1
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Perales IE, Jones SD, Piaszynski KM, Geyer PK. Developmental changes in nuclear lamina components during germ cell differentiation. Nucleus 2024; 15:2339214. [PMID: 38597409 PMCID: PMC11008544 DOI: 10.1080/19491034.2024.2339214] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2024] [Accepted: 04/02/2024] [Indexed: 04/11/2024] Open
Abstract
The nuclear lamina (NL) changes composition for regulation of nuclear events. We investigated changes that occur in Drosophila oogenesis, revealing switches in NL composition during germ cell differentiation. Germline stem cells (GSCs) express only LamB and predominantly emerin, whereas differentiating nurse cells predominantly express LamC and emerin2. A change in LamC-specific localization also occurs, wherein phosphorylated LamC redistributes to the nuclear interior only in the oocyte, prior to transcriptional reactivation of the meiotic genome. These changes support existing concepts that LamC promotes differentiation, a premise that was tested. Remarkably ectopic LamC production in GSCs did not promote premature differentiation. Increased LamC levels in differentiating germ cells altered internal nuclear structure, increased RNA production, and reduced female fertility due to defects in eggshell formation. These studies suggest differences between Drosophila lamins are regulatory, not functional, and reveal an unexpected robustness to level changes of a major scaffolding component of the NL.
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Affiliation(s)
- Isabella E. Perales
- Department of Biochemistry and Molecular Biology, University of Iowa, Iowa City, IA, USA
| | - Samuel D. Jones
- Department of Biochemistry and Molecular Biology, University of Iowa, Iowa City, IA, USA
| | | | - Pamela K. Geyer
- Department of Biochemistry and Molecular Biology, University of Iowa, Iowa City, IA, USA
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2
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Stephens RK, Miroshnikova YA. Nuclear periphery and its mechanical regulation in cell fate transitions. Curr Opin Struct Biol 2024; 87:102867. [PMID: 38889500 DOI: 10.1016/j.sbi.2024.102867] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2023] [Revised: 05/22/2024] [Accepted: 05/27/2024] [Indexed: 06/20/2024]
Abstract
Cell fate changes require rewiring of transcriptional programs to generate functionally specialized cell states. Reconfiguration of transcriptional networks requires overcoming epigenetic barriers imposed by silenced heterochromatin in order to activate lineage-specific genes. Further, cell fate decisions are made in a tissue-specific context, where cells are physically linked to each other as well as to the connective tissue environment. Here, cells are continuously exposed to a multitude of mechanical forces emanating from cellular dynamics in their local microenvironments, for example through cell movements, cell divisions, tissue contractions, or fluid flow. Through their ability to deform cellular structures and activate receptors, mechanical forces can be sensed at the plasma membrane, but also at the nuclear periphery through direct or cytoskeleton-mediated deformation of the nuclear envelope. This deformation and the associated signaling is capable of triggering changes in the mechanical state of the nuclear membranes, the organization and rigidity of the underlying nuclear lamina, compaction state of chromatin, and ultimately transcription. This review focuses on the role of nuclear architecture, particularly the nuclear lamina-chromatin interface, and its mechanical regulation in cell fate decisions as well as its physiological role in development and cellular reprogramming.
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Affiliation(s)
- Rebecca K Stephens
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, 20892, USA. https://twitter.com/BecKateStephens
| | - Yekaterina A Miroshnikova
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, 20892, USA.
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3
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Sobo JM, Alagna NS, Sun SX, Wilson KL, Reddy KL. Lamins: The backbone of the nucleocytoskeleton interface. Curr Opin Cell Biol 2024; 86:102313. [PMID: 38262116 DOI: 10.1016/j.ceb.2023.102313] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Revised: 12/14/2023] [Accepted: 12/15/2023] [Indexed: 01/25/2024]
Abstract
The nuclear lamina (NL) is a crucial component of the inner nuclear membrane (INM) and consists of lamin filaments and associated proteins. Lamins are type V intermediate filament proteins essential for maintaining the integrity and mechanical properties of the nucleus. In human cells, 'B-type' lamins (lamin B1 and lamin B2) are ubiquitously expressed, while 'A-type' lamins (lamin A, lamin C, and minor isoforms) are expressed in a tissue- and development-specific manner. Lamins homopolymerize to form filaments that localize primarily near the INM, but A-type lamins also localize to and function in the nucleoplasm. Lamins play central roles in the assembly, structure, positioning, and mechanics of the nucleus, modulating cell signaling and influencing development, differentiation, and other activities. This review highlights recent findings on the structure and regulation of lamin filaments, providing insights into their multifaceted functions, including their role as "mechanosensors", delving into the emerging significance of lamin filaments as vital links between cytoskeletal and nuclear structures, chromatin organization, and the genome.
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Affiliation(s)
- Joan M Sobo
- Department of Biological Chemistry, Center for Epigenetics, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Nicholas S Alagna
- Department of Biological Chemistry, Center for Epigenetics, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Sean X Sun
- Department of Mechanical Engineering, Whiting School of Engineering, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Katherine L Wilson
- Department of Cell Biology, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Karen L Reddy
- Department of Biological Chemistry, Center for Epigenetics, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA; Sidney Kimmel Comprehensive Cancer Center, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA.
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4
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Gabrielle M, Rohacs T. TMEM120A/TACAN: A putative regulator of ion channels, mechanosensation, and lipid metabolism. Channels (Austin) 2023; 17:2237306. [PMID: 37523628 PMCID: PMC10392765 DOI: 10.1080/19336950.2023.2237306] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Revised: 06/19/2023] [Accepted: 07/12/2023] [Indexed: 08/02/2023] Open
Abstract
TMEM120A (TACAN) is an enigmatic protein with several seemingly unconnected functions. It was proposed to be an ion channel involved in sensing mechanical stimuli, and knockdown/knockout experiments have implicated that TMEM120A may be necessary for sensing mechanical pain. TMEM120A's ion channel function has subsequently been challenged, as attempts to replicate electrophysiological experiments have largely been unsuccessful. Several cryo-EM structures revealed TMEM120A is structurally homologous to a lipid modifying enzyme called Elongation of Very Long Chain Fatty Acids 7 (ELOVL7). Although TMEM120A's channel function is debated, it still seems to affect mechanosensation by inhibiting PIEZO2 channels and by modifying tactile pain responses in animal models. TMEM120A was also shown to inhibit polycystin-2 (PKD2) channels through direct physical interaction. Additionally, TMEM120A has been implicated in adipocyte regulation and in innate immune response against Zika virus. The way TMEM120A is proposed to alter each of these processes ranges from regulating gene expression, acting as a lipid modifying enzyme, and controlling subcellular localization of other proteins through direct binding. Here, we examine TMEM120A's structure and proposed functions in diverse physiological contexts.
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Affiliation(s)
- Matthew Gabrielle
- Department of Pharmacology, Physiology and Neuroscience, Rutgers, New Jersey Medical School, Newark, NJ, USA
| | - Tibor Rohacs
- Department of Pharmacology, Physiology and Neuroscience, Rutgers, New Jersey Medical School, Newark, NJ, USA
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5
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Alagna NS, Thomas TI, Wilson KL, Reddy KL. Choreography of lamina-associated domains: structure meets dynamics. FEBS Lett 2023; 597:2806-2822. [PMID: 37953467 PMCID: PMC10858991 DOI: 10.1002/1873-3468.14771] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2023] [Revised: 09/13/2023] [Accepted: 09/17/2023] [Indexed: 11/14/2023]
Abstract
Lamina-associated domains are large regions of heterochromatin positioned at the nuclear periphery. These domains have been implicated in gene repression, especially in the context of development. In mammals, LAD organization is dependent on nuclear lamins, inner nuclear membrane proteins, and chromatin state. In addition, chromatin readers and modifier proteins have been implicated in this organization, potentially serving as molecular tethers that interact with both nuclear envelope proteins and chromatin. More recent studies have focused on teasing apart the rules that govern dynamic LAD organization and how LAD organization, in turn, relates to gene regulation and overall 3D genome organization. This review highlights recent studies in mammalian cells uncovering factors that instruct the choreography of LAD organization, re-organization, and dynamics at the nuclear lamina, including LAD dynamics in interphase and through mitotic exit, when LAD organization is re-established, as well as intra-LAD subdomain variations.
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Affiliation(s)
- Nicholas S. Alagna
- Department of Biological Chemistry, Center for Epigenetics, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Tiera I. Thomas
- Department of Biological Chemistry, Center for Epigenetics, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Katherine L. Wilson
- Department of Cell Biology, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Karen L. Reddy
- Department of Biological Chemistry, Center for Epigenetics, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA
- Sidney Kimmel Comprehensive Cancer Center, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA
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6
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Del Rosario JS, Gabrielle M, Yudin Y, Rohacs T. TMEM120A/TACAN inhibits mechanically activated PIEZO2 channels. J Gen Physiol 2022; 154:213349. [PMID: 35819364 PMCID: PMC9280072 DOI: 10.1085/jgp.202213164] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Accepted: 06/24/2022] [Indexed: 01/14/2023] Open
Abstract
PIEZO2 channels mediate rapidly adapting mechanically activated currents in peripheral sensory neurons of the dorsal root ganglia (DRG), and they are indispensable for light touch and proprioception. Relatively little is known about what other proteins regulate PIEZO2 activity in a cellular context. TMEM120A (TACAN) was proposed to act as a high threshold mechanically activated ion channel in nociceptive DRG neurons. Here, we find that Tmem120a coexpression decreased the amplitudes of mechanically activated PIEZO2 currents and increased their threshold of activation. TMEM120A did not inhibit mechanically activated PIEZO1 and TREK1 channels and TMEM120A alone did not result in the appearance of mechanically activated currents above background. Tmem120a and Piezo2 expression in mouse DRG neurons overlapped, and siRNA-mediated knockdown of Tmem120a increased the amplitudes of rapidly adapting mechanically activated currents and decreased their thresholds to mechanical activation. Our data identify TMEM120A as a negative modulator of PIEZO2 channel activity, and do not support TMEM120A being a mechanically activated ion channel.
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Affiliation(s)
- John Smith Del Rosario
- Department of Pharmacology, Physiology and Neuroscience, Rutgers New Jersey Medical School, Newark, NJ
| | - Matthew Gabrielle
- Department of Pharmacology, Physiology and Neuroscience, Rutgers New Jersey Medical School, Newark, NJ
| | - Yevgen Yudin
- Department of Pharmacology, Physiology and Neuroscience, Rutgers New Jersey Medical School, Newark, NJ
| | - Tibor Rohacs
- Department of Pharmacology, Physiology and Neuroscience, Rutgers New Jersey Medical School, Newark, NJ,Correspondence to Tibor Rohacs:
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7
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To be or not be (in the LAD): emerging roles of lamin proteins in transcriptional regulation. Biochem Soc Trans 2022; 50:1035-1044. [PMID: 35437578 PMCID: PMC9162450 DOI: 10.1042/bst20210858] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2021] [Revised: 03/29/2022] [Accepted: 03/30/2022] [Indexed: 12/21/2022]
Abstract
Lamins are components of the nuclear lamina, a protein meshwork that underlies the nuclear membrane. Lamins interact with chromatin in transcriptionally silent regions defined as lamina-associated-domains (LADs). However, recent studies have shown that lamins regulate active transcription inside LADs. In addition, ChIP-seq analysis has shown that lamins interact with lamin-dependent promoters and enhancers located in the interior of the nucleus. Moreover, functional studies suggest that lamins regulate transcription at associated-promoters and long-range chromatin interactions of key developmental gene programs. This review will discuss emerging, non-canonical functions of lamins in controlling non-silent genes located both inside and outside of LADs, focusing on transcriptional regulation and chromatin organization in Drosophila and mammals as metazoan model organisms.
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8
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Qian N, Li S, Tan X. The curious case of TMEM120A: Mechanosensor, fat regulator, or antiviral defender? Bioessays 2022; 44:e2200045. [PMID: 35419854 DOI: 10.1002/bies.202200045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Revised: 03/17/2022] [Accepted: 03/23/2022] [Indexed: 11/06/2022]
Abstract
Mechanical pain sensing, adipogenesis, and STING-dependent innate immunity seem three distinct biological processes without substantial relationships. Intriguingly, TMEM120A, a transmembrane protein, has been shown to detect mechanical pain stimuli as a mechanosensitive channel, contribute to adipocyte differentiation/function by regulating genome organization and promote STING trafficking to active cellular innate immune response. However, the role of TMEM120A as a mechanosensitive channel was challenged by recent studies which cannot reproduce data supporting its role in mechanosensing. Furthermore, the molecular mechanism by which TMEM120A contributes to adipocyte differentiation/function and promotes STING trafficking remains elusive. In this review, we discuss these multiple proposed functions of TMEM120A and hypothesize the molecular mechanism underlying TMEM120A's role in fatty acid metabolism and STING signaling.
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Affiliation(s)
- Nianchao Qian
- Beijing Advanced Innovation Center for Structural Biology, Beijing Frontier Research Center for Biological Structure, MOE Key Laboratory of Bioorganic Phosphorus Chemistry & Chemical Biology, School of Pharmaceutical Sciences, Tsinghua University, Beijing, China
| | - Shuo Li
- Beijing Advanced Innovation Center for Structural Biology, Beijing Frontier Research Center for Biological Structure, MOE Key Laboratory of Bioorganic Phosphorus Chemistry & Chemical Biology, School of Pharmaceutical Sciences, Tsinghua University, Beijing, China
| | - Xu Tan
- Beijing Advanced Innovation Center for Structural Biology, Beijing Frontier Research Center for Biological Structure, MOE Key Laboratory of Bioorganic Phosphorus Chemistry & Chemical Biology, School of Pharmaceutical Sciences, Tsinghua University, Beijing, China.,Tsinghua-Peking Center for Life Sciences, Beijing, China.,Center for Infectious Disease Research, School of Medicine, Tsinghua University, Beijing, China
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9
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Abstract
Lamins interact with a host of nuclear membrane proteins, transcription factors, chromatin regulators, signaling molecules, splicing factors, and even chromatin itself to form a nuclear subcompartment, the nuclear lamina, that is involved in a variety of cellular processes such as the governance of nuclear integrity, nuclear positioning, mitosis, DNA repair, DNA replication, splicing, signaling, mechanotransduction and -sensation, transcriptional regulation, and genome organization. Lamins are the primary scaffold for this nuclear subcompartment, but interactions with lamin-associated peptides in the inner nuclear membrane are self-reinforcing and mutually required. Lamins also interact, directly and indirectly, with peripheral heterochromatin domains called lamina-associated domains (LADs) and help to regulate dynamic 3D genome organization and expression of developmentally regulated genes.
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Affiliation(s)
- Xianrong Wong
- Laboratory of Developmental and Regenerative Biology, Skin Research Institute of Singapore, Agency for Science, Technology and Research (A∗STAR), Singapore 138648
| | - Ashley J Melendez-Perez
- Department of Biological Chemistry and Center for Epigenetics, Johns Hopkins University of Medicine, Baltimore, Maryland 21205, USA
| | - Karen L Reddy
- Department of Biological Chemistry and Center for Epigenetics, Johns Hopkins University of Medicine, Baltimore, Maryland 21205, USA
- Sidney Kimmel Cancer Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland 21231, USA
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10
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Czapiewski R, Batrakou DG, de Las Heras JI, Carter RN, Sivakumar A, Sliwinska M, Dixon CR, Webb S, Lattanzi G, Morton NM, Schirmer EC. Genomic loci mispositioning in Tmem120a knockout mice yields latent lipodystrophy. Nat Commun 2022; 13:321. [PMID: 35027552 PMCID: PMC8758788 DOI: 10.1038/s41467-021-27869-2] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Accepted: 12/19/2021] [Indexed: 12/13/2022] Open
Abstract
Little is known about how the observed fat-specific pattern of 3D-spatial genome organisation is established. Here we report that adipocyte-specific knockout of the gene encoding nuclear envelope transmembrane protein Tmem120a disrupts fat genome organisation, thus causing a lipodystrophy syndrome. Tmem120a deficiency broadly suppresses lipid metabolism pathway gene expression and induces myogenic gene expression by repositioning genes, enhancers and miRNA-encoding loci between the nuclear periphery and interior. Tmem120a-/- mice, particularly females, exhibit a lipodystrophy syndrome similar to human familial partial lipodystrophy FPLD2, with profound insulin resistance and metabolic defects that manifest upon exposure to an obesogenic diet. Interestingly, similar genome organisation defects occurred in cells from FPLD2 patients that harbour nuclear envelope protein encoding LMNA mutations. Our data indicate TMEM120A genome organisation functions affect many adipose functions and its loss may yield adiposity spectrum disorders, including a miRNA-based mechanism that could explain muscle hypertrophy in human lipodystrophy.
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Affiliation(s)
- Rafal Czapiewski
- Institute of Cell Biology, University of Edinburgh, Edinburgh, EH9 3BF, UK
| | - Dzmitry G Batrakou
- Institute of Cell Biology, University of Edinburgh, Edinburgh, EH9 3BF, UK
| | | | - Roderick N Carter
- Molecular Metabolism Group, University/BHF Centre for Cardiovascular Science, Queen's Medical Research Institute, University of Edinburgh, Edinburgh, EH16 4TJ, UK
| | | | | | - Charles R Dixon
- Institute of Cell Biology, University of Edinburgh, Edinburgh, EH9 3BF, UK
- Wellcome Centre for Cell Biology, University of Edinburgh, Edinburgh, EH9 3BF, UK
| | - Shaun Webb
- Wellcome Centre for Cell Biology, University of Edinburgh, Edinburgh, EH9 3BF, UK
| | - Giovanna Lattanzi
- CNR - National Research Council of Italy, Institute of Molecular Genetics "Luigi Luca Cavalli-Sforza", Unit of Bologna, Bologna, 40136, Italy
- IRCCS, Istituto Ortopedico Rizzoli, Bologna, 40136, Italy
| | - Nicholas M Morton
- Molecular Metabolism Group, University/BHF Centre for Cardiovascular Science, Queen's Medical Research Institute, University of Edinburgh, Edinburgh, EH16 4TJ, UK
| | - Eric C Schirmer
- Institute of Cell Biology, University of Edinburgh, Edinburgh, EH9 3BF, UK.
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11
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Bridger JM, Pereira RT, Pina C, Tosi S, Lewis A. Alterations to Genome Organisation in Stem Cells, Their Differentiation and Associated Diseases. Results Probl Cell Differ 2022; 70:71-102. [PMID: 36348105 DOI: 10.1007/978-3-031-06573-6_3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
The organisation of the genome in its home, the cell nucleus, is reliant on a number of different aspects to establish, maintain and alter its functional non-random positioning. The genome is dispersed throughout a cell nucleus in specific chromosome territories which are further divided into topologically associated domains (TADs), where regions of the genome from different and the same chromosomes come together. This organisation is both controlled by DNA and chromatin epigenetic modification and the association of the genome with nuclear structures such as the nuclear lamina, the nucleolus and nuclear bodies and speckles. Indeed, sequences that are associated with the first two structures mentioned are termed lamina-associated domains (LADs) and nucleolar-associated domains (NADs), respectively. The modifications and nuclear structures that regulate genome function are altered through a cell's life from stem cell to differentiated cell through to reversible quiescence and irreversible senescence, and hence impacting on genome organisation, altering it to silence specific genes and permit others to be expressed in a controlled way in different cell types and cell cycle statuses. The structures and enzymes and thus the organisation of the genome can also be deleteriously affected, leading to disease and/or premature ageing.
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Affiliation(s)
- Joanna M Bridger
- Division of Biosciences, Department of Life Sciences, Centre for Genome Engineering and Maintenance (cenGEM), College of Health, Medicine and Life Sciences, Brunel University London, Uxbridge, UK.
| | - Rita Torres Pereira
- Division of Biosciences, Department of Life Sciences, Centre for Genome Engineering and Maintenance (cenGEM), College of Health, Medicine and Life Sciences, Brunel University London, Uxbridge, UK
| | - Cristina Pina
- Division of Biosciences, Department of Life Sciences, Centre for Genome Engineering and Maintenance (cenGEM), College of Health, Medicine and Life Sciences, Brunel University London, Uxbridge, UK
| | - Sabrina Tosi
- Division of Biosciences, Department of Life Sciences, Centre for Genome Engineering and Maintenance (cenGEM), College of Health, Medicine and Life Sciences, Brunel University London, Uxbridge, UK
| | - Annabelle Lewis
- Division of Biosciences, Department of Life Sciences, Centre for Genome Engineering and Maintenance (cenGEM), College of Health, Medicine and Life Sciences, Brunel University London, Uxbridge, UK
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12
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Padilla-Mejia NE, Makarov AA, Barlow LD, Butterfield ER, Field MC. Evolution and diversification of the nuclear envelope. Nucleus 2021; 12:21-41. [PMID: 33435791 PMCID: PMC7889174 DOI: 10.1080/19491034.2021.1874135] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Revised: 12/08/2020] [Accepted: 12/11/2020] [Indexed: 02/06/2023] Open
Abstract
Eukaryotic cells arose ~1.5 billion years ago, with the endomembrane system a central feature, facilitating evolution of intracellular compartments. Endomembranes include the nuclear envelope (NE) dividing the cytoplasm and nucleoplasm. The NE possesses universal features: a double lipid bilayer membrane, nuclear pore complexes (NPCs), and continuity with the endoplasmic reticulum, indicating common evolutionary origin. However, levels of specialization between lineages remains unclear, despite distinct mechanisms underpinning various nuclear activities. Several distinct modes of molecular evolution facilitate organellar diversification and to understand which apply to the NE, we exploited proteomic datasets of purified nuclear envelopes from model systems for comparative analysis. We find enrichment of core nuclear functions amongst the widely conserved proteins to be less numerous than lineage-specific cohorts, but enriched in core nuclear functions. This, together with consideration of additional evidence, suggests that, despite a common origin, the NE has evolved as a highly diverse organelle with significant lineage-specific functionality.
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Affiliation(s)
- Norma E. Padilla-Mejia
- Division of Biological Chemistry and Drug Discovery, School of Life Sciences, University of Dundee, Dundee, UK
| | - Alexandr A. Makarov
- Division of Biological Chemistry and Drug Discovery, School of Life Sciences, University of Dundee, Dundee, UK
| | - Lael D. Barlow
- Division of Biological Chemistry and Drug Discovery, School of Life Sciences, University of Dundee, Dundee, UK
| | - Erin R. Butterfield
- Division of Biological Chemistry and Drug Discovery, School of Life Sciences, University of Dundee, Dundee, UK
| | - Mark C. Field
- Division of Biological Chemistry and Drug Discovery, School of Life Sciences, University of Dundee, Dundee, UK
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, České, Czech Republic
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13
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Gómez-Saldivar G, Glauser DA, Meister P. Tissue-specific DamID protocol using nanopore sequencing. J Biol Methods 2021; 8:e152. [PMID: 34514013 PMCID: PMC8411031 DOI: 10.14440/jbm.2021.362] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Revised: 05/05/2021] [Accepted: 05/12/2021] [Indexed: 11/23/2022] Open
Abstract
DNA adenine methylation identification (DamID) is a powerful method to determine DNA binding profiles of proteins at a genomic scale. The method leverages the fusion between a protein of interest and the Dam methyltransferase of E. coli, which methylates proximal DNA in vivo. Here, we present an optimized procedure, which was developed for tissue-specific analyses in Caenorhabditis elegans and successfully used to footprint genes actively transcribed by RNA polymerases and to map transcription factor binding in gene regulatory regions. The present protocol details C. elegans-specific steps involved in the preparation of transgenic lines and genomic DNA samples, as well as broadly applicable steps for the DamID procedure, including the isolation of methylated DNA fragments, the preparation of multiplexed libraries, Nanopore sequencing, and data analysis. Two distinctive features of the approach are (i) the use of an efficient recombination-based strategy to selectively analyze rare cell types and (ii) the use of Nanopore sequencing, which streamlines the process. The method allows researchers to go from genomic DNA samples to sequencing results in less than a week, while being sensitive enough to report reliable DNA footprints in cell types as rare as 2 cells per animal.
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Affiliation(s)
| | | | - Peter Meister
- Cell Fate and Nuclear Organization, Institute of Cell Biology, University of Bern, 3012 Bern, Switzerland
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14
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Mehta IS, Riyahi K, Pereira RT, Meaburn KJ, Figgitt M, Kill IR, Eskiw CH, Bridger JM. Interphase Chromosomes in Replicative Senescence: Chromosome Positioning as a Senescence Biomarker and the Lack of Nuclear Motor-Driven Chromosome Repositioning in Senescent Cells. Front Cell Dev Biol 2021; 9:640200. [PMID: 34113611 PMCID: PMC8185894 DOI: 10.3389/fcell.2021.640200] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Accepted: 02/25/2021] [Indexed: 01/10/2023] Open
Abstract
This study demonstrates, and confirms, that chromosome territory positioning is altered in primary senescent human dermal fibroblasts (HDFs). The chromosome territory positioning pattern is very similar to that found in HDFs made quiescent either by serum starvation or confluence; but not completely. A few chromosomes are found in different locations. One chromosome in particular stands out, chromosome 10, which is located in an intermediate location in young proliferating HDFs, but is found at the nuclear periphery in quiescent cells and in an opposing location of the nuclear interior in senescent HDFs. We have previously demonstrated that individual chromosome territories can be actively and rapidly relocated, with 15 min, after removal of serum from the culture media. These chromosome relocations require nuclear motor activity through the presence of nuclear myosin 1β (NM1β). We now also demonstrate rapid chromosome movement in HDFs after heat-shock at 42°C. Others have shown that heat shock genes are actively relocated using nuclear motor protein activity via actin or NM1β (Khanna et al., 2014; Pradhan et al., 2020). However, this current study reveals, that in senescent HDFs, chromosomes can no longer be relocated to expected nuclear locations upon these two types of stimuli. This coincides with a entirely different organisation and distribution of NM1β within senescent HDFs.
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Affiliation(s)
- Ishita S Mehta
- Centre for Genome Engineering and Maintenance, Division of Biosciences, Department of Life Sciences, College of Health, Medicine and Life Sciences, Kingston Lane, Brunel University London, Uxbridge, United Kingdom.,Tata Institute of Fundamental Research, Mumbai, India
| | - Kumars Riyahi
- Centre for Genome Engineering and Maintenance, Division of Biosciences, Department of Life Sciences, College of Health, Medicine and Life Sciences, Kingston Lane, Brunel University London, Uxbridge, United Kingdom
| | - Rita Torres Pereira
- Centre for Genome Engineering and Maintenance, Division of Biosciences, Department of Life Sciences, College of Health, Medicine and Life Sciences, Kingston Lane, Brunel University London, Uxbridge, United Kingdom
| | - Karen J Meaburn
- Centre for Genome Engineering and Maintenance, Division of Biosciences, Department of Life Sciences, College of Health, Medicine and Life Sciences, Kingston Lane, Brunel University London, Uxbridge, United Kingdom
| | - Martin Figgitt
- Centre for Genome Engineering and Maintenance, Division of Biosciences, Department of Life Sciences, College of Health, Medicine and Life Sciences, Kingston Lane, Brunel University London, Uxbridge, United Kingdom.,Department of Life Sciences, Birmingham City University, Birmingham, United Kingdom
| | - Ian R Kill
- Centre for Genome Engineering and Maintenance, Division of Biosciences, Department of Life Sciences, College of Health, Medicine and Life Sciences, Kingston Lane, Brunel University London, Uxbridge, United Kingdom
| | - Christopher H Eskiw
- Department of Food and Bioproduct Sciences, University of Saskatchewan, Saskatoon, SK, Canada
| | - Joanna M Bridger
- Centre for Genome Engineering and Maintenance, Division of Biosciences, Department of Life Sciences, College of Health, Medicine and Life Sciences, Kingston Lane, Brunel University London, Uxbridge, United Kingdom
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15
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Hoskins VE, Smith K, Reddy KL. The shifting shape of genomes: dynamics of heterochromatin interactions at the nuclear lamina. Curr Opin Genet Dev 2021; 67:163-173. [PMID: 33774266 PMCID: PMC8489734 DOI: 10.1016/j.gde.2021.02.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Revised: 01/26/2021] [Accepted: 02/02/2021] [Indexed: 12/12/2022]
Abstract
The nucleus is a highly structured organelle with many chromatin and protein compartments that partition the genome into regulatory domains. One such a compartment within the mammalian nucleus is the microenvironment underlying the nuclear envelope (NE) where intermediate filament proteins, lamins, act as a link between cytoskeletal and inner nuclear membrane (INM) proteins, chromatin binders and modifiers, and heterochromatin. These dynamic interactions regulate many cellular processes and, when they are perturbed, can lead to genome dysregulation and disease.
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Affiliation(s)
- Victoria E Hoskins
- Johns Hopkins University, School of Medicine, Center for Epigenetics, Department of Biological Chemistry, Baltimore, MD 21205, United States
| | - Kristiana Smith
- Johns Hopkins University, School of Medicine, Center for Epigenetics, Department of Biological Chemistry, Baltimore, MD 21205, United States
| | - Karen L Reddy
- Johns Hopkins University, School of Medicine, Center for Epigenetics, Department of Biological Chemistry, Baltimore, MD 21205, United States; Sidney Kimmel Cancer Institute, Johns Hopkins University, School of Medicine, Baltimore, MD 21205, United States; Johns Hopkins University, School of Medicine, Department of Medicine, Baltimore, MD 21205, United States.
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16
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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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17
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The nuclear envelope protein Net39 is essential for muscle nuclear integrity and chromatin organization. Nat Commun 2021; 12:690. [PMID: 33514739 PMCID: PMC7846557 DOI: 10.1038/s41467-021-20987-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Accepted: 12/24/2020] [Indexed: 01/14/2023] Open
Abstract
Lamins and transmembrane proteins within the nuclear envelope regulate nuclear structure and chromatin organization. Nuclear envelope transmembrane protein 39 (Net39) is a muscle nuclear envelope protein whose functions in vivo have not been explored. We show that mice lacking Net39 succumb to severe myopathy and juvenile lethality, with concomitant disruption in nuclear integrity, chromatin accessibility, gene expression, and metabolism. These abnormalities resemble those of Emery-Dreifuss muscular dystrophy (EDMD), caused by mutations in A-type lamins (LMNA) and other genes, like Emerin (EMD). We observe that Net39 is downregulated in EDMD patients, implicating Net39 in the pathogenesis of this disorder. Our findings highlight the role of Net39 at the nuclear envelope in maintaining muscle chromatin organization, gene expression and function, and its potential contribution to the molecular etiology of EDMD.
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18
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Gatticchi L, de Las Heras JI, Sivakumar A, Zuleger N, Roberti R, Schirmer EC. Tm7sf2 Disruption Alters Radial Gene Positioning in Mouse Liver Leading to Metabolic Defects and Diabetes Characteristics. Front Cell Dev Biol 2020; 8:592573. [PMID: 33330474 PMCID: PMC7719783 DOI: 10.3389/fcell.2020.592573] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Accepted: 10/26/2020] [Indexed: 01/23/2023] Open
Abstract
Tissue-specific patterns of radial genome organization contribute to genome regulation and can be established by nuclear envelope proteins. Studies in this area often use cancer cell lines, and it is unclear how well such systems recapitulate genome organization of primary cells or animal tissues; so, we sought to investigate radial genome organization in primary liver tissue hepatocytes. Here, we have used a NET47/Tm7sf2–/– liver model to show that manipulating one of these nuclear membrane proteins is sufficient to alter tissue-specific gene positioning and expression. Dam-LaminB1 global profiling in primary liver cells shows that nearly all the genes under such positional regulation are related to/important for liver function. Interestingly, Tm7sf2 is a paralog of the HP1-binding nuclear membrane protein LBR that, like Tm7sf2, also has an enzymatic function in sterol reduction. Fmo3 gene/locus radial mislocalization could be rescued with human wild-type, but not TM7SF2 mutants lacking the sterol reductase function. One central pathway affected is the cholesterol synthesis pathway. Within this pathway, both Cyp51 and Msmo1 are under Tm7sf2 positional and expression regulation. Other consequences of the loss of Tm7sf2 included weight gain, insulin sensitivity, and reduced levels of active Akt kinase indicating additional pathways under its regulation, several of which are highlighted by mispositioning genes. This study emphasizes the importance for tissue-specific radial genome organization in tissue function and the value of studying genome organization in animal tissues and primary cells over cell lines.
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Affiliation(s)
- Leonardo Gatticchi
- Department of Experimental Medicine, University of Perugia, Perugia, Italy
| | - Jose I de Las Heras
- Institute of Cell Biology, University of Edinburgh, Edinburgh, United Kingdom
| | - Aishwarya Sivakumar
- Institute of Cell Biology, University of Edinburgh, Edinburgh, United Kingdom
| | - Nikolaj Zuleger
- Institute of Cell Biology, University of Edinburgh, Edinburgh, United Kingdom
| | - Rita Roberti
- Department of Experimental Medicine, University of Perugia, Perugia, Italy
| | - Eric C Schirmer
- Institute of Cell Biology, University of Edinburgh, Edinburgh, United Kingdom
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Gatticchi L, Petricciuolo M, Scarpelli P, Macchioni L, Corazzi L, Roberti R. Tm7sf2 gene promotes adipocyte differentiation of mouse embryonic fibroblasts and improves insulin sensitivity. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2020; 1868:118897. [PMID: 33121932 DOI: 10.1016/j.bbamcr.2020.118897] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Revised: 10/14/2020] [Accepted: 10/16/2020] [Indexed: 12/13/2022]
Abstract
Adipogenesis is a finely orchestrated program involving a transcriptional cascade coordinated by CEBP and PPAR family members and by hormonally induced signaling pathways. Alterations in any of these factors result into impaired formation of fully differentiated adipocytes. Tm7sf2 gene encodes for a Δ(14)-sterol reductase primarily involved in cholesterol biosynthesis. Furthermore, TM7SF2 modulates the expression of the master gene of adipogenesis PPARγ, suggesting a role in the regulation of adipose tissue homeostasis. We investigated the differentiation of Tm7sf2-/- MEFs into adipocytes, compared to Tm7sf2+/+ MEFs. Tm7sf2 expression was increased at late stage of differentiation in wild type cells, while Tm7sf2-/- MEFs exhibited a reduced capacity to differentiate into mature adipocytes. Indeed, Tm7sf2-/- MEFs had lower neutral lipid accumulation and reduced expression of adipogenic regulators. At early stage, the reduction in C/EBPβ expression impaired mitotic clonal expansion, which is needed by preadipocytes for adipogenesis induction. At late stage, the expression and activity of C/EBPα and PPARγ were inhibited in Tm7sf2-/- cells, leading to the reduced expression of adipocyte genes like Srebp-1c, Fasn, Scd-1, Adipoq, Fabp4, and Glut4. Loss of the acquisition of adipocyte phenotype was accompanied by a reduction in the levels of Irs1, and phosphorylated Akt and ERK1/2, indicating a blunted insulin signaling in differentiating Tm7sf2-/- cells. Moreover, throughout the differentiation process, increased expression of the antiadipogenic Mmp3 was observed in MEFs lacking Tm7sf2. These findings indicate Tm7sf2 as a novel factor influencing adipocyte differentiation that could be relevant to adipose tissue development and maintenance of metabolic health.
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Affiliation(s)
- Leonardo Gatticchi
- Department of Experimental Medicine, Section of Physiology and Biochemistry, University of Perugia, 06132 Perugia, Italy.
| | - Maya Petricciuolo
- Department of Experimental Medicine, Section of Physiology and Biochemistry, University of Perugia, 06132 Perugia, Italy
| | - Paolo Scarpelli
- Department of Experimental Medicine, Section of Physiology and Biochemistry, University of Perugia, 06132 Perugia, Italy
| | - Lara Macchioni
- Department of Experimental Medicine, Section of Physiology and Biochemistry, University of Perugia, 06132 Perugia, Italy.
| | - Lanfranco Corazzi
- Department of Experimental Medicine, Section of Physiology and Biochemistry, University of Perugia, 06132 Perugia, Italy.
| | - Rita Roberti
- Department of Experimental Medicine, Section of Physiology and Biochemistry, University of Perugia, 06132 Perugia, Italy.
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20
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Duan T, Kitzman SC, Geyer PK. Survival of Drosophila germline stem cells requires the chromatin-binding protein Barrier-to-autointegration factor. Development 2020; 147:dev.186171. [PMID: 32345742 DOI: 10.1242/dev.186171] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2019] [Accepted: 03/31/2020] [Indexed: 11/20/2022]
Abstract
The nuclear lamina (NL) is an extensive protein network that underlies the inner nuclear envelope. This network includes LAP2-emerin-MAN1 domain (LEM-D) proteins that associate with the chromatin and DNA-binding protein Barrier-to-autointegration factor (BAF). Here, we investigate the partnership between three NL Drosophila LEM-D proteins and BAF. In most tissues, only Emerin/Otefin is required for NL enrichment of BAF, revealing an unexpected dependence on a single LEM-D protein. Prompted by these observations, we studied BAF contributions in the ovary, a tissue where Emerin/Otefin function is essential. We show that germ cell-specific BAF knockdown causes phenotypes that mirror emerin/otefin mutants. Loss of BAF disrupts NL structure, blocks differentiation and promotes germ cell loss, phenotypes that are partially rescued by inactivation of the ATR and Chk2 kinases. These data suggest that, similar to emerin/otefin mutants, BAF depletion activates the NL checkpoint that causes germ cell loss. Taken together, our findings provide evidence for a prominent NL partnership between the LEM-D protein Emerin/Otefin and BAF, revealing that BAF functions with this partner in the maintenance of an adult stem cell population.
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Affiliation(s)
- Tingting Duan
- Department of Biochemistry, University of Iowa, Iowa City, IA 52242, USA
| | - S Cole Kitzman
- Department of Biochemistry, University of Iowa, Iowa City, IA 52242, USA
| | - Pamela K Geyer
- Department of Biochemistry, University of Iowa, Iowa City, IA 52242, USA
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21
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Lamin A/C Assembly Defects in LMNA-Congenital Muscular Dystrophy Is Responsible for the Increased Severity of the Disease Compared with Emery-Dreifuss Muscular Dystrophy. Cells 2020; 9:cells9040844. [PMID: 32244403 PMCID: PMC7226786 DOI: 10.3390/cells9040844] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Revised: 03/24/2020] [Accepted: 03/27/2020] [Indexed: 01/13/2023] Open
Abstract
LMNA encodes for Lamin A/C, type V intermediate filaments that polymerize under the inner nuclear membrane to form the nuclear lamina. A small fraction of Lamin A/C, less polymerized, is also found in the nucleoplasm. Lamin A/C functions include roles in nuclear resistance to mechanical stress and gene regulation. LMNA mutations are responsible for a wide variety of pathologies, including Emery–Dreifuss (EDMD) and LMNA-related congenital muscular dystrophies (L-CMD) without clear genotype–phenotype correlations. Both diseases presented with striated muscle disorders although L-CMD symptoms appear much earlier and are more severe. Seeking for pathomechanical differences to explain the severity of L-CMD mutations, we performed an in silico analysis of the UMD-LMNA database and found that L-CMD mutations mainly affect residues involved in Lamin dimer and tetramer stability. In line with this, we found increased nucleoplasmic Lamin A/C in L-CMD patient fibroblasts and mouse myoblasts compared to the control and EDMD. L-CMD myoblasts show differentiation defects linked to their inability to upregulate muscle specific nuclear envelope (NE) proteins expression. NE proteins were mislocalized, leading to misshapen nuclei. We conclude that these defects are due to both the absence of Lamin A/C from the nuclear lamina and its maintenance in the nucleoplasm of myotubes.
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22
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Duan T, Green N, Tootle TL, Geyer PK. Nuclear architecture as an intrinsic regulator of Drosophila female germline stem cell maintenance. CURRENT OPINION IN INSECT SCIENCE 2020; 37:30-38. [PMID: 32087561 PMCID: PMC7089816 DOI: 10.1016/j.cois.2019.11.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Revised: 11/08/2019] [Accepted: 11/13/2019] [Indexed: 05/08/2023]
Abstract
Homeostasis of Drosophila germline stem cells (GSC) depends upon the integration of intrinsic and extrinsic signals. This review highlights emerging data that support nuclear architecture as an intrinsic regulator of GSC maintenance and germ cell differentiation. Here, we focus on the nuclear lamina (NL) and the nucleolus, two compartments that undergo alterations in composition upon germ cell differentiation. Loss of NL or nucleolar components leads to GSC loss, resulting from activation of GSC quality control checkpoint pathways. We suggest that the NL and nucleolus integrate signals needed for the switch between GSC maintenance and germ cell differentiation, and propose regulation of nuclear actin pools as one mechanism that connects these compartments.
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Affiliation(s)
- Tingting Duan
- Departments of Biochemistry, University of Iowa, College of Medicine, Iowa City, IA 52242, USA
| | - Nicole Green
- Anatomy and Cell Biology, University of Iowa, College of Medicine, Iowa City, IA 52242, USA
| | - Tina L Tootle
- Anatomy and Cell Biology, University of Iowa, College of Medicine, Iowa City, IA 52242, USA
| | - Pamela K Geyer
- Departments of Biochemistry, University of Iowa, College of Medicine, Iowa City, IA 52242, USA.
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23
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Kumar Y, Sengupta D, Bickmore WA. Recent advances in the spatial organization of the mammalian genome. J Biosci 2020. [DOI: 10.1007/s12038-019-9968-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
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24
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Kumar Y, Sengupta D, Bickmore W. Recent advances in the spatial organization of the mammalian genome. J Biosci 2020; 45:18. [PMID: 31965996] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The mammalian genome is complex and presents a dynamic structural organization that reflects function. Organization of the genome inside the mammalian nucleus impacts all nuclear processes including but not limited to transcription, replication and repair, and in many biological contexts such as early development, differentiation and physiological adaptations. However, there is limited understating of how 3D organization of the mammalian genome regulates different nuclear processes. Recent advances in microscopy and a myriad of genomics methods -- ropelled by next-generation sequencing -- have advanced our knowledge of genome organization to a great extent. In this review, we discuss nuclear compartments in general and recent advances in the understanding of how mammalian genome is organized in these compartments with an emphasis on dynamics at the nuclear periphery.
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Affiliation(s)
- Yatendra Kumar
- MRC Human Genetics Unit, IGMM, University of Edinburgh, Crewe Road South, Edinburgh EH42XU, UK
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25
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Gatticchi L, de Las Heras JI, Roberti R, Schirmer EC. Optimization of DamID for use in primary cultures of mouse hepatocytes. Methods 2019; 157:88-99. [PMID: 30445179 PMCID: PMC6426339 DOI: 10.1016/j.ymeth.2018.11.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2018] [Revised: 11/09/2018] [Accepted: 11/09/2018] [Indexed: 01/09/2023] Open
Abstract
DamID adaptation to primary hepatocytes may preserve tissue 3D genome architecture. Growth factors, vector tropism and enhancers are needed for DamID in primary cells. Mitochondrial contamination can yield high background signal in primary cells. Signal intensity comparisons can increase calling of interesting differential LADs.
DamID, a method to identify DNA associating with a particular protein, was originally developed for use in immortalized tissue culture lines. The power of this technique has led to its adaptation for a number of additional systems. Here we report adaptations for its use in primary cells isolated from rodents with emphasis on the challenges this presents. Specifically, we present several modifications that allow the method to be performed in mouse acutely isolated primary hepatocytes while seemingly maintaining tissue genome architecture. We also describe the downstream bioinformatic analysis necessary to identify LADs and discuss some of the parameters and their effects with regards to the sensitivity of the method.
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Affiliation(s)
- Leonardo Gatticchi
- Department of Experimental Medicine, University of Perugia, Perugia, Italy
| | | | - Rita Roberti
- Department of Experimental Medicine, University of Perugia, Perugia, Italy
| | - Eric C Schirmer
- Wellcome Centre for Cell Biology, University of Edinburgh, Edinburgh, UK.
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26
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Pascual-Reguant L, Blanco E, Galan S, Le Dily F, Cuartero Y, Serra-Bardenys G, Di Carlo V, Iturbide A, Cebrià-Costa JP, Nonell L, de Herreros AG, Di Croce L, Marti-Renom MA, Peiró S. Lamin B1 mapping reveals the existence of dynamic and functional euchromatin lamin B1 domains. Nat Commun 2018; 9:3420. [PMID: 30143639 PMCID: PMC6109041 DOI: 10.1038/s41467-018-05912-z] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Accepted: 08/02/2018] [Indexed: 12/13/2022] Open
Abstract
Lamins (A/C and B) are major constituents of the nuclear lamina (NL). Structurally conserved lamina-associated domains (LADs) are formed by genomic regions that contact the NL. Lamins are also found in the nucleoplasm, with a yet unknown function. Here we map the genome-wide localization of lamin B1 in an euchromatin-enriched fraction of the mouse genome and follow its dynamics during the epithelial-to-mesenchymal transition (EMT). Lamin B1 associates with actively expressed and open euchromatin regions, forming dynamic euchromatin lamin B1-associated domains (eLADs) of about 0.3 Mb. Hi-C data link eLADs to the 3D organization of the mouse genome during EMT and correlate lamin B1 enrichment at topologically associating domain (TAD) borders with increased border strength. Having reduced levels of lamin B1 alters the EMT transcriptional signature and compromises the acquisition of mesenchymal traits. Thus, during EMT, the process of genome reorganization in mouse involves dynamic changes in eLADs.
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Affiliation(s)
| | - Enrique Blanco
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Dr. Aiguader 88, Barcelona, Spain
| | - Silvia Galan
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Dr. Aiguader 88, Barcelona, Spain
- Structural Genomic Group, CNAG-CRG, Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Baldiri Reixac 4, Barcelona, Spain
| | - François Le Dily
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Dr. Aiguader 88, Barcelona, Spain
- Departament de Ciències Experimentals i de la Salut, Universitat Pompeu Fabra (UPF), 08003, Barcelona, Spain
| | - Yasmina Cuartero
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Dr. Aiguader 88, Barcelona, Spain
- Structural Genomic Group, CNAG-CRG, Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Baldiri Reixac 4, Barcelona, Spain
| | - Gemma Serra-Bardenys
- Vall d'Hebron Institute of Oncology, 08035, Barcelona, Spain
- Departament de Ciències Experimentals i de la Salut, Universitat Pompeu Fabra (UPF), 08003, Barcelona, Spain
| | - Valerio Di Carlo
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Dr. Aiguader 88, Barcelona, Spain
| | - Ane Iturbide
- Institute of Epigenetics and Stem Cells, D-81377, München, Germany
| | | | - Lara Nonell
- Servei d'Anàlisi de Microarrays Institut Hospital del Mar d'Investigacions Mèdiques, Barcelona, Spain
| | - Antonio García de Herreros
- Departament de Ciències Experimentals i de la Salut, Universitat Pompeu Fabra (UPF), 08003, Barcelona, Spain
- Programa de Recerca en Càncer, Institut Hospital del Mar d'Investigacions Mèdiques, Barcelona, Spain
| | - Luciano Di Croce
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Dr. Aiguader 88, Barcelona, Spain
- ICREA, Pg. Lluis Companys 23, Barcelona, Spain
| | - Marc A Marti-Renom
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Dr. Aiguader 88, Barcelona, Spain
- Structural Genomic Group, CNAG-CRG, Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Baldiri Reixac 4, Barcelona, Spain
- Departament de Ciències Experimentals i de la Salut, Universitat Pompeu Fabra (UPF), 08003, Barcelona, Spain
- ICREA, Pg. Lluis Companys 23, Barcelona, Spain
| | - Sandra Peiró
- Vall d'Hebron Institute of Oncology, 08035, Barcelona, Spain.
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27
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Pradhan R, Ranade D, Sengupta K. Emerin modulates spatial organization of chromosome territories in cells on softer matrices. Nucleic Acids Res 2018; 46:5561-5586. [PMID: 29684168 PMCID: PMC6009696 DOI: 10.1093/nar/gky288] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2018] [Revised: 04/04/2018] [Accepted: 04/06/2018] [Indexed: 02/06/2023] Open
Abstract
Cells perceive and relay external mechanical forces into the nucleus through the nuclear envelope. Here we examined the effect of lowering substrate stiffness as a paradigm to address the impact of altered mechanical forces on nuclear structure-function relationships. RNA sequencing of cells on softer matrices revealed significant transcriptional imbalances, predominantly in chromatin associated processes and transcriptional deregulation of human Chromosome 1. Furthermore, 3-Dimensional fluorescence in situ hybridization (3D-FISH) analyses showed a significant mislocalization of Chromosome 1 and 19 Territories (CT) into the nuclear interior, consistent with their transcriptional deregulation. However, CT18 with relatively lower transcriptional dysregulation, also mislocalized into the nuclear interior. Furthermore, nuclear Lamins that regulate chromosome positioning, were mislocalized into the nuclear interior in response to lowered matrix stiffness. Notably, Lamin B2 overexpression retained CT18 near the nuclear periphery in cells on softer matrices. While, cells on softer matrices also activated emerin phosphorylation at a novel Tyr99 residue, the inhibition of which in a phospho-deficient mutant (emerinY99F), selectively retained chromosome 18 and 19 but not chromosome 1 territories at their conserved nuclear locations. Taken together, emerin functions as a key mechanosensor, that modulates the spatial organization of chromosome territories in the interphase nucleus.
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Affiliation(s)
- Roopali Pradhan
- Biology, Main Building, First Floor, Room#B-216, Indian Institute of Science Education and Research (IISER), Pune, Dr Homi Bhabha Road, Pashan, Pune 411008, Maharashtra, India
| | - Devika Ranade
- Biology, Main Building, First Floor, Room#B-216, Indian Institute of Science Education and Research (IISER), Pune, Dr Homi Bhabha Road, Pashan, Pune 411008, Maharashtra, India
| | - Kundan Sengupta
- Biology, Main Building, First Floor, Room#B-216, Indian Institute of Science Education and Research (IISER), Pune, Dr Homi Bhabha Road, Pashan, Pune 411008, Maharashtra, India
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28
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Breaking the scale: how disrupting the karyoplasmic ratio gives cancer cells an advantage for metastatic invasion. Biochem Soc Trans 2017; 45:1333-1344. [PMID: 29150524 DOI: 10.1042/bst20170153] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2017] [Revised: 09/28/2017] [Accepted: 10/16/2017] [Indexed: 01/03/2023]
Abstract
Nuclear size normally scales with the size of the cell, but in cancer this 'karyoplasmic ratio' is disrupted. This is particularly so in more metastatic tumors where changes in the karyoplasmic ratio are used in both diagnosis and prognosis for several tumor types. However, the direction of nuclear size changes differs for particular tumor types: for example in breast cancer, larger nuclear size correlates with increased metastasis, while for lung cancer smaller nuclear size correlates with increased metastasis. Thus, there must be tissue-specific drivers of the nuclear size changes, but proteins thus far linked to nuclear size regulation are widely expressed. Notably, for these tumor types, ploidy changes have been excluded as the basis for nuclear size changes, and so, the increased metastasis is more likely to have a basis in the nuclear morphology change itself. We review what is known about nuclear size regulation and postulate how such nuclear size changes can increase metastasis and why the directionality can differ for particular tumor types.
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29
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de Leeuw R, Gruenbaum Y, Medalia O. Nuclear Lamins: Thin Filaments with Major Functions. Trends Cell Biol 2017; 28:34-45. [PMID: 28893461 DOI: 10.1016/j.tcb.2017.08.004] [Citation(s) in RCA: 191] [Impact Index Per Article: 27.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2017] [Revised: 08/08/2017] [Accepted: 08/14/2017] [Indexed: 10/18/2022]
Abstract
The nuclear lamina is a nuclear peripheral meshwork that is mainly composed of nuclear lamins, although a small fraction of lamins also localizes throughout the nucleoplasm. Lamins are classified as type V intermediate filament (IF) proteins. Mutations in lamin genes cause at least 15 distinct human diseases, collectively termed laminopathies, including muscle, metabolic, and neuronal diseases, and can cause accelerated aging. Most of these mutations are in the LMNA gene encoding A-type lamins. A growing number of nuclear proteins are known to bind lamins and are implicated in both nuclear and cytoskeletal organization, mechanical stability, chromatin organization, signaling, gene regulation, genome stability, and cell differentiation. Recent studies reveal the organization of the lamin filament meshwork in somatic cells where they assemble as tetramers in cross-section of the filaments.
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Affiliation(s)
- Rebecca de Leeuw
- Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Yosef Gruenbaum
- Department of Genetics, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Ohad Medalia
- Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland; Department of Life Sciences and the National Institute for Biotechnology in the Negev, Ben-Gurion University, Beer-Sheva 84105, Israel.
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30
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Abstract
Nuclear lamins are components of the peripheral lamina that define the mechanical properties of nuclei and tether heterochromatin to the periphery. A-type lamins localize also to the nuclear interior, but the regulation and specific functions of this nucleoplasmic lamin pool are poorly understood. In this Commentary, we summarize known pathways that are potentially involved in the localization and dynamic behavior of intranuclear lamins, including their post-translational modifications and interactions with nucleoplasmic proteins, such as lamina-associated polypeptide 2α (LAP2α; encoded by TMPO). In addition, new data suggest that lamins in the nuclear interior have an important role in chromatin regulation and gene expression through dynamic binding to both hetero- and euchromatic genomic regions and promoter subdomains, thereby affecting epigenetic pathways and chromatin accessibility. Nucleoplasmic lamins also have a role in spatial chromatin organization and may be involved in mechanosignaling. In view of this newly emerging concept, we propose that the previously reported cellular phenotypes in lamin-linked diseases are, at least in part, rooted in an impaired regulation and/or function of the nucleoplasmic lamin A/C pool.
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Affiliation(s)
- Nana Naetar
- Center of Medical Biochemistry, Max F. Perutz Laboratories (MFPL), Medical University of Vienna, Vienna Biocenter (VBC), Dr.-Bohr-Gasse 9, Vienna A-1030, Austria
| | - Simona Ferraioli
- Center of Medical Biochemistry, Max F. Perutz Laboratories (MFPL), Medical University of Vienna, Vienna Biocenter (VBC), Dr.-Bohr-Gasse 9, Vienna A-1030, Austria
| | - Roland Foisner
- Center of Medical Biochemistry, Max F. Perutz Laboratories (MFPL), Medical University of Vienna, Vienna Biocenter (VBC), Dr.-Bohr-Gasse 9, Vienna A-1030, Austria
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