1
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Hsiao YT, Liao IH, Wu BK, Chu HPC, Hsieh CL. Probing chromatin condensation dynamics in live cells using interferometric scattering correlation spectroscopy. Commun Biol 2024; 7:763. [PMID: 38914653 PMCID: PMC11196589 DOI: 10.1038/s42003-024-06457-2] [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: 11/24/2023] [Accepted: 06/14/2024] [Indexed: 06/26/2024] Open
Abstract
Chromatin organization and dynamics play important roles in governing the regulation of nuclear processes of biological cells. However, due to the constant diffusive motion of chromatin, examining chromatin nanostructures in living cells has been challenging. In this study, we introduce interferometric scattering correlation spectroscopy (iSCORS) to spatially map nanoscopic chromatin configurations within unlabeled live cell nuclei. This label-free technique captures time-varying linear scattering signals generated by the motion of native chromatin on a millisecond timescale, allowing us to deduce chromatin condensation states. Using iSCORS imaging, we quantitatively examine chromatin dynamics over extended periods, revealing spontaneous fluctuations in chromatin condensation and heterogeneous compaction levels in interphase cells, independent of cell phases. Moreover, we observe changes in iSCORS signals of chromatin upon transcription inhibition, indicating that iSCORS can probe nanoscopic chromatin structures and dynamics associated with transcriptional activities. Our scattering-based optical microscopy, which does not require labeling, serves as a powerful tool for visualizing dynamic chromatin nano-arrangements in live cells. This advancement holds promise for studying chromatin remodeling in various crucial cellular processes, such as stem cell differentiation, mechanotransduction, and DNA repair.
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Affiliation(s)
- Yi-Teng Hsiao
- Institute of Atomic and Molecular Sciences (IAMS), Academia Sinica, Taipei, Taiwan
| | - I-Hsin Liao
- Institute of Atomic and Molecular Sciences (IAMS), Academia Sinica, Taipei, Taiwan
- Institute of Molecular and Cellular Biology, National Taiwan University, Taipei, Taiwan
| | - Bo-Kuan Wu
- Institute of Atomic and Molecular Sciences (IAMS), Academia Sinica, Taipei, Taiwan
| | | | - Chia-Lung Hsieh
- Institute of Atomic and Molecular Sciences (IAMS), Academia Sinica, Taipei, Taiwan.
- Department of Physics, National Taiwan University, Taipei, Taiwan.
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2
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Rojas P, Wang J, Guglielmi G, Sadurnì MM, Pavlou L, Leung GHD, Rajagopal V, Spill F, Saponaro M. Genome-wide identification of replication fork stalling/pausing sites and the interplay between RNA Pol II transcription and DNA replication progression. Genome Biol 2024; 25:126. [PMID: 38773641 PMCID: PMC11106976 DOI: 10.1186/s13059-024-03278-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2023] [Accepted: 05/14/2024] [Indexed: 05/24/2024] Open
Abstract
BACKGROUND DNA replication progression can be affected by the presence of physical barriers like the RNA polymerases, leading to replication stress and DNA damage. Nonetheless, we do not know how transcription influences overall DNA replication progression. RESULTS To characterize sites where DNA replication forks stall and pause, we establish a genome-wide approach to identify them. This approach uses multiple timepoints during S-phase to identify replication fork/stalling hotspots as replication progresses through the genome. These sites are typically associated with increased DNA damage, overlapped with fragile sites and with breakpoints of rearrangements identified in cancers but do not overlap with replication origins. Overlaying these sites with a genome-wide analysis of RNA polymerase II transcription, we find that replication fork stalling/pausing sites inside genes are directly related to transcription progression and activity. Indeed, we find that slowing down transcription elongation slows down directly replication progression through genes. This indicates that transcription and replication can coexist over the same regions. Importantly, rearrangements found in cancers overlapping transcription-replication collision sites are detected in non-transformed cells and increase following treatment with ATM and ATR inhibitors. At the same time, we find instances where transcription activity favors replication progression because it reduces histone density. CONCLUSIONS Altogether, our findings highlight how transcription and replication overlap during S-phase, with both positive and negative consequences for replication fork progression and genome stability by the coexistence of these two processes.
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Affiliation(s)
- Patricia Rojas
- Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham, B15 2TT, UK
| | - Jianming Wang
- Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham, B15 2TT, UK
| | - Giovanni Guglielmi
- School of Mathematics, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
- Department of Biomedical Engineering, University of Melbourne, Melbourne, VIC, 3010, Australia
| | - Martina Mustè Sadurnì
- Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham, B15 2TT, UK
| | - Lucas Pavlou
- Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham, B15 2TT, UK
| | - Geoffrey Ho Duen Leung
- Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham, B15 2TT, UK
| | - Vijay Rajagopal
- Department of Biomedical Engineering, University of Melbourne, Melbourne, VIC, 3010, Australia
| | - Fabian Spill
- School of Mathematics, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| | - Marco Saponaro
- Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham, B15 2TT, UK.
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3
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Willemin A, Szabó D, Pombo A. Epigenetic regulatory layers in the 3D nucleus. Mol Cell 2024; 84:415-428. [PMID: 38242127 PMCID: PMC10872226 DOI: 10.1016/j.molcel.2023.12.032] [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: 07/26/2023] [Revised: 11/21/2023] [Accepted: 12/15/2023] [Indexed: 01/21/2024]
Abstract
Nearly 7 decades have elapsed since Francis Crick introduced the central dogma of molecular biology, as part of his ideas on protein synthesis, setting the fundamental rules of sequence information transfer from DNA to RNAs and proteins. We have since learned that gene expression is finely tuned in time and space, due to the activities of RNAs and proteins on regulatory DNA elements, and through cell-type-specific three-dimensional conformations of the genome. Here, we review major advances in genome biology and discuss a set of ideas on gene regulation and highlight how various biomolecular assemblies lead to the formation of structural and regulatory features within the nucleus, with roles in transcriptional control. We conclude by suggesting further developments that will help capture the complex, dynamic, and often spatially restricted events that govern gene expression in mammalian cells.
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Affiliation(s)
- Andréa Willemin
- Max-Delbrück-Center for Molecular Medicine in the Helmholtz Association (MDC), Berlin Institute for Medical Systems Biology (BIMSB), Epigenetic Regulation and Chromatin Architecture Group, Berlin, Germany; Humboldt-Universität zu Berlin, Institute for Biology, Berlin, Germany.
| | - Dominik Szabó
- Max-Delbrück-Center for Molecular Medicine in the Helmholtz Association (MDC), Berlin Institute for Medical Systems Biology (BIMSB), Epigenetic Regulation and Chromatin Architecture Group, Berlin, Germany; Humboldt-Universität zu Berlin, Institute for Biology, Berlin, Germany
| | - Ana Pombo
- Max-Delbrück-Center for Molecular Medicine in the Helmholtz Association (MDC), Berlin Institute for Medical Systems Biology (BIMSB), Epigenetic Regulation and Chromatin Architecture Group, Berlin, Germany; Humboldt-Universität zu Berlin, Institute for Biology, Berlin, Germany.
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4
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Wang T, Shi S, Shi Y, Jiang P, Hu G, Ye Q, Shi Z, Yu K, Wang C, Fan G, Zhao S, Ma H, Chang ACY, Li Z, Bian Q, Lin CP. Chemical-induced phase transition and global conformational reorganization of chromatin. Nat Commun 2023; 14:5556. [PMID: 37689690 PMCID: PMC10492836 DOI: 10.1038/s41467-023-41340-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2023] [Accepted: 08/29/2023] [Indexed: 09/11/2023] Open
Abstract
Chemicals or drugs can accumulate within biomolecular condensates formed through phase separation in cells. Here, we use super-resolution imaging to search for chemicals that induce phase transition within chromatin at the microscale. This microscopic screening approach reveals that adriamycin (doxorubicin) - a widely used anticancer drug that is known to interact with chromatin - specifically induces visible local condensation and global conformational change of chromatin in cancer and primary cells. Hi-C and ATAC-seq experiments systematically and quantitatively demonstrate that adriamycin-induced chromatin condensation is accompanied by weakened chromatin interaction within topologically associated domains, compartment A/B switching, lower chromatin accessibility, and corresponding transcriptomic changes. Mechanistically, adriamycin complexes with histone H1 and induces phase transition of H1, forming fibrous aggregates in vitro. These results reveal a phase separation-driven mechanism for a chemotherapeutic drug.
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Affiliation(s)
- Tengfei Wang
- School of Life Science and Technology, ShanghaiTech University, 201210, Shanghai, China
| | - Shuxiang Shi
- School of Life Science and Technology, ShanghaiTech University, 201210, Shanghai, China
- Lingang Laboratory, 200031, Shanghai, China
| | - Yuanyuan Shi
- Shanghai Institute of Precision Medicine, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, 200125, Shanghai, China
- Shanghai Key Laboratory of Reproductive Medicine, Shanghai Jiao Tong University School of Medicine, 200025, Shanghai, China
| | - Peipei Jiang
- Shanghai Institute of Precision Medicine, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, 200125, Shanghai, China
- Shanghai Key Laboratory of Reproductive Medicine, Shanghai Jiao Tong University School of Medicine, 200025, Shanghai, China
| | - Ganlu Hu
- Shanghai Institute for Advanced Immunochemical Studies, ShanghaiTech University, 201210, Shanghai, China
| | - Qinying Ye
- School of Life Science and Technology, ShanghaiTech University, 201210, Shanghai, China
| | - Zhan Shi
- School of Physical Science and Technology, ShanghaiTech University, 201210, Shanghai, China
| | - Kexin Yu
- School of Life Science and Technology, ShanghaiTech University, 201210, Shanghai, China
- iHuman Institute, ShanghaiTech University, 201010, Shanghai, China
| | - Chenguang Wang
- Shanghai Institute of Precision Medicine, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, 200125, Shanghai, China
- Shanghai Key Laboratory of Reproductive Medicine, Shanghai Jiao Tong University School of Medicine, 200025, Shanghai, China
- Department of Cardiology, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Guoping Fan
- Shanghai Institute for Advanced Immunochemical Studies, ShanghaiTech University, 201210, Shanghai, China
| | - Suwen Zhao
- School of Life Science and Technology, ShanghaiTech University, 201210, Shanghai, China
- iHuman Institute, ShanghaiTech University, 201010, Shanghai, China
| | - Hanhui Ma
- School of Life Science and Technology, ShanghaiTech University, 201210, Shanghai, China
| | - Alex C Y Chang
- Shanghai Institute of Precision Medicine, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, 200125, Shanghai, China
- Shanghai Key Laboratory of Reproductive Medicine, Shanghai Jiao Tong University School of Medicine, 200025, Shanghai, China
- Department of Cardiology, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Zhi Li
- School of Physical Science and Technology, ShanghaiTech University, 201210, Shanghai, China
| | - Qian Bian
- Shanghai Institute of Precision Medicine, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, 200125, Shanghai, China.
- Shanghai Key Laboratory of Reproductive Medicine, Shanghai Jiao Tong University School of Medicine, 200025, Shanghai, China.
| | - Chao-Po Lin
- School of Life Science and Technology, ShanghaiTech University, 201210, Shanghai, China.
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5
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Wagh K, Stavreva DA, Jensen RAM, Paakinaho V, Fettweis G, Schiltz RL, Wüstner D, Mandrup S, Presman DM, Upadhyaya A, Hager GL. Dynamic switching of transcriptional regulators between two distinct low-mobility chromatin states. SCIENCE ADVANCES 2023; 9:eade1122. [PMID: 37315128 PMCID: PMC10954219 DOI: 10.1126/sciadv.ade1122] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Accepted: 05/10/2023] [Indexed: 06/16/2023]
Abstract
How chromatin dynamics relate to transcriptional activity remains poorly understood. Using single-molecule tracking, coupled with machine learning, we show that histone H2B and multiple chromatin-bound transcriptional regulators display two distinct low-mobility states. Ligand activation results in a marked increase in the propensity of steroid receptors to bind in the lowest-mobility state. Mutational analysis revealed that interactions with chromatin in the lowest-mobility state require an intact DNA binding domain and oligomerization domains. These states are not spatially separated as previously believed, but individual H2B and bound-TF molecules can dynamically switch between them on time scales of seconds. Single bound-TF molecules with different mobilities exhibit different dwell time distributions, suggesting that the mobility of TFs is intimately coupled with their binding dynamics. Together, our results identify two unique and distinct low-mobility states that appear to represent common pathways for transcription activation in mammalian cells.
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Affiliation(s)
- Kaustubh Wagh
- Laboratory of Receptor Biology and Gene Expression, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
- Department of Physics, University of Maryland, College Park, MD 20742, USA
| | - Diana A. Stavreva
- Laboratory of Receptor Biology and Gene Expression, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Rikke A. M. Jensen
- Laboratory of Receptor Biology and Gene Expression, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
| | - Ville Paakinaho
- Laboratory of Receptor Biology and Gene Expression, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
- Institute of Biomedicine, University of Eastern Finland, Kuopio, P.O. Box 1627, 70211 Kuopio, Finland
| | - Gregory Fettweis
- Laboratory of Receptor Biology and Gene Expression, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - R. Louis Schiltz
- Laboratory of Receptor Biology and Gene Expression, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Daniel Wüstner
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
| | - Susanne Mandrup
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
| | - Diego M. Presman
- Laboratory of Receptor Biology and Gene Expression, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
- Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE), CONICET-Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Buenos Aires C1428EGA, Argentina
| | - Arpita Upadhyaya
- Department of Physics, University of Maryland, College Park, MD 20742, USA
- Institute for Physical Science and Technology, University of Maryland, College Park, MD 20742, USA
| | - Gordon L. Hager
- Laboratory of Receptor Biology and Gene Expression, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
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6
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Ball ML, Koestler SA, Muresan L, Rehman SA, O’Holleran K, White R. The anatomy of transcriptionally active chromatin loops in Drosophila primary spermatocytes using super-resolution microscopy. PLoS Genet 2023; 19:e1010654. [PMID: 36867662 PMCID: PMC10016678 DOI: 10.1371/journal.pgen.1010654] [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: 10/20/2022] [Revised: 03/15/2023] [Accepted: 02/04/2023] [Indexed: 03/04/2023] Open
Abstract
While the biochemistry of gene transcription has been well studied, our understanding of how this process is organised in 3D within the intact nucleus is less well understood. Here we investigate the structure of actively transcribed chromatin and the architecture of its interaction with active RNA polymerase. For this analysis, we have used super-resolution microscopy to image the Drosophila melanogaster Y loops which represent huge, several megabases long, single transcription units. The Y loops provide a particularly amenable model system for transcriptionally active chromatin. We find that, although these transcribed loops are decondensed they are not organised as extended 10nm fibres, but rather they largely consist of chains of nucleosome clusters. The average width of each cluster is around 50nm. We find that foci of active RNA polymerase are generally located off the main fibre axis on the periphery of the nucleosome clusters. Foci of RNA polymerase and nascent transcripts are distributed around the Y loops rather than being clustered in individual transcription factories. However, as the RNA polymerase foci are considerably less prevalent than the nucleosome clusters, the organisation of this active chromatin into chains of nucleosome clusters is unlikely to be determined by the activity of the polymerases transcribing the Y loops. These results provide a foundation for understanding the topological relationship between chromatin and the process of gene transcription.
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Affiliation(s)
- Madeleine L. Ball
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Site, Cambridge, United Kingdom
| | - Stefan A. Koestler
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Site, Cambridge, United Kingdom
| | - Leila Muresan
- Cambridge Advanced Imaging Centre, University of Cambridge, Downing Site, Cambridge, United Kingdom
| | - Sohaib Abdul Rehman
- Cambridge Advanced Imaging Centre, University of Cambridge, Downing Site, Cambridge, United Kingdom
| | - Kevin O’Holleran
- Cambridge Advanced Imaging Centre, University of Cambridge, Downing Site, Cambridge, United Kingdom
| | - Robert White
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Site, Cambridge, United Kingdom
- * E-mail:
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7
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SOX2 Modulates the Nuclear Organization and Transcriptional Activity of the Glucocorticoid Receptor. J Mol Biol 2022; 434:167869. [PMID: 36309135 DOI: 10.1016/j.jmb.2022.167869] [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: 07/11/2022] [Revised: 10/07/2022] [Accepted: 10/19/2022] [Indexed: 11/07/2022]
Abstract
Steroid receptors (SRs) are ligand-dependent transcription factors (TFs) relevant to key cellular processes in both physiology and pathology, including some types of cancer. SOX2 is a master TF of pluripotency and self-renewal of embryonic stem cells, and its dysregulation is also associated with various types of human cancers. A potential crosstalk between these TFs could be relevant in malignant cells yet, to the best of our knowledge, no formal study has been performed thus far. Here we show, by quantitative live-cell imaging microscopy, that ectopic expression of SOX2 disrupts the formation of hormone-dependent intranuclear condensates of many steroid receptors (SRs), including those formed by the glucocorticoid receptor (GR). SOX2 also reduces GR's binding to specific DNA targets and modulates its transcriptional activity. SOX2-driven effects on GR condensates do not require the intrinsically disordered N-terminal domain of the receptor and, surprisingly, neither relies on GR/SOX2 interactions. SOX2 also alters the intranuclear dynamics and compartmentalization of the SR coactivator NCoA-2 and impairs GR/NCoA-2 interactions. These results suggest an indirect mechanism underlying SOX2-driven effects on SRs involving this coactivator. Together, these results highlight that the transcriptional program elicited by GR relies on its nuclear organization and is intimately linked to the distribution of other GR partners, such as the NCoA-2 coactivator. Abnormal expression of SOX2, commonly observed in many tumors, may alter the biological action of GR and, probably, other SRs as well. Understanding this crosstalk may help to improve steroid hormone-based therapies in cancers with elevated SOX2 expression.
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8
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Ibrahim Z, Wang T, Destaing O, Salvi N, Hoghoughi N, Chabert C, Rusu A, Gao J, Feletto L, Reynoird N, Schalch T, Zhao Y, Blackledge M, Khochbin S, Panne D. Structural insights into p300 regulation and acetylation-dependent genome organisation. Nat Commun 2022; 13:7759. [PMID: 36522330 PMCID: PMC9755262 DOI: 10.1038/s41467-022-35375-2] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Accepted: 11/29/2022] [Indexed: 12/23/2022] Open
Abstract
Histone modifications are deposited by chromatin modifying enzymes and read out by proteins that recognize the modified state. BRD4-NUT is an oncogenic fusion protein of the acetyl lysine reader BRD4 that binds to the acetylase p300 and enables formation of long-range intra- and interchromosomal interactions. We here examine how acetylation reading and writing enable formation of such interactions. We show that NUT contains an acidic transcriptional activation domain that binds to the TAZ2 domain of p300. We use NMR to investigate the structure of the complex and found that the TAZ2 domain has an autoinhibitory role for p300. NUT-TAZ2 interaction or mutations found in cancer that interfere with autoinhibition by TAZ2 allosterically activate p300. p300 activation results in a self-organizing, acetylation-dependent feed-forward reaction that enables long-range interactions by bromodomain multivalent acetyl-lysine binding. We discuss the implications for chromatin organisation, gene regulation and dysregulation in disease.
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Affiliation(s)
- Ziad Ibrahim
- Leicester Institute of Structural and Chemical Biology, Department of Molecular and Cell Biology, University of Leicester, Leicester, UK
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, United States
| | - Tao Wang
- CNRS UMR 5309, INSERM U1209, Université Grenoble Alpes, Institute for Advanced Biosciences, Grenoble, France
| | - Olivier Destaing
- CNRS UMR 5309, INSERM U1209, Université Grenoble Alpes, Institute for Advanced Biosciences, Grenoble, France
| | - Nicola Salvi
- Institut de Biologie Structurale, CNRS, CEA, UGA, Grenoble, France
| | - Naghmeh Hoghoughi
- CNRS UMR 5309, INSERM U1209, Université Grenoble Alpes, Institute for Advanced Biosciences, Grenoble, France
| | - Clovis Chabert
- CNRS UMR 5309, INSERM U1209, Université Grenoble Alpes, Institute for Advanced Biosciences, Grenoble, France
| | - Alexandra Rusu
- Leicester Institute of Structural and Chemical Biology, Department of Molecular and Cell Biology, University of Leicester, Leicester, UK
| | - Jinjun Gao
- Ben May Department of Cancer Research, The University of Chicago, Chicago, IL, 60637, USA
| | - Leonardo Feletto
- Leicester Institute of Structural and Chemical Biology, Department of Molecular and Cell Biology, University of Leicester, Leicester, UK
| | - Nicolas Reynoird
- CNRS UMR 5309, INSERM U1209, Université Grenoble Alpes, Institute for Advanced Biosciences, Grenoble, France
| | - Thomas Schalch
- Leicester Institute of Structural and Chemical Biology, Department of Molecular and Cell Biology, University of Leicester, Leicester, UK
| | - Yingming Zhao
- Ben May Department of Cancer Research, The University of Chicago, Chicago, IL, 60637, USA
| | | | - Saadi Khochbin
- CNRS UMR 5309, INSERM U1209, Université Grenoble Alpes, Institute for Advanced Biosciences, Grenoble, France
| | - Daniel Panne
- Leicester Institute of Structural and Chemical Biology, Department of Molecular and Cell Biology, University of Leicester, Leicester, UK.
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9
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The sight of transcription. Nat Cell Biol 2022; 24:284-285. [DOI: 10.1038/s41556-022-00865-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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10
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Kimura H, Sato Y. Imaging transcription elongation dynamics by new technologies unveils the organization of initiation and elongation in transcription factories. Curr Opin Cell Biol 2022; 74:71-79. [DOI: 10.1016/j.ceb.2022.01.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2021] [Revised: 01/05/2022] [Accepted: 01/10/2022] [Indexed: 11/27/2022]
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11
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Winick-Ng W, Kukalev A, Harabula I, Zea-Redondo L, Szabó D, Meijer M, Serebreni L, Zhang Y, Bianco S, Chiariello AM, Irastorza-Azcarate I, Thieme CJ, Sparks TM, Carvalho S, Fiorillo L, Musella F, Irani E, Torlai Triglia E, Kolodziejczyk AA, Abentung A, Apostolova G, Paul EJ, Franke V, Kempfer R, Akalin A, Teichmann SA, Dechant G, Ungless MA, Nicodemi M, Welch L, Castelo-Branco G, Pombo A. Cell-type specialization is encoded by specific chromatin topologies. Nature 2021; 599:684-691. [PMID: 34789882 PMCID: PMC8612935 DOI: 10.1038/s41586-021-04081-2] [Citation(s) in RCA: 77] [Impact Index Per Article: 25.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Accepted: 09/30/2021] [Indexed: 11/09/2022]
Abstract
The three-dimensional (3D) structure of chromatin is intrinsically associated with gene regulation and cell function1-3. Methods based on chromatin conformation capture have mapped chromatin structures in neuronal systems such as in vitro differentiated neurons, neurons isolated through fluorescence-activated cell sorting from cortical tissues pooled from different animals and from dissociated whole hippocampi4-6. However, changes in chromatin organization captured by imaging, such as the relocation of Bdnf away from the nuclear periphery after activation7, are invisible with such approaches8. Here we developed immunoGAM, an extension of genome architecture mapping (GAM)2,9, to map 3D chromatin topology genome-wide in specific brain cell types, without tissue disruption, from single animals. GAM is a ligation-free technology that maps genome topology by sequencing the DNA content from thin (about 220 nm) nuclear cryosections. Chromatin interactions are identified from the increased probability of co-segregation of contacting loci across a collection of nuclear slices. ImmunoGAM expands the scope of GAM to enable the selection of specific cell types using low cell numbers (approximately 1,000 cells) within a complex tissue and avoids tissue dissociation2,10. We report cell-type specialized 3D chromatin structures at multiple genomic scales that relate to patterns of gene expression. We discover extensive 'melting' of long genes when they are highly expressed and/or have high chromatin accessibility. The contacts most specific of neuron subtypes contain genes associated with specialized processes, such as addiction and synaptic plasticity, which harbour putative binding sites for neuronal transcription factors within accessible chromatin regions. Moreover, sensory receptor genes are preferentially found in heterochromatic compartments in brain cells, which establish strong contacts across tens of megabases. Our results demonstrate that highly specific chromatin conformations in brain cells are tightly related to gene regulation mechanisms and specialized functions.
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Affiliation(s)
- Warren Winick-Ng
- Max-Delbrück Centre for Molecular Medicine, Berlin Institute for Medical Systems Biology, Epigenetic Regulation and Chromatin Architecture Group, Berlin, Germany.
| | - Alexander Kukalev
- Max-Delbrück Centre for Molecular Medicine, Berlin Institute for Medical Systems Biology, Epigenetic Regulation and Chromatin Architecture Group, Berlin, Germany
| | - Izabela Harabula
- Max-Delbrück Centre for Molecular Medicine, Berlin Institute for Medical Systems Biology, Epigenetic Regulation and Chromatin Architecture Group, Berlin, Germany
- Institute of Biology, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Luna Zea-Redondo
- Max-Delbrück Centre for Molecular Medicine, Berlin Institute for Medical Systems Biology, Epigenetic Regulation and Chromatin Architecture Group, Berlin, Germany
- Institute of Biology, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Dominik Szabó
- Max-Delbrück Centre for Molecular Medicine, Berlin Institute for Medical Systems Biology, Epigenetic Regulation and Chromatin Architecture Group, Berlin, Germany
- Institute of Biology, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Mandy Meijer
- Laboratory of Molecular Neurobiology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Leonid Serebreni
- Max-Delbrück Centre for Molecular Medicine, Berlin Institute for Medical Systems Biology, Epigenetic Regulation and Chromatin Architecture Group, Berlin, Germany
- Research Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), Vienna, Austria
| | - Yingnan Zhang
- School of Electrical Engineering and Computer Science, Ohio University, Athens, OH, USA
| | - Simona Bianco
- Dipartimentio di Fisica, Università di Napoli Federico II, and INFN Napoli, Complesso Universitario di Monte Sant'Angelo, Naples, Italy
| | - Andrea M Chiariello
- Dipartimentio di Fisica, Università di Napoli Federico II, and INFN Napoli, Complesso Universitario di Monte Sant'Angelo, Naples, Italy
| | - Ibai Irastorza-Azcarate
- Max-Delbrück Centre for Molecular Medicine, Berlin Institute for Medical Systems Biology, Epigenetic Regulation and Chromatin Architecture Group, Berlin, Germany
| | - Christoph J Thieme
- Max-Delbrück Centre for Molecular Medicine, Berlin Institute for Medical Systems Biology, Epigenetic Regulation and Chromatin Architecture Group, Berlin, Germany
| | - Thomas M Sparks
- Max-Delbrück Centre for Molecular Medicine, Berlin Institute for Medical Systems Biology, Epigenetic Regulation and Chromatin Architecture Group, Berlin, Germany
| | - Sílvia Carvalho
- Max-Delbrück Centre for Molecular Medicine, Berlin Institute for Medical Systems Biology, Epigenetic Regulation and Chromatin Architecture Group, Berlin, Germany
- UCIBIO, Department of Life Sciences, NOVA School of Science and Technology, Universidade NOVA de Lisboa, Caparica, Portugal
- Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto, Porto, Portugal
- Graduate Program in Areas of Basic and Applied Biology, Universidade do Porto, Porto, Portugal
| | - Luca Fiorillo
- Dipartimentio di Fisica, Università di Napoli Federico II, and INFN Napoli, Complesso Universitario di Monte Sant'Angelo, Naples, Italy
| | - Francesco Musella
- Dipartimentio di Fisica, Università di Napoli Federico II, and INFN Napoli, Complesso Universitario di Monte Sant'Angelo, Naples, Italy
| | - Ehsan Irani
- Max-Delbrück Centre for Molecular Medicine, Berlin Institute for Medical Systems Biology, Epigenetic Regulation and Chromatin Architecture Group, Berlin, Germany
- Berlin Institute of Health, Berlin, Germany
| | - Elena Torlai Triglia
- Max-Delbrück Centre for Molecular Medicine, Berlin Institute for Medical Systems Biology, Epigenetic Regulation and Chromatin Architecture Group, Berlin, Germany
- Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Aleksandra A Kolodziejczyk
- Cavendish Laboratory, University of Cambridge, Cambridge, UK
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, UK
- Immunology Department, Weizmann Institute of Science, Rehovot, Israel
| | - Andreas Abentung
- Institute for Neuroscience, Medical University of Innsbruck, Innsbruck, Austria
- Department of Clinical and Molecular Medicine, Norwegian University of Science and Technology, Trondheim, Norway
| | - Galina Apostolova
- Institute for Neuroscience, Medical University of Innsbruck, Innsbruck, Austria
| | - Eleanor J Paul
- Institute of Clinical Sciences, Imperial College London, London, UK
- Center for Developmental Neurobiology, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK
- MRC Center for Neurodevelopmental Disorders, King's College London, London, UK
| | - Vedran Franke
- Max-Delbrück Centre for Molecular Medicine, Berlin Institute for Medical Systems Biology, Bioinformatics and Omics Data Science Platform, Berlin, Germany
| | - Rieke Kempfer
- Max-Delbrück Centre for Molecular Medicine, Berlin Institute for Medical Systems Biology, Epigenetic Regulation and Chromatin Architecture Group, Berlin, Germany
- Institute of Biology, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Altuna Akalin
- Max-Delbrück Centre for Molecular Medicine, Berlin Institute for Medical Systems Biology, Bioinformatics and Omics Data Science Platform, Berlin, Germany
| | - Sarah A Teichmann
- Cavendish Laboratory, University of Cambridge, Cambridge, UK
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, UK
| | - Georg Dechant
- Institute for Neuroscience, Medical University of Innsbruck, Innsbruck, Austria
| | - Mark A Ungless
- Institute of Clinical Sciences, Imperial College London, London, UK
| | - Mario Nicodemi
- Dipartimentio di Fisica, Università di Napoli Federico II, and INFN Napoli, Complesso Universitario di Monte Sant'Angelo, Naples, Italy
- Berlin Institute of Health, Berlin, Germany
| | - Lonnie Welch
- School of Electrical Engineering and Computer Science, Ohio University, Athens, OH, USA
| | - Gonçalo Castelo-Branco
- Laboratory of Molecular Neurobiology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
- Ming Wai Lau Centre for Reparative Medicine, Stockholm node, Karolinska Institutet, Stockholm, Sweden
| | - Ana Pombo
- Max-Delbrück Centre for Molecular Medicine, Berlin Institute for Medical Systems Biology, Epigenetic Regulation and Chromatin Architecture Group, Berlin, Germany.
- Institute of Biology, Humboldt-Universität zu Berlin, Berlin, Germany.
- Berlin Institute of Health, Berlin, Germany.
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12
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Vettorazzi S, Nalbantoglu D, Gebhardt JCM, Tuckermann J. A guide to changing paradigms of glucocorticoid receptor function-a model system for genome regulation and physiology. FEBS J 2021; 289:5718-5743. [PMID: 34213830 DOI: 10.1111/febs.16100] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Revised: 06/08/2021] [Accepted: 07/01/2021] [Indexed: 12/13/2022]
Abstract
The glucocorticoid receptor (GR) is a bona fide ligand-regulated transcription factor. Cloned in the 80s, the GR has become one of the best-studied and clinically most relevant members of the nuclear receptor superfamily. Cooperative activity of GR with other transcription factors and a plethora of coregulators contribute to the tissue- and context-specific response toward the endogenous and pharmacological glucocorticoids (GCs). Furthermore, nontranscriptional activities in the cytoplasm are emerging as an additional function of GR. Over the past 40 years, the concepts of GR mechanisms of action had been constantly changing. Different methodologies in the pregenomic and genomic era of molecular biological research and recent cutting-edge technology in single-cell and single-molecule analysis are steadily evolving the views, how the GR in particular and transcriptional regulation in general act in physiological and pathological processes. In addition to the development of technologies for GR analysis, the use of model organisms provides insights how the GR in vivo executes GC action in tissue homeostasis, inflammation, and energy metabolism. The model organisms, namely the mouse, but also rats, zebrafish, and recently fruit flies carrying mutations of the GR became a major driving force to analyze the molecular function of GR in disease models. This guide provides an overview of the exciting research and paradigm shifts in the GR field from past to present with a focus on GR transcription factor networks, GR DNA-binding and single-cell analysis, and model systems.
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Affiliation(s)
- Sabine Vettorazzi
- Institute of Comparative Molecular Endocrinology (CME), Ulm University, Germany
| | - Denis Nalbantoglu
- Institute of Comparative Molecular Endocrinology (CME), Ulm University, Germany
| | | | - Jan Tuckermann
- Institute of Comparative Molecular Endocrinology (CME), Ulm University, Germany
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13
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Weems JC, Slaughter BD, Unruh JR, Weaver KJ, Miller BD, Delventhal KM, Conaway JW, Conaway RC. A role for the Cockayne Syndrome B (CSB)-Elongin ubiquitin ligase complex in signal-dependent RNA polymerase II transcription. J Biol Chem 2021; 297:100862. [PMID: 34116057 PMCID: PMC8294581 DOI: 10.1016/j.jbc.2021.100862] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Revised: 05/27/2021] [Accepted: 06/07/2021] [Indexed: 11/19/2022] Open
Abstract
The Elongin complex was originally identified as an RNA polymerase II (RNAPII) elongation factor and subsequently as the substrate recognition component of a Cullin-RING E3 ubiquitin ligase. More recent evidence indicates that the Elongin ubiquitin ligase assembles with the Cockayne syndrome B helicase (CSB) in response to DNA damage and can target stalled polymerases for ubiquitylation and removal from the genome. In this report, we present evidence that the CSB-Elongin ubiquitin ligase pathway has roles beyond the DNA damage response in the activation of RNAPII-mediated transcription. We observed that assembly of the CSB-Elongin ubiquitin ligase is induced not just by DNA damage, but also by a variety of signals that activate RNAPII-mediated transcription, including endoplasmic reticulum (ER) stress, amino acid starvation, retinoic acid, glucocorticoids, and doxycycline treatment of cells carrying several copies of a doxycycline-inducible reporter. Using glucocorticoid receptor (GR)-regulated genes as a model, we showed that glucocorticoid-induced transcription is accompanied by rapid recruitment of CSB and the Elongin ubiquitin ligase to target genes in a step that depends upon the presence of transcribing RNAPII on those genes. Consistent with the idea that the CSB-Elongin pathway plays a direct role in GR-regulated transcription, mouse cells lacking the Elongin subunit Elongin A exhibit delays in both RNAPII accumulation on and dismissal from target genes following glucocorticoid addition and withdrawal, respectively. Taken together, our findings bring to light a new role for the CSB-Elongin pathway in RNAPII-mediated transcription.
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Affiliation(s)
- Juston C Weems
- Stowers Institute for Medical Research, Kansas City, Missouri, USA
| | | | - Jay R Unruh
- Stowers Institute for Medical Research, Kansas City, Missouri, USA
| | - Kyle J Weaver
- Stowers Institute for Medical Research, Kansas City, Missouri, USA
| | - Brandon D Miller
- Stowers Institute for Medical Research, Kansas City, Missouri, USA
| | - Kym M Delventhal
- Stowers Institute for Medical Research, Kansas City, Missouri, USA
| | - Joan W Conaway
- Stowers Institute for Medical Research, Kansas City, Missouri, USA; Department of Biochemistry & Molecular Biology, University of Kansas Medical Center, Kansas City, Kansas, USA.
| | - Ronald C Conaway
- Stowers Institute for Medical Research, Kansas City, Missouri, USA; Department of Biochemistry & Molecular Biology, University of Kansas Medical Center, Kansas City, Kansas, USA.
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14
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Misteli T. The Self-Organizing Genome: Principles of Genome Architecture and Function. Cell 2020; 183:28-45. [PMID: 32976797 PMCID: PMC7541718 DOI: 10.1016/j.cell.2020.09.014] [Citation(s) in RCA: 287] [Impact Index Per Article: 71.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2020] [Revised: 08/03/2020] [Accepted: 09/02/2020] [Indexed: 01/17/2023]
Abstract
Genomes have complex three-dimensional architectures. The recent convergence of genetic, biochemical, biophysical, and cell biological methods has uncovered several fundamental principles of genome organization. They highlight that genome function is a major driver of genome architecture and that structural features of chromatin act as modulators, rather than binary determinants, of genome activity. The interplay of these principles in the context of self-organization can account for the emergence of structural chromatin features, the diversity and single-cell heterogeneity of nuclear architecture in cell types and tissues, and explains evolutionarily conserved functional features of genomes, including plasticity and robustness.
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Affiliation(s)
- Tom Misteli
- National Cancer Institute, NIH, Bethesda, MD 20892, USA.
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15
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Shi G, Liu L, Hyeon C, Thirumalai D. Interphase human chromosome exhibits out of equilibrium glassy dynamics. Nat Commun 2018; 9:3161. [PMID: 30089831 PMCID: PMC6082855 DOI: 10.1038/s41467-018-05606-6] [Citation(s) in RCA: 90] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2017] [Accepted: 07/05/2018] [Indexed: 01/01/2023] Open
Abstract
Fingerprints of the three-dimensional organization of genomes have emerged using advances in Hi-C and imaging techniques. However, genome dynamics is poorly understood. Here, we create the chromosome copolymer model (CCM) by representing chromosomes as a copolymer with two epigenetic loci types corresponding to euchromatin and heterochromatin. Using novel clustering techniques, we establish quantitatively that the simulated contact maps and topologically associating domains (TADs) for chromosomes 5 and 10 and those inferred from Hi-C experiments are in good agreement. Chromatin exhibits glassy dynamics with coherent motion on micron scale. The broad distribution of the diffusion exponents of the individual loci, which quantitatively agrees with experiments, is suggestive of highly heterogeneous dynamics. This is reflected in the cell-to-cell variations in the contact maps. Chromosome organization is hierarchical, involving the formation of chromosome droplets (CDs) on genomic scale, coinciding with the TAD size, followed by coalescence of the CDs, reminiscent of Ostwald ripening.
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Affiliation(s)
- Guang Shi
- Biophysics Program, Institute for Physical Science and Technology, University of Maryland, College Park, MD, 20742, USA
| | - Lei Liu
- Korea Institute for Advanced Study, Seoul, 02455, Republic of Korea
| | - Changbong Hyeon
- Korea Institute for Advanced Study, Seoul, 02455, Republic of Korea
| | - D Thirumalai
- Department of Chemistry, University of Texas at Austin, Austin, TX, 78712, USA.
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16
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Jubb AW, Boyle S, Hume DA, Bickmore WA. Glucocorticoid Receptor Binding Induces Rapid and Prolonged Large-Scale Chromatin Decompaction at Multiple Target Loci. Cell Rep 2018; 21:3022-3031. [PMID: 29241532 PMCID: PMC5745231 DOI: 10.1016/j.celrep.2017.11.053] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Revised: 10/01/2017] [Accepted: 11/15/2017] [Indexed: 12/26/2022] Open
Abstract
Glucocorticoids act by binding to the glucocorticoid receptor (GR), which binds to specific motifs within enhancers of target genes to activate transcription. Previous studies have suggested that GRs can promote interactions between gene promoters and distal elements within target loci. In contrast, we demonstrate here that glucocorticoid addition to mouse bone-marrow-derived macrophages produces very rapid chromatin unfolding detectable by fluorescence in situ hybridization (FISH) at loci associated with GR binding. Rapid chromatin decompaction was generally not dependent on transcription at those loci that are known to be inducible in both mouse and human macrophages and was sustained for up to 5 days following ligand removal. Chromatin decompaction was not dependent upon persistent GR binding, which decayed fully after 24 hr. We suggest that sustained large-scale chromatin reorganization forms an important part of the response to glucocorticoid and might contribute to glucocorticoid sensitivity and resistance. Glucocorticoids can induce rapid and persistent chromatin decompaction Transcription is not essential for chromatin decompaction Large-scale chromatin organization may modulate the glucocorticoid response
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Affiliation(s)
- Alasdair W Jubb
- MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, The University of Edinburgh, Crewe Road, Edinburgh EH4 2XU, UK; The Roslin Institute and Royal (Dick) School of Veterinary Studies, The University of Edinburgh, Easter Bush, Midlothian EH25 9RG, UK; Department of Medicine, University of Cambridge, Box 93, Addenbrookes Hospital, Hills Road, Cambridge CB2 2QQ, UK
| | - Shelagh Boyle
- MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, The University of Edinburgh, Crewe Road, Edinburgh EH4 2XU, UK
| | - David A Hume
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, The University of Edinburgh, Easter Bush, Midlothian EH25 9RG, UK; Mater Research-University of Queensland, Translational Research Institute, 37 Kent Street, Woolloongabba, QLD 4102, Australia.
| | - Wendy A Bickmore
- MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, The University of Edinburgh, Crewe Road, Edinburgh EH4 2XU, UK.
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17
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Mapping the Dynamics of the Glucocorticoid Receptor within the Nuclear Landscape. Sci Rep 2017; 7:6219. [PMID: 28740156 PMCID: PMC5524710 DOI: 10.1038/s41598-017-06676-0] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2017] [Accepted: 06/15/2017] [Indexed: 12/28/2022] Open
Abstract
The distribution of the transcription machinery among different sub-nuclear domains raises the question on how the architecture of the nucleus modulates the transcriptional response. Here, we used fluorescence fluctuation analyses to quantitatively explore the organization of the glucocorticoid receptor (GR) in the interphase nucleus of living cells. We found that this ligand-activated transcription factor diffuses within the nucleus and dynamically interacts with bodies enriched in the coregulator NCoA-2, DNA-dependent foci and chromatin targets. The distribution of the receptor among the nuclear compartments depends on NCoA-2 and the conformation of the receptor as assessed with synthetic ligands and GR mutants with impaired transcriptional abilities. Our results suggest that the partition of the receptor in different nuclear reservoirs ultimately regulates the concentration of receptor available for the interaction with specific targets, and thus has an impact on transcription regulation.
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18
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Cai YD, Zhang Q, Zhang YH, Chen L, Huang T. Identification of Genes Associated with Breast Cancer Metastasis to Bone on a Protein–Protein Interaction Network with a Shortest Path Algorithm. J Proteome Res 2017; 16:1027-1038. [DOI: 10.1021/acs.jproteome.6b00950] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- Yu-Dong Cai
- School
of Life Sciences, Shanghai University, Shanghai 200444 People’s Republic of China
| | - Qing Zhang
- School
of Life Sciences, Shanghai University, Shanghai 200444 People’s Republic of China
| | - Yu-Hang Zhang
- Institute
of Health Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, People’s Republic of China
| | - Lei Chen
- College
of Information Engineering, Shanghai Maritime University, Shanghai 201306, People’s Republic of China
| | - Tao Huang
- Institute
of Health Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, People’s Republic of China
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19
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Vaňková Hausnerová V, Lanctôt C. Chromatin decondensation is accompanied by a transient increase in transcriptional output. Biol Cell 2016; 109:65-79. [PMID: 27633335 DOI: 10.1111/boc.201600032] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2016] [Revised: 09/12/2016] [Accepted: 09/13/2016] [Indexed: 12/26/2022]
Abstract
BACKGROUND INFORMATION The levels of chromatin condensation usually correlate inversely with the levels of transcription. The mechanistic links between chromatin condensation and RNA polymerase II activity remain to be elucidated. In the present work, we sought to experimentally determine whether manipulation of chromatin condensation levels can have a direct effect on transcriptional activity. RESULTS We generated a U-2-OS cell line in which the nascent transcription of a reporter gene could be imaged alongside chromatin compaction levels in living cells. The transcripts were tagged at their 5' end with PP7 stem loops, which can be detected upon expression of a PP7 capsid protein fused to green fluorescent protein. Cycles of global chromatin hypercondensation and decondensation were performed by perfusing culture media of different osmolarities during imaging. We used the fluorescence recovery after photobleaching technique to analyse the transcriptional dynamics in both conditions. Surprisingly, we found that, despite a drop in signal intensity, nascent transcription appeared to continue at the same rate in hypercondensed chromatin. Furthermore, quantification of transcriptional profiles revealed that chromatin decondensation was accompanied by a brief and transient spike in transcriptional output. CONCLUSIONS We propose a model whereby the initiation of transcription is not impaired in condensed chromatin, but inefficient elongation in these conditions leads to the accumulation of RNA polymerase II at the transcription site. Upon chromatin decondensation, release of the RNA polymerase II halt triggers a wave of transcription, which we detect as a transient spike in activity. SIGNIFICANCE The results presented here shed light on the activity of RNA polymerase II during chromatin condensation and decondensation. As such, they point to a new level of transcriptional regulation.
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Affiliation(s)
- Viola Vaňková Hausnerová
- Institute of Cellular Biology and Pathology, First Faculty of Medicine, Charles University, Prague, Czech Republic.,BIOCEV and Department of Cell Biology, Faculty of Science, Charles University, Vestec u Prahy, 252 50, Czech Republic
| | - Christian Lanctôt
- Institute of Cellular Biology and Pathology, First Faculty of Medicine, Charles University, Prague, Czech Republic.,BIOCEV and Department of Cell Biology, Faculty of Science, Charles University, Vestec u Prahy, 252 50, Czech Republic
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20
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Xist imprinting is promoted by the hemizygous (unpaired) state in the male germ line. Proc Natl Acad Sci U S A 2015; 112:14415-22. [PMID: 26489649 DOI: 10.1073/pnas.1519528112] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The long noncoding X-inactivation-specific transcript (Xist gene) is responsible for mammalian X-chromosome dosage compensation between the sexes, the process by which one of the two X chromosomes is inactivated in the female soma. Xist is essential for both the random and imprinted forms of X-chromosome inactivation. In the imprinted form, Xist is paternally marked to be expressed in female embryos. To investigate the mechanism of Xist imprinting, we introduce Xist transgenes (Tg) into the male germ line. Although ectopic high-level Xist expression on autosomes can be compatible with viability, transgenic animals demonstrate reduced fitness, subfertility, defective meiotic pairing, and other germ-cell abnormalities. In the progeny, paternal-specific expression is recapitulated by the 200-kb Xist Tg. However, Xist imprinting occurs efficiently only when it is in an unpaired or unpartnered state during male meiosis. When transmitted from a hemizygous father (+/Tg), the Xist Tg demonstrates paternal-specific expression in the early embryo. When transmitted by a homozygous father (Tg/Tg), the Tg fails to show imprinted expression. Thus, Xist imprinting is directed by sequences within a 200-kb X-linked region, and the hemizygous (unpaired) state of the Xist region promotes its imprinting in the male germ line.
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21
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Lee K, Kim JH, Kwon H. The Actin-Related Protein BAF53 Is Essential for Chromosomal Subdomain Integrity. Mol Cells 2015; 38:789-95. [PMID: 26242195 PMCID: PMC4588722 DOI: 10.14348/molcells.2015.0109] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2015] [Revised: 05/26/2015] [Accepted: 05/28/2015] [Indexed: 01/09/2023] Open
Abstract
A chromosome territory is composed of chromosomal subdomains. The internal structure of chromosomal subdomains provides a structural framework for many genomic activities such as replication and DNA repair, and thus is key to determining the basis of their mechanisms. However, the internal structure and regulating proteins of a chromosomal subdomain remains elusive. Previously, we showed that the chromosome territory expanded after BAF53 knockdown. Because the integrity of chromosomal subdomains is a deciding factor of the volume of a chromosome territory, we examined here the effect of BAF53 knockdown on chromosomal subdomains. We found that BAF53 knockdown led to the disintegration of histone H2B-GFP-visualized chromosomal subdomains and BrdU-labeled replication foci. In addition, the size of DNA loops measured by the maximum fluorescent halo technique increased and became irregular after BAF53 knockdown, indicating DNA loops were released from the residual nuclear structure. These data can be accounted for by the model that BAF53 is prerequisite for maintaining the structural integrity of chromosomal subdomains.
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Affiliation(s)
- Kiwon Lee
- Department of Bioscience and Biotechnology and Protein Research Center for Bio-Industry, Hankuk University of Foreign Studies, Yongin 449-791,
Korea
| | - Ji Hye Kim
- Department of Bioscience and Biotechnology and Protein Research Center for Bio-Industry, Hankuk University of Foreign Studies, Yongin 449-791,
Korea
| | - Hyockman Kwon
- Department of Bioscience and Biotechnology and Protein Research Center for Bio-Industry, Hankuk University of Foreign Studies, Yongin 449-791,
Korea
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22
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Abstract
Chromatin, once thought to serve only as a means to package DNA, is now recognized as a major regulator of gene activity. As a result of the wide range of methods used to describe the numerous levels of chromatin organization, the terminology that has emerged to describe these organizational states is often imprecise and sometimes misleading. In this review, we discuss our current understanding of chromatin architecture and propose terms to describe the various biochemical and structural states of chromatin.
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Affiliation(s)
- Liron Even-Faitelson
- Program in Genetics and Genome Biology, The Hospital for Sick Children, 686 Bay Street, Toronto, ON, M5G 0A4, Canada
| | | | - Zahra Baghestani
- Program in Genetics and Genome Biology, The Hospital for Sick Children, 686 Bay Street, Toronto, ON, M5G 0A4, Canada
| | - David P Bazett-Jones
- Program in Genetics and Genome Biology, The Hospital for Sick Children, 686 Bay Street, Toronto, ON, M5G 0A4, Canada.
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23
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Dełeńko K, Niedojadło J, Łabędzka A, Wiśniewska E, Bednarska-Kozakiewicz E. Dedifferentiation of Arabidopsis thaliana cells is accompanied by a strong decrease in RNA polymerase II transcription activity and poly(A+) RNA and 25S rRNA eradication from the cytoplasm. PROTOPLASMA 2015; 252:537-46. [PMID: 25248757 PMCID: PMC4335095 DOI: 10.1007/s00709-014-0700-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Accepted: 09/09/2014] [Indexed: 05/09/2023]
Abstract
The mechanisms of plant cell dedifferentiation and the acquisition of totipotency are poorly understood. One of the methods to induce the dedifferentiation process in plant cells is simple and requires the removal of the cell wall. After cell wall removal in protoplasts, large-scale chromatin decondensation is observed (Tessadori et al. in J Cell Sci 120:1200-1208, 2007). Here, we show that in Arabidopsis thaliana protoplasts, despite chromatin decondensation, RNA polymerase II transcriptional activity is reduced. The subsequent investigated stages displayed a clear decrease in the quantity of 25S ribosomal RNA (rRNA) first and then poly(A+) RNA, particularly in the cytoplasm. Therefore, the reduced transcription activity and the removal of these RNA transcripts from the cytoplasm is a crucial process in obtaining totipotency in plant cells. After the cytoplasm cleaning of transcripts derived from mesophyll cells, we observed the resynthesis of these RNAs. An increase in the amount of examined molecules to a level similar to that in differentiated mesophyll cells precedes the divisions of already undifferentiated cells. In this work, we show changes in RNA polymerase II transcription dynamics and the quantity of poly(A+) RNA and 25S rRNA during dedifferentiation and re-entry into the cell cycle.
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Affiliation(s)
- Konrad Dełeńko
- Department of Cell Biology, Faculty of Biology and Environment Protection, Nicolaus Copernicus University, Gagarina 9, 87-100 Toruń, Poland
| | - Janusz Niedojadło
- Department of Cell Biology, Faculty of Biology and Environment Protection, Nicolaus Copernicus University, Gagarina 9, 87-100 Toruń, Poland
| | - Agata Łabędzka
- Department of Cell Biology, Faculty of Biology and Environment Protection, Nicolaus Copernicus University, Gagarina 9, 87-100 Toruń, Poland
| | - Ewa Wiśniewska
- Department of Clinical Pathomorphology, Ludwik Rydygier Collegium Medium Bydgoszcz, Nicolaus Copernicus University in Toruń, Skłodowskiej-Curie 9, 85-094 Bydgoszcz, Poland
| | - Elżbieta Bednarska-Kozakiewicz
- Department of Cell Biology, Faculty of Biology and Environment Protection, Nicolaus Copernicus University, Gagarina 9, 87-100 Toruń, Poland
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24
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Szafran AT, Mancini MA. The myImageAnalysis project: a web-based application for high-content screening. Assay Drug Dev Technol 2014; 12:87-99. [PMID: 24547743 DOI: 10.1089/adt.2013.532] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
A major challenge faced by screening centers developing image-based assays is the wide range of assays needed compared to the limited resources that are available to effectively analyze and manage them. To overcome this limitation, we have developed the web-based myImageAnalysis (mIA) application, integrated with an open database connectivity compliant database and powered by Pipeline Pilot (PLP) that incorporates dataset tracking, scheduling and archiving, image analysis, and data reporting. For system administrators, mIA provides automated methods for managing and archiving data. For the biologist, this application allows those without any programming or image analysis experience to quickly develop, validate, and share results of complex image-based assays. Further, the structure of the application within PLP allows those with experience in PLP programming to easily add additional analysis tools as required. The tools within mIA allow users to assess basic (cell count, protein per cell, protein subcellular localization) and more advanced (engineered cell lines analysis, cell toxicity) biological image-based assays that employ advanced statistics and provides key assay performance metrics.
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Affiliation(s)
- Adam T Szafran
- Department of Molecular and Cellular Biology, Baylor College of Medicine , Houston, Texas
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25
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Single-molecule analysis of transcription factor binding at transcription sites in live cells. Nat Commun 2014; 5:4456. [PMID: 25034201 PMCID: PMC4144071 DOI: 10.1038/ncomms5456] [Citation(s) in RCA: 120] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2013] [Accepted: 06/19/2014] [Indexed: 12/22/2022] Open
Abstract
Although numerous live-cell measurements have shown that transcription factors (TFs) bind chromatin transiently, no measurements of transient binding have been reported at the endogenous response elements (REs) where transcription is normally induced. Here we show that at endogenous REs the transcriptionally productive specific binding of two TFs, p53 and the glucocorticoid receptor (GR), is transient. We also find that the transient residence times of GR at endogenous REs are roughly comparable to those at an artificial, multi-copy array of gene regulatory sites, supporting the use of multi-copy arrays for live-cell analysis of transcription. Finally, we find that at any moment only a small fraction of TF molecules are engaged in transcriptionally productive binding at endogenous REs. The small fraction of bound factors provides one explanation for gene bursting and it also indicates that REs may often be unoccupied, resulting in partial responses to transcriptional signals.
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Belmont AS. Large-scale chromatin organization: the good, the surprising, and the still perplexing. Curr Opin Cell Biol 2013; 26:69-78. [PMID: 24529248 DOI: 10.1016/j.ceb.2013.10.002] [Citation(s) in RCA: 101] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2013] [Revised: 10/07/2013] [Accepted: 10/15/2013] [Indexed: 11/19/2022]
Abstract
Traditionally large-scale chromatin structure has been studied by microscopic approaches, providing direct spatial information but limited sequence context. In contrast, newer 3C (chromosome capture conformation) methods provide rich sequence context but uncertain spatial context. Recent demonstration of large, topologically linked DNA domains, hundreds to thousands of kb in size, may now link 3C data to actual chromosome physical structures, as visualized directly by microscopic methods. Yet, new data suggesting that 3C may measure cytological rather than molecular proximity prompts a renewed focus on understanding the origin of 3C interactions and dissecting the biological significance of long-range genomic interactions.
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Affiliation(s)
- Andrew S Belmont
- Department of Cell and Developmental Biology, University of Illinois, Urbana-Champaign, B107 CLSL, 601 South Goodwin Avenue, Urbana, IL 61801, United States.
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Raghuram N, Strickfaden H, McDonald D, Williams K, Fang H, Mizzen C, Hayes JJ, Th'ng J, Hendzel MJ. Pin1 promotes histone H1 dephosphorylation and stabilizes its binding to chromatin. ACTA ACUST UNITED AC 2013; 203:57-71. [PMID: 24100296 PMCID: PMC3798258 DOI: 10.1083/jcb.201305159] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The prolyl isomerase Pin1 stimulates the dephosphorylation of histone H1, stabilizing its binding to chromatin at transcriptionally active chromatin. Histone H1 plays a crucial role in stabilizing higher order chromatin structure. Transcriptional activation, DNA replication, and chromosome condensation all require changes in chromatin structure and are correlated with the phosphorylation of histone H1. In this study, we describe a novel interaction between Pin1, a phosphorylation-specific prolyl isomerase, and phosphorylated histone H1. A sub-stoichiometric amount of Pin1 stimulated the dephosphorylation of H1 in vitro and modulated the structure of the C-terminal domain of H1 in a phosphorylation-dependent manner. Depletion of Pin1 destabilized H1 binding to chromatin only when Pin1 binding sites on H1 were present. Pin1 recruitment and localized histone H1 phosphorylation were associated with transcriptional activation independent of RNA polymerase II. We thus identify a novel form of histone H1 regulation through phosphorylation-dependent proline isomerization, which has consequences on overall H1 phosphorylation levels and the stability of H1 binding to chromatin.
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Affiliation(s)
- Nikhil Raghuram
- Department of Oncology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta T6G 2R7, Canada
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28
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Lalmansingh AS, Arora K, Demarco RA, Hager GL, Nagaich AK. High-throughput RNA FISH analysis by imaging flow cytometry reveals that pioneer factor Foxa1 reduces transcriptional stochasticity. PLoS One 2013; 8:e76043. [PMID: 24073287 PMCID: PMC3779185 DOI: 10.1371/journal.pone.0076043] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2012] [Accepted: 08/23/2013] [Indexed: 12/31/2022] Open
Abstract
Genes are regulated at the single-cell level. Here, we performed RNA FISH of thousands of cells by flow cytometry (flow-RNA FISH) to gain insight into transcriptional variability between individual cells. These experiments utilized the murine adenocarcinoma 3134 cell line with 200 copies of the MMTV-Ras reporter integrated at a single genomic locus. The MMTV array contains approximately 800-1200 binding sites for the glucocorticoid receptor (GR) and 600 binding sites for the pioneer factor Foxa1. Hormone activation of endogenous GR by dexamethasone treatment resulted in highly variable changes in the RNA FISH intensity (25-300 pixel intensity units) and size (1.25-15 µm), indicative of probabilistic or stochastic mechanisms governing GR and cofactor activation of the MMTV promoter. Exogenous expression of the pioneer factor Foxa1 increased the FISH signal intensity and size as expected for a chromatin remodeler that enhances transcriptional competence through increased chromatin accessibility. In addition, specific analysis of Foxa1-enriched cell sub-populations showed that low and high Foxa1 levels substantially lowered the cell-to-cell variability in the FISH intensity as determined by a noise calculation termed the % coefficient of variation. These results suggest that an additional function of the pioneer factor Foxa1 may be to decrease transcriptional noise.
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Affiliation(s)
- Avin S Lalmansingh
- Office of Biotechnology Products, Center for Drug Evaluation and Research, Food and Drug Administration, Bethesda, Maryland, United States of America
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29
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Meluzzi D, Arya G. Recovering ensembles of chromatin conformations from contact probabilities. Nucleic Acids Res 2012; 41:63-75. [PMID: 23143266 PMCID: PMC3592477 DOI: 10.1093/nar/gks1029] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
The 3D higher order organization of chromatin within the nucleus of eukaryotic cells has so far remained elusive. A wealth of relevant information, however, is increasingly becoming available from chromosome conformation capture (3C) and related experimental techniques, which measure the probabilities of contact between large numbers of genomic sites in fixed cells. Such contact probabilities (CPs) can in principle be used to deduce the 3D spatial organization of chromatin. Here, we propose a computational method to recover an ensemble of chromatin conformations consistent with a set of given CPs. Compared with existing alternatives, this method does not require conversion of CPs to mean spatial distances. Instead, we estimate CPs by simulating a physically realistic, bead-chain polymer model of the 30-nm chromatin fiber. We then use an approach from adaptive filter theory to iteratively adjust the parameters of this polymer model until the estimated CPs match the given CPs. We have validated this method against reference data sets obtained from simulations of test systems with up to 45 beads and 4 loops. With additional testing against experiments and with further algorithmic refinements, our approach could become a valuable tool for researchers examining the higher order organization of chromatin.
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Affiliation(s)
- Dario Meluzzi
- Department of NanoEngineering, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
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30
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Pham CD, Sims HI, Archer TK, Schnitzler GR. Multiple distinct stimuli increase measured nucleosome occupancy around human promoters. PLoS One 2011; 6:e23490. [PMID: 21853138 PMCID: PMC3154950 DOI: 10.1371/journal.pone.0023490] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2011] [Accepted: 07/18/2011] [Indexed: 11/30/2022] Open
Abstract
Nucleosomes can block access to transcription factors. Thus the precise localization of nucleosomes relative to transcription start sites and other factor binding sites is expected to be a critical component of transcriptional regulation. Recently developed microarray approaches have allowed the rapid mapping of nucleosome positions over hundreds of kilobases (kb) of human genomic DNA, although these approaches have not yet been widely used to measure chromatin changes associated with changes in transcription. Here, we use custom tiling microarrays to reveal changes in nucleosome positions and abundance that occur when hormone-bound glucocorticoid receptor (GR) binds to sites near target gene promoters in human osteosarcoma cells. The most striking change is an increase in measured nucleosome occupancy at sites spanning ∼1 kb upstream and downstream of transcription start sites, which occurs one hour after addition of hormone, but is lost at 4 hours. Unexpectedly, this increase was seen both on GR-regulated and GR-non-regulated genes. In addition, the human SWI/SNF chromatin remodeling factor (a GR co-activator) was found to be important for increased occupancy upon hormone treatment and also for low nucleosome occupancy without hormone. Most surprisingly, similar increases in nucleosome occupancy were also seen on both regulated and non-regulated promoters during differentiation of human myeloid leukemia cells and upon activation of human CD4+ T-cells. These results indicate that dramatic changes in chromatin structure over ∼2 kb of human promoters may occur genomewide and in response to a variety of stimuli, and suggest novel models for transcriptional regulation.
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Affiliation(s)
- Chuong D. Pham
- AstraZeneca R&D Boston, Waltham, Massachusetts, United States of America
| | - Hillel I. Sims
- Department of Biology, Rosenstiel Basic Medical Sciences Research Center, Brandeis University, Waltham, Massachusetts, United States of America
| | - Trevor K. Archer
- Laboratory of Molecular Carcinogenesis, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina, United States of America
| | - Gavin R. Schnitzler
- Molecular Cardiology Research Institute, Tufts Medical Center, Boston, Massachusetts, United States of America
- * E-mail:
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31
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Ishihara S, Schwartz RH. Two-step binding of transcription factors causes sequential chromatin structural changes at the activated IL-2 promoter. THE JOURNAL OF IMMUNOLOGY 2011; 187:3292-9. [PMID: 21832163 DOI: 10.4049/jimmunol.1003173] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Most gene promoters have multiple binding sequences for many transcription factors, but the contribution of each of these factors to chromatin remodeling is still unclear. Although we previously found a dynamic change in the arrangement of nucleosome arrays at the Il2 promoter during T cell activation, its timing preceded that of a decrease in nucleosome occupancy at the promoter. In this article, we show that the initial nucleosome rearrangement was temporally correlated with the binding of NFAT1 and AP-1 (Fos/Jun), whereas the second step occurred in parallel with the recruitment of other transcription factors and RNA polymerase II. Pharmacologic inhibitors for activation of NFAT1 or induction of Fos blocked the initial phase in the sequential changes. This step was not affected, however, by inhibition of c-Jun phosphorylation, which instead blocked the binding of the late transcription factors, the recruitment of CREB-binding protein, and the acetylation of histone H3 at lysine 27. Thus, the sequential recruitment of transcription factors appears to facilitate two separate steps in chromatin remodeling at the Il2 locus.
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Affiliation(s)
- Satoru Ishihara
- Laboratory of Cellular and Molecular Immunology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA
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32
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Abstract
Over the last decade, and especially after the advent of fluorescent in situ hybridization imaging and chromosome conformation capture methods, the availability of experimental data on genome three-dimensional organization has dramatically increased. We now have access to unprecedented details of how genomes organize within the interphase nucleus. Development of new computational approaches to leverage this data has already resulted in the first three-dimensional structures of genomic domains and genomes. Such approaches expand our knowledge of the chromatin folding principles, which has been classically studied using polymer physics and molecular simulations. Our outlook describes computational approaches for integrating experimental data with polymer physics, thereby bridging the resolution gap for structural determination of genomes and genomic domains.
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33
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Abstract
Steroid hormone receptors regulate gene transcription in a highly tissue-specific manner. The local chromatin structure underlying promoters and hormone response elements is a major component involved in controlling these highly restricted expression patterns. Chromatin remodeling complexes, as well as histone and DNA modifying enzymes, are directed to gene-specific regions and create permissive or repressive chromatin environments. These structures further enable proper communication between transcription factors, co-regulators and basic transcription machinery. The regulatory elements active at target genes can be either constitutively accessible to receptors or subject to rapid receptor-dependent modification. The chromatin states responsible for these processes are in turn determined during development and differentiation. Thus access of regulatory factors to elements in chromatin provides a major level of cell selective regulation.
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Affiliation(s)
- Malgorzata Wiench
- Laboratory of Receptor Biology and Gene Expression, National Cancer Institute, Bethesda, MD 20892-5055, USA
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34
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Abstract
Chromatin is by its very nature a repressive environment which restricts the recruitment of transcription factors and acts as a barrier to polymerases. Therefore the complex process of gene activation must operate at two levels. In the first instance, localized chromatin decondensation and nucleosome displacement is required to make DNA accessible. Second, sequence-specific transcription factors need to recruit chromatin modifiers and remodellers to create a chromatin environment that permits the passage of polymerases. In this review I will discuss the chromatin structural changes that occur at active gene loci and at regulatory elements that exist as DNase I hypersensitive sites.
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Affiliation(s)
- Peter N Cockerill
- Experimental Haematology, Leeds Institute of Molecular Medicine, University of Leeds, UK.
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35
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Ashcroft FJ, Newberg JY, Jones ED, Mikic I, Mancini MA. High content imaging-based assay to classify estrogen receptor-α ligands based on defined mechanistic outcomes. Gene 2011; 477:42-52. [PMID: 21256200 PMCID: PMC3086628 DOI: 10.1016/j.gene.2011.01.009] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2010] [Revised: 01/06/2011] [Accepted: 01/07/2011] [Indexed: 01/18/2023]
Abstract
Estrogen receptor-α (ER) is an important target both for therapeutic compounds and endocrine disrupting chemicals (EDCs); however, the mechanisms involved in chemical modulation of regulating ER transcriptional activity are inadequately understood. Here, we report the development of a high content analysis-based assay to describe ER activity that uniquely exploits a microscopically visible multi-copy integration of an ER-regulated promoter. Through automated single-cell analyses, we simultaneously quantified promoter occupancy, recruitment of transcriptional cofactors and large-scale chromatin changes in response to a panel of ER ligands and EDCs. Image-derived multi-parametric data was used to classify a panel of ligand responses at high resolution. We propose this system as a novel technology providing new mechanistic insights into EDC activities in a manner useful for both basic mechanistic studies and drug testing.
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Affiliation(s)
- F J Ashcroft
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX 77030, USA
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36
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Fussner E, Ching RW, Bazett-Jones DP. Living without 30nm chromatin fibers. Trends Biochem Sci 2011; 36:1-6. [PMID: 20926298 DOI: 10.1016/j.tibs.2010.09.002] [Citation(s) in RCA: 133] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2010] [Revised: 09/07/2010] [Accepted: 09/08/2010] [Indexed: 10/19/2022]
Abstract
Eukaryotic genomes must be folded and compacted to fit within the restricted volume of the nucleus. According to the current paradigm, strings of nucleosomes, termed 10nm chromatin fibers, constitute the template of transcriptionally active genomic material. The majority of the genome is maintained in a silenced state through higher-order chromatin assemblies, based on the 30nm chromatin fiber, which excludes activating regulatory factors. New experimental approaches, however, including chromatin conformation capture and cryo-electron microscopy, call into question the in situ evidence for the 30nm chromatin fiber. We suggest that the organization of the genome based on 10nm chromatin fibers is sufficient to describe the complexities of nuclear organization and gene regulation.
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Affiliation(s)
- Eden Fussner
- Program in Genetics and Genome Biology, The Hospital for Sick Children, 101 College Street, East Tower, 15-401T, Toronto, Ontario, M5G 1L7, Canada
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37
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Abstract
The fractal globule is a compact polymer state that emerges during polymer condensation as a result of topological constraints which prevent one region of the chain from passing across another one. This long-lived intermediate state was introduced in 1988 (Grosberg et al. 1988) and has not been observed in experiments or simulations until recently (Lieberman-Aiden et al. 2009). Recent characterization of human chromatin using a novel chromosome conformational capture technique brought the fractal globule into the spotlight as a structural model of human chromosome on the scale of up to 10 Mb (Lieberman-Aiden et al. 2009). Here, we present the concept of the fractal globule, comparing it to other states of a polymer and focusing on its properties relevant for the biophysics of chromatin. We then discuss properties of the fractal globule that make it an attractive model for chromatin organization inside a cell. Next, we connect the fractal globule to recent studies that emphasize topological constraints as a primary factor driving formation of chromosomal territories. We discuss how theoretical predictions, made on the basis of the fractal globule model, can be tested experimentally. Finally, we discuss whether fractal globule architecture can be relevant for chromatin packing in other organisms such as yeast and bacteria.
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Affiliation(s)
- Leonid A Mirny
- Harvard-MIT Division of Health Sciences and Technology, Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA.
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38
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Naughton C, Sproul D, Hamilton C, Gilbert N. Analysis of active and inactive X chromosome architecture reveals the independent organization of 30 nm and large-scale chromatin structures. Mol Cell 2010; 40:397-409. [PMID: 21070966 PMCID: PMC3038259 DOI: 10.1016/j.molcel.2010.10.013] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2010] [Revised: 05/24/2010] [Accepted: 08/26/2010] [Indexed: 11/28/2022]
Abstract
Using a genetic model, we present a high-resolution chromatin fiber analysis of transcriptionally active (Xa) and inactive (Xi) X chromosomes packaged into euchromatin and facultative heterochromatin. Our results show that gene promoters have an open chromatin structure that is enhanced upon transcriptional activation but the Xa and the Xi have similar overall 30 nm chromatin fiber structures. Therefore, the formation of facultative heterochromatin is dependent on factors that act at a level above the 30 nm fiber and transcription does not alter bulk chromatin fiber structures. However, large-scale chromatin structures on Xa are decondensed compared with the Xi and transcription inhibition is sufficient to promote large-scale chromatin compaction. We show a link between transcription and large-scale chromatin packaging independent of the bulk 30 nm chromatin fiber and propose that transcription, not the global compaction of 30 nm chromatin fibers, determines the cytological appearance of large-scale chromatin structures.
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Affiliation(s)
- Catherine Naughton
- Institute of Genetics and Molecular Medicine, The University of Edinburgh, Edinburgh EH4 2XR, UK
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39
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Chromosome dynamics, molecular crowding, and diffusion in the interphase cell nucleus: a Monte Carlo lattice simulation study. Chromosome Res 2010; 19:63-81. [DOI: 10.1007/s10577-010-9168-1] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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40
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Tabaka M, Hołyst R. Binary and graded evolution in time in a simple model of gene induction. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2010; 82:052902. [PMID: 21230531 DOI: 10.1103/physreve.82.052902] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2010] [Indexed: 05/30/2023]
Abstract
We solve analytically the model of gene expression induction which consists of three steps: gene activation, gene products synthesis, and product degradation. The solution is given as a time-dependent probability distribution for gene products. Following the distribution in time from the inactive state of the gene to the stationary state we observe binary or graded response depending solely on the ratio r of the gene activation rate to the rate of the gene product degradation. If r << 1 the response is binary and the continuous transition from binary to graded response occurs between r=0.1 and r=1. Therefore, if binary response is observed during relaxation to steady state, then the activation rate constant must be smaller than the degradation rate constant.
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Affiliation(s)
- Marcin Tabaka
- Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland
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41
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Tessadori F. [Heterochromatin, a plastic component in the nucleus of Arabidopsis thaliana cells]. Biol Aujourdhui 2010; 204:189-97. [PMID: 20950562 DOI: 10.1051/jbio/2010017] [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: 03/29/2010] [Indexed: 11/15/2022]
Abstract
The cytogenetic observation of the nucleus of Arabidopsis thaliana, a plant member of the brassicaceae family, reveals a simple organization of the nuclear content. Indeed, the nuclear volume is occupied by two distinct and easily distinguishable forms of chromatin: a large fraction of relatively decondensed and transcriptionnally active euchromatin surrounds about ten conspicuous regions, the chromocenters, which contain most repeated and highly condensed heterochromatic sequences. Remarkably, during the development of A. thaliana or when the plant is exposed to certain environmental variations, dramatic changes in the appearance, the size or the presence of the chromocenters occur. A number of cytogenetic studies have not only characterized the genomic sequences accommodated in the chromocenters, but have also established the dynamics of their assembly and disruption. Moreover, various endogenous and exogenous factors involved in the presence and the size of chromocenters were recently identified. Taken together, these studies carried out in A. thaliana suggest that heterochromatin is a truly "malleable" fraction of the genome whose dynamic organization is not controlled only by epigenetic marks and whose importance in nuclear function goes beyond merely grouping together non-coding genomic sequences.
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42
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Genome-wide expression profiling and functional network analysis upon neuroectodermal conversion of human mesenchymal stem cells suggest HIF-1 and miR-124a as important regulators. Exp Cell Res 2010; 316:2760-78. [DOI: 10.1016/j.yexcr.2010.06.012] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2009] [Revised: 06/10/2010] [Accepted: 06/16/2010] [Indexed: 11/17/2022]
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43
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Fakhouri THI, Stevenson J, Chisholm AD, Mango SE. Dynamic chromatin organization during foregut development mediated by the organ selector gene PHA-4/FoxA. PLoS Genet 2010; 6. [PMID: 20714352 PMCID: PMC2920861 DOI: 10.1371/journal.pgen.1001060] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2010] [Accepted: 07/12/2010] [Indexed: 01/08/2023] Open
Abstract
Central regulators of cell fate, or selector genes, establish the identity of cells by direct regulation of large cohorts of genes. In Caenorhabditis elegans, foregut (or pharynx) identity relies on the FoxA transcription factor PHA-4, which activates different sets of target genes at various times and in diverse cellular environments. An outstanding question is how PHA-4 distinguishes between target genes for appropriate transcriptional control. We have used the Nuclear Spot Assay and GFP reporters to examine PHA-4 interactions with target promoters in living embryos and with single cell resolution. While PHA-4 was found throughout the digestive tract, binding and activation of pharyngeally expressed promoters was restricted to a subset of pharyngeal cells and excluded from the intestine. An RNAi screen of candidate nuclear factors identified emerin (emr-1) as a negative regulator of PHA-4 binding within the pharynx, but emr-1 did not modulate PHA-4 binding in the intestine. Upon promoter association, PHA-4 induced large-scale chromatin de-compaction, which, we hypothesize, may facilitate promoter access and productive transcription. Our results reveal two tiers of PHA-4 regulation. PHA-4 binding is prohibited in intestinal cells, preventing target gene expression in that organ. PHA-4 binding within the pharynx is limited by the nuclear lamina component EMR-1/emerin. The data suggest that association of PHA-4 with its targets is a regulated step that contributes to promoter selectivity during organ formation. We speculate that global re-organization of chromatin architecture upon PHA-4 binding promotes competence of pharyngeal gene transcription and, by extension, foregut development. Central regulators of cell fate establish the identity of cells by direct regulation of large cohorts of genes. In Caenorhabditis elegans, foregut (or pharynx) identity relies on the FoxA transcription factor PHA-4, which activates different target genes in different cellular environments. An outstanding question is how PHA-4 distinguishes between target genes for appropriate transcriptional control. Here we examine PHA-4 interactions with target promoters in living embryos and with single-cell resolution. While PHA-4 was found throughout the digestive tract, binding and activation of pharyngeally expressed promoters was restricted to a subset of pharyngeal cells and excluded from the intestine. An RNAi screen identified emerin (emr-1) as a negative regulator of PHA-4 binding within the pharynx. Upon promoter association, PHA-4 induced large-scale chromatin de-compaction, which, we hypothesize, facilitates promoter access. Our results reveal two tiers of PHA-4 regulation. PHA-4 binding is prohibited in intestinal cells and is limited in the pharynx by the nuclear lamina component EMR-1/emerin. The data suggest that association of PHA-4 with its targets is a regulated step that contributes to promoter selectivity during organ formation. We speculate that global re-organization of chromatin architecture upon PHA-4 binding promotes competence of pharyngeal gene transcription and, by extension, foregut development.
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Affiliation(s)
- Tala H. I. Fakhouri
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts, United States of America
| | - Jeff Stevenson
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts, United States of America
| | - Andrew D. Chisholm
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts, United States of America
| | - Susan E. Mango
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts, United States of America
- * E-mail:
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44
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de Graaf P, Mousson F, Geverts B, Scheer E, Tora L, Houtsmuller AB, Timmers HTM. Chromatin interaction of TATA-binding protein is dynamically regulated in human cells. J Cell Sci 2010; 123:2663-71. [PMID: 20627952 DOI: 10.1242/jcs.064097] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Gene transcription in mammalian cells is a dynamic process involving regulated assembly of transcription complexes on chromatin in which the TATA-binding protein (TBP) plays a central role. Here, we investigate the dynamic behaviour of TBP by a combination of fluorescence recovery after photobleaching (FRAP) and biochemical assays using human cell lines of different origin. The majority of nucleoplasmic TBP and other TFIID subunits associate with chromatin in a highly dynamic manner. TBP dynamics are regulated by the joint action of the SNF2-related BTAF1 protein and the NC2 complex. Strikingly, both BTAF1 and NC2 predominantly affect TBP dissociation rates, leaving the association rate unchanged. Chromatin immunoprecipitation shows that BTAF1 negatively regulates TBP and NC2 binding to active promoters. Our results support a model for a BTAF1-mediated release of TBP-NC2 complexes from chromatin.
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Affiliation(s)
- Petra de Graaf
- Department of Physiological Chemistry and Netherlands Proteomic Center, University Medical Centre Utrecht, Universiteitsweg 100, 3584 CG Utrecht, Netherlands
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45
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Shanbhag NM, Rafalska-Metcalf IU, Balane-Bolivar C, Janicki SM, Greenberg RA. ATM-dependent chromatin changes silence transcription in cis to DNA double-strand breaks. Cell 2010; 141:970-81. [PMID: 20550933 DOI: 10.1016/j.cell.2010.04.038] [Citation(s) in RCA: 550] [Impact Index Per Article: 39.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2009] [Revised: 01/27/2010] [Accepted: 04/06/2010] [Indexed: 12/01/2022]
Abstract
DNA double-strand breaks (DSBs) initiate extensive local and global alterations in chromatin structure, many of which depend on the ATM kinase. Histone H2A ubiquitylation (uH2A) on chromatin surrounding DSBs is one example, thought to be important for recruitment of repair proteins. uH2A is also implicated in transcriptional repression; an intriguing yet untested hypothesis is that this function is conserved in the context of DSBs. Using a novel reporter that allows for visualization of repair protein recruitment and local transcription in single cells, we describe an ATM-dependent transcriptional silencing program in cis to DSBs. ATM prevents RNA polymerase II elongation-dependent chromatin decondensation at regions distal to DSBs. Silencing is partially dependent on E3 ubiquitin ligases RNF8 and RNF168, whereas reversal of silencing relies on the uH2A deubiquitylating enzyme USP16. These findings give insight into the role of posttranslational modifications in mediating crosstalk between diverse processes occurring on chromatin.
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Affiliation(s)
- Niraj M Shanbhag
- Department of Cancer Biology, Abramson Family Cancer Research Institute, University of Pennsylvania School of Medicine, 421 Curie Boulevard, Philadelphia, PA 19104-6160, USA
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46
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Abstract
The primary role of the nucleus as an information storage, retrieval, and replication site requires the physical organization and compaction of meters of DNA. Although it has been clear for many years that nucleosomes constitute the first level of chromatin compaction, this contributes a relatively small fraction of the condensation needed to fit the typical genome into an interphase nucleus or set of metaphase chromosomes, indicating that there are additional "higher order" levels of chromatin condensation. Identifying these levels, their interrelationships, and the principles that govern their occurrence has been a challenging and much discussed problem. In this article, we focus on recent experimental advances and the emerging evidence indicating that structural plasticity and chromatin dynamics play dominant roles in genome organization. We also discuss novel approaches likely to yield important insights in the near future, and suggest research areas that merit further study.
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Ben-Ari Y, Brody Y, Kinor N, Mor A, Tsukamoto T, Spector DL, Singer RH, Shav-Tal Y. The life of an mRNA in space and time. J Cell Sci 2010; 123:1761-74. [PMID: 20427315 DOI: 10.1242/jcs.062638] [Citation(s) in RCA: 102] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Nuclear transcribed genes produce mRNA transcripts destined to travel from the site of transcription to the cytoplasm for protein translation. Certain transcripts can be further localized to specific cytoplasmic regions. We examined the life cycle of a transcribed beta-actin mRNA throughout gene expression and localization, in a cell system that allows the in vivo detection of the gene locus, the transcribed mRNAs and the cytoplasmic beta-actin protein that integrates into the actin cytoskeleton. Quantification showed that RNA polymerase II elongation progressed at a rate of 3.3 kb/minute and that transactivator binding to the promoter was transient (40 seconds), and demonstrated the unique spatial structure of the coding and non-coding regions of the integrated gene within the transcription site. The rates of gene induction were measured during interphase and after mitosis, demonstrating that daughter cells were not synchronized in respect to transcription initiation of the studied gene. Comparison of the spatial and temporal kinetics of nucleoplasmic and cytoplasmic mRNA transport showed that the beta-actin-localization response initiates from the existing cytoplasmic mRNA pool and not from the newly synthesized transcripts arising after gene induction. It was also demonstrated that mechanisms of random movement were predominant in mediating the efficient translocation of mRNA in the eukaryotic cell.
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Affiliation(s)
- Ya'ara Ben-Ari
- The Mina and Everard Goodman Faculty of Life Sciences and Institute of Nanotechnology, Bar-Ilan University, Ramat Gan 52900, Israel
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Rafalska-Metcalf IU, Powers SL, Joo LM, LeRoy G, Janicki SM. Single cell analysis of transcriptional activation dynamics. PLoS One 2010; 5:e10272. [PMID: 20422051 PMCID: PMC2858074 DOI: 10.1371/journal.pone.0010272] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2010] [Accepted: 03/27/2010] [Indexed: 12/20/2022] Open
Abstract
Background Gene activation is thought to occur through a series of temporally defined regulatory steps. However, this process has not been completely evaluated in single living mammalian cells. Methodology/Principal Findings To investigate the timing and coordination of gene activation events, we tracked the recruitment of GCN5 (histone acetyltransferase), RNA polymerase II, Brd2 and Brd4 (acetyl-lysine binding proteins), in relation to a VP16-transcriptional activator, to a transcription site that can be visualized in single living cells. All accumulated rapidly with the VP16 activator as did the transcribed RNA. RNA was also detected at significantly more transcription sites in cells expressing the VP16-activator compared to a p53-activator. After α-amanitin pre-treatment, the VP16-activator, GCN5, and Brd2 are still recruited to the transcription site but the chromatin does not decondense. Conclusions/Significance This study demonstrates that a strong activator can rapidly overcome the condensed chromatin structure of an inactive transcription site and supercede the expected requirement for regulatory events to proceed in a temporally defined order. Additionally, activator strength determines the number of cells in which transcription is induced as well as the extent of chromatin decondensation. As chromatin decondensation is significantly reduced after α-amanitin pre-treatment, despite the recruitment of transcriptional activation factors, this provides further evidence that transcription drives large-scale chromatin decondensation.
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Affiliation(s)
- Ilona U. Rafalska-Metcalf
- Gene Expression and Regulation Program, The Wistar Institute, Philadelphia, Pennsylvania, United States of America
| | - Sara Lawrence Powers
- Gene Expression and Regulation Program, The Wistar Institute, Philadelphia, Pennsylvania, United States of America
| | - Lucy M. Joo
- Gene Expression and Regulation Program, The Wistar Institute, Philadelphia, Pennsylvania, United States of America
| | - Gary LeRoy
- Department of Molecular Biology, Princeton University, Princeton, New Jersey, United States of America
| | - Susan M. Janicki
- Gene Expression and Regulation Program, The Wistar Institute, Philadelphia, Pennsylvania, United States of America
- * E-mail:
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Meister P, Towbin BD, Pike BL, Ponti A, Gasser SM. The spatial dynamics of tissue-specific promoters during C. elegans development. Genes Dev 2010; 24:766-82. [PMID: 20395364 PMCID: PMC2854392 DOI: 10.1101/gad.559610] [Citation(s) in RCA: 159] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2009] [Accepted: 02/25/2010] [Indexed: 12/23/2022]
Abstract
To understand whether the spatial organization of the genome reflects the cell's differentiated state, we examined whether genes assume specific subnuclear positions during Caenorhabditis elegans development. Monitoring the radial position of developmentally controlled promoters in embryos and larval tissues, we found that small integrated arrays bearing three different tissue-specific promoters have no preferential position in nuclei of undifferentiated embryos. However, in differentiated cells, they shifted stably toward the nuclear lumen when activated, or to the nuclear envelope when silent. In contrast, large integrated arrays bearing the same promoters became heterochromatic and nuclear envelope-bound in embryos. Tissue-specific activation of promoters in these large arrays in larvae overrode the perinuclear anchorage. For transgenes that carry both active and inactive promoters, the inward shift of the active promoter was dominant. Finally, induction of master regulator HLH-1 prematurely induced internalization of a muscle-specific promoter array in embryos. Fluorescence in situ hybridization confirmed analogous results for the endogenous endoderm-determining gene pha-4. We propose that, in differentiated cells, subnuclear organization arises from the selective positioning of active and inactive developmentally regulated promoters. We characterize two forces that lead to tissue-specific subnuclear organization of the worm genome: large repeat-induced heterochromatin, which associates with the nuclear envelope like repressed genes in differentiated cells, and tissue-specific promoters that shift inward in a dominant fashion over silent promoters, when they are activated.
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Affiliation(s)
- Peter Meister
- Friedrich Miescher Institute for Biomedical Research, CH-4058 Basel, Switzerland
| | - Benjamin D. Towbin
- Friedrich Miescher Institute for Biomedical Research, CH-4058 Basel, Switzerland
| | - Brietta L. Pike
- Friedrich Miescher Institute for Biomedical Research, CH-4058 Basel, Switzerland
| | - Aaron Ponti
- Friedrich Miescher Institute for Biomedical Research, CH-4058 Basel, Switzerland
| | - Susan M. Gasser
- Friedrich Miescher Institute for Biomedical Research, CH-4058 Basel, Switzerland
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Vitali P, Royo H, Marty V, Bortolin-Cavaillé ML, Cavaillé J. Long nuclear-retained non-coding RNAs and allele-specific higher-order chromatin organization at imprinted snoRNA gene arrays. J Cell Sci 2010; 123:70-83. [DOI: 10.1242/jcs.054957] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
The imprinted Snurf-Snrpn domain, also referred to as the Prader-Willi syndrome region, contains two ∼100-200 kb arrays of repeated small nucleolar (sno)RNAs processed from introns of long, paternally expressed non-protein-coding RNAs whose biogenesis and functions are poorly understood. We provide evidence that C/D snoRNAs do not derive from a single transcript as previously envisaged, but rather from (at least) two independent transcription units. We show that spliced snoRNA host-gene transcripts accumulate near their transcription sites as structurally constrained RNA species that are prevented from diffusing, as well as multiple stable nucleoplasmic RNA foci dispersed in the entire nucleus but not in the nucleolus. Chromatin structure at these repeated arrays displays an outstanding parent-of-origin-specific higher-order organization: the transcriptionally active allele is revealed as extended DNA FISH signals whereas the genetically identical, silent allele is visualized as singlet DNA FISH signals. A similar allele-specific chromatin organization is documented for snoRNA gene arrays at the imprinted Dlk1-Dio3 domain. Our findings have repercussions for understanding the spatial organization of gene expression and the intra-nuclear fate of non-coding RNAs in the context of nuclear architecture.
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Affiliation(s)
- Patrice Vitali
- Université de Toulouse, UPS; Laboratoire de Biologie Moléculaire Eucaryote, F-31000 Toulouse, France
- CNRS; LBME, F-31000 Toulouse, France
| | - Hélène Royo
- Université de Toulouse, UPS; Laboratoire de Biologie Moléculaire Eucaryote, F-31000 Toulouse, France
- CNRS; LBME, F-31000 Toulouse, France
| | - Virginie Marty
- Université de Toulouse, UPS; Laboratoire de Biologie Moléculaire Eucaryote, F-31000 Toulouse, France
- CNRS; LBME, F-31000 Toulouse, France
| | - Marie-Line Bortolin-Cavaillé
- Université de Toulouse, UPS; Laboratoire de Biologie Moléculaire Eucaryote, F-31000 Toulouse, France
- CNRS; LBME, F-31000 Toulouse, France
| | - Jérôme Cavaillé
- Université de Toulouse, UPS; Laboratoire de Biologie Moléculaire Eucaryote, F-31000 Toulouse, France
- CNRS; LBME, F-31000 Toulouse, France
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