1
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Moindrot B, Imaizumi Y, Feil R. Differential 3D genome architecture and imprinted gene expression: cause or consequence? Biochem Soc Trans 2024; 52:973-986. [PMID: 38775198 DOI: 10.1042/bst20230143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2024] [Revised: 04/26/2024] [Accepted: 04/29/2024] [Indexed: 06/27/2024]
Abstract
Imprinted genes provide an attractive paradigm to unravel links between transcription and genome architecture. The parental allele-specific expression of these essential genes - which are clustered in chromosomal domains - is mediated by parental methylation imprints at key regulatory DNA sequences. Recent chromatin conformation capture (3C)-based studies show differential organization of topologically associating domains between the parental chromosomes at imprinted domains, in embryonic stem and differentiated cells. At several imprinted domains, differentially methylated regions show allelic binding of the insulator protein CTCF, and linked focal retention of cohesin, at the non-methylated allele only. This generates differential patterns of chromatin looping between the parental chromosomes, already in the early embryo, and thereby facilitates the allelic gene expression. Recent research evokes also the opposite scenario, in which allelic transcription contributes to the differential genome organization, similarly as reported for imprinted X chromosome inactivation. This may occur through epigenetic effects on CTCF binding, through structural effects of RNA Polymerase II, or through imprinted long non-coding RNAs that have chromatin repressive functions. The emerging picture is that epigenetically-controlled differential genome architecture precedes and facilitates imprinted gene expression during development, and that at some domains, conversely, the mono-allelic gene expression also influences genome architecture.
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Affiliation(s)
- Benoit Moindrot
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), Gif-sur-Yvette, France
| | - Yui Imaizumi
- Institute of Molecular Genetics of Montpellier (IGMM), University of Montpellier, CNRS, Montpellier, France
| | - Robert Feil
- Institute of Molecular Genetics of Montpellier (IGMM), University of Montpellier, CNRS, Montpellier, France
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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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Bowness JS, Almeida M, Nesterova TB, Brockdorff N. YY1 binding is a gene-intrinsic barrier to Xist-mediated gene silencing. EMBO Rep 2024; 25:2258-2277. [PMID: 38654121 PMCID: PMC11094009 DOI: 10.1038/s44319-024-00136-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2024] [Revised: 03/26/2024] [Accepted: 04/03/2024] [Indexed: 04/25/2024] Open
Abstract
X chromosome inactivation (XCI) in mammals is mediated by Xist RNA which functions in cis to silence genes on a single X chromosome in XX female cells, thereby equalising levels of X-linked gene expression relative to XY males. XCI progresses over a period of several days, with some X-linked genes silencing faster than others. The chromosomal location of a gene is an important determinant of silencing rate, but uncharacterised gene-intrinsic features also mediate resistance or susceptibility to silencing. In this study, we examine mouse embryonic stem cell lines with an inducible Xist allele (iXist-ChrX mESCs) and integrate allele-specific data of gene silencing and decreasing inactive X (Xi) chromatin accessibility over time courses of Xist induction with cellular differentiation. Our analysis reveals that motifs bound by the transcription factor YY1 are associated with persistently accessible regulatory elements, including many promoters and enhancers of slow-silencing genes. We further show that YY1 is evicted relatively slowly from target sites on Xi, and that silencing of X-linked genes is increased upon YY1 degradation. Together our results suggest that YY1 acts as a barrier to Xist-mediated silencing until the late stages of the XCI process.
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Affiliation(s)
- Joseph S Bowness
- Department of Biochemistry, University of Oxford, Oxford, OX1 3QU, UK
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Dr. Aiguader 88, 08003, Barcelona, Spain
| | - Mafalda Almeida
- Department of Biochemistry, University of Oxford, Oxford, OX1 3QU, UK
| | | | - Neil Brockdorff
- Department of Biochemistry, University of Oxford, Oxford, OX1 3QU, UK.
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4
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Cifuentes D, Draisma J, Henriksson O, Korchmaros A, Kubjas K. 3D Genome Reconstruction from Partially Phased Hi-C Data. Bull Math Biol 2024; 86:33. [PMID: 38386111 PMCID: PMC10884149 DOI: 10.1007/s11538-024-01263-7] [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: 07/08/2023] [Accepted: 01/22/2024] [Indexed: 02/23/2024]
Abstract
The 3-dimensional (3D) structure of the genome is of significant importance for many cellular processes. In this paper, we study the problem of reconstructing the 3D structure of chromosomes from Hi-C data of diploid organisms, which poses additional challenges compared to the better-studied haploid setting. With the help of techniques from algebraic geometry, we prove that a small amount of phased data is sufficient to ensure finite identifiability, both for noiseless and noisy data. In the light of these results, we propose a new 3D reconstruction method based on semidefinite programming, paired with numerical algebraic geometry and local optimization. The performance of this method is tested on several simulated datasets under different noise levels and with different amounts of phased data. We also apply it to a real dataset from mouse X chromosomes, and we are then able to recover previously known structural features.
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Affiliation(s)
- Diego Cifuentes
- School of Industrial and Systems Engineering, Georgia Institute of Technology, 755 Ferst Drive, NW, Atlanta, GA, 30332, USA
| | - Jan Draisma
- Mathematisches Institut, University of Bern, Sidlerstrasse 5, 3012, Bern, Switzerland
| | - Oskar Henriksson
- Department of Mathematical Sciences, University of Copenhagen, Universitetsparken 5, 2100, Copenhagen, Denmark
| | - Annachiara Korchmaros
- Bioinformatics Group, Department of Computer Science and Interdisciplinary Center for Bioinformatics, University of Leipzig, Härtelstraße 16-18, 04107, Leipzig, Germany
| | - Kaie Kubjas
- Department of Mathematics and Systems Analysis, Aalto University, P.O. Box 11100, 00076, Aalto, Finland.
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5
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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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6
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Liu S, Zheng P, Wang CY, Jia BB, Zemke NR, Ren B, Zhuang X. Cell-type-specific 3D-genome organization and transcription regulation in the brain. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.04.570024. [PMID: 38105994 PMCID: PMC10723369 DOI: 10.1101/2023.12.04.570024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2023]
Abstract
3D organization of the genome plays a critical role in regulating gene expression. However, it remains unclear how chromatin organization differs among different cell types in the brain. Here we used genome-scale DNA and RNA imaging to investigate 3D-genome organization in transcriptionally distinct cell types in the primary motor cortex of the mouse brain. We uncovered a wide spectrum of differences in the nuclear architecture and 3D-genome organization among different cell types, ranging from the physical size of the cell nucleus to the active-inactive chromatin compartmentalization and radial positioning of chromatin loci within the nucleus. These cell-type-dependent variations in nuclear architecture and chromatin organization exhibited strong correlation with both total transcriptional activity of the cell and transcriptional regulation of cell-type-specific marker genes. Moreover, we found that the methylated-DNA-binding protein MeCP2 regulates transcription in a divergent manner, depending on the nuclear radial positions of chromatin loci, through modulating active-inactive chromatin compartmentalization.
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Affiliation(s)
- Shiwei Liu
- Howard Hughes Medical Institute, Department of Chemistry and Chemical Biology, Department of Physics, Harvard University, Cambridge, MA, USA
| | - Pu Zheng
- Howard Hughes Medical Institute, Department of Chemistry and Chemical Biology, Department of Physics, Harvard University, Cambridge, MA, USA
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA, USA
| | - Cosmos Yuqi Wang
- Howard Hughes Medical Institute, Department of Chemistry and Chemical Biology, Department of Physics, Harvard University, Cambridge, MA, USA
| | - Bojing Blair Jia
- Bioinformatics and Systems Biology Graduate Program, Medical Scientist Training Program, University of California San Diego, La Jolla, CA, USA
| | - Nathan R. Zemke
- Department of Cellular and Molecular Medicine and Center for Epigenomics, University of California, San Diego School of Medicine, La Jolla, CA, USA
| | - Bing Ren
- Department of Cellular and Molecular Medicine and Center for Epigenomics, University of California, San Diego School of Medicine, La Jolla, CA, USA
| | - Xiaowei Zhuang
- Howard Hughes Medical Institute, Department of Chemistry and Chemical Biology, Department of Physics, Harvard University, Cambridge, MA, USA
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7
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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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8
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Liao X, Ruan X, Yao P, Yang D, Wu X, Zhou X, Jing J, Wei D, Liang Y, Zhang T, Qin S, Jiang H. LncRNA-Gm9866 promotes liver fibrosis by activating TGFβ/Smad signaling via targeting Fam98b. J Transl Med 2023; 21:778. [PMID: 37919785 PMCID: PMC10621198 DOI: 10.1186/s12967-023-04642-1] [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: 08/03/2023] [Accepted: 10/20/2023] [Indexed: 11/04/2023] Open
Abstract
OBJECTIVE The exact mechanism and target molecules of liver fibrosis have remained largely elusive. Here, we investigated the role of long noncoding RNA Gm9866(lncRNA-Gm9866) on liver fibrosis. METHODS The transcription of lncRNA-Gm9866 in activated cells and mouse fibrotic livers was determined by quantitative polymerase chain reaction (qRT-PCR). The effects of lentivirus-mediated knockdown or overexpression of lncRNA-Gm9866 in liver fibrosis were examined in vitro and in vivo. Furthermore, bioinformatics analysis, cell samples validation, fluorescence in situ hybridization (FISH) co-localization, RNA binding protein immunoprecipitation (RIP), actinomycin D test and Western blot (WB) were carried out to explore the potential mechanism of lncRNA-Gm9866. RESULTS The expression of α-smooth muscle actin (α-SMA), Collagen I (COL-1) and lncRNA-Gm9866 were significantly increased in tissues and cells. Overexpressing lncRNA-Gm9866 promoted the activation of hepatic stellate cells (HSCs). Silencing lncRNA-Gm9866 inhibited the activation of HSCs and transforming growth factor-β1 (TGFβ1) induced fibrosis. Overexpressing lncRNA-Gm9866 promoted hepatocytes (HCs) apoptosis and the expression of pro-fibrogenic genes, inhibited the proliferation and migration of HCs. Knockdown of lncRNA-Gm9866 inhibited the apoptosis of HCs, the expression of pro-fibrogenic genes, TGFβ1 induced fibrosis and the occurrence of carbon tetrachloride (CCl4)-induced liver fibrosis, and promoted the proliferation and migration of HCs. Mechanistically, lncRNA-Gm9866 may directly bine with Fam98b. Silencing Fam98b in stably overexpressing lncRNA-Gm9866 cell lines reversed the increase of pro-fibrogenic genes and pro-apoptotic genes, fibrosis related pathway protein TGFβ1, Smad2/3, p-Smad2/3 and Notch3 induced by overexpressing lncRNA-Gm9866. CONCLUSIONS LncRNA-Gm9866 may regulate TGFβ/Smad and Notch pathways by targeting Fam98b to regulate liver fibrosis. LncRNA-Gm9866 may be a new target for diagnosis and treatment of liver fibrosis.
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Affiliation(s)
- Xiaomin Liao
- Department of Gastroenterology, The First Affiliated Hospital of Guangxi Medical University, No. 6, Shuangyong Road, Nanning, 530021, Guangxi, China
| | - Xianxian Ruan
- Department of Gastroenterology, The First Affiliated Hospital of Guangxi Medical University, No. 6, Shuangyong Road, Nanning, 530021, Guangxi, China
| | - Peishan Yao
- Department of Gastroenterology, The First Affiliated Hospital of Guangxi Medical University, No. 6, Shuangyong Road, Nanning, 530021, Guangxi, China
| | - Dan Yang
- Department of Gastroenterology, The Affiliated Hospital of Southwest Medical University, Luzhou, 646000, Sichuan, China
| | - Xianbin Wu
- Department of Gastroenterology, The Wuming Affiliated Hospital of Guangxi Medical University, Nanning, 530000, Guangxi, China
| | - Xia Zhou
- Department of Emergency, People's Hospital of Guizhou Province, Guiyang, 550000, Guizhou, China
| | - Jie Jing
- Department of Gastroenterology, The First Affiliated Hospital of Guangxi Medical University, No. 6, Shuangyong Road, Nanning, 530021, Guangxi, China
| | - Dafu Wei
- Department of Gastroenterology, The First Affiliated Hospital of Guangxi Medical University, No. 6, Shuangyong Road, Nanning, 530021, Guangxi, China
| | - Yaodan Liang
- Department of Gastroenterology, The First Affiliated Hospital of Guangxi Medical University, No. 6, Shuangyong Road, Nanning, 530021, Guangxi, China
| | - Taicheng Zhang
- Department of Gastroenterology, The First Affiliated Hospital of Guangxi Medical University, No. 6, Shuangyong Road, Nanning, 530021, Guangxi, China
| | - Shanyu Qin
- Department of Gastroenterology, The First Affiliated Hospital of Guangxi Medical University, No. 6, Shuangyong Road, Nanning, 530021, Guangxi, China.
| | - Haixing Jiang
- Department of Gastroenterology, The First Affiliated Hospital of Guangxi Medical University, No. 6, Shuangyong Road, Nanning, 530021, Guangxi, China.
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9
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Chahine Z, Gupta M, Lenz T, Hollin T, Abel S, Banks CAS, Saraf A, Prudhomme J, Florens L, Le Roch KG. PfMORC protein regulates chromatin accessibility and transcriptional repression in the human malaria parasite, P. falciparum. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.11.557253. [PMID: 37745554 PMCID: PMC10515874 DOI: 10.1101/2023.09.11.557253] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/26/2023]
Abstract
The environmental challenges the human malaria parasite, Plasmodium falciparum, faces during its progression into its various lifecycle stages warrant the use of effective and highly regulated access to chromatin for transcriptional regulation. Microrchidia (MORC) proteins have been implicated in DNA compaction and gene silencing across plant and animal kingdoms. Accumulating evidence has shed light into the role MORC protein plays as a transcriptional switch in apicomplexan parasites. In this study, using CRISPR/Cas9 genome editing tool along with complementary molecular and genomics approaches, we demonstrate that PfMORC not only modulates chromatin structure and heterochromatin formation throughout the parasite erythrocytic cycle, but is also essential to the parasite survival. Chromatin immunoprecipitation followed by deep sequencing (ChIP-seq) experiments suggest that PfMORC binds to not only sub-telomeric regions and genes involved in antigenic variation but is also most likely a key modulator of stage transition. Protein knockdown experiments followed by chromatin conformation capture (Hi-C) studies indicate that downregulation of PfMORC induces the collapse of the parasite heterochromatin structure leading to its death. All together these findings confirm that PfMORC plays a crucial role in chromatin structure and gene regulation, validating this factor as a strong candidate for novel antimalarial strategies.
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Affiliation(s)
- Z Chahine
- Department of Molecular, Cell and Systems Biology, University of California Riverside, CA, USA
| | - M Gupta
- Department of Molecular, Cell and Systems Biology, University of California Riverside, CA, USA
| | - T Lenz
- Department of Molecular, Cell and Systems Biology, University of California Riverside, CA, USA
| | - T Hollin
- Department of Molecular, Cell and Systems Biology, University of California Riverside, CA, USA
| | - S Abel
- Department of Molecular, Cell and Systems Biology, University of California Riverside, CA, USA
| | - CAS Banks
- Stowers Institute for Medical Research, 1000 E. 50th Street, Kansas City, MO 64110, USA
| | - A Saraf
- Stowers Institute for Medical Research, 1000 E. 50th Street, Kansas City, MO 64110, USA
| | - J Prudhomme
- Department of Molecular, Cell and Systems Biology, University of California Riverside, CA, USA
| | - L Florens
- Stowers Institute for Medical Research, 1000 E. 50th Street, Kansas City, MO 64110, USA
| | - KG Le Roch
- Department of Molecular, Cell and Systems Biology, University of California Riverside, CA, USA
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10
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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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11
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Laberthonnière C, Delourme M, Chevalier R, Dion C, Ganne B, Hirst D, Caron L, Perrin P, Adélaïde J, Chaffanet M, Xue S, Nguyen K, Reversade B, Déjardin J, Baudot A, Robin J, Magdinier F. In skeletal muscle and neural crest cells, SMCHD1 regulates biological pathways relevant for Bosma syndrome and facioscapulohumeral dystrophy phenotype. Nucleic Acids Res 2023; 51:7269-7287. [PMID: 37334829 PMCID: PMC10415154 DOI: 10.1093/nar/gkad523] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2023] [Revised: 05/15/2023] [Accepted: 06/05/2023] [Indexed: 06/21/2023] Open
Abstract
Many genetic syndromes are linked to mutations in genes encoding factors that guide chromatin organization. Among them, several distinct rare genetic diseases are linked to mutations in SMCHD1 that encodes the structural maintenance of chromosomes flexible hinge domain containing 1 chromatin-associated factor. In humans, its function as well as the impact of its mutations remains poorly defined. To fill this gap, we determined the episignature associated with heterozygous SMCHD1 variants in primary cells and cell lineages derived from induced pluripotent stem cells for Bosma arhinia and microphthalmia syndrome (BAMS) and type 2 facioscapulohumeral dystrophy (FSHD2). In human tissues, SMCHD1 regulates the distribution of methylated CpGs, H3K27 trimethylation and CTCF at repressed chromatin but also at euchromatin. Based on the exploration of tissues affected either in FSHD or in BAMS, i.e. skeletal muscle fibers and neural crest stem cells, respectively, our results emphasize multiple functions for SMCHD1, in chromatin compaction, chromatin insulation and gene regulation with variable targets or phenotypical outcomes. We concluded that in rare genetic diseases, SMCHD1 variants impact gene expression in two ways: (i) by changing the chromatin context at a number of euchromatin loci or (ii) by directly regulating some loci encoding master transcription factors required for cell fate determination and tissue differentiation.
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Affiliation(s)
| | - Mégane Delourme
- Aix Marseille Univ, INSERM, Marseille Medical Genetics, Marseille 13005, France
| | - Raphaël Chevalier
- Aix Marseille Univ, INSERM, Marseille Medical Genetics, Marseille 13005, France
| | - Camille Dion
- Aix Marseille Univ, INSERM, Marseille Medical Genetics, Marseille 13005, France
| | - Benjamin Ganne
- Aix Marseille Univ, INSERM, Marseille Medical Genetics, Marseille 13005, France
| | - David Hirst
- Aix Marseille Univ, INSERM, Marseille Medical Genetics, Marseille 13005, France
| | - Leslie Caron
- Aix Marseille Univ, INSERM, Marseille Medical Genetics, Marseille 13005, France
| | - Pierre Perrin
- Aix Marseille Univ, INSERM, Marseille Medical Genetics, Marseille 13005, France
| | - José Adélaïde
- Aix Marseille Univ, INSERM, CNRS, Institut Paoli Calmette, Centre de Recherche en Cancérologie de Marseille, Laboratory of predictive Oncology, Marseille 13009, France
| | - Max Chaffanet
- Aix Marseille Univ, INSERM, CNRS, Institut Paoli Calmette, Centre de Recherche en Cancérologie de Marseille, Laboratory of predictive Oncology, Marseille 13009, France
| | - Shifeng Xue
- Department of Biological Sciences, National University of Singapore, Singapore 117558, Singapore
- Genome Institute of Singapore, A*STAR, Singapore, Singapore
| | - Karine Nguyen
- Aix Marseille Univ, INSERM, Marseille Medical Genetics, Marseille 13005, France
- Département de Génétique Médicale, AP-HM, Hôpital d’enfants de la Timone, Marseille 13005, France
| | - Bruno Reversade
- Genome Institute of Singapore, A*STAR, Singapore, Singapore
- Department of Medical Genetics, Koç University, School of Medicine, Istanbul, Turkey
- Department of Physiology, Cardiovascular Disease Translational Research Programme, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
- Laboratory of Human Genetics & Therapeutics, Smart-Health Initiative, BESE, KAUST, Thuwal, Saudi Arabia
| | - Jérôme Déjardin
- Institut de Génétique Humaine, UMR 9002, CNRS–Université de Montpellier, Montpellier 34000, France
| | - Anaïs Baudot
- Aix Marseille Univ, INSERM, Marseille Medical Genetics, Marseille 13005, France
| | - Jérôme D Robin
- Aix Marseille Univ, INSERM, Marseille Medical Genetics, Marseille 13005, France
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12
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Patterson B, Yang B, Tanaka Y, Kim KY, Cakir B, Xiang Y, Kim J, Wang S, Park IH. Female naïve human pluripotent stem cells carry X chromosomes with Xa-like and Xi-like folding conformations. SCIENCE ADVANCES 2023; 9:eadf2245. [PMID: 37540754 PMCID: PMC10403202 DOI: 10.1126/sciadv.adf2245] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Accepted: 07/06/2023] [Indexed: 08/06/2023]
Abstract
Three-dimensional (3D) genomics shows immense promise for studying X chromosome inactivation (XCI) by interrogating changes to the X chromosomes' 3D states. Here, we sought to characterize the 3D state of the X chromosome in naïve and primed human pluripotent stem cells (hPSCs). Using chromatin tracing, we analyzed X chromosome folding conformations in these cells with megabase genomic resolution. X chromosomes in female naïve hPSCs exhibit folding conformations similar to the active X chromosome (Xa) and the inactive X chromosome (Xi) in somatic cells. However, naïve X chromosomes do not exhibit the chromatin compaction typically associated with these somatic X chromosome states. In H7 naïve human embryonic stem cells, XIST accumulation observed on damaged X chromosomes demonstrates the potential for naïve hPSCs to activate XCI-related mechanisms. Overall, our findings provide insight into the X chromosome status of naïve hPSCs with a single-chromosome resolution and are critical in understanding the unique epigenetic regulation in early embryonic cells.
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Affiliation(s)
- Benjamin Patterson
- Department of Genetics, Yale Stem Cell Center, Yale School of Medicine, New Haven, CT 06520, USA
| | - Bing Yang
- Department of Genetics, and Department of Cell Biology, Yale School of Medicine, New Haven, CT 06520, USA
| | - Yoshiaki Tanaka
- Department of Genetics, Yale Stem Cell Center, Yale School of Medicine, New Haven, CT 06520, USA
| | - Kun-Yong Kim
- Department of Genetics, Yale Stem Cell Center, Yale School of Medicine, New Haven, CT 06520, USA
| | - Bilal Cakir
- Department of Genetics, Yale Stem Cell Center, Yale School of Medicine, New Haven, CT 06520, USA
| | - Yangfei Xiang
- Department of Genetics, Yale Stem Cell Center, Yale School of Medicine, New Haven, CT 06520, USA
| | - Jonghun Kim
- Department of Genetics, Yale Stem Cell Center, Yale School of Medicine, New Haven, CT 06520, USA
| | - Siyuan Wang
- Department of Genetics, and Department of Cell Biology, Yale School of Medicine, New Haven, CT 06520, USA
| | - In-Hyun Park
- Department of Genetics, Yale Stem Cell Center, Yale School of Medicine, New Haven, CT 06520, USA
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13
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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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14
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Kudo R, Yoshida I, Matiz Ceron L, Mizushima S, Kuroki Y, Jogahara T, Kuroiwa A. The Neo-X Does Not Form a Barr Body but Shows a Slightly Condensed Structure in the Okinawa Spiny Rat (Tokudaia muenninki). Cytogenet Genome Res 2023; 162:632-643. [PMID: 37271129 DOI: 10.1159/000531275] [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: 04/07/2023] [Accepted: 05/27/2023] [Indexed: 06/06/2023] Open
Abstract
X chromosome inactivation (XCI) is an essential mechanism for gene dosage compensation between male and female cells in mammals. The Okinawa spiny rat (Tokudaia muenninki) is a native rodent in Japan with XX/XY sex chromosomes, like most mammals; however, the X chromosome has acquired a neo-X region (Xp) by fusion with an autosome. We previously reported that dosage compensation has not yet evolved in the neo-X region; however, X-inactive-specific transcript (Xist) RNA (long non-coding RNA required for the initiation of XCI) is partially localized in the region. Here, we show that the neo-X region represents an early chromosomal state in the acquisition of XCI by analyses of heterochromatin and Barr body formation. We found no evidence for heterochromatin formation in the neo-X region by R-banding by acridine orange (RBA) assays and immunostaining of H3K27me3. Double-immunostaining of H3K27me3 and HP1, a component of the Barr body, revealed that the entire ancestral X chromosome region (Xq) showed a bipartite folded structure. By contrast, HP1 was not localized to the neo-X region. However, BAC-FISH revealed that the signals of genes on the neo-X region of the inactive X chromosome were concentrated in a narrow region. These findings indicated that although the neo-X region of the inactive X chromosome does not form a complete Barr body structure (e.g., it lacks HP1), it forms a slightly condensed structure. These findings combined with the previously reported partial binding of Xist RNA suggest that the neo-X region exhibits incomplete inactivation. This may represent an early chromosomal state in the acquisition of the XCI mechanism.
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Affiliation(s)
- Ryoma Kudo
- Reproductive and Developmental Sciences, Biosystems Science Course, Graduate School of Life Science, Hokkaido University, Sapporo, Japan
| | - Ikuya Yoshida
- Reproductive and Developmental Sciences, Biosystems Science Course, Graduate School of Life Science, Hokkaido University, Sapporo, Japan
- Division of Reproductive and Developmental Biology, Department of Biological Sciences, Faculty of Science, Hokkaido University, Sapporo, Japan
| | - Luisa Matiz Ceron
- Reproductive and Developmental Sciences, Biosystems Science Course, Graduate School of Life Science, Hokkaido University, Sapporo, Japan
| | - Shusei Mizushima
- Reproductive and Developmental Sciences, Biosystems Science Course, Graduate School of Life Science, Hokkaido University, Sapporo, Japan
- Division of Reproductive and Developmental Biology, Department of Biological Sciences, Faculty of Science, Hokkaido University, Sapporo, Japan
| | - Yoko Kuroki
- Department of Genome Medicine, National Center for Child Health and Development, Tokyo, Japan
- Division of Collaborative Research, National Center for Child Health and Development, Tokyo, Japan
- Division of Diversity Research, National Research Institute for Child Health and Development, Tokyo, Japan
| | - Takamichi Jogahara
- Faculty of Law, Economics and Management, Okinawa University, Naha, Japan
| | - Asato Kuroiwa
- Reproductive and Developmental Sciences, Biosystems Science Course, Graduate School of Life Science, Hokkaido University, Sapporo, Japan
- Division of Reproductive and Developmental Biology, Department of Biological Sciences, Faculty of Science, Hokkaido University, Sapporo, Japan
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15
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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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16
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The Long Noncoding RNA Gm9866/Nuclear Factor- κB Axis Promotes Macrophage Polarization. Mediators Inflamm 2023; 2023:9991916. [PMID: 36756088 PMCID: PMC9899594 DOI: 10.1155/2023/9991916] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2022] [Revised: 01/17/2023] [Accepted: 01/18/2023] [Indexed: 02/03/2023] Open
Abstract
Macrophages are a type of immune cells with high levels of plasticity and heterogeneity. They can polarize into M1 or M2 functional phenotypes. These two phenotypes exhibit a dynamic balance during polarization-related diseases and play opposing roles. Long noncoding RNAs (lncRNAs) play an important role in biological processes such as cell proliferation, death, and differentiation; however, how long noncoding RNAs affect the cellular functionality of macrophages remains to be studied. Long noncoding RNA Gm9866 was found to be closely related to macrophage polarization through bioinformatics analysis. In this study, by conducting real-time polymerase chain reaction analysis, it was observed that long noncoding RNA Gm9866 expression significantly increased after treatment with interleukin-4 but significantly decreased after treatment with lipopolysaccharide. Fluorescence in situ hybridization revealed that long noncoding RNA Gm9866 was expressed mainly in the nucleus. Real-time polymerase chain reaction analysis showed that overexpression of long noncoding RNA Gm9866 in RAW264.7 cells further promoted the expression of M2 markers MRC1 (macrophage mannose receptor 1) and MRC2 (macrophage mannose receptor 2). Western blotting analysis demonstrated inhibition of nuclear factor-κB (NF-κB) expression. EdU (5-ethynyl-2'-deoxyuridine) and TUNEL (TdT-mediated dUTP nick-end labeling) staining assays revealed that overexpression of long noncoding RNA Gm9866 promoted cell proliferation and inhibited apoptosis. These findings thus indicated that long noncoding RNA Gm9866 promoted macrophage polarization and inhibited the nuclear factor-κB signaling pathway. Thus, long noncoding RNA Gm9866 may serve as a potential diagnostic and therapeutic target for polarization-related diseases such as infectious diseases, inflammatory diseases, liver fibrosis, and tumors.
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17
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Cohesin controls X chromosome structure remodeling and X-reactivation during mouse iPSC-reprogramming. Proc Natl Acad Sci U S A 2023; 120:e2213810120. [PMID: 36669113 PMCID: PMC9942853 DOI: 10.1073/pnas.2213810120] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Reactivation of the inactive X chromosome is a hallmark epigenetic event during reprogramming of mouse female somatic cells to induced pluripotent stem cells (iPSCs). This involves global structural remodeling from a condensed, heterochromatic into an open, euchromatic state, thereby changing a transcriptionally inactive into an active chromosome. Despite recent advances, very little is currently known about the molecular players mediating this process and how this relates to iPSC-reprogramming in general. To gain more insight, here we perform a RNAi-based knockdown screen during iPSC-reprogramming of mouse fibroblasts. We discover factors important for X chromosome reactivation (XCR) and iPSC-reprogramming. Among those, we identify the cohesin complex member SMC1a as a key molecule with a specific function in XCR, as its knockdown greatly affects XCR without interfering with iPSC-reprogramming. Using super-resolution microscopy, we find SMC1a to be preferentially enriched on the active compared with the inactive X chromosome and that SMC1a is critical for the decompacted state of the active X. Specifically, depletion of SMC1a leads to contraction of the active X both in differentiated and in pluripotent cells, where it normally is in its most open state. In summary, we reveal cohesin as a key factor for remodeling of the X chromosome from an inactive to an active structure and that this is a critical step for XCR during iPSC-reprogramming.
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18
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Kariti H, Feld T, Kaplan N. Hypothesis-driven probabilistic modelling enables a principled perspective of genomic compartments. Nucleic Acids Res 2023; 51:1103-1119. [PMID: 36629266 PMCID: PMC9943678 DOI: 10.1093/nar/gkac1258] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2022] [Revised: 11/30/2022] [Accepted: 01/10/2023] [Indexed: 01/12/2023] Open
Abstract
The Hi-C method has revolutionized the study of genome organization, yet interpretation of Hi-C interaction frequency maps remains a major challenge. Genomic compartments are a checkered Hi-C interaction pattern suggested to represent the partitioning of the genome into two self-interacting states associated with active and inactive chromatin. Based on a few elementary mechanistic assumptions, we derive a generative probabilistic model of genomic compartments, called deGeco. Testing our model, we find it can explain observed Hi-C interaction maps in a highly robust manner, allowing accurate inference of interaction probability maps from extremely sparse data without any training of parameters. Taking advantage of the interpretability of the model parameters, we then test hypotheses regarding the nature of genomic compartments. We find clear evidence of multiple states, and that these states self-interact with different affinities. We also find that the interaction rules of chromatin states differ considerably within and between chromosomes. Inspecting the molecular underpinnings of a four-state model, we show that a simple classifier can use histone marks to predict the underlying states with 87% accuracy. Finally, we observe instances of mixed-state loci and analyze these loci in single-cell Hi-C maps, finding that mixing of states occurs mainly at the cell level.
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Affiliation(s)
- Hagai Kariti
- Department of Physiology, Biophysics & Systems Biology, Rappaport Faculty of Medicine, Technion – Israel Institute of Technology, Haifa, Israel
| | - Tal Feld
- Department of Physiology, Biophysics & Systems Biology, Rappaport Faculty of Medicine, Technion – Israel Institute of Technology, Haifa, Israel,Viterbi Faculty of Electrical & Computer Engineering, Technion – Israel Institute of Technology, Haifa, Israel
| | - Noam Kaplan
- To whom correspondence should be addressed. Tel: +972 4 8295293;
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19
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Varoquaux N, Noble WS, Vert JP. Inference of 3D genome architecture by modeling overdispersion of Hi-C data. Bioinformatics 2023; 39:btac838. [PMID: 36594573 PMCID: PMC9857972 DOI: 10.1093/bioinformatics/btac838] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Revised: 11/16/2022] [Indexed: 01/04/2023] Open
Abstract
MOTIVATION We address the challenge of inferring a consensus 3D model of genome architecture from Hi-C data. Existing approaches most often rely on a two-step algorithm: first, convert the contact counts into distances, then optimize an objective function akin to multidimensional scaling (MDS) to infer a 3D model. Other approaches use a maximum likelihood approach, modeling the contact counts between two loci as a Poisson random variable whose intensity is a decreasing function of the distance between them. However, a Poisson model of contact counts implies that the variance of the data is equal to the mean, a relationship that is often too restrictive to properly model count data. RESULTS We first confirm the presence of overdispersion in several real Hi-C datasets, and we show that the overdispersion arises even in simulated datasets. We then propose a new model, called Pastis-NB, where we replace the Poisson model of contact counts by a negative binomial one, which is parametrized by a mean and a separate dispersion parameter. The dispersion parameter allows the variance to be adjusted independently from the mean, thus better modeling overdispersed data. We compare the results of Pastis-NB to those of several previously published algorithms, both MDS-based and statistical methods. We show that the negative binomial inference yields more accurate structures on simulated data, and more robust structures than other models across real Hi-C replicates and across different resolutions. AVAILABILITY AND IMPLEMENTATION A Python implementation of Pastis-NB is available at https://github.com/hiclib/pastis under the BSD license. SUPPLEMENTARY INFORMATION Supplementary data are available at Bioinformatics online.
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Affiliation(s)
- Nelle Varoquaux
- TIMC, Université Grenoble Alpes, CNRS, Grenoble INP, Grenoble 38000, France
| | - William S Noble
- Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA
- Paul G. Allen School of Computer Science and Engineering, University of Washington, Seattle, WA 98195, USA
| | - Jean-Philippe Vert
- Brain Team, Google Research, Paris 75009, France
- Centre for Computational Biology , MINES ParisTech, PSL University, Paris 75006, France
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20
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Shevchenko AI, Rifel NA, Zakian SM, Zakharova IS. Constitutive heterochromatin propagation contributes to the X chromosome inactivation. Chromosome Res 2022; 30:289-307. [PMID: 35920963 DOI: 10.1007/s10577-022-09706-4] [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: 04/27/2022] [Revised: 07/08/2022] [Accepted: 07/15/2022] [Indexed: 01/25/2023]
Abstract
Imprinted X chromosome inactivation (iXCI) balances the expression of X-linked genes in preimplantation embryos and extraembryonic tissues in rodents. Long noncoding Xist RNA drives iXCI, silencing genes and recruiting Xist-dependent chromatin repressors. Some domains on the inactive X chromosome include repressive modifications specific to constitutive heterochromatin, which show no direct link to Xist RNA. We explored the relationship between Xist RNA and chromatin silencing during iXCI in vole Microtus levis. We performed locus-specific activation of Xist transcription on the only active X chromosome using the dCas9-SAM system in XO vole trophoblast stem cells (TSCs), which allow modeling iXCI events to some extent. The artificially activated endogenous vole Xist transcript is truncated and restricted ~ 6.6 kb of the exon 1. Ectopic Xist RNA accumulates on the X chromosome and recruits Xist-dependent modifications during TSC differentiation, yet is incapable by itself repressing X-linked genes. Transcriptional silencing occurs upon ectopic Xist upregulation only when repressive marks spread from the massive telomeric constitutive heterochromatin to the X chromosome region containing genes. We hypothesize that the Xist RNA-induced propagation of repressive marks from the constitutive heterochromatin could be a mechanism involved in X chromosome inactivation.
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Affiliation(s)
- Alexander I Shevchenko
- Federal Research Center, "Institute of Cytology and Genetics of the Siberian Branch of the Russian Academy of Sciences", Novosibirsk, 630090, Russia.,Institute of Chemical Biology and Fundamental Medicine of the Siberian Branch of the Russian Academy of Sciences, Novosibirsk, 630090, Russia.,E.N. Meshalkin National Medical Research Center, Ministry of Health Care of Russian Federation, Novosibirsk, 630055, Russia
| | - Nikita A Rifel
- Federal Research Center, "Institute of Cytology and Genetics of the Siberian Branch of the Russian Academy of Sciences", Novosibirsk, 630090, Russia
| | - Suren M Zakian
- Federal Research Center, "Institute of Cytology and Genetics of the Siberian Branch of the Russian Academy of Sciences", Novosibirsk, 630090, Russia.,Institute of Chemical Biology and Fundamental Medicine of the Siberian Branch of the Russian Academy of Sciences, Novosibirsk, 630090, Russia.,E.N. Meshalkin National Medical Research Center, Ministry of Health Care of Russian Federation, Novosibirsk, 630055, Russia
| | - Irina S Zakharova
- Federal Research Center, "Institute of Cytology and Genetics of the Siberian Branch of the Russian Academy of Sciences", Novosibirsk, 630090, Russia. .,Institute of Chemical Biology and Fundamental Medicine of the Siberian Branch of the Russian Academy of Sciences, Novosibirsk, 630090, Russia. .,E.N. Meshalkin National Medical Research Center, Ministry of Health Care of Russian Federation, Novosibirsk, 630055, Russia.
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21
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Lu T, Ang CE, Zhuang X. Spatially resolved epigenomic profiling of single cells in complex tissues. Cell 2022; 185:4448-4464.e17. [PMID: 36272405 PMCID: PMC9691621 DOI: 10.1016/j.cell.2022.09.035] [Citation(s) in RCA: 54] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Revised: 08/22/2022] [Accepted: 09/26/2022] [Indexed: 11/06/2022]
Abstract
The recent development of spatial omics methods has enabled single-cell profiling of the transcriptome and 3D genome organization with high spatial resolution. Expanding the repertoire of spatial omics tools, a spatially resolved single-cell epigenomics method will accelerate understanding of the spatial regulation of cell and tissue functions. Here, we report a method for spatially resolved epigenomic profiling of single cells using in situ tagmentation and transcription followed by multiplexed imaging. We demonstrated the ability to profile histone modifications marking active promoters, putative enhancers, and silent promoters in individual cells, and generated high-resolution spatial atlas of hundreds of active promoters and putative enhancers in embryonic and adult mouse brains. Our results suggested putative promoter-enhancer pairs and enhancer hubs regulating developmentally important genes. We envision this approach will be generally applicable to spatial profiling of epigenetic modifications and DNA-binding proteins, advancing our understanding of how gene expression is spatiotemporally regulated by the epigenome.
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Affiliation(s)
- Tian Lu
- Howard Hughes Medical Institute, Harvard University, Cambridge, MA 02138, USA; Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA; Department of Physics, Harvard University, Cambridge, MA 02138, USA
| | - Cheen Euong Ang
- Howard Hughes Medical Institute, Harvard University, Cambridge, MA 02138, USA; Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA; Department of Physics, Harvard University, Cambridge, MA 02138, USA
| | - Xiaowei Zhuang
- Howard Hughes Medical Institute, Harvard University, Cambridge, MA 02138, USA; Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA; Department of Physics, Harvard University, Cambridge, MA 02138, USA.
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22
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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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23
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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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24
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Cechova M, Miga KH. Satellite DNAs and human sex chromosome variation. Semin Cell Dev Biol 2022; 128:15-25. [PMID: 35644878 DOI: 10.1016/j.semcdb.2022.04.022] [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: 03/15/2022] [Revised: 04/26/2022] [Accepted: 04/27/2022] [Indexed: 11/17/2022]
Abstract
Satellite DNAs are present on every chromosome in the cell and are typically enriched in repetitive, heterochromatic parts of the human genome. Sex chromosomes represent a unique genomic and epigenetic context. In this review, we first report what is known about satellite DNA biology on human X and Y chromosomes, including repeat content and organization, as well as satellite variation in typical euploid individuals. Then, we review sex chromosome aneuploidies that are among the most common types of aneuploidies in the general population, and are better tolerated than autosomal aneuploidies. This is demonstrated also by the fact that aging is associated with the loss of the X, and especially the Y chromosome. In addition, supernumerary sex chromosomes enable us to study general processes in a cell, such as analyzing heterochromatin dosage (i.e. additional Barr bodies and long heterochromatin arrays on Yq) and their downstream consequences. Finally, genomic and epigenetic organization and regulation of satellite DNA could influence chromosome stability and lead to aneuploidy. In this review, we argue that the complete annotation of satellite DNA on sex chromosomes in human, and especially in centromeric regions, will aid in explaining the prevalence and the consequences of sex chromosome aneuploidies.
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Affiliation(s)
- Monika Cechova
- Faculty of Informatics, Masaryk University, Czech Republic
| | - Karen H Miga
- Department of Biomolecular Engineering, University of California Santa Cruz, CA, USA; UC Santa Cruz Genomics Institute, University of California Santa Cruz, CA 95064, USA
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25
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Yang T, Ou J, Yildirim E. Xist exerts gene-specific silencing during XCI maintenance and impacts lineage-specific cell differentiation and proliferation during hematopoiesis. Nat Commun 2022; 13:4464. [PMID: 35915095 PMCID: PMC9343370 DOI: 10.1038/s41467-022-32273-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Accepted: 07/21/2022] [Indexed: 11/12/2022] Open
Abstract
X chromosome inactivation (XCI) is a dosage compensation phenomenon that occurs in females. Initiation of XCI depends on Xist RNA, which triggers silencing of one of the two X chromosomes, except for XCI escape genes that continue to be biallelically expressed. In the soma XCI is stably maintained with continuous Xist expression. How Xist impacts XCI maintenance remains an open question. Here we conditionally delete Xist in hematopoietic system of mice and report differentiation and cell cycle defects in female hematopoietic stem and progenitor cells (HSPCs). By utilizing female HSPCs and mouse embryonic fibroblasts, we find that X-linked genes show variable tolerance to Xist loss. Specifically, XCI escape genes exhibit preferential transcriptional upregulation, which associates with low H3K27me3 occupancy and high chromatin accessibility that accommodates preexisting binding of transcription factors such as Yin Yang 1 (YY1) at the basal state. We conclude that Xist is necessary for gene-specific silencing during XCI maintenance and impacts lineage-specific cell differentiation and proliferation during hematopoiesis. Here the authors investigate the functional relevance of X-chromosome inactivation (XCI) regulator Xist in hematopoiesis. They find that Xist loss leads to changes in the ratio of hematopoietic progenitor cells and results in chromatin accessibility and transcriptional upregulation on the inactive X chromosome, including XCI escape genes known to be associated with cell cycle and immune response.
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Affiliation(s)
- Tianqi Yang
- Department of Cell Biology, Duke University Medical Center, Durham, NC, 27710, USA.,Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, NC, 27710, USA.,Duke Regeneration Center, Duke University, Durham, NC, 27710, USA.,Duke Cancer Institute, Duke University Medical Center, Durham, NC, 27710, USA
| | - Jianhong Ou
- Department of Cell Biology, Duke University Medical Center, Durham, NC, 27710, USA.,Duke Regeneration Center, Duke University, Durham, NC, 27710, USA
| | - Eda Yildirim
- Department of Cell Biology, Duke University Medical Center, Durham, NC, 27710, USA. .,Duke Regeneration Center, Duke University, Durham, NC, 27710, USA. .,Duke Cancer Institute, Duke University Medical Center, Durham, NC, 27710, USA.
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26
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Zhang S, Plummer D, Lu L, Cui J, Xu W, Wang M, Liu X, Prabhakar N, Shrinet J, Srinivasan D, Fraser P, Li Y, Li J, Jin F. DeepLoop robustly maps chromatin interactions from sparse allele-resolved or single-cell Hi-C data at kilobase resolution. Nat Genet 2022; 54:1013-1025. [PMID: 35817982 PMCID: PMC10082397 DOI: 10.1038/s41588-022-01116-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Accepted: 05/30/2022] [Indexed: 11/09/2022]
Abstract
Mapping chromatin loops from noisy Hi-C heatmaps remains a major challenge. Here we present DeepLoop, which performs rigorous bias correction followed by deep-learning-based signal enhancement for robust chromatin interaction mapping from low-depth Hi-C data. DeepLoop enables loop-resolution, single-cell Hi-C analysis. It also achieves a cross-platform convergence between different Hi-C protocols and micrococcal nuclease (micro-C). DeepLoop allowed us to map the genetic and epigenetic determinants of allele-specific chromatin interactions in the human genome. We nominate new loci with allele-specific interactions governed by imprinting or allelic DNA methylation. We also discovered that, in the inactivated X chromosome (Xi), local loops at the DXZ4 'megadomain' boundary escape X-inactivation but the FIRRE 'superloop' locus does not. Importantly, DeepLoop can pinpoint heterozygous single-nucleotide polymorphisms and large structure variants that cause allelic chromatin loops, many of which rewire enhancers with transcription consequences. Taken together, DeepLoop expands the use of Hi-C to provide loop-resolution insights into the genetics of the three-dimensional genome.
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Affiliation(s)
- Shanshan Zhang
- Department of Genetics and Genome Sciences, School of Medicine, Case Western Reserve University, Cleveland, OH, USA.,The Biomedical Sciences Training Program, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - Dylan Plummer
- Department of Computer and Data Sciences, Case Western Reserve University, Cleveland, OH, USA
| | - Leina Lu
- Department of Genetics and Genome Sciences, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - Jian Cui
- Department of Genetics and Genome Sciences, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - Wanying Xu
- Department of Genetics and Genome Sciences, School of Medicine, Case Western Reserve University, Cleveland, OH, USA.,The Biomedical Sciences Training Program, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - Miao Wang
- Department of Biological Science, Florida State University, Tallahassee, FL, USA
| | - Xiaoxiao Liu
- Department of Genetics and Genome Sciences, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - Nachiketh Prabhakar
- Department of Computer and Data Sciences, Case Western Reserve University, Cleveland, OH, USA
| | - Jatin Shrinet
- Department of Biological Science, Florida State University, Tallahassee, FL, USA
| | - Divyaa Srinivasan
- Department of Biological Science, Florida State University, Tallahassee, FL, USA
| | - Peter Fraser
- Department of Biological Science, Florida State University, Tallahassee, FL, USA
| | - Yan Li
- Department of Genetics and Genome Sciences, School of Medicine, Case Western Reserve University, Cleveland, OH, USA.
| | - Jing Li
- Department of Computer and Data Sciences, Case Western Reserve University, Cleveland, OH, USA. .,Department of Population and Quantitative Health Sciences, Case Comprehensive Cancer Center, Case Western Reserve University, Cleveland, OH, USA.
| | - Fulai Jin
- Department of Genetics and Genome Sciences, School of Medicine, Case Western Reserve University, Cleveland, OH, USA. .,Department of Computer and Data Sciences, Case Western Reserve University, Cleveland, OH, USA. .,Department of Population and Quantitative Health Sciences, Case Comprehensive Cancer Center, Case Western Reserve University, Cleveland, OH, USA.
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27
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Deshpande AS, Ulahannan N, Pendleton M, Dai X, Ly L, Behr JM, Schwenk S, Liao W, Augello MA, Tyer C, Rughani P, Kudman S, Tian H, Otis HG, Adney E, Wilkes D, Mosquera JM, Barbieri CE, Melnick A, Stoddart D, Turner DJ, Juul S, Harrington E, Imieliński M. Identifying synergistic high-order 3D chromatin conformations from genome-scale nanopore concatemer sequencing. Nat Biotechnol 2022; 40:1488-1499. [DOI: 10.1038/s41587-022-01289-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2020] [Accepted: 03/16/2022] [Indexed: 12/28/2022]
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28
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Dossin F, Heard E. The Molecular and Nuclear Dynamics of X-Chromosome Inactivation. Cold Spring Harb Perspect Biol 2022; 14:a040196. [PMID: 34312245 PMCID: PMC9121902 DOI: 10.1101/cshperspect.a040196] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
In female eutherian mammals, dosage compensation of X-linked gene expression is achieved during development through transcriptional silencing of one of the two X chromosomes. Following X chromosome inactivation (XCI), the inactive X chromosome remains faithfully silenced throughout somatic cell divisions. XCI is dependent on Xist, a long noncoding RNA that coats and silences the X chromosome from which it is transcribed. Xist coating triggers a cascade of chromosome-wide changes occurring at the levels of transcription, chromatin composition, chromosome structure, and spatial organization within the nucleus. XCI has emerged as a paradigm for the study of such crucial nuclear processes and the dissection of their functional interplay. In the past decade, the advent of tools to characterize and perturb these processes have provided an unprecedented understanding into their roles during XCI. The mechanisms orchestrating the initiation of XCI as well as its maintenance are thus being unraveled, although many questions still remain. Here, we introduce key aspects of the XCI process and review the recent discoveries about its molecular basis.
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Affiliation(s)
- François Dossin
- European Molecular Biology Laboratory, Director's Unit, 69117 Heidelberg, Germany
| | - Edith Heard
- European Molecular Biology Laboratory, Director's Unit, 69117 Heidelberg, Germany
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29
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The 4D Nucleome Data Portal as a resource for searching and visualizing curated nucleomics data. Nat Commun 2022; 13:2365. [PMID: 35501320 PMCID: PMC9061818 DOI: 10.1038/s41467-022-29697-4] [Citation(s) in RCA: 37] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2021] [Accepted: 03/28/2022] [Indexed: 01/03/2023] Open
Abstract
The 4D Nucleome (4DN) Network aims to elucidate the complex structure and organization of chromosomes in the nucleus and the impact of their disruption in disease biology. We present the 4DN Data Portal (https://data.4dnucleome.org/), a repository for datasets generated in the 4DN network and relevant external datasets. Datasets were generated with a wide range of experiments, including chromosome conformation capture assays such as Hi-C and other innovative sequencing and microscopy-based assays probing chromosome architecture. All together, the 4DN data portal hosts more than 1800 experiment sets and 36000 files. Results of sequencing-based assays from different laboratories are uniformly processed and quality-controlled. The portal interface allows easy browsing, filtering, and bulk downloads, and the integrated HiGlass genome browser allows interactive visualization and comparison of multiple datasets. The 4DN data portal represents a primary resource for chromosome contact and other nuclear architecture data for the scientific community. This paper describes the ‘4DN Data Portal’ that hosts data generated by the 4D Nucleome network, including Hi-C and other chromatin conformation capture assays, as well as various sequencing-based and imaging-based assays. Raw data have been uniformly processed to increase comparability and the portal is implemented with visualization tools to browse the data without download.
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30
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Lentini A, Cheng H, Noble JC, Papanicolaou N, Coucoravas C, Andrews N, Deng Q, Enge M, Reinius B. Elastic dosage compensation by X-chromosome upregulation. Nat Commun 2022; 13:1854. [PMID: 35388014 PMCID: PMC8987076 DOI: 10.1038/s41467-022-29414-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Accepted: 03/14/2022] [Indexed: 12/24/2022] Open
Abstract
X-chromosome inactivation and X-upregulation are the fundamental modes of chromosome-wide gene regulation that collectively achieve dosage compensation in mammals, but the regulatory link between the two remains elusive and the X-upregulation dynamics are unknown. Here, we use allele-resolved single-cell RNA-seq combined with chromatin accessibility profiling and finely dissect their separate effects on RNA levels during mouse development. Surprisingly, we uncover that X-upregulation elastically tunes expression dosage in a sex- and lineage-specific manner, and moreover along varying degrees of X-inactivation progression. Male blastomeres achieve X-upregulation upon zygotic genome activation while females experience two distinct waves of upregulation, upon imprinted and random X-inactivation; and ablation of Xist impedes female X-upregulation. Female cells carrying two active X chromosomes lack upregulation, yet their collective RNA output exceeds that of a single hyperactive allele. Importantly, this conflicts the conventional dosage compensation model in which naïve female cells are initially subject to biallelic X-upregulation followed by X-inactivation of one allele to correct the X dosage. Together, our study provides key insights to the chain of events of dosage compensation, explaining how transcript copy numbers can remain remarkably stable across developmental windows wherein severe dose imbalance would otherwise be experienced by the cell.
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Affiliation(s)
- Antonio Lentini
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Huaitao Cheng
- Department of Oncology and Pathology, Karolinska Institutet, Stockholm, Sweden
| | - J C Noble
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Natali Papanicolaou
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Christos Coucoravas
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Nathanael Andrews
- Department of Oncology and Pathology, Karolinska Institutet, Stockholm, Sweden
| | - Qiaolin Deng
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
| | - Martin Enge
- Department of Oncology and Pathology, Karolinska Institutet, Stockholm, Sweden
| | - Björn Reinius
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden.
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31
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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: 45] [Impact Index Per Article: 22.5] [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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32
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BAF complex-mediated chromatin relaxation is required for establishment of X chromosome inactivation. Nat Commun 2022; 13:1658. [PMID: 35351876 PMCID: PMC8964718 DOI: 10.1038/s41467-022-29333-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2021] [Accepted: 03/10/2022] [Indexed: 12/12/2022] Open
Abstract
The process of epigenetic silencing, while fundamentally important, is not yet completely understood. Here we report a replenishable female mouse embryonic stem cell (mESC) system, Xmas, that allows rapid assessment of X chromosome inactivation (XCI), the epigenetic silencing mechanism of one of the two X chromosomes that enables dosage compensation in female mammals. Through a targeted genetic screen in differentiating Xmas mESCs, we reveal that the BAF complex is required to create nucleosome-depleted regions at promoters on the inactive X chromosome during the earliest stages of establishment of XCI. Without this action gene silencing fails. Xmas mESCs provide a tractable model for screen-based approaches that enable the discovery of unknown facets of the female-specific process of XCI and epigenetic silencing more broadly. Female embryonic stem cells (ESCs) are the ideal model to study X chromosome inactivation (XCI) establishment; however, these cells are challenging to keep in culture. Here the authors create fluorescent ‘Xmas’ reporter mice as a renewable source of ESCs and show nucleosome remodelers Smarcc1 and Smarca4 create a nucleosome-free promoter region prior to the establishment of silencing.
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33
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Abstract
We found the three-dimensional (3D) structure of chromatin at the chromosome level to be highly conserved for more than 50 million y of carnivore evolution. Intrachromosomal contacts were maintained even after chromosome rearrangements within carnivore lineages, demonstrating that the maintenance of 3D chromatin architecture is essential for conserved genome functions. These discoveries enabled the identification of orthologous chromosomal DNA segments among related species, a method we call 3D comparative scaffotyping. The method has application for putative chromosome assignment of chromosome-scale DNA sequence scaffolds produced by de novo genome sequencing. Broadly applied to biodiversity genome sequencing efforts, the approach can reduce costs associated with karyotyping and the physical mapping of DNA segments to chromosomes. High throughput chromatin conformation capture (Hi-C) of leukocyte DNA was used to investigate the evolutionary stability of chromatin conformation at the chromosomal level in 11 species from three carnivore families: Felidae, Canidae, and Ursidae. Chromosome-scale scaffolds (C-scaffolds) of each species were initially used for whole-genome alignment to a reference genome within each family. This approach established putative orthologous relationships between C-scaffolds among the different species. Hi-C contact maps for all C-scaffolds were then visually compared and found to be distinct for a given reference chromosome or C-scaffold within a species and indistinguishable for orthologous C-scaffolds having a 1:1 relationship within a family. The visual patterns within families were strongly supported by eigenvectors from the Hi-C contact maps. Analysis of Hi-C contact maps and eigenvectors across the three carnivore families revealed that most cross-family orthologous subchromosomal fragments have a conserved three-dimensional (3D) chromatin structure and thus have been under strong evolutionary constraint for ∼54 My of carnivore evolution. The most pronounced differences in chromatin conformation were observed for the X chromosome and the red fox genome, whose chromosomes have undergone extensive rearrangements relative to other canids. We also demonstrate that Hi-C contact map pattern analysis can be used to accurately identify orthologous relationships between C-scaffolds and chromosomes, a method we termed “3D comparative scaffotyping.” This method provides a powerful means for estimating karyotypes in de novo sequenced species that have unknown karyotype and no physical mapping information.
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34
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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: 80] [Impact Index Per Article: 40.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/18/2021] [Indexed: 12/21/2022]
Abstract
X-chromosome inactivation (XCI) is the epigenetic mechanism that ensures X-linked dosage compensation between cells of females (XX karyotype) and males (XY). XCI is essential for female embryos to survive through development and requires the accurate spatiotemporal regulation of many different factors to achieve remarkable chromosome-wide gene silencing. As a result of XCI, the active and inactive X chromosomes are functionally and structurally different, with the inactive X chromosome undergoing a major conformational reorganization within the nucleus. In this Review, we discuss the multiple layers of genetic and epigenetic regulation that underlie initiation of XCI during development and then maintain it throughout life, in light of the most recent findings in this rapidly advancing field. We discuss exciting new insights into the regulation of X inactive-specific transcript (XIST), the trigger and master regulator of XCI, and into the mechanisms and dynamics that underlie the silencing of nearly all X-linked genes. Finally, given the increasing interest in understanding the impact of chromosome organization on gene regulation, we provide an overview of the factors that are thought to reshape the 3D structure of the inactive X chromosome and of the relevance of such structural changes for XCI establishment and maintenance.
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35
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Alavattam KG, Maezawa S, Andreassen PR, Namekawa SH. Meiotic sex chromosome inactivation and the XY body: a phase separation hypothesis. Cell Mol Life Sci 2021; 79:18. [PMID: 34971404 DOI: 10.1007/s00018-021-04075-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Revised: 09/08/2021] [Accepted: 10/14/2021] [Indexed: 10/19/2022]
Abstract
In mammalian male meiosis, the heterologous X and Y chromosomes remain unsynapsed and, as a result, are subject to meiotic sex chromosome inactivation (MSCI). MSCI is required for the successful completion of spermatogenesis. Following the initiation of MSCI, the X and Y chromosomes undergo various epigenetic modifications and are transformed into a nuclear body termed the XY body. Here, we review the mechanisms underlying the initiation of two essential, sequential processes in meiotic prophase I: MSCI and XY-body formation. The initiation of MSCI is directed by the action of DNA damage response (DDR) pathways; downstream of the DDR, unique epigenetic states are established, leading to the formation of the XY body. Accumulating evidence suggests that MSCI and subsequent XY-body formation may be driven by phase separation, a physical process that governs the formation of membraneless organelles and other biomolecular condensates. Thus, here we gather literature-based evidence to explore a phase separation hypothesis for the initiation of MSCI and the formation of the XY body.
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Affiliation(s)
- Kris G Alavattam
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA, 98195, USA.,Center for Cardiovascular Biology, University of Washington, Seattle, WA, 98109, USA.,Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA, 98109, USA.,Department of Genome Sciences, University of Washington, Seattle, WA, 98195, USA
| | - So Maezawa
- Faculty of Science and Technology, Department of Applied Biological Science, Tokyo University of Science, Chiba, 278-8510, Japan
| | - Paul R Andreassen
- Division of Experimental Hematology and Cancer Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, 45229, USA
| | - Satoshi H Namekawa
- Department of Microbiology and Molecular Genetics, University of California, Davis, CA, 95616, USA.
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36
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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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37
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Cheng Y, Liu M, Hu M, Wang S. TAD-like single-cell domain structures exist on both active and inactive X chromosomes and persist under epigenetic perturbations. Genome Biol 2021; 22:309. [PMID: 34749781 PMCID: PMC8574027 DOI: 10.1186/s13059-021-02523-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Accepted: 10/22/2021] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND Topologically associating domains (TADs) are important building blocks of three-dimensional genome architectures. The formation of TADs has been shown to depend on cohesin in a loop-extrusion mechanism. Recently, advances in an image-based spatial genomics technique known as chromatin tracing lead to the discovery of cohesin-independent TAD-like structures, also known as single-cell domains, which are highly variant self-interacting chromatin domains with boundaries that occasionally overlap with TAD boundaries but tend to differ among single cells and among single chromosome copies. Recent computational modeling studies suggest that epigenetic interactions may underlie the formation of the single-cell domains. RESULTS Here we use chromatin tracing to visualize in female human cells the fine-scale chromatin folding of inactive and active X chromosomes, which are known to have distinct global epigenetic landscapes and distinct population-averaged TAD profiles, with inactive X chromosomes largely devoid of TADs and cohesin. We show that both inactive and active X chromosomes possess highly variant single-cell domains across the same genomic region despite the fact that only active X chromosomes show clear TAD structures at the population level. These X chromosome single-cell domains exist in distinct cell lines. Perturbations of major epigenetic components and transcription mostly do not affect the frequency or strength of the single-cell domains. Increased chromatin compaction of inactive X chromosomes occurs at a length scale above that of the single-cell domains. CONCLUSIONS In sum, this study suggests that single-cell domains are genome architecture building blocks independent of the tested major epigenetic components.
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Affiliation(s)
- Yubao Cheng
- Department of Genetics, Yale School of Medicine, Yale University, New Haven, CT 06510 USA
| | - Miao Liu
- Department of Genetics, Yale School of Medicine, Yale University, New Haven, CT 06510 USA
| | - Mengwei Hu
- Department of Genetics, Yale School of Medicine, Yale University, New Haven, CT 06510 USA
| | - Siyuan Wang
- Department of Genetics, Yale School of Medicine, Yale University, New Haven, CT 06510 USA
- Department of Cell Biology, Yale School of Medicine, Yale University, New Haven, CT 06510 USA
- Yale Combined Program in the Biological and Biomedical Sciences, Yale University, New Haven, CT 06510 USA
- Molecular Cell Biology, Genetics and Development Program, Yale University, New Haven, CT 06510 USA
- Biochemistry, Quantitative Biology, Biophysics and Structural Biology Program, Yale University, New Haven, CT 06510 USA
- M.D.-Ph.D. Program, Yale University, New Haven, CT 06510 USA
- Yale Center for RNA Science and Medicine, Yale University School of Medicine, New Haven, CT 06510 USA
- Yale Liver Center, Yale University School of Medicine, New Haven, CT 06510 USA
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38
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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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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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40
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Jerkovic I, Cavalli G. Understanding 3D genome organization by multidisciplinary methods. Nat Rev Mol Cell Biol 2021; 22:511-528. [PMID: 33953379 DOI: 10.1038/s41580-021-00362-w] [Citation(s) in RCA: 139] [Impact Index Per Article: 46.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/16/2021] [Indexed: 02/03/2023]
Abstract
Understanding how chromatin is folded in the nucleus is fundamental to understanding its function. Although 3D genome organization has been historically difficult to study owing to a lack of relevant methodologies, major technological breakthroughs in genome-wide mapping of chromatin contacts and advances in imaging technologies in the twenty-first century considerably improved our understanding of chromosome conformation and nuclear architecture. In this Review, we discuss methods of 3D genome organization analysis, including sequencing-based techniques, such as Hi-C and its derivatives, Micro-C, DamID and others; microscopy-based techniques, such as super-resolution imaging coupled with fluorescence in situ hybridization (FISH), multiplex FISH, in situ genome sequencing and live microscopy methods; and computational and modelling approaches. We describe the most commonly used techniques and their contribution to our current knowledge of nuclear architecture and, finally, we provide a perspective on up-and-coming methods that open possibilities for future major discoveries.
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Affiliation(s)
- Ivana Jerkovic
- Institute of Human Genetics, CNRS, University of Montpellier, Montpellier, France
| | - Giacomo Cavalli
- Institute of Human Genetics, CNRS, University of Montpellier, Montpellier, France.
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41
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CTCF chromatin residence time controls three-dimensional genome organization, gene expression and DNA methylation in pluripotent cells. Nat Cell Biol 2021; 23:881-893. [PMID: 34326481 DOI: 10.1038/s41556-021-00722-w] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Accepted: 06/24/2021] [Indexed: 12/12/2022]
Abstract
The 11 zinc finger (ZF) protein CTCF regulates topologically associating domain formation and transcription through selective binding to thousands of genomic sites. Here, we replaced endogenous CTCF in mouse embryonic stem cells with green-fluorescent-protein-tagged wild-type or mutant proteins lacking individual ZFs to identify additional determinants of CTCF positioning and function. While ZF1 and ZF8-ZF11 are not essential for cell survival, ZF8 deletion strikingly increases the DNA binding off-rate of mutant CTCF, resulting in reduced CTCF chromatin residence time. Loss of ZF8 results in widespread weakening of topologically associating domains, aberrant gene expression and increased genome-wide DNA methylation. Thus, important chromatin-templated processes rely on accurate CTCF chromatin residence time, which we propose depends on local sequence and chromatin context as well as global CTCF protein concentration.
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42
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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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43
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Kawashima S, Hattori A, Suzuki E, Matsubara K, Toki M, Kosaki R, Hasegawa Y, Nakabayashi K, Fukami M, Kagami M. Methylation status of genes escaping from X-chromosome inactivation in patients with X-chromosome rearrangements. Clin Epigenetics 2021; 13:134. [PMID: 34193245 PMCID: PMC8244138 DOI: 10.1186/s13148-021-01121-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Accepted: 06/22/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND X-chromosome inactivation (XCI) is a mechanism in which one of two X chromosomes in females is randomly inactivated in order to compensate for imbalance of gene dosage between sexes. However, about 15% of genes on the inactivated X chromosome (Xi) escape from XCI. The methylation level of the promoter region of the escape gene is lower than that of the inactivated genes. Dxz4 and/or Firre have critical roles for forming the three-dimensional (3D) structure of Xi. In mice, disrupting the 3D structure of Xi by deleting both Dxz4 and Firre genes led to changing of the escape genes list. To estimate the impact for escape genes by X-chromosome rearrangements, including DXZ4 and FIRRE, we examined the methylation status of escape gene promoters in patients with various X-chromosome rearrangements. RESULTS To detect the breakpoints, we first performed array-based comparative genomic hybridization and whole-genome sequencing in four patients with X-chromosome rearrangements. Subsequently, we conducted array-based methylation analysis and reduced representation bisulfite sequencing in the four patients with X-chromosome rearrangements and controls. Of genes reported as escape genes by gene expression analysis using human hybrid cells in a previous study, 32 genes showed hypomethylation of the promoter region in both male controls and female controls. Three patients with X-chromosome rearrangements had no escape genes with abnormal methylation of the promoter region. One of four patients with the most complicated rearrangements exhibited abnormal methylation in three escape genes. Furthermore, in the patient with the deletion of the FIRRE gene and the duplication of DXZ4, most escape genes remained hypomethylated. CONCLUSION X-chromosome rearrangements are unlikely to affect the methylation status of the promoter regions of escape genes, except for a specific case with highly complex rearrangements, including the deletion of the FIRRE gene and the duplication of DXZ4.
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Affiliation(s)
- Sayaka Kawashima
- Department of Molecular Endocrinology, National Research Institute for Child Health and Development, 2-10-1 Okura, Setagaya-ku, Tokyo, 157-8535, Japan.,Department of Pediatrics, Tohoku University School of Medicine, 1-1 Seiryomachi, Aobaku, Sendai, Miyagi, 980-8574, Japan
| | - Atsushi Hattori
- Department of Molecular Endocrinology, National Research Institute for Child Health and Development, 2-10-1 Okura, Setagaya-ku, Tokyo, 157-8535, Japan
| | - Erina Suzuki
- Department of Molecular Endocrinology, National Research Institute for Child Health and Development, 2-10-1 Okura, Setagaya-ku, Tokyo, 157-8535, Japan
| | - Keiko Matsubara
- Department of Molecular Endocrinology, National Research Institute for Child Health and Development, 2-10-1 Okura, Setagaya-ku, Tokyo, 157-8535, Japan
| | - Machiko Toki
- Department of Pediatrics, Hiratsuka City Hospital, 1-19-1 Minamihara, Hiratsuka, Kanagawa, 254-0065, Japan.,Department of Pediatrics, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582, Japan
| | - Rika Kosaki
- Division of Medical Genetics, National Center for Child Health and Development, 2-10-1 Okura, Setagaya-ku, Tokyo, 157-8535, Japan
| | - Yukihiro Hasegawa
- Division of Endocrinology and Metabolism, Tokyo Metropolitan Children's Medical Center, 2-8-29 Musashidai, Fuchu, Tokyo, 183-8561, Japan
| | - Kazuhiko Nakabayashi
- Department of Maternal Fetal Biology, National Research Institute for Child Health and Development, 2-10-1 Okura, Setagaya-ku, Tokyo, 157-8535, Japan
| | - Maki Fukami
- Department of Molecular Endocrinology, National Research Institute for Child Health and Development, 2-10-1 Okura, Setagaya-ku, Tokyo, 157-8535, Japan
| | - Masayo Kagami
- Department of Molecular Endocrinology, National Research Institute for Child Health and Development, 2-10-1 Okura, Setagaya-ku, Tokyo, 157-8535, Japan.
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44
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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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45
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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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46
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The dynamic epigenetic regulation of the inactive X chromosome in healthy human B cells is dysregulated in lupus patients. Proc Natl Acad Sci U S A 2021; 118:2024624118. [PMID: 34103397 DOI: 10.1073/pnas.2024624118] [Citation(s) in RCA: 46] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Systemic lupus erythematous (SLE) is a female-predominant disease characterized by autoimmune B cells and pathogenic autoantibody production. Individuals with two or more X chromosomes are at increased risk for SLE, suggesting that X-linked genes contribute to the observed sex bias of this disease. To normalize X-linked gene expression between sexes, one X in female cells is randomly selected for transcriptional silencing through X-chromosome inactivation (XCI), resulting in allele-specific enrichment of epigenetic modifications, including histone methylation and the long noncoding RNA XIST/Xist on the inactive X (Xi). As we have previously shown that epigenetic regulation of the Xi in female lymphocytes from mice is unexpectedly dynamic, we used RNA fluorescence in situ hybridization and immunofluorescence to profile epigenetic features of the Xi at the single-cell level in human B cell subsets from pediatric and adult SLE patients and healthy controls. Our data reveal that abnormal XCI maintenance in B cells is a feature of SLE. Using single-cell and bulk-cell RNA sequencing datasets, we found that X-linked immunity genes escape XCI in specific healthy human B cell subsets and that human SLE B cells exhibit aberrant expression of X-linked genes and XIST RNA interactome genes. Our data reveal that mislocalized XIST RNA, coupled with a dramatic reduction in heterochromatic modifications at the Xi in SLE, predispose for aberrant X-linked gene expression from the Xi, thus defining a genetic and epigenetic pathway that affects X-linked gene expression in human SLE B cells and likely contributes to the female bias in SLE.
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47
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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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48
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Fernandes N, Buchan JR. RNAs as Regulators of Cellular Matchmaking. Front Mol Biosci 2021; 8:634146. [PMID: 33898516 PMCID: PMC8062979 DOI: 10.3389/fmolb.2021.634146] [Citation(s) in RCA: 6] [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: 11/27/2020] [Accepted: 02/22/2021] [Indexed: 12/30/2022] Open
Abstract
RNA molecules are increasingly being identified as facilitating or impeding the interaction of proteins and nucleic acids, serving as so-called scaffolds or decoys. Long non-coding RNAs have been commonly implicated in such roles, particularly in the regulation of nuclear processes including chromosome topology, regulation of chromatin state and gene transcription, and assembly of nuclear biomolecular condensates such as paraspeckles. Recently, an increased awareness of cytoplasmic RNA scaffolds and decoys has begun to emerge, including the identification of non-coding regions of mRNAs that can also function in a scaffold-like manner to regulate interactions of nascently translated proteins. Collectively, cytoplasmic RNA scaffolds and decoys are now implicated in processes such as mRNA translation, decay, protein localization, protein degradation and assembly of cytoplasmic biomolecular condensates such as P-bodies. Here, we review examples of RNA scaffolds and decoys in both the nucleus and cytoplasm, illustrating common themes, the suitability of RNA to such roles, and future challenges in identifying and better understanding RNA scaffolding and decoy functions.
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Affiliation(s)
| | - J. Ross Buchan
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, AZ, United States
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49
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Sas-Nowosielska H, Magalska A. Long Noncoding RNAs-Crucial Players Organizing the Landscape of the Neuronal Nucleus. Int J Mol Sci 2021; 22:ijms22073478. [PMID: 33801737 PMCID: PMC8037058 DOI: 10.3390/ijms22073478] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Revised: 03/22/2021] [Accepted: 03/24/2021] [Indexed: 12/25/2022] Open
Abstract
The ability to regulate chromatin organization is particularly important in neurons, which dynamically respond to external stimuli. Accumulating evidence shows that lncRNAs play important architectural roles in organizing different nuclear domains like inactive chromosome X, splicing speckles, paraspeckles, and Gomafu nuclear bodies. LncRNAs are abundantly expressed in the nervous system where they may play important roles in compartmentalization of the cell nucleus. In this review we will describe the architectural role of lncRNAs in the nuclei of neuronal cells.
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50
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Abstract
The recent Coronavirus Disease 2019 pandemic has once again reminded us the importance of understanding infectious diseases. One important but understudied area in infectious disease research is the role of nuclear architecture or the physical arrangement of the genome in the nucleus in controlling gene regulation and pathogenicity. Recent advances in research methods, such as Genome-wide chromosome conformation capture using high-throughput sequencing (Hi-C), have allowed for easier analysis of nuclear architecture and chromosomal reorganization in both the infectious disease agents themselves as well as in their host cells. This review will discuss broadly on what is known about nuclear architecture in infectious disease, with an emphasis on chromosomal reorganization, and briefly discuss what steps are required next in the field. In this review, we examine the current state of nuclear architecture in infectious diseases with an emphasis on chromosomal reorganization. Nuclear architecture plays an important role in regulation of transcription for several pathogens, as well as inflammatory responses in their host. Recent advances in technologies such as Hi-C have allowed in-depth studies of chromosomal reorganization during infectious disease development and provided insights into transcription mechanisms and pathogenicity. In addition, it has been demonstrated that pathogens can also affect/utilize the hosts nuclear architecture. These areas are heavily understudied in pathogens, and we hope this review will provide a comprehensive review on the current state of nuclear architecture in infectious diseases and provide an additional avenue for eradication efforts.
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