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Cheng J, Allgeyer ES, Richens JH, Dzafic E, Palandri A, Lewków B, Sirinakis G, St Johnston D. A single-molecule localization microscopy method for tissues reveals nonrandom nuclear pore distribution in Drosophila. J Cell Sci 2021; 134:jcs259570. [PMID: 34806753 PMCID: PMC8729783 DOI: 10.1242/jcs.259570] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2021] [Accepted: 11/11/2021] [Indexed: 01/19/2023] Open
Abstract
Single-molecule localization microscopy (SMLM) can provide nanoscale resolution in thin samples but has rarely been applied to tissues because of high background from out-of-focus emitters and optical aberrations. Here, we describe a line scanning microscope that provides optical sectioning for SMLM in tissues. Imaging endogenously-tagged nucleoporins and F-actin on this system using DNA- and peptide-point accumulation for imaging in nanoscale topography (PAINT) routinely gives 30 nm resolution or better at depths greater than 20 µm. This revealed that the nuclear pores are nonrandomly distributed in most Drosophila tissues, in contrast to what is seen in cultured cells. Lamin Dm0 shows a complementary localization to the nuclear pores, suggesting that it corrals the pores. Furthermore, ectopic expression of the tissue-specific Lamin C causes the nuclear pores to distribute more randomly, whereas lamin C mutants enhance nuclear pore clustering, particularly in muscle nuclei. Given that nucleoporins interact with specific chromatin domains, nuclear pore clustering could regulate local chromatin organization and contribute to the disease phenotypes caused by human lamin A/C laminopathies.
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Affiliation(s)
- Jinmei Cheng
- The Gurdon Institute and Department of Genetics, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, UK
- Institute of Reproductive Medicine, School of Medicine, Nantong University, Nantong 226001, China
| | - Edward S. Allgeyer
- The Gurdon Institute and Department of Genetics, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, UK
| | - Jennifer H. Richens
- The Gurdon Institute and Department of Genetics, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, UK
| | - Edo Dzafic
- The Gurdon Institute and Department of Genetics, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, UK
| | - Amandine Palandri
- The Gurdon Institute and Department of Genetics, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, UK
| | - Bohdan Lewków
- The Gurdon Institute and Department of Genetics, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, UK
| | - George Sirinakis
- The Gurdon Institute and Department of Genetics, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, UK
| | - Daniel St Johnston
- The Gurdon Institute and Department of Genetics, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, UK
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2
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Expression of the Ebola Virus VP24 Protein Compromises the Integrity of the Nuclear Envelope and Induces a Laminopathy-Like Cellular Phenotype. mBio 2021; 12:e0097221. [PMID: 34225493 PMCID: PMC8406168 DOI: 10.1128/mbio.00972-21] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Ebola virus (EBOV) VP24 protein is a nucleocapsid-associated protein that inhibits interferon (IFN) gene expression and counteracts the IFN-mediated antiviral response, preventing nuclear import of signal transducer and activator of transcription 1 (STAT1). Proteomic studies to identify additional EBOV VP24 partners have pointed to the nuclear membrane component emerin as a potential element of the VP24 cellular interactome. Here, we have further studied this interaction and its impact on cell biology. We demonstrate that VP24 interacts with emerin but also with other components of the inner nuclear membrane, such as lamin A/C and lamin B. We also show that VP24 diminishes the interaction between emerin and lamin A/C and compromises the integrity of the nuclear membrane. This disruption is associated with nuclear morphological abnormalities, activation of a DNA damage response, the phosphorylation of extracellular signal-regulated kinase (ERK), and the induction of interferon-stimulated gene 15 (ISG15). Interestingly, expression of VP24 also promoted the cytoplasmic translocation and downmodulation of barrier-to-autointegration factor (BAF), a common interactor of lamin A/C and emerin, leading to repression of the BAF-regulated CSF1 gene. Importantly, we found that EBOV infection results in the activation of pathways associated with nuclear envelope damage, consistent with our observations in cells expressing VP24. In summary, here we demonstrate that VP24 acts at the nuclear membrane, causing morphological and functional changes in cells that recapitulate several of the hallmarks of laminopathy diseases.
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3
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Liu SY, Ikegami K. Nuclear lamin phosphorylation: an emerging role in gene regulation and pathogenesis of laminopathies. Nucleus 2021; 11:299-314. [PMID: 33030403 PMCID: PMC7588210 DOI: 10.1080/19491034.2020.1832734] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Decades of studies have established that nuclear lamin polymers form the nuclear lamina, a protein meshwork that supports the nuclear envelope structure and tethers heterochromatin to the nuclear periphery. Much less is known about unpolymerized nuclear lamins in the nuclear interior, some of which are now known to undergo specific phosphorylation. A recent finding that phosphorylated lamins bind gene enhancer regions offers a new hypothesis that lamin phosphorylation may influence transcriptional regulation in the nuclear interior. In this review, we discuss the regulation, localization, and functions of phosphorylated lamins. We summarize kinases that phosphorylate lamins in a variety of biological contexts. Our discussion extends to laminopathies, a spectrum of degenerative disorders caused by lamin gene mutations, such as cardiomyopathies and progeria. We compare the prevailing hypothesis for laminopathy pathogenesis based on lamins’ function at the nuclear lamina with an emerging hypothesis based on phosphorylated lamins’ function in the nuclear interior.
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Affiliation(s)
- Sunny Yang Liu
- Department of Pediatrics, The University of Chicago , Chicago, Illinois, USA
| | - Kohta Ikegami
- Department of Pediatrics, The University of Chicago , Chicago, Illinois, USA.,Division of Molecular and Cardiovascular Biology, Cincinnati Children's Hospital Medical Center , Cincinnati, Ohio, USA
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4
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Drosophila female germline stem cells undergo mitosis without nuclear breakdown. Curr Biol 2021; 31:1450-1462.e3. [PMID: 33548191 DOI: 10.1016/j.cub.2021.01.033] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Revised: 11/18/2020] [Accepted: 01/11/2021] [Indexed: 02/02/2023]
Abstract
Stem cell homeostasis requires nuclear lamina (NL) integrity. In Drosophila germ cells, compromised NL integrity activates the ataxia telangiectasia and Rad3-related (ATR) and checkpoint kinase 2 (Chk2) checkpoint kinases, blocking germ cell differentiation and causing germline stem cell (GSC) loss. Checkpoint activation occurs upon loss of either the NL protein emerin or its partner barrier-to-autointegration factor, two proteins required for nuclear reassembly at the end of mitosis. Here, we examined how mitosis contributes to NL structural defects linked to checkpoint activation. These analyses led to the unexpected discovery that wild-type female GSCs utilize a non-canonical mode of mitosis, one that retains a permeable but intact nuclear envelope and NL. We show that the interphase NL is remodeled during mitosis for insertion of centrosomes that nucleate the mitotic spindle within the confines of the nucleus. We show that depletion or loss of NL components causes mitotic defects, including compromised chromosome segregation associated with altered centrosome positioning and structure. Further, in emerin mutant GSCs, centrosomes remain embedded in the interphase NL. Notably, these embedded centrosomes carry large amounts of pericentriolar material and nucleate astral microtubules, revealing a role for emerin in the regulation of centrosome structure. Epistasis studies demonstrate that defects in centrosome structure are upstream of checkpoint activation, suggesting that these centrosome defects might trigger checkpoint activation and GSC loss. Connections between NL proteins and centrosome function have implications for mechanisms associated with NL dysfunction in other stem cell populations, including NL-associated diseases, such as laminopathies.
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5
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Alvarado-Kristensson M, Rosselló CA. The Biology of the Nuclear Envelope and Its Implications in Cancer Biology. Int J Mol Sci 2019; 20:E2586. [PMID: 31137762 PMCID: PMC6566445 DOI: 10.3390/ijms20102586] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2019] [Revised: 05/07/2019] [Accepted: 05/25/2019] [Indexed: 12/18/2022] Open
Abstract
The formation of the nuclear envelope and the subsequent compartmentalization of the genome is a defining feature of eukaryotes. Traditionally, the nuclear envelope was purely viewed as a physical barrier to preserve genetic material in eukaryotic cells. However, in the last few decades, it has been revealed to be a critical cellular component in controlling gene expression and has been implicated in several human diseases. In cancer, the relevance of the cell nucleus was first reported in the mid-1800s when an altered nuclear morphology was observed in tumor cells. This review aims to give a current and comprehensive view of the role of the nuclear envelope on cancer first by recapitulating the changes of the nuclear envelope during cell division, second, by reviewing the role of the nuclear envelope in cell cycle regulation, signaling, and the regulation of the genome, and finally, by addressing the nuclear envelope link to cell migration and metastasis and its use in cancer prognosis.
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Affiliation(s)
- Maria Alvarado-Kristensson
- Molecular Pathology, Department of Translational Medicine, Lund University, Skåne University Hospital, 20502 Malmö, Sweden.
| | - Catalina Ana Rosselló
- Laboratory of Molecular Cell Biomedicine, University of the Balearic Islands, 07121 Palma de Mallorca, Spain.
- Lipopharma Therapeutics, Isaac Newton, 07121 Palma de Mallorca, Spain.
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6
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Fal K, Asnacios A, Chabouté ME, Hamant O. Nuclear envelope: a new frontier in plant mechanosensing? Biophys Rev 2017; 9:389-403. [PMID: 28801801 PMCID: PMC5578935 DOI: 10.1007/s12551-017-0302-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2017] [Accepted: 07/28/2017] [Indexed: 02/07/2023] Open
Abstract
In animals, it is now well established that forces applied at the cell surface are propagated through the cytoskeleton to the nucleus, leading to deformations of the nuclear structure and, potentially, to modification of gene expression. Consistently, altered nuclear mechanics has been related to many genetic disorders, such as muscular dystrophy, cardiomyopathy and progeria. In plants, the integration of mechanical signals in cell and developmental biology has also made great progress. Yet, while the link between cell wall stresses and cytoskeleton is consolidated, such cortical mechanical cues have not been integrated with the nucleoskeleton. Here, we propose to take inspiration from studies on animal nuclei to identify relevant methods amenable to probing nucleus mechanics and deformation in plant cells, with a focus on microrheology. To identify potential molecular targets, we also compare the players at the nuclear envelope, namely lamina and LINC complex, in both plant and animal nuclei. Understanding how mechanical signals are transduced to the nucleus across kingdoms will likely have essential implications in development (e.g. how mechanical cues add robustness to gene expression patterns), in the nucleoskeleton-cytoskeleton nexus (e.g. how stress is propagated in turgid/walled cells), as well as in transcriptional control, chromatin biology and epigenetics.
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Affiliation(s)
- Kateryna Fal
- Laboratoire Reproduction et Développement des Plantes, Université de Lyon, ENS de Lyon, UCB Lyon 1, CNRS, INRA, 69342, Lyon, France
| | - Atef Asnacios
- Laboratoire Matières et Systèmes Complexes, Université Paris-Diderot and CNRS, UMR 7057, Sorbonne Paris Cité, Paris, France
| | - Marie-Edith Chabouté
- Institut de Biologie Moléculaire des Plantes, CNRS, Université de Strasbourg, 67000, Strasbourg, France
| | - Olivier Hamant
- Laboratoire Reproduction et Développement des Plantes, Université de Lyon, ENS de Lyon, UCB Lyon 1, CNRS, INRA, 69342, Lyon, France.
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7
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Cho S, Irianto J, Discher DE. Mechanosensing by the nucleus: From pathways to scaling relationships. J Cell Biol 2017; 216:305-315. [PMID: 28043971 PMCID: PMC5294790 DOI: 10.1083/jcb.201610042] [Citation(s) in RCA: 235] [Impact Index Per Article: 33.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Revised: 12/05/2016] [Accepted: 12/14/2016] [Indexed: 01/01/2023] Open
Abstract
Cho, Irianto, and Discher review emerging mechanisms of nuclear mechanosensing and propose through meta-analyses of published data the universality of mechanosensing pathways. The nucleus is linked mechanically to the extracellular matrix via multiple polymers that transmit forces to the nuclear envelope and into the nuclear interior. Here, we review some of the emerging mechanisms of nuclear mechanosensing, which range from changes in protein conformation and transcription factor localization to chromosome reorganization and membrane dilation up to rupture. Nuclear mechanosensing encompasses biophysically complex pathways that often converge on the main structural proteins of the nucleus, the lamins. We also perform meta-analyses of public transcriptomics and proteomics data, which indicate that some of the mechanosensing pathways relaying signals from the collagen matrix to the nucleus apply to a broad range of species, tissues, and diseases.
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Affiliation(s)
- Sangkyun Cho
- Molecular and Cell Biophysics Lab, University of Pennsylvania, Philadelphia, PA 19104
| | - Jerome Irianto
- Molecular and Cell Biophysics Lab, University of Pennsylvania, Philadelphia, PA 19104
| | - Dennis E Discher
- Molecular and Cell Biophysics Lab, University of Pennsylvania, Philadelphia, PA 19104
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Sechi S, Frappaolo A, Fraschini R, Capalbo L, Gottardo M, Belloni G, Glover DM, Wainman A, Giansanti MG. Rab1 interacts with GOLPH3 and controls Golgi structure and contractile ring constriction during cytokinesis in Drosophila melanogaster. Open Biol 2017; 7:160257. [PMID: 28100664 PMCID: PMC5303273 DOI: 10.1098/rsob.160257] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2016] [Accepted: 12/12/2016] [Indexed: 12/17/2022] Open
Abstract
Cytokinesis requires a tight coordination between actomyosin ring constriction and new membrane addition along the ingressing cleavage furrow. However, the molecular mechanisms underlying vesicle trafficking to the equatorial site and how this process is coupled with the dynamics of the contractile apparatus are poorly defined. Here we provide evidence for the requirement of Rab1 during cleavage furrow ingression in cytokinesis. We demonstrate that the gene omelette (omt) encodes the Drosophila orthologue of human Rab1 and is required for successful cytokinesis in both mitotic and meiotic dividing cells of Drosophila melanogaster We show that Rab1 protein colocalizes with the conserved oligomeric Golgi (COG) complex Cog7 subunit and the phosphatidylinositol 4-phosphate effector GOLPH3 at the Golgi stacks. Analysis by transmission electron microscopy and 3D-SIM super-resolution microscopy reveals loss of normal Golgi architecture in omt mutant spermatocytes indicating a role for Rab1 in Golgi formation. In dividing cells, Rab1 enables stabilization and contraction of actomyosin rings. We further demonstrate that GTP-bound Rab1 directly interacts with GOLPH3 and controls its localization at the Golgi and at the cleavage site. We propose that Rab1, by associating with GOLPH3, controls membrane trafficking and contractile ring constriction during cytokinesis.
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Affiliation(s)
- Stefano Sechi
- Istituto di Biologia e Patologia Molecolari del CNR, Dipartimento di Biologia e Biotecnologie, Università Sapienza di Roma, Piazzale A. Moro 5, 00185 Roma, Italy
| | - Anna Frappaolo
- Istituto di Biologia e Patologia Molecolari del CNR, Dipartimento di Biologia e Biotecnologie, Università Sapienza di Roma, Piazzale A. Moro 5, 00185 Roma, Italy
| | - Roberta Fraschini
- Dipartimento di Biotecnologie e Bioscienze, Università degli studi di Milano Bicocca, Piazza della Scienza 2, 20126 Milan, Italy
| | - Luisa Capalbo
- Department of Genetics, University of Cambridge, Downing Street, Cambridge CB2 3EH, UK
| | - Marco Gottardo
- Dipartimento di Scienze della Vita, Università di Siena, Via A. Moro 2, 53100 Siena, Italy
| | - Giorgio Belloni
- Istituto di Biologia e Patologia Molecolari del CNR, Dipartimento di Biologia e Biotecnologie, Università Sapienza di Roma, Piazzale A. Moro 5, 00185 Roma, Italy
| | - David M Glover
- Department of Genetics, University of Cambridge, Downing Street, Cambridge CB2 3EH, UK
| | - Alan Wainman
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK
| | - Maria Grazia Giansanti
- Istituto di Biologia e Patologia Molecolari del CNR, Dipartimento di Biologia e Biotecnologie, Università Sapienza di Roma, Piazzale A. Moro 5, 00185 Roma, Italy
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9
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Lamm CE, Link K, Wagner S, Milbradt J, Marschall M, Sonnewald U. Human Cytomegalovirus Nuclear Egress Proteins Ectopically Expressed in the Heterologous Environment of Plant Cells are Strictly Targeted to the Nuclear Envelope. Viruses 2016; 8:73. [PMID: 26978388 PMCID: PMC4810263 DOI: 10.3390/v8030073] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Revised: 02/23/2016] [Accepted: 02/29/2016] [Indexed: 12/14/2022] Open
Abstract
In all eukaryotic cells, the nucleus forms a prominent cellular compartment containing the cell's nuclear genome. Although structurally similar, animal and plant nuclei differ substantially in details of their architecture. One example is the nuclear lamina, a layer of tightly interconnected filament proteins (lamins) underlying the nuclear envelope of metazoans. So far no orthologous lamin genes could be detected in plant genomes and putative lamin-like proteins are only poorly described in plants. To probe for potentially conserved features of metazoan and plant nuclear envelopes, we ectopically expressed the core nuclear egress proteins of human cytomegalovirus pUL50 and pUL53 in plant cells. pUL50 localizes to the inner envelope of metazoan nuclei and recruits the nuclear localized pUL53 to it, forming heterodimers. Upon expression in plant cells, a very similar localization pattern of both proteins could be determined. Notably, pUL50 is specifically targeted to the plant nuclear envelope in a rim-like fashion, a location to which coexpressed pUL53 becomes strictly corecruited from its initial nucleoplasmic distribution. Using pUL50 as bait in a yeast two-hybrid screening, the cytoplasmic re-initiation supporting protein RISP could be identified. Interaction of pUL50 and RISP could be confirmed by coexpression and coimmunoprecipitation in mammalian cells and by confocal laser scanning microscopy in plant cells, demonstrating partial pUL50-RISP colocalization in areas of the nuclear rim and other intracellular compartments. Thus, our study provides strong evidence for conserved structural features of plant and metazoan nuclear envelops and identifies RISP as a potential pUL50-interacting plant protein.
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Affiliation(s)
- Christian E Lamm
- Division of Biochemistry, Department of Biology, Friedrich-Alexander University Erlangen-Nuremberg, Staudtstrasse 5, Erlangen 91058, Germany.
| | - Katrin Link
- Division of Biochemistry, Department of Biology, Friedrich-Alexander University Erlangen-Nuremberg, Staudtstrasse 5, Erlangen 91058, Germany.
| | - Sabrina Wagner
- Institute for Clinical and Molecular Virology, Friedrich-Alexander University Erlangen-Nuremberg, Schloßgarten 4, Erlangen 91054, Germany.
| | - Jens Milbradt
- Institute for Clinical and Molecular Virology, Friedrich-Alexander University Erlangen-Nuremberg, Schloßgarten 4, Erlangen 91054, Germany.
| | - Manfred Marschall
- Institute for Clinical and Molecular Virology, Friedrich-Alexander University Erlangen-Nuremberg, Schloßgarten 4, Erlangen 91054, Germany.
| | - Uwe Sonnewald
- Division of Biochemistry, Department of Biology, Friedrich-Alexander University Erlangen-Nuremberg, Staudtstrasse 5, Erlangen 91058, Germany.
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Fabbretti F, Iannetti I, Guglielmi L, Perconti S, Evangelistella C, Proietti De Santis L, Bongiorni S, Prantera G. Confocal Analysis of Nuclear Lamina Behavior during Male Meiosis and Spermatogenesis in Drosophila melanogaster. PLoS One 2016; 11:e0151231. [PMID: 26963718 PMCID: PMC4786128 DOI: 10.1371/journal.pone.0151231] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2015] [Accepted: 02/25/2016] [Indexed: 11/19/2022] Open
Abstract
Lamin family proteins are structural components of a filamentous framework, the nuclear lamina (NL), underlying the inner membrane of nuclear envelope. The NL not only plays a role in nucleus mechanical support and nuclear shaping, but is also involved in many cellular processes including DNA replication, gene expression and chromatin positioning. Spermatogenesis is a very complex differentiation process in which each stage is characterized by nuclear architecture dramatic changes, from the early mitotic stage to the sperm differentiation final stage. Nevertheless, very few data are present in the literature on the NL behavior during this process. Here we show the first and complete description of NL behavior during meiosis and spermatogenesis in Drosophila melanogaster. By confocal imaging, we characterized the NL modifications from mitotic stages, through meiotic divisions to sperm differentiation with an anti-laminDm0 antibody against the major component of the Drosophila NL. We observed that continuous changes in the NL structure occurred in parallel with chromatin reorganization throughout the whole process and that meiotic divisions occurred in a closed context. Finally, we analyzed NL in solofuso meiotic mutant, where chromatin segregation is severely affected, and found the strict correlation between the presence of chromatin and that of NL.
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Affiliation(s)
- Fabiana Fabbretti
- Department of Ecology and Biology, Università della Tuscia, Viterbo, Italy
- * E-mail: (GP); (FF)
| | - Ilaria Iannetti
- Department of Ecology and Biology, Università della Tuscia, Viterbo, Italy
| | - Loredana Guglielmi
- Department of Ecology and Biology, Università della Tuscia, Viterbo, Italy
| | - Susanna Perconti
- Department of Ecology and Biology, Università della Tuscia, Viterbo, Italy
| | | | | | - Silvia Bongiorni
- Department of Ecology and Biology, Università della Tuscia, Viterbo, Italy
| | - Giorgio Prantera
- Department of Ecology and Biology, Università della Tuscia, Viterbo, Italy
- * E-mail: (GP); (FF)
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11
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Abstract
The nuclear lamina represents a multifunctional platform involved in such diverse yet interconnected processes as spatial organization of the genome, maintenance of mechanical stability of the nucleus, regulation of transcription and replication. Most of lamina activities are exerted through tethering of lamina-associated chromatin domains (LADs) to the nuclear periphery. Yet, the lamina is a dynamic structure demonstrating considerable expansion during the cell cycle to accommodate increased number of LADs formed during DNA replication. We analyzed dynamics of nuclear growth during interphase and changes in lamina structure as a function of cell cycle progression. The nuclear lamina demonstrates steady growth from G1 till G2, while quantitative analysis of lamina meshwork by super-resolution microscopy revealed that microdomain organization of the lamina is maintained, with lamin A and lamin B microdomain periodicity and interdomain gap sizes unchanged. FRAP analysis, in contrast, demonstrated differences in lamin A and B1 exchange rates; the latter showing higher recovery rate in S-phase cells. In order to further analyze the mechanism of lamina growth in interphase, we generated a lamina-free nuclear envelope in living interphase cells by reversible hypotonic shock. The nuclear envelope in nuclear buds formed after such a treatment initially lacked lamins, and analysis of lamina formation revealed striking difference in lamin A and B1 assembly: lamin A reassembled within 30 min post-treatment, whereas lamin B1 did not incorporate into the newly formed lamina at all. We suggest that in somatic cells lamin B1 meshwork growth is coordinated with replication of LADs, and lamin A meshwork assembly seems to be chromatin-independent process.
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12
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Wasserlauf I, Usov K, Artemov G, Anan'ina T, Stegniy V. Specific features in linear and spatial organizations of pericentromeric heterochromatin regions in polytene chromosomes of the closely related species Drosophila virilis and D. kanekoi (Diptera: Drosophilidae). Genetica 2015; 143:331-42. [PMID: 25721230 DOI: 10.1007/s10709-015-9832-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2014] [Accepted: 02/23/2015] [Indexed: 12/17/2022]
Abstract
Heterochromatin plays an important role in the spatial arrangement and evolution of the eukaryotic genetic apparatus. The closely related species Drosophila virilis (phyla virilis) and D. kanekoi (phyla montana) differ in the amount of heterochromatin along the chromosomes as well as by the presence of the metacentric chromosome 2, which emerged as a result of a pericentric inversion during speciation, in the D. kanekoi karyotype. The purpose of this study was to establish if chromosome rearrangements have any influence on the linear redistribution of centromeric heterochromatin in polytene chromosomes and the spatial organization of chromosomes in the nuclei of nurse cell. We have microdissected the chromocenter of D. virilis salivary gland polytene chromosomes; obtained a DNA library of this region (DvirIII); and hybridized (FISH) DvirIII to the salivary gland and nurse cell polytene chromosomes of D. virilis and D. kanekoi. We demonstrated that DvirIII localizes to the pericentromeric heterochromatin regions of all chromosomes and peritelomeric region of chromosome 5 in both species. Unlike D. virilis, the DvirIII signal in D. kanekoi chromosomes is detectable in the telomeric region of chromosome 2. We have also conducted a 3D FISH of DvirIII probe to the D. virilis and D. kanekoi nurse cell chromosomes. In particular, the DvirIII signal in D. virilis was observed in the local chromocenter at one pole of the nucleus, while the signal belonging to the telomeric region of chromosome 5 was detectable at the other pole. In contrast, in D. kanekoi there exist two separate DvirIII-positive regions. One of these regions belongs to the pericentromeric region of chromosome 2 and the other, to pericentromeric regions of the remaining chromosomes. These results suggest that chromosome rearrangements play an important role in the redistribution of heterochromatin DNA sequences in the genome, representing a speciation mechanism, which, in general, could also affect the chromosome orientation in the 3D nuclear space.
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Affiliation(s)
- Irina Wasserlauf
- Tomsk State University, 36 Lenin Prospekt, Tomsk, 634050, Russian Federation,
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Abstract
Despite decades of research, cancer metastasis remains an incompletely understood process that is as complex as it is devastating. In recent years, there has been an increasing push to investigate the biomechanical aspects of tumorigenesis, complementing the research on genetic and biochemical changes. In contrast to the high genetic variability encountered in cancer cells, almost all metastatic cells are subject to the same physical constraints as they leave the primary tumor, invade surrounding tissues, transit through the circulatory system, and finally infiltrate new tissues. Advances in live cell imaging and other biophysical techniques, including measurements of subcellular mechanics, have yielded stunning new insights into the physics of cancer cells. While much of this research has been focused on the mechanics of the cytoskeleton and the cellular microenvironment, it is now emerging that the mechanical properties of the cell nucleus and its connection to the cytoskeleton may play a major role in cancer metastasis, as deformation of the large and stiff nucleus presents a substantial obstacle during the passage through the dense interstitial space and narrow capillaries. Here, we present an overview of the molecular components that govern the mechanical properties of the nucleus, and we discuss how changes in nuclear structure and composition observed in many cancers can modulate nuclear mechanics and promote metastatic processes. Improved insights into this interplay between nuclear mechanics and metastatic progression may have powerful implications in cancer diagnostics and therapy and may reveal novel therapeutic targets for pharmacological inhibition of cancer cell invasion.
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Affiliation(s)
- Celine Denais
- Department of Biomedical Engineering, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY, 14853, USA,
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14
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Stancheva I, Schirmer EC. Nuclear Envelope: Connecting Structural Genome Organization to Regulation of Gene Expression. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2014; 773:209-44. [DOI: 10.1007/978-1-4899-8032-8_10] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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15
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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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16
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Abstract
The nuclear lamins are type V intermediate filament proteins that are critically important for the structural properties of the nucleus. In addition, they are involved in the regulation of numerous nuclear processes, including DNA replication, transcription and chromatin organization. The developmentally regulated expression of lamins suggests that they are involved in cellular differentiation. Their assembly dynamic properties throughout the cell cycle, particularly in mitosis, are influenced by posttranslational modifications. Lamins may regulate nuclear functions by direct interactions with chromatin and determining the spatial organization of chromosomes within the nuclear space. They may also regulate chromatin functions by interacting with factors that epigenetically modify the chromatin or directly regulate replication or transcription.
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Affiliation(s)
- Thomas Dechat
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611, USA
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17
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Kuga T, Nozaki N, Matsushita K, Nomura F, Tomonaga T. Phosphorylation statuses at different residues of lamin B2, B1, and A/C dynamically and independently change throughout the cell cycle. Exp Cell Res 2010; 316:2301-12. [PMID: 20580708 DOI: 10.1016/j.yexcr.2010.05.017] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2009] [Revised: 04/23/2010] [Accepted: 05/18/2010] [Indexed: 11/17/2022]
Abstract
Lamins, major components of the nuclear lamina, undergo phosphorylation at multiple residues during cell cycle progression, but their detailed phosphorylation kinetics remain largely undetermined. Here, we examined changes in the phosphorylation of major phosphorylation residues (Thr14, Ser17, Ser385, Ser387, and Ser401) of lamin B2 and the homologous residues of lamin B1, A/C during the cell cycle using novel antibodies to the site-specific phosphorylation. The phosphorylation levels of these residues independently changed during the cell cycle. Thr14 and Ser17 were phosphorylated during G(2)/M phase to anaphase/telophase. Ser385 was persistently phosphorylated during mitosis to G(1) phase, whereas Ser387 was phosphorylated discontinuously in prophase and G(1) phase. Ser401 phosphorylation was enhanced in the G(1)/S boundary. Immunoprecipitation using the phospho-antibodies suggested that metaphase-phosphorylation at Thr14, Ser17, and Ser385 of lamins occurred simultaneously, whereas G(1)-phase phosphorylation at Ser385 and Ser387 occurred in distinct pools or with different timings. Additionally, we showed that lamin B2 phosphorylated at Ser17, but not Ser385, Ser387 and Ser401, was exclusively non-ionic detergent soluble, depolymerized forms in growing cells, implicating specific involvement of Ser17 phosphorylation in lamin depolymerization and nuclear envelope breakdown. These results suggest that the phosphorylations at different residues of lamins might play specific roles throughout the cell cycle.
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Affiliation(s)
- Takahisa Kuga
- Laboratory of Proteome Research, National Institute of Biomedical Innovation, Ibaraki, Osaka 567-0085, Japan.
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18
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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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19
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Nuclear pore proteins nup153 and megator define transcriptionally active regions in the Drosophila genome. PLoS Genet 2010; 6:e1000846. [PMID: 20174442 PMCID: PMC2820533 DOI: 10.1371/journal.pgen.1000846] [Citation(s) in RCA: 189] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2009] [Accepted: 01/14/2010] [Indexed: 12/03/2022] Open
Abstract
Transcriptional regulation is one of the most important processes for modulating gene expression. Though much of this control is attributed to transcription factors, histones, and associated enzymes, it is increasingly apparent that the spatial organization of chromosomes within the nucleus has a profound effect on transcriptional activity. Studies in yeast indicate that the nuclear pore complex might promote transcription by recruiting chromatin to the nuclear periphery. In higher eukaryotes, however, it is not known whether such regulation has global significance. Here we establish nucleoporins as a major class of global regulators for gene expression in Drosophila melanogaster. Using chromatin-immunoprecipitation combined with microarray hybridisation, we show that Nup153 and Megator (Mtor) bind to 25% of the genome in continuous domains extending 10 kb to 500 kb. These Nucleoporin-Associated Regions (NARs) are dominated by markers for active transcription, including high RNA polymerase II occupancy and histone H4K16 acetylation. RNAi–mediated knock-down of Nup153 alters the expression of ∼5,700 genes, with a pronounced down-regulatory effect within NARs. We find that nucleoporins play a central role in coordinating dosage compensation—an organism-wide process involving the doubling of expression of the male X chromosome. NARs are enriched on the male X chromosome and occupy 75% of this chromosome. Furthermore, Nup153-depletion abolishes the normal function of the male-specific dosage compensation complex. Finally, by extensive 3D imaging, we demonstrate that NARs contribute to gene expression control irrespective of their sub-nuclear localization. Therefore, we suggest that NAR–binding is used for chromosomal organization that enables gene expression control. The eukaryotic genome is spatially distributed in a highly organized manner, with chromosomal regions localizing to well-defined sub-nuclear positions. This organization could have a profound effect on chromatin accessibility and transcriptional activity on a genome-wide level. Using high-resolution, genome-wide, chromatin-binding profiles we show that the nuclear pore components Nup153 and Megator bind to quarter of the Drosophila genome in form of chromosomal domains. These domains represent active regions of the genome. Interestingly, comparison of male and female cells revealed enrichment of these domains on the male X chromosome, which represents an exceptionally active chromosome that is under dosage compensation control to equalize gene expression due to differences in X chromosome number between males and females. Based on extensive 3D image analysis, we show that these chromosomal domains are contributed by both peripheral as well as intranuclear pool of these proteins. We suggest that chromosomal organization by nucleoporins could contribute to global gene expression control.
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20
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Lavelle C. Forces and torques in the nucleus: chromatin under mechanical constraints. Biochem Cell Biol 2009; 87:307-22. [PMID: 19234543 DOI: 10.1139/o08-123] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Genomic DNA in eukaryotic cells is organized in discrete chromosome territories, each consisting of a single huge hierarchically supercoiled nucleosomal fiber. Through dynamic changes in structure, resulting from chemical modifications and mechanical constraints imposed by numerous factors in vivo, chromatin plays a critical role in the regulation of DNA metabolism processes, including replication and transcription. Indeed, DNA-translocating enzymes, such as polymerases, produce physical constraints that chromatin has to overcome. Recent techniques, in particular single-molecule micromanipulation, have allowed precise quantization of forces and torques at work in the nucleus and have greatly improved our understanding of chromatin behavior under physiological mechanical constraints. These new biophysical approaches should enable us to build realistic mechanistic models and progressively specify the ad hoc and hazy "because of chromatin structure" argument often used to interpret experimental studies of biological function in the context of chromatin.
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21
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Akita H, Kudo A, Minoura A, Yamaguti M, Khalil IA, Moriguchi R, Masuda T, Danev R, Nagayama K, Kogure K, Harashima H. Multi-layered nanoparticles for penetrating the endosome and nuclear membrane via a step-wise membrane fusion process. Biomaterials 2009; 30:2940-9. [PMID: 19261326 DOI: 10.1016/j.biomaterials.2009.02.009] [Citation(s) in RCA: 101] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2008] [Accepted: 02/09/2009] [Indexed: 11/19/2022]
Abstract
Efficient targeting of DNA to the nucleus is a prerequisite for effective gene therapy. The gene-delivery vehicle must penetrate through the plasma membrane, and the DNA-impermeable double-membraned nuclear envelope, and deposit its DNA cargo in a form ready for transcription. Here we introduce a concept for overcoming intracellular membrane barriers that involves step-wise membrane fusion. To achieve this, a nanotechnology was developed that creates a multi-layered nanoparticle, which we refer to as a Tetra-lamellar Multi-functional Envelope-type Nano Device (T-MEND). The critical structural elements of the T-MEND are a DNA-polycation condensed core coated with two nuclear membrane-fusogenic inner envelopes and two endosome-fusogenic outer envelopes, which are shed in stepwise fashion. A double-lamellar membrane structure is required for nuclear delivery via the stepwise fusion of double layered nuclear membrane structure. Intracellular membrane fusions to endosomes and nuclear membranes were verified by spectral imaging of fluorescence resonance energy transfer (FRET) between donor and acceptor fluorophores that had been dually labeled on the liposome surface. Coating the core with the minimum number of nucleus-fusogenic lipid envelopes (i.e., 2) is essential to facilitate transcription. As a result, the T-MEND achieves dramatic levels of transgene expression in non-dividing cells.
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22
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Dechat T, Adam SA, Goldman RD. Nuclear lamins and chromatin: when structure meets function. ADVANCES IN ENZYME REGULATION 2008; 49:157-66. [PMID: 19154754 PMCID: PMC3253622 DOI: 10.1016/j.advenzreg.2008.12.003] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Affiliation(s)
- Thomas Dechat
- Northwestern University Medical School, Department of Cell and Molecular Biology, Chicago, Illinois 60611, USA
| | - Stephen A. Adam
- Northwestern University Medical School, Department of Cell and Molecular Biology, Chicago, Illinois 60611, USA
| | - Robert D. Goldman
- Northwestern University Medical School, Department of Cell and Molecular Biology, Chicago, Illinois 60611, USA
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23
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Schirmer EC. The epigenetics of nuclear envelope organization and disease. Mutat Res 2008; 647:112-21. [PMID: 18722388 DOI: 10.1016/j.mrfmmm.2008.07.012] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2008] [Revised: 07/16/2008] [Accepted: 07/23/2008] [Indexed: 01/09/2023]
Abstract
Mammalian chromosomes and some specific genes have non-random positions within the nucleus that are tissue-specific and heritable. Work in many organisms has shown that genes at the nuclear periphery tend to be inactive and altering their partitioning to the interior results in their activation. Proteins of the nuclear envelope can recruit chromatin with specific epigenetic marks and can also recruit silencing factors that add new epigenetic modifications to chromatin sequestered at the periphery. Together these findings indicate that the nuclear envelope is a significant epigenetic regulator. The importance of this function is emphasized by observations of aberrant distribution of peripheral heterochromatin in several human diseases linked to mutations in NE proteins. These debilitating inherited diseases range from muscular dystrophies to the premature aging progeroid syndromes and the heterochromatin changes are just one early clue for understanding the molecular details of how they work. The architecture of the nuclear envelope provides a unique environment for epigenetic regulation and as such a great deal of research will be required before we can ascertain the full range of its contributions to epigenetics.
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Affiliation(s)
- Eric C Schirmer
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh EH9 3JR, UK.
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24
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Schermelleh L, Carlton PM, Haase S, Shao L, Winoto L, Kner P, Burke B, Cardoso MC, Agard DA, Gustafsson MGL, Leonhardt H, Sedat JW. Subdiffraction multicolor imaging of the nuclear periphery with 3D structured illumination microscopy. Science 2008; 320:1332-6. [PMID: 18535242 DOI: 10.1126/science.1156947] [Citation(s) in RCA: 751] [Impact Index Per Article: 46.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Fluorescence light microscopy allows multicolor visualization of cellular components with high specificity, but its utility has until recently been constrained by the intrinsic limit of spatial resolution. We applied three-dimensional structured illumination microscopy (3D-SIM) to circumvent this limit and to study the mammalian nucleus. By simultaneously imaging chromatin, nuclear lamina, and the nuclear pore complex (NPC), we observed several features that escape detection by conventional microscopy. We could resolve single NPCs that colocalized with channels in the lamin network and peripheral heterochromatin. We could differentially localize distinct NPC components and detect double-layered invaginations of the nuclear envelope in prophase as previously seen only by electron microscopy. Multicolor 3D-SIM opens new and facile possibilities to analyze subcellular structures beyond the diffraction limit of the emitted light.
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Affiliation(s)
- Lothar Schermelleh
- Center for Integrated Protein Science, Department of Biology, Ludwig Maximilians University Munich, 82152 Planegg-Martinsried, Germany
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25
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Rowat AC, Lammerding J, Herrmann H, Aebi U. Towards an integrated understanding of the structure and mechanics of the cell nucleus. Bioessays 2008; 30:226-36. [PMID: 18293361 DOI: 10.1002/bies.20720] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Changes in the shape and structural organization of the cell nucleus occur during many fundamental processes including development, differentiation and aging. In many of these processes, the cell responds to physical forces by altering gene expression within the nucleus. How the nucleus itself senses and responds to such mechanical cues is not well understood. In addition to these external forces, epigenetic modifications of chromatin structure inside the nucleus could also alter its physical properties. To achieve a better understanding, we need to elucidate the relationship between nuclear structure and material properties. Recently, new approaches have been developed to systematically investigate nuclear mechanical properties. These experiments provide important new insights into the disease mechanism of a growing class of tissue-specific disorders termed 'nuclear envelopathies'. Here we review our current understanding of what determines the shape and mechanical properties of the cell nucleus.
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Affiliation(s)
- Amy C Rowat
- Department of Physics/School of Engineering and Applied Science, Harvard University, Cambridge, MA 02138, USA.
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26
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Kalverda B, Röling MD, Fornerod M. Chromatin organization in relation to the nuclear periphery. FEBS Lett 2008; 582:2017-22. [PMID: 18435921 DOI: 10.1016/j.febslet.2008.04.015] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2008] [Accepted: 04/11/2008] [Indexed: 11/15/2022]
Abstract
In the limited space of the nucleus, chromatin is organized in a dynamic and non-random manner. Three ways of chromatin organization are compaction, formation of loops and localization within the nucleus. To study chromatin localization it is most convenient to use the nuclear envelope as a fixed viewpoint. Peripheral chromatin has both been described as silent chromatin, interacting with the nuclear lamina, and active chromatin, interacting with nuclear pore proteins. Current data indicate that the nuclear envelope is a reader as well as a writer of chromatin state, and that its influence is not limited to the nuclear periphery.
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Affiliation(s)
- Bernike Kalverda
- Department of Tumor Biology, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX Amsterdam, The Netherlands
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27
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Kreplak L, Richter K, Aebi U, Herrmann H. Chapter 15 Electron Microscopy of Intermediate Filaments: Teaming up with Atomic Force and Confocal Laser Scanning Microscopy. Methods Cell Biol 2008; 88:273-97. [DOI: 10.1016/s0091-679x(08)00415-9] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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28
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Clarke T, Bouquet JM, Fu X, Kallesøe T, Schmid M, Thompson EM. Rapidly evolving lamins in a chordate, Oikopleura dioica, with unusual nuclear architecture. Gene 2007; 396:159-69. [PMID: 17449201 DOI: 10.1016/j.gene.2007.03.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2007] [Revised: 03/01/2007] [Accepted: 03/12/2007] [Indexed: 01/06/2023]
Abstract
Metazoan lamins are implicated in the organization of numerous critical nuclear processes. Among chordates, the appendicularian, Oikopleura dioica, has an unusually short life cycle involving rapid growth through extensive recourse to endoreduplication, a characteristic more associated with some invertebrates. In some tissues, this is accompanied by the formation of elaborate, bilaterally symmetric nuclear morphologies associated with specific gene expression patterns. Lamin composition can mediate nuclear shape in spermiogenesis as well as during pathological and normal aging and we have analyzed the O. dioica lamin and intermediate filament (IF) complement, comparing it to that present in other deuterostomes. O. dioica has one lamin gene coding two splice variants. Both variants share with the sister class ascidians a highly reduced C-terminal tail region lacking the immunoglobulin fold, indicating this derivation occurred at the base of the urochordate lineage. The OdLamin2 variant has a unique insertion of 63 amino acids in the normally short N-terminal region and has a developmental expression profile corresponding to the occurrence of endocycling. O. dioica has 4 cytoplasmic IF proteins, IF-A, C, Dalpha, and Dbeta. No homologues to the ascidian IF-B or F proteins were identified, reinforcing the suggestion that these proteins are unique to ascidians. The degree of sequence evolution in the rod domains of O. dioica cytoplasmic IF proteins and their closest ascidian and vertebrate homologues was similar. In contrast, whereas the rate of lamin B rod domain sequence evolution has also been similar in vertebrates, cephalochordates and the sea urchin, faster rates have occurred among the urochordates, with the O. dioica lamin displaying a far greater rate than any other lamin.
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Affiliation(s)
- Thomas Clarke
- Sars Centre for Marine Molecular Biology, Bergen High Technology Centre, University of Bergen, Thormøhlensgate 55, N-5008 Bergen, Norway
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29
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Abstract
Cells have evolved sophisticated multi-protein complexes that can regulate gene activity at various steps of the transcription process. Recent advances highlight the role of nuclear positioning in the control of gene expression and have put nuclear envelope components at centre stage. On the inner face of the nuclear envelope, active genes localize to nuclear-pore structures whereas silent chromatin localizes to non-pore sites. Nuclear-pore components seem to not only recruit the RNA-processing and RNA-export machinery, but contribute a level of regulation that might enhance gene expression in a heritable manner.
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Affiliation(s)
- Asifa Akhtar
- EMBL, Meyerhofstrasse 1, 69117 Heidelberg, Germany.
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30
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Abstract
The inner face of the nuclear envelope of metazoan cells is covered by a thin lamina consisting of a one-layered network of intermediate filaments interconnecting with a complex set of transmembrane proteins and chromatin associating factors. The constituent proteins, the lamins, have recently gained tremendous recognition, because mutations in the lamin A gene, LMNA, are the cause of a complex group of at least 10 different diseases in human, including the Hutchinson-Gilford progeria syndrome. The analysis of these disease entities has made it clear that besides cytoskeletal functions, the lamina has an important role in the "behaviour" of the genome and is, probably as a consequence of this function, intimately involved in cell fate decisions. Furthermore, these functions are related to the involvement of lamins in organizing the position and functional state of interphase chromosomes as well as to the occurrence of lamins and lamina-associated proteins within the nucleoplasm. However, the structural features of these lamins and the nature of the factors that assist them in genome organization present an exciting challenge to modern biochemistry and cell biology.
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Affiliation(s)
- Joanna M Bridger
- Centre for Cell and Chromosome Biology, Division of Biosciences, Brunel University, London, UK
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31
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Rowat AC, Foster LJ, Nielsen MM, Weiss M, Ipsen JH. Characterization of the elastic properties of the nuclear envelope. J R Soc Interface 2006; 2:63-9. [PMID: 16849165 PMCID: PMC1578255 DOI: 10.1098/rsif.2004.0022] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Underlying the nuclear envelope (NE) of most eukaryotic cells is the nuclear lamina, a meshwork consisting largely of coiled-coil nuclear intermediate filament proteins that play a critical role in nuclear organization and gene expression, and are vital for the structural stability of the NE/nucleus. By confocal microscopy and micromanipulation of the NE in living cells and isolated nuclei, we show that the NE undergoes deformations without large-scale rupture and maintains structural stability when exposed to mechanical stress. In conjunction with image analysis, we have developed theory for a two-dimensional elastic material to quantify NE elastic behaviour. We show that the NE is elastic and exhibits characteristics of a continuous two-dimensional solid, including connections between lamins and the embedded nuclear pore complexes. Correlating models of NE lateral organization to the experimental findings indicates a heterogeneous lateral distribution of NE components on a mesoscopic scale.
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Affiliation(s)
- A C Rowat
- MEMPHYS-Center for Biomembrane Physics, Department of Physics, Campusvej 55, University of Southern Denmark, 5230 Odense M, Denmark
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32
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Pickersgill H, Kalverda B, de Wit E, Talhout W, Fornerod M, van Steensel B. Characterization of the Drosophila melanogaster genome at the nuclear lamina. Nat Genet 2006; 38:1005-14. [PMID: 16878134 DOI: 10.1038/ng1852] [Citation(s) in RCA: 419] [Impact Index Per Article: 23.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2006] [Accepted: 06/30/2006] [Indexed: 01/18/2023]
Abstract
The nuclear lamina binds chromatin in vitro and is thought to function in its organization, but genes that interact with it are unknown. Using an in vivo approach, we identified approximately 500 Drosophila melanogaster genes that interact with B-type lamin (Lam). These genes are transcriptionally silent and late replicating, lack active histone marks and are widely spaced. These factors collectively predict lamin binding behavior, indicating that the nuclear lamina integrates variant and invariant chromatin features. Consistently, proximity of genomic regions to the nuclear lamina is partly conserved between cell types, and induction of gene expression or active histone marks reduces Lam binding. Lam target genes cluster in the genome, and these clusters are coordinately expressed during development. This genome-wide analysis gives clear insight into the nature and dynamic behavior of the genome at the nuclear lamina, and implies that intergenic DNA functions in the global organization of chromatin in the nucleus.
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Affiliation(s)
- Helen Pickersgill
- Department of Tumor Biology, The Netherlands Cancer Institute, Plesmanlaan 121, 1066CX Amsterdam, The Netherlands
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33
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Ostlund C, Sullivan T, Stewart CL, Worman HJ. Dependence of diffusional mobility of integral inner nuclear membrane proteins on A-type lamins. Biochemistry 2006; 45:1374-82. [PMID: 16445279 PMCID: PMC2527696 DOI: 10.1021/bi052156n] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Integral proteins of the nuclear envelope inner membrane have been proposed to reach their sites by diffusion after their co-translational insertion in the rough endoplasmic reticulum. They are then retained in the inner nuclear membrane by binding to nuclear structures. One such structure is the nuclear lamina, an intermediate filament meshwork composed of A-type and B-type lamin proteins. Emerin, MAN1, and LBR are three integral inner nuclear membrane proteins. We expressed these proteins fused to green fluorescent protein in embryonic fibroblasts from wild-type mice and Lmna -/- mice, which lack A-type lamins. We then studied the diffusional mobilities of emerin, MAN1, and LBR using fluorescence recovery after photobleaching. We show that emerin and MAN1, but not LBR, are more mobile in the inner nuclear membrane of cells from Lmna -/- mice than in cells from wild-type mice. In cells from Lmna -/- mice expressing exogenous lamin A, the protein mobilities were similar to those in cells from wild-type mice. This supports a model where emerin and MAN1 are at least partly retained in the inner nuclear membrane by binding to A-type lamins, while LBR depends on other binding partners for its retention.
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Affiliation(s)
- Cecilia Ostlund
- Department of Medicine, College of Physicians and Surgeons, Columbia University, Room 10-509, 630 West 168th Street, New York, New York 10032, USA
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34
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Fang Y, Spector DL. Centromere positioning and dynamics in living Arabidopsis plants. Mol Biol Cell 2005; 16:5710-8. [PMID: 16195344 PMCID: PMC1289415 DOI: 10.1091/mbc.e05-08-0706] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2005] [Revised: 09/13/2005] [Accepted: 09/15/2005] [Indexed: 11/11/2022] Open
Abstract
The organization and dynamics of the genome have been shown to influence gene expression in many organisms. Data from mammalian tissue culture cells have provided conflicting conclusions with regard to the extent to which chromatin organization is inherited from mother to daughter nuclei. To gain insight into chromatin organization and dynamics, we developed transgenic Arabidopsis lines in which centromeres were tagged with a green fluorescent protein fusion of the centromere-specific histone H3. Using four-dimensional (4-D) live cell imaging, we show that Arabidopsis centromeres are constrained at the nuclear periphery during interphase and that the organization of endoreduplicated sister centromeres is cell type dependent with predominant clustering in root epidermal cells and dispersion in leaf epidermal cells. 4-D tracking of the entire set of centromeres through mitosis, in growing root meristematic cells, demonstrated that global centromere position is not precisely transmitted from the mother cell to daughter cells. These results provide important insight into our understanding of chromatin organization among different cells of a living organism.
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Affiliation(s)
- Yuda Fang
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA
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35
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Senda T, Iizuka-Kogo A, Shimomura A. Visualization of the nuclear lamina in mouse anterior pituitary cells and immunocytochemical detection of lamin A/C by quick-freeze freeze-substitution electron microscopy. J Histochem Cytochem 2005; 53:497-507. [PMID: 15805424 DOI: 10.1369/jhc.4a6478.2005] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We examined the nuclear lamina in the quickly frozen anterior pituitary cells by electron microscopic techniques combined with freeze substitution, deep etching, and immunocytochemistry and compared it with that in the chemically fixed cells. By quick-freeze freeze-substitution electron microscopy, an electron-lucent layer, as thick as 20 nm, was revealed just inside the inner nuclear membrane, whereas in the conventionally glutaraldehyde-fixed cells the layer was not seen. By quick-freeze deep-etch electron microscopy, we could not distinguish definitively the layer corresponding to the nuclear lamina in either fresh unfixed or glutaraldehyde-fixed cells. Immunofluorescence microscopy showed that lamin A/C in the nucleus was detected in the acetone-fixed cells and briefly in paraformaldehyde-fixed cells but not in the cells with prolonged paraformaldehyde fixation. Nuclear localization of lamin A/C was revealed by immunogold electron microscopy also in the quickly frozen and freeze-substituted cells, but not in the paraformaldehyde-fixed cells. Lamin A/C was localized mainly in the peripheral nucleoplasm within 60 nm from the inner nuclear membrane, which corresponded to the nuclear lamina. These results suggest that the nuclear lamina can be preserved both ultrastructurally and immunocytochemically by quick-freezing fixation, rather than by conventional chemical fixation.
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Affiliation(s)
- Takao Senda
- Department of Anatomy I, Fujita Health University School of Medicine, Toyoake, Aichi 470-1192, Japan.
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36
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Nakayama Y, Yamaguchi N. Multi-lobulation of the nucleus in prolonged S phase by nuclear expression of Chk tyrosine kinase. Exp Cell Res 2005; 304:570-81. [PMID: 15748901 DOI: 10.1016/j.yexcr.2004.11.027] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2004] [Revised: 10/13/2004] [Accepted: 11/26/2004] [Indexed: 11/24/2022]
Abstract
Chk tyrosine kinase phosphorylates Src-family tyrosine kinases and suppresses their kinase activity. We recently showed that Chk localizes to the nucleus as well as the cytoplasm and inhibits cell proliferation. To investigate the role of nuclear Chk in proliferation, various Chk mutants were constructed and expressed. Nuclear localization of Chk-induced dynamic multi-lobulation of the nucleus and prolonged S phase of the cell cycle. The N-terminal domain of Chk and a portion of its kinase domain but not the kinase activity were responsible for induction of the multi-lobulation. Cell sorting analysis revealed that nuclear multi-lobulated cells were enriched in late S phase. Multi-lobulated nuclei were surrounded with lamin B1 that was particularly concentrated in concave regions of the nuclei. Furthermore, treatment with nocodazole or taxol disrupted multi-lobulation of the nucleus. These results suggest that nuclear multi-lobulation in late S phase, which is dependent on polymerization and depolymerization of microtubules, may be involved in nuclear Chk-induced inhibition of proliferation.
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Affiliation(s)
- Yuji Nakayama
- Department of Molecular Cell Biology, Graduate School of Pharmaceutical Sciences, Chiba University, Inohana 1-8-1, Chuo-ku, Chiba 260-8675, Japan
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37
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Harmon B, Sedat J. Cell-by-cell dissection of gene expression and chromosomal interactions reveals consequences of nuclear reorganization. PLoS Biol 2005; 3:e67. [PMID: 15737020 PMCID: PMC1054879 DOI: 10.1371/journal.pbio.0030067] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2004] [Accepted: 12/17/2004] [Indexed: 02/03/2023] Open
Abstract
The functional consequences of long-range nuclear reorganization were studied in a cell-by-cell analysis of gene expression and long-range chromosomal interactions in the Drosophila eye and eye imaginal disk. Position-effect variegation was used to stochastically perturb gene expression and probe nuclear reorganization. Variegating genes on rearrangements of Chromosomes X, 2, and 3 were probed for long-range interactions with heterochromatin. Studies were conducted only in tissues known to express the variegating genes. Nuclear structure was revealed by fluorescence in situ hybridization with probes to the variegating gene and heterochromatin. Gene expression was determined alternately by immunofluorescence against specific proteins and by eye pigment autofluorescence. This allowed cell-by-cell comparisons of nuclear architecture between cells in which the variegating gene was either expressed or silenced. Very strong correlations between heterochromatic association and silencing were found. Expressing cells showed a broad distribution of distances between variegating genes and their own centromeric heterochromatin, while silenced cells showed a very tight distribution centered around very short distances, consistent with interaction between the silenced genes and heterochromatin. Spatial and temporal analysis of interactions with heterochromatin indicated that variegating genes primarily associate with heterochromatin in cells that have exited the cell cycle. Differentiation was not a requirement for association, and no differences in association were observed between cell types. Thus, long-range interactions between distal chromosome regions and their own heterochromatin have functional consequences for the organism. The authors have devised a way to compare the expression of a gene and its association with heterochromatin in a single cell - such association tightly correlates with gene silencing
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Affiliation(s)
- Brian Harmon
- 1University of California, San FranciscoCaliforniaUnited States of America
| | - John Sedat
- 1University of California, San FranciscoCaliforniaUnited States of America
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38
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Panorchan P, Wirtz D, Tseng Y. Structure-function relationship of biological gels revealed by multiple-particle tracking and differential interference contrast microscopy: the case of human lamin networks. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2004; 70:041906. [PMID: 15600434 DOI: 10.1103/physreve.70.041906] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2004] [Indexed: 05/24/2023]
Abstract
Lamin B1 filaments organize into a thin dense meshwork underlying the nucleoplasmic side of the nuclear envelope. Recent experiments in vivo suggest that lamin B1 plays a key structural role in the nuclear envelope, but the intrinsic mechanical properties of lamin B1 networks remain unknown. To assess the potential mechanical contribution of lamin B1 in maintaining the integrity and providing structural support to the nucleus, we measured the micromechanical properties and examined the ultrastructural distribution of lamin B1 networks in vitro using particle tracking methods and differential interference contrast (DIC) microscopy. We exploit various surface chemistries of the probe microspheres (carboxylated, polyethylene glycol-coated, and amine-modified) to differentiate lamin-rich from lamin-poor regions and to rigorously extract local viscoelastic moduli from the mean-squared displacements of noninteracting particles. Our results show that human lamin B1 can, even in the absence of auxiliary proteins, form stiff and yet extremely porous networks that are well suited to provide structural strength to the nuclear lamina. Combining DIC microscopy and particle tracking allows us to relate directly the local organization of a material to its local mechanical properties, a general methodology that can be extended to living cells.
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Affiliation(s)
- Porntula Panorchan
- Department of Chemical and Biomolecular Engineering, The Johns Hopkins University, 3400 North Charles Street, Baltimore, Maryland 21218, USA
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39
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D'Avino PP, Savoian MS, Glover DM. Mutations in sticky lead to defective organization of the contractile ring during cytokinesis and are enhanced by Rho and suppressed by Rac. ACTA ACUST UNITED AC 2004; 166:61-71. [PMID: 15240570 PMCID: PMC2172139 DOI: 10.1083/jcb.200402157] [Citation(s) in RCA: 107] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
The contractile ring is a highly dynamic structure, but how this dynamism is accomplished remains unclear. Here, we report the identification and analysis of a novel Drosophila gene, sticky (sti), essential for cytokinesis in all fly proliferating tissues. sti encodes the Drosophila orthologue of the mammalian Citron kinase. RNA interference–mediated silencing of sti in cultured cells causes them to become multinucleate. Components of the contractile ring and central spindle are recruited normally in such STICKY-depleted cells that nevertheless display asymmetric furrowing and aberrant blebbing. Together with an unusual distribution of F-actin and Anillin, these phenotypes are consistent with defective organization of the contractile ring. sti shows opposite genetic interactions with Rho and Rac genes suggesting that these GTPases antagonistically regulate STICKY functions. Similar genetic evidence indicates that RacGAP50C inhibits Rac during cytokinesis. We discuss that antagonism between Rho and Rac pathways may control contractile ring dynamics during cytokinesis.
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Affiliation(s)
- Pier Paolo D'Avino
- Cancer Research UK Cell Cycle Genetics Research Group, Department of Genetics, University of Cambridge, Downing Site, CB2 3EH.
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40
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Dahl KN, Kahn SM, Wilson KL, Discher DE. The nuclear envelope lamina network has elasticity and a compressibility limit suggestive of a molecular shock absorber. J Cell Sci 2004; 117:4779-86. [PMID: 15331638 DOI: 10.1242/jcs.01357] [Citation(s) in RCA: 296] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Mechanical properties of the nuclear envelope have implications for cell and nuclear architecture as well as gene regulation. Using isolated Xenopus oocyte nuclei, we have established swelling conditions that separate the intact nuclear envelope (membranes, pore complexes and underlying lamin filament network) from nucleoplasm and the majority of chromatin. Swelling proves reversible with addition of high molecular mass dextrans. Micropipette aspiration of swollen and unswollen nuclear envelopes is also reversible and yields a network elastic modulus, unaffected by nucleoplasm, that averages 25 mN/m. Compared to plasma membranes of cells, the nuclear envelope is much stiffer and more resilient. Our results suggest that the nuclear lamina forms a compressed network shell of interconnected rods that is extensible but limited in compressibility from the native state, thus acting as a 'molecular shock absorber'. In light of the conservation of B-type lamins in metazoan evolution, the mechanical properties determined in this investigation suggest physical mechanisms by which mutated lamins can either destabilize nuclear architecture or influence nuclear responses to mechanical signals in Emery-Dreifuss muscular dystrophy, cardiomyopathy, progeria syndromes (premature 'aging') and other laminopathies.
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Affiliation(s)
- Kris Noel Dahl
- Department of Chemical and Biomolecular Engineering, 220 South 33rd Street, University of Pennsylvania, Philadelphia, PA 19104-6393, USA
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41
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Gruenbaum Y, Goldman RD, Meyuhas R, Mills E, Margalit A, Fridkin A, Dayani Y, Prokocimer M, Enosh A. The nuclear lamina and its functions in the nucleus. INTERNATIONAL REVIEW OF CYTOLOGY 2004; 226:1-62. [PMID: 12921235 DOI: 10.1016/s0074-7696(03)01001-5] [Citation(s) in RCA: 173] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The nuclear lamina is a structure near the inner nuclear membrane and the peripheral chromatin. It is composed of lamins, which are also present in the nuclear interior, and lamin-associated proteins. The increasing number of proteins that interact with lamins and the compound interactions between these proteins and chromatin-associated proteins make the nuclear lamina a highly complex but also a very exciting structure. The nuclear lamina is an essential component of metazoan cells. It is involved in most nuclear activities including DNA replication, RNA transcription, nuclear and chromatin organization, cell cycle regulation, cell development and differentiation, nuclear migration, and apoptosis. Specific mutations in nuclear lamina genes cause a wide range of heritable human diseases. These diseases include Emery-Dreifuss muscular dystrophy, limb girdle muscular dystrophy, dilated cardiomyopathy (DCM) with conduction system disease, familial partial lipodystrophy (FPLD), autosomal recessive axonal neuropathy (Charcot-Marie-Tooth disorder type 2, CMT2), mandibuloacral dysplasia (MAD), Hutchison Gilford Progeria syndrome (HGS), Greenberg Skeletal Dysplasia, and Pelger-Huet anomaly (PHA). Genetic analyses in Caenorhabditis elegans, Drosophila, and mice show new insights into the functions of the nuclear lamina, and recent structural analyses have begun to unravel the molecular structure and assembly of lamins and their associated proteins.
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Affiliation(s)
- Yosef Gruenbaum
- Department of Genetics, The Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
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42
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Abstract
Development requires a precise program of gene expression to be carried out. Much work has focussed on the regulatory networks that control gene expression, for example in response to external cues. However, it is important to recognize that these regulatory events take place within the physical context of the nucleus, and that the physical position of a gene within the nuclear volume can have strong influences on its regulation and interactions. The first part of this review will summarize what is currently known about nuclear architecture, that is, the large-scale three-dimensional arrangement of chromosome loci within the nucleus. The remainder of the review will examine developmental processes from the point of view of the nucleus.
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Affiliation(s)
- Wallace F Marshall
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, CT 06520, USA.
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43
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Maske CP, Hollinshead MS, Higbee NC, Bergo MO, Young SG, Vaux DJ. A carboxyl-terminal interaction of lamin B1 is dependent on the CAAX endoprotease Rce1 and carboxymethylation. J Cell Biol 2003; 162:1223-32. [PMID: 14504265 PMCID: PMC2173957 DOI: 10.1083/jcb.200303113] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2003] [Accepted: 08/13/2003] [Indexed: 11/24/2022] Open
Abstract
The mammalian nuclear lamina protein lamin B1 is posttranslationally modified by farnesylation, endoproteolysis, and carboxymethylation at a carboxyl-terminal CAAX motif. In this work, we demonstrate that the CAAX endoprotease Rce1 is required for lamin B1 endoproteolysis, demonstrate an independent pool of proteolyzed but nonmethylated lamin B1, as well as fully processed lamin B1, in interphase nuclei, and show a role for methylation in the organization of lamin B1 into domains of the nuclear lamina. Deficiency in the endoproteolysis or methylation of lamin B1 results in loss of integrity and deformity of the nuclear lamina. These data show that the organization of the nuclear envelope and lamina is dependent on a mechanism involving the methylation of lamin B1, and they identify a potential mechanism of laminopathy involving a B-type lamin.
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Affiliation(s)
- Christopher P Maske
- Sir William Dunn School of Pathology, University of Oxford, Oxford, OX1 3RE, UK
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44
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Falloon EA, Dynlacht JR. Reversible changes in the nuclear lamina induced by hyperthermia. J Cell Biochem 2003; 86:451-60. [PMID: 12210752 DOI: 10.1002/jcb.10241] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The nuclear matrix (NM) has been identified as a potential target for heat-induced cell killing. Previous studies have shown that heat-shock may significantly modulate lamin B content. Since changes in NM structure have often been accompanied by changes in protein composition, we investigated whether hyperthermia induced changes in nuclear lamina (NL) structure in non-tolerant and thermotolerant cells, and the implications of these changes on cell survival. Using indirect immunofluorescence techniques and confocal microscopy, we found that heating cells at 42 or 45.5 degrees C caused invaginations and other distortions of the peripheral NL. While hyperthermia did not alter the number or structure of internal lamin B foci, heat-induced alterations to the peripheral NL were dose-dependent. Interestingly, NL structure recovered with time after heating in cells that were destined to live or die. Thermotolerant cells heated at 45.5 degrees C showed similar initial changes in the NL compared to non-tolerant cells, but recovery occurred much faster. Taken together, these results suggest that the amount of initial damage to the peripheral NL is not correlated with heat-induced cell killing. However, the possibility that an increased rate of recovery might confer a survival advantage cannot be discounted.
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Affiliation(s)
- Elizabeth A Falloon
- Department of Radiation Oncology, Indiana University School of Medicine, Indiana Cancer Pavilion, RT 041, 535 Barnhill Drive, Indianapolis, Indiana 46202, USA
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45
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Walter J, Schermelleh L, Cremer M, Tashiro S, Cremer T. Chromosome order in HeLa cells changes during mitosis and early G1, but is stably maintained during subsequent interphase stages. J Cell Biol 2003; 160:685-97. [PMID: 12604593 PMCID: PMC2173351 DOI: 10.1083/jcb.200211103] [Citation(s) in RCA: 246] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Whether chromosomes maintain their nuclear positions during interphase and from one cell cycle to the next has been controversially discussed. To address this question, we performed long-term live-cell studies using a HeLa cell line with GFP-tagged chromatin. Positional changes of the intensity gravity centers of fluorescently labeled chromosome territories (CTs) on the order of several microm were observed in early G1, suggesting a role of CT mobility in establishing interphase nuclear architecture. Thereafter, the positions were highly constrained within a range of approximately 1 microm until the end of G2. To analyze possible changes of chromosome arrangements from one cell cycle to the next, nuclei were photobleached in G2 maintaining a contiguous zone of unbleached chromatin at one nuclear pole. This zone was stably preserved until the onset of prophase, whereas the contiguity of unbleached chromosome segments was lost to a variable extent, when the metaphase plate was formed. Accordingly, chromatin patterns observed in daughter nuclei differed significantly from the mother cell nucleus. We conclude that CT arrangements were stably maintained from mid G1 to late G2/early prophase, whereas major changes of CT neighborhoods occurred from one cell cycle to the next. The variability of CT neighborhoods during clonal growth was further confirmed by chromosome painting experiments.
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Affiliation(s)
- Joachim Walter
- Dept. Biologie II, Lehrstuhl für Anthropologie und Humangenetik, LMU, Richard-Wagner-Strasse 10/I, 80333 München, Germany
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46
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Máthé E, Inoue YH, Palframan W, Brown G, Glover DM. Orbit/Mast, the CLASP orthologue of Drosophila, is required for asymmetric stem cell and cystocyte divisions and development of the polarised microtubule network that interconnects oocyte and nurse cells during oogenesis. Development 2003; 130:901-15. [PMID: 12538517 DOI: 10.1242/dev.00315] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Drosophila oocyte differentiation is preceded by the formation of a polarised 16-cell cyst from a single progenitor stem cell as a result of four rounds of asymmetric mitosis followed by incomplete cytokinesis. We show that the Orbit/Mast microtubule-associated protein is required at several stages in the formation of such polarised 16-cell cysts. In wild-type cysts, the Orbit/Mast protein not only associates with the mitotic spindle and its poles, but also with the central spindle (spindle remnant), ring canal and fusome, suggesting it participates in interactions between these structures. In orbit mutants, the stem cells and their associated fusomes are eventually lost as Orbit/Mast protein is depleted. The mitotic spindles of those cystocytes that do divide are either diminutive or monopolar, and do not make contact with the fusome. Moreover, the spindle remnants and ring canals fail to differentiate correctly in such cells and the structure of fusome is compromised. The Orbit/Mast protein thus appears to facilitate multiple interactions of the fusome with mitotic spindles and ring canals. This ensures correct growth of the fusome into a branched asymmetrically distributed organelle that is pre-determinative of 16-cell cyst formation and oocyte fate specification. Finally the Orbit/Mast protein is required during mid-oogenesis for the organisation of the polarised microtubule network inside the 16-cell cyst that ensures oocyte differentiation. The localisation of CLIP-190 to such microtubules and to the fusome is dependent upon Orbit/Mast to which it is complexed.
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Affiliation(s)
- Endre Máthé
- Cancer Research UK, Cell Cycle Genetics Research Group, Department of Genetics, University of Cambridge, Downing Street, Cambridge CB2 3EN, UK
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47
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Kondo Y, Kondoh J, Hayashi D, Ban T, Takagi M, Kamei Y, Tsuji L, Kim J, Yoneda Y. Molecular cloning of one isotype of human lamina-associated polypeptide 1s and a topological analysis using its deletion mutants. Biochem Biophys Res Commun 2002; 294:770-8. [PMID: 12061773 DOI: 10.1016/s0006-291x(02)00563-6] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
LAP1s (lamina-associated polypeptide 1s) are type 2 integral membrane proteins with a single membrane-spanning region of the inner nuclear membrane. We report here on the cloning of the full-length cDNA of human LAP1B (huLAP1B) that encodes 584 amino acids. The sequence homology between the predicted rat LAP1B and huLAP1B was found to be 73.6%. A topological analysis was carried out by transiently expressing N-terminal GFP fused deletion mutants of huLAP1B in cells. The transmembrane (TM) domain (aa 346-368) is required for the localization of the nuclear and endoplasmic reticulum membrane and that the TM domain and the C-terminal half of the nucleoplasmic domain (aa 190-331) are sufficient for the proper localization of LAP1B. In contrast, the well-conserved lumenal domain of the nuclear membrane is not required for its topological function. Biochemical analysis showed that huLAP1B is retained within the nucleus via interactions of the nucleoplasmic portion with nuclear components.
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Affiliation(s)
- Yukihiro Kondo
- Depertment of Cell Biology and Neuroscience, Graduate School of Medicine, Osaka University, 2-2 Yamada-oka, Suita, Japan
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48
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Zimowska G, Paddy MR. Structures and dynamics of Drosophila Tpr inconsistent with a static, filamentous structure. Exp Cell Res 2002; 276:223-32. [PMID: 12027452 DOI: 10.1006/excr.2002.5525] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Here we report immunofluorescence localizations of the Drosophila Tpr protein which are inconsistent with a filament-forming protein statically associated with nuclear pore complex-associated intranuclear filaments. Using tissues from throughout the Drosophila life cycle, we observe that Tpr is often localized to discontinuous, likely granular or particulate structures in the deep nuclear interior. These apparent granules have no obvious connectivity to pore complexes in the nuclear periphery, and are often localized on the surfaces of chromosomes and to the perinucleolar region. Most strikingly, after 1 h of heat shock, the great majority of the Tpr in the deep nuclear interior accumulates at a single heat shock puff, while Tpr in the nuclear periphery appears unchanged. This heat shock puff, 93D, is a known repository for many components of pre-mRNA metabolism during heat shock. Although we do not observe Tpr at sites of transcription under normal conditions, the 93D heat shock result leads us to favor a role for Tpr in mRNA metabolism, such as the transport of mRNA through the nuclear interior to nuclear pore complexes. Consistent with this, we observe networks of Tpr containing granules spanning between the nucleolus and the nuclear periphery which are also decorated by an anti-SR protein antibody. Since we also observe Drosophila Tpr in reticular or fibrous structures in other nuclei, such as salivary gland polytene nuclei, these results indicate that Tpr can exist in at least two structural forms, and suggest that Tpr may relocalize or even change structural forms in response to cellular needs.
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Affiliation(s)
- Grazyna Zimowska
- Department of Anatomy and Cell Biology, University of Florida, Gainesville, Florida 32610-0235, USA.
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49
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Tolstonog GV, Sabasch M, Traub P. Cytoplasmic intermediate filaments are stably associated with nuclear matrices and potentially modulate their DNA-binding function. DNA Cell Biol 2002; 21:213-39. [PMID: 12015898 DOI: 10.1089/10445490252925459] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The tight association of cytoplasmic intermediate filaments (cIFs) with the nucleus and the isolation of crosslinkage products of vimentin with genomic DNA fragments, including nuclear matrix attachment regions (MARs) from proliferating fibroblasts, point to a participation of cIFs in nuclear activities. To test the possibility that cIFs are complementary nuclear matrix elements, the nuclei of a series of cultured cells were subjected to the Li-diiodosalicylate (LIS) extraction protocol developed for the preparation of nuclear matrices and analyzed by immunofluorescence microscopy and immunoblotting with antibodies directed against lamin B and cIF proteins. When nuclei released from hypotonically swollen L929 suspension cells in the presence of digitonin or Triton X-100 were exposed to such strong shearing forces that a considerable number were totally disrupted, a thin, discontinuous layer of vimentin IFs remained tenaciously adhering to still intact nuclei, in apparent coalignment with the nuclear lamina. Even in broken nuclei, the distribution of vimentin followed that of lamin B in areas where the lamina still appeared intact. The same retention of vimentin together with desmin and glial IFs was observed on the nuclei isolated from differentiating C2C12 myoblast and U333 glioma cells, respectively. Nuclei from epithelial cells shed their residual perinuclear IF layers as coherent cytoskeletal ghosts, except for small fractions of vimentin and cytokeratin IFs, which remained in a dot-to cap-like arrangement on the nuclear surface, in apparent codistribution with lamin B. LIS extraction did not bring about a reduction in the cIF protein contents of such nuclei upon their transformation into nuclear matrices. Moreover, in whole mount preparations of mouse embryo fibroblasts, DNA/chromatin emerging from nuclei during LIS extraction mechanically and chemically cleaned the nuclear surface and perinuclear area from loosely anchored cytoplasmic material with the production of broad, IF-free annular spaces, but left substantial fractions of the vimentin IFs in tight association with the nuclear surface. Accordingly, double-immunogold electron microscopy of fixed and permeabilized fibroblasts disclosed a close neighborhood of vimentin IFs and lamin B, with a minimal distance between the nanogold particles of ca. 30 nm. These data indicate an extremely solid interconnection of cIFs with structural elements of the nuclear matrix, and make them, together with their susceptibility to crosslinkage to MARs and other genomic DNA sequences under native conditions, complementary or even integral constituents of the karyoskeleton.
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50
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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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