressing four principal questions: 1) Does the representation of nuclear matrix proteins reflect the developmental stage-specific requirements for modifications in transcription during osteoblast differentiation? 2) Are developmental stage-specific transcription factors components of nuclear matrix proteins? 3) Can the nuclear matrix facilitate interrelationships between physiological regulatory signals that control transcription and the integration of activities of multiple promoter regulatory elements? 4) Are alterations in gene expression and cell phenotypic properties in transformed osteoblasts and osteosarcoma cells reflected by modifications in nuclear matrix proteins? There is a striking representation of nuclear matrix proteins unique to cells, tissues as well as developmental stages of differentiation, and tissue organization. Together with selective association of regulatory molecules with the nuclear matrix in a growth and differentiation-specific manner, there is a potential for application of nuclear matrix proteins in tumor diagnosis, assessment of tumor progression, and prognosis of therapies where properties of the transformed state of cells is modified. It is realistic to consider the utilization of nuclear matrix proteins for targeting regions of cell nuclei and specific genomic domains on the basis of developmental phenotypic properties or tissue pathology.
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Affiliation(s)
- G S Stein
- Department of Cell Biology, University of Massachusetts Medical Center, Worcester 01655
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Bidwell JP, van Wijnen AJ, Fey EG, Merriman H, Penman S, Stein JL, Stein GS, Lian JB. Subnuclear distribution of the vitamin D receptor. J Cell Biochem 1994; 54:494-500. [PMID: 8014199 DOI: 10.1002/jcb.240540417] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The subnuclear distribution of the vitamin D receptor was investigated to begin addressing the contribution of nuclear architecture to vitamin D-responsive control of gene expression in ROS 17/2.8 rat osteosarcoma cells. The nuclear matrix is an anastomosing network of filaments that is functionally associated with DNA replication, transcription, and RNA processing. The representation of vitamin D receptor in the nuclear matrix and nonmatrix nuclear fractions was determined by the combined application of 1) sequence-specific interactions with the vitamin D receptor binding element of the rat bone-specific osteocalcin gene promoter and 2) Western blot analysis. Both methods confirmed the presence of vitamin D receptor in the nonmatrix nuclear fraction and the absence of detectable vitamin D receptors associated with the nuclear matrix. In contrast, these same nuclear matrix proteins preparations exhibited association with the general transcription factor AP-1 and a bone tissue-specific promoter binding factor NMP2. NMP-2 exhibits recognition for a promoter domain contiguous to the vitamin D-responsive element of the osteocalcin gene, although the vitamin D receptor does not appear to be a component of the nuclear matrix proteins. Interrelationships between nuclear matrix proteins and nonmatrix nuclear proteins, in mediating steroid hormone responsiveness of a vitamin D-regulated promoter, are therefore suggested.
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Affiliation(s)
- J P Bidwell
- Department of Cell Biology, University of Massachusetts, Worcester 01655
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Bidwell JP, Van Wijnen AJ, Fey EG, Dworetzky S, Penman S, Stein JL, Lian JB, Stein GS. Osteocalcin gene promoter-binding factors are tissue-specific nuclear matrix components. Proc Natl Acad Sci U S A 1993; 90:3162-6. [PMID: 8475055 PMCID: PMC46259 DOI: 10.1073/pnas.90.8.3162] [Citation(s) in RCA: 131] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
The nuclear matrix appears to play an important role in developmental gene expression during osteoblast differentiation. To better understand this role, we examined nuclear matrix DNA-binding proteins that are sequence-specific and interact with the osteocalcin gene promoter. Multiple protein-DNA interactions involving two distinct nuclear matrix proteins occur within the 5' regulatory sequences (nt -640 to -430). One of these proteins, NMP-1, is a ubiquitous, cell growth-regulated protein that is related to the transcription factor ATF and resides in both the nuclear matrix and the nonmatrix nuclear compartment. The other protein, NMP-2, is a cell type-specific, 38-kDa promoter factor that recognizes binding sites resembling the consensus site for the CCAAT/enhancer-binding protein C/EBP and is localized exclusively on the nuclear matrix. NMP-1 and NMP-2 each interact with two nuclear matrix protein-binding elements. These elements are present near key regulatory sites of the osteocalcin gene promoter, such as the principal steroid hormone (vitamin D)-responsive sequences. Binding in this region of the osteocalcin gene promoter suggests transient associations with the nuclear matrix that are distinct from the stable interactions of matrix attachment regions. Our results are consistent with involvement of the nuclear matrix in concentrating and/or localizing transcription factors that mediate the basal and steroid hormone responsiveness of osteocalcin gene transcription.
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Affiliation(s)
- J P Bidwell
- Department of Cell Biology, University of Massachusetts Medical Center, Worcester 01655
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Skalli O, Goldman RD. Recent insights into the assembly, dynamics, and function of intermediate filament networks. CELL MOTILITY AND THE CYTOSKELETON 1991; 19:67-79. [PMID: 1878980 DOI: 10.1002/cm.970190202] [Citation(s) in RCA: 126] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- O Skalli
- Department of Cell, Molecular, and Structural Biology, Northwestern University Medical School, Chicago, IL 60611
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26
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Zambetti G, Wilming L, Fey EG, Penman S, Stein J, Stein G. Differential association of membrane-bound and non-membrane-bound polysomes with the cytoskeleton. Exp Cell Res 1990; 191:246-55. [PMID: 2257879 DOI: 10.1016/0014-4827(90)90011-x] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
We report here a differential release of specific mRNAs from the cytoskeleton by cytochalasin D treatment. Non-membrane-bound polysomal mRNAs, such as histone mRNA and c-fos mRNA, are readily released from the cytoskeleton of HeLa cells during cytochalasin D treatment. Over 90% of H3 and H4 histone mRNA is associated with the cytoskeleton in control cells and only 25% in cells treated with cytochalasin D (40 micrograms/ml). In contrast, the membrane-bound polysomal mRNAs for HLA-B7 and chorionic gonadotropin-alpha are inefficiently released from the cytoskeletal framework by cytochalasin D alone; approximately 98% of the HLA-B7 mRNA in control cells is associated with the cytoskeleton, whereas approximately 65% of the HLA-B7 mRNA is retained on the cytoskeleton in cells treated with cytochalasin D (40 micrograms/ml). Disruption of polysome structure with puromycin during cytochalasin D treatment results in the efficient release of HLA-B7 mRNA from the cytoskeleton. Under these conditions, only 25% of the HLA-B7 mRNA remains associated with the cytoskeletal framework. Thus, membrane-bound polysomes appear to be attached to the cytoskeleton through a cytochalasin D-sensitive site as well as through association with the nascent polypeptide and/or ribosome. These results demonstrate a complex association of polysomes with the cytoskeleton and elements of the endoplasmic reticulum.
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Affiliation(s)
- G Zambetti
- Department of Cell Biology, University of Massachusetts Medical Center, Worcester 01655
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27
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Scherrer K. A unified matrix hypothesis of DNA-directed morphogenesis, protodynamism and growth control. Biosci Rep 1989; 9:157-88. [PMID: 2765661 DOI: 10.1007/bf01115994] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
A theoretical concept is proposed, in order to explain some enigmatic aspects of cellular and molecular biology of eukaryotic organisms. Among these are the C-value paradox of DNA redundancy, the correlation of DNA content and cell size, the disruption of genes at DNA level, the "Chromosome field" data of Lima de Faria (Hereditas 93:1, 1980), the "quantal mitosis" proposition of Holtzer et al. (Curr. Top. Dev. Biol. 7:229 1972), the inheritance of morphological patterns, the relations of DNA and chromosome organisation to cellular structure and function, the molecular basis of speciation, etc. The basic proposition of the "Unified Matrix Hypothesis" is that the nuclear DNA has a direct morphogenic function, in addition to its coding function in protein synthesis. This additional genetic information is thought to be largely contained in the non-protein coding transcribed DNA, and in the untranscribed part of the genome.
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Affiliation(s)
- K Scherrer
- Institut Jacques Monod, Université Paris VII, France
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28
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Price MG, Gomer RH. Mitoskelin: a mitochondrial protein found in cytoskeletal preparations. CELL MOTILITY AND THE CYTOSKELETON 1989; 13:274-87. [PMID: 2673550 DOI: 10.1002/cm.970130406] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
A 70 kD protein, which we have named mitoskelin, is highly enriched in cytoskeletal preparations from bovine cardiac muscle. Mitoskelin has three main variants with isoelectric points between 5.6 and 5.8. Immunoblotting with polyclonal antibodies directed against mitoskelin shows that, like intermediate filament proteins, the majority of mitoskelin resists solubilization from a myocardial homogenate by a series of extraction solutions ranging from very low salt to 0.6 M KI buffers and by 0.1-1% Nonidet P-40 detergent. By double-label immunofluorescence on cells and tissues, mitoskelin is colocalized with the mitochondrial marker cytochrome c oxidase. Mitoskelin is associated with the inner membranes of mitochondria as shown by immunoelectron microscopy and immunoblotting. Immunological cross-reactivity and similarities of molecular weight, pI, distribution, and chromatographic properties indicate that mitoskelin is the 70 kD component of complex I (NADH: ubiquinone oxidoreductase), a portion of the mitochondrial oxidative phosphorylation system. No function or activity has yet been demonstrated for the 70 kD component of the 25-polypeptide complex I. Dialysis against physiological buffers allows purified, urea-solubilized mitoskelin to form 10 nm wide filamentous structures that do not closely resemble intermediate filaments. These results suggest the exciting possibility that mitochondria may contain a membrane-associated filamentous skeleton.
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Affiliation(s)
- M G Price
- Department of Molecular Biology, Rice University, Houston 77251
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Meyer JM, Staubli A, Ruch JV. Ultrastructural duality of extracellular fibrillar components of the odontoblast layer in the mouse molar. Arch Oral Biol 1988; 33:25-31. [PMID: 3190510 DOI: 10.1016/0003-9969(88)90092-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The application of detergent solutions to dissociated molar dental papillae of mice permitted precise observation of the extracellular fibrillar material in the odontoblast layer and the predentine. Two types of fibrils were identified: cross-banded fibrils of variable diameter (25-200 nm) and aperiodic microfibrils of regular diameter (12.5 nm) and undetermined length. If the collagenic nature of the cross-banded fibrils is evident, the composition of the aperiodic microfibrils is probably different.
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Affiliation(s)
- J M Meyer
- Institut de Biologie Médicale, C.N.R.S., L.P. no. 6520, Faculté de Médecine, Strasbourg, France
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31
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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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Traas J, Ramaekers F. The membrane-associated cytoskeleton in cultured lens cells. Electron microscopical visualization in cleaved whole-mount preparations and platinum replicas. Exp Eye Res 1986; 43:519-28. [PMID: 3539628 DOI: 10.1016/s0014-4835(86)80020-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The membrane-bound cytoskeleton of bovine lens cells was investigated using different electron-microscopic methods. Cells were grown on glass coverslips and fixed in 0.5% glutaraldehyde, post-fixed and prepared for critical-point drying following standardized methods. Cells were broken open before post-fixation or after critical-point drying in order to expose the cortical cytoplasm. Cleaved, critical-point-dried cells were subsequently rotary replicated. Cells were also cleaved on grids before post-fixation. These cells were examined directly in the microscope. All methods showed the presence of a cytoskeletal network. Bundles and starlike foci of microfilaments and microtubules were usually found in close association with the membrane. Occasionally also intermediate filaments were observed, in a few cases running close to the microtubules. The reliability of the methods to visualize the membrane-bound cytoskeleton of lens cells is discussed.
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Goldman AE, Maul G, Steinert PM, Yang HY, Goldman RD. Keratin-like proteins that coisolate with intermediate filaments of BHK-21 cells are nuclear lamins. Proc Natl Acad Sci U S A 1986; 83:3839-43. [PMID: 2424013 PMCID: PMC323619 DOI: 10.1073/pnas.83.11.3839] [Citation(s) in RCA: 100] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Four proteins of Mr approximately equal to 60,000, 65,000, 67,000, and 70,000 coisolate with the major intermediate filament (IF) structural proteins of BHK-21 cells. These proteins are keratin-like, they form distinctive paracrystals in vitro, and they are concentrated at the nuclear surface. Since these properties indicate similarities with the nuclear lamins, we have prepared conventional fractions of BHK-21 nuclei from which the same type of paracrystal is obtained. Furthermore, biochemical and immunological data demonstrate that the lamins are identical to the Mr 60,000-70,000 proteins found in IF preparations, and both sets of proteins are similar to keratin. These results suggest that an IF-like protein network is present in the nuclear lamina. We speculate that in some unknown way this network connects to the cytoplasmic IF network that courses from the juxtanuclear region to the cell surface. These proposed interconnecting networks may form part of the infrastructure of cytoskeletal-nuclear matrix-connecting links involved in signal transmission between the nuclear and cytoplasmic compartments of eukaryotic cells.
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Dang CV, LaDuca FM, Bell WR. Histidyl-tRNA synthetase, the myositis Jo-1 antigen, is cytoplasmic and unassociated with the cytoskeletal framework. Exp Cell Res 1986; 164:261-6. [PMID: 3956597 DOI: 10.1016/0014-4827(86)90474-x] [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: 01/08/2023]
Abstract
The myositis-specific anti-Jo-1 autoantibody, which is directed against histidyl-tRNA-synthetase, is found in 30% of polymyositis patients. The Jo-1 antigen has been reported to be a nuclear antigen by some authors. On the contrary we show that less than 2% of the total histidyl-tRNA and lysyl-tRNA synthetase activities are associated with purified rat liver nuclei or the hepatocyte intermediate filament-nuclear fraction. In the presence of polyethylene glycol, in which the high Mr multi-enzyme complex containing lysyl-tRNA synthetase is insoluble, 65% of the lysyl-tRNA synthetase and only 15% of histidyl-tRNA synthetase activities remained associated with the cytoskeletal framework. The Jo-1 antigen exhibited a diffuse granular cytoplasmic distribution in cultured rat hepatocytes as determined by indirect immunofluorescent microscopy. Hence, the Jo-1 antigen is cytoplasmic and unassociated with the cytoskeletal framework or high Mr synthetase complex in situ.
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Kellermayer M, Ludany A, Jobst K, Szucs G, Trombitas K, Hazlewood CF. Cocompartmentation of proteins and K+ within the living cell. Proc Natl Acad Sci U S A 1986; 83:1011-5. [PMID: 3456561 PMCID: PMC323000 DOI: 10.1073/pnas.83.4.1011] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Monolayer H-50 tissue culture cells were treated with Triton X-100 and Brij 58 nonionic detergents, and their electron microscopic morphology along with the release of the intracellular proteins and K+ were studied. Although Triton X-100 was more effective, both detergents removed the lipoid membranes within 5 min. The mobilization and solubilization of the cytoplasmic and nuclear proteins occurred much faster with Triton X-100 than with Brij 58. In Triton X-100-treated cells, the loss of K+ was complete within 2 min. The loss of K+ from the Brij 58-treated cells was complete only after 10 min and the mobilization of K+ showed sigmoid-type release kinetics. These results support the view that most of K+ and "diffusible" proteins not freely dissolved in the cellular water, but they are cocompartmentalized inside the living cell.
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Paetau A, Virtanen I. Cytoskeletal properties and endogenous degradation of glial fibrillary acidic protein and vimentin in cultured human glioma cells. Acta Neuropathol 1986; 69:73-80. [PMID: 3515830 DOI: 10.1007/bf00687041] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The cytoskeletal properties and endogenous degradation of intermediate filaments in cultured human glioma cells (U-251MG) were studied using monoclonal antibodies in immunohistochemical and immunochemical methods. Both glial fibrillary acidic protein (GFAP)- and vimentin-antibodies gave a fibrillar cytoplasmic staining of the cells, and double immunofluorescence experiments showed the presence of both types of intermediate filaments in the same cells. GFAP and vimentin could also be located to typical coiling perinuclear bundles after vinblastine treatment of the cultures. In the detergent-resistant, adherent cytoskeletons of the glioma cells, both GFAP and vimentin persisted as fibrillar cytoplasmic arrays. Scanning and transmission electron microscopy showed that only intermediate filaments were left in the cytoplasmic domain. Electrophoretic analysis, combined with the immunoblotting method, revealed that the two major detergent-resistant cytoskeletal polypeptides of the cells, with molecular weights of 51 kD and 58 kD, were GFAP and vimentin, respectively. On the other hand, neither GFAP nor vimentin were detected in the detergent extracts of the glioma cells. Detergent-extraction in low ionic strength medium as well as inclusion of Ca2+ into the extraction medium resulted into a rapid degradation of both GFAP and vimentin. These degradation conditions produced different, partially soluble, lower MW immunoreactive polypeptides as detected by the immunoblotting technique. Interestingly, the degradation also produced soluble intact GFAP and vimentin. These results indicate that GFAP and vimentin have closely similar physicochemical properties in the cytoskeletons of human glioma cells including a nearly quantitative localization in filaments, rearrangement upon microtubule disruption, and resistance to extractions by detergents. Proteolytic degradation of both proteins can be induced by a protease activated by both low ionic strength and Ca2+.
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CHIBA KAZUYOSHI, HOSHI MOTONORI. Mass Isolation of Germinal Vesicles from Starfish Oocytes*. (germinal vesicle/nucleus/oocyte/starfish/mass isolation). Dev Growth Differ 1985. [DOI: 10.1111/j.1440-169x.1985.00277.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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38
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