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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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2
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Dileep V, Wilson KA, Marchal C, Lyu X, Zhao PA, Li B, Poulet A, Bartlett DA, Rivera-Mulia JC, Qin ZS, Robins AJ, Schulz TC, Kulik MJ, McCord RP, Dekker J, Dalton S, Corces VG, Gilbert DM. Rapid Irreversible Transcriptional Reprogramming in Human Stem Cells Accompanied by Discordance between Replication Timing and Chromatin Compartment. Stem Cell Reports 2019; 13:193-206. [PMID: 31231024 PMCID: PMC6627004 DOI: 10.1016/j.stemcr.2019.05.021] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2018] [Revised: 05/20/2019] [Accepted: 05/20/2019] [Indexed: 02/02/2023] Open
Abstract
The temporal order of DNA replication is regulated during development and is highly correlated with gene expression, histone modifications and 3D genome architecture. We tracked changes in replication timing, gene expression, and chromatin conformation capture (Hi-C) A/B compartments over the first two cell cycles during differentiation of human embryonic stem cells to definitive endoderm. Remarkably, transcriptional programs were irreversibly reprogrammed within the first cell cycle and were largely but not universally coordinated with replication timing changes. Moreover, changes in A/B compartment and several histone modifications that normally correlate strongly with replication timing showed weak correlation during the early cell cycles of differentiation but showed increased alignment in later differentiation stages and in terminally differentiated cell lines. Thus, epigenetic cell fate transitions during early differentiation can occur despite dynamic and discordant changes in otherwise highly correlated genomic properties.
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Affiliation(s)
- Vishnu Dileep
- Department of Biological Science, Florida State University, 319 Stadium Drive, Tallahassee, FL 32306, USA
| | - Korey A Wilson
- Department of Biological Science, Florida State University, 319 Stadium Drive, Tallahassee, FL 32306, USA
| | - Claire Marchal
- Department of Biological Science, Florida State University, 319 Stadium Drive, Tallahassee, FL 32306, USA
| | - Xiaowen Lyu
- Department of Biology, Emory University, Atlanta, GA 30322, USA
| | - Peiyao A Zhao
- Department of Biological Science, Florida State University, 319 Stadium Drive, Tallahassee, FL 32306, USA
| | - Ben Li
- Department of Biostatistics and Bioinformatics, Rollins School of Public Health, Emory University, 1518 Clifton Road NE, Atlanta, GA 30322, USA
| | - Axel Poulet
- Department of Biostatistics and Bioinformatics, Rollins School of Public Health, Emory University, 1518 Clifton Road NE, Atlanta, GA 30322, USA
| | - Daniel A Bartlett
- Department of Biological Science, Florida State University, 319 Stadium Drive, Tallahassee, FL 32306, USA
| | - Juan Carlos Rivera-Mulia
- Department of Biological Science, Florida State University, 319 Stadium Drive, Tallahassee, FL 32306, USA
| | - Zhaohui S Qin
- Department of Biostatistics and Bioinformatics, Rollins School of Public Health, Emory University, 1518 Clifton Road NE, Atlanta, GA 30322, USA
| | | | | | - Michael J Kulik
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA 30602, USA
| | - Rachel Patton McCord
- Program in Systems Biology, Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Job Dekker
- Program in Systems Biology, Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA 01605, USA; Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA
| | - Stephen Dalton
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA 30602, USA
| | - Victor G Corces
- Department of Biology, Emory University, Atlanta, GA 30322, USA
| | - David M Gilbert
- Department of Biological Science, Florida State University, 319 Stadium Drive, Tallahassee, FL 32306, USA.
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Hiratani I, Takahashi S. DNA Replication Timing Enters the Single-Cell Era. Genes (Basel) 2019; 10:genes10030221. [PMID: 30884743 PMCID: PMC6470765 DOI: 10.3390/genes10030221] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2019] [Revised: 03/12/2019] [Accepted: 03/12/2019] [Indexed: 12/20/2022] Open
Abstract
In mammalian cells, DNA replication timing is controlled at the level of megabase (Mb)-sized chromosomal domains and correlates well with transcription, chromatin structure, and three-dimensional (3D) genome organization. Because of these properties, DNA replication timing is an excellent entry point to explore genome regulation at various levels and a variety of studies have been carried out over the years. However, DNA replication timing studies traditionally required at least tens of thousands of cells, and it was unclear whether the replication domains detected by cell population analyses were preserved at the single-cell level. Recently, single-cell DNA replication profiling methods became available, which revealed that the Mb-sized replication domains detected by cell population analyses were actually well preserved in individual cells. In this article, we provide a brief overview of our current knowledge on DNA replication timing regulation in mammals based on cell population studies, outline the findings from single-cell DNA replication profiling, and discuss future directions and challenges.
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Affiliation(s)
- Ichiro Hiratani
- Laboratory for Developmental Epigenetics, RIKEN Center for Biosystems Dynamics Research (BDR), Kobe, Hyogo 650-0047, Japan.
| | - Saori Takahashi
- Laboratory for Developmental Epigenetics, RIKEN Center for Biosystems Dynamics Research (BDR), Kobe, Hyogo 650-0047, Japan.
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Genome-wide stability of the DNA replication program in single mammalian cells. Nat Genet 2019; 51:529-540. [PMID: 30804559 DOI: 10.1038/s41588-019-0347-5] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2017] [Accepted: 01/09/2019] [Indexed: 11/09/2022]
Abstract
Here, we report a single-cell DNA replication sequencing method, scRepli-seq, a genome-wide methodology that measures copy number differences between replicated and unreplicated DNA. Using scRepli-seq, we demonstrate that replication-domain organization is conserved among individual mouse embryonic stem cells (mESCs). Differentiated mESCs exhibited distinct profiles, which were also conserved among cells. Haplotype-resolved scRepli-seq revealed similar replication profiles of homologous autosomes, while the inactive X chromosome was clearly replicated later than its active counterpart. However, a small degree of cell-to-cell replication-timing heterogeneity was present, which was smallest at the beginning and the end of S phase. In addition, developmentally regulated domains were found to deviate from others and showed a higher degree of heterogeneity, thus suggesting a link to developmental plasticity. Moreover, allelic expression imbalance was found to strongly associate with replication-timing asynchrony. Our results form a foundation for single-cell-level understanding of DNA replication regulation and provide insights into three-dimensional genome organization.
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Takahashi S, Kobayashi S, Hiratani I. Epigenetic differences between naïve and primed pluripotent stem cells. Cell Mol Life Sci 2018; 75:1191-1203. [PMID: 29134247 PMCID: PMC5843680 DOI: 10.1007/s00018-017-2703-x] [Citation(s) in RCA: 65] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2017] [Revised: 10/22/2017] [Accepted: 10/30/2017] [Indexed: 02/07/2023]
Abstract
It has been 8 years since the concept of naïve and primed pluripotent stem cell states was first proposed. Both are states of pluripotency, but exhibit slightly different properties. The naïve state represents the cellular state of the preimplantation mouse blastocyst inner cell mass, while the primed state is representative of the post-implantation epiblast cells. These two cell types exhibit clearly distinct developmental potential, as evidenced by the fact that naïve cells are able to contribute to blastocyst chimeras, while primed cells cannot. However, the epigenetic differences that underlie the distinct developmental potential of these cell types remain unclear, which is rather surprising given the large amount of active investigation over the years. Elucidating such epigenetic differences should lead to a better understanding of the fundamental properties of these states of pluripotency and the means by which the naïve-to-primed transition occurs, which may provide insights into the essence of stem cell commitment.
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Affiliation(s)
- Saori Takahashi
- Laboratory for Developmental Epigenetics, RIKEN Center for Developmental Biology, 2-2-3 Minatojima-minamimachi, Chuo-ku, Kobe, 650-0047, Japan
| | - Shin Kobayashi
- Molecular Profiling Research Center for Drug Discovery, National Institute of Advanced Industrial Science and Technology, 2-4-7 Aomi, Koutou-ku, Tokyo, 135-0064, Japan.
- Department of Epigenetics, Medical Research Institute, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8510, Japan.
| | - Ichiro Hiratani
- Laboratory for Developmental Epigenetics, RIKEN Center for Developmental Biology, 2-2-3 Minatojima-minamimachi, Chuo-ku, Kobe, 650-0047, Japan.
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Pinter SF. A Tale of Two Cities: How Xist and its partners localize to and silence the bicompartmental X. Semin Cell Dev Biol 2016; 56:19-34. [PMID: 27072488 DOI: 10.1016/j.semcdb.2016.03.023] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2016] [Revised: 03/30/2016] [Accepted: 03/30/2016] [Indexed: 10/22/2022]
Abstract
Sex chromosomal dosage compensation in mammals takes the form of X chromosome inactivation (XCI), driven by the non-coding RNA Xist. In contrast to dosage compensation systems of flies and worms, mammalian XCI has to restrict its function to the Xist-producing X chromosome, while leaving autosomes and active X untouched. The mechanisms behind the long-range yet cis-specific localization and silencing activities of Xist have long been enigmatic, but genomics, proteomics, super-resolution microscopy, and innovative genetic approaches have produced significant new insights in recent years. In this review, I summarize and integrate these findings with a particular focus on the redundant yet mutually reinforcing pathways that enable long-term transcriptional repression throughout the soma. This includes an exploration of concurrent epigenetic changes acting in parallel within two distinct compartments of the inactive X. I also examine how Polycomb repressive complexes 1 and 2 and macroH2A may bridge XCI establishment and maintenance. XCI is a remarkable phenomenon that operates across multiple scales, combining changes in nuclear architecture, chromosome topology, chromatin compaction, and nucleosome/nucleotide-level epigenetic cues. Learning how these pathways act in concert likely holds the answer to the riddle posed by Cattanach's and other autosomal translocations: What makes the X especially receptive to XCI?
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Affiliation(s)
- Stefan F Pinter
- Department of Genetics and Genome Sciences, Institute for Systems Genomics, University of Connecticut Health Center, 263 Farmington Ave, Farmington, CT 06030-6403, USA.
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Massah S, Beischlag TV, Prefontaine GG. Epigenetic events regulating monoallelic gene expression. Crit Rev Biochem Mol Biol 2015; 50:337-58. [PMID: 26155735 DOI: 10.3109/10409238.2015.1064350] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
In mammals, generally it is assumed that the genes inherited from each parent are expressed to similar levels. However, it is now apparent that in non-sex chromosomes, 6-10% of genes are selected for monoallelic expression. Monoallelic expression or allelic exclusion is established either in an imprinted (parent-of-origin) or a stochastic manner. The stochastic model explains random selection while the imprinted model describes parent-of-origin specific selection of alleles for expression. Allelic exclusion occurs during X chromosome inactivation, parent-of-origin expression of imprinted genes and stochastic monoallelic expression of cell surface molecules, clustered protocadherin (PCDH) genes. Mis-regulation or loss of allelic exclusion contributes to developmental diseases. Epigenetic mechanisms are fundamental players that determine this type of expression despite a homogenous genetic background. DNA methylation and histone modifications are two mediators of the epigenetic phenomena. The majority of DNA methylation is found on cytosines of the CpG dinucleotide in mammals. Several covalent modifications of histones change the electrostatic forces between DNA and histones modifying gene expression. Long-range chromatin interactions organize chromatin into transcriptionally permissive and prohibitive regions leading to simultaneous regulation of gene expression and repression. Non-coding RNAs (ncRNAs) are also players in regulating gene expression. Together, these epigenetic mechanisms fine-tune gene expression levels essential for normal development and survival. In this review, first we discuss what is known about monoallelic gene expression. Then, we focus on the molecular mechanisms that regulate expression of three monoallelically expressed gene classes: the X-linked genes, selected imprinted genes and PCDH genes.
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Affiliation(s)
- Shabnam Massah
- a The Faculty of Health Sciences , Simon Fraser University , Burnaby , BC , Canada
| | - Timothy V Beischlag
- a The Faculty of Health Sciences , Simon Fraser University , Burnaby , BC , Canada
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Abstract
Patterns of replication within eukaryotic genomes correlate with gene expression, chromatin structure, and genome evolution. Recent advances in genome-scale mapping of replication kinetics have allowed these correlations to be explored in many species, cell types, and growth conditions, and these large data sets have allowed quantitative and computational analyses. One striking new correlation to emerge from these analyses is between replication timing and the three-dimensional structure of chromosomes. This correlation, which is significantly stronger than with any single histone modification or chromosome-binding protein, suggests that replication timing is controlled at the level of chromosomal domains. This conclusion dovetails with parallel work on the heterogeneity of origin firing and the competition between origins for limiting activators to suggest a model in which the stochastic probability of individual origin firing is modulated by chromosomal domain structure to produce patterns of replication. Whether these patterns have inherent biological functions or simply reflect higher-order genome structure is an open question.
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Affiliation(s)
- Nicholas Rhind
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA.
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Gilbert DM. Cell fate transitions and the replication timing decision point. J Cell Biol 2010; 191:899-903. [PMID: 21115801 PMCID: PMC2995162 DOI: 10.1083/jcb.201007125] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2010] [Accepted: 11/03/2010] [Indexed: 12/11/2022] Open
Abstract
Recent findings suggest that large-scale remodeling of three dimensional (3D) chromatin architecture occurs during a brief period in early G1 phase termed the replication timing decision point (TDP). In this speculative article, I suggest that the TDP may represent an as yet unappreciated window of opportunity for extracellular cues to influence 3D architecture during stem cell fate decisions. I also describe several testable predictions of this hypothesis.
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Affiliation(s)
- David M Gilbert
- Department of Biological Science, Florida State University, Tallahassee, FL 32306, USA.
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