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Wen X, Luo Z, Zhao W, Calandrelli R, Nguyen TC, Wan X, Richard JLC, Zhong S. Single-cell multiplex chromatin and RNA interactions in aging human brain. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.06.28.546457. [PMID: 37425846 PMCID: PMC10326989 DOI: 10.1101/2023.06.28.546457] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/11/2023]
Abstract
The dynamically organized chromatin complexes often involve multiplex chromatin interactions and sometimes chromatin-associated RNA (caRNA) 1-3. Chromatin complex compositions change during cellular differentiation and aging, and are expected to be highly heterogeneous among terminally differentiated single cells 4-7. Here we introduce the Multi-Nucleic Acid Interaction Mapping in Single Cell (MUSIC) technique for concurrent profiling of multiplex chromatin interactions, gene expression, and RNA-chromatin associations within individual nuclei. Applied to 14 human frontal cortex samples from elderly donors, MUSIC delineates diverse cortical cell types and states. We observed the nuclei exhibiting fewer short-range chromatin interactions are correlated with an "older" transcriptomic signature and with Alzheimer's pathology. Furthermore, the cell type exhibiting chromatin contacts between cis expression quantitative trait loci (cis eQTLs) and a promoter tends to be the cell type where these cis eQTLs specifically affect their target gene's expression. Additionally, the female cortical cells exhibit highly heterogeneous interactions between the XIST non-coding RNA and Chromosome X, along with diverse spatial organizations of the X chromosomes. MUSIC presents a potent tool for exploring chromatin architecture and transcription at cellular resolution in complex tissues.
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Affiliation(s)
- Xingzhao Wen
- Program in Bioinformatics and Systems Biology, University of California San Diego, La Jolla, CA 92093, USA
| | - Zhifei Luo
- Shu Chien-Gene Lay Department of Bioengineering, University of California San Diego, La Jolla, CA 92093, USA
| | - Wenxin Zhao
- Shu Chien-Gene Lay Department of Bioengineering, University of California San Diego, La Jolla, CA 92093, USA
| | - Riccardo Calandrelli
- Institute of Engineering in Medicine, University of California San Diego, La Jolla, CA 92093, USA
| | - Tri C. Nguyen
- Shu Chien-Gene Lay Department of Bioengineering, University of California San Diego, La Jolla, CA 92093, USA
| | - Xueyi Wan
- Shu Chien-Gene Lay Department of Bioengineering, University of California San Diego, La Jolla, CA 92093, USA
| | | | - Sheng Zhong
- Program in Bioinformatics and Systems Biology, University of California San Diego, La Jolla, CA 92093, USA
- Shu Chien-Gene Lay Department of Bioengineering, University of California San Diego, La Jolla, CA 92093, USA
- Institute of Engineering in Medicine, University of California San Diego, La Jolla, CA 92093, USA
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2
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Calandrelli R, Wen X, Charles Richard JL, Luo Z, Nguyen TC, Chen CJ, Qi Z, Xue S, Chen W, Yan Z, Wu W, Zaleta-Rivera K, Hu R, Yu M, Wang Y, Li W, Ma J, Ren B, Zhong S. Genome-wide analysis of the interplay between chromatin-associated RNA and 3D genome organization in human cells. Nat Commun 2023; 14:6519. [PMID: 37845234 PMCID: PMC10579264 DOI: 10.1038/s41467-023-42274-7] [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: 05/17/2023] [Accepted: 10/05/2023] [Indexed: 10/18/2023] Open
Abstract
The interphase genome is dynamically organized in the nucleus and decorated with chromatin-associated RNA (caRNA). It remains unclear whether the genome architecture modulates the spatial distribution of caRNA and vice versa. Here, we generate a resource of genome-wide RNA-DNA and DNA-DNA contact maps in human cells. These maps reveal the chromosomal domains demarcated by locally transcribed RNA, hereafter termed RNA-defined chromosomal domains. Further, the spreading of caRNA is constrained by the boundaries of topologically associating domains (TADs), demonstrating the role of the 3D genome structure in modulating the spatial distribution of RNA. Conversely, stopping transcription or acute depletion of RNA induces thousands of chromatin loops genome-wide. Activation or suppression of the transcription of specific genes suppresses or creates chromatin loops straddling these genes. Deletion of a specific caRNA-producing genomic sequence promotes chromatin loops that straddle the interchromosomal target sequences of this caRNA. These data suggest a feedback loop where the 3D genome modulates the spatial distribution of RNA, which in turn affects the dynamic 3D genome organization.
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Affiliation(s)
- Riccardo Calandrelli
- Shu Chien-Gene Lay Department of Bioengineering, University of California San Diego, La Jolla, CA, USA
| | - Xingzhao Wen
- Bioinformatics and Systems Biology Program, University of California San Diego, La Jolla, CA, USA
| | | | - Zhifei Luo
- Shu Chien-Gene Lay Department of Bioengineering, University of California San Diego, La Jolla, CA, USA
| | - Tri C Nguyen
- Shu Chien-Gene Lay Department of Bioengineering, University of California San Diego, La Jolla, CA, USA
| | - Chien-Ju Chen
- Bioinformatics and Systems Biology Program, University of California San Diego, La Jolla, CA, USA
| | - Zhijie Qi
- Shu Chien-Gene Lay Department of Bioengineering, University of California San Diego, La Jolla, CA, USA
| | - Shuanghong Xue
- Shu Chien-Gene Lay Department of Bioengineering, University of California San Diego, La Jolla, CA, USA
| | - Weizhong Chen
- Shu Chien-Gene Lay Department of Bioengineering, University of California San Diego, La Jolla, CA, USA
| | - Zhangming Yan
- Shu Chien-Gene Lay Department of Bioengineering, University of California San Diego, La Jolla, CA, USA
| | - Weixin Wu
- Shu Chien-Gene Lay Department of Bioengineering, University of California San Diego, La Jolla, CA, USA
| | - Kathia Zaleta-Rivera
- Shu Chien-Gene Lay Department of Bioengineering, University of California San Diego, La Jolla, CA, USA
| | - Rong Hu
- Department of Cellular and Molecular Medicine, Center for Epigenomics, University of California San Diego, La Jolla, CA, USA
- Ludwig Institute for Cancer Research, La Jolla, CA, USA
| | - Miao Yu
- Ludwig Institute for Cancer Research, La Jolla, CA, USA
| | - Yuchuan Wang
- Computational Biology Department, School of Computer Science, Carnegie Mellon University, Pittsburgh, PA, USA
| | - Wenbo Li
- Department of Biochemistry and Molecular Biology, McGovern Medical School, University of Texas Health Science Center, Houston, TX, USA
| | - Jian Ma
- Computational Biology Department, School of Computer Science, Carnegie Mellon University, Pittsburgh, PA, USA
| | - Bing Ren
- Department of Cellular and Molecular Medicine, Center for Epigenomics, University of California San Diego, La Jolla, CA, USA
- Ludwig Institute for Cancer Research, La Jolla, CA, USA
| | - Sheng Zhong
- Shu Chien-Gene Lay Department of Bioengineering, University of California San Diego, La Jolla, CA, USA.
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3
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Di Nunzio F, Uversky VN, Mouland AJ. Biomolecular condensates: insights into early and late steps of the HIV-1 replication cycle. Retrovirology 2023; 20:4. [PMID: 37029379 PMCID: PMC10081342 DOI: 10.1186/s12977-023-00619-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Accepted: 03/16/2023] [Indexed: 04/09/2023] Open
Abstract
A rapidly evolving understanding of phase separation in the biological and physical sciences has led to the redefining of virus-engineered replication compartments in many viruses with RNA genomes. Condensation of viral, host and genomic and subgenomic RNAs can take place to evade the innate immunity response and to help viral replication. Divergent viruses prompt liquid-liquid phase separation (LLPS) to invade the host cell. During HIV replication there are several steps involving LLPS. In this review, we characterize the ability of individual viral and host partners that assemble into biomolecular condensates (BMCs). Of note, bioinformatic analyses predict models of phase separation in line with several published observations. Importantly, viral BMCs contribute to function in key steps retroviral replication. For example, reverse transcription takes place within nuclear BMCs, called HIV-MLOs while during late replication steps, retroviral nucleocapsid acts as a driver or scaffold to recruit client viral components to aid the assembly of progeny virions. Overall, LLPS during viral infections represents a newly described biological event now appreciated in the virology field, that can also be considered as an alternative pharmacological target to current drug therapies especially when viruses become resistant to antiviral treatment.
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Affiliation(s)
- Francesca Di Nunzio
- Advanced Molecular Virology Unit, Department of Virology, Institut Pasteur, Université Paris Cité, 75015, Paris, France
| | - Vladimir N Uversky
- Department of Molecular Medicine and USF Health Byrd Alzheimer's Research Institute, Morsani College of Medicine, University of South Florida, Tampa, FL, 33612, USA
| | - Andrew J Mouland
- Lady Davis Institute at the Jewish General Hospital, Montréal, QC, H3T 1E2, Canada.
- Department of Microbiology and Immunology, McGill University, Montréal, QC, H3A 2B4, Canada.
- Department of Medicine, McGill University, Montréal, QC, H4A 3J1, Canada.
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4
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Li X, An Z, Zhang W, Li F. Phase Separation: Direct and Indirect Driving Force for High-Order Chromatin Organization. Genes (Basel) 2023; 14:499. [PMID: 36833426 PMCID: PMC9956262 DOI: 10.3390/genes14020499] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2023] [Revised: 02/09/2023] [Accepted: 02/14/2023] [Indexed: 02/18/2023] Open
Abstract
The multi-level spatial chromatin organization in the nucleus is closely related to chromatin activity. The mechanism of chromatin organization and remodeling attract much attention. Phase separation describes the biomolecular condensation which is the basis for membraneless compartments in cells. Recent research shows that phase separation is a key aspect to drive high-order chromatin structure and remodeling. In addition, chromatin functional compartmentalization in the nucleus which is formed by phase separation also plays an important role in overall chromatin structure. In this review, we summarized the latest work about the role of phase separation in spatial chromatin organization, focusing on direct and indirect effects of phase separation on 3D chromatin organization and its impact on transcription regulation.
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Affiliation(s)
- Xiaoli Li
- Division of Cell, Developmental and Integrative Biology, School of Medicine, South China University of Technology, Guangzhou 510006, China
- Department of Cell Biology and Genetics, Core Facility of Developmental Biology, Chongqing Medical University, Chongqing 400016, China
| | - Ziyang An
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-Sen University, Guangzhou 510275, China
| | - Wenqing Zhang
- Division of Cell, Developmental and Integrative Biology, School of Medicine, South China University of Technology, Guangzhou 510006, China
| | - Feifei Li
- Division of Cell, Developmental and Integrative Biology, School of Medicine, South China University of Technology, Guangzhou 510006, China
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5
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Ilık İA, Aktaş T. Nuclear speckles: dynamic hubs of gene expression regulation. FEBS J 2022; 289:7234-7245. [PMID: 34245118 DOI: 10.1111/febs.16117] [Citation(s) in RCA: 37] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Revised: 06/13/2021] [Accepted: 07/08/2021] [Indexed: 01/13/2023]
Abstract
Complex, multistep biochemical reactions that routinely take place in our cells require high concentrations of enzymes, substrates, and other structural components to proceed efficiently and typically require chemical environments that can inhibit other reactions in their immediate vicinity. Eukaryotic cells solve these problems by restricting such reactions into diffusion-restricted compartments within the cell called organelles that can be separated from their environment by a lipid membrane, or into membrane-less compartments that form through liquid-liquid phase separation (LLPS). One of the most easily noticeable and the earliest discovered organelle is the nucleus, which harbors the genetic material in cells where transcription by RNA polymerases produces most of the messenger RNAs and a plethora of noncoding RNAs, which in turn are required for translation of mRNAs in the cytoplasm. The interior of the nucleus is not a uniform soup of biomolecules and rather consists of a variety of membrane-less bodies, such as the nucleolus, nuclear speckles (NS), paraspeckles, Cajal bodies, histone locus bodies, and more. In this review, we will focus on NS with an emphasis on recent developments including our own findings about the formation of NS by two large IDR-rich proteins SON and SRRM2.
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Affiliation(s)
| | - Tuğçe Aktaş
- Max Planck Institute for Molecular Genetics, Berlin, Germany
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6
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Zhang YW, Chen L, Li SC. Detecting TAD-like domains from RNA-associated interactions. Nucleic Acids Res 2022; 50:e88. [PMID: 35639502 PMCID: PMC9410901 DOI: 10.1093/nar/gkac422] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Revised: 05/02/2022] [Accepted: 05/09/2022] [Indexed: 12/25/2022] Open
Abstract
Topologically associated domains (TADs) are crucial chromatin structural units. Evidence has illustrated that RNA-chromatin and RNA-RNA spatial interactions, so-called RNA-associated interactions (RAIs), may be associated with TAD-like domains (TLDs). To decode hierarchical TLDs from RAIs, we proposed SuperTLD, a domain detection algorithm incorporating imputation. We applied SuperTLD on four RAI data sets and compared TLDs with the TADs identified from the corresponding Hi-C datasets. The TLDs and TADs share a moderate similarity of hierarchies ≥ 0.5312 and the finest structures ≥ 0.8295. Comparison between boundaries and domains further demonstrated the novelty of TLDs. Enrichment analysis of epigenetic characteristics illustrated that the novel TLDs exhibit an enriched CTCF by 0.6245 fold change and H3 histone marks enriched within domains. GO analysis on the TLD novel boundaries exhibited enriched diverse terms, revealing TLDs' formation mechanism related closely to gene regulation.
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Affiliation(s)
- Yu Wei Zhang
- Department of Computer Science, City University of Hong Kong, Hong Kong
| | - Lingxi Chen
- Department of Computer Science, City University of Hong Kong, Hong Kong
| | - Shuai Cheng Li
- Department of Computer Science, City University of Hong Kong, Hong Kong
- Department of Biomedical Engineering, City University of Hong Kong, Hong Kong
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7
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Localization and functions of native and eGFP-tagged capsid proteins in HIV-1 particles. PLoS Pathog 2022; 18:e1010754. [PMID: 35951676 PMCID: PMC9426931 DOI: 10.1371/journal.ppat.1010754] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Revised: 08/30/2022] [Accepted: 07/21/2022] [Indexed: 12/24/2022] Open
Abstract
In infectious HIV-1 particles, the capsid protein (CA) forms a cone-shaped shell called the capsid, which encases the viral ribonucleoprotein complex (vRNP). Following cellular entry, the capsid is disassembled through a poorly understood process referred to as uncoating, which is required to release the reverse transcribed HIV-1 genome for integration into host chromatin. Whereas single virus imaging using indirect CA labeling techniques suggested uncoating to occur in the cytoplasm or at the nuclear pore, a recent study using eGFP-tagged CA reported uncoating in the nucleus. To delineate the HIV-1 uncoating site, we investigated the mechanism of eGFP-tagged CA incorporation into capsids and the utility of this fluorescent marker for visualizing HIV-1 uncoating. We find that virion incorporated eGFP-tagged CA is effectively excluded from the capsid shell, and that a subset of the tagged CA is vRNP associated. These results thus imply that eGFP-tagged CA is not a direct marker for capsid uncoating. We further show that native CA co-immunoprecipitates with vRNP components, providing a basis for retention of eGFP-tagged and untagged CA by sub-viral complexes in the nucleus. Moreover, we find that functional viral replication complexes become accessible to integrase-interacting host factors at the nuclear pore, leading to inhibition of infection and demonstrating capsid permeabilization prior to nuclear import. Finally, we find that HIV-1 cores containing a mixture of wild-type and mutant CA interact differently with cytoplasmic versus nuclear pools of the CA-binding host cofactor CPSF6. Our results suggest that capsid remodeling (including a loss of capsid integrity) is the predominant pathway for HIV-1 nuclear entry and provide new insights into the mechanism of CA retention in the nucleus via interaction with vRNP components. The timing, location and mechanisms of HIV-1 capsid disassembly which is referred to as uncoating remains unclear. Direct labeling of HIV-1 capsids, by incorporating a few green fluorescent proteins (GFP) tagged capsid protein (CA) into virions allows to image the spatio-temporal loss of HIV-1 CA during virus infection. However, the localization and functions of a few virion incorporated eGFP-tagged CA proteins remain unclear, since <50% of virus packaged CA proteins participate to form the conical capsid shell that protects the HIV-1 genome. Here we developed several approaches to test the localization and function of eGFP-tagged CA proteins in virions. We found that eGFP-tagged CA proteins are excluded from the conical capsid shell and that a subset of these proteins is associated with the viral ribonucleoprotein complex (vRNPs), through direct interactions between CA and vRNP components. eGFP-tagged CA is retained in the nucleus by virtue of vRNP association and is unlikely to report on HIV-1 capsid disassembly. We also found that HIV-1 capsids become permeabilized and are remodeled during their transport into the nucleus. Our study provides new insights into the ability of CA to interact with vRNPs for its retention in the nucleus and highlights capsid remodeling as a preferred pathway for HIV-1 entry into the nucleus.
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8
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Faber GP, Nadav-Eliyahu S, Shav-Tal Y. Nuclear speckles - a driving force in gene expression. J Cell Sci 2022; 135:275909. [PMID: 35788677 DOI: 10.1242/jcs.259594] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Nuclear speckles are dynamic membraneless bodies located in the cell nucleus. They harbor RNAs and proteins, many of which are splicing factors, that together display complex biophysical properties dictating nuclear speckle formation and maintenance. Although these nuclear bodies were discovered decades ago, only recently has in-depth genomic analysis begun to unravel their essential functions in modulation of gene activity. Major advancements in genomic mapping techniques combined with microscopy approaches have enabled insights into the roles nuclear speckles may play in enhancing gene expression, and how gene positioning to specific nuclear landmarks can regulate gene expression and RNA processing. Some studies have drawn a link between nuclear speckles and disease. Certain maladies either involve nuclear speckles directly or dictate the localization and reorganization of many nuclear speckle factors. This is most striking during viral infection, as viruses alter the entire nuclear architecture and highjack host machinery. As discussed in this Review, nuclear speckles represent a fascinating target of study not only to reveal the links between gene positioning, genome subcompartments and gene activity, but also as a potential target for therapeutics.
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Affiliation(s)
- Gabriel P Faber
- The Mina and Everard Goodman Faculty of Life Sciences , Bar-Ilan University, Ramat Gan 5290002, Israel.,Institute of Nanotechnology , Bar-Ilan University, Ramat Gan 5290002, Israel
| | - Shani Nadav-Eliyahu
- The Mina and Everard Goodman Faculty of Life Sciences , Bar-Ilan University, Ramat Gan 5290002, Israel.,Institute of Nanotechnology , Bar-Ilan University, Ramat Gan 5290002, Israel
| | - Yaron Shav-Tal
- The Mina and Everard Goodman Faculty of Life Sciences , Bar-Ilan University, Ramat Gan 5290002, Israel.,Institute of Nanotechnology , Bar-Ilan University, Ramat Gan 5290002, Israel
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9
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Belmont AS. Nuclear Compartments: An Incomplete Primer to Nuclear Compartments, Bodies, and Genome Organization Relative to Nuclear Architecture. Cold Spring Harb Perspect Biol 2022; 14:a041268. [PMID: 34400557 PMCID: PMC9248822 DOI: 10.1101/cshperspect.a041268] [Citation(s) in RCA: 39] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
This work reviews nuclear compartments, defined broadly to include distinct nuclear structures, bodies, and chromosome domains. It first summarizes original cytological observations before comparing concepts of nuclear compartments emerging from microscopy versus genomic approaches and then introducing new multiplexed imaging approaches that promise in the future to meld both approaches. I discuss how previous models of radial distribution of chromosomes or the binary division of the genome into A and B compartments are now being refined by the recognition of more complex nuclear compartmentalization. The poorly understood question of how these nuclear compartments are established and maintained is then discussed, including through the modern perspective of phase separation, before moving on to address possible functions of nuclear compartments, using the possible role of nuclear speckles in modulating gene expression as an example. Finally, the review concludes with a discussion of future questions for this field.
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Affiliation(s)
- Andrew S Belmont
- Department of Cell and Developmental Biology, University of Illinois, Urbana-Champaign, Urbana, Illinois 61801, USA
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10
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The era of 3D and spatial genomics. Trends Genet 2022; 38:1062-1075. [PMID: 35680466 DOI: 10.1016/j.tig.2022.05.010] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Revised: 05/10/2022] [Accepted: 05/11/2022] [Indexed: 12/28/2022]
Abstract
Over a decade ago the advent of high-throughput chromosome conformation capture (Hi-C) sparked a new era of 3D genomics. Since then the number of methods for mapping the 3D genome has flourished, enabling an ever-increasing understanding of how DNA is packaged in the nucleus and how the spatiotemporal organization of the genome orchestrates its vital functions. More recently, the next generation of spatial genomics technologies has begun to reveal how genome sequence and 3D genome organization vary between cells in their tissue context. We summarize how the toolkit for charting genome topology has evolved over the past decade and discuss how new technological developments are advancing the field of 3D and spatial genomics.
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11
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Raina K, Rao BJ. Mammalian nuclear speckles exhibit stable association with chromatin: a biochemical study. Nucleus 2022; 13:58-73. [PMID: 35220893 PMCID: PMC8890396 DOI: 10.1080/19491034.2021.2024948] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
Nuclear Speckles (NS) are phase-separated condensates of protein and RNA whose components dynamically coordinate RNA transcription, splicing, transport and DNA repair. NS, probed largely by imaging studies, remained historically well known as Interchromatin Granule Clusters, and biochemical properties, especially their association with Chromatin have been largely unexplored. In this study, we tested whether NS exhibit any stable association with chromatin and show that limited DNAse-1 nicking of chromatin leads to the collapse of NS into isotropic distribution or aggregates of constituent proteins without affecting other nuclear structures. Further biochemical probing revealed that NS proteins were tightly associated with chromatin, extractable only by high-salt treatment just like histone proteins. NS were also co-released with solubilised mono-dinucleosomal chromatin fraction following the MNase digestion of chromatin. We propose a model that NS-chromatin constitutes a “putative stable association” whose coupling might be subject to the combined regulation from both chromatin and NS changes. Abbreviations: NS: Nuclear speckles; DSB: double strand breaks; PTM: posttranslational modifications; DDR: DNA damage repair; RBP-RNA binding proteins; TAD: topologically associated domains; LCR: low complexity regions; IDR: intrinsically disordered regions.
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Affiliation(s)
- Komal Raina
- Department of Biological Sciences, Tata Institute of Fundamental Research, Mumbai, India
- Department of Biology, Indian Institute of Science Education and Research (Iiser) Tirupati, Transit Campus: Sree Rama Engineering College, Tirupati, India
| | - Basuthkar J Rao
- Department of Biological Sciences, Tata Institute of Fundamental Research, Mumbai, India
- Department of Biology, Indian Institute of Science Education and Research (Iiser) Tirupati, Transit Campus: Sree Rama Engineering College, Tirupati, India
- Department of Animal Biology, University of Hyderabad, Hyderabad, India
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12
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Measuring Cytological Proximity of Chromosomal Loci to Defined Nuclear Compartments with TSA-seq. Methods Mol Biol 2022; 2532:145-186. [PMID: 35867249 DOI: 10.1007/978-1-0716-2497-5_8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Distinct nuclear structures and bodies are involved in genome intranuclear positioning. Measuring proximity and relative distances of genomic loci to these nuclear compartments, and correlating this chromosome intranuclear positioning with epigenetic marks and functional readouts genome-wide, will be required to appreciate the true extent to which this nuclear compartmentalization contributes to regulation of genome functions. Here we present detailed protocols for TSA-seq, the first sequencing-based method for estimation of cytological proximity of chromosomal loci to spatially discrete nuclear structures, such as nuclear bodies or the nuclear lamina. TSA-seq uses Tyramide Signal Amplification (TSA) of immunostained cells to create a concentration gradient of tyramide-biotin free radicals which decays exponentially as a function of distance from a point-source target. Reaction of these free radicals with DNA deposits tyramide-biotin onto DNA as a function of distance from the point source. The relative enrichment of this tyramide-labeled DNA versus input DNA, revealed by DNA sequencing, can then be used as a "cytological ruler" to infer relative, or even absolute, mean chromosomal distances from immunostained nuclear compartments. TSA-seq mapping is highly reproducible and largely independent of the target protein or antibody choice for labeling a particular nuclear compartment. Our protocols include variations in TSA labeling conditions to provide varying spatial resolution as well as enhanced sensitivity. Our most streamlined protocol produces TSA-seq spatial mapping over a distance range of ~1 micron from major nuclear compartments using ~10-20 million cells.
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13
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Coordination of transcription, processing, and export of highly expressed RNAs by distinct biomolecular condensates. Emerg Top Life Sci 2021; 4:281-291. [PMID: 32338276 PMCID: PMC7733674 DOI: 10.1042/etls20190160] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2020] [Revised: 04/01/2020] [Accepted: 04/06/2020] [Indexed: 12/30/2022]
Abstract
Genes under control of super-enhancers are expressed at extremely high levels and are frequently associated with nuclear speckles. Recent data suggest that the high concentration of unphosphorylated RNA polymerase II (Pol II) and Mediator recruited to super-enhancers create phase-separated condensates. Transcription initiates within or at the surface of these phase-separated droplets and the phosphorylation of Pol II, associated with transcription initiation and elongation, dissociates Pol II from these domains leading to engagement with nuclear speckles, which are enriched with RNA processing factors. The transitioning of Pol II from transcription initiation domains to RNA processing domains effectively co-ordinates transcription and processing of highly expressed RNAs which are then rapidly exported into the cytoplasm.
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14
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Orti F, Navarro AM, Rabinovich A, Wodak SJ, Marino-Buslje C. Insight into membraneless organelles and their associated proteins: Drivers, Clients and Regulators. Comput Struct Biotechnol J 2021; 19:3964-3977. [PMID: 34377363 PMCID: PMC8318826 DOI: 10.1016/j.csbj.2021.06.042] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2021] [Revised: 06/26/2021] [Accepted: 06/27/2021] [Indexed: 02/06/2023] Open
Abstract
In recent years, attention has been devoted to proteins forming immiscible liquid phases within the liquid intracellular medium, commonly referred to as membraneless organelles (MLO). These organelles enable the spatiotemporal associations of cellular components that exchange dynamically with the cellular milieu. The dysregulation of these liquid-liquid phase separation processes (LLPS) may cause various diseases including neurodegenerative pathologies and cancer, among others. Until very recently, databases containing information on proteins forming MLOs, as well as tools and resources facilitating their analysis, were missing. This has recently changed with the publication of 4 databases that focus on different types of experiments, sets of proteins, inclusion criteria, and levels of annotation or curation. In this study we integrate and analyze the information across these databases, complement their records, and produce a consolidated set of proteins that enables the investigation of the LLPS phenomenon. To gain insight into the features that characterize different types of MLOs and the roles of their associated proteins, they were grouped into categories: High Confidence MLO associated (including Drivers and reviewed proteins), Potential Clients and Regulators, according to their annotated functions. We show that none of the databases taken alone covers the data sufficiently to enable meaningful analysis, validating our integration effort as essential for gaining better understanding of phase separation and laying the foundations for the discovery of new proteins potentially involved in this important cellular process. Lastly, we developed a server, enabling customized selections of different sets of proteins based on MLO location, database, disorder content, among other attributes (https://forti.shinyapps.io/mlos/).
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Affiliation(s)
- Fernando Orti
- Bioinformatics Unit, Fundación Instituto Leloir. Avda. Patricias Argentinas 435, Buenos Aires B1405WE, Argentina
| | - Alvaro M. Navarro
- Bioinformatics Unit, Fundación Instituto Leloir. Avda. Patricias Argentinas 435, Buenos Aires B1405WE, Argentina
| | - Andres Rabinovich
- Bioinformatics Unit, Fundación Instituto Leloir. Avda. Patricias Argentinas 435, Buenos Aires B1405WE, Argentina
| | - Shoshana J. Wodak
- VIB-VUB Center for Structural Biology, Flemish Institute for Biotechnology, Brussels, Belgium
- Structural Biology Brussels, Vrije Universiteit Brussel, Brussels, Belgium
| | - Cristina Marino-Buslje
- Bioinformatics Unit, Fundación Instituto Leloir. Avda. Patricias Argentinas 435, Buenos Aires B1405WE, Argentina
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15
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Gordon JM, Phizicky DV, Neugebauer KM. Nuclear mechanisms of gene expression control: pre-mRNA splicing as a life or death decision. Curr Opin Genet Dev 2021; 67:67-76. [PMID: 33291060 PMCID: PMC8084925 DOI: 10.1016/j.gde.2020.11.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Revised: 10/26/2020] [Accepted: 11/03/2020] [Indexed: 02/06/2023]
Abstract
Thousands of genes produce polyadenylated mRNAs that still contain one or more introns. These transcripts are known as retained intron RNAs (RI-RNAs). In the past 10 years, RI-RNAs have been linked to post-transcriptional alternative splicing in a variety of developmental contexts, but they can also be dead-end products fated for RNA decay. Here we discuss the role of intron retention in shaping gene expression programs, as well as recent evidence suggesting that the biogenesis and fate of RI-RNAs is regulated by nuclear organization. We discuss the possibility that proximity of RNA to nuclear speckles - biomolecular condensates that are highly enriched in splicing factors and other RNA binding proteins - is associated with choices ranging from efficient co-transcriptional splicing, export and stability to regulated post-transcriptional splicing and possible vulnerability to decay.
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Affiliation(s)
- Jackson M Gordon
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, 06520, USA
| | - David V Phizicky
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, 06520, USA
| | - Karla M Neugebauer
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, 06520, USA.
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16
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Stress-induced RNA-chromatin interactions promote endothelial dysfunction. Nat Commun 2020; 11:5211. [PMID: 33060583 PMCID: PMC7566596 DOI: 10.1038/s41467-020-18957-w] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Accepted: 09/11/2020] [Indexed: 01/06/2023] Open
Abstract
Chromatin-associated RNA (caRNA) has been proposed as a type of epigenomic modifier. Here, we test whether environmental stress can induce cellular dysfunction through modulating RNA-chromatin interactions. We induce endothelial cell (EC) dysfunction with high glucose and TNFα (H + T), that mimic the common stress in diabetes mellitus. We characterize the H + T-induced changes in gene expression by single cell (sc)RNA-seq, DNA interactions by Hi-C, and RNA-chromatin interactions by iMARGI. H + T induce inter-chromosomal RNA-chromatin interactions, particularly among the super enhancers. To test the causal relationship between H + T-induced RNA-chromatin interactions and the expression of EC dysfunction-related genes, we suppress the LINC00607 RNA. This suppression attenuates the expression of SERPINE1, a critical pro-inflammatory and pro-fibrotic gene. Furthermore, the changes of the co-expression gene network between diabetic and healthy donor-derived ECs corroborate the H + T-induced RNA-chromatin interactions. Taken together, caRNA-mediated dysregulation of gene expression modulates EC dysfunction, a crucial mechanism underlying numerous diseases. Global interaction of chromatin-associated RNAs and DNA can be identified in situ. Here the authors report the genome-wide increase of interchromosomal RNA-DNA interactions and demonstrate the importance of such RNA-DNA contacts exemplified by LINC00607 RNA and SERPINE1 gene’s super enhancer in dysfunctional endothelial cell models.
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17
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Li W, Singh PK, Sowd GA, Bedwell GJ, Jang S, Achuthan V, Oleru AV, Wong D, Fadel HJ, Lee K, KewalRamani VN, Poeschla EM, Herschhorn A, Engelman AN. CPSF6-Dependent Targeting of Speckle-Associated Domains Distinguishes Primate from Nonprimate Lentiviral Integration. mBio 2020; 11:e02254-20. [PMID: 32994325 PMCID: PMC7527728 DOI: 10.1128/mbio.02254-20] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Accepted: 08/28/2020] [Indexed: 12/19/2022] Open
Abstract
Lentiviral DNA integration favors transcriptionally active chromatin. We previously showed that the interaction of human immunodeficiency virus type 1 (HIV-1) capsid with cleavage and polyadenylation specificity factor 6 (CPSF6) localizes viral preintegration complexes (PICs) to nuclear speckles for integration into transcriptionally active speckle-associated domains (SPADs). In the absence of the capsid-CPSF6 interaction, PICs uncharacteristically accumulate at the nuclear periphery and target heterochromatic lamina-associated domains (LADs) for integration. The integrase-binding protein lens epithelium-derived growth factor (LEDGF)/p75 in contrast to CPSF6 predominantly functions to direct HIV-1 integration to interior regions of transcription units. Though CPSF6 and LEDGF/p75 can reportedly interact with the capsid and integrase proteins of both primate and nonprimate lentiviruses, the extents to which these different viruses target SPADs versus LADs, as well as their dependencies on CPSF6 and LEDGF/p75 for integration targeting, are largely unknown. Here, we mapped 5,489,157 primate and nonprimate lentiviral integration sites in HEK293T and Jurkat T cells as well as derivative cells that were knocked out or knocked down for host factor expression. Despite marked preferences of all lentiviruses to target genes for integration, nonprimate lentiviruses only marginally favored SPADs, with corresponding upticks in LAD-proximal integration. While LEDGF/p75 knockout disrupted the intragenic integration profiles of all lentiviruses similarly, CPSF6 depletion specifically counteracted SPAD integration targeting by primate lentiviruses. CPSF6 correspondingly failed to appreciably interact with nonprimate lentiviral capsids. We conclude that primate lentiviral capsid proteins evolved to interact with CPSF6 to optimize PIC localization for integration into transcriptionally active SPADs.IMPORTANCE Integration is the defining step of the retroviral life cycle and underlies the inability to cure HIV/AIDS through the use of intensified antiviral therapy. The reservoir of latent, replication-competent proviruses that forms early during HIV infection reseeds viremia when patients discontinue medication. HIV cure research is accordingly focused on the factors that guide provirus formation and associated chromatin environments that regulate transcriptional reactivation, and studies of orthologous infectious agents such as nonprimate lentiviruses can inform basic principles of HIV biology. HIV-1 utilizes the integrase-binding protein LEDGF/p75 and the capsid interactor CPSF6 to target speckle-associated domains (SPADs) for integration. However, the extent to which these two host proteins regulate integration of other lentiviruses is largely unknown. Here, we mapped millions of retroviral integration sites in cell lines that were depleted for LEDGF/p75 and/or CPSF6. Our results reveal that primate lentiviruses uniquely target SPADs for integration in a CPSF6-dependent manner.
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Affiliation(s)
- Wen Li
- Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Boston, Massachusetts, USA
- Department of Medicine, Harvard Medical School, Boston, Massachusetts, USA
| | - Parmit K Singh
- Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Boston, Massachusetts, USA
- Department of Medicine, Harvard Medical School, Boston, Massachusetts, USA
| | - Gregory A Sowd
- Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Boston, Massachusetts, USA
- Department of Medicine, Harvard Medical School, Boston, Massachusetts, USA
| | - Gregory J Bedwell
- Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Boston, Massachusetts, USA
- Department of Medicine, Harvard Medical School, Boston, Massachusetts, USA
| | - Sooin Jang
- Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Boston, Massachusetts, USA
- Department of Medicine, Harvard Medical School, Boston, Massachusetts, USA
| | - Vasudevan Achuthan
- Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Boston, Massachusetts, USA
- Department of Medicine, Harvard Medical School, Boston, Massachusetts, USA
| | - Amarachi V Oleru
- Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Boston, Massachusetts, USA
| | - Doris Wong
- Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Boston, Massachusetts, USA
| | - Hind J Fadel
- Department of Internal Medicine, Mayo Clinic, Rochester, Minnesota, USA
| | - KyeongEun Lee
- Basic Research Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, Maryland, USA
| | - Vineet N KewalRamani
- Basic Research Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, Maryland, USA
| | - Eric M Poeschla
- Division of Infectious Diseases, University of Colorado Denver School of Medicine, Aurora, Colorado, USA
| | - Alon Herschhorn
- Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Boston, Massachusetts, USA
- Department of Medicine, Harvard Medical School, Boston, Massachusetts, USA
| | - Alan N Engelman
- Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Boston, Massachusetts, USA
- Department of Medicine, Harvard Medical School, Boston, Massachusetts, USA
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18
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Hasenson SE, Shav‐Tal Y. Speculating on the Roles of Nuclear Speckles: How RNA‐Protein Nuclear Assemblies Affect Gene Expression. Bioessays 2020; 42:e2000104. [DOI: 10.1002/bies.202000104] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Revised: 06/17/2020] [Indexed: 02/06/2023]
Affiliation(s)
- Sarah E. Hasenson
- The Mina & Everard Goodman Faculty of Life Sciences and the Institute of Nanotechnology and Advanced Materials Bar‐Ilan University Ramat Gan 4481400 Israel
| | - Yaron Shav‐Tal
- The Mina & Everard Goodman Faculty of Life Sciences and the Institute of Nanotechnology and Advanced Materials Bar‐Ilan University Ramat Gan 4481400 Israel
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19
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Francis AC, Marin M, Singh PK, Achuthan V, Prellberg MJ, Palermino-Rowland K, Lan S, Tedbury PR, Sarafianos SG, Engelman AN, Melikyan GB. HIV-1 replication complexes accumulate in nuclear speckles and integrate into speckle-associated genomic domains. Nat Commun 2020; 11:3505. [PMID: 32665593 PMCID: PMC7360574 DOI: 10.1038/s41467-020-17256-8] [Citation(s) in RCA: 74] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Accepted: 06/19/2020] [Indexed: 12/12/2022] Open
Abstract
The early steps of HIV-1 infection, such as uncoating, reverse transcription, nuclear import, and transport to integration sites are incompletely understood. Here, we imaged nuclear entry and transport of HIV-1 replication complexes in cell lines, primary monocyte-derived macrophages (MDMs) and CD4+ T cells. We show that viral replication complexes traffic to and accumulate within nuclear speckles and that these steps precede the completion of viral DNA synthesis. HIV-1 transport to nuclear speckles is dependent on the interaction of the capsid proteins with host cleavage and polyadenylation specificity factor 6 (CPSF6), which is also required to stabilize the association of the viral replication complexes with nuclear speckles. Importantly, integration site analyses reveal a strong preference for HIV-1 to integrate into speckle-associated genomic domains. Collectively, our results demonstrate that nuclear speckles provide an architectural basis for nuclear homing of HIV-1 replication complexes and subsequent integration into associated genomic loci. Early steps of HIV infection of primary human cells remain poorly understood. Here, Francis et al. show that early viral replication complexes accumulate within nuclear speckles, in reliance on viral capsid/host CPSF6 interactions, and preferentially integrate in speckle-associated genomic domains.
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Affiliation(s)
- Ashwanth C Francis
- Division of Infectious Diseases, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA, 30322, USA.
| | - Mariana Marin
- Division of Infectious Diseases, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA, 30322, USA
| | - Parmit K Singh
- Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Boston, MA, 02115, USA.,Department of Medicine, Harvard Medical School, Boston, MA, 02115, USA
| | - Vasudevan Achuthan
- Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Boston, MA, 02115, USA.,Department of Medicine, Harvard Medical School, Boston, MA, 02115, USA
| | - Mathew J Prellberg
- Division of Infectious Diseases, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA, 30322, USA
| | - Kristina Palermino-Rowland
- Division of Infectious Diseases, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA, 30322, USA
| | - Shuiyun Lan
- Laboratory of Biochemical Pharmacology, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA, 30322, USA
| | - Philip R Tedbury
- Laboratory of Biochemical Pharmacology, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA, 30322, USA
| | - Stefan G Sarafianos
- Laboratory of Biochemical Pharmacology, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA, 30322, USA
| | - Alan N Engelman
- Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Boston, MA, 02115, USA.,Department of Medicine, Harvard Medical School, Boston, MA, 02115, USA
| | - Gregory B Melikyan
- Division of Infectious Diseases, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA, 30322, USA. .,Children's Healthcare of Atlanta, Atlanta, GA, 30322, USA.
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20
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Kato M, Carninci P. Genome-Wide Technologies to Study RNA-Chromatin Interactions. Noncoding RNA 2020; 6:ncrna6020020. [PMID: 32471183 PMCID: PMC7345514 DOI: 10.3390/ncrna6020020] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2020] [Revised: 05/23/2020] [Accepted: 05/25/2020] [Indexed: 12/21/2022] Open
Abstract
An increasing number of studies have revealed that long non-coding RNAs (lncRNAs) play important roles in gene regulation and nuclear organization. Although the mechanisms are still largely unknown, many lncRNAs have been shown to interact with chromatin. Thus, one approach to understanding the function of these lncRNAs is to identify their sites of genomic interaction. Hybridization capture methods using oligonucleotide probes have been used for years to study chromatin-associated RNA. Recently, several groups have developed novel methods based on proximity ligation to investigate RNA–chromatin interactions at a genome-wide scale. This review discusses these technologies and highlights their advantages and disadvantages for the consideration of potential users.
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Affiliation(s)
- Masaki Kato
- Correspondence: (M.K.); (P.C.); Tel.: +81-045-503-9111 (M.K.)
| | - Piero Carninci
- Correspondence: (M.K.); (P.C.); Tel.: +81-045-503-9111 (M.K.)
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21
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Smith KP, Hall LL, Lawrence JB. Nuclear hubs built on RNAs and clustered organization of the genome. Curr Opin Cell Biol 2020; 64:67-76. [PMID: 32259767 DOI: 10.1016/j.ceb.2020.02.015] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Revised: 02/13/2020] [Accepted: 02/22/2020] [Indexed: 12/18/2022]
Abstract
RNAs play diverse roles in formation and function of subnuclear compartments, most of which are associated with active genes. NEAT1 and NEAT2/MALAT1 exemplify long non-coding RNAs (lncRNAs) known to function in nuclear bodies; however, we suggest that RNA biogenesis itself may underpin much nuclear compartmentalization. Recent studies show that active genes cluster with nuclear speckles on a genome-wide scale, significantly advancing earlier cytological evidence that speckles (aka SC-35 domains) are hubs of concentrated pre-mRNA metabolism. We propose the 'karyotype to hub' hypothesis to explain this organization: clustering of genes in the human karyotype may have evolved to facilitate the formation of efficient nuclear hubs, driven in part by the propensity of ribonucleoproteins (RNPs) to form large-scale condensates. The special capacity of highly repetitive RNAs to impact architecture is highlighted by recent findings that human satellite II RNA sequesters factors into abnormal nuclear bodies in disease, potentially co-opting a normal developmental mechanism.
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Affiliation(s)
- Kelly P Smith
- Department of Neurology, University of Massachusetts Medical School, 55 Lake Ave. North, Worcester, MA, 01655, USA
| | - Lisa L Hall
- Department of Neurology, University of Massachusetts Medical School, 55 Lake Ave. North, Worcester, MA, 01655, USA
| | - Jeanne B Lawrence
- Department of Neurology, University of Massachusetts Medical School, 55 Lake Ave. North, Worcester, MA, 01655, USA.
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22
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Krasikova A, Kulikova T. Identification of Genomic Loci Responsible for the Formation of Nuclear Domains Using Lampbrush Chromosomes. Noncoding RNA 2019; 6:ncrna6010001. [PMID: 31881720 PMCID: PMC7151628 DOI: 10.3390/ncrna6010001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Revised: 12/19/2019] [Accepted: 12/22/2019] [Indexed: 12/12/2022] Open
Abstract
In the cell nuclei, various types of nuclear domains assemble as a result of transcriptional activity at specific chromosomal loci. Giant transcriptionally active lampbrush chromosomes, which form in oocyte nuclei of amphibians and birds enable the mapping of genomic sequences with high resolution and the visualization of individual transcription units. This makes avian and amphibian oocyte nuclei an advantageous model for studying locus-specific nuclear domains. We developed two strategies for identification and comprehensive analysis of the genomic loci involved in nuclear domain formation on lampbrush chromosomes. The first approach was based on the sequential FISH-mapping of BAC clones containing genomic DNA fragments with a known chromosomal position close to the locus of a nuclear domain. The second approach involved mechanical microdissection of the chromosomal region adjacent to the nuclear domain followed by the generation of FISH-probes and DNA sequencing. Furthermore, deciphering the DNA sequences from the dissected material by high throughput sequencing technologies and their mapping to the reference genome helps to identify the genomic region responsible for the formation of the nuclear domain. For those nuclear domains structured by nascent transcripts, identification of genomic loci of their formation is a crucial step in the identification of scaffold RNAs.
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23
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Wu W, Yan Z, Nguyen TC, Bouman Chen Z, Chien S, Zhong S. Mapping RNA-chromatin interactions by sequencing with iMARGI. Nat Protoc 2019; 14:3243-3272. [PMID: 31619811 PMCID: PMC7314528 DOI: 10.1038/s41596-019-0229-4] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2018] [Accepted: 07/23/2019] [Indexed: 12/11/2022]
Abstract
RNA-chromatin interactions represent an important aspect of the transcriptional regulation of genes and transposable elements. However, analyses of chromatin-associated RNAs (caRNAs) are often limited to one caRNA at a time. Here, we describe the iMARGI (in situ mapping of RNA-genome interactome) technique, which is used to discover caRNAs and reveal their respective genomic interaction loci. iMARGI starts with in situ crosslinking and genome fragmentation, followed by converting each proximal RNA-DNA pair into an RNA-linker-DNA chimeric sequence. These chimeric sequences are subsequently converted into a sequencing library suitable for paired-end sequencing. A standardized bioinformatic software package, iMARGI-Docker, is provided to decode the paired-end sequencing data into caRNA-DNA interactions. Compared to its predecessor MARGI (mapping RNA-genome interactions), the number of input cells for iMARGI is 3-5 million (a 100-fold reduction), experimental time is reduced, and clear checkpoints have been established. It takes a few hours a day and a total of 8 d to complete the construction of an iMARGI sequencing library and 1 d to carry out data processing with iMARGI-Docker.
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Affiliation(s)
- Weixin Wu
- Department of Bioengineering, University of California, San Diego, La Jolla, CA, USA
| | - Zhangming Yan
- Department of Bioengineering, University of California, San Diego, La Jolla, CA, USA
- Institute of Engineering in Medicine, University of California, San Diego, La Jolla, CA, USA
| | - Tri C Nguyen
- Department of Bioengineering, University of California, San Diego, La Jolla, CA, USA
| | - Zhen Bouman Chen
- Department of Diabetes Complications and Metabolism, Beckman Research Institute, City of Hope, Duarte, CA, USA
| | - Shu Chien
- Department of Bioengineering, University of California, San Diego, La Jolla, CA, USA
- Institute of Engineering in Medicine, University of California, San Diego, La Jolla, CA, USA
| | - Sheng Zhong
- Department of Bioengineering, University of California, San Diego, La Jolla, CA, USA.
- Institute of Engineering in Medicine, University of California, San Diego, La Jolla, CA, USA.
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24
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Chen Y, Belmont AS. Genome organization around nuclear speckles. Curr Opin Genet Dev 2019; 55:91-99. [PMID: 31394307 DOI: 10.1016/j.gde.2019.06.008] [Citation(s) in RCA: 79] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2019] [Revised: 06/05/2019] [Accepted: 06/11/2019] [Indexed: 01/08/2023]
Abstract
Higher eukaryotic cell nuclei are highly compartmentalized into bodies and structural assemblies of specialized functions. Nuclear speckles/IGCs are one of the most prominent nuclear bodies, yet their functional significance remains largely unknown. Recent advances in sequence-based mapping of nuclear genome organization now provide genome-wide analysis of chromosome organization relative to nuclear speckles. Here we review older microscopy-based studies on a small number of genes with the new genomic mapping data suggesting a significant fraction of the genome is almost deterministically positioned near nuclear speckles. Both microscopy and genomic-based approaches support the concept of the nuclear speckle periphery as a major active chromosomal compartment which may play an important role in fine-tuning gene regulation.
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Affiliation(s)
- Yu Chen
- Department of Molecular and Cell Biology, Li Ka Shing Center for Biomedical and Health Sciences, CIRM Center of Excellence, University of California, Berkeley, CA 94720, USA; Howard Hughes Medical Institute, Berkeley, CA 94720, USA
| | - Andrew S Belmont
- Department of Cell and Developmental Biology, University of Illinois, Urbana-Champaign, B107 CLSL, 601 S. Goodwin Avenue, Urbana, IL 61801, USA.
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25
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Hu S, Lv P, Yan Z, Wen B. Disruption of nuclear speckles reduces chromatin interactions in active compartments. Epigenetics Chromatin 2019; 12:43. [PMID: 31315647 PMCID: PMC6636040 DOI: 10.1186/s13072-019-0289-2] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Accepted: 07/07/2019] [Indexed: 01/06/2023] Open
Abstract
BACKGROUND Nuclei of eukaryotes contain various higher-order chromatin architectures and nuclear bodies (NBs), which are critical for proper nuclear functions. Recent studies showed that active chromatin regions are associated with nuclear speckles (NSs), a type of NBs involved in RNA processing. However, the functional roles of NSs in 3D genome organization remain unclear. RESULTS Using mouse hepatocytes as the model, we knocked down SRRM2, a core protein component scaffolding NSs, and performed Hi-C experiments to examine genome-wide chromatin interactions. We found that Srrm2 depletion disrupted the NSs and changed the expression of 1282 genes. The intra-chromosomal interactions were decreased in type A (active) compartments and increased in type B (repressive) compartments. Furthermore, upon Srrm2 knockdown, the insulation of TADs was decreased specifically in active compartments, and the most significant reduction occurred in A1 sub-compartments. Interestingly, the change of intra-TAD chromatin interactions upon Srrm2 depletion was not associated with the alteration of gene expression. CONCLUSIONS We show that disruption of NSs by Srrm2 knockdown causes a global decrease in chromatin interactions in active compartments, indicating critical functions of NSs in the organization of the 3D genome.
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Affiliation(s)
- Shibin Hu
- MOE Key Laboratory of Metabolism and Molecular Medicine, School of Basic Medical Sciences, and Institutes of Biomedical Sciences, Fudan University, Shanghai, 200032, China
| | - Pin Lv
- MOE Key Laboratory of Metabolism and Molecular Medicine, School of Basic Medical Sciences, and Institutes of Biomedical Sciences, Fudan University, Shanghai, 200032, China
| | - Zixiang Yan
- MOE Key Laboratory of Metabolism and Molecular Medicine, School of Basic Medical Sciences, and Institutes of Biomedical Sciences, Fudan University, Shanghai, 200032, China
| | - Bo Wen
- The Fifth People's Hospital of Shanghai, and Institutes of Biomedical Sciences, Fudan University, Shanghai, 200032, China. .,MOE Key Laboratory of Metabolism and Molecular Medicine and Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Fudan University, Shanghai, 200032, China.
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26
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Parmar JJ, Woringer M, Zimmer C. How the Genome Folds: The Biophysics of Four-Dimensional Chromatin Organization. Annu Rev Biophys 2019; 48:231-253. [DOI: 10.1146/annurev-biophys-052118-115638] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The genetic information that instructs transcription and other cellular functions is carried by the chromosomes, polymers of DNA in complex with histones and other proteins. These polymers are folded inside nuclei five orders of magnitude smaller than their linear length, and many facets of this folding correlate with or are causally related to transcription and other cellular functions. Recent advances in sequencing and imaging-based techniques have enabled new views into several layers of chromatin organization. These experimental findings are accompanied by computational modeling efforts based on polymer physics that can provide mechanistic insights and quantitative predictions. Here, we review current knowledge of the main levels of chromatin organization, from the scale of nucleosomes to the entire nucleus, our current understanding of their underlying biophysical and molecular mechanisms, and some of their functional implications.
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Affiliation(s)
- Jyotsana J. Parmar
- Unité Imagerie et Modélisation, CNRS UMR 3691, and C3BI (Center of Bioinformatics, Biostatistics and Integrative Biology), CNRS USR 3756, Institut Pasteur, 75015 Paris, France;, ,
| | - Maxime Woringer
- Unité Imagerie et Modélisation, CNRS UMR 3691, and C3BI (Center of Bioinformatics, Biostatistics and Integrative Biology), CNRS USR 3756, Institut Pasteur, 75015 Paris, France;, ,
- Sorbonne Universités, CNRS, 75005 Paris, France
- Department of Molecular and Cell Biology, Li Ka Shing Center for Biomedical and Health Sciences, and CIRM Center of Excellence in Stem Cell Genomics, University of California, Berkeley, California 94720, USA
| | - Christophe Zimmer
- Unité Imagerie et Modélisation, CNRS UMR 3691, and C3BI (Center of Bioinformatics, Biostatistics and Integrative Biology), CNRS USR 3756, Institut Pasteur, 75015 Paris, France;, ,
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27
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Nguyen TC, Zaleta-Rivera K, Huang X, Dai X, Zhong S. RNA, Action through Interactions. Trends Genet 2018; 34:867-882. [PMID: 30177410 DOI: 10.1016/j.tig.2018.08.001] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Revised: 07/10/2018] [Accepted: 08/03/2018] [Indexed: 12/18/2022]
Abstract
As transcription of the human genome is quite pervasive, it is possible that many novel functions of the noncoding genome have yet to be identified. Often the noncoding genome's functions are carried out by their RNA transcripts, which may rely on their structures and/or extensive interactions with other molecules. Recent technology developments are transforming the fields of RNA biology from studying one RNA at a time to transcriptome-wide mapping of structures and interactions. Here, we highlight the recent advances in transcriptome-wide RNA interaction analysis. These technologies revealed surprising versatility of RNA to participate in diverse molecular systems. For example, tens of thousands of RNA-RNA interactions have been revealed in cultured cells as well as in mouse brain, including interactions between transposon-produced transcripts and mRNAs. In addition, most transcription start sites in the human genome are associated with noncoding RNA transcribed from other genomic loci. These recent discoveries expanded our understanding of RNAs' roles in chromatin organization, gene regulation, and intracellular signaling.
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Affiliation(s)
- Tri C Nguyen
- Department of Bioengineering, University of California, San Diego, La Jolla, CA, USA
| | - Kathia Zaleta-Rivera
- Department of Bioengineering, University of California, San Diego, La Jolla, CA, USA
| | - Xuerui Huang
- Department of Bioengineering, University of California, San Diego, La Jolla, CA, USA
| | - Xiaofeng Dai
- Wuxi School of Medicine, Jiangnan University, Wuxi Shi, Jiangsu Sheng, P.R. China.
| | - Sheng Zhong
- Department of Bioengineering, University of California, San Diego, La Jolla, CA, USA.
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