1
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Dror I, Tan T, Plath K. A critical role for X-chromosome architecture in mammalian X-chromosome dosage compensation. Curr Opin Genet Dev 2024; 87:102235. [PMID: 39053028 DOI: 10.1016/j.gde.2024.102235] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2024] [Revised: 07/02/2024] [Accepted: 07/05/2024] [Indexed: 07/27/2024]
Abstract
To regulate gene expression, the macromolecular components of the mammalian interphase nucleus are spatially organized into a myriad of functional compartments. Over the past decade, increasingly sophisticated genomics, microscopy, and functional approaches have probed this organization in unprecedented detail. These investigations have linked chromatin-associated noncoding RNAs to specific nuclear compartments and uncovered mechanisms by which these RNAs establish such domains. In this review, we focus on the long non-coding RNA Xist and summarize new evidence demonstrating the significance of chromatin reconfiguration in creating the inactive X-chromosome compartment. Differences in chromatin compaction correlate with distinct levels of gene repression on the X-chromosome, potentially explaining how human XIST can induce chromosome-wide dampening and silencing of gene expression at different stages of human development.
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Affiliation(s)
- Iris Dror
- Department of Biological Chemistry, David Geffen School of Medicine at the University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Tiao Tan
- Department of Biological Chemistry, David Geffen School of Medicine at the University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Kathrin Plath
- Department of Biological Chemistry, David Geffen School of Medicine at the University of California Los Angeles, Los Angeles, CA 90095, USA; Molecular Biology Institute, Jonsson Comprehensive Cancer Center, Brain Research Institute, Graduate Program in the Biosciences, Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, University of California Los Angeles, Los Angeles, CA 90095, USA.
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2
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Martitz A, Schulz EG. Spatial orchestration of the genome: topological reorganisation during X-chromosome inactivation. Curr Opin Genet Dev 2024; 86:102198. [PMID: 38663040 DOI: 10.1016/j.gde.2024.102198] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2024] [Revised: 03/21/2024] [Accepted: 04/05/2024] [Indexed: 06/11/2024]
Abstract
Genomes are organised through hierarchical structures, ranging from local kilobase-scale cis-regulatory contacts to large chromosome territories. Most notably, (sub)-compartments partition chromosomes according to transcriptional activity, while topologically associating domains (TADs) define cis-regulatory landscapes. The inactive X chromosome in mammals has provided unique insights into the regulation and function of the three-dimensional (3D) genome. Concurrent with silencing of the majority of genes and major alterations of its chromatin state, the X chromosome undergoes profound spatial rearrangements at multiple scales. These include the emergence of megadomains, alterations of the compartment structure and loss of the majority of TADs. Moreover, the Xist locus, which orchestrates X-chromosome inactivation, has provided key insights into regulation and function of regulatory domains. This review provides an overview of recent insights into the control of these structural rearrangements and contextualises them within a broader understanding of 3D genome organisation.
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Affiliation(s)
- Alexandra Martitz
- Systems Epigenetics, Otto Warburg Laboratories, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany; Department of Biology, Chemistry, Pharmacy, Freie Universität Berlin, 14195 Berlin, Germany
| | - Edda G Schulz
- Systems Epigenetics, Otto Warburg Laboratories, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany.
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3
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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.
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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.
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4
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Kitamura Y, Takahashi K, Maezawa S, Munakata Y, Sakashita A, Kaplan N, Namekawa SH. CTCF-mediated 3D chromatin predetermines the gene expression program in the male germline. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.30.569508. [PMID: 38076840 PMCID: PMC10705413 DOI: 10.1101/2023.11.30.569508] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/18/2023]
Abstract
Spermatogenesis is a unidirectional differentiation process that generates haploid sperm, but how the gene expression program that directs this process is established is largely unknown. Here we determine the high-resolution 3D chromatin architecture of male germ cells during spermatogenesis and show that CTCF-mediated 3D chromatin predetermines the gene expression program required for spermatogenesis. In undifferentiated spermatogonia, CTCF-mediated chromatin contacts on autosomes pre-establish meiosis-specific super-enhancers (SE). These meiotic SE recruit the master transcription factor A-MYB in meiotic spermatocytes, which strengthens their 3D contacts and instructs a burst of meiotic gene expression. We also find that at the mitosis-to-meiosis transition, the germline-specific Polycomb protein SCML2 resolves chromatin loops that are specific to mitotic spermatogonia. Moreover, SCML2 and A-MYB establish the unique 3D chromatin organization of sex chromosomes during meiotic sex chromosome inactivation. We propose that CTCF-mediated 3D chromatin organization enforces epigenetic priming that directs unidirectional differentiation, thereby determining the cellular identity of the male germline.
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Affiliation(s)
- Yuka Kitamura
- Department of Microbiology and Molecular Genetics, University of California, Davis, Davis, CA, 95616, USA
| | - Kazuki Takahashi
- Division of Reproductive Sciences, Division of Developmental Biology, Perinatal Institute, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH, 45229, USA
| | - So Maezawa
- Division of Reproductive Sciences, Division of Developmental Biology, Perinatal Institute, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH, 45229, USA
- Faculty of Science and Technology, Department of Applied Biological Science, Tokyo University of Science, Noda, Chiba, 281-8510, Japan
| | - Yasuhisa Munakata
- Department of Microbiology and Molecular Genetics, University of California, Davis, Davis, CA, 95616, USA
- Division of Reproductive Sciences, Division of Developmental Biology, Perinatal Institute, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH, 45229, USA
| | - Akihiko Sakashita
- Division of Reproductive Sciences, Division of Developmental Biology, Perinatal Institute, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH, 45229, USA
- Department of Molecular Biology, Keio University School of Medicine, Tokyo, 160-8582 Japan
| | - Noam Kaplan
- Department of Physiology, Biophysics & Systems Biology, Rappaport Faculty of Medicine, Technion - Israel Institute of Technology, Haifa, Israel
| | - Satoshi H. Namekawa
- Department of Microbiology and Molecular Genetics, University of California, Davis, Davis, CA, 95616, USA
- Division of Reproductive Sciences, Division of Developmental Biology, Perinatal Institute, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH, 45229, USA
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5
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Keniry A, Blewitt ME. Chromatin-mediated silencing on the inactive X chromosome. Development 2023; 150:dev201742. [PMID: 37991053 DOI: 10.1242/dev.201742] [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: 11/23/2023]
Abstract
In mammals, the second X chromosome in females is silenced to enable dosage compensation between XX females and XY males. This essential process involves the formation of a dense chromatin state on the inactive X (Xi) chromosome. There is a wealth of information about the hallmarks of Xi chromatin and the contribution each makes to silencing, leaving the tantalising possibility of learning from this knowledge to potentially remove silencing to treat X-linked diseases in females. Here, we discuss the role of each chromatin feature in the establishment and maintenance of the silent state, which is of crucial relevance for such a goal.
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Affiliation(s)
- Andrew Keniry
- Epigenetics and Development Division, The Walter and Eliza Hall Institute for Medical Research, 1G Royal Parade, Parkville, VIC 3052, Australia
- The Department of Medical Biology, University of Melbourne, Parkville, VIC 3010, Australia
| | - Marnie E Blewitt
- Epigenetics and Development Division, The Walter and Eliza Hall Institute for Medical Research, 1G Royal Parade, Parkville, VIC 3052, Australia
- The Department of Medical Biology, University of Melbourne, Parkville, VIC 3010, Australia
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6
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Bredemeyer KR, Hillier L, Harris AJ, Hughes GM, Foley NM, Lawless C, Carroll RA, Storer JM, Batzer MA, Rice ES, Davis BW, Raudsepp T, O'Brien SJ, Lyons LA, Warren WC, Murphy WJ. Single-haplotype comparative genomics provides insights into lineage-specific structural variation during cat evolution. Nat Genet 2023; 55:1953-1963. [PMID: 37919451 PMCID: PMC10845050 DOI: 10.1038/s41588-023-01548-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2023] [Accepted: 09/20/2023] [Indexed: 11/04/2023]
Abstract
The role of structurally dynamic genomic regions in speciation is poorly understood due to challenges inherent in diploid genome assembly. Here we reconstructed the evolutionary dynamics of structural variation in five cat species by phasing the genomes of three interspecies F1 hybrids to generate near-gapless single-haplotype assemblies. We discerned that cat genomes have a paucity of segmental duplications relative to great apes, explaining their remarkable karyotypic stability. X chromosomes were hotspots of structural variation, including enrichment with inversions in a large recombination desert with characteristics of a supergene. The X-linked macrosatellite DXZ4 evolves more rapidly than 99.5% of the genome clarifying its role in felid hybrid incompatibility. Resolved sensory gene repertoires revealed functional copy number changes associated with ecomorphological adaptations, sociality and domestication. This study highlights the value of gapless genomes to reveal structural mechanisms underpinning karyotypic evolution, reproductive isolation and ecological niche adaptation.
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Affiliation(s)
- Kevin R Bredemeyer
- Veterinary Integrative Biosciences, Texas A&M University, College Station, TX, USA
- Interdisciplinary Program in Genetics & Genomics, Texas A&M University, College Station, TX, USA
| | - LaDeana Hillier
- Department of Genome Sciences, University of Washington, Seattle, WA, USA
| | - Andrew J Harris
- Veterinary Integrative Biosciences, Texas A&M University, College Station, TX, USA
- Interdisciplinary Program in Genetics & Genomics, Texas A&M University, College Station, TX, USA
| | - Graham M Hughes
- School of Biology & Environmental Sciences, University College Dublin, Dublin, Ireland
| | - Nicole M Foley
- Veterinary Integrative Biosciences, Texas A&M University, College Station, TX, USA
| | - Colleen Lawless
- School of Biology & Environmental Sciences, University College Dublin, Dublin, Ireland
| | - Rachel A Carroll
- Department of Animal Sciences, University of Missouri, Columbia, MO, USA
| | | | - Mark A Batzer
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA, USA
| | - Edward S Rice
- Department of Animal Sciences, University of Missouri, Columbia, MO, USA
| | - Brian W Davis
- Veterinary Integrative Biosciences, Texas A&M University, College Station, TX, USA
- Interdisciplinary Program in Genetics & Genomics, Texas A&M University, College Station, TX, USA
| | - Terje Raudsepp
- Veterinary Integrative Biosciences, Texas A&M University, College Station, TX, USA
- Interdisciplinary Program in Genetics & Genomics, Texas A&M University, College Station, TX, USA
| | - Stephen J O'Brien
- Guy Harvey Oceanographic Center, Nova Southeastern University, Fort Lauderdale, FL, USA
| | - Leslie A Lyons
- Department of Veterinary Medicine & Surgery, University of Missouri, Columbia, MO, USA
| | - Wesley C Warren
- Department of Animal Sciences, University of Missouri, Columbia, MO, USA.
| | - William J Murphy
- Veterinary Integrative Biosciences, Texas A&M University, College Station, TX, USA.
- Interdisciplinary Program in Genetics & Genomics, Texas A&M University, College Station, TX, USA.
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7
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Lin J, Zhang J, Ma L, Fang H, Ma R, Groneck C, Filippova GN, Deng X, Ma W, Disteche CM, Berletch JB. KDM6A facilitates Xist upregulation at the onset of X inactivation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.16.553617. [PMID: 37645756 PMCID: PMC10462084 DOI: 10.1101/2023.08.16.553617] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/31/2023]
Abstract
X chromosome inactivation (XCI) is a female-specific process in which one X chromosome is silenced to balance X-linked gene expression between the sexes. XCI is initiated in early development by upregulation of the lncRNA Xist on the future inactive X (Xi). A subset of X-linked genes escape silencing and thus have higher expression in females, suggesting female-specific functions. One of these genes is the highly conserved gene Kdm6a , which encodes a histone demethylase that removes methyl groups at H3K27 to facilitate gene expression. Here, we investigate the role of KDM6A in the regulation of Xist . We observed impaired upregulation of Xist during early stages of differentiation in hybrid mouse ES cells following CRISPR/Cas9 knockout of Kdm6a . This is associated with reduced Xist RNA coating of the Xi, suggesting diminished XCI potency. Indeed, Kdm6a knockout results in aberrant overexpression of genes from the Xi after differentiation. KDM6A binds to the Xist promoter and knockout cells show an increase in H3K27me3 at Xist . These results indicate that KDM6A plays a role in the initiation of XCI through histone demethylase-dependent activation of Xist during early differentiation.
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8
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Dekker J, Alber F, Aufmkolk S, Beliveau BJ, Bruneau BG, Belmont AS, Bintu L, Boettiger A, Calandrelli R, Disteche CM, Gilbert DM, Gregor T, Hansen AS, Huang B, Huangfu D, Kalhor R, Leslie CS, Li W, Li Y, Ma J, Noble WS, Park PJ, Phillips-Cremins JE, Pollard KS, Rafelski SM, Ren B, Ruan Y, Shav-Tal Y, Shen Y, Shendure J, Shu X, Strambio-De-Castillia C, Vertii A, Zhang H, Zhong S. Spatial and temporal organization of the genome: Current state and future aims of the 4D nucleome project. Mol Cell 2023; 83:2624-2640. [PMID: 37419111 PMCID: PMC10528254 DOI: 10.1016/j.molcel.2023.06.018] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2023] [Revised: 06/10/2023] [Accepted: 06/12/2023] [Indexed: 07/09/2023]
Abstract
The four-dimensional nucleome (4DN) consortium studies the architecture of the genome and the nucleus in space and time. We summarize progress by the consortium and highlight the development of technologies for (1) mapping genome folding and identifying roles of nuclear components and bodies, proteins, and RNA, (2) characterizing nuclear organization with time or single-cell resolution, and (3) imaging of nuclear organization. With these tools, the consortium has provided over 2,000 public datasets. Integrative computational models based on these data are starting to reveal connections between genome structure and function. We then present a forward-looking perspective and outline current aims to (1) delineate dynamics of nuclear architecture at different timescales, from minutes to weeks as cells differentiate, in populations and in single cells, (2) characterize cis-determinants and trans-modulators of genome organization, (3) test functional consequences of changes in cis- and trans-regulators, and (4) develop predictive models of genome structure and function.
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Affiliation(s)
- Job Dekker
- University of Massachusetts Chan Medical School, Boston, MA, USA; Howard Hughes Medical Institute, Chevy Chase, MD, USA.
| | - Frank Alber
- University of California, Los Angeles, Los Angeles, CA, USA
| | | | | | - Benoit G Bruneau
- Gladstone Institutes, San Francisco, CA, USA; University of California, San Francisco, San Francisco, CA, USA
| | | | | | | | | | | | | | | | | | - Bo Huang
- University of California, San Francisco, San Francisco, CA, USA
| | - Danwei Huangfu
- Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Reza Kalhor
- Johns Hopkins University, Baltimore, MD, USA
| | | | - Wenbo Li
- University of Texas Health Science Center at Houston, Houston, TX, USA
| | - Yun Li
- University of North Carolina, Gillings School of Global Public Health, Chapel Hill, NC, USA
| | - Jian Ma
- Carnegie Mellon University, Pittsburgh, PA, USA
| | | | | | | | - Katherine S Pollard
- Gladstone Institutes, San Francisco, CA, USA; University of California, San Francisco, San Francisco, CA, USA; Chan Zuckerberg Biohub, San Francisco, San Francisco, CA, USA
| | | | - Bing Ren
- University of California, San Diego, La Jolla, CA, USA
| | - Yijun Ruan
- Zhejiang University, Hangzhou, Zhejiang, China
| | | | - Yin Shen
- University of California, San Francisco, San Francisco, CA, USA
| | | | - Xiaokun Shu
- University of California, San Francisco, San Francisco, CA, USA
| | | | | | | | - Sheng Zhong
- University of California, San Diego, La Jolla, CA, USA.
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9
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Poonperm R, Ichihara S, Miura H, Tanigawa A, Nagao K, Obuse C, Sado T, Hiratani I. Replication dynamics identifies the folding principles of the inactive X chromosome. Nat Struct Mol Biol 2023; 30:1224-1237. [PMID: 37563439 PMCID: PMC10442229 DOI: 10.1038/s41594-023-01052-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2022] [Accepted: 06/28/2023] [Indexed: 08/12/2023]
Abstract
Chromosome-wide late replication is an enigmatic hallmark of the inactive X chromosome (Xi). How it is established and what it represents remains obscure. By single-cell DNA replication sequencing, here we show that the entire Xi is reorganized to replicate rapidly and uniformly in late S-phase during X-chromosome inactivation (XCI), reflecting its relatively uniform structure revealed by 4C-seq. Despite this uniformity, only a subset of the Xi became earlier replicating in SmcHD1-mutant cells. In the mutant, these domains protruded out of the Xi core, contacted each other and became transcriptionally reactivated. 4C-seq suggested that they constituted the outermost layer of the Xi even before XCI and were rich in escape genes. We propose that this default positioning forms the basis for their inherent heterochromatin instability in cells lacking the Xi-binding protein SmcHD1 or exhibiting XCI escape. These observations underscore the importance of 3D genome organization for heterochromatin stability and gene regulation.
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Affiliation(s)
- Rawin Poonperm
- Laboratory for Developmental Epigenetics, RIKEN Center for Biosystems Dynamics Research (BDR), Kobe, Japan
| | - Saya Ichihara
- Department of Advanced Bioscience, Graduate School of Agriculture, Kindai University, Nara, Japan
- Cell Architecture Laboratory, Department of Chromosome Science, National Institute of Genetics, Shizuoka, Japan
| | - Hisashi Miura
- Laboratory for Developmental Epigenetics, RIKEN Center for Biosystems Dynamics Research (BDR), Kobe, Japan
| | - Akie Tanigawa
- Laboratory for Developmental Epigenetics, RIKEN Center for Biosystems Dynamics Research (BDR), Kobe, Japan
| | - Koji Nagao
- Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Japan
| | - Chikashi Obuse
- Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Japan
| | - Takashi Sado
- Department of Advanced Bioscience, Graduate School of Agriculture, Kindai University, Nara, Japan
- Agricultural Technology and Innovation Research Institute, Kindai University, Nara, Japan
| | - Ichiro Hiratani
- Laboratory for Developmental Epigenetics, RIKEN Center for Biosystems Dynamics Research (BDR), Kobe, Japan.
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10
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Fang H, Tronco AR, Bonora G, Nguyen T, Thakur J, Berletch JB, Filippova GN, Henikoff S, Shendure J, Noble WS, Disteche CM, Deng X. CTCF-mediated insulation and chromatin environment modulate Car5b escape from X inactivation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.04.539469. [PMID: 37205597 PMCID: PMC10187265 DOI: 10.1101/2023.05.04.539469] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Background The number and escape levels of genes that escape X chromosome inactivation (XCI) in female somatic cells vary among tissues and cell types, potentially contributing to specific sex differences. Here we investigate the role of CTCF, a master chromatin conformation regulator, in regulating escape from XCI. CTCF binding profiles and epigenetic features were systematically examined at constitutive and facultative escape genes using mouse allelic systems to distinguish the inactive X (Xi) and active X (Xa) chromosomes. Results We found that escape genes are located inside domains flanked by convergent arrays of CTCF binding sites, consistent with the formation of loops. In addition, strong and divergent CTCF binding sites often located at the boundaries between escape genes and adjacent neighbors subject to XCI would help insulate domains. Facultative escapees show clear differences in CTCF binding dependent on their XCI status in specific cell types/tissues. Concordantly, deletion but not inversion of a CTCF binding site at the boundary between the facultative escape gene Car5b and its silent neighbor Siah1b resulted in loss of Car5b escape. Reduced CTCF binding and enrichment of a repressive mark over Car5b in cells with a boundary deletion indicated loss of looping and insulation. In mutant lines in which either the Xi-specific compact structure or its H3K27me3 enrichment was disrupted, escape genes showed an increase in gene expression and associated active marks, supporting the roles of the 3D Xi structure and heterochromatic marks in constraining levels of escape. Conclusion Our findings indicate that escape from XCI is modulated both by looping and insulation of chromatin via convergent arrays of CTCF binding sites and by compaction and epigenetic features of the surrounding heterochromatin.
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Affiliation(s)
- He Fang
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA, 98195
| | - Ana R Tronco
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA, 98195
| | - Giancarlo Bonora
- Department of Genome Sciences, University of Washington, Seattle, WA, 98195
| | - Truong Nguyen
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA, 98195
| | - Jitendra Thakur
- Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA, 98109
| | - Joel B Berletch
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA, 98195
| | - Galina N Filippova
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA, 98195
| | - Steven Henikoff
- Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA, 98109
| | - Jay Shendure
- Department of Genome Sciences, University of Washington, Seattle, WA, 98195
| | - William S Noble
- Department of Genome Sciences, University of Washington, Seattle, WA, 98195
- Paul G. Allen School of Computer Science and Engineering, University of Washington, Seattle, WA, 98195
| | - Christine M Disteche
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA, 98195
- Department of Medicine, University of Washington, Seattle, WA, 98195
| | - Xinxian Deng
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA, 98195
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11
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Strathmann EA, Hölker I, Tschernoster N, Hosseinibarkooie S, Come J, Martinat C, Altmüller J, Wirth B. Epigenetic regulation of plastin 3 expression by the macrosatellite DXZ4 and the transcriptional regulator CHD4. Am J Hum Genet 2023; 110:442-459. [PMID: 36812914 PMCID: PMC10027515 DOI: 10.1016/j.ajhg.2023.02.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Accepted: 02/03/2023] [Indexed: 02/23/2023] Open
Abstract
Dysregulated Plastin 3 (PLS3) levels associate with a wide range of skeletal and neuromuscular disorders and the most common types of solid and hematopoietic cancer. Most importantly, PLS3 overexpression protects against spinal muscular atrophy. Despite its crucial role in F-actin dynamics in healthy cells and its involvement in many diseases, the mechanisms that regulate PLS3 expression are unknown. Interestingly, PLS3 is an X-linked gene and all asymptomatic SMN1-deleted individuals in SMA-discordant families who exhibit PLS3 upregulation are female, suggesting that PLS3 may escape X chromosome inactivation. To elucidate mechanisms contributing to PLS3 regulation, we performed a multi-omics analysis in two SMA-discordant families using lymphoblastoid cell lines and iPSC-derived spinal motor neurons originated from fibroblasts. We show that PLS3 tissue-specifically escapes X-inactivation. PLS3 is located ∼500 kb proximal to the DXZ4 macrosatellite, which is essential for X chromosome inactivation. By applying molecular combing in a total of 25 lymphoblastoid cell lines (asymptomatic individuals, individuals with SMA, control subjects) with variable PLS3 expression, we found a significant correlation between the copy number of DXZ4 monomers and PLS3 levels. Additionally, we identified chromodomain helicase DNA binding protein 4 (CHD4) as an epigenetic transcriptional regulator of PLS3 and validated co-regulation of the two genes by siRNA-mediated knock-down and overexpression of CHD4. We show that CHD4 binds the PLS3 promoter by performing chromatin immunoprecipitation and that CHD4/NuRD activates the transcription of PLS3 by dual-luciferase promoter assays. Thus, we provide evidence for a multilevel epigenetic regulation of PLS3 that may help to understand the protective or disease-associated PLS3 dysregulation.
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Affiliation(s)
- Eike A Strathmann
- Institute of Human Genetics, University Hospital of Cologne, University Cologne, Kerpener Str. 34, 50931 Cologne, Germany; Center for Molecular Medicine Cologne, University of Cologne, 50931 Cologne, Germany; Institute for Genetics, University of Cologne, 50674 Cologne, Germany
| | - Irmgard Hölker
- Institute of Human Genetics, University Hospital of Cologne, University Cologne, Kerpener Str. 34, 50931 Cologne, Germany; Center for Molecular Medicine Cologne, University of Cologne, 50931 Cologne, Germany; Institute for Genetics, University of Cologne, 50674 Cologne, Germany
| | - Nikolai Tschernoster
- Institute of Human Genetics, University Hospital of Cologne, University Cologne, Kerpener Str. 34, 50931 Cologne, Germany; Cologne Center for Genomics and West German Genome Center, University of Cologne, 50931 Cologne, Germany
| | - Seyyedmohsen Hosseinibarkooie
- Institute of Human Genetics, University Hospital of Cologne, University Cologne, Kerpener Str. 34, 50931 Cologne, Germany; Center for Molecular Medicine Cologne, University of Cologne, 50931 Cologne, Germany; Institute for Genetics, University of Cologne, 50674 Cologne, Germany
| | - Julien Come
- INSERM/ UEVE UMR 861, Université Paris Saclay, I-STEM, 91100 Corbeil-Essonnes, France
| | - Cecile Martinat
- INSERM/ UEVE UMR 861, Université Paris Saclay, I-STEM, 91100 Corbeil-Essonnes, France
| | - Janine Altmüller
- Cologne Center for Genomics and West German Genome Center, University of Cologne, 50931 Cologne, Germany
| | - Brunhilde Wirth
- Institute of Human Genetics, University Hospital of Cologne, University Cologne, Kerpener Str. 34, 50931 Cologne, Germany; Center for Molecular Medicine Cologne, University of Cologne, 50931 Cologne, Germany; Institute for Genetics, University of Cologne, 50674 Cologne, Germany; Center for Rare Diseases, University Hospital of Cologne, 50931 Cologne, Germany.
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12
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Tsue AF, Kania EE, Lei DQ, Fields R, McGann CD, Hershberg E, Deng X, Kihiu M, Ong SE, Disteche CM, Kugel S, Beliveau BJ, Schweppe DK, Shechner DM. Oligonucleotide-directed proximity-interactome mapping (O-MAP): A unified method for discovering RNA-interacting proteins, transcripts and genomic loci in situ. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.19.524825. [PMID: 36711823 PMCID: PMC9882335 DOI: 10.1101/2023.01.19.524825] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Throughout biology, RNA molecules form complex networks of molecular interactions that are central to their function, but remain challenging to investigate. Here, we introduce Oligonucleotide-mediated proximity-interactome MAPping (O-MAP), a straightforward method for elucidating the biomolecules near an RNA of interest, within its native cellular context. O-MAP uses programmable oligonucleotide probes to deliver proximity-biotinylating enzymes to a target RNA, enabling nearby molecules to be enriched by streptavidin pulldown. O-MAP induces exceptionally precise RNA-localized in situ biotinylation, and unlike alternative methods it enables straightforward optimization of its targeting accuracy. Using the 47S pre-ribosomal RNA and long noncoding RNA Xist as models, we develop O-MAP workflows for unbiased discovery of RNA-proximal proteins, transcripts, and genomic loci. This revealed unexpected co-compartmentalization of Xist and other chromatin-regulatory RNAs and enabled systematic characterization of nucleolar-chromatin interactions across multiple cell lines. O-MAP is portable to cultured cells, organoids, and tissues, and to RNAs of various lengths, abundances, and sequence composition. And, O-MAP requires no genetic manipulation and uses exclusively off-the-shelf parts. We therefore anticipate its application to a broad array of RNA phenomena.
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13
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Grimm NB, Lee JT. Selective Xi reactivation and alternative methods to restore MECP2 function in Rett syndrome. Trends Genet 2022; 38:920-943. [PMID: 35248405 PMCID: PMC9915138 DOI: 10.1016/j.tig.2022.01.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Revised: 01/15/2022] [Accepted: 01/19/2022] [Indexed: 10/19/2022]
Abstract
The human X-chromosome harbors only 4% of our genome but carries over 20% of genes associated with intellectual disability. Given that they inherit only one X-chromosome, males are more frequently affected by X-linked neurodevelopmental genetic disorders than females. However, despite inheriting two X-chromosomes, females can also be affected because X-chromosome inactivation enables only one of two X-chromosomes to be expressed per cell. For Rett syndrome and similar X-linked disorders affecting females, disease-specific treatments have remained elusive. However, a cure may be found within their own cells because every sick cell carries a healthy copy of the affected gene on the inactive X (Xi). Therefore, selective Xi reactivation may be a viable approach that would address the root cause of various X-linked disorders. Here, we discuss Rett syndrome and compare current approaches in the pharmaceutical pipeline to restore MECP2 function. We then focus on Xi reactivation and review available methods, lessons learned, and future directions.
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Affiliation(s)
- Niklas-Benedikt Grimm
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA, USA; Department of Genetics, The Blavatnik Institute, Harvard Medical School, Boston, MA, USA; Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Barcelona, Spain; Universitat Pompeu Fabra (UPF), Barcelona, Spain
| | - Jeannie T Lee
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA, USA; Department of Genetics, The Blavatnik Institute, Harvard Medical School, Boston, MA, USA.
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14
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Bauer M, Payer B, Filion GJ. Causality in transcription and genome folding: Insights from X inactivation. Bioessays 2022; 44:e2200105. [PMID: 36028473 DOI: 10.1002/bies.202200105] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Revised: 08/11/2022] [Accepted: 08/14/2022] [Indexed: 11/10/2022]
Abstract
The spatial organization of genomes is becoming increasingly understood. In mammals, where it is most investigated, this organization ties in with transcription, so an important research objective is to understand whether gene activity is a cause or a consequence of genome folding in space. In this regard, the phenomena of X-chromosome inactivation and reactivation open a unique window of investigation because of the singularities of the inactive X chromosome. Here we focus on the cause-consequence nexus between genome conformation and transcription and explain how recent results about the structural changes associated with inactivation and reactivation of the X chromosome shed light on this problem.
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Affiliation(s)
- Moritz Bauer
- Oncode Institute, Hubrecht Institute-KNAW and University Medical Center Utrecht, Utrecht, The Netherlands
| | - Bernhard Payer
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Barcelona, Spain.,Universitat Pompeu Fabra (UPF), Barcelona, Spain
| | - Guillaume J Filion
- Dept. Biological Sciences, University of Toronto Scarborough, Toronto, ON, Canada
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15
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Fleck K, Raj R, Erceg J. The 3D genome landscape: Diverse chromosomal interactions and their functional implications. Front Cell Dev Biol 2022; 10:968145. [PMID: 36036013 PMCID: PMC9402908 DOI: 10.3389/fcell.2022.968145] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2022] [Accepted: 07/19/2022] [Indexed: 11/13/2022] Open
Abstract
Genome organization includes contacts both within a single chromosome and between distinct chromosomes. Thus, regulatory organization in the nucleus may include interplay of these two types of chromosomal interactions with genome activity. Emerging advances in omics and single-cell imaging technologies have allowed new insights into chromosomal contacts, including those of homologs and sister chromatids, and their significance to genome function. In this review, we highlight recent studies in this field and discuss their impact on understanding the principles of chromosome organization and associated functional implications in diverse cellular processes. Specifically, we describe the contributions of intra-chromosomal, inter-homolog, and inter-sister chromatid contacts to genome organization and gene expression.
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Affiliation(s)
- Katherine Fleck
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT, United States
| | - Romir Raj
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT, United States
| | - Jelena Erceg
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT, United States
- Institute for Systems Genomics, University of Connecticut, Storrs, CT, United States
- Department of Genetics and Genome Sciences, University of Connecticut Health Center, Farmington, CT, United States
- *Correspondence: Jelena Erceg,
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16
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Much C, Smallegan MJ, Hwang T, Hanson SD, Dumbović G, Rinn JL. Evolutionary divergence of Firre localization and expression. RNA (NEW YORK, N.Y.) 2022; 28:842-853. [PMID: 35304421 PMCID: PMC9074896 DOI: 10.1261/rna.079070.121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Accepted: 03/06/2022] [Indexed: 06/03/2023]
Abstract
Long noncoding RNAs (lncRNAs) are rapidly evolving and thus typically poorly conserved in their sequences. How these sequence differences affect the characteristics and potential functions of lncRNAs with shared synteny remains unclear. Here we show that the syntenically conserved lncRNA Firre displays distinct expression and localization patterns in human and mouse. Single molecule RNA FISH reveals that in a range of cell lines, mouse Firre (mFirre) is predominantly nuclear, while human FIRRE (hFIRRE) is distributed between the cytoplasm and nucleus. This localization pattern is maintained in human/mouse hybrid cells expressing both human and mouse Firre, implying that the localization of the lncRNA is species autonomous. We find that the majority of hFIRRE transcripts in the cytoplasm are comprised of isoforms that are enriched in RRD repeats. We furthermore determine that in various tissues, mFirre is more highly expressed than its human counterpart. Our data illustrate that the rapid evolution of syntenic lncRNAs can lead to variations in lncRNA localization and abundance, which in turn may result in disparate lncRNA functions even in closely related species.
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Affiliation(s)
- Christian Much
- BioFrontiers Institute, University of Colorado Boulder, Boulder, Colorado 80303, USA
| | - Michael J Smallegan
- BioFrontiers Institute, University of Colorado Boulder, Boulder, Colorado 80303, USA
- Department of Molecular, Cellular and Developmental Biology, University of Colorado Boulder, Boulder, Colorado 80302, USA
| | - Taeyoung Hwang
- BioFrontiers Institute, University of Colorado Boulder, Boulder, Colorado 80303, USA
| | - Skylar D Hanson
- BioFrontiers Institute, University of Colorado Boulder, Boulder, Colorado 80303, USA
| | - Gabrijela Dumbović
- BioFrontiers Institute, University of Colorado Boulder, Boulder, Colorado 80303, USA
- Institute for Cardiovascular Regeneration, Goethe University Frankfurt, 60596 Frankfurt am Main, Germany
| | - John L Rinn
- BioFrontiers Institute, University of Colorado Boulder, Boulder, Colorado 80303, USA
- Department of Biochemistry, University of Colorado Boulder, Boulder, Colorado 80302, USA
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17
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From genotype to phenotype: genetics of mammalian long non-coding RNAs in vivo. Nat Rev Genet 2022; 23:229-243. [PMID: 34837040 DOI: 10.1038/s41576-021-00427-8] [Citation(s) in RCA: 48] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/15/2021] [Indexed: 12/14/2022]
Abstract
Genome-wide sequencing has led to the discovery of thousands of long non-coding RNA (lncRNA) loci in the human genome, but evidence of functional significance has remained controversial for many lncRNAs. Genetically engineered model organisms are considered the gold standard for linking genotype to phenotype. Recent advances in CRISPR-Cas genome editing have led to a rapid increase in the use of mouse models to more readily survey lncRNAs for functional significance. Here, we review strategies to investigate the physiological relevance of lncRNA loci by highlighting studies that have used genetic mouse models to reveal key in vivo roles for lncRNAs, from fertility to brain development. We illustrate how an investigative approach, starting with whole-gene deletion followed by transcription termination and/or transgene rescue strategies, can provide definitive evidence for the in vivo function of mammalian lncRNAs.
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18
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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: 85] [Impact Index Per Article: 42.5] [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.
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19
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Bredemeyer KR, Seabury CM, Stickney MJ, McCarrey JR, vonHoldt BM, Murphy WJ. Rapid Macrosatellite Evolution Promotes X-Linked Hybrid Male Sterility in a Feline Interspecies Cross. Mol Biol Evol 2021; 38:5588-5609. [PMID: 34519828 PMCID: PMC8662614 DOI: 10.1093/molbev/msab274] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The sterility or inviability of hybrid offspring produced from an interspecific mating result from incompatibilities between parental genotypes that are thought to result from divergence of loci involved in epistatic interactions. However, attributes contributing to the rapid evolution of these regions also complicates their assembly, thus discovery of candidate hybrid sterility loci is difficult and has been restricted to a small number of model systems. Here we reported rapid interspecific divergence at the DXZ4 macrosatellite locus in an interspecific cross between two closely related mammalian species: the domestic cat (Felis silvestris catus) and the Jungle cat (Felis chaus). DXZ4 is an interesting candidate due to its structural complexity, copy number variability, and described role in the critical yet complex biological process of X-chromosome inactivation. However, the full structure of DXZ4 was absent or incomplete in nearly every available mammalian genome assembly given its repetitive complexity. We compared highly continuous genomes for three cat species, each containing a complete DXZ4 locus, and discovered that the felid DXZ4 locus differs substantially from the human ortholog, and that it varies in copy number between cat species. Additionally, we reported expression, methylation, and structural conformation profiles of DXZ4 and the X chromosome during stages of spermatogenesis that have been previously associated with hybrid male sterility. Collectively, these findings suggest a new role for DXZ4 in male meiosis and a mechanism for feline interspecific incompatibility through rapid satellite divergence.
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Affiliation(s)
- Kevin R Bredemeyer
- Veterinary Integrative Biosciences, Texas A&M University, College Station, TX, USA
- Interdisciplinary Program in Genetics and Genomics, Texas A&M University, College Station, TX, USA
| | | | - Mark J Stickney
- Veterinary Medical Teaching Hospital, Texas A&M University, College Station, TX, USA
| | - John R McCarrey
- Department of Biology, University of Texas at San Antonio, San Antonio, TX, USA
| | | | - William J Murphy
- Veterinary Integrative Biosciences, Texas A&M University, College Station, TX, USA
- Interdisciplinary Program in Genetics and Genomics, Texas A&M University, College Station, TX, USA
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20
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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.
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21
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Trigiante G, Blanes Ruiz N, Cerase A. Emerging Roles of Repetitive and Repeat-Containing RNA in Nuclear and Chromatin Organization and Gene Expression. Front Cell Dev Biol 2021; 9:735527. [PMID: 34722514 PMCID: PMC8552494 DOI: 10.3389/fcell.2021.735527] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Accepted: 09/09/2021] [Indexed: 12/14/2022] Open
Abstract
Genomic repeats have been intensely studied as regulatory elements controlling gene transcription, splicing and genome architecture. Our understanding of the role of the repetitive RNA such as the RNA coming from genomic repeats, or repetitive sequences embedded in mRNA/lncRNAs, in nuclear and cellular functions is instead still limited. In this review we discuss evidence supporting the multifaceted roles of repetitive RNA and RNA binding proteins in nuclear organization, gene regulation, and in the formation of dynamic membrane-less aggregates. We hope that our review will further stimulate research in the consolidating field of repetitive RNA biology.
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Affiliation(s)
| | | | - Andrea Cerase
- Centre for Genomics and Child Health, Barts and The London School of Medicine and Dentistry, Blizard Institute, Queen Mary University of London, London, United Kingdom
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22
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Bonora G, Ramani V, Singh R, Fang H, Jackson DL, Srivatsan S, Qiu R, Lee C, Trapnell C, Shendure J, Duan Z, Deng X, Noble WS, Disteche CM. Single-cell landscape of nuclear configuration and gene expression during stem cell differentiation and X inactivation. Genome Biol 2021; 22:279. [PMID: 34579774 PMCID: PMC8474932 DOI: 10.1186/s13059-021-02432-w] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Accepted: 07/07/2021] [Indexed: 11/25/2022] Open
Abstract
BACKGROUND Mammalian development is associated with extensive changes in gene expression, chromatin accessibility, and nuclear structure. Here, we follow such changes associated with mouse embryonic stem cell differentiation and X inactivation by integrating, for the first time, allele-specific data from these three modalities obtained by high-throughput single-cell RNA-seq, ATAC-seq, and Hi-C. RESULTS Allele-specific contact decay profiles obtained by single-cell Hi-C clearly show that the inactive X chromosome has a unique profile in differentiated cells that have undergone X inactivation. Loss of this inactive X-specific structure at mitosis is followed by its reappearance during the cell cycle, suggesting a "bookmark" mechanism. Differentiation of embryonic stem cells to follow the onset of X inactivation is associated with changes in contact decay profiles that occur in parallel on both the X chromosomes and autosomes. Single-cell RNA-seq and ATAC-seq show evidence of a delay in female versus male cells, due to the presence of two active X chromosomes at early stages of differentiation. The onset of the inactive X-specific structure in single cells occurs later than gene silencing, consistent with the idea that chromatin compaction is a late event of X inactivation. Single-cell Hi-C highlights evidence of discrete changes in nuclear structure characterized by the acquisition of very long-range contacts throughout the nucleus. Novel computational approaches allow for the effective alignment of single-cell gene expression, chromatin accessibility, and 3D chromosome structure. CONCLUSIONS Based on trajectory analyses, three distinct nuclear structure states are detected reflecting discrete and profound simultaneous changes not only to the structure of the X chromosomes, but also to that of autosomes during differentiation. Our study reveals that long-range structural changes to chromosomes appear as discrete events, unlike progressive changes in gene expression and chromatin accessibility.
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Affiliation(s)
- Giancarlo Bonora
- Department of Genome Sciences, University of Washington, Seattle, WA, USA
| | - Vijay Ramani
- Department of Biochemistry & Biophysics, University of California San Francisco, San Francisco, CA, USA
| | - Ritambhara Singh
- Department of Computer Science, Brown University, Providence, RI, USA
- Center for Computational Molecular Biology, Brown University, Providence, RI, USA
| | - He Fang
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA, USA
| | - Dana L Jackson
- Department of Genome Sciences, University of Washington, Seattle, WA, USA
| | - Sanjay Srivatsan
- Department of Genome Sciences, University of Washington, Seattle, WA, USA
| | - Ruolan Qiu
- Department of Genome Sciences, University of Washington, Seattle, WA, USA
| | - Choli Lee
- Department of Genome Sciences, University of Washington, Seattle, WA, USA
| | - Cole Trapnell
- Department of Genome Sciences, University of Washington, Seattle, WA, USA
- Brotman Baty Institute for Precision Medicine, Seattle, WA, USA
- Allen Discovery Center for Cell Lineage Tracing, Seattle, WA, USA
| | - Jay Shendure
- Department of Genome Sciences, University of Washington, Seattle, WA, USA
- Brotman Baty Institute for Precision Medicine, Seattle, WA, USA
- Allen Discovery Center for Cell Lineage Tracing, Seattle, WA, USA
- Howard Hughes Medical Institute, Seattle, WA, USA
| | - Zhijun Duan
- Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, USA
- Division of Hematology, Department of Medicine, University of Washington, Seattle, USA
| | - Xinxian Deng
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA, USA.
| | - William S Noble
- Department of Genome Sciences, University of Washington, Seattle, WA, USA.
- Paul G. Allen School of Computer Science and Engineering, University of Washington, Seattle, WA, USA.
| | - Christine M Disteche
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA, USA.
- Brotman Baty Institute for Precision Medicine, Seattle, WA, USA.
- Department of Medicine, University of Washington, Seattle, WA, USA.
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23
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Brashear WA, Bredemeyer KR, Murphy WJ. Genomic architecture constrained placental mammal X Chromosome evolution. Genome Res 2021; 31:1353-1365. [PMID: 34301625 PMCID: PMC8327908 DOI: 10.1101/gr.275274.121] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Accepted: 06/22/2021] [Indexed: 01/02/2023]
Abstract
Susumu Ohno proposed that the gene content of the mammalian X Chromosome should remain highly conserved due to dosage compensation. X Chromosome linkage (gene order) conservation is widespread in placental mammals but does not fall within the scope of Ohno's prediction and may be an indirect result of selection on gene content or selection against rearrangements that might disrupt X-Chromosome inactivation (XCI). Previous comparisons between the human and mouse X Chromosome sequences have suggested that although single-copy X Chromosome genes are conserved between species, most ampliconic genes were independently acquired. To better understand the evolutionary and functional constraints on X-linked gene content and linkage conservation in placental mammals, we aligned a new, high-quality, long-read X Chromosome reference assembly from the domestic cat (incorporating 19.3 Mb of targeted BAC clone sequence) to the pig, human, and mouse assemblies. A comprehensive analysis of annotated X-linked orthologs in public databases demonstrated that the majority of ampliconic gene families were present on the ancestral placental X Chromosome. We generated a domestic cat Hi-C contact map from an F1 domestic cat/Asian leopard cat hybrid and demonstrated the formation of the bipartite structure found in primate and rodent inactivated X Chromosomes. Conservation of gene order and recombination patterns is attributable to strong selective constraints on three-dimensional genomic architecture necessary for superloop formation. Species with rearranged X Chromosomes retain the ancestral order and relative spacing of loci critical for superloop formation during XCI, with compensatory inversions evolving to maintain these long-range physical interactions.
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Affiliation(s)
- Wesley A Brashear
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, Texas 77843, USA.,Interdisciplinary Program in Genetics, Texas A&M University, College Station, Texas 77843, USA
| | - Kevin R Bredemeyer
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, Texas 77843, USA.,Interdisciplinary Program in Genetics, Texas A&M University, College Station, Texas 77843, USA
| | - William J Murphy
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, Texas 77843, USA.,Interdisciplinary Program in Genetics, Texas A&M University, College Station, Texas 77843, USA
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24
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Li J, Lin Y, Tang Q, Li M. Understanding three-dimensional chromatin organization in diploid genomes. Comput Struct Biotechnol J 2021; 19:3589-3598. [PMID: 34257838 PMCID: PMC8246089 DOI: 10.1016/j.csbj.2021.06.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2021] [Revised: 06/11/2021] [Accepted: 06/12/2021] [Indexed: 11/17/2022] Open
Abstract
The three-dimensional (3D) organization of chromatin in the nucleus of diploid eukaryotic organisms has fascinated biologists for many years. Despite major progress in chromatin conformation studies, current knowledge regarding the spatial organization of diploid (maternal and paternal) genomes is still limited. Recent advances in Hi-C technology and data processing approaches have enabled construction of diploid Hi-C contact maps. These maps greatly accelerated the pace of novel discoveries in haplotype-resolved 3D genome studies, revealing the role of allele biased chromatin conformation in transcriptional regulation. Here, we review emerging concepts and haplotype phasing strategies of Hi-C data in 3D diploid genome studies. We discuss new insights on homologous chromosomal organization and the interplay between allelic biased chromatin architecture and several nuclear functions, explaining how haplotype-resolved Hi-C technologies have been used to resolve important biological questions.
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Affiliation(s)
- Jing Li
- Institute of Animal Genetics and Breeding, College of Animal Science and Technology, Sichuan Agricultural University, Chengdu 611130, China
| | - Yu Lin
- Institute of Animal Genetics and Breeding, College of Animal Science and Technology, Sichuan Agricultural University, Chengdu 611130, China
| | - Qianzi Tang
- Institute of Animal Genetics and Breeding, College of Animal Science and Technology, Sichuan Agricultural University, Chengdu 611130, China
| | - Mingzhou Li
- Institute of Animal Genetics and Breeding, College of Animal Science and Technology, Sichuan Agricultural University, Chengdu 611130, China
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Abstract
Mammalian cells equalize X-linked dosages between the male (XY) and female (XX) sexes by silencing one X chromosome in the female sex. This process, known as "X chromosome inactivation" (XCI), requires a master switch within the X inactivation center (Xic). The Xic spans several hundred kilobases in the mouse and includes a number of regulatory noncoding genes that produce functional transcripts. Over three decades, transgenic and deletional analyses have demonstrated both the necessity and sufficiency of the Xic to induce XCI, including the steps of X chromosome counting, choice, and initiation of whole-chromosome silencing. One recent study, however, reported that deleting the noncoding sequences of the Xic surprisingly had no effect for XCI and attributed a sufficiency to drive counting to the coding gene, Rnf12/Rlim Here, we revisit the question by creating independent Xic deletion cell lines. Multiple independent clones carrying heterozygous deletions of the Xic display an inability to up-regulate Xist expression, consistent with a counting defect. This defect is rescued by a second site mutation in Tsix occurring in trans, bypassing the defect in counting. These findings reaffirm the essential nature of noncoding Xic elements for the initiation of XCI.
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Chromosome compartments on the inactive X guide TAD formation independently of transcription during X-reactivation. Nat Commun 2021; 12:3499. [PMID: 34108480 PMCID: PMC8190187 DOI: 10.1038/s41467-021-23610-1] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Accepted: 05/10/2021] [Indexed: 12/21/2022] Open
Abstract
A hallmark of chromosome organization is the partition into transcriptionally active A and repressed B compartments, and into topologically associating domains (TADs). Both structures were regarded to be absent from the inactive mouse X chromosome, but to be re-established with transcriptional reactivation and chromatin opening during X-reactivation. Here, we combine a tailor-made mouse iPSC reprogramming system and high-resolution Hi-C to produce a time course combining gene reactivation, chromatin opening and chromosome topology during X-reactivation. Contrary to previous observations, we observe A/B-like compartments on the inactive X harbouring multiple subcompartments. While partial X-reactivation initiates within a compartment rich in X-inactivation escapees, it then occurs rapidly along the chromosome, concomitant with downregulation of Xist. Importantly, we find that TAD formation precedes transcription and initiates from Xist-poor compartments. Here, we show that TAD formation and transcriptional reactivation are causally independent during X-reactivation while establishing Xist as a common denominator.
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Abstract
We have known for decades that long noncoding RNAs (lncRNAs) can play essential functions across most forms of life. The maintenance of chromosome length requires an lncRNA (e.g., hTERC) and two lncRNAs in the ribosome that are required for protein synthesis. Thus, lncRNAs can represent powerful RNA machines. More recently, it has become clear that mammalian genomes encode thousands more lncRNAs. Thus, we raise the question: Which, if any, of these lncRNAs could also represent RNA-based machines? Here we synthesize studies that are beginning to address this question by investigating fundamental properties of lncRNA genes, revealing new insights into the RNA structure-function relationship, determining cis- and trans-acting lncRNAs in vivo, and generating new developments in high-throughput screening used to identify functional lncRNAs. Overall, these findings provide a context toward understanding the molecular grammar underlying lncRNA biology.
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Affiliation(s)
- John L Rinn
- BioFrontiers Institute, Department of Biochemistry, University of Colorado, Boulder, Colorado 80303, USA;
| | - Howard Y Chang
- Center for Personal Dynamic Regulomes, Stanford University, Stanford, California 94305, USA.,Howard Hughes Medical Institute, Stanford University, Stanford, California 94305, USA
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28
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Kriz AJ, Colognori D, Sunwoo H, Nabet B, Lee JT. Balancing cohesin eviction and retention prevents aberrant chromosomal interactions, Polycomb-mediated repression, and X-inactivation. Mol Cell 2021; 81:1970-1987.e9. [PMID: 33725485 PMCID: PMC8106664 DOI: 10.1016/j.molcel.2021.02.031] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2020] [Revised: 12/18/2020] [Accepted: 02/22/2021] [Indexed: 12/17/2022]
Abstract
Depletion of architectural factors globally alters chromatin structure but only modestly affects gene expression. We revisit the structure-function relationship using the inactive X chromosome (Xi) as a model. We investigate cohesin imbalances by forcing its depletion or retention using degron-tagged RAD21 (cohesin subunit) or WAPL (cohesin release factor). Cohesin loss disrupts the Xi superstructure, unveiling superloops between escapee genes with minimal effect on gene repression. By contrast, forced cohesin retention markedly affects Xi superstructure, compromises spreading of Xist RNA-Polycomb complexes, and attenuates Xi silencing. Effects are greatest at distal chromosomal ends, where looping contacts with the Xist locus are weakened. Surprisingly, cohesin loss creates an Xi superloop, and cohesin retention creates Xi megadomains on the active X chromosome. Across the genome, a proper cohesin balance protects against aberrant inter-chromosomal interactions and tempers Polycomb-mediated repression. We conclude that a balance of cohesin eviction and retention regulates X inactivation and inter-chromosomal interactions across the genome.
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Affiliation(s)
- Andrea J Kriz
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114, USA; Department of Genetics, Harvard Medical School, Boston, MA 02114, USA
| | - David Colognori
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114, USA; Department of Genetics, Harvard Medical School, Boston, MA 02114, USA
| | - Hongjae Sunwoo
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114, USA; Department of Genetics, Harvard Medical School, Boston, MA 02114, USA
| | - Behnam Nabet
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA; Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02115, USA
| | - Jeannie T Lee
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114, USA; Department of Genetics, Harvard Medical School, Boston, MA 02114, USA.
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29
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Abstract
Cancers and developmental disorders are associated with alterations in the 3D genome architecture in space and time (the fourth dimension). Mammalian 3D genome organization is complex and dynamic and plays an essential role in regulating gene expression and cellular function. To study the causal relationship between genome function and its spatio-temporal organization in the nucleus, new technologies for engineering and manipulating the 3D organization of the genome have been developed. In particular, CRISPR-Cas technologies allow programmable manipulation at specific genomic loci, enabling unparalleled opportunities in this emerging field of 3D genome engineering. We review advances in mammalian 3D genome engineering with a focus on recent manipulative technologies using CRISPR-Cas and related technologies.
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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: 4] [Impact Index Per Article: 1.3] [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.
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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
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31
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Wirth B. Spinal Muscular Atrophy: In the Challenge Lies a Solution. Trends Neurosci 2021; 44:306-322. [PMID: 33423791 DOI: 10.1016/j.tins.2020.11.009] [Citation(s) in RCA: 76] [Impact Index Per Article: 25.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2020] [Revised: 11/08/2020] [Accepted: 11/30/2020] [Indexed: 12/16/2022]
Abstract
The path from gene discovery to therapy in spinal muscular atrophy (SMA) has been a highly challenging endeavor, but also led to one of the most successful stories in neurogenetics. In SMA, a neuromuscular disorder with an often fatal outcome until recently, with those affected never able to sit, stand, or walk, children now achieve these motoric abilities and almost age-based development when treated presymptomatically. This review summarizes the challenges along this 30-year journey. It is also meant to inspire early-career scientists not to give up when things become difficult but to try to uncover the biological underpinnings and transform the challenge into the next big discovery. Without doubt, the improvements seen with the three therapeutic strategies in SMA are impressive; many open questions remain and are discussed in this review.
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Affiliation(s)
- Brunhilde Wirth
- Institute of Human Genetics, Center for Molecular Medicine, Center for Rare Disorders, University of Cologne, Kerpener Str. 34, 50931 Cologne, Germany.
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32
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Bizhanova A, Kaufman PD. Close to the edge: Heterochromatin at the nucleolar and nuclear peripheries. BIOCHIMICA ET BIOPHYSICA ACTA. GENE REGULATORY MECHANISMS 2021; 1864:194666. [PMID: 33307247 PMCID: PMC7855492 DOI: 10.1016/j.bbagrm.2020.194666] [Citation(s) in RCA: 46] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2020] [Revised: 11/11/2020] [Accepted: 11/29/2020] [Indexed: 02/06/2023]
Abstract
Chromatin is a dynamic structure composed of DNA, RNA, and proteins, regulating storage and expression of the genetic material in the nucleus. Heterochromatin plays a crucial role in driving the three-dimensional arrangement of the interphase genome, and in preserving genome stability by maintaining a subset of the genome in a silent state. Spatial genome organization contributes to normal patterns of gene function and expression, and is therefore of broad interest. Mammalian heterochromatin, the focus of this review, mainly localizes at the nuclear periphery, forming Lamina-associated domains (LADs), and at the nucleolar periphery, forming Nucleolus-associated domains (NADs). Together, these regions comprise approximately one-half of mammalian genomes, and most but not all loci within these domains are stochastically placed at either of these two locations after exit from mitosis at each cell cycle. Excitement about the role of these heterochromatic domains in early development has recently been heightened by the discovery that LADs appear at some loci in the preimplantation mouse embryo prior to other chromosomal features like compartmental identity and topologically-associated domains (TADs). While LADs have been extensively studied and mapped during cellular differentiation and early embryonic development, NADs have been less thoroughly studied. Here, we summarize pioneering studies of NADs and LADs, more recent advances in our understanding of cis/trans-acting factors that mediate these localizations, and discuss the functional significance of these associations.
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Affiliation(s)
- Aizhan Bizhanova
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Paul D Kaufman
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Medical School, Worcester, MA 01605, USA.
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Raznahan A, Disteche CM. X-chromosome regulation and sex differences in brain anatomy. Neurosci Biobehav Rev 2021; 120:28-47. [PMID: 33171144 PMCID: PMC7855816 DOI: 10.1016/j.neubiorev.2020.10.024] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2020] [Revised: 10/13/2020] [Accepted: 10/20/2020] [Indexed: 01/08/2023]
Abstract
Humans show reproducible sex-differences in cognition and psychopathology that may be contributed to by influences of gonadal sex-steroids and/or sex-chromosomes on regional brain development. Gonadal sex-steroids are well known to play a major role in sexual differentiation of the vertebrate brain, but far less is known regarding the role of sex-chromosomes. Our review focuses on this latter issue by bridging together two literatures that have to date been largely disconnected. We first consider "bottom-up" genetic and molecular studies focused on sex-chromosome gene content and regulation. This literature nominates specific sex-chromosome genes that could drive developmental sex-differences by virtue of their sex-biased expression and their functions within the brain. We then consider the complementary "top down" view, from magnetic resonance imaging studies that map sex- and sex chromosome effects on regional brain anatomy, and link these maps to regional gene-expression within the brain. By connecting these top-down and bottom-up approaches, we emphasize the potential role of X-linked genes in driving sex-biased brain development and outline key goals for future work in this field.
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Affiliation(s)
- Armin Raznahan
- Section on Developmental Neurogenomics, Human Genetics Branch, National Institute of Mental Health, Bethesda, MD, 20892, USA.
| | - Christine M Disteche
- Department of Pathology and Medicine, University of Washington, Seattle, WA 98195, USA.
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34
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Ye T, Ma W. ASHIC: hierarchical Bayesian modeling of diploid chromatin contacts and structures. Nucleic Acids Res 2020; 48:e123. [PMID: 33074315 PMCID: PMC7708071 DOI: 10.1093/nar/gkaa872] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2020] [Revised: 09/15/2020] [Accepted: 09/24/2020] [Indexed: 12/29/2022] Open
Abstract
The recently developed Hi-C technique has been widely applied to map genome-wide chromatin interactions. However, current methods for analyzing diploid Hi-C data cannot fully distinguish between homologous chromosomes. Consequently, the existing diploid Hi-C analyses are based on sparse and inaccurate allele-specific contact matrices, which might lead to incorrect modeling of diploid genome architecture. Here we present ASHIC, a hierarchical Bayesian framework to model allele-specific chromatin organizations in diploid genomes. We developed two models under the Bayesian framework: the Poisson-multinomial (ASHIC-PM) model and the zero-inflated Poisson-multinomial (ASHIC-ZIPM) model. The proposed ASHIC methods impute allele-specific contact maps from diploid Hi-C data and simultaneously infer allelic 3D structures. Through simulation studies, we demonstrated that ASHIC methods outperformed existing approaches, especially under low coverage and low SNP density conditions. Additionally, in the analyses of diploid Hi-C datasets in mouse and human, our ASHIC-ZIPM method produced fine-resolution diploid chromatin maps and 3D structures and provided insights into the allelic chromatin organizations and functions. To summarize, our work provides a statistically rigorous framework for investigating fine-scale allele-specific chromatin conformations. The ASHIC software is publicly available at https://github.com/wmalab/ASHIC.
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Affiliation(s)
- Tiantian Ye
- Genetics, Genomics and Bioinformatics Program
| | - Wenxiu Ma
- Department of Statistics, University of California Riverside, Riverside, CA 92521, USA
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35
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Fang H, Bonora G, Lewandowski JP, Thakur J, Filippova GN, Henikoff S, Shendure J, Duan Z, Rinn JL, Deng X, Noble WS, Disteche CM. Trans- and cis-acting effects of Firre on epigenetic features of the inactive X chromosome. Nat Commun 2020; 11:6053. [PMID: 33247132 PMCID: PMC7695720 DOI: 10.1038/s41467-020-19879-3] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2019] [Accepted: 10/28/2020] [Indexed: 12/12/2022] Open
Abstract
Firre encodes a lncRNA involved in nuclear organization. Here, we show that Firre RNA expressed from the active X chromosome maintains histone H3K27me3 enrichment on the inactive X chromosome (Xi) in somatic cells. This trans-acting effect involves SUZ12, reflecting interactions between Firre RNA and components of the Polycomb repressive complexes. Without Firre RNA, H3K27me3 decreases on the Xi and the Xi-perinucleolar location is disrupted, possibly due to decreased CTCF binding on the Xi. We also observe widespread gene dysregulation, but not on the Xi. These effects are measurably rescued by ectopic expression of mouse or human Firre/FIRRE transgenes, supporting conserved trans-acting roles. We also find that the compact 3D structure of the Xi partly depends on the Firre locus and its RNA. In common lymphoid progenitors and T-cells Firre exerts a cis-acting effect on maintenance of H3K27me3 in a 26 Mb region around the locus, demonstrating cell type-specific trans- and cis-acting roles of this lncRNA.
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Affiliation(s)
- He Fang
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA, USA
| | - Giancarlo Bonora
- Department of Genome Sciences, University of Washington, Seattle, WA, USA
| | - Jordan P Lewandowski
- Department of Stem Cell and Regenerative Biology, Harvard University, Boston, MA, USA
| | | | - Galina N Filippova
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA, USA
| | | | - Jay Shendure
- Department of Genome Sciences, University of Washington, Seattle, WA, USA
| | - Zhijun Duan
- Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA, USA
- Division of Hematology, Department of Medicine, University of Washington, Seattle, WA, USA
| | - John L Rinn
- Department of Biochemistry, University of Colorado at Boulder, Boulder, CO, USA
| | - Xinxian Deng
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA, USA.
| | - William S Noble
- Department of Genome Sciences, University of Washington, Seattle, WA, USA.
- Paul G. Allen School of Computer Science and Engineering, University of Washington, Seattle, WA, USA.
| | - Christine M Disteche
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA, USA.
- Department of Medicine, University of Washington, Seattle, WA, USA.
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36
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Wu Q, Liu P, Wang L. Many facades of CTCF unified by its coding for three-dimensional genome architecture. J Genet Genomics 2020; 47:407-424. [PMID: 33187878 DOI: 10.1016/j.jgg.2020.06.008] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Revised: 04/15/2020] [Accepted: 06/01/2020] [Indexed: 02/06/2023]
Abstract
CCCTC-binding factor (CTCF) is a multifunctional zinc finger protein that is conserved in metazoan species. CTCF is consistently found to play an important role in many diverse biological processes. CTCF/cohesin-mediated active chromatin 'loop extrusion' architects three-dimensional (3D) genome folding. The 3D architectural role of CTCF underlies its multifarious functions, including developmental regulation of gene expression, protocadherin (Pcdh) promoter choice in the nervous system, immunoglobulin (Ig) and T-cell receptor (Tcr) V(D)J recombination in the immune system, homeobox (Hox) gene control during limb development, as well as many other aspects of biology. Here, we review the pleiotropic functions of CTCF from the perspective of its essential role in 3D genome architecture and topological promoter/enhancer selection. We envision the 3D genome as an enormous complex architecture, with tens of thousands of CTCF sites as connecting nodes and CTCF proteins as mysterious bonds that glue together genomic building parts with distinct articulation joints. In particular, we focus on the internal mechanisms by which CTCF controls higher order chromatin structures that manifest its many façades of physiological and pathological functions. We also discuss the dichotomic role of CTCF sites as intriguing 3D genome nodes for seemingly contradictory 'looping bridges' and 'topological insulators' to frame a beautiful magnificent house for a cell's nuclear home.
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Affiliation(s)
- Qiang Wu
- MOE Key Lab of Systems Biomedicine, State Key Laboratory of Oncogenes and Related Genes, Center for Comparative Biomedicine, Institute of Systems Biomedicine, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University (SJTU), Shanghai, 200240, China.
| | - Peifeng Liu
- MOE Key Lab of Systems Biomedicine, State Key Laboratory of Oncogenes and Related Genes, Center for Comparative Biomedicine, Institute of Systems Biomedicine, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University (SJTU), Shanghai, 200240, China
| | - Leyang Wang
- MOE Key Lab of Systems Biomedicine, State Key Laboratory of Oncogenes and Related Genes, Center for Comparative Biomedicine, Institute of Systems Biomedicine, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University (SJTU), Shanghai, 200240, China
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37
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Bansal P, Kondaveeti Y, Pinter SF. Forged by DXZ4, FIRRE, and ICCE: How Tandem Repeats Shape the Active and Inactive X Chromosome. Front Cell Dev Biol 2020; 7:328. [PMID: 32076600 PMCID: PMC6985041 DOI: 10.3389/fcell.2019.00328] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2019] [Accepted: 11/26/2019] [Indexed: 12/11/2022] Open
Abstract
Recent efforts in mapping spatial genome organization have revealed three evocative and conserved structural features of the inactive X in female mammals. First, the chromosomal conformation of the inactive X reveals a loss of topologically associated domains (TADs) present on the active X. Second, the macrosatellite DXZ4 emerges as a singular boundary that suppresses physical interactions between two large TAD-depleted "megadomains." Third, DXZ4 reaches across several megabases to form "superloops" with two other X-linked tandem repeats, FIRRE and ICCE, which also loop to each other. Although all three structural features are conserved across rodents and primates, deletion of mouse and human orthologs of DXZ4 and FIRRE from the inactive X have revealed limited impact on X chromosome inactivation (XCI) and escape in vitro. In contrast, loss of Xist or SMCHD1 have been shown to impair TAD erasure and gene silencing on the inactive X. In this perspective, we summarize these results in the context of new research describing disruption of X-linked tandem repeats in vivo, and discuss their possible molecular roles through the lens of evolutionary conservation and clinical genetics. As a null hypothesis, we consider whether the conservation of some structural features on the inactive X may reflect selection for X-linked tandem repeats on account of necessary cis- and trans-regulatory roles they may play on the active X, rather than the inactive X. Additional hypotheses invoking a role for X-linked tandem repeats on X reactivation, for example in the germline or totipotency, remain to be assessed in multiple developmental models spanning mammalian evolution.
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Affiliation(s)
- Prakhar Bansal
- Department of Genetics and Genome Sciences, School of Medicine, UCONN Health, University of Connecticut, Farmington, CT, United States
- Institute for Systems Genomics, University of Connecticut, Farmington, CT, United States
| | - Yuvabharath Kondaveeti
- Department of Genetics and Genome Sciences, School of Medicine, UCONN Health, University of Connecticut, Farmington, CT, United States
- Institute for Systems Genomics, University of Connecticut, Farmington, CT, United States
| | - Stefan F. Pinter
- Department of Genetics and Genome Sciences, School of Medicine, UCONN Health, University of Connecticut, Farmington, CT, United States
- Institute for Systems Genomics, University of Connecticut, Farmington, CT, United States
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38
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Llères D, Moindrot B, Pathak R, Piras V, Matelot M, Pignard B, Marchand A, Poncelet M, Perrin A, Tellier V, Feil R, Noordermeer D. CTCF modulates allele-specific sub-TAD organization and imprinted gene activity at the mouse Dlk1-Dio3 and Igf2-H19 domains. Genome Biol 2019; 20:272. [PMID: 31831055 PMCID: PMC6909504 DOI: 10.1186/s13059-019-1896-8] [Citation(s) in RCA: 53] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2019] [Accepted: 11/22/2019] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND Genomic imprinting is essential for mammalian development and provides a unique paradigm to explore intra-cellular differences in chromatin configuration. So far, the detailed allele-specific chromatin organization of imprinted gene domains has mostly been lacking. Here, we explored the chromatin structure of the two conserved imprinted domains controlled by paternal DNA methylation imprints-the Igf2-H19 and Dlk1-Dio3 domains-and assessed the involvement of the insulator protein CTCF in mouse cells. RESULTS Both imprinted domains are located within overarching topologically associating domains (TADs) that are similar on both parental chromosomes. At each domain, a single differentially methylated region is bound by CTCF on the maternal chromosome only, in addition to multiple instances of bi-allelic CTCF binding. Combinations of allelic 4C-seq and DNA-FISH revealed that bi-allelic CTCF binding alone, on the paternal chromosome, correlates with a first level of sub-TAD structure. On the maternal chromosome, additional CTCF binding at the differentially methylated region adds a further layer of sub-TAD organization, which essentially hijacks the existing paternal-specific sub-TAD organization. Perturbation of maternal-specific CTCF binding site at the Dlk1-Dio3 locus, using genome editing, results in perturbed sub-TAD organization and bi-allelic Dlk1 activation during differentiation. CONCLUSIONS Maternal allele-specific CTCF binding at the imprinted Igf2-H19 and the Dlk1-Dio3 domains adds an additional layer of sub-TAD organization, on top of an existing three-dimensional configuration and prior to imprinted activation of protein-coding genes. We speculate that this allele-specific sub-TAD organization provides an instructive or permissive context for imprinted gene activation during development.
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Affiliation(s)
- David Llères
- Institute of Molecular Genetics of Montpellier (IGMM), University of Montpellier, CNRS, Montpellier, France
| | - Benoît Moindrot
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, University Paris-sud and University Paris-Saclay, Gif-sur-Yvette, France
| | - Rakesh Pathak
- Institute of Molecular Genetics of Montpellier (IGMM), University of Montpellier, CNRS, Montpellier, France
| | - Vincent Piras
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, University Paris-sud and University Paris-Saclay, Gif-sur-Yvette, France
| | - Mélody Matelot
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, University Paris-sud and University Paris-Saclay, Gif-sur-Yvette, France
| | - Benoît Pignard
- Institute of Molecular Genetics of Montpellier (IGMM), University of Montpellier, CNRS, Montpellier, France
| | - Alice Marchand
- Institute of Molecular Genetics of Montpellier (IGMM), University of Montpellier, CNRS, Montpellier, France
| | - Mallory Poncelet
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, University Paris-sud and University Paris-Saclay, Gif-sur-Yvette, France
| | - Aurélien Perrin
- Institute of Molecular Genetics of Montpellier (IGMM), University of Montpellier, CNRS, Montpellier, France
| | - Virgile Tellier
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, University Paris-sud and University Paris-Saclay, Gif-sur-Yvette, France
| | - Robert Feil
- Institute of Molecular Genetics of Montpellier (IGMM), University of Montpellier, CNRS, Montpellier, France.
| | - Daan Noordermeer
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, University Paris-sud and University Paris-Saclay, Gif-sur-Yvette, France.
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39
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Andergassen D, Smith ZD, Lewandowski JP, Gerhardinger C, Meissner A, Rinn JL. In vivo Firre and Dxz4 deletion elucidates roles for autosomal gene regulation. eLife 2019; 8:e47214. [PMID: 31738164 PMCID: PMC6860989 DOI: 10.7554/elife.47214] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2019] [Accepted: 10/30/2019] [Indexed: 12/12/2022] Open
Abstract
Recent evidence has determined that the conserved X chromosome mega-structures controlled by the Firre and Dxz4 loci are not required for X chromosome inactivation (XCI) in cell lines. Here, we examined the in vivo contribution of these loci by generating mice carrying a single or double deletion of Firre and Dxz4. We found that these mutants are viable, fertile and show no defect in random or imprinted XCI. However, the lack of these elements results in many dysregulated genes on autosomes in an organ-specific manner. By comparing the dysregulated genes between the single and double deletion, we identified superloop, megadomain, and Firre locus-dependent gene sets. The largest transcriptional effect was observed in all strains lacking the Firre locus, indicating that this locus is the main driver for these autosomal expression signatures. Collectively, these findings suggest that these X-linked loci are involved in autosomal gene regulation rather than XCI biology.
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Affiliation(s)
- Daniel Andergassen
- Department of Stem Cell and Regenerative BiologyHarvard UniversityCambridgeUnited States
| | - Zachary D Smith
- Department of Stem Cell and Regenerative BiologyHarvard UniversityCambridgeUnited States
| | - Jordan P Lewandowski
- Department of Stem Cell and Regenerative BiologyHarvard UniversityCambridgeUnited States
| | - Chiara Gerhardinger
- Department of Stem Cell and Regenerative BiologyHarvard UniversityCambridgeUnited States
| | - Alexander Meissner
- Department of Stem Cell and Regenerative BiologyHarvard UniversityCambridgeUnited States
- Department of Genome RegulationMax Planck Institute for Molecular GeneticsBerlinGermany
| | - John L Rinn
- Department of BiochemistryUniversity of Colorado BoulderBoulderUnited States
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40
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Erceg J, AlHaj Abed J, Goloborodko A, Lajoie BR, Fudenberg G, Abdennur N, Imakaev M, McCole RB, Nguyen SC, Saylor W, Joyce EF, Senaratne TN, Hannan MA, Nir G, Dekker J, Mirny LA, Wu CT. The genome-wide multi-layered architecture of chromosome pairing in early Drosophila embryos. Nat Commun 2019; 10:4486. [PMID: 31582744 PMCID: PMC6776651 DOI: 10.1038/s41467-019-12211-8] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2019] [Accepted: 08/27/2019] [Indexed: 12/13/2022] Open
Abstract
Genome organization involves cis and trans chromosomal interactions, both implicated in gene regulation, development, and disease. Here, we focus on trans interactions in Drosophila, where homologous chromosomes are paired in somatic cells from embryogenesis through adulthood. We first address long-standing questions regarding the structure of embryonic homolog pairing and, to this end, develop a haplotype-resolved Hi-C approach to minimize homolog misassignment and thus robustly distinguish trans-homolog from cis contacts. This computational approach, which we call Ohm, reveals pairing to be surprisingly structured genome-wide, with trans-homolog domains, compartments, and interaction peaks, many coinciding with analogous cis features. We also find a significant genome-wide correlation between pairing, transcription during zygotic genome activation, and binding of the pioneer factor Zelda. Our findings reveal a complex, highly structured organization underlying homolog pairing, first discovered a century ago in Drosophila. Finally, we demonstrate the versatility of our haplotype-resolved approach by applying it to mammalian embryos.
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Affiliation(s)
- Jelena Erceg
- Department of Genetics, Harvard Medical School, Boston, MA, 02115, USA
| | - Jumana AlHaj Abed
- Department of Genetics, Harvard Medical School, Boston, MA, 02115, USA
| | - Anton Goloborodko
- Institute for Medical Engineering and Science, Massachusetts Institute of Technology (MIT), Cambridge, MA, 02139, USA
| | - Bryan R Lajoie
- Howard Hughes Medical Institute and Program in Systems Biology, Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA, 01605-0103, USA
- Illumina, San Diego, CA, USA
| | - Geoffrey Fudenberg
- Institute for Medical Engineering and Science, Massachusetts Institute of Technology (MIT), Cambridge, MA, 02139, USA
- Gladstone Institutes of Data Science and Biotechnology, San Francisco, CA, 94158, USA
| | - Nezar Abdennur
- Institute for Medical Engineering and Science, Massachusetts Institute of Technology (MIT), Cambridge, MA, 02139, USA
| | - Maxim Imakaev
- Institute for Medical Engineering and Science, Massachusetts Institute of Technology (MIT), Cambridge, MA, 02139, USA
| | - Ruth B McCole
- Department of Genetics, Harvard Medical School, Boston, MA, 02115, USA
| | - Son C Nguyen
- Department of Genetics, Harvard Medical School, Boston, MA, 02115, USA
- Department of Genetics, Penn Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104-6145, USA
| | - Wren Saylor
- Department of Genetics, Harvard Medical School, Boston, MA, 02115, USA
| | - Eric F Joyce
- Department of Genetics, Harvard Medical School, Boston, MA, 02115, USA
- Department of Genetics, Penn Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104-6145, USA
| | - T Niroshini Senaratne
- Department of Genetics, Harvard Medical School, Boston, MA, 02115, USA
- Department of Pathology and Laboratory Medicine, David Geffen School of Medicine, University of California, Los Angeles, CA, 90095, USA
| | - Mohammed A Hannan
- Department of Genetics, Harvard Medical School, Boston, MA, 02115, USA
| | - Guy Nir
- Department of Genetics, Harvard Medical School, Boston, MA, 02115, USA
| | - Job Dekker
- Howard Hughes Medical Institute and Program in Systems Biology, Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA, 01605-0103, USA
| | - Leonid A Mirny
- Institute for Medical Engineering and Science, Massachusetts Institute of Technology (MIT), Cambridge, MA, 02139, USA.
- Department of Physics, Massachusetts Institute of Technology (MIT), Cambridge, MA, 02139, USA.
| | - C-Ting Wu
- Department of Genetics, Harvard Medical School, Boston, MA, 02115, USA.
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA, 02115, USA.
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41
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Fang H, Disteche CM, Berletch JB. X Inactivation and Escape: Epigenetic and Structural Features. Front Cell Dev Biol 2019; 7:219. [PMID: 31632970 PMCID: PMC6779695 DOI: 10.3389/fcell.2019.00219] [Citation(s) in RCA: 79] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Accepted: 09/18/2019] [Indexed: 12/27/2022] Open
Abstract
X inactivation represents a complex multi-layer epigenetic mechanism that profoundly modifies chromatin composition and structure of one X chromosome in females. The heterochromatic inactive X chromosome adopts a unique 3D bipartite structure and a location close to the nuclear periphery or the nucleolus. X-linked lncRNA loci and their transcripts play important roles in the recruitment of proteins that catalyze chromatin and DNA modifications for silencing, as well as in the control of chromatin condensation and location of the inactive X chromosome. A subset of genes escapes X inactivation, raising questions about mechanisms that preserve their expression despite being embedded within heterochromatin. Escape gene expression differs between males and females, which can lead to physiological sex differences. We review recent studies that emphasize challenges in understanding the role of lncRNAs in the control of epigenetic modifications, structural features and nuclear positioning of the inactive X chromosome. Second, we highlight new findings about the distribution of genes that escape X inactivation based on single cell studies, and discuss the roles of escape genes in eliciting sex differences in health and disease.
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Affiliation(s)
- He Fang
- Department of Pathology, University of Washington, Seattle, WA, United States
| | - Christine M. Disteche
- Department of Pathology, University of Washington, Seattle, WA, United States
- Department of Medicine, University of Washington, Seattle, WA, United States
| | - Joel B. Berletch
- Department of Pathology, University of Washington, Seattle, WA, United States
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42
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High-Throughput Single-Cell Sequencing with Linear Amplification. Mol Cell 2019; 76:676-690.e10. [PMID: 31495564 DOI: 10.1016/j.molcel.2019.08.002] [Citation(s) in RCA: 60] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2018] [Revised: 05/22/2019] [Accepted: 08/01/2019] [Indexed: 11/22/2022]
Abstract
Conventional methods for single-cell genome sequencing are limited with respect to uniformity and throughput. Here, we describe sci-L3, a single-cell sequencing method that combines combinatorial indexing (sci-) and linear (L) amplification. The sci-L3 method adopts a 3-level (3) indexing scheme that minimizes amplification biases while enabling exponential gains in throughput. We demonstrate the generalizability of sci-L3 with proof-of-concept demonstrations of single-cell whole-genome sequencing (sci-L3-WGS), targeted sequencing (sci-L3-target-seq), and a co-assay of the genome and transcriptome (sci-L3-RNA/DNA). We apply sci-L3-WGS to profile the genomes of >10,000 sperm and sperm precursors from F1 hybrid mice, mapping 86,786 crossovers and characterizing rare chromosome mis-segregation events in meiosis, including instances of whole-genome equational chromosome segregation. We anticipate that sci-L3 assays can be applied to fully characterize recombination landscapes, to couple CRISPR perturbations and measurements of genome stability, and to other goals requiring high-throughput, high-coverage single-cell sequencing.
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43
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Wang CY, Colognori D, Sunwoo H, Wang D, Lee JT. PRC1 collaborates with SMCHD1 to fold the X-chromosome and spread Xist RNA between chromosome compartments. Nat Commun 2019; 10:2950. [PMID: 31270318 PMCID: PMC6610634 DOI: 10.1038/s41467-019-10755-3] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Accepted: 05/27/2019] [Indexed: 12/21/2022] Open
Abstract
X-chromosome inactivation triggers fusion of A/B compartments to inactive X (Xi)-specific structures known as S1 and S2 compartments. SMCHD1 then merges S1/S2s to form the Xi super-structure. Here, we ask how S1/S2 compartments form and reveal that Xist RNA drives their formation via recruitment of Polycomb repressive complex 1 (PRC1). Ablating Smchd1 in post-XCI cells unveils S1/S2 structures. Loss of SMCHD1 leads to trapping Xist in the S1 compartment, impairing RNA spreading into S2. On the other hand, depleting Xist, PRC1, or HNRNPK precludes re-emergence of S1/S2 structures, and loss of S1/S2 compartments paradoxically strengthens the partition between Xi megadomains. Finally, Xi-reactivation in post-XCI cells can be enhanced by depleting both SMCHD1 and DNA methylation. We conclude that Xist, PRC1, and SMCHD1 collaborate in an obligatory, sequential manner to partition, fuse, and direct self-association of Xi compartments required for proper spreading of Xist RNA. The inactive X (Xi)-specific S1/S2 chromosome compartments are merged by SMCHD1, but how the S1/S2 structure is constructed is unclear. The authors find that PRC1 drives the formation of S1/S2s and that the stepwise folding process of the Xi facilitates Xist RNA spreading between Xi compartments.
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Affiliation(s)
- Chen-Yu Wang
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA, USA.,Department of Genetics, The Blavatnik Institute, Harvard Medical School, Boston, MA, USA
| | - David Colognori
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA, USA.,Department of Genetics, The Blavatnik Institute, Harvard Medical School, Boston, MA, USA
| | - Hongjae Sunwoo
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA, USA.,Department of Genetics, The Blavatnik Institute, Harvard Medical School, Boston, MA, USA
| | - Danni Wang
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA, USA.,Department of Genetics, The Blavatnik Institute, Harvard Medical School, Boston, MA, USA
| | - Jeannie T Lee
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA, USA. .,Department of Genetics, The Blavatnik Institute, Harvard Medical School, Boston, MA, USA.
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44
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Megadomains and superloops form dynamically but are dispensable for X-chromosome inactivation and gene escape. Nat Commun 2018; 9:5004. [PMID: 30479398 PMCID: PMC6258728 DOI: 10.1038/s41467-018-07446-w] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2017] [Accepted: 10/24/2018] [Indexed: 01/17/2023] Open
Abstract
The mammalian inactive X-chromosome (Xi) is structurally distinct from all other chromosomes and serves as a model for how the 3D genome is organized. The Xi shows weakened topologically associated domains and is instead organized into megadomains and superloops directed by the noncoding loci, Dxz4 and Firre. Their functional significance is presently unclear, though one study suggests that they permit Xi genes to escape silencing. Here, we find that megadomains do not precede Xist expression or Xi gene silencing. Deleting Dxz4 disrupts the sharp megadomain border, whereas deleting Firre weakens intra-megadomain interactions. However, deleting Dxz4 and/or Firre has no impact on Xi silencing and gene escape. Nor does it affect Xi nuclear localization, stability, or H3K27 methylation. Additionally, ectopic integration of Dxz4 and Xist is not sufficient to form megadomains on autosomes. We conclude that Dxz4 and megadomains are dispensable for Xi silencing and escape from X-inactivation. The mammalian inactive X-chromosome (Xi) is organized into megadomains and superloops directed by the noncoding loci, Dxz4 and Firre. Here the authors provide evidence that megadomains do not precede Xist expression or Xi gene silencing, and suggest that Dxz4, Firre, and megadomains are dispensable for Xi silencing and escape from X-inactivation.
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45
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Westervelt N, Chadwick BP. Characterization of the ICCE Repeat in Mammals Reveals an Evolutionary Relationship with the DXZ4 Macrosatellite through Conserved CTCF Binding Motifs. Genome Biol Evol 2018; 10:2190-2204. [PMID: 30102341 PMCID: PMC6125249 DOI: 10.1093/gbe/evy176] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/07/2018] [Indexed: 12/16/2022] Open
Abstract
Appreciation is growing for how chromosomes are organized in three-dimensional space at interphase. Microscopic and high throughput sequence-based studies have established that the mammalian inactive X chromosome (Xi) adopts an alternate conformation relative to the active X chromosome. The Xi is organized into several multi-megabase chromatin loops called superloops. At the base of these loops are superloop anchors, and in humans three of these anchors are composed of large tandem repeat DNA that include DXZ4, Functional Intergenic Repeating RNA Element, and Inactive-X CTCF-binding Contact Element (ICCE). Each repeat contains a high density of binding sites for the architectural organization protein CCCTC-binding factor (CTCF) which exclusively associates with the Xi allele in normal cells. Removal of DXZ4 from the Xi compromises proper folding of the chromosome. In this study, we report the characterization of the ICCE tandem repeat, for which very little is known. ICCE is embedded within an intron of the Nobody (NBDY) gene locus at Xp11.21. We find that primary DNA sequence conservation of ICCE is only retained in higher primates, but that ICCE orthologs exist beyond the primate lineage. Like DXZ4, what is conserved is organization of the underlying DNA into a large tandem repeat, physical location within the NBDY locus and conservation of short DNA sequences corresponding to specific CTCF and Yin Yang 1 binding motifs that correlate with female-specific DNA hypomethylation. Unlike DXZ4, ICCE is not common to all eutherian mammals. Analysis of certain ICCE CTCF motifs reveal striking similarity with the DXZ4 motif and support an evolutionary relationship between DXZ4 and ICCE.
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Affiliation(s)
- Natalia Westervelt
- Department of Biological Science, Florida State University, King Life Science Building
| | - Brian P Chadwick
- Department of Biological Science, Florida State University, King Life Science Building
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46
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Ma W, Ay F, Lee C, Gulsoy G, Deng X, Cook S, Hesson J, Cavanaugh C, Ware CB, Krumm A, Shendure J, Blau CA, Disteche CM, Noble WS, Duan Z. Using DNase Hi-C techniques to map global and local three-dimensional genome architecture at high resolution. Methods 2018; 142:59-73. [PMID: 29382556 PMCID: PMC5993575 DOI: 10.1016/j.ymeth.2018.01.014] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2017] [Revised: 12/14/2017] [Accepted: 01/25/2018] [Indexed: 01/09/2023] Open
Abstract
The folding and three-dimensional (3D) organization of chromatin in the nucleus critically impacts genome function. The past decade has witnessed rapid advances in genomic tools for delineating 3D genome architecture. Among them, chromosome conformation capture (3C)-based methods such as Hi-C are the most widely used techniques for mapping chromatin interactions. However, traditional Hi-C protocols rely on restriction enzymes (REs) to fragment chromatin and are therefore limited in resolution. We recently developed DNase Hi-C for mapping 3D genome organization, which uses DNase I for chromatin fragmentation. DNase Hi-C overcomes RE-related limitations associated with traditional Hi-C methods, leading to improved methodological resolution. Furthermore, combining this method with DNA capture technology provides a high-throughput approach (targeted DNase Hi-C) that allows for mapping fine-scale chromatin architecture at exceptionally high resolution. Hence, targeted DNase Hi-C will be valuable for delineating the physical landscapes of cis-regulatory networks that control gene expression and for characterizing phenotype-associated chromatin 3D signatures. Here, we provide a detailed description of method design and step-by-step working protocols for these two methods.
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Affiliation(s)
- Wenxiu Ma
- Department of Genome Sciences, University of Washington, USA
| | - Ferhat Ay
- Department of Genome Sciences, University of Washington, USA
| | - Choli Lee
- Department of Genome Sciences, University of Washington, USA
| | - Gunhan Gulsoy
- Department of Genome Sciences, University of Washington, USA
| | - Xinxian Deng
- Department of Pathology, University of Washington, USA
| | - Savannah Cook
- Institute for Stem Cell and Regenerative Medicine, University of Washington, USA; Department of Comparative Medicine, University of Washington, USA
| | - Jennifer Hesson
- Institute for Stem Cell and Regenerative Medicine, University of Washington, USA; Department of Comparative Medicine, University of Washington, USA
| | - Christopher Cavanaugh
- Institute for Stem Cell and Regenerative Medicine, University of Washington, USA; Department of Comparative Medicine, University of Washington, USA
| | - Carol B Ware
- Institute for Stem Cell and Regenerative Medicine, University of Washington, USA; Department of Comparative Medicine, University of Washington, USA
| | - Anton Krumm
- Department of Radiation Oncology, University of Washington, USA
| | - Jay Shendure
- Department of Genome Sciences, University of Washington, USA; Howard Hughes Medical Institute, Seattle, WA 98195-8056, USA
| | - C Anthony Blau
- Institute for Stem Cell and Regenerative Medicine, University of Washington, USA; Division of Hematology, Department of Medicine, University of Washington, USA
| | | | - William S Noble
- Department of Genome Sciences, University of Washington, USA.
| | - ZhiJun Duan
- Institute for Stem Cell and Regenerative Medicine, University of Washington, USA; Division of Hematology, Department of Medicine, University of Washington, USA.
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47
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Barutcu AR, Maass PG, Lewandowski JP, Weiner CL, Rinn JL. A TAD boundary is preserved upon deletion of the CTCF-rich Firre locus. Nat Commun 2018; 9:1444. [PMID: 29654311 PMCID: PMC5899154 DOI: 10.1038/s41467-018-03614-0] [Citation(s) in RCA: 70] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2017] [Accepted: 02/27/2018] [Indexed: 12/22/2022] Open
Abstract
The binding of the transcriptional regulator CTCF to the genome has been implicated in the formation of topologically associated domains (TADs). However, the general mechanisms of folding the genome into TADs are not fully understood. Here we test the effects of deleting a CTCF-rich locus on TAD boundary formation. Using genome-wide chromosome conformation capture (Hi-C), we focus on one TAD boundary on chromosome X harboring ~ 15 CTCF binding sites and located at the long non-coding RNA (lncRNA) locus Firre. Specifically, this TAD boundary is invariant across evolution, tissues, and temporal dynamics of X-chromosome inactivation. We demonstrate that neither the deletion of this locus nor the ectopic insertion of Firre cDNA or its ectopic expression are sufficient to alter TADs in a sex-specific or allele-specific manner. In contrast, Firre's deletion disrupts the chromatin super-loop formation of the inactive X-chromosome. Collectively, our findings suggest that apart from CTCF binding, additional mechanisms may play roles in establishing TAD boundary formation.
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Affiliation(s)
- A Rasim Barutcu
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, MA, 02138, USA.
- Broad Institute of Massachusetts Institute of Technology and Harvard, Cambridge, MA, 02142, USA.
| | - Philipp G Maass
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, MA, 02138, USA
| | - Jordan P Lewandowski
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, MA, 02138, USA
- Department of Pathology, Beth Israel Deaconess Medical Center, Boston, MA, 02215, USA
| | - Catherine L Weiner
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, MA, 02138, USA
- Broad Institute of Massachusetts Institute of Technology and Harvard, Cambridge, MA, 02142, USA
- Department of Pathology, Beth Israel Deaconess Medical Center, Boston, MA, 02215, USA
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA, 02138, USA
| | - John L Rinn
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, MA, 02138, USA.
- Broad Institute of Massachusetts Institute of Technology and Harvard, Cambridge, MA, 02142, USA.
- Department of Pathology, Beth Israel Deaconess Medical Center, Boston, MA, 02215, USA.
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA, 02138, USA.
- Department of Biochemistry, University of Colorado, BioFrontiers Institute, Boulder, CO, 80301, USA.
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