1
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Li L, Wu Y, Dai K, Wang Q, Ye S, Shi Q, Chen Z, Huang YC, Zhao W, Li L. The CHCHD2/Sirt1 corepressors involve in G9a-mediated regulation of RNase H1 expression to control R-loop. CELL INSIGHT 2023; 2:100112. [PMID: 37388553 PMCID: PMC10300302 DOI: 10.1016/j.cellin.2023.100112] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/19/2023] [Revised: 05/25/2023] [Accepted: 05/28/2023] [Indexed: 07/01/2023]
Abstract
R-loops are regulators of many cellular processes and are threats to genome integrity. Therefore, understanding the mechanisms underlying the regulation of R-loops is important. Inspired by the findings on RNase H1-mediated R-loop degradation or accumulation, we focused our interest on the regulation of RNase H1 expression. In the present study, we report that G9a positively regulates RNase H1 expression to boost R-loop degradation. CHCHD2 acts as a repressive transcription factor that inhibits the expression of RNase H1 to promote R-loop accumulation. Sirt1 interacts with CHCHD2 and deacetylates it, which functions as a corepressor that suppresses the expression of downstream target gene RNase H1. We also found that G9a methylated the promoter of RNase H1, inhibiting the binding of CHCHD2 and Sirt1. In contrast, when G9a was knocked down, recruitment of CHCHD2 and Sirt1 to the RNase H1 promoter increased, which co-inhibited RNase H1 transcription. Furthermore, knockdown of Sirt1 led to binding of G9a to the RNase H1 promoter. In summary, we demonstrated that G9a regulates RNase H1 expression to maintain the steady-state balance of R-loops by suppressing the recruitment of CHCHD2/Sirt1 corepressors to the target gene promoter.
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2
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Ballmer D, Tardat M, Ortiz R, Graff-Meyer A, Ozonov E, Genoud C, Peters A, Fanourgakis G. HP1 proteins regulate nucleolar structure and function by secluding pericentromeric constitutive heterochromatin. Nucleic Acids Res 2022; 51:117-143. [PMID: 36533441 PMCID: PMC9841413 DOI: 10.1093/nar/gkac1159] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Revised: 10/29/2022] [Accepted: 12/13/2022] [Indexed: 12/23/2022] Open
Abstract
Nucleoli are nuclear compartments regulating ribosome biogenesis and cell growth. In embryonic stem cells (ESCs), nucleoli containing transcriptionally active ribosomal genes are spatially separated from pericentromeric satellite repeat sequences packaged in largely repressed constitutive heterochromatin (PCH). To date, mechanisms underlying such nuclear partitioning and the physiological relevance thereof are unknown. Here we show that repressive chromatin at PCH ensures structural integrity and function of nucleoli during cell cycle progression. Loss of heterochromatin proteins HP1α and HP1β causes deformation of PCH, with reduced H3K9 trimethylation (H3K9me3) and HP1γ levels, absence of H4K20me3 and upregulated major satellites expression. Spatially, derepressed PCH aberrantly associates with nucleoli accumulating severe morphological defects during S/G2 cell cycle progression. Hp1α/β deficiency reduces cell proliferation, ribosomal RNA biosynthesis and mobility of Nucleophosmin, a major nucleolar component. Nucleolar integrity and function require HP1α/β proteins to be recruited to H3K9me3-marked PCH and their ability to dimerize. Correspondingly, ESCs deficient for both Suv39h1/2 H3K9 HMTs display similar nucleolar defects. In contrast, Suv4-20h1/2 mutant ESCs lacking H4K20me3 at PCH do not. Suv39h1/2 and Hp1α/β deficiency-induced nucleolar defects are reminiscent of those defining human ribosomopathy disorders. Our results reveal a novel role for SUV39H/HP1-marked repressive constitutive heterochromatin in regulating integrity, function and physiology of nucleoli.
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Affiliation(s)
- Daniel Ballmer
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, 4058 Basel, Switzerland,Faculty of Sciences, University of Basel, 4056 Basel, Switzerland
| | - Mathieu Tardat
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, 4058 Basel, Switzerland
| | - Raphael Ortiz
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, 4058 Basel, Switzerland
| | - Alexandra Graff-Meyer
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, 4058 Basel, Switzerland
| | - Evgeniy A Ozonov
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, 4058 Basel, Switzerland
| | - Christel Genoud
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, 4058 Basel, Switzerland
| | | | - Grigorios Fanourgakis
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, 4058 Basel, Switzerland
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3
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Paccosi E, Balajee AS, Proietti-De-Santis L. A matter of delicate balance: Loss and gain of Cockayne syndrome proteins in premature aging and cancer. FRONTIERS IN AGING 2022; 3:960662. [PMID: 35935726 PMCID: PMC9351357 DOI: 10.3389/fragi.2022.960662] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/03/2022] [Accepted: 07/04/2022] [Indexed: 12/26/2022]
Abstract
DNA repair genes are critical for preserving genomic stability and it is well established that mutations in DNA repair genes give rise to progeroid diseases due to perturbations in different DNA metabolic activities. Cockayne Syndrome (CS) is an autosomal recessive inheritance caused by inactivating mutations in CSA and CSB genes. This review will primarily focus on the two Cockayne Syndrome proteins, CSA and CSB, primarily known to be involved in Transcription Coupled Repair (TCR). Curiously, dysregulated expression of CS proteins has been shown to exhibit differential health outcomes: lack of CS proteins due to gene mutations invariably leads to complex premature aging phenotypes, while excess of CS proteins is associated with carcinogenesis. Thus it appears that CS genes act as a double-edged sword whose loss or gain of expression leads to premature aging and cancer. Future mechanistic studies on cell and animal models of CS can lead to potential biological targets for interventions in both aging and cancer development processes. Some of these exciting possibilities will be discussed in this review in light of the current literature.
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Affiliation(s)
- Elena Paccosi
- Unit of Molecular Genetics of Aging, Department of Ecology and Biology, University of Tuscia, Viterbo, Italy
- *Correspondence: Elena Paccosi, ; Adayabalam S. Balajee, ; Luca Proietti-De-Santis,
| | - Adayabalam S. Balajee
- Cytogenetic Biodosimetry Laboratory, Radiation Emergency Assistance Center/Training Site, Oak Ridge Institute of Science and Education, Oak Ridge Associated Universities, Oak Ridge, TN, United States
- *Correspondence: Elena Paccosi, ; Adayabalam S. Balajee, ; Luca Proietti-De-Santis,
| | - Luca Proietti-De-Santis
- Unit of Molecular Genetics of Aging, Department of Ecology and Biology, University of Tuscia, Viterbo, Italy
- *Correspondence: Elena Paccosi, ; Adayabalam S. Balajee, ; Luca Proietti-De-Santis,
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4
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Epigenetic regulation of human non-coding RNA gene transcription. Biochem Soc Trans 2022; 50:723-736. [PMID: 35285478 DOI: 10.1042/bst20210860] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Revised: 02/18/2022] [Accepted: 02/21/2022] [Indexed: 12/12/2022]
Abstract
Recent investigations on the non-protein-coding transcriptome of human cells have revealed previously hidden layers of gene regulation relying on regulatory non-protein-coding (nc) RNAs, including the widespread ncRNA-dependent regulation of epigenetic chromatin states and of mRNA translation and stability. However, despite its centrality, the epigenetic regulation of ncRNA genes has received relatively little attention. In this mini-review, we attempt to provide a synthetic account of recent literature suggesting an unexpected complexity in chromatin-dependent regulation of ncRNA gene transcription by the three human nuclear RNA polymerases. Emerging common features, like the heterogeneity of chromatin states within ncRNA multigene families and their influence on 3D genome organization, point to unexplored issues whose investigation could lead to a better understanding of the whole human epigenomic network.
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5
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Xie SQ, Leeke BJ, Whilding C, Wagner RT, Garcia-Llagostera F, Low Y, Chammas P, Cheung NTF, Dormann D, McManus MT, Percharde M. Nucleolar-based Dux repression is essential for embryonic two-cell stage exit. Genes Dev 2022; 36:331-347. [PMID: 35273077 PMCID: PMC8973846 DOI: 10.1101/gad.349172.121] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Accepted: 02/17/2022] [Indexed: 12/14/2022]
Abstract
Upon fertilization, the mammalian embryo must switch from dependence on maternal transcripts to transcribing its own genome, and in mice this involves the transient up-regulation of MERVL transposons and MERVL-driven genes at the two-cell stage. The mechanisms and requirement for MERVL and two-cell (2C) gene up-regulation are poorly understood. Moreover, this MERVL-driven transcriptional program must be rapidly shut off to allow two-cell exit and developmental progression. Here, we report that robust ribosomal RNA (rRNA) synthesis and nucleolar maturation are essential for exit from the 2C state. 2C-like cells and two-cell embryos show similar immature nucleoli with altered structure and reduced rRNA output. We reveal that nucleolar disruption via blocking RNA polymerase I activity or preventing nucleolar phase separation enhances conversion to a 2C-like state in embryonic stem cells (ESCs) by detachment of the MERVL activator Dux from the nucleolar surface. In embryos, nucleolar disruption prevents proper nucleolar maturation and Dux silencing and leads to two- to four-cell arrest. Our findings reveal an intriguing link between rRNA synthesis, nucleolar maturation, and gene repression during early development.
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Affiliation(s)
- Sheila Q Xie
- MRC London Institute of Medical Sciences, London W12 0NN, United Kingdom.,Institute of Clinical Sciences, Imperial College London, London W12 0NN, United Kingdom
| | - Bryony J Leeke
- MRC London Institute of Medical Sciences, London W12 0NN, United Kingdom.,Institute of Clinical Sciences, Imperial College London, London W12 0NN, United Kingdom
| | - Chad Whilding
- MRC London Institute of Medical Sciences, London W12 0NN, United Kingdom.,Institute of Clinical Sciences, Imperial College London, London W12 0NN, United Kingdom
| | - Ryan T Wagner
- University of California at San Francisco, San Francisco, California 91413, USA
| | - Ferran Garcia-Llagostera
- MRC London Institute of Medical Sciences, London W12 0NN, United Kingdom.,Institute of Clinical Sciences, Imperial College London, London W12 0NN, United Kingdom
| | - YiXuan Low
- MRC London Institute of Medical Sciences, London W12 0NN, United Kingdom.,Institute of Clinical Sciences, Imperial College London, London W12 0NN, United Kingdom
| | - Paul Chammas
- MRC London Institute of Medical Sciences, London W12 0NN, United Kingdom.,Institute of Clinical Sciences, Imperial College London, London W12 0NN, United Kingdom
| | - Nathan T-F Cheung
- MRC London Institute of Medical Sciences, London W12 0NN, United Kingdom.,Institute of Clinical Sciences, Imperial College London, London W12 0NN, United Kingdom
| | - Dirk Dormann
- MRC London Institute of Medical Sciences, London W12 0NN, United Kingdom.,Institute of Clinical Sciences, Imperial College London, London W12 0NN, United Kingdom
| | - Michael T McManus
- University of California at San Francisco, San Francisco, California 91413, USA
| | - Michelle Percharde
- MRC London Institute of Medical Sciences, London W12 0NN, United Kingdom.,Institute of Clinical Sciences, Imperial College London, London W12 0NN, United Kingdom
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6
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Lanzafame M, Branca G, Landi C, Qiang M, Vaz B, Nardo T, Ferri D, Mura M, Iben S, Stefanini M, Peverali FA, Bini L, Orioli D. Cockayne syndrome group A and ferrochelatase finely tune ribosomal gene transcription and its response to UV irradiation. Nucleic Acids Res 2021; 49:10911-10930. [PMID: 34581821 PMCID: PMC8565352 DOI: 10.1093/nar/gkab819] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Revised: 08/10/2021] [Accepted: 09/12/2021] [Indexed: 11/14/2022] Open
Abstract
CSA and CSB proteins are key players in transcription-coupled nucleotide excision repair (TC-NER) pathway that removes UV-induced DNA lesions from the transcribed strands of expressed genes. Additionally, CS proteins play relevant but still elusive roles in other cellular pathways whose alteration may explain neurodegeneration and progeroid features in Cockayne syndrome (CS). Here we identify a CS-containing chromatin-associated protein complex that modulates rRNA transcription. Besides RNA polymerase I (RNAP1) and specific ribosomal proteins (RPs), the complex includes ferrochelatase (FECH), a well-known mitochondrial enzyme whose deficiency causes erythropoietic protoporphyria (EPP). Impairment of either CSA or FECH functionality leads to reduced RNAP1 occupancy on rDNA promoter that is associated to reduced 47S pre-rRNA transcription. In addition, reduced FECH expression leads to an abnormal accumulation of 18S rRNA that in primary dermal fibroblasts from CS and EPP patients results in opposed rRNA amounts. After cell irradiation with UV light, CSA triggers the dissociation of the CSA–FECH–CSB–RNAP1–RPs complex from the chromatin while it stabilizes its binding to FECH. Besides disclosing a function for FECH within nucleoli, this study sheds light on the still unknown mechanisms through which CSA modulates rRNA transcription.
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Affiliation(s)
- Manuela Lanzafame
- Institute of Molecular Genetics -L.L. Cavalli Sforza, CNR, 27100 Pavia, Italy
| | - Giulia Branca
- Institute of Molecular Genetics -L.L. Cavalli Sforza, CNR, 27100 Pavia, Italy
| | - Claudia Landi
- Department of Life Sciences, University of Siena, 53100 Siena, Italy
| | - Mingyue Qiang
- Department of Dermatology and Allergic Diseases, Ulm University, Albert-Einstein Allee 23, 89081 Ulm, Germany
| | - Bruno Vaz
- Institute of Molecular Genetics -L.L. Cavalli Sforza, CNR, 27100 Pavia, Italy
| | - Tiziana Nardo
- Institute of Molecular Genetics -L.L. Cavalli Sforza, CNR, 27100 Pavia, Italy
| | - Debora Ferri
- Institute of Molecular Genetics -L.L. Cavalli Sforza, CNR, 27100 Pavia, Italy
| | - Manuela Mura
- Institute of Molecular Genetics -L.L. Cavalli Sforza, CNR, 27100 Pavia, Italy
| | - Sebastian Iben
- Department of Dermatology and Allergic Diseases, Ulm University, Albert-Einstein Allee 23, 89081 Ulm, Germany
| | - Miria Stefanini
- Institute of Molecular Genetics -L.L. Cavalli Sforza, CNR, 27100 Pavia, Italy
| | - Fiorenzo A Peverali
- Institute of Molecular Genetics -L.L. Cavalli Sforza, CNR, 27100 Pavia, Italy
| | - Luca Bini
- Department of Life Sciences, University of Siena, 53100 Siena, Italy
| | - Donata Orioli
- Institute of Molecular Genetics -L.L. Cavalli Sforza, CNR, 27100 Pavia, Italy
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7
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Jiang X, Zhu X, Cheng Y, Azhar M, Xing X, Li W, Cao Y, Shi Q, Bao J. The Spin1 interactor, Spindoc, is dispensable for meiotic division, but essential for haploid spermatid development in mice. Reprod Biol Endocrinol 2021; 19:144. [PMID: 34526015 PMCID: PMC8442334 DOI: 10.1186/s12958-021-00828-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Accepted: 09/03/2021] [Indexed: 11/21/2022] Open
Abstract
In mammals, germline development undergoes dramatic morphological and molecular changes and is epigenetically subject to intricate yet exquisite regulation. Which epigenetic players and how they participate in the germline developmental process are not fully characterized. Spin1 is a multifunctional epigenetic protein reader that has been shown to recognize H3 "K4me3-R8me2a" histone marks, and more recently the non-canonical bivalent H3 "K4me3-K9me3/2" marks as well. As a robust Spin1-interacting cofactor, Spindoc has been identified to enhance the binding of Spin1 to its substrate histone marks, thereby modulating the downstream signaling; However, the physiological role of Spindoc in germline development is unknown. We generated two Spindoc knockout mouse models through CRISPR/Cas9 strategy, which revealed that Spindoc is specifically required for haploid spermatid development, but not essential for meiotic divisions in spermatocytes. This study unveiled a new epigenetic player that participates in haploid germline development.
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Affiliation(s)
- Xue Jiang
- Division of Life Sciences and Medicine, The First Affiliated Hospital of USTC, University of Science and Technology of China (USTC), Hefei, Anhui, 230001, People's Republic of China
| | - Xiaoli Zhu
- Division of Life Sciences and Medicine, The First Affiliated Hospital of USTC, University of Science and Technology of China (USTC), Hefei, Anhui, 230001, People's Republic of China
| | - Yu Cheng
- Division of Life Sciences and Medicine, The First Affiliated Hospital of USTC, University of Science and Technology of China (USTC), Hefei, Anhui, 230001, People's Republic of China
| | - Muhammad Azhar
- Division of Life Sciences and Medicine, The First Affiliated Hospital of USTC, University of Science and Technology of China (USTC), Hefei, Anhui, 230001, People's Republic of China
| | - Xuemei Xing
- Division of Life Sciences and Medicine, The First Affiliated Hospital of USTC, University of Science and Technology of China (USTC), Hefei, Anhui, 230001, People's Republic of China
| | - Wenqing Li
- Division of Life Sciences and Medicine, The First Affiliated Hospital of USTC, University of Science and Technology of China (USTC), Hefei, Anhui, 230001, People's Republic of China
| | - Yuzhu Cao
- Division of Life Sciences and Medicine, The First Affiliated Hospital of USTC, University of Science and Technology of China (USTC), Hefei, Anhui, 230001, People's Republic of China.
| | - Qinghua Shi
- Division of Life Sciences and Medicine, The First Affiliated Hospital of USTC, University of Science and Technology of China (USTC), Hefei, Anhui, 230001, People's Republic of China.
| | - Jianqiang Bao
- Division of Life Sciences and Medicine, The First Affiliated Hospital of USTC, University of Science and Technology of China (USTC), Hefei, Anhui, 230001, People's Republic of China.
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8
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Datta A, Pollock KJ, Kormuth KA, Brosh RM. G-Quadruplex Assembly by Ribosomal DNA: Emerging Roles in Disease Pathogenesis and Cancer Biology. Cytogenet Genome Res 2021; 161:285-296. [PMID: 34469893 DOI: 10.1159/000516394] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Accepted: 01/03/2021] [Indexed: 12/15/2022] Open
Abstract
Unique repetitive elements of the eukaryotic genome can be problematic for cellular DNA replication and transcription and pose a source of genomic instability. Human ribosomal DNA (rDNA) exists as repeating units clustered together on several chromosomes. Understanding the molecular mechanisms whereby rDNA interferes with normal genome homeostasis is the subject of this review. We discuss the instability of rDNA as a driver of senescence and the important roles of helicases to suppress its deleterious effects. The propensity of rDNA that is rich in guanine bases to form G-quadruplexes (G4) is discussed and evaluated in disease pathogenesis. Targeting G4 in the ribosomes and other chromosomal loci may represent a useful synthetic lethal approach to combating cancer.
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Affiliation(s)
- Arindam Datta
- Translational Gerontology Branch, National Institute on Aging, NIH, Baltimore, Maryland, USA
| | - Kevin J Pollock
- Department of Biology, Bethany College, Bethany, West Virginia, USA
| | - Karen A Kormuth
- Department of Biology, Bethany College, Bethany, West Virginia, USA
| | - Robert M Brosh
- Translational Gerontology Branch, National Institute on Aging, NIH, Baltimore, Maryland, USA
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9
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Antagonising Chromatin Remodelling Activities in the Regulation of Mammalian Ribosomal Transcription. Genes (Basel) 2021; 12:genes12070961. [PMID: 34202617 PMCID: PMC8303148 DOI: 10.3390/genes12070961] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Revised: 06/16/2021] [Accepted: 06/19/2021] [Indexed: 12/29/2022] Open
Abstract
Ribosomal transcription constitutes the major energy consuming process in cells and is regulated in response to proliferation, differentiation and metabolic conditions by several signalling pathways. These act on the transcription machinery but also on chromatin factors and ncRNA. The many ribosomal gene repeats are organised in a number of different chromatin states; active, poised, pseudosilent and repressed gene repeats. Some of these chromatin states are unique to the 47rRNA gene repeat and do not occur at other locations in the genome, such as the active state organised with the HMG protein UBF whereas other chromatin state are nucleosomal, harbouring both active and inactive histone marks. The number of repeats in a certain state varies on developmental stage and cell type; embryonic cells have more rRNA gene repeats organised in an open chromatin state, which is replaced by heterochromatin during differentiation, establishing different states depending on cell type. The 47S rRNA gene transcription is regulated in different ways depending on stimulus and chromatin state of individual gene repeats. This review will discuss the present knowledge about factors involved, such as chromatin remodelling factors NuRD, NoRC, CSB, B-WICH, histone modifying enzymes and histone chaperones, in altering gene expression and switching chromatin states in proliferation, differentiation, metabolic changes and stress responses.
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10
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Clapier CR. Sophisticated Conversations between Chromatin and Chromatin Remodelers, and Dissonances in Cancer. Int J Mol Sci 2021; 22:5578. [PMID: 34070411 PMCID: PMC8197500 DOI: 10.3390/ijms22115578] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Revised: 05/18/2021] [Accepted: 05/18/2021] [Indexed: 01/13/2023] Open
Abstract
The establishment and maintenance of genome packaging into chromatin contribute to define specific cellular identity and function. Dynamic regulation of chromatin organization and nucleosome positioning are critical to all DNA transactions-in particular, the regulation of gene expression-and involve the cooperative action of sequence-specific DNA-binding factors, histone modifying enzymes, and remodelers. Remodelers are molecular machines that generate various chromatin landscapes, adjust nucleosome positioning, and alter DNA accessibility by using ATP binding and hydrolysis to perform DNA translocation, which is highly regulated through sophisticated structural and functional conversations with nucleosomes. In this review, I first present the functional and structural diversity of remodelers, while emphasizing the basic mechanism of DNA translocation, the common regulatory aspects, and the hand-in-hand progressive increase in complexity of the regulatory conversations between remodelers and nucleosomes that accompanies the increase in challenges of remodeling processes. Next, I examine how, through nucleosome positioning, remodelers guide the regulation of gene expression. Finally, I explore various aspects of how alterations/mutations in remodelers introduce dissonance into the conversations between remodelers and nucleosomes, modify chromatin organization, and contribute to oncogenesis.
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Affiliation(s)
- Cedric R Clapier
- Department of Oncological Sciences & Howard Hughes Medical Institute, Huntsman Cancer Institute, University of Utah School of Medicine, 2000 Circle of Hope, Salt Lake City, UT 84112, USA
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11
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The Ribosomal Gene Loci-The Power behind the Throne. Genes (Basel) 2021; 12:genes12050763. [PMID: 34069807 PMCID: PMC8157237 DOI: 10.3390/genes12050763] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Revised: 05/12/2021] [Accepted: 05/14/2021] [Indexed: 12/20/2022] Open
Abstract
Nucleoli form around actively transcribed ribosomal RNA (rRNA) genes (rDNA), and the morphology and location of nucleolus-associated genomic domains (NADs) are linked to the RNA Polymerase I (Pol I) transcription status. The number of rDNA repeats (and the proportion of actively transcribed rRNA genes) is variable between cell types, individuals and disease state. Substantial changes in nucleolar morphology and size accompanied by concomitant changes in the Pol I transcription rate have long been documented during normal cell cycle progression, development and malignant transformation. This demonstrates how dynamic the nucleolar structure can be. Here, we will discuss how the structure of the rDNA loci, the nucleolus and the rate of Pol I transcription are important for dynamic regulation of global gene expression and genome stability, e.g., through the modulation of long-range genomic interactions with the suppressive NAD environment. These observations support an emerging paradigm whereby the rDNA repeats and the nucleolus play a key regulatory role in cellular homeostasis during normal development as well as disease, independent of their role in determining ribosome capacity and cellular growth rates.
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12
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Tiwari V, Baptiste BA, Okur MN, Bohr VA. Current and emerging roles of Cockayne syndrome group B (CSB) protein. Nucleic Acids Res 2021; 49:2418-2434. [PMID: 33590097 DOI: 10.1093/nar/gkab085] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Revised: 01/26/2021] [Accepted: 02/01/2021] [Indexed: 12/11/2022] Open
Abstract
Cockayne syndrome (CS) is a segmental premature aging syndrome caused primarily by defects in the CSA or CSB genes. In addition to premature aging, CS patients typically exhibit microcephaly, progressive mental and sensorial retardation and cutaneous photosensitivity. Defects in the CSB gene were initially thought to primarily impair transcription-coupled nucleotide excision repair (TC-NER), predicting a relatively consistent phenotype among CS patients. In contrast, the phenotypes of CS patients are pleiotropic and variable. The latter is consistent with recent work that implicates CSB in multiple cellular systems and pathways, including DNA base excision repair, interstrand cross-link repair, transcription, chromatin remodeling, RNAPII processing, nucleolin regulation, rDNA transcription, redox homeostasis, and mitochondrial function. The discovery of additional functions for CSB could potentially explain the many clinical phenotypes of CSB patients. This review focuses on the diverse roles played by CSB in cellular pathways that enhance genome stability, providing insight into the molecular features of this complex premature aging disease.
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Affiliation(s)
- Vinod Tiwari
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
| | - Beverly A Baptiste
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
| | - Mustafa N Okur
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
| | - Vilhelm A Bohr
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
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13
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Poot M, Hochstenbach R. Prevalence and Phenotypic Impact of Robertsonian Translocations. Mol Syndromol 2021; 12:1-11. [PMID: 33776621 PMCID: PMC7983559 DOI: 10.1159/000512676] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2020] [Accepted: 10/26/2020] [Indexed: 12/11/2022] Open
Abstract
Robertsonian translocations (RTs) result from fusion of 2 acrocentric chromosomes (e.g., 13, 14, 15, 21, 22) and consequential losses of segments of the p arms containing 47S rDNA clusters and transcription factor binding sites. Depending on the position of the breakpoints, the size of these losses vary considerably between types of RTs. The prevalence of RTs in the general population is estimated to be around 1 per 800 individuals, making RTs the most common chromosomal rearrangement in healthy individuals. Based on their prevalence, RTs are classified as "common," rob(13;14) and rob(14;21), or "rare" (the 8 remaining nonhomologous combinations). Carriers of RTs are at an increased risk for offspring with chromosomal imbalances or with uniparental disomy. RTs are generally regarded as phenotypically neutral, although, due to RTs formation, 2 of the 10 ribosomal rDNA gene clusters, several long noncoding RNAs, and in the case of RTs involving chromosome 21, several mRNA encoding genes are lost. Nevertheless, recent evidence indicates that RTs may have a significant phenotypic impact. In particular, rob(13;14) carriers have a significantly elevated risk for breast cancer. While RTs are easily spotted by routine karyotyping, they may go unnoticed if only array-CGH and NextGen sequencing methods are applied. This review first discusses possible molecular mechanisms underlying the particularly high rates of RT formation and their incidence in the general population, and second, likely causes for the elevated cancer risk of some RTs will be examined.
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Affiliation(s)
- Martin Poot
- Department of Human Genetics, University of Würzburg, Würzburg, Germany
| | - Ron Hochstenbach
- Department of Clinical Genetics, Amsterdam UMC, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
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14
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Zhao F, Liu Y, Su X, Lee JE, Song Y, Wang D, Ge K, Gao J, Zhang MQ, Li H. Molecular basis for histone H3 "K4me3-K9me3/2" methylation pattern readout by Spindlin1. J Biol Chem 2020; 295:16877-16887. [PMID: 32994220 PMCID: PMC7864079 DOI: 10.1074/jbc.ra120.013649] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Revised: 09/16/2020] [Indexed: 12/11/2022] Open
Abstract
Histone recognition by "reader" modules serves as a fundamental mechanism in epigenetic regulation. Previous studies have shown that Spindlin1 is a reader of histone H3K4me3 as well as "K4me3-R8me2a" and promotes transcription of rDNA or Wnt/TCF4 target genes. Here we show that Spindlin1 also acts as a potent reader of histone H3 "K4me3-K9me3/2" bivalent methylation pattern. Calorimetric titration revealed a binding affinity of 16 nm between Spindlin1 and H3 "K4me3-K9me3" peptide, which is one to three orders of magnitude stronger than most other histone readout events at peptide level. Structural studies revealed concurrent recognition of H3K4me3 and H3K9me3/2 by aromatic pockets 2 and 1 of Spindlin1, respectively. Epigenomic profiling studies showed that Spindlin1 colocalizes with both H3K4me3 and H3K9me3 peaks in a subset of genes enriched in biological processes of transcription and its regulation. Moreover, the distribution of Spindlin1 peaks is primarily associated with H3K4me3 but not H3K9me3, which suggests that Spindlin1 is a downstream effector of H3K4me3 generated in heterochromatic regions. Collectively, our work calls attention to an intriguing function of Spindlin1 as a potent H3 "K4me3-K9me3/2" bivalent mark reader, thereby balancing gene expression and silencing in H3K9me3/2-enriched regions.
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Affiliation(s)
- Fan Zhao
- MOE Key Laboratory of Protein Sciences, Beijing Advanced Innovation Center for Structural Biology, Beijing Frontier Research Center for Biological Structure, Department of Basic Medical Sciences, School of Medicine, Tsinghua University, Beijing, China
| | - Yunan Liu
- MOE Key Laboratory of Bioinformatics, Bioinformatics Division, Center for Synthetic and Systems Biology, BNRist, Tsinghua University, Beijing, China
| | - Xiaonan Su
- MOE Key Laboratory of Protein Sciences, Beijing Advanced Innovation Center for Structural Biology, Beijing Frontier Research Center for Biological Structure, Department of Basic Medical Sciences, School of Medicine, Tsinghua University, Beijing, China
| | - Ji-Eun Lee
- Adipocyte Biology and Gene Regulation Section, Laboratory of Endocrinology and Receptor Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland USA
| | - Yutong Song
- MOE Key Laboratory of Protein Sciences, Beijing Advanced Innovation Center for Structural Biology, Beijing Frontier Research Center for Biological Structure, Department of Basic Medical Sciences, School of Medicine, Tsinghua University, Beijing, China
| | - Daliang Wang
- MOE Key Laboratory of Protein Sciences, Beijing Advanced Innovation Center for Structural Biology, Beijing Frontier Research Center for Biological Structure, Department of Basic Medical Sciences, School of Medicine, Tsinghua University, Beijing, China
| | - Kai Ge
- Adipocyte Biology and Gene Regulation Section, Laboratory of Endocrinology and Receptor Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland USA
| | - Juntao Gao
- MOE Key Laboratory of Bioinformatics, Bioinformatics Division, Center for Synthetic and Systems Biology, BNRist, Tsinghua University, Beijing, China
| | - Michael Q Zhang
- MOE Key Laboratory of Bioinformatics, Bioinformatics Division, Center for Synthetic and Systems Biology, BNRist, Tsinghua University, Beijing, China; Department of Biological Sciences Center for Systems Biology, University of Texas at Dallas, Richardson, Texas, USA
| | - Haitao Li
- MOE Key Laboratory of Protein Sciences, Beijing Advanced Innovation Center for Structural Biology, Beijing Frontier Research Center for Biological Structure, Department of Basic Medical Sciences, School of Medicine, Tsinghua University, Beijing, China; Tsinghua-Peking Center for Life Sciences, Beijing, China.
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15
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The Cockayne syndrome group A and B proteins are part of a ubiquitin-proteasome degradation complex regulating cell division. Proc Natl Acad Sci U S A 2020; 117:30498-30508. [PMID: 33199595 DOI: 10.1073/pnas.2006543117] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Cytokinesis is monitored by a molecular machinery that promotes the degradation of the intercellular bridge, a transient protein structure connecting the two daughter cells. Here, we found that CSA and CSB, primarily defined as DNA repair factors, are located at the midbody, a transient structure in the middle of the intercellular bridge, where they recruit CUL4 and MDM2 ubiquitin ligases and the proteasome. As a part of this molecular machinery, CSA and CSB contribute to the ubiquitination and the degradation of proteins such as PRC1, the Protein Regulator of Cytokinesis, to ensure the correct separation of the two daughter cells. Defects in CSA or CSB result in perturbation of the abscission leading to the formation of long intercellular bridges and multinucleated cells, which might explain part of the Cockayne syndrome phenotypes. Our results enlighten the role played by CSA and CSB as part of a ubiquitin/proteasome degradation process involved in transcription, DNA repair, and cell division.
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16
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Chopra A, Cho WC, Willmore WG, Biggar KK. Hypoxia-Inducible Lysine Methyltransferases: G9a and GLP Hypoxic Regulation, Non-histone Substrate Modification, and Pathological Relevance. Front Genet 2020; 11:579636. [PMID: 33088284 PMCID: PMC7495024 DOI: 10.3389/fgene.2020.579636] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Accepted: 08/13/2020] [Indexed: 12/29/2022] Open
Abstract
Oxygen sensing is inherent among most animal lifeforms and is critical for organism survival. Oxygen sensing mechanisms collectively trigger cellular and physiological responses that enable adaption to a reduction in ideal oxygen levels. The major mechanism by which oxygen-responsive changes in the transcriptome occur are mediated through the hypoxia-inducible factor (HIF) pathway. Upon reduced oxygen conditions, HIF activates hypoxia-responsive gene expression programs. However, under normal oxygen conditions, the activity of HIF is regularly suppressed by cellular oxygen sensors; prolyl-4 and asparaginyl hydroxylases. Recently, these oxygen sensors have also been found to suppress the function of two lysine methyltransferases, G9a and G9a-like protein (GLP). In this manner, the methyltransferase activity of G9a and GLP are hypoxia-inducible and thus present a new avenue of low-oxygen signaling. Furthermore, G9a and GLP elicit lysine methylation on a wide variety of non-histone proteins, many of which are known to be regulated by hypoxia. In this article we aim to review the effects of oxygen on G9a and GLP function, non-histone methylation events inflicted by these methyltransferases, and the clinical relevance of these enzymes in cancer.
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Affiliation(s)
- Anand Chopra
- Institute of Biochemistry, Carleton University, Ottawa, ON, Canada.,Department of Biology, Carleton University, Ottawa, ON, Canada
| | - William C Cho
- Department of Clinical Oncology, Queen Elizabeth Hospital, Hong Kong, China
| | - William G Willmore
- Institute of Biochemistry, Carleton University, Ottawa, ON, Canada.,Department of Biology, Carleton University, Ottawa, ON, Canada
| | - Kyle K Biggar
- Institute of Biochemistry, Carleton University, Ottawa, ON, Canada.,Department of Biology, Carleton University, Ottawa, ON, Canada
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17
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Rolicka A, Guo Y, Gañez Zapater A, Tariq K, Quin J, Vintermist A, Sadeghifar F, Arsenian-Henriksson M, Östlund Farrants AK. The chromatin-remodeling complexes B-WICH and NuRD regulate ribosomal transcription in response to glucose. FASEB J 2020; 34:10818-10834. [PMID: 32598531 DOI: 10.1096/fj.202000411r] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Revised: 05/26/2020] [Accepted: 06/04/2020] [Indexed: 12/20/2022]
Abstract
Regulation of ribosomal transcription is under tight control from environmental stimuli, and this control involves changes in the chromatin structure. The underlying mechanism of how chromatin changes in response to nutrient and energy supply in the cell is still unclear. The chromatin-remodeling complex B-WICH is involved in activating the ribosomal transcription, and we show here that knock down of the B-WICH component WSTF results in cells that do not respond to glucose. The promoter is less accessible, and RNA pol I and its transcription factors SL1/TIF-1B and RRN3/TIF-1A, as well as the proto-oncogene c-MYC and the activating deacetylase SIRT7 do not bind upon glucose stimulation. In contrast, the repressive chromatin state that forms after glucose deprivation is reversible, and RNA pol I factors are recruited. WSTF knock down results in an accumulation of the ATPase CHD4, a component of the NuRD chromatin remodeling complex, which is responsible for establishing a repressive poised state at the promoter. The TTF-1, which binds and affect the binding of the chromatin complexes, is important to control the association of activating chromatin component UBF. We suggest that B-WICH is required to allow for a shift to an active chromatin state upon environmental stimulation, by counteracting the repressive state induced by the NuRD complex.
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Affiliation(s)
- Anna Rolicka
- Department of Molecular Biosciences, The Wenner-Gren Institute, The Arrhenius Lab F4, Stockholm University, Stockholm, Sweden
| | - Yuan Guo
- Department of Molecular Biosciences, The Wenner-Gren Institute, The Arrhenius Lab F4, Stockholm University, Stockholm, Sweden
| | - Antoni Gañez Zapater
- Department of Molecular Biosciences, The Wenner-Gren Institute, The Arrhenius Lab F4, Stockholm University, Stockholm, Sweden
| | - Kanwal Tariq
- Department of Molecular Biosciences, The Wenner-Gren Institute, The Arrhenius Lab F4, Stockholm University, Stockholm, Sweden
| | - Jaclyn Quin
- Department of Molecular Biosciences, The Wenner-Gren Institute, The Arrhenius Lab F4, Stockholm University, Stockholm, Sweden
| | - Anna Vintermist
- Department of Molecular Biosciences, The Wenner-Gren Institute, The Arrhenius Lab F4, Stockholm University, Stockholm, Sweden
| | - Fatemeh Sadeghifar
- Department of Molecular Biosciences, The Wenner-Gren Institute, The Arrhenius Lab F4, Stockholm University, Stockholm, Sweden
| | - Marie Arsenian-Henriksson
- Department of Microbiology, Tumor and Cell Biology (MTC), Biomedicum B7, Karolinska Institutet, Stockholm, Sweden
| | - Ann-Kristin Östlund Farrants
- Department of Molecular Biosciences, The Wenner-Gren Institute, The Arrhenius Lab F4, Stockholm University, Stockholm, Sweden
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18
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Okur MN, Lee JH, Osmani W, Kimura R, Demarest TG, Croteau DL, Bohr VA. Cockayne syndrome group A and B proteins function in rRNA transcription through nucleolin regulation. Nucleic Acids Res 2020; 48:2473-2485. [PMID: 31970402 PMCID: PMC7049711 DOI: 10.1093/nar/gkz1242] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2018] [Revised: 12/30/2019] [Accepted: 12/31/2019] [Indexed: 02/07/2023] Open
Abstract
Cockayne Syndrome (CS) is a rare neurodegenerative disease characterized by short stature, accelerated aging and short lifespan. Mutations in two human genes, ERCC8/CSA and ERCC6/CSB, are causative for CS and their protein products, CSA and CSB, while structurally unrelated, play roles in DNA repair and other aspects of DNA metabolism in human cells. Many clinical and molecular features of CS remain poorly understood, and it was observed that CSA and CSB regulate transcription of ribosomal DNA (rDNA) genes and ribosome biogenesis. Here, we investigate the dysregulation of rRNA synthesis in CS. We report that Nucleolin (Ncl), a nucleolar protein that regulates rRNA synthesis and ribosome biogenesis, interacts with CSA and CSB. In addition, CSA induces ubiquitination of Ncl, enhances binding of CSB to Ncl, and CSA and CSB both stimulate the binding of Ncl to rDNA and subsequent rRNA synthesis. CSB and CSA also increase RNA Polymerase I loading to the coding region of the rDNA and this is Ncl dependent. These findings suggest that CSA and CSB are positive regulators of rRNA synthesis via Ncl regulation. Most CS patients carry mutations in CSA and CSB and present with similar clinical features, thus our findings provide novel insights into disease mechanism.
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Affiliation(s)
- Mustafa N Okur
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
| | - Jong-Hyuk Lee
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
| | - Wasif Osmani
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
| | - Risako Kimura
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
| | - Tyler G Demarest
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
| | - Deborah L Croteau
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
| | - Vilhelm A Bohr
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
- Danish Center for Healthy Aging, University of Copenhagen, Blegdamsvej 3B, 2200 Copenhagen N, Denmark
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19
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DNA Damage Changes Distribution Pattern and Levels of HP1 Protein Isoforms in the Nucleolus and Increases Phosphorylation of HP1β-Ser88. Cells 2019; 8:cells8091097. [PMID: 31533340 PMCID: PMC6770535 DOI: 10.3390/cells8091097] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2019] [Revised: 09/10/2019] [Accepted: 09/10/2019] [Indexed: 12/28/2022] Open
Abstract
The family of heterochromatin protein 1 (HP1) isoforms is essential for chromatin packaging, regulation of gene expression, and repair of damaged DNA. Here we document that γ-radiation reduced the number of HP1α-positive foci, but not HP1β and HP1γ foci, located in the vicinity of the fibrillarin-positive region of the nucleolus. The additional analysis confirmed that γ-radiation has the ability to significantly decrease the level of HP1α in rDNA promoter and rDNA encoding 28S rRNA. By mass spectrometry, we showed that treatment by γ-rays enhanced the HP1β serine 88 phosphorylation (S88ph), but other analyzed modifications of HP1β, including S161ph/Y163ph, S171ph, and S174ph, were not changed in cells exposed to γ-rays or treated by the HDAC inhibitor (HDACi). Interestingly, a combination of HDACi and γ-radiation increased the level of HP1α and HP1γ. The level of HP1β remained identical before and after the HDACi/γ-rays treatment, but HDACi strengthened HP1β interaction with the KRAB-associated protein 1 (KAP1) protein. Conversely, HP1γ did not interact with KAP1, although approximately 40% of HP1γ foci co-localized with accumulated KAP1. Especially HP1γ foci at the periphery of nucleoli were mostly absent of KAP1. Together, DNA damage changed the morphology, levels, and interaction properties of HP1 isoforms. Also, γ-irradiation-induced hyperphosphorylation of the HP1β protein; thus, HP1β-S88ph could be considered as an important marker of DNA damage.
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20
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Yao RW, Xu G, Wang Y, Shan L, Luan PF, Wang Y, Wu M, Yang LZ, Xing YH, Yang L, Chen LL. Nascent Pre-rRNA Sorting via Phase Separation Drives the Assembly of Dense Fibrillar Components in the Human Nucleolus. Mol Cell 2019; 76:767-783.e11. [PMID: 31540874 DOI: 10.1016/j.molcel.2019.08.014] [Citation(s) in RCA: 163] [Impact Index Per Article: 32.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2018] [Revised: 02/04/2019] [Accepted: 08/13/2019] [Indexed: 12/21/2022]
Abstract
Fibrillar centers (FCs) and dense fibrillar components (DFCs) are essential morphologically distinct sub-regions of mammalian cell nucleoli for rDNA transcription and pre-rRNA processing. Here, we report that a human nucleolus consists of several dozen FC/DFC units, each containing 2-3 transcriptionally active rDNAs at the FC/DFC border. Pre-rRNA processing factors, such as fibrillarin (FBL), form 18-24 clusters that further assemble into the DFC surrounding the FC. Mechanistically, the 5' end of nascent 47S pre-rRNA binds co-transcriptionally to the RNA-binding domain of FBL. FBL diffuses to the DFC, where local self-association via its glycine- and arginine-rich (GAR) domain forms phase-separated clusters to immobilize FBL-interacting pre-rRNA, thus promoting directional traffic of nascent pre-rRNA while facilitating pre-rRNA processing and DFC formation. These results unveil FC/DFC ultrastructures in nucleoli and suggest a conceptual framework for considering nascent RNA sorting using multivalent interactions of their binding proteins.
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Affiliation(s)
- Run-Wen Yao
- State Key Laboratory of Molecular Biology, Shanghai Key Laboratory of Molecular Andrology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 320 Yueyang Road, Shanghai 200031, China
| | - Guang Xu
- State Key Laboratory of Molecular Biology, Shanghai Key Laboratory of Molecular Andrology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 320 Yueyang Road, Shanghai 200031, China
| | - Ying Wang
- CAS Key Laboratory of Computational Biology, CAS-MPG Partner Institute for Computational Biology, Shanghai Institute of Nutrition and Health, Shanghai Institutes for Biological Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 320 Yueyang Road, Shanghai 200031, China
| | - Lin Shan
- State Key Laboratory of Molecular Biology, Shanghai Key Laboratory of Molecular Andrology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 320 Yueyang Road, Shanghai 200031, China
| | - Peng-Fei Luan
- State Key Laboratory of Molecular Biology, Shanghai Key Laboratory of Molecular Andrology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 320 Yueyang Road, Shanghai 200031, China
| | - Yang Wang
- State Key Laboratory of Molecular Biology, Shanghai Key Laboratory of Molecular Andrology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 320 Yueyang Road, Shanghai 200031, China
| | - Man Wu
- State Key Laboratory of Molecular Biology, Shanghai Key Laboratory of Molecular Andrology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 320 Yueyang Road, Shanghai 200031, China
| | - Liang-Zhong Yang
- State Key Laboratory of Molecular Biology, Shanghai Key Laboratory of Molecular Andrology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 320 Yueyang Road, Shanghai 200031, China
| | - Yu-Hang Xing
- State Key Laboratory of Molecular Biology, Shanghai Key Laboratory of Molecular Andrology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 320 Yueyang Road, Shanghai 200031, China
| | - Li Yang
- CAS Key Laboratory of Computational Biology, CAS-MPG Partner Institute for Computational Biology, Shanghai Institute of Nutrition and Health, Shanghai Institutes for Biological Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 320 Yueyang Road, Shanghai 200031, China; School of Life Science and Technology, ShanghaiTech University, 100 Haike Road, Shanghai 201210, China
| | - Ling-Ling Chen
- State Key Laboratory of Molecular Biology, Shanghai Key Laboratory of Molecular Andrology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 320 Yueyang Road, Shanghai 200031, China; School of Life Science and Technology, ShanghaiTech University, 100 Haike Road, Shanghai 201210, China.
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21
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Kresoja-Rakic J, Santoro R. Nucleolus and rRNA Gene Chromatin in Early Embryo Development. Trends Genet 2019; 35:868-879. [PMID: 31327501 DOI: 10.1016/j.tig.2019.06.005] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Revised: 06/17/2019] [Accepted: 06/24/2019] [Indexed: 12/16/2022]
Abstract
The nucleolus is the largest substructure in the nucleus and forms around the nucleolar organizer regions (NORs), which comprise hundreds of rRNA genes. Recent evidence highlights further functions of the nucleolus that go beyond ribosome biogenesis. Data indicate that the nucleolus acts as a compartment for the location and regulation of repressive genomic domains and, together with the nuclear lamina, represents the hub for the organization of the inactive heterochromatin. In this review, we discuss recent findings that have revealed how nucleolar structure and rRNA gene chromatin states are regulated during early mammalian development and their contribution to the higher-order spatial organization of the genome.
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Affiliation(s)
- Jelena Kresoja-Rakic
- Department of Molecular Mechanisms of Disease, DMMD, University of Zurich, CH-8057 Zurich, Switzerland
| | - Raffaella Santoro
- Department of Molecular Mechanisms of Disease, DMMD, University of Zurich, CH-8057 Zurich, Switzerland.
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22
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Liu X, Cai S, Zhang C, Liu Z, Luo J, Xing B, Du X. Deacetylation of NAT10 by Sirt1 promotes the transition from rRNA biogenesis to autophagy upon energy stress. Nucleic Acids Res 2019; 46:9601-9616. [PMID: 30165671 PMCID: PMC6182161 DOI: 10.1093/nar/gky777] [Citation(s) in RCA: 62] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2018] [Accepted: 08/17/2018] [Indexed: 02/06/2023] Open
Abstract
Anabolism and catabolism are tightly regulated according to the cellular energy supply. Upon energy stress, ribosomal RNA (rRNA) biogenesis is inhibited, and autophagy is induced. However, the mechanism linking rRNA biogenesis and autophagy is unclear. Here, we demonstrate that the nucleolar protein NAT10 plays a role in the transition between rRNA biogenesis and autophagy. Under normal conditions, NAT10 is acetylated to activate rRNA biogenesis and inhibit autophagy induction. Mechanistic studies demonstrate that NAT10 binds to and acetylates the autophagy regulator Che-1 at K228 to suppress the Che-1-mediated transcriptional activation of downstream genes Redd1 and Deptor under adequate energy supply conditions. Upon energy stress, NAT10 is deacetylated by Sirt1, leading to suppression of NAT10-activated rRNA biogenesis. In addition, deacetylation of NAT10 abolishes the NAT10-mediated transcriptional repression of Che-1, leading to the release of autophagy inhibition. Collectively, we demonstrate that the acetylation status of NAT10 is important for the anabolism-catabolism transition in response to energy stress, providing a novel mechanism by which nucleolar proteins control rRNA synthesis and autophagy in response to the cellular energy supply.
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Affiliation(s)
- Xiaofeng Liu
- Hepatopancreatobiliary Surgery Department I, Key laboratory of Carcinogenesis and Translational Research (Ministry of Education/Beijing), Peking University Cancer Hospital & Institute, Beijing 100142, China
| | - Shiying Cai
- Department of Cell Biology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing 100191, China
| | - Chunfeng Zhang
- Department of Medical Genetics, School of Basic Medical Sciences, Peking University Health Science Center, Beijing 100191, China
| | - Zhenzhen Liu
- Hepatopancreatobiliary Surgery Department I, Key laboratory of Carcinogenesis and Translational Research (Ministry of Education/Beijing), Peking University Cancer Hospital & Institute, Beijing 100142, China
| | - Jianyuan Luo
- Department of Medical Genetics, School of Basic Medical Sciences, Peking University Health Science Center, Beijing 100191, China
| | - Baocai Xing
- Hepatopancreatobiliary Surgery Department I, Key laboratory of Carcinogenesis and Translational Research (Ministry of Education/Beijing), Peking University Cancer Hospital & Institute, Beijing 100142, China
| | - Xiaojuan Du
- Department of Cell Biology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing 100191, China
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23
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Genome Organization in and around the Nucleolus. Cells 2019; 8:cells8060579. [PMID: 31212844 PMCID: PMC6628108 DOI: 10.3390/cells8060579] [Citation(s) in RCA: 71] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Revised: 06/09/2019] [Accepted: 06/11/2019] [Indexed: 12/17/2022] Open
Abstract
The nucleolus is the largest substructure in the nucleus, where ribosome biogenesis takes place, and forms around the nucleolar organizer regions (NORs) that comprise ribosomal RNA (rRNA) genes. Each cell contains hundreds of rRNA genes, which are organized in three distinct chromatin and transcriptional states—silent, inactive and active. Increasing evidence indicates that the role of the nucleolus and rRNA genes goes beyond the control of ribosome biogenesis. Recent results highlighted the nucleolus as a compartment for the location and regulation of repressive genomic domains and, together with the nuclear lamina, represents the hub for the organization of the inactive heterochromatin. In this review, we aim to describe the crosstalk between the nucleolus and the rest of the genome and how distinct rRNA gene chromatin states affect nucleolus structure and are implicated in genome stability, genome architecture, and cell fate decision.
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24
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Phan T, Khalid F, Iben S. Nucleolar and Ribosomal Dysfunction-A Common Pathomechanism in Childhood Progerias? Cells 2019; 8:E534. [PMID: 31167386 PMCID: PMC6627804 DOI: 10.3390/cells8060534] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2019] [Revised: 05/21/2019] [Accepted: 06/02/2019] [Indexed: 01/03/2023] Open
Abstract
The nucleolus organizes around the sites of transcription by RNA polymerase I (RNA Pol I). rDNA transcription by this enzyme is the key step of ribosome biogenesis and most of the assembly and maturation processes of the ribosome occur co-transcriptionally. Therefore, disturbances in rRNA transcription and processing translate to ribosomal malfunction. Nucleolar malfunction has recently been described in the classical progeria of childhood, Hutchinson-Gilford syndrome (HGPS), which is characterized by severe signs of premature aging, including atherosclerosis, alopecia, and osteoporosis. A deregulated ribosomal biogenesis with enlarged nucleoli is not only characteristic for HGPS patients, but it is also found in the fibroblasts of "normal" aging individuals. Cockayne syndrome (CS) is also characterized by signs of premature aging, including the loss of subcutaneous fat, alopecia, and cataracts. It has been shown that all genes in which a mutation causes CS, are involved in rDNA transcription by RNA Pol I. A disturbed ribosomal biogenesis affects mitochondria and translates into ribosomes with a reduced translational fidelity that causes endoplasmic reticulum (ER) stress and apoptosis. Therefore, it is speculated that disease-causing disturbances in the process of ribosomal biogenesis may be more common than hitherto anticipated.
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Affiliation(s)
- Tamara Phan
- Department of Dermatology, Ulm University, James-Franck Ring N27, 89081 Ulm, Germany.
| | - Fatima Khalid
- Department of Dermatology, Ulm University, James-Franck Ring N27, 89081 Ulm, Germany.
| | - Sebastian Iben
- Department of Dermatology, Ulm University, James-Franck Ring N27, 89081 Ulm, Germany.
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25
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Molecular basis of chromatin remodeling by Rhp26, a yeast CSB ortholog. Proc Natl Acad Sci U S A 2019; 116:6120-6129. [PMID: 30867290 DOI: 10.1073/pnas.1818163116] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
CSB/ERCC6 belongs to an orphan subfamily of SWI2/SNF2-related chromatin remodelers and plays crucial roles in gene expression, DNA damage repair, and the maintenance of genome integrity. The molecular basis of chromatin remodeling by Cockayne syndrome B protein (CSB) is not well understood. Here we investigate the molecular mechanism of chromatin remodeling by Rhp26, a Schizosaccharomyces pombe CSB ortholog. The molecular basis of chromatin remodeling and nucleosomal epitope recognition by Rhp26 is distinct from that of canonical chromatin remodelers, such as imitation switch protein (ISWI). We reveal that the remodeling activities are bidirectionally regulated by CSB-specific motifs: the N-terminal leucine-latch motif and the C-terminal coupling motif. Rhp26 remodeling activities depend mainly on H4 tails and to a lesser extent on H3 tails, but not on H2A and H2B tails. Rhp26 promotes the disruption of histone cores and the release of free DNA. Finally, we dissected the distinct contributions of two Rhp26 C-terminal regions to chromatin remodeling and DNA damage repair.
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Iyama T, Okur MN, Golato T, McNeill DR, Lu H, Hamilton R, Raja A, Bohr VA, Wilson DM. Regulation of the Intranuclear Distribution of the Cockayne Syndrome Proteins. Sci Rep 2018; 8:17490. [PMID: 30504782 PMCID: PMC6269539 DOI: 10.1038/s41598-018-36027-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Accepted: 11/01/2018] [Indexed: 12/04/2022] Open
Abstract
Cockayne syndrome (CS) is an inherited disorder that involves photosensitivity, developmental defects, progressive degeneration and characteristics of premature aging. Evidence indicates primarily nuclear roles for the major CS proteins, CSA and CSB, specifically in DNA repair and RNA transcription. We reveal herein a complex regulation of CSB targeting that involves three major consensus signals: NLS1 (aa467-481), which directs nuclear and nucleolar localization in cooperation with NoLS1 (aa302-341), and NLS2 (aa1038-1055), which seemingly optimizes nuclear enrichment. CSB localization to the nucleolus was also found to be important for full UVC resistance. CSA, which does not contain any obvious targeting sequences, was adversely affected (i.e. presumably destabilized) by any form of truncation. No inter-coordination between the subnuclear localization of CSA and CSB was observed, implying that this aspect does not underlie the clinical features of CS. The E3 ubiquitin ligase binding partner of CSA, DDB1, played an important role in CSA stability (as well as DDB2), and facilitated CSA association with chromatin following UV irradiation; yet did not affect CSB chromatin binding. We also observed that initial recruitment of CSB to DNA interstrand crosslinks is similar in the nucleoplasm and nucleolus, although final accumulation is greater in the former. Whereas assembly of CSB at sites of DNA damage in the nucleolus was not affected by RNA polymerase I inhibition, stable retention at these sites of presumed repair was abrogated. Our studies reveal a multi-faceted regulation of the intranuclear dynamics of CSA and CSB that plays a role in mediating their cellular functions.
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Affiliation(s)
- Teruaki Iyama
- Laboratory of Molecular Gerontology, National Institute on Aging, Intramural Research Program, National Institutes of Health, 251 Bayview Blvd., Ste. 100, Baltimore, MD, 21224, USA
| | - Mustafa N Okur
- Laboratory of Molecular Gerontology, National Institute on Aging, Intramural Research Program, National Institutes of Health, 251 Bayview Blvd., Ste. 100, Baltimore, MD, 21224, USA
| | - Tyler Golato
- Laboratory of Molecular Gerontology, National Institute on Aging, Intramural Research Program, National Institutes of Health, 251 Bayview Blvd., Ste. 100, Baltimore, MD, 21224, USA
| | - Daniel R McNeill
- Laboratory of Molecular Gerontology, National Institute on Aging, Intramural Research Program, National Institutes of Health, 251 Bayview Blvd., Ste. 100, Baltimore, MD, 21224, USA
| | - Huiming Lu
- Laboratory of Molecular Gerontology, National Institute on Aging, Intramural Research Program, National Institutes of Health, 251 Bayview Blvd., Ste. 100, Baltimore, MD, 21224, USA
| | - Royce Hamilton
- Laboratory of Molecular Gerontology, National Institute on Aging, Intramural Research Program, National Institutes of Health, 251 Bayview Blvd., Ste. 100, Baltimore, MD, 21224, USA
| | - Aishwarya Raja
- Laboratory of Molecular Gerontology, National Institute on Aging, Intramural Research Program, National Institutes of Health, 251 Bayview Blvd., Ste. 100, Baltimore, MD, 21224, USA
| | - Vilhelm A Bohr
- Laboratory of Molecular Gerontology, National Institute on Aging, Intramural Research Program, National Institutes of Health, 251 Bayview Blvd., Ste. 100, Baltimore, MD, 21224, USA
| | - David M Wilson
- Laboratory of Molecular Gerontology, National Institute on Aging, Intramural Research Program, National Institutes of Health, 251 Bayview Blvd., Ste. 100, Baltimore, MD, 21224, USA.
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Anderson EM, Penrod RD, Barry SM, Hughes BW, Taniguchi M, Cowan CW. It is a complex issue: emerging connections between epigenetic regulators in drug addiction. Eur J Neurosci 2018; 50:2477-2491. [PMID: 30251397 DOI: 10.1111/ejn.14170] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2018] [Revised: 09/04/2018] [Accepted: 09/11/2018] [Indexed: 02/06/2023]
Abstract
Drug use leads to addiction in some individuals, but the underlying brain mechanisms that control the transition from casual drug use to an intractable substance use disorder (SUD) are not well understood. Gene x environment interactions such as the frequency of drug use and the type of substance used likely to promote maladaptive plastic changes in brain regions that are critical for controlling addiction-related behavior. Epigenetics encompasses a broad spectrum of mechanisms important for regulating gene transcription that are not dependent on changes in DNA base pair sequences. This review focuses on the proteins and complexes contributing to epigenetic modifications in the nucleus accumbens (NAc) following drug experience. We discuss in detail the three major mechanisms: histone acetylation and deacetylation, histone methylation, and DNA methylation. We discuss how drug use alters the regulation of the associated proteins regulating these processes and highlight how experimental manipulations of these proteins in the NAc can alter drug-related behaviors. Finally, we discuss the ways that histone modifications and DNA methylation coordinate actions by recruiting large epigenetic enzyme complexes to aid in transcriptional repression. Targeting these multiprotein epigenetic enzyme complexes - and the individual proteins that comprise them - might lead to effective therapeutics to reverse or treat SUDs in patients.
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Affiliation(s)
- Ethan M Anderson
- Departments of Neuroscience and Psychiatry and Behavioral Sciences, Medical University of South Carolina, 173 Ashley Ave, MSC 510, Charleston, SC, 29425-2030, USA
| | - Rachel D Penrod
- Departments of Neuroscience and Psychiatry and Behavioral Sciences, Medical University of South Carolina, 173 Ashley Ave, MSC 510, Charleston, SC, 29425-2030, USA
| | - Sarah M Barry
- Departments of Neuroscience and Psychiatry and Behavioral Sciences, Medical University of South Carolina, 173 Ashley Ave, MSC 510, Charleston, SC, 29425-2030, USA
| | - Brandon W Hughes
- Departments of Neuroscience and Psychiatry and Behavioral Sciences, Medical University of South Carolina, 173 Ashley Ave, MSC 510, Charleston, SC, 29425-2030, USA
| | - Makoto Taniguchi
- Departments of Neuroscience and Psychiatry and Behavioral Sciences, Medical University of South Carolina, 173 Ashley Ave, MSC 510, Charleston, SC, 29425-2030, USA
| | - Christopher W Cowan
- Departments of Neuroscience and Psychiatry and Behavioral Sciences, Medical University of South Carolina, 173 Ashley Ave, MSC 510, Charleston, SC, 29425-2030, USA
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Sanchez-Roman I, Lautrup S, Aamann MD, Neilan EG, Østergaard JR, Stevnsner T. Two Cockayne Syndrome patients with a novel splice site mutation - clinical and metabolic analyses. Mech Ageing Dev 2018; 175:7-16. [PMID: 29944916 DOI: 10.1016/j.mad.2018.06.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2018] [Revised: 05/11/2018] [Accepted: 06/06/2018] [Indexed: 01/03/2023]
Abstract
Cockayne Syndrome (CS) is a rare autosomal recessive disorder, which leads to neurodegeneration, growth failure and premature aging. Most of the cases are due to mutations in the ERCC6 gene, which encodes the protein CSB. CSB is involved in several functions including DNA repair and transcription. Here we describe two Danish brothers with CS. Both patients carried a novel splice site mutation (c.2382+2T>G), and a previously described nonsense mutation (c.3259C>T, p.Arg1087X) in a biallelic state. Both patients presented the cardinal features of the disease including microcephaly, congenital cataract and postnatal growth failure. In addition, their fibroblasts were hypersensitive to UV irradiation and exhibited increased superoxide levels in comparison to fibroblasts from healthy age and gender matched individuals. Metabolomic analysis revealed a distinctive metabolic profile in cells from the CS patients compared to control cells. Among others, α-ketoglutarate, hydroxyglutarate and certain amino acids (ornithine, proline and glycine) were reduced in the CS patient fibroblasts, whereas glycolytic intermediates (glucose-6-phosphate and pyruvic acid) and fatty acids (palmitic, stearic and myristic acid) were increased. Our data not only provide additional information to the database of CS mutations, but also point towards targets for potential treatment of this devastating disease.
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Affiliation(s)
- Ines Sanchez-Roman
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark; Department of Basic Biomedical Science, Faculty of Biomedical and Health Sciences, Universidad Europea de Madrid, Madrid, Spain
| | - Sofie Lautrup
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark
| | - Maria Diget Aamann
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark
| | - Edward G Neilan
- Division of Genetics and Genomics, Boston Children's Hospital and Harvard Medical School, Boston, MA, USA
| | - John R Østergaard
- Centre for Rare Diseases, Department of Pediatrics, Aarhus University Hospital, Aarhus, Denmark
| | - Tinna Stevnsner
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark.
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Abstract
Ribosome biogenesis is a complex and highly energy-demanding process that requires the concerted action of all three nuclear RNA polymerases (Pol I-III) in eukaryotes. The three largest ribosomal RNAs (rRNAs) originate from a precursor transcript (pre-rRNA) that is encoded by multicopy genes located in the nucleolus. Transcription of these rRNA genes (rDNA) by Pol I is the key regulation step in ribosome production and is tightly controlled by an intricate network of signaling pathways and epigenetic mechanisms. In this article, we give an overview of the composition of the basal Pol I machinery and rDNA chromatin. We discuss rRNA gene regulation in response to environmental signals and developmental cues and focus on perturbations occurring in diseases linked to either excessive or limited rRNA levels. Finally, we discuss the emerging view that rDNA integrity and activity may be involved in the aging process.
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Affiliation(s)
- Samim Sharifi
- Institute of Biochemistry and Biophysics, Center for Molecular Biomedicine, Friedrich Schiller University, 07745 Jena, Germany; , .,Leibniz-Institute on Aging-Fritz Lipmann Institute, 07745 Jena, Germany
| | - Holger Bierhoff
- Institute of Biochemistry and Biophysics, Center for Molecular Biomedicine, Friedrich Schiller University, 07745 Jena, Germany; , .,Leibniz-Institute on Aging-Fritz Lipmann Institute, 07745 Jena, Germany
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30
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Neben CL, Tuzon CT, Mao X, Lay FD, Merrill AE. FGFR2 mutations in bent bone dysplasia syndrome activate nucleolar stress and perturb cell fate determination. Hum Mol Genet 2018; 26:3253-3270. [PMID: 28595297 DOI: 10.1093/hmg/ddx209] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Accepted: 05/31/2017] [Indexed: 12/21/2022] Open
Abstract
Fibroblast Growth Factor (FGF) signaling promotes self-renewal in progenitor cells by encouraging proliferation and inhibiting cellular senescence. Yet, these beneficial effects can be hijacked by disease-causing mutations in FGF receptor (FGFR) during embryogenesis. By studying dominant FGFR2 mutations that are germline in bent bone dysplasia syndrome (BBDS), we reveal a mechanistic connection between FGFR2, ribosome biogenesis, and cellular stress that links cell fate determination to disease pathology. We previously showed that FGFR2 mutations in BBDS, which amplify nucleolar targeting of FGFR2, activate ribosomal DNA (rDNA) transcription and delay differentiation in osteoprogenitor cells and patient-derived bone. Here we find that the BBDS mutations augment the ability of FGFR2 to recruit histone-remodeling factors that epigenetically activate transcriptionally silent rDNA. Nucleolar morphology is controlled by chromatin structure, and the high levels of euchromatic rDNA induced by the BBDS mutations direct nucleolar disorganization, alter ribosome biogenesis, and activate the Rpl11-Mdm2-p53 nucleolar stress response pathway. Inhibition of p53 in cells expressing the FGFR2 mutations in BBDS rescues delayed osteoblast differentiation, suggesting that p53 activation is an essential pathogenic factor in, and potential therapeutic target for, BBDS. This work establishes rDNA as developmentally regulated loci that receive direct input from FGF signaling to balance self-renewal and cell fate determination.
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Affiliation(s)
- Cynthia L Neben
- Center for Craniofacial Molecular Biology, Ostrow School of Dentistry.,Department of Biochemistry and Molecular Biology, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Creighton T Tuzon
- Center for Craniofacial Molecular Biology, Ostrow School of Dentistry.,Department of Biochemistry and Molecular Biology, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Xiaojing Mao
- Center for Craniofacial Molecular Biology, Ostrow School of Dentistry.,Department of Biochemistry and Molecular Biology, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Fides D Lay
- Department of Biochemistry and Molecular Biology, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Amy E Merrill
- Center for Craniofacial Molecular Biology, Ostrow School of Dentistry.,Department of Biochemistry and Molecular Biology, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
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Shao P, Liu Q, Maina PK, Cui J, Bair TB, Li T, Umesalma S, Zhang W, Qi HH. Histone demethylase PHF8 promotes epithelial to mesenchymal transition and breast tumorigenesis. Nucleic Acids Res 2017; 45:1687-1702. [PMID: 27899639 PMCID: PMC5389682 DOI: 10.1093/nar/gkw1093] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Accepted: 10/27/2016] [Indexed: 12/21/2022] Open
Abstract
Histone demethylase PHF8 is upregulated and plays oncogenic roles in various cancers; however, the mechanisms underlying its dysregulation and functions in carcinogenesis remain obscure. Here, we report the novel functions of PHF8 in EMT (epithelial to mesenchymal transition) and breast cancer development. Genome-wide gene expression analysis revealed that PHF8 overexpression induces an EMT-like process, including the upregulation of SNAI1 and ZEB1. PHF8 demethylates H3K9me1, H3K9me2 and sustains H3K4me3 to prime the transcriptional activation of SNAI1 by TGF-β signaling. We show that PHF8 is upregulated and positively correlated with MYC at protein levels in breast cancer. MYC post-transcriptionally regulates the expression of PHF8 via the repression of microRNAs. Specifically, miR-22 directly targets and inhibits PHF8 expression, and mediates the regulation of PHF8 by MYC and TGF-β signaling. This novel MYC/microRNAs/PHF8 regulatory axis thus places PHF8 as an important downstream effector of MYC. Indeed, PHF8 contributes to MYC-induced cell proliferation and the expression of EMT-related genes. We also report that PHF8 plays important roles in breast cancer cell migration and tumor growth. These oncogenic functions of PHF8 in breast cancer confer its candidacy as a promising therapeutic target for this disease.
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Affiliation(s)
- Peng Shao
- Department of Anatomy and Cell Biology, Carver College of Medicine, The University of Iowa, IA 52242, USA
| | - Qi Liu
- Department of Anatomy and Cell Biology, Carver College of Medicine, The University of Iowa, IA 52242, USA
| | - Peterson Kariuki Maina
- Department of Anatomy and Cell Biology, Carver College of Medicine, The University of Iowa, IA 52242, USA
| | - Jiayue Cui
- Department of Histology and Embryology, College of Basic Medical Sciences, Jilin University, Changchun 130021, China
| | - Thomas B Bair
- Iowa Institute of Human Genetics, Carver College of Medicine, The University of Iowa, IA 52242, USA
| | - Tiandao Li
- McDonnell Genome Institute, Washington University, St. Louis, MO 63108, USA
| | - Shaikamjad Umesalma
- Department of Pathology, Carver College of Medicine, The University of Iowa, IA 52242, USA
| | - Weizhou Zhang
- Department of Pathology, Carver College of Medicine, The University of Iowa, IA 52242, USA
| | - Hank Heng Qi
- Department of Anatomy and Cell Biology, Carver College of Medicine, The University of Iowa, IA 52242, USA
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UV-induced proteolysis of RNA polymerase II is mediated by VCP/p97 segregase and timely orchestration by Cockayne syndrome B protein. Oncotarget 2017; 8:11004-11019. [PMID: 28036256 PMCID: PMC5355241 DOI: 10.18632/oncotarget.14205] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Accepted: 12/20/2016] [Indexed: 11/25/2022] Open
Abstract
RNA polymerase II (RNAPII) acts as a damage sensor for transcription-coupled nucleotide excision repair (TC-NER) and undergoes proteolytic clearance from damaged chromatin by the ubiquitin-proteasome system (UPS). Here, we report that Valosin-containing protein (VCP)/p97, a druggable oncotarget, is essential for RNAPII's proteolytic clearance in mammalian cells. We show that inhibition of VCP/p97, or siRNA-mediated ablation of VCP/p97 and its cofactors UFD1 and UBXD7 severely impairs ultraviolet radiation (UVR)-induced RNAPII degradation. VCP/p97 interacts with RNAPII, and the interaction is enhanced by Cockayne syndrome B protein (CSB). However, the VCP/p97-mediated RNAPII proteolysis occurs independent of CSB. Surprisingly, CSB enhances UVR-induced RNAPII ubiquitination but delays its turnover. Additionally, VCP/p97-mediated RNAPII turnover occurs with and without Von Hippel-Lindau tumor suppressor protein (pVHL), a known substrate receptor of Elongin E3 ubiquitin ligase for RNAPII. Moreover, pVHL re-expression improves cell viability following UVR. Whereas, VCP/p97 inhibition decreases cell viability and enhances a low-dose UVR killing in presence of pVHL. These findings reveal a function of VCP/p97 segregase in UVR-induced RNAPII degradation in mammalian cells, and suggest a role of CSB in coordinating VCP/p97-mediated extraction of ubiquitinated RNAPII and CSB itself from chromatin.
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Tsekrekou M, Stratigi K, Chatzinikolaou G. The Nucleolus: In Genome Maintenance and Repair. Int J Mol Sci 2017; 18:ijms18071411. [PMID: 28671574 PMCID: PMC5535903 DOI: 10.3390/ijms18071411] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2017] [Revised: 06/22/2017] [Accepted: 06/27/2017] [Indexed: 11/16/2022] Open
Abstract
The nucleolus is the subnuclear membrane-less organelle where rRNA is transcribed and processed and ribosomal assembly occurs. During the last 20 years, however, the nucleolus has emerged as a multifunctional organelle, regulating processes that go well beyond its traditional role. Moreover, the unique organization of rDNA in tandem arrays and its unusually high transcription rates make it prone to unscheduled DNA recombination events and frequent RNA:DNA hybrids leading to DNA double strand breaks (DSBs). If not properly repaired, rDNA damage may contribute to premature disease onset and aging. Deregulation of ribosomal synthesis at any level from transcription and processing to ribosomal subunit assembly elicits a stress response and is also associated with disease onset. Here, we discuss how genome integrity is maintained within nucleoli and how such structures are functionally linked to nuclear DNA damage response and repair giving an emphasis on the newly emerging roles of the nucleolus in mammalian physiology and disease.
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Affiliation(s)
- Maria Tsekrekou
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Nikolaou Plastira 100, 70013 Heraklion, Crete, Greece.
- Department of Biology, University of Crete, Vassilika Vouton, 71409 Heraklion, Crete, Greece.
| | - Kalliopi Stratigi
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Nikolaou Plastira 100, 70013 Heraklion, Crete, Greece.
- Department of Biology, University of Crete, Vassilika Vouton, 71409 Heraklion, Crete, Greece.
| | - Georgia Chatzinikolaou
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Nikolaou Plastira 100, 70013 Heraklion, Crete, Greece.
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35
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Caputo M, Balzerano A, Arisi I, D’Onofrio M, Brandi R, Bongiorni S, Brancorsini S, Frontini M, Proietti-De-Santis L. CSB ablation induced apoptosis is mediated by increased endoplasmic reticulum stress response. PLoS One 2017; 12:e0172399. [PMID: 28253359 PMCID: PMC5333825 DOI: 10.1371/journal.pone.0172399] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Accepted: 02/03/2017] [Indexed: 12/17/2022] Open
Abstract
The DNA repair protein Cockayne syndrome group B (CSB) has been recently identified as a promising anticancer target. Suppression, by antisense technology, of this protein causes devastating effects on tumor cells viability, through a massive induction of apoptosis, while being non-toxic to non-transformed cells. To gain insights into the mechanisms underlying the pro-apoptotic effects observed after CSB ablation, global gene expression patterns were determined, to identify genes that were significantly differentially regulated as a function of CSB expression. Our findings revealed that response to endoplasmic reticulum stress and response to unfolded proteins were ranked top amongst the cellular processes affected by CSB suppression. The major components of the endoplasmic reticulum stress-mediated apoptosis pathway, including pro-apoptotic factors downstream of the ATF3-CHOP cascade, were dramatically up-regulated. Altogether our findings add new pieces to the understanding of CSB mechanisms of action and to the molecular basis of CS syndrome.
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Affiliation(s)
- Manuela Caputo
- Unit of Molecular Genetics of Aging—Department of Ecology and Biology—University of Tuscia, Viterbo, Italy
| | - Alessio Balzerano
- Unit of Molecular Genetics of Aging—Department of Ecology and Biology—University of Tuscia, Viterbo, Italy
| | - Ivan Arisi
- Genomics Facility, European Brain Research Institute (EBRI) “Rita Levi-Montalcini”, Rome, Italy
| | - Mara D’Onofrio
- Genomics Facility, European Brain Research Institute (EBRI) “Rita Levi-Montalcini”, Rome, Italy
| | - Rossella Brandi
- Genomics Facility, European Brain Research Institute (EBRI) “Rita Levi-Montalcini”, Rome, Italy
| | - Silvia Bongiorni
- Unit of Molecular Genetics of Aging—Department of Ecology and Biology—University of Tuscia, Viterbo, Italy
| | - Stefano Brancorsini
- Department of Experimental Medicine—Section of Terni, University of Perugia, Terni, Italy
| | - Mattia Frontini
- Department of Haematology, University of Cambridge, Cambridge Biomedical Campus, Cambridge, United Kingdom
- National Health Service (NHS) Blood and Transplant, Cambridge Biomedical Campus, Cambridge, United Kingdom
- British Heart Foundation Centre of Excellence, University of Cambridge, Cambridge Biomedical Campus, Cambridge, United Kingdom
| | - Luca Proietti-De-Santis
- Unit of Molecular Genetics of Aging—Department of Ecology and Biology—University of Tuscia, Viterbo, Italy
- * E-mail:
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36
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Nucleotide Excision Repair: From Neurodegeneration to Cancer. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 1007:17-39. [PMID: 28840550 DOI: 10.1007/978-3-319-60733-7_2] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
DNA damage poses a constant threat to genome integrity taking a variety of shapes and arising by normal cellular metabolism or environmental insults. Human syndromes, characterized by increased cancer pre-disposition or early onset of age-related pathology and developmental abnormalities, often result from defective DNA damage responses and compromised genome integrity. Over the last decades intensive research worldwide has made important contributions to our understanding of the molecular mechanisms underlying genomic instability and has substantiated the importance of DNA repair in cancer prevention in the general population. In this chapter, we discuss Nucleotide Excision Repair pathway, the causative role of its components in disease-related pathology and recent technological achievements that decipher mutational landscapes and may facilitate pathological classification and personalized therapy.
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Franek M, Kovaříková A, Bártová E, Kozubek S. Nucleolar Reorganization Upon Site-Specific Double-Strand Break Induction. J Histochem Cytochem 2016; 64:669-686. [PMID: 27680669 PMCID: PMC5084524 DOI: 10.1369/0022155416668505] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Accepted: 08/09/2016] [Indexed: 12/20/2022] Open
Abstract
DNA damage response (DDR) in ribosomal genes and mechanisms of DNA repair in embryonic stem cells (ESCs) are less explored nuclear events. DDR in ESCs should be unique due to their high proliferation rate, expression of pluripotency factors, and specific chromatin signature. Given short population doubling time and fast progress through G1 phase, ESCs require a sustained production of rRNA, which leads to the formation of large and prominent nucleoli. Although transcription of rRNA in the nucleolus is relatively well understood, little is known about DDR in this nuclear compartment. Here, we directed formation of double-strand breaks in rRNA genes with I- PpoI endonuclease, and we studied nucleolar morphology, DDR, and chromatin modifications. We observed a pronounced formation of I- PpoI-induced nucleolar caps, positive on BRCA1, NBS1, MDC1, γH2AX, and UBF1 proteins. We showed interaction of nucleolar protein TCOF1 with HDAC1 and TCOF1 with CARM1 after DNA injury. Moreover, H3R17me2a modification mediated by CARM1 was found in I- PpoI-induced nucleolar caps. Finally, we report that heterochromatin protein 1 is not involved in DNA repair of nucleolar caps.
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Affiliation(s)
- Michal Franek
- Institute of Biophysics, Academy of Sciences of the Czech Republic, Brno, Czech Republic (MF, AK, EB, SK)
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38
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Zhang Y, Najmi SM, Schneider DA. Transcription factors that influence RNA polymerases I and II: To what extent is mechanism of action conserved? BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2016; 1860:246-255. [PMID: 27989933 DOI: 10.1016/j.bbagrm.2016.10.010] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Revised: 10/07/2016] [Accepted: 10/25/2016] [Indexed: 01/05/2023]
Abstract
In eukaryotic cells, nuclear RNA synthesis is accomplished by at least three unique, multisubunit RNA polymerases. The roles of these enzymes are generally partitioned into the synthesis of the three major classes of RNA: rRNA, mRNA, and tRNA for RNA polymerases I, II, and III respectively. Consistent with their unique cellular roles, each enzyme has a complement of specialized transcription factors and enzymatic properties. However, not all transcription factors have evolved to affect only one eukaryotic RNA polymerase. In fact, many factors have been shown to influence the activities of multiple nuclear RNA polymerases. This review focuses on a subset of these factors, specifically addressing the mechanisms by which these proteins influence RNA polymerases I and II.
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Affiliation(s)
- Yinfeng Zhang
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, AL 35294
| | - Saman M Najmi
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, AL 35294
| | - David A Schneider
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, AL 35294
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Beyer S, Pontis J, Schirwis E, Battisti V, Rudolf A, Le Grand F, Ait-Si-Ali S. Canonical Wnt signalling regulates nuclear export of Setdb1 during skeletal muscle terminal differentiation. Cell Discov 2016; 2:16037. [PMID: 27790377 PMCID: PMC5067623 DOI: 10.1038/celldisc.2016.37] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2016] [Accepted: 09/19/2016] [Indexed: 02/06/2023] Open
Abstract
The histone 3 lysine 9 methyltransferase Setdb1 is essential for both stem cell pluripotency and terminal differentiation of different cell types. To shed light on the roles of Setdb1 in these mutually exclusive processes, we used mouse skeletal myoblasts as a model of terminal differentiation. Ex vivo studies on isolated single myofibres showed that Setdb1 is required for adult muscle stem cells expansion following activation. In vitro studies in skeletal myoblasts confirmed that Setdb1 suppresses terminal differentiation. Genomic binding analyses showed a release of Setdb1 from selected target genes upon myoblast terminal differentiation, concomitant to a nuclear export of Setdb1 to the cytoplasm. Both genomic release and cytoplasmic Setdb1 relocalisation during differentiation were dependent on canonical Wnt signalling. Transcriptomic assays in myoblasts unravelled a significant overlap between Setdb1 and Wnt3a regulated genetic programmes. Together, our findings revealed Wnt-dependent subcellular relocalisation of Setdb1 as a novel mechanism regulating Setdb1 functions and myogenesis.
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Affiliation(s)
- Sophie Beyer
- Centre National de la Recherche Scientifique CNRS-Université Paris Diderot, Sorbonne Paris Cité, Epigenetics and Cell Fate UMR7216 , Paris, France
| | - Julien Pontis
- Centre National de la Recherche Scientifique CNRS-Université Paris Diderot, Sorbonne Paris Cité, Epigenetics and Cell Fate UMR7216 , Paris, France
| | - Elija Schirwis
- Institut Cochin, Université Paris-Descartes, Centre National de la Recherche Scientifique (CNRS) UMR8104, Paris, France; Institut National de la Santé et de la Recherche Médicale (INSERM) U1016, Paris, France
| | - Valentine Battisti
- Centre National de la Recherche Scientifique CNRS-Université Paris Diderot, Sorbonne Paris Cité, Epigenetics and Cell Fate UMR7216 , Paris, France
| | - Anja Rudolf
- Institut Cochin, Université Paris-Descartes, Centre National de la Recherche Scientifique (CNRS) UMR8104, Paris, France; Institut National de la Santé et de la Recherche Médicale (INSERM) U1016, Paris, France
| | - Fabien Le Grand
- Institut Cochin, Université Paris-Descartes, Centre National de la Recherche Scientifique (CNRS) UMR8104, Paris, France; Institut National de la Santé et de la Recherche Médicale (INSERM) U1016, Paris, France
| | - Slimane Ait-Si-Ali
- Centre National de la Recherche Scientifique CNRS-Université Paris Diderot, Sorbonne Paris Cité, Epigenetics and Cell Fate UMR7216 , Paris, France
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Roche B, Arcangioli B, Martienssen RA. RNA interference is essential for cellular quiescence. Science 2016; 354:science.aah5651. [PMID: 27738016 DOI: 10.1126/science.aah5651] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2016] [Accepted: 09/27/2016] [Indexed: 12/19/2022]
Abstract
Quiescent cells play a predominant role in most organisms. Here we identify RNA interference (RNAi) as a major requirement for quiescence (G0 phase of the cell cycle) in Schizosaccharomyces pombe RNAi mutants lose viability at G0 entry and are unable to maintain long-term quiescence. We identified suppressors of G0 defects in cells lacking Dicer (dcr1Δ), which mapped to genes involved in chromosome segregation, RNA polymerase-associated factors, and heterochromatin formation. We propose a model in which RNAi promotes the release of RNA polymerase in cycling and quiescent cells: (i) RNA polymerase II release mediates heterochromatin formation at centromeres, allowing proper chromosome segregation during mitotic growth and G0 entry, and (ii) RNA polymerase I release prevents heterochromatin formation at ribosomal DNA during quiescence maintenance. Our model may account for the codependency of RNAi and histone H3 lysine 9 methylation throughout eukaryotic evolution.
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Affiliation(s)
- B Roche
- Howard Hughes Medical Institute-Gordon and Betty Moore Foundation, Cold Spring Harbor Laboratory, 1 Bungtown Road, Cold Spring Harbor, NY 11724, USA
| | - B Arcangioli
- Dynamics of the Genome Unit, Department of Genomes and Genetics, Institut Pasteur, UMR3525, 25-28 rue du Docteur Roux, Paris 75015, France
| | - R A Martienssen
- Howard Hughes Medical Institute-Gordon and Betty Moore Foundation, Cold Spring Harbor Laboratory, 1 Bungtown Road, Cold Spring Harbor, NY 11724, USA.
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Isbel L, Prokopuk L, Wu H, Daxinger L, Oey H, Spurling A, Lawther AJ, Hale MW, Whitelaw E. Wiz binds active promoters and CTCF-binding sites and is required for normal behaviour in the mouse. eLife 2016; 5. [PMID: 27410475 PMCID: PMC4977153 DOI: 10.7554/elife.15082] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2016] [Accepted: 07/09/2016] [Indexed: 12/26/2022] Open
Abstract
We previously identified Wiz in a mouse screen for epigenetic modifiers. Due to its known association with G9a/GLP, Wiz is generally considered a transcriptional repressor. Here, we provide evidence that it may also function as a transcriptional activator. Wiz levels are high in the brain, but its function and direct targets are unknown. ChIP-seq was performed in adult cerebellum and Wiz peaks were found at promoters and transcription factor CTCF binding sites. RNA-seq in Wiz mutant mice identified genes differentially regulated in adult cerebellum and embryonic brain. In embryonic brain most decreased in expression and included clustered protocadherin genes. These also decreased in adult cerebellum and showed strong Wiz ChIP-seq enrichment. Because a precise pattern of protocadherin gene expression is required for neuronal development, behavioural tests were carried out on mutant mice, revealing an anxiety-like phenotype. This is the first evidence of a role for Wiz in neural function. DOI:http://dx.doi.org/10.7554/eLife.15082.001
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Affiliation(s)
- Luke Isbel
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, Melbourne, Australia
| | - Lexie Prokopuk
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, Melbourne, Australia
| | - Haoyu Wu
- Department of Human Genetics, Leiden University Medical Centre, Leiden, The Netherlands
| | - Lucia Daxinger
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, Melbourne, Australia.,Department of Human Genetics, Leiden University Medical Centre, Leiden, The Netherlands
| | - Harald Oey
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, Melbourne, Australia
| | - Alex Spurling
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, Melbourne, Australia
| | - Adam J Lawther
- Department of Psychology and Counselling, La Trobe University, Melbourne, Australia.,School of Psychology and Public Health, La Trobe University, Melbourne, Australia
| | - Matthew W Hale
- Department of Psychology and Counselling, La Trobe University, Melbourne, Australia.,School of Psychology and Public Health, La Trobe University, Melbourne, Australia
| | - Emma Whitelaw
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, Melbourne, Australia
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Abstract
Heterochromatin is the transcriptionally repressed portion of eukaryotic chromatin that maintains a condensed appearance throughout the cell cycle. At sites of ribosomal DNA (rDNA) heterochromatin, epigenetic states contribute to gene silencing and genome stability, which are required for proper chromosome segregation and a normal life span. Here, we focus on recent advances in the epigenetic regulation of rDNA silencing in Saccharomyces cerevisiae and in mammals, including regulation by several histone modifications and several protein components associated with the inner nuclear membrane within the nucleolus. Finally, we discuss the perturbations of rDNA epigenetic pathways in regulating cellular aging and in causing various types of diseases.
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43
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Ribosomal RNA Genes in the Protozoan Parasite Leishmania major Possess a Nucleosomal Structure. Protist 2016; 167:121-35. [PMID: 26963795 DOI: 10.1016/j.protis.2016.02.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2015] [Revised: 12/14/2015] [Accepted: 02/03/2016] [Indexed: 01/07/2023]
Abstract
Little is known about nucleosome structure and epigenetic regulation of transcription of rRNA genes in early-branched eukaryotes. Here we analyze the chromatin architecture and distribution of some histone modifications in the rRNA genes in the parasitic protozoon Leishmania major. Southern blots of MNase-partially-digested chromatin with DNA probes spanning the whole rRNA gene repeat showed that the intergenic spacer presents a tight nucleosomal structure, whereas the promoter region is practically devoid of nucleosomes. Intermediate levels of nucleosomes were found in the rRNA coding regions. ChIP assays allowed us to determine that H3K14ac, H3K23ac and H3K27ac, epigenetics marks that are generally associated with activation of transcription, are enriched in the promoter region. In contrast, H4K20me3, which is generally related to transcriptional silencing, was absent from the promoter region and intergenic spacer and enriched in the coding region. Interestingly, the distribution pattern for H3K9me3, generally linked to heterochromatin formation, was very similar to the distribution observed with the euchromatin marks, suggesting that this modification could be involved in transcriptional activation of rRNA genes in L. major.
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44
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Abstract
Nucleoli are formed on the basis of ribosomal genes coding for RNAs of ribosomal particles, but also include a great variety of other DNA regions. In this article, we discuss the characteristics of ribosomal DNA: the structure of the rDNA locus, complex organization and functions of the intergenic spacer, multiplicity of gene copies in one cell, selective silencing of genes and whole gene clusters, relation to components of nucleolar ultrastructure, specific problems associated with replication. We also review current data on the role of non-ribosomal DNA in the organization and function of nucleoli. Finally, we discuss probable causes preventing efficient visualization of DNA in nucleoli.
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45
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He J, Zhu Q, Wani G, Sharma N, Wani AA. Valosin-containing Protein (VCP)/p97 Segregase Mediates Proteolytic Processing of Cockayne Syndrome Group B (CSB) in Damaged Chromatin. J Biol Chem 2016; 291:7396-408. [PMID: 26826127 DOI: 10.1074/jbc.m115.705350] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2015] [Indexed: 11/06/2022] Open
Abstract
Cockayne syndrome group A and B (CSB) proteins act in transcription-coupled repair, a subpathway of nucleotide excision repair. Here we demonstrate that valosin-containing protein (VCP)/p97 segregase functions in ultraviolet radiation (UVR)-induced ubiquitin-mediated CSB degradation. We show that VCP/p97 inhibition and siRNA-mediated ablation of VCP/p97 and its cofactors UFD1 and UBXD7 impair CSB degradation. VCP/p97 inhibition also results in the accumulation of CSB in chromatin. Moreover, VCP/p97 interacts with both native and ubiquitin-conjugated forms of CSB. The localized cellular UVR exposures lead to VCP/p97 accumulation at DNA damage spots, forming distinct UVR-induced foci. However, manifestation of VCP/p97 foci is independent of CSB and UBXD7. Furthermore, VCP/p97 and UBXD7 associate with the Cockayne syndrome group A-DDB1-Cul4A complex, an E3 ligase responsible for CSB ubiquitination. Compromising proteasome and VCP/p97 function allows accumulation of both native and ubiquitinated CSB and results in an increase of UBXD7, proteasomal RPN2, and Sug1 in the chromatin compartment. Surprisingly, both biochemical inhibition and genetic defect of VCP/p97 enhance the recovery of RNA synthesis following UVR, whereas both VCP/p97 and proteasome inhibitions decrease cell viability. Our findings reveal a new role of VCP/p97 segregase in the timely processing of ubiquitinated CSB from damaged chromatin.
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Affiliation(s)
| | | | | | | | - Altaf A Wani
- From the Departments of Radiology and Molecular and Cellular Biochemistry and James Cancer Hospital and Solove Research Institute, Ohio State University, Columbus, Ohio 43210
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46
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Bártová E, Večeřa J, Krejčí J, Legartová S, Pacherník J, Kozubek S. The level and distribution pattern of HP1β in the embryonic brain correspond to those of H3K9me1/me2 but not of H3K9me3. Histochem Cell Biol 2016; 145:447-61. [PMID: 26794325 DOI: 10.1007/s00418-015-1402-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/28/2015] [Indexed: 01/13/2023]
Abstract
We studied the histone signature of embryonic and adult brains to strengthen existing evidence of the importance of the histone code in mouse brain development. We analyzed the levels and distribution patterns of H3K9me1, H3K9me2, H3K9me3, and HP1β in both embryonic and adult brains. Western blotting showed that during mouse brain development, the levels of H3K9me1, H3K9me2, and HP1β exhibited almost identical trends, with the highest protein levels occurring at E15 stage. These trends differed from the relatively stable level of H3K9me3 at developmental stages E8, E13, E15, and E18. Compared with embryonic brains, adult brains were characterized by very low levels of H3K9me1/me2/me3 and HP1β. Manipulation of the embryonic epigenome through histone deacetylase inhibitor treatment did not affect the distribution patterns of the studied histone markers in embryonic ventricular ependyma. Similarly, Hdac3 depletion in adult animals had no effect on histone methylation in the adult hippocampus. Our results indicate that the distribution of HP1β in the embryonic mouse brain is related to that of H3K9me1/me2 but not to that of H3K9me3. The unique status of H3K9me3 in the brain was confirmed by its pronounced accumulation in the granular layer of the adult olfactory bulb. Moreover, among the studied proteins, H3K9me3 was the only posttranslational histone modification that was highly abundant at clusters of centromeric heterochromatin, called chromocenters. When we focused on the hippocampus, we found this region to be rich in H3K9me1 and H3K9me3, whereas H3K9me2 and HP1β were present at a very low level or even absent in the hippocampal blade. Taken together, these results revealed differences in the epigenome of the embryonic and adult mouse brain and showed that the adult hippocampus, the granular layer of the adult olfactory bulb, and the ventricular ependyma of the embryonic brain are colonized by specific epigenetic marks.
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Affiliation(s)
- Eva Bártová
- Institute of Biophysics, Academy of Sciences of the Czech Republic, v.v.i., Královopolská 135, 612 65, Brno, Czech Republic.
| | - Josef Večeřa
- Department of Experimental Biology, Faculty of Science, Masaryk University, Kamenice 753/5, Brno, Czech Republic
| | - Jana Krejčí
- Institute of Biophysics, Academy of Sciences of the Czech Republic, v.v.i., Královopolská 135, 612 65, Brno, Czech Republic
| | - Soňa Legartová
- Institute of Biophysics, Academy of Sciences of the Czech Republic, v.v.i., Královopolská 135, 612 65, Brno, Czech Republic
| | - Jiří Pacherník
- Department of Experimental Biology, Faculty of Science, Masaryk University, Kamenice 753/5, Brno, Czech Republic
| | - Stanislav Kozubek
- Institute of Biophysics, Academy of Sciences of the Czech Republic, v.v.i., Královopolská 135, 612 65, Brno, Czech Republic
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47
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Analysis of histone modifications at human ribosomal DNA in liver cancer cell. Sci Rep 2015; 5:18100. [PMID: 26657029 PMCID: PMC4676023 DOI: 10.1038/srep18100] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2015] [Accepted: 11/11/2015] [Indexed: 01/25/2023] Open
Abstract
Human liver cancer is the cancer commonly seen clinically. The transcription of ribosomal DNA (rDNA) is a critical step for cells, and epigenetic marks such as post-translational histone modifications have been involved in the regulation of rDNA transcription. But less is known about the pathogenesis of the liver cancers concerning the rDNA transcription regulation. Here we aligned the ChIP-seq data of histone modification markers and CTCF to the human genome assembly which contains a single rDNA repeat in human liver cancer cell and validated their distribution with ChIP-QPCR. Human liver cancer cell possesses a higher enrichment of H3K4me1 and H3K27me3 at ~28 kb within the intergenic spacer (IGS) of rDNA and a higher enrichment of H3K4me3 and H3K27ac upstream of TSS. Furtherly, we studied whether UBF could affect histone modification markers and CTCF at rDNA in human liver cancer cell. UBF depletion leads to a decrease of gene activation mark H3K4me3 across the rDNA promoter. And other histone modification marks and CTCF were not altered after UBF depletion. Taken together, our data showed a high resolution map of histone modification marks at rDNA in human liver cancer cell and provide novel evidence to decipher chromatin-mediated regulation of rDNA in liver cancer.
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48
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Simon JM, Parker JS, Liu F, Rothbart SB, Ait-Si-Ali S, Strahl BD, Jin J, Davis IJ, Mosley AL, Pattenden SG. A Role for Widely Interspaced Zinc Finger (WIZ) in Retention of the G9a Methyltransferase on Chromatin. J Biol Chem 2015; 290:26088-102. [PMID: 26338712 PMCID: PMC4646261 DOI: 10.1074/jbc.m115.654459] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2015] [Revised: 08/23/2015] [Indexed: 11/06/2022] Open
Abstract
G9a and GLP lysine methyltransferases form a heterodimeric complex that is responsible for the majority of histone H3 lysine 9 mono- and di-methylation (H3K9me1/me2). Widely interspaced zinc finger (WIZ) associates with the G9a-GLP protein complex, but its role in mediating lysine methylation is poorly defined. Here, we show that WIZ regulates global H3K9me2 levels by facilitating the interaction of G9a with chromatin. Disrupting the association of G9a-GLP with chromatin by depleting WIZ resulted in altered gene expression and protein-protein interactions that were distinguishable from that of small molecule-based inhibition of G9a/GLP, supporting discrete functions of the G9a-GLP-WIZ chromatin complex in addition to H3K9me2 methylation.
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Affiliation(s)
- Jeremy M Simon
- From the Carolina Institute for Developmental Disabilities, Department of Cell Biology and Physiology, and the Department of Genetics, Curriculum in Bioinformatics and Computational Biology, Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - Joel S Parker
- the Department of Genetics and the Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - Feng Liu
- the Center for Integrative Chemical Biology and Drug Discovery, Eshelman School of Pharmacy, University of North Carolina, Chapel Hill, Chapel Hill, North Carolina 27599
| | - Scott B Rothbart
- the Center for Epigenetics, Van Andel Research Institute, Grand Rapids, Michigan 49503
| | - Slimane Ait-Si-Ali
- the Laboratoire Epigénétique et Destin Cellulaire, UMR7216, CNRS, Université Paris Diderot, Sorbonne Paris Cité, 75013 Paris, France
| | - Brian D Strahl
- the Lineberger Comprehensive Cancer Center, the Curriculum in Genetics and Molecular Biology, and the Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - Jian Jin
- the Department of Structural and Chemical Biology, the Department of Oncological Sciences, and the Department of Pharmacology and Systems Therapeutics, Icahn School of Medicine at Mount Sinai, New York, New York 10029
| | - Ian J Davis
- the Department of Genetics, the Lineberger Comprehensive Cancer Center, the Department of Pediatrics, and the Carolina Center for Genome Sciences, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, and
| | - Amber L Mosley
- the Department of Biochemistry and Molecular Biology and the Center for Computational Biology and Bioinformatics, Indiana University School of Medicine, Indianapolis, Indiana 46202
| | - Samantha G Pattenden
- the Center for Integrative Chemical Biology and Drug Discovery, Eshelman School of Pharmacy, University of North Carolina, Chapel Hill, Chapel Hill, North Carolina 27599,
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49
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Sorokin DV, Stixová L, Sehnalová P, Legartová S, Suchánková J, Šimara P, Kozubek S, Matula P, Skalníková M, Raška I, Bártová E. Localized movement and morphology of UBF1-positive nucleolar regions are changed by γ-irradiation in G2 phase of the cell cycle. Nucleus 2015. [PMID: 26208041 DOI: 10.1080/19491034.2015.1075111] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
Abstract
The nucleolus is a well-organized site of ribosomal gene transcription. Moreover, many DNA repair pathway proteins, including ATM, ATR kinases, MRE11, PARP1 and Ku70/80, localize to the nucleolus (Moore et al., 2011 ). We analyzed the consequences of DNA damage in nucleoli following ultraviolet A (UVA), C (UVC), or γ-irradiation in order to test whether and how radiation-mediated genome injury affects local motion and morphology of nucleoli. Because exposure to radiation sources can induce changes in the pattern of UBF1-positive nucleolar regions, we visualized nucleoli in living cells by GFP-UBF1 expression for subsequent morphological analyses and local motion studies. UVA radiation, but not 5 Gy of γ-rays, induced apoptosis as analyzed by an advanced computational method. In non-apoptotic cells, we observed that γ-radiation caused nucleolar re-positioning over time and changed several morphological parameters, including the size of the nucleolus and the area of individual UBF1-positive foci. Radiation-induced nucleoli re-arrangement was observed particularly in G2 phase of the cell cycle, indicating repair of ribosomal genes in G2 phase and implying that nucleoli are less stable, thus sensitive to radiation, in G2 phase.
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Affiliation(s)
- Dmitry V Sorokin
- a Institute of Biophysics ; Academy of Sciences of the Czech Republic ; Brno , Czech Republic
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50
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Nicolai S, Filippi S, Caputo M, Cipak L, Gregan J, Ammerer G, Frontini M, Willems D, Prantera G, Balajee AS, Proietti-De-Santis L. Identification of Novel Proteins Co-Purifying with Cockayne Syndrome Group B (CSB) Reveals Potential Roles for CSB in RNA Metabolism and Chromatin Dynamics. PLoS One 2015; 10:e0128558. [PMID: 26030138 PMCID: PMC4451243 DOI: 10.1371/journal.pone.0128558] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2012] [Accepted: 04/29/2015] [Indexed: 01/19/2023] Open
Abstract
The CSB protein, a member of the SWI/SNF ATP dependent chromatin remodeling family of proteins, plays a role in a sub-pathway of nucleotide excision repair (NER) known as transcription coupled repair (TCR). CSB is frequently mutated in Cockayne syndrome group B, a segmental progeroid human autosomal recessive disease characterized by growth failure and degeneration of multiple organs. Though initially classified as a DNA repair protein, recent studies have demonstrated that the loss of CSB results in pleiotropic effects. Identification of novel proteins belonging to the CSB interactome may be useful not only for predicting the molecular basis for diverse pathological symptoms of CS-B patients but also for unraveling the functions of CSB in addition to its authentic role in DNA repair. In this study, we performed tandem affinity purification (TAP) technology coupled with mass spectrometry and co-immunoprecipitation studies to identify and characterize the proteins that potentially interact with CSB-TAP. Our approach revealed 33 proteins that were not previously known to interact with CSB. These newly identified proteins indicate potential roles for CSB in RNA metabolism involving repression and activation of transcription process and in the maintenance of chromatin dynamics and integrity.
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Affiliation(s)
- Serena Nicolai
- Unit of Molecular Genetics of Aging, Department of Ecology and Biology, University of Tuscia, 01100, Viterbo, Italy
| | - Silvia Filippi
- Unit of Molecular Genetics of Aging, Department of Ecology and Biology, University of Tuscia, 01100, Viterbo, Italy
| | - Manuela Caputo
- Unit of Molecular Genetics of Aging, Department of Ecology and Biology, University of Tuscia, 01100, Viterbo, Italy
| | - Lubos Cipak
- Cancer Research Institute, Slovak Academy of Sciences, Bratislava, Slovak Republic
| | - Juraj Gregan
- Department of Genetics, Comenius University in Bratislava, Slovakia
| | - Gustav Ammerer
- Department of Biochemistry, Mass Spectrometry Facility, Max F. Perutz Laboratories, University of Vienna, Vienna, Austria
| | - Mattia Frontini
- Department of Haematology, University of Cambridge, CB2 0PT, Cambridge, United Kingdom
| | - Daniela Willems
- Unit of Molecular Genetics of Aging, Department of Ecology and Biology, University of Tuscia, 01100, Viterbo, Italy
| | - Giorgio Prantera
- Unit of Molecular Genetics of Aging, Department of Ecology and Biology, University of Tuscia, 01100, Viterbo, Italy
| | - Adayabalam S. Balajee
- Center for Radiological Research, Department of Radiation Oncology, Columbia University Medical Center, New York, New York, 10032, United States of America
| | - Luca Proietti-De-Santis
- Unit of Molecular Genetics of Aging, Department of Ecology and Biology, University of Tuscia, 01100, Viterbo, Italy
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