1
|
Pabba MK, Meyer J, Celikay K, Schermelleh L, Rohr K, Cardoso MC. DNA choreography: correlating mobility and organization of DNA across different resolutions from loops to chromosomes. Histochem Cell Biol 2024:10.1007/s00418-024-02285-x. [PMID: 38758428 DOI: 10.1007/s00418-024-02285-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/27/2024] [Indexed: 05/18/2024]
Abstract
The dynamics of DNA in the cell nucleus plays a role in cellular processes and fates but the interplay of DNA mobility with the hierarchical levels of DNA organization is still underexplored. Here, we made use of DNA replication to directly label genomic DNA in an unbiased genome-wide manner. This was followed by live-cell time-lapse microscopy of the labeled DNA combining imaging at different resolutions levels simultaneously and allowing one to trace DNA motion across organization levels within the same cells. Quantification of the labeled DNA segments at different microscopic resolution levels revealed sizes comparable to the ones reported for DNA loops using 3D super-resolution microscopy, topologically associated domains (TAD) using 3D widefield microscopy, and also entire chromosomes. By employing advanced chromatin tracking and image registration, we discovered that DNA exhibited higher mobility at the individual loop level compared to the TAD level and even less at the chromosome level. Additionally, our findings indicate that chromatin movement, regardless of the resolution, slowed down during the S phase of the cell cycle compared to the G1/G2 phases. Furthermore, we found that a fraction of DNA loops and TADs exhibited directed movement with the majority depicting constrained movement. Our data also indicated spatial mobility differences with DNA loops and TADs at the nuclear periphery and the nuclear interior exhibiting lower velocity and radius of gyration than the intermediate locations. On the basis of these insights, we propose that there is a link between DNA mobility and its organizational structure including spatial distribution, which impacts cellular processes.
Collapse
Affiliation(s)
- Maruthi K Pabba
- Department of Biology, Technical University of Darmstadt, Darmstadt, Germany
| | - Janis Meyer
- Biomedical Computer Vision Group, BioQuant, IPMB, Heidelberg University, Heidelberg, Germany
| | - Kerem Celikay
- Biomedical Computer Vision Group, BioQuant, IPMB, Heidelberg University, Heidelberg, Germany
| | | | - Karl Rohr
- Biomedical Computer Vision Group, BioQuant, IPMB, Heidelberg University, Heidelberg, Germany.
| | - M Cristina Cardoso
- Department of Biology, Technical University of Darmstadt, Darmstadt, Germany.
| |
Collapse
|
2
|
Zacco E, Broglia L, Kurihara M, Monti M, Gustincich S, Pastore A, Plath K, Nagakawa S, Cerase A, Sanchez de Groot N, Tartaglia GG. RNA: The Unsuspected Conductor in the Orchestra of Macromolecular Crowding. Chem Rev 2024; 124:4734-4777. [PMID: 38579177 PMCID: PMC11046439 DOI: 10.1021/acs.chemrev.3c00575] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2023] [Revised: 01/12/2024] [Accepted: 01/18/2024] [Indexed: 04/07/2024]
Abstract
This comprehensive Review delves into the chemical principles governing RNA-mediated crowding events, commonly referred to as granules or biological condensates. We explore the pivotal role played by RNA sequence, structure, and chemical modifications in these processes, uncovering their correlation with crowding phenomena under physiological conditions. Additionally, we investigate instances where crowding deviates from its intended function, leading to pathological consequences. By deepening our understanding of the delicate balance that governs molecular crowding driven by RNA and its implications for cellular homeostasis, we aim to shed light on this intriguing area of research. Our exploration extends to the methodologies employed to decipher the composition and structural intricacies of RNA granules, offering a comprehensive overview of the techniques used to characterize them, including relevant computational approaches. Through two detailed examples highlighting the significance of noncoding RNAs, NEAT1 and XIST, in the formation of phase-separated assemblies and their influence on the cellular landscape, we emphasize their crucial role in cellular organization and function. By elucidating the chemical underpinnings of RNA-mediated molecular crowding, investigating the role of modifications, structures, and composition of RNA granules, and exploring both physiological and aberrant phase separation phenomena, this Review provides a multifaceted understanding of the intriguing world of RNA-mediated biological condensates.
Collapse
Affiliation(s)
- Elsa Zacco
- RNA
Systems Biology Lab, Center for Human Technologies, Istituto Italiano di Tecnologia, Via Enrico Melen, 83, 16152 Genova, Italy
| | - Laura Broglia
- RNA
Systems Biology Lab, Center for Human Technologies, Istituto Italiano di Tecnologia, Via Enrico Melen, 83, 16152 Genova, Italy
| | - Misuzu Kurihara
- RNA
Biology Laboratory, Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo 060-0812, Japan
| | - Michele Monti
- RNA
Systems Biology Lab, Center for Human Technologies, Istituto Italiano di Tecnologia, Via Enrico Melen, 83, 16152 Genova, Italy
| | - Stefano Gustincich
- Central
RNA Lab, Center for Human Technologies, Istituto Italiano di Tecnologia, Via Enrico Melen, 83, 16152 Genova, Italy
| | - Annalisa Pastore
- UK
Dementia Research Institute at the Maurice Wohl Institute of King’s
College London, London SE5 9RT, U.K.
| | - Kathrin Plath
- Department
of Biological Chemistry, David Geffen School
of Medicine at the University of California Los Angeles, Los Angeles, California 90095, United States
| | - Shinichi Nagakawa
- RNA
Biology Laboratory, Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo 060-0812, Japan
| | - Andrea Cerase
- Blizard
Institute,
Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London E1 4NS, U.K.
- Unit
of Cell and developmental Biology, Department of Biology, Università di Pisa, 56123 Pisa, Italy
| | - Natalia Sanchez de Groot
- Unitat
de Bioquímica, Departament de Bioquímica i Biologia
Molecular, Universitat Autònoma de
Barcelona, 08193 Barcelona, Spain
| | - Gian Gaetano Tartaglia
- RNA
Systems Biology Lab, Center for Human Technologies, Istituto Italiano di Tecnologia, Via Enrico Melen, 83, 16152 Genova, Italy
- Catalan
Institution for Research and Advanced Studies, ICREA, Passeig Lluís Companys 23, 08010 Barcelona, Spain
| |
Collapse
|
3
|
Cremer C, Schock F, Failla AV, Birk U. Modulated illumination microscopy: Application perspectives in nuclear nanostructure analysis. J Microsc 2024. [PMID: 38618985 DOI: 10.1111/jmi.13297] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2023] [Revised: 02/26/2024] [Accepted: 03/19/2024] [Indexed: 04/16/2024]
Abstract
The structure of the cell nucleus of higher organisms has become a major topic of advanced light microscopy. So far, a variety of methods have been applied, including confocal laser scanning fluorescence microscopy, 4Pi, STED and localisation microscopy approaches, as well as different types of patterned illumination microscopy, modulated either laterally (in the object plane) or axially (along the optical axis). Based on our experience, we discuss here some application perspectives of Modulated Illumination Microscopy (MIM) and its combination with single-molecule localisation microscopy (SMLM). For example, spatially modulated illumination microscopy/SMI (illumination modulation along the optical axis) has been used to determine the axial extension (size) of small, optically isolated fluorescent objects between ≤ 200 nm and ≥ 40 nm diameter with a precision down to the few nm range; it also allows the axial positioning of such structures down to the 1 nm scale; combined with laterally structured illumination/SIM, a 3D localisation precision of ≤1 nm is expected using fluorescence yields typical for SMLM applications. Together with the nanosizing capability of SMI, this can be used to analyse macromolecular nuclear complexes with a resolution approaching that of cryoelectron microscopy.
Collapse
Affiliation(s)
- Christoph Cremer
- Kirchhoff Institute for Physics (KIP), Heidelberg, Germany
- Interdisciplinary Centre for Scientific Computing (IWR), University of Heidelberg, Heidelberg, Germany
- Max Planck Institute for Polymer Research, Mainz, Germany
| | - Florian Schock
- Kirchhoff Institute for Physics (KIP), Heidelberg, Germany
| | - Antonio Virgilio Failla
- UKE Microscopy Imaging Facility, University Medical Centre Hamburg Eppendorf, Hamburg, Germany
| | - Udo Birk
- Institute for Photonics and Robotics (IPR), Department of Applied Future Technologies, University of Applied Sciences of the Grisons (FH Graubünden), Chur, Switzerland
| |
Collapse
|
4
|
Pradhan SK, Lozoya T, Prorok P, Yuan Y, Lehmkuhl A, Zhang P, Cardoso MC. Developmental Changes in Genome Replication Progression in Pluripotent versus Differentiated Human Cells. Genes (Basel) 2024; 15:305. [PMID: 38540366 PMCID: PMC10969796 DOI: 10.3390/genes15030305] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2024] [Revised: 02/22/2024] [Accepted: 02/23/2024] [Indexed: 06/14/2024] Open
Abstract
DNA replication is a fundamental process ensuring the maintenance of the genome each time cells divide. This is particularly relevant early in development when cells divide profusely, later giving rise to entire organs. Here, we analyze and compare the genome replication progression in human embryonic stem cells, induced pluripotent stem cells, and differentiated cells. Using single-cell microscopic approaches, we map the spatio-temporal genome replication as a function of chromatin marks/compaction level. Furthermore, we mapped the replication timing of subchromosomal tandem repeat regions and interspersed repeat sequence elements. Albeit the majority of these genomic repeats did not change their replication timing from pluripotent to differentiated cells, we found developmental changes in the replication timing of rDNA repeats. Comparing single-cell super-resolution microscopic data with data from genome-wide sequencing approaches showed comparable numbers of replicons and large overlap in origins numbers and genomic location among developmental states with a generally higher origin variability in pluripotent cells. Using ratiometric analysis of incorporated nucleotides normalized per replisome in single cells, we uncovered differences in fork speed throughout the S phase in pluripotent cells but not in somatic cells. Altogether, our data define similarities and differences on the replication program and characteristics in human cells at different developmental states.
Collapse
Affiliation(s)
- Sunil Kumar Pradhan
- Cell Biology and Epigenetics, Department of Biology, Technical University of Darmstadt, 64287 Darmstadt, Germany; (S.K.P.); (P.P.)
| | - Teresa Lozoya
- Cell Biology and Epigenetics, Department of Biology, Technical University of Darmstadt, 64287 Darmstadt, Germany; (S.K.P.); (P.P.)
| | - Paulina Prorok
- Cell Biology and Epigenetics, Department of Biology, Technical University of Darmstadt, 64287 Darmstadt, Germany; (S.K.P.); (P.P.)
| | - Yue Yuan
- Center for Tissue Engineering and Stem Cell Research, Guizhou Medical University, Guiyang 550004, China;
| | - Anne Lehmkuhl
- Cell Biology and Epigenetics, Department of Biology, Technical University of Darmstadt, 64287 Darmstadt, Germany; (S.K.P.); (P.P.)
| | - Peng Zhang
- Center for Tissue Engineering and Stem Cell Research, Guizhou Medical University, Guiyang 550004, China;
| | - M. Cristina Cardoso
- Cell Biology and Epigenetics, Department of Biology, Technical University of Darmstadt, 64287 Darmstadt, Germany; (S.K.P.); (P.P.)
| |
Collapse
|
5
|
Dror I, Chitiashvili T, Tan SYX, Cano CT, Sahakyan A, Markaki Y, Chronis C, Collier AJ, Deng W, Liang G, Sun Y, Afasizheva A, Miller J, Xiao W, Black DL, Ding F, Plath K. XIST directly regulates X-linked and autosomal genes in naive human pluripotent cells. Cell 2024; 187:110-129.e31. [PMID: 38181737 PMCID: PMC10783549 DOI: 10.1016/j.cell.2023.11.033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Revised: 04/01/2023] [Accepted: 11/28/2023] [Indexed: 01/07/2024]
Abstract
X chromosome inactivation (XCI) serves as a paradigm for RNA-mediated regulation of gene expression, wherein the long non-coding RNA XIST spreads across the X chromosome in cis to mediate gene silencing chromosome-wide. In female naive human pluripotent stem cells (hPSCs), XIST is in a dispersed configuration, and XCI does not occur, raising questions about XIST's function. We found that XIST spreads across the X chromosome and induces dampening of X-linked gene expression in naive hPSCs. Surprisingly, XIST also targets specific autosomal regions, where it induces repressive chromatin changes and gene expression dampening. Thereby, XIST equalizes X-linked gene dosage between male and female cells while inducing differences in autosomes. The dispersed Xist configuration and autosomal localization also occur transiently during XCI initiation in mouse PSCs. Together, our study identifies XIST as the regulator of X chromosome dampening, uncovers an evolutionarily conserved trans-acting role of XIST/Xist, and reveals a correlation between XIST/Xist dispersal and autosomal targeting.
Collapse
Affiliation(s)
- Iris Dror
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Tsotne Chitiashvili
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Shawn Y X Tan
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Clara T Cano
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Anna Sahakyan
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Yolanda Markaki
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA; Institute for Structural and Chemical Biology & Department of Molecular and Cell Biology, University of Leicester, Leicester LE1 7RH, UK
| | - Constantinos Chronis
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA; Department of Biochemistry and Molecular Genetics, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Amanda J Collier
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Weixian Deng
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Guohao Liang
- Department of Biomedical Engineering, University of California Irvine, Irvine, CA 92697, USA
| | - Yu Sun
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Anna Afasizheva
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Jarrett Miller
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Wen Xiao
- Department of Microbiology, Immunology and Molecular Genetics, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Douglas L Black
- Department of Microbiology, Immunology and Molecular Genetics, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Fangyuan Ding
- Department of Biomedical Engineering, University of California Irvine, Irvine, CA 92697, USA; Department of Developmental and Cell Biology, Department of Pharmaceutical Sciences, University of California Irvine, Irvine, CA 92697, USA
| | - Kathrin Plath
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA.
| |
Collapse
|
6
|
Demmerle J, Hao S, Cai D. Transcriptional condensates and phase separation: condensing information across scales and mechanisms. Nucleus 2023; 14:2213551. [PMID: 37218279 PMCID: PMC10208215 DOI: 10.1080/19491034.2023.2213551] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2023] [Revised: 04/26/2023] [Accepted: 05/10/2023] [Indexed: 05/24/2023] Open
Abstract
Transcription is the fundamental process of gene expression, which in eukaryotes occurs within the complex physicochemical environment of the nucleus. Decades of research have provided extreme detail in the molecular and functional mechanisms of transcription, but the spatial and genomic organization of transcription remains mysterious. Recent discoveries show that transcriptional components can undergo phase separation and create distinct compartments inside the nucleus, providing new models through which to view the transcription process in eukaryotes. In this review, we focus on transcriptional condensates and their phase separation-like behaviors. We suggest differentiation between physical descriptions of phase separation and the complex and dynamic biomolecular assemblies required for productive gene expression, and we discuss how transcriptional condensates are central to organizing the three-dimensional genome across spatial and temporal scales. Finally, we map approaches for therapeutic manipulation of transcriptional condensates and ask what technical advances are needed to understand transcriptional condensates more completely.
Collapse
Affiliation(s)
- Justin Demmerle
- Department of Biochemistry and Molecular Biology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
| | - Siyuan Hao
- Department of Biochemistry and Molecular Biology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
| | - Danfeng Cai
- Department of Biochemistry and Molecular Biology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins School of Medicine, Baltimore, MD, USA
- Department of Oncology, Johns Hopkins School of Medicine, Baltimore, MD, USA
| |
Collapse
|
7
|
Peeters SB, Posynick BJ, Brown CJ. Out of the Silence: Insights into How Genes Escape X-Chromosome Inactivation. EPIGENOMES 2023; 7:29. [PMID: 38131901 PMCID: PMC10742877 DOI: 10.3390/epigenomes7040029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2023] [Revised: 11/08/2023] [Accepted: 11/14/2023] [Indexed: 12/23/2023] Open
Abstract
The silencing of all but one X chromosome in mammalian cells is a remarkable epigenetic process leading to near dosage equivalence in X-linked gene products between the sexes. However, equally remarkable is the ability of a subset of genes to continue to be expressed from the otherwise inactive X chromosome-in some cases constitutively, while other genes are variable between individuals, tissues or cells. In this review we discuss the advantages and disadvantages of the approaches that have been used to identify escapees. The identity of escapees provides important clues to mechanisms underlying escape from XCI, an arena of study now moving from correlation to functional studies. As most escapees show greater expression in females, the not-so-inactive X chromosome is a substantial contributor to sex differences in humans, and we highlight some examples of such impact.
Collapse
Affiliation(s)
| | | | - Carolyn J. Brown
- Molecular Epigenetics Group, Department of Medical Genetics, Life Sciences Institute, University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC V6T 1Z3, Canada
| |
Collapse
|
8
|
Collombet S, Rall I, Dugast-Darzacq C, Heckert A, Halavatyi A, Le Saux A, Dailey G, Darzacq X, Heard E. RNA polymerase II depletion from the inactive X chromosome territory is not mediated by physical compartmentalization. Nat Struct Mol Biol 2023; 30:1216-1223. [PMID: 37291424 PMCID: PMC10442225 DOI: 10.1038/s41594-023-01008-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Accepted: 04/28/2023] [Indexed: 06/10/2023]
Abstract
Subnuclear compartmentalization has been proposed to play an important role in gene regulation by segregating active and inactive parts of the genome in distinct physical and biochemical environments. During X chromosome inactivation (XCI), the noncoding Xist RNA coats the X chromosome, triggers gene silencing and forms a dense body of heterochromatin from which the transcription machinery appears to be excluded. Phase separation has been proposed to be involved in XCI, and might explain the exclusion of the transcription machinery by preventing its diffusion into the Xist-coated territory. Here, using quantitative fluorescence microscopy and single-particle tracking, we show that RNA polymerase II (RNAPII) freely accesses the Xist territory during the initiation of XCI. Instead, the apparent depletion of RNAPII is due to the loss of its chromatin stably bound fraction. These findings indicate that initial exclusion of RNAPII from the inactive X reflects the absence of actively transcribing RNAPII, rather than a consequence of putative physical compartmentalization of the inactive X heterochromatin domain.
Collapse
Affiliation(s)
| | - Isabell Rall
- European Molecular Biology Laboratory, Heidelberg, Germany
| | - Claire Dugast-Darzacq
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, USA
- Li Ka Shing Center for Biomedical and Health Sciences, University of California, Berkeley, Berkeley, CA, USA
| | - Alec Heckert
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, USA
- Li Ka Shing Center for Biomedical and Health Sciences, University of California, Berkeley, Berkeley, CA, USA
| | | | - Agnes Le Saux
- Curie Institute, PSL Research University, CNRS UMR3215, INSERM U934, UPMC Paris-Sorbonne, Paris, France
| | - Gina Dailey
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, USA
- Li Ka Shing Center for Biomedical and Health Sciences, University of California, Berkeley, Berkeley, CA, USA
| | - Xavier Darzacq
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, USA.
- Li Ka Shing Center for Biomedical and Health Sciences, University of California, Berkeley, Berkeley, CA, USA.
| | - Edith Heard
- European Molecular Biology Laboratory, Heidelberg, Germany.
- Curie Institute, PSL Research University, CNRS UMR3215, INSERM U934, UPMC Paris-Sorbonne, Paris, France.
- College de France, Paris, France.
| |
Collapse
|
9
|
Gelléri M, Chen SY, Hübner B, Neumann J, Kröger O, Sadlo F, Imhoff J, Hendzel MJ, Cremer M, Cremer T, Strickfaden H, Cremer C. True-to-scale DNA-density maps correlate with major accessibility differences between active and inactive chromatin. Cell Rep 2023; 42:112567. [PMID: 37243597 DOI: 10.1016/j.celrep.2023.112567] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Revised: 03/02/2023] [Accepted: 05/10/2023] [Indexed: 05/29/2023] Open
Abstract
Chromatin compaction differences may have a strong impact on accessibility of individual macromolecules and macromolecular assemblies to their DNA target sites. Estimates based on fluorescence microscopy with conventional resolution, however, suggest only modest compaction differences (∼2-10×) between the active nuclear compartment (ANC) and inactive nuclear compartment (INC). Here, we present maps of nuclear landscapes with true-to-scale DNA densities, ranging from <5 to >300 Mbp/μm3. Maps are generated from individual human and mouse cell nuclei with single-molecule localization microscopy at ∼20 nm lateral and ∼100 nm axial optical resolution and are supplemented by electron spectroscopic imaging. Microinjection of fluorescent nanobeads with sizes corresponding to macromolecular assemblies for transcription into nuclei of living cells demonstrates their localization and movements within the ANC and exclusion from the INC.
Collapse
Affiliation(s)
- Márton Gelléri
- Institute of Molecular Biology (IMB), 55128 Mainz, Germany.
| | - Shih-Ya Chen
- Institute of Molecular Biology (IMB), 55128 Mainz, Germany
| | - Barbara Hübner
- Biocenter, Department Biology II, Ludwig Maximilian University (LMU), 82152 Martinsried, Germany
| | - Jan Neumann
- Institute of Molecular Biology (IMB), 55128 Mainz, Germany; Max Planck Institute for Chemistry, 55128 Mainz, Germany
| | - Ole Kröger
- Interdisciplinary Center for Scientific Computing (IWR), University Heidelberg, 69120 Heidelberg, Germany
| | - Filip Sadlo
- Interdisciplinary Center for Scientific Computing (IWR), University Heidelberg, 69120 Heidelberg, Germany
| | - Jorg Imhoff
- Neuroconsult GmbH, 69120 Heidelberg, Germany
| | - Michael J Hendzel
- Departments of Cell Biology and Oncology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB T6G 1Z2, Canada
| | - Marion Cremer
- Biocenter, Department Biology II, Ludwig Maximilian University (LMU), 82152 Martinsried, Germany
| | - Thomas Cremer
- Biocenter, Department Biology II, Ludwig Maximilian University (LMU), 82152 Martinsried, Germany
| | - Hilmar Strickfaden
- Departments of Cell Biology and Oncology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB T6G 1Z2, Canada.
| | - Christoph Cremer
- Institute of Molecular Biology (IMB), 55128 Mainz, Germany; Max Planck Institute for Chemistry, 55128 Mainz, Germany; Interdisciplinary Center for Scientific Computing (IWR), University Heidelberg, 69120 Heidelberg, Germany; Kirchhoff Institute for Physics, University Heidelberg, 69120 Heidelberg, Germany.
| |
Collapse
|
10
|
Nepita I, Piazza S, Ruglioni M, Cristiani S, Bosurgi E, Salvadori T, Vicidomini G, Diaspro A, Castello M, Cerase A, Bianchini P, Storti B, Bizzarri R. On the Advent of Super-Resolution Microscopy in the Realm of Polycomb Proteins. BIOLOGY 2023; 12:374. [PMID: 36979066 PMCID: PMC10044799 DOI: 10.3390/biology12030374] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2022] [Revised: 02/23/2023] [Accepted: 02/24/2023] [Indexed: 03/02/2023]
Abstract
The genomes of metazoans are organized at multiple spatial scales, ranging from the double helix of DNA to whole chromosomes. The intermediate genomic scale of kilobases to megabases, which corresponds to the 50-300 nm spatial scale, is particularly interesting, as the 3D arrangement of chromatin is implicated in multiple regulatory mechanisms. In this context, polycomb group (PcG) proteins stand as major epigenetic modulators of chromatin function, acting prevalently as repressors of gene transcription by combining chemical modifications of target histones with physical crosslinking of distal genomic regions and phase separation. The recent development of super-resolution microscopy (SRM) has strongly contributed to improving our comprehension of several aspects of nano-/mesoscale (10-200 nm) chromatin domains. Here, we review the current state-of-the-art SRM applied to PcG proteins, showing that the application of SRM to PcG activity and organization is still quite limited and mainly focused on the 3D assembly of PcG-controlled genomic loci. In this context, SRM approaches have mostly been applied to multilabel fluorescence in situ hybridization (FISH). However, SRM data have complemented the maps obtained from chromosome capture experiments and have opened a new window to observe how 3D chromatin topology is modulated by PcGs.
Collapse
Affiliation(s)
- Irene Nepita
- Nanoscopy, Istituto Italiano di Tecnologia, Via E. Melen 83, 16152 Genova, Italy
| | - Simonluca Piazza
- Molecular Microscopy and Spectroscopy, Istituto Italiano di Tecnologia, Via E. Melen 83, 16152 Genova, Italy
- R&D Department, Genoa Instruments s.r.l., Via E. Melen 83, 16152 Genova, Italy
| | - Martina Ruglioni
- Department of Surgical, Medical and Molecular Pathology, and Critical Care Medicine, University of Pisa, Via Roma 65, 56126 Pisa, Italy
| | - Sofia Cristiani
- Department of Surgical, Medical and Molecular Pathology, and Critical Care Medicine, University of Pisa, Via Roma 65, 56126 Pisa, Italy
| | - Emanuele Bosurgi
- Department of Surgical, Medical and Molecular Pathology, and Critical Care Medicine, University of Pisa, Via Roma 65, 56126 Pisa, Italy
| | - Tiziano Salvadori
- Department of Surgical, Medical and Molecular Pathology, and Critical Care Medicine, University of Pisa, Via Roma 65, 56126 Pisa, Italy
| | - Giuseppe Vicidomini
- Molecular Microscopy and Spectroscopy, Istituto Italiano di Tecnologia, Via E. Melen 83, 16152 Genova, Italy
| | - Alberto Diaspro
- Nanoscopy, Istituto Italiano di Tecnologia, Via E. Melen 83, 16152 Genova, Italy
- DIFILAB, Dipartimento di Fisica, Università degli Studi di Genova, Via Dodecaneso 33, 16146 Genova, Italy
| | - Marco Castello
- Nanoscopy, Istituto Italiano di Tecnologia, Via E. Melen 83, 16152 Genova, Italy
- R&D Department, Genoa Instruments s.r.l., Via E. Melen 83, 16152 Genova, Italy
| | - Andrea Cerase
- Unit of Cell and Developmental Biology, Department of Biology, University of Pisa, Strada Statale dell’Abetone Brennero 4, 56123 Pisa, Italy
| | - Paolo Bianchini
- Nanoscopy, Istituto Italiano di Tecnologia, Via E. Melen 83, 16152 Genova, Italy
- DIFILAB, Dipartimento di Fisica, Università degli Studi di Genova, Via Dodecaneso 33, 16146 Genova, Italy
| | - Barbara Storti
- NEST, Scuola Normale Superiore and Istituto Nanoscienze-CNR, Piazza San Silvestro 12, 56127 Pisa, Italy
| | - Ranieri Bizzarri
- Nanoscopy, Istituto Italiano di Tecnologia, Via E. Melen 83, 16152 Genova, Italy
- Department of Surgical, Medical and Molecular Pathology, and Critical Care Medicine, University of Pisa, Via Roma 65, 56126 Pisa, Italy
- NEST, Scuola Normale Superiore and Istituto Nanoscienze-CNR, Piazza San Silvestro 12, 56127 Pisa, Italy
| |
Collapse
|
11
|
Pradhan SK, Cardoso MC. Analysis of Cell Cycle and DNA Compaction Dependent Subnuclear Distribution of Histone Marks. Methods Mol Biol 2023; 2589:225-239. [PMID: 36255628 DOI: 10.1007/978-1-0716-2788-4_15] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
In eukaryotes, the organization of DNA wrapped around histones regulates DNA-dependent processes. Changes in epigenetic modifications modulate the compaction of DNA into chromatin and, thus, regulate DNA metabolism in time and space. Hence, to catalog the spatiotemporal epigenetic information and its relation to the dynamic nuclear landscape is of paramount importance. Here, we present a method, based on FiJi and the statistical image analysis tool nucim(R), to classify in 3D the nuclear DNA compaction in single interphase cells. We, furthermore, mapped the distribution of (epi)genetic marks and nuclear proteins/processes to the compaction classes along with their dynamics over the cell cycle. These techniques allow to catalog and quantify the dynamic changes in the epigenome in space and time and in single cells.
Collapse
Affiliation(s)
- Sunil Kumar Pradhan
- Cell Biology and Epigenetics, Technical University of Darmstadt, Darmstadt, Germany
| | - M Cristina Cardoso
- Cell Biology and Epigenetics, Technical University of Darmstadt, Darmstadt, Germany.
| |
Collapse
|
12
|
Chromatin compaction precedes apoptosis in developing neurons. Commun Biol 2022; 5:797. [PMID: 35941180 PMCID: PMC9359995 DOI: 10.1038/s42003-022-03704-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Accepted: 07/11/2022] [Indexed: 11/19/2022] Open
Abstract
While major changes in cellular morphology during apoptosis have been well described, the subcellular changes in nuclear architecture involved in this process remain poorly understood. Imaging of nucleosomes in cortical neurons in vitro before and during apoptosis revealed that chromatin compaction precedes the activation of caspase-3 and nucleus shrinkage. While this early chromatin compaction remained unaffected by pharmacological blockade of the final execution of apoptosis through caspase-3 inhibition, interfering with the chromatin dynamics by modulation of actomyosin activity prevented apoptosis, but resulted in necrotic-like cell death instead. With super-resolution imaging at different phases of apoptosis in vitro and in vivo, we demonstrate that chromatin compaction occurs progressively and can be classified into five stages. In conclusion, we show that compaction of chromatin in the neuronal nucleus precedes apoptosis execution. These early changes in chromatin structure critically affect apoptotic cell death and are not part of the final execution of the apoptotic process in developing cortical neurons. Single-molecule imaging in developing cortical neurons shows that chromatin compaction precedes apoptosis and is an essential part of it, but can be uncoupled from the following apoptotic process.
Collapse
|
13
|
Razin SV, Zhegalova IV, Kantidze OL. Domain Model of Eukaryotic Genome Organization: From DNA Loops Fixed on the Nuclear Matrix to TADs. BIOCHEMISTRY. BIOKHIMIIA 2022; 87:667-680. [PMID: 36154886 DOI: 10.1134/s0006297922070082] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Revised: 06/18/2022] [Accepted: 06/22/2022] [Indexed: 06/16/2023]
Abstract
The article reviews the development of ideas on the domain organization of eukaryotic genome, with special attention on the studies of DNA loops anchored to the nuclear matrix and their role in the emergence of the modern model of eukaryotic genome spatial organization. Critical analysis of results demonstrating that topologically associated chromatin domains are structural-functional blocks of the genome supports the notion that these blocks are fundamentally different from domains whose existence was proposed by the domain hypothesis of eukaryotic genome organization formulated in the 1980s. Based on the discussed evidence, it is concluded that the model postulating that eukaryotic genome is built from uniformly organized structural-functional blocks has proven to be untenable.
Collapse
Affiliation(s)
- Sergey V Razin
- Institute of Gene Biology, Russian Academy of Sciences, Moscow, 119334, Russia.
- Faculty of Biology, Lomonosov Moscow State University, Moscow, 119991, Russia
| | - Irina V Zhegalova
- Skolkovo Institute of Science and Technology, Moscow, 121205, Russia
- Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Moscow, 119991, Russia
- Kharkevich Institute for Information Transmission Problems, Moscow, 127051, Russia
| | - Omar L Kantidze
- Institute of Gene Biology, Russian Academy of Sciences, Moscow, 119334, Russia
| |
Collapse
|
14
|
Dossin F, Heard E. The Molecular and Nuclear Dynamics of X-Chromosome Inactivation. Cold Spring Harb Perspect Biol 2022; 14:a040196. [PMID: 34312245 PMCID: PMC9121902 DOI: 10.1101/cshperspect.a040196] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
In female eutherian mammals, dosage compensation of X-linked gene expression is achieved during development through transcriptional silencing of one of the two X chromosomes. Following X chromosome inactivation (XCI), the inactive X chromosome remains faithfully silenced throughout somatic cell divisions. XCI is dependent on Xist, a long noncoding RNA that coats and silences the X chromosome from which it is transcribed. Xist coating triggers a cascade of chromosome-wide changes occurring at the levels of transcription, chromatin composition, chromosome structure, and spatial organization within the nucleus. XCI has emerged as a paradigm for the study of such crucial nuclear processes and the dissection of their functional interplay. In the past decade, the advent of tools to characterize and perturb these processes have provided an unprecedented understanding into their roles during XCI. The mechanisms orchestrating the initiation of XCI as well as its maintenance are thus being unraveled, although many questions still remain. Here, we introduce key aspects of the XCI process and review the recent discoveries about its molecular basis.
Collapse
Affiliation(s)
- François Dossin
- European Molecular Biology Laboratory, Director's Unit, 69117 Heidelberg, Germany
| | - Edith Heard
- European Molecular Biology Laboratory, Director's Unit, 69117 Heidelberg, Germany
| |
Collapse
|
15
|
Cerase A, Calabrese JM, Tartaglia GG. Phase separation drives X-chromosome inactivation. Nat Struct Mol Biol 2022; 29:183-185. [PMID: 35301494 DOI: 10.1038/s41594-021-00697-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- Andrea Cerase
- Blizard Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, UK. .,Department of Biology, Università di Pisa, Pisa, Italy.
| | - J Mauro Calabrese
- Department of Pharmacology and Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
| | - Gian Gaetano Tartaglia
- Department of Biology 'Charles Darwin', Sapienza University of Rome, Rome, Italy. .,Department of Neuroscience and Brain Technologies, Istituto Italiano di Tecnologia, Genoa, Italy.
| |
Collapse
|
16
|
Connolly C, Takahashi S, Miura H, Hiratani I, Gilbert N, Donaldson AD, Hiraga SI. SAF-A promotes origin licensing and replication fork progression to ensure robust DNA replication. J Cell Sci 2022; 135:jcs258991. [PMID: 34888666 DOI: 10.1242/jcs.258991] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Accepted: 12/02/2021] [Indexed: 11/20/2022] Open
Abstract
The organisation of chromatin is closely intertwined with biological activities of chromosome domains, including transcription and DNA replication status. Scaffold-attachment factor A (SAF-A), also known as heterogeneous nuclear ribonucleoprotein U (HNRNPU), contributes to the formation of open chromatin structure. Here, we demonstrate that SAF-A promotes the normal progression of DNA replication and enables resumption of replication after inhibition. We report that cells depleted of SAF-A show reduced origin licensing in G1 phase and, consequently, reduced origin activation frequency in S phase. Replication forks also progress less consistently in cells depleted of SAF-A, contributing to reduced DNA synthesis rate. Single-cell replication timing analysis revealed two distinct effects of SAF-A depletion: first, the boundaries between early- and late-replicating domains become more blurred; and second, SAF-A depletion causes replication timing changes that tend to bring regions of discordant domain compartmentalisation and replication timing into concordance. Associated with these defects, SAF-A-depleted cells show elevated formation of phosphorylated histone H2AX (γ-H2AX) and tend to enter quiescence. Overall, we find that SAF-A protein promotes robust DNA replication to ensure continuing cell proliferation.
Collapse
Affiliation(s)
- Caitlin Connolly
- Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, UK
| | - Saori Takahashi
- RIKEN Center for Biosystems Dynamics Research, Kobe, Hyogo 650-0047, Japan
| | - Hisashi Miura
- RIKEN Center for Biosystems Dynamics Research, Kobe, Hyogo 650-0047, Japan
| | - Ichiro Hiratani
- RIKEN Center for Biosystems Dynamics Research, Kobe, Hyogo 650-0047, Japan
| | - Nick Gilbert
- MRC Human Genetics Unit, The University of Edinburgh, Crewe Rd, Edinburgh EH4 2XU, UK
| | - Anne D Donaldson
- Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, UK
| | - Shin-Ichiro Hiraga
- Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, UK
| |
Collapse
|
17
|
Gene regulation in time and space during X-chromosome inactivation. Nat Rev Mol Cell Biol 2022; 23:231-249. [PMID: 35013589 DOI: 10.1038/s41580-021-00438-7] [Citation(s) in RCA: 80] [Impact Index Per Article: 40.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/18/2021] [Indexed: 12/21/2022]
Abstract
X-chromosome inactivation (XCI) is the epigenetic mechanism that ensures X-linked dosage compensation between cells of females (XX karyotype) and males (XY). XCI is essential for female embryos to survive through development and requires the accurate spatiotemporal regulation of many different factors to achieve remarkable chromosome-wide gene silencing. As a result of XCI, the active and inactive X chromosomes are functionally and structurally different, with the inactive X chromosome undergoing a major conformational reorganization within the nucleus. In this Review, we discuss the multiple layers of genetic and epigenetic regulation that underlie initiation of XCI during development and then maintain it throughout life, in light of the most recent findings in this rapidly advancing field. We discuss exciting new insights into the regulation of X inactive-specific transcript (XIST), the trigger and master regulator of XCI, and into the mechanisms and dynamics that underlie the silencing of nearly all X-linked genes. Finally, given the increasing interest in understanding the impact of chromosome organization on gene regulation, we provide an overview of the factors that are thought to reshape the 3D structure of the inactive X chromosome and of the relevance of such structural changes for XCI establishment and maintenance.
Collapse
|
18
|
Xist nucleates local protein gradients to propagate silencing across the X chromosome. Cell 2021; 184:6174-6192.e32. [PMID: 34813726 PMCID: PMC8671326 DOI: 10.1016/j.cell.2021.10.022] [Citation(s) in RCA: 47] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Revised: 07/29/2021] [Accepted: 10/11/2021] [Indexed: 02/08/2023]
Abstract
The lncRNA Xist forms ∼50 diffraction-limited foci to transcriptionally silence one X chromosome. How this small number of RNA foci and interacting proteins regulate a much larger number of X-linked genes is unknown. We show that Xist foci are locally confined, contain ∼2 RNA molecules, and nucleate supramolecular complexes (SMACs) that include many copies of the critical silencing protein SPEN. Aggregation and exchange of SMAC proteins generate local protein gradients that regulate broad, proximal chromatin regions. Partitioning of numerous SPEN molecules into SMACs is mediated by their intrinsically disordered regions and essential for transcriptional repression. Polycomb deposition via SMACs induces chromatin compaction and the increase in SMACs density around genes, which propagates silencing across the X chromosome. Our findings introduce a mechanism for functional nuclear compartmentalization whereby crowding of transcriptional and architectural regulators enables the silencing of many target genes by few RNA molecules.
Collapse
|
19
|
Four-dimensional chromosome reconstruction elucidates the spatiotemporal reorganization of the mammalian X chromosome. Proc Natl Acad Sci U S A 2021; 118:2107092118. [PMID: 34645712 DOI: 10.1073/pnas.2107092118] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/27/2021] [Indexed: 12/14/2022] Open
Abstract
Chromosomes are segmented into domains and compartments, but how these structures are spatially related in three dimensions (3D) is unclear. Here, we developed tools that directly extract 3D information from Hi-C experiments and integrate the data across time. With our "4DHiC" method, we use X chromosome inactivation (XCI) as a model to examine the time evolution of 3D chromosome architecture during large-scale changes in gene expression. Our modeling resulted in several insights. Both A/B and S1/S2 compartments divide the X chromosome into hemisphere-like structures suggestive of a spatial phase-separation. During the XCI, the X chromosome transits through A/B, S1/S2, and megadomain structures by undergoing only partial mixing to assume new structures. Interestingly, when an active X chromosome (Xa) is reorganized into an inactive X chromosome (Xi), original underlying compartment structures are not fully eliminated within the Xi superstructure. Our study affirms slow mixing dynamics in the inner chromosome core and faster dynamics near the surface where escapees reside. Once established, the Xa and Xi resemble glassy polymers where mixing no longer occurs. Finally, Xist RNA molecules initially reside within the A compartment but transition to the interface between the A and B hemispheres and then spread between hemispheres via both surface and core to establish the Xi.
Collapse
|
20
|
Abstract
Nuclei are central hubs for information processing in eukaryotic cells. The need to fit large genomes into small nuclei imposes severe restrictions on genome organization and the mechanisms that drive genome-wide regulatory processes. How a disordered polymer such as chromatin, which has vast heterogeneity in its DNA and histone modification profiles, folds into discernibly consistent patterns is a fundamental question in biology. Outstanding questions include how genomes are spatially and temporally organized to regulate cellular processes with high precision and whether genome organization is causally linked to transcription regulation. The advent of next-generation sequencing, super-resolution imaging, multiplexed fluorescent in situ hybridization, and single-molecule imaging in individual living cells has caused a resurgence in efforts to understand the spatiotemporal organization of the genome. In this review, we discuss structural and mechanistic properties of genome organization at different length scales and examine changes in higher-order chromatin organization during important developmental transitions.
Collapse
Affiliation(s)
- Rajarshi P Ghosh
- Department of Molecular and Cell Biology and Howard Hughes Medical Institute, University of California, Berkeley, California 94720, USA; ,
| | - Barbara J Meyer
- Department of Molecular and Cell Biology and Howard Hughes Medical Institute, University of California, Berkeley, California 94720, USA; ,
| |
Collapse
|
21
|
Marenda M, Lazarova E, van de Linde S, Gilbert N, Michieletto D. Parameter-free molecular super-structures quantification in single-molecule localization microscopy. J Cell Biol 2021; 220:211893. [PMID: 33734291 PMCID: PMC7980255 DOI: 10.1083/jcb.202010003] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Revised: 01/06/2021] [Accepted: 02/23/2021] [Indexed: 12/18/2022] Open
Abstract
Understanding biological function requires the identification and characterization of complex patterns of molecules. Single-molecule localization microscopy (SMLM) can quantitatively measure molecular components and interactions at resolutions far beyond the diffraction limit, but this information is only useful if these patterns can be quantified and interpreted. We provide a new approach for the analysis of SMLM data that develops the concept of structures and super-structures formed by interconnected elements, such as smaller protein clusters. Using a formal framework and a parameter-free algorithm, (super-)structures formed from smaller components are found to be abundant in classes of nuclear proteins, such as heterogeneous nuclear ribonucleoprotein particles (hnRNPs), but are absent from ceramides located in the plasma membrane. We suggest that mesoscopic structures formed by interconnected protein clusters are common within the nucleus and have an important role in the organization and function of the genome. Our algorithm, SuperStructure, can be used to analyze and explore complex SMLM data and extract functionally relevant information.
Collapse
Affiliation(s)
- Mattia Marenda
- Medical Research Council Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, UK.,Scottish Universities Physics Alliance, School of Physics and Astronomy, University of Edinburgh, Edinburgh, UK
| | - Elena Lazarova
- Medical Research Council Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, UK
| | - Sebastian van de Linde
- Scottish Universities Physics Alliance, Department of Physics, University of Strathclyde, Glasgow, UK
| | - Nick Gilbert
- Medical Research Council Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, UK
| | - Davide Michieletto
- Medical Research Council Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, UK.,Scottish Universities Physics Alliance, School of Physics and Astronomy, University of Edinburgh, Edinburgh, UK
| |
Collapse
|
22
|
Phase Separation in RNA Biology. J Genet Genomics 2021; 48:872-880. [PMID: 34371110 DOI: 10.1016/j.jgg.2021.07.012] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2021] [Revised: 07/19/2021] [Accepted: 07/20/2021] [Indexed: 11/23/2022]
Abstract
Formation of biomolecular condensates via liquid-liquid phase separation (LLPS) is an advantageous strategy for cells to organize subcellular compartments for diverse functions. The involvement of LLPS is more widespread and overrepresented in RNA-related biological processes. This is in part because that RNAs are intrinsically multivalent macromolecules and the presence of RNAs affects the formation, dissolution and biophysical properties of biomolecular condensates formed by LLPS. Emerging studies have illustrated how LLPS participates in RNA transcription, splicing, processing, quality control, translation and function. The interconnected regulation between LLPS and RNAs ensures tight control of RNA-related cellular functions.
Collapse
|
23
|
Xie L, Liu Z. Single-cell imaging of genome organization and dynamics. Mol Syst Biol 2021; 17:e9653. [PMID: 34232558 PMCID: PMC8262488 DOI: 10.15252/msb.20209653] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Revised: 04/13/2021] [Accepted: 04/23/2021] [Indexed: 12/28/2022] Open
Abstract
Probing the architecture, mechanism, and dynamics of genome folding is fundamental to our understanding of genome function in homeostasis and disease. Most chromosome conformation capture studies dissect the genome architecture with population- and time-averaged snapshots and thus have limited capabilities to reveal 3D nuclear organization and dynamics at the single-cell level. Here, we discuss emerging imaging techniques ranging from light microscopy to electron microscopy that enable investigation of genome folding and dynamics at high spatial and temporal resolution. Results from these studies complement genomic data, unveiling principles underlying the spatial arrangement of the genome and its potential functional links to diverse biological activities in the nucleus.
Collapse
Affiliation(s)
- Liangqi Xie
- Janelia Research CampusHoward Hughes Medical InstituteAshburnVAUSA
| | - Zhe Liu
- Janelia Research CampusHoward Hughes Medical InstituteAshburnVAUSA
| |
Collapse
|
24
|
Rodermund L, Coker H, Oldenkamp R, Wei G, Bowness J, Rajkumar B, Nesterova T, Susano Pinto DM, Schermelleh L, Brockdorff N. Time-resolved structured illumination microscopy reveals key principles of Xist RNA spreading. Science 2021; 372:372/6547/eabe7500. [PMID: 34112668 DOI: 10.1126/science.abe7500] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Accepted: 05/07/2021] [Indexed: 01/23/2023]
Abstract
X-inactive specific transcript (Xist) RNA directs the process of X chromosome inactivation in mammals by spreading in cis along the chromosome from which it is transcribed and recruiting chromatin modifiers to silence gene transcription. To elucidate mechanisms of Xist RNA cis-confinement, we established a sequential dual-color labeling, super-resolution imaging approach to trace individual Xist RNA molecules over time, which enabled us to define fundamental parameters of spreading. We demonstrate a feedback mechanism linking Xist RNA synthesis and degradation and an unexpected physical coupling between preceding and newly synthesized Xist RNA molecules. Additionally, we find that the protein SPEN, a key factor for Xist-mediated gene silencing, has a distinct function in Xist RNA localization, stability, and coupling behaviors. Our results provide insights toward understanding the distinct dynamic properties of Xist RNA.
Collapse
Affiliation(s)
- Lisa Rodermund
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK
| | - Heather Coker
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK
| | - Roel Oldenkamp
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK
| | - Guifeng Wei
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK
| | - Joseph Bowness
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK
| | - Bramman Rajkumar
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK
| | - Tatyana Nesterova
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK
| | | | | | - Neil Brockdorff
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK.
| |
Collapse
|
25
|
Prakash K, Diederich B, Reichelt S, Heintzmann R, Schermelleh L. Super-resolution structured illumination microscopy: past, present and future. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2021; 379:20200143. [PMID: 33896205 PMCID: PMC8366908 DOI: 10.1098/rsta.2020.0143] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Structured illumination microscopy (SIM) has emerged as an essential technique for three-dimensional (3D) and live-cell super-resolution imaging. However, to date, there has not been a dedicated workshop or journal issue covering the various aspects of SIM, from bespoke hardware and software development and the use of commercial instruments to biological applications. This special issue aims to recap recent developments as well as outline future trends. In addition to SIM, we cover related topics such as complementary super-resolution microscopy techniques, computational imaging, visualization and image processing methods. This article is part of the Theo Murphy meeting issue 'Super-resolution structured illumination microscopy (part 1)'.
Collapse
Affiliation(s)
- Kirti Prakash
- National Physical Laboratory, TW11 0LW Teddington, UK
- Department of Paediatrics, Wellcome-MRC Cambridge Stem Cell Institute, University of Cambridge, Cambridge, UK
| | - Benedict Diederich
- Leibniz Institute of Photonic Technology, Albert-Einstein-Straße 9, 07745 Jena, Germany
- Institute of Physical Chemistry and Abbe Center of Photonics, Friedrich-Schiller-University, Helmholtzweg 4, Jena, Germany
| | - Stefanie Reichelt
- CRUK Cambridge Research Institute, Robinson Way, Cambridge CB2 0RE, UK
| | - Rainer Heintzmann
- Leibniz Institute of Photonic Technology, Albert-Einstein-Straße 9, 07745 Jena, Germany
- Institute of Physical Chemistry and Abbe Center of Photonics, Friedrich-Schiller-University, Helmholtzweg 4, Jena, Germany
- Faculty of Physics and Astronomy, Friedrich-Schiller-University, Jena, Germany
| | - Lothar Schermelleh
- Micron Advanced Bioimaging Unit, Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK
| |
Collapse
|
26
|
Marenda M, Lazarova E, van de Linde S, Gilbert N, Michieletto D. Parameter-free molecular super-structures quantification in single-molecule localization microscopy. J Cell Biol 2021. [PMID: 33734291 DOI: 10.1101/2020.08.19.254540] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/12/2023] Open
Abstract
Understanding biological function requires the identification and characterization of complex patterns of molecules. Single-molecule localization microscopy (SMLM) can quantitatively measure molecular components and interactions at resolutions far beyond the diffraction limit, but this information is only useful if these patterns can be quantified and interpreted. We provide a new approach for the analysis of SMLM data that develops the concept of structures and super-structures formed by interconnected elements, such as smaller protein clusters. Using a formal framework and a parameter-free algorithm, (super-)structures formed from smaller components are found to be abundant in classes of nuclear proteins, such as heterogeneous nuclear ribonucleoprotein particles (hnRNPs), but are absent from ceramides located in the plasma membrane. We suggest that mesoscopic structures formed by interconnected protein clusters are common within the nucleus and have an important role in the organization and function of the genome. Our algorithm, SuperStructure, can be used to analyze and explore complex SMLM data and extract functionally relevant information.
Collapse
Affiliation(s)
- Mattia Marenda
- Medical Research Council Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, UK
- Scottish Universities Physics Alliance, School of Physics and Astronomy, University of Edinburgh, Edinburgh, UK
| | - Elena Lazarova
- Medical Research Council Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, UK
| | - Sebastian van de Linde
- Scottish Universities Physics Alliance, Department of Physics, University of Strathclyde, Glasgow, UK
| | - Nick Gilbert
- Medical Research Council Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, UK
| | - Davide Michieletto
- Medical Research Council Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, UK
- Scottish Universities Physics Alliance, School of Physics and Astronomy, University of Edinburgh, Edinburgh, UK
| |
Collapse
|
27
|
Song Z, Lin J, Li Z, Huang C. The nuclear functions of long noncoding RNAs come into focus. Noncoding RNA Res 2021; 6:70-79. [PMID: 33898883 PMCID: PMC8053782 DOI: 10.1016/j.ncrna.2021.03.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Revised: 03/18/2021] [Accepted: 03/22/2021] [Indexed: 12/16/2022] Open
Abstract
Long noncoding RNAs (lncRNAs), defined as untranslated and tightly-regulated transcripts with a length exceeding 200 nt, are common outputs of the eukaryotic genome. It is becoming increasingly apparent that many lncRNAs likely serve as important regulators in a variety of biological processes. In particular, some of them accumulate in the nucleus and function in diverse nuclear events, including chromatin remodeling, transcriptional regulation, RNA processing, DNA damage repair, etc. Here, we unite recent progresses on the functions of nuclear lncRNAs and provide insights into the future research directions of this field.
Collapse
Affiliation(s)
- Zhenxing Song
- School of Life Sciences, Chongqing University, Chongqing, 401331, China
- Center of Plant Functional Genomics, Institute of Advanced Interdisciplinary Studies, Chongqing University, Chongqing, 401331, China
| | - Jiamei Lin
- School of Life Sciences, Chongqing University, Chongqing, 401331, China
- Center of Plant Functional Genomics, Institute of Advanced Interdisciplinary Studies, Chongqing University, Chongqing, 401331, China
| | - Zhengguo Li
- School of Life Sciences, Chongqing University, Chongqing, 401331, China
- Center of Plant Functional Genomics, Institute of Advanced Interdisciplinary Studies, Chongqing University, Chongqing, 401331, China
| | - Chuan Huang
- School of Life Sciences, Chongqing University, Chongqing, 401331, China
- Center of Plant Functional Genomics, Institute of Advanced Interdisciplinary Studies, Chongqing University, Chongqing, 401331, China
- Corresponding author. School of Life Sciences, Chongqing University, Chongqing, 401331, China.
| |
Collapse
|
28
|
Sas-Nowosielska H, Magalska A. Long Noncoding RNAs-Crucial Players Organizing the Landscape of the Neuronal Nucleus. Int J Mol Sci 2021; 22:ijms22073478. [PMID: 33801737 PMCID: PMC8037058 DOI: 10.3390/ijms22073478] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Revised: 03/22/2021] [Accepted: 03/24/2021] [Indexed: 12/25/2022] Open
Abstract
The ability to regulate chromatin organization is particularly important in neurons, which dynamically respond to external stimuli. Accumulating evidence shows that lncRNAs play important architectural roles in organizing different nuclear domains like inactive chromosome X, splicing speckles, paraspeckles, and Gomafu nuclear bodies. LncRNAs are abundantly expressed in the nervous system where they may play important roles in compartmentalization of the cell nucleus. In this review we will describe the architectural role of lncRNAs in the nuclei of neuronal cells.
Collapse
|
29
|
Poonperm R, Hiratani I. Formation of a multi-layered 3-dimensional structure of the heterochromatin compartment during early mammalian development. Dev Growth Differ 2021; 63:5-17. [PMID: 33491197 DOI: 10.1111/dgd.12709] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Revised: 12/14/2020] [Accepted: 01/05/2021] [Indexed: 01/10/2023]
Abstract
During embryogenesis in mammals, the 3-dimensional (3D) genome organization changes globally in parallel with transcription changes in a cell-type specific manner. This involves the progressive formation of heterochromatin, the best example of which is the inactive X chromosome (Xi) in females, originally discovered as a compact 3D structure at the nuclear periphery known as the Barr body. The heterochromatin formation on the autosomes and the Xi is tightly associated with the differentiation state and the developmental potential of cells, making it an ideal readout of the cellular epigenetic state. At a glance, the heterochromatin appears to be uniform. However, recent studies are beginning to reveal a more complex picture, with multiple hierarchical levels co-existing within the heterochromatin compartment. Such hierarchical levels appear to exist in the heterochromatin compartment on autosomes as well as on the Xi. Here, we review recent progress in our understanding of the 3D genome organization changes during the period of differentiation surrounding pluripotency in vivo and in vitro, with a focus on the heterochromatin compartment. We first look at the whole genome, then focus on the Xi, and discuss their differences and similarities. Finally, we present a unified view of how the heterochromatin compartment is formed and regulated during early development. In particular, we emphasize that there are multiple layers within the heterochromatic compartment on both the autosomes and the Xi, with regulatory mechanisms common and specific to each layer.
Collapse
Affiliation(s)
- Rawin Poonperm
- Laboratory for Developmental Epigenetics, RIKEN Center for Biosystems Dynamics Research (BDR), Kobe, Japan
| | - Ichiro Hiratani
- Laboratory for Developmental Epigenetics, RIKEN Center for Biosystems Dynamics Research (BDR), Kobe, Japan
| |
Collapse
|
30
|
Chu LA, Chang SW, Tang WC, Tseng YT, Chen P, Chen BC. 5D superresolution imaging for a live cell nucleus. Curr Opin Genet Dev 2020; 67:77-83. [PMID: 33383256 DOI: 10.1016/j.gde.2020.11.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Revised: 11/21/2020] [Accepted: 11/22/2020] [Indexed: 11/16/2022]
Abstract
With a spatial resolution breaking the diffraction limit of light, superresolution imaging allows the visualization of detailed structures of organelles such as mitochondria, cytoskeleton, nucleus, and so on. With multi-dimensional imaging (x, y, z, t, λ), namely, multi-color 3D live imaging enables us fully understand the function of the cell. It is necessary to analyze structural changes or molecular interactions across a large volume in 3D with different labelled targets. To achieve this goal, scientists recently have expanded the original 2D superresolution microscopic tools into 3D imaging techniques. In this review, we will discuss recent development in superresolution microscopy for live imaging with minimal phototoxicity. We will focus our discussion on the cell nucleus where the genetic materials are stored and processed. Machine learning algorism will be introduced to improve the axial resolution of superresolution imaging.
Collapse
Affiliation(s)
- Li-An Chu
- Department of Biomedical Engineering and Environmental Science, National Tsing Hua University, Hsinchu, 30013, Taiwan; Brain Research Center, National Tsing Hua University, Hsinchu, 30013, Taiwan.
| | - Shu-Wei Chang
- Research Center for Applied Sciences, Academia Sinica, Taipei, 11529, Taiwan
| | - Wei-Chun Tang
- Research Center for Applied Sciences, Academia Sinica, Taipei, 11529, Taiwan
| | - Yu-Ting Tseng
- Research Center for Applied Sciences, Academia Sinica, Taipei, 11529, Taiwan
| | - Peilin Chen
- Research Center for Applied Sciences, Academia Sinica, Taipei, 11529, Taiwan
| | - Bi-Chang Chen
- Brain Research Center, National Tsing Hua University, Hsinchu, 30013, Taiwan; Research Center for Applied Sciences, Academia Sinica, Taipei, 11529, Taiwan.
| |
Collapse
|
31
|
Cremer M, Brandstetter K, Maiser A, Rao SSP, Schmid VJ, Guirao-Ortiz M, Mitra N, Mamberti S, Klein KN, Gilbert DM, Leonhardt H, Cardoso MC, Aiden EL, Harz H, Cremer T. Cohesin depleted cells rebuild functional nuclear compartments after endomitosis. Nat Commun 2020; 11:6146. [PMID: 33262376 PMCID: PMC7708632 DOI: 10.1038/s41467-020-19876-6] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Accepted: 10/28/2020] [Indexed: 01/05/2023] Open
Abstract
Cohesin plays an essential role in chromatin loop extrusion, but its impact on a compartmentalized nuclear architecture, linked to nuclear functions, is less well understood. Using live-cell and super-resolved 3D microscopy, here we find that cohesin depletion in a human colon cancer derived cell line results in endomitosis and a single multilobulated nucleus with chromosome territories pervaded by interchromatin channels. Chromosome territories contain chromatin domain clusters with a zonal organization of repressed chromatin domains in the interior and transcriptionally competent domains located at the periphery. These clusters form microscopically defined, active and inactive compartments, which likely correspond to A/B compartments, which are detected with ensemble Hi-C. Splicing speckles are observed nearby within the lining channel system. We further observe that the multilobulated nuclei, despite continuous absence of cohesin, pass through S-phase with typical spatio-temporal patterns of replication domains. Evidence for structural changes of these domains compared to controls suggests that cohesin is required for their full integrity.
Collapse
Affiliation(s)
- Marion Cremer
- Anthropology and Human Genomics, Department Biology II, Ludwig-Maximilians-Universität München, München, Germany.
| | - Katharina Brandstetter
- Human Biology & BioImaging, Center for Molecular Biosystems, Department Biology II, Ludwig-Maximilians-Universität München, München, Germany
| | - Andreas Maiser
- Human Biology & BioImaging, Center for Molecular Biosystems, Department Biology II, Ludwig-Maximilians-Universität München, München, Germany
| | - Suhas S P Rao
- Center for Genome Architecture, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
- Department of Structural Biology, Stanford University School of Medicine, California, USA
| | - Volker J Schmid
- Bayesian Imaging and Spatial Statistics Group, Department of Statistics, Ludwig-Maximilians-Universität München, München, Germany
| | - Miguel Guirao-Ortiz
- Human Biology & BioImaging, Center for Molecular Biosystems, Department Biology II, Ludwig-Maximilians-Universität München, München, Germany
| | - Namita Mitra
- Center for Genome Architecture, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Stefania Mamberti
- Cell Biology and Epigenetics, Department of Biology, Technische Universität Darmstadt, Darmstadt, Germany
| | - Kyle N Klein
- Department of Biological Science, Florida State University, Tallahassee, FL, USA
| | - David M Gilbert
- Department of Biological Science, Florida State University, Tallahassee, FL, USA
| | - Heinrich Leonhardt
- Human Biology & BioImaging, Center for Molecular Biosystems, Department Biology II, Ludwig-Maximilians-Universität München, München, Germany
| | - M Cristina Cardoso
- Cell Biology and Epigenetics, Department of Biology, Technische Universität Darmstadt, Darmstadt, Germany
| | - Erez Lieberman Aiden
- Center for Genome Architecture, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
- Center for Theoretical Biological Physics, Rice University, Houston, TX, USA
- Broad Institute of the Massachusetts Institute of Technology and Harvard University, Cambridge, MA, USA
- Departments of Computer Science and Computational and Applied Mathematics, Rice University, Houston, TX, USA
| | - Hartmann Harz
- Human Biology & BioImaging, Center for Molecular Biosystems, Department Biology II, Ludwig-Maximilians-Universität München, München, Germany.
| | - Thomas Cremer
- Anthropology and Human Genomics, Department Biology II, Ludwig-Maximilians-Universität München, München, Germany.
| |
Collapse
|
32
|
Schertzer MD, Murvin MM, Calabrese JM. Using RNA Sequencing and Spike-in RNAs to Measure Intracellular Abundance of lncRNAs and mRNAs. Bio Protoc 2020; 10:e3772. [PMID: 33204768 DOI: 10.21769/bioprotoc.3772] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Long noncoding RNAs (lncRNAs) play essential roles in normal physiology and in disease but their mechanisms of action can be challenging to identify. For mechanistic studies, it is often useful to know a lncRNA's intracellular abundance, i.e., approximately how many molecules of the lncRNA are present in a typical cell of a cell-type of interest. At least two approaches have been used to approximate lncRNA intracellular abundance: single-molecule sensitivity RNA fluorescence in situ hybridization (smFISH) and single-gene, calibrated reverse-transcription followed by quantitative PCR (RT-qPCR). However, like all experimental approaches, these methods have their limitations. smFISH, when analyzed using diffraction-limited microscopy, can underestimate intracellular abundance, especially for lncRNAs that accumulate in focused subcellular regions. Calibrated RT-qPCR may return inaccurate estimates of abundance because individual PCR amplicons spaced across the length of a transcript can vary in their efficiency of reverse transcription. Here, we describe a sequencing-based approach that is straightforward, orthogonal to smFISH and RT-qPCR, and can be used to approximate the intracellular abundance for most expressed long RNAs (lncRNAs and mRNAs) in a cell type of interest. Firstly, the average weight of total RNA per cell for the cell type of interest is estimated by replicate rounds of RNA purification from a known number of cells. Secondly, an rRNA-depletion RNA-Seq protocol is performed after adding spike-in control RNAs to a known quantity of total cellular RNA. Lastly, by comparing read counts per transcript to a standard curve derived from the spiked-in RNAs, the intracellular abundance for each transcript is estimated. The sequencing-based approach provides a powerful complement to existing methods, particularly in situations where it is desirable to quantify the abundance of multiple lncRNAs and/or mRNAs simultaneously.
Collapse
Affiliation(s)
- Megan D Schertzer
- Department of Pharmacology and Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, 120 Mason Farm Road, Chapel Hill, NC, 27599, USA.,Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, 120 Mason Farm Road, Chapel Hill, NC, 27599, USA
| | - McKenzie M Murvin
- Department of Pharmacology and Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, 120 Mason Farm Road, Chapel Hill, NC, 27599, USA.,Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, 120 Mason Farm Road, Chapel Hill, NC, 27599, USA
| | - J Mauro Calabrese
- Department of Pharmacology and Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, 120 Mason Farm Road, Chapel Hill, NC, 27599, USA
| |
Collapse
|
33
|
Cremer T, Cremer M, Hübner B, Silahtaroglu A, Hendzel M, Lanctôt C, Strickfaden H, Cremer C. The Interchromatin Compartment Participates in the Structural and Functional Organization of the Cell Nucleus. Bioessays 2020; 42:e1900132. [PMID: 31994771 DOI: 10.1002/bies.201900132] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Revised: 11/24/2019] [Indexed: 12/11/2022]
Abstract
This article focuses on the role of the interchromatin compartment (IC) in shaping nuclear landscapes. The IC is connected with nuclear pore complexes (NPCs) and harbors splicing speckles and nuclear bodies. It is postulated that the IC provides routes for imported transcription factors to target sites, for export routes of mRNA as ribonucleoproteins toward NPCs, as well as for the intranuclear passage of regulatory RNAs from sites of transcription to remote functional sites (IC hypothesis). IC channels are lined by less-compacted euchromatin, called the perichromatin region (PR). The PR and IC together form the active nuclear compartment (ANC). The ANC is co-aligned with the inactive nuclear compartment (INC), comprising more compacted heterochromatin. It is postulated that the INC is accessible for individual transcription factors, but inaccessible for larger macromolecular aggregates (limited accessibility hypothesis). This functional nuclear organization depends on still unexplored movements of genes and regulatory sequences between the two compartments.
Collapse
Affiliation(s)
- Thomas Cremer
- Anthropology and Human Genomics, Department of Biology II, Ludwig-Maximilians University (LMU), Biocenter, Grosshadernerstr. 2, 82152, Martinsried, Germany
| | - Marion Cremer
- Anthropology and Human Genomics, Department of Biology II, Ludwig-Maximilians University (LMU), Biocenter, Grosshadernerstr. 2, 82152, Martinsried, Germany
| | - Barbara Hübner
- Anthropology and Human Genomics, Department of Biology II, Ludwig-Maximilians University (LMU), Biocenter, Grosshadernerstr. 2, 82152, Martinsried, Germany
| | - Asli Silahtaroglu
- Department of Cellular and Molecular Medicine Faculty of Health and Medical Sciences, University of Copenhagen, Nørre Alle 14, Byg.18.03, 2200, Copenhagen N, Denmark
| | - Michael Hendzel
- Department of Oncology, Cross Cancer Institute, University of Alberta, 11560 University Avenue, Edmonton, Alberta, T6G 1Z2, Canada
| | - Christian Lanctôt
- Integration Santé, 1250 Avenue de la Station local 2-304, Shawinigan, Québec, G9N 8K9, Canada
| | - Hilmar Strickfaden
- Department of Oncology, Cross Cancer Institute, University of Alberta, 11560 University Avenue, Edmonton, Alberta, T6G 1Z2, Canada
| | - Christoph Cremer
- Institute of Molecular Biology (IMB) Ackermannweg 4, 55128 Mainz, Germany, and Institute of Pharmacy & Molecular Biotechnology (IPMB), University Heidelberg, Im Neuenheimer Feld 364, 69120, Heidelberg, Germany
| |
Collapse
|
34
|
Miron E, Oldenkamp R, Brown JM, Pinto DMS, Xu CS, Faria AR, Shaban HA, Rhodes JDP, Innocent C, de Ornellas S, Hess HF, Buckle V, Schermelleh L. Chromatin arranges in chains of mesoscale domains with nanoscale functional topography independent of cohesin. SCIENCE ADVANCES 2020; 6:eaba8811. [PMID: 32967822 PMCID: PMC7531892 DOI: 10.1126/sciadv.aba8811] [Citation(s) in RCA: 82] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Accepted: 08/06/2020] [Indexed: 05/05/2023]
Abstract
Three-dimensional (3D) chromatin organization plays a key role in regulating mammalian genome function; however, many of its physical features at the single-cell level remain underexplored. Here, we use live- and fixed-cell 3D super-resolution and scanning electron microscopy to analyze structural and functional nuclear organization in somatic cells. We identify chains of interlinked ~200- to 300-nm-wide chromatin domains (CDs) composed of aggregated nucleosomes that can overlap with individual topologically associating domains and are distinct from a surrounding RNA-populated interchromatin compartment. High-content mapping uncovers confinement of cohesin and active histone modifications to surfaces and enrichment of repressive modifications toward the core of CDs in both hetero- and euchromatic regions. This nanoscale functional topography is temporarily relaxed in postreplicative chromatin but remarkably persists after ablation of cohesin. Our findings establish CDs as physical and functional modules of mesoscale genome organization.
Collapse
Affiliation(s)
- Ezequiel Miron
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK
| | - Roel Oldenkamp
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK
| | - Jill M Brown
- MRC Weatherall Institute of Molecular Medicine, Haematology Unit, University of Oxford, Oxford OX3 9DS, UK
| | - David M S Pinto
- Micron Oxford Advanced Bioimaging Unit, University of Oxford, Oxford OX1 3QU, UK
| | - C Shan Xu
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Ana R Faria
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK
| | - Haitham A Shaban
- Spectroscopy Department, Physics Division, National Research Centre, 12622 Dokki, Cairo, Egypt
| | - James D P Rhodes
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK
| | | | - Sara de Ornellas
- MRC Weatherall Institute of Molecular Medicine, Haematology Unit, University of Oxford, Oxford OX3 9DS, UK
| | - Harald F Hess
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Veronica Buckle
- MRC Weatherall Institute of Molecular Medicine, Haematology Unit, University of Oxford, Oxford OX3 9DS, UK
| | - Lothar Schermelleh
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK.
- Micron Oxford Advanced Bioimaging Unit, University of Oxford, Oxford OX1 3QU, UK
| |
Collapse
|
35
|
Frank L, Rippe K. Repetitive RNAs as Regulators of Chromatin-Associated Subcompartment Formation by Phase Separation. J Mol Biol 2020; 432:4270-4286. [DOI: 10.1016/j.jmb.2020.04.015] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Revised: 04/14/2020] [Accepted: 04/14/2020] [Indexed: 12/21/2022]
|
36
|
Xist attenuates acute inflammatory response by female cells. Cell Mol Life Sci 2020; 78:299-316. [PMID: 32193609 DOI: 10.1007/s00018-020-03500-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Revised: 01/20/2020] [Accepted: 03/05/2020] [Indexed: 12/22/2022]
Abstract
Biological sex influences inflammatory response, as there is a greater incidence of acute inflammation in men and chronic inflammation in women. Here, we report that acute inflammation is attenuated by X-inactive specific transcript (Xist), a female cell-specific nuclear long noncoding RNA crucial for X-chromosome inactivation. Lipopolysaccharide-mediated acute inflammation increased Xist levels in the cytoplasm of female mouse J774A.1 macrophages and human AML193 monocytes. In both cell types, cytoplasmic Xist colocalizes with the p65 subunit of NF-κB. This interaction was associated with reduced NF-κB nuclear migration, suggesting a novel mechanism to suppress acute inflammation. Further supporting this hypothesis, expression of 5' XIST in male cells significantly reduced IL-6 and NF-κB activity. Adoptive transfer of male splenocytes expressing Xist reduced acute paw swelling in male mice indicating that Xist can have a protective anti-inflammatory effect. These findings show that XIST has functions beyond X chromosome inactivation and suggest that XIST can contribute to sex-specific differences underlying inflammatory response by attenuating acute inflammation in women.
Collapse
|
37
|
Akkipeddi SMK, Velleca AJ, Carone DM. Probing the function of long noncoding RNAs in the nucleus. Chromosome Res 2020; 28:87-110. [PMID: 32026224 PMCID: PMC7131881 DOI: 10.1007/s10577-019-09625-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Revised: 12/20/2019] [Accepted: 12/29/2019] [Indexed: 12/26/2022]
Abstract
The nucleus is a highly organized and dynamic environment where regulation and coordination of processes such as gene expression and DNA replication are paramount. In recent years, noncoding RNAs have emerged as key participants in the regulation of nuclear processes. There are a multitude of functional roles for long noncoding RNA (lncRNA), mediated through their ability to act as molecular scaffolds bridging interactions with proteins, chromatin, and other RNA molecules within the nuclear environment. In this review, we discuss the diversity of techniques that have been developed to probe the function of nuclear lncRNAs, along with the ways in which those techniques have revealed insights into their mechanisms of action. Foundational observations into lncRNA function have been gleaned from molecular cytology-based, single-cell approaches to illuminate both the localization and abundance of lncRNAs in addition to their potential binding partners. Biochemical, extraction-based approaches have revealed the molecular contacts between lncRNAs and other molecules within the nuclear environment and how those interactions may contribute to nuclear organization and regulation. Using examples of well-studied nuclear lncRNAs, we demonstrate that the emerging functions of individual lncRNAs have been most clearly deduced from combined cytology and biochemical approaches tailored to study specific lncRNAs. As more functional nuclear lncRNAs continue to emerge, the development of additional technologies to study their interactions and mechanisms of action promise to continually expand our understanding of nuclear organization, chromosome architecture, genome regulation, and disease states.
Collapse
Affiliation(s)
| | - Anthony J Velleca
- Department of Molecular Phamacology, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Dawn M Carone
- Department of Biology, Swarthmore College, Swarthmore, PA, USA.
| |
Collapse
|
38
|
Li Y, Klase Z, Sardo L. Visualizing Chromatin Modifications in Isolated Nuclei. Methods Mol Biol 2020; 2175:23-31. [PMID: 32681481 DOI: 10.1007/978-1-0716-0763-3_3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2023]
Abstract
Modifications in chromatin structure are traditionally monitored by biochemical assays that provide average measurements of static events in a population of cells. Microscopy provides a method by which single cells or nuclei can be observed. Traditionally, microscopy has been used to image the nucleus by the application of immunostaining to chemically fixed samples or the use of exogenously expressed fluorescent proteins. This method represents an approach to observe changes in endogenous proteins relating to chromatin structure in real time. Here we describe a method for isolating transcriptionally and enzymatically active nuclei from live cells and visualizing events using fluorescently labeled antibodies. This method allows the observation of real time changes in chromatin architecture and can be used to observe the effects of drugs on nuclei while under microscopic observation.
Collapse
Affiliation(s)
- Yuan Li
- Department of Infectious Diseases and Vaccines, MRL, Merck & Co. Inc., West Point, PA, USA
| | - Zachary Klase
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, PA, USA.
| | - Luca Sardo
- Department of Infectious Diseases and Vaccines, MRL, Merck & Co. Inc., West Point, PA, USA
| |
Collapse
|
39
|
Cerase A, Armaos A, Neumayer C, Avner P, Guttman M, Tartaglia GG. Phase separation drives X-chromosome inactivation: a hypothesis. Nat Struct Mol Biol 2019; 26:331-334. [PMID: 31061525 DOI: 10.1038/s41594-019-0223-0] [Citation(s) in RCA: 75] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Andrea Cerase
- EMBL-Rome, Monterotondo, Italy. .,Blizard Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, UK.
| | - Alexandros Armaos
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Barcelona, Spain
| | - Christoph Neumayer
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA
| | | | - Mitchell Guttman
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA.
| | - Gian Gaetano Tartaglia
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Barcelona, Spain. .,ICREA and UPF, Barcelona, Spain. .,Department of Biology 'Charles Darwin', Sapienza University of Rome, Rome, Italy. .,Department of Neuroscience and Brain Technologies, Istituto Italiano di Tecnologia, Genoa, Italy.
| |
Collapse
|
40
|
Abstract
The non-coding RNA Xist regulates the process of X chromosome inactivation, in which one of the two X chromosomes present in cells of early female mammalian embryos is selectively and coordinately shut down. Remarkably Xist RNA functions in cis, affecting only the chromosome from which it is transcribed. This feature is attributable to the unique propensity of Xist RNA to accumulate over the territory of the chromosome on which it is synthesized, contrasting with the majority of RNAs that are rapidly exported out of the cell nucleus. In this review I provide an overview of the progress that has been made towards understanding localized accumulation of Xist RNA, drawing attention to evidence that some other non-coding RNAs probably function in a highly analogous manner. I describe a simple model for localized accumulation of Xist RNA and discuss key unresolved questions that need to be addressed in future studies.
Collapse
Affiliation(s)
- Neil Brockdorff
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK
| |
Collapse
|
41
|
Chagin VO, Reinhart B, Becker A, Mortusewicz O, Jost KL, Rapp A, Leonhardt H, Cardoso MC. Processive DNA synthesis is associated with localized decompaction of constitutive heterochromatin at the sites of DNA replication and repair. Nucleus 2019; 10:231-253. [PMID: 31744372 PMCID: PMC6949026 DOI: 10.1080/19491034.2019.1688932] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2019] [Revised: 09/01/2019] [Accepted: 10/22/2019] [Indexed: 12/18/2022] Open
Abstract
Constitutive heterochromatin is considered as a functionally inert genome compartment, important for its architecture and stability. How such stable structure is maintained is not well understood. Here, we apply four different visualization schemes to label it and investigate its dynamics during DNA replication and repair. We show that replisomes assemble over the heterochromatin in a temporally ordered manner. Furthermore, heterochromatin undergoes transient decompaction locally at the active sites of DNA synthesis. Using selective laser microirradiation conditions that lead to damage repaired via processive DNA synthesis, we measured similarly local decompaction of heterochromatin. In both cases, we could not observe large-scale movement of heterochromatin to the domain surface. Instead, the processive DNA synthesis machinery assembled at the replication/repair sites. Altogether, our data are compatible with a progression of DNA replication/repair along the chromatin in a dynamic mode with localized and transient decompaction that does not globally remodels the whole heterochromatin compartment.
Collapse
Affiliation(s)
- Vadim O. Chagin
- Cell Biology & Epigenetics, Department of Biology, Technische Universität Darmstadt, Darmstadt, Germany
- Institute of Cytology, Russian Academy of Sciences, St. Petersburg, Russia
| | - Britta Reinhart
- Cell Biology & Epigenetics, Department of Biology, Technische Universität Darmstadt, Darmstadt, Germany
| | - Annette Becker
- Cell Biology & Epigenetics, Department of Biology, Technische Universität Darmstadt, Darmstadt, Germany
| | | | - K. Laurence Jost
- Cell Biology & Epigenetics, Department of Biology, Technische Universität Darmstadt, Darmstadt, Germany
| | - Alexander Rapp
- Cell Biology & Epigenetics, Department of Biology, Technische Universität Darmstadt, Darmstadt, Germany
| | | | - M. Cristina Cardoso
- Cell Biology & Epigenetics, Department of Biology, Technische Universität Darmstadt, Darmstadt, Germany
| |
Collapse
|
42
|
Syrett CM, Sierra I, Beethem ZT, Dubin AH, Anguera MC. Loss of epigenetic modifications on the inactive X chromosome and sex-biased gene expression profiles in B cells from NZB/W F1 mice with lupus-like disease. J Autoimmun 2019; 107:102357. [PMID: 31780316 DOI: 10.1016/j.jaut.2019.102357] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Revised: 10/30/2019] [Accepted: 11/01/2019] [Indexed: 12/29/2022]
Abstract
The mechanisms underlying the female-bias in autoimmunity are poorly understood. The contribution of genetic and epigenetic factors from the inactive X chromosome (Xi) are beginning to emerge as critical mediators of autoimmunity in females. Here, we ask how epigenetic features of the Xi change during disease development in B cells from the NZB/W F1 spontaneous mouse model of lupus, which is female-biased. We find that Xist RNA becomes increasingly mislocalized from the Xi with disease onset. While NZB/W F1 naïve B cells have H3K27me3 foci on the Xi, which are missing from healthy C57BL/6 and BALB/c mice, these foci are progressively lost in stimulated B cells during disease. Using single-molecule RNA FISH, we show that the X-linked gene Tlr7 is biallelically expressed in ~20% of NZB/W F1 B cells, and that the amount of biallelic expression does not change with disease. We also present sex-specific gene expression profiles for diseased NZB/W F1 B cells, and find female-specific upregulation of 20 genes, including the autoimmunity-related genes Cxcl13, Msr1, Igj, and Prdm1. Together, these studies provide important insight into the loss of epigenetic modifications from the Xi and changes with gene expression in a mouse model of female-biased SLE.
Collapse
Affiliation(s)
- Camille M Syrett
- Department of Biomedical Sciences, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Isabel Sierra
- Department of Biomedical Sciences, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Zachary T Beethem
- Department of Biomedical Sciences, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Aimee H Dubin
- Department of Biomedical Sciences, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Montserrat C Anguera
- Department of Biomedical Sciences, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, USA.
| |
Collapse
|
43
|
Rosin LF, Crocker O, Isenhart RL, Nguyen SC, Xu Z, Joyce EF. Chromosome territory formation attenuates the translocation potential of cells. eLife 2019; 8:49553. [PMID: 31682226 PMCID: PMC6855801 DOI: 10.7554/elife.49553] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Accepted: 11/02/2019] [Indexed: 12/11/2022] Open
Abstract
The formation and spatial arrangement of chromosome territories (CTs) in interphase has been posited to influence the outcome and frequency of genomic translocations. This is supported by correlations between the frequency of inter-chromosomal contacts and translocation events in myriad systems. However, it remains unclear if CT formation itself influences the translocation potential of cells. We address this question in Drosophila cells by modulating the level of Condensin II, which regulates CT organization. Using whole-chromosome Oligopaints to identify genomic rearrangements, we find that increased contact frequencies between chromosomes due to Condensin II knockdown leads to an increased propensity to form translocations following DNA damage. Moreover, Condensin II over-expression is sufficient to drive spatial separation of CTs and attenuate the translocation potential of cells. Together, these results provide the first causal evidence that proper CT formation can protect the genome from potentially deleterious translocations in the presence of DNA damage.
Collapse
Affiliation(s)
- Leah F Rosin
- Department of Genetics, Penn Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, United States
| | - Olivia Crocker
- Department of Genetics, Penn Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, United States
| | - Randi L Isenhart
- Department of Genetics, Penn Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, United States
| | - Son C Nguyen
- Department of Genetics, Penn Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, United States
| | - Zhuxuan Xu
- Department of Genetics, Penn Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, United States
| | - Eric F Joyce
- Department of Genetics, Penn Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, United States
| |
Collapse
|
44
|
Razin SV, Ulianov SV, Gavrilov AA. 3D Genomics. Mol Biol 2019; 53:802-812. [DOI: 10.1134/s0026893319060153] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2019] [Revised: 06/01/2019] [Accepted: 06/03/2019] [Indexed: 08/30/2023]
|
45
|
Ochs F, Karemore G, Miron E, Brown J, Sedlackova H, Rask MB, Lampe M, Buckle V, Schermelleh L, Lukas J, Lukas C. Stabilization of chromatin topology safeguards genome integrity. Nature 2019; 574:571-574. [DOI: 10.1038/s41586-019-1659-4] [Citation(s) in RCA: 104] [Impact Index Per Article: 20.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2018] [Accepted: 09/10/2019] [Indexed: 11/10/2022]
|
46
|
Cheutin T, Cavalli G. The multiscale effects of polycomb mechanisms on 3D chromatin folding. Crit Rev Biochem Mol Biol 2019; 54:399-417. [PMID: 31698957 DOI: 10.1080/10409238.2019.1679082] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Revised: 10/08/2019] [Accepted: 10/08/2019] [Indexed: 12/30/2022]
Abstract
Polycomb group (PcG) proteins silence master regulatory genes required to properly confer cell identity during the development of both Drosophila and mammals. They may act through chromatin compaction and higher-order folding of chromatin inside the cell nucleus. During the last decade, analysis on interphase chromosome architecture discovered self-interacting regions named topologically associated domains (TADs). TADs result from the 3D chromatin folding of a succession of transcribed and repressed epigenomic domains and from loop extrusion mediated by cohesin/CTCF in mammals. Polycomb silenced chromatin constitutes one type of repressed epigenomic domains which form compacted nano-compartments inside cell nuclei. Recruitment of canonical PcG proteins on chromatin relies on initial binding to discrete elements and further spreading into large chromatin domains covered with H3K27me3. Some of these discrete elements have a bivalent nature both in mammals and Drosophila and are dynamically regulated during development. Loops can occur between them, suggesting that their interaction plays both functional and structural roles. Formation of large chromatin domains covered by H3K27me3 seems crucial for PcG silencing and PcG proteins might exert their function through compaction of these domains in both mammals and flies, rather than by directly controlling the nucleosomal accessibility of discrete regulatory elements. In addition, PcG chromatin domains interact over long genomic distances, shaping a higher-order chromatin network. Therefore, PcG silencing might rely on multiscale chromatin folding to maintain cell identity during differentiation.
Collapse
Affiliation(s)
- Thierry Cheutin
- Institute of Human Genetics, CNRS and the University of Montpellier, Montpellier, France
| | - Giacomo Cavalli
- Institute of Human Genetics, CNRS and the University of Montpellier, Montpellier, France
| |
Collapse
|
47
|
Abstract
In mammals, dosage compensation of sex chromosomal genes between females (XX) and males (XY) is achieved through X-chromosome inactivation (XCI). The X-linked X-inactive-specific transcript (Xist) long noncoding RNA is indispensable for XCI and initiates the process early during development by spreading in cis across the X chromosome from which it is transcribed. During XCI, Xist RNA triggers gene silencing, recruits a plethora of chromatin modifying factors, and drives a major structural reorganization of the X chromosome. Here, we review our knowledge of the multitude of epigenetic events orchestrated by Xist RNA to allow female mammals to survive through embryonic development by establishing and maintaining proper dosage compensation. In particular, we focus on recent studies characterizing the interaction partners of Xist RNA, and we discuss how they have affected the field by addressing long-standing controversies or by giving rise to new research perspectives that are currently being explored. This review is dedicated to the memory of Denise Barlow, pioneer of genomic imprinting and functional long noncoding RNAs (lncRNAs), whose work has revolutionized the epigenetics field and continues to inspire generations of scientists.
Collapse
|
48
|
Schertzer MD, Braceros KC, Starmer J, Cherney RE, Lee DM, Salazar G, Justice M, Bischoff SR, Cowley DO, Ariel P, Zylka MJ, Dowen JM, Magnuson T, Calabrese JM. lncRNA-Induced Spread of Polycomb Controlled by Genome Architecture, RNA Abundance, and CpG Island DNA. Mol Cell 2019; 75:523-537.e10. [PMID: 31256989 PMCID: PMC6688959 DOI: 10.1016/j.molcel.2019.05.028] [Citation(s) in RCA: 79] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2018] [Revised: 04/10/2019] [Accepted: 05/17/2019] [Indexed: 01/28/2023]
Abstract
Long noncoding RNAs (lncRNAs) cause Polycomb repressive complexes (PRCs) to spread over broad regions of the mammalian genome. We report that in mouse trophoblast stem cells, the Airn and Kcnq1ot1 lncRNAs induce PRC-dependent chromatin modifications over multi-megabase domains. Throughout the Airn-targeted domain, the extent of PRC-dependent modification correlated with intra-nuclear distance to the Airn locus, preexisting genome architecture, and the abundance of Airn itself. Specific CpG islands (CGIs) displayed characteristics indicating that they nucleate the spread of PRCs upon exposure to Airn. Chromatin environments surrounding Xist, Airn, and Kcnq1ot1 suggest common mechanisms of PRC engagement and spreading. Our data indicate that lncRNA potency can be tightly linked to lncRNA abundance and that within lncRNA-targeted domains, PRCs are recruited to CGIs via lncRNA-independent mechanisms. We propose that CGIs that autonomously recruit PRCs interact with lncRNAs and their associated proteins through three-dimensional space to nucleate the spread of PRCs in lncRNA-targeted domains.
Collapse
Affiliation(s)
- Megan D. Schertzer
- Department of Pharmacology, University of North Carolina, Chapel Hill, NC, 27599,Curriculum in Genetics and Molecular Biology, University of North Carolina, Chapel Hill, NC, 27599
| | - Keean C.A. Braceros
- Department of Pharmacology, University of North Carolina, Chapel Hill, NC, 27599,Curriculum in Mechanistic, Interdisciplinary Studies of Biological Systems, University of North Carolina, Chapel Hill, NC, 27599
| | - Joshua Starmer
- Department of Genetics, University of North Carolina, Chapel Hill, NC, 27599
| | - Rachel E. Cherney
- Department of Pharmacology, University of North Carolina, Chapel Hill, NC, 27599,Curriculum in Genetics and Molecular Biology, University of North Carolina, Chapel Hill, NC, 27599
| | - David M. Lee
- Department of Pharmacology, University of North Carolina, Chapel Hill, NC, 27599,Curriculum in Genetics and Molecular Biology, University of North Carolina, Chapel Hill, NC, 27599
| | - Gabriela Salazar
- Department of Cell Biology and Physiology and UNC Neuroscience Center, University of North Carolina, Chapel Hill, NC, 27599
| | - Megan Justice
- Curriculum in Genetics and Molecular Biology, University of North Carolina, Chapel Hill, NC, 27599,Integrative Program for Biological and Genome Sciences, University of North Carolina, Chapel Hill, NC, 27599
| | - Steven R. Bischoff
- Animal Models Core, University of North Carolina, Chapel Hill, NC, 27599
| | - Dale O. Cowley
- Animal Models Core, University of North Carolina, Chapel Hill, NC, 27599
| | - Pablo Ariel
- Microscopy Services Laboratory and Department of Pathology and Laboratory Medicine, University of North Carolina, Chapel Hill, NC, 27599
| | - Mark J. Zylka
- Department of Cell Biology and Physiology and UNC Neuroscience Center, University of North Carolina, Chapel Hill, NC, 27599
| | - Jill M. Dowen
- Curriculum in Genetics and Molecular Biology, University of North Carolina, Chapel Hill, NC, 27599,Integrative Program for Biological and Genome Sciences, University of North Carolina, Chapel Hill, NC, 27599,Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, NC, 27599,Department of Biology, University of North Carolina, Chapel Hill, NC, 27599,Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC, 27599
| | - Terry Magnuson
- Department of Genetics, University of North Carolina, Chapel Hill, NC, 27599,Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC, 27599
| | - J. Mauro Calabrese
- Department of Pharmacology, University of North Carolina, Chapel Hill, NC, 27599,Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC, 27599,Lead contact.,Correspondence:
| |
Collapse
|
49
|
Xu J, Liu Y. A guide to visualizing the spatial epigenome with super-resolution microscopy. FEBS J 2019; 286:3095-3109. [PMID: 31127980 DOI: 10.1111/febs.14938] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2018] [Revised: 03/24/2019] [Accepted: 05/23/2019] [Indexed: 12/28/2022]
Abstract
Genomic DNA in eukaryotic cells is tightly compacted with histone proteins into nucleosomes, which are further packaged into the higher-order chromatin structure. The physical structuring of chromatin is highly dynamic and regulated by a large number of epigenetic modifications in response to various environmental exposures, both in normal development and pathological processes such as aging and cancer. Higher-order chromatin structure has been indirectly inferred by conventional bulk biochemical assays on cell populations, which do not allow direct visualization of the spatial information of epigenomics (referred to as spatial epigenomics). With recent advances in super-resolution microscopy, the higher-order chromatin structure can now be visualized in vivo at an unprecedent resolution. This opens up new opportunities to study physical compaction of 3D chromatin structure in single cells, maintaining a well-preserved spatial context of tissue microenvironment. This review discusses the recent application of super-resolution fluorescence microscopy to investigate the higher-order chromatin structure of different epigenomic states. We also envision the synergistic integration of super-resolution microscopy and high-throughput genomic technologies for the analysis of spatial epigenomics to fully understand the genome function in normal biological processes and diseases.
Collapse
Affiliation(s)
- Jianquan Xu
- Biomedical Optical Imaging Laboratory, Departments of Medicine and Bioengineering, University of Pittsburgh, Pittsburgh, PA, USA
| | - Yang Liu
- Biomedical Optical Imaging Laboratory, Departments of Medicine and Bioengineering, University of Pittsburgh, Pittsburgh, PA, USA
| |
Collapse
|
50
|
Szabo Q, Bantignies F, Cavalli G. Principles of genome folding into topologically associating domains. SCIENCE ADVANCES 2019; 5:eaaw1668. [PMID: 30989119 PMCID: PMC6457944 DOI: 10.1126/sciadv.aaw1668] [Citation(s) in RCA: 317] [Impact Index Per Article: 63.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2018] [Accepted: 02/20/2019] [Indexed: 05/12/2023]
Abstract
This review discusses the features of TADs across species, and their role in chromosome organization, genome function, and evolution.
Collapse
Affiliation(s)
- Quentin Szabo
- Institute of Human Genetics, CNRS and University of Montpellier, Montpellier, France
| | - Frédéric Bantignies
- Institute of Human Genetics, CNRS and University of Montpellier, Montpellier, France
| | - Giacomo Cavalli
- Institute of Human Genetics, CNRS and University of Montpellier, Montpellier, France
| |
Collapse
|