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Bruhn C, Ajazi A, Ferrari E, Lanz MC, Batrin R, Choudhary R, Walvekar A, Laxman S, Longhese MP, Fabre E, Smolka MB, Foiani M. The Rad53 CHK1/CHK2-Spt21 NPAT and Tel1 ATM axes couple glucose tolerance to histone dosage and subtelomeric silencing. Nat Commun 2020; 11:4154. [PMID: 32814778 PMCID: PMC7438486 DOI: 10.1038/s41467-020-17961-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Accepted: 07/23/2020] [Indexed: 12/14/2022] Open
Abstract
The DNA damage response (DDR) coordinates DNA metabolism with nuclear and non-nuclear processes. The DDR kinase Rad53CHK1/CHK2 controls histone degradation to assist DNA repair. However, Rad53 deficiency causes histone-dependent growth defects in the absence of DNA damage, pointing out unknown physiological functions of the Rad53-histone axis. Here we show that histone dosage control by Rad53 ensures metabolic homeostasis. Under physiological conditions, Rad53 regulates histone levels through inhibitory phosphorylation of the transcription factor Spt21NPAT on Ser276. Rad53-Spt21 mutants display severe glucose dependence, caused by excess histones through two separable mechanisms: dampening of acetyl-coenzyme A-dependent carbon metabolism through histone hyper-acetylation, and Sirtuin-mediated silencing of starvation-induced subtelomeric domains. We further demonstrate that repression of subtelomere silencing by physiological Tel1ATM and Rpd3HDAC activities coveys tolerance to glucose restriction. Our findings identify DDR mutations, histone imbalances and aberrant subtelomeric chromatin as interconnected causes of glucose dependence, implying that DDR kinases coordinate metabolism and epigenetic changes.
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Affiliation(s)
- Christopher Bruhn
- The FIRC Institute of Molecular Oncology (IFOM), Via Adamello 16, 20139, Milan, Italy.
| | - Arta Ajazi
- The FIRC Institute of Molecular Oncology (IFOM), Via Adamello 16, 20139, Milan, Italy
| | - Elisa Ferrari
- The FIRC Institute of Molecular Oncology (IFOM), Via Adamello 16, 20139, Milan, Italy
| | - Michael Charles Lanz
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY, 14853, USA
| | - Renaud Batrin
- Université de Paris, Laboratoire Génomes, Biologie Cellulaire et Thérapeutiques, CNRS UMR7212, INSERM U944, Centre de Recherche St Louis, F-75010, Paris, France
| | - Ramveer Choudhary
- The FIRC Institute of Molecular Oncology (IFOM), Via Adamello 16, 20139, Milan, Italy
| | - Adhish Walvekar
- Institute for Stem Cell Science and Regenerative Medicine (inStem), Bangalore, Karnataka, 560065, India
| | - Sunil Laxman
- Institute for Stem Cell Science and Regenerative Medicine (inStem), Bangalore, Karnataka, 560065, India
| | - Maria Pia Longhese
- Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano-Bicocca, Edificio U3, Piazza della Scienza 2, 20126, Milan, Italy
| | - Emmanuelle Fabre
- Université de Paris, Laboratoire Génomes, Biologie Cellulaire et Thérapeutiques, CNRS UMR7212, INSERM U944, Centre de Recherche St Louis, F-75010, Paris, France
| | - Marcus Bustamente Smolka
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY, 14853, USA
| | - Marco Foiani
- The FIRC Institute of Molecular Oncology (IFOM), Via Adamello 16, 20139, Milan, Italy.
- Università degli Studi di Milano, Via Festa del Perdono 7, 20122, Milan, Italy.
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Maestroni L, Reyes C, Vaurs M, Gachet Y, Tournier S, Géli V, Coulon S. Nuclear envelope attachment of telomeres limits TERRA and telomeric rearrangements in quiescent fission yeast cells. Nucleic Acids Res 2020; 48:3029-3041. [PMID: 31980821 PMCID: PMC7102995 DOI: 10.1093/nar/gkaa043] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2019] [Revised: 01/13/2020] [Accepted: 01/16/2020] [Indexed: 11/12/2022] Open
Abstract
Telomere anchoring to nuclear envelope (NE) is a key feature of nuclear genome architecture. Peripheral localization of telomeres is important for chromatin silencing, telomere replication and for the control of inappropriate recombination. Here, we report that fission yeast quiescent cells harbor predominantly a single telomeric cluster anchored to the NE. Telomere cluster association to the NE relies on Rap1-Bqt4 interaction, which is impacted by the length of telomeric sequences. In quiescent cells, reducing telomere length or deleting bqt4, both result in an increase in transcription of the telomeric repeat-containing RNA (TERRA). In the absence of Bqt4, telomere shortening leads to deep increase in TERRA level and the concomitant formation of subtelomeric rearrangements (STEEx) that accumulate massively in quiescent cells. Taken together, our data demonstrate that Rap1-Bqt4-dependent telomere association to NE preserves telomere integrity in post-mitotic cells, preventing telomeric transcription and recombination. This defines the nuclear periphery as an area where recombination is restricted, creating a safe zone for telomeres of post-mitotic cells.
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Affiliation(s)
- Laetitia Maestroni
- CNRS, INSERM, Aix Marseille Univ, Institut Paoli-Calmettes, CRCM, Marseille, France. Equipe labellisée Ligue contre le Cancer, France
| | - Céline Reyes
- LBCMCP, Centre de Biologie Intégrative, Université de Toulouse, CNRS, UPS, 31062 Toulouse Cedex, France
| | - Mélina Vaurs
- CNRS, INSERM, Aix Marseille Univ, Institut Paoli-Calmettes, CRCM, Marseille, France. Equipe labellisée Ligue contre le Cancer, France
| | - Yannick Gachet
- LBCMCP, Centre de Biologie Intégrative, Université de Toulouse, CNRS, UPS, 31062 Toulouse Cedex, France
| | - Sylvie Tournier
- LBCMCP, Centre de Biologie Intégrative, Université de Toulouse, CNRS, UPS, 31062 Toulouse Cedex, France
| | - Vincent Géli
- CNRS, INSERM, Aix Marseille Univ, Institut Paoli-Calmettes, CRCM, Marseille, France. Equipe labellisée Ligue contre le Cancer, France
| | - Stéphane Coulon
- CNRS, INSERM, Aix Marseille Univ, Institut Paoli-Calmettes, CRCM, Marseille, France. Equipe labellisée Ligue contre le Cancer, France
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3
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Gomar-Alba M, Mendoza M. Modulation of Cell Identity by Modification of Nuclear Pore Complexes. Front Genet 2020; 10:1301. [PMID: 31969901 PMCID: PMC6960265 DOI: 10.3389/fgene.2019.01301] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Accepted: 11/26/2019] [Indexed: 11/17/2022] Open
Abstract
Nuclear pore complexes (NPCs) are protein assemblies that form channels across the nuclear envelope to mediate communication between the nucleus and the cytoplasm. Additionally, NPCs interact with chromatin and influence the position and expression of multiple genes. Interestingly, the composition of NPCs can vary in different cell-types, tissues, and developmental states. Here, we review recent findings suggesting that modifications of NPC composition, including post-translational modifications, play an instructive role in cell fate establishment. In particular, we focus on the role of cell-specific NPC deacetylation in asymmetrically dividing budding yeast, which modulates transport-dependent and transport-independent NPC functions to determine the time of commitment to a new division cycle in daughter cells. By modulating protein localization and gene expression, NPCs are therefore emerging as central regulators of cell identity.
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Affiliation(s)
- Mercè Gomar-Alba
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, Illkirch, France.,Centre National de la Recherche Scientifique, Illkirch, France.,Institut National de la Santé et de la Recherche Médicale, Illkirch, France.,Université de Strasbourg, Strasbourg, France
| | - Manuel Mendoza
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, Illkirch, France.,Centre National de la Recherche Scientifique, Illkirch, France.,Institut National de la Santé et de la Recherche Médicale, Illkirch, France.,Université de Strasbourg, Strasbourg, France
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4
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Rapoport A, Golovina EA, Gervais P, Dupont S, Beney L. Anhydrobiosis: Inside yeast cells. Biotechnol Adv 2019; 37:51-67. [DOI: 10.1016/j.biotechadv.2018.11.003] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Revised: 11/01/2018] [Accepted: 11/13/2018] [Indexed: 12/21/2022]
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de Bruyn Kops A, Burke JE, Guthrie C. Brr6 plays a role in gene recruitment and transcriptional regulation at the nuclear envelope. Mol Biol Cell 2018; 29:2578-2590. [PMID: 30133335 PMCID: PMC6254580 DOI: 10.1091/mbc.e18-04-0258] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
Correlation between transcriptional regulation and positioning of genes at the nuclear envelope is well established in eukaryotes, but the mechanisms involved are not well understood. We show that brr6-1, a mutant of the essential yeast envelope transmembrane protein Brr6p, impairs normal positioning and expression of the PAB1 and FUR4-GAL1,10,7 loci. Similarly, expression of a dominant negative nucleoplasmic Brr6 fragment in wild-type cells reproduced many of the brr6-1 effects. Histone chromatin immunoprecipitation (ChIP) experiments showed decreased acetylation at the key histone H4K16 residue in the FUR4-GAL1,10,7 region in brr6-1. Importantly, blocking deacetylation significantly suppressed selected brr6-1 phenotypes. ChIPseq with FLAG-tagged Brr6 fragments showed enrichment at FUR4 and several other genes that showed striking changes in brr6-1 RNAseq data. These associations depended on a Brr6 putative zinc finger domain. Importantly, artificially tethering the GAL1 locus to the envelope suppressed the brr6-1 effects on GAL1 and FUR4 expression and increased H4K16 acetylation between GAL1 and FUR4 in the mutant. Together these results argue that Brr6 interacts with chromatin, helping to maintain normal chromatin architecture and transcriptional regulation of certain loci at the nuclear envelope.
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Affiliation(s)
- Anne de Bruyn Kops
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA 94143
| | - Jordan E Burke
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA 94143
| | - Christine Guthrie
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA 94143
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6
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Blank spots on the map: some current questions on nuclear organization and genome architecture. Histochem Cell Biol 2018; 150:579-592. [PMID: 30238154 DOI: 10.1007/s00418-018-1726-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/10/2018] [Indexed: 12/11/2022]
Abstract
The past decades have provided remarkable insights into how the eukaryotic cell nucleus and the genome within it are organized. The combined use of imaging, biochemistry and molecular biology approaches has revealed several basic principles of nuclear architecture and function, including the existence of chromatin domains of various sizes, the presence of a large number of non-membranous intranuclear bodies, non-random positioning of genes and chromosomes in 3D space, and a prominent role of the nuclear lamina in organizing genomes. Despite this tremendous progress in elucidating the biological properties of the cell nucleus, many questions remain. Here, we highlight some of the key open areas of investigation in the field of nuclear organization and genome architecture with a particular focus on the mechanisms and principles of higher-order genome organization, the emerging role of liquid phase separation in cellular organization, and the functional role of the nuclear lamina in physiological processes.
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7
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Dia N, Lavie L, Faye N, Méténier G, Yeramian E, Duroure C, Toguebaye BS, Frutos R, Niang MN, Vivarès CP, Ben Mamoun C, Cornillot E. Subtelomere organization in the genome of the microsporidian Encephalitozoon cuniculi: patterns of repeated sequences and physicochemical signatures. BMC Genomics 2016; 17:34. [PMID: 26744270 PMCID: PMC4704409 DOI: 10.1186/s12864-015-1920-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2015] [Accepted: 09/11/2015] [Indexed: 12/23/2022] Open
Abstract
Background The microsporidian Encephalitozoon cuniculi is an obligate intracellular eukaryotic pathogen with a small nuclear genome (2.9 Mbp) consisting of 11 chromosomes. Although each chromosome end is known to contain a single rDNA unit, the incomplete assembly of subtelomeric regions following sequencing of the genome identified only 3 of the 22 expected rDNA units. While chromosome end assembly remains a difficult process in most eukaryotic genomes, it is of significant importance for pathogens because these regions encode factors important for virulence and host evasion. Results Here we report the first complete assembly of E. cuniculi chromosome ends, and describe a novel mosaic structure of segmental duplications (EXT repeats) in these regions. EXT repeats range in size between 3.5 and 23.8 kbp and contain four multigene families encoding membrane associated proteins. Twenty-one recombination sites were identified in the sub-terminal region of E. cuniculi chromosomes. Our analysis suggests that these sites contribute to the diversity of chromosome ends organization through Double Strand Break repair mechanisms. The region containing EXT repeats at chromosome extremities can be differentiated based on gene composition, GC content, recombination sites density and chromosome landscape. Conclusion Together this study provides the complete structure of the chromosome ends of E. cuniculi GB-M1, and identifies important factors, which could play a major role in parasite diversity and host-parasite interactions. Comparison with other eukaryotic genomes suggests that terminal regions could be distinguished precisely based on gene content, genetic instability and base composition biais. The diversity of processes assciated with chromosome extremities and their biological consequences, as they are presented in the present study, emphasize the fact that great effort will be necessary in the future to characterize more carefully these regions during whole genome sequencing efforts. Electronic supplementary material The online version of this article (doi:10.1186/s12864-015-1920-7) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Ndongo Dia
- Unité de Virologie Médicale, Institut Pasteur de Dakar, 36 Avenue Pasteur, B.P. 220, Dakar, Sénégal.
| | - Laurence Lavie
- Clermont Université, Université Blaise Pascal, Laboratoire Microorganismes, Génome et Environnement, UMR 6023, CNRS, 63177, Aubière, France.
| | - Ngor Faye
- Laboratoire de Parasitologie Générale, Département de Biologie Animale, Faculté des Sciences et Technologies, Université Cheikh Anta Diop, Dakar, Sénégal.
| | - Guy Méténier
- Clermont Université, Université Blaise Pascal, Laboratoire Microorganismes, Génome et Environnement, UMR 6023, CNRS, 63177, Aubière, France.
| | - Edouard Yeramian
- Unité de Bioinformatique Structurale, UMR 3528 CNRS, Institut Pasteur, 25-28, rue du Dr Roux, 75015, Paris, France.
| | - Christophe Duroure
- Laboratoire de Météorologie Physique, OPGC UMR 6016 CNRS-Université Blaise Pascal, 24 Avenue des Landais, 63177, Aubière Cedex, France.
| | - Bhen S Toguebaye
- Laboratoire de Parasitologie Générale, Département de Biologie Animale, Faculté des Sciences et Technologies, Université Cheikh Anta Diop, Dakar, Sénégal.
| | - Roger Frutos
- CIRAD, UMR 17, Cirad-Ird, TA-A17/G, Campus International de Baillarguet, 34398, Montpellier, France.
| | - Mbayame N Niang
- Unité de Virologie Médicale, Institut Pasteur de Dakar, 36 Avenue Pasteur, B.P. 220, Dakar, Sénégal.
| | - Christian P Vivarès
- Clermont Université, Université Blaise Pascal, Laboratoire Microorganismes, Génome et Environnement, UMR 6023, CNRS, 63177, Aubière, France.
| | - Choukri Ben Mamoun
- Section of Infectious Disease and Department of Microbial Pathogenesis, Winchester Building WWW403D, Yale School of Medicine, 15 York St., New Haven, CT, 06520, USA.
| | - Emmanuel Cornillot
- Institut de Recherche en Cancérologie de Montpellier, IRCM - INSERM U1194 & Université de Montpellier & ICM, Institut régional du Cancer Montpellier, Campus Val d'Aurelle, 34298, Montpellier cedex 5, France. .,Institut de Biologie Computationnelle, IBC, Campus Saint Priest, 34090, Montpellier, France.
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8
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Tumor suppressor control of the cancer stem cell niche. Oncogene 2015; 35:4165-78. [PMID: 26686086 DOI: 10.1038/onc.2015.475] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2015] [Revised: 10/23/2015] [Accepted: 11/09/2015] [Indexed: 01/09/2023]
Abstract
Mammary stem cells (MSCs) expansion is associated with aggressive human breast cancer. The nuclear receptor peroxisome proliferator activated receptor γ (PPARγ) is a breast cancer tumor suppressor, but the mechanisms of this suppression are not completely characterized. To determine whether PPARγ regulates MSC expansion in mammary cancer, we deleted PPARγ expression in the mammary epithelium of an in vivo model of basal breast cancer. Loss of PPARγ expression reduced tumor latency, and expanded the CD24+/CD49f(hi) MSC population. PPARγ-null mammary tumors exhibited increased angiogenesis, which was detected in human breast cancer. In vivo inhibition of a PPARγ-regulated miR-15a/angiopoietin-1 pathway blocked increased angiogenesis and MSC expansion. PPARγ bound and activated a canonical response element in the miR-15a gene. PPARγ-null tumors were sensitive to the targeted anti-angiogenic drug sunitinib but resistant to cytotoxic chemotherapy. Normalization of tumor vasculature with sunitinib resulted in objective response to cytotoxic chemotherapy. Chemotherapy-treated PPARγ-null mammary tumors exhibited luminal phenotype and expansion of unipotent CD61+ luminal progenitor cells. Transplantation of chemotherapy-treated luminal progenitor cells recapitulated the luminal phenotype. These results have important implications for anti-angiogenic therapy in breast cancer patients.
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9
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The biological functions of Naa10 - From amino-terminal acetylation to human disease. Gene 2015; 567:103-31. [PMID: 25987439 DOI: 10.1016/j.gene.2015.04.085] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Revised: 04/20/2015] [Accepted: 04/27/2015] [Indexed: 01/07/2023]
Abstract
N-terminal acetylation (NTA) is one of the most abundant protein modifications known, and the N-terminal acetyltransferase (NAT) machinery is conserved throughout all Eukarya. Over the past 50 years, the function of NTA has begun to be slowly elucidated, and this includes the modulation of protein-protein interaction, protein-stability, protein function, and protein targeting to specific cellular compartments. Many of these functions have been studied in the context of Naa10/NatA; however, we are only starting to really understand the full complexity of this picture. Roughly, about 40% of all human proteins are substrates of Naa10 and the impact of this modification has only been studied for a few of them. Besides acting as a NAT in the NatA complex, recently other functions have been linked to Naa10, including post-translational NTA, lysine acetylation, and NAT/KAT-independent functions. Also, recent publications have linked mutations in Naa10 to various diseases, emphasizing the importance of Naa10 research in humans. The recent design and synthesis of the first bisubstrate inhibitors that potently and selectively inhibit the NatA/Naa10 complex, monomeric Naa10, and hNaa50 further increases the toolset to analyze Naa10 function.
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10
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Bianchi A, Lanzuolo C. Into the chromatin world: Role of nuclear architecture in epigenome regulation. AIMS BIOPHYSICS 2015. [DOI: 10.3934/biophy.2015.4.585] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
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11
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Sazer S, Lynch M, Needleman D. Deciphering the evolutionary history of open and closed mitosis. Curr Biol 2014; 24:R1099-103. [PMID: 25458223 DOI: 10.1016/j.cub.2014.10.011] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
The origin of the nucleus at the prokaryote-to-eukaryote transition represents one of the most important events in the evolution of cellular organization. The nuclear envelope encircles the chromosomes in interphase and is a selectively permeable barrier between the nucleoplasm and cytoplasm and an organizational scaffold for the nucleus. It remains intact in the 'closed' mitosis of some yeasts, but loses its integrity in the 'open' mitosis of mammals. Instances of both types of mitosis within two evolutionary clades indicate multiple evolutionary transitions between open and closed mitosis, although the underlying genetic changes that influenced these transitions remain unknown. A survey of the diversity of mitotic nuclei that fall between these extremes is the starting point from which to determine the physiologically relevant characteristics distinguishing open from closed mitosis and to understand how they evolved and why they are retained in present-day organisms. The field is now poised to begin addressing these issues by defining and documenting patterns of mitotic nuclear variation within and among species and mapping them onto a phylogenic tree. Deciphering the evolutionary history of open and closed mitosis will complement cell biological and genetic approaches aimed at deciphering the fundamental organizational principles of the nucleus.
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Affiliation(s)
- Shelley Sazer
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, and Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX 77030, USA.
| | - Michael Lynch
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
| | - Daniel Needleman
- School of Engineering and Applied Sciences, and Department of Molecular and Cellular Biology, and FAS Center for Systems Biology, Harvard University, Cambridge, MA 02138, USA
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12
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Riedmann EM. Landes Highlights. RNA Biol 2014. [DOI: 10.4161/rna.26483] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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13
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Abstract
Integral nuclear pore proteins associate with subsets of snoRNA and tRNA genes transcribed by RNA polymerase III and promote 3′ transcript processing in nematodes.
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14
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Padeken J, Heun P. Nucleolus and nuclear periphery: velcro for heterochromatin. Curr Opin Cell Biol 2014; 28:54-60. [PMID: 24690547 DOI: 10.1016/j.ceb.2014.03.001] [Citation(s) in RCA: 125] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2013] [Revised: 03/06/2014] [Accepted: 03/08/2014] [Indexed: 01/09/2023]
Abstract
Heterochromatin was first defined by Emil Heitz in 1928 by light microscopy. In the 1950s electron microscopy studies revealed that heterochromatin preferentially localizes to the nuclear periphery and around the nucleolus. While the use of genomic approaches led to the genome wide identification of lamina-associated and nucleolus-associated chromatin domains (LADs, NADs), recent studies now shed light on the processes mediating this topology and its dynamics. The identification of different factors on all regulatory levels, such as transcription factors, histone modifications, chromatin proteins, DNA sequences and non-coding RNAs, suggests the involvement of multiple distinct tethering pathways. Positioning at these nuclear sub-compartments is often but not always associated with transcriptional silencing, underlining the importance of the pre-existing chromatin context.
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Affiliation(s)
- Jan Padeken
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse, 66, 4058 Basel, Switzerland
| | - Patrick Heun
- Max Planck Institute of Immunobiology and Epigenetics, Stübeweg 51, 79108 Freiburg, Germany.
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15
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Ptak C, Aitchison JD, Wozniak RW. The multifunctional nuclear pore complex: a platform for controlling gene expression. Curr Opin Cell Biol 2014; 28:46-53. [PMID: 24657998 DOI: 10.1016/j.ceb.2014.02.001] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2014] [Revised: 02/21/2014] [Accepted: 02/22/2014] [Indexed: 12/21/2022]
Abstract
In addition to their established roles in nucleocytoplasmic transport, the intimate association of nuclear pore complexes (NPCs) with chromatin has long led to speculation that these structures influence peripheral chromatin structure and regulate gene expression. These ideas have their roots in morphological observations, however recent years have seen the identification of physical interactions between NPCs, chromatin, and the transcriptional machinery. Key insights into the molecular functions of specific NPC proteins have uncovered roles for these proteins in transcriptional activation and elongation, mRNA processing, as well as chromatin structure and localization. Here, we review recent studies that provide further molecular detail on the role of specific NPC components as distinct platforms for these chromatin dependent processes.
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Affiliation(s)
- Christopher Ptak
- Department of Cell Biology, University of Alberta, Edmonton, Alberta T6G 2H7, Canada
| | - John D Aitchison
- Seattle Biomedical Research Institute and Institute for Systems Biology, 307 Westlake Ave N, Seattle, WA 98109, USA.
| | - Richard W Wozniak
- Department of Cell Biology, University of Alberta, Edmonton, Alberta T6G 2H7, Canada.
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Abstract
In eukaryotes, the function of the cell's nucleus has primarily been considered to be the repository for the organism's genome. However, this rather simplistic view is undergoing a major shift, as it is increasingly apparent that the nucleus has functions extending beyond being a mere genome container. Recent findings have revealed that the structural composition of the nucleus changes during development and that many of these components exhibit cell- and tissue-specific differences. Increasing evidence is pointing to the nucleus being integral to the function of the interphase cytoskeleton, with changes to nuclear structural proteins having ramifications affecting cytoskeletal organization and the cell's interactions with the extracellular environment. Many of these functions originate at the nuclear periphery, comprising the nuclear envelope (NE) and underlying lamina. Together, they may act as a "hub" in integrating cellular functions including chromatin organization, transcriptional regulation, mechanosignaling, cytoskeletal organization, and signaling pathways. Interest in such an integral role has been largely stimulated by the discovery that many diseases and anomalies are caused by defects in proteins of the NE/lamina, the nuclear envelopathies, many of which, though rare, are providing insights into their more common variants that are some of the major issues of the twenty-first century public health. Here, we review the contributions that mouse mutants have made to our current understanding of the NE/lamina, their respective roles in disease and the use of mice in developing potential therapies for treating the diseases.
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17
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Collas P, Lund EG, Oldenburg AR. Closing the (nuclear) envelope on the genome: how nuclear lamins interact with promoters and modulate gene expression. Bioessays 2013; 36:75-83. [PMID: 24272858 DOI: 10.1002/bies.201300138] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The nuclear envelope shapes the functional organization of the nucleus. Increasing evidence indicates that one of its main components, the nuclear lamina, dynamically interacts with the genome, including the promoter region of specific genes. This seems to occur in a manner that accords developmental significance to these interactions. This essay addresses key issues raised by recent data on the association of nuclear lamins with the genome. We discuss how lamins interact with large chromatin domains and with spatially restricted regions on gene promoters. We address the relationship between these interactions, chromatin modifications and gene expression outcomes. Lamin-genome contacts are redistributed after cell division and during stem cell differentiation, with evidence of lineage specificity. Thus, we also speculate on a developmental role of lamin interactions with specific genes. Finally, we highlight how concepts arising from this recent work lay the foundations of future challenges and investigations.
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Affiliation(s)
- Philippe Collas
- Stem Cell Epigenetics Laboratory, Faculty of Medicine, Institute of Basic Medical Sciences, Norwegian Center for Stem Cell Research, University of Oslo, Oslo, Norway
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Katta SS, Smoyer CJ, Jaspersen SL. Destination: inner nuclear membrane. Trends Cell Biol 2013; 24:221-9. [PMID: 24268652 DOI: 10.1016/j.tcb.2013.10.006] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2013] [Revised: 10/21/2013] [Accepted: 10/22/2013] [Indexed: 12/25/2022]
Abstract
The inner nuclear membrane (INM) of eukaryotic cells is enriched in proteins that are required for nuclear structure, chromosome organization, DNA repair, and transcriptional control. Mislocalization of INM proteins is observed in a wide spectrum of human diseases; however, the mechanism by which INM proteins reach their final destination is poorly understood. In this review we discuss how investigating INM composition, dissecting targeting pathways of conserved INM proteins in multiple systems and analyzing the nuclear transport of viruses and signaling complexes have broadened our knowledge of INM transport to include both nuclear pore complex-dependent and -independent pathways. The study of these INM targeting pathways is important to understanding nuclear organization and in both normal and diseased cells.
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Affiliation(s)
| | | | - Sue L Jaspersen
- Stowers Institute for Medical Research, Kansas City, MO 64110, USA; Department of Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City, KS 66160, USA.
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