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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] [What about the content of this article? (0)] [Affiliation(s)] [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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AlRuwaili R, Al-Kuraishy HM, Al-Gareeb AI, Ali NH, Alexiou A, Papadakis M, Saad HM, Batiha GES. The Possible Role of Brain-derived Neurotrophic Factor in Epilepsy. Neurochem Res 2024; 49:533-547. [PMID: 38006577 PMCID: PMC10884085 DOI: 10.1007/s11064-023-04064-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2023] [Revised: 11/11/2023] [Accepted: 11/14/2023] [Indexed: 11/27/2023]
Abstract
Epilepsy is a neurological disease characterized by repeated seizures. Despite of that the brain-derived neurotrophic factor (BDNF) is implicated in the pathogenesis of epileptogenesis and epilepsy, BDNF may have a neuroprotective effect against epilepsy. Thus, the goal of the present review was to highlight the protective and detrimental roles of BDNF in epilepsy. In this review, we also try to find the relation of BDNF with other signaling pathways and cellular processes including autophagy, mTOR pathway, progranulin (PGN), and α-Synuclein (α-Syn) which negatively and positively regulate BDNF/tyrosine kinase receptor B (TrkB) signaling pathway. Therefore, the assessment of BDNF levels in epilepsy should be related to other neuronal signaling pathways and types of epilepsy in both preclinical and clinical studies. In conclusion, there is a strong controversy concerning the potential role of BDNF in epilepsy. Therefore, preclinical, molecular, and clinical studies are warranted in this regard.
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Affiliation(s)
- Raed AlRuwaili
- Department of Internal Medicine, College of Medicine, Jouf University, Sakaka, Saudi Arabia
| | - Hayder M Al-Kuraishy
- Department of Clinical Pharmacology and Medicine, College of Medicine, ALmustansiriyia University, P.O. Box 14132, Baghdad, Iraq
| | - Ali I Al-Gareeb
- Department of Clinical Pharmacology and Medicine, College of Medicine, ALmustansiriyia University, P.O. Box 14132, Baghdad, Iraq
| | - Naif H Ali
- Department of Internal Medicine, Medical College, Najran University, Najran, Saudi Arabia
| | - Athanasios Alexiou
- University Centre for Research & Development, Chandigarh University, Chandigarh-Ludhiana Highway, Mohali, Punjab, India
- Department of Research & Development, Funogen, Athens, Greece
- Department of Research & Development, AFNP Med, Wien, 1030, Austria
- Department of Science and Engineering, Novel Global Community Educational Foundation, Hebersham, NSW, 2770, Australia
| | - Marios Papadakis
- Department of Surgery II, University Hospital Witten-Herdecke, University of Witten-Herdecke, Heusnerstrasse 40, 42283, Wuppertal, Germany.
| | - Hebatallah M Saad
- Department of Pathology, Faculty of Veterinary Medicine, Matrouh University, Matrouh, 51744, Egypt.
| | - Gaber El-Saber Batiha
- Department of Pharmacology and Therapeutics, Faculty of Veterinary Medicine, Damanhour University, Damanhour, AlBeheira, 22511, Egypt.
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3
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Khan A, Metts JM, Collins LC, Mills CA, Li K, Brademeyer AL, Bowman BM, Major MB, Aubé J, Herring LE, Davis IJ, Strahl BD. SETD2 maintains nuclear lamina stability to safeguard the genome. bioRxiv 2023:2023.09.28.560032. [PMID: 37808753 PMCID: PMC10557632 DOI: 10.1101/2023.09.28.560032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/10/2023]
Abstract
Histone methyltransferases play essential roles in the organization and function of chromatin. They are also frequently mutated in human diseases including cancer1. One such often mutated methyltransferase, SETD2, associates co-transcriptionally with RNA polymerase II and catalyzes histone H3 lysine 36 trimethylation (H3K36me3) - a modification that contributes to gene transcription, splicing, and DNA repair2. While studies on SETD2 have largely focused on the consequences of its catalytic activity, the non-catalytic functions of SETD2 are largely unknown. Here we report a catalysis-independent function of SETD2 in maintaining nuclear lamina stability and genome integrity. We found that SETD2, via its intrinsically disordered N-terminus, associates with nuclear lamina proteins including lamin A/C, lamin B1, and emerin. Depletion of SETD2, or deletion of its N-terminus, resulted in widespread nuclear morphology abnormalities and genome stability defects that were reminiscent of a defective nuclear lamina. Mechanistically, the N-terminus of SETD2 facilitates the association of the mitotic kinase CDK1 with lamins, thereby promoting lamin phosphorylation and depolymerization required for nuclear envelope disassembly during mitosis. Taken together, our findings reveal an unanticipated link between the N-terminus of SETD2 and nuclear lamina organization that may underlie how SETD2 acts as a tumor suppressor.
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Affiliation(s)
- Abid Khan
- Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, North Carolina 27599, USA
| | - James M. Metts
- Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, North Carolina 27599, USA
| | - Lucas C. Collins
- Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, North Carolina 27599, USA
| | - C. Allie Mills
- UNC Proteomics Core Facility, Department of Pharmacology, University of North Carolina, Chapel Hill, North Carolina, 27599, USA
| | - Kelin Li
- Division of Chemical Biology and Medicinal Chemistry, UNC Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
| | - Amanda L. Brademeyer
- Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, North Carolina 27599, USA
| | - Brittany M. Bowman
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina 27599, USA
- Department of Cell Biology & Physiology, Washington University in St. Louis
| | - M. Ben Major
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina 27599, USA
- Department of Cell Biology & Physiology, Washington University in St. Louis
| | - Jeffrey Aubé
- Division of Chemical Biology and Medicinal Chemistry, UNC Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
| | - Laura E. Herring
- UNC Proteomics Core Facility, Department of Pharmacology, University of North Carolina, Chapel Hill, North Carolina, 27599, USA
| | - Ian J. Davis
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina 27599, USA
- Department of Pediatrics, University of North Carolina, Chapel Hill, North Carolina 27514
| | - Brian D. Strahl
- Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, North Carolina 27599, USA
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina 27599, USA
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Abstract
Activation of regeneration upon tissue damages requires the activation of many developmental genes responsible for cell proliferation, migration, differentiation, and tissue patterning. Ample evidence revealed that the regulation of chromatin organization functions as a crucial mechanism for establishing and maintaining cellular identity through precise control of gene transcription. The alteration of chromatin organization can lead to changes in chromatin accessibility and/or enhancer-promoter interactions. Like embryogenesis, each stage of tissue regeneration is accompanied by dynamic changes of chromatin organization in regeneration-responsive cells. In the past decade, many studies have been conducted to investigate the contribution of chromatin organization during regeneration in various tissues, organs, and organisms. A collection of chromatin regulators were demonstrated to play critical roles in regeneration. In this review, we will summarize the progress in the understanding of chromatin organization during regeneration in different research organisms and discuss potential common mechanisms responsible for the activation of regeneration response program.
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Affiliation(s)
- Xiaohui Jia
- National Institute of Biological Sciences, Beijing, 102206, China
- China Agricultural University, Beijing, 100083, China
| | - Weifeng Lin
- National Institute of Biological Sciences, Beijing, 102206, China
- Tsinghua Institute of Multidisciplinary Biomedical Research, Tsinghua University, Beijing, 100084, China
| | - Wei Wang
- National Institute of Biological Sciences, Beijing, 102206, China.
- Tsinghua Institute of Multidisciplinary Biomedical Research, Tsinghua University, Beijing, 100084, China.
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5
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Dror E, Fagnocchi L, Wegert V, Apostle S, Grimaldi B, Gruber T, Panzeri I, Heyne S, Höffler KD, Kreiner V, Ching R, Tsai-Hsiu Lu T, Semwal A, Johnson B, Senapati P, Lempradl A, Schones D, Imhof A, Shen H, Pospisilik JA. Epigenetic dosage identifies two major and functionally distinct β cell subtypes. Cell Metab 2023; 35:821-836.e7. [PMID: 36948185 PMCID: PMC10160009 DOI: 10.1016/j.cmet.2023.03.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Revised: 01/17/2023] [Accepted: 03/08/2023] [Indexed: 03/24/2023]
Abstract
The mechanisms that specify and stabilize cell subtypes remain poorly understood. Here, we identify two major subtypes of pancreatic β cells based on histone mark heterogeneity (βHI and βLO). βHI cells exhibit ∼4-fold higher levels of H3K27me3, distinct chromatin organization and compaction, and a specific transcriptional pattern. βHI and βLO cells also differ in size, morphology, cytosolic and nuclear ultrastructure, epigenomes, cell surface marker expression, and function, and can be FACS separated into CD24+ and CD24- fractions. Functionally, βHI cells have increased mitochondrial mass, activity, and insulin secretion in vivo and ex vivo. Partial loss of function indicates that H3K27me3 dosage regulates βHI/βLO ratio in vivo, suggesting that control of β cell subtype identity and ratio is at least partially uncoupled. Both subtypes are conserved in humans, with βHI cells enriched in humans with type 2 diabetes. Thus, epigenetic dosage is a novel regulator of cell subtype specification and identifies two functionally distinct β cell subtypes.
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Affiliation(s)
- Erez Dror
- Department of Epigenetics, Max Planck Institute of Immunobiology and Epigenetics, Freiburg 79108, Germany.
| | - Luca Fagnocchi
- Department of Epigenetics, Van Andel Institute, Grand Rapids, MI 49503, USA
| | - Vanessa Wegert
- Department of Epigenetics, Max Planck Institute of Immunobiology and Epigenetics, Freiburg 79108, Germany; Department of Epigenetics, Van Andel Institute, Grand Rapids, MI 49503, USA
| | - Stefanos Apostle
- Department of Epigenetics, Van Andel Institute, Grand Rapids, MI 49503, USA
| | - Brooke Grimaldi
- Department of Epigenetics, Van Andel Institute, Grand Rapids, MI 49503, USA
| | - Tim Gruber
- Department of Epigenetics, Van Andel Institute, Grand Rapids, MI 49503, USA
| | - Ilaria Panzeri
- Department of Epigenetics, Max Planck Institute of Immunobiology and Epigenetics, Freiburg 79108, Germany; Department of Epigenetics, Van Andel Institute, Grand Rapids, MI 49503, USA
| | - Steffen Heyne
- Department of Epigenetics, Max Planck Institute of Immunobiology and Epigenetics, Freiburg 79108, Germany
| | - Kira Daniela Höffler
- Department of Epigenetics, Max Planck Institute of Immunobiology and Epigenetics, Freiburg 79108, Germany
| | - Victor Kreiner
- Department of Epigenetics, Max Planck Institute of Immunobiology and Epigenetics, Freiburg 79108, Germany
| | - Reagan Ching
- Department of Epigenetics, Max Planck Institute of Immunobiology and Epigenetics, Freiburg 79108, Germany
| | - Tess Tsai-Hsiu Lu
- Department of Epigenetics, Max Planck Institute of Immunobiology and Epigenetics, Freiburg 79108, Germany
| | - Ayush Semwal
- Department of Epigenetics, Van Andel Institute, Grand Rapids, MI 49503, USA
| | - Ben Johnson
- Department of Epigenetics, Van Andel Institute, Grand Rapids, MI 49503, USA
| | - Parijat Senapati
- Department of Diabetes Complications and Metabolism, Diabetes and Metabolism Research Institute, Beckman Research Institute of City of Hope, Duarte, CA 91010, USA
| | - Adelheid Lempradl
- Department of Epigenetics, Max Planck Institute of Immunobiology and Epigenetics, Freiburg 79108, Germany; Department of Epigenetics, Van Andel Institute, Grand Rapids, MI 49503, USA
| | - Dustin Schones
- Department of Diabetes Complications and Metabolism, Diabetes and Metabolism Research Institute, Beckman Research Institute of City of Hope, Duarte, CA 91010, USA
| | - Axel Imhof
- Biomedical Center Munich, Ludwig Maximilian University of Munich, 82152 Planegg-Martinsried, Germany
| | - Hui Shen
- Department of Epigenetics, Van Andel Institute, Grand Rapids, MI 49503, USA
| | - John Andrew Pospisilik
- Department of Epigenetics, Max Planck Institute of Immunobiology and Epigenetics, Freiburg 79108, Germany; Department of Epigenetics, Van Andel Institute, Grand Rapids, MI 49503, USA.
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6
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Marcelot A, Rodriguez-tirado F, Cuniasse P, Joiner M, Miron S, Soshnev AA, Fang M, Pufall MA, Mathews KD, Moore SA, Zinn-justin S, Geyer PK. A De Novo Sequence Variant in Barrier-to-Autointegration Factor Is Associated with Dominant Motor Neuronopathy. Cells 2023; 12:847. [PMID: 36980188 PMCID: PMC10099716 DOI: 10.3390/cells12060847] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Revised: 02/23/2023] [Accepted: 02/26/2023] [Indexed: 03/12/2023] Open
Abstract
Barrier-to-autointegration factor (BAF) is an essential component of the nuclear lamina. Encoded by BANF1, this DNA binding protein contributes to the regulation of gene expression, cell cycle progression, and nuclear integrity. A rare recessive BAF variant, Ala12Thr, causes the premature aging syndrome, Néstor–Guillermo progeria syndrome (NGPS). Here, we report the first dominant pathogenic BAF variant, Gly16Arg, identified in a patient presenting with progressive neuromuscular weakness. Although disease variants carry nearby amino acid substitutions, cellular and biochemical properties are distinct. In contrast to NGPS, Gly16Arg patient fibroblasts show modest changes in nuclear lamina structure and increases in repressive marks associated with heterochromatin. Structural studies reveal that the Gly16Arg substitution introduces a salt bridge between BAF monomers, reducing the conformation ensemble available to BAF. We show that this structural change increases the double-stranded DNA binding affinity of BAF Gly16Arg. Together, our findings suggest that BAF Gly16Arg has an increased chromatin occupancy that leads to epigenetic changes and impacts nuclear functions. These observations provide a new example of how a missense mutation can change a protein conformational equilibrium to cause a dominant disease and extend our understanding of mechanisms by which BAF function impacts human health.
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7
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Danielsson BE, Tieu KV, Spagnol ST, Vu KK, Cabe JI, Raisch TB, Dahl KN, Conway DE. Chromatin condensation regulates endothelial cell adaptation to shear stress. Mol Biol Cell 2022; 33:ar101. [PMID: 35895088 DOI: 10.1091/mbc.e22-02-0064] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Vascular endothelial cells (ECs) have been shown to be mechanoresponsive to the forces of blood flow, including fluid shear stress (FSS), the frictional force of blood on the vessel wall. Recent reports have shown that FSS induces epigenetic changes in chromatin. Epigenetic changes, such as methylation and acetylation of histones, not only affect gene expression but also affect chromatin condensation, which can alter nuclear stiffness. Thus, we hypothesized that changes in chromatin condensation may be an important component for how ECs adapt to FSS. Using both in vitro and in vivo models of EC adaptation to FSS, we observed an increase in histone acetylation and a decrease in histone methylation in ECs adapted to flow as compared with static. Using small molecule drugs, as well as vascular endothelial growth factor, to change chromatin condensation, we show that decreasing chromatin condensation enables cells to more quickly align to FSS, whereas increasing chromatin condensation inhibited alignment. Additionally, we show data that changes in chromatin condensation can also prevent or increase DNA damage, as measured by phosphorylation of γH2AX. Taken together, these results indicate that chromatin condensation, and potentially by extension nuclear stiffness, is an important aspect of EC adaptation to FSS.
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Affiliation(s)
- Brooke E Danielsson
- Department of Biomedical Engineering, Virginia Commonwealth University, Richmond, Virginia 23284
| | - Katie V Tieu
- Department of Biomedical Engineering, Virginia Commonwealth University, Richmond, Virginia 23284
| | - Stephen T Spagnol
- Department of Chemical Engineering, Carnegie Mellon University, Pittsburgh, PA 15213
| | - Kira K Vu
- Department of Biomedical Engineering, Virginia Commonwealth University, Richmond, Virginia 23284
| | - Jolene I Cabe
- Department of Biomedical Engineering, Virginia Commonwealth University, Richmond, Virginia 23284
| | - Tristan B Raisch
- Department of Biomedical Engineering, Virginia Commonwealth University, Richmond, Virginia 23284
| | - Kris Noel Dahl
- Department of Chemical Engineering, Carnegie Mellon University, Pittsburgh, PA 15213.,Forensics Department, Thornton Tomasetti, New York City, NY 10271
| | - Daniel E Conway
- Department of Biomedical Engineering, Virginia Commonwealth University, Richmond, Virginia 23284.,Department of Biomedical Engineering, The Ohio State University, Columbus, OH 43210.,Center for Cancer Engineering, and Arthur G. James Comprehensive Cancer Center, The Ohio State University, Columbus, OH 43210
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8
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Kitzman SC, Duan T, Pufall MA, Geyer PK. Checkpoint activation drives global gene expression changes in Drosophila nuclear lamina mutants. G3 (Bethesda) 2022; 12:6459172. [PMID: 34893833 PMCID: PMC9210273 DOI: 10.1093/g3journal/jkab408] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Accepted: 11/22/2021] [Indexed: 11/25/2022]
Abstract
The nuclear lamina (NL) lines the inner nuclear membrane. This extensive protein network organizes chromatin and contributes to the regulation of transcription, DNA replication, and repair. Lap2-emerin-MAN1 domain (LEM-D) proteins are key members of the NL, representing proteins that connect the NL to the genome through shared interactions with the chromatin-binding protein Barrier-to-Autointegration Factor (BAF). Functions of the LEM-D protein emerin and BAF are essential during Drosophila melanogaster oogenesis. Indeed, loss of either emerin or BAF blocks germ cell development and causes loss of germline stem cells, defects linked to the deformation of NL structure, and non-canonical activation of Checkpoint kinase 2 (Chk2). Here, we investigate the contributions of emerin and BAF to gene expression in the ovary. Profiling RNAs from emerin and baf mutant ovaries revealed that nearly all baf misregulated genes were shared with emerin mutants, defining a set of NL-regulated genes. Strikingly, loss of Chk2 restored the expression of most NL-regulated genes, identifying a large class of Chk2-dependent genes (CDGs). Nonetheless, some genes remained misexpressed upon Chk2 loss, identifying a smaller class of emerin-dependent genes (EDGs). Properties of EDGs suggest a shared role for emerin and BAF in the repression of developmental genes. Properties of CDGs demonstrate that Chk2 activation drives global misexpression of genes in the emerin and baf mutant backgrounds. Notably, CDGs were found upregulated in lamin-B mutant backgrounds. These observations predict that Chk2 activation might have a general role in gene expression changes found in NL-associated diseases, such as laminopathies.
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Affiliation(s)
| | - Tingting Duan
- Department of Biochemistry, University of Iowa, Iowa City, IA 52242, USA
| | - Miles A Pufall
- 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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Tarvirdipour S, Skowicki M, Schoenenberger CA, Kapinos LE, Lim R, Benenson Y, Palivan CG. A self-assembling peptidic platform to boost the cellular uptake and nuclear delivery of oligonucleotides. Biomater Sci 2022; 10:4309-4323. [DOI: 10.1039/d2bm00826b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The design of non-viral vectors that efficiently deliver genetic materials into cells, in particular to the nucleus, remains a major challenge in gene therapy and vaccine development. To tackle the...
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10
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Zhang L, Chen Y, Belmont AS. Measuring Cytological Proximity of Chromosomal Loci to Defined Nuclear Compartments with TSA-seq. Methods Mol Biol 2022. [PMID: 35867249 DOI: 10.1007/978-1-0716-2497-5_8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Distinct nuclear structures and bodies are involved in genome intranuclear positioning. Measuring proximity and relative distances of genomic loci to these nuclear compartments, and correlating this chromosome intranuclear positioning with epigenetic marks and functional readouts genome-wide, will be required to appreciate the true extent to which this nuclear compartmentalization contributes to regulation of genome functions. Here we present detailed protocols for TSA-seq, the first sequencing-based method for estimation of cytological proximity of chromosomal loci to spatially discrete nuclear structures, such as nuclear bodies or the nuclear lamina. TSA-seq uses Tyramide Signal Amplification (TSA) of immunostained cells to create a concentration gradient of tyramide-biotin free radicals which decays exponentially as a function of distance from a point-source target. Reaction of these free radicals with DNA deposits tyramide-biotin onto DNA as a function of distance from the point source. The relative enrichment of this tyramide-labeled DNA versus input DNA, revealed by DNA sequencing, can then be used as a "cytological ruler" to infer relative, or even absolute, mean chromosomal distances from immunostained nuclear compartments. TSA-seq mapping is highly reproducible and largely independent of the target protein or antibody choice for labeling a particular nuclear compartment. Our protocols include variations in TSA labeling conditions to provide varying spatial resolution as well as enhanced sensitivity. Our most streamlined protocol produces TSA-seq spatial mapping over a distance range of ~1 micron from major nuclear compartments using ~10-20 million cells.
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11
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Flores LF, Tader BR, Tolosa EJ, Sigafoos AN, Marks DL, Fernandez-Zapico ME. Nuclear Dynamics and Chromatin Structure: Implications for Pancreatic Cancer. Cells 2021; 10:2624. [PMID: 34685604 DOI: 10.3390/cells10102624] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2021] [Revised: 09/20/2021] [Accepted: 09/27/2021] [Indexed: 12/14/2022] Open
Abstract
Changes in nuclear shape have been extensively associated with the dynamics and functionality of cancer cells. In most normal cells, nuclei have a regular ellipsoid shape and minimal variation in nuclear size; however, an irregular nuclear contour and abnormal nuclear size is often observed in cancer, including pancreatic cancer. Furthermore, alterations in nuclear morphology have become the 'gold standard' for tumor staging and grading. Beyond the utility of altered nuclear morphology as a diagnostic tool in cancer, the implications of altered nuclear structure for the biology and behavior of cancer cells are profound as changes in nuclear morphology could impact cellular responses to physical strain, adaptation during migration, chromatin organization, and gene expression. Here, we aim to highlight and discuss the factors that regulate nuclear dynamics and their implications for pancreatic cancer biology.
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12
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Jernfors T, Danforth J, Kesäniemi J, Lavrinienko A, Tukalenko E, Fajkus J, Dvořáčková M, Mappes T, Watts PC. Expansion of rDNA and pericentromere satellite repeats in the genomes of bank voles Myodes glareolus exposed to environmental radionuclides. Ecol Evol 2021; 11:8754-8767. [PMID: 34257925 PMCID: PMC8258220 DOI: 10.1002/ece3.7684] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 04/27/2021] [Accepted: 05/05/2021] [Indexed: 12/21/2022] Open
Abstract
Altered copy number of certain highly repetitive regions of the genome, such as satellite DNA within heterochromatin and ribosomal RNA loci (rDNA), is hypothesized to help safeguard the genome against damage derived from external stressors. We quantified copy number of the 18S rDNA and a pericentromeric satellite DNA (Msat-160) in bank voles (Myodes glareolus) inhabiting the Chernobyl Exclusion Zone (CEZ), an area that is contaminated by radionuclides and where organisms are exposed to elevated levels of ionizing radiation. We found a significant increase in 18S rDNA and Msat-160 content in the genomes of bank voles from contaminated locations within the CEZ compared with animals from uncontaminated locations. Moreover, 18S rDNA and Msat-160 copy number were positively correlated in the genomes of bank voles from uncontaminated, but not in the genomes of animals inhabiting contaminated, areas. These results show the capacity for local-scale geographic variation in genome architecture and are consistent with the genomic safeguard hypothesis. Disruption of cellular processes related to genomic stability appears to be a hallmark effect in bank voles inhabiting areas contaminated by radionuclides.
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Affiliation(s)
- Toni Jernfors
- Department of Biological and Environmental ScienceUniversity of JyväskyläJyväskyläFinland
| | - John Danforth
- Department of Biochemistry & Molecular BiologyRobson DNA Science CentreArnie Charbonneau Cancer InstituteCumming School of MedicineUniversity of CalgaryCalgaryCanada
| | - Jenni Kesäniemi
- Department of Biological and Environmental ScienceUniversity of JyväskyläJyväskyläFinland
| | - Anton Lavrinienko
- Department of Biological and Environmental ScienceUniversity of JyväskyläJyväskyläFinland
| | - Eugene Tukalenko
- Department of Biological and Environmental ScienceUniversity of JyväskyläJyväskyläFinland
- National Research Center for Radiation Medicine of the National Academy of Medical ScienceKyivUkraine
| | - Jiří Fajkus
- Mendel Centre for Plant Genomics and ProteomicsCentral European Institute of Technology (CEITEC)Masaryk UniversityBrnoCzech Republic
- Laboratory of Functional Genomics and ProteomicsNCBRFaculty of ScienceMasaryk UniversityBrnoCzech Republic
- Department of Cell Biology and RadiobiologyInstitute of Biophysics of the Czech Academy of SciencesBrnoCzech Republic
| | - Martina Dvořáčková
- Mendel Centre for Plant Genomics and ProteomicsCentral European Institute of Technology (CEITEC)Masaryk UniversityBrnoCzech Republic
| | - Tapio Mappes
- Department of Biological and Environmental ScienceUniversity of JyväskyläJyväskyläFinland
| | - Phillip C. Watts
- Department of Biological and Environmental ScienceUniversity of JyväskyläJyväskyläFinland
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13
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Breunig CT, Köferle A, Neuner AM, Wiesbeck MF, Baumann V, Stricker SH. CRISPR Tools for Physiology and Cell State Changes: Potential of Transcriptional Engineering and Epigenome Editing. Physiol Rev 2020; 101:177-211. [PMID: 32525760 DOI: 10.1152/physrev.00034.2019] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Given the large amount of genome-wide data that have been collected during the last decades, a good understanding of how and why cells change during development, homeostasis, and disease might be expected. Unfortunately, the opposite is true; triggers that cause cellular state changes remain elusive, and the underlying molecular mechanisms are poorly understood. Although genes with the potential to influence cell states are known, the historic dependency on methods that manipulate gene expression outside the endogenous chromatin context has prevented us from understanding how cells organize, interpret, and protect cellular programs. Fortunately, recent methodological innovations are now providing options to answer these outstanding questions, by allowing to target and manipulate individual genomic and epigenomic loci. In particular, three experimental approaches are now feasible due to DNA targeting tools, namely, activation and/or repression of master transcription factors in their endogenous chromatin context; targeting transcription factors to endogenous, alternative, or inaccessible sites; and finally, functional manipulation of the chromatin context. In this article, we discuss the molecular basis of DNA targeting tools and review the potential of these new technologies before we summarize how these have already been used for the manipulation of cellular states and hypothesize about future applications.
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Affiliation(s)
- Christopher T Breunig
- MCN Junior Research Group, Munich Center for Neurosciences, Ludwig-Maximilian- Universität, BioMedical Center, Planegg-Martinsried, Germany; and Epigenetic Engineering, Institute of Stem Cell Research, Helmholtz Zentrum, German Research Center for Environmental Health, BioMedical Center, Planegg-Martinsried, Germany
| | - Anna Köferle
- MCN Junior Research Group, Munich Center for Neurosciences, Ludwig-Maximilian- Universität, BioMedical Center, Planegg-Martinsried, Germany; and Epigenetic Engineering, Institute of Stem Cell Research, Helmholtz Zentrum, German Research Center for Environmental Health, BioMedical Center, Planegg-Martinsried, Germany
| | - Andrea M Neuner
- MCN Junior Research Group, Munich Center for Neurosciences, Ludwig-Maximilian- Universität, BioMedical Center, Planegg-Martinsried, Germany; and Epigenetic Engineering, Institute of Stem Cell Research, Helmholtz Zentrum, German Research Center for Environmental Health, BioMedical Center, Planegg-Martinsried, Germany
| | - Maximilian F Wiesbeck
- MCN Junior Research Group, Munich Center for Neurosciences, Ludwig-Maximilian- Universität, BioMedical Center, Planegg-Martinsried, Germany; and Epigenetic Engineering, Institute of Stem Cell Research, Helmholtz Zentrum, German Research Center for Environmental Health, BioMedical Center, Planegg-Martinsried, Germany
| | - Valentin Baumann
- MCN Junior Research Group, Munich Center for Neurosciences, Ludwig-Maximilian- Universität, BioMedical Center, Planegg-Martinsried, Germany; and Epigenetic Engineering, Institute of Stem Cell Research, Helmholtz Zentrum, German Research Center for Environmental Health, BioMedical Center, Planegg-Martinsried, Germany
| | - Stefan H Stricker
- MCN Junior Research Group, Munich Center for Neurosciences, Ludwig-Maximilian- Universität, BioMedical Center, Planegg-Martinsried, Germany; and Epigenetic Engineering, Institute of Stem Cell Research, Helmholtz Zentrum, German Research Center for Environmental Health, BioMedical Center, Planegg-Martinsried, Germany
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14
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Maji A, Ahmed JA, Roy S, Chakrabarti B, Mitra MK. A Lamin-Associated Chromatin Model for Chromosome Organization. Biophys J 2020; 118:3041-3050. [PMID: 32492372 DOI: 10.1016/j.bpj.2020.05.014] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Revised: 05/09/2020] [Accepted: 05/12/2020] [Indexed: 12/22/2022] Open
Abstract
We propose a simple model for chromatin organization based on the interaction of the chromatin fibers with lamin proteins along the nuclear membrane. Lamin proteins are known to be a major factor that influences chromatin organization and hence gene expression in the cells. We provide a quantitative understanding of lamin-associated chromatin organization in a crowded macromolecular environment by systematically varying the heteropolymer segment distribution and the strength of the lamin-chromatin attractive interaction. Our minimal polymer model reproduces the formation of lamin-associated-domains and provides an in silico tool for quantifying domain length distributions for different distributions of heteropolymer segments. We show that a Gaussian distribution of heteropolymer segments, coupled with strong lamin-chromatin interactions, can qualitatively reproduce observed length distributions of lamin-associated-domains. Further, lamin-mediated interaction can enhance the formation of chromosome territories as well as the organization of chromatin into tightly packed heterochromatin and the loosely packed gene-rich euchromatin regions.
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Affiliation(s)
- Ajoy Maji
- Department of Physics, Indian Institute of Technology Bombay, Mumbai, India
| | - Jahir A Ahmed
- AKI's Poona College of Arts, Science and Commerce, Camp, Pune, India
| | - Subhankar Roy
- Saha Institute of Nuclear Physics, HBNI, Kolkata, India
| | | | - Mithun K Mitra
- Department of Physics, Indian Institute of Technology Bombay, Mumbai, India.
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15
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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16
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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. Curr Opin Insect Sci 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] [What about the content of this article? (0)] [Affiliation(s)] [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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17
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Qiu GH, Zheng X, Fu M, Huang C, Yang X. The protective function of non-coding DNA in DNA damage accumulation with age and its roles in age-related diseases. Biogerontology 2019; 20:741-61. [PMID: 31473864 DOI: 10.1007/s10522-019-09832-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2019] [Accepted: 08/28/2019] [Indexed: 12/11/2022]
Abstract
Aging is a progressive decline of physiological function in tissue and organ accompanying both accumulation of DNA damage and reduction of non-coding DNA. Peripheral non-coding DNA/heterochromatin has been proposed to protect the genome and centrally-located protein-coding sequences in soma and male germ cells against radiation and the invasion of exogenous nucleic acids. Therefore, this review summarizes the reduction of non-coding DNA/heterochromatin (including telomeric DNA and rDNA) and DNA damage accumulation during normal physiological aging and in various aging-related diseases. Based on analysis of data, it is found that DNA damage accumulation is roughly negatively correlated with the reduction of non-coding DNA and therefore speculated that DNA damage accumulation is likely due to the reduction of non-coding DNA protection in genome defense during aging. Therefore, it is proposed here that means to increase the total amount of non-coding DNA and/or heterochromatin prior to the onset of these diseases could potentially better protect the genome and protein-coding DNA, reduce the incidence of aging-related diseases, and thus lead to better health during aging.
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18
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Oluwadare O, Highsmith M, Cheng J. An Overview of Methods for Reconstructing 3-D Chromosome and Genome Structures from Hi-C Data. Biol Proced Online 2019; 21:7. [PMID: 31049033 PMCID: PMC6482566 DOI: 10.1186/s12575-019-0094-0] [Citation(s) in RCA: 69] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Accepted: 04/01/2019] [Indexed: 01/08/2023] Open
Abstract
Over the past decade, methods for predicting three-dimensional (3-D) chromosome and genome structures have proliferated. This has been primarily due to the development of high-throughput, next-generation chromosome conformation capture (3C) technologies, which have provided next-generation sequencing data about chromosome conformations in order to map the 3-D genome structure. The introduction of the Hi-C technique-a variant of the 3C method-has allowed researchers to extract the interaction frequency (IF) for all loci of a genome at high-throughput and at a genome-wide scale. In this review we describe, categorize, and compare the various methods developed to map chromosome and genome structures from 3C data-particularly Hi-C data. We summarize the improvements introduced by these methods, describe the approach used for method evaluation, and discuss how these advancements shape the future of genome structure construction.
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Affiliation(s)
- Oluwatosin Oluwadare
- Department of Electrical Engineering and Computer Science, University of Missouri, Columbia, MO 65211 USA
| | - Max Highsmith
- Department of Electrical Engineering and Computer Science, University of Missouri, Columbia, MO 65211 USA
| | - Jianlin Cheng
- Department of Electrical Engineering and Computer Science, University of Missouri, Columbia, MO 65211 USA
- Informatics Institute, University of Missouri, Columbia, MO 65211 USA
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19
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20
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Almonacid M, Terret ME, Verlhac MH. Nuclear positioning as an integrator of cell fate. Curr Opin Cell Biol 2018; 56:122-129. [PMID: 30594054 DOI: 10.1016/j.ceb.2018.12.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2018] [Revised: 08/21/2018] [Accepted: 12/01/2018] [Indexed: 11/28/2022]
Abstract
Cells are the building units of living organisms and consequently adapt to their environment by modulating their intracellular architecture, in particular the position of their nucleus. Important efforts have been made to decipher the molecular mechanisms involved in nuclear positioning. The LINC complex at the nuclear envelope is a very important part of the molecular connectivity between the cell outside and the intranuclear compartment, and thus emerged as a central player in nuclear mechanotransduction. More recent concepts in nuclear mechanotransduction came from studies involving nuclear confined migration, compression or swelling. Also, the effect of nuclear mechanosensitive properties in driving cell differentiation raises the question of nuclear mechanotransduction and gene expression and recent efforts have been done to tackle it, even though it remains difficult to address in a direct manner. Eventually, an original mechanism of nucleus positioning, mechanotransduction and regulation of gene expression in the non-adherent, non-polarized mouse oocyte, highlights the fact that nuclear positioning is an important developmental issue.
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Affiliation(s)
- Maria Almonacid
- CIRB, Collège de France, and CNRS-UMR7241 and INSERM-U1050, Equipe Labellisée FRM, Paris F-75005, France.
| | - Marie-Emilie Terret
- CIRB, Collège de France, and CNRS-UMR7241 and INSERM-U1050, Equipe Labellisée FRM, Paris F-75005, France
| | - Marie-Hélène Verlhac
- CIRB, Collège de France, and CNRS-UMR7241 and INSERM-U1050, Equipe Labellisée FRM, Paris F-75005, France
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21
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Adriaens C, Serebryannyy LA, Feric M, Schibler A, Meaburn KJ, Kubben N, Trzaskoma P, Shachar S, Vidak S, Finn EH, Sood V, Pegoraro G, Misteli T. Blank spots on the map: some current questions on nuclear organization and genome architecture. Histochem Cell Biol 2018; 150:579-92. [PMID: 30238154 DOI: 10.1007/s00418-018-1726-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [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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22
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Sarrate Z, Solé M, Vidal F, Anton E, Blanco J. Chromosome positioning and male infertility: it comes with the territory. J Assist Reprod Genet 2018; 35:1929-38. [PMID: 30229502 DOI: 10.1007/s10815-018-1313-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2018] [Accepted: 09/11/2018] [Indexed: 01/30/2023] Open
Abstract
The production of functional spermatozoa through spermatogenesis requires a spatially and temporally highly regulated gene expression pattern, which in case of alterations, leads to male infertility. Changes of gene expression by chromosome anomalies, gene variants, and epigenetic alterations have been described as the main genetic causes of male infertility. Recent molecular and cytogenetic approaches have revealed that higher order chromosome positioning is essential for basic genome functions, including gene expression. This review addresses this issue by exposing well-founded evidences which support that alterations on the chromosome topology in spermatogenetic cells leads to defective sperm function and could be considered as an additional genetic cause of male infertility.
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23
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Wang S, Stoops E, Cp U, Markus B, Reuveny A, Ordan E, Volk T. Mechanotransduction via the LINC complex regulates DNA replication in myonuclei. J Cell Biol 2018; 217:2005-2018. [PMID: 29650775 PMCID: PMC5987719 DOI: 10.1083/jcb.201708137] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2017] [Revised: 02/08/2018] [Accepted: 03/27/2018] [Indexed: 12/26/2022] Open
Abstract
Nuclear mechanotransduction has been implicated in the control of chromatin organization and gene expression. Wang et al. show that, in Drosophila myofibers, the LINC complex is required for the regulation of DNA replication and synchronized cell-cycle progression in myonuclei. Nuclear mechanotransduction has been implicated in the control of chromatin organization; however, its impact on functional contractile myofibers is unclear. We found that deleting components of the linker of nucleoskeleton and cytoskeleton (LINC) complex in Drosophila melanogaster larval muscles abolishes the controlled and synchronized DNA endoreplication, typical of nuclei across myofibers, resulting in increased and variable DNA content in myonuclei of individual myofibers. Moreover, perturbation of LINC-independent mechanical input after knockdown of β-Integrin in larval muscles similarly led to increased DNA content in myonuclei. Genome-wide RNA-polymerase II occupancy analysis in myofibers of the LINC mutant klar indicated an altered binding profile, including a significant decrease in the chromatin regulator barrier-to-autointegration factor (BAF) and the contractile regulator Troponin C. Importantly, muscle-specific knockdown of BAF led to increased DNA content in myonuclei, phenocopying the LINC mutant phenotype. We propose that mechanical stimuli transmitted via the LINC complex act via BAF to regulate synchronized cell-cycle progression of myonuclei across single myofibers.
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Affiliation(s)
- Shuoshuo Wang
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Elizabeth Stoops
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Unnikannan Cp
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Barak Markus
- G-INCPM/Mantoux Institute for Bioinformatics, Weizmann Institute of Science, Rehovot, Israel
| | - Adriana Reuveny
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Elly Ordan
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Talila Volk
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
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24
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Abstract
Peripheral and abundant noncoding DNA has been hypothesized to protect the genome and the central protein-coding sequences against DNA damage in somatic genome. In the cytosol, invading exogenous nucleic acids may first be deactivated by small RNAs encoded by noncoding DNA via mechanisms similar to the prokaryotic CRISPR-Cas system. In the nucleus, the radicals generated by radiation in the cytosol, radiation energy and invading exogenous nucleic acids are absorbed, blocked and/or reduced by peripheral heterochromatin, and damaged DNA in heterochromatin is removed and excluded from the nucleus to the cytoplasm through nuclear pore complexes. To further strengthen the hypothesis, this review summarizes the experimental evidence supporting the protective function of noncoding DNA in the genome of male germ cells. Based on these data, this review provides evidence supporting the protective role of noncoding DNA in the genome defense of sperm genome through similar mechanisms to those of the somatic genome.
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Affiliation(s)
- Guo-Hua Qiu
- Fujian Provincial Key Laboratory for the Prevention & Control of Animal Infectious Diseases & Biotechnology; Key Laboratory of Preventive Veterinary Medicine and Biotechnology, Fujian Province University; College of Life Sciences, Longyan University, Longyan 364012, Fujian, PR China
| | - Cuiqin Huang
- Fujian Provincial Key Laboratory for the Prevention & Control of Animal Infectious Diseases & Biotechnology; Key Laboratory of Preventive Veterinary Medicine and Biotechnology, Fujian Province University; College of Life Sciences, Longyan University, Longyan 364012, Fujian, PR China
| | - Xintian Zheng
- Fujian Provincial Key Laboratory for the Prevention & Control of Animal Infectious Diseases & Biotechnology; Key Laboratory of Preventive Veterinary Medicine and Biotechnology, Fujian Province University; College of Life Sciences, Longyan University, Longyan 364012, Fujian, PR China
| | - Xiaoyan Yang
- Fujian Provincial Key Laboratory for the Prevention & Control of Animal Infectious Diseases & Biotechnology; Key Laboratory of Preventive Veterinary Medicine and Biotechnology, Fujian Province University; College of Life Sciences, Longyan University, Longyan 364012, Fujian, PR China
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25
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Abstract
The ability of cells to respond to mechanical forces is critical for numerous biological processes. Emerging evidence indicates that external mechanical forces trigger changes in nuclear envelope structure and composition, chromatin organization and gene expression. However, it remains unclear if these processes originate in the nucleus or are downstream of cytoplasmic signals. Here we discuss recent findings that support a direct role of the nucleus in cellular mechanosensing and highlight novel tools to study nuclear mechanotransduction.
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26
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Hall LL, Byron M, Carone DM, Whitfield TW, Pouliot GP, Fischer A, Jones P, Lawrence JB. Demethylated HSATII DNA and HSATII RNA Foci Sequester PRC1 and MeCP2 into Cancer-Specific Nuclear Bodies. Cell Rep 2017; 18:2943-2956. [PMID: 28329686 DOI: 10.1016/j.celrep.2017.02.072] [Citation(s) in RCA: 64] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2015] [Revised: 01/03/2017] [Accepted: 02/23/2017] [Indexed: 02/05/2023] Open
Abstract
This study reveals that high-copy satellite II (HSATII) sequences in the human genome can bind and impact distribution of chromatin regulatory proteins and that this goes awry in cancer. In many cancers, master regulatory proteins form two types of cancer-specific nuclear bodies, caused by locus-specific deregulation of HSATII. DNA demethylation at the 1q12 mega-satellite, common in cancer, causes PRC1 aggregation into prominent Cancer-Associated Polycomb (CAP) bodies. These loci remain silent, whereas HSATII loci with reduced PRC1 become derepressed, reflecting imbalanced distribution of UbH2A on these and other PcG-regulated loci. Large nuclear foci of HSATII RNA form and sequester copious MeCP2 into Cancer-Associated Satellite Transcript (CAST) bodies. Hence, HSATII DNA and RNA have an exceptional capacity to act as molecular sponges and sequester chromatin regulatory proteins into abnormal nuclear bodies in cancer. The compartmentalization of regulatory proteins within nuclear structure, triggered by demethylation of "junk" repeats, raises the possibility that this contributes to further compromise of the epigenome and neoplastic progression.
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Affiliation(s)
- Lisa L Hall
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, MA 01655, USA
| | - Meg Byron
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, MA 01655, USA
| | - Dawn M Carone
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, MA 01655, USA
| | - Troy W Whitfield
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, MA 01655, USA; Program in Bioinformatics and Integrative Biology, University of Massachusetts Medical School, Worcester, MA 01655, USA
| | - Gayle P Pouliot
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, MA 01655, USA
| | - Andrew Fischer
- Department of Pathology, University of Massachusetts Medical School, Worcester, MA 01655, USA
| | - Peter Jones
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, MA 01655, USA
| | - Jeanne B Lawrence
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, MA 01655, USA.
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27
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Qiu GH, Yang X, Zheng X, Huang C. The eukaryotic genome is structurally and functionally more like a social insect colony than a book. Epigenomics 2017; 9:1469-1483. [PMID: 28972397 DOI: 10.2217/epi-2017-0059] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Traditionally, the genome has been described as the 'book of life'. However, the metaphor of a book may not reflect the dynamic nature of the structure and function of the genome. In the eukaryotic genome, the number of centrally located protein-coding sequences is relatively constant across species, but the amount of noncoding DNA increases considerably with the increase of organismal evolutional complexity. Therefore, it has been hypothesized that the abundant peripheral noncoding DNA protects the genome and the central protein-coding sequences in the eukaryotic genome. Upon comparison with the habitation, sociality and defense mechanisms of a social insect colony, it is found that the genome is similar to a social insect colony in various aspects. A social insect colony may thus be a better metaphor than a book to describe the spatial organization and physical functions of the genome. The potential implications of the metaphor are also discussed.
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Affiliation(s)
- Guo-Hua Qiu
- Fujian Provincial Key Laboratory for the Prevention & Control of Animal Infectious Diseases & Biotechnology, College of Life Sciences, Longyan University, Longyan 364012, Fujian, PR China
| | - Xiaoyan Yang
- Fujian Provincial Key Laboratory for the Prevention & Control of Animal Infectious Diseases & Biotechnology, College of Life Sciences, Longyan University, Longyan 364012, Fujian, PR China
| | - Xintian Zheng
- Fujian Provincial Key Laboratory for the Prevention & Control of Animal Infectious Diseases & Biotechnology, College of Life Sciences, Longyan University, Longyan 364012, Fujian, PR China
| | - Cuiqin Huang
- Fujian Provincial Key Laboratory for the Prevention & Control of Animal Infectious Diseases & Biotechnology, College of Life Sciences, Longyan University, Longyan 364012, Fujian, PR China
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28
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Rawlings J. Roles of SMC Complexes During T Lymphocyte Development and Function. Advances in Protein Chemistry and Structural Biology 2017. [DOI: 10.1016/bs.apcsb.2016.08.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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29
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Watson LA, Tsai LH. In the loop: how chromatin topology links genome structure to function in mechanisms underlying learning and memory. Curr Opin Neurobiol 2016; 43:48-55. [PMID: 28024185 DOI: 10.1016/j.conb.2016.12.002] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2016] [Revised: 12/01/2016] [Accepted: 12/05/2016] [Indexed: 12/18/2022]
Abstract
Different aspects of learning, memory, and cognition are regulated by epigenetic mechanisms such as covalent DNA modifications and histone post-translational modifications. More recently, the modulation of chromatin architecture and nuclear organization is emerging as a key factor in dynamic transcriptional regulation of the post-mitotic neuron. For instance, neuronal activity induces relocalization of gene loci to 'transcription factories', and specific enhancer-promoter looping contacts allow for precise transcriptional regulation. Moreover, neuronal activity-dependent DNA double-strand break formation in the promoter of immediate early genes appears to overcome topological constraints on transcription. Together, these findings point to a critical role for genome topology in integrating dynamic environmental signals to define precise spatiotemporal gene expression programs supporting cognitive processes.
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Affiliation(s)
| | - Li-Huei Tsai
- Picower Institute for Learning and Memory, USA; Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Building 46, Room 4235A, Cambridge, MA 02139, USA.
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30
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Höfer CT, Jolmes F, Haralampiev I, Veit M, Herrmann A. Influenza A virus nucleoprotein targets subnuclear structures. Cell Microbiol 2016; 19. [PMID: 27696627 DOI: 10.1111/cmi.12679] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2015] [Revised: 09/20/2016] [Accepted: 09/30/2016] [Indexed: 02/01/2023]
Abstract
The Influenza A virus nucleoprotein (NP) is the major protein component of the genomic viral ribonucleoprotein (vRNP) complexes, which are the replication- and transcription-competent units of Influenza viruses. Early during infection, NP mediates import of vRNPs into the host cell nucleus where viral replication and transcription take place; also newly synthesized NP molecules are targeted into the nucleus, enabling coreplicational assembly of progeny vRNPs. NP reportedly acts as regulatory factor during infection, and it is known to be involved in numerous interactions with host cell proteins. Yet, the NP-host cell interplay is still poorly understood. Here, we report that NP significantly interacts with the nuclear compartment and displays distinct affinities for different subnuclear structures. NP subnuclear behavior was studied by expression of fluorescent NP fusion proteins - including obligate monomeric NP - and site-specific fluorescence photoactivation measurements. We found that NP constructs accumulate in subnuclear domains frequently found adjacent to or overlapping with promyelocytic leukemia bodies and Cajal bodies. Targeting of NP to Cajal bodies could further be demonstrated in the context of virus infection. We hypothesize that by targeting functional nuclear organization, NP might either link viral replication to specific cellular machinery or interfere with host cell processes.
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Affiliation(s)
- Chris T Höfer
- IRI Life Sciences, Department of Biology, Molecular Biophysics, Humboldt-Universität zu Berlin, Berlin, Germany.,Department of Veterinary Medicine, Institute of Virology, Freie Universität Berlin, Berlin, Germany
| | - Fabian Jolmes
- IRI Life Sciences, Department of Biology, Molecular Biophysics, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Ivan Haralampiev
- IRI Life Sciences, Department of Biology, Molecular Biophysics, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Michael Veit
- Department of Veterinary Medicine, Institute of Virology, Freie Universität Berlin, Berlin, Germany
| | - Andreas Herrmann
- IRI Life Sciences, Department of Biology, Molecular Biophysics, Humboldt-Universität zu Berlin, Berlin, Germany
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Nandakumar V, Hansen N, Glenn HL, Han JH, Helland S, Hernandez K, Senechal P, Johnson RH, Bussey KJ, Meldrum DR. Vorinostat differentially alters 3D nuclear structure of cancer and non-cancerous esophageal cells. Sci Rep 2016; 6:30593. [PMID: 27503568 DOI: 10.1038/srep30593] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2016] [Accepted: 07/05/2016] [Indexed: 12/16/2022] Open
Abstract
The histone deacetylase (HDAC) inhibitor vorinostat has received significant attention in recent years as an 'epigenetic' drug used to treat solid tumors. However, its mechanisms of action are not entirely understood, particularly with regard to its interaction with the aberrations in 3D nuclear structure that accompany neoplastic progression. We investigated the impact of vorinostat on human esophageal epithelial cell lines derived from normal, metaplastic (pre-cancerous), and malignant tissue. Using a combination of novel optical computed tomography (CT)-based quantitative 3D absorption microscopy and conventional confocal fluorescence microscopy, we show that subjecting malignant cells to vorinostat preferentially alters their 3D nuclear architecture relative to non-cancerous cells. Optical CT (cell CT) imaging of fixed single cells showed that drug-treated cancer cells exhibit significant alterations in nuclear morphometry. Confocal microscopy revealed that vorinostat caused changes in the distribution of H3K9ac-marked euchromatin and H3K9me3-marked constitutive heterochromatin. Additionally, 3D immuno-FISH showed that drug-induced expression of the DNA repair gene MGMT was accompanied by spatial relocation toward the center of the nucleus in the nuclei of metaplastic but not in non-neoplastic cells. Our data suggest that vorinostat's differential modulation of 3D nuclear architecture in normal and abnormal cells could play a functional role in its anti-cancer action.
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Abstract
The view of the cell nucleus has evolved from an isolated, static organelle to a dynamic structure integrated with other mechanical elements of the cell. Both dynamics and integration appear to contribute to a mechanical regulation of genome expression. Here, we review physical structures inside the nucleus at different length scales and the dynamic reorganization modulated by cellular forces. First, we discuss nuclear organization focusing on self-assembly and disassembly of DNA structures and various nuclear bodies. We then discuss the importance of connections from the chromatin fiber through the nuclear envelope to the rest of the cell as they relate to mechanobiology. Finally, we discuss how cell stimulation, both chemical and physical, can alter nuclear structures and ultimately cellular function in healthy cells and in some model diseases. The view of chromatin and nuclear bodies as mechanical entities integrated with force generation from the cytoskeleton combines polymer physics with cell biology and medicine.
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Affiliation(s)
- Stephen T. Spagnol
- Department of Chemical Engineering, Carnegie Mellon University, 5000 Forbes Ave., Pittsburgh, PA 15213, USA
| | - Travis J. Armiger
- Department of Chemical Engineering, Carnegie Mellon University, 5000 Forbes Ave., Pittsburgh, PA 15213, USA
| | - Kris Noel Dahl
- Department of Chemical Engineering, Carnegie Mellon University, 5000 Forbes Ave., Pittsburgh, PA 15213, USA
- Department of Biomedical Engineering, Carnegie Mellon University, Pittsburgh, USA
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33
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Spagnol ST, Dahl KN. Spatially Resolved Quantification of Chromatin Condensation through Differential Local Rheology in Cell Nuclei Fluorescence Lifetime Imaging. PLoS One 2016; 11:e0146244. [PMID: 26765322 PMCID: PMC4713418 DOI: 10.1371/journal.pone.0146244] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2015] [Accepted: 12/15/2015] [Indexed: 02/06/2023] Open
Abstract
The linear sequence of DNA encodes access to the complete set of proteins that carry out cellular functions. Yet, much of the functionality appropriate for each cell is nested within layers of dynamic regulation and organization, including a hierarchy of chromatin structural states and spatial arrangement within the nucleus. There remain limitations in our understanding of gene expression within the context of nuclear organization from an inability to characterize hierarchical chromatin organization in situ. Here we demonstrate the use of fluorescence lifetime imaging microscopy (FLIM) to quantify and spatially resolve chromatin condensation state using cell-permeable, DNA-binding dyes (Hoechst 33342 and PicoGreen). Through in vitro and in situ experiments we demonstrate the sensitivity of fluorescence lifetime to condensation state through the mechanical effects that accompany the structural changes and are reflected through altered viscosity. The establishment of FLIM for resolving and quantifying chromatin condensation state opens the door for single-measurement mechanical studies of the nucleus and for characterizing the role of genome structure and organization in nuclear processes that accompany physiological and pathological changes.
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Affiliation(s)
- Stephen T. Spagnol
- Department of Chemical Engineering, Carnegie Mellon University, 5000 Forbes Ave., Pittsburgh, Pennsylvania, 15213, United States of America
| | - Kris Noel Dahl
- Department of Chemical Engineering, Carnegie Mellon University, 5000 Forbes Ave., Pittsburgh, Pennsylvania, 15213, United States of America
- Department of Biomedical Engineering, Carnegie Mellon University, 5000 Forbes Ave., Pittsburgh, Pennsylvania, 15213, United States of America
- * E-mail:
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34
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Qiu GH. Genome defense against exogenous nucleic acids in eukaryotes by non-coding DNA occurs through CRISPR-like mechanisms in the cytosol and the bodyguard protection in the nucleus. Mutation Research/Reviews in Mutation Research 2016; 767:31-41. [DOI: 10.1016/j.mrrev.2016.01.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2015] [Revised: 10/22/2015] [Accepted: 01/03/2016] [Indexed: 02/07/2023]
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35
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Kirmes I, Szczurek A, Prakash K, Charapitsa I, Heiser C, Musheev M, Schock F, Fornalczyk K, Ma D, Birk U, Cremer C, Reid G. A transient ischemic environment induces reversible compaction of chromatin. Genome Biol 2015; 16:246. [PMID: 26541514 PMCID: PMC4635527 DOI: 10.1186/s13059-015-0802-2] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2015] [Accepted: 10/09/2015] [Indexed: 11/10/2022] Open
Abstract
Background Cells detect and adapt to hypoxic and nutritional stress through immediate transcriptional, translational and metabolic responses. The environmental effects of ischemia on chromatin nanostructure were investigated using single molecule localization microscopy of DNA binding dyes and of acetylated histones, by the sensitivity of chromatin to digestion with DNAseI, and by fluorescence recovery after photobleaching (FRAP) of core and linker histones. Results Short-term oxygen and nutrient deprivation of the cardiomyocyte cell line HL-1 induces a previously undescribed chromatin architecture, consisting of large, chromatin-sparse voids interspersed between DNA-dense hollow helicoid structures 40–700 nm in dimension. The chromatin compaction is reversible, and upon restitution of normoxia and nutrients, chromatin transiently adopts a more open structure than in untreated cells. The compacted state of chromatin reduces transcription, while the open chromatin structure induced upon recovery provokes a transitory increase in transcription. Digestion of chromatin with DNAseI confirms that oxygen and nutrient deprivation induces compaction of chromatin. Chromatin compaction is associated with depletion of ATP and redistribution of the polyamine pool into the nucleus. FRAP demonstrates that core histones are not displaced from compacted chromatin; however, the mobility of linker histone H1 is considerably reduced, to an extent that far exceeds the difference in histone H1 mobility between heterochromatin and euchromatin. Conclusions These studies exemplify the dynamic capacity of chromatin architecture to physically respond to environmental conditions, directly link cellular energy status to chromatin compaction and provide insight into the effect ischemia has on the nuclear architecture of cells. Electronic supplementary material The online version of this article (doi:10.1186/s13059-015-0802-2) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Ina Kirmes
- Institute for Molecular Biology, 55128, Mainz, Germany
| | | | - Kirti Prakash
- Institute for Molecular Biology, 55128, Mainz, Germany.,Institute of Pharmacy and Molecular Biotechnology, University of Heidelberg, 69120, Heidelberg, Germany
| | | | | | | | | | - Karolina Fornalczyk
- Institute for Molecular Biology, 55128, Mainz, Germany.,Department of Molecular Biophysics, University of Łódź, Łódź, Poland
| | - Dongyu Ma
- Institute for Molecular Biology, 55128, Mainz, Germany.,Centre for Biomedicine and Medical Technology Mannheim (CBTM), University of Heidelberg, 68167, Mannheim, Germany
| | - Udo Birk
- Institute for Molecular Biology, 55128, Mainz, Germany
| | - Christoph Cremer
- Institute for Molecular Biology, 55128, Mainz, Germany. .,Institute of Pharmacy and Molecular Biotechnology, University of Heidelberg, 69120, Heidelberg, Germany.
| | - George Reid
- Institute for Molecular Biology, 55128, Mainz, Germany.
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36
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Awazu A. Nuclear dynamical deformation induced hetero- and euchromatin positioning. Phys Rev E Stat Nonlin Soft Matter Phys 2015; 92:032709. [PMID: 26465500 DOI: 10.1103/physreve.92.032709] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2015] [Indexed: 06/05/2023]
Abstract
We studied the role of active deformation dynamics in cell nuclei in chromatin positioning. Model chains containing two types of regions, with high (euchromatic) or low (heterochromatic) mobility, were confined in a pulsating container simulating a nucleus showing dynamic deformations. Brownian dynamic simulations show that the positioning of low mobility regions changes from sites near the periphery to the center if the affinity between these regions and the container periphery disappears. The former and latter positionings are similar to the "conventional" and "inverted" chromatin positionings in nuclei of normal differentiated cells and cells lacking Lamin-related proteins. Additionally, nuclear dynamical deformation played essential roles in "inverted" chromatin positioning.
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Affiliation(s)
- Akinori Awazu
- Department of Mathematical and Life Sciences, Hiroshima University and Research Center for Mathematics on Chromatin Live Dynamics, Kagami-yama 1-3-1, Higashi-Hiroshima 739-8526, Japan
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37
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Dobigny G, Britton-Davidian J, Robinson TJ. Chromosomal polymorphism in mammals: an evolutionary perspective. Biol Rev Camb Philos Soc 2015; 92:1-21. [PMID: 26234165 DOI: 10.1111/brv.12213] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2014] [Revised: 06/23/2015] [Accepted: 07/09/2015] [Indexed: 12/28/2022]
Abstract
Although chromosome rearrangements (CRs) are central to studies of genome evolution, our understanding of the evolutionary consequences of the early stages of karyotypic differentiation (i.e. polymorphism), especially the non-meiotic impacts, is surprisingly limited. We review the available data on chromosomal polymorphisms in mammals so as to identify taxa that hold promise for developing a more comprehensive understanding of chromosomal change. In doing so, we address several key questions: (i) to what extent are mammalian karyotypes polymorphic, and what types of rearrangements are principally involved? (ii) Are some mammalian lineages more prone to chromosomal polymorphism than others? More specifically, do (karyotypically) polymorphic mammalian species belong to lineages that are also characterized by past, extensive karyotype repatterning? (iii) How long can chromosomal polymorphisms persist in mammals? We discuss the evolutionary implications of these questions and propose several research avenues that may shed light on the role of chromosome change in the diversification of mammalian populations and species.
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Affiliation(s)
- Gauthier Dobigny
- Institut de Recherche pour le Développement, Centre de Biologie pour la Gestion des Populations (UMR IRD-INRA-Cirad-Montpellier SupAgro), Campus International de Baillarguet, CS30016, 34988, Montferrier-sur-Lez, France
| | - Janice Britton-Davidian
- Institut des Sciences de l'Evolution, Université de Montpellier, CNRS, IRD, EPHE, Cc065, Place Eugène Bataillon, 34095, Montpellier Cedex 5, France
| | - Terence J Robinson
- Evolutionary Genomics Group, Department of Botany and Zoology, Stellenbosch University, Private Bag X1, Matieland, Stellenbosch, 7062, South Africa
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38
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Paz N, Felipe-Blanco I, Royo F, Zabala A, Guerra-Merino I, García-Orad Á, Zugaza JL, Parada LA. Expression of the DYRK1A gene correlates with its 3D positioning in the interphase nucleus of Down syndrome cells. Chromosome Res 2015; 23:285-98. [PMID: 25645734 DOI: 10.1007/s10577-015-9467-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2014] [Revised: 01/20/2015] [Accepted: 01/21/2015] [Indexed: 10/24/2022]
Abstract
Down syndrome is a common birth defect caused by trisomy of chromosome 21. Chromosomes occupy distinct territories in interphase nuclei, and their distribution within the nuclear space is nonrandom. In humans with Down syndrome, two chromosomes 21 frequently localize proximal to one another and distant from the third chromosome. Here, we investigated the nuclear organization of DYRK1A and SOD1, two genes mapping to chromosome 21 that greatly contribute to the pathology. We found that DYRK1A conserves its central positioning between normal and trisomic cells, whereas SOD1 adopts more peripheral distribution in trisomic cells. We also found that the relative position of these genes with respect to each other varies among the different copies of chromosome territories 21 within a cell, and that this distinct distribution is associated with differences in their expression levels. All together, our results may explain, at least in part, the difference in the expression level of these two genes implicated in the pathogenesis of Down syndrome.
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Affiliation(s)
- Nerea Paz
- GSI Helmholtzzentrum für Schwerionenforschung, Biophysics Department, Planckstraβe 1, 64291, Darmstadt, Germany
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39
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Razin SV, Borunova VV, Iarovaia OV, Vassetzky YS. Nuclear matrix and structural and functional compartmentalization of the eucaryotic cell nucleus. Biochemistry (Mosc) 2015; 79:608-18. [PMID: 25108324 DOI: 10.1134/s0006297914070037] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Becoming popular at the end of the 20th century, the concept of the nuclear matrix implies the existence of a nuclear skeleton that organizes functional elements in the cell nucleus. This review presents a critical analysis of the results obtained in the study of nuclear matrix in the light of current views on the organization of the cell nucleus. Numerous studies of nuclear matrix have failed to provide evidence of the existence of such a structure. Moreover, the existence of a filamentous structure that supports the nuclear compartmentalization appears to be unnecessary, since this function is performed by the folded genome itself.
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Affiliation(s)
- S V Razin
- Institute of Gene Biology, Russian Academy of Sciences, Moscow, 119334, Russia.
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40
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Qiu GH. Protection of the genome and central protein-coding sequences by non-coding DNA against DNA damage from radiation. Mutation Research/Reviews in Mutation Research 2015; 764:108-17. [DOI: 10.1016/j.mrrev.2015.04.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2014] [Revised: 03/11/2015] [Accepted: 04/22/2015] [Indexed: 01/08/2023]
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41
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Del Prete S, Arpón J, Sakai K, Andrey P, Gaudin V. Nuclear architecture and chromatin dynamics in interphase nuclei of Arabidopsis thaliana. Cytogenet Genome Res 2014; 143:28-50. [PMID: 24992956 DOI: 10.1159/000363724] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The interphase cell nucleus is extraordinarily complex, ordered, and dynamic. In the last decade, remarkable progress has been made in deciphering the functional organisation of the cell nucleus, and intricate relationships between genome functions (transcription, DNA repair, or replication) and various nuclear compartments have been revealed. In this review, we describe the architecture of the Arabidopsis thaliana interphase cell nucleus and discuss the dynamic nature of its organisation. We underline the need for further developments in quantitative and modelling approaches to nuclear organization.
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Affiliation(s)
- Stefania Del Prete
- INRA, UMR1318-AgroParisTech, Institut Jean-Pierre Bourgin (IJPB), INRA-Centre de Versailles-Grignon, Versailles, France
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42
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Lund E, Oldenburg AR, Collas P. Enriched domain detector: a program for detection of wide genomic enrichment domains robust against local variations. Nucleic Acids Res 2014; 42:e92. [PMID: 24782521 PMCID: PMC4066758 DOI: 10.1093/nar/gku324] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2014] [Revised: 04/03/2014] [Accepted: 04/07/2014] [Indexed: 12/31/2022] Open
Abstract
Nuclear lamins contact the genome at the nuclear periphery through large domains and are involved in chromatin organization. Among broad peak calling algorithms available to date, none are suited for mapping lamin-genome interactions genome wide. We disclose a novel algorithm, enriched domain detector (EDD), for analysis of broad enrichment domains from chromatin immunoprecipitation (ChIP)-seq data. EDD enables discovery of genomic domains interacting with broadly distributed proteins, such as A- and B-type lamins affinity isolated by ChIP. The advantages of EDD over existing broad peak callers are sensitivity to domain width rather than enrichment strength at a particular site, and robustness against local variations.
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Affiliation(s)
- Eivind Lund
- Stem Cell Epigenetics Laboratory, Institute of Basic Medical Sciences, Faculty of Medicine, University of Oslo, and Norwegian Center for Stem Cell Research, PO Box 1112 Blindern, 0317 Oslo, Norway
| | - Anja R Oldenburg
- Stem Cell Epigenetics Laboratory, Institute of Basic Medical Sciences, Faculty of Medicine, University of Oslo, and Norwegian Center for Stem Cell Research, PO Box 1112 Blindern, 0317 Oslo, Norway
| | - Philippe Collas
- Stem Cell Epigenetics Laboratory, Institute of Basic Medical Sciences, Faculty of Medicine, University of Oslo, and Norwegian Center for Stem Cell Research, PO Box 1112 Blindern, 0317 Oslo, Norway
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43
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Abstract
Homologous recombination is crucial for genome stability and for genetic exchange. Although our knowledge of the principle steps in recombination and its machinery is well advanced, homology search, the critical step of exploring the genome for homologous sequences to enable recombination, has remained mostly enigmatic. However, recent methodological advances have provided considerable new insights into this fundamental step in recombination that can be integrated into a mechanistic model. These advances emphasize the importance of genomic proximity and nuclear organization for homology search and the critical role of homology search mediators in this process. They also aid our understanding of how homology search might lead to unwanted and potentially disease-promoting recombination events.
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Affiliation(s)
- Jörg Renkawitz
- 1] Department of Molecular Cell Biology, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany. [2] Institute of Science and Technology (IST) Austria, 3400 Klosterneuburg, Austria. [3]
| | - Claudio A Lademann
- 1] Department of Molecular Cell Biology, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany. [2]
| | - Stefan Jentsch
- Department of Molecular Cell Biology, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany
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44
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Abstract
A conserved organizational feature of eukaryotic nuclei is the peripheral heterochromatin compartment, which provides a protected area for epigenetically silent genes and gene-poor DNA. In metazoan cells this compartment is associated with the nuclear lamina, the protein meshwork at the inner edge of the nucleus. Heterochromatin-nuclear lamina interactions promote epigenetic gene silencing, which may drive many normal and diseased biological processes. We recently obtained evidence that a previously unstudied human protein, PRR14, participates in the tethering of heterochromatin to the inner nuclear periphery. PRR14 associates with the nuclear lamina and attaches to heterochromatin through its binding partner, heterochromatin protein 1 (HP1). After disassembly early in mitosis, PRR14 reassembles in two steps, first binding to anaphase chromosomes through HP1, followed by association with the nuclear lamina in telophase. PRR14 may thereby play a role in specifying HP1-bound heterochromatin for reattachment to the nuclear lamina at mitotic exit. Here we review the relevant literature, summarize our initial work, and provide additional comments and findings.
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Affiliation(s)
- Andrey Poleshko
- Fox Chase Cancer Center; Institute for Cancer Research; Philadelphia, PA USA
| | - Richard A Katz
- Fox Chase Cancer Center; Institute for Cancer Research; Philadelphia, PA USA
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45
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Abstract
Chromosomes within eukaryotic cell nuclei at interphase are not positioned at random, since gene-rich chromosomes are predominantly found towards the interior of the cell nucleus across a number of cell types. The physical mechanisms that could drive and maintain the spatial segregation of chromosomes based on gene density are unknown. Here, we identify a mechanism for such segregation, showing that the territorial organization of chromosomes, another central feature of nuclear organization, emerges naturally from our model. Our computer simulations indicate that gene density-dependent radial segregation of chromosomes arises as a robust consequence of differences in non-equilibrium activity across chromosomes. Arguing that such differences originate in the inhomogeneous distribution of ATP-dependent chromatin remodeling and transcription machinery on each chromosome, we show that a variety of non-random positional distributions emerge through the interplay of such activity, nuclear shape and specific interactions of chromosomes with the nuclear envelope. Results from our model are in reasonable agreement with experimental data and we make a number of predictions that can be tested in experiments.
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Affiliation(s)
- Nirmalendu Ganai
- Department of Physics, Nabadwip Vidyasagar College, Nabadwip, Nadia 741302, India, TIFR Centre for Interdisciplinary Sciences, 21 Brundavan Colony, Narsingi, Hyderabad 500075, India, Centre for Advanced Materials, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032, India, The Institute of Mathematical Sciences, C.I.T. Campus, Taramani, Chennai 600 113, India, Mechanobiology Institute, National University of Singapore, T-Lab, #10-01, 5A Engineering Drive 1, Singapore 117411, Singapore and Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore 117543, Singapore
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46
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Wilczynski GM. Significance of higher-order chromatin architecture for neuronal function and dysfunction. Neuropharmacology 2014; 80:28-33. [PMID: 24456745 DOI: 10.1016/j.neuropharm.2014.01.016] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2013] [Revised: 01/08/2014] [Accepted: 01/09/2014] [Indexed: 02/08/2023]
Abstract
Recent studies in neurons indicate that the large-scale chromatin architectural framework, including chromosome territories or lamina-associated chromatin, undergoes dynamic changes that represent an emergent level of regulation of neuronal gene-expression. This phenomenon has been implicated in neuronal differentiation, long-term potentiation, seizures, and disorders of neural plasticity such as Rett syndrome and epilepsy.
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Affiliation(s)
- Grzegorz M Wilczynski
- Nencki Institute of Experimental Biology, Polish Academy of Sciences, Pasteura 3, 02-093 Warsaw, Poland.
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47
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LeBlanc SE, Wu Q, Barutcu AR, Xiao H, Ohkawa Y, Imbalzano AN. The PPARγ locus makes long-range chromatin interactions with selected tissue-specific gene loci during adipocyte differentiation in a protein kinase A dependent manner. PLoS One 2014; 9:e86140. [PMID: 24465921 PMCID: PMC3896465 DOI: 10.1371/journal.pone.0086140] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2013] [Accepted: 12/05/2013] [Indexed: 02/05/2023] Open
Abstract
Differentiation signaling results in reprogramming of cellular gene expression that leads to morphological changes and functional specialization of a precursor cell. This global change in gene expression involves temporal regulation of differentiation-specific genes that are located throughout the genome, raising the idea that genome structure may also be re-organized during cell differentiation to facilitate regulated gene expression. Using in vitro adipocyte differentiation as a model, we explored whether gene organization within the nucleus is altered upon exposure of precursor cells to signaling molecules that induce adipogenesis. The peroxisome proliferator-activated receptor gamma (PPARγ) nuclear hormone receptor is a master determinant of adipogenesis and is required for adipose differentiation. We utilized the chromosome conformation capture (3C) assay to determine whether the position of the PPARγ locus relative to other adipogenic genes is changed during differentiation. We report that the PPARγ2 promoter is transiently positioned in proximity to the promoters of genes encoding adipokines and lipid droplet associated proteins at 6 hours post-differentiation, a time that precedes expression of any of these genes. In contrast, the PPARγ2 promoter was not in proximity to the EF1α promoter, which drives expression of a constitutively active, housekeeping gene that encodes a translation elongation factor, nor was the PPARγ2 promoter in proximity to the promoter driving the expression of the C/EBPα regulatory protein. The formation of the long-range, intergenic interactions involving the PPARγ2 promoter required the regulatory factor C/EBPβ, elevated cyclic AMP (cAMP) levels, and protein kinase A (PKA) signaling. We conclude that genome organization is dynamically remodeled in response to adipogenic signaling, and we speculate that these transient inter-genic interactions may be formed for the purposes of selecting some of the transcriptionally silent tissue-specific loci for subsequent transcriptional activation.
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Affiliation(s)
- Scott E. LeBlanc
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Qiong Wu
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - A. Rasim Barutcu
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Hengyi Xiao
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
- Laboratory of Aging Research, State Key Laboratory of Biotherapy, West China Hospital, West China Medical School, Sichuan University, Chengdu, China
| | - Yasuyuki Ohkawa
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
- Department of Advanced Medical Initiatives, JST-CREST, Faculty of Medicine, Kyushu University, Fukuoka, Japan
| | - Anthony N. Imbalzano
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
- * E-mail:
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48
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Abstract
Multiple cis-elements surrounding the β-globin gene locus combine to target this locus to the nuclear periphery through at least two different epigenetic marks. Increasing evidence points to nuclear compartmentalization as a contributing mechanism for gene regulation, yet mechanisms for compartmentalization remain unclear. In this paper, we use autonomous targeting of bacterial artificial chromosome (BAC) transgenes to reveal cis requirements for peripheral targeting. Three peripheral targeting regions (PTRs) within an HBB BAC bias a competition between pericentric versus peripheral heterochromatin targeting toward the nuclear periphery, which correlates with increased H3K9me3 across the β-globin gene cluster and locus control region. Targeting to both heterochromatin compartments is dependent on Suv39H-mediated H3K9me3 methylation. In different chromosomal contexts, PTRs confer no targeting, targeting to pericentric heterochromatin, or targeting to the periphery. A combination of fluorescent in situ hybridization, BAC transgenesis, and knockdown experiments reveals that peripheral tethering of the endogenous HBB locus depends both on Suv39H-mediated H3K9me3 methylation over hundreds of kilobases surrounding HBB and on G9a-mediated H3K9me2 methylation over flanking sequences in an adjacent lamin-associated domain. Our results demonstrate that multiple cis-elements regulate the overall balance of specific epigenetic marks and peripheral gene targeting.
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Affiliation(s)
- Qian Bian
- Department of Cell and Developmental Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801
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49
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Acloque H, Bonnet-Garnier A, Mompart F, Pinton A, Yerle-Bouissou M. Sperm nuclear architecture is locally modified in presence of a Robertsonian translocation t(13;17). PLoS One 2013; 8:e78005. [PMID: 24205066 PMCID: PMC3815027 DOI: 10.1371/journal.pone.0078005] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2013] [Accepted: 09/17/2013] [Indexed: 11/19/2022] Open
Abstract
In mammals, the non-random organization of the sperm nucleus supports an early function during embryonic development. Altering this organization may interfere with the zygote development and reduce fertility or prolificity. Thus, rare studies on sperm cells from infertile patients described an altered nuclear organization that may be a cause or a consequence of their respective pathologies. Thereby, chromosomal rearrangements and aneuploidy can be studied not only for their adverse effects on production of normal/balanced gametes at meiosis but also for their possible impact on sperm nuclear architecture and the epigenetic consequences of altered chromosome positioning. We decided to compare the global architecture of sperm nuclei from boars, either with a normal chromosome composition or with a Robertsonian translocation involving chromosomes 13 and 17. We hypothesized that the fusion between these chromosomes may change their spatial organization and we examined to what extend it could also modify the global sperm nuclear architecture. Analysis of telomeres, centromeres and gonosomes repartition does not support a global nuclear disorganization. But specific analysis of chromosomes 13 and 17 territories highlights an influence of chromosome 17 for the positioning of the fused chromosomes within the nucleus. We also observed a specific clustering of centromeres depending of the chromosome subtypes. Altogether our results showed that chromosome fusion does not significantly alter sperm nucleus architecture but suggest that centromere remodelling after chromosome fusion locally impacts chromosome positioning.
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Affiliation(s)
- Hervé Acloque
- INRA, UMR444 Génétique Cellulaire, Castanet Tolosan, France
- Université de Toulouse, INP, ENVT, UMR444 Génétique Cellulaire, Toulouse, France
- * E-mail:
| | - Amélie Bonnet-Garnier
- INRA, UMR444 Génétique Cellulaire, Castanet Tolosan, France
- Université de Toulouse, INP, ENVT, UMR444 Génétique Cellulaire, Toulouse, France
| | - Florence Mompart
- INRA, UMR444 Génétique Cellulaire, Castanet Tolosan, France
- Université de Toulouse, INP, ENVT, UMR444 Génétique Cellulaire, Toulouse, France
| | - Alain Pinton
- INRA, UMR444 Génétique Cellulaire, Castanet Tolosan, France
- Université de Toulouse, INP, ENVT, UMR444 Génétique Cellulaire, Toulouse, France
| | - Martine Yerle-Bouissou
- INRA, UMR444 Génétique Cellulaire, Castanet Tolosan, France
- Université de Toulouse, INP, ENVT, UMR444 Génétique Cellulaire, Toulouse, France
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50
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Barton LJ, Pinto BS, Wallrath LL, Geyer PK. The Drosophila nuclear lamina protein otefin is required for germline stem cell survival. Dev Cell 2013; 25:645-54. [PMID: 23806619 DOI: 10.1016/j.devcel.2013.05.023] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2011] [Revised: 01/11/2013] [Accepted: 05/23/2013] [Indexed: 01/27/2023]
Abstract
LEM domain (LEM-D) proteins are components of an extensive protein network that assembles beneath the inner nuclear envelope. Defects in LEM-D proteins cause tissue-restricted human diseases associated with altered stem cell homeostasis. Otefin (Ote) is a Drosophila LEM-D protein that is intrinsically required for female germline stem cell (GSC) maintenance. Previous studies linked Ote loss with transcriptional activation of the key differentiation gene bag-of-marbles (bam), leading to the model in which Ote tethers the bam gene to the nuclear periphery for gene silencing. Using genetic and phenotypic analyses of multiple ote(-/-) backgrounds, we obtained evidence that is inconsistent with this model. We show that bam repression is maintained in ote(-/-) GSCs and that germ cell loss persists in ote(-/-), bam(-/-) mutants, together demonstrating that GSC loss is independent of bam transcription. We show that the primary defect in ote(-/-) GSCs is a block of differentiation, which ultimately leads to germ cell death.
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Affiliation(s)
- Lacy J Barton
- Department of Biochemistry, University of Iowa, College of Medicine, Iowa City, IA 52242, USA
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